title: Special representations of Weyl groups: a positivity property

abstract:
  We show that the irreducible representation of the asymptotic Hecke algebra
corresponding to a special representation of a Weyl group admits a basis with
strong positivity properties.


title:
All orders results for self-crossing Wilson loops mimicking double
  parton scattering

abstract:
  Loop-level scattering amplitudes for massless particles have singularities in
regions where tree amplitudes are perfectly smooth. For example, a $2\to4$
gluon scattering process has a singularity in which each incoming gluon splits
into a pair of gluons, followed by a pair of $2\to2$ collisions between the
gluon pairs. This singularity mimics double parton scattering because it occurs
when the transverse momentum of a pair of outgoing gluons vanishes. The
singularity is logarithmic at fixed order in perturbation theory. We exploit
the duality between scattering amplitudes and polygonal Wilson loops to study
six-point amplitudes in this limit to high loop order in planar ${\cal N}=4$
super-Yang-Mills theory. The singular configuration corresponds to the limit in
which a hexagonal Wilson loop develops a self-crossing. The singular terms are
governed by an evolution equation, in which the hexagon mixes into a pair of
boxes; the mixing back is suppressed in the planar (large $N_c$) limit. Because
the kinematic dependence of the box Wilson loops is dictated by (dual)
conformal invariance, the complete kinematic dependence of the singular terms
for the self-crossing hexagon on the one nonsingular variable is determined to
all loop orders. The complete logarithmic dependence on the singular variable
can be obtained through nine loops, up to a couple of constants, using a
correspondence with the multi-Regge limit. As a byproduct, we obtain a simple
formula for the leading logs to all loop orders. We also show that, although
the MHV six-gluon amplitude is singular, remarkably, the transcendental
functions entering the non-MHV amplitude are finite in the same limit, at least
through four loops.


title:
A New Algorithm to Simulate the First Exit Times of a Vector of Brownian
  Motions, with an Application to Finance

abstract:
  We provide a new methodology to simulate the first exit times of a vector of
Brownian motions from an orthant. This new approach can be used to simulate the
first exit times of dimension higher than two. When at least one Brownian
motion has non-zero drift, the joint density function of the first exit times
in N dimensions needs to be known, or approximated. However, when the drifts
are all zero, a simpler simulation algorithm is obtained without using the
joint density function.


title:
Large-scale magnetic fields can explain the baryon asymmetry of the
  Universe

abstract:
  Helical hypermagnetic fields in the primordial Universe can produce the
observed amount of baryon asymmetry through the chiral anomaly without any
ingredients beyond the standard model of particle physics. While they generate
no $B-L$ asymmetry, the generated baryon asymmetry survives the spharelon
washout effect, because the generating process remains active until the
electroweak phase transition. Solving the Boltzmann equation numerically and
finding an attractor solution, we show that the baryon asymmetry of our
Universe can be explained, if the present large-scale magnetic fields indicated
by the blazar observations have a negative helicity and existed in the early
Universe before the electroweak phase transition. We also derive the upper
bound on the strength of the helical magnetic field, which is tighter than the
cosmic microwave background constraint, to avoid the overproduction of baryon
asymmetry.


title: The integrality conjecture and the cohomology of preprojective stacks

abstract:
  We study the Borel-Moore homology of stacks of representations of
preprojective algebras $\Pi_Q$, via the study of the DT theory of the
undeformed 3-Calabi-Yau completion $\Pi_Q[x]$. Via a result on the supports of
the BPS sheaves for $\Pi_Q[x]$-mod, we prove purity of the BPS cohomology for
the stack of $\Pi_Q[x]$-modules, and define BPS sheaves for stacks of
$\Pi_Q$-modules. These are mixed Hodge modules on the coarse moduli space of
$\Pi_Q$-modules that control the Borel-Moore homology and geometric
representation theory associated to these stacks. We show that the
hypercohomology of these objects is pure, and thus that the Borel-Moore
homology of stacks of $\Pi_Q$-modules is also pure.
  We transport the cohomological wall-crossing and integrality theorems from DT
theory to the category of $\Pi_Q$-modules. Among these and other applications,
we use our results to prove positivity of a number of "restricted" Kac
polynomials, determine the critical cohomology of
$\mathrm{Hilb}_n(\mathbb{A}^3)$, and the Borel-Moore homology of genus one
character stacks, as well as various applications to the cohomological Hall
algebras associated to Borel-Moore homology of stacks of preprojective
algebras, including the PBW theorem, and torsion-freeness.


title: Motion Of Level Set By General Curvature

abstract:
  In this paper, we study the motion of level sets by general curvature. The
difficulty of this setting is that a general curvature function is only well
defined in an admissible cone. In order to extend the existence of a weak
solution of a general curvature flow to outside the cone we introduce a new
approximation function $\hat{f}^n$ (see (3.1)). Moreover, using the idea in
[4], we give an elliptic approach for the Ben-Andrews' non-collapsing result in
fully nonlinear curvature flows; we hope this approach can be generalized to a
wider class of elliptic equations.


title:
Configuration Dependence of Band Gap Narrowing and Localization in
  Dilute GaAs_{1-x} Bi_x Alloys

abstract:
  Anion substitution with bismuth (Bi) in III-V semiconductors is an effective
method for experimental engineering of the band gap Eg at low Bi
concentrations, in particular in gallium arsenide (GaAs). The inverse
Bi-concentration dependence of Eg has been found to be linear at low
concentrations x and dominated by a valence band-defect level anticrossing
between As and Bi occupied p levels. This dependence breaks down at high
concentrations where empirical models accounting only for the As-Bi interaction
are not applicable. Predictive models for the valence band hybridization
require a first-principle understanding which can be obtained by density
functional theory with the main challenges being the proper description of Eg
and the spin-orbit coupling. By using an efficient method to include these
effects, it is shown here that at high concentrations Eg is modified mainly by
a Bi-Bi p orbital interaction and by the large Bi atom-induced strain. This
points to the role of different atomic configurations obtained by varying the
experimental growth conditions in engineering arsenide band gaps, in particular
for telecommunication laser technology.


title: $w=-1$ as an Attractor

abstract:
  It has recently been shown, in flat Robertson-Walker geometries, that the
dynamics of gravitational actions which are minimally coupled to matter fields
leads to the appearance of "attractors" - sets of physical observables on which
phase space measures become peaked. These attractors will be examined in the
context of inhomogeneous perturbations about the FRW background and in the
context of anisotropic Bianchi I systems. We show that maximally expanding
solutions are generically attractors, i.e. any measure based on phase-space
observables becomes sharply peaked about those solutions which have $P=-\rho$.


title:
Exchangeable Random Measures for Sparse and Modular Graphs with
  Overlapping Communities

abstract:
  We propose a novel statistical model for sparse networks with overlapping
community structure. The model is based on representing the graph as an
exchangeable point process, and naturally generalizes existing probabilistic
models with overlapping block-structure to the sparse regime. Our construction
builds on vectors of completely random measures, and has interpretable
parameters, each node being assigned a vector representing its level of
affiliation to some latent communities. We develop methods for simulating this
class of random graphs, as well as to perform posterior inference. We show that
the proposed approach can recover interpretable structure from two real-world
networks and can handle graphs with thousands of nodes and tens of thousands of
edges.


title: DHIGLS: DRAO H I Intermediate Galactic Latitude Survey

abstract:
  Observations of Galactic H I gas for seven targeted regions at intermediate
Galactic latitude are presented at 1' angular resolution using data from the
DRAO Synthesis Telescope (ST) and the Green Bank Telescope (GBT). The DHIGLS
data are the most extensive arcminute resolution measurements of the diffuse
atomic interstellar medium beyond those in the Galactic plane. The acquisition,
reduction, calibration, and mosaicking of the DRAO ST data and the cross
calibration and incorporation of the short-spacing information from the GBT are
described. The high quality of the resulting DHIGLS products enables a variety
of new studies in directions of low Galactic column density. We analyze the
angular power spectra of maps of the integrated H I emission (column density)
from the data cubes for several distinct velocity ranges. Fitting power
spectrum models based on a power law, but including the effects of the
synthesized beam and noise at high spatial frequencies, we find exponents
ranging from -2.5 to -3.0.. Power spectra of maps of the centroid velocity for
these components give similar results. These exponents are interpreted as being
representative of the 3D density and 3D velocity fields of the atomic gas,
respectively. We find evidence for dramatic changes in the H I structures in
channel maps over even small changes in velocity. This narrow line emission has
counterparts in absorption spectra against bright background radio sources,
quantifying that the gas is cold and dense and can be identified as the cold
neutral medium phase. Fully reduced DHIGLS H I data cubes and other data
products are available at www.cita.utoronto.ca/DHIGLS.


title: A note on the subadditivity of Syzygies

abstract:
  Let $R=S/I$ be a graded algebra with $t_i$ and $T_i$ being the minimal and
maximal shifts in the minimal $S$ resolution of $R$ at degree $i$. In this
paper we prove that $t_n\leq t_1+T_{n-1}$, for all $n$ and as a consequence, we
show that for Gorenstein algebras of codimension $h$, the subadditivity of
maximal shifts $T_i$ in the minimal resolution holds for $i \geq h-1$, i.e, we
show that $T_i \leq T_a+T_{i-a}$ for $i\geq h-1$.


title:
Evaluating consistency of deterministic streamline tractography in
  non-linearly warped DTI data

abstract:
  Tractography is typically performed for each subject using the diffusion
tensor imaging (DTI) data in its native subject space rather than in some space
common to the entire study cohort. Despite performing tractography on a
population average in a normalized space, the latter is considered less
favorably at the \emph{individual} subject level because it requires spatial
transformations of DTI data that involve non-linear warping and reorientation
of the tensors. Although the commonly used reorientation strategies such as
finite strain and preservation of principle direction are expected to result in
adequate accuracy for voxel based analyses of DTI measures such as fractional
anisotropy (FA), mean diffusivity (MD), the reorientations are not always exact
except in the case of rigid transformations. Small imperfections in
reorientation at individual voxel level accumulate and could potentially affect
the tractography results adversely. This study aims to evaluate and compare
deterministic white matter fiber tracking in non-linearly warped DTI against
that in native DTI. The data present promising evidence that tractography in
non-linear warped DTI data could indeed be a viable and valid option for
various statistical analysis of DTI data in a spatially normalized space.


