title:
A Generic Coordinate Descent Framework for Learning from Implicit
  Feedback

abstract:
  In recent years, interest in recommender research has shifted from explicit
feedback towards implicit feedback data. A diversity of complex models has been
proposed for a wide variety of applications. Despite this, learning from
implicit feedback is still computationally challenging. So far, most work
relies on stochastic gradient descent (SGD) solvers which are easy to derive,
but in practice challenging to apply, especially for tasks with many items. For
the simple matrix factorization model, an efficient coordinate descent (CD)
solver has been previously proposed. However, efficient CD approaches have not
been derived for more complex models.
  In this paper, we provide a new framework for deriving efficient CD
algorithms for complex recommender models. We identify and introduce the
property of k-separable models. We show that k-separability is a sufficient
property to allow efficient optimization of implicit recommender problems with
CD. We illustrate this framework on a variety of state-of-the-art models
including factorization machines and Tucker decomposition. To summarize, our
work provides the theory and building blocks to derive efficient implicit CD
algorithms for complex recommender models.


title: Tornado-Like Evolution of A Kink-Unstable Solar Prominence

abstract:
  We report on the tornado-like evolution of a quiescent prominence on 2014
November 1. The eastern section of the prominence first rose slowly
transforming into an arch-shaped structure as high as ~150 Mm above the limb;
the arch then writhed moderately in a left-handed sense, while the originally
dark prominence material became in emission in the Fe IX 171~{\AA} passband,
and a braided structure appeared at the eastern edge of the warped arch. The
unraveling of the braided structure was associated with a transient brightening
in EUV and apparently contributed to the formation of a curtain-like structure
(CLS). The CLS consisted of myriads of thread-like loops rotating
counterclockwise about the vertical if viewed from above. Heated prominence
material was observed to slide along these loops and land outside the filament
channel. The tornado was eventually disintegrated and the remaining material
flew along a left-handed helical path of approximately a full turn, as
corroborated through stereoscopic reconstruction, into the cavity of the
stable, western section of the prominence. We suggest that the tornado-like
evolution of the prominence was governed by the helical kink instability, and
that the CLS formed through magnetic reconnections between the prominence field
and the overlying coronal field.


title: An Epidemiological Model of Malaria Accounting for Asymptomatic Carriers

abstract:
  Asymptomatic individuals in the context of malarial disease refers to
subjects who carry a parasite load but do not show clinical symptoms. A correct
understanding of the influence of asymptomatic individuals on transmission
dynamics will provide a comprehensive description of the complex interplay
between the definitive host (female \textit{Anopheles} mosquito), intermediate
host (human) and agent (\textit{Plasmodium} parasite). The goal of this article
is to conduct a rigorous mathematical analysis of a new compartmentalized
malaria model accounting for asymptomatic human hosts for the purpose of
calculating the basic reproductive number ($\mathcal{R}_0$), and determining
the bifurcations that might occur at the onset of disease free equilibrium. A
point of departure of this model from others appearing in literature is that
the asymptomatic compartment is decomposed into two mutually disjoint
sub-compartments by making use of the naturally acquired immunity (NAI) of the
population under consideration. After deriving the model, a qualitative
analysis is carried out to classify the stability of the equilibria of the
system. Our results show that the dynamical system is locally asymptotically
stable provided that $\mathcal{R}_0<1$. However this stability is not global,
owning to the occurrence of a sub-critical bifurcation in which additional
non-trivial sub-threshold equilibrium solutions appear in response to a
specified parameter being perturbed. To ensure that the model does not undergo
a backward bifurcation, we demand that an auxiliary parameter denoted
$\Lambda<1$ in addition to the threshold constraint $\mathcal{R}_0<1$. The
authors hope that this qualitative analysis will fill in the gaps of what is
currently known about asymptomatic malaria and aid in designing strategies that
assist the further development of malaria control and eradication efforts.


title: Results from Electron-Positron Collisions at BESIII

abstract:
  A selection of results from electron-positron collisions at BESIII are
reviewed. The results presented here illustrate the wide range of physics
topics that can be studied using the Beijing Electron Positron Collider~(BEPC).
At low collision energies, the cross section for $e^+e^-\to \pi^+\pi^-$
provides much-needed input into theoretical calculations of the anomalous
magnetic moment of the muon, and the reaction $e^+e^-\to p\bar{p}$ provides
access to the electromagnetic form factors of the proton. In the charmonium
region, a large sample of $\psi^\prime$ decays can be used to measure new decay
modes of charmonium states. And at higher energies, BESIII is uniquely situated
to explore questions concerning the still-unexplained $XYZ$ states.


title:
Pseudoscalar condensation induced by chiral anomaly and vorticity for
  massive fermions

abstract:
  We derive the pseudoscalar condensate induced by anomaly and vorticity from
the Wigner function for massive fermions in homogeneous electromagnetic fields.
It has an anomaly term and a force-vorticity coupling term. As a mass effect,
the pseudoscalar condensate is linearly proportional to the fermion mass in
small mass expansion. By a generalization to two-flavor and three-flavor cases,
the neutral pion and eta meson condensates are calculated from the Wigner
function and have anomaly parts as well as force-vorticity parts, in which the
anomaly part of the neutral pion condensate is consistent to the previous
result. We also discuss about possible observables of the condensates in heavy
ion collisions such as collective flows of neutral pions and eta mesons which
may be influenced by the electromagnetic field and vorticity profiles.


title:
The high-redshift evolution of the Red Sequence scatter from joint
  simulations and HAWK-I Cluster Survey

abstract:
  We study the evolution of the Red Sequence (RS) scatter in galaxy clusters
and groups simultaneously using predictions from our simulations (cosmological
hydrodynamic + semi-analytical) as well as observational data from the HAWK-I
Cluster Survey (HCS), a sample of galaxy clusters at redshifts $0.8 < z < 1.5$.
We analyze the intrinsic scatter of the RS to investigate whether the stellar
age can be its main effective driver, at the same time assessing the role of
metallicity variations in shaping the RS building at around epoch $z\sim$1 and
beyond. To this purpose we rely on various methods to derive the average age
and age spread from the RS colour scatter of the HCS sample, with the aid of
population synthesis models. The RS scatter predicted by the models at $z< 0.7$
is found to not depend on the star formation history adopted, whilst at $z>the
correlation found between age and rest-frame colour scatters is quite robust,
although all age scatter estimations ultimately depend on the definition of RS
as well as on the completeness limits adopted. We find that the age spread of
RS galaxies predicted by both hydrodynamical simulations and SAM increases with
cosmic epoch, while the ratio between the age spread and the average age
remains approximately constant. Both trends are in agreement with observational
results from both the HCS and other literature samples.


title: Boyle's Conjecture and perfect localizations

abstract:
  In this article we study the behavior of left QI-rings under perfect
localizations. We show that a perfect localization of a left QI-ring is a left
QI-ring. We prove that Boyle's conjecture is true for left QI-rings with finite
Gabriel dimension such that the hereditary torsion theory generated by
semisimple modules is perfect. As corollary we get that Boyle's conjecture is
true for left QI-rings which satisfy the restricted left socle condition, this
result was proved first by C. Faith in \cite{faithhereditary}.


title:
A note on o-minimal flows and the Ax--Lindemann--Weierstrass theorem for
  abelian varieties over $\mathbb{C}$

abstract:
  In this short note we present an elementary proof of the
Ax-Lindemann-Weierstrass theorem for abelian and semi-abelian varieties. The
proof uses ideas of Pila, Ullmo, Yafaev, Zannier and is based on basic
properties of sets definable in o-minimal structures. It does not use the
Pila-Wilkie counting theorem.


title: Surface orbitronics: new twists from orbital Rashba physics

abstract:
  When the inversion symmetry is broken at a surface, spin-orbit interaction
gives rise to spin-dependent energy shifts - a phenomenon which is known as the
spin Rashba effect. Recently, it has been recognized that an orbital
counterpart of the spin Rashba effect - the orbital Rashba effect - can be
realized at surfaces even without spin- orbit coupling. Here, we propose a
mechanism for the orbital Rashba effect based on sp orbital hybridization,
which ultimately leads to the electric polarization of surface states. As a
proof of principle, we show from first principles that this effect leads to
chiral orbital textures in $\mathbf{k}$-space of the BiAg$_2$ monolayer. In
predicting the magnitude of the orbital moment arising from the orbital Rashba
effect, we demonstrate the crucial role that the Berry phase theory plays for
the magnitude and variation of the orbital textures. As a result, we predict a
pronounced manifestation of various orbital effects at surfaces, and proclaim
the orbital Rashba effect to be a key platform for surface orbitronics.


title: Observations of gravity-capillary lump interactions

abstract:
  In this experimental study, we investigate the interaction of
gravity-capillary solitary waves generated by two surface pressure sources
moving side by side at constant speed. The nonlinear response of a water
surface to a single source moving at a speed just below the minimum phase speed
of linear gravity-capillary waves in deep water ($c_{min}\approx23$ cm
s$^{-1}$) consists of periodic generation of pairs of three-dimensional
solitary waves (or lumps) in a V-shaped pattern downstream of the source. In
the reference frame of the laboratory, these unsteady lumps propagate in a
direction oblique to the motion of the source. In the present experiments, the
strengths of the two sources are adjusted to produce nearly identical responses
and the free-surface deformations are visualized using photography-based
techniques. The first lumps generated by the two sources move in intersecting
directions that make a half angle of approximately 15 degrees and collide in
the centerplane between the sources. A steep depression is formed during the
collision, but this depression quickly decreases in amplitude while radiating
small-amplitude radial waves. After the collision, a quasi-stable pattern is
formed with several rows of localized depressions that are qualitatively
similar to lumps but exhibit periodic amplitude oscillations, similar to a
breather. The shape of the wave pattern and the period of oscillations depend
strongly on the distance between the sources.


title: Computations of the Structure of the Goldman Lie Algebra for the Torus

abstract:
  We consider the structure of the Goldman Lie algebra for the closed torus,
and show that it is finitely generated over the rationals. We also consider
other traditional Lie algebra structures and determine that the Goldman Lie
algebra for the torus is not nilpotent or solvable, and we compute the derived
Lie algebra.


