title:
An Introduction to the Massive Helicity Formalism with applications to
  the Electroweak SM

abstract:
  The power of the helicity formalism has been appreciated recently from its
application to the massless case, where plenty of formal aspects of multi-legs
amplitudes have been derived. However, in order to extend the formalism to the
realistic cases, such as the electroweak Standard Model and QCD with massive
quarks, some extra inputs are needed. We discuss first the formalism needed to
evaluate amplitudes expressed with the modern notation for massive fermions and
vectors based on a thorough treatment of Proca vector fields. Then, we present
some examples of elementary processes where it is shown how the formalism leads
to tremendous simplifications, these include 2-body decays $Z\to ff$, $h\to ff$
and $h\to W^{-}W^{+}$ as well as the 3-body decay $h\to V f'\bar{f}$.


title:
Quantifying the eddy-jet feedback strength of the annular mode in an
  idealized GCM and reanalysis data

abstract:
  A linear response function (LRF) that relates the temporal tendency of zonal
mean temperature and zonal wind to their anomalies and external forcing is used
to accurately quantify the strength of the eddy-jet feedback associated with
the annular mode in an idealized GCM. Following a simple feedback model, the
results confirm the presence of a positive eddy-jet feedback in the annular
mode dynamics, with a feedback strength of 0.137 day$^{-1}$ in the idealized
GCM. Statistical methods proposed by earlier studies to quantify the feedback
strength are evaluated against results from the LRF. It is argued that the
mean-state-independent eddy forcing reduces the accuracy of these statistical
methods because of the quasi-oscillatory nature of the eddy forcing. A new
method is proposed to approximate the feedback strength as the regression
coefficient of low-pass filtered eddy forcing onto low-pass filtered annular
mode index, which converges to the value produced by the LRF when timescales
longer than 200 days are used for the low-pass filtering. Applying the new
low-pass filtering method to the reanalysis data, the feedback strength in the
Southern annular mode is found to be 0.121 day$^{-1}$, which is presented as an
improvement over previous estimates. This work also highlights the importance
of using sub-daily data in the analysis by showing the significant contribution
of medium-scale waves of periods less than 2 days to the annular mode dynamics,
which was under-appreciated in most of previous research. The present study
provides a framework to quantify the eddy-jet feedback strength in models and
reanalysis data.


title: Null Sectional Curvatures of Warped Products

abstract:
  In this paper, we investigate the null (light-like) sectional curvatures of
Lorentzian warped product manifolds. We derive the formulas for the null
sectional curvature of many well-known warped product space-time models such as
multiply generalized Robertson-Walker space-times, generalized Kasner
spacetimes and standard static space-times.


title:
Instantaneous Reaction-Time in Dynamic-Consistency Checking of
  Conditional Simple Temporal Networks -- Extended version with an Improved
  Upper Bound --

abstract:
  CSTNs is a constraint-based graph-formalism for conditional temporal
planning. In order to address the DC-Checking problem, in [Comin and Rizzi,
TIME 2015] we introduced epsilon-DC (a refined, more realistic, notion of DC),
and provided an algorithmic solution to it. The epsilon-DC notion is
interesting per se, and the epsilon-DC-Checking algorithm in [Comin and Rizzi,
TIME 2015] rests on the assumption that the reaction-time satisfies epsilon >
0; leaving unsolved the question of what happens when epsilon = 0. In this
work, we introduce and study pi-DC, a sound notion of DC with an instantaneous
reaction-time (i.e. one in which the planner can react to any observation at
the same instant of time in which the observation is made). Firstly, we
demonstrate by a counter-example that pi-DC is not equivalent to 0-DC, and that
0-DC is actually inadequate for modeling DC with an instantaneous
reaction-time. This shows that the main results obtained in our previous work
do not apply directly, as they were formulated, to the case of epsilon=0.
Motivated by this observation, as a second contribution, our previous tools are
extended in order to handle pi-DC, and the notion of ps-tree is introduced,
also pointing out a relationship between pi-DC and HyTN-Consistency. Thirdly, a
simple reduction from pi-DC-Checking to DC-Checking is identified. This allows
us to design and to analyze the first sound-and-complete pi-DC-Checking
procedure. Remarkably, the time complexity of the proposed algorithm remains
(pseudo) singly-exponential in the number of propositional letters. Finally, it
is observed that the technique can be leveraged to actually reduce from pi-DC
to 1-DC, this allows us to further improve the exponents in the time complexity
of pi-DC-Checking.


title:
The Structure and Dynamical Evolution of the Stellar Disk of a Simulated
  Milky Way-Mass Galaxy

abstract:
  We study the structure, age and metallicity gradients, and dynamical
evolution using a cosmological zoom-in simulation of a Milky Way-mass galaxy
from the Feedback in Realistic Environments project. In the simulation, stars
older than 6 Gyr were formed in a chaotic, bursty mode and have the largest
vertical scale heights (1.5-2.5 kpc) by z=0, while stars younger than 6 Gyr
were formed in a relatively calm, stable disk. The vertical scale height
increases with stellar age at all radii, because (1) stars that formed earlier
were thicker "at birth", and (2) stars were kinematically heated to an even
thicker distribution after formation. Stars of the same age are thicker in the
outer disk than in the inner disk (flaring). These lead to positive vertical
age gradients and negative radial age gradients. The radial metallicity
gradient is neg- ative at the mid-plane, flattens at larger disk height |Z|,
and turns positive above |Z|~1.5kpc. The vertical metallicity gradient is
negative at all radii, but is steeper at smaller radii. These trends broadly
agree with observations in the Milky Way and can be naturally understood from
the age gradients. The vertical stellar density profile can be well-described
by two components, with scale heights 200-500 pc and 1-1.5 kpc, respectively.
The thick component is a mix of stars older than 4 Gyr which formed through a
combination of several mechanisms. Our results also demonstrate that it is
possible to form a thin disk in cosmological simulations even with strong
stellar feedback.


title:
Quantum State Absorptions Coupled To Resonance Raman Spectroscopy Could
  Result In A General Explanation of TERS

abstract:
  Tip enhanced Raman scattering (TERS) amplifies the intensity of vibrational
Raman scattering by employing the tip of a probe interacting, in ultra close
proximity, with a surface. Although a general understanding of the TERS process
is still to be fully elucidated, scanning tunneling microscopy (STM) feedback
is often applied with success in TERS to keep a noble metal probe in intimate
proximity with a noble metal substrate. Since such STM TERS is a common
modality, the possible implications of plasmonic fields that may be induced by
the tunneling process are investigated and reported. In addition, TERS of a 2D
resonant molecular system, a MoS2 bilayer crystal and a 2D non-resonant, lipid
molecular bilayer is compared. Data with multiple excitation wavelengths and
surfaces for the resonant system in the near- (TERS) and far-field regimes are
reported. An interpretation based on weak coupling interactions within the
framework of conventional resonance Raman scattering can explain the observed
TERS enhancements. The non-resonant molecular lipid system, on the other hand,
requires strong coupling for a full understanding of the reported observations.


title:
Simultaneous Input and State Estimation for Linear Time-Varying
  Continuous-Time Stochastic Systems

abstract:
  In this paper, we present an optimal filter for linear time-varying
continuous-time stochastic systems that simultaneously estimates the states and
unknown inputs in an unbiased minimum-variance sense. We first show that the
unknown inputs cannot be estimated without additional assumptions. Then, we
discuss two complementary variants of the filter: (i) for the case when an
additional measurement containing information about the state derivative is
available, and (ii) for the case without the additional measurement but the
input signals are assumed to be sufficiently smooth and have bounded
derivatives. Conditions for uniform asymptotic stability and the existence of a
steady-state solution for the proposed filter, as well as the convergence rate
of the state and input estimate biases are given. Moreover, we show that a
principle of separation of estimation and control holds and that the unknown
inputs may be rejected. Two examples, including a nonlinear vehicle reentry
example, are given to illustrate that our filter is applicable even when some
strong assumptions do not hold.


title:
Magnetoresistance and surface roughness study of the initial growth of
  electrodeposited Co/Cu multilayers

abstract:
  The giant magnetoresistance (GMR) effect has been widely investigated on
electrodeposited ferromagnetic/non-magnetic (FM/NM) multilayers generally
containing a large number of bilayers. In most applications of the GMR effect,
layered structures consisting of a relatively small number of consecutive FM
and NM layers are used. It is of great interest, therefore, to investigate the
initial stages of GMR multilayer film growth by electrodeposition. In the
present work we have extended our previous studies on ED GMR multilayers to
layered structures with a total thickness ranging from a few nanometers up to
70 nm. The evolution of the surface roughness and electrical transport
properties of such ultrathin ED Co/Cu layered structures was investigated.
Various layer combinations were produced including both Co and Cu either as
starting or top layers in order (i) to see differences in the nucleation of the
first layer and (ii) to trace out the effect of the so called exchange
reaction. Special attention was paid to measure the field dependence of the
magnetoresistance, MR(H) in order to derive information for the appearance of
superparamagnetic regions in the magnetic layers. This proved to be helpful for
monitoring the evolution of the layer microstructure at each step of the
deposition sequence.


title:
A second order dynamical system with Hessian-driven damping and penalty
  term associated to variational inequalities

abstract:
  We consider the minimization of a convex objective function subject to the
set of minima of another convex function, under the assumption that both
functions are twice continuously differentiable. We approach this optimization
problem from a continuous perspective by means of a second order dynamical
system with Hessian-driven damping and a penalty term corresponding to the
constrained function. By constructing appropriate energy functionals, we prove
weak convergence of the trajectories generated by this differential equation to
a minimizer of the optimization problem as well as convergence for the
objective function values along the trajectories. The performed investigations
rely on Lyapunov analysis in combination with the continuous version of the
Opial Lemma. In case the objective function is strongly convex, we can even
show strong convergence of the trajectories.


title: Sub-Nyquist SAR via Fourier Domain Range Doppler Processing

abstract:
  Conventional Synthetic Aperture Radar (SAR) systems are limited in their
ability to satisfy the increasing requirement for improved spatial resolution
and wider coverage. The demand for high resolution requires high sampling
rates, while coverage is limited by the pulse repetition frequency.
Consequently, sampling rate reduction is of high practical value in SAR
imaging. In this paper, we introduce a new algorithm, equivalent to the
well-known Range-Doppler method, to process SAR data using the Fourier series
coefficients of the raw signals. We then demonstrate how to exploit the
algorithm features to reduce sampling rate in both range and azimuth axes and
process the signals at sub-Nyquist rates, by using compressed sensing (CS)
tools. In particular, we demonstrate recovery of an image using only a portion
of the received signal's bandwidth and also while dropping a large percentage
of the transmitted pulses. The complementary pulses may be used to capture
other scenes within the same coherent processing interval. In addition, we
propose exploiting the ability to reconstruct the image from narrow bands in
order to dynamically adapt the transmitted waveform energy to vacant spectral
bands, paving the way to cognitive SAR. The proposed recovery algorithms form a
new CS-SAR imaging method that can be applied to high-resolution SAR data
acquired at sub-Nyquist rates in range and azimuth. The performance of our
method is assessed using simulated and real data sets. Finally, our approach is
implemented in hardware using a previously suggested Xampling radar prototype.


