title:
Feedback Regularization and Geometric PID Control for Trajectory
  Tracking of Coupled Mechanical Systems: Hoop Robots on an Inclined Plane

abstract:
  This paper applies geometric PID control for asymptotic tracking of a desired
trajectory by a hoop robot in the presence of disturbances and uncertainties.
The hoop robot, consisting of a circular body rolling without slip along a
one-dimensional surface, is a planar analog of a spherical robot. A variety of
coupled mechanical system may be used to actuate the hoop robot. This paper
specifically considers two different actuators, one a simple pendulum and the
other an internal cart. The geometric PID controller requires the plant to be a
mechanical system, and the hoop robot does not satisfy this condition.
Therefore a geometric inner loop is presented that gives the hoop robot the
required structure. This procedure is here referred to as feedback
regularization. Feedback regularization--in contrast to feedback
linearization--is coordinate independent, and hence reflects the fundamental
system structure. Note also that the resulting mechanical system is nonlinear
and underactuated. Subsequently, the geometric PID outer loop guarantees
almost-semiglobal tracking with locally exponential convergence, and the
integral action of the PID guarantees robustness to constant disturbances and
parameter uncertainties, including constant inclination of the rolling surface.
The complete tracking controller is the composition of the two
coordinate-independent loops, and therefore is also coordinate independent.


title:
A Hardy-Littlewood-Sobolev type inequality for variable exponents and
  applications to quasilinear Choquard equations involving variable exponent

abstract:
  In this work, we have proved a version of the Hardy-Littlewood-Sobolev
inequality for variable exponents. After we use the variational method to
establish the existence of solution for a class of Choquard equations involving
the $p(x)$-Laplacian operator.


title:
Continuous-time hybridization expansion quantum impurity solver for
  multi-orbital systems with complex hybridizations

abstract:
  We describe an open-source implementation of the continuous-time
hybridization-expansion quantum Monte Carlo method for impurity models with
general instantaneous two-body interactions and complex hybridization
functions. The code is built on the ALPS libraries (Applications and Libraries
for Physics Simulations).


title: Early Signals from Volumetric DDoS Attacks: An Empirical Study

abstract:
  Distributed Denial of Service (DDoS) is a common type of Cybercrime. It can
strongly damage a company reputation and increase its costs. Attackers improve
continuously their strategies. They doubled the amount of unleashed
communication requests in volume, size, and frequency in the last few years.
This occurs against different hosts, causing resource exhaustion. Previous
studies focused on detecting or mitigating ongoing DDoS attacks. Yet,
addressing DDoS attacks when they are already in place may be too late. In this
article, we consider network resilience by early prediction of attack trends.
We show empirically the advantage of using non-parametric leading indicators
for early prediction of volumetric DDoS attacks. We report promising results
over a real dataset from CAIDA. Our results raise new questions and
opportunities for further research in early predicting trends of DDoS attacks.


title: Optimal Sound Absorbing Structures

abstract:
  Causal nature of the acoustic response, for any materials or structures,
dictates an inequality that relates the absorption spectrum of the sample to
its thickness. We present a general recipe for constructing sound-absorbing
structures that can attain near-equality for the causal relation with very high
absorption performance; such structures are denoted optimal. Our strategy
involves using carefully designed acoustic metamaterials as backing to a thin
layer of conventional sound absorbing material, e.g., acoustic sponge. By using
this design approach, we have realized a 12 cm-thick structure that exhibits
broadband, near-perfect flat absorption spectrum starting at around 400 Hz.
From the causal relation, the calculated minimum sample thickness is 11.5 cm
for the observed absorption spectrum. We present the theory that underlies such
absorption performance, involving the evanescent waves and their interaction
with a dissipative medium, and show the excellent agreement with the
experiment.


title: NP vs PSPACE

abstract:
  We present a proof of the conjecture $\mathcal{NP}$ = $\mathcal{PSPACE}$ by
showing that arbitrary tautologies of Johansson's minimal propositional logic
admit "small" polynomial-size dag-like natural deductions in Prawitz's system
for minimal propositional logic. These "small" deductions arise from standard
"large"\ tree-like inputs by horizontal dag-like compression that is obtained
by merging distinct nodes labeled with identical formulas occurring in
horizontal sections of deductions involved. The underlying "geometric" idea: if
the height, $h\left( \partial \right) $ , and the total number of distinct
formulas, $\phi \left( \partial \right) $ , of a given tree-like deduction
$\partial$ of a minimal tautology $\rho$ are both polynomial in the length of
$\rho$, $\left| \rho \right|$, then the size of the horizontal dag-like
compression is at most $h\left( \partial \right) \times \phi \left( \partial
\right) $, and hence polynomial in $\left| \rho \right|$. The attached proof is
due to the first author, but it was the second author who proposed an initial
idea to attack a weaker conjecture $\mathcal{NP}= \mathcal{\mathit{co}NP}$ by
reductions in diverse natural deduction formalisms for propositional logic.
That idea included interactive use of minimal, intuitionistic and classical
formalisms, so its practical implementation was too involved. The attached
proof of $ \mathcal{NP}=\mathcal{PSPACE}$ runs inside the natural deduction
interpretation of Hudelmaier's cutfree sequent calculus for minimal logic.


title: Asynchronous Multi-Task Learning

abstract:
  Many real-world machine learning applications involve several learning tasks
which are inter-related. For example, in healthcare domain, we need to learn a
predictive model of a certain disease for many hospitals. The models for each
hospital may be different because of the inherent differences in the
distributions of the patient populations. However, the models are also closely
related because of the nature of the learning tasks modeling the same disease.
By simultaneously learning all the tasks, multi-task learning (MTL) paradigm
performs inductive knowledge transfer among tasks to improve the generalization
performance. When datasets for the learning tasks are stored at different
locations, it may not always be feasible to transfer the data to provide a
data-centralized computing environment due to various practical issues such as
high data volume and privacy. In this paper, we propose a principled MTL
framework for distributed and asynchronous optimization to address the
aforementioned challenges. In our framework, gradient update does not wait for
collecting the gradient information from all the tasks. Therefore, the proposed
method is very efficient when the communication delay is too high for some task
nodes. We show that many regularized MTL formulations can benefit from this
framework, including the low-rank MTL for shared subspace learning. Empirical
studies on both synthetic and real-world datasets demonstrate the efficiency
and effectiveness of the proposed framework.


title:
Dependence of the broad Fe K$\alpha$ line on the physical parameters of
  AGN

abstract:
  In this paper, the dependence of the broad Fe K$\alpha$ line on the physical
parameters of AGN, such as the black hole mass $M_{BH}$, accretion rate
(equivalently represented by Eddington ratio $\lambda_{Edd}$), and optical
classification, is investigated by applying the X-ray spectra stacking method
to a large sample of AGN which have well measured optical parameters. A broad
line feature is detected ($>3\sigma$) in the stacked spectra of the high
$\lambda_{Edd}$ sub-sample ($\log\lambda_{Edd}>-0.9$). The profile of the broad
line can be well fitted with relativistic broad line model, with the line
energy consistent with highly ionized Fe K$\alpha$ line (i.e. Fe xxvi). A model
consisting of multiple narrow lines cannot be ruled out, however. We found
hints that the Fe K line becomes broader as the $\lambda_{Edd}$ increases. No
broad line feature is shown in the sub-sample of broad-line Seyfert 1 (BLS1)
galaxies and in the full sample, while a broad line might be present, though at
low significance, in the sub-sample of narrow-line Seyfert 1 (NLS1) galaxies.
We find no strong dependence of the broad line on black hole masses. Our
results indicate that the detection/properties of the broad Fe K$\alpha$ line
may strongly depend on $\lambda_{Edd}$, which can be explained if the
ionization state and/or truncation radius of the accretion disc changes with
$\lambda_{Edd}$. The non-detection of the broad line in the BLS1 sub-sample can
be explained if the the average EW of the relativistic Fe K$\alpha$ line is
weak or/and the fraction of sources with relativistic Fe K$\alpha$ line is
small in BLS1 galaxies.


title: Analysis of Exact and Approximated Epidemic Models over Complex Networks

abstract:
  We study the spread of discrete-time epidemics over arbitrary networks for
well-known propagation models, namely SIS (susceptible-infected-susceptible),
SIR (susceptible-infected-recovered), SIRS
(susceptible-infected-recovered-susceptible) and SIV
(susceptible-infected-vaccinated). Such epidemics are described by $2^n$- or
$3^n$-state Markov chains. Ostensibly, because analyzing such Markov chains is
too complicated, their $O(n)$-dimensional nonlinear "mean-field" approximation,
and its linearization, are often studied instead. We provide a complete global
analysis of the epidemic dynamics of the nonlinear mean-field approximation. In
particular, we show that depending on the largest eigenvalue of the underlying
graph adjacency matrix and the rates of infection, recovery, and vaccination,
the global dynamics takes on one of two forms: either the epidemic dies out, or
it converges to another unique fixed point (the so-called endemic state where a
constant fraction of the nodes remain infected). A similar result has also been
shown in the continuous-time case. We tie in these results with the "true"
underlying Markov chain model by showing that the linear model is the tightest
upper-bound on the true probabilities of infection that involves only
marginals, and that, even though the nonlinear model is not an upper-bound on
the true probabilities in general, it does provide an upper-bound on the
probability of the chain not being absorbed. As a consequence, we also show
that when the disease-free fixed point is globally stable for the mean-field
model, the Markov chain has an $O(\log n)$ mixing time, which means the
epidemic dies out quickly. We compare and summarize the results on different
propagation models.


title: Lieb-Thirring Inequalities for Finite and Infinite Gap Jacobi Matrices

abstract:
  We establish Lieb-Thirring power bounds on discrete eigenvalues of Jacobi
operators for Schatten class perturbations under very general assumptions. Our
results apply, in particular, to perturbations of reflectionless Jacobi
operators with finite gap and Cantor-type essential spectrum.