title:
Virtual Breakdown Mechanism: Field-Driven Splitting of Pure Water for
  Hydrogen Production

abstract:
  Due to the low conductivity of pure water, using an electrolyte is common for
achieving efficient water electrolysis. In this paper, we have broken through
this common sense by using deep-sub-Debye-length nanogap electrochemical cells
for the electrolysis of pure water. At such nanometer scale, the field-driven
pure water splitting exhibits a completely different mechanism from the
macrosystem. We have named this process 'virtual breakdown mechanism' that
results in a series of fundamental changes and more than 10^5-fold enhancement
of the equivalent conductivity of pure water. This fundamental discovery has
been theoretically discussed in this paper and experimentally demonstrated in a
group of electrochemical cells with nanogaps between two electrodes down to 37
nm. Based on our nanogap electrochemical cells, the electrolysis current from
pure water is comparable to or even larger than the current from 1 mol/L sodium
hydroxide solution, indicating the high-efficiency of pure water splitting as a
potential for on-demand hydrogen production.


title: Machine Learning of Accurate Energy-Conserving Molecular Force Fields

abstract:
  Using conservation of energy - a fundamental property of closed classical and
quantum mechanical systems - we develop an efficient gradient-domain machine
learning (GDML) approach to construct accurate molecular force fields using a
restricted number of samples from ab initio molecular dynamics (AIMD)
trajectories. The GDML implementation is able to reproduce global potential
energy surfaces of intermediate-sized molecules with an accuracy of 0.3 kcal
$\text{mol}^{-1}$ for energies and 1 kcal $\text{mol}^{-1}$ $\text{\AA}^{-1}$
for atomic forces using only 1000 conformational geometries for training. We
demonstrate this accuracy for AIMD trajectories of molecules, including
benzene, toluene, naphthalene, ethanol, uracil, and aspirin. The challenge of
constructing conservative force fields is accomplished in our work by learning
in a Hilbert space of vector-valued functions that obey the law of energy
conservation. The GDML approach enables quantitative molecular dynamics
simulations for molecules at a fraction of cost of explicit AIMD calculations,
thereby allowing the construction of efficient force fields with the accuracy
and transferability of high-level ab initio methods.


title: Constraints on generalized non-standard $tbW$ couplings

abstract:
  General non-standard $tbW$ couplings are studied as model independently as
possible based on the effective Lagrangian consisting of the dimension-6
operators, which is an extension of the standard-model Lagrangian. The
$tbW$-interaction Lagrangian in this framework includes four kinds of
couplings, which could be complex. Constraints on those non-standard $tbW$
couplings are obtained by comparing the experimental data related to the $t\to
b W$ process with the corresponding theoretical formulas derived from the
effective Lagrangian. The constraints on some sets of the non-standard
couplings are shown not to be so strong because those couplings balance out
each other as we treat all the non-standard couplings as complex numbers at the
same time.


title:
Forward-backward stochastic differential equations with monotone
  functionals and mean field games with common noise

abstract:
  In this paper, we consider a system of forward-backward stochastic
differential equations (FBSDEs) with monotone functionals. We show the
existence and uniqueness of such a system by the method of continuation
similarly to Peng and Wu (1999) for classical FBSDEs and obtain estimates under
conditional probability. As applications, we prove the well-posedness result
for a mean field FBSDE with conditional law and show the existence of a
decoupling function. In addition, we show that mean field games with common
noise are uniquely solvable under a linear controlled process with convex and
weak-monotone cost functions and prove that the optimal control is in a
feedback form depending only on the current state and conditional law.


title:
Remarks on Localizing Futaki-Morita Integrals At Isolated Degenerate
  Zeros

abstract:
  In this note we study the localization of Futaki-Morita integrals at isolated
degenerate zeros by giving a streamlined exposition in the spirit of Bott and
implement the localization procedure for a holomorphic vector field on $CP^n$
with a maximally degenerate zero, giving an essentially unique formula for the
Futaki-Morita integral invariants without using a summation over multiple
points. In a coming paper we will apply similar calculations to the
Calabi-Futaki invariant of a K\"ahler blowup.


title:
Spectral scalability as a result of geometrical self-similarity in
  fractal multilayers

abstract:
  The optical spectra of fractal multilayer dielectric structures have been
shown to possess spectral scalability, which has been found to be directly
related to the structure's spatial (geometrical) self-similarity. Phase and
amplitude scaling relations, as well as effects of finite structure size, have
been derived.


title:
Real-time kinematic positioning of LEO satellites using a
  single-frequency GPS receiver

abstract:
  Due to their low cost and low power consumption, single-frequency GPS
receivers are considered suitable for low-cost space applications such as small
satellite missions. Recently, requirements have emerged for real-time accurate
orbit determination at sub-meter level in order to carry out onboard geocoding
of high-resolution imagery, open-loop operation of altimeters and radio
occultation. This study proposes an improved real-time kinematic positioning
method for LEO satellites using single-frequency receivers. The C/A code and L1
phase are combined to eliminate ionospheric effects. The epoch-differenced
carrier phase measurements are utilized to acquire receiver position changes
which are further used to smooth the absolute positions. A kinematic Kalman
filter is developed to implement kinematic orbit determination. Actual flight
data from China small satellite SJ-9A are used to test the navigation
performance. Results show that the proposed method outperforms traditional
kinematic positioning method in terms of accuracy. A 3D position accuracy of
0.72 m and 0.79 m has been achieved using the predicted portion of IGS
ultra-rapid products and broadcast ephemerides, respectively.


title: Knowledge Enhanced Hybrid Neural Network for Text Matching

abstract:
  Long text brings a big challenge to semantic matching due to their
complicated semantic and syntactic structures. To tackle the challenge, we
consider using prior knowledge to help identify useful information and filter
out noise to matching in long text. To this end, we propose a knowledge
enhanced hybrid neural network (KEHNN). The model fuses prior knowledge into
word representations by knowledge gates and establishes three matching channels
with words, sequential structures of sentences given by Gated Recurrent Units
(GRU), and knowledge enhanced representations. The three channels are processed
by a convolutional neural network to generate high level features for matching,
and the features are synthesized as a matching score by a multilayer
perceptron. The model extends the existing methods by conducting matching on
words, local structures of sentences, and global context of sentences.
Evaluation results from extensive experiments on public data sets for question
answering and conversation show that KEHNN can significantly outperform
the-state-of-the-art matching models and particularly improve the performance
on pairs with long text.


title:
Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering:
  Determined by the OLYMPUS Experiment

abstract:
  The OLYMPUS collaboration reports on a precision measurement of the
positron-proton to electron-proton elastic cross section ratio, $R_{2\gamma}$,
a direct measure of the contribution of hard two-photon exchange to the elastic
cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams
were directed through a hydrogen gas target internal to the DORIS storage ring
at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and
time-of-flight scintillators detected elastically scattered leptons in
coincidence with recoiling protons over a scattering angle range of $\approx
20\degree$ to $80\degree$. The relative luminosity between the two beam species
was monitored using tracking telescopes of interleaved GEM and MWPC detectors
at $12\degree$, as well as symmetric M{\o}ller/Bhabha calorimeters at
$1.29\degree$. A total integrated luminosity of 4.5~fb$^{-1}$ was collected. In
the extraction of $R_{2\gamma}$, radiative effects were taken into account
using a Monte Carlo generator to simulate the convolutions of internal
bremsstrahlung with experiment-specific conditions such as detector acceptance
and reconstruction efficiency. The resulting values of $R_{2\gamma}$, presented
here for a wide range of virtual photon polarization $0.456<\epsilon<0.978$,
are smaller than some hadronic two-photon exchange calculations predict, but
are in reasonable agreement with a subtracted dispersion model and a
phenomenological fit to the form factor data.


title: Robust Matrix Regression

abstract:
  Modern technologies are producing datasets with complex intrinsic structures,
and they can be naturally represented as matrices instead of vectors. To
preserve the latent data structures during processing, modern regression
approaches incorporate the low-rank property to the model and achieve
satisfactory performance for certain applications. These approaches all assume
that both predictors and labels for each pair of data within the training set
are accurate. However, in real-world applications, it is common to see the
training data contaminated by noises, which can affect the robustness of these
matrix regression methods. In this paper, we address this issue by introducing
a novel robust matrix regression method. We also derive efficient proximal
algorithms for model training. To evaluate the performance of our methods, we
apply it to real world applications with comparative studies. Our method
achieves the state-of-the-art performance, which shows the effectiveness and
the practical value of our method.


title:
Intrinsic Geometric Information Transfer Learning on Multiple
  Graph-Structured Datasets

abstract:
  Graphs provide a powerful means for representing complex interactions between
entities. Recently, deep learning approaches are emerging for representing and
modeling graph-structured data, although the conventional deep learning methods
(such as convolutional neural networks and recurrent neural networks) have
mainly focused on grid-structured inputs (image and audio). Leveraged by the
capability of representation learning, deep learning based techniques are
reporting promising results for graph applications by detecting structural
characteristics of graphs in an automated fashion. In this paper, we attempt to
advance deep learning for graph-structured data by incorporating another
component, transfer learning. By transferring the intrinsic geometric
information learned in the source domain, our approach can help us to construct
a model for a new but related task in the target domain without collecting new
data and without training a new model from scratch. We thoroughly test our
approach with large-scale real corpora and confirm the effectiveness of the
proposed transfer learning framework for deep learning on graphs. According to
our experiments, transfer learning is most effective when the source and target
domains bear a high level of structural similarity in their graph
representations.


title:
Induced robust topological order on an ordinary insulator
  hetero-structured with a strong topological insulator

abstract:
  Topological states of matter originate from distinct topological electronic
structures of materials. As for strong topological insulators (STIs), the
topological surface (interface) is a direct consequence of electronic structure
transition between materials categorized to different topological genus.
Therefore, it is fundamentally interesting if such topological character can be
manipulated. Besides tuning the crystal field and the strength of spin-orbital
coupling (e.g., by external strain, or chemical doping), there is currently
rare report on topological state induced in ordinary insulators (OIs) by the
heterostructure of OI/STI. Here we report the observation of a Dirac cone
topological surface state (TSS) induced on the Sb2Se3 layer up to 15 nm thick
in the OI/STI heterostructure, in sharp contrast with the OI/OI heterostructure
where no sign of TSS can be observed. This is evident for an induced
topological state in an OI by heterostructure.