title:
Existence of global solutions to the derivative NLS equation with the
  inverse scattering transform method

abstract:
  We address existence of global solutions to the derivative nonlinear
Schr\"{o}dinger (DNLS) equation without the small-norm assumption. By using the
inverse scattering transform method without eigenvalues and resonances, we
construct a unique global solution in $H^2(\mathbb{R}) \cap
H^{1,1}(\mathbb{R})$ which is also Lipschitz continuous with respect to the
initial data. Compared to the existing literature on the spectral problem for
the DNLS equation, the corresponding Riemann--Hilbert problem is defined in the
complex plane with the jump on the real line.


title:
Tracing the Chromospheric and Coronal Magnetic Field with AIA, IRIS,
  IBIS, and ROSA Data

abstract:
  The aim of this study is to explore the suitability of chromospheric images
for magnetic modeling of active regions. We use high-resolution images (0.1")
from the Interferometric Bidimensional Spectrometer (IBIS) in the Ca II 8542 A
line, the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument in the
H-alpha 6563 A line, the Interface Region Imaging Spectrograph (IRIS) in the
2796 A line, and compare non-potential magnetic field models obtained from
those chromospheric images with those obtained from images of the Atmospheric
Imaging Assembly (AIA) in coronal (171 A, etc.) and in chromospheric (304 A)
wavelengths. Curvi-linear structures are automatically traced in those images
with the OCCULT-2 code, to which we forward-fitted magnetic field lines
computed with the Vertical-Current Approximation Non-Linear Force Free Field
(VCA-NLFFF) code. We find that the chromospheric images: (1) reveal crisp
curvi-linear structures (fibrils, loop segments, spicules) that are extremely
well-suited for constraining magnetic modeling; (2) that these curvi-linear
structures are field-aligned with the best-fit solution by a median
misalignment angle of ~4-7 deg; (3) the free energy computed from coronal data
may underestimate that obtained from cromospheric data by a factor of ~ 2-4,
(4) the height range of chromospheric features is confined to h ~ 4000$ km,
while coronal features are detected up to h ~ 35,000$ km; and (5) the
plasma-beta parameter is beta ~ 10^(-5)-10^(-1) for all traced features. We
conclude that chromospheric images reveal important magnetic structures that
are complementary to coronal images and need to be included in comprehensive
magnetic field models, a quest that is not accomodated in standard NLFFF codes.


title: Parallel Ordered Sets Using Join

abstract:
  The ordered set is one of the most important data type in both theoretical
algorithm design and analysis and practical programming. In this paper we study
the set operations on two ordered sets, including Union, Intersect and
Difference, based on four types of balanced Binary Search Trees (BST) including
AVL trees, red-black trees, weight balanced trees and treaps. We introduced
only one subroutine Join that needs to be implemented differently for each
balanced BST, and on top of which we can implement generic, simple and
efficient parallel functions for ordered sets. We first prove the
work-efficiency of these Join-based set functions using a generic proof working
for all the four types of balanced BSTs.
  We also implemented and tested our algorithm on all the four balancing
schemes. Interestingly the implementations on all four data structures and
three set functions perform similarly in time and speedup (more than 45x on 64
cores). We also compare the performance of our implementation to other existing
libraries and algorithms.


title:
Accuracy requirements to test the applicability of the random cascade
  model to supersonic turbulence

abstract:
  A model, which is widely used for inertial rang statistics of supersonic
turbulence in the context of molecular clouds and star formation, expresses
(measurable) relative scaling exponents Z_p of two-point velocity statistics as
a function of two parameters, beta and Delta. The model relates them to the
dimension D of the most dissipative structures, D=3-Delta/(1-beta). While this
description has proved most successful for incompressible turbulence
(beta=Delta=2/3, and D=1), its applicability in the highly compressible regime
remains debated. For this regime, theoretical arguments suggest D=2 and
Delta=2/3, or Delta=1. Best estimates based on 3D periodic box simulations of
supersonic isothermal turbulence yield Delta=0.71 and D=1.9, with uncertainty
ranges of Delta in [0.67, 0.78] and D in [2.04,1.60]. With these 5-10\%
uncertainty ranges just marginally including the theoretical values of
Delta=2/3 and D=2, doubts remain whether the model indeed applies and, if it
applies, for what values of beta and Delta. We use a Monte Carlo approach to
mimic actual simulation data and examine what factors are most relevant for the
fit quality. We estimate that 0.1% (0.05%) accurate Z_p, with p=1...5, should
allow for 2% (1%) accurate estimates of beta and Delta in the highly
compressible regime, but not in the mildly compressible regime. We argue that
simulation-based Z_p with such accuracy are within reach of today's computer
resources. If this kind of data does not allow for the expected high quality
fit of beta and Delta, then this may indicate the inapplicability of the model
for the simulation data. In fact, other models than the one we examine here
have been suggested.


title:
Electrically-Pumped Wavelength-Tunable GaAs Quantum Dots Interfaced with
  Rubidium Atoms

abstract:
  We demonstrate the first wavelength-tunable electrically-pumped source of
non-classical light that can emit photons with wavelength in resonance with the
D2 transitions of 87Rb atoms. The device is fabricated by integrating a novel
GaAs single-quantum-dot light-emitting-diode (LED) onto a piezoelectric
actuator. By feeding the emitted photons into a 75-mm-long cell containing warm
87Rb atom vapor, we observe slow-light with a temporal delay of up to 3.4 ns.
In view of the possibility of using 87Rb atomic vapors as quantum memories,
this work makes an important step towards the realization of hybrid-quantum
systems for future quantum networks.


title: Sequence Classification with Neural Conditional Random Fields

abstract:
  The proliferation of sensor devices monitoring human activity generates
voluminous amount of temporal sequences needing to be interpreted and
categorized. Moreover, complex behavior detection requires the personalization
of multi-sensor fusion algorithms. Conditional random fields (CRFs) are
commonly used in structured prediction tasks such as part-of-speech tagging in
natural language processing. Conditional probabilities guide the choice of each
tag/label in the sequence conflating the structured prediction task with the
sequence classification task where different models provide different
categorization of the same sequence. The claim of this paper is that CRF models
also provide discriminative models to distinguish between types of sequence
regardless of the accuracy of the labels obtained if we calibrate the class
membership estimate of the sequence. We introduce and compare different neural
network based linear-chain CRFs and we present experiments on two complex
sequence classification and structured prediction tasks to support this claim.


title:
A sparse grid discontinuous Galerkin method for high-dimensional
  transport equations and its application to kinetic simulations

abstract:
  In this paper, we develop a sparse grid discontinuous Galerkin (DG) scheme
for transport equations and applied it to kinetic simulations. The method uses
the weak formulations of traditional Runge-Kutta DG (RKDG) schemes for
hyperbolic problems and is proven to be $L^2$ stable and convergent. A major
advantage of the scheme lies in its low computational and storage cost due to
the employed sparse finite element approximation space. This attractive feature
is explored in simulating Vlasov and Boltzmann transport equations. Good
performance in accuracy and conservation is verified by numerical tests in up
to four dimensions.


title: Tuner control system of spoke012 SRF cavity for C-ADS injector I at IHEP

abstract:
  A new tuner control system of spoke superconducting radio frequency (SRF)
cavity has been developed and applied to cryomodule I (CM1) of C-ADS injector I
at IHEP. We have successfully implemented the tuner controllerfor the first
time and achieved a cavity tuning phase error of 0.7degrees (about 4 Hz peak to
peak) in the presence of electromechanical coupled resonance. This paper will
present the preliminary experimental results based on the new tuner controller
under proton beam commissioning.


title: The Lagrange spectrum of some square-tiled surfaces

abstract:
  Lagrange spectra have been defined for closed submanifolds of the moduli
space of translation surfaces which are invariant under the action of SL(2,R).
We consider the closed orbit generated by a specific covering of degree 7 of
the standard torus, which is an element of the stratum H(2). We give an
explicit formula for the values in the spectrum, in terms of a cocycle over the
classical continued fraction. Differently from the classical case of the
modular surface, where the lowest part of the Lagrange spectrum is discrete, we
find an isolated minimum, and a set with a rich structure right above it.


title: The Cayley Grassmannian

abstract:
  We study the projective variety CG parametrizing four dimensional subalgebras
of the complex octonions, which we call the Cayley Grass-mannian. We prove that
it is a spherical G2-variety with only three orbits that we describe
explicitely. Its cohomology ring has a basis of Schubert type classes and we
determine the intersection product completely.


title:
Error estimate for time-explicit finite volume approximation of strong
  solutions to systems of conservation laws

abstract:
  We study the finite volume approximation of strong solutions to nonlinear
systems of conservation laws. We focus on time-explicit schemes on unstructured
meshes, with entropy satisfying numerical fluxes. The numerical entropy
dissipation is quantified at each interface of the mesh, which enables to prove
a weak--BV estimate for the numerical approximation under a strengthen CFL
condition. Then we derive error estimates in the multidimensional case, using
the relative entropy between the strong solution and its finite volume
approximation. The error terms are carefully studied, leading to a classical
$h^1/4$ estimate in $L^2$ under this strengthen CFL condition.


title:
A Note on the Complexity of Computing the Number of Reachable Vertices
  in a Digraph

abstract:
  In this work, we consider the following problem: given a digraph $G=(V,E)$,
for each vertex $v$, we want to compute the number of vertices reachable from
$v$. In other words, we want to compute the out-degree of each vertex in the
transitive closure of $G$. We show that this problem is not solvable in time
$\mathcal{O}\left(|E|^{2-\epsilon}\right)$ for any $\epsilon>0$, unless the
Strong Exponential Time Hypothesis is false. This result still holds if $G$ is
assumed to be acyclic.


title: Sub-cortical brain structure segmentation using F-CNN's

abstract:
  In this paper we propose a deep learning approach for segmenting sub-cortical
structures of the human brain in Magnetic Resonance (MR) image data. We draw
inspiration from a state-of-the-art Fully-Convolutional Neural Network (F-CNN)
architecture for semantic segmentation of objects in natural images, and adapt
it to our task. Unlike previous CNN-based methods that operate on image
patches, our model is applied on a full blown 2D image, without any alignment
or registration steps at testing time. We further improve segmentation results
by interpreting the CNN output as potentials of a Markov Random Field (MRF),
whose topology corresponds to a volumetric grid. Alpha-expansion is used to
perform approximate inference imposing spatial volumetric homogeneity to the
CNN priors. We compare the performance of the proposed pipeline with a similar
system using Random Forest-based priors, as well as state-of-art segmentation
algorithms, and show promising results on two different brain MRI datasets.