title:
Unconventional superconductivity in bilayer transition metal
  dichalcogenides

abstract:
  Bilayer transition metal dichalcogenides (TMDs) belong to a class of
materials with two unique features, the coupled spin-valley-layer degrees of
freedom and the crystal structure that is globally centrosymmetric but locally
non-centrosymmetric. In this work, we will show that the combination of these
two features can lead to a rich phase diagram for unconventional
superconductivity, including intra-layer and inter-layer singlet pairings and
inter-layer triplet pairings, in bilayer superconducting TMDs. In particular,
we predict that the inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov state can
exist in bilayer TMDs under an in-plane magnetic field. We also discuss the
experimental relevance of our results and possible experimental signatures.


title: Nonlocality of three-qubit Greenberger-Horne-Zeilinger-symmetric states

abstract:
  Mixed states appear naturally in experiment over pure states. So for studying
different notions of nonlocality and their relation with entanglement in
realistic scenarios, one needs to consider mixed states. In a recent article
[Phys. Rev. Lett. \textbf{108}, 020502 (2012)], a complete characterization of
entanglement of an entire class of mixed three qubit states with the same
symmetry as Greenberger-Horne-Zeilinger state known as GHZ-symmetric states,
has been achieved. In this paper we investigate different notions of
nonlocality of the same class of states. By finding the analytical expressions
of maximum violation value of most efficient Bell inequalities we obtain the
conditions of standard nonlocality and genuine nonlocality of this class of
states. Also relation between entanglement and nonlocality is discussed for
this class of states. Interestingly, genuine entanglement of GHZ-symmetric
states is necessary to reveal standard nonlocality. However, it is not
sufficient to exploit the same.


title: Low Rank Phase Retrieval

abstract:
  We develop two iterative algorithms for solving the low rank phase retrieval
(LRPR) problem. LRPR refers to recovering a low-rank matrix $\X$ from
magnitude-only (phaseless) measurements of random linear projections of its
columns. Both methods consist of a spectral initialization step followed by an
iterative algorithm to maximize the observed data likelihood. We obtain sample
complexity bounds for our proposed initialization approach to provide a good
approximation of the true $\X$. When the rank is low enough, these bounds are
significantly lower than what existing single vector phase retrieval algorithms
need. Via extensive experiments, we show that the same is also true for the
proposed complete algorithms.


title: Contexts and Data Quality Assessment

abstract:
  The quality of data is context dependent. Starting from this intuition and
experience, we propose and develop a conceptual framework that captures in
formal terms the notion of "context-dependent data quality". We start by
proposing a generic and abstract notion of context, and also of its uses, in
general and in data management in particular. On this basis, we investigate
"data quality assessment" and "quality query answering" as context-dependent
activities. A context for the assessment of a database D at hand is modeled as
an external database schema, with possibly materialized or virtual data, and
connections to external data sources. The database D is put in context via
mappings to the contextual schema, which produces a collection C of alternative
clean versions of D. The quality of D is measured in terms of its distance to
C. The class C} is also used to define and do "quality query answering". The
proposed model allows for natural extensions, like the use of data quality
predicates, the optimization of the access by the context to external data
sources, and also the representation of contexts by means of more expressive
ontologies.


title: Dynamic Market Mechanisms for Wind Energy

abstract:
  We investigate the problem of market mechanism design for wind energy. We
consider a dynamic two-step model with one strategic seller with wind
generation and one buyer, who trade energy through a mechanism determined by a
designer. The seller has private information about his technology and wind
condition, which he learns dynamically over time. We consider (static) forward
and real-time mechanisms that take place at time T=1 and T=2, respectively. We
also propose a dynamic mechanism that provides a coupling between the outcomes
of the forward and real-time markets. We show that the dynamic mechanism
outperforms the forward and real-time mechanisms for a general objective of the
designer. Therefore, we demonstrate the advantage of adopting dynamic market
mechanisms over static market mechanisms for wind energy. The dynamic mechanism
reveals information about wind generation in advance, and also provides
flexibility for incorporation of new information arriving over time. We discuss
how our results generalize to environments with many strategic sellers. We also
study two variants of the dynamic mechanism that guarantee no penalty risk for
the seller, and/or monitor the wind condition. We illustrate our results with a
numerical example.


title:
A multiscale framework for the simulation of the anisotropic mechanical
  behavior of shale

abstract:
  Shale, like many other sedimentary rocks, is typically heterogeneous,
anisotropic, and is characterized by partial alignment of anisotropic clay
minerals and naturally formed bedding planes. In this study, a micromechanical
framework based on the Lattice Discrete Particle Model (LDPM) is formulated to
capture these features. Material anisotropy is introduced through an
approximated geometric description of shale internal structure, which includes
representation of material property variation with orientation and explicit
modeling of parallel lamination. The model is calibrated by carrying out
numerical simulations to match various experimental data, including the ones
relevant to elastic properties, Brazilian tensile strength, and unconfined
compressive strength. Furthermore, parametric study is performed to investigate
the relationship between the mesoscale parameters and the macroscopic
properties. It is shown that the dependence of the elastic stiffness, strength,
and failure mode on loading orientation can be captured successfully. Finally,
a homogenization approach based on the asymptotic expansion of field variables
is applied to upscale the proposed micromechanical model, and the properties of
the homogenized model are analyzed.


title:
Decoherent Histories Quantum Mechanics Starting with Records of What
  Happens

abstract:
  We present a formulation of the decoherent (or consistent) histories quantum
theory of closed systems starting with records of what histories happen.
Alternative routes to a formulation of quantum theory like this one can be
useful both for understanding quantum mechanics and for generalizing and
extending it to new realms of application and experimental test.


title:
Avoiding algebraic integers of bounded house in orbits of rational
  functions over cyclotomic closures

abstract:
  Let $k$ be a number field with cyclotomic closure $k^{\mathrm{cyc}}$, and let
$h \in k^{\mathrm{cyc}}(x)$. For $A \ge 1$ a real number, we show that \[ \{
\alpha \in k^{\mathrm{cyc}} : h(\alpha) \in \overline{\mathbb Z} \text{ has
house at most } A \} \] is finite for many $h$. We also show that for many such
$h$ the same result holds if $h(\alpha)$ is replaced by orbits $h(h(\cdots
h(\alpha)))$. This generalizes a result proved by Ostafe that concerns avoiding
roots of unity, which is the case $A=1$.


title: Numerically Grounded Language Models for Semantic Error Correction

abstract:
  Semantic error detection and correction is an important task for applications
such as fact checking, speech-to-text or grammatical error correction. Current
approaches generally focus on relatively shallow semantics and do not account
for numeric quantities. Our approach uses language models grounded in numbers
within the text. Such groundings are easily achieved for recurrent neural
language model architectures, which can be further conditioned on incomplete
background knowledge bases. Our evaluation on clinical reports shows that
numerical grounding improves perplexity by 33% and F1 for semantic error
correction by 5 points when compared to ungrounded approaches. Conditioning on
a knowledge base yields further improvements.


title:
Explicit calculation of multi-fold contour integrals of certain ratios
  of Euler gamma functions. Part 1

abstract:
  In this paper we proceed to study properties of Mellin-Barnes (MB) transforms
of Usyukina-Davydychev (UD) functions. In our previous papers [Nuclear Physics
B 870 (2013) 243], [Nuclear Physics B 876 (2013) 322] we showed that multi-fold
Mellin-Barnes (MB) transforms of Usyukina-Davydychev (UD) functions may be
reduced to two-fold MB transforms and that the higher-order UD functions were
obtained in terms of a differential operator by applying it to a slightly
modified first UD function. The result is valid in $d=4$ dimensions and its
analog in $d=4-2\varepsilon$ dimensions exits too [Theoretical and Mathematical
Physics 177 (2013) 1515]. In [Nuclear Physics B 870 (2013) 243] the chain of
recurrent relations for analytically regularized UD functions was obtained
implicitly by comparing the left hand side and the right hand side of the
diagrammatic relations between the diagrams with different loop orders. In
turn, these diagrammatic relations were obtained due to the method of loop
reduction for the triangle ladder diagrams proposed in 1983 by Belokurov and
Usyukina. Here we reproduce these recurrent relations by calculating explicitly
via Barnes lemmas the contour integrals produced by the left hand sides of the
diagrammatic relations. In such a way we explicitly calculate a family of
multi-fold contour integrals of certain ratios of Euler gamma functions. We
make a conjecture that similar results for the contour integrals are valid for
a wider family of smooth functions which includes the MB transforms of UD
functions.


title:
Reply to Gillis's "On the Analysis of Bell's 1964 Paper by Wiseman,
  Cavalcanti, and Rieffel"

abstract:
  We address Gillis' recent criticism [arXiv:1506.05795] of a series of papers
(by different combinations of the present authors) on formulations of Bell's
theorem. Those papers intended to address an unfortunate gap of communication
between two broad camps in the quantum foundations community that we identify
as "operationalists" and "realists". Here, we once again urge the readers to
approach the question from an unbiased standpoint, and explain that Gillis'
criticism draws too heavily on the philosophical inclinations of one side of
that debate -- the realist camp. As part of that explanation we discuss
intuition versus proof, look again at Bell's formalizations of locality, and
correct misstatements by Gillis of our views, and those of Bell and Einstein.


title: Galactoseismology in the GAIA Era

abstract:
  The GAIA satellite will provide unprecedented phase-space information for our
Galaxy and enable a new era of Galactic dynamics. We may soon see successful
realizations of Galactoseismology, i.e., inferring the characteristics of the
Galactic potential and sub-structure from a dynamical analysis of observed
perturbations in the gas or stellar disk of the Milky Way. Here, we argue that
to maximally take advantage of the GAIA data and other complementary surveys,
it is necessary to build comprehensive models for both the stars and the gas.
We outline several key morphological puzzles of the Galactic disk and proposed
solutions that may soon be tested.


