title:
Quenching a Quantum Critical State by the Order Parameter: Dynamical
  Quantum Phase Transitions and Quantum Speed Limits

abstract:
  Quantum critical states exhibit strong quantum fluctuations and are therefore
highly susceptible to perturbations. In this work we study the dynamical
stability against a sudden coupling to these strong fluctuations by quenching
the order parameter of the underlying transition. Such a quench can generate
superextensive energy fluctuations. This leads to a dynamical quantum phase
transition (DQPT) with nonanalytic real-time behavior in the resulting decay of
the initial state. By establishing a general connection between DQPTs and
quantum speed limits, this allows us to obtain a yet unrecognized quantum speed
limit with unconventional system size dependence. These findings are
illustrated for the one-dimensional and the infinitely-connected
transverse-field Ising model. The main concepts, however, are general and can
be applied also to other critical states. An outlook is given onto the
implications of the superextensive energy fluctuations on potential restricted
thermalization despite of nonintegrability.


title:
Discovery of a Substellar Companion to the Nearby Debris Disk Host HR
  2562

abstract:
  We present the discovery of a brown dwarf companion to the debris disk host
star HR 2562. This object, discovered with the Gemini Planet Imager (GPI), has
a projected separation of 20.3$\pm$0.3 au (0.618$\pm$0.004") from the star.
With the high astrometric precision afforded by GPI, we have confirmed common
proper motion of HR 2562B with the star with only a month time baseline between
observations to more than $5\sigma$. Spectral data in $J$, $H$, and $K$ bands
show morphological similarity to L/T transition objects. We assign a spectral
type of L7$\pm$3 to HR 2562B, and derive a luminosity of $\log$(L$_{\rm
bol}$/L$_{\odot}$)=-4.62$\pm$0.12, corresponding to a mass of 30$\pm$15 M$_{\rm
Jup}$ from evolutionary models at an estimated age of the system of 300-900
Myr. Although the uncertainty in the age of the host star is significant, the
spectra and photometry exhibit several indications of youth for HR 2562B. The
source has a position angle consistent with an orbit in the same plane as the
debris disk recently resolved with Herschel. Additionally, it appears to be
interior to the debris disk. Though the extent of the inner hole is currently
too uncertain to place limits on the mass of HR 2562B, future observations of
the disk with higher spatial resolution may be able to provide mass
constraints. This is the first brown dwarf-mass object found to reside in the
inner hole of a debris disk, offering the opportunity to search for evidence of
formation above the deuterium burning limit in a circumstellar disk.


title: Permutation graphs and unique games

abstract:
  We study the value of unique games as a graph-theoretic parameter. This is
obtained by labeling edges with permutations. We describe the classical value
of a game as well as give a necessary and sufficient condition for the
existence of an optimal assignment based on a generalisation of permutation
graphs and graph bundles. In considering some special cases, we relate XOR
games to EDGE BIPARTIZATION, and define an edge-labeling with permutations from
Latin squares.


title:
Search for gamma-ray emission from AE Aquarii with seven years of
  FERMI-LAT observations

abstract:
  AE Aquarii (AE Aqr) is a cataclysmic binary hosting one of the fastest
rotating (P$_{\rm spin}$ = 33.08 s) white dwarfs known. Based on seven years of
Fermi Large Area Telescope (LAT) Pass 8 data, we report on a deep search for
gamma-ray emission from AE Aqr. Using X-ray observations from ASCA, XMM-Newton,
Chandra, Swift, Suzaku, and NuSTAR, spanning 20 years, we substantially extend
and improve the spin ephemeris of AE Aqr. Using this ephemeris, we searched for
gamma-ray pulsations at the spin period of the white dwarf. No gamma-ray
pulsations were detected above 3 $\sigma$ significance. Neither phase-averaged
gamma-ray emission nor gamma-ray variability of AE Aquarii is detected by
Fermi-LAT. We impose the most restrictive upper limit to the gamma-ray flux
from AE Aqr to date: $1.3\times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ in the 100
MeV-300 GeV energy range, providing constraints on models.


title:
Efficient posterior inference on the volatility of a jump diffusion
  process

abstract:
  Jump diffusion processes are widely used to model asset prices over time,
mainly for their ability to capture complex discontinuous behavior, but
inference on the model parameters remains a challenge. Here our goal is
posterior inference on the volatility coefficient of the diffusion part of the
process based on discrete samples. A Bayesian approach requires specification
of a model for the jump part of the process, prior distributions for the
corresponding parameters, and computation of the joint posterior. Since the
volatility coefficient is our only interest, it would be desirable to avoid the
modeling and computational costs associated with the jump part of the process.
Towards this, we consider a {\em purposely misspecified model} that ignores the
jump part entirely. We work out precisely the asymptotic behavior of the
Bayesian posterior under the misspecified model, propose some simple
modifications to correct for the effects of misspecification, and demonstrate
that our modified posterior inference on the volatility is efficient in the
sense that its asymptotic variance equals the no-jumps model Cram\'er--Rao
bound.


title: Topic Grids for Homogeneous Data Visualization

abstract:
  We propose the topic grids to detect anomaly and analyze the behavior based
on the access log content. Content-based behavioral risk is quantified in the
high dimensional space where the topics are generated from the log. The topics
are being projected homogeneously into a space that is perception- and
interaction-friendly to the human experts.


title: Deep learning is competing random forest in computational docking

abstract:
  Computational docking is the core process of computer-aided drug design; it
aims at predicting the best orientation and conformation of a small drug
molecule when bound to a target large protein receptor. The docking quality is
typically measured by a scoring function: a mathematical predictive model that
produces a score representing the binding free energy and hence the stability
of the resulting complex molecule. We analyze the performance of both learning
techniques on the scoring power, the ranking power, docking power, and
screening power using the PDBbind 2013 database. For the scoring and ranking
powers, the proposed learning scoring functions depend on a wide range of
features (energy terms, pharmacophore, intermolecular) that entirely
characterize the protein-ligand complexes. For the docking and screening
powers, the proposed learning scoring functions depend on the intermolecular
features of the RF-Score to utilize a larger number of training complexes. For
the scoring power, the DL\_RF scoring function achieves Pearson's correlation
coefficient between the predicted and experimentally measured binding
affinities of 0.799 versus 0.758 of the RF scoring function. For the ranking
power, the DL scoring function ranks the ligands bound to fixed target protein
with accuracy 54% for the high-level ranking and with accuracy 78% for the
low-level ranking while the RF scoring function achieves (46% and 62%)
respectively. For the docking power, the DL\_RF scoring function has a success
rate when the three best-scored ligand binding poses are considered within 2
\AA\ root-mean-square-deviation from the native pose of 36.0% versus 30.2% of
the RF scoring function. For the screening power, the DL scoring function has
an average enrichment factor and success rate at the top 1% level of (2.69 and
6.45%) respectively versus (1.61 and 4.84%) respectively of the RF scoring
function.


title:
Synergistic Sorting, MultiSelection and Deferred Data Structures on
  MultiSets

abstract:
  Karp et al. (1988) described Deferred Data Structures for Multisets as "lazy"
data structures which partially sort data to support online rank and select
queries, with the minimum amount of work in the worst case over instances of
size $n$ and number of queries $q$ fixed (i.e., the query size). Barbay et al.
(2016) refined this approach to take advantage of the gaps between the
positions hit by the queries (i.e., the structure in the queries). We develop
new techniques in order to further refine this approach and to take advantage
all at once of the structure (i.e., the multiplicities of the elements), the
local order (i.e., the number and sizes of runs) and the global order (i.e.,
the number and positions of existing pivots) in the input; and of the structure
and order in the sequence of queries. Our main result is a synergistic deferred
data structure which performs much better on large classes of instances, while
performing always asymptotically as good as previous solutions. As intermediate
results, we describe two new synergistic sorting algorithms, which take
advantage of the structure and order (local and global) in the input, improving
upon previous results which take advantage only of the structure (Munro and
Spira 1979) or of the local order (Takaoka 1997) in the input; and one new
multiselection algorithm which takes advantage of not only the order and
structure in the input, but also of the structure in the queries. We described
two compressed data structures to represent a multiset taking advantage of both
the local order and structure, while supporting the operators rank and select
on the multiset.


title: Coauthorship and citation networks for statisticians: Comment

abstract:
  This is a comment on the paper arXiv:1410.2840 by Ji and Jin, to appear in
the AOAS.


title: Computerized Tomography with Total Variation and with Shearlets

abstract:
  To reduce the x-ray dose in computerized tomography (CT), many constrained
optimization approaches have been proposed aiming at minimizing a regularizing
function that measures lack of consistency with some prior knowledge about the
object that is being imaged, subject to a (predetermined) level of consistency
with the detected attenuation of x-rays. Proponents of the shearlet transform
in the regularizing function claim that the reconstructions so obtained are
better than those produced using TV for texture preservation (but may be worse
for noise reduction). In this paper we report results related to this claim. In
our reported experiments using simulated CT data collection of the head,
reconstructions whose shearlet transform has a small $\ell_1$-norm are not more
efficacious than reconstructions that have a small TV value. Our experiments
for making such comparisons use the recently-developed superiorization
methodology for both regularizing functions. Superiorization is an automated
procedure for turning an iterative algorithm for producing images that satisfy
a primary criterion (such as consistency with the observed measurements) into
its superiorized version that will produce results that, according to the
primary criterion are as good as those produced by the original algorithm, but
in addition are superior to them according to a secondary (regularizing)
criterion. The method presented for superiorization involving the $\ell_1$-norm
of the shearlet transform is novel and is quite general: It can be used for any
regularizing function that is defined as the $\ell_1$-norm of a transform
specified by the application of a matrix. Because in the previous literature
the split Bregman algorithm is used for similar purposes, a section is included
comparing the results of the superiorization algorithm with the split Bregman
algorithm.


title:
On Clustering and Embedding Mixture Manifolds using a Low Rank
  Neighborhood Approach

abstract:
  Samples from intimate (non-linear) mixtures are generally modeled as being
drawn from a smooth manifold. Scenarios where the data contains multiple
intimate mixtures with some constituent materials in common can be thought of
as manifolds which share a boundary. Two important steps in the processing of
such data are (i) to identify (cluster) the different mixture-manifolds present
in the data and (ii) to eliminate the non-linearities present the data by
mapping each mixture-manifold into some low-dimensional euclidean space
(embedding). Manifold clustering and embedding techniques appear to be an ideal
tool for this task, but the present state-of-the-art algorithms perform poorly
for hyperspectral data, particularly in the embedding task. We propose a novel
reconstruction-based algorithm for improved clustering and embedding of
mixture-manifolds. The algorithms attempts to reconstruct each target-point as
an affine combination of its nearest neighbors with an additional rank penalty
on the neighborhood to ensure that only neighbors on the same manifold as the
target-point are used in the reconstruction. The reconstruction matrix
generated by using this technique is block-diagonal and can be used for
clustering (using spectral clustering) and embedding. The improved performance
of the algorithms vis-a-vis its competitors is exhibited on a variety of
simulated and real mixture datasets.


