title: Quantum Zeno Dynamics through stochastic protocols

abstract:
  Quantum Zeno Dynamics is the phenomenon that the observation or strong
driving of a quantum system can freeze its dynamics to a subspace, effectively
truncating the Hilbert space of the system. It represents the quantum version
of the famous flying arrow Zeno paradox. Here, we study how temporal
stochasticity in the system observation (or driving) affects the survival
probability of the system in the subspace. In particular, we introduce a strong
and a weak Zeno regime for which we quantify the confinement by providing an
analytical expression for this survival probability. We investigate several
dissipative and coherent protocols to confine the dynamics, and show that they
can be successfully adapted to the stochastic version. In the weak Zeno regime
the dynamics within the subspace effectively acts as an additional source of
stochasticity in the confinement protocol. Our analytical predictions are
numerically tested and verified on a paradigmatic spin chain. As practical
implications different coherent and dissipative confinement protocols allow to
choose a trade-off between a probabilistic scheme with high fidelity (compared
to perfect subspace dynamics) and a deterministic one with a slightly lower
fidelity, which is a step towards better control in future quantum
technologies.


title:
Propagation of Ultra High Energy Cosmic Rays in Extragalactic Magnetic
  Fields: A view from cosmological simulations

abstract:
  We use the CRPropa code to simulate the propagation of ultra high energy
cosmic rays (with energy $\geq 10^{18} \rm eV$ and pure proton composition)
through extragalactic magnetic fields that have been simulated with the
cosmological ENZO code.We test both primordial and astrophysical magnetogenesis
scenarios in order to investigate the impact of different magnetic field
strengths in clusters, filaments and voids on the deflection of cosmic rays
propagating across cosmological distances. We also study the effect of
different source distributions of cosmic rays around simulated Milky-Way like
observers. Our analysis shows that the arrival spectra and anisotropy of events
are rather insensitive to the distribution of extragalactic magnetic fields,
while they are more affected by the clustering of sources within a $\sim 50$
Mpc distance to observers. Finally, we find that in order to reproduce the
observed degree of isotropy of cosmic rays at $\sim $ EeV energies, the average
magnetic fields in cosmic voids must be $\sim 0.1 \rm \ nG$, providing limits
on the strength of primordial seed fields.


title:
Thin-disk laser scaling limit due to thermal-lens induced misalignment
  instability

abstract:
  We present an obstacle in power scaling of thin-disk lasers related with
self-driven growth of misalignment due to thermal lens effects. This
self-driven growth arises from the changes of the optical phase difference at
the disk caused by the excursion of the laser eigen-mode from the optical axis.
We found a criterion based on a simplified model of this phenomenon which can
be applied to design laser resonators insensitive to this effect. Moreover, we
propose several resonator architectures which are not affected by this effect.


title: 3D visualization of astronomy data cubes using immersive displays

abstract:
  We report on an exploratory project aimed at performing immersive 3D
visualization of astronomical data, starting with spectral-line radio data
cubes from galaxies. This work is done as a collaboration between the
Department of Physics and Astronomy and the Department of Computer Science at
the University of Manitoba. We are building our prototype using the 3D engine
Unity, because of its ease of use for integration with advanced displays such
as a CAVE environment, a zSpace tabletop, or virtual reality headsets. We
address general issues regarding 3D visualization, such as: load and convert
astronomy data, perform volume rendering on the GPU, and produce physically
meaningful visualizations using principles of visual literacy. We discuss some
challenges to be met when designing a user interface that allows us to take
advantage of this new way of exploring data. We hope to lay the foundations for
an innovative framework useful for all astronomers who use spectral line data
cubes, and encourage interested parties to join our efforts. This pilot project
addresses the challenges presented by frontier astronomy experiments, such as
the Square Kilometre Array and its precursors.


title: Convergence and Cycling in Walker-type Saddle Search Algorithms

abstract:
  Algorithms for computing local minima of smooth objective functions enjoy a
mature theory as well as robust and efficient implementations. By comparison,
the theory and practice of saddle search is destitute. In this paper we present
results for idealized versions of the dimer and gentlest ascent (GAD) saddle
search algorithms that show-case the limitations of what is theoretically
achievable within the current class of saddle search algorithms: (1) we present
an improved estimate on the region of attraction of saddles; and (2) we
construct quasi-periodic solutions which indicate that it is impossible to
obtain globally convergent variants of dimer and GAD type algorithms.


title: The noncommutative geometry of elliptic difference equations

abstract:
  We give a new construction of noncommutative surfaces via elliptic difference
operators, attaching a 1-parameter noncommutative deformation to any projective
rational surface with smooth anticanonical curve. The construction agrees with
one implicit in work of Van den Bergh (iterated blowups of noncommutative
Hirzebruch surfaces), but the construction enables one to prove a number of new
facts about these surfaces. We show that they are noncommutative smooth proper
surfaces in the sense of Chan and Nyman, with projective Quot schemes, that
moduli spaces of simple sheaves are Poisson and that moduli spaces classifying
semistable sheaves of rank 0 or 1 are projective. We further show that the
action of SL_2(Z) as derived autoequivalences of rational elliptic surfaces
extends to an action as derived equivalences of surfaces in our family with
K^2=0.
  We also discuss applications to the theory of special functions arising by
interpreting moduli spaces of 1-dimensional sheaves as moduli spaces of
difference equations. When the moduli space is a single point, the equation is
rigid, and we give an integral representation for the solutions. More
generally, twisting by line bundles corresponds to isomonodromy deformations,
so this gives rise to Lax pairs. When the moduli space is 2-dimensional, one
obtains Lax pairs for the elliptic Painlev\'e equation; this associates a Lax
pair to any rational number, of order twice the denominator. There is also an
elliptic analogue of the Riemann-Hilbert correspondence: an analytic
equivalence between categories of elliptic difference equations, swapping the
role of the shift of the equation and the nome of the curve.


title: The Phylogenetic LASSO and the Microbiome

abstract:
  Scientific investigations that incorporate next generation sequencing involve
analyses of high-dimensional data where the need to organize, collate and
interpret the outcomes are pressingly important. Currently, data can be
collected at the microbiome level leading to the possibility of personalized
medicine whereby treatments can be tailored at this scale. In this paper, we
lay down a statistical framework for this type of analysis with a view toward
synthesis of products tailored to individual patients. Although the paper
applies the technique to data for a particular infectious disease, the
methodology is sufficiently rich to be expanded to other problems in medicine,
especially those in which coincident `-omics' covariates and clinical responses
are simultaneously captured.


title:
Identifying and Harnessing the Building Blocks of Machine Learning
  Pipelines for Sensible Initialization of a Data Science Automation Tool

abstract:
  As data science continues to grow in popularity, there will be an increasing
need to make data science tools more scalable, flexible, and accessible. In
particular, automated machine learning (AutoML) systems seek to automate the
process of designing and optimizing machine learning pipelines. In this
chapter, we present a genetic programming-based AutoML system called TPOT that
optimizes a series of feature preprocessors and machine learning models with
the goal of maximizing classification accuracy on a supervised classification
problem. Further, we analyze a large database of pipelines that were previously
used to solve various supervised classification problems and identify 100 short
series of machine learning operations that appear the most frequently, which we
call the building blocks of machine learning pipelines. We harness these
building blocks to initialize TPOT with promising solutions, and find that this
sensible initialization method significantly improves TPOT's performance on one
benchmark at no cost of significantly degrading performance on the others.
Thus, sensible initialization with machine learning pipeline building blocks
shows promise for GP-based AutoML systems, and should be further refined in
future work.


title: Electromagnetic duality anomaly in curved spacetimes

abstract:
  The source-free Maxwell action is invariant under electric-magnetic duality
rotations in arbitrary spacetimes. This leads to a conserved classical Noether
charge. We show that this conservation law is broken at the quantum level in
presence of a background classical gravitational field with a non-trivial
Chern-Pontryagin invariant, in a parallel way to the chiral anomaly for
massless Dirac fermions. Among the physical consequences, the net polarization
of the quantum electromagnetic field is not conserved.


title: Landau-Ginzburg Hodge numbers for mirrors of del Pezzo surfaces

abstract:
  We consider the conjectures from the paper by Katzarkov, Kontsevich, and
Pantev about Landau-Ginzburg Hodge numbers associated to tamely compactifiable
Landau-Ginzburg models. We test these conjectures in case of dimension two,
verifying some and giving a counterexample to the other.


title: Fusion basis for lattice gauge theory and loop quantum gravity

abstract:
  We introduce a new basis for the gauge-invariant Hilbert space of lattice
gauge theory and loop quantum gravity in $(2+1)$ dimensions, the fusion basis.
In doing so, we shift the focus from the original lattice (or spin-network)
structure directly to that of the magnetic (curvature) and electric (torsion)
excitations themselves. These excitations are classified by the irreducible
representations of the Drinfel'd double of the gauge group, and can be readily
"fused" together by studying the tensor product of such representations. We
will also describe in detail the ribbon operators that create and measure these
excitations and make the quasi-local structure of the observable algebra
explicit. Since the fusion basis allows for both magnetic and electric
excitations from the onset, it turns out to be a precious tool for studying the
large scale structure and coarse-graining flow of lattice gauge theories and
loop quantum gravity. This is in neat contrast with the widely used
spin-network basis, in which it is much more complicated to account for
electric excitations, i.e. for Gau\ss~constraint violations, emerging at larger
scales. Moreover, since the fusion basis comes equipped with a hierarchical
structure, it readily provides the language to design states with sophisticated
multi-scale structures. Another way to employ this hierarchical structure is to
encode a notion of subsystems for lattice gauge theories and $(2+1)$ gravity
coupled to point particles. In a follow-up work, we will exploit this notion to
provide a new definition of entanglement entropy for these theories.


title:
The competing risks Cox model with and without auxiliary case covariates
  under weaker or no missing-at-random cause of failure

abstract:
  In the analysis of time-to-event data with multiple causes using a competing
risks Cox model, often the cause of failure is unknown for some of the cases.
The probability of a missing cause is typically assumed to be independent of
the cause given the time of the event and covariates measured before the event
occurred. In practice, however, the underlying missing-at-random assumption
does not necessarily hold. Motivated by colorectal cancer subtype analysis, we
develop semiparametric methods to conduct valid analysis, first when additional
auxiliary variables are available for cases only. We consider a weaker
missing-at-random assumption, with missing pattern depending on the observed
quantities, which include the auxiliary covariates. Overlooking these
covariates will potentially result in biased estimates. We use an informative
likelihood approach that will yield consistent estimates even when the
underlying model for missing cause of failure is misspecified. We then consider
a method to conduct valid statistical analysis when there are no auxiliary
covariates in the not missing-at-random scenario. The superiority of our
methods in finite samples is demonstrated by simulation study results. We
illustrate the use of our method in an analysis of colorectal cancer data from
the Nurses' Health Study cohort, where, apparently, the traditional
missing-at-random assumption fails to hold for particular molecular subtypes.