title:
High Efficiency Gamma-Ray Flash Generation via Multiple Compton
  Scattering

abstract:
  Gamma-ray flash generation in near critical density (NCD) target irradiated
by four symmetrical colliding laser pulses is numerically investigated. With
peak intensities about $10^{23}$ W/cm$^2$, the laser pulses boost electron
energy through direct laser acceleration, while pushing them inward with the
ponderomotive force. After backscattering with counter-propagating laser, the
accelerated electron is trapped in the optical lattice or the electromagnetic
standing waves (SW) created by the coherent overlapping of the laser pulses,
and emits gamma-ray photons in Multiple Compton Scattering regime, where
electrons act as a medium transferring energy from the laser to gamma-rays. The
energy conversion rate from laser pulses to gamma-ray can be as high as 50\%


title:
Superconductivity mediated by quantum critical antiferromagnetic
  fluctuations: The rise and fall of hot spots

abstract:
  In several unconventional superconductors, the highest superconducting
transition temperature $T_{c}$ is found in a region of the phase diagram where
the antiferromagnetic transition temperature extrapolates to zero, signaling a
putative quantum critical point. The elucidation of the interplay between these
two phenomena - high-$T_{c}$ superconductivity and magnetic quantum criticality
- remains an important piece of the complex puzzle of unconventional
superconductivity. In this paper, we combine sign-problem-free Quantum Monte
Carlo simulations and field-theoretical analytical calculations to unveil the
microscopic mechanism responsible for the superconducting instability of a
general low-energy model, called spin-fermion model. In this approach,
low-energy electronic states interact with each other via the exchange of
quantum critical magnetic fluctuations. We find that even in the regime of
moderately strong interactions, both the superconducting transition temperature
and the pairing susceptibility are governed not by the properties of the entire
Fermi surface, but instead by the properties of small portions of the Fermi
surface called hot spots. Moreover, $T_{c}$ increases with increasing
interaction strength, until it starts to saturate at the crossover from
hot-spots dominated to Fermi-surface dominated pairing. Our work provides not
only invaluable insights into the system parameters that most strongly affect
$T_{c}$, but also important benchmarks to assess the origin of
superconductivity in both microscopic models and actual materials.


title: A projection algorithm for non-monotone variational inequalities

abstract:
  We introduce and study the convergence properties of a projection-type
algorithm for solving the variational inequality problem for point-to-set
operators. No monotoni\-city assumption is used in our analysis. The operator
defining the problem is only assumed to be continuous in the point-to-set
sense, i.e., inner- and outer-semicontinuous. Additionally, we assume
non-emptiness of the so-called dual solution set. We prove that the whole
sequence of iterates converges to a solution of the variational inequality.
Moreover, we provide numerical experiments illustrating the behavior of our
iterates. Through several examples, we provide a comparison with a recent
similar algorithm.


title: Atomic Force Microscope manipulation of Ag atom on the Si(111) surface

abstract:
  We present first-principles total-energy electronic-structure calculations
that provide the microscopic mechanism of the Ag atom diffusion between the
half unit cells (HUCs) on the Si(111)-(7x7) surface with and without the tip of
the atomic force microscope (AFM). We find that, without the presence of the
AFM tip, the diffusions between the two HUCs are almost symmetric with the
energy barrier of about 1 eV in the both directions. The diffusion is a
two-step process with an intermediate metastable configuration in which the Ag
atom is at the boundary of the HUCs. With the presence of the tip, we find that
the reaction pathways are essentially the same, but the energy barrier in one
direction is substantially reduced to be 0.2 - 0.4 eV by the tip, while that of
the diffusion in the reverse direction remains larger than 1 eV. The Si tip
reduces the energy barrier more than the Pt tip due to the flexibility of the
tip apex structure. In addition to the reduction of the barrier, the tip traps
the diffusing adatom preventing the diffusion in the reverse direction. Also we
find that the shape of the tip apex structure is important for the trapping
ability of the adatom. When the tip apex structure is blunt, the adatom
interacts with the tip atom other than the tip apex atom. The bond formation
between the AFM tip atom and the surface adatom is essential for the atom
manipulation using the AFM tip. Our results show that the atom manipulation is
possible with both the metallic and semiconducting AFM tips.


title:
The Role of Rating and Loan Characteristics in Online Microfunding
  Behaviors

abstract:
  We propose an in-depth study of lending behaviors in Kiva using a mix of
quantitative and large-scale data mining techniques. Kiva is a non-profit
organization that offers an online platform to connect lenders with borrowers.
Their site, kiva.org, allows citizens to microlend small amounts of money to
entrepreneurs (borrowers) from different countries. The borrowers are always
affiliated with a Field Partner (FP) which can be a microfinance institution
(MFI) or other type of local organization that has partnered with Kiva. Field
partners give loans to selected businesses based on their local knowledge
regarding the country, the business sector including agriculture, health or
manufacture among others, and the borrower.Our objective is to understand the
relationship between lending activity and various features offered by the
online platform. Specifically, we focus on two research questions: (i) the role
that MFI ratings play in driving lending activity and (ii) the role that
various loan features have in the lending behavior. The first question analyzes
whether there exists a relationship between the MFI ratings - that lenders can
explore online - and their lending volumes. The second research question
attempts to understand if certain loan features - available online at Kiva -
such as the type of small business, the gender of the borrower, or the loan's
country information might affect the way lenders lend.


title: Reversibility Problem of Multidimensional Finite Cellular Automata

abstract:
  While the reversibility of multidimensional cellular automata is undecidable
and there exists a criterion for determining if a multidimensional linear
cellular automaton is reversible, there are only a few results about the
reversibility problem of multidimensional linear cellular automata under
boundary conditions. This work proposes a criterion for testing the
reversibility of a multidimensional linear cellular automaton under null
boundary condition and an algorithm for the computation of its reverse, if it
exists. The investigation of the dynamical behavior of a multidimensional
linear cellular automaton under null boundary condition is equivalent to
elucidating the properties of block Toeplitz matrix. The proposed criterion
significantly reduce the computational cost whenever the number of cells or the
dimension is large; the discussion can also apply to cellular automata under
periodic boundary condition with a minor modification.


title: A note on some applications of the extension of Abel's lemma

abstract:
  We offer some new applications of an extension of Abel's lemma, as well as
its more general form established by Andrews and Freitas. A nice connection is
established between this lemma and series involving the Riemann zeta function.


title:
Multiple-scale analysis on the radiation within the coupled KdV
  equations

abstract:
  A multiple scale model of the nonlinearly coupled KdV equations is
established to predict mechanism of interaction of equatorial Rossby waves and
barotropic waves in certain case. Analytically, predicted precursor radiation
is a centrosymmetric object and is shown in excellent quantitative agreement
with numerical simulations; furthermore, the multiple scale model elucidates
the salient mechanisms of the interaction of solitary waves and the mechanism
for radiation. While the atmosphere-ocean science community is very interested
in theoretical studies of tropical wave interactions and in developing reduced
dynamical models that can explain some key features of equatorial phenomena,
our analytic predictions quantitively explain formation of radiation during
interaction in Biello's model beyond qualitative level.


title: High energy properties of the flat spectrum radio quasar 4C 50.11

abstract:
  We investigate the $\gamma$-ray and X-ray properties of the flat spectrum
radio quasar (FSRQ) \4c50 at redshift $z= 1.517$. The {\it Fermi} Large Area
Telescope (LAT) data indicate that this source was in an active state since
2013 July. During the active period, the $\gamma$-ray flux increased by more
than a factor of three and two distinct flares were detected with the
variability timescale as short as several hours.
  The $\gamma$-ray spectra can be well fitted by a log-parabola. From the
fitting, we find a correlation between the peak energy and spectral curvature
for the $\gamma$-ray spectra, which is the first time seen in $\gamma$-ray
emission from a blazar. The {\it Swift} X-ray Telescope (XRT) data show that
the source was variable at X-ray energies, but no evidence shows flux or
spectral changes related to the $\gamma$-ray activity. The broad-band X-ray
spectrum obtained with {\it Swift} XRT and {\it NuSTAR} is well described by a
broken PL model, with an extremely hard spectrum ($\Gamma_{1} \sim 0.1$) below
the break energy, $E_{\rm break} \sim 2.1 {\rm keV}$, and $\Gamma_{2} \sim 1.5$
above the break energy. The spectral steepening below $\sim 3$ keV is likely
due to the low energy cut-off in the energy distribution of the photon-emitting
electron population. Both the $\gamma$-ray and X-ray emission appear harder
when brighter. The broad-band spectral energy distribution (SED) is constructed
for the source, and we provide a model fit to the SED. Our modeling suggests
that the emission region should be outside the broad line region, and the
properties of the region indicate a jet with 42\% of the Eddington power during
the active state.


title: On generalized superelliptic Riemann surfaces

abstract:
  A closed Riemann surface $\mathcal X$, of genus $g \geq 2$, is called a
generalized superelliptic curve of level $n \geq 2$ if it admits an order $n$
conformal automorphism $\tau$ so that $\mathcal X/\langle \tau \rangle$ has
genus zero and $\tau$ is central in ${\rm Aut}(\mathcal X)$; the cyclic group
$H=\langle \tau \rangle$ is called a generalized superelliptic group of level
$n$ for $\mathcal X$. These Riemann surfaces are natural generalizations of
hyperelliptic Riemann surfaces (when $n=2$). We provide an algebraic curve
description of these Riemann surfaces in terms of their groups of
automorphisms. Also, we observe that the generalized superelliptic group $H$ of
level $n$ is unique, with the exception of a very particular family of
exceptional generalized superelliptic Riemann surfaces for $n$ even. In
particular, the uniqueness holds if either: (i) $n$ is odd or (ii) the quotient
$\mathcal X/H$ has all its cone points of order $n$ (for instance, when
$\mathcal X$ is a superelliptic curve of level $n$). In the non-exceptional
case, we use this uniqueness property of its generalized superelliptic group
$H$ to observe that the corresponding curves are definable over their fields of
moduli if ${\rm Aut}(\mathcal X)/H$ is neither trivial or cyclic.


title: Numerical Approach to Maximize SNR for CDMA Systems

abstract:
  Signal to Noise Ratio (SNR) is an important index for wireless
communications. There are many methods for increasing SNR. In CDMA systems,
spreading sequences are used. To increase SNR, we have to improve spreading
sequences. In classical approaches, the expression of SNR is not differentiable
in terms of the parameter of the spreading sequences even in no fading
situations. Thus, we express it as the differentiable form and construct the
non-linear programing for maximizing SNR. In particular, we solve the problem
of maximizing SNR numerically by obtaining spreading sequences whose SNR is
guaranteed to be high.