title: Asymptotic stabilization of Betti diagrams of generic initial systems

abstract:
  Several authors investigating the asymptotic behaviour of the Betti diagrams
of the graded system obtained by taking powers of an ideal have shown that the
shape of the nonzero entries in the diagrams stabilizes when $I$ is a
homogeneous ideal with generators of the same degree. In this paper, we study
the Betti diagrams of graded systems of ideals built by taking the initial
ideals or generic initial ideals of powers, and discuss the stabilization of
additional collections of Betti diagrams. Our main result shows that when I has
generators of the same degree, the entries in the Betti diagrams of the reverse
lexicographic generic initial system are given asymptotically by polynomials
and that the shape of the diagrams stabilizes.


title:
Emergence of low noise \emph{frustrated} states in E/I balanced neural
  networks

abstract:
  We study emerging phenomena in binary neural networks where, with a
probability c synaptic intensities are chosen according with a Hebbian
prescription, and with probability (1-c) there is an extra random contribution
to synaptic weights. This new term, randomly taken from a Gaussian bimodal
distribution, balances the synaptic population in the network so that one has
80-20 relation in E/I population ratio, mimicking the balance observed in
mammals cortex. For some regions of the relevant parameters, our system depicts
standard memory (at low temperature) and non-memory attractors (at high
temperature). However, as c decreases and the level of the underlying noise
also decreases below a certain temperature T_t, a kind of memory-frustrated
state, which resembles spin-glass behavior, sharply emerges. Contrary to what
occurs in Hopfield-like neural networks, the frustrated state appears here even
in the limit of the loading parameter alpha-->0. Moreover, we observed that the
frustrated state in fact corresponds to two states of non-vanishing activity
uncorrelated with stored memories, associated, respectively, to a high activity
or Up state and to a low activity or Down state. Using a linear stability
analysis, we found regions in the space of relevant parameters for locally
stable steady states and demonstrated that frustrated states coexist with
memory attractors below T_t. Then, multistability between memory and frustrated
states is present for relatively small c, and metastability of memory
attractors can emerge as c decreases even more. We studied our system using
standard mean-field techniques and with Monte Carlo simulations, obtaining a
perfect agreement between theory and simulations. Our study can be useful to
...


title: MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri

abstract:
  We present a study of white light flares from the active M5.5 dwarf Proxima
Centauri using the Canadian microsatellite MOST. Using 37.6 days of monitoring
data from 2014 and 2015, we have detected 66 individual flare events, the
largest number of white light flares observed to date on Proxima Cen. Flare
energies in our sample range from $10^{29}$-$10^{31.5}$ erg. The flare rate is
lower than that of other classic flare stars of similar spectral type, such as
UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth.
Proxima Cen does have an unusually high flare rate given its slow rotation
period, however. Extending the observed power-law occurrence distribution down
to $10^{28}$ erg, we show that flares with flux amplitudes of 0.5% occur 63
times per day, while superflares with energies of $10^{33}$ erg occur ~8 times
per year. Small flares may therefore pose a great difficulty in searches for
transits from the recently announced 1.27 M_earth Proxima b, while frequent
large flares could have significant impact on the planetary atmosphere.


title:
Using Software-Defined Networking for Ransomware Mitigation: the Case of
  CryptoWall

abstract:
  Currently, different forms of ransomware are increasingly threatening
Internet users. Modern ransomware encrypts important user data and it is only
possible to recover it once a ransom has been paid. In this paper we show how
Software-Defined Networking (SDN) can be utilized to improve ransomware
mitigation. In more detail, we analyze the behavior of popular ransomware -
CryptoWall - and, based on this knowledge, we propose two real-time mitigation
methods. Then we designed the SDN-based system, implemented using OpenFlow,
which facilitates a timely reaction to this threat, and is a crucial factor in
the case of crypto ransomware. What is important is that such a design does not
significantly affect overall network performance. Experimental results confirm
that the proposed approach is feasible and efficient.


title: New quantum codes from dual-containing cyclic codes over finite rings

abstract:
  Let $R=\mathbb{F}_{2^{m}}+u\mathbb{F}_{2^{m}}+\cdots+u^{k}\mathbb{F}_{2^{m}}$
, where $\mathbb{F}_{2^{m}}$ is a finite field with $2^{m}$ elements, $m$ is a
positive integer, $u$ is an indeterminate with $u^{k+1}=0.$ In this paper, we
propose the constructions of two new families of quantum codes obtained from
dual-containing cyclic codes of odd length over $R$. A new Gray map over $R$ is
defined and a sufficient and necessary condition for the existence of
dual-containing cyclic codes over $R$ is given. A new family of $2^{m}$-ary
quantum codes is obtained via the Gray map and the Calderbank-Shor-Steane
construction from dual-containing cyclic codes over $R.$ Furthermore, a new
family of binary quantum codes is obtained via the Gray map, the trace map and
the Calderbank-Shor-Steane construction from dual-containing cyclic codes over
$R.$


title:
Systematic afterpulsing-estimation algorithms for gated avalanche
  photodiodes

abstract:
  We present a method designed to efficiently extract optical signals from
InGaAs avalanche photodiodes (APDs) operated in gated mode. In particular, our
method permits an estimation of the fraction of counts which actually results
from the signal being measured, as opposed to being produced by noise
mechanisms, specifically by afterpulsing. Our method in principle allows the
use of InGaAs APDs at high detection efficiencies, with the full operation
bandwidth, either with or without resorting to the application of a dead time.
As we show below, our method can be used in configurations where afterpulsing
exceeds the genuine signal by orders of magnitude, even near saturation. The
algorithms which we have developed are suitable to be used either in real-time
processing of raw detection probabilities or in post-processing applications,
after a calibration step has been performed. The algorithms which we propose
here can complement technologies designed for the reduction of afterpulsing.


title: Future Network: End-to-End Slicing and Hop-On (a Slice)

abstract:
  The concept of network slice, i.e.,a service customized virtual network (VN)
is attracting more and more attentions in the telecommunication industry. A
slice is a set of network resources which fits the service attributes and
requirements of customer services. The network resources consist of cloud
resources and communication link resources. A slice can serve one or more
customer services which share the similar service attributes and requirements.
To define, create and manage a slice (VN) is one aspect of future networks.
Another aspect is the slice operation, i.e., the provisioning of services to
customers using created slices. In this paper, the focus is put on the
configuration of slices and the operation of slices. In this paper, the
detailed description of slice (VN) configuration is provided. A new concept of
hop-on (a slice) is described. Given a well defined and configured end-to-end
slice (VN), the realtime data traffic delivery over a slice is governed by
network operation control entities, which are also pre-configured. Therefore,
the procedure of customer traffic delivery over a slice is just like a traveler
hopping on tourist bus and then the traffic control officers at key
intersections directing the traveler to go through pre-designed routes until
the destination is reached.


title:
The cost of not having a perfect reference in diagnostic accuracy
  studies: theoretical results and a web visualisation tool

abstract:
  Dichotomous diagnostic tests are widely used to detect the presence or
absence of a biomedical condition of interest. A rigorous evaluation of the
accuracy of a diagnostic test is critical to determine its practical value.
Performance measures, such as the sensitivity and specificity of the test,
should be estimated by comparison with a gold standard. Since an error-free
reference test is frequently missing, approaches based on available imperfect
diagnostic tests are used, namely: comparisons with an imperfect gold standard
or with a composite reference standard, discrepant analysis, and latent class
models.
  In this work, we compare these methods using a theoretical approach based on
analytical expressions for the deviations between the sensitivity and
specificity according to each method, and the corresponding true values. We
explore the impact on the deviations of varying conditions: tests sensitivities
and specificities, prevalence of the condition and local dependence between the
tests. An R interactive graphical application is made available for the
visualisation of the outcomes. Based on our findings, we discuss the methods
validity and potential usefulness.


title: More on some non-gaussian wave packets

abstract:
  We expand on a previous study, offering a generalized wave function
associated with the parabolic cylinder function and a connection with a
two-particle position-space wave function. We also provide an explicit formula
for a wave function associated with recent work by the present author and M.
Wolf.


title:
Non-destructive photon detection using a single rare earth ion coupled
  to a photonic cavity

abstract:
  We study the possibility of using single rare-earth ions coupled to a
photonic cavity with high cooperativity for performing non-destructive
measurements of photons, which would be useful for global quantum networks and
photonic quantum computing. We calculate the achievable fidelity as a function
of the parameters of the rare-earth ion and photonic cavity, which include the
ion's optical and spin dephasing rates, the cavity linewidth, the single photon
coupling to the cavity, and the detection efficiency. We suggest a promising
experimental realization using current state of the art technology in
Nd:YVO$_4$.


title: Dynamical Behavior for the Solutions of the Navier-Stokes Equation

abstract:
  We study the Cauchy problem for the incompressible Navier-Stokes equations
(NS) in three and higher spatial dimensions: \begin{align} u_t -\Delta u+u\cdot
\nabla u +\nabla p=0, \ \ {\rm div} u=0, \ \ u(0,x)= u_0(x). \label{NSa}
\end{align} Leray and Giga obtained that for the weak and mild solutions $u$ of
NS in $L^p(\mathbb{R}^d)$ which blow up at finite time $T>0$, respectively, one
has that for $d <p \leq \infty$, $$ \|u(t)\|_p \gtrsim ( T-t )^{-(1-d/p)/2}, \
\ 0< t<T. $$ We will obtain the blowup profile and the concentration phenomena
in $L^p(\mathbb{R}^d)$ with $d\leq p\leq \infty$ for the blowup mild solution.
On the other hand, if the Fourier support has the form ${\rm supp} \
\widehat{u_0} \subset \{\xi\in \mathbb{R}^n: \xi_1\geq L \}$ and
$\|u_0\|_{\infty} \ll L$ for some $L >0$, then \eqref{NSa} has a unique global
solution $u\in C(\mathbb{R}_+, L^\infty)$. Finally, if the blowup rate is of
type I: $$ \|u(t)\|_p \sim ( T-t )^{-(1-d/p)/2}, \ for \ 0< t<T<\infty, \
d<p<\infty $$ in 3 dimensional case, then we can obtain a minimal blowup
solution $\Phi$ for which $$ \inf \{\limsup_{t \to
T}(T-t)^{(1-3/p)/2}\|u(t)\|_{L^p_x}: \ u\in C([0,T); L^p) \mbox{\ solves
\eqref{NSa}}\} $$ is attainable at some $\Phi \in L^\infty (0,T; \ \dot
B^{-1+6/p}_{p/2,\infty})$.