title: Similarity Search Combining Query Relaxation and Diversification

abstract:
  We study the similarity search problem which aims to find the similar query
results according to a set of given data and a query string. To balance the
result number and result quality, we combine query result diversity with query
relaxation. Relaxation guarantees the number of the query results, returning
more relevant elements to the query if the results are too few, while the
diversity tries to reduce the similarity among the returned results. By making
a trade-off of similarity and diversity, we improve the user experience. To
achieve this goal, we define a novel goal function combining similarity and
diversity. Aiming at this goal, we propose three algorithms. Among them,
algorithms genGreedy and genCluster perform relaxation first and select part of
the candidates to diversify. The third algorithm CB2S splits the dataset into
smaller pieces using the clustering algorithm of k-means and processes queries
in several small sets to retrieve more diverse results. The balance of
similarity and diversity is determined through setting a threshold, which has a
default value and can be adjusted according to users' preference. The
performance and efficiency of our system are demonstrated through extensive
experiments based on various datasets.


title: PointClouds: Distributing Points Uniformly on a Surface

abstract:
  The concept of a Point Cloud has played an increasingly important role in
many areas of Engineering, Science, and Mathematics. Examples are: LIDAR,
3D-Printing, Data Analysis, Computer Graphics, Machine Learning, Mathematical
Visualization, Numerical Analysis, and Monte Carlo Methods. Entering point
cloud into Google returns nearly 3.5 million results! A point cloud for a
finite volume manifold M is a finite subset or a sequence in M, with the
essential feature that it is a representative sample of M. The definition of a
point cloud varies with its use, particularly what constitutes being
representative. Point clouds arise in many different ways: in LIDAR they are
just 3D data captured by a scanning device, while in Monte Carlo applications
they are constructed using highly complex algorithms developed over many years.
In this article we outline a rigorous mathematical theory of point clouds,
based on the classic Cauchy Crofton formula of Integral Geometry and its
generalizations. We begin with point clouds on surfaces in R^3, which
simplifies the exposition and makes our constructions easily visualizable. We
proceed to hyper-surfaces and then sub-manifolds of arbitrary co-dimension in
R^n, and finally, using an elegant result of Jurgen Moser to arbitrary smooth
manifolds with a volume element.


title: DC Magnetometry at the $T_2$ Limit

abstract:
  Sensing static or slowly varying magnetic fields with high sensitivity and
spatial resolution is critical to many applications in fundamental physics,
bioimaging and materials science. Several versatile magnetometry platforms have
emerged over the past decade, such as electronic spins associated with Nitrogen
Vacancy (NV) centers in diamond. However, their high sensitivity to external
fields also makes them poor sensors of DC fields. Indeed, the usual method of
Ramsey magnetometry leaves them prone to environmental noise, limiting the
allowable interrogation time to the short dephasing time T2*. Here we introduce
a hybridized magnetometery platform, consisting of a sensor and ancilla, that
allows sensing static magnetic fields with interrogation times up to the much
longer T2 coherence time, allowing significant potential gains in field
sensitivity. While more generally applicable, we demonstrate the method for an
electronic NV sensor and a nuclear ancilla. It relies on frequency upconversion
of transverse DC fields through the ancilla, allowing quantum lock-in detection
with low-frequency noise rejection. In our experiments, we demonstrate
sensitivities better than 6uT/vHz, comparable to the Ramsey method, and
narrow-band signal noise filtering better than 64kHz. With technical
optimization, we expect more than an one order of magnitude improvement in each
of these parameters. Since our method measures transverse fields, in
combination with the Ramsey detection of longitudinal fields, it ushers in a
compelling technique for sensitive vector DC magnetometry at the nanoscale.


title: The norm of the Fourier transform on compact or discrete abelian groups

abstract:
  We calculate the norm of the Fourier operator from $L^p(X)$ to $L^q(\hat{X})$
when $X$ is an infinite locally compact abelian group that is, furthermore,
compact or discrete. This subsumes the sharp Hausdorff-Young inequality on such
groups. In particular, we identify the region in $(p,q)$-space where the norm
is infinite, generalizing a result of Fournier, and setting up a contrast with
the case of finite abelian groups, where the norm was determined by Gilbert and
Rzeszotnik. As an application, uncertainty principles on such groups expressed
in terms of R\'enyi entropies are discussed.


title: Asymmetric Dark Matter Models in SO(10)

abstract:
  We systematically study the possibilities for asymmetric dark matter in the
context of non-supersymmetric SO(10) models of grand unification. Dark matter
stability in SO(10) is guaranteed by a remnant $\mathbb{Z}_2$ symmetry which is
preserved when the intermediate scale gauge subgroup of SO(10) is broken by a
${\bf 126}$ dimensional representation. The asymmetry in the dark matter states
is directly generated through the out-of-equilibrium decay of particles around
the intermediate scale, or transferred from the baryon/lepton asymmetry
generated in the Standard Model sector by leptogenesis. We systematically
classify possible asymmetric dark matter candidates in terms of their quantum
numbers, and derive the conditions for each case that the observed dark matter
density is (mostly) explained by the asymmetry of dark matter particles.


title:
Reemergeing electronic nematicity in heavily hole-doped Fe-based
  superconductors

abstract:
  In correlated electrons system, quantum melting of electronic crystalline
phase often gives rise to many novel electronic phases. In cuprates
superconductors, melting the Mott insulating phase with carrier doping leads to
a quantum version of liquid crystal phase, the electronic nematicity, which
breaks the rotational symmetry and exhibits a tight twist with high-temperature
superconductivity. Recently, the electronic nematicity has also been observed
in Fe-based superconductors. However, whether it shares a similar scenario with
its cuprates counterpart is still elusive. Here, by measuring nuclear magnetic
resonance in CsFe2As2, a prototypical Fe-based superconductor perceived to have
evolved from a Mott insulating phase at 3d5 configuration, we report
anisotropic quadruple broadening effect as a direct result of local rotational
symmetry breaking. For the first time, clear connection between the Mott
insulating phase and the electronic nematicity can be established and
generalized to the Fe-based superconductors. This finding would promote a
universal understanding on electronic nematicity and its relation with
high-temperature superconductivity.


title:
Expected number of real roots for random linear combinations of
  orthogonal polynomials associated with radial weights

abstract:
  In this note, we obtain asymptotic expected number of real zeros for random
polynomials of the form $$f_n(z)=\sum_{j=0}^na^n_jc^n_jz^j$$ where $a^n_j$ are
independent and identically distributed real random variables with bounded
$(2+\delta)$th absolute moment and the deterministic numbers $c^n_j$ are
normalizing constants for the monomials $z^j$ within a weighted $L^2$-space
induced by a radial weight function satisfying suitable smoothness and growth
conditions.


title: Genomic Region Detection via Spatial Convex Clustering

abstract:
  Several modern genomic technologies, such as DNA-Methylation arrays, measure
spatially registered probes that number in the hundreds of thousands across
multiplechromosomes. The measured probes are by themselves less interesting
scientifically; instead scientists seek to discover biologically interpretable
genomic regions comprised of contiguous groups of probes which may act as
biomarkers of disease or serve as a dimension-reducing pre-processing step for
downstream analyses. In this paper, we introduce an unsupervised feature
learning technique which maps technological units (probes) to biological units
(genomic regions) that are common across all subjects. We use ideas from fusion
penalties and convex clustering to introduce a method for Spatial Convex
Clustering, or SpaCC. Our method is specifically tailored to detecting
multi-subject regions of methylation, but we also test our approach on the
well-studied problem of detecting segments of copy number variation. We
formulate our method as a convex optimization problem, develop a massively
parallelizable algorithm to find its solution, and introduce automated
approaches for handling missing values and determining tuning parameters.
Through simulation studies based on real methylation and copy number variation
data, we show that SpaCC exhibits significant performance gains relative to
existing methods. Finally, we illustrate SpaCC's advantages as a pre-processing
technique that reduces large-scale genomics data into a smaller number of
genomic regions through several cancer epigenetics case studies on subtype
discovery, network estimation, and epigenetic-wide association.


title:
Dipolar ordering and domains in crystals of Mn$_{12}$ Ac molecular
  magnets

abstract:
  Dipolar coupling in crystals of the Mn$_{12}$Ac molecular magnet elongated
along the anisotropy axis favors ferromagnetic ordering below the mean-field
Curie temperature 0.71 K. With the help of Monte Carlo on crystals of up to one
million Mn$_{12}$ molecules, it is shown that ordering occurs at 0.36 K. The
resulting state is split into ferromagnetic domains with domain walls
preferring the diagonal orientation. Domain walls are pinned by the lattice at
low temperatures. Making the crystal shorter makes domains finer and smoothens
out the singularity at the transition, decreasing susceptibility in the domain
state. Hysteresis loops look ferromagnetic for prolate crystals and
antiferromagnetic for oblate crystals.


title:
The quenched mass portion of star-forming galaxies and the origin of the
  star formation sequence slope

abstract:
  Observationally, a massive disk galaxy can harbor a bulge component that is
comparably inactive as a quiescent galaxy (QG). It has been speculated that the
quenched component contained in star-forming galaxies (SFGs) is the reason why
the star formation main sequence (MS) has a shallow slope at high masses. In
this paper, we present a toy model to quantify the quenched mass portion of
SFGs ($f_{\rm Q}$) at fixed stellar mass ($M_{\ast}$) and to reconcile the MS
slopes both in the low and the high mass regimes. In this model, each SFG is
composed by a star-forming plus a quenched component. The mass of the
star-forming component ($M_{\rm SF}$) correlates with the star formation rate
(SFR) following a relation SFR $\propto M_{\rm SF}^{\alpha_{\rm SF}}$, where
$\alpha_{\rm SF}\sim 1.0$ . The quenched component contributes to the stellar
mass but does not to the SFR. It is thus possible to quantify $f_{\rm Q}$ based
on the departure of the observed MS slope $\alpha$ from $\alpha_{\rm SF}$.
Adopting the redshift-dependent MS slope reported by \citet{Whitaker 2014}, we
explore the evolution of the $f_{\rm Q}-M_{\ast}$ relations over $z=[0.5,2.5]$.
We find that Milky-Way mass SFGs (with $M_{\ast}\approx 10^{10.7}M_{\odot}$)
typically have a $f_{\rm Q}=30\%-40\%$ at $z\sim 2.25$, whereas this value
rapidly rises up to $70\%-80\%$ at $z\sim 0.75$. The origin of an $\alpha\sim
1.0$ MS slope seen in the low mass regime is also discussed. We argue for a
scenario in which the majority of low mass SFGs stay in a "steady-stage" star
formation phase. In this phase, the SFR is mainly regulated by stellar feedback
and not significantly influenced by the quenching mechanisms, thus keeping
roughly constant over cosmic time. This scenario successfully produces an
$\alpha \sim 1.0$ MS slope, as well as the observed MS evolution from $z=2.5$
to $z=0$ at low masses.