title:
The Congruence Subgroup Problem for low rank Free and Free Metabelian
  groups

abstract:
  The congruence subgroup problem for a finitely generated group $\Gamma$ asks
whether $\widehat{Aut\left(\Gamma\right)}\to Aut(\hat{\Gamma})$ is injective,
or more generally, what is its kernel $C\left(\Gamma\right)$? Here $\hat{X}$
denotes the profinite completion of $X$. In this paper we first give two new
short proofs of two known results (for $\Gamma=F_{2}$ and $\Phi_{2}$) and a new
result for $\Gamma=\Phi_{3}$:
  1. $C\left(F_{2}\right)=\left\{ e\right\}$ when $F_{2}$ is the free group on
two generators.
  2. $C\left(\Phi_{2}\right)=\hat{F}_{\omega}$ when $\Phi_{n}$ is the free
metabelian group on $n$ generators, and $\hat{F}_{\omega}$ is the free
profinite group on $\aleph_{0}$ generators.
  3. $C\left(\Phi_{3}\right)$ contains $\hat{F}_{\omega}$.
  Results 2. and 3. should be contrasted with an upcoming result of the first
author showing that $C\left(\Phi_{n}\right)$ is abelian for $n\geq4$.


title:
Computation of the incomplete gamma function for negative values of the
  argument

abstract:
  An algorithm for computing the incomplete gamma function $\gamma^*(a,z)$ for
real values of the parameter $a$ and negative real values of the argument $z$
is presented. The algorithm combines the use of series expansions,
Poincar\'e-type expansions, uniform asymptotic expansions and recurrence
relations, depending on the parameter region. A relative accuracy $\sim
10^{-13}$ in the parameter region $(a,z) \in [-500,\,500] \times [-500,\,0)$
can be obtained when computing the function $\gamma^*(a,z)$ with the Fortran 90
module IncgamNEG implementing the algorithm.


title: 1-color-avoiding paths, special tournaments, and incidence geometry

abstract:
  We discuss two approaches to a recent question of Loh: must a 3-colored
transitive tournament on $N$ vertices have a 1-color-\emph{avoiding} path of
vertex-length at least $N^{2/3}$? This question generalizes the
Erd\H{o}s--Szekeres theorem on monotone subsequences.
  First, we define three canonical transformations on these tournaments called
Color, Record, and Dual. We use these to establish a reduction to special
tournaments with natural geometric and combinatorial properties. In many cases
(including all known tight examples), these tournaments have recursive Gallai
decompositions. Not all relevant tournaments have Gallai decompositions, but
those that do satisfy the desired $N^{2/3}$ bound by recent work of Wagner,
roughly analogous to earlier work of Fox, Grinshpun, and Pach on a similar
\emph{undirected} problem.
  Second, we consider the related geometric problem of bounding
\emph{slice-increasing} sets $S\subseteq [n]^3$, which---under an additional
ordering hypothesis on $S$---was shown by Loh to be equivalent to the original
question. In particular, we establish a rigorous connection from a problem of
Szab\'o and Tardos, raise a stronger $L^2$-question on slice-counts, and
mention a surprising overlap with the joints problem.


title: Lossy Asymptotic Equipartition property for Hierarchical Data Structures

abstract:
  This paper presents a rate-distortion theory for hierarchical networked data
structures modelled as tree-indexed multitype process. To be specific, this
paper gives a generalized Asymptotic Equipartition Property (AEP) for the
Process. The general methodology of proof of the AEP are process level large
deviation principles for suitably defined empirical measures for muiltitype
Galton-Watson trees.


title:
Resilience of Locally Routed Network Flows: More Capacity is Not Always
  Better

abstract:
  In this paper, we are concerned with the resilience of locally routed network
flows with finite link capacities. In this setting, an external inflow is
injected to the so-called origin nodes. The total inflow arriving at each node
is routed locally such that none of the outgoing links are overloaded unless
the node receives an inflow greater than its total outgoing capacity. A link
irreversibly fails if it is overloaded or if there is no operational link in
its immediate downstream to carry its flow. For such systems, resilience is
defined as the minimum amount of reduction in the link capacities that would
result in the failure of all the outgoing links of an origin node. We show that
such networks do not necessarily become more resilient as additional capacity
is built in the network. Moreover, when the external inflow does not exceed the
network capacity, selective reductions of capacity at certain links can
actually help averting the cascading failures, without requiring any change in
the local routing policies. This is an attractive feature as it is often easier
in practice to reduce the available capacity of some critical links than to add
physical capacity or to alter routing policies, e.g., when such policies are
determined by social behavior, as in the case of road traffic networks. The
results can thus be used for real-time monitoring of distance-to-failure in
such networks and devising a feasible course of actions to avert systemic
failures.


title:
Semi-numerical solution for a fractal telegraphic dual-porosity fluid
  flow model

abstract:
  In this work, we present a semi-numerical solution of a fractal telegraphic
dual-porosity fluid flow model. It combines Laplace transform and finite
difference schemes. The Laplace transform handles the time variable whereas the
finite difference method deals with the spatial coordinate. This semi-numerical
scheme is not restricted by space discretization and allows the computation of
a solution at any time without compromising numerical stability or the mass
conservation principle. Our formulation results in a non-analytically-solvable
second-order differential equation whose numerical treatment outcomes in a
tri-diagonal linear algebraic system. Moreover, we describe comparisons between
semi-numerical and semi-analytical solutions for particular cases. Results
agree well with those from semi-analytic solutions. Furthermore, we expose a
parametric analysis from the coupled model in order to show the effects of
relevant parameters on pressure profiles and flow rates for the case where
neither analytic nor semi-analytic solutions are available.


title: Inelastic scattering of xenon atoms by quantized vortices in superfluids

abstract:
  We study inelastic interactions of particles with quantized vortices in
superfluids by using a semi-classical matter wave theory that is analogous to
the Landau two-fluid equations, but allows for the vortex dynamics. The
research is motivated by recent experiments on xenon doped helium nanodroplets
that show clustering of the impurities along the vortex cores. We numerically
simulate the dynamics of trapping and interactions of xenon atoms by quantized
vortices in superfluid helium and the obtained results can be extended to
scattering of other impurities by quantized vortices. Different energies and
impact parameters of incident particles are considered. We show that inelastic
scattering is closely linked to the generation of Kelvin waves along a
quantized vortex during the interaction even if there is no capture. The
capture criterion of an impurity is formulated in terms of the binding energy.


title: Recipes for Edge-Transitive Tetravalent Graphs

abstract:
  This paper is to accompany the Census of Edge-Transitive Tetravalent Graphs,
available at jan.ucc.nau.edu/~swilson/C4FullSite/index.html, which is a
collection of all known edge-transitive graphs of valence 4 up to 512 vertices.
The Census contains information for each graph. This information includes
parameters such as group order, diameter, girth etc., all known constructions,
relations to other graphs in the Census and intersting substructures such as
colorings, cycle structures, and dissections. We try to present most graphs as
members of one or more parameterized families, and one purpose of this paper is
to gather together, here in one place, descriptions of each of these families,
to show how each is constructed, what the history of each is and how one family
is related to another. We also discuss in this paper the theory and techniques
behind computer searches leading to many entries in the Census.


title: Simulations of the magnetospheres of accreting millisecond pulsars

abstract:
  Accreting pulsars power relativistic jets, and display a complex spin
phenomenology. These behaviours may be closely related to the large-scale
configuration of the star's magnetic field, shaped by its interaction with the
surrounding accretion disc. Here we present the first relativistic simulations
of the interaction of a pulsar magnetosphere with an accretion flow. Our
axisymmetric simulations treat the magnetospheric, or coronal, regions using a
resistive extension of force-free electrodynamics. The magnetic field is also
evolved inside the disc, which is a defined volume with a specified velocity
field and conductivity profile, found using an alpha-disc model. We study a
range of disc alpha-parameters, thicknesses, magnetic Prandtl numbers, and
inner truncation radii. We find that a large fraction of the magnetic flux in
the pulsar's closed zone is opened by the intrusion of the disc, leading to an
enhancement of the power extracted by the pulsar wind and the spin-down torque
applied to the pulsar. In our simulations, most of the spin-down contribution
to the stellar torque acts on open field lines. The efficiency of field-line
opening is high in the simulations' long-term quasi-steady states, which
implies that a millisecond pulsar's electromagnetic wind could be strong enough
to power the observed neutron-star radio jets, and may significantly affect the
pulsar's spin evolution.


title:
A Measurement of the Galaxy Group-Thermal Sunyaev-Zel'dovich Effect
  Cross-Correlation Function

abstract:
  Stacking cosmic microwave background (CMB) maps around known galaxy clusters
and groups provides a powerful probe of the distribution of hot gas in these
systems via the Sunyaev-Zel'dovich (SZ) effect. A stacking analysis allows one
to detect the average SZ signal around low mass halos, and to extend
measurements out to large scales, which are too faint to detect individually in
the SZ or in X-ray emission. In addition, cross correlations between SZ maps
and other tracers of large-scale structure (with known redshifts) can be used
to extract the redshift-dependence of the SZ background. Motivated by these
exciting prospects, we measure the two-point cross-correlation function between
a catalog of $\sim 380,000$ galaxy groups (with redshifts spanning
$z=0.01-0.2$) from the Sloan Digital Sky Survey (SDSS) and Compton-y parameter
maps constructed by the Planck collaboration. We find statistically significant
correlations between the group catalog and Compton-y maps in each of six
separate mass bins, with estimated halo masses in the range $10^{11.5-15.5}
M_\odot/h$. We compare these measurements with halo models of the SZ signal,
which describe the stacked measurement in terms of one-halo and two-halo terms.
The one-halo term quantifies the average pressure profile around the groups in
a mass bin, while the two-halo term describes the contribution of correlated
neighboring halos. For the more massive groups we find clear evidence for the
one- and two-halo regimes, while groups with mass below $10^{13} M_\odot/h$ are
dominated by the two-halo term given the resolution of Planck data. We use the
signal in the two-halo regime to determine the bias-weighted electron pressure
of the universe: $\langle b P_e \rangle= 1.50 \pm 0.226 \times 10^{-7}$ keV
cm$^{-3}$ (1-$\sigma$) at $z\approx 0.15$.


title:
How polarizabilities and $C_6$ coefficients actually vary with atomic
  volume

abstract:
  In this work we investigate how atomic $C_6$ coefficients and static dipole
polarizabilities $\alpha$ scale with effective volume. We show, using confined
atoms covering rows 1-5 of the periodic table, that $C_6/C_6^R\approx
(V/V^R)^{p_Z}$ and $\alpha/\alpha^R\approx (V/V^R)^{p'_Z}$ (for volume $V=\int
dr \frac{4\pi}{3}r^3 n(r)$) where $C_6^R$, $\alpha^R$ and $V^R$ are the
reference values and effective volume of the free atom. The scaling exponents
$p_Z$ and $p'_Z$ vary substantially as a function of element number $Z=N$, in
contrast to the standard "rule of thumb" that $p_Z=2$ and $p'_Z=1$. Remarkably,
We find that the polarizability and $C_6$ exponents $p'$ and $p$ are related by
$p'\approx p-0.615$ rather than the expected $p'\approx p/2$. Results are
largely independent of the form of the confining potential (harmonic, cubic and
quartic potentials are considered) and kernel approximation, justifying this
analysis.