title: Labeling of Query Words using Conditional Random Field

abstract:
  This paper describes our approach on Query Word Labeling as an attempt in the
shared task on Mixed Script Information Retrieval at Forum for Information
Retrieval Evaluation (FIRE) 2015. The query is written in Roman script and the
words were in English or transliterated from Indian regional languages. A total
of eight Indian languages were present in addition to English. We also
identified the Named Entities and special symbols as part of our task. A CRF
based machine learning framework was used for labeling the individual words
with their corresponding language labels. We used a dictionary based approach
for language identification. We also took into account the context of the word
while identifying the language. Our system demonstrated an overall accuracy of
75.5% for token level language identification. The strict F-measure scores for
the identification of token level language labels for Bengali, English and
Hindi are 0.7486, 0.892 and 0.7972 respectively. The overall weighted F-measure
of our system was 0.7498.


title: Multi-center Superstrata

abstract:
  We construct a new class of superstrata, the regular supergravity solutions
describing the microstates of D1-D5-P black holes. Our solutions are obtained
by adding momentum charge to the D1-D5 geometries based on multiple concentric
Kaluza-Klein monopoles.


title: Authorship Verification - An Approach based on Random Forest

abstract:
  Authorship attribution, being an important problem in many areas in-cluding
information retrieval, computational linguistics, law and journalism etc., has
been identified as a subject of increasingly research interest in the re-cent
years. In case of Author Identification task in PAN at CLEF 2015, the main
focus was given on cross-genre and cross-topic author verification tasks. We
have used several word-based and style-based features to identify the
dif-ferences between the known and unknown problems of one given set and label
the unknown ones accordingly using a Random Forest based classifier.


title:
Protein structure, activity and thermal stability within nanoscopic
  compartments

abstract:
  We report that protein confinement within nanoscopic vesicular compartments
corresponds to a liquid-liquid phase transition with the protein/water within
vesicle lumen interacting very differently than in bulk. We show this effect
leads to considerable structural changes on the proteins with evidence
suggesting non-alpha helical conformations. Most importantly both aspects lead
to a significant improvement on protein stability against thermal denaturation
up to 95degC at neutral pH, with little or no evidence of unfolding or reduced
enzymatic activity. The latter parameter does indeed exhibit an increase after
thermal cycling. Our results suggest that nanoscopic confinement is a promising
new avenue for the enhanced long-term storage of proteins. Moreover, our
investigations have potentially important implications for the origin of life,
since such compartmentalization may well have been critical for ensuring the
preservation of primordial functional proteins under relatively harsh
conditions, thus playing a key role in the subsequent emergence of primitive
life forms.


title: Two-Loop Scattering Amplitudes from the Riemann Sphere

abstract:
  The scattering equations give striking formulae for massless scattering
amplitudes at tree level and, as shown recently, at one loop. The progress at
loop level was based on ambitwistor string theory, which naturally yields the
scattering equations. We proposed that, for ambitwistor strings, the standard
loop expansion in terms of the genus of the worldsheet is equivalent to an
expansion in terms of nodes of a Riemann sphere, with the nodes carrying the
loop momenta. In this paper, we show how to obtain two-loop scattering
equations with the correct factorization properties. We adapt genus-two
integrands from the ambitwistor string to the nodal Riemann sphere and show
that these yield correct answers, by matching standard results for the
four-point two-loop amplitudes of maximal supergravity and super-Yang-Mills
theory. In the Yang-Mills case, this requires the loop analogue of the
Parke-Taylor factor carrying the colour dependence, which includes non-planar
contributions.


title:
The Effect of Cosmological Evolution on Solar System Constraints and on
  the Scalarization of Neutron Stars in Massless Scalar-Tensor Theories

abstract:
  Certain scalar-tensor theories of gravity that generalize
Jordan-Fierz-Brans-Dicke theory are known to predict non-trivial phenomenology
for neutron stars. In these theories, first proposed by Damour and
Esposito-Far\`ese, the scalar field has a standard kinetic term, and couples
conformally to the matter fields. The weak equivalence principle is therefore
satisfied, but scalar effects may arise in strong-field regimes, e.g. allowing
for violations of the strong equivalence principle in neutron stars
("spontaneous scalarization") or in sufficiently tight binary neutron-star
systems ("dynamical/induced scalarization"). The original scalar-tensor theory
proposed by Damour and Esposito-Far\`ese is in tension with solar-system
constraints (for couplings that lead to scalarization), if one accounts for
cosmological evolution of the scalar field and no mass term is included in the
action. We here extend the conformal coupling of that theory, in order to
ascertain if, in this way, solar-system tests can be passed, while retaining a
non-trivial phenomenology for neutron stars. We find that even with this
generalized conformal coupling, it is impossible to construct a theory that
passes both Big-Bang nucleosynthesis and solar-system constraints, while
simultaneously allowing for scalarization in isolated/binary neutron stars.


title:
On Hyperoctahedral Enumeration System, Application to Signed
  Permutations

abstract:
  In this paper, we start by giving the definitions and basic facts about
hyperoctahedral number system. There is a natural correspondence between the
integers expressed in the latter and the elements of the hyperoctahedral group
when we use the inversion statistic on this group to code the signed
permutations. We use this correspondence to define a way with which the signed
permutations group can be ordered. With this classification scheme, we can find
the r-th signed permutation from a given number r and vice versa without
consulting the list in lexicographical order of the elements of the signed
permutations group.


title: Percolation in photonic crystals revealed by Fano Resonance

abstract:
  The understanding of how the arrangement of defects in photonic crystals
impacts its photonic properties is cru-cial for the design of functional
materials based thereon. By preparing photonic crystals with random missing
scatterers we create crystals where disorder is embodied as vacancies in an
otherwise perfect lattice rather than the usual positional or size disorder. We
show that the amount of defects not only determines the intensity but also the
nature of the light scattering. As the amount of defects varies, light
scattering undergoes a transition whereby the usual signatures of photonic gaps
(Bragg peak) suffer line-shape changes (Bragg dip) that can be readily
described with the Fano resonance q parameter. When the amount of vacancies
reaches the percolation threshold, q undergoes a sign change signaling the
transition from a crystal to a mosaic of microcrystals through a state where
scattering is maximum. Beyond that point the system reenters a state of low
scattering that ap-pears in the guise of normal Bragg diffraction.


title:
Assessing Functional Neural Connectivity as an Indicator of Cognitive
  Performance

abstract:
  Studies in recent years have demonstrated that neural organization and
structure impact an individual's ability to perform a given task. Specifically,
individuals with greater neural efficiency have been shown to outperform those
with less organized functional structure. In this work, we compare the
predictive ability of properties of neural connectivity on a working memory
task. We provide two novel approaches for characterizing functional network
connectivity from electroencephalography (EEG), and compare these features to
the average power across frequency bands in EEG channels. Our first novel
approach represents functional connectivity structure through the distribution
of eigenvalues making up channel coherence matrices in multiple frequency
bands. Our second approach creates a connectivity network at each frequency
band, and assesses variability in average path lengths of connected components
and degree across the network. Failures in digit and sentence recall on single
trials are detected using a Gaussian classifier for each feature set, at each
frequency band. The classifier results are then fused across frequency bands,
with the resulting detection performance summarized using the area under the
receiver operating characteristic curve (AUC) statistic. Fused AUC results of
0.63/0.58/0.61 for digit recall failure and 0.58/0.59/0.54 for sentence recall
failure are obtained from the connectivity structure, graph variability, and
channel power features respectively.


title: High-precision theory for top-quark production

abstract:
  I present high-precision results for top quark production at hadron collider
energies. Total and differential cross sections are calculated through aN$^3$LO
for top-antitop pair production and through aNNLO for single-top production.
Top production in association with a charged Higgs boson and via anomalous
couplings is also briefly discussed.


title:
Effect of disorder on the competition between nematic and
  superconducting order in FeSe

abstract:
  Crystalline FeSe is known to display strong nematic order below a weak
tetragonal-orthorhombic structural transition around $T_s\sim 90$K, and a
superconducting transition at $T_c\sim 9K$. Recently, it was shown that
electron irradiation, which creates pointlike potential scattering defects, has
the surprising effect of enhancing $T_c$ while suppressing $T_s$. Here we
discuss a possible scenario for such an effect, which postulates a competition
between $s_\pm$ superconductivity and nematic order. The transition to the
nematic state is modeled by a mean field theory of a $d$-wave Pomeranchuk
instability, together with a Cooper pairing interaction in both one- and
multiband models. The effect of nonmagnetic impurities on both orders is
treated on equal footing within the Born approximation. We find evidence that
disorder can indeed enhance $T_c$ while suppressing the competition with
nematic order, but only in a multiband situation. We discuss our results in the
context of experimental data on FeSe crystals.


title:
Work producing reservoirs: Stochastic thermodynamics with generalized
  Gibbs ensembles

abstract:
  We develop a consistent stochastic thermodynamics for environments composed
of thermodynamic reservoirs in an external conservative force field, that is
environments described by the Generalized or Gibbs canonical ensemble. We
demonstrate that small systems weakly coupled to such reservoirs exchange both
heat and work by verifying a local detailed balance relation for the induced
stochastic dynamics. Based on this analysis, we help to rationalize the
observation that nonthermal reservoirs can increase the efficiency of
thermodynamic heat engines.


title: The power and production efficiency of blazar jets

abstract:
  We use published data on the power and production efficiency of jets in
blazars with double radio lobes in order to compare results obtained using
different methods. In order to eliminate selection effects, we use
cross-matched sub-samples containing only luminous blazars. We compare the
three main existing methods, namely those based on the emission of radio lobes,
on spectral fitting, and on radio core shift. We find the average jet power
obtained for identical samples with the radio-lobe method is $\sim10$ times
lower than that from the spectral fitting. In turn, the power from spectral
fitting is compatible with that from core-shift modelling for plausible
parameters of the latter. We also consider a phenomenological estimator based
on the {\gamma}-ray luminosity. We examine uncertainties of those methods and
discuss two alternative hypotheses. In one, the blazar-fit and core-shift
methods are assumed to be correct, and the lower power from radio lobes is
caused by intermittency of accretion. Long periods of quiescence cause the
energy in the radio lobes, accumulated over the lifetime of the blazar, to be
much less than that estimated based on the present luminous state. In addition,
the power calculated using the radio lobes can be underestimated for
intrinsically compact jets, in which the radio core flux can be
over-subtracted. In our second hypothesis, the radio-lobe method is assumed to
be correct, and the blazar-fit and core-shift powers are reduced due to the
presence of $\sim15$ pairs per proton, and a larger magnetization than usually
assumed, respectively.