title:
A low-mass-ratio and deep contact binary as the progenitor of the merger
  V1309 Sco

abstract:
  Nova Sco 2008 (=V1309 Sco) is an example of a V838 Mon type eruption rather
than a typical classical nova. This enigmatic object was recently shown to have
resulted from the merger of two stars in a contact binary. It is the first
stellar merger that was identified to be undergoing a common envelope
transient. To understand the properties of its binary progenitor, the
pre-outburst light curves were analyzed by using the W-D method. The
photometric solution of the 2002 light curve shows that it is a deep contact
binary (f = 89.5(+-40.5)%) with a mass ratio of 0.094. The asymmetry of the
light curve is explained by the presence of a dark spot on the more massive
component. The extremely high fill-out factor suggests that the merging of the
contact binary is driven by dynamical mass loss from the outer Lagrange point.
However, the analysis of the 2004 light curve indicates that no solutions were
obtained even at an extremely low mass ratio of q = 0.03. This suggests that
the common convective envelope of the binary system disappeared and the
secondary component spiraled into the envelope of the primary in 2004. Finally,
the ejection of the envelope of the primary produced the outburst.


title: A Formula about W-operator and Its Application to Hurwitz Number

abstract:
  W-operators are differential operators on the polynomial ring. Mironov,
Morosov and Natanzon construct the generalized Hurwitz numbers. They use the
W-operator to prove a formula for the generating function of the generalized
Hurwitz numbers. A special example of the W-operator is the cut-and-join
operator. Goulden and Jackson use the cut-and-join operator to calculate the
simple Hurwitz number. In this paper, we study the relation between W-operator
W([d]) and the central elements in Sn. Based on the relation we find, we give
another proof about a differential equation of the generating function of
d-Hurwitz number.


title: Errors-in-variables models with dependent measurements

abstract:
  Suppose that we observe $y \in \mathbb{R}^n$ and $X \in \mathbb{R}^{n \times
m}$ in the following errors-in-variables model: \begin{eqnarray*} y & = & X_0
\beta^* +\epsilon \\ X & = & X_0 + W, \end{eqnarray*} where $X_0$ is an $n
\times m$ design matrix with independent subgaussian row vectors, $\epsilon \in
\mathbb{R}^n$ is a noise vector and $W$ is a mean zero $n \times m$ random
noise matrix with independent subgaussian column vectors, independent of $X_0$
and $\epsilon$. This model is significantly different from those analyzed in
the literature in the sense that we allow the measurement error for each
covariate to be a dependent vector across its $n$ observations. Such error
structures appear in the science literature when modeling the trial-to-trial
fluctuations in response strength shared across a set of neurons.
  Under sparsity and restrictive eigenvalue type of conditions, we show that
one is able to recover a sparse vector $\beta^* \in \mathbb{R}^m$ from the
model given a single observation matrix $X$ and the response vector $y$. We
establish consistency in estimating $\beta^*$ and obtain the rates of
convergence in the $\ell_q$ norm, where $q = 1, 2$. We show error bounds which
approach that of the regular Lasso and the Dantzig selector in case the errors
in $W$ are tending to 0. We analyze the convergence rates of the gradient
descent methods for solving the nonconvex programs and show that the composite
gradient descent algorithm is guaranteed to converge at a geometric rate to a
neighborhood of the global minimizers: the size of the neighborhood is bounded
by the statistical error in the $\ell_2$ norm. Our analysis reveals interesting
connections between computational and statistical efficiency and the
concentration of measure phenomenon in random matrix theory. We provide
simulation evidence illuminating the theoretical predictions.


title:
An iterative local updating ensemble smoother for estimation and
  uncertainty assessment of hydrologic model parameters with multimodal
  distributions

abstract:
  Ensemble smoother (ES) has been widely used in inverse modeling of hydrologic
systems. However, for problems where the distribution of model parameters is
multimodal, using ES directly would be problematic. One popular solution is to
use a clustering algorithm to identify each mode and update the clusters with
ES separately. However, this strategy may not be very efficient when the
dimension of parameter space is high or the number of modes is large.
Alternatively, we propose in this paper a very simple and efficient algorithm,
i.e., the iterative local updating ensemble smoother (ILUES), to explore
multimodal distributions of model parameters in nonlinear hydrologic systems.
The ILUES algorithm works by updating local ensembles of each sample with ES to
explore possible multimodal distributions. To achieve satisfactory data matches
in nonlinear problems, we adopt an iterative form of ES to assimilate the
measurements multiple times. Numerical cases involving nonlinearity and
multimodality are tested to illustrate the performance of the proposed method.
It is shown that overall the ILUES algorithm can well quantify the parametric
uncertainties of complex hydrologic models, no matter whether the multimodal
distribution exists.


title:
Liquid-state acoustically-nonlinear nanoplasmonic source of optical
  frequency combs

abstract:
  Nonlinear acoustic interactions in liquids are effectively stronger than
nonlinear optical interactions in solids. Thus, harnessing these interactions
will offer new possibilities in the design of ultra-compact nonlinear photonic
devices. We theoretically demonstrate a hybrid, liquid-state and nanoplasmonic,
source of optical frequency combs compatible with fibre-optic technology. This
source relies on a nanoantenna to harness the strength of nonlinear acoustic
effects and synthesise optical spectra from ultrasound.


title: SIR Asymptotics in General Network Models

abstract:
  In the performance analyses of wireless networks, asymptotic quantities and
properties often pro- vide useful results and insights. The asymptotic analyses
become especially important when complete analytical expressions of the
performance metrics of interest are not available, which is often the case if
one departs from very specific modeling assumptions. In this paper, we consider
the asymptotics of the SIR distribution in general wireless network models,
including ad hoc and cellular networks, simple and non-simple point processes,
and singular and bounded path loss models, for which, in most cases, finding
analytical expressions of the complete SIR distribution seems hopeless. We show
that the lower tails of the SIR distributions decay polynomially with the order
solely determined by the path loss exponent or the fading parameter, while the
upper tails decay exponentially, with the exception of cellular networks with
singular path loss. In addition, we analyze the impact of the nearest
interferer on the asymptotic properties of the SIR distributions, and we
formulate three crisp conjectures that -if true- determine the asymptotic
behavior in many cases based on the large-scale path loss properties of the
desired signal and/or nearest interferer only.


title: Optimally Leveraging Density and Locality to Support LIMIT Queries

abstract:
  Existing database systems are not optimized for queries with a LIMIT
clause---operating instead in an all-or-nothing manner. In this paper, we
propose a fast LIMIT query evaluation engine, called NeedleTail, aimed at
letting analysts browse a small sample of the query results on large datasets
as quickly as possible, independent of the overall size of the result set.
NeedleTail introduces density maps, a lightweight in-memory indexing structure,
and a set of efficient algorithms (with desirable theoretical guarantees) to
quickly locate promising blocks, trading off locality and density. In settings
where the samples are used to compute aggregates, we extend techniques from
survey sampling to mitigate the bias in our samples. Our experimental results
demonstrate that NeedleTail returns results 4x faster on HDDs and 9x faster on
SSDs on average, while occupying up to 23x less memory than existing
techniques.


title:
High-Dimensional Stochastic Optimal Control using Continuous Tensor
  Decompositions

abstract:
  Motion planning and control problems are embedded and essential in almost all
robotics applications. These problems are often formulated as stochastic
optimal control problems and solved using dynamic programming algorithms.
Unfortunately, most existing algorithms that guarantee convergence to optimal
solutions suffer from the curse of dimensionality: the run time of the
algorithm grows exponentially with the dimension of the state space of the
system. We propose novel dynamic programming algorithms that alleviate the
curse of dimensionality in problems that exhibit certain low-rank structure.
The proposed algorithms are based on continuous tensor decompositions recently
developed by the authors. Essentially, the algorithms represent
high-dimensional functions (e.g., the value function) in a compressed format,
and directly perform dynamic programming computations (e.g., value iteration,
policy iteration) in this format. Under certain technical assumptions, the new
algorithms guarantee convergence towards optimal solutions with arbitrary
precision. Furthermore, the run times of the new algorithms scale polynomially
with the state dimension and polynomially with the ranks of the value function.
This approach realizes substantial computational savings in "compressible"
problem instances, where value functions admit low-rank approximations. We
demonstrate the new algorithms in a wide range of problems, including a
simulated six-dimensional agile quadcopter maneuvering example and a
seven-dimensional aircraft perching example. In some of these examples, we
estimate computational savings of up to ten orders of magnitude over standard
value iteration algorithms. We further demonstrate the algorithms running in
real time on board a quadcopter during a flight experiment under motion
capture.


title:
Induced representations of Hilbert modules over locally C*-algebras and
  the imprimitivity theorem

abstract:
  We study induced representations of Hilbert modules over locally C*-algebras
and their non-degeneracy. We show that if $V$ and $W$ are Morita equivalent
Hilbert modules over locally C*-algebras $A$ and $B$, respectively, then there
exists a bijective correspondence between equivalence classes of non-degenerate
representations of $V$ and $W$.


title:
Combinatorial Identities for Generalized Stirling Numbers Expanding
  $f$-Factorial Functions and the $f$-Harmonic Numbers

abstract:
  We introduce a class of $f(t)$-factorials, or $f(t)$-Pochhammer symbols, that
includes many, if not most, well-known factorial and multiple factorial
function variants as special cases. We consider the combinatorial properties of
the corresponding generalized classes of Stirling numbers of the first kind
which arise as the coefficients of the symbolic polynomial expansions of these
$f$-factorial functions. The combinatorial properties of these more general
parameterized Stirling number triangles we prove within the article include
analogs to known expansions of the ordinary Stirling numbers by $p$-order
harmonic number sequences through the definition of a corresponding class of
$p$-order $f$-harmonic numbers.