title:
Optimized motor imagery paradigm based on imagining Chinese characters
  writing movement

abstract:
  Motor imagery (MI) is a mental representation of motor behavior that has been
widely used as a control method for a brain-computer interface (BCI), allowing
communication for the physically impaired. The performance of MI based BCI
mainly depends on the subject's ability to self-modulate EEG signals. Proper
training can help naive subjects learn to modulate brain activity proficiently.
However, training subjects typically involves abstract motor tasks and is
time-consuming. To improve the performance of naive subjects during motor
imagery, a novel paradigm was presented that would guide naive subjects to
modulate brain activity effectively. In this new paradigm, pictures of the left
or right hand were used as cues for subjects to finish the motor imagery task.
Fourteen healthy subjects (11 male, aged 22-25 years, mean 23.6+/-1.16)
participated in this study. The task was to imagine writing a Chinese
character. Specifically, subjects could imagine hand movements following the
sequence of writing strokes in the Chinese character. This paradigm was meant
to find an effective and familiar action for most Chinese people, to provide
them with a specific, extensively practiced task and help them modulate brain
activity. Results showed that the writing task paradigm yielded significantly
better performance than the traditional arrow paradigm (p<0.001). Questionnaire
replies indicated that most subjects thought the new paradigm was easier and
more comfortable. The proposed new motor imagery paradigm could guide subjects
to help them modulate brain activity effectively. Results showed that there
were significant improvements using new paradigm, both in classification
accuracy and usability.


title:
G10/COSMOS: 38 band (far-UV to far-IR) panchromatic photometry using
  LAMBDAR

abstract:
  We present a consistent total flux catalogue for a $\sim$1 deg$^2$ subset of
the COSMOS region (R.A. $\in [149.55\degr, 150.65\degr]$, DEC $\in [1.80\degr,
2.73\degr]$) with near-complete coverage in 38 bands from the far-ultraviolet
to the far-infrared. We produce aperture matched photometry for 128,304 objects
with i < 24.5 in a manner that is equivalent to the Wright et al. (2016)
catalogue from the low-redshift (z < 0.4) Galaxy and Mass Assembly (GAMA)
survey. This catalogue is based on publicly available imaging from GALEX, CFHT,
Subaru, VISTA, Spitzer and Herschel, contains a robust total flux measurement
or upper limit for every object in every waveband and complements our
re-reduction of publicly available spectra in the same region. We perform a
number of consistency checks, demonstrating that our catalogue is comparable to
existing data sets, including the recent COSMOS2015 catalogue (Laigle et al.
2016). We also release an updated Davies et al. (2015) spectroscopic catalogue
that folds in new spectroscopic and photometric redshift data sets. The
catalogues are available for download at
http://cutout.icrar.org/G10/dataRelease.php. Our analysis is optimised for both
panchromatic analysis over the full wavelength range and for direct comparison
to GAMA, thus permitting measurements of galaxy evolution for 0 < z < 1 while
minimising the systematic error resulting from disparate data reduction
methods.


title:
Referential Uncertainty and Word Learning in High-dimensional,
  Continuous Meaning Spaces

abstract:
  This paper discusses lexicon word learning in high-dimensional meaning spaces
from the viewpoint of referential uncertainty. We investigate various
state-of-the-art Machine Learning algorithms and discuss the impact of scaling,
representation and meaning space structure. We demonstrate that current Machine
Learning techniques successfully deal with high-dimensional meaning spaces. In
particular, we show that exponentially increasing dimensions linearly impact
learner performance and that referential uncertainty from word sensitivity has
no impact.


title: Kepler Observations of the Asteroseismic Binary HD 176465

abstract:
  Binary star systems are important for understanding stellar structure and
evolution, and are especially useful when oscillations can be detected and
analysed with asteroseismology. However, only four systems are known in which
solar-like oscillations are detected in both components. Here, we analyse the
fifth such system, HD 176465, which was observed by Kepler. We carefully
analysed the system's power spectrum to measure individual mode frequencies,
adapting our methods where necessary to accommodate the fact that both stars
oscillate in a similar frequency range. We also modelled the two stars
independently by fitting stellar models to the frequencies and complementary
parameters. We are able to cleanly separate the oscillation modes in both
systems. The stellar models produce compatible ages and initial compositions
for the stars, as is expected from their common and contemporaneous origin.
Combining the individual ages, the system is about 3.0$\pm$0.5 Gyr old. The two
components of HD 176465 are young physically-similar oscillating solar
analogues, the first such system to be found, and provide important constraints
for stellar evolution and asteroseismology.


title: Digitizing Municipal Street Inspections Using Computer Vision

abstract:
  "People want an authority to tell them how to value things. But they chose
this authority not based on facts or results. They chose it because it seems
authoritative and familiar." - The Big Short
  The pavement condition index is one such a familiar measure used by many US
cities to measure street quality and justify billions of dollars spent every
year on street repair. These billion-dollar decisions are based on evaluation
criteria that are subjective and not representative. In this paper, we build
upon our initial submission to D4GX 2015 that approaches this problem of
information asymmetry in municipal decision-making.
  We describe a process to identify street-defects using computer vision
techniques on data collected using the Street Quality Identification Device
(SQUID). A User Interface to host a large quantity of image data towards
digitizing the street inspection process and enabling actionable intelligence
for a core public service is also described. This approach of combining device,
data and decision-making around street repair enables cities make targeted
decisions about street repair and could lead to an anticipatory response which
can result in significant cost savings. Lastly, we share lessons learnt from
the deployment of SQUID in the city of Syracuse, NY.


title:
Magnon dispersion shift in the induced-ferromagnetic phase of the
  noncentrosymmetric MnSi

abstract:
  Small angle neutron inelastic scattering measurement has been performed to
study the magnon dispersion relation in the field-induced-ferromagnetic phase
of the noncentrosymmetric binary compound MnSi. For the magnons propagating
parallel or anti-parallel to the external magnetic field, we experimentally
confirmed that the dispersion relation is asymmetrically shifted along the
magnetic field direction. This magnon dispersion shift is attributed to the
relativistic Dzyaloshinskii-Moriya interaction, which is finite in
noncentrosymmetric magnets, such as MnSi. The shift direction is found to be
switchable by reversing the external magnetic field direction.


title: Self-testing in parallel with CHSH

abstract:
  Self-testing allows classical referees to verify the quantum behaviour of
some untrusted devices. Recently we developed a framework for building large
self-tests by repeating a smaller self-test many times in parallel. However,
the framework did not apply to the CHSH test, which tests a maximally entangled
pair of qubits. CHSH is the most well known and widely used test of this type.
Here we extend the parallel self-testing framework to build parallel CHSH
self-tests for any number of pairs of maximally entangled qubits. Our
construction achieves an error bound which is polynomial in the number of
tested qubit pairs.


title: Closed-Form Expressions for the n-Queens Problem and Related Problems

abstract:
  In this paper, we derive simple closed-form expressions for the $n$-queens
problem and three related problems in terms of permanents of $(0,1)$ matrices.
These formulas are the first of their kind. Moreover, they provide the first
method for solving these problems with polynomial space that has a nontrivial
time complexity bound. We then show how a closed-form for the number of Latin
squares of order $n$ follows from our method. Finally, we prove lower bounds.
In particular, we show that the permanent of Schur's complex valued matrix is a
lower bound for the toroidal semi-queens problem, or equivalently, the number
of transversals in a cyclic Latin square.


title: Some families of trees arising in permutation analysis

abstract:
  We extend classical results on simple varieties of trees (asymptotic
enumeration, average behavior of tree parameters) to trees counted by their
number of leaves. Motivated by genome comparison of related species, we then
apply these results to strong interval trees with a restriction on the arity of
prime nodes. Doing so, we describe a filtration of the set of permutations
based on their strong interval trees. This filtration is also studied from a
purely analytical point of view, thus illustrating the convergence of analytic
series towards a non-analytic limit at the level of the asymptotic behavior of
their coefficients.


title:
Constructions of invariants for surface-links via link invariants and
  applications to the Kauffman bracket

abstract:
  In this paper, we formulate a construction of ideal coset invariants for
surface-links in $4$-space using invariants for knots and links in $3$-space.
We apply the construction to the Kauffman bracket polynomial invariant and
obtain an invariant for surface-links called the Kauffman bracket ideal coset
invariant of surface-links. We also define a series of new invariants
$\{{\mathbf K}_{2n-1}(\mathcal L) | n=2, 3, 4, \ldots\}$ for surface-links
$\mathcal L$ by using skein relations, which are more effective than the
Kauffman bracket ideal coset invariant to distinguish given surface-links.


title:
One-Lee weight and two-Lee weight $\mathbb{Z}_2\mathbb{Z}_2[u]$-additive
  codes

abstract:
  In this paper, we study one-Lee weight and two-Lee weight codes over
$\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$, where $u^{2}=0$. Some properties of one-Lee
weight $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$-additive codes are given, and a
complete classification of one-Lee weight
$\mathbb{Z}_2\mathbb{Z}_2[u]$-additive formally self-dual codes is obtained.
The structure of two-Lee weight projective $\mathbb{Z}_2\mathbb{Z}_2[u]$ codes
is determined. Some optimal binary linear codes are obtained directly from
one-Lee weight and two-Lee weight $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$-additive
codes via the extended Gray map.


title:
Accurate Enthalpies of Formation of Astromolecules: Energy, Stability
  and Abundance

abstract:
  Accurate enthalpies of formation are reported for known and potential
astromolecules using high level ab initio quantum chemical calculations. A
total of 130 molecules comprising of 31 isomeric groups and 24
cyanide/isocyanide pairs with atoms ranging from 3 to 12 have been considered.
The results show an interesting, surprisingly not well explored, relationship
between energy, stability and abundance (ESA) existing among these molecules.
Among the isomeric species, isomers with lower enthalpies of formation are more
easily observed in the interstellar medium compared to their counterparts with
higher enthalpies of formation. Available data in literature confirm the high
abundance of the most stable isomer over other isomers in the different groups
considered. Potential for interstellar hydrogen bonding accounts for the few
exceptions observed. Thus, in general, it suffices to say that the interstellar
abundances of related species are directly proportional to their stabilities.
The immediate consequences of this relationship in addressing some of the whys
and wherefores among astromolecules and in predicting some possible candidates
for future astronomical observations are discussed. Our comprehensive results
on 130 molecules indicate that the available experimental enthalpy of formation
for some molecules, such as NaCN, may be less reliable and new measurements may
be needed.


title:
Exponential map and normal form for cornered asymptotically hyperbolic
  metrics

abstract:
  This paper considers asymptotically hyperbolic manifolds with a finite
boundary intersecting the usual infinite boundary -- cornered asymptotically
hyperbolic manifolds -- and proves a theorem of Cartan-Hadamard type near
infinity for the normal exponential map on the finite boundary. As a main
application, a normal form for such manifolds at the corner is then
constructed, analogous to the normal form for usual asymptotically hyperbolic
manifolds and suited to studying geometry at the corner. The normal form is at
the same time a submanifold normal form near the finite boundary and an
asymptotically hyperbolic normal form near the infinite boundary.