title:
A Clifford algebra gauge invariant Lagrangian for gravity. Part 2 :
  compatibility with General Relativity tests

abstract:
  Gauge fields associated to the Dirac matrix algebra used with the standard
quadratic gauge field Lagrangian lead to an extended gravitational Lagrangian
which includes the Einstein-Hilbert one, plus quadratic, cosmological constant
and torsion terms. This note looks at three cases : the static central
symmetric field, the isotropic expanding universe, and the asymptotic field of
a rotating body, and show that, in weak gravitational fields, there is no
contradiction with General Relativity results.


title:
A Product Integration type Method for solving Nonlinear Integral
  Equations in L

abstract:
  This paper deals with nonlinear Fredholm integral equations of the second
kind. We study the case of a weakly singular kernel and we set the problem in
the space L 1 ([a, b], C). As numerical method, we extend the product
integration scheme from C 0 ([a, b], C) to L 1 ([a, b], C).


title:
Mining Software Quality from Software Reviews: Research Trends and Open
  Issues

abstract:
  Software review text fragments have considerably valuable information about
users experience. It includes a huge set of properties including the software
quality. Opinion mining or sentiment analysis is concerned with analyzing
textual user judgments. The application of sentiment analysis on software
reviews can find a quantitative value that represents software quality.
Although many software quality methods are proposed they are considered
difficult to customize and many of them are limited. This article investigates
the application of opinion mining as an approach to extract software quality
properties. We found that the major issues of software reviews mining using
sentiment analysis are due to software lifecycle and the diverse users and
teams.


title: On an extremal problem for nonoverlapping domains *

abstract:
  The paper considers the problem of finding the range of functional I = J f (z
0), f (z 0), F ($\zeta$ 0), F ($\zeta$ 0) , defined on the class M of pairs
functions (f (z), F ($\zeta$)) that are univalent in the system of the disk and
the interior of the disk, using the method of internal variations. We establish
that the range of this functional is bounded by the curve whose equation is
written in terms of elliptic integrals, depending on the parameters of the
functional I.


title:
Parameter Insensitivity in ADMM-Preconditioned Solution of Saddle-Point
  Problems

abstract:
  We consider the solution of linear saddle-point problems, using the
alternating direction method-of-multipliers (ADMM) as a preconditioner for the
generalized minimum residual method (GMRES). We show, using theoretical bounds
and empirical results, that ADMM is made remarkably insensitive to the
parameter choice with Krylov subspace acceleration. We prove that ADMM-GMRES
can consistently converge, irrespective of the exact parameter choice, to an
$\epsilon$-accurate solution of a $\kappa$-conditioned problem in
$O(\kappa^{2/3}\log\epsilon^{-1})$ iterations. The accelerated method is
applied to randomly generated problems, as well as the Newton direction
computation for the interior-point solution of semidefinite programs in the
SDPLIB test suite. The empirical results confirm this parameter insensitivity,
and suggest a slightly improved iteration bound of
$O(\sqrt{\kappa}\log\epsilon^{-1})$.


title: Reducing Runtime by Recycling Samples

abstract:
  Contrary to the situation with stochastic gradient descent, we argue that
when using stochastic methods with variance reduction, such as SDCA, SAG or
SVRG, as well as their variants, it could be beneficial to reuse previously
used samples instead of fresh samples, even when fresh samples are available.
We demonstrate this empirically for SDCA, SAG and SVRG, studying the optimal
sample size one should use, and also uncover be-havior that suggests running
SDCA for an integer number of epochs could be wasteful.


title:
Classification methods applied to credit scoring: A systematic review
  and overall comparison

abstract:
  The need for controlling and effectively managing credit risk has led
financial institutions to excel in improving techniques designed for this
purpose, resulting in the development of various quantitative models by
financial institutions and consulting companies. Hence, the growing number of
academic studies about credit scoring shows a variety of classification methods
applied to discriminate good and bad borrowers. This paper, therefore, aims to
present a systematic literature review relating theory and application of
binary classification techniques for credit scoring financial analysis. The
general results show the use and importance of the main techniques for credit
rating, as well as some of the scientific paradigm changes throughout the
years.


title:
Periodic and Non-Periodic Solutions of a Ricker-type Second-Order
  Equation with Periodic Parameters

abstract:
  We study the dynamics of the positive solutions of a second-order,
Ricker-type exponential difference equation with periodic parameters. We find
that qualitatively different dynamics occur depending on whether the period p
of the main parameter is odd or even. If p is odd then periodic and
non-periodic solutions may coexist (with different initial values) if the
amplitude of the periodic parameter is allowed to vary over a sufficiently
large range. But if p is even then all solutions converge to an asymptotically
stable limit cycle of period p if either all the odd-indexed or all the
even-indexed terms of the periodic parameter are less than 2, and the sum of
the even terms does not equal the sum of the odd terms. The key idea in our
analysis is a semiconjugate factorization of the above equation into a
triangular system of two first-order equations.


title:
A simple method for estimating the fractal dimension from digital
  images: The compression dimension

abstract:
  The fractal structure of real world objects is often analyzed using digital
images. In this context, the compression fractal dimension is put forward. It
provides a simple method for the direct estimation of the dimension of fractals
stored as digital image files. The computational scheme can be implemented
using readily available free software. Its simplicity also makes it very
interesting for introductory elaborations of basic concepts of fractal
geometry, complexity, and information theory. A test of the computational
scheme using limited-quality images of well-defined fractal sets obtained from
the Internet and free software has been performed. Also, a systematic
evaluation of the proposed method using computer generated images of the
Weierstrass cosine function shows an accuracy comparable to those of the
methods most commonly used to estimate the dimension of fractal data sequences
applied to the same test problem.


title: Selfcomplementary quantum channels

abstract:
  Selfcomplementary quantum channels are characterized by such an interaction
between the principal quantum system and the environment that leads to the same
output states of both interacting systems. These maps can describe approximate
quantum copy machines, as perfect copying of an unknown quantum state is not
possible due to the celebrated no-cloning theorem. We provide here a
parametrization of a large class of selfcomplementary channels and analyze
their properties. Selfcomplementary channels preserve some residual coherences
and residual entanglement. Investigating some measures of non-Markovianity we
show that time evolution under selfcomplementary channels is highly
non-Markovian.


title:
Complex Squeezing and Force Measurement Beyond the Standard Quantum
  Limit

abstract:
  A continuous quantum field, such as a propagating beam of light, may be
characterized by a squeezing spectrum that is inhomogeneous in frequency. We
point out that homodyne detectors, which are commonly employed to detect
quantum squeezing, are blind to squeezing spectra in which the correlation
between amplitude and phase fluctuations is complex. We find theoretically that
such complex squeezing is a component of ponderomotive squeezing of light
through cavity optomechanics. We propose a detection scheme, called synodyne
detection, which reveals complex squeezing and allows the accounting of
measurement back-action. Even with the optomechanical system subject to
continuous measurement, such detection allows the measurement of one component
of an external force with sensitivity only limited by the mechanical
oscillator's thermal occupation.


title: Products of Differences in Prime Order Finite Fields

abstract:
  There exists an absolute constant $C$ with the following property. Let $A
\subseteq \mathbb{F}_p$ be a set in the prime order finite field with $p$
elements. Suppose that $|A| > C p^{5/8}$. The set \[ (A \pm A)(A \pm A) =
\{(a_1 \pm a_2)(a_3 \pm a_4) : a_1,a_2,a_3,a_4 \in A\} \] contains at least
$p/2$ elements.


title: Simulations of substructures in relativistic jets

abstract:
  We present a set of simulations of relativistic jets from accretion disk
initial setup with a new code in Fortran 90 to get numerical solutions of a
system of General Relativistic Magnetohydrodynamics (GRMHD) partial
differential equations in a fixed Black Hole (BH) spacetime which is able to
show substructures formations inside the jet as well as a lobe formation on the
disk. For this, a central scheme of finite volume method without dimensional
split and no Riemann solvers (a Nessyahu-Tadmor method) was implemented. Thus,
we were able to obtain stable numerical solutions with spurious oscillations
under control and no excessive numerical dissipation. We setup a magnetized
accretion disk uncharged plasma surrounding a central Schwarzschild BH immersed
in a magnetosphere which evolve to the ejection of matter in the form of jet
with its substructures over a distance of almost twenty times the BH radius.


title:
Efficient Access of Mobile Flows to Heterogeneous Networks under Flash
  Crowds

abstract:
  Future wireless networks need to offer orders of magnitude more capacity to
address the predicted growth in mobile traffic demand. Operators to enhance the
capacity of cellular networks are increasingly using WiFi to offload traffic
from their core networks. This paper deals with the efficient and flexible
management of a heterogeneous networking environment offering wireless access
to multimode terminals. This wireless access is evaluated under disruptive
usage scenarios, such as flash crowds, which can mean unwanted severe
congestion on a specific operator network whilst the remaining available
capacity from other access technologies is not being used. To address these
issues, we propose a scalable network assisted distributed solution that is
administered by centralized policies, and an embedded reputation system, by
which initially selfish operators are encouraged to cooperate under the threat
of churn. Our solution after detecting a congested technology, including within
its wired backhaul, automatically offloads and balances the flows amongst the
access resources from all the existing technologies, following some quality
metrics. Our results show that the smart integration of access networks can
yield an additional wireless quality for mobile flows up to thirty eight
percent beyond that feasible from the best effort standalone operation of each
wireless access technology. It is also evidenced that backhaul constraints are
conveniently reflected on the way the flow access to wireless media is granted.
Finally, we have analyzed the sensitivity of the handover decision algorithm
running in each terminal agent to consecutive flash crowds, as well as its
centralized feature that controls the connection quality offered by a
heterogeneous access infrastructure owned by distinct operators.


title:
Chromospheric evaporation flows and density changes deduced from
  Hinode/EIS during an M1.6 flare

abstract:
  We analyzed high-cadence sit-and-stare observations acquired with the
Hinode/EIS spectrometer and HXR measurements acquired with RHESSI during an
M-class flare. During the flare impulsive phase, we observe no significant
flows in the cooler Fe XIII line but strong upflows, up to 80-150 km/s, in the
hotter Fe XVI line. The largest Doppler shifts observed in the Fe XVI line were
co-temporal with the sharp intensity peak. The electron density obtained from a
Fe XIII line pair ratio exhibited fast increase (within two minutes) from the
pre-flare level of 5.01x10^(9) cm^(-3) to 3.16x10^(10) cm^(-3) during the flare
peak. The nonthermal energy flux density deposited from the coronal
acceleration site to the lower atmospheric layers during the flare peak was
found to be 1.34x10^(10) erg/s/cm^(2) for a low-energy cut-off that was
estimated to be 16 keV. During the decline flare phase, we found a secondary
intensity and density peak of lower amplitude that was preceded by upflows of
15 km/s that were detected in both lines. The flare was also accompanied by a
filament eruption that was partly captured by the EIS observations. We derived
Doppler velocities of 250-300 km/s for the upflowing filament material.The
spectroscopic results for the flare peak are consistent with the scenario of
explosive chromospheric evaporation, although a comparatively low value of the
nonthermal energy flux density was determined for this phase of the flare. This
outcome is discussed in the context of recent hydrodynamic simulations. It
provides observational evidence that the response of the atmospheric plasma
strongly depends on the properties of the electron beams responsible for the
heating, in particular the steepness of the energy distribution.