title: A comparison of non-stationary stochastic lot-sizing strategies

abstract:
  We consider the non-stationary stochastic lot sizing problem with backorder
costs and make a cost comparison among different lot-sizing strategies. We
initially provide an overview of the strategies and some corresponding solution
approaches in the literature. We then compare the cost performances of the
lot-sizing strategies on a common test bed while taking into account the added
value of realized demand information. The results of this numerical experience
enable us to derive novel insights about the cost performance of different
stochastic lot-sizing strategies under re-planning with respect to demand
realization.


title: Sharp magnetic structures from dynamos with density stratification

abstract:
  Recent direct numerical simulations (DNS) of large-scale turbulent dynamos in
strongly stratified layers have resulted in surprisingly sharp bipolar
structures at the surface. Here we present new DNS of helically and
non-helically forced turbulence with and without rotation and compare with
corresponding mean-field simulations (MFS) to show that these structures are a
generic outcome of a broader class of dynamos in density-stratified layers. The
MFS agree qualitatively with the DNS, but the period of oscillations tends to
be longer in the DNS. In both DNS and MFS, the sharp structures are produced by
converging flows at the surface and might be driven in nonlinear stage of
evolution by the Lorentz force associated with the large-scale dynamo-driven
magnetic field if the dynamo number is at least 2.5 times supercritical.


title: Personalized Emphasis Framing for Persuasive Message Generation

abstract:
  In this paper, we present a study on personalized emphasis framing which can
be used to tailor the content of a message to enhance its appeal to different
individuals. With this framework, we directly model content selection decisions
based on a set of psychologically-motivated domain-independent personal traits
including personality (e.g., extraversion and conscientiousness) and basic
human values (e.g., self-transcendence and hedonism). We also demonstrate how
the analysis results can be used in automated personalized content selection
for persuasive message generation.


title:
Boundary convex cocompactness and stability of subgroups of finitely
  generated groups

abstract:
  A Kleinian group $\Gamma < \mathrm{Isom}(\mathbb H^3)$ is called convex
cocompact if any orbit of $\Gamma$ in $\mathbb H^3$ is quasiconvex or,
equivalently, $\Gamma$ acts cocompactly on the convex hull of its limit set in
$\partial \mathbb H^3$. Subgroup stability is a strong quasiconvexity condition
in finitely generated groups which is intrinsic to the geometry of the ambient
group and generalizes the classical quasiconvexity condition above.
Importantly, it coincides with quasiconvexity in hyperbolic groups and convex
cocompactness in mapping class groups. Using the Morse boundary, we develop an
equivalent characterization of subgroup stability which generalizes the above
boundary characterization from Kleinian groups.


title:
Microwave Admittance of Gold-Palladium Nanowires with Proximity-Induced
  Superconductivity

abstract:
  We report quantitative electrical admittance measurements of diffusive
superconductor--normal-metal--superconductor (SNS) junctions at gigahertz
frequencies and millikelvin temperatures. The gold-palladium-based SNS
junctions are arranged into a chain of superconducting quantum interference
devices. The chain is coupled strongly to a multimode microwave resonator with
a mode spacing of approximately 0.6 GHz. By measuring the resonance frequencies
and quality factors of the resonator modes, we extract the dissipative and
reactive parts of the admittance of the chain. We compare the phase and
temperature dependence of the admittance near 1 GHz to theory based on the
time-dependent Usadel equations. This comparison allows us to identify
important discrepancies between theory and experiment that are not resolved by
including inelastic scattering or elastic spin-flip scattering in the theory.


title: Integrand reduction beyond one-loop calculations

abstract:
  In this presentation, we review the general features of integrand-reduction
techniques, with a particular focus on their generalization beyond one loop. We
start with a brief discussion of the one-loop scenario, a case in which
integrand-reduction algorithms are well established and played over the past
decade an important role in the development of automated tools for the
theoretical evaluation of physical observables. The generalization of
integrand-reduction techniques to all loops has been the subject of several
efforts in the recent past, thus providing a better understanding of the
universal properties of scattering amplitudes. The ultimate goal of these
studies is the development of efficient alternative computational techniques
for the evaluation of Feynman integrals beyond one loop.


title:
On the virtual levels of positively projected massless Coulomb-Dirac
  operators

abstract:
  Considering different self-adjoint realisations of positively projected
massless Coulomb-Dirac operators we find out, under which conditions any
negative perturbation, however small, leads to emergence of negative spectrum.
We also prove some weighted Lieb-Thirring estimates for negative eigenvalues of
such operators. In the process we find explicit spectral representations for
all self-adjoint realisations of massless Coulomb-Dirac operators on the
half-line.

categories: math-ph math.CA math.MP math.SP quant-ph


title: On the growth of Sobolev norms for NLS on $2d$ and $3d$ manifolds

abstract:
  Using suitable modified energies we study higher order Sobolev norms' growth
in time for the nonlinear Schr\"odinger equation (NLS) on a generic $2d$ or
$3d$ compact manifold. In $2d$ we extend earlier results that dealt only with
cubic nonlinearities, and get polynomial in time bounds for any higher order
nonlinearities. In $3d$, we prove that solutions to the cubic NLS grow at most
exponentially, while for sub-cubic NLS we get polynomial bounds on the growth
of the $H^2$-norm.


title: Asymptotic Enumeration of Difference Matrices over Cyclic Groups

abstract:
  We identify a relationship between a certain family of random walks on
Euclidean lattices and difference matrices over cyclic groups. We then use the
techniques of Fourier analysis to estimate the return probabilities of these
random walks, which in turn yields the asymptotic number of difference matrices
over cyclic groups as the number of columns increases.


title: Complexity of Discrete Energy Minimization Problems

abstract:
  Discrete energy minimization is widely-used in computer vision and machine
learning for problems such as MAP inference in graphical models. The problem,
in general, is notoriously intractable, and finding the global optimal solution
is known to be NP-hard. However, is it possible to approximate this problem
with a reasonable ratio bound on the solution quality in polynomial time? We
show in this paper that the answer is no. Specifically, we show that general
energy minimization, even in the 2-label pairwise case, and planar energy
minimization with three or more labels are exp-APX-complete. This finding rules
out the existence of any approximation algorithm with a sub-exponential
approximation ratio in the input size for these two problems, including
constant factor approximations. Moreover, we collect and review the
computational complexity of several subclass problems and arrange them on a
complexity scale consisting of three major complexity classes -- PO, APX, and
exp-APX, corresponding to problems that are solvable, approximable, and
inapproximable in polynomial time. Problems in the first two complexity classes
can serve as alternative tractable formulations to the inapproximable ones.
This paper can help vision researchers to select an appropriate model for an
application or guide them in designing new algorithms.


title:
From the pion cloud of Tomonaga to the electron pairs of Schrieffer:
  many body wave functions from nuclear physics to condensed matter physics

abstract:
  It is well known that diverse pieces of models and physical ideas coming from
different areas of physics converged in the BCS theory of superconductivity. On
the contrary it is little known that the formalism developed in the Tomonaga
quantum field theory of the pion-nucleon system was an important ingredient for
the development of BCS theory. We discuss the evolution of these ideas in
quantum field theory providing an unconventional historical perspective.


title: A note on strongly real Beauville $p$-groups

abstract:
  We give an infinite family of non-abelian strongly real Beauville $p$-groups
for any odd prime $p$ by considering the lower central quotients of the free
product of two cyclic groups of order $p$. This is the first known infinite
family of non-abelian strongly real Beauville $p$-groups.


title: From tensor category to Temperley-Lieb algebra representation

abstract:
  We construct a representation of the Temperley-Lieb algebra from a
multiplicity-free semisimple monoidal Abelian category ${\cal C}$, with two
simple objects $\lambda$ and $\nu$ such that $\lambda\otimes\nu$ is simple and
Hom$_{\cal C}(\lambda\otimes \lambda, \nu)$ is not empty. A self-contained
manual to tensor categories is also provided as well as a summary of the best
known example of the construction: Schur-Weyl duality for $U_q(sl_2))$.


title:
Particle representations for stochastic partial differential equations
  with boundary conditions

abstract:
  In this article, we study a weighted particle representation for a class of
stochastic partial differential equations with Dirichlet boundary conditions.
The locations and weights of the particles satisfy an infinite system of
stochastic differential equations (SDEs). The evolution of the particles is
modeled by an infinite system of stochastic differential equations with
reflecting boundary condition and driven by independent finite dimensional
Brownian motions. The weights of the particles evolve according to an infinite
system of stochastic differential equations driven by a common cylindrical
noise $W$ and interact through $V$, the associated weighted empirical measure.
When the particles hit the boundary their corresponding weights are assigned a
pre-specified value. We show the existence and uniqueness of a solution of the
infinite dimensional system of stochastic differential equations modeling the
location and the weights of the particles. We also prove that the associated
weighted empirical measure $V$ is the unique solution of a nonlinear stochastic
partial differential equation driven by $W$ with Dirichlet boundary condition.
The work is motivated by and applied to the stochastic Allen-Cahn equation and
extends the earlier of work of Kurtz and Xiong.


title: Burstiness and tie reinforcement in time varying social networks

abstract:
  We introduce a time-varying network model accounting for burstiness and tie
reinforcement observed in social networks. The analytical solution indicates a
non-trivial phase diagram determined by the competition of the leading terms of
the two processes. We test our results against numerical simulations, and
compare the analytical predictions with an empirical dataset finding good
agreements between them. The presented framework can be used to classify the
dynamical features of real social networks and to gather new insights about the
effects of social dynamics on ongoing spreading processes.


