title: Lensless Imaging with Compressive Ultrafast Sensing

abstract:
  Lensless imaging is an important and challenging problem. One notable
solution to lensless imaging is a single pixel camera which benefits from ideas
central to compressive sampling. However, traditional single pixel cameras
require many illumination patterns which result in a long acquisition process.
Here we present a method for lensless imaging based on compressive ultrafast
sensing. Each sensor acquisition is encoded with a different illumination
pattern and produces a time series where time is a function of the photon's
origin in the scene. Currently available hardware with picosecond time
resolution enables time tagging photons as they arrive to an omnidirectional
sensor. This allows lensless imaging with significantly fewer patterns compared
to regular single pixel imaging. To that end, we develop a framework for
designing lensless imaging systems that use ultrafast detectors. We provide an
algorithm for ideal sensor placement and an algorithm for optimized active
illumination patterns. We show that efficient lensless imaging is possible with
ultrafast measurement and compressive sensing. This paves the way for novel
imaging architectures and remote sensing in extreme situations where imaging
with a lens is not possible.


title:
Subcritical Approach to Sharp Hardy-Littlewood-Sobolev Type Inequalities
  on the Upper Half Space

abstract:
  In this paper we establish the reversed sharp Hardy-Littlewood-Sobolev (HLS
for short) inequality on the upper half space and obtain a new HLS type
integral inequality on the upper half space (extending an inequality found by
Hang, Wang and Yan in \cite{HWY2008}) by introducing a uniform approach. The
extremal functions are classified via the method of moving spheres, and the
best constants are computed. The new approach can also be applied to obtain the
classical HLS inequality and other similar inequalities.


title:
Recovery of an embedded obstacle and its surrounding medium by
  formally-determined scattering data

abstract:
  We consider an inverse acoustic scattering problem in simultaneously
recovering an embedded obstacle and its surrounding inhomogeneous medium by
formally determined far-field data. It is shown that the knowledge of the
scattering amplitude with a fixed incident direction and all observation angles
along with frequencies from an open interval can be used to uniquely identify
the embedded obstacle, sound-soft or sound-hard disregarding the surrounding
medium. Furthermore, if the surrounding inhomogeneous medium is from an
admissible class (still general), then the medium can be recovered as well. Our
argument is based on deriving certain integral identities involving the
unknowns and then inverting them by certain harmonic analysis techniques.
Finally, based on our theoretical study, a fast and robust sampling method is
proposed to reconstruct the shape and location of the buried targets and the
support of the surrounding inhomogeneities.


title: Measure expanding actions, expanders and warped cones

abstract:
  We define a way of approximating actions on measure spaces using finite
graphs; we then show that in quite general settings these graphs form a family
of expanders if and only if the action is expanding in measure. This provides a
somewhat unified approach to construct expanders. We also show that the graphs
we obtain are uniformly quasi-isometric to the level sets of warped cones. This
way we can also prove non-embeddability results for the latter and restate an
old conjecture of Gamburd-Jakobson-Sarnak.


title: CuMF_SGD: Fast and Scalable Matrix Factorization

abstract:
  Matrix factorization (MF) has been widely used in e.g., recommender systems,
topic modeling and word embedding. Stochastic gradient descent (SGD) is popular
in solving MF problems because it can deal with large data sets and is easy to
do incremental learning. We observed that SGD for MF is memory bound.
Meanwhile, single-node CPU systems with caching performs well only for small
data sets; distributed systems have higher aggregated memory bandwidth but
suffer from relatively slow network connection. This observation inspires us to
accelerate MF by utilizing GPUs's high memory bandwidth and fast intra-node
connection. We present cuMF_SGD, a CUDA-based SGD solution for large-scale MF
problems. On a single CPU, we design two workload schedule schemes, i.e.,
batch-Hogwild! and wavefront-update that fully exploit the massive amount of
cores. Especially, batch-Hogwild! as a vectorized version of Hogwild! overcomes
the issue of memory discontinuity. We also develop highly-optimized kernels for
SGD update, leveraging cache, warp-shuffle instructions and half-precision
floats. We also design a partition scheme to utilize multiple GPUs while
addressing the well-known convergence issue when parallelizing SGD. On three
data sets with only one Maxwell or Pascal GPU, cuMF_SGD runs 3.1X-28.2X as fast
compared with state-of-art CPU solutions on 1-64 CPU nodes. Evaluations also
show that cuMF_SGD scales well on multiple GPUs in large data sets.


title: Cycles with two blocks in $k$-chromatic digraphs

abstract:
  Let $k$ and $\ell$ be positive integers. A cycle with two blocks $c(k,\ell)$
is an oriented cycle which consists of two internally (vertex) disjoint
directed paths of lengths at least $k$ and $\ell$, respectively, from a vertex
to another one. A problem of Addario-Berry, Havet and Thomass\'e (2007) asked
if, given positive integers $k$ and $\ell$ such that $k+\ell\ge 4$, any
strongly connected digraph $D$ containing no $c(k,\ell)$ has chromatic number
at most $k+\ell-1$. In this paper, we show that such digraph $D$ has chromatic
number at most $O((k+\ell)^2)$, improving the previous upper bound
$O((k+\ell)^4)$ obtained by Cohen, Havet, Lochet and Nisse (2016). In fact, we
are able to find a digraph which shows that the answer to the above problem is
no. We also show that if in addition $D$ is Hamiltonian, then its underlying
simple graph is $(k+\ell-1)$-degenerate and thus the chromatic number of $D$ is
at most $k+\ell$, which is tight.


title: On a theorem of A. I. Popov on sums of squares

abstract:
  Let $r_k(n)$ denote the number of representations of the positive integer $n$
as the sum of $k$ squares. In 1934, the Russian mathematician A.~I.~Popov
stated, but did not rigorously prove, a beautiful series transformation
involving $r_k(n)$ and certain Bessel functions. We provide a proof of this
identity for the first time, as well as for another identity, which can be
regarded as both an analogue of Popov's identity and an identity involving
$r_2(n)$ from Ramanujan's lost notebook.


title: Anticoherent Subspaces

abstract:
  We extend the notion of anticoherent spin states to anticoherent subspaces.
An anticoherent subspace of order t, is a subspace whose unit vectors are all
anticoherent states of order t. We use Klein's description of algebras of
polynomials which are invariant under finite subgroups of SU(2) to provide
constructions of anticoherent subspaces. Furthermore, we show a connection
between the existence of these subspaces and the properties of the higher-rank
numerical range for a set of spin observables. We also note that these
constructions give us subspaces of spin states all of whose unit vectors have
Majorana representations which are spherical designs of order at least t.


title: Coevolution of Binaries and Gaseous Discs

abstract:
  The recent discoveries of circumbinary planets by $\it Kepler$ raise
questions for contemporary planet formation models. Understanding how these
planets form requires characterizing their formation environment, the
circumbinary protoplanetary disc, and how the disc and binary interact and
change as a result. The central binary excites resonances in the surrounding
protoplanetary disc that drive evolution in both the binary orbital elements
and in the disc. To probe how these interactions impact binary eccentricity and
disc structure evolution, N-body smooth particle hydrodynamics (SPH)
simulations of gaseous protoplanetary discs surrounding binaries based on
Kepler 38 were run for $10^4$ binary periods for several initial binary
eccentricities. We find that nearly circular binaries weakly couple to the disc
via a parametric instability and excite disc eccentricity growth. Eccentric
binaries strongly couple to the disc causing eccentricity growth for both the
disc and binary. Discs around sufficiently eccentric binaries that strongly
couple to the disc develop an $m = 1$ spiral wave launched from the 1:3
eccentric outer Lindblad resonance (EOLR) that corresponds to an alignment of
gas particle longitude of periastrons. All systems display binary semimajor
axis decay due to dissipation from the viscous disc.


title:
The Pontryagin's maximum principle for stochastic differential systems
  under state constraints

abstract:
  In this study, we consider an optimal control problem driven by a stochastic
differential equation with state constraints. Here, the state constraints mean
the constraints about the path of state. In order to show the maximum principe
for the optimal control problem under state constraints, we investigate a new
near optimal control problem. In the following, we establish the stochastic
maximum principle for the new optimal control problem under multi-time state
constraints. In the end, we give a production planning example to verify the
main results of this study.


title: A Curvature Flow and Applications to an Isoperimetric Inequality

abstract:
  Long time existence and convergence to a circle is proved for radial graph
solutions to a mean curvature type curve flow in warped product surfaces (under
a weak assumption on the warp potential of the surface). This curvature flow
preserves the area enclosed by the evolving curve, and this fact is used to
prove a general isoperimetric inequality applicable to radial graphs in warped
product surfaces under weak assumptions on the warp potential.


title: Anomalous Thermal Diffusivity in Underdoped YBa$_2$Cu$_3$O$_{6+x}$

abstract:
  We present local optical measurements of thermal diffusivity in the $ab$
plane of underdoped YBCO crystals. We find that the diffusivity anisotropy is
comparable to reported values of the electrical resistivity anisotropy,
suggesting that the anisotropies have the same origin. The anisotropy drops
sharply below the charge order transition. We interpret our results through a
strong electron-phonon scattering picture and find that both electronic and
phononic contributions to the diffusivity saturate a proposed bound. Our
results suggest that neither well-defined electron nor phonon quasiparticles
are present in this material.


title:
Phase diagram of dirty two-band superconductors and observability of
  impurity-induced $s+is$ state

abstract:
  We investigate the phase diagram of dirty two-band superconductors. This
paper primarily focuses on the properties and observability of the
time-reversal symmetry-breaking $s+is$ superconducting states, which can be
generated in two-band superconductors by interband impurity scattering. We show
that such states can appear in two distinct ways. First, according to a
previously discussed scenario, the $s+is$ state can form as an intermediate
phase at the impurity-driven crossover between $s_{\pm}$ and $s_{++}$ states.
We show that there is a second scenario where domains of the $s+is$ state
exists in the form of an isolated dome inside the $s_{\pm}$ domain, completely
detached from the transition between $s_{\pm}$ and $s_{++}$ states. We
demonstrate that in both cases the $s+is$ state, generated by impurity
scattering exists in an extremely small interval of impurity concentrations.
Although this likely precludes direct experimental observation of the $s+is$
state formation due to this mechanism, this physics leads to the appearance of
a region inside both the $s_{\pm}$ and $s_{++}$ domains with unusual properties
due to softening of normal modes.