title: CarbonKit: Designing A Personal Carbon Tracking Platform

abstract:
  Ubiquitous technology platforms have been created to track and improve health
and fitness; similar technologies can help individuals monitor and reduce their
carbon footprints. This paper proposes CarbonKit, a platform combining
technology, markets, and incentives to empower and reward people for reducing
their carbon footprint. We argue that a goal-and-reward behavioral feedback
loop can be combined with the Big Data available from tracked activities, apps,
and social media to make CarbonKit an integral part of individuals daily lives.
CarbonKit comprises five modules that link personal carbon tracking, health and
fitness, social media, and economic incentives. Protocols for safeguarding
security, privacy and individuals control over their own data are essential to
the design of the CarbonKit. Initially CarbonKit would operate on a voluntary
basis, but such a system can also serve as part of a mandatory region-wide
initiative. We use the example of the British Columbia to illustrate the
regulatory framework and participating stakeholders that would be required to
support the CarbonKit in specific jurisdictions.


title:
Keldysh meets Lindblad: Correlated Gain and Loss in Higher-Order
  Perturbation Theory

abstract:
  Motivated by correlated decay processes producing gain, loss and lasing in
driven semiconductor quantum-dots, we develop a theoretical technique using
Keldysh diagrammatic perturbation theory to derive a Lindblad master equation
that goes beyond the usual second order perturbation theory. We demonstrate the
method on the driven dissipative Rabi model, including terms up to fourth order
in the interaction between the qubit and both the resonator and environment.
This results in a large class of Lindblad dissipators and associated rates
which go beyond the terms that have previously been proposed to describe
similar systems. All of the additional terms contribute to the system behaviour
at the same order of perturbation theory. We then apply these results to
analyse the phonon-assisted steady-state gain of a microwave field driving a
double quantum-dot in a resonator. We show that resonator gain and loss are
substantially affected by dephasing-assisted dissipative processes in the
quantum-dot system. These additional processes, which go beyond recently
proposed polaronic theories, are in good quantitative agreement with
experimental observations.


title: Dephasing-assisted Gain and Loss in Mesoscopic Quantum Systems

abstract:
  Motivated by recent experiments, we analyse the phonon-assisted steady-state
gain of a microwave field driving a double quantum-dot in a resonator. We apply
the results of our companion paper, which derives the complete set of
fourth-order Lindblad dissipators using Keldysh methods, to show that resonator
gain and loss are substantially affected by dephasing-assisted dissipative
processes in the quantum-dot system. These additional processes, which go
beyond recently proposed polaronic theories, are in good quantitative agreement
with experimental observations


title:
Wireless Energy Harvesting Cooperative Communications with Direct Link
  and Energy Accumulation

abstract:
  This paper investigates a wireless energy harvesting cooperative network
(WEHCN) consisting of a source, a decode-and-forward (DF) relay and a
destination. We consider the relay as an energy harvesting (EH) node equipped
with EH circuit and a rechargeable battery. Moreover, the direct link between
source and destination is assumed to exist. The relay can thus harvest and
accumulate energy from radio-frequency signals ejected by the source and assist
its information transmission opportunistically. We develop an incremental
accumulate-then-forward (IATF) relaying protocol for the considered WEHCN. In
the IATF protocol, the source sends its information to destination via the
direct link and requests the relay to cooperate only when it is necessary such
that the relay has more chances to accumulate the harvested energy. By modeling
the charging/discharging behaviors of the relay battery as a finite-state
Markov chain, we derive a closed-form expression for the outage probability of
the proposed IATF. Numerical results validate our theoretical analysis and show
that the IATF scheme can significantly outperform the direct transmission
scheme without cooperation.


title:
Large field enhancement obtained by combining Fabry-Perot resonance and
  Rayleigh anomaly in photonic crystal slabs

abstract:
  By applying the properties of Fabry-Perot resonance and Rayleigh anomaly, we
have shown that a photonic crystal slab can scatter the light from an incident
plane wave into a diffracted light with a very large reflection or transmission
coefficient. The enhanced field is either a propagating diffraction order (with
a grazing angle of diffraction) or a weakly evanescent order, so it can be
particularly useful for applications requiring an enhanced propagating field
(or an enhanced field with a low attenuation). An efficient effective medium
technique is developed for the design of the resonant photonic crystal slabs.
Numerical simulations have shown that photonic crystal slabs with low index
contrast, such as the ones found in the cell wall of diatoms, can enhance the
intensity of the incident light by four orders of magnitude.


title: On Univariate Convex Regression

abstract:
  We find the local rate of convergence of the least squares estimator (LSE) of
a one dimensional convex regression function when (a) a certain number of
derivatives vanish at the point of interest, and (b) the true regression
function is locally affine. In each case we derive the limiting distribution of
the LSE and its derivative. The pointwise limiting distributions depend on the
second and third derivatives at 0 of the "invelope function" of the integral of
a two-sided Brownian motion with polynomial drifts. We also investigate the
inconsistency of the LSE and the unboundedness of its derivative at the
boundary of the domain of the covariate space. An estimator of the argmin of
the convex regression function is proposed and its asymptotic distribution is
derived. Further, we present some new results on the characterization of the
convex LSE that may be of independent interest.


title: Low-Rank Matrix Completion using Nuclear Norm with Facial Reduction

abstract:
  Minimization of the nuclear norm is often used as a surrogate, convex
relaxation, for finding the minimum rank completion (recovery) of a partial
matrix. The minimum nuclear norm problem can be solved as a trace minimization
semidefinite programming problem, (SDP). The SDP and its dual are regular in
the sense that they both satisfy strict feasibility. Interior point algorithms
are the current methods of choice for these problems. This means that it is
difficult to solve large scale problems and difficult to get high accuracy
solutions.
  In this paper we take advantage of the structure at optimality for the
minimum nuclear norm problem. We show that even though strict feasibility
holds, the facial reduction framework can be successfully applied to obtain a
proper face that contains the optimal set, and thus can dramatically reduce the
size of the final nuclear norm problem while guaranteeing a low-rank solution.
We include numerical tests for both exact and noisy cases. In all cases we
assume that knowledge of a target rank is available.


title: Ising-Type Magnetic Ordering in Atomically Thin FePS3

abstract:
  Magnetism in two-dimensional materials is not only of fundamental scientific
interest but also a promising candidate for numerous applications. However,
studies so far, especially the experimental ones, have been mostly limited to
the magnetism arising from defects, vacancies, edges or chemical dopants which
are all extrinsic effects. Here, we report on the observation of intrinsic
antiferromagnetic ordering in the two-dimensional limit. By monitoring the
Raman peaks that arise from zone folding due to antiferromagnetic ordering at
the transition temperature, we demonstrate that FePS3 exhibits an Ising-type
antiferromagnetic ordering down to the monolayer limit, in good agreement with
the Onsager solution for two-dimensional order-disorder transition. The
transition temperature remains almost independent of the thickness from bulk to
the monolayer limit with TN ~118 K, indicating that the weak interlayer
interaction has little effect on the antiferromagnetic ordering.


title:
Every Filter Extracts A Specific Texture In Convolutional Neural
  Networks

abstract:
  Many works have concentrated on visualizing and understanding the inner
mechanism of convolutional neural networks (CNNs) by generating images that
activate some specific neurons, which is called deep visualization. However, it
is still unclear what the filters extract from images intuitively. In this
paper, we propose a modified code inversion algorithm, called feature map
inversion, to understand the function of filter of interest in CNNs. We reveal
that every filter extracts a specific texture. The texture from higher layer
contains more colours and more intricate structures. We also demonstrate that
style of images could be a combination of these texture primitives. Two methods
are proposed to reallocate energy distribution of feature maps randomly and
purposefully. Then, we inverse the modified code and generate images of diverse
styles. With these results, we provide an explanation about why Gram matrix of
feature maps \cite{Gatys_2016_CVPR} could represent image style.


title:
Power Data Classification: A Hybrid of a Novel Local Time Warping and
  LSTM

abstract:
  In this paper, for the purpose of data centre energy consumption monitoring
and analysis, we propose to detect the running programs in a server by
classifying the observed power consumption series. Time series classification
problem has been extensively studied with various distance measurements
developed; also recently the deep learning based sequence models have been
proved to be promising. In this paper, we propose a novel distance measurement
and build a time series classification algorithm hybridizing nearest neighbour
and long short term memory (LSTM) neural network. More specifically, first we
propose a new distance measurement termed as Local Time Warping (LTW), which
utilizes a user-specified set for local warping, and is designed to be
non-commutative and non-dynamic programming. Second we hybridize the 1NN-LTW
and LSTM together. In particular, we combine the prediction probability vector
of 1NN-LTW and LSTM to determine the label of the test cases. Finally, using
the power consumption data from a real data center, we show that the proposed
LTW can improve the classification accuracy of DTW from about 84% to 90%. Our
experimental results prove that the proposed LTW is competitive on our data set
compared with existed DTW variants and its non-commutative feature is indeed
beneficial. We also test a linear version of LTW and it can significantly
outperform existed linear runtime lower bound methods like LB_Keogh.
Furthermore, with the hybrid algorithm, for the power series classification
task we achieve an accuracy up to about 93%. Our research can inspire more
studies on time series distance measurement and the hybrid of the deep learning
models with other traditional models.


title: Density-functional study of plutonium monoxide monohydride

abstract:
  The structural, electronic, mechanical, optical, thermodynamic properties of
plutonium monoxide monohydride (PuOH) are studied by density-functional
calculations within the framework of LDA/GGA and LDA/GGA+U.From the total
energy calculation, the lowest-energy crystal structure of PuOH is predicted to
have space group F-43m (No. 216). Within the LDA+U framework, the calculated
lattice parameter of F-43m-PuOH is in good agreement with the experimental
value and the corresponding ground state is predicted to be an
antiferromagnetic charge-transfer insulator. Furthermore, we investigate the
bonding character of PuOH by analyzing the electron structure and find that
there are a stronger Pu-O bond and a weaker Pu-H bond.The mechanical properties
including the elastic constants, elastic moduli and Debye's temperature, and
the optical properties including the reflectivity and absorption coefficient
are also calculated. We then compute the phonon spectrum which verified the
dynamical stability of F-43m-PuOH. Some thermodynamic quantities such as the
specific heat are evaluated. Finally we calculate the formation energy of PuOH,
and the reaction energies for the oxidation of PuOH and PuOH-coated Pu, which
are in reasonable agreement with the experimental values.