title: Traces of a triboson resonance

abstract:
  We show that the relatively small but coincident excesses observed around 2
TeV in the ATLAS Run 1 and Run 2 hadronic diboson searches --- when a cut on
the number of tracks in the fat jets is not applied --- and the null results of
all remaining high-mass diboson searches are compatible with the decay of a
triboson resonance $R$ into $WZ$ plus an extra particle $X$. These decays can
take place via new neutral ($Y^0$) or charged ($Y^\pm$) particles, namely $R
\to Y^0 \, W$, with $Y^0 \to Z X$, or $R \to Y^\pm Z$, with $Y^\pm \to W X$. An
obvious candidate for such intermediate particle is a neutral one $Y^0$, given
a $3.9\sigma$ excess found at 650 GeV by the CMS Collaboration in searches for
intermediate mass diboson resonances decaying to $ZV$, with $V=W,Z$. We discuss
discovery strategies for triboson resonances with small modifications of
existing hadronic searches.


title: The relevance of ambipolar diffusion for neutron star evolution

abstract:
  We study ambipolar diffusion in strongly magnetised neutron stars, with
special focus on the effects of neutrino reaction rates and the impact of a
superfluid/superconducting transition in the neutron star core. For
axisymmetric magnetic field configurations, we determine the deviation from
$\beta-$equilibrium induced by the magnetic force and calculate the velocity of
the slow, quasi-stationary, ambipolar drift. We study the temperature
dependence of the velocity pattern and clearly identify the transition to a
predominantly solenoidal flow. For stars without superconducting/superfluid
constituents and with a mixed poloidal-toroidal magnetic field of typical
magnetar strength, we find that ambipolar diffusion proceeds fast enough to
have a significant impact on the magnetic field evolution only at low core
temperatures, $T \lesssim 1-2\times10^8$ K. The ambipolar diffusion timescale
becomes appreciably shorter when fast neutrino reactions are present, because
the possibility to balance part of the magnetic force with pressure gradients
is reduced. We also find short ambipolar diffusion timescales in the case of
superconducting cores for $T \lesssim 10^9$ K, due to the reduced interaction
between protons and neutrons. In the most favourable scenario, with fast
neutrino reactions and superconducting cores, ambipolar diffusion results in
advection velocities of several km/kyr. This velocity can substantially
reorganize magnetic fields in magnetar cores, in a way that can only be
confirmed by dynamical simulations.


title: Alternative Self-dual Gravity in Eight Dimensions

abstract:
  We develop an alternative Ashtekar formalism in eight dimensions. In fact,
using a MacDowell-Mansouri physical framework and a self-dual curvature
symmetry we propose an action in eight dimensions in which the Levi-Civita
tenor with eight indices plays a key role. We explicitly show that such an
action contains number of linear, quadratic and cubic terms in the Riemann
tensor, Ricci tensor and scalar curvature. In particular, the linear term is
reduced to the Einstein-Hilbert action with cosmological constant in eight
dimensions. We prove that such a reduced action is equivalent to the Lovelock
action in eight dimensions.


title:
The Density of Dark Matter in the Galactic Bulge and Implications for
  Indirect Detection

abstract:
  A recent study, making use of the number of horizontal branch stars observed
in infrared photometric surveys and kinematic measurements of M-giant stars
from the BRAVA survey, combined with N-body simulations of stellar populations,
has presented a new determination of the dark matter mass within the bulge-bar
region of the Milky Way. That study constrains the total mass within the $\pm
2.2 \times \pm 1.4 \times \pm 1.2$ kpc volume of the bulge-bar region to be
($1.84 \pm 0.07) \times 10^{10} \, M_{\odot}$, of which 9-30% is made up of
dark matter. Here, we use this result to constrain the the Milky Way's dark
matter density profile, and discuss the implications for indirect dark matter
searches. Although uncertainties remain significant, these results favor dark
matter distributions with a cusped density profile. For example, for a scale
radius of 20 kpc and a local dark matter density of 0.4 GeV/cm$^3$, density
profiles with an inner slope of 0.69 to 1.40 are favored, approximately
centered around the standard NFW value. In contrast, profiles with large
flat-density cores are disfavored by this information.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ph


title:
Searching for Cosmic Strings in CMB Anisotropy Maps using Wavelets and
  Curvelets

abstract:
  We use wavelet and curvelet transforms to extract signals of cosmic strings
from cosmic microwave background (CMB) temperature anisotropy maps, and to
study the limits on the cosmic string tension which various ongoing CMB
temperature anisotropy experiments will be able to achieve. We construct sky
maps with size and angular resolution corresponding to various experiments.
These maps contain the signals of a scaling solution of long string segments
with a given string tension $G \mu$, the contribution of the dominant Gaussian
primordial cosmological fluctuations, and pixel by pixel white noise with an
amplitude corresponding to the instrumental noise of the various experiments.
In the case that we include white noise, we find that the curvelets are more
powerful than wavelets. For maps with Planck specification, we obtain bounds on
the string tension comparable to what was obtained by the Planck collaboration.
Experiments with better angular resolution such as the South Pole Telescope
third generation (SPT-3G) survey will be able to yield stronger limits. For
maps with a specification of SPT-3G we find that string signals will be visible
down to a string tension of $G \mu = 1.4 \times 10^{-7}$.


title:
Connecting the dots: a correlation between ionising radiation and cloud
  mass-loss rate traced by optical integral field spectroscopy

abstract:
  We present an analysis of the effect of feedback from O- and B-type stars
with data from the integral field spectrograph MUSE mounted on the Very Large
Telescope of pillar-like structures in the Carina Nebular Complex, one of the
most massive star-forming regions in the Galaxy. For the observed pillars, we
compute gas electron densities and temperatures maps, produce integrated line
and velocity maps of the ionised gas, study the ionisation fronts at the pillar
tips, analyse the properties of the single regions, and detect two ionised jets
originating from two distinct pillar tips. For each pillar tip we determine the
incident ionising photon flux $Q_\mathrm{0,pil}$ originating from the nearby
massive O- and B-type stars and compute the mass-loss rate $\dot{M}$ of the
pillar tips due to photo-evaporation caused by the incident ionising radiation.
We combine the results of the Carina data set with archival MUSE data of a
pillar in NGC 3603 and with previously published MUSE data of the Pillars of
Creation in M16, and with a total of 10 analysed pillars, find tight
correlations between the ionising photon flux and the electron density, the
electron density and the distance from the ionising sources, and the ionising
photon flux and the mass-loss rate. The combined MUSE data sets of pillars in
regions with different physical conditions and stellar content therefore yield
an empirical quantification of the feedback effects of ionising radiation. In
agreement with models, we find that $\dot{M}\propto Q_\mathrm{0,pil}^{1/2}$.


title:
Manifesting Color-Kinematics Duality in the Scattering Equation
  Formalism

abstract:
  We prove that the scattering equation formalism for Yang-Mills amplitudes can
be used to make manifest the theory's color-kinematics duality. This is
achieved through a concrete reduction algorithm which renders this duality
manifest term-by-term. The reduction follows from the recently derived set of
identities for amplitudes expressed in the scattering equation formalism that
are analogous to monodromy relations in string theory. A byproduct of our
algorithm is a generalization of the identities among gravity and Yang-Mills
amplitudes.


title:
Constraints on the evolution of the relationship between HI mass and
  halo mass in the last 12 Gyr

abstract:
  The neutral hydrogen (HI) content of dark matter haloes forms an intermediate
state in the baryon cycle that connects the hot shock-heated gas and cold
star-forming gas in haloes. Measurement of the relationship between HI mass and
halo mass therefore puts important constraints on galaxy formation models. We
combine radio observations of HI in emission at low redshift ($z\sim 0$) with
optical/UV observations of HI in absorption at high redshift ($1<z<4$) to
derive constraints on the evolution of the HI-mass halo-mass (HIHM) relation
from redshift $z=4$ to $z=0$. We find that one can model the HIHM relation
similar to the stellar-mass halo-mass (SHM) relation at $z \sim 0$. At $z=0$,
haloes with mass $10^{11.7}$ M$_\odot$ have the highest HI mass fraction ($\sim
1\%$), which is about four times smaller than their stellar mass fraction. We
model the evolution of the HIHM relation in a manner similar to that of the SHM
relation. Combining this parameterisation with a redshift- and mass-dependent
modified Navarro-Frenk-White (NFW) profile for the HI density within a halo, we
draw constraints on the evolution of the HIHM relation from the observed HI
column density, incidence rate, and clustering bias at high redshift. We
compare these findings with results from hydrodynamical simulations and other
approaches in the literature, and find the models to be consistent with each
other at the $68\%$ confidence level.


title: Semi-analytic techniques for calculating bubble wall profiles

abstract:
  We present semi-analytic techniques for finding bubble wall profiles during
first order phase transitions with multiple scalar fields. Our method involves
reducing the problem to an equation with a single field, finding an analytic
solution and perturbing around it. The perturbations can be written in a
semi-analytic form. We argue that our technique lacks convergence problems and
demonstrate the speed of convergence on an example potential.


title: Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMA

abstract:
  High-mass stars shape the interstellar medium in galaxies, and yet, largely
because the initial conditions are poorly constrained, we do not know how they
form. One possibility is that high-mass stars and star clusters form at the
junction of filamentary networks, referred to as 'hubs'. In this letter we
present the complex anatomy of a protocluster hub within an Infrared Dark Cloud
(IRDC), G035.39-00.33, believed to be in an early phase of its evolution. We
use high-angular resolution ($\{\theta_{\rm maj}, \theta_{\rm min}\}=\{1.4{\rm
arcsec}, 0.8{\rm arcsec}\}\sim\{0.02{\rm pc}, 0.01{\rm pc}\}$) and
high-sensitivity ($0.2$mJy beam$^{-1}$; $\sim0.2$M$_{\odot}$) 1.07 mm dust
continuum observations from the Atacama Large Millimeter Array (ALMA) to
identify a network of narrow, $0.028\,\pm\,0.005$pc wide, filamentary
structures. These are a factor of $\gtrsim3$ narrower than the proposed
'quasi-universal' $\sim0.1$pc width of interstellar filaments. Additionally, 28
compact objects are reported, spanning a mass range $0.3{\rm M_{\odot}}<M_{\rm
c}<10.4{\rm M_{\odot}}$. This indicates that at least some low-mass objects are
forming coevally with more massive counterparts. Comparing to the popular
'bead-on-a-string' analogy, the protocluster hub is poorly represented by a
monolithic clump embedded within a single filament. Instead, it comprises
multiple intra-hub filaments, each of which retains its integrity as an
independent structure and possesses its own embedded core population.