title:
Output Feedback Control of a Class of Uncertain Systems Under
  Control-derivative dependent disturbances

abstract:
  This paper addresses the design of robust dynamic output feedback control for
highly uncertain systems in which the unknown disturbance might be excited by
the derivative of the control input. This context appears in many industrial
problems such as the speed control of the hydraulic turbines and the frequency
stabilization in micro grids to cite but few examples. A key feature that has
to be carefully addressed in this context is that too agressive feedback might
lead to the loss of controllability and/or a significant drop in the
closed-loop performance. The paper formulates the problem, underlines its
relevance and gives a rigorous solution in which a dynamic output feedback is
given together with a realistic set of sufficient conditions on the
controller's parameters that enable to assess the behavior of the closed-loop
under different circumstances. A numerical example is given to illustrate the
relevance of the proposed successful design characterization.


title: The Piecewise Cubic Method (PCM) for Computational Fluid Dynamics

abstract:
  We present a new high-order finite volume reconstruction method for
hyperbolic conservation laws. The method is based on a piecewise cubic
polynomial which provides its solutions a fifth-order accuracy in space. The
spatially reconstructed solutions are evolved in time with a fourth-order
accuracy by tracing the characteristics of the cubic polynomials. As a result,
our temporal update scheme provides a significantly simpler and computationally
more efficient approach in achieving fourth order accuracy in time, relative to
the comparable fourth-order Runge-Kutta method. We demonstrate that the
solutions of PCM converges in fifth-order in solving 1D smooth flows described
by hyperbolic conservation laws. We test the new scheme in a range of numerical
experiments, including both gas dynamics and magnetohydrodynamics applications
in multiple spatial dimensions.


title: Finite Computational Structures and Implementations

abstract:
  What is computable with limited resources? How can we verify the correctness
of computations? How to measure computational power with precision? Despite the
immense scientific and engineering progress in computing, we still have only
partial answers to these questions. In order to make these problems more
precise, we describe an abstract algebraic definition of classical computation,
generalizing traditional models to semigroups. The mathematical abstraction
also allows the investigation of different computing paradigms (e.g. cellular
automata, reversible computing) in the same framework. Here we summarize the
main questions and recent results of the research of finite computation.


title:
Discretization of mixed formulations of elliptic problems on polyhedral
  meshes

abstract:
  We review basic design principles underpinning the construction of mimetic
finite difference and a few finite volume and finite element schemes for mixed
formulations of elliptic problems. For a class of low-order mixed-hybrid
schemes, we show connections between these principles and prove that the
consistency and stability conditions must lead to a member of the mimetic
family of schemes regardless of the selected discretization framework. Finally,
we give two examples of using flexibility of the mimetic framework: derivation
of higher-order schemes and convergent schemes for nonlinear problems with
small diffusion coefficients.


title: Derivation of the Special Theory of Relativity from Invariance of Action

abstract:
  It is known that action is invariant in special relativity. The goal of this
note is to show that the reverse statement is also correct, that special
relativity follows from the postulate that action is invariant under the
transformation from one inertial frame to another.


title:
Substrate induced tuning of compressive strain and phonon modes in large
  area MoS2 and WS2 van der Waals epitaxial thin films

abstract:
  Large area MoS2 and WS2 van der Waals epitaxial thin films with complete
control over number of layers including monolayer is grown by pulsed laser
deposition utilizing slower growth kinetics. The films grown on c-plane
sapphire show stiffening of A1g and E12g phonon modes with decreasing number of
layers for both MoS2 and WS2. The observed stiffening translate into the
compressive strain of 0.52 % & 0.53 % with accompanying increase in fundamental
direct band gap to 1.74 and 1.68 eV for monolayer MoS2 and WS2, respectively.
The strain decays with the number of layers. HRTEM imaging directly reveals the
nature of atomic registry of van der Waals layers with the substrate and the
associated compressive strain. The results demonstrate a practical route to
stabilize and engineer strain for this class of material over large area device
fabrication.


title: A new identity of Dickson polynomials

abstract:
  A new polynomial identity is found for Dickson polynomials in characteristic
2. The identity is used to prove that the two polynomials $x^{q+1}+x+1/a$ and
$C(x)+a$ have the same splitting field over $F$, where $F$ is a field of
characteristic 2, $a$ is a nonzero element of $F$, $q=2^n>2$, and $C(x) = x
(\sum_{i=0}^{n-1} x^{2^i-1})^{q+1}$ is a M\"uller--Cohen--Matthews polynomial
of degree $(q^2-q)/2$. In addition, a new proof is obtained for the known
result that $C(x)$ induces a permutation on $F_{2^m}$ if $2m$ and $n$ are
relatively prime.


title: Mixed context networks for semantic segmentation

abstract:
  Semantic segmentation is challenging as it requires both object-level
information and pixel-level accuracy. Recently, FCN-based systems gained great
improvement in this area. Unlike classification networks, combining features of
different layers plays an important role in these dense prediction models, as
these features contains information of different levels. A number of models
have been proposed to show how to use these features. However, what is the best
architecture to make use of features of different layers is still a question.
In this paper, we propose a module, called mixed context network, and show that
our presented system outperforms most existing semantic segmentation systems by
making use of this module.


title:
Imaging of locally rough surfaces from intensity-only far-field or
  near-field data

abstract:
  This paper is concerned with a nonlinear imaging problem, which aims to
reconstruct a locally perturbed, perfectly reflecting, infinite plane from
intensity-only (or phaseless) far-field or near-field data. A recursive Newton
iteration algorithm in frequencies is developed to reconstruct the locally
rough surface from multi-frequency intensity-only far-field or near-field data,
where the fast integral equation solver developed in [39] is used to solve the
direct scattering problem in each iteration. For the case with far-field data,
a main feature of our work is that the incident field is taken as a
superposition of two plane waves with different directions rather than one
plane wave, so the location and shape of the local perturbation of the infinite
plane can be reconstructed simultaneously from intensity-only far-field data
with multiple wave numbers. This is different from previous work on inverse
scattering from phaseless far-field data, where only the shape reconstruction
was considered due to the translation invariance property of the phaseless
far-field pattern corresponding to one plane wave as the incident field.
Finally, numerical examples are carried out to demonstrate that our
reconstruction algorithm is stable and accurate even for the case of
multiple-scale profiles.


title: Gravitational "seesaw" and light bending in higher-derivative gravity

abstract:
  Local gravitational theories with more than four derivatives have remarkable
quantum properties, e.g., they are super-renormalizable and may be unitary in
the Lee-Wick sense. Therefore, it is important to explore also the IR limit of
these theories and identify observable signatures of the higher derivatives. In
the present work we study the scattering of a photon by a classical external
gravitational field in the sixth-derivative model whose propagator contains
only real, simple poles. Also, we discuss the possibility of a gravitational
seesaw-like mechanism, which could allow the make up of a relatively small
physical mass from the huge massive parameters of the action. If possible, this
mechanism would be a way out of the Planck suppression, affecting the
gravitational deflection of low energy photons. It turns out that the mechanism
which actually occurs works only to shift heavier masses to the further UV
region. This fact may be favourable for protecting the theory from
instabilities, but makes experimental detection of higher derivatives more
difficult.


title: Graphical Models for Zero-Inflated Single Cell Gene Expression

abstract:
  Bulk gene expression experiments relied on aggregations of thousands of cells
to measure the average expression in an organism. Advances in microfluidic and
droplet sequencing now permit expression profiling in single cells. This study
of cell-to-cell variation reveals that individual cells lack detectable
expression of transcripts that appear abundant on a population level, giving
rise to zero-inflated expression patterns. To infer gene co-regulatory networks
from such data, we propose a multivariate Hurdle model. It is comprised of a
mixture of singular Gaussian distributions. We employ neighborhood selection
with the pseudo-likelihood and a group lasso penalty to select and fit
undirected graphical models that capture conditional independences between
genes. The proposed method is more sensitive than existing approaches in
simulations, even under departures from our Hurdle model. The method is applied
to data for T follicular helper cells, and a high-dimensional profile of mouse
dendritic cells. It infers network structure not revealed by other methods; or
in bulk data sets. An R implementation is available at
https://github.com/amcdavid/HurdleNormal .


title: Bidirectional LSTM-CRF for Clinical Concept Extraction

abstract:
  Extraction of concepts present in patient clinical records is an essential
step in clinical research. The 2010 i2b2/VA Workshop on Natural Language
Processing Challenges for clinical records presented concept extraction (CE)
task, with aim to identify concepts (such as treatments, tests, problems) and
classify them into predefined categories. State-of-the-art CE approaches
heavily rely on hand crafted features and domain specific resources which are
hard to collect and tune. For this reason, this paper employs bidirectional
LSTM with CRF decoding initialized with general purpose off-the-shelf word
embeddings for CE. The experimental results achieved on 2010 i2b2/VA reference
standard corpora using bidirectional LSTM CRF ranks closely with top ranked
systems.


title:
The focusing properties of both normal and superconducting low energy CW
  proton Linacs

abstract:
  The continue wave (CW) high current proton linac has wide applications as the
front end of the high power proton machines. The low energy part is the most
difficult one and there is no widely accepted solution yet. Both normal
conducting and superconducting acceleration structures are thought to be the
possible solutions. Although the characteristics of normal conducting
structures and superconducting ones are quite different, such as acceleration
voltage, maximum electric field and so on, we found the focusing properties of
the lattice composed by these two acceleration structures are quite similar for
different reasons. The advantages and disadvantages of lattices composed of
both the normal conducting and superconducting structures are analysed from the
beam dynamics point of view, and their constraints on beam main parameters are
discussed.


title: Semibricks

abstract:
  In representation theory of finite-dimensional algebras, (semi)bricks are a
generalization of (semi)simple modules, and they have long been studied. The
aim of this paper is to study semibricks from the point of view of
$\tau$-tilting theory. We construct canonical bijections between the set of
support $\tau$-tilting modules, the set of semibricks satisfying a certain
finiteness condition, and the set of 2-term simple-minded collections. In
particular, we unify Koenig-Yang bijections and Ingalls-Thomas bijections
generalized by Marks-\v{S}\v{t}ov\'{i}\v{c}ek, which involve several important
notions in the derived categories and the module categories. We also
investigate connections between our results and two kinds of reduction theorems
of $\tau$-rigid modules by Jasso and Eisele-Janssens-Raedschelders. Moreover,
we study semibricks over Nakayama algebras and tilted algebras in detail.