title: Recoverability of Joint Distribution from Missing Data

abstract:
  A probabilistic query may not be estimable from observed data corrupted by
missing values if the data are not missing at random (MAR). It is therefore of
theoretical interest and practical importance to determine in principle whether
a probabilistic query is estimable from missing data or not when the data are
not MAR. We present an algorithm that systematically determines whether the
joint probability is estimable from observed data with missing values, assuming
that the data-generation model is represented as a Bayesian network containing
unobserved latent variables that not only encodes the dependencies among the
variables but also explicitly portrays the mechanisms responsible for the
missingness process. The result significantly advances the existing work.


title:
Universal Berezinskii-Kosterlitz-Thouless dynamic scaling in the
  intermediate timerange in frustrated Heisenberg antiferromagnets on
  triangular lattice

abstract:
  We investigate non-equilibrium properties of the frustrated Heisenberg
antiferromagnets on the triangular lattice. Nonequilibrium critical relaxation
of frustrated Heisenberg antiferromagnets shows a dynamic transition (or, at
least, sharp crossover) at the same temperature $T_{\rm u}=0.282 J$ as for
static properties due to unbinding of $\mathbb{Z}_2$-vortices. We show that
starting from the high-temperature initial state, due to presence of
$\mathbb{Z}_2$-vortices in the considering system, in a broad temperature range
$T<T_{\rm u}$ the dynamic properties in the intermediate time range are similar
to those of two-dimensional XY model below Berezinskii-Kosterlitz-Thouless
transition. The interaction of $\mathbb{Z}_2$-vortices with spin-wave degrees
of freedom does not emerge until rather long times.


title: Groupoid equivariant prequantization

abstract:
  In their 2005 paper, C. Laurent-Gengoux and P. Xu define prequantization for
pre-Hamiltonian actions of quasi-presymplectic Lie groupoids in terms of
central extensions of Lie groupoids. The definition requires that the
quasi-presymplectic structure be exact (i.e. the closed 3-form on the unit
space of the Lie groupoid must be exact). In the present paper, we define
prequantization for pre-Hamiltonian actions of (not necessarily exact)
quasi-presymplectic Lie groupoids in terms of Dixmier-Douady bundles. The
definition is a natural adaptation of E. Meinrenken's treatment of
prequantization for quasi-Hamiltonian Lie group actions with group-valued
moment map. The definition given in this paper is shown to be compatible with
the definition of Laurent-Gengoux and Xu when the underlying
quasi-presymplectic structure is exact. Properties related to Morita invariance
and symplectic reduction are established.


title: Star-factors in graphs of high degree

abstract:
  We prove that every graph with sufficiently large minimum degree $d$ contains
a spanning forest in which every component is a star of size at least $\sqrt{d}
- \tilde O(d^{1/4})$. This improves the result of Alon and Wormald and is
optimal up to the lower order term.


title:
Feasibility study of SiGHT: a novel ultra low background photosensor for
  low temperature operation

abstract:
  Rare event search experiments, such as those searching for dark matter and
observations of neutrinoless double beta decay, require ultra low levels of
radioactive background for unmistakable identification. In order to reduce the
radioactive backgrounds of detectors used in these types of event searches, low
background photosensors are required, as the physical size of these detectors
become increasing larger, and hence the number of such photosensors used also
increases rapidly. Considering that most dark matter and neutrinoless double
beta decay experiments are turning towards using noble liquids as the target
choice, liquid xenon and liquid argon for instance, photosensors that can work
well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon
and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a
novel photosensor designed specifically for use in ultra low background
experiments operating at cryogenic temperatures. It is based on the proven
photocathode plus silicon photomultiplier (SiPM) hybrid technology and consists
of very few other, but also ultra radio-pure, materials like fused silica and
silicon for the SiPM. The introduction of the SiGHT concept, as well as a
feasibility study for its production, is reported in this paper.


title:
Correlation effect in Sr$_{1-x}$La$_x$RuO$_3$ studied by soft x-ray
  photoemission spectroscopy

abstract:
  To clarify how the electronic state of Sr1-xLaxRuO3 evolves with La doping,
we conducted photoemission (PES) experiments using soft x-rays. The spectral
shape of the Ru 4d derived peak near the Fermi level changes significantly with
increasing x. This variation indicates that a spectral weight transfer from the
coherent to incoherent component occurs due to an enhancement of the electron
correlation effect. Resonant PES experiments at the La 3d_{5/2} edge have
confirmed that there is no significant contribution of the La 5d state in the
energy range where the spectral weight transfer is observed. Using the
dependence of the photoelectron mean free path on the photon energy, we
subtracted the surface components from the PES spectra and confirmed that the
enhancement of the electron correlation effect with La doping is an intrinsic
bulk phenomenon. On the other hand, a large portion of the coherent component
remains at the Fermi level up to x = 0.5, reflecting that the Ru 4d state still
has itinerant characteristics. Moreover, we found that the PES spectra hardly
depend on the temperature and do not exhibit a discernible change with magnetic
ordering, suggesting that the temperature variation of the exchange splitting
does not follow the prediction of the Stoner theory. The presently obtained
experimental results indicate that the electron correlation effect plays an
important role in Sr1-xLaxRuO3 and that the Ru 4d electrons possess both local
and itinerant characteristics.


title:
Quantum Spin-quantum Anomalous Hall Effect with Tunable Edge States in
  Sb Monolayer-based Heterostructures

abstract:
  A novel topological insulator with tunable edge states, called quantum
spin-quantum anomalous Hall (QSQAH) insulator, is predicted in a
heterostructure of a hydrogenated Sb (SbH) monolayer on a LaFeO3 substrate by
using ab initio methods. The substrate induces a drastic staggered exchange
field in the SbH film, which plays an important role to generate the QSQAH
effect. A topologically nontrivial band gap (up to 35 meV) is opened by Rashba
spin-orbit coupling, which can be enlarged by strain and electric field. To
understand the underlying physical mechanism of the QSQAH effect, a
tight-binding model based on px and py orbitals is constructed. With the model,
the exotic behaviors of the edge states in the heterostructure are
investigated. Dissipationless chiral charge edge states related to one valley
are found to emerge along the both sides of the sample, while low-dissipation
spin edge states related to the other valley flow only along one side of the
sample. These edge states can be tuned flexibly by polarization-sensitive
photoluminescence controls and/or chemical edge modifications. Such flexible
manipulations of the charge, spin, and valley degrees of freedom provide a
promising route towards applications in electronics, spintronics, and
valleytronics.


title:
Displacement convexity for the entropy in semidiscrete nonlinear
  Fokker-Planck equations

abstract:
  The displacement $\lambda$-convexity of a nonstandard entropy with respect to
a nonlocal transportation metric in finite state spaces is shown using a
gradient flow approach. The constant $\lambda$ is computed explicitly in terms
of a priori estimates of the solution to a finite-difference approximation of a
nonlinear Fokker-Planck equation. The key idea is to employ a new mean
function, which defines the Onsager operator in the gradient flow formulation.


title:
#Exploration: A Study of Count-Based Exploration for Deep Reinforcement
  Learning

abstract:
  Count-based exploration algorithms are known to perform near-optimally when
used in conjunction with tabular reinforcement learning (RL) methods for
solving small discrete Markov decision processes (MDPs). It is generally
thought that count-based methods cannot be applied in high-dimensional state
spaces, since most states will only occur once. Recent deep RL exploration
strategies are able to deal with high-dimensional continuous state spaces
through complex heuristics, often relying on optimism in the face of
uncertainty or intrinsic motivation. In this work, we describe a surprising
finding: a simple generalization of the classic count-based approach can reach
near state-of-the-art performance on various high-dimensional and/or continuous
deep RL benchmarks. States are mapped to hash codes, which allows to count
their occurrences with a hash table. These counts are then used to compute a
reward bonus according to the classic count-based exploration theory. We find
that simple hash functions can achieve surprisingly good results on many
challenging tasks. Furthermore, we show that a domain-dependent learned hash
code may further improve these results. Detailed analysis reveals important
aspects of a good hash function: 1) having appropriate granularity and 2)
encoding information relevant to solving the MDP. This exploration strategy
achieves near state-of-the-art performance on both continuous control tasks and
Atari 2600 games, hence providing a simple yet powerful baseline for solving
MDPs that require considerable exploration.


title:
trlib: A vector-free implementation of the GLTR method for iterative
  solution of the trust region problem

abstract:
  We describe trlib, a library that implements a variant of Gould's Generalized
Lanczos method (Gould et al. in SIAM J. Opt. 9(2), 504-525, 1999) for solving
the trust region problem.
  Our implementation has several distinct features that set it apart from
preexisting ones. We implement both conjugate gradient (CG) and Lanczos
iterations for assembly of Krylov subspaces. A vector- and matrix-free reverse
communication interface allows the use of most general data structures, such as
those arising after discretization of function space problems. The hard case of
the trust region problem frequently arises in sequential methods for nonlinear
optimization. In this implementation, we made an effort to fully address the
hard case in an exact way by considering all invariant Krylov subspaces.
  We investigate the numerical performance of trlib on the full subset of
unconstrained problems of the CUTEst benchmark set. In addition to this,
interfacing the PDE discretization toolkit FEniCS with trlib using the
vector-free reverse communication interface is demonstrated for a family of
PDE-constrained control trust region problems adapted from the OPTPDE
collection.


title: On a Second Discretization of the ZS-AKNS Spectral Problem: Revisit

abstract:
  In this paper we revisit a discrete spectral problem which was proposed by
Ragnisco and Tu in 1989, as a second discretization of the ZS-AKNS spectral
problem. We show that the spectral problem corresponds to a bidirectional
discretization of the derivative of two wave functions $\phi_{1,x}$ and
$\phi_{2,x}$. As a connection with higher dimensional systems, the spectral
problem and a related hierarchy can be derived from Lax triads of the
differential-difference KP hierarchy via a symmetry constraint. Isospectral and
nonisospectral flows derived from the spectral problem compose a Lie algebra.
By considering its infinite dimensional subalgebras and continuum limit of
recursion operator, three semi-discrete AKNS hierarchies are constructed.