title:
Kinetics and mechanisms of the acid-base reaction between NH$_3$ and
  HCOOH in interstellar ice analogs

abstract:
  Interstellar complex organic molecules (COMs) are commonly observed during
star formation, and are proposed to form through radical chemistry in icy grain
mantles. Reactions between ions and neutral molecules in ices may provide an
alternative cold channel to complexity, as ion-neutral reactions are thought to
have low or even no energy barriers. Here we present a study of a the kinetics
and mechanisms of a potential ion-generating acid-base reaction between
NH$_{3}$ and HCOOH to form the salt NH$_{4}^{+}$HCOO$^{-}$. We observe salt
growth at temperatures as low as 15K, indicating that this reaction is feasible
in cold environments. The kinetics of salt growth are best fit by a two-step
model involving a slow "pre-reaction" step followed by a fast reaction step.
The reaction energy barrier is determined to be 70 $\pm$ 30K with a
pre-exponential factor 1.4 $\pm$ 0.4 x 10$^{-3}$ s$^{-1}$. The pre-reaction
rate varies under different experimental conditions and likely represents a
combination of diffusion and orientation of reactant molecules. For a
diffusion-limited case, the pre-reaction barrier is 770 $\pm$ 110K with a
pre-exponential factor of $\sim$7.6 x 10$^{-3}$ s$^{-1}$. Acid-base chemistry
of common ice constituents is thus a potential cold pathway to generating ions
in interstellar ices.


title: Charged Proca Stars

abstract:
  In this paper, we study gauged solutions associated to a massive vector field
representing a spin-one condensate, namely the Proca field. We focus on regular
spherically-symmetric solutions which we construct either using a
self-interaction potential or general relativity in order to glue the solutions
together. We start generating non-gravitating solutions, so-called, Proca
Q-balls and charged Proca Q-balls. Then, we turn-on backreaction on the metric,
allowing gravity to hold together the Proca condensate, to study the so-called
Proca stars, charged Proca stars, Proca Q-stars and charged Proca Q-stars.


title:
Chemical Abundances of Seven Outer Halo M31 Globular Clusters from the
  Pan-Andromeda Archaeological Survey

abstract:
  Observations of stellar streams in M31's outer halo suggest that M31 is
actively accreting several dwarf galaxies and their globular clusters (GCs).
Detailed abundances can chemically link clusters to their birth environments,
establishing whether or not a GC has been accreted from a satellite dwarf
galaxy. This talk presents the detailed chemical abundances of seven M31 outer
halo GCs (with projected distances from M31 greater than 30 kpc), as derived
from high-resolution integrated-light spectra taken with the Hobby Eberly
Telescope. Five of these clusters were recently discovered in the Pan-Andromeda
Archaeological Survey (PAndAS)---this talk presents the first determinations of
integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters.
Four of the target clusters (PA06, PA53, PA54, and PA56) are metal-poor
($[\rm{Fe/H}] < -1.5$), $\alpha$-enhanced (though they are possibly less
alpha-enhanced than Milky Way stars at the 1 sigma level), and show signs of
star-to-star Na and Mg variations. The other three GCs (H10, H23, and PA17) are
more metal-rich, with metallicities ranging from [Fe/H] = -1.4 to -0.9. While
H23 is chemically similar to Milky Way field stars, Milky Way GCs, and other
M31 clusters, H10 and PA17 have moderately-low [Ca/Fe], compared to Milky Way
field stars and clusters. Additionally, PA17's high [Mg/Ca] and [Ba/Eu] ratios
are distinct from Milky Way stars, and are in better agreement with the stars
and clusters in the Large Magellanic Cloud (LMC). None of the clusters studied
here can be conclusively linked to any of the identified streams from PAndAS;
however, based on their locations, kinematics, metallicities, and detailed
abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated
with the progenitor of the Giant Stellar Stream, H10 may be associated with the
SW Cloud, and PA53 and PA56 may be associated with the Eastern Cloud.


title:
OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental
  Mode RR Lyrae Stars

abstract:
  In an era of extensive photometric observations, the catalogs of RR Lyr type
variable stars number tens of thousands of objects. The relation between the
iron abundance [Fe/H] and the Fourier parameters of the stars light curve
allows us to investigate mean metallicities and metallicity gradients in
various stellar environments, independently of time-consuming spectroscopic
observations. In this paper we use almost 6500 $V$- and $I$-band light curves
of fundamental mode RR Lyr stars from the OGLE-IV survey to provide a relation
between the $V$- and $I$-band phase parameter $\varphi_{31}$ used to estimate
[Fe/H]. The relation depends on metallicity, which limits its applicability. We
apply this relation to metallicity formulae developed for the Johnson $V$- and
the Kepler $Kp$-band to obtain the relation between [Fe/H] and $\varphi_{31}$
for the $I$-band photometry. Last, we apply the new relation of Nemec to the
OGLE-IV fundamental mode RR Lyr stars data and construct a metallicity map of
the Magellanic Clouds. Median [Fe/H] is $-1.39\pm0.44$ dex for the LMC and
$-1.77\pm0.48$ dex for the SMC, on the Jurcsik metallicity scale. We also find
a metallicity gradient within the LMC with a slope of $-0.029\pm0.002$ dex/kpc
in the inner 5 kpc and $-0.030 \pm0.003$ dex/kpc beyond 8 kpc, and no gradient
in-between ($-0.019\pm0.002$ dex/kpc integrally). We do not observe a
metallicity gradient in the SMC, although we show that the metal-rich RRab
stars are more concentrated toward the SMC center than the metal-poor.


title:
Open charm production in Double Parton Scattering processes in the
  forward kinematics

abstract:
  We calculate the rate of double open charm production in the forward
kinematics studied recently in the LHCb experiment. We find that the mean field
approximation for the double parton GPD (Generalized parton distributions),
which neglects parton - parton correlations, underestimates the rate by a
factor of two. The enhancement due to the perturbative QCD correlation \12
mechanism which explains the rate of double parton interactions at the central
rapidities is found to explain 60 $\div$ 80 \% of the discrepancy. We argue
that the nonperturbative fluctuations leading to non-factorized (correlated)
contributions to the initial conditions for the DGLAP collinear evolution of
the double parton GPD play an important role in this kinematics. Combined, the
two correlation mechanisms provide a good description of the rate of double
charm production reported by the LHCb. We also give predictions for the
variation of the \effs (i.e. the ratio of double and square of single inclusive
rates) in the discussed kinematics as a function of $p_t$. The account for two
correlation mechanisms strongly reduces sensitivity of the results to the
starting point of the QCD evolution.


title:
Galois groups for integrable and projectively integrable linear
  difference equations

abstract:
  We consider first-order linear difference systems over $\mathbb{C}(x)$, with
respect to a difference operator $\sigma$ that is either a shift
$\sigma:x\mapsto x+1$, $q$-dilation $\sigma:x\mapsto qx$ with
$q\in{\mathbb{C}^\times}$ not a root of unity, or Mahler operator
$\sigma:x\mapsto x^q$ with $q\in\mathbb{Z}_{\geq 2}$. Such a system is
integrable if its solutions also satisfy a linear differential system; it is
projectively integrable if it becomes integrable "after moding out by scalars."
We apply recent results of Sch\"{a}fke and Singer to characterize which groups
can occur as Galois groups of integrable or projectively integrable linear
difference systems. In particular, such groups must be solvable. Finally, we
give hypertranscendence criteria.


title:
Network analysis method: correlation values between two arbitrary points
  on a network

abstract:
  This study presents a generalization for a method examining the correlation
function of an arbitrary system with interactions in an Ising model to obtain a
value of correlation between two arbitrary points on a network. The
establishment of a network clarifies the type of calculations necessary for the
correlation values between secondary and tertiary nodes. Moreover, it is
possible to calculate the correlation values of the target that are interlinked
in a complex manner by proposing a network analysis method to express the same
as a network with mutual linkages between the target of each field.


title:
Electromagnetic ion-cyclotron instability in a dusty plasma with
  product-bi-kappa distributions for the plasma particles

abstract:
  We study the dispersion relation for parallel propagating ion-cyclotron (IC)
waves in a dusty plasma, considering situations where the velocity dispersion
along perpendicular direction is greater than along the parallel direction, and
considering the use of product-bi-kappa (PBK) velocity distributions for the
plasma particles. The results obtained by numerical solution of the dispersion
relation, in a case with isotropic Maxwellian distributions for electrons and
PBK distribution for ions, show the occurrence of the electromagnetic
ion-cyclotron instability (EMIC), and show that the decrease in the kappa
indexes of the PBK ion distribution leads to significant increase in the
magnitude of the growth rates and in the range of wavenumber for which the
instability occurs. On the other hand, for anisotropic Maxwellian distribution
for ions and PBK distribution for electrons, the decrease of the kappa index in
the PBK electron distribution contributes to reduce the growth rate of the EMIC
instability, but the reduction effect is less pronounced than the increase
obtained with ion PBK distribution with the same $\kappa$ index. The results
obtained also show that, as a general rule, the presence of a dust population
contributes to reduce the instability in magnitude of the growth rates and
range, but that in the case of PBK ion distribution with small kappa indexes
the instability may continue to occur for dust populations which would
eliminate completely the instability in the case of bi-Maxwellian ion
distributions. It has also been seen that the anisotropy due to the kappa
indexes in the ion PBK distribution is not so efficient in producing the EMIC
instability as the ratio of perpendicular and parallel ion temperatures, for
equivalent value of the effective temperature.


title: Instantons on multi-Taub-NUT Spaces I: Asymptotic Form and Index Theorem

abstract:
  We study finite action anti-self-dual Yang-Mills connections on the
multi-Taub-NUT space. We establish the curvature and the harmonic spinors decay
rates and compute the index of the associated Dirac operator.
  This is the first in a series of papers proving the completeness of the bow
construction of instantons on multi-Taub-NUT spaces and exploring it in detail.


title: Natural properties of the trunk of a knot

abstract:
  The trunk of a knot in $S^3$, defined by Makoto Ozawa, is a measure of
geometric complexity similar to the bridge number or width of a knot. We prove
that for any two knots $K_1$ and $K_2$, we have $tr(K_1 \# K_2) =
\max\{tr(K_1),tr(K_2)\}$, confirming a conjecture of Ozawa. Another conjecture
of Ozawa asserts that any width-minimizing embedding of a knot $K$ also
minimizes the trunk of $K$. We produce several families of probable
counterexamples to this conjecture.


title: An inexact potential reduction method for linear programming

abstract:
  A class of interior point methods using inexact directions is analysed. The
linear system arising in interior point methods for linear programming is
reformulated such that the solution is less sensitive to perturbations in the
right-hand side. For the new system an implementable condition is formulated
that controls the relative error in the solution. Based on this condition, a
feasible and an infeasible potential reduction method are described which
retain the convergence and complexity bounds known for exact directions.


