title: Gravitational waveforms in scalar-tensor gravity at 2PN relative order

abstract:
  We compute the gravitational waveform from a binary system in scalar-tensor
gravity at 2PN relative order. We restrict our calculation to non-spinning
binary systems on quasi-circular orbits and compute the spin-weighted spherical
modes of the radiation. The evolution of the phase of the waveform is computed
in the time and frequency domains. The emission of dipolar radiation is the
lowest-order dissipative process in scalar-tensor gravity. However, stringent
constraints set by current astrophysical observations indicate that this effect
is subdominant to quadrupolar radiation for most prospective gravitational-wave
sources. We compute the waveform for systems whose inspiral is driven by: (a)
dipolar radiation (e.g., binary pulsars or spontaneously scalarized systems)
and (b) quadrupolar radiation (e.g., typical sources for space-based and
ground-based detectors).


title:
Adaptive Pseudo-Transient-Continuation-Galerkin Methods for Semilinear
  Elliptic Partial Differential Equations

abstract:
  In this paper we investigate the application of pseudo-transient-continuation
(PTC) schemes for the numerical solution of semilinear elliptic partial
differential equations, with possible singular perturbations. We will outline a
residual reduction analysis within the framework of general Hilbert spaces,
and, subsequently, employ the PTC-methodology in the context of finite element
discretizations of semilinear boundary value problems. Our approach combines
both a prediction-type PTC-method (for infinite dimensional problems) and an
adaptive finite element discretization (based on a robust a posteriori residual
analysis), thereby leading to a fully adaptive PTC-Galerkin scheme. Numerical
experiments underline the robustness and reliability of the proposed approach
for different examples.


title:
Examining and contrasting the cognitive activities engaged in
  undergraduate research experiences and lab courses

abstract:
  While the positive outcomes of undergraduate research experiences (UREs) have
been extensively categorized, the mechanisms for those outcomes are less
understood. Through lightly structured focus group interviews, we have
extracted the cognitive tasks that students identify as engaging in during
their UREs. We also use their many comparative statements about their
coursework, especially lab courses, to evaluate their experimental
physics-related cognitive tasks in those environments. We find there are a
number of cognitive tasks consistently encountered in physics UREs that are
present in most experimental research. These are seldom encountered in lab or
lecture courses, with some notable exceptions. Having time to reflect and fix
or revise, and having a sense of autonomy, were both repeatedly cited as key
enablers of the benefits of UREs. We also identify tasks encountered in actual
experimental research that are not encountered in UREs. We use these findings
to identify opportunities for better integration of the cognitive tasks in UREs
and lab courses, as well as discussing the barriers that exist. This work
responds to extensive calls for science education to better develop students'
scientific skills and practices, as well as calls to expose more students to
scientific research.


title: Unbounded Disjointness Preserving Linear Functionals and Operators

abstract:
  Let $E$ and $F$ be Banach lattices. We show first that the disjointness
preserving linear functionals separate the points of any infinite dimensional
Banach lattice $E$, which shows that in this case the unbounded disjointness
operators from $E\to F$ separate the points of $E$. Then we show that every
disjointness preserving operator $T:E\to F$ is norm bounded on an order dense
ideal. In case $E$ has order continuous norm, this implies that that every
unbounded disjointness preserving map $T:E\to F$ has a unique decomposition
$T=R+S$, where $R$ is a bounded disjointness preserving operator and $S$ is an
unbounded disjointness preserving operator, which is zero on a norm dense
ideal. For the case that $E=C(X)$, with $X$ a compact Hausdorff space, we show
that every disjointness preserving operator $T:C(X)\to F$ is norm bounded on an
norm dense sublattice algebra of $C(X)$, which leads then to a decomposition of
$T$ into a bounded disjointness operator and a finite sum of unbounded
disjointness preserving operators, which are zero on order dense ideals.


title: Special classes of $q$-bracket operators

abstract:
  We study the $q$-bracket operator of Bloch and Okounkov when applied to
$f(\lambda)=\sum_{\lambda_i \in \lambda}g(\lambda_i)$ and
$f(\lambda)=\sum_{\substack{\lambda_i \in \lambda \lambda_i \text{distinct}
}}g(\lambda_i)$. We use these expansions to derive convolution identities for
the functions $f$ and link both classes of $q$-brackets through divisor sums.
As a result, we generalize Euler's classic convolution identity for the
partition function and obtain an analogous identity for the totient function.
As corollaries, we generalize Stanley's theorem as well as provide several new
combinatorial results.


title:
Revolutionizing our View of Protostellar Multiplicity and Disks: The VLA
  Nascent Disk and Multiplicity (VANDAM) Survey of the Perseus Molecular Cloud

abstract:
  There is substantial evidence for disk formation taking place during the
early stages of star formation and for most stars being born in multiple
systems; however, protostellar multiplicity and disk searches have been
hampered by low resolution, sample bias, and variable sensitivity. We have
conducted an unbiased, high-sensitivity Karl G. Jansky Very Large Array (VLA)
survey toward all known protostars (n = 94) in the Perseus molecular cloud
(d~230 pc), with a resolution of ~15 AU (0.06") at 8 mm. We have detected
candidate protostellar disks toward 17 sources (with 12 of those in the Class 0
stage) and we have found substructure on < 50AU scales for three Class 0 disk
candidates, possibly evidence for disk fragmentation. We have discovered 16 new
multiple systems (or new components) in this survey; the new systems have
separations < 500 AU and 3 by < 30 AU. We also found a bi-modal distribution of
separations, with peaks at ~75 AU and ~3000 AU, suggestive of formation through
two distinct mechanisms: disk and turbulent fragmentation. The results from
this survey demonstrate the necessity and utility of uniform, unbiased surveys
of protostellar systems at millimeter and centimeter wavelengths.


title:
Chains of Reasoning over Entities, Relations, and Text using Recurrent
  Neural Networks

abstract:
  Our goal is to combine the rich multistep inference of symbolic logical
reasoning with the generalization capabilities of neural networks. We are
particularly interested in complex reasoning about entities and relations in
text and large-scale knowledge bases (KBs). Neelakantan et al. (2015) use RNNs
to compose the distributed semantics of multi-hop paths in KBs; however for
multiple reasons, the approach lacks accuracy and practicality. This paper
proposes three significant modeling advances: (1) we learn to jointly reason
about relations, entities, and entity-types; (2) we use neural attention
modeling to incorporate multiple paths; (3) we learn to share strength in a
single RNN that represents logical composition across all relations. On a
largescale Freebase+ClueWeb prediction task, we achieve 25% error reduction,
and a 53% error reduction on sparse relations due to shared strength. On chains
of reasoning in WordNet we reduce error in mean quantile by 84% versus previous
state-of-the-art. The code and data are available at
https://rajarshd.github.io/ChainsofReasoning


title: Admissible Banach function spaces and nonuniform stabilities

abstract:
  For nonuniform exponentially bounded evolution families defined on Banach
spaces, we introduce a class of Banach function spaces, whose norms are
completely determined by the nonuniform behaviour of the corresponding
evolution family. We generalize a classical theorem of Datko on these spaces.
In addition, we obtain new criteria for the existence of nonuniform stability.


title: An Infinitesimal $p$-adic Multiplicative Manin-Mumford Conjecture

abstract:
  Our results concern analytic functions on the open unit $p$-adic poly-disc in
$\mathbb{C}^n_p$ centered at the multiplicative unit and we prove that such
functions only vanish at finitely many $n$-tuples of roots of unity
$(\zeta_1-1,\ldots,\zeta_n-1)$ unless they vanish along a translate of the
formal multiplicative group. For polynomial functions, this follows from the
multiplicative Manin-Mumford conjecture. However we allow for a much wider
class of analytic functions; in particular we establish a rigidity result for
formal tori. Moreover, our methods apply to Lubin-Tate formal groups beyond
just the formal multiplicative group and we extend the results to this setting.


title:
Enabling accurate first-principle calculations of electronic properties
  with a corrected k.p scheme

abstract:
  A computationally inexpensive k.p-based interpolation scheme is developed
that can extend the eigenvalues and momentum matrix elements of a sparsely
sampled k-point grid into a densely sampled one. Dense sampling, often required
to accurately describe transport and optical properties of bulk materials, can
be demanding to compute, for instance, in combination with hybrid functionals
in density functional theory (DFT) or with perturbative expansions beyond DFT
such as the $GW$ method. The scheme is based on solving the k.p method and
extrapolating from multiple reference k-points. It includes a correction term
that reduces the number of empty bands needed and ameliorates band
discontinuities. We show how the scheme can be used to generate accurate band
structures, density of states, and dielectric functions. Several examples are
given, using traditional and hybrid functionals, with Si, TiNiSn, and Cu as
model materials. We illustrate that d-electron and semi-core states, which are
particular challenging for the k.p method, can be handled with the correction
scheme if the sparse grid is not too sparse.

categories: cond-mat.mtrl-sci cond-mat.mes-hall physics.chem-ph physics.comp-ph


title: Uniform tail approximation of homogenous functionals of Gaussian fields

abstract:
  Let $X(t),t\in R^d$ be a centered Gaussian random field with continuous
trajectories and set $\xi_u(t)= X(f(u)t),t\in R^d$ with $f$ some positive
function. Classical results establish the tail asymptotics of $P\{
\Gamma(\xi_u) > u\}$ as $u\to \infty$ with $\Gamma(\xi_u)= \sup_{t \in [0,T
]^d} \xi_u(t),T>0$ by requiring that $f(u) \to 0$ with speed controlled by the
local behaviour of the correlation function of $X$. Recent research shows that
for applications more general continuous functionals than supremum should be
considered and the Gaussian field can depend also on some additional parameter
$\tau_u \in K$, say $\xi_{u,\tau_u}(t),t\in R^d$. In this contribution we
derive uniform approximations of $P\{ \Gamma(\xi_{u,\tau_u})> u\}$ with respect
to $\tau_u$ in some index set $K_u$, as $u\to\infty$. Our main result have
important theoretical implications; two applications are already included in
[10,11]. In this paper we present three additional ones, namely i) we derive
uniform upper bounds for the probability of double-maxima, ii) we extend
Piterbarg-Prisyazhnyuk theorem to some large classes of homogeneous functionals
of centered Gaussian fields $\xi_{u}$, and iii) we show the finiteness of
generalized Piterbarg constants.