title: StuffNet: Using 'Stuff' to Improve Object Detection

abstract:
  We propose a Convolutional Neural Network (CNN) based algorithm - StuffNet -
for object detection. In addition to the standard convolutional features
trained for region proposal and object detection [31], StuffNet uses
convolutional features trained for segmentation of objects and 'stuff'
(amorphous categories such as ground and water). Through experiments on Pascal
VOC 2010, we show the importance of features learnt from stuff segmentation for
improving object detection performance. StuffNet improves performance from
18.8% mAP to 23.9% mAP for small objects. We also devise a method to train
StuffNet on datasets that do not have stuff segmentation labels. Through
experiments on Pascal VOC 2007 and 2012, we demonstrate the effectiveness of
this method and show that StuffNet also significantly improves object detection
performance on such datasets.


title: Interval Superposition Arithmetic

abstract:
  This paper presents a novel set-based computing method, called interval
superposition arithmetic, for enclosing the image set of multivariate
factorable functions on a given domain. In order to construct such enclosures,
the proposed arithmetic operates over interval superposition models which are
parameterized by a matrix with interval components. Every point in the domain
of a factorable function is then associated with a sequence of components of
this matrix and the superposition, i.e. Minkowski sum, of these elements
encloses the image of the function at this point. Interval superposition
arithmetic has a linear runtime complexity with respect to the number of
variables. Besides presenting a detailed theoretical analysis of the accuracy
and convergence properties of interval superposition arithmetic, the paper
illustrates its advantages compared to existing set arithmetics via numerical
examples.


title: Learning Quadrotor Dynamics Using Neural Network for Flight Control

abstract:
  Traditional learning approaches proposed for controlling quadrotors or
helicopters have focused on improving performance for specific trajectories by
iteratively improving upon a nominal controller, for example learning from
demonstrations, iterative learning, and reinforcement learning. In these
schemes, however, it is not clear how the information gathered from the
training trajectories can be used to synthesize controllers for more general
trajectories. Recently, the efficacy of deep learning in inferring helicopter
dynamics has been shown. Motivated by the generalization capability of deep
learning, this paper investigates whether a neural network based dynamics model
can be employed to synthesize control for trajectories different than those
used for training. To test this, we learn a quadrotor dynamics model using only
translational and only rotational training trajectories, each of which can be
controlled independently, and then use it to simultaneously control the yaw and
position of a quadrotor, which is non-trivial because of nonlinear couplings
between the two motions. We validate our approach in experiments on a quadrotor
testbed.


title:
Resonant Magnetization Switching Conditions of an Exchange-coupled
  Bilayer under Spin Wave Excitation

abstract:
  We systematically investigated the spin wave-assisted magnetization switching
(SWAS) of a L10-FePt / Ni81Fe19 (Permalloy; Py) exchange-coupled bilayer using
a pulse-like rf field (hrf) and mapped the switching events in the magnetic
field (H) - hrf frequency (f) plane to reveal the switching conditions. The
switching occurred only in a limited region following the dispersion
relationship of the perpendicular standing spin wave (PSSW) modes in Py. The
results indicate that SWAS is a resonant magnetization switching process, which
is different from the conventional microwave assisted switching, and has the
potential to be applied to selective switching for multilevel recording media.


title: Quasi-lisse vertex algebras and modular linear differential equations

abstract:
  We introduce a notion of quasi-lisse vertex algebras, which generalizes
admissible affine vertex algebras. We show that the normalized character of an
ordinary module over a quasi-lisse vertex operator algebra has a modular
invariance property, in the sense that it satisfies a modular linear
differential equation. As an application we obtain the explicit character
formulas of simple affine vertex algebras associated with the Deligne
exceptional series at level $-h^{\vee}/6-1$, which express the homogeneous
Schur indices of 4d SCFTs studied by Beem, Lemos, Liendo, Peelaers, Rastelli
and van Rees, as quasi-modular forms.


title: Anomalous Hall Coulomb drag of massive Dirac fermions

abstract:
  Dirac fermions are actively investigated, and the discovery of the quantized
anomalous Hall effect of massive Dirac fermions has spurred the promise of
low-energy electronics. Some materials hosting Dirac fermions are natural
platforms for interlayer coherence effects such as Coulomb drag and exciton
condensation. Here we determine the role played by the anomalous Hall effect in
Coulomb drag in massive Dirac fermion systems. We focus on topological
insulator films with out-of plane magnetizations in both the active and passive
layers. The transverse response of the active layer is dominated by a
topological term arising from the Berry curvature. We show that the topological
mechanism does not contribute to Coulomb drag, yet the longitudinal drag force
in the passive layer gives rise to a transverse drag current. This anomalous
Hall drag current is independent of the active-layer magnetization, a fact that
can be verified experimentally. It depends non-monotonically on the
passive-layer magnetization, exhibiting a peak that becomes more pronounced at
low densities. These findings should stimulate new experiments and quantitative
studies of anomalous Hall drag.


title:
Synthesis from Assume-Guarantee Contracts using Skolemized Proofs of
  Realizability

abstract:
  The realizability problem in requirements engineering is to determine the
existence of an implementation that meets the given formal requirements. A step
forward after realizability is proven, is to construct such an implementation
automatically, and thus solve the problem of program synthesis. In this paper,
we propose a novel approach to pro- gram synthesis guided by k-inductive proofs
of realizability of assume- guarantee contracts constructed from safety
properties. The proof of re- alizability is performed over a set of
forall-exists formulas, and synthesis is per- formed by extracting Skolem
functions witnessing the existential quan- tification. These Skolem functions
can then be combined into an imple- mentation. Our approach is implemented in
the JSyn tool which con- structs Skolem functions from a contract written in a
variant of the Lus- tre programming language and then compiles the Skolem
functions into a C language implementation. For a variety of benchmark models
that already contained hand-written implementations, we are able to identify
the usability and effectiveness of the synthesized counterparts, assuming a
component-based verification framework.


title: Feature-Based Classification of Networks

abstract:
  Network representations of systems from various scientific and societal
domains are neither completely random nor fully regular, but instead appear to
contain recurring structural building blocks. These features tend to be shared
by networks belonging to the same broad class, such as the class of social
networks or the class of biological networks. At a finer scale of
classification within each such class, networks describing more similar systems
tend to have more similar features. This occurs presumably because networks
representing similar purposes or constructions would be expected to be
generated by a shared set of domain specific mechanisms, and it should
therefore be possible to classify these networks into categories based on their
features at various structural levels. Here we describe and demonstrate a new,
hybrid approach that combines manual selection of features of potential
interest with existing automated classification methods. In particular,
selecting well-known and well-studied features that have been used throughout
social network analysis and network science and then classifying with methods
such as random forests that are of special utility in the presence of feature
collinearity, we find that we achieve higher accuracy, in shorter computation
time, with greater interpretability of the network classification results.


title: The argmin process of random walks and L\'evy processes

abstract:
  In this paper we consider the argmin process of random walks and L\'evy
processes. We prove that they enjoy the Markov property, and provide their
transition kernels in some special cases.


title: On the origin of exponential growth in induced earthquakes in Groningen

abstract:
  The Groningen gas field shows exponential growth in earthquakes event counts
around a magnitude M1 with a doubling time of 6-9 years since 2001. This
behavior is identified with dimensionless curvature in land subsidence, which
has been evolving at a constant rate over the last few decades {essentially
uncorrelated to gas production.} We demonstrate our mechanism by a tabletop
crack formation experiment. The observed skewed distribution of event
magnitudes is matched by that of maxima of event clusters with a normal
distribution. It predicts about one event $<$\,M5 per day in 2025, pointing to
increasing stress to human living conditions.


title:
One example about the relationship between the CD inequality and CDE'
  inequality

abstract:
  In this paper,we will give an easy example to satisfy that we can not
conclude CDE' Inequality just from the CD Inequality.


title: Making brain-machine interfaces robust to future neural variability

abstract:
  A major hurdle to clinical translation of brain-machine interfaces (BMIs) is
that current decoders, which are trained from a small quantity of recent data,
become ineffective when neural recording conditions subsequently change. We
tested whether a decoder could be made more robust to future neural variability
by training it to handle a variety of recording conditions sampled from months
of previously collected data as well as synthetic training data perturbations.
We developed a new multiplicative recurrent neural network BMI decoder that
successfully learned a large variety of neural-to- kinematic mappings and
became more robust with larger training datasets. When tested with a non-human
primate preclinical BMI model, this decoder was robust under conditions that
disabled a state-of-the-art Kalman filter based decoder. These results validate
a new BMI strategy in which accumulated data history is effectively harnessed,
and may facilitate reliable daily BMI use by reducing decoder retraining
downtime.


title:
Do fast stellar centroiding methods saturate the Cram\'{e}r-Rao lower
  bound?

abstract:
  One of the most demanding tasks in astronomical image processing---in terms
of precision---is the centroiding of stars. Upcoming large surveys are going to
take images of billions of point sources, including many faint stars, with
short exposure times. Real-time estimation of the centroids of stars is crucial
for real-time PSF estimation, and maximal precision is required for
measurements of proper motion.
  The fundamental Cram\'{e}r-Rao lower bound sets a limit on the
root-mean-squared-error achievable by optimal estimators. In this work, we aim
to compare the performance of various centroiding methods, in terms of
saturating the bound, when they are applied to relatively low signal-to-noise
ratio unsaturated stars assuming zero-mean constant Gaussian noise. In order to
make this comparison, we present the ratio of the root-mean-squared-errors of
these estimators to their corresponding Cram\'{e}r-Rao bound as a function of
the signal-to-noise ratio and the full-width at half-maximum of faint stars.
  We discuss two general circumstances in centroiding of faint stars: (i) when
we have a good estimate of the PSF, (ii) when we do not know the PSF. In the
case that we know the PSF, we show that a fast polynomial centroiding after
smoothing the image by the PSF can be as efficient as the maximum-likelihood
estimator at saturating the bound. In the case that we do not know the PSF, we
demonstrate that although polynomial centroiding is not as optimal as PSF
profile fitting, it comes very close to saturating the Cram\'{e}r-Rao lower
bound in a wide range of conditions. We also show that the moment-based method
of center-of-light never comes close to saturating the bound, and thus it does
not deliver reliable estimates of centroids.


title: Classifying Subatomic Domains

abstract:
  In general, ring theory is focused on atomic rings, i.e. rings in which every
element has some factorization into irreducible elements. In a recent paper of
Boynton and Coykendall \cite{BC}, the two authors introduce two properties that
are slightly weaker than atomicity, which they call "almost atomicity" and
"quasiatomicity". In this paper, we classify various subatomic properties and
show that they are all distinct.