title:
Development of a two-dimensional imaging GEM detector using the
  resistive anode readout method with $6\times6$ cells

abstract:
  We report the application of the resistive anode readout method on a two
dimensional imaging GEM detector. The resistive anode consists of $6\times6$
cells with the cell size $6~\mathrm{mm}\times6~\mathrm{mm}$. New electronics
and DAQ system are used to process the signals from the 49 readout channels.
The detector has been tested by using the X-ray tube (8~keV). The spatial
resolution of the detector is about $103.46~\mathrm{{\mu}m}$ with the detector
response part about $66.41~\mathrm{{\mu}m}$. The nonlinearity of the detector
is less than $1.5\%$. A quite good two dimensional imaging capability is
achieved as well. The performances of the detector show the prospect of the
resistive anode readout method for the large readout area imaging detectors.


title: Naming a Channel with Beeps

abstract:
  We consider a communication channel in which the only possible communication
mode is transmitting beeps, which reach all the nodes instantaneously. Nodes
are anonymous, in that they do not have any individual identifiers. The
algorithmic goal is to randomly assign names to the nodes in such a manner that
the names make a contiguous segment of positive integers starting from $1$. We
give a Las Vegas naming algorithm for the case when the number of nodes $n$ is
known, and a Monte Carlo algorithm for the case when the number of nodes $n$ is
not known. The algorithms are provably optimal with respect to the expected
time $O(n\log n)$, the number of used random bits $O(n\log n)$, and the
probability of error.


title:
Estimation of Mutation Rates from Fluctuation Experiments via
  Probability Generating Functions

abstract:
  This paper calculates probability distributions modeling the Luria-Delbr\"uck
experiment. We show that by thinking purely in terms of generating functions,
and using a 'backwards in time' paradigm, that formulas describing various
situations can be easily obtained. This includes a generating function for
Haldane's probability distribution due to Ycart. We apply our formulas to both
simulated and real data created by looking at yeast cells acquiring an
immunization to the antibiotic canavanine.
  This paper is somewhat incomplete, having been last significantly modified in
March 29, 2014. However the first author feels that this paper has some
worthwhile ideas, and so is going to make this paper publicly available.


title:
Phase transition and critical phenomena of black holes: A general
  approach

abstract:
  We present a general framework to study the phase transition of a black hole.
Assuming that there is a phase transition, it is shown that without invoking
any specific black hole, the critical exponents and the scaling powers can be
obtained. We find that the values are exactly same which were calculated by
taking explicit forms of different black hole spacetimes. The reason for this
universality is also explained. The implication of the analysis is -- one does
not need to investigate this problem case by case, what the people are doing
right now. We also observe that these, except two such quantities, are
independent of the details of the spacetime dimensions.


title: Affine-compact functors

abstract:
  Several well known polytopal constuctions are examined from the functorial
point of view. A naive analogy between the Billera-Sturmfels fiber polytope and
the abelian kernel is disproved by an infinite explicit series of polytopes. A
correct functorial formula is provided in terms of the affine-compact kernel.
The dual cokernel object is almost always the natural affine projection. The
Mond-Smith-van Straten space of sandwiched simplices, useful in stochastic
factorizations, leads to a different kind of affine-compact functors and new
challenges in polytope theory.


title:
Delayed triggering of radio Active Galactic Nuclei in gas-rich minor
  mergers in the local Universe

abstract:
  We examine the processes triggering star formation and Active Galactic
Nucleus (AGN) activity in a sample of 25 low redshift ($z<0.13$) gas-rich
galaxy mergers observed at milli-arcsecond resolution with Very Long Baseline
Interferometry as part of the mJy Imaging VLBA Exploration at 20cm (mJIVE-20)
survey. The high ($>10^7$ K) brightness temperature required for an mJIVE-20
detection allows us to unambiguously identify the radio AGN in our sample. We
find three such objects. Our VLBI AGN identifications are classified as
Seyferts or LINERs in narrow line optical diagnostic plots; mid-infrared
colours of our targets and the comparison of H$\alpha$ star formation rates
with integrated radio luminosity are also consistent with the VLBI
identifications. We reconstruct star formation histories in our galaxies using
optical and UV photometry, and find that these radio AGN are not triggered
promptly in the merger process, consistent with previous findings for non-VLBI
samples of radio AGN. This delay can significantly limit the efficiency of
feedback by radio AGN triggered in galaxy mergers. We find that radio AGN hosts
have lower star formation rates than non-AGN radio-selected galaxies at the
same starburst age. Conventional and VLBI radio imaging shows these AGN to be
compact on arcsecond scales. Our modeling suggests that the actual sizes of
AGN-inflated radio lobes may be much larger than this, but these are too faint
to be detected in existing observations. Deep radio imaging is required to map
out the true extent of the AGN, and to determine whether the low star formation
rates in radio AGN hosts are a result of the special conditions required for
radio jet triggering, or the effect of AGN feedback.


title: Auslander-Gorenstein algebras and precluster tilting

abstract:
  We generalize the notions of $n$-cluster tilting subcategories and
$\tau$-selfinjective algebras into $n$-precluster tilting subcategories and
$\tau_n$-selfinjective algebras, where we show that a subcategory naturally
associated to $n$-precluster tilting subcategories has a higher
Auslander--Reiten theory. Furthermore, we give a bijection between
$n$-precluster tilting subcategories and $n$-minimal Auslander--Gorenstein
algebras, which is a higher dimensional analog of Auslander--Solberg
correspondence (Auslander--Solberg, 1993) as well as a Gorenstein analog of
$n$-Auslander correspondence (Iyama, 2007). The Auslander--Reiten theory
associated to an $n$-precluster tilting subcategory is used to classify the
$n$-minimal Auslander--Gorenstein algebras into four disjoint classes. Our
method is based on relative homological algebra due to Auslander--Solberg.


title:
Are wearable devices ready for HTTPS? Measuring the cost of secure
  communication protocols on wearable devices

abstract:
  The majority of available wearable devices require communication with
Internet servers for data analysis and storage, and rely on a paired smartphone
to enable secure communication. However, wearable devices are mostly equipped
with WiFi network interfaces, enabling direct communication with the Internet.
Secure communication protocols should then run on these wearables itself, yet
it is not clear if they can be efficiently supported. In this paper, we show
that wearable devices are ready for direct and secure Internet communication by
means of experiments with both controlled and Internet servers. We observe that
the overall energy consumption and communication delay can be reduced with
direct Internet connection via WiFi from wearables compared to using
smartphones as relays via Bluetooth. We also show that the additional HTTPS
cost caused by TLS handshake and encryption is closely related to number of
parallel connections, and has the same relative impact on wearables and
smartphones.


title: $\mathbf{F}_p$-representations over $p$-fields

abstract:
  Let $p$ be a prime, $k$ a finite extension of $\mathbf{F}_p$ of cardinal $q$,
$l$ a finite extension of $k$ of group $\Sigma=\mathrm{Gal}(l|k)$, and $T$ a
subgroup of $l^\times$. Using the method of "little groups", we classify
irreducible $\mathbf{F}_p$-representations of the group $G=T\times_q\Sigma$,
the twisted product of $\Sigma$ with the $\Sigma$-module $T$. We then use these
results to classify irreducible continuous $\mathbf{F}_p$-representations of
the profinite group of automorphisms $\mathrm{Gal}(\tilde K|K)$ of the maximal
galoisian extension $\tilde K$ of a local field $K$ with residue field $k$.


title: Little galoisian modules

abstract:
  Let $p$ be a prime number, let $K$ be a $p$-field (a local field with finite
residue field of characteristic $p$), let $L$ be a finite galoisian tamely
ramified extension of $K$, and let $G=\mathrm{Gal}(L|K)$. Suppose that $L$ is
split over $K$ in the sense that the short exact sequence $1\to T\to G\to
G/T\to1$ has a section, where $T$ is the inertia subgroup of $G$. We determine
the structure of the $\mathbf{F}_p[G]$-module $L^\times\!/L^{\times p}$ in
characteristic $0$ when the $p$-torsion subgroup ${}_pL^\times$ of $L^\times$
has order $p$, and of the $\mathbf{F}_p[G]$-modules $L^\times\!/L^{\times p}$
and $L^+\!/\wp(L^+)$ in characteristic $p$, where $\wp(x)=x^p-x$. Let $\tilde
K$ be a maximal galoisian extension of $K$, let $V$ be the maximal tamely
ramified extension of $K$ in $\tilde K$, let $\Gamma=\mathrm{Gal}(V|K)$, and
let $B$ be the maximal abelian extension of exponent $p$ of $V$ in $\tilde K$.
We determine the structure of the $\mathbf{F}_p[[\Gamma]]$-module
$\mathrm{Gal}(B|V)$, and show how this leads in characteristic $0$ to a simple
proof of the fact that the profinite group $\mathrm{Gal}(\tilde K|K)$ is
generated by $[K:\mathbf{Q}_p]+3$ elements.


title: Wildly primitive extensions

abstract:
  A finite separable extension of a field is called primitive if there are no
intermediate extensions. The most interesting primitive extensions of a local
field with finite residue field are the wildly ramified ones, and our aim here
is to parametrise them in a canonical manner.


title: Singular spectral shift function for Schr\"odinger operators

abstract:
  Let $H_0 = -\Delta + V_0(x)$ be a Schroedinger operator on
$L_2(\mathbb{R}^\nu),$ $\nu=1,2,$ or 3, where $V_0(x)$ is a bounded measurable
real-valued function on $\mathbb{R}^\nu.$ Let $V$ be an operator of
multiplication by a bounded integrable real-valued function $V(x)$ and put $H_r
= H_0+rV$ for real $r.$ We show that the associated spectral shift function
(SSF) $\xi$ admits a natural decomposition into the sum of absolutely
continuous $\xi^{(a)}$ and singular $\xi^{(s)}$ SSFs. This is a special case of
an analogous result for resolvent comparable pairs of self-adjoint operators,
which generalises the known case of a trace class perturbation while also
simplifying its proof. We present two proofs -- one short and one long -- which
we consider to have value of their own. The long proof along the way reframes
some classical results from the perturbation theory of self-adjoint operators,
including the existence and completeness of the wave operators and the
Birman-Krein formula relating the scattering matrix and the SSF. The two proofs
demonstrate the equality of the singular SSF with two a priori different but
intrinsically integer-valued functions: the total resonance index and the
singular $\mu$-invariant.