title:
An alternative method to characterize first- and second-order phase
  transitions in surface reaction models

abstract:
  In this work, we revisited the Ziff-Gulari-Barshad (ZGB) model to study its
phase transitions and critical exponents through time-dependent Monte Carlo
simulations. We used a method proposed recently to locate the non-equilibrium
second-order phase transitions and that has been successfully used in systems
with defined Hamiltonians and with absorbing states. This method, which is
based on optimization of the coefficient of determination of the order
parameter, was able to characterize the second-order phase transition of the
model, as well as its upper spinodal point, a pseudo-critical point located
near the first-order transition. The static critical exponents $\beta $,
$\nu_{\parallel }$, and $\nu_{\perp }$, as well as the dynamic critical
exponents $\theta $ and $z$ for the second-order point were also estimated and
are in excellent agreement with results found in literature.


title: Global Neural CCG Parsing with Optimality Guarantees

abstract:
  We introduce the first global recursive neural parsing model with optimality
guarantees during decoding. To support global features, we give up dynamic
programs and instead search directly in the space of all possible subtrees.
Although this space is exponentially large in the sentence length, we show it
is possible to learn an efficient A* parser. We augment existing parsing
models, which have informative bounds on the outside score, with a global model
that has loose bounds but only needs to model non-local phenomena. The global
model is trained with a new objective that encourages the parser to explore a
tiny fraction of the search space. The approach is applied to CCG parsing,
improving state-of-the-art accuracy by 0.4 F1. The parser finds the optimal
parse for 99.9% of held-out sentences, exploring on average only 190 subtrees.


title:
Pencil-Beam Single-point-fed Dirac Leaky-Wave Antenna on a
  Transmission-Line Grid

abstract:
  Leaky-wave antennas (LWAs) are widely used as single-point-fed linear antenna
arrays. The extension of LWAs to 2D implies that they can be used as
single-point-fed 2D antenna arrays without requiring a complex feeding network.
However, generating a pencil beam from 2D LWAs is not straightforward and due
care has to be taken for the design of the LWA. On the other hand,
transmission-line (TL) grids have demonstrated interesting behaviors, such as
an effective negative refractive index and growing of evanescent waves. In this
paper, a singlepoint-fed TL-grid 2D Dirac leaky-wave antenna (DLWA) design is
proposed that generates a pencil beam at both broadside and slightly tilted
angles. The TL-grid unit cell is analytically treated in light of its
scattering and impedance matrices. The optimized TL-grid unit cell is shown to
exhibit a closed bandgap in the dispersion relation which is also linearly
varying with frequency (hence it is a DLWA). The proposed 2D DLWA design is
fabricated and the experimental results are presented.


title:
Risk Bounds for High-dimensional Ridge Function Combinations Including
  Neural Networks

abstract:
  Let $ f^{\star} $ be a function on $ \mathbb{R}^d $ with an assumption of a
spectral norm $ v_{f^{\star}} $. For various noise settings, we show that $
\mathbb{E}\|\hat{f} - f^{\star} \|^2 \leq \left(v^4_{f^{\star}}\frac{\log
d}{n}\right)^{1/3} $, where $ n $ is the sample size and $ \hat{f} $ is either
a penalized least squares estimator or a greedily obtained version of such
using linear combinations of sinusoidal, sigmoidal, ramp, ramp-squared or other
smooth ridge functions. The candidate fits may be chosen from a continuum of
functions, thus avoiding the rigidity of discretizations of the parameter
space. On the other hand, if the candidate fits are chosen from a
discretization, we show that $ \mathbb{E}\|\hat{f} - f^{\star} \|^2 \leq
\left(v^3_{f^{\star}}\frac{\log d}{n}\right)^{2/5} $. This work bridges
non-linear and non-parametric function estimation and includes single-hidden
layer nets. Unlike past theory for such settings, our bound shows that the risk
is small even when the input dimension $ d $ of an infinite-dimensional
parameterized dictionary is much larger than the available sample size. When
the dimension is larger than the cube root of the sample size, this quantity is
seen to improve the more familiar risk bound of $
v_{f^{\star}}\left(\frac{d\log (n/d)}{n}\right)^{1/2} $, also investigated
here.


title: Scaling Laws in Spatial Network Formation

abstract:
  Geometric constraints impact the formation of a broad range of spatial
networks, from amino acid chains folding to proteins structures to rearranging
particle aggregates. How the network of interactions dynamically self-organizes
in such systems is far from fully understood. Here, we analyze a class of
spatial network formation processes by introducing a mapping from geometric to
graph-theoretic constraints. Combining stochastic and mean field analyses
yields an algebraic scaling law for the extent (graph diameter) of the
resulting networks with system size, in contrast to logarithmic scaling known
for networks without constraints. Intriguingly, the exponent falls between that
of self-avoiding random walks and that of space filling arrangements,
consistent with experimentally observed scaling (of the spatial radius of
gyration) for protein tertiary structures.


title:
A Generalized Framework on Beamformer Design and CSI Acquisition for
  Single-Carrier Massive MIMO Systems in Millimeter Wave Channels

abstract:
  In this paper, we establish a general framework on the reduced dimensional
channel state information (CSI) estimation and pre-beamformer design for
frequency-selective massive multiple-input multiple-output MIMO systems
employing single-carrier (SC) modulation in time division duplex (TDD) mode by
exploiting the joint angle-delay domain channel sparsity in millimeter (mm)
wave frequencies. First, based on a generic subspace projection taking the
joint angle-delay power profile and user-grouping into account, the reduced
rank minimum mean square error (RR-MMSE) instantaneous CSI estimator is derived
for spatially correlated wideband MIMO channels. Second, the statistical
pre-beamformer design is considered for frequency-selective SC massive MIMO
channels. We examine the dimension reduction problem and subspace (beamspace)
construction on which the RR-MMSE estimation can be realized as accurately as
possible. Finally, a spatio-temporal domain correlator type reduced rank
channel estimator, as an approximation of the RR-MMSE estimate, is obtained by
carrying out least square (LS) estimation in a proper reduced dimensional
beamspace. It is observed that the proposed techniques show remarkable
robustness to the pilot interference (or contamination) with a significant
reduction in pilot overhead.


title: Attribute Recognition from Adaptive Parts

abstract:
  Previous part-based attribute recognition approaches perform part detection
and attribute recognition in separate steps. The parts are not optimized for
attribute recognition and therefore could be sub-optimal. We present an
end-to-end deep learning approach to overcome the limitation. It generates
object parts from key points and perform attribute recognition accordingly,
allowing adaptive spatial transform of the parts. Both key point estimation and
attribute recognition are learnt jointly in a multi-task setting. Extensive
experiments on two datasets verify the efficacy of proposed end-to-end
approach.


title:
On the Computational Complexities of Three Privacy Measures for Large
  Networks Under Active Attack

abstract:
  With the arrival of modern internet era, large public networks of various
types have come to existence to benefit the society as a whole and several
research areas such as sociology, economics and geography in particular.
However, the societal and research benefits of these networks have also given
rise to potentially significant privacy issues in the sense that malicious
entities may violate the privacy of the users of such a network by analyzing
the network and deliberately using such privacy violations for deleterious
purposes. Such considerations have given rise to a new active research area
that deals with the quantification of privacy of users in large networks and
the corresponding investigation of computational complexity issues of computing
such quantified privacy measures. In this paper, we formalize three such
privacy measures for large networks and provide non-trivial theoretical
computational complexity results for computing these measures. Our results show
the first two measures can be computed efficiently, whereas the third measure
is provably hard to compute within a logarithmic approximation factor.
Furthermore, we also provide computational complexity results for the case when
the privacy requirement of the network is severely restricted, including an
efficient logarithmic approximation.


title:
Modeling and Analysis of a Two-Phase Thin Film Model with Insoluble
  Surfactant

abstract:
  In this paper we consider a two-phase thin film consisting of two immiscible
viscous fluids endowed with a layer of insoluble surfactant on the surface of
the upper fluid. The governing equations for the two film heights and the
surfactant concentration are derived using a lubrication approximation. Taking
gravitational forces into account but neglecting capillary effects, the
resulting system of evolution equations is parabolic, strongly coupled, of
second order and degenerated in the equations for the two film heights.
Incorporating on the contrary capillary forces and neglecting the effects of
gravitation, the system of evolution equations is parabolic, degenerated and of
fourth order for the film heights, strongly coupled to a second order transport
equation for the surfactant concentration. Local well-posedness and asymptotic
stability are shown for both systems.


title: Testing a dynamical origin of Standard Model fermion masses

abstract:
  We discuss a test of the Standard Model fermion mass origin in models of
dynamical electroweak symmetry breaking. The couplings of composite
pseudoscalar resonances to top quarks allow to distinguish high-scale
Extended-Technicolor-type fermion mass generation from fermion partial
compositeness and low-scale mass generation via an induced vacuum expectation
value of a doublet coupled to the composite sector. These different possible
origins of fermion masses are thus accessible via weak-scale physics searched
for at the LHC.


title: Network Simplification in Half-Duplex: Building on Submodularity

abstract:
  This paper explores the {\it network simplification} problem in the context
of Gaussian Half-Duplex (HD) diamond networks. Specifically, given an $N$-relay
diamond network, this problem seeks to derive fundamental guarantees on the
capacity of the best $k$-relay subnetwork, as a function of the full network
capacity. The main focus of this work is on the case when $k=N-1$ relays are
selected out of the $N$ possible ones. First, a simple algorithm, which removes
the relay with the minimum capacity (i.e., the worst relay), is analyzed and it
is shown that the remaining $(N-1)$-relay subnetwork has an approximate (i.e.,
optimal up to a constant gap) HD capacity that is at least half of the
approximate HD capacity of the full network. This fraction guarantee is shown
to be tight if only the single relay capacities are known, i.e., there exists a
class of Gaussian HD diamond networks with $N$ relays where, by removing the
worst relay, the subnetwork of the remaining $k=N-1$ relays has an approximate
capacity equal to half of the approximate capacity of the full network. Next,
this work proves a fundamental guarantee, which improves over the previous
fraction: there always exists a subnetwork of $k=N-1$ relays that achieves at
least a fraction $\frac{N-1}{N}$ of the approximate capacity of the full
network. This fraction is proved to be tight and it is shown that any optimal
schedule of the full network can be used by at least one of the $N$ subnetworks
of $N-1$ relays to achieve a worst-case performance guarantee of
$\frac{N-1}{N}$. Additionally, these results are extended to derive lower
bounds on the fraction guarantee for general $k \in [1:N]$. The key steps in
the proofs lie in the derivation of properties of submodular functions, which
provide a combinatorial handle on the network simplification problem in
Gaussian HD diamond networks.