title: Surface tension of highly magnetized degenerate quark matter

abstract:
  We study the surface tension of highly magnetized three flavor quark matter
within the formalism of multiple reflection expansion (MRE). Quark matter is
described as a mixture of free Fermi gases composed by quarks $u$, $d$, $s$ and
electrons, in chemical equilibrium under weak interactions. Due to the presence
of strong magnetic fields the particles' transverse motion is quantized into
Landau levels, and the surface tension has a different value in the parallel
and transverse directions with respect to the magnetic field.
  We calculate the transverse and longitudinal surface tension for different
values of the magnetic field and for quark matter drops with different sizes,
from a few fm to the bulk limit. For baryon number densities between $2-10$
times the nuclear saturation density, the surface tension falls in the range $2
- 20$ MeV /fm$^{2}$. The largest contribution comes from strange quarks which
have a surface tension an order of magnitude larger than the one for $u$ or $d$
quarks and more than two orders of magnitude larger than for electrons. Our
results show that the total surface tension is quite insensitive to the size of
the drop. We also find that the surface tensions in the transverse and parallel
directions are almost unaffected by the magnetic field if $eB$ is below $\sim 5
\times 10^{-3} $ GeV$^2$. Nevertheless, for higher values of $eB$, there is a
significant increase in the parallel surface tension and a significant decrease
in the transverse one with respect to the unmagnetized case.


title:
NLO QCD + EW corrections to $ZZZ$ production with subsequent leptonic
  decays at LHC

abstract:
  In this paper we present the NLO QCD + NLO EW corrections to the $ZZZ$
production with subsequent $Z$-boson leptonic decays at the LHC by adopting the
improved narrow width approximation, which takes into account off-shell
contributions and spin correlations. Integrated cross sections at $13$, $14$,
$33$ and $100~{\rm TeV}$ hadron colliders and various kinematic distributions
are presented. Our numerical results show that the jet emission correction
accounts for a large part of the total QCD correction, especially in the high
energy region. By applying a proper cut to the jet transverse momentum, e.g.,
$p_{{\rm \,T,jet}} > p_{{\rm \,T,jet}}^{{\rm \,\,\,cut}}=50~{\rm GeV}$, the jet
emission correction can be reduced and the cross section is less dependent on
the factorization/renormalization scale. This work reveals that both the NLO
QCD and the NLO EW corrections are significant. For example, the NLO QCD, NLO
EW and NLO QCD + EW relative corrections in the inclusive event selection
scheme at the $13~{\rm TeV}$ LHC can reach $63.2\%$, $-9.6\%$ and $47.5\%$,
respectively, which means that neither the NLO QCD nor the NLO EW correction is
negligible in precision calculations.


title:
Widely tunable, narrow linewidth external-cavity gain chip laser for
  spectroscopy between 1.0 - 1.1 um

abstract:
  We have developed and characterised a stable, narrow linewidth
external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a
single-angled-facet gain chip. We propose the ECL as a low-cost,
high-performance alternative to fibre and diode lasers in this wavelength range
and demonstrate its capability through the spectroscopy of metastable helium.
Within the coarse tuning range, the wavelength can be continuously tuned over
30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz
(piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL
was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5
ms, while a long-term frequency stability better than 40(20) kHz over 11 hours
was observed when locked to an atomic reference.


title: Anomalous dimensions of higher spin currents in large N CFTs

abstract:
  We examine anomalous dimensions of higher spin currents in the critical O(N)
scalar model and the Gross-Neveu model in arbitrary d dimensions. These two
models are proposed to be dual to the type A and type B Vasiliev theories,
respectively. We reproduce the known results on the anomalous dimensions to the
leading order in 1/N by using conformal perturbation theory. This work can be
regarded as an extension of previous work on the critical O(N) scalars in 3
dimensions, where it was shown that the bulk computation for the masses of
higher spin fields on AdS_4 can be mapped to the boundary one in conformal
perturbation theory. The anomalous dimensions of the both theories agree with
each other up to an overall factor depending only on d, and we discuss the
coincidence for d=3 by utilizing N=2 supersymmetry.


title:
Recovering scattering obstacles by multi-frequency phaseless far-field
  data

abstract:
  It is well known that the modulus of the far-field pattern (or phaseless
far-field pattern) is invariant under translations of the scattering obstacle
if only one plane wave is used as the incident field, so the shape but not the
location of the obstacle can be recovered from the phaseless far-field data. In
this paper, it is proved that the translation invariance property of the
phaseless far-field pattern can be broken if superpositions of two plane waves
are used as the incident fields for all wave numbers in a finite interval.
Based on this, a recursive Newton-type iteration algorithm in frequencies is
then developed to recover both the location and the shape of the obstacle
simultaneously from multi-frequency phaseless far-field data. Numerical
examples are also carried out to illustrate the validity of the approach and
the effectiveness of the inversion algorithm.


title:
Doping Effects on the Electronic Structure of an Anisotropic Kondo
  Semiconductor CeOs$_2$Al$_{10}$: An Optical Study with Re and Ir Substitution

abstract:
  An anisotropic Kondo semiconductor CeOs$_2$Al$_{10}$ exhibits an unusual
antiferromagnetic order at rather high transition temperature $T_0$ of 28.5 K.
Two possible origins of the magnetic order have been proposed so far, one is
the Kondo coupling of the hybridization between the conduction ($c$) and the
$4f$ states and the other is the charge-density wave/charge ordering along the
orthorhombic $b$ axis. To clarify the origin of the magnetic order, we have
investigated the electronic structure of hole- and electron-doped
CeOs$_2$Al$_{10}$ [Ce(Os$_{1-y}$Re$_y$)$_2$Al$_{10}$ and
Ce(Os$_{1-x}$Ir$_x$)$_2$Al$_{10}$, respectively] by using optical conductivity
spectra along the $b$ axis. The intensity of the $c$-$f$ hybridization gap at
$\hbar\omega\sim50$ meV continuously decreases from $y=0.10$ to $x=0.12$ via
$x=y=0$. The intensity of the charge excitation observed at $\hbar\omega\sim20$
meV has the maximum at $x=y=0$ as similar with the doping dependence of $T_{\rm
0}$. The fact that the charge excitation is strongly related to the magnetic
order strengthens the possibility of the charge density wave/charge ordering as
the origin of the magnetic order.


title:
Resurgent functions and nonlinear systems of differential and difference
  equations

abstract:
  The principal aim of this article is to establish an iteration method on the
space of resurgent functions. We discuss endless continuability of iterated
convolution products of resurgent functions and derive their estimates
developing the method in arXiv:1610.05453. Using the estimates, we show the
resurgence of formal series solutions of nonlinear differential and difference
equations.


title:
Cognitive Indoor Positioning and Tracking using Multipath Channel
  Information

abstract:
  This paper presents a robust and accurate positioning system that adapts its
behavior to the surrounding environment, mimicking the capability of the visual
brain to filtering out clutter and focusing attention on activity and relevant
information. Especially in indoor environments, which are characterized by
harsh multipath propagation, robust positioning is still hard to achieve under
the constraint of reasonable infrastructural needs. In such environments it is
essential to separate relevant from irrelevant information and attain an
appropriate uncertainty model for measurements that are used for positioning.


title: A Robust 3D-2D Interactive Tool for Scene Segmentation and Annotation

abstract:
  Recent advances of 3D acquisition devices have enabled large-scale
acquisition of 3D scene data. Such data, if completely and well annotated, can
serve as useful ingredients for a wide spectrum of computer vision and graphics
works such as data-driven modeling and scene understanding, object detection
and recognition. However, annotating a vast amount of 3D scene data remains
challenging due to the lack of an effective tool and/or the complexity of 3D
scenes (e.g. clutter, varying illumination conditions). This paper aims to
build a robust annotation tool that effectively and conveniently enables the
segmentation and annotation of massive 3D data. Our tool works by coupling 2D
and 3D information via an interactive framework, through which users can
provide high-level semantic annotation for objects. We have experimented our
tool and found that a typical indoor scene could be well segmented and
annotated in less than 30 minutes by using the tool, as opposed to a few hours
if done manually. Along with the tool, we created a dataset of over a hundred
3D scenes associated with complete annotations using our tool. The tool and
dataset are available at www.scenenn.net.


title: A remote reactor monitoring with plastic scintillation detector

abstract:
  Conceiving the possibility of using plastic scintillator bars as robust
detectors for antineutrino detection for the remote reactor monitoring and
nuclear safeguard application we study expected basic performance by Monte
Carlo simulation. We present preliminary results for a 1 m3 highly segmented
detector made of 100 rectangular scintillation bars forming an array which is
sandwiched at both sides by the continuous light guides enabling light sharing
between all photo detectors. Light detection efficiency is calculated for
several light collection configurations, considering different scintillation
block geometries and number of photo-detectors. The photo-detectors signals are
forming the specific hit pattern, which is characterizing the impinging
particle. The statistical analysis of hit patterns allows effectively select
antineutrino events and rejects backgrounds. To evaluate detector sensitivity
to fuel isotopic composition evolution during fuel burning cycle we have
calculated antineutrino spectra. The statistical analyses of the antineutrino
spectra for several dates of fuel burning cycle, folded with 15% FWHM at 1 MeV
energy resolution of the detector, prove the possibility of proposed detector
to measure fuel composition evolution during fuel cycle.


title:
Meaning of the field dependence of the renormalization scale in Higgs
  inflation

abstract:
  We consider the prescription dependence of the Higgs effective potential
under the presence of general nonminimal couplings. We evaluate the fermion
loop correction to the effective action in a simplified Higgs-Yukawa model
whose path integral measure takes simple form either in the Jordan or Einstein
frame. The resultant effective action becomes identical in both cases when we
properly take into account the quartically divergent term coming from the
change of measure. Working in the counterterm formalism, we clarify that the
difference between the prescriptions I and II comes from the counter term to
cancel the logarithmic divergence. This difference can be absorbed into the
choice of tree-level potential from the infinitely many possibilities,
including all the higher-dimensional terms. We also present another mechanism
to obtain a flat potential by freezing the running of the effective quartic
coupling for large field values, using the nonminimal coupling in the gauge
kinetic function.