title: Stochastic Integral Operator Model for IS, US and WSSUS Channels

abstract:
  In this article, we proved that, under weak and natural requirements,
uncorrelated scattering (in particular WSSUS) channels can be modeled as
stochastic integrals. Moreover, if we assume (not only uncorrelated but also)
independent scattering, then the stochastic integral kernel is an additive
stochastic process. This allows us to decompose an IS channel into a sum of
independent channels; one deterministic, one with a Gaussian kernel, and two
others described by the Levy measure of the additive process.


title: A note on Iitaka's conjecture $C_{3,1}$ in positive characteristics

abstract:
  Let $f:X\to Y$ be a fibration from a smooth projective 3-fold to a smooth
projective curve, over an algebraically closed field $k$ of characteristic $p
>5$. We prove that if the generic fiber $X_{\eta}$ has big canonical divisor
$K_{X_{\eta}}$, then $$\kappa(X)\ge\kappa(Y) + \kappa(X_{\eta}).$$


abstract:
  A continuous-state polynomial branching process is constructed as the
pathwise unique solution of a stochastic integral equation with absorbing
boundary condition. The extinction and explosion probabilities and the mean
extinction and explosion times are computed explicitly, which are also new in
the classical branching case. We present necessary and sufficient conditions
for the process to extinguish or explode in finite times. In the critical or
subcritical case, we give a construction of the process coming down from
infinity. Finally, it is shown that the continuous-state polynomial branching
process arises naturally as the rescaled limit of a sequence of discrete-state
processes.


title: The value of timing information in event-triggered control

abstract:
  We study event-triggered control for stabilization of unstable linear plants
over rate-limited communication channels subject to unknown, bounded delay. On
one hand, the timing of event triggering carries implicit information about the
state of the plant. On the other hand, the delay in the communication channel
causes information loss, as it makes the state information available at the
controller out of date. Combining these two effects, we show a phase transition
behavior in the transmission rate required for stabilization using a given
event-triggering strategy. For small values of the delay, the timing
information carried by the triggering events is substantial, and the system can
be stabilized with any positive rate. When the delay exceeds a critical
threshold, the timing information alone is not enough to achieve stabilization
and the required rate grows. When the loss of information due to the
communication delay perfectly compensates the implicit information carried by
the triggering events, the delay equals the inverse of the entropy rate of the
plant, and we obtain the same rate requirement prescribed by the data-rate
theorem. When the delay is larger than this threshold, the required rate
becomes larger than that required by the data-rate theorem. We also provide an
explicit construction yielding a sufficient rate for stabilization, and
generalize our results to vector systems. The results do not rely on any a
priori probabilistic model of the delay or the initial conditions.


title:
Ground state structure of polymeric carbon monoxide with high energy
  density

abstract:
  Crystal structure prediction methods and first-principles calculations have
been used to explore low-energy structures of carbon monoxide (CO). Contrary to
the standard wisdom, the most stable structure of CO at ambient pressure was
found to be a polymeric structure of Pna21 symmetry rather than a molecular
solid. This phase is formed from six-membered (4 Carbon + 2 Oxygen) rings
connected by C=C double bonds with two double-bonded oxygen atoms attached to
each ring. Interestingly, the polymeric Pna21 phase of CO has a much higher
energy density than trinitrotoluene (TNT). On compression to about 7 GPa, Pna21
is found to transform into another chain-like phase of Cc symmetry which has
similar ring units to Pna21. On compression to 100 GPa it is energetically
favorable for CO to polymerize to form a single-bonded Cmcm phase from another
structure of Cmca symmetry composed of units similar to those found in the
single-bonded I212121 structure. Thermodynamic stability of these structures
was verified using calculations with different density functionals, including
hybrid and van der Waals corrected functionals.


title: Sparse Methods for Direction-of-Arrival Estimation

abstract:
  Direction-of-arrival (DOA) estimation refers to the process of retrieving the
direction information of several electromagnetic waves/sources from the outputs
of a number of receiving antennas that form a sensor array. DOA estimation is a
major problem in array signal processing and has wide applications in radar,
sonar, wireless communications, etc. With the development of sparse
representation and compressed sensing, the last decade has witnessed a
tremendous advance in this research topic. The purpose of this article is to
provide an overview of these sparse methods for DOA estimation, with a
particular highlight on the recently developed gridless sparse methods, e.g.,
those based on covariance fitting and the atomic norm. Several future research
directions are also discussed.


title: Social Computing for Mobile Big Data in Wireless Networks

abstract:
  Mobile big data contains vast statistical features in various dimensions,
including spatial, temporal, and the underlying social domain. Understanding
and exploiting the features of mobile data from a social network perspective
will be extremely beneficial to wireless networks, from planning, operation,
and maintenance to optimization and marketing. In this paper, we categorize and
analyze the big data collected from real wireless cellular networks. Then, we
study the social characteristics of mobile big data and highlight several
research directions for mobile big data in the social computing areas.


title:
Cylindrically Symmetric Ground State Solutions for Curl-Curl Equations
  with Critical Exponent

abstract:
  We study the following nonlinear critical curl-curl equation
\begin{equation}\label{eq0.1}\nabla\times \nabla\times U +V(x)U=|U|^{p-2}U+
|U|^4U,\quad x\in \mathbb{R}^3,\end{equation} where $V(x)=V(r, x_3)$ with
$r=\sqrt{x_1^2+x_2^2}$ is 1-periodic in $x_3$ direction and belongs to
$L^\infty(\R^3)$. When $0\not\in \sigma(-\Delta+\frac{1}{r^2}+V)$ and
$p\in(4,6)$, we prove the existence of nontrivial solution for (\ref{eq0.1}),
which is indeed a ground state solution in a suitable cylindrically symmetric
space. Especially, if $ \sigma(-\Delta+\frac{1}{r^2}+V)>0$, a ground state
solution is obtained for any $p\in(2,6)$.


title: Higher Dimensional Quasi-Power Theorem and Berry-Esseen Inequality

abstract:
  Hwang's quasi-power theorem asserts that a sequence of random variables whose
moment generating functions are approximately given by powers of some analytic
function is asymptotically normally distributed. This theorem is generalised to
higher dimensional random variables. To obtain this result, a higher
dimensional analogue of the Berry-Esseen inequality is proved, generalising a
two-dimensional version by Sadikova.


title:
Efficient quantum communications with multiplexed coherent state
  fingerprints

abstract:
  We provide the first example of a communication model and a distributed task,
for which there exists a realistic quantum protocol which is asymptotically
more efficient than any classical protocol, both in the communication and the
information resources. For this, we extend a recently proposed coherent state
mapping for quantum communication protocols, introduce the notion of
multiplexed coherent state fingerprints and show how to use them to design an
efficient quantum protocol for estimating the Euclidean distance of two real
vectors within a constant factor.


title: Biased Roulette Wheel: A Quantitative Trading Strategy Approach

abstract:
  The purpose of this research paper it is to present a new approach in the
framework of a biased roulette wheel. It is used the approach of a quantitative
trading strategy, commonly used in quantitative finance, in order to assess the
profitability of the strategy in the short term. The tools of backtesting and
walk-forward optimization were used to achieve such task. The data has been
generated from a real European roulette wheel from an on-line casino based in
Riga, Latvia. It has been recorded 10,980 spins and sent to the computer
through a voice-to-text software for further numerical analysis in R. It has
been observed that the probabilities of occurrence of the numbers at the
roulette wheel follows an Ornstein-Uhlenbeck process. Moreover, it is shown
that a flat betting system against Kelly Criterion was more profitable in the
short term.


title: Neural Ideals in SageMath

abstract:
  A major area in neuroscience research is the study of how the brain processes
spatial information. Neurons in the brain represent external stimuli via neural
codes. These codes often arise from stereotyped stimulus-response maps,
associating to each neuron a convex receptive field. An important problem
consists in determining what stimulus space features can be extracted directly
from a neural code. The neural ideal is an algebraic object that encodes the
full combinatorial data of a neural code. This ideal can be expressed in a
canonical form that directly translates to a minimal description of the
receptive field structure intrinsic to the code. In here, we describe a
SageMath package that contains several algorithms related to the canonical form
of a neural ideal.


title:
Application of the AAK theory for sparse approximation of exponential
  sums

abstract:
  In this paper, we derive a new method for optimal $\ell^{1}$- and
$\ell^2$-approximation of discrete signals on ${\mathbb N}_{0}$ whose entries
can be represented as an exponential sum of finite length. Our approach employs
Prony's method in a first step to recover the exponential sum that is
determined by the signal. In the second step we use the AAK-theory to derive an
algorithm for computing a shorter exponential sum that approximates the
original signal in the $\ell^{p}$-norm well. AAK-theory originally determines
best approximations of bounded periodic functions in Hardy-subspaces. We
rewrite these ideas for our purposes and give a proof of the used AAK theorem
based only on basic tools from linear algebra and Fourier analysis. The new
algorithm is tested numerically in different examples.


title:
Spontaneous Decoherence of Coupled Harmonic Oscillators Confined in A
  Ring

abstract:
  We study the spontaneous decoherence of the coupled harmonic oscillators
confined in a ring container, where the nearest-neighbor harmonic potentials
are taken into consideration. Without any external symmetry breaking field or
surrounding environment, the quantum superposition state prepared in the
relative degrees of freedom gradually loses its quantum coherence
spontaneously. This spontaneous decoherence is interpreted by the hidden
couplings between the center-of-mass and relative degrees of freedoms, which
actually originates from the symmetries of the ring geometry and corresponding
nontrivial boundary conditions. Especially, such spontaneous decoherence
completely vanishes at the thermodynamical limit because the nontrivial
boundary conditions become trivial Born-von Karman boundary conditions when the
perimeter of the ring container tends to infinity. Our investigation shows that
a thermal macroscopic object with certain symmetries has chance to degrade its
quantum properties even without applying an external symmetry breaking field or
surrounding environment.


title:
Event-triggered stabilization of coupled dynamical systems with fast
  Markovian switching

abstract:
  In this paper, stability of linearly coupled dynamical systems with feedback
pinning is studied. Event-triggered rules are employed on both diffusion
coupling and feedback pinning to reduce the updating load of the coupled
system. Here, both the coupling matrix and the set of pinned-nodes vary with
time are induced by a homogeneous Markov chain. For each node, the diffusion
coupling and feedback pinning are set up from the observation of its neighbors'
and target's (if pinned) information at the latest event time and the next
event time is triggered by some specified criteria. Two event-triggering rules
are proposed and it is proved that if the system with time-average coupling and
pinning gains are stable, the event-triggered strategies can stabilize the
system if the switching is sufficiently fast. Moreover, Zeno behaviors are
excluded in some cases. Finally, numerical examples are presented to illustrate
the theoretical results.