title:
Free energy of directed polymers in random environment in
  $1+1$-dimension at high temperature

abstract:
  We consider the free energy $F(\beta)$ of the directed polymers in random
environment in $1+1$-dimension. It is known that $F(\beta)$ is of order
$-\beta^4$ as $\beta\to 0$. In this paper, we will prove that under a certain
condition of the potential, \begin{align*} \lim_{\beta\to
0}\frac{F(\beta)}{\beta^4}=\lim_{T\to\infty}\frac{1}{T}P_{\mathcal{Z}}\left[\log
\mathcal{Z}_{\sqrt{2}}(T)\right] =-\frac{1}{6}, \end{align*} where
$\{\mathcal{Z}_\beta(t,x):t\geq 0,x\in\mathbb{R}\}$ is the unique mild solution
to the stochastic heat equation \begin{align*} \frac{\partial}{\partial
t}\mathcal{Z}=\frac{1}{2}\Delta \mathcal{Z}+\beta \mathcal{Z}{\dot{\mathcal
W}},\ \ \lim_{t\to 0}\mathcal{Z}(t,x)dx=\delta_{0}(dx), \end{align*} where
$\mathcal{W}$ is a time-space white noise and \begin{align*}
\mathcal{Z}_\beta(t)=\int_\mathbb{R}\mathcal{Z}_\beta(t,x)dx. \end{align*}


title:
Existence of supersingular reduction for families of K3 surfaces with
  large Picard number in positive characteristic

abstract:
  We study non-isotrivial families of $K3$ surfaces in positive characteristic
$p$ whose geometric generic fibers satisfy $\rho\geq21-2h$ and $h\geq3$, where
$\rho$ is the Picard number and $h$ is the height of the formal Brauer group.
We show that, under a mild assumption on the characteristic of the base field,
they have potential supersingular reduction. Our methods rely on Maulik's
results on moduli spaces of $K3$ surfaces and the construction of sections of
powers of Hodge bundles due to van der Geer and Katsura. For large $p$ and each
$2\leq{h}\leq10$, using deformation theory and Taelman's methods, we construct
non-isotrivial families of $K3$ surfaces satisfying $\rho=22-2h$.


title: Spin-Valley Beam Splitter in Graphene

abstract:
  The fourfold spin-valley degenerate degrees of freedom in bulk graphene can
support rich physics and novel applications associated with multicomponent
quantum Hall effects and linear conductance filtering. In this work, we study
how to break the spin-valley degeneracy of electron beams spatially. We propose
a spin-valley beam splitter in a gated ferromagnetic/pristine/strained graphene
structure. We demonstrate that, in a full resonant tunneling regime for all
spin-valley beam components, the formation of quasi-standing waves can lead
four giant lateral Goos-H\"{a}nchen shifts as large as the transverse beam
width, while the interplay of the two modulated regions can lead difference of
resonant angles or energies for the four spin-valley flavors, manifesting an
effective spin-valley beam splitting effect. The beam splitting effect is found
to be controllable by the gating and strain.


title:
Large-scale tidal effect on redshift-space power spectrum in a
  finite-volume survey

abstract:
  Long-wavelength matter inhomogeneities contain cleaner information on the
nature of primordial perturbations as well as the physics of the early
universe. The large-scale coherent overdensity and tidal force, not directly
observable for a finite-volume galaxy survey, are both related to the Hessian
of large-scale gravitational potential and therefore of equal importance. We
show that the coherent tidal force causes a homogeneous anisotropic distortion
of the observed distribution of galaxies in all three directions, perpendicular
and parallel to the line-of-sight direction. This effect mimics the
redshift-space distortion signal of galaxy peculiar velocities, as well as a
distortion by the Alcock-Paczynski effect. We quantify its impact on the
redshift-space power spectrum to the leading order, and discuss its importance
for the ongoing and upcoming galaxy surveys.


title:
Caffarelli-Kohn-Nirenberg type inequalities of fractional order with
  applications

abstract:
  Let $0<s<1$ and $p>1$ be such that $ps<N$. Assume that $\Omega$ is a bounded
domain containing the origin. Staring from the ground state inequality by R.
Frank and R. Seiringer we obtain: 1- The following improved Hardy inequality
for $p\ge 2$ For all $q<p$, there exists a positive constant $C\equiv C(\Omega,
q, N, s)$ such that
  $$ \int_{{\mathbb R}^N}\int_{{\mathbb R}^N} \,
\frac{|u(x)-u(y)|^{p}}{|x-y|^{N+ps}}\,dx\,dy - \Lambda_{N,p,s} \int_{{\mathbb
R}^N} \frac{|u(x)|^p}{|x|^{p}}\,dx\geq C
\int_{\Omega}\dint_{\Omega}\frac{|u(x)-u(y)|^p}{|x-y|^{N+qs}}dxdy $$ for all $u
\in \mathcal{C}_0^\infty({\mathbb R}^N)$. Here $\Lambda_{N,p,s}$ is the optimal
constant in the Hardy inequality.
  2- Define $p^*_{s}=\frac{pN}{N-ps}$ and let $\beta<\frac{N-ps}{2}$, then
\begin{equation*} \int_{{\mathbb R}^N}\int_{{\mathbb R}^N}
\frac{|u(x)-u(y)|^p}{|x-y|^{N+ps}|x|^{\beta}|y|^{\beta}} \,dy\,dx\ge
S(N,p,s,\beta)\Big(\int_{{\mathbb R}^N}
\frac{|u(x)|^{p^*_{s}}}{|x|^{2\beta\frac{p^*_s}{p}}}\,dx\Big)^{\frac{p}{p^*_{s}}},
\end{equation*} for all $u\in \mathcal{C}^\infty_0(\Omega)$ where $S\equiv
S(N,p,s,\beta)>0$.
  3- If $\beta\equiv \frac{N-ps}{2}$, as a consequence of the improved Hardy
inequality, we obtain that for all $q<p$, there exists a positive constant
$C(\Omega)$ such that \begin{equation*} \int_{{\mathbb R}^N}\int_{{\mathbb
R}^N} \dfrac{|u(x)-u(y)|^p}{|x-y|^{N+ps}|x|^{\beta}|y|^{\beta}} \,dy\,dx\ge
C(\Omega)\Big(\int_{\Omega} \frac{|u(x)|^{p^*_{s,q}}}{|x|^{2\beta
\frac{p^*_{s,q}}{p}}}\,dx\Big)^{\frac{p}{p^*_{s,q}}}, \end{equation*} for all
$u\in \mathcal{C}^\infty_0(\Omega)$ where $p^*_{s,q}=\frac{pN}{N-qs}$.
  \
  Notice that the previous inequalities can be understood as the fractional
extension of the Callarelli-Kohn-Nirenberg inequalities.


title:
On regularity and singularity for $L^\infty(0,T;L^{3,w}(\mathbb{R}^3))$
  solutions to the Navier-Stokes equations

abstract:
  We study local regularity properties of a weak solution $u$ to the Cauchy
problem of the incompressible Navier-Stokes equations. We present a new
regularity criterion for the weak solution $u$ satisfying the condition
$L^\infty(0,T;L^{3,w}(\mathbb{R}^3))$ without any smallness assumption on that
scale, where $L^{3,w}(\mathbb{R}^3)$ denotes the standard weak Lebesgue space.
As an application, we conclude that there are at most a finite number of blowup
points at any singular time $t$. The condition that the weak Lebesgue space
norm of the veclocity field $u$ is bounded in time is encompassing type I
singularity and significantly weaker than the end point case of the so-called
Ladyzhenskaya-Prodi-Serrin condition proved by
Escauriaza-Sergin-\v{S}ver\'{a}k.


title:
Superconducting gap structure in ambient-pressure-grown
  $\mathrm{LaO_{0.5}F_{0.5}BiS_{2}}$

abstract:
  We have performed transverse-field muon spin relaxation (TF-$\mu$SR)
measurements on ambient-pressure-grown polycrystalline
$\mathrm{LaO_{0.5}F_{0.5}BiS_{2}}$. From these measurements, no signature of
magnetic order is found down to 25 mK. The value of the magnetic penetration
depth extrapolated to 0 K is 0.89 (5) $\mu$m. The temperature dependence of
superconducting penetration depth is best described by either a multigap s +
s-wave model with $\Delta_{1}$ = 0.947 (7) meV and $\Delta_{2}$ = 0.22 (4) meV
or the ansiotropic s-wave model with $\Delta(0)$ = 0.776 meV and anisotropic
gap amplitude ratio $\Delta_{min}/\Delta_{max}$ = 0.34. Comparisons with other
potentially multigap $\mathrm{BiS_{2}}$-based superconductors are discussed. We
find that these $\mathrm{BiS_{2}}$-based superconductors, including
$\mathrm{Bi_{4}O_{4}S_3}$ and the high-pressure synthesized
$\mathrm{LaO_{0.5}F_{0.5}BiS_{2}}$, generally conform to the Uemura relation.


title:
Entanglement dynamics in critical random quantum Ising chain with
  perturbations

abstract:
  We simulate the entanglement dynamics in a critical random quantum Ising
chain with generic perturbations using the time-evolving block decimation
algorithm. Starting from a product state, we observe super-logarithmic growth
of entanglement entropy with time. The numerical result is consistent with the
analytical prediction of Vosk and Altman using a real-space renormalization
group technique.


title:
Spectroscopic evidence of Multiple Stellar Populations in Globular
  Clusters

abstract:
  Galactic globular clusters are not simple stellar populations. And nothing is
simple in their study, basically because we try to reconstruct chains of events
that occurred at redshift z > 2-3 by observing these objects at z=0, after a
Hubble time. Fortunately, spectroscopy offers a magnifying lens: differences of
tens or hundreds of Myrs between stellar generations are translated into
differences in abundances up to a full dex. I will review the complex pattern
emerging by the combined efforts of different groups, focusing on the chemical
signatures of multiple populations in globular clusters.