title:
Quark Mass Correction to Chiral Separation Effect and Pseudoscalar
  Condensate

abstract:
  We derived an analytic structure of the quark mass correction to chiral
separation effect (CSE) in small mass regime. We confirmed this structure by a
D3/D7 holographic model study in a finite density, finite magnetic field
background. The quark mass correction to CSE can be related to correlators of
pseudo-scalar condensate, quark number density and quark condensate in static
limit. We found scaling relations of these correlators with spatial momentum in
the small momentum regime. They characterize medium responses to electric
field, inhomogeneous quark mass and chiral shift. Beyond the small momentum
regime, we found existence of normalizable mode, which possibly leads to
formation of spiral phase. The normalizable mode exists beyond a critical
magnetic field, whose magnitude decreases with quark chemical potential.


title:
Zero temperature limit for (1+1) directed polymers with correlated
  random potential

abstract:
  Zero temperature limit in (1+1) directed polymers with finite range
correlated random potential is studied. In terms of the standard replica
technique it is demonstrated that in this limit the considered system reveals
the one-step replica symmetry breaking structure similar to the one which takes
place in the Random Energy Model. In particular, it is shown that at the
temperature $T_{*} \sim (u R)^{1/3}$ (where $u$ and $R$ are the strength and
the correlation length of the random potential) there is a crossover from the
high- to the low-temperature regime. Namely, in the high-temperature regime at
$T >> T_{*}$ the model is equivalent to the one with the $\delta$-correlated
potential where the non-universal prefactor of the free energy is proportional
to $T^{-2/3}$, while at $T << T_{*}$ this non-universal prefactor saturates at
a finite (temperature independent) value.


title: NLTE Analysis of High Resolution H-band Spectra. I. Neutral Silicon

abstract:
  We investigated the reliability of our silicon atomic model and the influence
of non-local thermodynamical equilibrium (NLTE) on the formation of neutral
silicon (Si I) lines in the near-infrared (near-IR) H-band. We derived the
differential Si abundances for 13 sample stars with high-resolution H-band
spectra from the Apache Point Observatory Galactic Evolution Experiment
(APOGEE), as well as from optical spectra, both under local thermodynamical
equilibrium (LTE) and NLTE conditions. We found that the differences between
the Si abundances derived from the H-band and from optical lines for the same
stars are less than 0.1 dex when the NLTE effects included, and that NLTE
reduces the line-to-line scatter in the H-band spectra for most sample stars.
These results suggest that our Si atomic model is appropriate for studying the
formation of H-band Si lines. Our calculations show that the NLTE corrections
of the Si I H-band lines are negative, i.e. the final Si abundances will be
overestimated in LTE. The corrections for strong lines depend on surface
gravity, and tend to be larger for giants, reaching ~ -0.2 dex in our sample,
and up to ~ -0.4 dex in extreme cases of APOGEE targets. Thus, the NLTE effects
should be included in deriving silicon abundances from H-band Si I lines,
especially for the cases where only strong lines are available.


title: A gap for eigenvalues of a clamped plate problem

abstract:
  This paper studies eigenvalues of the clamped plate problem on a bounded
domain in an $n$-dimensional Euclidean space. We give an estimate for the gap
between $\sqrt {\Gamma_{k+1}-\Gamma_{1}}$ and $\sqrt {\Gamma_{k}-\Gamma_{1}}$,
for any positive integer $k$. According to the asymptotic formula of Agmon and
Pleijel, we know, the gap between $\sqrt {\Gamma_{k+1}-\Gamma_{1}}$ and $\sqrt
{\Gamma_{k}-\Gamma_{1}}$ is bounded by a term with a lower order $k^{\frac1n}$
in the sense of the asymptotic formula of Agmon and Peijel, where $\Gamma_j$
denotes the $j^{^{\text{th}}}$ eigenvalue of the clamped plate problem.


title: Global Exponential Stabilization of Acyclic Traffic Networks

abstract:
  This work is devoted to the construction of explicit feedback control laws
for the robust, global, exponential stabilization of general, uncertain,
discrete-time, acyclic traffic networks. We consider discrete-time, uncertain
network models which satisfy very weak assumptions. The construction of the
controllers and the rigorous proof of the robust, global, exponential stability
for the closed-loop system are based on recently proposed vector-Lyapunov
function criteria, as well as the fact that the network is acyclic. It is
shown, in this study, that the latter requirement is necessary for the
existence of a robust, global, exponential stabilizer of the desired
uncongested equilibrium point of the network. An illustrative example
demonstrates the applicability of the obtained results to realistic traffic
flow networks.


title:
On the frequency variogram and on frequency domain methods for the
  analysis of spatio-temporal data

abstract:
  The covariance function and the variogram play very important roles in
modelling and in prediction of spatial and spatio-temporal data. The assumption
of second order stationarity, in space and time, is often made in the analysis
of spatial data and the spatio-temporal data. Several times the assumption of
stationarity is considered to be very restrictive, and therefore, a weaker
assumption that the data is Intrinsically stationary both in space and time is
often made and used, mainly by the geo-statisticians and other environmental
scientists. In this paper we consider the data to be intrinsically stationary.
Because of the inclusion of time dimension,the estimation and derivation of the
sampling properties of various estimators related to spatio-temporal data
become complicated. In this paper our object is to present an alternative way,
based on Frequency Domain methods for modelling the data. Here we consider
Discrete Fourier Transforms (DFT) defined for the (Intrinsic) time series data
observed at several locations as our data, and then consider the estimation of
the parameters of spatio-temporal covariance function, estimation of Frequency
Variogram, tests of independence etc. We use the well known property that the
Discrete Fourier Transforms of stationary time series evaluated at distinct
Fourier Frequencies are asymptotically independent and distributed as complex
normal in deriving many results considered in this paper.


title:
Centrality measures in networks based on nodes attributes, long-range
  interactions and group influence

abstract:
  We propose a new method for assessing agents influence in network structures,
which takes into consideration nodes attributes, individual and group
influences of nodes, and the intensity of interactions. This approach helps us
to identify both explicit and hidden central elements which cannot be detected
by classical centrality measures or other indices.


title: NLTE Analysis of High Resolution H-band Spectra. II. Neutral Magnesium

abstract:
  Aiming at testing the validity of our magnesium atomic model and
investigating the effects of non-local thermodynamical equilibrium (NLTE) on
the formation of the H-band neutral magnesium lines, we derive the differential
Mg abundances from selected transitions for 13 stars either adopting or
relaxing the assumption of local thermodynamical equilibrium (LTE). Our
analysis is based on high-resolution and high signal-to-noise ratio H-band
spectra from the Apache Point Observatory Galactic Evolution Experiment
(APOGEE) and optical spectra from several instruments. The absolute differences
between the Mg abundances derived from the two wavelength bands are always less
than 0.1 dex in the NLTE analysis, while they are slightly larger for the LTE
case. This suggests that our Mg atomic model is appropriate for investigating
the NLTE formation of the H-band Mg lines. The NLTE corrections for the Mg I
H-band lines are sensitive to the surface gravity, becoming larger for smaller
log g values, and strong lines are more susceptible to departures from LTE. For
cool giants, NLTE corrections tend to be negative, and for the strong line at
15765 \AA\ they reach -0.14 dex in our sample, and up to -0.22 dex for other
APOGEE stars. Our results suggest that it is important to include NLTE
corrections in determining Mg abundances from the H-band Mg I transitions,
especially when strong lines are used.


title: Spectral approximation of aperiodic Schr\"odinger operators

abstract:
  We study the (H\"older-)continuous behavior of the spectra belonging to a
family of linear bounded operators $(A_t)_{t\in T}$ indexed by a topological
space $T$. For the cases of self-adjoint, unitary and normal operators, a
characterization of the continuity of $\Sigma:T\to \mathcal{K}(\mathbb{R}),
t\mapsto \sigma(A_t),$ is proven while the distance of the spectra is measured
by the Hausorff metric. If $T$ is a metric space, the H\"older-continuous
behavior of $\Sigma$ is characterized for self-adjoint and unitary operators.
Here we observe interesting effects, namely the rate of convergence is bisect
whenever spectral gaps closes.
  Based on this, we provide a tool to prove the continuity of the spectra for
large classes of operators. In particular, we apply this theory to generalized
Schr\"odinger operators and show that the continuity of the spectra is
characterized by the continuous variation of the underlying dynamical systems.
  Finally, we analyze the existence of periodic dynamical systems approximating
a given dynamical system. This leads to periodic approximations of the
corresponding Schr\"odinger operators by the previously developed theory. We
prove that local symmetries of the patterns and the presence of a substitution
is a sufficient criteria for periodic approximations of subshifts in
$\mathbb{Z}^d$. For $d=1$, a characterization is proven for the existence of
periodic approximations. For these approaches, the notion of a dictionary is
further developed and defined independently of a given configuration. We prove
that the set of dictionaries equipped with the local pattern topology is
homeomorphic to the space of subshifts. This yields a useful tool to analyze
these systems. Furthermore, it delivers the connection of the existence of
periodic orbits in a subshift of finite type and the existence of periodic
approximations for subshifts.


title: Linear Quadratic Mean Field Game with Control Input Constraint

abstract:
  In this paper, we study a class of linear-quadratic (LQ) mean-field games in
which the individual control process is constrained in a closed convex subset
$\Gamma$ of full space $\mathbb{R}^m$. The decentralized strategies and
consistency condition are represented by a class of mean-field forward-backward
stochastic differential equation (MF-FBSDE) with projection operators on
$\Gamma$. The wellposedness of consistency condition system is obtained using
the monotonicity condition method. The related $\epsilon$-Nash equilibrium
property is also verified.


title: Surface relaxation of vapour-depositing colloidal glasses

abstract:
  Vapour deposition can directly produce ultrastable glasses, which are similar
to conventional glasses aged over thousands of years. The highly mobile surface
layer is believed to accelerate the ageing process of vapour-deposited glasses,
but its microscopic kinetics has not been experimentally observed. Here we
studied the deposition growth kinetics of a two-dimensional colloidal glass at
the single-particle level using video microscopy. We found that newly deposited
particles in the surface layer (depth $d<14$ particles) relaxed via frequent
out-of-cage motions, while particles in the deeper middle layer
($14<d\lesssim100$ particles) relaxed via activation of cooperative
rearrangement regions (CRRs). These CRRs were much larger, more anisotropic and
occurred more frequently than CRRs in the bulk ($d\gtrsim100$ particles) or
after deposition. Their centers of mass moved towards the surface, while the
particles within moved towards the bulk, causing free-volume "bubbles" to move
towards the surface to give a more compact bulk glass. This two-step relaxation
in two surface layers is distinct from the previously assumed relaxation in one
surface mobile layer


title: Fully Dynamic Algorithm for Top-$k$ Densest Subgraphs

abstract:
  Given a large graph, the densest-subgraph problem asks to find a subgraph
with maximum average degree. When considering the top-$k$ version of this
problem, a na\"ive solution is to iteratively find the densest subgraph and
remove it in each iteration. However, such a solution is impractical due to
high processing cost. The problem is further complicated when dealing with
dynamic graphs, since adding or removing an edge requires re-running the
algorithm. In this paper, we study the top-$k$ densest-subgraph problem in the
sliding-window model and propose an efficient fully-dynamic algorithm. The
input of our algorithm consists of an edge stream, and the goal is to find the
node-disjoint subgraphs that maximize the sum of their densities. In contrast
to existing state-of-the-art solutions that require iterating over the entire
graph upon any update, our algorithm profits from the observation that updates
only affect a limited region of the graph. Therefore, the top-$k$ densest
subgraphs are maintained by only applying local updates. We provide a
theoretical analysis of the proposed algorithm and show empirically that the
algorithm often generates denser subgraphs than state-of-the-art competitors.
Experiments show an improvement in efficiency of up to five orders of magnitude
compared to state-of-the-art solutions.