title:
Intrinsic non-adiabatic topological torque in magnetic skyrmions and
  vortices

abstract:
  We propose that topological spin currents flowing in topologically
non-trivial magnetic textures, such as magnetic skyrmions and vortices, produce
an intrinsic non-adiabatic torque of the form ${\bf T}_t\sim [(\partial_x{\bf
m}\times\partial_y{\bf m})\cdot{\bf m}]\partial_y{\bf m}$. We show that this
torque, which is absent in one-dimensional domain walls and/or non-topological
textures, is responsible for the enhanced non-adiabaticity parameter observed
in magnetic vortices compared to one-dimensional textures. The impact of this
torque on the motion of magnetic skyrmions is expected to be crucial,
especially to determine their robustness against defects and pinning centers.


title:
Conditional symmetries and exact solutions of nonlinear
  reaction-diffusion systems with non-constant diffusivities

abstract:
  Q-conditional symmetries (nonclassical symmetries) for the general class of
two-component reaction-diffusion systems with non-constant diffusivities are
studied. Using the recently introduced notion of Q-conditional symmetries of
the first type, an exhausted list of reaction-diffusion systems admitting such
symmetry is derived. The results obtained for the reaction-diffusion systems
are compared with those for the scalar reaction-diffusion equations. The
symmetries found for reducing reaction-diffusion systems to two-dimensional
dynamical systems, i.e., ODE systems, and finding exact solutions are applied.
As result, multiparameter families of exact solutions in the explicit form for
a nonlinear reaction-diffusion system with an arbitrary diffusivity are
constructed. Finally, the application of the exact solutions for solving a
biologically and physically motivated system is presented.


title:
The effect of neutron skin on inclusive prompt photon production in
  Pb~+~Pb collisions at the LHC

abstract:
  Recent experiments on lead (\textrm{$Pb_{82}^{208}$}) nuclei have observed
the celebrated phenomenon of neutron skin-thickness of low energy nuclear
physics. The skin-thickness provides a measure of extension of spatial
distribution of neutrons inside the atomic nucleus than protons. We have
studied the effect of neutron skin-thickness on inclusive prompt photon
production in Pb~+~Pb collisions at the Large Hadron Collider energies. We have
calculated the \textquoteleft central-to-peripheral ratio\textquoteright
($R_\textrm{cp}$) of prompt photon production with and without accounting for
neutron skin effect. The neutron skin causes a characteristic enhancement in
the ratio, in particular at forward rapidity, which is distinguishable in our
calculation. However a very precise direct photon measurement up to large
transverse momenta would be necessary to constrain the feature in experiment.


title: Perturbation to TBM mixing and its phenomenological implications

abstract:
  To accommodate the recently observed non-zero reactor mixing angle
$\theta_{13}$, we consider the lepton mixing matrix as Tri-bimaximal mixing
(TBM) form in the leading order along with a perturbation in neutrino sector.
The perturbation is taken to be a rotation in 23 plane followed by a rotation
in 13 plane, i.e., $R_{23}(\theta_{23}')R_{13}(\theta_{13}',\phi)$. We obtain
the allowed values of the parameters $\theta_{23}'$, $\theta_{13}'$ and $\phi$,
which can accommodate all the observed mixing angles consistently and calculate
the phenomenological observables such as the Dirac CP violating phase
($\delta_{CP}$), Jarlskog invariant ($J_{CP}$), effective majorana mass
$M_{ee}^{\nu}$, and $m_{\nu_e}$, the electron neutrino mass. We find that
$\delta_{CP}$ can take any values between $0$ and $-\pi/2$ and $M_{ee}^{\nu}$
always comes below its experimental upper limit.


title:
Optimal Operation of Stationary and Mobile Batteries in Distribution
  Grids

abstract:
  The trending integrations of Battery Energy Storage System (BESS, stationary
battery) and Electric Vehicles (EV, mobile battery) to distribution grids call
for advanced Demand Side Management (DSM) technique that addresses the
scalability concerns of the system and stochastic availabilities of EVs.
Towards this goal, a stochastic DSM is proposed to capture the uncertainties in
EVs. Numerical approximation is then used to make the problem tractable. To
accelerate the computational speed, the proposed DSM is tightly relaxed to a
convex form using second-order cone programming. Furthermore, in light of the
continuous increasing problem size, a distributed method with a guaranteed
convergence is applied to shift the centralized computational burden to
distributed controllers. To verify the proposed DSM, real-life EV data
collected on UCLA campus is used to test the proposed DSM in an IEEE benchmark
test system. Numerical results demonstrate the correctness and merits of the
proposed approach.


title: Relaxation decoupling in metallic glassy state

abstract:
  Upon cooling, glass-forming liquids experience a two-step relaxation
associated to the cage rattling and the escape from the cage, and the following
decoupling between the \b{eta}- and the {\alpha}-relaxations. The found
decoupling behaviors have greatly changed the face of glassy physics and
materials studies. Here we report a novel dynamic decoupling that the
relaxation function changes gradually from a single-step to a two-step form as
temperature declines through the stress relaxation of various metallic glasses
in a broad time and temperature range below glass transition temperature (Tg).
Such a two-step relaxation is unexpected in glassy state and reveals a
decoupling of dynamic modes arising from two different mechanisms: a faster one
exhibiting ballistic-like feature, and a slower one associated with a broader
distribution of relaxation times typical of subdiffusive atomic motion. This
first observation of two-step dynamics in metallic glassy state points to a far
richer-than-expected scenario for glass relaxation.


title: On the new LHC resonance

abstract:
  We present an alternative interpretation within the Standard Model of the new
LHC resonance at $125 \; GeV$. We further elaborate on our previous proposal
that the resonance at 125 GeV could be interpreted as a pseudoscalar meson with
quantum number $J^{PC} = 0^{- +}$. We develop a phenomenological approach where
this pseudoscalar mimics the decays of the Standard Model Higgs boson in the
vector boson decay channels. We propose that the true Higgs boson should be a
heavy resonance with mass of $750 \, GeV$ as argued in Ref.~\cite{Cea:2012}. We
determine the most relevant decay modes and estimate the partial decay widths
and branching ratios. We also discuss briefly the experimental signatures of
this heavy Higgs boson. Finally, we attempt a comparison of our theoretical
expectations with recent data at $\sqrt{s} =13 \,TeV$ from ATLAS and CMS
experiments in the so-called golden channel. We find that the available
experimental data could be consistent with the heavy Higgs scenario.


title:
Nonlinear reaction-diffusion systems with a non-constant diffusivity:
  conditional symmetries in no-go case

abstract:
  Q-conditional symmetries (nonclassical symmetries) for a general class of
two-component reaction-diffusion systems with non-constant diffusivities are
studied. The work is a natural continuation of our paper (Cherniha and
Davydovych, 2012) in order to extend the results on so-called no-go case. Using
the notion of Q-conditional symmetries of the first type, an exhaustive list of
reaction-diffusion systems admitting such symmetry is derived. The results
obtained are compared with those derived earlier. The symmetries for reducing
reaction-diffusion systems to two-dimensional dynamical systems (ODE systems)
and finding exact solutions are applied. As result, multiparameter families of
exact solutions in the explicit form for nonlinear reaction-diffusion systems
with an arbitrary power-law diffusivity are constructed and their properties
for possible applicability are established.


title:
Structural evolution in $A\approx 100$ nuclei within the mapped
  interacting boson model based on the Gogny energy density functional

abstract:
  The structure of even-even neutron-rich Ru, Mo, Zr and Sr nuclei in the
$A\approx 100$ mass region is studied within the interacting boson model (IBM)
with microscopic input from the self-consistent mean-field approximation based
on the Gogny-D1M energy density functional. The deformation energy surface in
the quadrupole deformation space $(\beta,\gamma)$, computed within the
constrained Hartree-Fock-Bogoliubov framework, is mapped onto the expectation
value of the appropriately chosen IBM Hamiltonian with configuration mixing in
the boson condensate state. The mapped IBM Hamiltonian is used to study the
spectroscopic properties of $^{98-114}$Ru, $^{96-112}$Mo, $^{94-110}$Zr and
$^{92-108}$Sr. Several cases of $\gamma$-soft behavior are predicted in Ru and
Mo nuclei while a pronounced coexistence between strongly-prolate and
weakly-oblate deformed shapes is found for Zr and Sr nuclei. The method
describes well the evolution of experimental yrast and non-yrast states as well
as selected $B$(E2) transition probabilities.


title:
Direct and inverse approximation theorems of $2\pi$-periodic functions
  by Taylor--Abel--Poisson means

abstract:
  We obtain direct and inverse approximation theorems of $2\pi$-periodic
functions by Taylor--Abel--Poisson operators in the integral metric.


title:
New Perspectives on Frontal Variability in the Southern Ocean Using a
  Local Identification Scheme

abstract:
  The frontal structure of the Southern Ocean is investigated using a
sophisticated frontal detection methodology, the Wavelet/Higher Order
Statistics Enhancement (WHOSE) method, introduced in \cite{Chapman2014}. This
methodology is applied to 21 years of daily gridded sea-surface height (SSH)
data to obtain daily maps of the locations of the fronts. By forming
`heat-maps' of the frontal occurrence frequency and then approximating these
heat-maps by a superposition of simple functions, the time-mean locations of
the fronts, as well as a measure of their capacity to meander, are obtained and
related to the frontal locations found by previous studies.
  The spatial and temporal variability of the frontal structure is then
considered. The number of fronts is found to be highly variable throughout the
Southern Ocean, increasing (`splitting') downstream of large bathymetric
features and decreasing (`merging') in regions where the fronts are tightly
controlled by the underlying topography. In contrast, frontal meandering
remains relatively constant. Contrary to many previous studies, little no
southward migration of the fronts over the 1993-2014 time period is found, and
there is only weak sensitivity to atmospheric forcing related to SAM or ENSO.
The reasons for the discrepancy between this study and previous studies using
contour methods are investigated and it is shown that the spatial variability
of the frontal structure is not tied to the underlying sea-surface height. It
is argued that the results of studies using sea-surface height contours to
define front must be interpreted with care.


title:
Maximal amenable MASAs of the free group factor of two generators
  arising from the free products of hyperfinite factors

abstract:
  In this paper, we give examples of maximal amenable subalgebras of the free
group factor of two generators. More precisely, we consider two copies of the
hyperfinite factor $R_i$ of type $\mathrm{II}_1$. From each $R_i$, we take a
Haar unitary $u_i$ which generates a Cartan subalgebra of it. We show that the
von Neumann subalgebra generated by the self-adjoint operator
$u_1+u_1^{-1}+u_2+u_2^{-1}$ is maximal amenable in the free product. This
provides infinitely many non-unitary conjugate maximal amenable MASAs.