title: Modulus-Pressure Equation for Confined Fluids

abstract:
  Ultrasonic experiments allow one to measure the elastic modulus of bulk solid
or fluid samples. Recently such experiments have been carried out on
fluid-saturated nanoporous glass to probe the modulus of a confined fluid. In
our previous work [J. Chem. Phys., (2015) 143, 194506], using Monte Carlo
simulations we showed that the elastic modulus $K$ of a fluid confined in a
mesopore is a function of the pore size. Here we focus on modulus-pressure
dependence $K(P)$, which is linear for bulk materials, a relation known as the
Tait-Murnaghan equation. Using transition-matrix Monte Carlo simulations we
calculated the elastic modulus of bulk argon as a function of pressure and
argon confined in silica mesopores as a function of Laplace pressure. Our
calculations show that while the elastic modulus is strongly affected by
confinement and temperature, the slope of the modulus versus pressure is not.
Moreover, the calculated slope is in a good agreement with the reference data
for bulk argon and experimental data for confined argon derived from ultrasonic
experiments. We propose to use the value of the slope of $K(P)$ to estimate the
elastic moduli of an unknown porous medium.


title:
Bayesian inference on dynamic linear models of day-to-day
  origin-destination flows in transportation networks

abstract:
  Estimation of origin-destination (OD) demand plays a key role in successful
transportation studies. In this paper, we consider the estimation of
time-varying day-to-day OD flows given data on traffic volumes in a
transportation network for a sequence of days. We propose a dynamic linear
model (DLM) in order to represent the stochastic evolution of OD flows over
time. DLM's are Bayesian state-space models which can capture non-stationarity.
We take into account the hierarchical relationships between the distribution of
OD flows among routes and the assignment of traffic volumes on links. Route
choice probabilities are obtained through a utility model based on past route
costs. We propose a Markov chain Monte Carlo algorithm, which integrates Gibbs
sampling and a forward filtering backward sampling technique, in order to
approximate the joint posterior distribution of mean OD flows and parameters of
the route choice model. Our approach can be applied to congested networks and
in the case when data are available on only a subset of links. We illustrate
the application of our approach through simulated experiments on a test network
from the literature.


title:
Crystallographic dependent transport properties and oxygen issue in
  superconducting LiTi2O4 thin films

abstract:
  A systematic study is performed on the spinel oxide, i.e. LiTi2O4 thin films
oriented along [111]-, [110]-, and [001]-directions, to reveal the
crystallographic dependence of transport properties. With decreasing
temperature, the LiTi2O4 displays roughly identical onset temperatures of
twofold symmetry of in-plane angular dependent magnetoresistivity (AMR) (at ~
100 K), crossover from negative- to positive- magnetoresistance (at ~ 50 K),
and coherence length in the superconducting state. While, the twofold symmetry
in AMR itself suggests anisotropic electron scattering. The superconducting
transition temperature (Tc) seems insensitive to the lattice parameter.
Moreover, the spherical aberration-corrected scanning transmission electron
microscopy (Cs-STEM) discloses that oxygen vacancies exist in the LiTi2O4
films. These oxygen vacancies cause the change of lattice but show little
influence on superconductivity, differing from high-Tc cuprates where subtle
variation of oxygen way lead to a significant change in superconductivity.


title: Parsec-scale jet properties of the quasar PG 1302$-$102

abstract:
  The quasar PG 1302$-$102 is believed to harbour a supermassive binary black
hole (SMBBH) system. Using the available 15 GHz and $2-8$ GHz, multi-epoch Very
Long Baseline Array data, we constrain the pc-scale jet properties based on the
inferred mean proper motion, including a bulk Lorentz factor $\geq 5.1 \pm
0.8$, jet inclination angle $\leq (11.4 \pm 1.7)$ degrees, projected position
angle $= 31.8$ degrees, intrinsic half opening angle $\leq (0.9 \pm 0.1)$
degrees and a mean $2-8$ GHz spectral index of 0.31. A general relativistic
helical jet model is presented and applied to predict quasi-periodic
oscillations of $\sim$ 10 days, power law power spectrum shape and a
contribution of up to $\sim$ 53 percent to the observed variable core flux
density. The model is used to make a case for high resolution, moderately
sampled, long duration radio interferometric observations to reveal signatures
due to helical knots and distinguish them from those due to SMBBH orbital
activity including a phase difference $\sim \pi$ and an amplitude ratio
(helical light curve amplitude/SMBBH light curve amplitude) of $0.2-3.3$. The
prescription can be used to identify helical kinematic signatures from quasars,
providing possible candidates for further studies with polarization
measurements. It can also be used to infer promising SMBBH candidates for the
study of gravitational waves if there are systematic deviations from helical
signatures.


title: Time Evolution of Galaxy Scaling Relations in Cosmological Simulations

abstract:
  We predict the evolution of galaxy scaling relationships from cosmological,
hydrodynamical simulations, that reproduce the scaling relations of present-day
galaxies. Although we do not assume co-evolution between galaxies and black
holes a priori, we are able to reproduce the black hole mass--velocity
dispersion relation. This relation does not evolve, and black holes actually
grow along the relation from significantly less massive seeds than have
previously been used. AGN feedback does not very much affect the chemical
evolution of our galaxies. In our predictions, the stellar mass--metallicity
relation does not change its shape, but the metallicity significantly increases
from $z\sim2$ to $z\sim1$, while the gas-phase mass-metallicity relation does
change shape, having a steeper slope at higher redshifts ($z\lesssim3$).
Furthermore, AGN feedback is required to reproduce observations of the most
massive galaxies at $z\lesssim1$, specifically their positions on the star
formation main sequence and galaxy mass--size relation.


title:
AlGaN Channel Field Effect Transistors with Graded Heterostructure Ohmic
  Contacts

abstract:
  We report on ultra-wide bandgap (UWBG) Al0.75Ga0.25N channel
metal-insulator-semiconductor field-effect transistors (MISFET) with
heterostructure engineered low-resistance ohmic contacts. The low intrinsic
electron affinity of AlN (0.6 eV) leads to large Schottky barriers at
metal-AlGaN interface, resulting in highly resistive ohmic contacts. In this
work, we use reverse compositional graded n++ AlGaN contact layer to achieve
upward electron affinity grading, leading to a low specific contact resistance
of 1.9x10-6 ohm.cm2 to n-Al0.75Ga0.25N channels (bandgap ~ 5.3 eV) with
non-alloyed contacts. We also demonstrate UWBG Al0.75Ga0.25N channel MISFET
device operation employing compositional graded n++ ohmic contact layer and 20
nm atomic layer deposited Al2O3 as the gate-dielectric.


title: Pure resolutions of unbounded complexes of modules

abstract:
  Let $R$ be a commutative ring. We show that pure injective resolutions and
pure projective resolutions can be constructed for unbounded complexes of
$R$-modules. We use these to obtain a closed symmetric monoidal structure on
the unbounded pure derived category.


title:
Two-dimensional atomic layer-molecule hybrid superconductors with
  controllable exchange coupling

abstract:
  The coexistence and competition of superconductivity and magnetism can lead
to a variety of rich physics and technological applications. Recent discovery
of atomic-layer superconductors and self-assembly of magnetic molecules on
solid surfaces should allow one to create a new two-dimensional (2D) hybrid
superconducting system, but its possibility has never been fully investigated
so far. Here we report the fabrication of highly ordered 2D hybrid
superconductors based on indium atomic layers on silicon surfaces and magnetic
metal-phthalocyanines (MPc) and clarify their detailed structural,
superconducting and magnetic properties. Our primary findings include a
substantial controllability of the superconducting transition temperatures (Tc)
through substitution of central metal ions (M = Cu, Fe, Mn) of the molecules.
This is attributed to charge transfers between the magnetic molecules and the
superconducting layers and to different degrees of exchange coupling between
them, which originates from anisotropic distributions of the relevant
d-orbitals. The present study opens a route for designing and creating exotic
2D superconductors with an atomic-scale precision.


title:
Properties of interstellar dust responsible for extinction laws with
  unusually low total-to-selective extinction ratios of Rv=1-2

abstract:
  It is well known that the extinction properties along lines of sight to Type
Ia supernovae are described by steep extinction curves with unusually low
total-to-selective extinction ratios of Rv = 1.0-2.0. In order to reveal the
properties of interstellar dust that causes such peculiar extinction laws, we
perform the fitting calculations to the measured extinction curves by applying
a two-component dust model composed of graphite and silicate. As for the size
distribution of grains, we consider two function forms of the power-law and
lognormal distributions. We find that the steep extinction curves derived from
the one-parameter formula by Cardelli et al. (1989) with Rv = 2.0, 1.5, and 1.0
can be reasonably explained even by the simple power-law dust model that has a
fixed power index of -3.5 with the maximum cut-off radii of a_{max} = 0.13 um,
0.094 um, and 0.057 um, respectively. These maximum cut-off radii are smaller
than a_{max} ~ 0.24 um considered to be valid in the Milky Way, clearly
demonstrating that the interstellar dust responsible for steep extinction
curves is highly biased to smaller sizes. We show that the lognomal size
distribution can also lead to good fits to the extinction curves with Rv =
1.0-3.1 by taking the appropriate combinations of the relevant parameters. We
discuss that the extinction data at ultraviolet wavelengths are essential for
constraining the composition and size distribution of interstellar dust.


title:
A Convolutional Neural Network Approach for Post-Processing in HEVC
  Intra Coding

abstract:
  Lossy image and video compression algorithms yield visually annoying
artifacts including blocking, blurring, and ringing, especially at low
bit-rates. To reduce these artifacts, post-processing techniques have been
extensively studied. Recently, inspired by the great success of convolutional
neural network (CNN) in computer vision, some researches were performed on
adopting CNN in post-processing, mostly for JPEG compressed images. In this
paper, we present a CNN-based post-processing algorithm for High Efficiency
Video Coding (HEVC), the state-of-the-art video coding standard. We redesign a
Variable-filter-size Residue-learning CNN (VRCNN) to improve the performance
and to accelerate network training. Experimental results show that using our
VRCNN as post-processing leads to on average 4.6% bit-rate reduction compared
to HEVC baseline. The VRCNN outperforms previously studied networks in
achieving higher bit-rate reduction, lower memory cost, and multiplied
computational speedup.