title: Global versus Local -- Mach's Principle versus the Equivalence Principle

abstract:
  The equivalence principle is the conceptual basis for general relativity. In
contrast Mach's principle, although said to have been influential on Einstein
in his formulation of general relativity, has not been shown to be central to
the structure of general relativity. In this essay we suggest that the quantum
effects of Hawking and Unruh radiation are a manifestation of a {\it thermal}
Mach's principle, where the local thermodynamic properties of the system are
determined by the non-local structure of the quantum fields which determine the
vacuum of a given spacetime. By comparing Hawking and Unruh temperatures for
the same local acceleration we find a violation of the Einstein elevator
version of the equivalence principle, which vanishes in the limit that the
horizon is approached.


title:
Breakout: An Open Measurement and Intervention Tool for Distributed Peer
  Learning Groups

abstract:
  We present Breakout, a group interaction platform for online courses that
enables the creation and measurement of face-to-face peer learning groups in
online settings. Breakout is designed to help students easily engage in
synchronous, video breakout session based peer learning in settings that
otherwise force students to rely on asynchronous text-based communication. The
platform also offers data collection and intervention tools for studying the
communication patterns inherent in online learning environments. The goals of
the system are twofold: to enhance student engagement in online learning
settings and to create a platform for research into the relationship between
distributed group interaction patterns and learning outcomes.


title: Effectiveness of Rapid Rail Transit System in Beijing

abstract:
  The effectiveness of rapid rail transit system is analyzed using tools of
complex network for the first time. We evaluated the effectiveness of the
system in Beijing quantitatively from different perspectives, including
descriptive statistics analysis, bridging property, centrality property,
ability of connecting different part of the system and ability of disease
spreading. The results showed that the public transport of Beijing does benefit
from the rapid rail transit lines, but there is still room to improve. The
paper concluded with some policy suggestions regarding how to promote the
system. This study offered significant insight that can help understand the
public transportation better. The methodology can be easily applied to analyze
other urban public systems, such as electricity grid, water system, to develop
more livable cities.


title: On Szeg\H{o}'s theorem for a nonclassical case

abstract:
  In this paper we prove Szeg\H{o}'s Theorem for the case when a finite number
of Verblunsky coefficients lie outside the closed unit disk. Although a form of
this result was already proved by A.L. Sakhnovich, we use a very different
method, which shows that the OPUC machinery can still be applied to deal with
such nonclassical cases. The basic tool we use is Khrushchev's formula that in
the classical case relates the absolutely continuous part of the measure and
the $N$-th iterate of the Schur algorithm. It is noteworthy that Khrushchev's
formula makes the proof short and extremely transparent. Also, we discuss
Verblunsky's theorem for the case in question.


title: GASS 3505: the prototype of HI-excess, passive galaxies

abstract:
  We present our multiwavelength analysis of a prototype \HI-excess galaxy,
GASS 3505, selected based on having a large gas content ($M_{\rm HI} =
10^{9.9}$ \msun) compared to its little associated star formation activity
($\sim$0.1 \msun\ yr$^{-1}$) in the GALEX Arecibo SDSS Survey (GASS). Very
Large Array (VLA) observations show that the \HI\ in GASS 3505 is distributed
in a regularly rotating, extended ($\sim$50 kpc radius) gas ring. In the SDSS
optical image GASS 3505 appears as a bulge-dominated galaxy, however deep
optical imaging reveals low surface brightness ($\gtrsim25$ mag arcsec$^{-2}$)
stellar emission around the central bulge. Direct evidence for accretion is
detected in form of an extended ($\sim$60 kpc) stellar stream, showing that
GASS 3505 has experienced a minor merger in the recent past. We investigate the
possibility that the \HI\ ring in GASS 3505 was accreted in such a merger event
using N-body and smoothed particle hydrodynamic (SPH) simulations. The best
model that reproduces the general properties (i.e., gas distribution and
kinematics, stellar morphology) of the galaxy involves a merger between the
central bulge and a gas-rich ($M_{\star}$ = 10$^9$ \msun\ and $M_{\rm
HI}$/$M_{\star}$ = 10) disk galaxy. However, small discrepancies in the
observed and modeled properties could suggest that other sources of gas have to
be involved in the build-up of the gas reservoir. This work is the first step
toward a larger program to investigate the physical mechanisms that drive the
large scatter in the gas scaling relations of nearby galaxies.


title:
Direct virtual photon production in Au+Au collisions at $\sqrt{s_{NN}}$
  = 200 GeV

abstract:
  We report the direct virtual photon invariant yields in the transverse
momentum ranges $1\!<\!p_{T}\!<\!3$ GeV/$c$ and $5\!<\!p_T\!<\!10$ GeV/$c$ at
mid-rapidity derived from the dielectron invariant mass continuum region
$0.10<M_{ee}<0.28$ GeV/$c^{2}$ for 0-80\% minimum-bias Au+Au collisions at
$\sqrt{s_{NN}}=200$ GeV. A clear excess in the invariant yield compared to the
number-of-binary-collisions ($N_{bin}$) scaled $p+p$ reference is observed in
the $p_T$ range $1\!<\!p_{T}\!<\!3$ GeV/$c$. For $p_T\!>6$ GeV/$c$ the
production follows $N_{bin}$ scaling. Model calculations with contributions
from thermal radiation and initial hard parton scattering are consistent within
uncertainties with the direct virtual photon invariant yield.


title:
Nuclear neutrino energy spectra in high temperature astrophysical
  environments

abstract:
  Astrophysical environments that reach temperatures greater than $\sim$ 100
keV can have significant neutrino energy loss via both plasma processes and
nuclear weak interactions. We find that nuclear processes likely produce the
highest-energy neutrinos. Among the important weak nuclear interactions are
both charged current channels (electron capture/emission and positron
capture/emission) and neutral current channels (de-excitation of nuclei via
neutrino pair emission). We show that in order to make a realistic prediction
of the nuclear neutrino spectrum, one must take nuclear structure into account;
in some cases, the most important transitions may involve excited states,
possibly in both parent and daughter nuclei. We find that the standard
technique of producing a neutrino energy spectrum by using a single transition
with a Q-value and matrix element chosen to fit published neutrino production
rates and energy losses will not accurately capture important spectral
features.


title:
Stochastic multi-scale models of competition within heterogeneous
  cellular populations: simulation methods and mean-field analysis

abstract:
  We propose a modelling framework to analyse the stochastic behaviour of
heterogeneous, multi-scale cellular populations. We illustrate our methodology
with a particular example in which we study a population with an
oxygen-regulated proliferation rate. Our formulation is based on an
age-dependent stochastic process. Cells within the population are characterised
by their age. The age-dependent (oxygen-regulated) birth rate is given by a
stochastic model of oxygen-dependent cell cycle progression. We then formulate
an age-dependent birth-and-death process, which dictates the time evolution of
the cell population. The population is under a feedback loop which controls its
steady state size: cells consume oxygen which in turns fuels cell
proliferation. We show that our stochastic model of cell cycle progression
allows for heterogeneity within the cell population induced by stochastic
effects. Such heterogeneous behaviour is reflected in variations in the
proliferation rate. Within this set-up, we have established three main results.
First, we have shown that the age to the G1/S transition, which essentially
determines the birth rate, exhibits a remarkably simple scaling behaviour. This
allows for a huge simplification of our numerical methodology. A further result
is the observation that heterogeneous populations undergo an internal process
of quasi-neutral competition. Finally, we investigated the effects of
cell-cycle-phase dependent therapies (such as radiation therapy) on
heterogeneous populations. In particular, we have studied the case in which the
population contains a quiescent sub-population. Our mean-field analysis and
numerical simulations confirm that, if the survival fraction of the therapy is
too high, rescue of the quiescent population occurs. This gives rise to
emergence of resistance to therapy since the rescued population is less
sensitive to therapy.


title: Pooling Faces: Template based Face Recognition with Pooled Face Images

abstract:
  We propose a novel approach to template based face recognition. Our dual goal
is to both increase recognition accuracy and reduce the computational and
storage costs of template matching. To do this, we leverage on an approach
which was proven effective in many other domains, but, to our knowledge, never
fully explored for face images: average pooling of face photos. We show how
(and why!) the space of a template's images can be partitioned and then pooled
based on image quality and head pose and the effect this has on accuracy and
template size. We perform extensive tests on the IJB-A and Janus CS2 template
based face identification and verification benchmarks. These show that not only
does our approach outperform published state of the art despite requiring far
fewer cross template comparisons, but also, surprisingly, that image pooling
performs on par with deep feature pooling.


title: Some elementary observations regarding reductive Cartan geometries

abstract:
  After defining generalizations of the notions of covariant derivatives and
geodesics from Riemannian geometry for reductive Cartan geometries in general,
various results for reductive Cartan geometries analogous to important
elementary results from Riemannian geometry are proven using these
generalizations. In particular, a generalization of the Hopf-Rinow theorem is
given with a pleasantly concise proof.


title: Recent advances in coarse-grained modeling of virus assembly

abstract:
  In many virus families, tens to thousands of proteins assemble spontaneously
into a capsid (protein shell) while packaging the genomic nucleic acid. This
review summarizes recent advances in computational modeling of these dynamical
processes. We present an overview of recent technological and algorithmic
developments, which are enabling simulations to describe the large ranges of
length-and time-scales relevant to assembly, under conditions more closely
matched to experiments than in earlier work. We then describe two examples in
which computational modeling has recently provided an important complement to
experiments.