title:
Nematicity, magnetism and superconductivity in FeSe under pressure:
  Unified explanation based on the self-consistent vertex correction theory

abstract:
  To understand the rich electronic phase diagram in FeSe under pressure that
vividly demonstrates the strong interplay between the nematicity, magnetism and
superconductivity, we analyze the electronic states by including the
higher-order many-body effects called the vertex correction (VC). We predict
the pressure-induced emergence of xy-orbital hole-pocket based on the
first-principles analysis. Due to this pressure-induced Lifshitz transition,
the spin fluctuations on the xy orbital are enhanced, whereas those on xz,yz
orbitals are gradually reduced. For this reason, nonmagnetic orbital order $O =
n_{xz} - n_{yz}$, which is driven by the spin fluctuations on xz,yz orbitals
through the intra-orbital VCs, is suppressed, and it is replaced with the
magnetism of xy-orbital d-electrons. The nodal s-wave state at ambient pressure
($O > 0$) and the enhancement of Tc under pressure are driven by the
cooperation between the spin and orbital fluctuations.


title: Big Data analytics. Three use cases with R, Python and Spark

abstract:
  Management and analysis of big data are systematically associated with a data
distributed architecture in the Hadoop and now Spark frameworks. This article
offers an introduction for statisticians to these technologies by comparing the
performance obtained by the direct use of three reference environments: R,
Python Scikit-learn, Spark MLlib on three public use cases: character
recognition, recommending films, categorizing products. As main result, it
appears that, if Spark is very efficient for data munging and recommendation by
collaborative filtering (non-negative factorization), current implementations
of conventional learning methods (logistic regression, random forests) in MLlib
or SparkML do not ou poorly compete habitual use of these methods (R, Python
Scikit-learn) in an integrated or undistributed architecture


title:
Integrated four-channel all-fiber up-conversion single-photon-detector
  with adjustable efficiency and dark count

abstract:
  Up-conversion single photon detector (UCSPD) has been widely used in many
research fields including quantum key distribution (QKD), lidar, optical time
domain reflectrometry (OTDR) and deep space communication. For the first time
in laboratory, we have developed an integrated four-channel all-fiber UCSPD
which can work in both free-running and gate modes. This compact module can
satisfy different experimental demands with adjustable detection efficiency and
dark count. We have characterized the key parameters of the UCSPD system.


title: Complementarity and light modes

abstract:
  In quantum physics we are confronted with new entities which consist
indivisible of an energy packet and a coupled wave. The complementarity
principle for certain properties of these quantum objects may be their main
mystery. Photons are especially useful to investigate these complementary
properties. A series of new experiments using spontaneous parametric down
conversion (SPDC) as a tool allowed the detailed analysis of the physical
background of this complementarity and offers a new conceptual perspective.
Based on these results a straightforward explanation of these sometimes
counter-intuitive effects is given.


title:
Inhibiting decoherence of two-level atom in thermal bath by presence of
  boundaries

abstract:
  We study, in the paradigm of open quantum systems, the dynamics of quantum
coherence of a static polarizable two-level atom which is coupled with a
thermal bath of fluctuating electromagnetic field in the absence and presence
of boundaries. The purpose is to find the conditions under which the
decoherence can be inhibited effectively. We find that without boundaries,
quantum coherence of the two-level atom inevitably decreases due to the effect
of thermal bath. However, the quantum decoherence, in the presence of a
boundary, could be effectively inhibited when the atom is transversely
polarizable and near this boundary. In particular, we find that in the case of
two parallel reflecting boundaries, the atom with a parallel dipole
polarization at arbitrary location between these two boundaries will be never
subjected to decoherence provided we take some special distances for the two
boundaries.


title: Reedy diagrams in symmetric monoidal model categories

abstract:
  Given a small category $I$ and a closed symmetric monoidal category $\mm$, we
show that the diagram category $\mm^I$ with the objectwise product is a closed
symmetric monoidal category. We then prove that if $I$ is a Reedy category and
$\mm$ has a model structure compatible with its product, then so is the Reedy
model structure on $\mm^I$ provided that $\mm$ is cofibrantly generated.


title: A model study of present-day Hall-effect circulators

abstract:
  Stimulated by the recent implementation of a three-port Hall-effect microwave
circulator of Mahoney et al. (MEA), we present model studies of the performance
of this device. Our calculations are based on the capacitive-coupling model of
Viola and DiVincenzo (VD). Based on conductance data from a typical Hall-bar
device obtained from a two-dimensional electron gas (2DEG) in a magnetic field,
we numerically solve the coupled field-circuit equations to calculate the
expected performance of the circulator, as determined by the $S$ parameters of
the device when coupled to 50$\Omega$ ports, as a function of frequency and
magnetic field. Above magnetic fields of 1.5T, for which a typical 2DEG enters
the quantum Hall regime (corresponding to a Landau-level filling fraction $\nu$
of 20), the Hall angle $\theta_H=\tan^{-1}\sigma_{xy}/\sigma_{xx}$ always
remains close to $90^\circ$, and the $S$ parameters are close to the analytic
predictions of VD for $\theta_H=\pi/2$. As anticipated by VD, MEA find the
device to have rather high (k$\Omega$) impedance, and thus to be extremely
mismatched to $50\Omega$, requiring the use of impedance matching. We
incorporate the lumped matching circuits of MEA in our modeling and confirm
that they can produce excellent circulation, although confined to a very small
bandwidth. We predict that this bandwidth is significantly improved by working
at lower magnetic field when the Landau index is high, e.g. $\nu=20$, and the
impedance mismatch is correspondingly less extreme. Our modeling also confirms
the observation of MEA that parasitic port-to-port capacitance can produce very
interesting countercirculation effects.


title: Transition formulas for involution Schubert polynomials

abstract:
  The orbits of the orthogonal and symplectic groups on the flag variety are in
bijection, respectively, with the involutions and fixed-point-free involutions
in the symmetric group $S_n$. Wyser and Yong have described polynomial
representatives for the cohomology classes of the closures of these orbits,
which we denote as $\hat{\mathfrak{S}}_y$ (to be called involution Schubert
polynomials) and $\hat{\mathfrak{S}}^{\tt FPF}_y$ (to be called
fixed-point-free involution Schubert polynomials). Our main results are
explicit formulas decomposing the product of $\hat{\mathfrak{S}}_y$
(respectively, $\hat{\mathfrak{S}}^{\tt FPF}_y$) with any $y$-invariant linear
polynomial as a linear combination of other involution Schubert polynomials.
These identities serve as analogues of Lascoux and Sch\"utzenberger's
transition formula for Schubert polynomials, and lead to a self-contained
algebraic proof of the nontrivial equivalence of several definitions of
$\hat{\mathfrak{S}}_y$ and $\hat{\mathfrak{S}}^{\tt FPF}_y$ appearing in the
literature. Our formulas also imply combinatorial identities about involution
words, certain variations of reduced words for involutions in $S_n$. We
construct operators on involution words based on the Little map to prove these
identities bijectively. The proofs of our main theorems depend on some new
technical results, extending work of Incitti, about covering relations in the
Bruhat order of $S_n$ restricted to involutions.


title: Saturn's Polar Atmosphere

abstract:
  This book chapter, Saturn's Polar Atmosphere, is to be published by Cambridge
University Press as part of a multi-volume work edited by Kevin Baines, Michael
Flasar, Norbert Krupp, and Thomas Stallard, entitled "Saturn in the 21st
Century." This chapter reviews the state of our knowledge about Saturn's polar
atmosphere that has been revealed through Earth- and space-based observation as
well as theoretical and numerical modeling. In particular, the Cassini mission
to Saturn, which has been in orbit around the ringed planet since 2004, has
revolutionized our understanding of the planet. The current review updates a
previous review by Del Genio et al (2009; Saturn Atmospheric Structure and
Dynamics, Chapter 7 of "Saturn from Cassini-Huygens"), written after Cassini's
primary mission phase that ended in 2008, by focusing on the north polar region
of Saturn and comparing it to the southern high latitudes. Two prominent
features in the northern high latitudes are the northern hexagon and the north
polar vortex; we extensively review observational and theoretical
investigations to date of both features. We also review the seasonal evolution
of the polar regions using the observational data accumulated during the
Cassini mission since 2004 (shortly after the northern winter solstice in
2002), through the equinox in 2009, and approaching the next solstice in 2017.
We conclude the current review by listing unanswered questions and describing
the observations of the polar regions planned for the Grand Finale phase of the
Cassini mission between 2016 and 2017.


title: Tunable erbium-doped microbubble laser fabricated by sol-gel coating

abstract:
  In this work, we show that the application of a sol-gel coating renders a
microbubble whispering gallery resonator into an active device. During the
fabrication of the resonator, a thin layer of erbium-doped sol-gel is applied
to a tapered microcapillary, then a microbubble with a wall thickness of 1.3
$\mu$m is formed with the rare earth diffused into its walls. The doped
microbubble is pumped at 980 nm and lasing in the emission band of the
Er$^{3+}$ ions with a wavelength of 1535 nm is observed. The laser wavelength
can be tuned by aerostatic pressure tuning of the whispering gallery modes of
the microbubble. Up to 240 pm tuning is observed with 2 bar of applied
pressure. It is shown that the doped microbubble could be used as a compact,
tunable laser source. The lasing microbubble can also be used to improve
sensing capabilities in optofluidic sensing applications.


title: Integral monodromy groups of Kloosterman sheaves

abstract:
  We show that integral monodromy groups of Kloosterman $\ell$-adic sheaves of
rank $n\ge 2$ on $\mathbb{G}_m/\mathbb{F}_q$ are as large as possible when the
characteristic $\ell$ is large enough, depending only on the rank. This variant
of Katz's results over $\mathbb{C}$ was known by works of Gabber, Larsen, Nori
and Hall under restrictions such as $\ell$ large enough depending on
$\operatorname{char}(\mathbb{F}_q)$ with an ineffective constant, which is
unsuitable for applications. We use the theory of finite groups of Lie type to
extend Katz's ideas, in particular the classification of maximal subgroups of
Aschbacher and Kleidman-Liebeck. These results will apply to study reductions
of hyper-Kloosterman sums in forthcoming work.