title:
Conversion Methods for Improving Structural Analysis of
  Differential-Algebraic Equation Systems

abstract:
  Differential-algebraic equation systems (DAEs) are generated routinely by
simulation and modeling environments. Before a simulation starts and a
numerical method is applied, some kind of structural analysis (SA) is used to
determine which equations to be differentiated, and how many times. Both
Pantelides's algorithm and Pryce's $\Sigma$-method are equivalent: if one of
them finds correct structural information, the other does also. Nonsingularity
of the Jacobian produced by SA indicates a success, which occurs on many
problems of interest. However, these methods can fail on simple, solvable DAEs
and give incorrect structural information including the index. This article
investigates $\Sigma$-method's failures and presents two conversion methods for
fixing them. Both methods convert a DAE on which the $\Sigma$-method fails to
an equivalent problem on which this SA is more likely to succeed.


title:
Scalar bosons under the influence of noninertial effects in the cosmic
  string spacetime

abstract:
  In this paper we present two different classes of solutions for the
Klein-Gordon equation in the presence of a scalar potential under the influence
of noninertial effects in the cosmic string spacetime. We show that noninertial
effects restrict the physical region of the spacetime where the particle can be
placed, and furthermore that the energy levels are shifted by these effects. In
addition, we show that the presence of a Coulomb-like scalar potential allows
the formation bound states when the Klein-Gordon equation is considered in this
kind of spacetime.


title:
Conversion Methods, Block Triangularization, and Structural Analysis of
  Differential-Algebraic Equation Systems

abstract:
  In a previous article, the authors developed two conversion methods to
improve the $\Sigma$-method for structural analysis (SA) of
differential-algebraic equations (DAEs). These methods reformulate a DAE on
which the $\Sigma$-method fails into an equivalent problem on which this SA is
more likely to succeed with a generically nonsingular Jacobian. The basic
version of these methods processes the DAE as a whole. This article presents
the block version that exploits block triangularization of a DAE. Using a block
triangular form of a Jacobian sparsity pattern, we identify which diagonal
blocks of the Jacobian are identically singular and then perform a conversion
on each such block. This approach improves the efficiency of finding a suitable
conversion for fixing SA's failures. All of our conversion methods can be
implemented in a computer algebra system so that every conversion can be
automated.


title: Study on the Idle Mode Capability with LoS and NLoS Transmissions

abstract:
  In this paper, we study the impact of the base station (BS) idle mode
capability (IMC) on the network performance in dense small cell networks
(SCNs). Different from existing works, we consider a sophisticated path loss
model incorporating both line-of-sight (LoS) and non-line-of-sight (NLoS)
transmissions. Analytical results are obtained for the coverage probability and
the area spectral efficiency (ASE) performance for SCNs with IMCs at the BSs.
The upper bound, the lower bound and the approximate expression of the
activated BS density are also derived. The performance impact of the IMC is
shown to be significant. As the BS density surpasses the UE density, thus
creating a surplus of BSs, the coverage probability will continuously increase
toward one. For the practical regime of the BS density, the results derived
from our analysis are distinctively different from existing results, and thus
shed new light on the deployment and the operation of future dense SCNs.


title:
$L_p$-norm regularization algorithms for optimization over permutation
  matrices

abstract:
  Optimization problems over permutation matrices appear widely in facility
layout, chip design, scheduling, pattern recognition, computer vision, graph
matching, etc. Since this problem is NP-hard due to the combinatorial nature of
permutation matrices, we relax the variable to be the more tractable doubly
stochastic matrices and add an $L_p$-norm ($0 < p < 1$) regularization term to
the objective function. The optimal solutions of the $L_p$-regularized problem
are the same as the original problem if the regularization parameter is
sufficiently large. A lower bound estimation of the nonzero entries of the
stationary points and some connections between the local minimizers and the
permutation matrices are further established. Then we propose an $L_p$
regularization algorithm with local refinements. The algorithm approximately
solves a sequence of $L_p$ regularization subproblems by the projected gradient
method using a nonmontone line search with the Barzilai-Borwein step sizes. Its
performance can be further improved if it is combined with certain local search
methods, the cutting plane techniques as well as a new negative proximal point
scheme. Extensive numerical results on QAPLIB and the bandwidth minimization
problem show that our proposed algorithms can often find reasonably high
quality solutions within a competitive amount of time.


title: Flexible Paxos: Quorum intersection revisited

abstract:
  Distributed consensus is integral to modern distributed systems. The widely
adopted Paxos algorithm uses two phases, each requiring majority agreement, to
reliably reach consensus. In this paper, we demonstrate that Paxos, which lies
at the foundation of many production systems, is conservative. Specifically, we
observe that each of the phases of Paxos may use non-intersecting quorums.
Majority quorums are not necessary as intersection is required only across
phases.
  Using this weakening of the requirements made in the original formulation, we
propose Flexible Paxos, which generalizes over the Paxos algorithm to provide
flexible quorums. We show that Flexible Paxos is safe, efficient and easy to
utilize in existing distributed systems. We conclude by discussing the wide
reaching implications of this result. Examples include improved availability
from reducing the size of second phase quorums by one when the number of
acceptors is even and utilizing small disjoint phase-2 quorums to speed up the
steady-state.


title:
Semantic descriptions of 24 evaluational adjectives, for application in
  sentiment analysis

abstract:
  We apply the Natural Semantic Metalanguage (NSM) approach (Goddard and
Wierzbicka 2014) to the lexical-semantic analysis of English evaluational
adjectives and compare the results with the picture developed in the Appraisal
Framework (Martin and White 2005). The analysis is corpus-assisted, with
examples mainly drawn from film and book reviews, and supported by
collocational and statistical information from WordBanks Online. We propose NSM
explications for 24 evaluational adjectives, arguing that they fall into five
groups, each of which corresponds to a distinct semantic template. The groups
can be sketched as follows: "First-person thought-plus-affect", e.g. wonderful;
"Experiential", e.g. entertaining; "Experiential with bodily reaction", e.g.
gripping; "Lasting impact", e.g. memorable; "Cognitive evaluation", e.g.
complex, excellent. These groupings and semantic templates are compared with
the classifications in the Appraisal Framework's system of Appreciation. In
addition, we are particularly interested in sentiment analysis, the automatic
identification of evaluation and subjectivity in text. We discuss the relevance
of the two frameworks for sentiment analysis and other language technology
applications.


title:
AKARI near-infrared spectroscopy of the extended green object
  G318.05+0.09: Detection of CO fundamental ro-vibrational emission

abstract:
  We present the results of near-infrared (2.5--5.4um) long-slit spectroscopy
of the extended green object (EGO) G318.05+0.09 with AKARI. Two distinct
sources are found in the slit. The brighter source has strong red continuum
emission with H2O ice, CO2 ice, and CO gas and ice absorption features at 3.0,
4.25um, 4.67um, respectively, while the other greenish object shows peculiar
emission that has double peaks at around 4.5 and 4.7um. The former source is
located close to the ultra compact HII region IRAS 14498-5856 and is identified
as an embedded massive young stellar object. The spectrum of the latter source
can be interpreted by blue-shifted (-3000 ~ -6000km/s) optically-thin emission
of the fundamental ro-vibrational transitions (v=1-0) of CO molecules with
temperatures of 12000--3700K without noticeable H2 and HI emission. We discuss
the nature of this source in terms of outflow associated with the young stellar
object and supernova ejecta associated with a supernova remnant.


title:
Stochastic Gravitational-Wave Background due to Primordial Binary Black
  Hole Mergers

abstract:
  Recent Advanced LIGO detections of binary black hole mergers have prompted
multiple studies investigating the possibility that the heavy GW150914 binary
system was of primordial origin, and hence could be evidence for dark matter in
the form of black holes. We compute the stochastic background arising from the
incoherent superposition of such primordial binary black hole systems in the
universe and compare it to the similar background spectrum due to binary black
hole systems of stellar origin. We investigate the possibility of detecting
this background with future gravitational wave detectors, and discuss the
possibility of using the stochastic gravitational-wave background measurement
to constrain the dark matter component in the form of black holes.


title:
Runge-Kutta discontinuous local evolution Galerkin methods for the
  shallow water equations on the cubed-sphere

abstract:
  The paper develops high order accurate Runge-Kutta discontinuous local
evolution Galerkin (RKDLEG) methods on the cubed-sphere grid for the shallow
water equations (SWEs). Instead of using the dimensional splitting method or
solving one-dimensional Riemann problem in the direction normal to the cell
interface, the RKDLEG methods are built on genuinely multi-dimensional
approximate local evolution operator of the locally linearized SWEs on a sphere
by considering all bicharacteristic directions. Several numerical experiments
are conducted to demonstrate the accuracy and performance of our RKDLEG
methods, in comparison to the Runge-Kutta discontinuous Galerkin method with
Godunov's flux etc.


title: Extended MHD turbulence and its applications to the solar wind

abstract:
  Extended MHD is a one-fluid model that incorporates two-fluid effects such as
electron inertia and the Hall drift. This model is used to construct fully
nonlinear Alfv\'enic wave solutions, and thereby derive the kinetic and
magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the
constant cascading rates of the energy and generalized helicities of this
model. The magnetic and kinetic spectra are derived in the ideal $\left(k <
1/\lambda_i\right)$, Hall $\left(1/\lambda_i < k < 1/\lambda_e \right)$, and
electron inertia $\left(k > 1/\lambda_e\right)$ regimes; $k$ is the wavenumber
and $\lambda_s = c/\omega_{p s}$ is the skin depth of species `$s$'. In the
Hall regime, it is shown that the emergent results are fully consistent with
previous numerical and analytical studies, especially in the context of the
solar wind. The focus is primarily on the electron inertia regime, where
magnetic energy spectra with power-law indexes of $-11/3$ and $-13/3$ are
always recovered. The latter, in particular, is quite close to recent
observational evidence from the solar wind with a potential slope of
approximately $-4$ in this regime. It is thus plausible that these spectra may
constitute a part of the (extended) inertial range, as opposed to the standard
`dissipation' range paradigm.


title:
Similarity indexing of exoplanets in search for potential habitability:
  application to Mars-like worlds

abstract:
  Study of exoplanets is one of the main goals of present research in planetary
sciences and astrobiology. Analysis of huge planetary data from space missions
such as CoRoT and Kepler is directed ultimately at finding a planet similar to
Earth -- the Earth's twin, and answering the question of potential
exo-habitability. The Earth Similarity Index (ESI) is a first step in this
quest, ranging from 1 (Earth) to 0 (totally dissimilar to Earth). It was
defined for the four physical parameters of a planet: radius, density, escape
velocity and surface temperature. The ESI is further sub-divided into interior
ESI (geometrical mean of radius and density) and surface ESI (geometrical mean
of escape velocity and surface temperature). The challenge here is to determine
which exoplanet parameter(s) is important in finding this similarity; how
exactly the individual parameters entering the interior ESI and surface ESI are
contributing to the global ESI. Since the surface temperature entering surface
ESI is a non-observable quantity, it is difficult to determine its value. Using
the known data for the Solar System objects, we established the calibration
relation between surface and equilibrium temperatures to devise an effective
way to estimate the value of the surface temperature of exoplanets for further
analysis with our graphic methodology.
  A new approach, called Mars Similarity Index (MSI), is introduced to identify
planets that may be habitable to the extreme forms of life. MSI is defined in
the range between 1 (present Mars) and 0 (dissimilar to present Mars) and uses
the same physical parameters as ESI. We are interested in Mars-like planets to
search for planets that may host the extreme life forms, such as the ones
living in extreme environments on Earth; for example, methane on Mars may be a
product of the methane-specific extremophile life form metabolism.