title:
Learning to Rank Questions for Community Question Answering with Ranking
  SVM

abstract:
  This paper presents our method to retrieve relevant queries given a new
question in the context of Discovery Challenge: Learning to Re-Ranking
Questions for Community Question Answering competition. In order to do that, a
set of learning to rank methods was investigated to select an appropriate
method. The selected method was optimized on training data by using a search
strategy. After optimizing, the method was applied to development and test set.
Results from the competition indicate that the performance of our method
outperforms almost participants and show that Ranking SVM is efficient for
retrieving relevant queries in community question answering.


title: Revealing the inner structure of the newly observed $D_2^*(3000)$

abstract:
  Stimulated by the recent observation of the $D_2^\ast(3000)$, we study the
decay behaviors of the $3P$ and $2F$ charmed mesons in the present work. By
comparing the masses and decay properties of the $3^3P_2$ and $2^3F_2$ charmed
mesons with the observation of the $D_2^\ast(3000)$, we conclude that the most
possible assignment of the $D_2^\ast(3000)$ is the $3^3P_2$ charmed meson,
while the assignment of the $2^3F_2$ charmed meson could not be fully exclude.
The results of the unobserved $3P$ and $2F$ charmed mesons in this work could
provide some fundamental information of searching for these charmed mesons in
the further experiments by LHCb and forthcoming Belle II.


title: Occlusion-Model Guided Anti-Occlusion Depth Estimation in Light Field

abstract:
  Occlusion is one of the most challenging problems in depth estimation.
Previous work has modeled the single-occluder occlusion in light field and get
good results, however it is still difficult to obtain accurate depth for
multi-occluder occlusion. In this paper, we explore the multi-occluder
occlusion model in light field, and derive the occluder-consistency between the
spatial and angular space which is used as a guidance to select the un-occluded
views for each candidate occlusion point. Then an anti-occlusion energy
function is built to regularize depth map. The experimental results on public
light field datasets have demonstrated the advantages of the proposed algorithm
compared with other state-of-the-art light field depth estimation algorithms,
especially in multi-occluder areas.


title: Face Alignment In-the-Wild: A Survey

abstract:
  Over the last two decades, face alignment or localizing fiducial facial
points has received increasing attention owing to its comprehensive
applications in automatic face analysis. However, such a task has proven
extremely challenging in unconstrained environments due to many confounding
factors, such as pose, occlusions, expression and illumination. While numerous
techniques have been developed to address these challenges, this problem is
still far away from being solved. In this survey, we present an up-to-date
critical review of the existing literatures on face alignment, focusing on
those methods addressing overall difficulties and challenges of this topic
under uncontrolled conditions. Specifically, we categorize existing face
alignment techniques, present detailed descriptions of the prominent algorithms
within each category, and discuss their advantages and disadvantages.
Furthermore, we organize special discussions on the practical aspects of face
alignment in-the-wild, towards the development of a robust face alignment
system. In addition, we show performance statistics of the state of the art,
and conclude this paper with several promising directions for future research.


title:
Thermal gravitational-wave background in the general pre-inflationary
  scenario

abstract:
  We investigate the primordial gravitational waves (PGWs) in the general
scenario where the inflation is preceded by a pre-inflationary stage with the
effective equation of state $w$. Comparing with the results in the usual
inflationary models, the power spectrum of PGWs is modified in two aspects: One
is the mixture of the perturbation modes caused by he presence of the
pre-inflationary period, and the other is the thermal initial state formed at
the Planck era of the early Universe. By investigating the observational
imprints of these modifications on the B-mode polarization of cosmic microwave
background (CMB) radiation, we obtain the constraints on the conformal
temperature of the thermal gravitational-wave background $T<5.01\times
10^{-4}$Mpc$^{-1}$ and a tensor-to-scalar ratio $r<0.084$ ($95\%$ confident
level), which follows the bounds on total number of e-folds $N>63.5$ for the
model with $w=1/3$, and $N>65.7$ for that with $w=1$. By taking into account
various noises and the foreground radiations, we forecast the detection
possibility of the thermal gravitational-wave background by the future CMBPol
mission, and find that if $r>0.01$, the detection is possible as long as
$T>1.5\times 10^{-4}$Mpc$^{-1}$. However, the effect of different $w$ is quite
small, and it seems impossible to determine its value from the potential
observations of CMBPol mission.


title:
Orbital and Spin Parameter Variations of Partial Eclipsing Low Mass
  X-ray Binary X 1822-371

abstract:
  We report our measurements for orbital and spin parameters of X 1822-371
using its X-ray partial eclipsing profile and pulsar timing from data collected
by the Rossi X-ray Timing Explorer (RXTE). Four more X-ray eclipse times
obtained by the RXTE 2011 observations were combined with historical records to
trace evolution of orbital period. We found that a cubic ephemeris likely
better describes evolution of the X-ray eclipse times during a time span of
about 34 years with a marginal second order derivative of
$\ddot{P}_{orb}=(-1.05 \pm 0.59) \times 10^{-19}$ s$^{-1}$. Using the pulse
arrival time delay technique, the orbital and spin parameters were obtained
from RXTE observations from 1998 to 2011. The detected pulse periods show that
the neutron star in X 1822-371 is continuously spun-up with a rate of
$\dot{P}_{s}=(-2.6288 \pm 0.0095) \times 10^{-12}$ s s$^{-1}$. Evolution of the
epoch of the mean longitude $l=\pi /2$ (i.e. $T_{\pi / 2}$) gives an orbital
period derivative value consistent with that obtained from the quadratic
ephemeris evaluated by the X-ray eclipse but the detected $T_{\pi / 2}$ values
are significantly and systematically earlier than the corresponding expected
X-ray eclipse times by $90 \pm 11$ s. This deviation is probably caused by
asymmetric X-ray emissions. We also attempted to constrain the mass and radius
of the neutron star using the spin period change rate and concluded that the
intrinsic luminosity of X 1822-371 is likely more than $10^{38}$ ergs s$^{-1}$.


title: Weak Arithmetic Cobordism

abstract:
  In the early 2000's Levine and Morel have given a geometric construction of
an algebraic cobordism group defined for all smooth quasi projective varieties
over a field. We show how we can refine their construction to build an Arakelov
version of this group for Arakelov varieties over a number field, and how this
integrates well in the general philosophy of Arakelov geometry.


title: How supernovae became the basis of observational cosmology

abstract:
  This paper is dedicated to the discovery of one of the most important
relationships in supernova cosmology - the relation between the peak luminosity
of Type Ia supernovae and their luminosity decline rate after maximum light.
The history of this relationship is quite long and interesting. The
relationship was independently discovered by the American statistician and
astronomer Bert Woodard Rust and the Soviet astronomer Yury Pavlovich Pskovskii
in the 1970s. Using a limited sample of Type I supernovae they were able to
show that the brighter the supernova is, the slower its luminosity declines
after maximum. Only with the appearance of CCD cameras could Mark Phillips
re-inspect this relationship on a new level of accuracy using a better sample
of supernovae. His investigations confirmed the idea proposed earlier by Rust
and Pskovskii.

categories: astro-ph.SR astro-ph.CO astro-ph.HE physics.hist-ph


title: Molecular simulation of the surface tension of real fluids

abstract:
  Molecular models of real fluids are validated by comparing the vapor-liquid
surface tension from molecular dynamics (MD) simulation to correlations of
experimental data. The considered molecular models consist of up to 28
interaction sites, including Lennard-Jones sites, point charges, dipoles and
quadrupoles. They represent 38 real fluids, such as ethylene oxide, sulfur
dioxide, phosgene, benzene, ammonia, formaldehyde, methanol and water, and were
adjusted to reproduce the saturated liquid density, vapor pressure and enthalpy
of vaporization. The models were not adjusted to interfacial properties,
however, so that the present MD simulations are a test of model predictions. It
is found that all of the considered models overestimate the surface tension. In
most cases, however, the relative deviation between the simulation results and
correlations to experimental data is smaller than 20 %. This observation
corroborates the outcome of our previous studies on the surface tension of
2CLJQ and 2CLJD fluids where an overestimation of the order of 10 to 20 % was
found.

categories: physics.comp-ph cond-mat.soft cs.CE physics.chem-ph


title:
Neutrino Mass, Dark Matter and Anomalous Magnetic Moment of Muon in a
  $U(1)_{L_{\mu}-L_{\tau}}$ Model

abstract:
  The observation of neutrino masses, mixing and the existence of dark matter
are amongst the most important signatures of physics beyond the Standard Model
(SM). In this paper, we propose to extend the SM by a local $L_\mu - L_\tau$
gauge symmetry, two additional complex scalars and three right-handed
neutrinos. The $L_\mu - L_\tau$ gauge symmetry is broken spontaneously when one
of the scalars acquires a vacuum expectation value. The $L_\mu - L_\tau$ gauge
symmetry is known to be anomaly free and can explain the beyond SM measurement
of the anomalous muon $({\rm g-2})$ through additional contribution arising
from the extra $Z_{\mu\tau}$ mediated diagram. Small neutrino masses are
explained naturally through the Type-I seesaw mechanism, while the mixing
angles are predicted to be in their observed ranges due to the broken
$L_\mu-L_\tau$ symmetry. The second complex scalar is shown to be stable and
becomes the dark matter candidate in our model. We show that while the
$Z_{\mu\tau}$ portal is ineffective for the parameters needed to explain the
anomalous muon $({\rm g-2})$ data, the correct dark matter relic abundance can
easily be obtained from annihilation through the Higgs portal. Annihilation of
the scalar dark matter in our model can also explain the Galactic Centre gamma
ray excess observed by Fermi-LAT. We show the predictions of our model for
future direct detection experiments and neutrino oscillation experiments.


title:
Heralded quantum controlled phase gates with dissipative dynamics in
  macroscopically-distant resonators

abstract:
  Heralded near-deterministic multi-qubit controlled phase gates with
integrated error detection have recently been proposed by Borregaard et al.
[Phys. Rev. Lett. 114, 110502 (2015)]. This protocol is based on a single
four-level atom (a heralding quartit) and $N$ three-level atoms (operational
qutrits) coupled to a single-resonator mode acting as a cavity bus. Here we
generalize this method for two distant resonators without the cavity bus
between the heralding and operational atoms. Specifically, we analyze the
two-qubit controlled-Z gate and its multi-qubit-controlled generalization
(i.e., a Toffoli-like gate) acting on the two-lowest levels of $N$ qutrits
inside one resonator, with their successful actions being heralded by an
auxiliary microwave-driven quartit inside the other resonator. Moreover, we
propose a circuit-quantum-electrodynamics realization of the protocol with flux
and phase qudits in linearly-coupled transmission-line resonators with
dissipation. These methods offer a quadratic fidelity improvement compared to
cavity-assisted deterministic gates.