title:
LAMOST observations in the Kepler field. Analysis of the stellar
  parameters measured with the LASP based on the low-resolution spectra

abstract:
  All of the 14 subfields of the Kepler field have been observed at least once
with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST,
Xinglong Observatory, China) during the 2012-2014 observation seasons. There
are 88,628 reduced spectra with SNR$_g$ (signal-to-noise ratio in g band)
$\geq$ 6 after the first round (2012-2014) of observations for the
LAMOST-Kepler project (LK-project). By adopting the upgraded version of the
LAMOST Stellar Parameter pipeline (LASP), we have determined the atmospheric
parameters ($T_{\rm eff}$ , $\log g$, and $\rm [Fe/H]$) and heliocentric radial
velocity $v_{\rm rad}$ for 51,406 stars with 61,226 spectra. Compared with
atmospheric parameters derived from both high-resolution spectroscopy and
asteroseismology method for common stars in Huber et al. (2014), an external
calibration of LASP atmospheric parameters was made, leading to the
determination of external errors for the giants and dwarfs, respectively.
Multiple spectroscopic observations for the same objects of the LK-project were
used to estimate the internal uncertainties of the atmospheric parameters as a
function of SNR$_g$ with the unbiased estimation method. The LASP atmospheric
parameters were calibrated based on both the external and internal
uncertainties for the giants and dwarfs, respectively. A general statistical
analysis of the stellar parameters leads to discovery of 106 candidate
metal-poor stars, 9 candidate very metal-poor stars, and 18 candidate
high-velocity stars. Fitting formulae were obtained segmentally for both the
calibrated atmospheric parameters of the LK-project and the KIC parameters with
the common stars. The calibrated atmospheric parameters and radial velocities
of the LK-project will be useful for studying stars in the Kepler field.


title: Verifying quantum superpositions at metre scales

abstract:
  While the existence of quantum superpositions of massive particles over
microscopic separations has been established since the birth of quantum
mechanics, the maintenance of superposition states over macroscopic separations
is a subject of modern experimental tests. In Ref. [1], T. Kovachy et al.
report on applying optical pulses to place a freely falling Bose-Einstein
condensate into a superposition of two trajectories that separate by an
impressive distance of 54 cm before being redirected toward one another. When
the trajectories overlap, a final optical pulse produces interference with high
contrast, but with random phase, between the two wave packets. Contrary to
claims made in Ref. [1], we argue that the observed interference is consistent
with, but does not prove, that the spatially separated atomic ensembles were in
a quantum superposition state. Therefore, the persistence of such superposition
states remains experimentally unestablished.


title:
Simultaneous light emission and detection of InGaN/GaN multiple quantum
  well diodes for in-plane visible light communication on a chip

abstract:
  This paper presents the design, fabrication, and experimental
characterization of monolithically integrated p-n junction InGaN/GaN multiple
quantum well diodes (MQWDs) and suspended waveguides. Suspended MQWDs can be
used as transmitters and receivers simultaneously, and suspended waveguides are
used for light coupling to create an in-plane visible light communication
system. Compared to the waveguide with separation trench, the calculated total
light efficiency is increased from 18% to 22% for the continuous waveguide. The
MQWDs are characterized by their typical current-voltage performance, and the
pulse excitation measurements confirm that the InGaN/GaN MQWDs can achieve the
light emission and photodetection at the same time. The photocurrent
measurements indicate that the photocurrent is modulated by a bias voltage and
that the photons are being supplied from another transmitter. An experimental
demonstration is presented showing that the proposed device works well for
in-plane full-duplex communication using visible light.


title: Decomposing 8-regular graphs into paths of length 4

abstract:
  A $T$-decomposition of a graph $G$ is a set of edge-disjoint copies of $T$ in
$G$ that cover the edge set of $G$. Graham and H\"aggkvist (1989) conjectured
that any $2\ell$-regular graph $G$ admits a $T$-decomposition if $T$ is a tree
with $\ell$ edges. Kouider and Lonc (1999) conjectured that, in the special
case where $T$ is the path with $\ell$ edges, $G$ admits a $T$-decomposition
$\mathcal{D}$ where every vertex of $G$ is the end-vertex of exactly two paths
of $\mathcal{D}$, and proved that this statement holds when $G$ has girth at
least $(\ell+3)/2$. In this paper we verify Kouider and Lonc's Conjecture for
paths of length $4$.


title: String C-groups from groups of order 2^m and exponent at least 2^(m - 3)

abstract:
  This work provides a classification of string C-groups of order 2m and
exponent at least 2^(m - 3). Prior to the classification, we complete the list
of groups of exponent 2^(m - 3) and rank at least 3. The main result states
that, aside from the cyclic and dihedral groups, only two groups of exponent at
least 2^(m - 3) are connected string C-groups. Both have rank 3 and are
quotients of the string Coxeter group W = [4, 2^(m - 3)].


title: A hybrid adaptive MCMC algorithm in function spaces

abstract:
  The preconditioned Crank-Nicolson (pCN) method is a Markov Chain Monte Carlo
(MCMC) scheme, specifically designed to perform Bayesian inferences in function
spaces. Unlike many standard MCMC algorithms, the pCN method can preserve the
sampling efficiency under the mesh refinement, a property referred to as being
dimension independent. In this work we consider an adaptive strategy to further
improve the efficiency of pCN. In particular we develop a hybrid adaptive MCMC
method: the algorithm performs an adaptive Metropolis scheme in a chosen finite
dimensional subspace, and a standard pCN algorithm in the complement space of
the chosen subspace. We show that the proposed algorithm satisfies certain
important ergodicity conditions. Finally with numerical examples we demonstrate
that the proposed method has competitive performance with existing adaptive
algorithms.


title:
Experimental demonstration of spontaneous chirality in a nonlinear
  microresonator

abstract:
  Chirality is an important concept that describes the asymmetry property of a
system, which usually emerges spontaneously due to mirror symmetry breaking.
Such spontaneous chirality manifests predominantly as parity breaking in modern
physics, which has been studied extensively, for instance, in Higgs physics,
double-well Bose-Einstein condensates, topological insulators and
superconductors. In the optical domain, spontaneous chiral symmetry breaking
has been elusive experimentally, especially for micro- and nano-photonics which
demands multiple identical subsystems, such as photonic nanocavities,
meta-molecules and other dual-core settings. Here, for the first time, we
observe spontaneous emergence of a chiral field in a single ultrahigh-Q
whispering- gallery microresonator. This counter-intuitive effect arises due to
the inherent Kerr nonlinearity-modulated coupling between clockwise (CW) and
counterclockwise (CCW) propagating waves. At an ultra-weak input threshold of a
few hundred microwatts, the initial chiral symmetry is broken spontaneously,
and the CW-to-CCW output ratio reaches 20:1. The spontaneous chirality in
microresonator holds great potential in studies of fundamental physics and
applied photonic devices.


title:
The universe on a table top: engineering quantum decay of a relativistic
  scalar field from a metastable vacuum

abstract:
  The quantum decay of a relativistic scalar field from a metastable state
("false vacuum decay") is a fundamental idea in quantum field theory and
cosmology. This occurs via local formation of bubbles of true vacuum with their
subsequent rapid expansion. It can be considered as a relativistic analog of a
first-order phase transition in condensed matter. Here we expand upon our
recent proposal [EPL 110, 56001 (2015)] for an experimental test of false
vacuum decay using an ultra-cold spinor Bose gas. A false vacuum for the
relative phase of two spin components, serving as the unstable scalar field, is
generated by means of a modulated linear coupling of the spin components. We
analyze the system theoretically using the functional integral approach and
show that various microscopic degrees of freedom in the system, albeit leading
to dissipation in the relative phase sector, will not hamper the observation of
the false vacuum decay in the laboratory. This is well supported by numerical
simulations demonstrating the spontaneous formation of true vacuum bubbles on
millisecond time-scales in two-component $^{7}$Li or $^{41}$K bosonic
condensates in one-dimensional traps of $\sim100\,\mu \mathrm{m}$ size.


title:
On the Minimum Mean $p$-th Error in Gaussian Noise Channels and its
  Applications

abstract:
  The problem of estimating an arbitrary random vector from its observation
corrupted by additive white Gaussian noise, where the cost function is taken to
be the Minimum Mean $p$-th Error (MMPE), is considered. The classical Minimum
Mean Square Error (MMSE) is a special case of the MMPE. Several bounds,
properties and applications of the MMPE are derived and discussed. The optimal
MMPE estimator is found for Gaussian and binary input distributions. Properties
of the MMPE as a function of the input distribution, SNR and order $p$ are
derived. In particular, it is shown that the MMPE is a continuous function of
$p$ and SNR. These results are possible in view of interpolation and change of
measure bounds on the MMPE. The `Single-Crossing-Point Property' (SCPP) that
bounds the MMSE for all SNR values {\it above} a certain value, at which the
MMSE is known, together with the I-MMSE relationship is a powerful tool in
deriving converse proofs in information theory. By studying the notion of
conditional MMPE, a unifying proof (i.e., for any $p$) of the SCPP is shown. A
complementary bound to the SCPP is then shown, which bounds the MMPE for all
SNR values {\it below} a certain value, at which the MMPE is known. As a first
application of the MMPE, a bound on the conditional differential entropy in
terms of the MMPE is provided, which then yields a generalization of the
Ozarow-Wyner lower bound on the mutual information achieved by a discrete input
on a Gaussian noise channel. As a second application, the MMPE is shown to
improve on previous characterizations of the phase transition phenomenon that
manifests, in the limit as the length of the capacity achieving code goes to
infinity, as a discontinuity of the MMSE as a function of SNR. As a final
application, the MMPE is used to show bounds on the second derivative of mutual
information, that tighten previously known bounds.


title: An optimal learning method for developing personalized treatment regimes

abstract:
  A treatment regime is a function that maps individual patient information to
a recommended treatment, hence explicitly incorporating the heterogeneity in
need for treatment across individuals. Patient responses are dichotomous and
can be predicted through an unknown relationship that depends on the patient
information and the selected treatment. The goal is to find the treatments that
lead to the best patient responses on average. Each experiment is expensive,
forcing us to learn the most from each experiment. We adopt a Bayesian approach
both to incorporate possible prior information and to update our treatment
regime continuously as information accrues, with the potential to allow smaller
yet more informative trials and for patients to receive better treatment. By
formulating the problem as contextual bandits, we introduce a knowledge
gradient policy to guide the treatment assignment by maximizing the expected
value of information, for which an approximation method is used to overcome
computational challenges. We provide a detailed study on how to make sequential
medical decisions under uncertainty to reduce health care costs on a real world
knee replacement dataset. We use clustering and LASSO to deal with the
intrinsic sparsity in health datasets. We show experimentally that even though
the problem is sparse, through careful selection of physicians (versus picking
them at random), we can significantly improve the success rates.