title:
The long-term centimeter variability of active galactic nuclei: A new
  relation between variability timescale and accretion rate

abstract:
  We study the long-term ($\approx$30 years) radio variability of 43 radio
bright AGNs by exploiting the data base of the University of Michigan Radio
Astronomy Observatory (UMRAO) monitoring program. We model the periodograms
(temporal power spectra) of the observed lightcurves as simple power-law noise
(red noise, spectral power $P(f)\propto f^{-\beta}$) using Monte Carlo
simulations, taking into account windowing effects (red-noise leak, aliasing).
The power spectra of 39 (out of 43) sources are in good agreement with the
models, yielding a range in power spectral index ($\beta$) from $\approx$1 to
$\approx$3. We fit a Gaussian function to each flare in a given lightcurve to
obtain the flare duration. We discover a correlation between $\beta$ and the
median duration of the flares. We use the derivative of a lightcurve to obtain
a characteristic variability timescale which does not depend on the assumed
functional form of the flares, incomplete fitting, and so on. We find that,
once the effects of relativistic Doppler boosting are corrected for, the
variability timescales of our sources are proportional to the accretion rate to
the power of $0.25\pm 0.03$ over five orders of magnitude in accretion rate,
regardless of source type. We further find that modeling the periodograms of
four of our sources requires the assumption of broken powerlaw spectra. From
simulating lightcurves as superpositions of exponential flares we conclude that
strong overlap of flares leads to featureless simple power-law periodograms of
AGNs at radio wavelengths in most cases.


title: The Gross Pitaevski map as a chaotic dynamical system

abstract:
  The Gross Pitaevski map is a discrete time, split operator version of the
Gross Pitaevski dynamics in the circle, for which exponential instability has
been recently reported. Here it is studied as a classical dynamical system in
its own right. A systematic analysis of Lyapunov exponents exposes strongly
chaotic behavior. Exponential growth of energy is then shown to be a direct
consequence of rotational invariance and for stationary solutions the full
spectrum of Lyapunov exponents is analytically computed. The present analysis
includes the resonant case, when the free rotation period is commensurate to
$2\pi$, and the map has countably many constants of the motion. Except for
lowest order resonances, this case exhibits an integrable-chaotic transition.


title:
Revisiting Studies of the Statistical Property of a Strong Gravitational
  Lens System and Model-independent Constraint on the Curvature of the Universe

abstract:
  In this paper we use a recently compiled data set, which comprises 118
galactic-scale strong gravitational lensing (SGL) systems to constrain the
statistic property of SGL system, as well as the curvature of universe without
assuming any fiducial cosmological model. Based on the singular isothermal
ellipsoid (SIE) model of SGL system, we obtain that the constrained curvature
parameter $\Omega_{\rm k}$ is close to zero from the SGL data, which is
consistent with the latest result of planck measurement. More interestingly, we
find that the parameter $f$ in the SIE model is strongly correlated with the
curvature $\Omega_{\rm k}$. Neglecting this correlation in the analysis will
significantly overestimate the constraining power of SGL data on the curvature.
Furthermore, the obtained constraint on $f$ is different from previous results:
$f=1.105\pm0.030$ ($68\%$ C.L.), which means that the standard singular
isothermal sphere (SIS) model ($f=1$) is disfavored by the current SGL data at
more than $3\sigma$ confidence level. We also divide the whole SGL data into
two parts according to the centric stellar velocity dispersion $\sigma_{\rm c}$
and find that the larger value of $\sigma_{\rm c}$ the subsample has, the more
favored the standard SIS model is. Finally, we extend the SIE model by assuming
the power-law density profiles for the total mass density,
$\rho=\rho_0(r/r_0)^{-\alpha}$, and luminosity density,
$\nu=\nu_0(r/r_0)^{-\delta}$, and obtain the constraints on the power-law
indexes: $\alpha=1.95\pm0.04$ and $\delta=2.40\pm0.13$ at 68\% confidence
level. When assuming the power-law index $\alpha=\delta=\gamma$, this scenario
is totally disfavored by the current SGL data, $\chi^2_{\rm min,\gamma} -
\chi^2_{\rm min,SIE} \simeq 53$.


title: Transversal Intersection and Sum of Polynomial Ideals

abstract:
  In this paper we derive some conditions for transversal intersection of
polynomial ideals. We exhibit some examples. Finally, as an application of the
results proved, we compute the Betti numbers for ideals of the form $I_{1}(XY)
+ J$, where $X$ and $Y$ are matrices and $J$ is the ideal generated by the
$2\times 2$ minors of the matrix consisting of any two rows of $X$.


title:
Site-specific reactivity of ethylene at distorted dangling bond
  configurations on Si(001)

abstract:
  We report differences in adsorption and reaction energetics for ethylene on
Si(001) with respect to different dangling bond configurations induced by
hydrogen precoverage as obtained via density functional theory calculations.
This can help to understand the influence of surface defects and precoverage on
the reactivity of organic molecules on semiconductor surfaces in general. Our
results show that the reactivity on surface dimers fully enclosed by hydrogen
covered atoms is essentially unchanged compared to the clean surface. This is
confirmed by our scanning tunnelling microscopy measurements. On the contrary,
adsorption sites with partially covered surface dimers show a drastic increase
in reactivity. This is due to a lowering of the reaction barrier by more than
fifty percent compared to the clean surface, which is in line with previous
experiments. Adsorption on dimers enclosed by molecule (ethylene) covered
surface atoms is reported to have a highly decreased reactivity, a result of
destabilization of the intermediate state due to steric repulsion, as
quantified with the periodic energy decomposition analysis (pEDA). Furthermore,
an approach for the calculation of Gibbs energies of adsorption based on
statistical thermodynamics considerations is applied to the system. The results
show that the loss in molecular entropy leads to a significant destabilization
of adsorption states.


title: Propagation of an Airy-Gaussian beam in defected photonic lattices

abstract:
  We investigate numerically that a finite Airy-Gaussian (AiG) beam varies its
trajectory and shape in the defected photonic lattices. The propagation
properties and beam self-bending are controlled with modulation depth and
period of the photonic lattices, positive and negative defects, beam
distribution factor and nonlinearity change. For positive defects, the
pseudo-period oscillation and localization of the AiG beam may be formed under
a certain condition, while the beam is diffused for negative defects. Moreover,
the solitons may appear during the propagation process when the self-focusing
nonlinearity is introduced.


title:
Optimization of the magnetic properties of aligned Co nanowires/polymer
  composites for the fabrication of permanent magnets

abstract:
  We aim at combining high coercivity magnetic nanowires in a polymer matrix in
a view to fabricate rare--earth free bonded magnets. In particular, our aim is
to fabricate anisotropic materials by aligning the wires in the polymer matrix.
We have explored the different parameters of the fabrication process in order
to produce a material with the best possible magnetic properties. We show that
the choice of a proper solvent allows obtaining stable nanowire suspensions.
The length and the type of the polymer chains play also an important role.
Smaller chains ($M_w < 10000$) provide better magnetization results. The
magnetic field applied during the casting of the material plays also a role and
should be of the order of a fraction of a tesla. The local order of the
nanowires in the matrix has been characterized by TEM and Small Angle Neutron
Scattering. The correlation between the local order of the wires and the
magnetic properties is discussed. Materials with coercivity $\mu_0 H_c$ up to
0.70 $T$ at room temperature have been obtained.


title: Charmed particles production in pA-interactions at 70 GeV

abstract:
  The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP,
Protvino) are presented. Interactions of the 70 GeV proton beam with carbon,
silicon and lead targets were studied to detect decays of charmed $D^0$, $\bar
D^0$, $D^+$, $D^-$ mesons and $\Lambda_c^+$ baryon near their production
threshold. Measurements of lifetimes and masses have shown a good agreement
with PDG data. The inclusive cross sections of charm production and their
A-dependencies have been obtained. The yields of these particles are compared
with the theoretical predictions and the data of other experiments. The
measured cross section of the total open charm production $\sigma(c\bar c) =
7.1 \pm 2.3(stat) \pm 1.4(syst)$ $\mu$b/nucleon at the collision c.m. energy
$\surd s$ = 11.8 GeV is well above the QCD model predictions. The contributions
of different kinds of charmed particles to the total cross section of the open
charm production in proton-nucleus interactions vary with energy.


title:
Color Change Effect in an Organic-Inorganic Hybrid Material Based on a
  Porphyrin Diacid

abstract:
  Porphyrinic materials show a range of interesting and useful optical and
electrical properties. The less well-known sub-class of porphyrin diacids has
been used in this work to construct an ionic hybrid organic-inorganic material
in combination with a halogenidometalate anion. The resulting compound,
$[H_6TPyP][BiCl_6]_2$ (1) (TPyP = tetra(4-pyridyl)porphyrin) has been obtained
via a facile solution based synthesis in single crystalline form. The material
exhibits a broad photoluminescence emission band between 650 and 850 nm at room
temperature. Single crystals of $[H_6TPyP][BiCl_6]_2$ show a photocurrent in
the fA and a much higher dark current in the nA range. They also display an
unexpected reversible color change upon wetting with different liquids. This
phenomenon has been investigated with optical spectroscopy, SEM, XPS and NEXAFS
techniques, showing that a surface-based structural coloration effect is the
source of the color change. This stands in contrast to other materials where
structural coloration typically has to be introduced through elaborate,
multi-step processes or the use of natural templates. Additionally, it
underscores the potential of self-assembly of porphyrinic hybrid compounds in
the fabrication of materials with unusual optical properties.


title:
Embeddings of non-simply-connected 4-manifolds in 7-space. I.
  Classification modulo knots

abstract:
  We work in the smooth category. Let $N$ be a closed connected orientable
4-manifold with torsion free $H_1$, where $H_q:=H_q(N;Z)$. Our main result is a
complete readily calculable classification of embeddings $N\to R^7$, up to the
equivalence relation generated by isotopy and embedded connected sum with
embeddings $S^4\to R^7$. Such a classification was already known only for
$H_1=0$ by the work of Bo\'echat, Haefliger and Hudson from 1970. Our
classification involves the Bo\'echat-Haefliger invariant $\varkappa(f)\in
H_2$, Seifert bilinear form $\lambda(f):H_3\times H_3\to Z$ and
$\beta$-invariant $\beta(f)$ which assumes values in a quotient of $H_1$
defined by values of $\varkappa(f)$ and $\lambda(f)$. In particular, for
$N=S^1\times S^3$ we give a geometrically defined 1-1 correspondence between
the set of equivalence classes of embeddings and an explicit quotient of the
set $Z\oplus Z$.
  Our proof is based on development of Kreck modified surgery approach,
involving some simpler reformulations, and also uses parametric connected sum.