title:
Sub-dominant cogrowth behaviour and the viability of deciding
  amenability numerically

abstract:
  We critically analyse a recent numerical method due to the first author,
Rechnitzer and van Rensburg, which attempts to detect amenability or
non-amenability in a finitely generated group by numerically estimating its
asymptotic cogrowth rate. We identify two potential sources of error. We then
propose a modification of the method that enables it to easily compute
surprisingly accurate estimates for initial terms of the cogrowth sequence.


title:
The C--H Stretching Features at 3.2--3.5 Micrometer of Polycyclic
  Aromatic Hydrocarbons with Aliphatic Sidegroups

abstract:
  The so-called unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7,
8.6, and 11.3 micrometer are ubiquitously seen in a wide variety of
astrophysical regions. The UIE features are characteristic of the stretching
and bending vibrations of aromatic hydrocarbon materials, e.g., polycyclic
aromatic hydrocarbon (PAH) molecules. The 3.3 micrometer aromatic C--H
stretching feature is often accompanied by a weaker feature at 3.4 micrometer.
The latter is often thought to result from the C--H stretch of aliphatic groups
attached to the aromatic systems. The ratio of the observed intensity of the
3.3 micrometer aromatic C--H feature to that of the 3.4 micrometer aliphatic
C--H feature allows one to estimate the aliphatic fraction of the UIE carriers,
provided that the intrinsic oscillator strengths of the 3.3 micrometer aromatic
C--H stretch (A3.3) and the 3.4 micrometer aliphatic C--H stretch (A3.4) are
known. While previous studies on the aliphatic fraction of the UIE carriers
were mostly based on the A3.4/A3.3 ratios derived from the mono-methyl
derivatives of small PAH molecules, in this work we employ density functional
theory to compute the infrared vibrational spectra of several PAH molecules
with a wide range of sidegroups including ethyl, propyl, butyl, and several
unsaturated alkyl chains, as well as all the isomers of dimethyl-substituted
pyrene. We find that, except PAHs with unsaturated alkyl chains, the
corresponding A3.4/A3.3 ratios are close to that of mono-methyl PAHs. This
confirms the predominantly-aromatic nature of the UIE carriers previously
inferred from the A3.4/A3.3 ratio derived from mono-methyl PAHs.


title: On a problem of Hasse and Ramachandra

abstract:
  Let $K$ be an imaginary quadratic field, and let $\mathfrak{f}$ be a
nontrivial integral ideal of $K$. Hasse and Ramachandra asked whether the ray
class field of $K$ modulo $\mathfrak{f}$ can be generated by a single value of
the Weber function. We completely resolve this question when $\mathfrak{f}=(N)$
for an integer $N>1$.


title:
On the Aliphatic versus Aromatic Content of the Carriers of the
  "Unidentified" Infrared Emission Features

abstract:
  Although it is generally accepted that the so-called "unidentified" infrared
emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 micrometer are
characteristic of the stretching and bending vibrations of aromatic hydrocarbon
materials, the exact nature of their carriers remains unknown: whether they are
free-flying, predominantly aromatic gas-phase molecules, or amorphous solids
with a mixed aromatic/aliphatic composition are being debated. Recently, the
3.3 and 3.4 micrometer features which are commonly respectively attributed to
aromatic and aliphatic C-H stretches have been used to place an upper limit of
~2\% on the aliphatic fraction of the UIE carriers (i.e. the number of C atoms
in aliphatic chains to that in aromatic rings). Here we further explore the
aliphatic versus aromatic content of the UIE carriers by examining the ratio of
the observed intensity of the 6.2 micrometer aromatic C-C feature (I6.2) to
that of the 6.85 micrometer aliphatic C-H deformation feature (I6.85). To
derive the intrinsic oscillator strengths of the 6.2 micrometer stretch (A6.2)
and the 6.85 micrometer deformation (A6.85), we employ density functional
theory to compute the vibrational spectra of seven methylated polycyclic
aromatic hydrocarbon molecules and their cations. By comparing I6.85/I6.2 with
A6.85/A6.2, we derive the fraction of C atoms in methyl(ene) aliphatic form to
be at most ~10\%, confirming the earlier finding that the UIE emitters are
predominantly aromatic. We have also computed the intrinsic strength of the
7.25 micrometer feature (A7.25), another aliphatic C-H deformation band. We
find that A6.85 appreciably exceeds A7.25. This explains why the 6.85
micrometer feature is more frequently detected in space than the 7.25
micrometer feature.


title: Isotropy index for the connected sum and the direct product of manifolds

abstract:
  A subspace or subgroup is isotropic under a bilinear map if the restriction
of the map on it is trivial. We study maximal isotropic subspaces or subgroups
under skew-symmetric maps, and in particular the isotropy index---the maximum
dimension of an isotropic subspace or maximum rank of an isotropic subgroup.
For a smooth closed orientable manifold $M$, we describe the geometric meaning
of the isotropic subgroups of the first cohomology group with different
coefficients under the cup product. We calculate the corresponding isotropy
index, as well as the set of ranks of all maximal isotropic subgroups, for the
connected sum and the direct product of manifolds. Finally, we study the
relationship of the isotropy index with the first Betti number and the co-rank
of the fundamental group. We also discuss applications of these results to the
topology of foliations.


title: Normal bases for modular function fields

abstract:
  We provide a concrete example of a normal basis for a finite Galois extension
which is not abelian. More precisely, let $\mathbb{C}(X(N))$ be the field of
meromorphic functions on the modular curve $X(N)$ of level $N$. We construct a
completely free element in the extension $\mathbb{C}(X(N))/\mathbb{C}(X(1))$ by
means of Siegel functions.


title:
Computer-Aided Colorectal Tumor Classification in NBI Endoscopy Using
  CNN Features

abstract:
  In this paper we report results for recognizing colorectal NBI endoscopic
images by using features extracted from convolutional neural network (CNN). In
this comparative study, we extract features from different layers from
different CNN models, and then train linear SVM classifiers. Experimental
results with 10-fold cross validations show that features from first few
convolution layers are enough to achieve similar performance (i.e., recognition
rate of 95%) with non-CNN local features such as Bag-of-Visual words, Fisher
vector, and VLAD.


title:
Limitations of empirical sediment transport formulas for shallow water
  and their consequences for swash zone modelling

abstract:
  Volumetric sediment concentrations computed by phase-resolving swash
morphodynamic models are shown to exceed unity minus porosity (i.e. the maximal
physically possible concentration value) by up to factor of $10^5$ when using
standard expressions to compute the sediment transport rate. An ad hoc limit of
sediment concentration is introduced as a means to evaluate consequences of
exceeding physically realistic concentration by standard expressions. We find
that implementation of this ad hoc limit strongly changes the quantitative and
qualitative predictions of phase-resolving swash morphodynamic models,
suggesting that existing swash predictions are unreliable. This is because
standard expressions inappropriately consider or ignore the fact that the
shallow swash water depth limits the storage capacity of transported sediment.


title:
Studying the physics potential of long-baseline experiments in terms of
  new sensitivity parameters

abstract:
  We investigate physics opportunities to constraint leptonic CP-violation
phase $\delta_{CP}$ through numerical analysis of working neutrino oscillation
probability parameters, in the context of long base line experiments. Numerical
analysis of two parameters, the " transition probability $\delta_{CP}$ phase
sensitivity parameter ($A^M$) " and " CP-violation probability $\delta_{CP}$
phase sensitivity parameter ($A^{CP}$) ", as function of beam energy and/or
base line has been preferably carried out. It is an elegant technique to
broadly analyze different experiments to constraint $\delta_{CP}$ phase and
also to investigate mass hierarchy in the leptonic sector. The positive and
negative values of parameter $A^{CP}$ corresponding to either of hierarchy in
the specific beam energy ranges, could be a very promising way to explore mass
hierarchy and $\delta_{CP}$ phase. The keys to more robust bounds on
$\delta_{CP}$ phase are improvements of the involved detection techniques to
explore bit low energy and relatively long base line regions with better
experimental accuracy.


title: Double groupoid cohomology and extensions

abstract:
  We study extensions of double groupoids in the sense of \cite{AN2} and show
some classical results of group theory extensions in the case of double
groupoids. For it, given a double groupoid $(\mathcal{B};
\mathcal{V},\mathcal{H}; \mathcal{P})$ \emph{acting} on an abelian group bundle
$\mathbf{K} \to \mathcal{P}$, we introduce a cohomology double complex, in a
similar way as was done in \cite{AN2} and we show that the extensions of
$\mathcal{F}$ by $\mathbf{K}$ are classified by the total first cohomology
group of the associated total complex.
  With the aim to extend the above results to the topological setting,
following ideas of Deligne \cite{D} and Tu \cite{tu}, by means of simplicial
methods, we introduce a \emph{sheaf cohomology} for topological double
groupoids, generalizing the double groupoid cohomological in the discrete case,
and we carry out in the topological setting the results obtained for discrete
double groupoids.


title: Transfer Learning for Endoscopic Image Classification

abstract:
  In this paper we propose a method for transfer learning of endoscopic images.
For transferring between features obtained from images taken by different (old
and new) endoscopes, we extend the Max-Margin Domain Transfer (MMDT) proposed
by Hoffman et al. in order to use L2 distance constraints as regularization,
called Max-Margin Domain Transfer with L2 Distance Constraints (MMDTL2).
Furthermore, we develop the dual formulation of the optimization problem in
order to reduce the computation cost. Experimental results demonstrate that the
proposed MMDTL2 outperforms MMDT for real data sets taken by different
endoscopes.


title: Carbon Stars in the Satellites and Halo of M31

abstract:
  We spectroscopically identify a sample of carbon stars in the satellites and
halo of M31 using moderate-resolution optical spectroscopy from the
Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We
present the photometric properties of our sample of 41 stars, including their
brightness with respect to the tip of the red giant branch (TRGB) and their
distributions in various color-color spaces. This analysis reveals a bluer
population of carbon stars fainter than the TRGB and a redder population of
carbon stars brighter than the TRGB. We then apply principal component analysis
to determine the sample's eigenspectra and eigencoefficients. Correlating the
eigencoefficients with various observable properties reveals the spectral
features that trace effective temperature and metallicity. Putting the
spectroscopic and photometric information together, we find the carbon stars in
the satellites and halo of M31 to be minimally impacted by dust and internal
dynamics. We also find that while there is evidence to suggest that the
sub-TRGB stars are extrinsic in origin, it is also possible that they are are
particularly faint members of the asymptotic giant branch.