title: Remarks on symplectic sectional curvature

abstract:
  In [11], I. M. Gelfand, V. Retakh, and M. Shubin defined the symplectic
sectional curvature of a torsion-free connection preserving a symplectic form.
The present article defines the corresponding notion of constant symplectic
sectional curvature and characterizes this notion in terms of the curvature
tensor of the symplectic connection and its covariant derivatives. Some
relations between various more general conditions on the symplectic sectional
curvature and the geometry of the symplectic connection or that induced on a
symplectic submanifold are explored as well.


title:
Wave turbulence in a two-layer fluid: coupling between free surface and
  interface waves

abstract:
  We experimentally study gravity-capillary wave turbulence on the interface
between two immiscible fluids of close density with free upper surface. We
locally measure the wave height at the interface between both fluids by means
of a highly sensitive laser Doppler vibrometer. We show that the inertial range
of the capillary wave turbulence regime is significantly extended when the
upper fluid depth is increased: The crossover frequency between the gravity and
capillary wave turbulence regimes is found to decrease whereas the dissipative
cut-off frequency of the spectrum is found to increase. We explain these
observations by the progressive decoupling between waves propagating at the
interface and the ones at the free surface, using the full dispersion relation
of gravity-capillary waves in a two-layer fluid of finite depths. The cut-off
evolution is due to the disappearance of parasitic capillaries responsible for
the main wave dissipation for a single fluid.

categories: physics.flu-dyn nlin.CD physics.ao-ph physics.class-ph


title:
Gauge invariance and relativistic effects in photon absorption and
  scattering by matter

abstract:
  There is an incompatibility between gauge invariance and the semi-classical
time-dependent perturbation theory commonly used to calculate light absorption
and scattering cross-sections. There is an additional incompatibility between
perturbationtheory and the description of the electron dynamics by a
semi-relativistic Hamiltonian.In this paper, the gauge-dependence problem of
exact perturbation theory is described, the proposed solutions are reviewed and
it is concluded that none of them seems fully satisfactory. The problem is
finally solved by using the fully relativistic absorption and scattering
cross-sections given by quantum electrodynamics. Then, a new many-body
Foldy-Wouthuysen transformation is presented to obtain correct
semi-relativistic transition operators.This transformation considerably
simplifies the calculation of relativistic corrections. In the process, a new
light-matter interaction term emerges, called the spin-position interaction,
that contributes significantly to the magnetic x-ray circular dichroism of
transition metals.We compare our result with the ones obtained by using several
semi-relativistic time-dependent Hamiltonians. In the case of absorption, the
final formula agrees with the result obtained from one of them. However, the
correct scattering cross-section is not given by any of the semi-relativistic
Hamiltonians.


title:
Positivity of the time constant in a continuous model of first passage
  percolation

abstract:
  We consider a non trivial Boolean model $\Sigma$ on ${\mathbb R}^d$ for
$d\geq 2$. For every $x,y \in {\mathbb R}^d$ we define $T(x,y)$ as the minimum
time needed to travel from $x$ to $y$ by a traveler that walks at speed $1$
outside $\Sigma$ and at infinite speed inside $\Sigma$. By a standard
application of Kingman sub-additive theorem, one easily shows that $T(0,x)$
behaves like $\mu \|x\|$ when $\|x\|$ goes to infinity, where $\mu$ is a
constant named the time constant in classical first passage percolation. In
this paper we investigate the positivity of $\mu$. More precisely, under an
almost optimal moment assumption on the radii of the balls of the Boolean
model, we prove that $\mu\textgreater{}0$ if and only if the intensity
$\lambda$ of the Boolean model satisfies $\lambda \textless{}
\widehat{\lambda}\_c$, where $ \widehat{\lambda}\_c$ is one of the classical
critical parameters defined in continuum percolation.


title: Low-energy spectrum of Toeplitz operators with a miniwell

abstract:
  In the semiclassical limit, it is well-known that the first eigenvector of a
Toeplitz operator concentrates on the minimal set of the symbol. In this paper,
we give a more precise criterion for concentration in the case where the
minimal set of the symbol is a submanifold, in the spirit of the "miniwell
condition" of Helffer-Sj{\"o}strand.


title: Applications and non-idealities of submicron Al-AlOx-Nb tunnel junctions

abstract:
  We have developed a technique to fabricate sub-micron, 0.6 um x 0.6 um
Al-AlOx-Nb tunnel junctions using a standard e-beam resist, angle evaporation
and double oxidation of the tunneling barrier, resulting in high quality
niobium, as determined by the the high measured values of the critical
temperature TC 7.5 K and the gap 1.3 meV. The devices show great promise for
local nanoscale thermometry in the temperature range 1 - 7.5 K. Electrical
characterization of the junctions was performed at sub-Kelvin temperatures both
with and without an external magnetic field, which was used to suppress
superconductivity in Al and thus bring the junction into a
normal-metal-insulator-superconductor (NIS) configuration. We observed excess
sub-gap current, which could not be explained by the standard tunneling theory.
Evidence points towards materials science issues of the barrier or Nb/AlOx
interface as the culprit.


title: The smooth Hom-stack of an orbifold

abstract:
  For a compact manifold M and a differentiable stack \cX presented by a Lie
groupoid X, we show the Hom-stack Hom(M,\cX) is presented by a Fr\'echet-Lie
groupoid Map(M,X) and so is an infinite-dimensional differentiable stack. We
further show that if \cX is an orbifold, presented by a proper \'etale Lie
groupoid, then Map(M,X) is proper \'etale and so presents an
infinite-dimensional orbifold.


title:
Exact solution of the two-axis countertwisting Hamiltonian for the
  half-integer $J$ case

abstract:
  Bethe ansatz solutions of the two-axis countertwisting Hamiltonian for any
(integer and half-integer) $J$ are derived based on the Jordan-Schwinger
(differential) boson realization of the $SU(2)$ algebra after desired Euler
rotations, where $J$ is the total angular momentum quantum number of the
system. It is shown that solutions to the Bethe ansatz equations can be
obtained as zeros of the extended Heine-Stieltjes polynomials. Two sets of
solutions, with solution number being $J+1$ and $J$ respectively when $J$ is an
integer and $J+1/2$ each when $J$ is a half-integer, are obtained. Properties
of the zeros of the related extended Heine-Stieltjes polynomials for
half-integer $J$ cases are discussed. It is clearly shown that double
degenerate level energies for half-integer $J$ are symmetric with respect to
the $E=0$ axis. It is also shown that the excitation energies of the `yrast'
and other `yrare' bands can all be asymptotically given by quadratic functions
of $J$, especially when $J$ is large.


title:
The HADES RV Programme with HARPS-N@TNG. III. Flux-flux and
  activity-rotation relationships of early-M dwarfs

abstract:
  (Abridged) Understanding stellar activity in M dwarfs is crucial for the
physics of stellar atmospheres as well as for ongoing radial velocity exoplanet
programmes. Despite the increasing interest in M dwarfs, our knowledge of the
chromospheres of these stars is far from being complete. We aim to test whether
the relations between activity, rotation, and stellar parameters and flux-flux
relationships also hold for early-M dwarfs on the main-sequence. We analyse in
an homogeneous and coherent way a well defined sample of 71 late-K/early-M
dwarfs that are currently being observed in the framework of the HArps-n red
Dwarf Exoplanet Survey (HADES). Rotational velocities are derived using the
cross-correlation technique while emission flux excesses in the Ca II H & K and
Balmer lines from Halpha up to Hepsilon are obtained by using the spectral
subtraction technique. The relationships between the emission excesses and the
stellar parameters are studied. Relations between pairs of fluxes of different
chromospheric lines are also studied. We find that the strength of the
chromospheric emission in the Ca II H & K and Balmer lines is roughly constant
for stars in the M0-M3 spectral range. Our data suggest that a moderate but
significant correlation between activity and rotation might be present as well
as a hint of kinematically selected young stars showing higher levels of
emission. We find our sample of M dwarfs to be complementary in terms of
chromospheric and X-ray fluxes with those of the literature, extending the
analysis of the flux-flux relationships to the very low flux domain. Our
results agree with previous works suggesting that the activity-rotation-age
relationship known to hold for solar-type stars also applies to early-M dwarfs.
We also confirm previous findings that the field stars which deviate from the
bulk of the empirical flux-flux relationships show evidence of youth.


title: Poisson kernel expansions for Schr\"odinger operators on trees

abstract:
  We study Schr\"odinger operators on trees and construct associated Poisson
kernels, in analogy to the laplacian on the unit disc. We show that in the
absolutely continuous spectrum, the generalized eigenfunctions of the operator
are generated by the Poisson kernel. We use this to define a "Fourier
transform", giving a Fourier inversion formula and a Plancherel formula, where
the domain of integration runs over the energy parameter and the geometric
boundary of the tree.


title:
Propagation phenomena in monostable integro-differential equations:
  acceleration or not?