title: PL(M) admits no Polish group topology

abstract:
  We show that the group of piecewise linear homeomorphisms of any compact PL
manifold does not admit a Polish group topology. This uses a) new results on
the relationship between topologies on groups of homeomorphisms, their
algebraic structure, and the topology of the underlying manifold, and b) new
results on the structure of certain subgroups of PL(M). The proof also shows
that the group of piecewise projective homeomorphisms of the circle has no
Polish group topology.


title: Oriented Book Embeddings

abstract:
  A graph $G$ has a $k$-page book embedding if $G$ can be embedded into a
$k$-page book. The minimum $k$ such that $G$ has a $k$-page book embedding is
the book thickness of $G$, denoted $bt(G)$. Most of the work on this subject
has been done for unoriented graphs and oriented acyclic graphs (no directed
cycles). In this work we discuss oriented graphs $\overrightarrow{D}$
containing directed cycles by using oriented book embeddings and oriented book
thickness, $obt(\overrightarrow{D})$. To characterize $\overrightarrow{D}$ such
that $obt(\overrightarrow{D}) = k$, we define the class $\mathcal{M}^k$ of
$k$-page critical oriented graphs to be all oriented graphs
$\overrightarrow{D}$ with $obt(\overrightarrow{D}) =k$, but for every proper
oriented subgraph of $\overrightarrow{D}$, denoted $\overrightarrow{D}'$, we
have that $obt(\overrightarrow{D}') < k$. Determining $\mathcal{M}^k$ for
general $k$ is challenging; we narrow down the list of oriented graphs in
$\mathcal{M}^k$ for small $k$. In this work we show complete lists for
$\mathcal{M}^1$ and for $\mathcal{M}^2 \cap \mathcal{U}$, where $\mathcal{U}$
consists of all strictly dicyclic oriented graphs, that is, oriented graphs
containing exactly one oriented cycle, which is a directed cycle.
  Keywords: book embedding, book thickness, oriented book embedding, oriented
book thickness, directed cycle, critical graph


title:
A replay-attack resistant message authentication scheme using time-based
  keying hash functions and unique message identifiers

abstract:
  Hash-based message authentication codes are an extremely simple yet hugely
effective construction for producing keyed message digests using shared
secrets. HMACs have seen widespread use as ad-hoc digital signatures in many
Internet applications. While messages signed with an HMAC are secure against
sender impersonation and tampering in transit, if used alone they are
susceptible to replay attacks. We propose a construction that extends HMACs to
produce a keyed message digest that has a finite validity period. We then
propose a message signature scheme that uses this time-dependent MAC along with
an unique message identifier to calculate a set of authentication factors using
which a recipient can readily detect and ignore replayed messages, thus
providing perfect resistance against replay attacks. We further analyse
time-based message authentication codes and show that they provide stronger
security guarantees than plain HMACs, even when used independently of the
aforementioned replay attack resistant message signature scheme.


title:
The Fornax Deep Survey with VST. I. The extended and diffuse stellar
  halo of NGC~1399 out to 192 kpc

abstract:
  [Abrigded] We have started a new deep, multi-imaging survey of the Fornax
cluster, dubbed Fornax Deep Survey (FDS), at the VLT Survey Telescope. In this
paper we present the deep photometry inside two square degrees around the
bright galaxy NGC1399 in the core of the cluster. We found a very extended and
diffuse envelope surrounding the luminous galaxy NGC1399: we map the surface
brightness out to 33 arcmin (~ 192 kpc) from the galaxy center and down to
about 31 mag/arcsec^2 in the g band. The deep photometry allows us to detect a
faint stellar bridge in the intracluster region between NGC1399 and NGC1387. By
analyzing the integrated colors of this feature, we argue that it could be due
to the ongoing interaction between the two galaxies, where the outer envelope
of NGC1387 on its east side is stripped away. By fitting the light profile, we
found that it exists a physical break radius in the total light distribution at
R=10 arcmin (~58 kpc) that sets the transition region between the bright
central galaxy and the outer exponential stellar halo. We discuss the main
implications of this work on the build-up of the stellar halo at the center of
the Fornax cluster. By comparing with the numerical simulations of the stellar
halo formation for the most massive BCGs, we find that the observed stellar
halo mass fraction is consistent with a halo formed through the multiple
accretion of progenitors with a stellar mass in the range 10^8 - 10^11 M_sun.
This might suggest that the halo of NGC1399 has also gone through a major
merging event. The absence of a significant number of luminous stellar streams
and tidal tails out to 192 kpc suggests that the epoch of this strong
interaction goes back to an early formation epoch. Therefore, differently from
the Virgo cluster, the extended stellar halo around NGC1399 is characterised by
a more diffuse and well-mixed component, including the ICL.


title:
Noncollinear exchange interaction in transition metal dichalcogenide
  edges

abstract:
  We study the Ruderman-Kittel-Kasuya-Yosida effective exchange interaction
between magnetic impurities embedded on the edges of transition-metal
dichalcogenide flakes, using a three-orbital tight-binding model. Electronic
states lying midgap of the bulk structure have strong one-dimensional (1D)
character, localized on the edges of the crystallite. This results in exchange
interactions with $1/r$ (or slower) decay with distance $r$, similar to other
1D systems. Most interestingly, however, the strong spin-orbit interaction in
these materials results in sizable non-collinear Dzyaloshinskii-Moriya
interactions between impurities, comparable in size to the usual Ising and
in-plane components. Varying the relevant Fermi energy by doping or gating may
allow one to modulate the effective interactions, controlling the possible
helical ground state configurations of multiple impurities.


title: Exploiting the Structure: Stochastic Gradient Methods Using Raw Clusters

abstract:
  The amount of data available in the world is growing faster than our ability
to deal with it. However, if we take advantage of the internal
\emph{structure}, data may become much smaller for machine learning purposes.
In this paper we focus on one of the fundamental machine learning tasks,
empirical risk minimization (ERM), and provide faster algorithms with the help
from the clustering structure of the data.
  We introduce a simple notion of raw clustering that can be efficiently
computed from the data, and propose two algorithms based on clustering
information. Our accelerated algorithm ClusterACDM is built on a novel Haar
transformation applied to the dual space of the ERM problem, and our
variance-reduction based algorithm ClusterSVRG introduces a new gradient
estimator using clustering. Our algorithms outperform their classical
counterparts ACDM and SVRG respectively.


title:
Orthogonality of Bethe Ansatz eigenfunctions for the Laplacian on a
  hyperoctahedral Weyl alcove

abstract:
  We prove the orthogonality of the Bethe Ansatz eigenfunctions for the
Laplacian on a hyperoctahedral Weyl alcove with repulsive homogeneous Robin
boundary conditions at the walls. To this end these eigenfunctions are
retrieved as the continuum limit of an orthogonal basis of algebraic Bethe
Ansatz eigenfunctions for a finite $q$-boson system endowed with diagonal
open-end boundary interactions.


title: Widening Disparity and its Suppression in a Stochastic Replicator Model

abstract:
  Winner-take-all phenomena are observed in various competitive systems. We
find similar phenomena in replicator models with randomly fluctuating growth
rates. The disparity between winners and losers increases indefinitely, even if
all elements are statistically equivalent. A lognormal distribution describes
well the nonstationary time evolution. If a nonlinear load corresponding to
progressive taxation is introduced, a stationary distribution is obtained and
disparity widening is suppressed.


title:
Accurate halo-model matter power spectra with dark energy, massive
  neutrinos and modified gravitational forces

abstract:
  We present an accurate non-linear matter power spectrum prediction scheme for
a variety of extensions to the standard cosmological paradigm, which uses the
tuned halo model previously developed in Mead (2015b). We consider dark energy
models that are both minimally and non-minimally coupled, massive neutrinos and
modified gravitational forces with chameleon and Vainshtein screening
mechanisms. In all cases we compare halo-model power spectra to measurements
from high-resolution simulations. We show that the tuned halo model method can
predict the non-linear matter power spectrum measured from simulations of
parameterised $w(a)$ dark energy models at the few per cent level for
$k<10\,h\mathrm{Mpc}^{-1}$, and we present theoretically motivated extensions
to cover non-minimally coupled scalar fields, massive neutrinos and Vainshtein
screened modified gravity models that result in few per cent accurate power
spectra for $k<10\,h\mathrm{Mpc}^{-1}$. For chameleon screened models we
achieve only 10 per cent accuracy for the same range of scales. Finally, we use
our halo model to investigate degeneracies between different extensions to the
standard cosmological model, finding that the impact of baryonic feedback on
the non-linear matter power spectrum can be considered independently of
modified gravity or massive neutrino extensions. In contrast, considering the
impact of modified gravity and massive neutrinos independently results in
biased estimates of power at the level of 5 per cent at scales
$k>0.5\,h\mathrm{Mpc}^{-1}$. An updated version of our publicly available
HMcode can be found at https://github.com/alexander-mead/HMcode


title: The low-mass end of the baryonic Tully-Fisher relation

abstract:
  The scaling of disk galaxy rotation velocity with baryonic mass (the
"Baryonic Tully-Fisher" relation, BTF) has long confounded galaxy formation
models. It is steeper than the M ~ V^3 scaling relating halo virial masses and
circular velocities and its zero point implies that galaxies comprise a very
small fraction of available baryons. Such low galaxy formation efficiencies may
in principle be explained by winds driven by evolving stars, but the tightness
of the BTF relation argues against the substantial scatter expected from such
vigorous feedback mechanism. We use the APOSTLE/EAGLE simulations to show that
the BTF relation is well reproduced in LCDM simulations that match the size and
number of galaxies as a function of stellar mass. In such models, galaxy
rotation velocities are proportional to halo virial velocity and the steep
velocity-mass dependence results from the decline in galaxy formation
efficiency with decreasing halo mass needed to reconcile the CDM halo mass
function with the galaxy luminosity function. Despite the strong feedback, the
scatter in the simulated BTF is smaller than observed, even when considering
all simulated galaxies and not just rotationally-supported ones. The
simulations predict that the BTF should become increasingly steep at the faint
end, although the velocity scatter at fixed mass should remain small. Observed
galaxies with rotation speeds below ~40 km/s seem to deviate from this
prediction. We discuss observational biases and modeling uncertainties that may
help to explain this disagreement in the context of LCDM models of dwarf galaxy
formation.