title: Understanding Band Gaps of Solids in Generalized Kohn-Sham Theory

abstract:
  The fundamental energy gap of a periodic solid distinguishes insulators from
metals and characterizes low-energy single-electron excitations. But the gap in
the band-structure of the exact multiplicative Kohn-Sham (KS) potential
substantially underestimates the fundamental gap, a major limitation of KS
density functional theory. Here we give a simple proof of a new theorem: In
generalized KS theory (GKS), the band gap of an extended system equals the
fundamental gap for the approximate functional if the GKS potential operator is
continuous and the density change is delocalized when an electron or hole is
added. Our theorem explains how GKS band gaps from meta-generalized gradient
approximations (meta-GGAs) and hybrid functionals can be more realistic than
those from GGAs or even from the exact KS potential. The theorem also follows
from earlier work. The band edges in the GKS one-electron spectrum are also
related to measurable energies. A linear chain of hydrogen molecules, solid
aluminum arsenide, and solid argon provide numerical illustrations.


title: A Novel Approach for Shot Boundary Detection in Videos

abstract:
  This paper presents a novel approach for video shot boundary detection. The
proposed approach is based on split and merge concept. A fisher linear
discriminant criterion is used to guide the process of both splitting and
merging. For the purpose of capturing the between class and within class
scatter we employ 2D2 FLD method which works on texture feature of regions in
each frame of a video. Further to reduce the complexity of the process we
propose to employ spectral clustering to group related regions together to a
single there by achieving reduction in dimension. The proposed method is
experimentally also validated on a cricket video. It is revealed that shots
obtained by the proposed approach are highly cohesive and loosely coupled


title:
Hybrid quantum magnetic field sensor with an electron spin and a nuclear
  spin in diamond

abstract:
  Recently, magnetic field sensors based on an electron spin of a nitrogen
vacancy (NV) center in diamond have been studied both from an experimental and
theoretical point of view. This system provides a nanoscale magnetometer, and
it is possible to detect a precession of a single spin. In this paper, we
propose a sensor consisting of an electron spin and a nuclear spin in diamond.
Although the electron spin has a reasonable interaction strength with magnetic
field, the coherence time of the spin is relatively short. On the other hand,
the nuclear spin has a longer life time while the spin has a negligible
interaction with magnetic fields. We show that, through the combination of such
two different spins via the hyperfine interaction, it is possible to construct
a magnetic field sensor with the sensitivity far beyond that of previous
sensors using just a single electron spin.


title: A Large-Scale Multilingual Disambiguation of Glosses

abstract:
  Linking concepts and named entities to knowledge bases has become a crucial
Natural Language Understanding task. In this respect, recent works have shown
the key advantage of exploiting textual definitions in various Natural Language
Processing applications. However, to date there are no reliable large-scale
corpora of sense-annotated textual definitions available to the research
community. In this paper we present a large-scale high-quality corpus of
disambiguated glosses in multiple languages, comprising sense annotations of
both concepts and named entities from a unified sense inventory. Our approach
for the construction and disambiguation of the corpus builds upon the structure
of a large multilingual semantic network and a state-of-the-art disambiguation
system; first, we gather complementary information of equivalent definitions
across different languages to provide context for disambiguation, and then we
combine it with a semantic similarity-based refinement. As a result we obtain a
multilingual corpus of textual definitions featuring over 38 million
definitions in 263 languages, and we make it freely available at
http://lcl.uniroma1.it/disambiguated-glosses. Experiments on Open Information
Extraction and Sense Clustering show how two state-of-the-art approaches
improve their performance by integrating our disambiguated corpus into their
pipeline.


title: Search for exoplanets and brown dwarfs with VLBI

abstract:
  The main aim of this work is to estimate possible radio GHz emission of
extrasolar planets and brown dwarfs and to check if such radiation can be
detected by Very Large Baseline Interferometers (VLBI). In the estimation we
assume that the emission may originate in processes similar to those observed
in the Jupiter system. The frequency of the radio emission that is produced in
this system depends mostly on the magnetic field strength. Jupiter's magnetic
field ($\sim 9$ G on average) allows for radiation from kHz frequencies up to
40 MHz. This is well below the frequency range of VLBI. However, it was
demonstrated that the magnetic field strength in massive and young object may
be up to two orders of magnitude higher than for Jupiter, which is especially
relevant for planets around short-lived A type stars. This should extend the
range of the emission up to GHz frequencies. We calculated expected flux
densities of radio emission for a variety of hypothetical young planetary
systems. We analysed two different emission scenarios, and found that the
radiation induced by moons (process similar to Jupiter-Io interactions) appears
to be less efficient than the emission generated by a stellar wind on a
planetary magnetosphere. We also estimated hypothetical emission of planets and
brown dwarfs located around relatively young and massive main sequence A-type
stars. Our results show that the emission produced by stellar winds could be
detected by currently operating VLBI networks.


title: Orthogonal projectors onto spaces of periodic splines

abstract:
  The main result of this paper is a proof that for any integrable function $f$
on the torus, any sequence of its orthogonal projections $(\widetilde{P}_n f)$
onto periodic spline spaces with arbitrary knots $\widetilde{\Delta}_n$ and
arbitrary polynomial degree converges to $f$ almost everywhere with respect to
the Lebesgue measure, provided the mesh diameter $|\widetilde{\Delta}_n|$ tends
to zero. We also give a proof of the fact that the operators $\widetilde{P}_n$
are bounded on $L^\infty$ independently of the knots $\widetilde{\Delta}_n$.


title:
A Newton multigrid method for steady-state shallow water equations with
  topography and dry areas

abstract:
  The paper develops a Newton multigrid (MG) method for one- and
two-dimensional steady-state shallow water equations (SWEs) with topography and
dry areas.It solves the nonlinear system arising from the well-balanced finite
volume discretization of the steady-state SWEs by using Newton's method as the
outer iteration and a geometric MG method with the block symmetric Gauss-Seidel
smoother as the inner iteration. The proposed Newton MG method makes use of the
local residual to regularize the Jacobian matrix of the Newton iteration, and
can handle the steady-state problem with wet/dry transitions. Several numerical
experiments are conducted to demonstrate the efficiency, robustness, and
well-balanced property of the proposed method. The relation between the
convergence behavior of the Newton MG method and the distribution of the
eigenvalues of the iteration matrix is detailedly discussed.


title: Wave Particle Duality, the Observer and Retrocausality

abstract:
  We approach wave particle duality, the role of the observer and implications
on Retrocausality, by starting with the results of a well verified quantum
experiment. We analyze how some current theoretical approaches interpret these
results. We then provide an alternative theoretical framework that is
consistent with the observations and in many ways simpler than usual attempts
to account for retrocausality, involving a non-local conscious Observer.


title: Probing Three-dimensional Collective Cancer Invasion with DIGME

abstract:
  Multicellular migration and pattern formation play important roles in
developmental biology, cancer metastasis and wound healing. To understand the
collective cell dynamics in three dimensional extracellular matrix (ECM), we
have developed a simple and mechanical-based strategy, Diskoid In Geometrically
Micropatterned ECM (DIGME). DIGME allows easy engineering of the shape of 3-D
tissue organoid, the mesoscale ECM heterogeneity, and the fiber alignment of
collagen-based ECM all at the same time. We have employed DIGME to study the
collective cancer invasion and find that DIGME provides a powerful tool to
probe three dimensional dynamics of tumor organoid in patterned
microenvironment.


title: On the Sensitivity Complexity of $k$-Uniform Hypergraph Properties

abstract:
  In this paper we investigate the sensitivity complexity of hypergraph
properties. We present a $k$-uniform hypergraph property with sensitivity
complexity $O(n^{\lceil k/3\rceil})$ for any $k\geq3$, where $n$ is the number
of vertices. Moreover, we can do better when $k\equiv1$ (mod 3) by presenting a
$k$-uniform hypergraph property with sensitivity $O(n^{\lceil k/3\rceil-1/2})$.
This result disproves a conjecture of Babai~\cite{Babai}, which conjectures
that the sensitivity complexity of $k$-uniform hypergraph properties is at
least $\Omega(n^{k/2})$. We also investigate the sensitivity complexity of
other symmetric functions and show that for many classes of transitive Boolean
functions the minimum achievable sensitivity complexity can be $O(N^{1/3})$,
where $N$ is the number of variables. Finally, we give a lower bound for
sensitivity of $k$-uniform hypergraph properties, which implies the {\em
sensitivity conjecture} of $k$-uniform hypergraph properties for any constant
$k$.


title: Collective strong coupling of cold potassium atoms in a ring cavity

abstract:
  We present experiments on ensemble cavity quantum electrodynamics with cold
potassium atoms in a high-finesse ring cavity. Potassium-39 atoms are cooled in
a two-dimensional magneto-optical trap and transferred to a three-dimensional
trap which intersects the cavity mode. The apparatus is described in detail and
the first observations of strong coupling with potassium atoms are presented.
Collective strong coupling of atoms and light is demonstrated via the splitting
of the cavity transmission spectrum and the avoided crossing of the normal
modes.


title:
Counting of Holomorphic Orbi-spheres in $\mathbb{P}^1_{2,2,2,2}$ and
  Determinant Equation

abstract:
  We count the number of holomorphic orbi-spheres in the
$\mathbb{Z}_2$-quotient of an elliptic curve. We first prove that there is an
explicit correspondence between the holomorphic orbi-spheres and the
sublattices of $\mathbb{Z} \oplus \mathbb{Z} \sqrt{-1} (\subset \mathbb{C})$.
The problem of counting sublattices of index $d$ then reduces to find the
number of integer solutions of the equation $\alpha \delta - \beta \gamma = d$
up to an equivalence.


title: Definable tree property can hold at all uncountable regular cardinals

abstract:
  Starting from a supercompact cardinal and a measurable above it, we construct
a model of ZFC in which definable tree property holds at all uncountable
regular cardinals. This answers a question from [1].


title:
Two more counterexamples to the infinite dimensional Carleson embedding
  theorem

abstract:
  The existence of a counterexample to the infinite-dimensional Carleson
embedding theorem has been established by Nazarov, Pisier, Treil, and Volberg.
We provide an explicit construction of such an example. We also obtain a
non-constructive example of particularly simple form; the density function of
the measure (with respect to a certain weighted area measure) is the
tensor-square of a Hilbert space-valued analytic function. This special
structure of the measure has implications for Hankel-like operators appearing
in control theory.