title: Signatures of an annular Fermi sea

abstract:
  We report Shubnikov-de Haas oscillations measurements revealing experimental
signatures of an annular Fermi sea that develops near the energy band edge of
the excited subband of two-dimensional holes confined in a wide GaAs quantum
well. As we increase the hole density, when the Fermi level reaches the excited
subband edge, the low-field magnetoresistance traces show a sudden emergence of
new oscillations at an unexpectedly large frequency whose value does
$\textit{not}$ correspond to the (negligible) density of holes in the excited
subband. There is also a sharp and significant increase in zero-field
resistance near this onset of subband occupation. Guided by numerical energy
dispersion calculations, we associate these observations with the unusual shape
of the excited subband dispersion which results in a "ring of extrema" at
finite wavevectors and an annular Fermi sea. Such a dispersion and Fermi sea
have long been expected from energy band calculations in systems with strong
spin-orbit interaction but their experimental signatures have been elusive.


title: Phenomenology of Bulk Scalar Singlets in the Randall Sundrum Model

abstract:
  We present a Randall-Sundrum toy model with an added scalar singlet that
couples only to KK fermions in the bulk. Such a scalar would nontrivially
affect radion phenomenology. In addition, we examine the radion phenomenology
in light of the new scalar and show how this scalar could present another probe
to search for the radion.


title:
Heralded single excitation of atomic ensemble via solid-state-based
  telecom photon detection

abstract:
  Telecom photonic quantum networks with matter quantum systems enable a rich
variety of applications, such as a long distance quantum cryptography and
one-way quantum computing. Preparation of a heralded single excitation (HSE) in
an atomic ensemble by detecting a telecom wavelength photon having a
correlation with the atomic excitation is an important step. Such a system has
been demonstrated with a quantum frequency conversion (QFC) to telecom
wavelength employing a Rb atomic cloud. However the limited wavelength
selection prevents the next step. Here we for the first time demonstrate HSE
with a solid-state-based QFC and a detector for a telecom wavelength that will
have a great advantage of the utility of mature telecom technologies. We
unambiguously show that the demonstrated HSE indicates a non-classical
statistics by the direct measurement of the autocorrelation function.


title: An intrinsic hyperboloid approach for Einstein Klein-Gordon equations

abstract:
  In [7] Klainerman introduced the hyperboloidal method to prove the global
existence results for nonlinear Klein-Gordon equations by using commuting
vector fields. In this paper, we extend the hyperboloidal method from Minkowski
space to Lorentzian spacetimes. This approach is developed in [14] for proving,
under the maximal foliation gauge, the global nonlinear stability of Minkowski
space for Einstein equations with massive scalar fields, which states that, the
sufficiently small data in a compact domain, surrounded by a Schwarzschild
metric, leads to a unique, globally hyperbolic, smooth and geodesically
complete solution to the Einstein Klein-Gordon system.
  In this paper, we set up the geometric framework of the intrinsic hyperboloid
approach in the curved spacetime. By performing a thorough geometric comparison
between the radial normal vector field induced by the intrinsic hyperboloids
and the canonical $\p_r$, we manage to control the hyperboloids when they are
close to their asymptote, which is a light cone in the Schwarzschild zone. By
using such geometric information, we not only obtain the crucial boundary
information for running the energy method in [14], but also prove that the
intrinsic geometric quantities including the Hawking mass all converge to their
Schwarzschild values when approaching the asymptote.


title: Butterflies from Information Metric

abstract:
  We study time evolution of distance between thermal states excited by local
operators, with different external couplings. We find that growth of the
distance implies growth of commutators of operators, signifying the local
excitations are scrambled. We confirm this growth of distance by holographic
computation, by evaluating volume of codimension 1 extremal volume surface. We
find that the distance increases exponentially as $e^{\frac{2\pi t}{\beta}}$.
Our result implies that, in chaotic system, trajectories of excited thermal
states exhibit high sensitivity to perturbation to the Hamiltonian, and the
distance between them will be significant at the scrambling time. We also
confirm the decay of two point function of holographic Wilson loops on
thermofield double state.


title: Dark matter, light mediators, and the neutrino floor

abstract:
  We analyze future direct data matter detection experiments using Effective
Field Theory (EFT) operators with light, $\lesssim 100$ MeV mass mediators. We
compare the nuclear recoil energy spectra from these operators to the predicted
high energy solar neutrino spectrum. A set of operators that generate spectra
similar to the neutrino background is identified, however this set is distinct
from those that mimic the neutrino background for heavy, $\gtrsim 100$ MeV mass
mediators. We outline a general classification scheme based on momentum
dependence of the dark matter-nucleus interaction to determine how strong the
discovery limit for a given operator saturates in the presence of the neutrino
background. Our results highlight the benefit of considering a general
theoretical framework regarding dark matter, and motivate continued
experimental progress towards lower nuclear recoil energy thresholds.


title:
Freeze-in Production of Sterile Neutrino Dark Matter in U(1)$_{\rm B-L}$
  Model

abstract:
  With the advent of new and more sensitive direct detection experiments, scope
for a thermal WIMP explanation of dark matter (DM) has become extremely
constricted. The non-observation of thermal WIMP in these experiments has put a
strong upper bound on WIMP-nucleon scattering cross section and within a few
years it is likely to touch the neutrino floor. Hence in all probability, DM
may have some non-thermal origin. In this work we explore in detail this
possibility of a non-thermal sterile neutrino DM within the framework of
U(1)$_{\rm B-L}$ model. The U(1)$_{\rm B-L}$ model on the other hand is a
well-motivated and minimal way of extending the standard model so that it can
explain the neutrino masses via Type-I see-saw mechanism. We have shown,
besides explaining the neutrino mass, it can also accommodate a non-thermal
sterile neutrino DM with correct relic density. In contrast with the existing
literature, we have found that $W^\pm$ decay can also be a dominant production
mode of the sterile neutrino DM. To obtain the comoving number density of dark
matter, we have solved here a coupled set of Boltzmann equations considering
all possible decay as well as annihilation production modes of the sterile
neutrino dark matter. The framework developed here though has been done for a
U(1)$_{\rm B-L}$ model, can be applied quite generally for any models with an
extra neutral gauge boson and a fermionic non-thermal dark matter.


title:
XPS and DFT study of pulsed Bi-implantation of bulk and thin-films of
  ZnO - the role of oxygen imperfections

abstract:
  An atomic and electronic structure of the bulk and thin-film morphologies of
ZnO were modified using pulsed Bi-ion implantation (1x1017 cm-2 fluence, 70 min
exposure under Bi-ion beam, EBi+ = 30 keV, pulsed ion-current density of not
more than 0.8 mA/cm2 with a repetition rate of 12.5 Hz). The final samples were
qualified by X-ray photoelectron core-level and valence band mapping
spectroscopy applying ASTM materials science standard. The spectroscopy data
obtained was discussed on the basis of DFT-models for Bi-embedding into ZnO
host-matrices. It was established that in the case of direct Bi-impurities
insertion into the employed ZnO-host for both studied morphologies neither the
only "pure" Bi2O3-like phase nor the only "pure" Bi-metal will be preferable to
appear as a secondary phase. An unfavorability of the large cluster
agglomeration of Bi-impurities in ZnO-hosts has been shown and an oxygen 2s
electronic states pleomorphizm was surely established.


title:
Cryptanalysis and Improvement of an Improved Two Factor Authentication
  Scheme for Telecare Medicine Information Systems

abstract:
  Telecare medical information systems (TMIS) aim to provide healthcare
services remotely. Efficient and secure mechanism for authentication and key
agreement is required in order to guarantee the security and privacy of
patients in TMIS.


title:
FSO-based Vertical Backhaul/Fronthaul Framework for 5G+ Wireless
  Networks

abstract:
  The presence of a super high rate, but also cost-efficient, easy-to-deploy,
and scalable, backhaul/fronthaul framework is essential in the upcoming
fifth-generation (5G) wireless networks \& beyond. Motivated by the mounting
interest in the unmanned flying platforms of various types including unmanned
aerial vehicles (UAVs), drones, balloons, and
high-altitude/medium-altitude/low-altitude platforms (HAPs/MAPs/LAPs), which we
refer to as the networked flying platforms (NFPs), for providing communications
services and the recent advances in free-space optics (FSO), this article
investigates the feasibility of a novel vertical backhaul/fronthaul framework
where the NFPs transport the backhaul/fronthaul traffic between the access and
core networks via point-to-point FSO links. The performance of the proposed
innovative approach is investigated under different weather conditions and a
broad range of system parameters. Simulation results demonstrate that the
FSO-based vertical backhaul/fronthaul framework can offer data rates higher
than the baseline alternatives, and thus can be considered as a promising
solution to the emerging backhaul/fronthaul requirements of the 5G+ wireless
networks, particularly in the presence of ultra-dense heterogeneous small
cells. The paper also presents the challenges that accompany such a novel
framework and provides some key ideas towards overcoming these challenges.


title: Holographic Beam Mapping of the CHIME Pathfinder Array

abstract:
  The Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder radio
telescope is currently surveying the northern hemisphere between 400 and 800
MHz. By mapping the large scale structure of neutral hydrogen through its
redshifted 21 cm line emission between $z \sim 0.8-2.5$ CHIME will contribute
to our understanding of Dark Energy. Bright astrophysical foregrounds must be
separated from the neutral hydrogen signal, a task which requires precise
characterization of the polarized telescope beams. Using the DRAO John A. Galt
26 m telescope, we have developed a holography instrument and technique for
mapping the CHIME Pathfinder beams. We report the status of the instrument and
initial results of this effort.


title:
Synthesising Strategy Improvement and Recursive Algorithms for Solving
  2.5 Player Parity Games

abstract:
  2.5 player parity games combine the challenges posed by 2.5 player
reachability games and the qualitative analysis of parity games. These two
types of problems are best approached with different types of algorithms:
strategy improvement algorithms for 2.5 player reachability games and recursive
algorithms for the qualitative analysis of parity games. We present a method
that - in contrast to existing techniques - tackles both aspects with the best
suited approach and works exclusively on the 2.5 player game itself. The
resulting technique is powerful enough to handle games with several million
states.