title: On the gaps between non-zero Fourier coefficients of eigenforms with CM

abstract:
  Suppose $E$ is an elliptic curve over $\mathbb{Q}$ of conductor $N$ with
complex multiplication (CM) by $\mathbb{Q}(i)$, and $f_E$ is the corresponding
cuspidal Hecke eigenform in $S^{\mathrm{new}}_2(\Gamma_0(N))$. Then $n$-th
Fourier coefficient of $f_E$ is non-zero in the short interval $(X, X +
cX^{\frac{1}{4}})$ for all $X \gg 0$ and for some $c > 0$. As a consequence, we
produce infinitely many cuspidal CM eigenforms $f$ level $N>1$ and weight $k >
2$ for which $i_f(n) \ll n^{\frac{1}{4}}$ holds, for all $n \gg 0$.


title: Non-Hookean statistical mechanics of clamped graphene ribbons

abstract:
  Thermally fluctuating sheets and ribbons provide an intriguing forum in which
to investigate strong violations of Hooke's Law: large distance elastic
parameters are in fact not constant, but instead depend on the macroscopic
dimensions. Inspired by recent experiments on free-standing graphene
cantilevers, we combine the statistical mechanics of thin elastic plates and
large-scale numerical simulations to investigate the thermal renormalization of
the bending rigidity of graphene ribbons clamped at one end. For ribbons of
dimensions $W\times L$ (with $L\geq W$), the macroscopic bending rigidity
$\kappa_R$ determined from cantilever deformations is independent of the width
when $W<\ell_\textrm{th}$, where $\ell_\textrm{th}$ is a thermal length scale,
as expected. When $W>\ell_\textrm{th}$, however, this thermally renormalized
bending rigidity begins to systematically increase, in agreement with the
scaling theory, although in our simulations we were not quite able to reach the
system sizes necessary to determine the fully developed power law dependence on
$W$. When the ribbon length $L > \ell_p$, where $\ell_p$ is the $W$-dependent
thermally renormalized ribbon persistence length, we observe a scaling collapse
and the beginnings of large scale random walk behavior.


title:
Scaled VIP Algorithms for Joint Dynamic Forwarding and Caching in Named
  Data Networks

abstract:
  Emerging Information-Centric Networking (ICN) architectures seek to optimally
utilize both bandwidth and storage for efficient content distribution over the
network. The Virtual Interest Packet (VIP) framework has been proposed to
enable joint design of forwarding and caching within the Named Data Networking
(NDN) architecture. The virtual plane of the VIP framework captures the
measured demand for content objects, but does not reflect interest collapse and
suppression in the NDN network. We aim to further improve the performance of
the existing VIP algorithms by using a modified virtual plane where VIP counts
are appropriately scaled to reflect interest suppression effects. We
characterize the stability region of the modified virtual plane with VIP
scaling, develop a new distributed forwarding and caching algorithm operating
on the scaled VIPs, and demonstrate the throughput optimality of the scaled VIP
algorithm in the virtual plane. Numerical experiments demonstrate significantly
enhanced performance relative to the existing VIP algorithm, as well as a
number of other baseline algorithms.


title: Design and Measurement of Dipole Magnets for CSNS 1.6GeV RCS

abstract:
  The Rapid Cycling Synchrotron (RCS) in Chinese Spallation Neutron Source
(CSNS) accelerates proton beam from 80Mev to 1.6GeV at a repetition rate of
25Hz. All dipole magnets of RCS are operated at AC with biased DC. Aiming at
the properties of these dipole magnets, we take some methods to improve
magnetic field quality in the good region and reduce eddy currents in the iron
core . In this paper, we would present the process of the magnet design and
temperature rise calculation. At the same time, the field measurement results
and temperature test of the prototype magnet are also described and discussed.


title:
Cross Euclidean-to-Riemannian Metric Learning with Application to Face
  Recognition from Video

abstract:
  Riemannian manifolds have been widely employed for video representations in
visual classification tasks including video-based face recognition. The success
mainly derives from learning a discriminant Riemannian metric which encodes the
non-linear geometry of the underlying Riemannian manifolds. In this paper, we
propose a novel metric learning framework to learn a distance metric across a
Euclidean space and a Riemannian manifold to fuse the average appearance and
pattern variation of faces within one video. The proposed metric learning
framework can handle three typical tasks of video-based face recognition:
Video-to-Still, Still-to-Video and Video-to-Video settings. To accomplish this
new framework, by exploiting typical Riemannian geometries for kernel
embedding, we map the source Euclidean space and Riemannian manifold into a
common Euclidean subspace, each through a corresponding high-dimensional
Reproducing Kernel Hilbert Space (RKHS). With this mapping, the problem of
learning a cross-view metric between the two source heterogeneous spaces can be
expressed as learning a single-view Euclidean distance metric in the target
common Euclidean space. By learning information on heterogeneous data with the
shared label, the discriminant metric in the common space improves face
recognition from videos. Extensive experiments on four challenging video face
databases demonstrate that the proposed framework has a clear advantage over
the state-of-the-art methods in the three classical video-based face
recognition tasks.


title: Towards NLO calculations in the parton Reggeization approach

abstract:
  Parton Reggeization approach is the scheme of kT-factorization for multiscale
hard processes, which is based on the Lipatov's gauge invariant effective field
theory (EFT) for high energy processes in QCD. The new type of rapidity
divergences, associated with the log 1/x-corrections, appears in the loop
corrections in this formalism. The covariant procedure of regularization of
rapidity divergences, preserving the gauge invariance of effective action is
described. As an example application, the one-loop correction to the propagator
of Reggeized quark and gamma Q q -scattering vertex are computed. Obtained
results are used to construct the Regge limit of one-loop gamma+gamma -> q +
barq amplitude. The cancelation of rapidity divergences and consistency of the
EFT prediction with the full QCD result is demonstrated. The rapidity
renormalization group within the EFT is discussed.


title:
The Hard Lefschetz Theorem in positive characteristic for the Flag
  Varieties

abstract:
  For a given flag variety, we characterize the primes $p$ for which there
exists a weight $\lambda$ such that the Hard Lefschetz Theorem holds for
multiplication by $\lambda$ on the cohomology of the flag variety with
coefficients in an infinite field of characteristic $p$.


title: Cultural Evolution as a Non-Stationary Stochastic Process

abstract:
  We present an individual based model of cultural evolution, where interacting
agents are coded by binary strings standing for strategies for action,
blueprints for products or attitudes and beliefs. The model is patterned on an
established model of biological evolution, the Tangled Nature Model (TNM),
where a `tangle' of interactions between agents determines their reproductive
success. In addition, our agents also have the ability to copy part of each
other's strategy, a feature inspired by the Axelrod model of cultural
diversity. Unlike the latter, but similarly to the TNM, the model dynamics goes
through a series of metastable stages of increasing length, each characterized
by mutually enforcing cultural patterns. These patterns are abruptly replaced
by other patterns characteristic of the next metastable period. We analyze the
time dependence of the population and diversity in the system, show how
different cultures are formed and merge, and how their survival probability
lacks, in the model, a finite average life-time. Finally, we use historical
data on the number of car manufacturers after the introduction of the
automobile to the market, to argue that ourmodel can qualitatively reproduce
the flurry of cultural activity which follows a disruptive innovation.


title: About the solvability of matrix polynomial equations

abstract:
  We study self-adjoint matrix polynomial equations in a single variable and
prove existence of self-adjoint solutions under some assumptions on the leading
form. Our main result is that any self-adjoint matrix polynomial equation of
odd degree with non-degenerate leading form can be solved in self-adjoint
matrices. We also study equations of even degree and equations in many
variables.


title:
R-ratio of electron-positron annihilation into hadrons: higher-order
  pi2-terms

abstract:
  High-energy behavior of R-ratio of electron-positron annihilation into
hadrons is studied. In particular, it is argued that at any given order of
perturbation theory the re-expansion of the R-ratio in the ultraviolet
asymptotic can be reduced to the form of power series in the naive continuation
of the strong running coupling into the timelike domain. The convergence range
of the re-expanded R-ratio and the corresponding higher-order pi2-terms are
discussed.


title: Quasi-equivalence of Heights and Runge's Theorem

abstract:
  Let $P$ be a polynomial that depends on two variables $X$ and $Y$ and has
algebraic coefficients. If $x$ and $y$ are algebraic numbers with $P(x,y)=0$,
then by work of N\'eron $h(x)/q$ is asymptotically equal to $h(y)/p$ where $p$
and $q$ are the partial degrees of $P$ in $X$ and $Y$, respectively. In this
paper we compute a completely explicit bound for $|h(x)/q-h(y)/p|$ in terms of
$P$ which grows asymptotically as $\max\{h(x),h(y)\}^{1/2}$. We apply this
bound to obtain a simple version of Runge's Theorem on the integral solutions
of certain polynomial equations.


title:
Fine-grained Analysis of Sentence Embeddings Using Auxiliary Prediction
  Tasks

abstract:
  There is a lot of research interest in encoding variable length sentences
into fixed length vectors, in a way that preserves the sentence meanings. Two
common methods include representations based on averaging word vectors, and
representations based on the hidden states of recurrent neural networks such as
LSTMs. The sentence vectors are used as features for subsequent machine
learning tasks or for pre-training in the context of deep learning. However,
not much is known about the properties that are encoded in these sentence
representations and about the language information they capture. We propose a
framework that facilitates better understanding of the encoded representations.
We define prediction tasks around isolated aspects of sentence structure
(namely sentence length, word content, and word order), and score
representations by the ability to train a classifier to solve each prediction
task when using the representation as input. We demonstrate the potential
contribution of the approach by analyzing different sentence representation
mechanisms. The analysis sheds light on the relative strengths of different
sentence embedding methods with respect to these low level prediction tasks,
and on the effect of the encoded vector's dimensionality on the resulting
representations.


title:
Holographic Van der Waals-like phase transition in the Gauss-Bonnet
  gravity

abstract:
  The Van der Waals-like phase transition is observed in temperature-thermal
entropy plane in spherically symmetric charged Gauss-Bonnet-AdS black hole
background. In terms of AdS/CFT, the non-local observables such as holographic
entanglement entropy, Wilson loop, and two point correlation function of very
heavy operators in the field theory dual to spherically symmetric charged
Gauss-Bonnet-AdS black hole have been investigated. All of them exhibit the Van
der Waals-like phase transition for a fixed charge parameter or Gauss-Bonnet
parameter in such gravity background. Further, with choosing various values of
charge or Gauss-Bonnet parameter, the equal area law and the critical exponent
of the heat capacity are found to be consistent with phase structures in
temperature-thermal entropy plane.