title:
Gauge invariant theories of linear response for strongly correlated
  superconductors

abstract:
  We present a general diagrammatic theory for determining consistent
electromagnetic response functions in strongly correlated fermionic
superfluids. The general treatment of correlations beyond BCS theory requires a
new theoretical formalism not contained in the current literature. Among
concrete examples are a rather extensive class of theoretical models which
incorporate BCS-BEC crossover as applied to the ultra cold Fermi gases, along
with theories specifically associated with the high-$T_c$ cuprates. The
challenge is to maintain gauge invariance, while simultaneously incorporating
additional self-energy terms arising from strong correlation effects. Central
to our approach is the application of the Ward-Takahashi identity, which
introduces collective mode contributions in the response functions and
guarantees that the $f$-sum rule is satisfied. We outline a powerful and very
general method to determine these collective modes in a manner compatible with
gauge invariance. Finally, as an alternative approach, we contrast with the
path integral formalism. Here, the calculation of gauge invariant response
appears more straightforward. However, the collective modes introduced are
essentially those of strict BCS theory, with no modification from correlation
effects. Since the path integral scheme simultaneously addresses
electrodynamics and thermodynamics, we emphasize that it should be subjected to
a consistency test beyond gauge invariance, namely that of the compressibility
sum-rule. We show how this sum-rule fails in the conventional path integral
approach.


title: Phase Structure of 1d Interacting Floquet Systems I: Abelian SPTs

abstract:
  Recent work suggests that a sharp definition of `phase of matter' can be
given for some quantum systems out of equilibrium---first for many-body
localized systems with time independent Hamiltonians and more recently for
periodically driven or Floquet localized systems. In this work we propose a
classification of the finite abelian symmetry protected phases of interacting
Floquet localized systems in one dimension. We find that the different Floquet
phases correspond to elements of $\text{Cl}\times\mathcal{A}_G$, where
$\text{Cl}$ is the undriven interacting classification, and $\mathcal{A}_G$ is
a set of (twisted) 1d representations of $G$. We will address symmetry broken
phases in a subsequent paper.


title:
The exceptional generalised geometry of supersymmetric AdS flux
  backgrounds

abstract:
  We analyse generic AdS flux backgrounds preserving eight supercharges in
$D=4$ and $D=5$ dimensions using exceptional generalised geometry. We show that
they are described by a pair of globally defined, generalised structures,
identical to those that appear for flat flux backgrounds but with different
integrability conditions. We give a number of explicit examples of such
"exceptional Sasaki-Einstein" backgrounds in type IIB supergravity and
M-theory. In particular, we give the complete analysis of the generic AdS$_5$
M-theory backgrounds. We also briefly discuss the structure of the moduli space
of solutions. In all cases, one structure defines a "generalised Reeb vector"
that generates a Killing symmetry of the background corresponding to the
R-symmetry of the dual field theory, and in addition encodes the generic
contact structures that appear in the $D=4$ M-theory and $D=5$ type IIB cases.
Finally, we investigate the relation between generalised structures and
quantities in the dual field theory, showing that the central charge and
R-charge of BPS wrapped-brane states are both encoded by the generalised Reeb
vector, as well as discussing how volume minimisation (the dual of $a$- and
$\mathcal{F}$-maximisation) is encoded.


title: Daleel: Simplifying Cloud Instance Selection Using Machine Learning

abstract:
  Decision making in cloud environments is quite challenging due to the
diversity in service offerings and pricing models, especially considering that
the cloud market is an incredibly fast moving one. In addition, there are no
hard and fast rules, each customer has a specific set of constraints (e.g.
budget) and application requirements (e.g. minimum computational resources).
Machine learning can help address some of the complicated decisions by carrying
out customer-specific analytics to determine the most suitable instance type(s)
and the most opportune time for starting or migrating instances. We employ
machine learning techniques to develop an adaptive deployment policy, providing
an optimal match between the customer demands and the available cloud service
offerings. We provide an experimental study based on extensive set of job
executions over a major public cloud infrastructure.


title:
Keck/MOSFIRE Spectroscopy of z=7-8 Galaxies: Ly$\alpha$ Emission from a
  Galaxy at z=7.66

abstract:
  We report the results from some of the deepest Keck/Multi-Object Spectrometer
For Infra-Red Exploration data yet obtained for candidate $z \gtrsim 7$
galaxies. Our data show one significant line detection with 6.5$\sigma$
significance in our combined 10 hr of integration which is independently
detected on more than one night, thus ruling out the possibility that the
detection is spurious. The asymmetric line profile and non-detection in the
optical bands strongly imply that the detected line is Ly$\alpha$ emission from
a galaxy at $z$(Ly$\alpha)=7.6637 \pm 0.0011$, making it the fourth
spectroscopically confirmed galaxy via Ly$\alpha$ at $z>7.5$. This galaxy is
bright in the rest-frame ultraviolet (UV; $M_{\rm UV} \sim -21.2$) with a
moderately blue UV slope ($\beta=-2.2^{+0.3}_{-0.2}$), and exhibits a
rest-frame Ly$\alpha$ equivalent width of EW(Ly$\alpha$) $\sim
15.6^{+5.9}_{-3.6}$ \AA. The non-detection of the 11 other $z \sim$ 7-8
galaxies in our long 10 hr integration, reaching a median 5$\sigma$ sensitivity
of 28 \AA\ in the rest-frame EW(Ly$\alpha$), implies a 1.3$\sigma$ deviation
from the null hypothesis of a non-evolving distribution in the rest-frame
EW(Ly$\alpha$) between $3<z<6$ and $z=$ 7-8. Our results are consistent with
previous studies finding a decline in Ly$\alpha$ emission at $z>6.5$, which may
signal the evolving neutral fraction in the intergalactic medium at the end of
the reionization epoch, although our weak evidence suggests the need for a
larger statistical sample to allow for a more robust conclusion.


title:
The Herschel Virgo Cluster Survey. XIX. Physical properties of low
  luminosity FIR sources at $z <$ 0.5

abstract:
  The Star formation rate (SFR) is a crucial parameter to investigate galaxy
evolution. At low redshift the cosmic SFR density declines smoothly, and
massive active galaxies become passive, reducing their star formation activity.
This implies that the bulk of the SFR density at low redshift is mainly driven
by low mass objects. We investigate the properties of a sample of low
luminosity Far-Infrared (FIR) sources selected at 250 microns from Pappalardo
et al. (2015). We have collected data from Ultraviolet to FIR to perform a
multi-wavelengths analysis. The main goal is to investigate the correlation
between SFR, stellar mass, and dust mass for a galaxy population with a wide
range in dust content and stellar mass, including the low mass regime that most
probably dominates the SFR density at low z. We define a main sample of ~800
sources with full Spectral Energy Distribution (SED) coverage between 0.15 <
lambda < 500 microns and an extended sample with ~5000 sources in which we
remove the constraints on the Ultraviolet and Near-Infrared bands. We analyze
both samples with two different SED fitting methods: MAGPHYS and CIGALE. In the
SFR versus stellar mass plane our samples occupy a region included between
local spirals and higher redshift star forming galaxies. The galaxies subsample
with the higher masses (M* > 3e10 Msol) does not lie on the main sequence, but
shows a small offset, as a consequence of the decreased star formation. Low
mass galaxies (M* < 1e10 Msol) settle in the main sequence with SFR and stellar
mass consistent with local spirals. Deep Herschel data allow the identification
of a mixed galaxy population, with galaxies still in an assembly phase, or
galaxies at the beginning of their passive evolution. We find that the dust
luminosity is the parameter that discriminates these two galaxy populations.


title: Probing a slepton Higgs on all frontiers

abstract:
  We study several aspects of supersymmetric models with a $U(1)_R$ symmetry
where the Higgs doublet is identified with the superpartner of a lepton. We
derive new, stronger bounds on the gaugino masses based on current
measurements, and also propose ways to probe the model up to scales of
$\mathcal{O}(10\, \textrm{TeV})$ at future $e^+e^-$ colliders. Since the
$U(1)_R$ symmetry cannot be exact, we analyze the effects of $R$-symmetry
breaking on neutrino masses and proton decay. In particular, we find that
getting the neutrino mixing angles to agree with experiments in a minimal model
requires a UV cutoff for the theory at around $ 10 \text{ TeV} $.


title: Cyclonic spectra, cyclotomic spectra, and a conjecture of Kaledin

abstract:
  With an explicit, algebraic indexing $(2,1)$-category, we develop an
efficient homotopy theory of cyclonic objects: circle-equivariant objects
relative to the family of finite subgroups. We construct an $\infty$-category
of cyclotomic spectra as the homotopy fixed points of an action of the
multiplicative monoid of the natural numbers on the category of cyclonic
spectra. Finally, we elucidate and prove a conjecture of Kaledin on cyclotomic
complexes.


title:
A Note on Alternating Minimization Algorithm for the Matrix Completion
  Problem

abstract:
  We consider the problem of reconstructing a low rank matrix from a subset of
its entries and analyze two variants of the so-called Alternating Minimization
algorithm, which has been proposed in the past. We establish that when the
underlying matrix has rank $r=1$, has positive bounded entries, and the graph
$\mathcal{G}$ underlying the revealed entries has bounded degree and diameter
which is at most logarithmic in the size of the matrix, both algorithms succeed
in reconstructing the matrix approximately in polynomial time starting from an
arbitrary initialization. We further provide simulation results which suggest
that the second algorithm which is based on the message passing type updates,
performs significantly better.


title: Uchi Mata family analysis for Coaches and Teachers

abstract:
  In this paper it is performed the biomechanical analysis of Uchi Mata family,
the unifying vision of biomechanics let coaches and teachers to approach
competition and lessons in different way. Uchi Mata and all throws that are in
the biomechanical group of Couple applied by trunk - leg showed that these most
effective techniques in high level competition, are in fact also energetically
less expensive than those of the Lever group. The overview of the sportive judo
books that show the different kind of Uchi Mata, for example, are in term of
Biomechanics always the same movement. The Japanese different vision informed
also the studies among the world that never analyzed the unifying vision. The
complementary tools to increase the effectiveness are also analyzed and few New
or Chaotic application of trunk-leg family. The Physical and biomechanical
background is analyzed showing that these throws are also bio-mechanically
simpler, relying only on closing the distance and apply Couple . GAI plus
Couple. Their intrinsic simplicity, however, hides a different complexity from
those of the Lever which, remember, they need a high motor coordination to be
effective. In fact, being able to apply these techniques of Couple require a
particular timing ability.