title:
Preconditioned Steepest Descent Methods for some Nonlinear Elliptic
  Equations Involving p-Laplacian Terms

abstract:
  We describe and analyze preconditioned steepest descent (PSD) solvers for
fourth and sixth-order nonlinear elliptic equations that include p-Laplacian
terms on periodic domains in 2 and 3 dimensions. The highest and lowest order
terms of the equations are constant-coefficient, positive linear operators,
which suggests a natural preconditioning strategy. Such nonlinear elliptic
equations often arise from time discretization of parabolic equations that
model various biological and physical phenomena, in particular, liquid
crystals, thin film epitaxial growth and phase transformations. The analyses of
the schemes involve the characterization of the strictly convex energies
associated with the equations. We first give a general framework for PSD in
generic Hilbert spaces. Based on certain reasonable assumptions of the linear
pre-conditioner, a geometric convergence rate is shown for the nonlinear PSD
iteration. We then apply the general the theory to the fourth and sixth-order
problems of interest, making use of Sobolev embedding and regularity results to
confirm the appropriateness of our pre-conditioners for the regularized
p-Lapacian problems. Our results include a sharper theoretical convergence
result for p-Laplacian systems compared to what may be found in existing works.
We demonstrate rigorously how to apply the theory in the finite dimensional
setting using finite difference discretization methods. Numerical simulations
for some important physical application problems -- including thin film epitaxy
with slope selection and the square phase field crystal model -- are carried
out to verify the efficiency of the scheme.


title:
Germanium Collimating micro-Channel Arrays For High Resolution, High
  Energy Confocal X-ray Fluorescence Microscopy

abstract:
  Confocal x-ray fluorescence microscopy (CXRF) allows direct detection of
x-ray fluorescence from a micron-scale 3D volume of an extended, unthinned
sample. We have previously demonstrated the use of a novel collection optic,
fabricated from silicon, that improves the spatial resolution of this approach
by an order of magnitude over CXRF using polycapillaries. The optic, called a
collimating channel array (CCA), consists of micron-scale,
lithographically-fabricated arrays of collimating channels, all directed
towards a single source position. Due to the limited absorbing power of
silicon, the useful energy range of these optics was limited to fluorescence
emission below about 10 keV. Here, we report fabrication of CCAs from germanium
substrates, and demonstrate their practical use for CXRF up to 20 keV.
Specifically we demonstrate a nearly energy-independent critical spatial
resolution $d_R$ of 2.1$\pm$0.17 \um from 2-20 keV, as well as excellent
background reduction compared to silicon-based CCAs throughout this energy
range. Design details of the optic and background-reduction holder are
described. Two versions of the optic are now available upon request at the
beamline 20ID-B, Advanced Photon Source (APS) - Argonne National Laboratory.


title:
Accelerating eigenvector and pseudospectra computation using blocked
  multi-shift triangular solves

abstract:
  Multi-shift triangular solves are basic linear algebra calculations with
applications in eigenvector and pseudospectra computation. We propose blocked
algorithms that efficiently exploit Level 3 BLAS to perform multi-shift
triangular solves and safe multi-shift triangular solves. Numerical experiments
indicate that computing triangular eigenvectors with a safe multi-shift
triangular solve achieves speedups by a factor of 60 relative to LAPACK. This
algorithm accelerates the calculation of general eigenvectors threefold. When
using multi-shift triangular solves to compute pseudospectra, we report
ninefold speedups relative to EigTool.


title: Mixed Strategy for Constrained Stochastic Optimal Control

abstract:
  Choosing control inputs randomly can result in a reduced expected cost in
optimal control problems with stochastic constraints, such as stochastic model
predictive control (SMPC). We consider a controller with initial randomization,
meaning that the controller randomly chooses from K+1 control sequences at the
beginning (called K-randimization).It is known that, for a finite-state,
finite-action Markov Decision Process (MDP) with K constraints, K-randimization
is sufficient to achieve the minimum cost. We found that the same result holds
for stochastic optimal control problems with continuous state and action
spaces.Furthermore, we show the randomization of control input can result in
reduced cost when the optimization problem is nonconvex, and the cost reduction
is equal to the duality gap. We then provide the necessary and sufficient
conditions for the optimality of a randomized solution, and develop an
efficient solution method based on dual optimization. Furthermore, in a special
case with K=1 such as a joint chance-constrained problem, the dual optimization
can be solved even more efficiently by root finding. Finally, we test the
theories and demonstrate the solution method on multiple practical problems
ranging from path planning to the planning of entry, descent, and landing (EDL)
for future Mars missions.


title:
Orbital stability of Gausson solutions to logarithmic Schr\"odinger
  equations

abstract:
  In this paper we present a proof of the orbital stability of ground state for
logarithmic Schr\"odinger equation in any dimension and under nonradial
perturbations.


title: Attosecond physics at the nanoscale

abstract:
  Recently two emerging areas of research, attosecond and nanoscale physics,
have started to come together. Attosecond physics deals with phenomena
occurring when ultrashort laser pulses, with duration on the femto- and
sub-femtosecond time scales, interact with atoms, molecules or solids. The
laser-induced electron dynamics occurs natively on a timescale down to a few
hundred or even tens of attoseconds, which is comparable with the optical
field. On the other hand, the second branch involves the manipulation and
engineering of mesoscopic systems, such as solids, metals and dielectrics, with
nanometric precision. Although nano-engineering is a vast and well-established
research field on its own, the merger with intense laser physics is relatively
recent. In this article we present a comprehensive experimental and theoretical
overview of physics that takes place when short and intense laser pulses
interact with nanosystems, such as metallic and dielectric nanostructures. In
particular we elucidate how the spatially inhomogeneous laser induced fields at
a nanometer scale modify the laser-driven electron dynamics. Consequently, this
has important impact on pivotal processes such as ATI and HHG. The deep
understanding of the coupled dynamics between these spatially inhomogeneous
fields and matter configures a promising way to new avenues of research and
applications. Thanks to the maturity that attosecond physics has reached,
together with the tremendous advance in material engineering and manipulation
techniques, the age of atto-nano physics has begun, but it is in the initial
stage. We present thus some of the open questions, challenges and prospects for
experimental confirmation of theoretical predictions, as well as experiments
aimed at characterizing the induced fields and the unique electron dynamics
initiated by them with high temporal and spatial resolution.


title:
Escape rate for special semi-flows over non-invertible subshifts of
  finite type

abstract:
  We prove an escape rate result for special semi-flows over non-invertible
subshifts of finite type. Our proofs are based on a discretisation of the flow
and an application of an escape rate result for conformal repellers.


title:
Consensus and disagreement: the role of quantized behaviours in opinion
  dynamics

abstract:
  This paper deals with continuous-time opinion dynamics that feature the
interplay of continuous opinions and discrete behaviours. In our model, the
opinion of one individual is only influenced by the behaviours of fellow
individuals. The key technical difficulty in the study of these dynamics is
that the right-hand sides of the equations are discontinuous and thus their
solutions must be intended in some generalized sense: in our analysis, we
consider both Carath\'eodory and Krasowskii solutions. We first prove existence
and completeness of Carath\'eodory solutions from every initial condition and
we highlight a pathological behaviour of Carath\'eodory solutions, which can
converge to points that are not (Carath\'eodory) equilibria. Notably, such
points can be arbitrarily far from consensus and indeed simulations show that
convergence to non-consensus configurations is very common. In order to cope
with these pathological attractors, we then study Krasowskii solutions. We give
an estimate of the asymptotic distance of all Krasowskii solutions from
consensus and we prove its tightness via an example: this estimate is quadratic
in the number of agents, implying that quantization can drastically destroy
consensus. However, we are able to prove convergence to consensus in some
special cases, namely when the communication among the individuals is described
by either a complete or a complete bipartite graph.


title: Galaxy growth from redshift 5 to 0 at fixed comoving number density

abstract:
  Studying the average properties of galaxies at a fixed comoving number
density over a wide redshift range has become a popular observational method,
because it may trace the evolution of galaxies statistically. We test this
method by comparing the evolution of galaxies at fixed number density and by
following individual galaxies through cosmic time (z=0-5) in cosmological,
hydrodynamical simulations from OWLS. Comparing progenitors, descendants, and
galaxies selected at fixed number density at each redshift, we find differences
of up to a factor of three for galaxy and interstellar medium (ISM) masses. The
difference is somewhat larger for black hole masses. The scatter in ISM mass
increases significantly towards low redshift with all selection techniques. We
use the fixed number density technique to study the assembly of dark matter,
gas, stars, and black holes and the evolution in accretion and star formation
rates. We find three different regimes for massive galaxies, consistent with
observations: at high redshift the gas accretion rate dominates, at
intermediate redshifts the star formation rate is the highest, and at low
redshift galaxies grow mostly through mergers. Quiescent galaxies have much
lower ISM masses (by definition) and much higher black hole masses, but the
stellar and halo masses are fairly similar. Without active galactic nucleus
(AGN) feedback, massive galaxies are dominated by star formation down to z=0
and most of their stellar mass growth occurs in the centre. With AGN feedback,
stellar mass is only added to the outskirts of galaxies by mergers and they
grow inside-out.


title:
Empirical study of the role of the topology in spreading on
  communication networks

abstract:
  Topological aspects, like community structure, and temporal activity
patterns, like burstiness, have been shown to severly influence the speed of
spreading in temporal networks. We study the influence of the topology on the
susceptible-infected (SI) spreading on time stamped communication networks, as
obtained from a dataset of mobile phone records. We consider city level
networks with intra- and inter-city connections. The networks using only
intra-city links are usually sparse, where the spreading depends mainly on the
average degree. The inter-city links serve as bridges in spreading, speeding up
considerably the process. We demonstrate the effect also on model simulations.


title: Extracting Formal Models from Normative Texts

abstract:
  Normative texts are documents based on the deontic notions of obligation,
permission, and prohibition. Our goal is to model such texts using the C-O
Diagram formalism, making them amenable to formal analysis, in particular
verifying that a text satisfies properties concerning causality of actions and
timing constraints. We present an experimental, semi-automatic aid to bridge
the gap between a normative text and its formal representation. Our approach
uses dependency trees combined with our own rules and heuristics for extracting
the relevant components. The resulting tabular data can then be converted into
a C-O Diagram.