title: Lines on K3 quartic surfaces in characteristic 3

abstract:
  We investigate the number of straight lines contained in a K3 quartic surface
\(X\) defined over an algebraically closed field of characteristic 3. We prove
that if \(X\) contains 112 lines, then \(X\) is projectively equivalent to the
Fermat quartic surface; otherwise, \(X\) contains at most 67 lines. We improve
this bound to 58 if \(X\) contains a star (ie four distinct lines intersecting
at a smooth point of \(X\)). Explicit equations of three 1-dimensional families
of smooth quartic surfaces with 58 lines, and of a quartic surface with 8
singular points and 48 lines are provided.


title: Recent progress on Bernoulli convolutions

abstract:
  The Bernoulli convolution with parameter $\lambda\in(0,1)$ is the measure on
$\bf R$ that is the distribution of the random power series $\sum\pm\lambda^n$,
where $\pm$ are independent fair coin-tosses. This paper surveys recent
progress on our understanding of the regularity properties of these measures.


title:
A radiation-hydrodynamic model of accretion columns for ultra-luminous
  X-ray pulsars

abstract:
  Prompted by the recent discovery of pulsed emission from an ultra-luminous
X-ray source, M82 X-2 ("ULX-pulsar"), we perform a two-dimensional
radiation-hydrodynamic simulation of a super-critical accretion flow onto a
neutron star through a narrow accretion column. We set an accretion column with
a cone shape filled with tenuous gas with density of $10^{-4} {\rm g}~ {\rm
cm}^{-3}$ above a neutron star and solve the two dimensional gas motion and
radiative transfer within the column. The side boundaries are set such that
radiation can freely escape, while gas cannot. Since the initial gas layer is
not in a hydrostatic balance, the column gas falls onto the neutron-star
surface, thereby a shock being generated. As a result, the accretion column is
composed of two regions: an upper, nearly free-fall region and a lower settling
region, as was noted by Basko \& Sunyaev (1976). The average accretion rate is
very high; ${\dot M}\sim 10^{2-3} L_{\rm E}/c^2$ (with $L_{\rm E}$ being the
Eddington luminosity), and so radiation energy dominates over gas internal
energy entirely within the column. Despite the high accretion rate, the
radiation flux in the laboratory frame is kept barely below $L_{\rm E}/(4\pi
r^2)$ at a distance $r$ in the settling region so that matter can slowly
accrete. This adjustment is made possible, since large amount of photons
produced via dissipation of kinetic energy of matter can escape through the
side boundaries. The total luminosity can greatly exceed $L_{\rm E}$ by several
orders of magnitude, whereas the apparent luminosity observed from the top of
the column is much less. Due to such highly anisotropic radiation fields,
observed flux should exhibit periodic variations with the rotation period,
provided that the rotation and magnetic axes are misaligned.


title:
Gendo-symmetric algebras, dominant dimensions and Gorenstein homological
  algebra

abstract:
  We prove that a finite dimensional algebra $A$ with representation-finite
subcategory consisting of modules that are semi-Gorenstein-projective and
$n$-th syzygy modules is left weakly Gorenstein. This generalises a theorem of
Ringel and Zhang who proved the result in the case $n=1$. As an application we
show that monomial algebras and endomorphism rings of modules over
representation-finite algebras are weakly Gorenstein. We then give a new
connection between the theory of dominant dimension and Gorenstein homological
algebra for gendo-symmetric algebras. As an application, we will see that the
existence of a non-projective Gorenstein-projective-injective module in a
gendo-symmetric algebra already implies that this algebra is not CM-finite. We
apply out methods to give a first systematic construction of non-weakly
Gorenstein algebras using the theory of gendo-symmetric algebras. In
particular, we can construct non-weakly Gorenstein algebras with an arbitrary
number of simple modules from certain quantum exterior algebras such as the
Liu-Schulz algebra.


title:
An Efficient Precoder Design for Multiuser MIMO Cognitive Radio Networks
  with Interference Constraints

abstract:
  We consider a linear precoder design for an underlay cognitive radio
multiple-input multiple-output broadcast channel, where the secondary system
consisting of a secondary base-station (BS) and a group of secondary users
(SUs) is allowed to share the same spectrum with the primary system. All the
transceivers are equipped with multiple antennas, each of which has its own
maximum power constraint. Assuming zero-forcing method to eliminate the
multiuser interference, we study the sum rate maximization problem for the
secondary system subject to both per-antenna power constraints at the secondary
BS and the interference power constraints at the primary users. The problem of
interest differs from the ones studied previously that often assumed a sum
power constraint and/or single antenna employed at either both the primary and
secondary receivers or the primary receivers. To develop an efficient numerical
algorithm, we first invoke the rank relaxation method to transform the
considered problem into a convex-concave problem based on a downlink-uplink
result. We then propose a barrier interior-point method to solve the resulting
saddle point problem. In particular, in each iteration of the proposed method
we find the Newton step by solving a system of discrete-time Sylvester
equations, which help reduce the complexity significantly, compared to the
conventional method. Simulation results are provided to demonstrate fast
convergence and effectiveness of the proposed algorithm.


title: Robust bounds in multivariate extremes

abstract:
  Extreme value theory provides an asymptotically justified framework for
estimation of exceedance probabilities in regions where few or no observations
are available. For multivariate tail estimation, the strength of extremal
dependence is crucial and it is typically modeled by a parametric family of
spectral distributions. In this work we provide asymptotic bounds on exceedance
probabilities that are robust against misspecification of the extremal
dependence model. They arise from optimizing the statistic of interest over all
dependence models within some neighborhood of the reference model. A certain
relaxation of these bounds yields surprisingly simple and explicit expressions,
which we propose to use in applications. We show the effectiveness of the
robust approach compared to classical confidence bounds when the model is
misspecified. The results are further applied to quantify the effect of model
uncertainty on the Value-at-Risk of a financial portfolio.


title: Einstein-Podolsky-Rosen Entanglement between Separated Atomic Ensembles

abstract:
  The Einstein-Podolsky-Rosen (EPR) entanglement is of special importance not
only for fundamental research in quantum mechanics, but also for quantum
information processing. Establishing EPR entanglement between two memory
systems, such as atomic ensembles, nitrogen-vacancy centers, and
rare-earth-ion-doped solids is promising for realizing spatial-multimode based
quantum communication, quantum computation, and quantum imaging. To date, there
have been few reports on realizing EPR entanglement between physical systems in
true position and momentum. Here we describe successfully establishing such
entanglement between two separated atomic ensembles by using quantum storage.
We clearly prove the existence of EPR entanglement in position and momentum
between two memories by demonstrating the satisfying of the inseparability
criterion with the aid of quantum ghost-imaging and ghost-interference
experiments.


title: Primordial Gravitational Waves from Axion-Gauge Fields Dynamics

abstract:
  Inspired by the chromo-natural inflation model of Adshead&Wyman, we reshape
its scalar content to relax the tension with current observational bounds.
Besides an inflaton, the setup includes a spectator sector in which an axion
and SU(2) gauge fields are coupled via a Chern-Simons-type term. The result is
a viable theory endowed with an alternative production mechanism for
gravitational waves during inflation. The gravitational wave signal sourced by
the spectator fields can be much larger than the contribution from standard
vacuum fluctuations, it is distinguishable from the latter on the basis of its
chirality and, depending on the theory parameters values, also its tilt. This
production process breaks the well-known relation between the tensor-to-scalar
ratio and the energy scale of inflation. As a result, even if the Hubble rate
is itself too small for the vacuum to generate a tensor amplitude detectable by
upcoming experiments, this model still supports observable gravitational waves.


title:
An iterated local search algorithm for the minimum differential
  dispersion problem

abstract:
  Given a set of $n$ elements separated by a pairwise distance matrix, the
minimum differential dispersion problem (Min-Diff DP) aims to identify a subset
of m elements (m < n) such that the difference between the maximum sum and the
minimum sum of the inter-element distances between any two chosen elements is
minimized. We propose an effective iterated local search (denoted by
ILS_MinDiff) for Min-Diff DP. To ensure an effective exploration and
exploitation of the search space, the proposed ILS_MinDiff algorithm iterates
through three sequential search phases: a fast descent-based neighborhood
search phase to find a local optimum from a given starting solution, a local
optima exploring phase to visit nearby high-quality solutions around a given
local optimum, and a local optima escaping phase to move away from the current
search region. Experimental results on six data sets of 190 benchmark instances
demonstrate that ILS_MinDiff competes favorably with the state-of-the-art
algorithms by finding 130 improved best results (new upper bounds).


title: Numerical range with respect to a family of projections

abstract:
  In this note we introduce the concept of the numerical range of a bounded
linear operator with respect to a family of projections. We give a precise
definition and elaborate on its connection to the classical numerical range as
well as to generalisations such as the quadratic numerical range and block
numerical range.


title:
Using Machine Learning to Decide When to Precondition Cylindrical
  Algebraic Decomposition With Groebner Bases

abstract:
  Cylindrical Algebraic Decomposition (CAD) is a key tool in computational
algebraic geometry, particularly for quantifier elimination over real-closed
fields. However, it can be expensive, with worst case complexity doubly
exponential in the size of the input. Hence it is important to formulate the
problem in the best manner for the CAD algorithm. One possibility is to
precondition the input polynomials using Groebner Basis (GB) theory. Previous
experiments have shown that while this can often be very beneficial to the CAD
algorithm, for some problems it can significantly worsen the CAD performance.
  In the present paper we investigate whether machine learning, specifically a
support vector machine (SVM), may be used to identify those CAD problems which
benefit from GB preconditioning. We run experiments with over 1000 problems
(many times larger than previous studies) and find that the machine learned
choice does better than the human-made heuristic.


title:
Experimental transmission of quantum digital signatures over 90-km of
  installed optical fiber using a differential phase shift quantum key
  distribution system

abstract:
  Quantum digital signatures apply quantum mechanics to the problem of
guaranteeing message integrity and non-repudiation with information-theoretical
security, which are complementary to the confidentiality realized by quantum
key distribution. Previous experimental demonstrations have been limited to
transmission distances of less than 5-km of optical fiber in a laboratory
setting. Here we report the first demonstration of quantum digital signatures
over installed optical fiber as well as the longest transmission link reported
to date. This demonstration used a 90-km long differential phase shift quantum
key distribution system to achieve approximately one signed bit per second - an
increase in the signature generation rate of several orders of magnitude over
previous optical fiber demonstrations.


title:
Li-Yau gradient estimate for compact manifolds with negative part of
  Ricci curvature in the Kato class

abstract:
  This article shows that if the negative part of Ricci curvature lies in the
Kato class, the heat kernel satisfies a Li-Yau type estimate. Additionally,
using the resulting heat kernel bound, we show that the obtained heat kernel
estimate leads to bounds on the first Betti number only depending on the Kato
constant.