title:
Vortices and magnetic bags in Abelian models with extended scalar
  sectors and some of their applications

abstract:
  A detailed study of vortices is presented in Ginzburg-Landau (or Abelian
Higgs) models with two complex scalars (order parameters) assuming a general
U(1)$\times$U(1) symmetric potential. Particular emphasis is given to the case,
when only one of the scalars obtains a vacuum expectation value (VEV). It is
found that for a significantly large domain in parameter space vortices with a
scalar field condensate in their core (condensate core, CC) coexist with
Abrikosov-Nielsen-Olesen (ANO) vortices. Importantly CC vortices are stable and
have lower energy than the ANO ones. Magnetic bags or giant vortices of the
order of 1000 flux quanta are favoured to form for the range of parameters
("strong couplings") appearing for the superconducting state of liquid metallic
hydrogen (LMH). Furthermore, it is argued that finite energy/unit length 1VEV
vortices are smoothly connected to fractional flux 2VEV ones. Stable, finite
energy CC-type vortices are also exhibited in the case when one of the scalar
fields is neutral.


title: Non-local response in the disordered Majorana chain

abstract:
  The prospects for realizing a topological quantum computer have brightened
since the apparent detection of Majorana fermions at the ends of semiconducting
nanowires. These Majorana zero-modes persist in the presence of the strong
disorder that may be present in such systems, protected by the mobility gap of
localized systems. Recent proposals to manipulate quantum information in a
Majorana chain involve adiabatically adjusting gate voltages in one-dimensional
nanowire networks. However, as we show, in the adiabatic limit, a disordered
system with multiple zero-mode Majorana fermions will undergo a non-local
response to a local perturbation via a multi-level Landau-Zener transition.
This will disperse the quantum information stored in the target zero-modes
amongst other zero-modes that are present in the system, complicating the
realization of controlled gates. There is however a solution that may work in
practice: we show that there is an optimum window of intermediate time-scales
during which the quantum information is approximately preserved under
manipulation.


title:
Cooper pair splitting efficiency in the hybrid three-terminal quantum
  dot

abstract:
  Nanodevices consisting of a quantum dot tunnel coupled to one superconducting
and two normal electrodes may serve as a source of entangled electrons. As a
result of crossed Andreev reflection the Cooper pair of s-wave character may be
split into two electrons and each of them goes into a distinct normal
electrode, preserving entanglement. Efficiency of the process depends on the
specific system and is tunable by electric means. Our calculations show that in
the studied device this efficiency may attain values as large as $80 \%$.


title: On nearly linear recurrence sequences

abstract:
  A nearly linear recurrence sequence (nlrs) is a complex sequence $(a_n)$ with
the property that there exist complex numbers $A_0$,$\ldots$, $A_{d-1}$ such
that the sequence $\big(a_{n+d}+A_{d-1}a_{n+d-1}+\cdots
+A_0a_n\big)_{n=0}^{\infty}$ is bounded. We give an asymptotic Binet-type
formula for such sequences. We compare $(a_n)$ with a natural linear recurrence
sequence (lrs) $(\tilde{a}_n)$ associated with it and prove under certain
assumptions that the difference sequence $(a_n- \tilde{a}_n)$ tends to
infinity. We show that several finiteness results for lrs, in particular the
Skolem-Mahler-Lech theorem and results on common terms of two lrs, are not
valid anymore for nlrs with integer terms. Our main tool in these
investigations is an observation that lrs with transcendental terms may have
large fluctuations, quite different from lrs with algebraic terms. On the other
hand we show under certain hypotheses, that though there may be infinitely many
of them, the common terms of two nlrs are very sparse. The proof of this result
combines our Binet-type formula with a Baker type estimate for logarithmic
forms.


title:
Floquet Engineering of Haldane Chern Insulators and Chiral bosonic phase
  transitions

abstract:
  The realization of synthetic gauge fields has attracted a lot of attention
recently in relation with periodically driven systems and the Floquet theory.
In ultra-cold atom systems in optical lattices and photonic networks, this
allows to simulate exotic phases of matter such as quantum Hall phases,
anomalous quantum Hall phases and analogs of topological insulators. In this
paper, we apply the Floquet theory to engineer anisotropic Haldane models on
the honeycomb lattice and two-leg ladder systems. We show that these
anisotropic Haldane models still possess a topologically non-trivial band
structure associated with chiral edge modes (without the presence of a net unit
flux in a unit cell), then referring to the quantum anomalous Hall effect.
Focusing on (interacting) boson systems in s-wave bands of the lattice, we show
how to engineer through the Floquet theory, a quantum phase transition between
a uniform superfluid and a BEC (Bose-Einstein Condensate) analog of FFLO
(Fulde-Ferrell-Larkin-Ovchinnikov) states, where bosons condense at non-zero
wave-vectors. We perform a Ginzburg-Landau analysis of the quantum phase
transition on the graphene lattice, and compute observables such as chiral
currents and the momentum distribution. The results are supported by exact
diagonalization calculations and compared with those of the isotropic
situation. The validity of high-frequency expansion in the Floquet theory is
also tested using time-dependent simulations for various parameters of the
model. Last, we show that the anisotropic choice for the effective vector
potential allows a bosonization approach in equivalent ladder (strip)
geometries.


title: WD 1145+017 Photometric Observations During 8 Months of High Activity

abstract:
  WD 1145+017 was observed from 2015 November to 2016 July for the purpose of
characterizing transit behavior of the white dwarf by dust clouds thought to be
produced by fragments of an asteroid in close orbit with the star.
Fortuitously, most of these observations were carried out during a time when
the overall `dip' activity was dramatically enhanced over that during its
discovery with Kepler K2. By the end of our reported observations the dip
activity had declined to a level close to its K2 discovery state. Three notable
events were observed. In 2016 January a large number of dust clouds appeared
that had an orbital period of 4.4912 hours, and this event also marked the end
of a 3-month interval dominated by the K2 `A' period. The second event was a
2016 April 21 appearance of four dip features with drift lines in a waterfall
diagram (date vs. phase) that diverged from their origin date, at a location
away from the `A' asteroid, and which lasted for two weeks. The third event was
the sudden appearance of a dip feature with a period of 4.6064 hours, which is
essentially the same as the K2 `B' period. The evolution of dip shape, depth,
and total fade amount provide constraints on dust production and loss
mechanisms. Collisions can account for the sudden appearance of dust clouds,
and the sudden increase in dust amount, but another mechanism for continual
dust production is also required.


title:
gLOP: the global and Local Penalty for Capturing Predictive
  Heterogeneity

abstract:
  When faced with a supervised learning problem, we hope to have rich enough
data to build a model that predicts future instances well. However, in
practice, problems can exhibit predictive heterogeneity: most instances might
be relatively easy to predict, while others might be predictive outliers for
which a model trained on the entire dataset does not perform well. Identifying
these can help focus future data collection. We present gLOP, the global and
Local Penalty, a framework for capturing predictive heterogeneity and
identifying predictive outliers. gLOP is based on penalized regression for
multitask learning, which improves learning by leveraging training signal
information from related tasks. We give two optimization algorithms for gLOP,
one space-efficient, and another giving the full regularization path. We also
characterize uniqueness in terms of the data and tuning parameters, and present
empirical results on synthetic data and on two health research problems.


title: Obscured flat spectrum radio AGN as sources of high-energy neutrinos

abstract:
  Active Galactic Nuclei (AGN) are believed to be one of the main source
candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently
discovered by the IceCube neutrino observatory. Nevertheless, several
correlation studies between AGN and the cosmic neutrinos detected by IceCube
show no significance. Therefore, in this article we consider a specific
sub-class of AGN for which an increased neutrino production is expected. This
sub-class contains AGN for which their high-energy jet is pointing toward
Earth. Furthermore, we impose the condition that the jet is obscured by gas or
dust surrounding the AGN.
  A method is presented to determine the total column density of the obscuring
medium, which is probed by determining the relative X-ray attenuation with
respect to the radio flux as obtained from the AGN spectrum. The total column
density allows us to probe the interaction of the jet with the surrounding
matter which leads to additional neutrino production. Finally, starting from
two different source catalogs, this method is applied to specify a sample of
low redshift radio galaxies for which an increased neutrino production is
expected.


title:
Projected Hartree Fock Theory as a Polynomial Similarity Transformation
  Theory of Single Excitations

abstract:
  Spin-projected Hartree-Fock is introduced as a particle-hole excitation
ansatz over a symmetry-adapted reference determinant. Remarkably, this
expansion has an analytic expression that we were able to decipher. While the
form of the polynomial expansion is universal, the excitation amplitudes need
to be optimized. This is equivalent to the optimization of orbitals in the
conventional projected Hartree-Fock framework of non-orthogonal determinants.
Using the inverse of the particle-hole expansion, we similarity transform the
Hamiltonian in a coupled-cluster style theory. The left eigenvector of the
non-hermitian Hamiltonian is constructed in a similar particle-hole expansion
fashion, and we show that to numerically reproduce variational projected
Hartree-Fock results, one needs as many pair excitations in the bra as the
number of strongly correlated entangled pairs in the system. This
single-excitation polynomial similarity transformation theory is an alternative
to our recently presented double excitation theory, but supports projected
Hartree-Fock and coupled cluster simultaneously rather than interpolating
between them.


title:
Pulse and quench induced dynamical phase transition in a chiral
  multiferroic spin chain

abstract:
  Quantum dynamics of magnetic order in a chiral multiferroic chain is studied.
We consider two different scenarios: Ultrashort terahertz (THz) excitations or
a sudden electric field quench. Performing analytical and numerical exact
diagonalization calculations we trace the pulse induced spin dynamics and
extract quantities that are relevant to quantum information processing. In
particular, we analyze the dynamics of the system chirality, the von Neumann
entropy, the pairwise and the many body entanglement. If the characteristic
frequencies of the generated states are non-commensurate then a partial loss of
pair concurrence occurs. Increasing the system size this effect becomes even
more pronounced. Many particle entanglement and chirality are robust and
persist in the incommensurate phase. To analyze the dynamical quantum
transitions for the quenched and pulsed dynamics we combined the Weierstrass
factorization technique for entire functions and Lanczos exact diagonalization
method. For a small system we obtained analytical results including the rate
function of Loschmidt echo. Exact numerical calculations for a system up to 40
spins confirm phase transition. Quench- induced dynamical transitions have been
extensively studied recently. Here we show that related dynamical transitions
can be achieved and controlled by appropriate electric field pulses.