title: Numerical Study of the Simplest String Bit Model

abstract:
  String bit models provide a possible method to formulate a string as a
discrete chain of pointlike string bits. When the bit number $M$ is large, a
chain behaves as a continuous string. We study the simplest case that has only
one bosonic bit and one fermionic bit. The creation and annihilation operators
are adjoint representations of the $U\left(N\right)$ color group. We show that
the supersymmetry reduces the parameter number of a Hamiltonian from 7 to 3
and, at $N=\infty$, ensures a continuous energy spectrum, which implies the
emergence of one spatial dimension. The Hamiltonian $H_{0}$ is constructed so
that in the large $N$ limit it produces a world sheet spectrum with one
Grassmann world sheet field. We concentrate on numerical study of the model in
finite $N$. For the Hamiltonian $H_{0}$, we find that the would-be ground
energy states disappear at $N=\left(M-1\right)/2$ for odd $M\leq11$. Such a
simple pattern is spoiled if $H$ has an additional term $\xi\Delta H$ which
does not affect the result of $N=\infty$. The disappearance point moves to
higher (lower) $N$ when $\xi$ increases (decreases). Particularly, the
$\pm\left(H_{0}-\Delta H\right)$ cases suggest a possibility that the ground
state could survive at large $M$ and $M\gg N$. Our study reveals that the model
has stringy behavior: when $N$ is fixed and large enough, the ground energy
decreases linearly with respect to $M$, and the excitation energy is roughly of
order $M^{-1}$. We also verify that a stable system of Hamiltonian $\pm
H_{0}+\xi\Delta H$ requires $\xi\geq\mp1$.


title: Firedec: a two-channel finite-resolution image deconvolution algorithm

abstract:
  We present a two-channel deconvolution method that decomposes images into a
parametric point-source channel and a pixelized extended-source channel. Based
on the central idea of the deconvolution algorithm proposed by Magain, Courbin
& Sohy (1998), the method aims at improving the resolution of the data rather
than at completely removing the point spread function (PSF). Improvements over
the original method include a better regularization of the pixel channel of the
image, based on wavelet filtering and multiscale analysis, and a better
controlled separation of the point source vs. the extended source. In addition,
the method is able to simultaneously deconvolve many individual frames of the
same object taken with different instruments under different PSF conditions.
For this purpose, we introduce a general geometric transformation between
individual images. This transformation allows the combination of the images
without having to interpolate them. We illustrate the capability of our
algorithm using real and simulated images with complex diffraction-limited PSF.


title:
Dimensions of the irreducible representations of the symmetric and
  alternating group

abstract:
  We establish the existence of an irreducible representation of $A_n$ whose
dimension does not occur as the dimension of an irreducible representation of
$S_n$, and vice versa. This proves a conjecture by Tong-Viet. The main
ingredient in the proof is a result on large prime factors in short intervals.


title:
Probabilistic Extension to the Concurrent Constraint Factor Oracle Model
  for Music Improvisation

abstract:
  We can program a Real-Time (RT) music improvisation system in C++ without a
formal semantic or we can model it with process calculi such as the
Non-deterministic Timed Concurrent Constraint (ntcc) calculus. "A Concurrent
Constraints Factor Oracle (FO) model for Music Improvisation" (Ccfomi) is an
improvisation model specified on ntcc. Since Ccfomi improvises
non-deterministically, there is no control on choices and therefore little
control over the sequence variation during the improvisation. To avoid this, we
extended Ccfomi using the Probabilistic Non-deterministic Timed Concurrent
Constraint calculus. Our extension to Ccfomi does not change the time and space
complexity of building the FO, thus making our extension compatible with RT.
However, there was not a ntcc interpreter capable of RT to execute Ccfomi. We
developed Ntccrt --a RT capable interpreter for ntcc-- and we executed Ccfomi
on Ntccrt. In the future, we plan to extend Ntccrt to execute our extension to
Ccfomi.


title:
Hydrodynamics of Suspensions of Passive and Active Rigid Particles: A
  Rigid Multiblob Approach

abstract:
  We develop a rigid multiblob method for numerically solving the mobility
problem for suspensions of passive and active rigid particles of complex shape
in Stokes flow in unconfined, partially confined, and fully confined
geometries. As in a number of existing methods, we discretize rigid bodies
using a collection of minimally-resolved spherical blobs constrained to move as
a rigid body, to arrive at a potentially large linear system of equations for
the unknown Lagrange multipliers and rigid-body motions. Here we develop a
block-diagonal preconditioner for this linear system and show that a standard
Krylov solver converges in a modest number of iterations that is essentially
independent of the number of particles. For unbounded suspensions and
suspensions sedimented against a single no-slip boundary, we rely on existing
analytical expressions for the Rotne-Prager tensor combined with a fast
multipole method or a direct summation on a Graphical Processing Unit to obtain
an simple yet efficient and scalable implementation. For fully confined
domains, such as periodic suspensions or suspensions confined in slit and
square channels, we extend a recently-developed rigid-body immersed boundary
method to suspensions of freely-moving passive or active rigid particles at
zero Reynolds number. We demonstrate that the iterative solver for the coupled
fluid and rigid body equations converges in a bounded number of iterations
regardless of the system size. We optimize a number of parameters in the
iterative solvers and apply our method to a variety of benchmark problems to
carefully assess the accuracy of the rigid multiblob approach as a function of
the resolution. We also model the dynamics of colloidal particles studied in
recent experiments, such as passive boomerangs in a slit channel, as well as a
pair of non-Brownian active nanorods sedimented against a wall.


title:
Nematicity in stripe ordered cuprates probed via resonant x-ray
  scattering

abstract:
  In underdoped cuprate superconductors, a rich competition occurs between
superconductivity and charge density wave (CDW) order. Whether rotational
symmetry breaking (nematicity) occurs intrinsically and generically or as a
consequence of other orders is under debate. Here we employ resonant x-ray
scattering in stripe-ordered (La,M)_2CuO_4 to probe the relationship between
electronic nematicity of the Cu 3d orbitals, structure of the (La,M)_2O_2
layers, and CDW order. We find distinct temperature dependences for the
structure of the (La,M)_2O_2 layers and the electronic nematicity of the CuO_2
planes, with only the latter being enhanced by the onset of CDW order. These
results identify electronic nematicity as an order parameter that is distinct
from a purely structural order parameter in underdoped striped cuprates.


title: On Column Selection in Approximate Kernel Canonical Correlation Analysis

abstract:
  We study the problem of column selection in large-scale kernel canonical
correlation analysis (KCCA) using the Nystr\"om approximation, where one
approximates two positive semi-definite kernel matrices using "landmark" points
from the training set. When building low-rank kernel approximations in KCCA,
previous work mostly samples the landmarks uniformly at random from the
training set. We propose novel strategies for sampling the landmarks
non-uniformly based on a version of statistical leverage scores recently
developed for kernel ridge regression. We study the approximation accuracy of
the proposed non-uniform sampling strategy, develop an incremental algorithm
that explores the path of approximation ranks and facilitates efficient model
selection, and derive the kernel stability of out-of-sample mapping for our
method. Experimental results on both synthetic and real-world datasets
demonstrate the promise of our method.


title:
Results from (anti-)(hyper-)nuclei production and searches for exotic
  bound states with ALICE at the LHC

abstract:
  The excellent particle identification capabilities of the ALICE detector,
using the time projection chamber and the time-of-flight detector, allow the
detection of light nuclei and anti-nuclei. Furthermore, the high tracking
resolution provided by the inner tracking system enables the separation of
primary nuclei from those coming from the decay of heavier systems. This allows
for the reconstruction of decays such as the hypertriton mesonic weak decay
($^3_{\Lambda}$H$\rightarrow ^3$He + $\pi^-$), the decay of a hypothetical
bound state of a $\Lambda$n into a deuteron and pion or the H-dibaryon decaying
into a $\Lambda$, a proton and a $\pi^{-}$. An overview of the production of
stable nuclei and anti-nuclei in proton-proton, proton-lead and, in particular,
lead-lead collisions is presented. Hypernuclei production rates in Pb--Pb are
also shown, together with the upper limits estimated on the production of
hypothetical exotica candidates. The results are compared with predictions for
the production in thermal (statistical) and coalescence models.


title: Participation Incentives in Randomized Social Choice

abstract:
  When aggregating preferences of agents via voting, two desirable goals are to
identify outcomes that are Pareto optimal and to incentivize agents to
participate in the voting process. We consider participation notions as
formalized by Brandl, Brandt, and Hofbauer (2015) and study how far efficiency
and participation are achievable by randomized social choice functions in
particular when agents' preferences are downward lexicographic (DL) or satisfy
stochastic dominance (SD). Our results include the followings ones: we prove
formal relations between the participation notions with respect to SD and DL
and we show that the maximal recursive rule satisfies very strong participation
with respect to both SD and DL.


title: A Decomposition of Parking Functions by Undesired Spaces

abstract:
  There is a well-known bijection between parking functions of a fixed length
and maximal chains of the noncrossing partition lattice which we can use to
associate to each set of parking functions a poset whose Hasse diagram is the
union of the corresponding maximal chains. We introduce a decomposition of
parking functions based on the largest number omitted and prove several
theorems about the corresponding posets. In particular, they share properties
with the noncrossing partition lattice such as local self-duality, a nice
characterization of intervals, a readily computable M\"obius function, and a
symmetric chain decomposition. We also explore connections with order
complexes, labeled Dyck paths, and rooted forests.


title:
Regularization and confounding in linear regression for treatment effect
  estimation

abstract:
  This paper investigates the use of regularization priors in the context of
treatment effect estimation using observational data where the number of
control variables is large relative to the number of observations. First, the
phenomenon of regularization-induced confounding is introduced, which refers to
the tendency of regularization priors to adversely bias treatment effect
estimates by over-shrinking control variable regression coefficients. Then, a
simultaneous regression model is presented which permits regularization priors
to be specified in a way that avoids this unintentional re-confounding. The new
model is illustrated on synthetic and empirical data.