title: Completeness for a First-order Abstract Separation Logic

abstract:
  Existing work on theorem proving for the assertion language of separation
logic (SL) either focuses on abstract semantics which are not readily available
in most applications of program verification, or on concrete models for which
completeness is not possible. An important element in concrete SL is the
points-to predicate which denotes a singleton heap. SL with the points-to
predicate has been shown to be non-recursively enumerable. In this paper, we
develop a first-order SL, called FOASL, with an abstracted version of the
points-to predicate. We prove that FOASL is sound and complete with respect to
an abstract semantics, of which the standard SL semantics is an instance. We
also show that some reasoning principles involving the points-to predicate can
be approximated as FOASL theories, thus allowing our logic to be used for
reasoning about concrete program verification problems. We give some example
theories that are sound with respect to different variants of separation logics
from the literature, including those that are incompatible with Reynolds's
semantics. In the experiment we demonstrate our FOASL based theorem prover
which is able to handle a large fragment of separation logic with heap
semantics as well as non-standard semantics.


title:
Global well-posedness and scattering for small data for the 3-d KP-II
  Cauchy problem

abstract:
  We study global well-posedness for the Kadomtsev-Petviashvili II equation in
three space dimensions with small initial data. The crucial points are new
bilinear estimates and the definition of the function spaces. As by-product we
obtain that all solutions to small initial data scatter.


title: An x-ray quantum eraser setup for time-energy complementarity

abstract:
  A new quantum eraser setup exploiting for the first time the time-energy
complementarity relation in the x-ray regime is investigated theoretically.
Starting point is the interference process between x-ray quanta driving two
nuclear hyperfine transitions in a nuclear forward scattering setup. We show
that which-way information can be obtained by marking the scattering paths with
orthogonal polarization states, thus leading to the disappearance of the
interference pattern. In turn, erasure of the which-way information leads to
the reappearance of the interference fringes. We put forward two schemes using
resonant scattering off nuclear targets and design which-way marking procedures
to realize the quantum eraser setup for x-ray quanta.


title:
Measurement of the $D_s^+ \to \ell^+\nu_\ell$ branching fractions and
  the decay constant $f_{D_s^+}$

abstract:
  Using 482~pb$^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass
energy of $\sqrt{s} = 4.009$ GeV with the BESIII detector, we measure the
branching fractions of the decays $D_s^+\to\mu^+\nu_\mu$ and
$D_s^+\to\tau^+\nu_\tau$. By constraining the ratio of decay rates of $D_s^+$
to $\tau^+\nu_\tau$ and to $\mu^+\nu_\mu$ to the Standard Model prediction, the
branching fractions are determined to be $\mathcal{B}(D_s^+ \to \mu^+\nu_\mu) =
(0.495 \pm 0.067 \pm 0.026)\%$ and $\mathcal{B}(D_s^+ \to \tau^+\nu_\tau) =
(4.83 \pm 0.65 \pm 0.26)\%$. Using these branching fractions, we obtain a value
for the decay constant $f_{D_s^+}$ of $(241.0 \pm 16.3 \pm 6.5)~\text{MeV}$,
where the first error is statistical and the second systematic.


title: Emergent Geometric Frustration of Artificial Magnetic Skyrmion Crystals

abstract:
  Magnetic skyrmions have been receiving growing attention as potential
information storage and magnetic logic devices since an increasing number of
materials have been identified that support skyrmion phases. Explorations of
artificial frustrated systems have led to new insights into controlling and
engineering new emergent frustration phenomena in frustrated and disordered
systems. Here, we propose a skyrmion spin ice, giving a unifying framework for
the study of geometric frustration of skyrmion crystals in a non-frustrated
artificial geometrical lattice as a consequence of the structural confinement
of skyrmions in magnetic potential wells. The emergent ice rules from the
geometrically frustrated skyrmion crystals highlight a novel phenomenon in this
skyrmion system: emergent geometrical frustration. We demonstrate how skyrmion
crystal topology transitions between a non-frustrated periodic configuration
and a frustrated ice-like ordering can also be realized reversibly. The
proposed artificial frustrated skyrmion systems can be annealed into different
ice phases with an applied current induced spin-transfer torque, including a
long range ordered ice rule obeying ground state, as-relaxed random state,
biased state and monopole state. The spin-torque reconfigurability of the
artificial skyrmion ice states, difficult to achieve in other artificial spin
ice systems, is compatible with standard spintronic device fabrication
technology, which makes the semiconductor industrial integration
straightforward.


title: Abundance analysis of s-process enhanced barium stars

abstract:
  Detailed chemical composition studies of stars with enhanced abundances of
neutron-capture elements can provide observational constraints for
neutron-capture nucleosynthesis studies and clues for understanding their
contribution to the Galactic chemical enrichment. We present abundance results
from high-resolution spectral analyses of a sample of four chemically peculiar
stars characterized by s-process enhancement. High-Resolution spectra (R ~
42000) of these objects spanning a wavelength range from 4000 to 6800 A, are
taken from the ELODIE archive. We have estimated the stellar atmospheric
parameters, the effective temperature T_eff, the surface gravity log g, and
metallicity [Fe/H] from local thermodynamic equilibrium analysis using model
atmospheres. We report estimates of elemental abundances for several
neutron-capture elements, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu and Dy. While
HD 49641 and HD 58368 show [Ba/Fe] > 1.16 the other two objects HD 119650 and
HD 191010 are found to be mild barium stars with [Ba/Fe] ~ 0.4. The derived
abundances of the elements are interpreted on the basis of existing theories
for understanding their origin and evolution.


title: Star Formation and Gas Accretion in Nearby Galaxies

abstract:
  In order to quantify the relationship between gas accretion and star
formation, we analyse a sample of 29 nearby galaxies from the WHISP survey
which contains galaxies with and without evidence for recent gas accretion. We
compare combined radial profiles of FUV (GALEX) and IR 24 {\mu}m (Spitzer)
characterizing distributions of recent star formation with radial profiles of
CO (IRAM, BIMA, or CARMA) and HI (WSRT) tracing molecular and atomic gas
contents to examine star formation efficiencies in symmetric (quiescent),
asymmetric (accreting), and interacting (tidally disturbed) galaxies. In
addition, we investigate the relationship between star formation rate and HI in
the outer discs for the three groups of galaxies. We confirm the general
relationship between gas surface density and star formation surface density,
but do not find a significant difference between the three groups of galaxies.


title: Forecasting of time data with using fractional Brownian motion

abstract:
  We investigated the quality of forecasting of fractional Brownian motion, and
new method for estimating of Hurst exponent is validated. Stochastic model of
the time series in the form of converted fractional Brownian motion is
proposed. The method of checking the adequacy of the proposed model is
developed and short-term forecasting for temporary data is constructed. The
research results are implemented.in software tools for analysis and modeling of
time series.


title:
The Riemann Hypothesis: A Qualitative Characterization of the Nontrivial
  Zeros of the Riemann Zeta Function Using Polylogarithms

abstract:
  We formulate a parametrized uniformly absolutely globally convergent series
of $\zeta$(s) denoted by Z(s, x). When expressed in closed form, it is given by
Z(s, x) = (s -- 1)$\zeta$(s) + 1 x Li s z z -- 1 dz, where Li s (x) is the
polylogarithm function. As an immediate first application of the new
parametrized series, a new expression of $\zeta$(s) follows: (s -- 1)$\zeta$(s)
= -- 1 0 Li s z z -- 1 dz. As a second important application, using the
functional equation and exploiting uniform convergence of the series defining
Z(s, x), we have for any non-trivial zero s


title:
The Cramer-Wold theorem on quadratic surfaces and Heisenberg uniqueness
  pairs

abstract:
  Two measurable sets $S, \Lambda \subseteq \mathcal{R}^d$ form a Heisenberg
uniqueness pair, if every bounded measure $\mu$ with support in S whose Fourier
transform vanishes on {\Lambda} must be zero. We show that a quadratic
hypersurface and the union of two hyperplanes in general position form a
Heisenberg uniqueness pair in $\mathcal{R}^d$. As a corollary we obtain a new,
surprising version of the classical Cram\'er-Wold theorem: a bounded measure
supported on a quadratic hypersurface is uniquely determined by its projections
onto two generic hyperplanes (whereas an arbitrary measure requires the
knowledge of a dense set of projections). We also give an application to the
unique continuation of eigenfunctions of second-order PDEs with constant
coefficients .


title:
On the Hartle-Hawking-Israel states for spacetimes with static bifurcate
  Killing horizons

abstract:
  We revisit the construction by Sanders [S1] of the Hartle-Hawking-Israel
state for a free quantum Klein-Gordon field on a spacetime with a static,
bifurcate Killing horizon and a wedge reflection. Using the notion of the
Calder{\'o}n projector for elliptic boundary value problems and
pseudodifferential calculus on manifolds, we give a short proof of its Hadamard
property.


title:
Combining clustering of variables and feature selection using random
  forests

abstract:
  Standard approaches to tackle high-dimensional supervised classification
problem often include variable selection and dimension reduction procedures.
The novel methodology proposed in this paper combines clustering of variables
and feature selection. More precisely, hierarchical clustering of variables
procedure allows to build groups of correlated variables in order to reduce the
redundancy of information and summarizes each group by a synthetic numerical
variable. Originality is that the groups of variables (and the number of
groups) are unknown a priori. Moreover the clustering approach used can deal
with both numerical and categorical variables (i.e. mixed dataset). Among all
the possible partitions resulting from dendrogram cuts, the most relevant
synthetic variables (i.e. groups of variables) are selected with a variable
selection procedure using random forests. Numerical performances of the
proposed approach are compared with direct applications of random forests and
variable selection using random forests on the original p variables.
Improvements obtained with the proposed methodology are illustrated on two
simulated mixed datasets (cases n>p and n<p, where n is the sample size) and on
a real proteomic dataset. Via the selection of groups of variables (based on
the synthetic variables), interpretability of the results becomes easier.


title: Gauss-quadrature method for one-dimensional mean-field SDEs

abstract:
  Mean-field SDEs, also known as McKean-Vlasov equations, are stochastic
differential equations where the drift and diffusion depend on the current
distribution in addition to the current position. We describe an efficient
numerical method for approximating the distribution at time t of the solution
to the initial-value problem for one-dimensional mean-field SDEs. The idea is
to time march (e.g., using the Euler-Maruyama time-stepping method) an m-point
Gauss quadrature rule. With suitable regularity conditions, convergence with
first order is proved for Euler-Maruyama time stepping. We also estimate the
work needed to achieve a given accuracy in terms of the smoothness of the
underlying problem. Numerical experiments are given, which show the
effectiveness of this method as well as two second-order time-stepping methods.
The methods are also effective for ordinary SDEs in one dimension, as we
demonstrate by comparison with the multilevel Monte Carlo method.