title: The geometry of real reducible polarizations in quantum mechanics

abstract:
  The formulation of Geometric Quantization contains several axioms and
assumptions. We show that for real polarizations we can generalize the standard
geometric quantization procedure by introducing an arbitrary connection on the
polarization bundle. The existence of reducible quantum structures leads to
considering the class of Liouville symplectic manifolds. Our main application
of this modified geometric quantization scheme is to Quantum Mechanics on
Riemannian manifolds. With this method we obtain an energy operator without the
scalar curvature term that appears in the standard formulation, thus agreeing
with the usual expression found in the Physics literature.


title: On the Power of Likelihood Ratio Tests in Dimension-Restricted Submodels

abstract:
  Likelihood ratio tests are widely used to test statistical hypotheses about
parametric families of probability distributions. If interest is restricted to
a subfamily of distributions, then it is natural to inquire if the restricted
LRT is superior to the unrestricted LRT. Marden's general LRT conjecture posits
that any restriction placed on the alternative hypothesis will increase power.
The only published counterexample to this conjecture is rather technical and
involves a restriction that maintains the dimension of the alternative. We
formulate the dimension-restricted LRT conjecture, which posits that any
restriction that replaces a parametric family with a subfamily of lower
dimension will increase power. Under standard regularity conditions, we then
demonstrate that the restricted LRT is asymptotically more powerful than the
unrestricted LRT for local alternatives. Remarkably, however, even the
dimension-restricted LRT conjecture fails in the case of finite samples. Our
counterexamples involve subfamilies of multinomial distributions. In
particular, our study of the Hardy-Weinberg subfamily of trinomial
distributions provides a simple and elegant demonstration that restrictions may
not increase power.


title: Locally Robust Semiparametric Estimation

abstract:
  Many economic and causal parameters depend on nonparametric or high
dimensional first steps. We give a general construction of locally
robust/orthogonal moment functions for GMM, where moment conditions have zero
derivative with respect to first steps. We show that orthogonal moment
functions can be constructed by adding to identifying moments the nonparametric
influence function for the effect of the first step on identifying moments.
Orthogonal moments reduce model selection and regularization bias, as is very
important in many applications, especially for machine learning first steps.
  We give debiased machine learning estimators of functionals of high
dimensional conditional quantiles and of dynamic discrete choice parameters
with high dimensional state variables. We show that adding to identifying
moments the nonparametric influence function provides a general construction of
orthogonal moments, including regularity conditions, and show that the
nonparametric influence function is robust to additional unknown functions on
which it depends. We give a general approach to estimating the unknown
functions in the nonparametric influence function and use it to automatically
debias estimators of functionals of high dimensional conditional location
learners. We give a variety of new doubly robust moment equations and
characterize double robustness. We give general and simple regularity
conditions and apply these for asymptotic inference on functionals of high
dimensional regression quantiles and dynamic discrete choice parameters with
high dimensional state variables.


title:
Schur complement Domain Decomposition Methods for the solution of
  multiple scattering problems

abstract:
  We present a Schur complement Domain Decomposition (DD) algorithm for the
solution of frequency domain multiple scattering problems. Just as in the
classical DD methods we (1) enclose the ensemble of scatterers in a domain
bounded by an artificial boundary, (2) we subdivide this domain into a
collection of nonoverlapping subdomains so that the boundaries of the
subdomains do not intersect any of the scatterers, and (3) we connect the
solutions of the subproblems via Robin boundary conditions matching on the
common interfaces between subdomains. We use subdomain Robin-to-Robin maps to
recast the DD problem as a sparse linear system whose unknown consists of Robin
data on the interfaces between subdomains---two unknowns per interface. The
Robin-to-Robin maps are computed in terms of well-conditioned boundary integral
operators. Unlike classical DD, we do not reformulate the Domain Decomposition
problem in the form a fixed point iteration, but rather we solve the ensuing
linear system by Gaussian elimination of the unknowns corresponding to inner
interfaces between subdomains via Schur complements. Once all the unknowns
corresponding to inner subdomains interfaces have been eliminated, we solve a
much smaller linear system involving unknowns on the inner and outer artificial
boundary. We present numerical evidence that our Schur complement DD algorithm
can produce accurate solutions of very large multiple scattering problems that
are out of reach for other existing approaches.


title:
Employing Range Separation on the meta-GGA Rung: New Functional Suitable
  for Both Covalent and Noncovalent Interactions

abstract:
  We devise a scheme for converting an existing exchange functional into its
range-separated hybrid variant. The underlying exchange hole of the
Becke-Roussel type has the exact second-order expansion in the interelectron
distance. The short-range part of the resulting range-separated exchange energy
depends on the kinetic energy density and the Laplacian even if the base
functional lacks the dependence on these variables. The most successful
practical realization of the scheme, named LC-PBETPSS, combines the
range-separated PBE exchange lifted to the hybrid meta-GGA rung and the TPSS
correlation. The value of the range-separation parameter is estimated
theoretically and confirmed by empirical optimization. The D3 dispersion
correction is recommended for all energy computations employing the presented
functional. Numerical tests show remarkably robust performance of the method
for noncovalent interaction energies, barrier heights, main-group
thermochemistry, and excitation energies.


title: The PADME experiment at Laboratori Nazionali di Frascati

abstract:
  The PADME experiment will search for the invisible decay of Dark Photons
produced in interactions of positron from the DA$\Phi$NE Linac on a target. The
collaboration aims at reaching a sensitivity of $\sim10^{-3}$ on the coupling
constant for values of Dark Photon masses up to $23.7\,\mbox{MeV}$.


title:
Current Status of the Facility Instrumentation Suite at The Large
  Binocular Telescope Observatory

abstract:
  We review the current status of the facility instrumentation for the Large
Binocular Telescope (LBT). The LBT has 2x 8.4m primary mirrors on a single
mount with an effective collecting area of 11.8m or 23m when
interferometrically combined. The facility instruments are: 1) the Large
Binocular Cameras (LBCs), each with a 23'x25' field of view (FOV). The blue and
red optimized optical LBCs are mounted at the prime focus of the left and right
primary mirrors, respectively. The filter suite of the two LBCs covers
0.3-1.1{\mu}m, including the new TiO (0.78{\mu}m) and CN (0.82{\mu}m) filters;
2) the Multi-Object Double Spectrograph (MODS), two identical optical
spectrographs each mounted at a straight through f/15 Gregorian mount. MODS-1 &
-2 can do imaging with Sloan filters and medium resolution (R~2000)
spectroscopy, each with 24 interchangeable masks (multi-object or longslit)
over a 6'x6' FOV. Each MODS is capable of blue (0.32-0.6{\mu}m) and red
(0.5-1.05{\mu}m) wavelength only coverage or, using a dichroic, 0.32-1.05{\mu}m
coverage; and 3) the two LBT Utility Camera in the Infrared instruments
(LUCIs), each mounted at a bent-front Gregorian f/15 port. LUCI-1 & 2 are
designed for seeing-limited (4'x4'FOV) and AO (0.5'x0.5' FOV) imaging &
spectroscopy over 0.95-2.5{\mu}m with spectroscopic resolutions of R~400-11000,
including 32 interchangeable cryogenically cooled masks. All facility
instruments are on the LBT and, for the first time, have been on-sky for
science. We also report on the first science use of "mixed-mode" (differently
paired instruments). While both primary mirrors reside on a single fixed mount,
they are capable of operating independently within a defined "co-pointing"
limit. This provides users with the additional capability to independently
dither each mirror or center observations on two different sets of spatial
coordinates within this limit. (ABRIDGED)


title: Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2

abstract:
  We investigate valley dynamics associated with trions in monolayer tungsten
diselenide (WSe2) using polarization resolved two-color pump-probe
spectroscopy. When tuning the pump and probe energy across the trion resonance,
distinct trion valley polarization dynamics are observed as a function of
energy and attributed to the intra-valley and inter-valley trions in monolayer
WSe2. We observe no decay of a near-unity valley polarization associated with
the intra-valley trions during ~ 25 ps, while the valley polarization of the
inter-valley trions exhibits a fast decay of ~ 4 ps. Furthermore, we show that
resonant excitation is a prerequisite for observing the long-lived valley
polarization associated with the intra-valley trion. The exceptionally robust
valley polarization associated with resonantly created intra-valley trions
discovered here may be explored for future valleytronic applications such as
valley Hall effects.


title:
Distributed Learning for Stochastic Generalized Nash Equilibrium
  Problems

abstract:
  This work examines a stochastic formulation of the generalized Nash
equilibrium problem (GNEP) where agents are subject to randomness in the
environment of unknown statistical distribution. We focus on fully-distributed
online learning by agents and employ penalized individual cost functions to
deal with coupled constraints. Three stochastic gradient strategies are
developed with constant step-sizes. We allow the agents to use heterogeneous
step-sizes and show that the penalty solution is able to approach the Nash
equilibrium in a stable manner within $O(\mu_\text{max})$, for small step-size
value $\mu_\text{max}$ and sufficiently large penalty parameters. The operation
of the algorithm is illustrated by considering the network Cournot competition
problem.


title: Soft QGP probes with ALICE

abstract:
  In heavy-ion collisions at the LHC a hot and dense medium of deconfided
partons, the Quark-Gluon Plasma (QGP), is created. Its global properties can be
characterized by the measurements of particles in the low transverse momentum
(or "soft") regime, which represent the majority of created particles. In this
report we outline a selection of measurements of the soft probes by the ALICE
experiment in pp, p--Pb, and Pb--Pb collisions. The paper focuses on recent
flow measurements via angular correlations and femtoscopic studies. The first
ever preliminary analysis of $\mathrm{K}^0_{\rm S}\mathrm{K}^{\pm}$ femtoscopy
is also presented.


title: Inflation on a Slippery Slope

abstract:
  We study inflation in a random multifield potential, using techniques
developed by Marsh et al. The potential is a function of a large number of
fields, and we choose parameters so that inflation only occurs in regions where
the potential is accidentally flat. Using an improved estimate for the dynamics
of eigenvalue repulsion, we are able to describe the steepening of the
potential as inflation progresses. We provide suggestive arguments, but not a
proof, that the resulting scalar power spectrum generically disagrees with
observations. We also point out two problematic aspects of the model: there is
no well-defined probability distribution for the gradient of the potential, and
the evolution of the potential over small distances in field space is
unphysical.