abstract:
  We consider the homogeneous integro-differential equation$\partial \_t
u=J*u-u+f(u)$ with a monostable nonlinearity $f$. Our interest is twofold: we
investigate the existence/non existence of travelling waves, and the
propagation properties of the Cauchy problem.When the dispersion kernel $J$ is
exponentially bounded, travelling waves are known to exist and solutions of the
Cauchy problem typically propagate at a constant speed \cite{Schumacher1980},
\cite{Weinberger1982}, \cite{Carr2004}, \cite{Coville2007a},
\cite{Coville2008a}, \cite{Yagisita2009}. %When the dispersion kernel $J$ is
exponentially bounded, travelling waves are known to exist when $f$ belongs to
one of the three main class of non-linearities (bistable, ignition or
monostable), and solutions of the Cauchy problem typically propagate at a
constant speed \cite{Schumacher1980},
\cite{Wei-82},\cite{Bates1997},\cite{Chen1997}, \cite{Carr2004},
\cite{Coville2007a}, \cite{Coville2008a}, \cite{Yagisita2009,Yagisita2009a}. On
the other hand, when the dispersion kernel $J$ has heavy tails and the
non-linearity $f$ is non degenerate, i.e $f'(0)\textgreater{}0$, travelling
waves do not exist and solutions of the Cauchy problem propagate by
accelerating \cite{Medlock2003}, \cite{Yagisita2009}, \cite{Garnier2011}. For a
general monostable non-linearity, a dichotomy between these two types of
propagation behaviour is still not known. The originality of our work is to
provide such dichotomy by studying the interplay between the tails of the
dispersion kernel and the Allee effect induced by the degeneracy of $f$, i.e.
$f'(0)=0$. First, for algebraic decaying kernels, we prove the exact separation
between existence and non existence of travelling waves. This in turn provides
the exact separation between non acceleration and acceleration in the Cauchy
problem. In the latter case, we provide a first estimate of the position of the
level sets of the solution.


title:
Pedestrian flows through a narrow doorway: Effect of individual
  behaviours on the global flow and microscopic dynamics

abstract:
  We study the dynamics of pedestrian evacuations through a narrow doorway by
means of controlled experiments. The influence of the pedestrians' behaviours
is investigated by prescribing a selfish attitude to a fraction c\_s of the
participants, while the others behave politely. Thanks to an original setup
enabling the re-injection of egressed participants into the room, the analysis
is conducted in a (macroscopically) quasi-stationary regime. We find that, as
c\_s is increased, the flow rate J rises, interpolating between published
values for egresses in normal conditions and measurements for competitive
evacuations. The dependence of several flow properties on the pedestrian
density $\rho$ at the door, independently of c\_s , suggests that
macroscopically the behavioural aspects could be subsumed under the density, at
least in our specific settings with limited crowd pressure. In particular,
under these conditions, J grows monotonically with $\rho$ up to "close-packing"
($\rho$ $\approx$ 9 pers/m${}^2$). The flow is then characterised
microscopically. Among other quantities, the time lapses between successive
escapes, the pedestrians' waiting times in front of the door, and their angles
of incidence are analysed statistically. In a nutshell, our main results show
that the flow is orderly for polite crowds, with narrowly distributed time
lapses between egresses, while for larger c\_s the flow gets disorderly and
vanishing time lapses emerge. For all c\_s , we find an alternation between
short and long time lapses, which we ascribe to a generalised zipper effect.
The average waiting time in the exit zone increases with its occupancy. The
disorder in the flow and the pressure felt by participants are also assessed.


title:
The Main Sequences of Starforming Galaxies and Active Galactic Nuclei at
  High Redshift

abstract:
  We provide a novel, unifying physical interpretation on the origin, the
average shape, the scatter, and the cosmic evolution for the main sequences of
starforming galaxies and active galactic nuclei at high redshift z $\gtrsim$ 1.
We achieve this goal in a model-independent way by exploiting: (i) the
redshift-dependent SFR functions based on the latest UV/far-IR data from
HST/Herschel, and re- lated statistics of strong gravitationally lensed
sources; (ii) deterministic evolutionary tracks for the history of star
formation and black hole accretion, gauged on a wealth of multiwavelength
observations including the observed Eddington ratio distribution. We further
validate these ingredients by showing their consistency with the observed
galaxy stellar mass functions and AGN bolometric luminosity functions at
different redshifts via the continuity equation approach. Our analysis of the
main sequence for high-redshift galaxies and AGNs highlights that the present
data are consistently interpreted in terms of an in situ coevolution scenario
for star formation and black hole accretion, envisaging these as local, time
coordinated processes.


title:
String field theory solution corresponding to constant background
  magnetic field

abstract:
  Following the method recently proposed by Erler and Maccaferri, we construct
solutions to the equation of motion of Witten's cubic string field theory,
which describe constant magnetic field background. We study the boundary
condition changing operators relevant to such background and calculate the
operator product expansions of them. We obtain solutions whose classical action
coincide with the Born-Infeld action.


title:
Translation of the paper `Mesures stationnaires et ferm'es invariants
  des espaces homog'enes I', by Y. Benoist and J.-F. Quint

abstract:
  A translation of the famous paper of Benoist and Quint, `Mesures
stationnaires et ferm\'es invariants des espaces homog\'enes I', Ann. Math. 174
(2011).


title:
The sharp lower bound of the lifespan of solutions to semilinear wave
  equations with low powers in two space dimensions

abstract:
  This paper is devoted to a proof of the conjecture in Takamura(2015) on the
lower bound of the lifespan of solutions to semilinear wave equations in two
space dimensions. The result is divided into two cases according to the total
integral of the initial speed.


title: On the automorphism groups of Frobenius Groups

abstract:
  This is one of a series papers which aim towards to solve the problem of
determining automorphism groups of Frobenius groups. This one solves the
problem in the case where the Frobenius kernels are elementary abelian and
Frobenius complements are cyclic.


title: $\left(\varphi_1, \varphi_2\right)-$Variational principle

abstract:
  In this paper we prove that if $X $ is a Banach space, then for every lower
semi-continuous bounded below function $f, $ there exists a $\left(\varphi_1,
\varphi_2\right)-$convex function $g, $ with arbitrarily small norm, such that
$f + g $ attains its strong minimum on $X. $ This result extends some of the
well-known varitional principles as that of Ekeland [18], that of
Borwein-Preiss [6] and that of Deville-Godefroy-Zizler [14, 15].


title:
Estimation of the critical behavior in an active colloidal system with
  Vicsek-like interactions

abstract:
  We study numerically the critical behavior of a modified, active
Asakura-Oosawa model for colloid-polymer mixtures. The colloids are modeled as
self-propelled particles with Vicsek-like interactions. This system undergoes
phase separation between a colloid-rich and a polymer-rich phase, whereby the
phase diagram depends on the strength of the Vicsek-like interactions.
Employing a subsystem-block-density distribution analysis, we determine the
critical point and make an attempt to estimate the critical exponents. In
contrast to the passive model, we find that the critical point is not located
on the rectilinear diameter. A first estimate of the critical exponents $\beta$
and $\nu$ is consistent with the underlying 3d-Ising universality class
observed for the passive model.


title:
Exploring a heavy charged Higgs using jet substructure in a fully
  hadronic channel

abstract:
  In the framework of the type-II Two Higgs Doublet Model (2HDM-II) a charged
Higgs search strategy is presented for the dominant production mode $gb
\rightarrow tH^\pm$ at the 14 TeV LHC. We consider the decay process which
includes $t \rightarrow bW^\pm$ and $H^\pm \rightarrow AW^\pm$, and a fully
hadronic final state consisting of $bb\bar{b}+\mbox{jets}+X$. Dictated by the
$b \rightarrow s\gamma$ constraints which render $M_{H^\pm} > 480$ GeV we study
two scenarios in which the charged Higgs mass is 750 GeV and the pseudoscalar
Higgs mass is 200 GeV and 500 GeV. In this mass scheme highly boosted final
state objects are expected and handled with jet substructure techniques which
also acts to suppress the standard model background. A detailed detector
analysis is performed, followed by a multivariate analysis involving many
kinematic variables to optimize signal to background significance. Finally the
LHC search sensitivities for the two scenarios are presented for various
integrated luminosities.


title: Physical properties of molecular clouds for the entire Milky Way disk

abstract:
  This study presents a catalog of 8107 molecular clouds that covers the entire
Galactic plane and includes 98% of the $^{12}$CO emission observed within
$b\pm5^\circ$. The catalog was produced using a hierarchical cluster
identification method applied to the result of a Gaussian decomposition of the
Dame et al. data. The total H$_2$ mass in the catalog is $1.2\times10^9
M_\odot$, in agreement with previous estimates. We find that 30% of the sight
lines intersect only a single cloud, with another 25% intersecting only two
clouds. The most probable cloud size is $R\sim30$ pc. We find that $M\propto
R^{2.2\pm0.2}$, with no correlation between the cloud surface density,
$\Sigma$, and $R$. In contrast with the general idea, we find a rather large
range of values of $\Sigma$, from 2 to $300 M_\odot$ pc$^{-2}$, and a
systematic decrease with increasing Galactic radius, $R_{\rm gal}$. The cloud
velocity dispersion and the normalization $\sigma_0=\sigma_v/R^{1/2}$ both
decrease systematically with $R_{\rm gal}$. When studied over the whole
Galactic disk, there is a large dispersion in the line width-size relation, and
a significantly better correlation between $\sigma_v$ and $\Sigma\,R$. The
normalization of this correlation is constant to better than a factor of two
for $R_{\rm gal}<20$ kpc. This relation is used to disentangle the ambiguity
between near and far kinematic distances. We report a strong variation of the
turbulent energy injection rate. In the outer Galaxy it may be maintained by
accretion through the disk and/or onto the clouds, but neither source can drive
the 100 times higher cloud-averaged injection rate in the inner Galaxy.


title: Some Combinatorial Aspects of Discrete Non-linear Population Dynamics

abstract:
  Motivated by issues arising in population dynamics, we consider the problem
of iterating a given analytic function a number of times. We use the celebrated
technique known as Carleman linearization that turns (for a certain class of
functions) this problem into simply taking the power of a real number. We
expand this method, showing in particular that it can be used for population
models with immigration, and we also apply it to the famous logistic map. We
also are able to give a number of results for the invariant density of this
map, some being related to the Carleman linearization.


title:
Architecture of the Andromeda: a quantitative analysis of clustering in
  the inner stellar halo

abstract:
  We present a quantitative measurement of the amount of clustering present in
the inner $\sim30$ kpc of the stellar halo of the Andromeda galaxy (M31). For
this we analyse the angular positions and radial velocities of the carefully
selected Planetary Nebulae (PNe) in the M31 stellar halo. We study the
cumulative distribution of pair-wise distances in angular position and line of
sight velocity space, and find that the M31 stellar halo contains substantially
more stars in the form of close pairs as compared to that of a featureless
smooth halo. In comparison to a smoothed/scrambled distribution we estimate
that the clustering excess in the M31 inner halo is roughly $40\%$ at maximum
and on average $\sim 20\%$. Importantly, comparing against the 11 stellar halo
models of \cite{2005ApJ...635..931B}, which were simulated within the context
of the $\Lambda{\rm CDM}$ cosmological paradigm, we find that the amount of
substructures in the M31 stellar halo closely resembles that of a typical
$\Lambda{\rm CDM}$ halo.