title: $D$-modules and finite monodromy

abstract:
  We investigate an analogue of the Grothendieck $p$-curvature conjecture,
where the vanishing of the $p$-curvature is replaced by the stronger condition,
that the module with connection mod $p$ underlies a $\mathcal{D}_X$-module
structure. We show that this weaker conjecture holds in various situations, for
example if the underlying vector bundle is finite in the sense of Nori, or if
the connection underlies a $\mathbb{Z}$-variation of Hodge structure. We also
show isotriviality assuming a coprimality condition on certain mod $p$
Tannakian fundmental groups, which in particular resolves in the projective
case a conjecture of Matzat-van der Put. v2: the well known 4.2 has been added
to make the note self-contained.


title: Astheno-K\"ahler and balanced structures on fibrations

abstract:
  We study the existence of three classes of Hermitian metrics on certain types
of compact complex manifolds. More precisely, we consider balanced, SKT and
astheno-K\"ahler metrics. We prove that the twistor spaces of compact
hyperk\"ahler and negative quaternionic-K\"ahler manifolds do not admit
astheno-K\"ahler metrics. Then we provide examples of astheno-K\"ahler
structures on toric bundles over K\"ahler manifolds. In particular, we find
examples of compact complex non-K\"ahler manifolds which admit a balanced and
an astheno-K\"ahler metrics, thus answering to a question in [52] (see also
[24]). One of these examples is simply connected. We also show that the Lie
groups $SU(3)$ and $G_2$ admit SKT and astheno-K\"ahler metrics, which are
different. Furthermore, we investigate the existence of balanced metrics on
compact complex homogeneous spaces with an invariant volume form, showing in
particular that if a compact complex homogeneous space $M$ with invariant
volume admits a balanced metric, then its first Chern class $c_1(M)$ does not
vanish. Finally we characterize Wang C-spaces admitting SKT metrics.


title:
On non-K\"ahler compact complex manifolds with balanced and
  astheno-K\"ahler metrics

abstract:
  In this note we present, for every $n \geq 4$, a non-K\"ahler compact complex
manifold $X$ of complex dimension $n$ admitting a balanced metric and an
astheno-K\"ahler metric which is in addition $k$-th Gauduchon for any $1\leq
k\leq n-1$.


title:
Spatial distribution of low-energy plasma around comet 67P/CG from
  Rosetta measurements

abstract:
  We use measurements from the Rosetta plasma consortium (RPC) Langmuir probe
(LAP) and mutual impedance probe (MIP) to study the spatial distribution of
low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko.
The spatial distribution is highly structured with the highest density in the
summer hemisphere and above the region connecting the two main lobes of the
comet, i.e. the neck region. There is a clear correlation with the neutral
density and the plasma to neutral density ratio is found to be about 1-2x10^-6,
at a cometocentric distance of 10 km and at 3.1 AU from the sun. A clear 6.2 h
modulation of the plasma is seen as the neck is exposed twice per rotation. The
electron density of the collisonless plasma within 260 km from the nucleus
falls of with radial distance as about 1/r. The spatial structure indicates
that local ionization of neutral gas is the dominant source of low-energy
plasma around the comet.


title: Smooth models of singular $K3$-surfaces

abstract:
  We show that the classical Fermat quartic has exactly three smooth spatial
models. As a generalization, we give a classification of smooth spatial (as
well as some other) models of singular $K3$-surfaces of small discriminant. As
a by-product, we observe a correlation (up to a certain limit) between the
discriminant of a singular $K3$-surface and the number of lines in its models.
We also construct a $K3$-quartic surface with $52$ lines and singular points,
as well as a few other examples with many lines or models.


title: Cucker-Smale model with normalized communication weights and time delay

abstract:
  We study a Cucker-Smale-type system with time delay in which agents interact
with each other through normalized communication weights. We construct a
Lyapunov functional for the system and provide sufficient conditions for
asymptotic flocking, i.e., convergence to a common velocity vector. We also
carry out a rigorous limit passage to the mean-field limit of the particle
system as the number of particles tends to infinity.For the resulting
Vlasov-type equation we prove the existence, stability and large-time behavior
of measure-valued solutions. This is, to our best knowledge, the first such
result for a Vlasov-type equation with time delay. We also present numerical
simulations of the discrete system with few particles that provide further
insights into the flocking and oscillatory behaviors of the particle velocities
depending on the size of the time delay.


title: Quasi-Perfect Lee Codes from Quadratic Curves over Finite Fields

abstract:
  Golomb and Welch conjectured in 1970 that there only exist perfect Lee codes
for radius $t=1$ or dimension $n=1, 2$. It is admitted that the existence and
the construction of quasi-perfect Lee codes have to be studied since they are
the best alternative to the perfect codes. In this paper we firstly highlight
the relationships between subset sums, Cayley graphs, and Lee linear codes and
present some results. Next, we present a new constructive method for
constructing quasi-perfect Lee codes. Our approach uses subsets derived from
some quadratic curves over finite fields (in odd characteristic) to derive two
classes of $2$-quasi-perfect Lee codes are given over the space
$\mathbb{Z}_p^n$ for $n=\frac{p^k+1}{2}$ $(\text{with} ~p\equiv 1, -5 \mod 12
\text{and} k \text{is any integer}, \text{or} p\equiv -1, 5 \mod 12 \text{and}
k \text{is an even integer})$ and $n=\frac{p^k-1}{2}$ $(\text{with}p\equiv -1,
5 \mod 12, k \text{is an odd integer} \text{and} p^k>12)$, where $p$ is an odd
prime. Our codes encompass the quasi-perfect Lee codes constructed recently by
Camarero and Mart\'inez. Furthermore, we solve a conjecture proposed by
Camarero and Mart\'inez (in "quasi-perfect Lee codes of radius $2$ and
arbitrarily large dimension", IEEE Trans. Inf. Theory, vol. 62, no. 3, 2016) by
proving that the related Cayley graphs are Ramanujan or almost Ramanujan. The
Lee codes presented in this paper have applications to constrained and
partial-response channels, in flash memories and decision diagrams.


title: Load Coupling Power Optimization in Cloud Radio Access Networks

abstract:
  Recently, Cloud-based Radio Access Network (C-RAN) has been proposed as a
potential solution to reduce energy cost in cellular networks. C-RAN
centralizes the baseband processing capabilities of Base Stations (BSs) in a
cloud computing platform in the form of BaseBand Unit (BBU) pool. In C-RAN,
power consumed by the traditional BS system is distributed as wireless
transmission power of the Remote Radio Heads (RRHs) and baseband processing
power of the BBU pool. Different from previous work where wireless transmission
power and baseband processing power are optimized individually and
independently, this paper focuses on joint optimization of allocation for these
two kinds of power and attempts to minimize the total power consumption subject
to Quality of Service (QoS) requirements from users in terms of data rates.
First, we exploit the load coupling model to express the coupling relations
among power, load and user data rates. Based on the load coupling mode, we
formulate the joint power optimization problem in C-RAN over both wireless
transmission power and baseband processing power. Second, we prove that
operating at full load may not be optimal in minimizing the total power
consumption in C-RAN. Finally, we propose an efficient iterative algorithm to
solve the target problem. Simulations have been performed to validate our
theoretical and algorithmic work. The results show that the proposed algorithm
outperforms existing schemes (without joint power optimization) in terms of
power consumption.


title: Qualitative dynamics of wavepackets in turbulent jets

abstract:
  It has long been established that turbulent jets comprise large-scale
coherent structures, now more commonly referred to as "wavepackets". These
structures exhibit a remarkable spatio-temporal organisation, despite
turbulence.
  In this work we analyse, from a qualitative point of view, the temporal
dynamics of axisymmetric wavepackets educed, experimentally, from subsonic
iso-thermal jets. We use the data presented by, where time-series of the
wavepackets are extracted at different streamwise locations. A thorough
analysis is performed, statistical tools are used for estimating the embedding
and correlation dimensions characterising the dynamical system. System
identification is used for computing nonlinear surrogate models. Finally,
control-oriented linear models are computed.
  The goal of the contribution is to assess the extent to which non-linear
models are necessary, or appropriate, for description of the temporal
wave-packet dynamics and to provide a complementary perspective to the current
modelling.


title:
Engineering quantum spin Hall insulators by strained-layer
  heterostructures

abstract:
  Quantum spin Hall insulators (QSHIs), also known as two-dimensional
topological insulators, have emerged as an unconventional class of quantum
states with insulating bulk and conducting edges originating from nontrivial
inverted band structures, and have been proposed as a platform for exploring
spintronics applications and exotic quasiparticles related to the spin-helical
edge modes. Despite theoretical proposals for various materials, however,
experimental demonstrations of QSHIs have so far been limited to two
systems--HgTe/CdTe and InAs/GaSb--both of which are lattice-matched
semiconductor heterostructures. Here we report transport measurements in yet
another realization of a band-inverted heterostructure as a QSHI
candidate--InAs/In$_{x}$Ga$_{1-x}$Sb with lattice mismatch. We show that the
compressive strain in the In$_{x}$Ga$_{1-x}$Sb layer enhances the band overlap
and energy gap. Consequently, high bulk resistivity, two orders of magnitude
higher than for InAs/GaSb, is obtained deep in the band-inverted regime. The
strain also enhances bulk Rashba spin-orbit splitting, leading to an unusual
situation where the Fermi level crosses only one spin branch for electronlike
and holelike bands over a wide density range. These properties make this system
a promising platform for robust QSHIs with unique spin properties and
demonstrate strain to be an important ingredient for tuning spin-orbit
interaction.


title: The 2nd Generation VLTI path to performance

abstract:
  The upgrade of the VLTI infrastructure for the 2nd generation instruments is
now complete with the transformation of the laboratory, and installation of
star separators on both the 1.8-m Auxiliary Telescopes (ATs) and the 8-m Unit
Telescopes (UTs). The Gravity fringe tracker has had a full semester of
commissioning on the ATs, and a first look at the UTs. The CIAO infrared
wavefront sensor is about to demonstrate its performance relative to the
visible wavefront sensor MACAO. First astrometric measurements on the ATs and
astrometric qualification of the UTs are on-going. Now is a good time to
revisit the performance roadmap for VLTI that was initiated in 2014, which
aimed at coherently driving the developments of the interferometer, and
especially its performance, in support to the new generation of instruments:
Gravity and MATISSE.


title:
On the Correctness of Inverted Index Based Public-Key Searchable
  Encryption Scheme for Multi-time Search

abstract:
  In this short note we argue that the state-of-art inverted index based public
key searchable encryption scheme proposed by Wang et al may not be completely
correct by giving a counterexample.