title:
Polynomial Time Algorithms and Extended Formulations for Unit Commitment
  Problems

abstract:
  Recently increasing penetration of renewable energy generation brings
challenges for power system operators to perform efficient power generation
daily scheduling, due to the intermittent nature of the renewable generation
and discrete decisions of each generation unit. Among all aspects to be
considered, a unit commitment polytope is fundamental and embedded in the
models at different stages of power system planning and operations. In this
paper, we focus on deriving polynomial time algorithms for the unit commitment
problems with general convex cost function and piecewise linear cost function
respectively. We refine an $\mathcal{O}(T^3)$ time, where $ T $ represents the
number of time periods, algorithm for the deterministic single-generator unit
commitment problem with general convex cost function and accordingly develop an
extended formulation in a higher dimensional space that can provide an integral
solution, in which the physical meanings of the decision variables are
described. It means the original problem can be solved as a convex program
instead of a mixed-integer convex program. Furthermore, for the case in which
the cost function is piecewise linear, by exploring the optimality conditions,
we derive more efficient algorithms for both deterministic (i.e.,
$\mathcal{O}(T)$ time) and stochastic (i.e., $\mathcal{O}(N)$ time, where $N$
represents the number of nodes in the stochastic scenario tree)
\rred{single-generator} unit commitment problems. We also develop the
corresponding extended formulations for both deterministic and stochastic
single-generator unit commitment problems that solve the original mixed-integer
linear programs as linear programs. Similarly, physical meanings of the
decision variables are explored to show the insights of the new modeling
approach.


title:
Onset of oligarchic growth and implication for accretion histories of
  dwarf planets

abstract:
  We investigate planetary accretion that starts from equal-mass planetesimals
using an analytic theory and numerical simulations. We particularly focus on
how the planetary mass $M_{\rm oli}$ at the onset of oligarchic growth depends
on the initial mass $m_0$ of a planetesimal. Oligarchic growth commences when
the velocity dispersion relative to the Hill velocity of the protoplanet takes
its minimum. We find that if $m_0$ is small enough, this normalized velocity
dispersion becomes as low as unity during the intermediate stage between the
runaway and oligarchic growth stages. In this case, $M_{\rm oli}$ is
independent of $m_0$. If $m_0$ is large, on the other hand, oligarchic growth
commences directly after runaway growth, and $M_{\rm oli} \propto m_0^{3/7}$.
The planetary mass $M_{\rm oli}$ for the solid surface density of the Minimum
Mass Solar Nebula is close to the masses of the dwarf planets in a reasonable
range of $m_0$. This indicates that they are likely to be the largest remnant
planetesimals that failed to become planets. The power-law exponent $q$ of the
differential mass distribution of remnant planetesimals is typically $-2.0$ and
$-2.7$ to $-2.5$ for small and large $m_0$. The slope, $q \simeq -2.7$, and the
bump at $10^{21}$ g (or 50 km in radius) for the mass distribution of hot
Kuiper belt objects are reproduced if $m_0$ is the bump mass. On the other
hand, small initial planetesimals with $m_0 \sim 10^{13}$ g or less are favored
to explain the slope of large asteroids, $q \simeq -2.0$, while the bump at
$10^{21}$ g can be reproduced by introducing a small number of asteroid seeds
each with mass of $10^{19} $ g.


title: An Asynchronous Task-based Fan-Both Sparse Cholesky Solver

abstract:
  Systems of linear equations arise at the heart of many scientific and
engineering applications. Many of these linear systems are sparse; i.e., most
of the elements in the coefficient matrix are zero. Direct methods based on
matrix factorizations are sometimes needed to ensure accurate solutions. For
example, accurate solution of sparse linear systems is needed in shift-invert
Lanczos to compute interior eigenvalues. The performance and resource usage of
sparse matrix factorizations are critical to time-to-solution and maximum
problem size solvable on a given platform. In many applications, the
coefficient matrices are symmetric, and exploiting symmetry will reduce both
the amount of work and storage cost required for factorization. When the
factorization is performed on large-scale distributed memory platforms,
communication cost is critical to the performance of the algorithm. At the same
time, network topologies have become increasingly complex, so that modern
platforms exhibit a high level of performance variability. This makes
scheduling of computations an intricate and performance-critical task. In this
paper, we investigate the use of an asynchronous task paradigm, one-sided
communication and dynamic scheduling in implementing sparse Cholesky
factorization (symPACK) on large-scale distributed memory platforms. Our solver
symPACK relies on efficient and flexible communication primitives provided by
the UPC++ library. Performance evaluation shows good scalability and that
symPACK outperforms state-of-the-art parallel distributed memory factorization
packages, validating our approach on practical cases.


title: Gaia: focus, straylight and basic angle

abstract:
  The Gaia all-sky astrometric survey is challenged by several issues affecting
the spacecraft stability. Amongst them, we find the focus evolution, straylight
and basic angle variations
  Contrary to pre-launch expectations, the image quality is continuously
evolving, during commissioning and the nominal mission. Payload
decontaminations and wavefront sensor assisted refocuses have been carried out
to recover optimum performance. Straylight and basic angle variations several
orders of magnitude greater than foreseen were found and studied during
commissioning by the Gaia scientists (payload experts). Building on their
investigations, an ESA-Airbus DS working group was established during the early
nominal mission and worked on a detailed root cause analysis. In parallel, Gaia
scientists have also continued analysing the data, most notably comparing the
BAM signal to global astrometric solutions, with remarkable agreement.
  In this contribution, a status review of these issues will be provided, with
emphasis on the mitigation schemes and the lessons learned for future space
missions where extreme stability is a key requirement.


title: An Ax-Kochen-Ershov Theorem for Monotone Differential-Henselian Fields

abstract:
  Scanlon [5] proves Ax-Kochen-Ershov type results for differential-henselian
monotone valued differential fields with many constants. We show how to get rid
of the condition "with many constants".


title: Definitive Test of the R_h=ct Universe Using Redshift Drift

abstract:
  The redshift drift of objects moving in the Hubble flow has been proposed as
a powerful model-independent probe of the underlying cosmology. A measurement
of the first and second order redshift derivatives appears to be well within
the reach of upcoming surveys using ELT-HIRES and the SKA Phase 2 array. Here
we show that an unambiguous prediction of the R_h=ct cosmology is zero drift at
all redshifts, contrasting sharply with all other models in which the expansion
rate is variable. For example, multi-year monitoring of sources at redshift z=5
with the ELT-HIRES is expected to show a velocity shift Delta v = -15 cm/s/yr
due to the redshift drift in Planck LCDM, while Delta v=0 cm/s/yr in R_h=ct.
With an anticipated ELT-HIRES measurement error of +/-5 cm/s/yr after 5 years,
these upcoming redshift drift measurements might therefore be able to
differentiate between R_h=ct and Planck LCDM at ~3 sigma, assuming that any
possible source evolution is well understood. Such a result would provide the
strongest evidence yet in favour of the R_h=ct cosmology. With a 20-year
baseline, these observations could favor one of these models over the other at
better than 5 sigma.


title:
Phosphorus-bearing molecules in solar-type star forming regions: First
  PO detection

abstract:
  As part of the Large Program ASAI (Astrochemical Surveys At IRAM), we have
used the IRAM 30m telescope to lead a systematic search for the emission of
rotational transitions of P-bearing species between 80 and 350 GHz towards
L1157-B1, a shock position in the solar-type star forming region L1157. We
report the detection of several transitions of PN and, for the first time, of
prebiotic molecule PO. None of these species are detected towards the driving
protostar of the outflow L1157-mm. Analysis of the line profiles shows that PN
arises from the outflow cavity, where SiO, a strong shock tracer, is produced.
Radiative transfer analysis yields an abundance of 2.5e-9 and 0.9e-9 for PO and
PN, respectively. These results imply a strong depletion (approx 100) of
Phosphorus in the quiescent cloud gas. Shock modelling shows that atomic N
plays a major role in the chemistry of PO and PN. The relative abundance of PO
and PN brings constraints both on the duration of the pre-shock phase, which
has to be about 1 Myr, and on the shock parameters. The maximum temperature in
the shock has to be larger than 4000K, which implies a shock velocity of 40
km/s.


abstract:
  We have conducted the Meterwavelength Single-pulse Polarimetric Emission
Survey to study the radio emission properties of normal pulsars. A total of 123
pulsars with periods between 0.1 seconds and 8.5 seconds were observed in the
survey at two different frequencies, 105 profiles at 333 MHz, 118 profiles at
618 MHz and 100 pulsars at both. In this work we concentrate primarily on the
time-averaged properties of the pulsar emission. The measured widths of the
pulsar profiles in our sample usually exhibit the radius to frequency mapping.
We validate the existence of lower bounds for the distribution of profile
widths with pulsar period ($P$), which is seen for multiple definitions of the
width, viz. a lower boundary line (LBL) at $2.7^{\circ} P^{-0.5}$ with width
measured at 50% level of profile peak, a LBL at $5.7^{\circ} P^{-0.5}$ for 10%
level of peak and LBL at $6.3^{\circ} P^{-0.5}$ for width defined as 5$\sigma$
above the baseline level. In addition we have measured the degree of linear
polarization in the average profile of pulsars and confirmed their dependence
on pulsar spindown energy loss ($\dot{E}$). The single pulse polarization data
show interesting trends with the polarization position angle (PPA) distribution
exhibiting the simple rotating vector model for high $\dot{E}$ pulsars while
the PPA becomes more complex for medium and low $\dot{E}$ pulsars. The single
pulse total intensity data is useful for studying a number of emission
properties from pulsars like subpulse drifting, nulling and mode changing which
is being explored in separate works.


title:
Meterwavelength Single-pulse Polarimetric Emission Survey II: The
  phenomenon of Drifting Subpulses

abstract:
  A large sample of pulsars was observed as part of the Meterwavelength
Single-pulse Polarimetric Emission Survey. We carried out a detailed
fluctuation spectral analysis which revealed periodic features in 46% pulsars
including 22 pulsars where drifting characteristics were reported for the first
time. The pulsar population can be categorized into three distinct groups,
pulsars which show systematic drift motion within the pulse window, the pulsars
showing no systematic drift but periodic amplitude fluctuation and pulsars with
no periodic variations. We discovered the dependence of the drifting phenomenon
on the spin down energy loss ($\dot{E}$), with the three categories occupying
distinctly different regions along the $\dot{E}$ axis. The estimation of the
drift periodicity ($P_3$) from the peak frequency in the fluctuation spectra is
ambiguous due to the aliasing effect. However, using basic physical arguments
we were able to determine $P_3$ in pulsars showing systematic drift motion. The
estimated $P_3$ values in these pulsars were anti-correlated with $\dot{E}$
which favoured the Partially Screened Gap model of Inner Acceleration Region in
pulsars.