title: Algebraic cycles and Todorov surfaces

abstract:
  Motivated by the Bloch-Beilinson conjectures, Voisin has formulated a
conjecture about 0-cycles on self-products of surfaces of geometric genus one.
We verify Voisin's conjecture for the family of Todorov surfaces with $K^2=2$
and fundamental group $\mathbb{Z}/2\mathbb{Z}$. As a by-product, we prove that
certain Todorov surfaces have finite-dimensional motive.


title:
Nonequilibrium phase behaviour from minimization of free power
  dissipation

abstract:
  We develop a general theory for describing phase coexistence between
nonequilibrium steady states in Brownian systems, based on power functional
theory (M. Schmidt and J.M. Brader, J. Chem. Phys. 138, 214101 (2013)). We
apply the framework to the special case of fluid-fluid phase separation of
active soft sphere swimmers. The central object of the theory, the dissipated
free power, is calculated via computer simulations and compared to a simple
analytical approximation. The theory describes well the simulation data and
predicts motility-induced phase separation due to avoidance of dissipative
clusters.


title:
Cosmology with gamma-ray bursts: II Cosmography challenges and
  cosmological scenarios for the accelerated Universe

abstract:
  Context. Explaining the accelerated expansion of the Universe is one of the
fundamental challenges in physics today. Cosmography provides information about
the evolution of the universe derived from measured distances, assuming only
that the space time ge- ometry is described by the
Friedman-Lemaitre-Robertson-Walker metric, and adopting an approach that
effectively uses only Taylor expansions of basic observables. Aims. We perform
a high-redshift analysis to constrain the cosmographic expansion up to the
fifth order. It is based on the Union2 type Ia supernovae data set, the
gamma-ray burst Hubble diagram, a data set of 28 independent measurements of
the Hubble param- eter, baryon acoustic oscillations measurements from galaxy
clustering and the Lyman-{\alpha} forest in the SDSS-III Baryon Oscillation
Spectroscopic Survey (BOSS), and some Gaussian priors on h and {\Omega}M .
Methods. We performed a statistical analysis and explored the probability
distributions of the cosmographic parameters. By building up their regions of
confidence, we maximized our likelihood function using the Markov chain Monte
Carlo method. Results. Our high-redshift analysis confirms that the expansion
of the Universe currently accelerates; the estimation of the jerk parameter
indicates a possible deviation from the standard {\Lambda}CDM cosmological
model. Moreover, we investigate implications of our results for the
reconstruction of the dark energy equation of state (EOS) by comparing the
standard technique of cosmography with an alternative approach based on
generalized Pad\'e approximations of the same observables. Because these
expansions converge better, is possible to improve the constraints on the
cosmographic parameters and also on the dark matter EOS. Conclusions. The
estimation of the jerk and the DE parameters indicates at 1{\sigma} a possible
deviation from the {\Lambda}CDM cosmological model.


title: Matter-wave dark solitons in box-like traps

abstract:
  Motivated by the experimental development of quasi-homogeneous Bose-Einstein
condensates confined in box-like traps, we study numerically the dynamics of
dark solitons in such traps at zero temperature. We consider the cases where
the side walls of the box potential rise either as a power-law or a Gaussian.
While the soliton propagates through the homogeneous interior of the box
without dissipation, it typically dissipates energy during a reflection from a
wall through the emission of sound waves, causing a slight increase in the
soliton's speed. We characterise this energy loss as a function of the wall
parameters. Moreover, over multiple oscillations and reflections in the
box-like trap, the energy loss and speed increase of the soliton can be
significant, although the decay eventually becomes stabilized when the soliton
equilibrates with the ambient sound field.


title: Gaussian white noise as a resource for microscopic engines

abstract:
  We show that uncorrelated Gaussian noise, despite its paradigmatic
association with thermal equilibrium, can drive a system out of equilibrium and
can serve as a resource from which work can be extracted. We consider an
overdamped particle in a periodic potential with an internal degree of freedom
and a state-dependent friction, coupled to an equilibrium bath. Applying
additional Gaussian white noise drives the system into a non-equilibrium steady
state and causes a finite current if the potential is spatially asymmetric. We
calculate the current explicitly in the three complementary limits. Since the
particle current is driven solely by additive Gaussian white noise, this shows
that the latter can potentially be exploited as a work resource to power small
engines. By comparing the extracted power to the energy injection due to the
noise, we find an expression for the efficiency of such an engine.


title:
Bounds on the rate of convergence for inhomogeneous $M/M/S$ systems with
  either state-dependent transitions, or batch arrivals and service, or both

abstract:
  In this paper one presents method for the computation of convergence bounds
for four classes of multiserver queueing systems, described by inhomogeneous
Markov chains. Specifically one considers inhomogeneous $M/M/S$ queueing system
with possibly state-dependent arrival and service intensities and additionally
possible batch arrivals and batch service. The unified approach based on
logarithmic norm of linear operators for obtaining sharp upper and lower bounds
on the rate of convergence and corresponding sharp perturbation bounds is
described. As a side result, one shows by virtue of numerical examples that the
approach based on logarithmic norm can also be used for approximation of
limiting characteristics (idle probability and mean number of customers in the
system) of the considered systems with given approximation error. Extensive
numerical examples are provided.


title: Peculiar properties of Cr$_3$As$_3$-chain-based superconductors

abstract:
  $A_2$Cr$_3$As$_3$ ($A$ = K, Rb, Cs) are the unique Cr-based ambient-pressure
superconductors to date discovered by serendipity in 2015. The new
superconducting family are structurally characterized by quasi one-dimensional
[(Cr$_3$As$_3$)$^{2-}$]$_{\infty}$ double-walled subnanotubes, which exhibit
peculiar properties that mostly point to unconventional superconductivity. In
this conference paper, we first describe how the superconductors were
discovered. Then we overview the recent progresses on crystal structure,
electronic structures, theoretical models, and various physical properties in
$A_2$Cr$_3$As$_3$. Some new experimental results are included. Finally we
conclude by addressing the related open questions in this emerging subfield of
superconductivity.


title: Stochastic pure state representation for open quantum systems

abstract:
  We show that the usual master equation formalism of Markovian open quantum
systems is completely equivalent to a certain state vector formalism. The state
vector of the system satisfies a given frictional Schr\"odinger equation except
for random instant transitions of discrete nature. Hasse's frictional
Hamiltonian is recovered for the damped harmonic oscillator.


title:
A large deviation perspective on exponential decay of entropy and lower
  bounds on the Ricci-curvature

abstract:
  We offer a new point of view on the (Modified) Log-Sobolev inequality and
lower bounds on the Ricci-curvature in the setting where the dynamics are
obtained as the limit of Markov processes. In this setting, the large deviation
rate function of the stationary measures of the Markov processes, plays the
role of entropy. We define an entropy-information inequality (EII) that
generalizes the (MLSI) and is equivalent to exponential decay of the rate
function along the flow, and define an entropy-convexity inequality (ECI) that
serves as an analogue of a lower bound on the Ricci-curvature in this setting.


title:
Paternity testing and other inference about relationships from DNA
  mixtures

abstract:
  We present methods for inference about relationships between contributors to
a DNA mixture and other individuals of known genotype: a basic example would be
testing whether a contributor to a mixture is the father of a child of known
genotype. The evidence for such a relationship is evaluated as the likelihood
ratio for the specified relationship versus the alternative that there is no
such relationship. We analyse real casework examples from a criminal case and a
disputed paternity case; in both examples part of the evidence was from a DNA
mixture. DNA samples are of varying quality and therefore present challenging
problems in interpretation. Our methods are based on a recent statistical model
for DNA mixtures, in which a Bayesian network (BN) is used as a computational
device; the present work builds on that approach, but makes more explicit use
of the BN in the modelling. The R code for the analyses presented is freely
available as supplementary material.
  We show how additional information of specific genotypes relevant to the
relationship under analysis greatly strengthens the resulting inference. We
find that taking full account of the uncertainty inherent in a DNA mixture can
yield likelihood ratios very close to what one would obtain if we had a single
source DNA profile. Furthermore, the methods can be readily extended to analyse
different scenarios as our methods are not limited to the particular genotyping
kits used in the examples, to the allele frequency databases used, to the
numbers of contributors assumed, to the number of traces analysed
simultaneously, nor to the specific hypotheses tested.


title: Non-linear response in extended systems: a real-time approach

abstract:
  In this thesis we present a new formalism to study linear and non-linear
response in extended systems. Our approach is based on real-time solution of an
effective Schr\"odinger equation. The coupling between electrons and external
field is described by means of Modern Theory of Polarization. Correlation
effects are derived from Green's function theory. We show that the inclusion of
local-field effects and electron-hole interaction is crucial to predict and
reproduce second and third harmonic generation in low dimensional structures,
where strong bound excitons are present. Finally in the last part we introduce
a real-time density functional approach suitable for infinite periodic crystals
in which we work within the so-called length gauge and calculate the
polarisation as a dynamical Berry's phase. This approach, in addition to the
electron density considers also the macroscopic polarisation as a main variable
to correctly treat periodic crystals in presence of electric fields within a
density functional framework.


title: Nonlinear localized flatband modes with spin-orbit coupling

abstract:
  We report the coexistence and properties of stable compact localized states
(CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flatband
network with spin-orbit coupling (SOC). The system can be implemented by means
of a binary Bose-Einstein condensate loaded in the corresponding optical
lattice. In the linear limit, the SOC opens a minigap between flat and
dispersive bands in the system's bandgap structure, and preserves the existence
of CLSs at the flatband frequency, simultaneously lowering their symmetry.
Adding onsite cubic nonlinearity, the CLSs persist and remain available in an
exact analytical form, with frequencies which are smoothly tuned into the
minigap. Inside of the minigap, the CLS and DS families are stable in narrow
areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and
DSs are stable too.


title:
Classical understanding of the electron vortex beams in a uniform
  magnetic field

abstract:
  Recently interesting observations on electron vortex beams, which have
angular momentum about the center of the vortex beams, have been made. We have
shown that the basic features of the electron vortex beams in a uniform
magnetic field are understandable by using the classical motions of electrons.
We have constructed a classical vortex-like motion by the collective motion of
individual electrons in their cyclotron motions with a constant canonical
angular momentum in the symmetric gauge, which models electron vortex beams, in
a uniform magnetic field. With this model the various properties of circulating
currents and the relation between energy and kinetic angular momentum in the
electron vortex beams are well explained. We have also shown that the mismatch
between the centers of the electron vortex beam and the classical cyclotron
orbits naturally induces the parallel axis theorem and also the time-varying
kinetic angular momentum of the electron vortex beam for certain distributions
of classical electrons.