title:
Self-induced switchings between multiple space-time patterns on complex
  networks of excitable units

abstract:
  We report on self-induced switchings between multiple distinct space--time
patterns in the dynamics of a spatially extended excitable system. These
switchings between low-amplitude oscillations, nonlinear waves, and extreme
events strongly resemble a random process, although the system is
deterministic. We show that a chaotic saddle -- which contains all the patterns
as well as channel-like structures that mediate the transitions between them --
is the backbone of such a pattern switching dynamics. Our analyses indicate
that essential ingredients for the observed phenomena are that the system
behaves like an inhomogeneous oscillatory medium that is capable of
self-generating spatially localized excitations and that is dominated by
short-range connections but also features long-range connections. With our
findings, we present an alternative to the well-known ways to obtain
self-induced pattern switching, namely noise-induced attractor hopping,
heteroclinic orbits, and adaptation to an external signal. This alternative way
can be expected to improve our understanding of pattern switchings in spatially
extended natural dynamical systems like the brain and the heart.


title:
Cooperative Hierarchical Caching in 5G Cloud Radio Access Networks
  (C-RANs)

abstract:
  Over the last few years, Cloud Radio Access Network (C-RAN) has arisen as a
transformative architecture for 5G cellular networks that brings the
flexibility and agility of cloud computing to wireless communications. At the
same time, content caching in wireless networks has become an essential
solution to lower the content-access latency and backhaul traffic loading,
which translate into user Quality of Experience (QoE) improvement and network
cost reduction. In this article, a novel Cooperative Hierarchical Caching (CHC)
framework in C-RAN is introduced where contents are jointly cached at the
BaseBand Unit (BBU) and at the Radio Remote Heads (RRHs). Unlike in traditional
approaches, the cache at the BBU, cloud cache, presents a new layer in the
cache hierarchy, bridging the latency/capacity gap between the traditional
edge-based and core-based caching schemes. Trace-driven simulations reveal that
CHC yields up to 80% improvement in cache hit ratio, 21% decrease in average
content-access latency, and 20% reduction in backhaul traffic load compared to
the edge-only caching scheme with the same total cache capacity. Before closing
the article, several challenges and promising opportunities for deploying
content caching in C-RAN are highlighted towards a content-centric mobile
wireless network.


title:
Schwarzian derivative treatment of the quantum second-order
  supersymmetry anomaly, and coupling-constant metamorphosis

abstract:
  A canonical quantization scheme applied to a classical supersymmetric system
with quadratic in momentum supercharges gives rise to a quantum anomaly problem
described by a specific term to be quadratic in Planck constant. We reveal a
close relationship between the anomaly and the Schwarzian derivative, and
specify a quantization prescription which generates the anomaly-free
supersymmetric quantum system with second order supercharges. We also discuss
the phenomenon of a coupling-constant metarmorphosis that associates quantum
systems with first-order supersymmetry to the systems with the second-order
supercharges.


title: Accessible values of Assouad and the lower dimensions of subsets

abstract:
  Let $E$ be a subset of a doubling metric space $(X,d)$. We prove that for any
$s\in [0, \dim_{A}E]$, where $\dim_{A}$ denotes the Assouad dimension, there
exists a subset $F$ of $E$ such that $\dim_{A}F=s$. We also show that the same
statement holds for the lower dimension $\dim_L$.


title: Active Information Acquisition

abstract:
  We propose a general framework for sequential and dynamic acquisition of
useful information in order to solve a particular task. While our goal could in
principle be tackled by general reinforcement learning, our particular setting
is constrained enough to allow more efficient algorithms. In this paper, we
work under the Learning to Search framework and show how to formulate the goal
of finding a dynamic information acquisition policy in that framework. We apply
our formulation on two tasks, sentiment analysis and image recognition, and
show that the learned policies exhibit good statistical performance. As an
emergent byproduct, the learned policies show a tendency to focus on the most
prominent parts of each instance and give harder instances more attention
without explicitly being trained to do so.


title:
Interleaved numerical renormalization group as an efficient multiband
  impurity solver

abstract:
  Quantum impurity problems can be solved using the numerical renormalization
group (NRG), which involves discretizing the free conduction electron system
and mapping to a `Wilson chain'. It was shown recently that Wilson chains for
different electronic species can be interleaved by use of a modified
discretization, dramatically increasing the numerical efficiency of the RG
scheme [Phys. Rev. B 89, 121105(R) (2014)]. Here we systematically examine the
accuracy and efficiency of the `interleaved' NRG (iNRG) method in the context
of the single impurity Anderson model, the two-channel Kondo model, and a
three-channel Anderson-Hund model. The performance of iNRG is explicitly
compared with `standard' NRG (sNRG): when the average number of states kept per
iteration is the same in both calculations, the accuracy of iNRG is equivalent
to that of sNRG but the computational costs are signifficantly lower in iNRG
when the same symmetries are exploited. Although iNRG weakly breaks SU(N)
channel symmetry (if present), both accuracy and numerical cost are entirely
competitive with sNRG exploiting full symmetries. iNRG is therefore shown to be
a viable and technically simple alternative to sNRG for high-symmetry models.
Moreover, iNRG can be used to solve a range of lower-symmetry multiband
problems that are inaccessible to sNRG.


title:
The start of the Sagittarius spiral arm (Sagittarius origin) and the
  start of the Norma spiral arm (Norma origin) - model-computed and observed
  arm tangents at galactic longitudes -20 degrees < l < +23 degrees

abstract:
  Here we fitted a 4-arm spiral structure to the more accurate data on global
arm pitch angle and arm longitude tangents, to get the start of each spiral arm
near the Galactic nucleus. We find that the tangent to the 'start of the
Sagittarius' spiral arm (arm middle) is at l= -17 degrees +/- 0.5 degree, while
the tangent to the 'start of the Norma' spiral arm (arm middle) is at l= +20
degrees +/- 0.5 degree.
  Earlier, we published a compilation of observations and analysis of the
tangent to each spiral arm tracer, from longitudes +23 degrees to +340 degrees;
here we cover the arm tracers in the remaining longitudes +340 degrees (=- 20
degrees) to +23 degrees. Our model arm tangents are confirmed through the
recent observed masers data (at the arm's inner edge). Observed arm tracers in
the inner Galaxy show an offset from the mid-arm; this was also found elsewhere
in the Milky Way disk (Vallee 2014c).
  In addition, we collated the observed tangents to the so-called '3-kpc-arm'
features; here they are found statistically to be near l= -18 degrees +/- 2
degrees and near l= +21 degrees +/- 2 degrees, after excluding misidentified
spiral arms. We find that the model-computed arm tangents in the inner Galaxcy
are spatially coincident with the mean longitude of the observed tangents to
the '3-kpc-arm' features (same galactic longitudes, within the errors). These
spatial similarities may be suggestive of a contiguous space.


title:
Maximum Likelihood Estimation for Semiparametric Transformation Models
  with Interval-Censored Data

abstract:
  Interval censoring arises frequently in clinical, epidemiological, financial,
and sociological studies, where the event or failure of interest is known only
to occur within an interval induced by periodic monitoring. We formulate the
effects of potentially time-dependent covariates on the interval-censored
failure time through a broad class of semiparametric transformation models that
encompasses proportional hazards and proportional odds models. We consider
nonparametric maximum likelihood estimation for this class of models with an
arbitrary number of monitoring times for each subject. We devise an EM-type
algorithm that converges stably, even in the presence of time-dependent
covariates, and show that the estimators for the regression parameters are
consistent, asymptotically normal, and asymptotically efficient with an easily
estimated covariance matrix. Finally, we demonstrate the performance of our
procedures through extensive simulation studies and application to an HIV/AIDS
study conducted in Thailand.


title:
Sparse Kalman Filtering Approaches to Covariance Estimation from High
  Frequency Data in the Presence of Jumps

abstract:
  Estimation of the covariance matrix of asset returns from high frequency data
is complicated by asynchronous returns, market mi- crostructure noise and
jumps. One technique for addressing both asynchronous returns and market
microstructure is the Kalman-EM (KEM) algorithm. However the KEM approach
assumes log-normal prices and does not address jumps in the return process
which can corrupt estimation of the covariance matrix.
  In this paper we extend the KEM algorithm to price models that include jumps.
We propose two sparse Kalman filtering approaches to this problem. In the first
approach we develop a Kalman Expectation Conditional Maximization (KECM)
algorithm to determine the un- known covariance as well as detecting the jumps.
For this algorithm we consider Laplace and the spike and slab jump models, both
of which promote sparse estimates of the jumps. In the second method we take a
Bayesian approach and use Gibbs sampling to sample from the posterior
distribution of the covariance matrix under the spike and slab jump model.
Numerical results using simulated data show that each of these approaches
provide for improved covariance estima- tion relative to the KEM method in a
variety of settings where jumps occur.


title: Endomorphisms of The Hamming Graph and Related Graphs

abstract:
  In this paper we determine all singular endomorphisms of the Hamming graph
and other related graphs. The Hamming graph has vertices $\mathbb{Z}^{m}_n$
where two vertices are adjacent, if their Hamming distance is $1$. We show that
its singular endomorphisms are uniform (each kernel has the same size) and that
they are induced by Latin hypercubes (which essentially determines the number
of singular endomorphisms). However, we do the same for its complement and some
related graphs where the Hamming distance is allowed to be one of $1,...,k$,
for some $1\leq k\leq m-1$. Ultimately, we consider the same situation where
the vertices are tuples in $\mathbb{Z}_{n_1}\times\mathbb{Z}_{n_2}\times\cdots
\times\mathbb{Z}_{n_m}$ (not all $n_i$ are equal).


title:
Using particle swarm optimization to search for locally $D$-optimal
  designs for mixed factor experiments with binary response

abstract:
  Identifying optimal designs for generalized linear models with a binary
response can be a challenging task, especially when there are both continuous
and discrete independent factors in the model. Theoretical results rarely exist
for such models, and the handful that do exist come with restrictive
assumptions. This paper investigates the use of particle swarm optimization
(PSO) to search for locally $D$-optimal designs for generalized linear models
with discrete and continuous factors and a binary outcome and demonstrates that
PSO can be an effective method. We provide two real applications using PSO to
identify designs for experiments with mixed factors: one to redesign an odor
removal study and the second to find an optimal design for an electrostatic
discharge study. In both cases we show that the $D$-efficiencies of the designs
found by PSO are much better than the implemented designs. In addition, we show
PSO can efficiently find $D$-optimal designs on a prototype or an irregularly
shaped design space, provide insights on the existence of minimally supported
optimal designs, and evaluate sensitivity of the $D$-optimal design to
mis-specifications in the link function.