title:
Fast, On-board, Model-aided Visual-Inertial Odometry System for
  Quadrotor Micro Aerial Vehicles

abstract:
  The main contribution of this paper is a high frequency, low-complexity,
on-board visual-inertial odometry system for quadrotor micro air vehicles. The
system consists of an extended Kalman filter (EKF) based state estimation
algorithm that fuses information from a low cost MEMS inertial measurement unit
acquired at 200Hz and VGA resolution images from a monocular camera at 50Hz.
The dynamic model describing the quadrotor motion is employed in the estimation
algorithm as a third source of information. Visual information is incorporated
into the EKF by enforcing the epipolar constraint on features tracked between
image pairs, avoiding the need to explicitly estimate the location of the
tracked environmental features. Combined use of the dynamic model and epipolar
constraints makes it possible to obtain drift free velocity and attitude
estimates in the presence of both accelerometer and gyroscope biases. A
strategy to deal with the unobservability that arises when the quadrotor is in
hover is also provided. Experimental data from a real-time implementation of
the system on a 50 gram embedded computer are presented in addition to the
simulations to demonstrate the efficacy of the proposed system.


title:
Challenges in QCD matter physics - The Compressed Baryonic Matter
  experiment at FAIR

abstract:
  Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.


title:
Simulation Study on the Emittance Compensation of Off-axis Emitted Beam
  in RF Photoinjector

abstract:
  To make full use of photocathode material and improve its quantum efficiency
lifetime, it can be necessary to operate laser away from the cathode center in
photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent
RF effect, which would generate a significant growth in transverse emittance.
It has been demonstrated that such an emittance growth can be almost completely
compensated by orienting the beam on a proper orbit in the downstream RF
cavities along the injector. In this paper we analyze in detail the simulation
techniques used in reference[1] and the issues associated with them. The
optimization of photoinjector systems involving off-axis beams is a challenging
problem. To solve this problem, one needs advanced simulation tools including
both genetic algorithms and an efficient algorithm for 3D space charge. In this
paper, we report on simulation studies where the two codes ASTRA and IMPACT-T
are used jointly to overcome these challenges, in order to optimize a system
designed to compensate for the emittance growth in a beam emitted off axis.


title: Estimating the speed-up of Adaptively Restrained Langevin Dynamics

abstract:
  We consider Adaptively Restrained Langevin dynamics, in which the kinetic
energy function vanishes for small velocities. Properly parameterized, this
dynamics makes it possible to reduce the computational complexity of updating
inter-particle forces, and to accelerate the computation of ergodic averages of
molecular simulations. In this paper, we analyze the influence of the method
parameters on the total achievable speed-up. In particular, we estimate both
the algorithmic speed-up, resulting from incremental force updates, and the
influence of the change of the dynamics on the asymptotic variance. This allows
us to propose a practical strategy for the parametrization of the method. We
validate these theoretical results by representative numerical experiments.


title:
Towards Self-explanatory Ontology Visualization with Contextual
  Verbalization

abstract:
  Ontologies are one of the core foundations of the Semantic Web. To
participate in Semantic Web projects, domain experts need to be able to
understand the ontologies involved. Visual notations can provide an overview of
the ontology and help users to understand the connections among entities.
However, the users first need to learn the visual notation before they can
interpret it correctly. Controlled natural language representation would be
readable right away and might be preferred in case of complex axioms, however,
the structure of the ontology would remain less apparent. We propose to combine
ontology visualizations with contextual ontology verbalizations of selected
ontology (diagram) elements, displaying controlled natural language (CNL)
explanations of OWL axioms corresponding to the selected visual notation
elements. Thus, the domain experts will benefit from both the high-level
overview provided by the graphical notation and the detailed textual
explanations of particular elements in the diagram.


title:
Completeness Properties of the open-point and bi-point-open topologies
  on C(X)

abstract:
  This paper studies various completeness properties of the open-point and
bi-point-open topologies on the space C(X) of all real-valued continuous
functions on a Tychonoff space X. The properties range from complete
metrizability to the Baire space property.


title:
The Effects of Cultural dimensions and Demographic Characteristics on
  E-learning Acceptance

abstract:
  This study aims to develop and test an amalgamated conceptual framework based
on Technology Acceptance Model (TAM) and other models from social psychology,
such as theory of reasoned action and TAM2 that captures the salient factors
influencing the user adoption and acceptance of web-based learning systems.
This framework has been applied to the study of higher educational institutions
in the context of developing as well as developed countries (e.g. Lebanon and
UK). Additionally, the framework investigates the moderating effect of
Hofstedes four cultural dimensions at the individual level and a set of
individual differences (age, gender, experience and educational level) on the
key determinants that affect the behavioral intention to use e-learning. A
total of 1197 questionnaires were received from students who were using
web-based learning systems at higher educational institutions in Lebanon and
the UK with opposite scores on cultural dimensions. Confirmatory Factor
Analysis (CFA) was used to perform reliability and validity checks, and
Structural Equation Modeling (SEM) in conjunction with multi-group analysis
method was used to test the hypothesized conceptual model. Our findings suggest
that individual, social, cultural and organizational factors are important to
consider in explaining students behavioral intention and usage of e-learning
environments. The findings of this research contribute to the literature by
validating and supporting the applicability of our extended TAM in the Lebanese
and British contexts and provide several prominent implications to both theory
and practice on the individual, organizational and societal levels.


title: Torsion in the 0-cycle group with modulus

abstract:
  We show, for a smooth projective variety $X$ over an algebraically closed
field $k$ with an effective Cartier divisor $D$, that the torsion subgroup
$\CH_0(X|D)\{l\}$ can be described in terms of a relative {\'e}tale cohomology
for any prime $l \neq p = {\rm char}(k)$. This extends a classical result of
Bloch, on the torsion in the ordinary Chow group, to the modulus setting. We
prove the Roitman torsion theorem (including $p$-torsion) for $\CH_0(X|D)$ when
$D$ is reduced. We deduce applications to the problem of invariance of the
prime-to-$p$ torsion in $\CH_0(X|D)$ under an infinitesimal extension of $D$.


title:
Fluid-like Surface Layer and Its Flow Characteristics in Glassy
  Nanotubes

abstract:
  We observed strongly size-dependent viscoelasticity in amorphous SiO2 and Si
nanotubes with shell thickness down to ~8 nm. A core-shell model shows that a
~1 nm thick fluid-like surface layer has a significant effect on the mechanical
behavior of nanotubes and matches well with our experimental results.
Surprising, the surface layer exhibits a room temperature viscosity equivalent
to that of bulk glass above 1000 C. Additionally, a low activation energy
extracted from temperature dependent creep tests indicates that the viscous
flow in the surface layer is due to bond motion/switching, instead of bond
breaking. These findings unambiguously show the presence of a fluid-like
surface layer and elucidate its role on dynamic mechanical behavior in
nanoscale inorganic glass.


title:
Multilayer coating for higher accelerating fields in superconducting
  radio-frequency cavities: a review of theoretical aspects

abstract:
  Theory of the superconductor-insulator-superconductor (S-I-S) multilayer
structure in superconducting accelerating cavity application is reviewed. The
theoretical field limit, optimum layer thicknesses and material combination,
and surface resistance are discussed. Those for the S-S bilayer structure are
also reviewed.


title: Discriminants of multilinear systems

abstract:
  We study well-constrained bilinear algebraic systems in order to formulate
their discriminant. We derive a new determinantal formula for the discriminant
of a multilinear system that appears in the study of Nash equilibria of
multiplayer games with mixed strategies.


title:
On Some Expansion Theorems Involving Confluent Hypergeometric
  $_{2}F_{2}(x)$ Polynomial

abstract:
  Recently, Rathie and K{\i}l{\i}\c{c}man (2014) employed Kummer-type
transformation for $_{2}F_{2}(a, d+1; b, d; x)$ to develop certain classes of
expansions theorems for $_{2}F_{2}(x)$ hypergeometric polynomial. Our aim is to
deduce Kummer-type transformation for $_{2}F_{2}(a, d+2; b, d; x)$ and utilize
it to develop some new expansion theorems for the confluent hypergeometric
$_{2}F_{2}(x)$ polynomial. We also obtain a well-known result given by Kim et
al. (Integral Transforms Spec. Funct. 23(6); 435-444, 2012) and many other new
results as particular cases of our theorems.


title:
$\alpha'$-expansion of Anti-Symmetric Wilson Loops in $\mathcal{N}=4$
  SYM from Fermi Gas

abstract:
  We study the large 't Hooft coupling expansion of 1/2 BPS Wilson loops in the
anti-symmetric representation in $ \mathcal{N}=4 $ super Yang-Mills (SYM)
theory at the leading order in the 1/N expansion. Via AdS/CFT correspondence,
this expansion corresponds to the $\alpha'$ expansion in bulk type IIB string
theory. We show that this expansion can be systematically computed by using the
low temperature expansion of Fermi distribution function, known as the
Sommerfeld expansion in statistical mechanics. We check numerically that our
expansion agrees with the exact result of anti-symmetric Wilson loops recently
found by Fiol and Torrents.


title:
Current density and conductivity through modified gravity in the
  graphene with defects

abstract:
  We propose a model describing the evolution of the free electron current
density in graphene.
  Based on the concept of Mp-branes, we perform the analysis using the
difference between curvatures of parallel and antiparallel spins. In such a
framework an effective graviton emerges in the form of gauge field exchange
between electrons. In a plain graphene system, the curvatures produced by both
kinds of spins neutralize each other. However, in the presence of defects, the
inequality between curvatures leads to the emergence of current density,
modified gravity and conductivity. Depending on the type of the defects, the
resulting current density can be negative or positive.


title:
General proof for irrationality of infinite sums based on Fourier's
  proof

abstract:
  In this paper we review a general proof for the irrationality property of
numbers which take a certain form of infinite sums.


title: On Functionally Commutative Quantum Systems

abstract:
  In this paper, a method to solve functionally commutative time- dependent
linear homogeneous differential equation is discussed. We apply this technique
to solve some dynamical quantum problems.


title: Solubility and partitioning of impurities in Be alloys

abstract:
  The most energetically favourable accommodation processes for common
impurities and alloying elements in Be metal and Be-Fe-Al intermetallics were
investigated using atomic scale simulations. Fe additions, combined with
suitable heat treatments, may scavange Al and Si through their incorporation
into the FeBe5 intermetallic. In the absence of Fe, Al and Si will not be
associated with Be metal. Li and Mg are also not soluble, but may react with
other impurities if present (such as Al or H). Mg may also form the MgBe13
intermetallic phase under certain conditions. He and H exhibit negligible
solubility in all phases investigated and whilst He will tend to form bubbles,
H can precipitate as BeH2. Similarly, C additions will form the stable compound
Be2C. Finally, oxygen exhibits a strong affinity to Be, exhibiting both some
degree of solubility in all phases considered here (though especially metallic
Be) and a highly favourable energy of formation for BeO.