title: A CNN Cascade for Landmark Guided Semantic Part Segmentation

abstract:
  This paper proposes a CNN cascade for semantic part segmentation guided by
pose-specific information encoded in terms of a set of landmarks (or
keypoints). There is large amount of prior work on each of these tasks
separately, yet, to the best of our knowledge, this is the first time in
literature that the interplay between pose estimation and semantic part
segmentation is investigated. To address this limitation of prior work, in this
paper, we propose a CNN cascade of tasks that firstly performs landmark
localisation and then uses this information as input for guiding semantic part
segmentation. We applied our architecture to the problem of facial part
segmentation and report large performance improvement over the standard
unguided network on the most challenging face datasets. Testing code and models
will be published online at http://cs.nott.ac.uk/~psxasj/.


title:
A Near-Quadratic Lower Bound for the Size of Quantum Circuits of
  Constant Treewidth

abstract:
  We show that any quantum circuit of treewidth $t$, built from $r$-qubit
gates, requires at least $\Omega(\frac{n^{2}}{2^{O(r\cdot t)}\cdot \log^4 n})$
gates to compute the element distinctness function. Our result generalizes a
near-quadratic lower bound for quantum formula size obtained by Roychowdhury
and Vatan [SIAM J. on Computing, 2001]. The proof of our lower bound follows by
an extension of Ne\v{c}iporuk's method to the context of quantum circuits of
constant treewidth. This extension is made via a combination of techniques from
structural graph theory, tensor-network theory, and the connected-component
counting method, which is a classic tool in algebraic geometry.


title: Nanoscale imaging of current density with a single-spin magnetometer

abstract:
  Charge transport in nanostructures and thin films is fundamental to many
phenomena and processes in science and technology, ranging from quantum effects
and electronic correlations in mesoscopic physics, to integrated charge- or
spin-based electronic circuits, to photoactive layers in energy research.
Direct visualization of the charge flow in such structures is challenging due
to their nanometer size and the itinerant nature of currents. In this work, we
demonstrate non-invasive magnetic imaging of current density in two-dimensional
conductor networks including metallic nanowires and carbon nanotubes. Our
sensor is the electronic spin of a diamond nitrogen-vacancy center attached to
a scanning tip. Using a differential measurement technique, we detect DC
currents down to a few uA above a baseline current density of 2e4 A/cm2.
Reconstructed images have a spatial resolution of typically 50 nm, with a
best-effort value of 22 nm. Current density imaging offers a new route for
studying electronic transport and conductance variations in two-dimensional
materials and devices, with many exciting applications in condensed matter
physics.


title:
Excitonic gap formation and condensation in the bilayer graphene
  structure

abstract:
  We have studied the excitonic gap formation in the Bernal Stacked, bilayer
graphene (BLG) structures at half-filling. Considering the local Coulomb
interaction between the layers, we calculate the excitonic gap parameter and we
discuss the role of the interlayer and intralayer Coulomb interactions and the
interlayer hopping on the excitonic pair formation in the BLG. Particularly, we
predict the origin of excitonic gap formation and condensation, in relation to
the farthermost interband optical transition spectrum. The general diagram of
excitonic phase transition is given, explaining different interlayer
correlation regimes. The temperature dependence of the excitonic gap parameter
is shown and the role of the chemical potential, in the BLG, is discussed in
details.


title:
Nonlinear solution techniques for solving a Monge-Amp\`ere equation for
  redistribution of a mesh

abstract:
  A Monge-Amp\`ere (MA) equation arises when seeking an optimally transported
mesh that equidistributes a given monitor function in Cartesian space. This MA
equation is a fully nonlinear PDE, with a source term that is a function of the
gradient of the solution. This nonlinear source term is an additional
computational challenge that has received little attention from MA applications
in other fields. There are two major components needed to find a solution to
the MA equation: a spatial discretisation and an algorithm to find a solution
of the resulting nonlinear algebraic equations. There have been a number of
different approaches proposed in the literature to solve the MA equation but
none of which perform consistent comparisons across both algorithmic and
discretisation differences. In this study we explore different algorithmic
methods for the MA equation all within the context of a finite volume spatial
discretisation. We introduce a new linearisation of the MA equation that
neglects the nonlinearities arising from the source term and show that it leads
to a method that is fast, robust and free of tuning parameters. We present
numerical experiments that show methods based on this linearisation of the MA
equation are more computationally efficient than those that rely on other
techniques such as a parabolic relaxation. Further, the equations resulting
from a full linearisation of the MA equation, equivalent to using Newton's
method, can be seen as analogous to an advection-diffusion equation. This
allows many tools that exist for computational fluid dynamics to be re-factored
easily to solve the MA equation. The robustness and efficiency of the newly
introduced method gives hope that an adaptive solver for geophysical flows
using mesh redistribution can be computationally feasible in the near future.


title:
The ALMA detection of CO rotational line emission in AGB stars in the
  Large Magellanic Cloud

abstract:
  Context: Low- and intermediate-mass stars lose most of their stellar mass at
the end of their lives on the asymptotic giant branch (AGB). Determining gas
and dust mass-loss rates (MLRs) is important in quantifying the contribution of
evolved stars to the enrichment of the interstellar medium. Aims: Attempt to,
for the first time, spectrally resolve CO thermal line emission in a small
sample of AGB stars in the Large Magellanic Cloud. Methods: ALMA was used to
observe 2 OH/IR stars and 4 carbon stars in the LMC in the CO J= 2-1 line.
Results: We present the first measurement of expansion velocities in
extragalactic carbon stars. All four C-stars are detected and wind expansion
velocities and stellar velocities are directly measured. Mass-loss rates are
derived from modelling the spectral energy distribution and Spitzer/IRS
spectrum with the DUSTY code. Gas-to-dust ratios are derived that make the
predicted velocities agree with the observed ones. The expansion velocities and
MLRs are compared to a Galactic sample of well-studied relatively low MLRs
stars supplemented with "extreme" C-stars that have properties more similar to
the LMC targets. Gas MLRs derived from a simple formula are significantly
smaller than derived from the dust modelling, indicating an order of magnitude
underestimate of the estimated CO abundance, time-variable mass loss, or that
the CO intensities in LMC stars are lower than predicted by the formula derived
for Galactic objects. This could be related to a stronger interstellar
radiation field in the LMC. Conclusions: Although the LMC sample is small and
the comparison to Galactic stars is non-trivial because of uncertainties in
their distances it appears that for C stars the wind expansion velocities in
the LMC are lower than in the solar neighbourhood, while the MLRs appear
similar. This is in agreement with dynamical dust-driven wind models.


title: Separably injective $C_\sigma$-spaces

abstract:
  We show that a (complex) $C_\sigma$-space is separably injective if and only
if it is linearly isometric to the Banach space $C_0(\Omega)$ of complex
continuous functions vanishing at infinity on a substonean locally compact
Hausdorff space $\Omega$.


title:
Kiloparsec-scale dust disks in high-redshift luminous submillimeter
  galaxies

abstract:
  We present high-resolution (0.16$"$) 870um Atacama Large
Millimeter/submillimeter Array (ALMA) imaging of 16 luminous (L_IR ~ 4 x 10^12
L_sun) submillimeter galaxies (SMGs) from the ALESS survey of the Extended
Chandra Deep Field South. This dust imaging traces the dust-obscured star
formation in these z~2.5 galaxies on ~1.3 kpc scales. The emission has a median
effective radius of $R_e=0.24" \pm 0.02"$, corresponding to a typical physical
size of $R_{e}=1.8\pm$0.2 kpc. We derive a median S\'ersic index of
$n=0.9\pm0.2$, implying that the dust emission is remarkably disk-like at the
current resolution and sensitivity. We use different weighting schemes with the
visibilities to search for clumps on 0.12$"$ (~1.0 kpc) scales, but we find no
significant evidence for clumping in the majority of cases. Indeed, we
demonstrate using simulations that the observed morphologies are generally
consistent with smooth exponential disks, suggesting that caution should be
exercised when identifying candidate clumps in even moderate S/N
interferometric data. We compare our maps to comparable-resolution HST
H$_{160}$-band images, finding that the stellar morphologies appear
significantly more extended and disturbed, and suggesting that major mergers
may be responsible for driving the formation of the compact dust disks we
observe. The stark contrast between the obscured and unobscured morphologies
may also have implications for SED fitting routines that assume the dust is
co-located with the optical/near-IR continuum emission. Finally, we discuss the
potential of the current bursts of star formation to transform the observed
galaxy sizes and light profiles, showing that the $z\sim0$ descendants of these
SMGs are expected to have stellar masses, effective radii, and gas surface
densities consistent with the most compact massive (M_* ~ 1-2 x 10^11 M_sun)
early-type galaxies observed locally.


title:
Bulk-edge correspondence in nonunitary Floquet systems with chiral
  symmetry

abstract:
  We study topological phases in one-dimensional open Floquet systems driven by
chiral symmetric nonunitary time evolution. We derive a procedure to calculate
topological numbers from nonunitary time-evolution operators with chiral
symmetry. While the procedure has been applied to open Floquet systems
described by nonunitary time-evolution operators, we give the microscopic
foundation and clarify its validity for the first time. We construct a model of
chiral symmetric nonunitary quantum walks classified into class BDI$^\dagger$
or AIII, which is one of enlarged symmetry classes for topological phases in
open systems, based on experiments of discrete-time quantum walks. Then, we
confirm that the topological numbers obtained from the derived procedure give
correct predictions of the emergent edge states. We also show that the model
retains $\mathcal{PT}$ symmetry in certain cases and its dynamics is crucially
affected by the presence or absence of $\mathcal{PT}$ symmetry.


title: Spin-orbit coupling in a hexagonal ring of pendula

abstract:
  We consider the mechanical motion of a system of six macroscopic pendula
which are connected with springs and arranged in a hexagonal geometry. When the
springs are pre-tensioned, the coupling between neighbouring pendula along the
longitudinal (L) and the transverse (T) directions are different: identifying
the motion along the L and T directions as a spin-like degree of freedom, we
theoretically and experimentally verify that the pre-tensioned springs result
in a tunable spin-orbit coupling. We elucidate the structure of such a
spin-orbit coupling in the extended two-dimensional honeycomb lattice, making
connections to physics of graphene. The experimental frequencies and the
oscillation patterns of the eigenmodes for the hexagonal ring of pendula are
extracted from a spectral analysis of the motion of the pendula in response to
an external excitation and are found to be in good agreement with our
theoretical predictions. We anticipate that extending this classical analogue
of quantum mechanical spin-orbit coupling to two-dimensional lattices will lead
to exciting new topological phenomena in classical mechanics.