title:
Radio Non-Detection of the SGR 1806-20 Giant Flare and Implications for
  Fast Radio Bursts

abstract:
  We analyse archival data from the Parkes radio telescope which was observing
a location 35.6$^\circ$ away from SGR 1806-20 during its giant $\gamma$-ray
flare of 2004 December 27. We show that no FRB-like burst counterpart was
detected, and set a radio limit of 110\,MJy at 1.4 GHz, including the estimated
70\,dB suppression of the signal due to its location in the far side lobe of
Parkes and the predicted scattering from the interstellar medium. The upper
limit for the magnetar giant flare radio to $\gamma$-ray fluence ratio is
$\eta_\mathrm{SGR} \lesssim 10^{7}\,\mathrm{Jy\,ms\,erg^{-1}\,cm^{2}}$. Based
on the non-detection of a short and prompt $\gamma$-ray counterpart of fifteen
FRBs in $\gamma$-ray transient monitors, we set a lower limit on the fluence
ratios of FRBs to be $\eta_\mathrm{FRB} \gtrsim
10^{7-9}\,\mathrm{Jy\,ms\,erg^{-1}\,cm^{2}}$. The fluence ratio limit for \sgr\
is inconsistent with all but one of the fifteen FRBs. We discuss possible
variations in the magnetar-FRB emission mechanism and observational caveats
that may reconcile the theory with observations.


title:
Searching for new yellow symbiotic stars: positive identification of
  StHa63

abstract:
  Yellow symbiotic stars are useful targets to probe whether mass transfer has
happened in these binary systems. However, the number of known yellow symbiotic
stars is very scarce. We report spectroscopic observations of five candidate
yellow symbiotic stars selected by their position in the 2MASS (J-H) vs. (H-Ks)
diagram and included in some emission-line catalogs. Among the five candidates,
only StHa63 is identified as a new yellow symbiotic star because of its
spectrum and its position in the [TiO]1-[TiO]2 diagram that indicates a K4-K6
spectral type. In addition, the derived electron density (10E8.4 cm-3) and
several emission line intensity ratios provide further support for that
classification. The other four candidates are rejected as symbiotic stars
because three of them actually do not show emission lines and the fourth one
shows only Balmer emission lines. We also found that the WISE W3-W4 index
clearly separates normal K-giants from yellow symbiotic stars and, therefore,
can be used as an additional tool to select candidate yellow symbiotic stars.


title:
Site-specific recombinatorics: in situ cellular barcoding with the Cre
  Lox system

abstract:
  Cellular barcoding is a significant, recently developed, biotechnology tool
that enables the familial identification of progeny of individual cells in
vivo. Most existing approaches rely on ex vivo viral transduction of cells with
barcodes, followed by adoptive transfer into an animal, which works well for
some systems, but precludes barcoding cells in their native environment, such
as those inside solid tissues. With a view to overcoming this limitation, we
propose a new design for a genetic barcoding construct based on the Cre Lox
system that induces randomly created stable barcodes in cells in situ by
exploiting inherent sequence distance constraints during site-specific
recombination. Leveraging this previously unused feature, we identify the
cassette with maximal code diversity. This proves to be orders of magnitude
higher than what is attainable with previously considered Cre Lox barcoding
approaches and is well suited for its intended applications as it exceeds the
number of lymphocytes or hematopoietic progenitor cells in mice. Moreover, it
can be built using established technology.


title:
Convex Relaxation Regression: Black-Box Optimization of Smooth Functions
  by Learning Their Convex Envelopes

abstract:
  Finding efficient and provable methods to solve non-convex optimization
problems is an outstanding challenge in machine learning and optimization
theory. A popular approach used to tackle non-convex problems is to use convex
relaxation techniques to find a convex surrogate for the problem.
Unfortunately, convex relaxations typically must be found on a
problem-by-problem basis. Thus, providing a general-purpose strategy to
estimate a convex relaxation would have a wide reaching impact. Here, we
introduce Convex Relaxation Regression (CoRR), an approach for learning convex
relaxations for a class of smooth functions. The main idea behind our approach
is to estimate the convex envelope of a function $f$ by evaluating $f$ at a set
of $T$ random points and then fitting a convex function to these function
evaluations. We prove that with probability greater than $1-\delta$, the
solution of our algorithm converges to the global optimizer of $f$ with error
$\mathcal{O} \Big( \big(\frac{\log(1/\delta) }{T} \big)^{\alpha} \Big)$ for
some $\alpha> 0$. Our approach enables the use of convex optimization tools to
solve a class of non-convex optimization problems.


title: On minimising a portfolio's shortfall probability

abstract:
  We obtain a lower asymptotic bound on the decay rate of the probability of a
portfolio's underperformance against a benchmark over a large time horizon. It
is assumed that the prices of the securities are governed by geometric Brownian
motions with the coefficients depending on an economic factor, possibly
nonlinearly. The economic factor is modelled with a general Ito equation. The
bound is shown to be tight. More specifically, epsilon-optimal portfolios are
obtained under additional conditions.


title:
Microstructure evolution of compressible granular systems under large
  deformations

abstract:
  We report three-dimensional particle mechanics static calculations that
predict the microstructure evolution during die-compaction of elastic spherical
particles up to relative densities close to one. We employ a nonlocal contact
formulation that remains predictive at high levels of confinement by removing
the classical assumption that contacts between particles are formulated locally
as independent pair-interactions. The approach demonstrates that the
coordination number depends on the level of compressibility, i.e., on the
Poisson's ratio, of the particles. Results also reveal that distributions of
contact forces between particles and between particles and walls, although
similar at jamming onset, are very different at full compaction. Particle-wall
forces are in remarkable agreement with experimental measurements reported in
the literature, providing a unifying framework for bridging experimental
boundary observations with bulk behavior.


title:
Global $W^{1,p}$ estimates for solutions to the linearized
  Monge--Amp\`ere equations

abstract:
  In this paper, we investigate regularity for solutions to the linearized
Monge-Amp\`ere equations when the nonhomogeneous term has low integrability. We
establish global
  $W^{1,p}$ estimates for all $p<\frac{nq}{n-q}$ for solutions to the equations
with right hand side in $L^q$ where $n/2<q\leq n$. These estimates hold under
natural assumptions on the domain, Monge-Amp\`ere measures and boundary data.
Our estimates are affine invariant analogues of the global $W^{1,p}$ estimates
of N. Winter for fully nonlinear, uniformly elliptic equations.


title:
Semiclassical limits of Ore extensions and a Poisson generalized Weyl
  algebra

abstract:
  We observe \cite[Proposition 4.1]{LaLe} that Poisson polynomial extensions
appear as semiclassical limits of a class of Ore extensions. As an application,
a Poisson generalized Weyl algebra $A_1$ considered as a Poisson version of the
quantum generalized Weyl algebra is constructed and its Poisson structures are
studied. In particular, it is obtained a necessary and sufficient condition
such that $A_1$ is Poisson simple and established that the Poisson
endomorphisms of $A_1$ are Poisson analogues of the endomorphisms of the
quantum generalized Weyl algebra.


title: BISTRO: An Efficient Relaxation-Based Method for Contextual Bandits

abstract:
  We present efficient algorithms for the problem of contextual bandits with
i.i.d. covariates, an arbitrary sequence of rewards, and an arbitrary class of
policies. Our algorithm BISTRO requires d calls to the empirical risk
minimization (ERM) oracle per round, where d is the number of actions. The
method uses unlabeled data to make the problem computationally simple. When the
ERM problem itself is computationally hard, we extend the approach by employing
multiplicative approximation algorithms for the ERM. The integrality gap of the
relaxation only enters in the regret bound rather than the benchmark. Finally,
we show that the adversarial version of the contextual bandit problem is
learnable (and efficient) whenever the full-information supervised online
learning problem has a non-trivial regret guarantee (and efficient).


title:
The topological structures in strongly coupled QGP with chiral fermions
  on the lattice

abstract:
  The nature of chiral phase transition for two flavor QCD is an interesting
but unresolved problem. One of the most intriguing issues is whether or not the
anomalous U(1) symmetry in the flavor sector is effectively restored along with
the chiral symmetry. This may determine the universality class of the chiral
phase transition. Since the physics near the chiral phase transition is
essentially non-perturbative, we employ first principles lattice techniques to
address this issue. We use overlap fermions, which have exact chiral symmetry
on the lattice, to probe the anomalous U(1) symmetry violation of 2+1 flavor
dynamical QCD configurations with domain wall fermions. The latter also
optimally preserves chiral and flavor symmetries on the lattice, since it is
known that the remnant chiral symmetry of the light quarks influences the
scaling of the chiral condensate in the crossover transition region. We observe
that the anomalous U(1) is not effectively restored in the chiral crossover
region. We perform a systematic study of the finite size and cut-off effects
since the signals of U(1) violation are sensitive to it. We also provide a
glimpse of the microscopic topological structures of the QCD medium that are
responsible for the strongly interacting nature of the quark gluon plasma
phase. We study the effect of these microscopic constituents through our first
calculations for the topological susceptibility of QCD at finite temperature,
which could be a crucial input for the equation of state for anomalous
hydrodynamics.


title:
Robustness Metric for Quantifying Causal Model Confidence and Parameter
  Uncertainty

abstract:
  Many methods of estimating causal models do not provide estimates of
confidence in the resulting model. In this work, a metric is proposed for
validating the output of a causal model fit; the robustness of the model
structure with resampled data. The metric is developed for time series causal
models, but is also applicable to non-time series data. The proposed metric may
be utilized regardless of the method selected for fitting the causal model. We
find that with synthetically generated data, this metric is able to
successfully identify the true data generating model in most cases.
Additionally, the metric provides both a qualitative measure of model
confidence represented by the robustness level as well as accurate estimates of
uncertainty in model coefficients which are important in interpreting model
results. The use of this metric is demonstrated on both numerically simulated
data and a case study from existing causal model literature.


title: On a class of nonlinear matrix equations $X\pm A^{\small H}f(X)^{-1}A=Q$

abstract:
  Nonlinear matrix equations are encountered in many applications of control
and engineering problems. In this work, we establish a complete study for a
class of nonlinear matrix equations. With the aid of Sherman Morrison Woodbury
formula, we have shown that any equation in this class has the maximal positive
definite solution under a certain condition. Furthermore, A thorough study of
properties about this class of matrix equations is provided. An acceleration of
iterative method with R-superlinear convergence with order $r>1$ is then
designed to solve the maximal positive definite solution efficiently.


title:
Rebuttal of the 'Letter to the Editor' of Annals of Applied Statistics
  on Lambert W x F Distributions and the IGMM Algorithm

abstract:
  I discuss comments and claims made in Stehlik and Hermann (2015) about skewed
Lambert W x F random variables and the IGMM algorithm. I clarify
misunderstandings about the definition and use of Lambert W x F distributions
and show that most of their empirical results cannot be reproduced. I also
introduce a variant of location-scale Lambert W x F distributions that are
well-defined for random variables X ~ F with non-finite mean and variance.