title:
Synchrotron and Smith-Purcell radiations from a charge rotating around a
  cylindrical grating

abstract:
  We investigate the radiation from a charge rotating around conductors with
cylindrical symmetry. First the problem is considered with a charge rotating
around a conducting cylinder immersed in a homogeneous medium. The surface
charge and current densities induced on the cylinder surface are evaluated. A
formula is derived for the spectral-angular density of the radiation intensity.
In the second part, we study the radiation for a charge rotating around a
diffraction grating on a cylindrical surface with metallic strips parallel to
the cylinder axis. The effect of the grating on the radiation intensity is
approximated by the surface currents induced on the strips by the field of the
rotating charge. The expressions are derived for the electric and magnetic
fields and for the angular density of the radiation intensity on a given
harmonic. We show that the interference between the synchrotron and
Smith-Purcell radiations may lead to interesting features. In particular, the
behavior of the radiation intensity on large harmonics can be essentially
different from that for a charge rotating in the vacuum or around a solid
cylinder. Unlike to these limiting cases, for the geometry of diffraction
grating the radiation intensity on higher harmonics does not vanish for small
angles with respect to the cylinder axis. For given characteristics of the
charge, by the choice of the parameters of the diffraction grating, one can
have highly directional radiation near the normal to the plane of the charge
rotation. With decreasing energy, the relative contribution of the synchrotron
radiation decreases and the Smith-Purcell part is dominant.


title: Axial form factor of the nucleon at large momentum transfers

abstract:
  Motivated by the emerging possibilities to study threshold pion
electroproduction at large momentum transfers at Jefferson Laboratory following
the 12 GeV upgrade, we provide a short theory summary and an estimate of the
nucleon axial form factor for large virtualities in the $Q^2 =
1-10~\text{GeV}^2$ range using next-to-leading order light-cone sum rules.


title:
Strong maximum principles for fractional elliptic and parabolic problems
  with mixed boundary conditions

abstract:
  We present some comparison results for solutions to certain non local
elliptic and parabolic problems that involve the fractional Laplacian operator
and mixed boundary conditions, given by a zero Dirichlet datum on part of the
complementary of the domain and zero Neumann data on the rest. These results
represent a non local generalization of a Hopf's lemma for elliptic and
parabolic problems with mixed conditions. In particular we prove the non local
version of the results obtained by J. D\'avila and J. D\'avila-L. Dupaigne for
the classical case respectively.


title:
Temperature dependence of the magnon spin diffusion length and magnon
  spin conductivity in the magnetic insulator yttrium iron garnet

abstract:
  We present a systematic study of the temperature dependence of diffusive
magnon spin transport, using a non-local device geometry. In our measurements,
we detect spin signals arising from electrical and thermal magnon generation,
and we directly extract the magnon spin diffusion length $\lambda_m$ for
temperatures from 2 to 293 K. Values of $\lambda_m$ obtained from electrical
and thermal generation agree within the experimental error, with
$\lambda_m=9.6\pm0.9$ $\mu$m at room temperature to a minimum of
$\lambda_m=5.5\pm0.7$ $\mu$m at 30 K. Using a 2D finite element model to fit
the data obtained for electrical magnon generation we extract the magnon spin
conductivity $\sigma_m$ as a function of temperature, which is reduced from
$\sigma_m=5.1\pm0.2\times10^5$ S/m at room temperature to
$\sigma_m=0.7\pm0.4\times10^5$ S/m at 5 K. Finally, we observe an enhancement
of the signal originating from thermally generated magnons for low
temperatures, where a maximum is observed around $T=7$ K. An explanation for
this low temperature enhancement is however still missing and requires
additional investigations.


title:
Transverse momentum dependent splitting functions at work:
  quark-to-gluon splitting

abstract:
  Using the recently obtained Pgq splitting function we extend the low x
evolution equation for gluons to account for contributions originating from
quark-to-gluon splitting. In order to write down a consistent equation we resum
virtual corrections coming from the gluon channel and demonstrate that this
implies a suitable regularization of the Pgq singularity, corresponding to a
soft emitted quark. We also note that the obtained equation is in a
straightforward manner generalized to a nonlinear evolution equation which
takes into account effects due to the presence of high gluon densities.


title:
Improving Newton's method performance by parametrization: the case of
  Richards equation

abstract:
  The nonlinear systems obtained by discretizing degenerate parabolic equations
may be hard to solve, especially with Newton's method. In this paper, we apply
to Richards equation a strategy that consists in defining a new primary unknown
for the continuous equation in order to stabilize Newton's method by
parametrizing the graph linking the pressure and the saturation. The resulting
form of Richards equation is then discretized thanks to a monotone Finite
Volume scheme. We prove the well-posedness of the numerical scheme. Then we
show under appropriate non-degeneracy conditions on the parametrization that
Newton\^as method converges locally and quadratically. Finally, we provide
numerical evidences of the efficiency of our approach.


title: Effective Field Theory for Few-Boson Systems

abstract:
  We study universal bosonic few-body systems within the framework of effective
field theory at leading order (LO). We calculate binding energies of systems of
up to six particles and the atom-dimer scattering length. Convergence to the
limit of zero-range two- and three-body interactions is shown, indicating that
no additional few-body interactions need to be introduced at LO.
Generalizations of the Tjon line are constructed, showing correlations between
few-body binding energies and the binding energy of the trimer, for a given
dimer energy. As a specific example, we implement our theory for 4He atomic
systems, and show that the results are in surprisingly good agreement with
those of sophisticated 4He-4He potentials. Potential implications for the
convergence of the EFT expansion are discussed.


title: Perturbation Theory for Arbitrary Coupling Strength ?

abstract:
  We present a \emph{new} formulation of perturbation theory for quantum
systems, designated here as: `mean field perturbation theory'(MFPT), which is
free from power-series-expansion in any physical parameter, including the
coupling strength. Its application is thereby extended to deal with
interactions of \textit{arbitrary} strength and to compute system-properties
having non-analytic dependence on the coupling, thus overcoming the primary
limitations of the `standard formulation of perturbation theory' ( SFPT). MFPT
is defined by developing perturbation about a chosen input Hamiltonian, which
is exactly solvable but which acquires the non-linearity and the analytic
structure~(in the coupling-strength)~of the original interaction through a
self-consistent, feedback mechanism. We demonstrate Borel-summability of MFPT
for the case of the quartic- and sextic-anharmonic oscillators and the quartic
double-well oscillator (QDWO) by obtaining uniformly accurate results for the
ground state of the above systems for arbitrary physical values of the coupling
strength. The results obtained for the QDWO may be of particular significance
since `renormalon'-free, unambiguous results are achieved for its spectrum in
contrast to the well-known failure of SFPT in this case.
  \pacs{11.15.Bt,11.10.Jj,11.25.Db,12.38.Cy,03.65.Ge}


title:
Femtosecond X-Ray Scattering Study of Ultrafast Photoinduced Structural
  Dynamics in Solvated [Co(terpy)2]2+

abstract:
  We study the structural dynamics of photoexcited [Co(terpy)2]2+ in an aqueous
solution with ultrafast x-ray diffuse scattering experiments conducted at the
Linac Coherent Light Source. Through direct comparisons with density functional
theory calculations, our analysis shows that the photoexcitation event leads to
elongation of the Co-N bonds, followed by coherent Co-N bond length
oscillations arising from the impulsive excitation of a vibrational mode
dominated by the symmetrical stretch of all six Co-N bonds. This mode has a
period of 0.33 ps and decays on a subpicosecond time scale. We find that the
equilibrium bond-elongated structure of the high spin state is established on a
single-picosecond time scale and that this state has a lifetime of ~ 7 ps.


title:
Holographically emulating sequential versus instantaneous disappearance
  of vector mesons in a hot environment

abstract:
  Descent extensions of the soft-wall model are used to accommodate two
variants of Regge trajectories of vector meson excitations. At non-zero
temperatures, various options for either sequential or instantaneous
disappearance of vector mesons as normalisable modes are found, thus emulating
deconfinement at a certain temperature in the order of the (pseudo-) critical
temperature of QCD. The crucial role of the blackness function, which steers
the thermodynamic properties of the considered system, is highlighted.


title: Charge redistribution from anomalous magnetovorticity coupling

abstract:
  We investigate novel transport phenomena in a chiral fluid originated from an
interplay between a vorticity and strong magnetic field, which induces a
redistribution of vector charges in the system and an axial current along the
magnetic field. The corresponding transport coefficients are obtained from an
energy-shift argument for the chiral fermions in the lowest Landau level (LLL)
due to a spin-vorticity coupling and also from diagrammatic computations on the
basis of the linear response theory. Based on consistent results from the both
methods, we observe that the transport coefficients are proportional to the
anomaly coefficient and are independent of temperature and chemical potential.
We therefore speculate that these transport phenomena are connected to quantum
anomaly.


title: Phase-flip chimera induced by environmental nonlocal coupling

abstract:
  We report the emergence of a collective dynamical state, namely phase-flip
chimera, from an en- semble of identical nonlinear oscillators that are coupled
indirectly via the dynamical variables from a common environment, which in turn
are nonlocally coupled. The phase-flip chimera is character- ized by the
coexistence of two adjacent out-of-phase synchronized coherent domains
interspersed by an incoherent domain, in which the nearby oscillators are in
out-of-phase synchronized states. At- tractors of the coherent domains are
either from the same or different basins of attractions depending on whether
they are periodic or chaotic. Conventional chimera precedes the phase-flip
chimera in general. Further, the phase-flip chimera emerges after the
completely synchronized evolution of the ensemble in contrast to conventional
chimeras which emerge as an intermediate state between completely incoherent
and coherent states. We have also characterized the observed dynamical
transitions using the strength of incoherence, probability distribution of
correlation coefficient and the framework of master stability function.


title: On a cosine function defined for smooth normed spaces

abstract:
  We do further investigation in a certain cosine function defined for smooth
Minkowski spaces. We prove that such function is symmetric if and only if the
referred space is Euclidean, and also that it can be given in terms of the
Gateaux derivative of the norm. As an application we use it to study the ratio
between the lengths of tangent segments drawn through an external point to the
unit circle of a Radon plane. We also give an easy characterization of such
planes in terms of signs of the cosine function.