title:
A Local-Global Equality on Every Affine Variety Admitting Points in an
  Arbitrary Rank-One Subgroup of a Global Function Field

abstract:
  For every affine variety over a global function field, we show that the set
of its points with coordinates in an arbitrary rank-one multiplicative subgroup
of this function field is topologically dense in the set of its points with
coordinates in the topological closure of this subgroup in the product of the
multiplicative group of those local completions of this function field over all
but finitely many places.


title: Risk-Sensitive Stopping Problems for Continuous-Time Markov Chains

abstract:
  In this paper we consider stopping problems for continuous-time Markov chains
under a general risk-sensitive optimization criterion for problems with finite
and infinite time horizon. More precisely our aim is to maximize the certainty
equivalent of the stopping reward minus cost over the time horizon. We derive
optimality equations for the value functions and prove the existence of optimal
stopping times. The exponential utility is treated as a special case. In
contrast to risk-neutral stopping problems it may be optimal to stop between
jumps of the Markov chain. We briefly discuss the influence of the risk
sensitivity on the optimal stopping time and consider a special house selling
problem as an example.


title:
The HADES RV Programme with HARPS-N@TNG IV. Time resolved analysis of
  the Ca ii H&K and H{\alpha} chromospheric emission of low-activity early-type
  M dwarfs

abstract:
  M dwarfs are prime targets for planet search programs, particularly of those
focused on the detection and characterization of rocky planets in the habitable
zone. Understanding their magnetic activity is important because it affects our
ability to detect small planets, and it plays a key role in the
characterization of the stellar environment. We analyze observations of the Ca
II H&K and H{\alpha} lines as diagnostics of chromospheric activity for
low-activity early-type M dwarfs. We analyze the time series of spectra of 71
early-type M dwarfs collected for the HADES project for planet search purposes.
The HARPS-N spectra provide simultaneously the H&K doublet and the H{\alpha}
line. We develop a reduction scheme able to correct the HARPS-N spectra for
instrumental and atmospheric effects, and to provide flux-calibrated spectra in
units of flux at the stellar surface. The H&K and H{\alpha} fluxes are compared
with each other, and their variability is analyzed. We find that the H and K
flux excesses are strongly correlated with each other, while the H{\alpha} flux
excess is generally less correlated with the H&K doublet. We also find that
H{\alpha} emission does not increase monotonically with the H&K line flux,
showing some absorption before being filled in by chromospheric emission when
H&K activity increases. Analyzing the time variability of the emission fluxes,
we derive a tentative estimate of the rotation period (of the order of a few
tens of days) for some of the program stars, and the typical lifetime of
chromospheric active regions (a few stellar rotations). Our results are in good
agreement with previous studies. In particular, we find evidence that the
chromospheres of early-type M dwarfs could be characterized by different
filaments coverage, affecting the formation mechanism of the H{\alpha} line. We
also show that chromospheric structure is likely related to spectral type.


title: Loop space construction of bigraphs and box complexes

abstract:
  Dochtermann introduced the loop space construction of a based graph $(G,v)$
whose basepoint is a looped vertex. He showed that the complex $C(\Omega(G,v))$
is homotopy equivalent to the loop space $\Omega(C(G),v)$ of $C(G)$. Here we
write $C(G)$ to mean the clique complex of the maximal reflexive subgraph of
$G$. In this paper, we consider its bigraph version. A bigraph is a graph
equipped with its 2-coloring. We introduce the loop space construction
$\Omega_{/K_2}(X,x)$ of a based bigraph $(X,x)$. This is a graph such that
$C(\Omega_{/K_2}(X,x))$ is homotopy equivalent to the loop space of the box
complex $B_{/K_2}(X)$ of the bigraph. As a result, we have alternative proofs
of some results of Matsushita and Schultz.


title: Learning Determinantal Point Processes in Sublinear Time

abstract:
  We propose a new class of determinantal point processes (DPPs) which can be
manipulated for inference and parameter learning in potentially sublinear time
in the number of items. This class, based on a specific low-rank factorization
of the marginal kernel, is particularly suited to a subclass of continuous DPPs
and DPPs defined on exponentially many items. We apply this new class to
modelling text documents as sampling a DPP of sentences, and propose a
conditional maximum likelihood formulation to model topic proportions, which is
made possible with no approximation for our class of DPPs. We present an
application to document summarization with a DPP on $2^{500}$ items.


title:
Unified Functorial Signal Representation I: From Grothendieck fibration
  to Base structured categories

abstract:
  In this paper we study categories $(F,\mathbf{C},\mathbf{D})$ and
$(\mathbb{F},\mathbf{C},\mathbf{Set})$ and prove them to be fibred on
$\mathbf{C}$. Then we examine Grothendieck construction in the context of an
ordinary functor $F: \mathbf{C} \rightarrow \mathbf{D}$ through the concept of
trivial categorification, using an appropriate functor $\mathbf{F}: \mathbf{C}
\xrightarrow{F} \mathbf{D} \xrightarrow{I} \mathbf{Cat}$ to construct
$\int_{\mathbf{C}^{op}} \bar{\mathbf{F}}$. This category characterizes a
functor as an abstract right category action while its dual $\mathcal{X}
\rtimes_{\mathbf{F}} \mathbf{C}$ or $(\int_{\mathbf{C}^{op}}
\bar{\mathbf{F}})^{op}$ characterizes a functor as an abstract left category
action. Similarly using $\mathbb{F}: \mathbf{C} \xrightarrow{F} \mathbf{D}
\xrightarrow{U} \mathbf{Set}$ we define $\mathcal{X} \rtimes_{\mathbb{F}}
\mathbf{C}$ and ${\int_{\mathbf{C}^{op}} \bar{\mathbb{F}}}$ as categories
denoting concrete left and right actions of $\mathbf{C}$ respectively.
Collectively referred to as `base structured categories', these are proven
abstractly isomorphic to the base category $\mathbf{C}$ but concretely
isomorphic to each other or $(\mathbb{F},\mathbf{C},\mathbf{Set}) \cong
\int_{\mathbf{C}} \bar{\mathbb{F}} \cong \mathcal{X} \rtimes_{\mathbb{F}}
\mathbf{C}$. These are special instances of fibred categories where the base
category is $\mathbf{C}$ and fibres are $\mathbf{D}$ objects being treated as
trivial categories. The perspective of making only base structure explicit
through category theory concealing the vertical structure using identity
morphisms enables one to combine intuitions of Grothendieck's relative and
Leyton's generative theory. As explored further, it facilitates the application
of functors in certain fundamental applications which hitherto have been
treating objects of category $\mathbf{D}$ purely in a set theoretic way.


title:
Effects of interplay of nanoparticles, surfactants and base fluid on the
  interfacial tension of nanocolloids

abstract:
  A systematically designed study has been conducted to understand and clearly
demarcate the degree of contribution by the constituting elements to the
surface tension of nanocolloids. The effects of elements such as surfactants,
particles and the combined effects of these on the interfacial tension of these
complex fluids are studied employing pendant drop shape analysis method by
fitting Young Laplace equation. Only particle has shown considerable increase
in surface tension with particle concentration in a polar medium like DI water
whereas only marginal effect particles on surface tension in weakly polar
mediums like glycerol and ethylene glycol. Such behaviour has been attributed
to the enhanced desorption of particles to the interface and a mathematical
framework has been derived to quantify this. Combined particle and surfactant
effect on surface tension of complex nanofluid system showed a decreasing
behaviour with respect to the particle and surfactant concentration with a
considerably feeble effect of particle concentration. This combined colloidal
system recorded a surface tension value below the surface tension of aqueous
surfactant system at the same concentration, which is a counterintuitive
observation as only particle results in increase in surface tension and only
surfactant results in decrease in surface tension. The possible physical
mechanism behind such an anomaly happening at the complex fluid air interface
has been explained. Detailed analyses based on thermodynamic, mechanical and
chemical equilibrium of the constituents and their adsorption-desorption
characteristics as extracted from Gibbs adsorption analysis has been provided.

categories: cond-mat.soft cond-mat.mes-hall physics.chem-ph physics.flu-dyn


title: Almost periodic functions and hyperbolic counting

abstract:
  In this paper we prove the existence of asymptotic moments, and an estimate
on the tails of the limiting distribution, for a specific class of almost
periodic functions. Then we introduce the hyperbolic circle problem, proving an
estimate on the asymptotic variance of the remainder that improves a result of
Chamizo. Applying the results of the first part we prove the existence of
limiting distribution and asymptotic moments for three functions that are
integrated versions of the remainder, and were considered originally (with due
adaptations to our settings) by Wolfe, Phillips and Rudnick, and Hill and
Parnovski.


title: An automatic bad band preremoval algorithm for hyperspectral imagery

abstract:
  For most hyperspectral remote sensing applications, removing bad bands, such
as water absorption bands, is a required preprocessing step. Currently, the
commonly applied method is by visual inspection, which is very time-consuming
and it is easy to overlook some noisy bands. In this study, we find an inherent
connection between target detection algorithms and the corrupted band removal.
As an example, for the matched filter (MF), which is the most widely used
target detection method for hyperspectral data, we present an automatic
MF-based algorithm for bad band identification. The MF detector is a filter
vector, and the resulting filter output is the sum of all bands weighted by the
MF coefficients. Therefore, we can identify bad bands only by using the MF
filter vector itself, the absolute value of whose entry accounts for the
importance of each band for the target detection. For a specific target of
interest, the bands with small MF weights correspond to the noisy or bad ones.
Based on this fact, we develop an automatic bad band preremoval algorithm by
utilizing the average absolute value of MF weights for multiple targets within
a scene. Experiments with three well known hyperspectral datasets show that our
method can always identify the water absorption and other low signal-to-noise
(SNR) bands that are usually chosen as bad bands manually.


title: On uniform flag bundles on Fano manifolds

abstract:
  As a natural extension of the theory of uniform vector bundles on Fano
manifolds, we consider uniform principal bundles, and study them by means of
the associated flag bundles, as their natural projective geometric
realizations. In this paper we develop the necessary background, and prove some
theorems that are flag bundle counterparts of some of the central results in
the theory of uniform vector bundles.