title:
Measurement of the pi^0 -> e^+e^-gamma Dalitz decay at the Mainz
  Microtron

abstract:
  The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0
p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The
value obtained for the slope parameter of the pi^0 electromagnetic transition
form factor, a_pi = 0.030+/-0.010_tot, is in agreement with existing
measurements of this decay and with recent theoretical calculations. The
uncertainty obtained in the value of a_pi is lower than in previous results
based on the pi^0 -> e^+e^-gamma decay.


title: A Modal Logic of Supervenience

abstract:
  Supervenience is an important philosophical concept. In this paper, inspired
by the supervenience-determined consequence relation and the semantics of
agreement operator, we introduce a modal logic of supervenience, which has a
dyadic operator of supervenience as a sole modality. The semantics of
supervenience modality is very natural to correspond to the
supervenience-determined consequence relation, in a quite similar way that the
strict implication corresponds to the inference-determined consequence
relation. We show that this new logic is more expressive than the modal logic
of agreement, by proposing a notion of bisimulation for the latter logic. We
provide a sound proof system for our new logic. We also lift on to more general
logics of supervenience. Related to this, we compare propositional logic of
determinacy and non-contingency in expressive powers, and give axiomatizations
of propositional logic of determinacy over various classes of frames, thereby
resolving an open research direction listed
in~\cite[Sec.~8.2]{Gorankoetal:2016}. As a corollary, we also present an
alternative axiomatization for propositional logic of determinacy over
universal models. We conclude with a lot of future work.


title:
A Neural Architecture Mimicking Humans End-to-End for Natural Language
  Inference

abstract:
  In this work we use the recent advances in representation learning to propose
a neural architecture for the problem of natural language inference. Our
approach is aligned to mimic how a human does the natural language inference
process given two statements. The model uses variants of Long Short Term Memory
(LSTM), attention mechanism and composable neural networks, to carry out the
task. Each part of our model can be mapped to a clear functionality humans do
for carrying out the overall task of natural language inference. The model is
end-to-end differentiable enabling training by stochastic gradient descent. On
Stanford Natural Language Inference(SNLI) dataset, the proposed model achieves
better accuracy numbers than all published models in literature.


title: On Propagation of Fixed Points of Quantum Operations and Beyond

abstract:
  We show that some abstract results on propagation of fixed points for
completely positive maps on $C^*$-algebras provide a natural approach to unify
recent Noether type theorems on the equivalence of symmetries with conservation
laws for dynamical systems of Markov processes, of quantum operations, and of
quantum stochastic maps. In addition, we obtain some new Noether type theorems,
provide examples and counter-examples, and extend most of the existing results
with characterisations in terms of dual infinitesimal generators of the
corresponding strongly continuous one-parameter semigroups.


title:
DistributedFBA.jl: High-level, high-performance flux balance analysis in
  Julia

abstract:
  Motivation:
  Flux balance analysis, and its variants, are widely used methods for
predicting steady-state reaction rates in biochemical reaction networks. The
exploration of high dimensional networks with such methods is currently
hampered by software performance limitations.
  Results:
  DistributedFBA.jl is a high-level, high-performance, open-source
implementation of flux balance analysis in Julia. It is tailored to solve
multiple flux balance analyses on a subset or all the reactions of large and
huge-scale networks, on any number of threads or nodes.
  Availability:
  The code and benchmark data are freely available on
http://github.com/opencobra/COBRA.jl. The documentation can be found at
http://opencobra.github.io/COBRA.jl


title:
Relating cell shape and mechanical stress in a spatially disordered
  epithelium using a vertex-based model

abstract:
  Using a popular vertex-based model to describe a spatially disordered planar
epithelial monolayer, we examine the relationship between cell shape and
mechanical stress at the cell and tissue level. Deriving expressions for stress
tensors starting from an energetic formulation of the model, we show that the
principal axes of stress for an individual cell align with the principal axes
of shape, and we determine the bulk effective tissue pressure when the
monolayer is isotropic at the tissue level. Using simulations for a monolayer
that is not under peripheral stress, we fit parameters of the model to
experimental data for Xenopus embryonic tissue. The model predicts that
mechanical interactions can generate mesoscopic patterns within the monolayer
that exhibit long-range correlations in cell shape. The model also suggests
that the orientation of mechanical and geometric cues for processes such as
cell division are likely to be strongly correlated in real epithelia. Some
limitations of the model in capturing geometric features of Xenopus epithelial
cells are highlighted.


title: Recent results from the NA61/SHINE strong interaction physics programme

abstract:
  The main physics goals of the NA61/SHINE programme on strong interactions are
the study of the properties of the onset of deconfinement and the search for
signatures of the critical point of strongly interacting matter. For this
purpose a scan of the two dimensional phase diagram ($T$-$\mu_{B}$) is being
performed at the SPS by measurements of hadron production in nucleus-nucleus
collisions as a function of collision energy and system size.
  This contribution presents intriguing results on the energy dependence of
hadron spectra and yields in inelastic p+p and centrality selected Be+Be and
Ar+Sc collisions. In particular, the energy dependence of the signals of
deconfinement, the "horn", "step" and "kink", and new results on fluctuations
and correlations are shown and compared with the corresponding data of other
experiments and model predictions.


title:
Single spin asymmetry in forward $pA$ collisions II: Fragmentation
  contribution

abstract:
  We compute the twist-three fragmentation contribution to the transverse
single spin asymmetry (SSA) in light hadron production $p^\uparrow p\to hX$ and
$p^\uparrow A\to hX$ including the gluon saturation effect in the unpolarized
nucleon/nucleus. Together with the results in our previous paper, this
completes the full evaluation of the SSA in this process in the "hybrid"
formalism. We argue that the dependence of SSAs on the atomic mass number in
the forward region can elucidate the relative importance of the soft gluon pole
contribution from the twist-three quark-gluon-quark correlation in the
polarized nucleon and the twist-three fragmentation contribution from the final
state hadron.


title: Toward a systems-level view of mitotic checkpoints

abstract:
  Reproduction and natural selection are the key elements of life. In order to
reproduce, the genetic material must be doubled, separated and placed into two
new daughter cells, each containing a complete set of chromosomes and
organelles. In mitosis, transition from one process to the next is guided by
intricate surveillance mechanisms, known as the mitotic checkpoints.
Dis-regulation of cell division through checkpoint malfunction can lead to
developmental defects and contribute to the development or progression of
tumors. This review approaches two important mitotic checkpoints, the spindle
assembly checkpoint (SAC) and the spindle position checkpoint (SPOC). The
highly conserved spindle assembly checkpoint (SAC) controls the onset of
anaphase by preventing premature segregation of the sister chromatids of the
duplicated genome, to the spindle poles. In contrast, the spindle position
checkpoint (SPOC), in the budding yeast S. cerevisiae, ensures that during
asymmetric cell division mitotic exit does not occur until the spindle is
properly aligned with the cell polarity axis. Although there are no known
homologs, there is indication that functionally similar checkpoints exist also
in animal cells.


title: Improved Handover Through Dual Connectivity in 5G mmWave Mobile Networks

abstract:
  The millimeter wave (mmWave) bands offer the possibility of orders of
magnitude greater throughput for fifth generation (5G) cellular systems.
However, since mmWave signals are highly susceptible to blockage, channel
quality on any one mmWave link can be extremely intermittent. This paper
implements a novel dual connectivity protocol that enables mobile user
equipment (UE) devices to maintain physical layer connections to 4G and 5G
cells simultaneously. A novel uplink control signaling system combined with a
local coordinator enables rapid path switching in the event of failures on any
one link. This paper provides the first comprehensive end-to-end evaluation of
handover mechanisms in mmWave cellular systems. The simulation framework
includes detailed measurement-based channel models to realistically capture
spatial dynamics of blocking events, as well as the full details of MAC, RLC
and transport protocols. Compared to conventional handover mechanisms, the
study reveals significant benefits of the proposed method under several
metrics.


title:
On the formation of a stable penumbra in a region of flux emergence in
  the Sun

abstract:
  We studied the formation of the first penumbral sector around a pore in the
following polarity of the Active Region (AR) NOAA 11490. We used a high
spatial, spectral, and temporal resolution data set acquired by the
Interferometric BIdimensional Spectrometer operating at the NSO/Dunn Solar
Telescope as well as data taken by the Helioseismic and Magnetic Imager onboard
the Solar Dynamics Observatory satellite. On the side towards the leading
polarity, elongated granules in the photosphere and an arch filament system
(AFS) in the chromosphere are present, while the magnetic field shows a
sea-serpent configuration, indicating a region of magnetic flux emergence. We
found that the formation of a stable penumbra in the following polarity of the
AR begins in the area facing the opposite polarity located below the AFS in the
flux emergence region, differently from what found by Schlichenmaier and
colleaguestbf. Moreover, during the formation of the first penumbral sector,
the area characterized by magnetic flux density larger than 900 G and the area
of the umbra increase.


title: Optimal Stencils in Sobolev Spaces

abstract:
  This paper proves that the approximation of pointwise derivatives of order
$s$ of functions in Sobolev space $W_2^m(\R^d)$ by linear combinations of
function values cannot have a convergence rate better than $m-s-d/2$, no matter
how many nodes are used for approximation and where they are placed. These
convergence rates are attained by {\em scalable} approximations that are exact
on polynomials of order at least $\lfloor m-d/2\rfloor +1$, proving that the
rates are optimal for given $m,\,s,$ and $d$. And, for a fixed node set
$X\subset\R^d$, the convergence rate in any Sobolev space $W_2^m(\Omega)$
cannot be better than $q-s$ where $q$ is the maximal possible order of
polynomial exactness of approximations based on $X$, no matter how large $m$
is. In particular,scalable stencil constructions via polyharmonic kernels are
shown to realize the optimal convergence rates, and good approximations of
their error in Sobolev space can be calculated via their error in Beppo-Levi
spaces. This allows to construct near-optimal stencils in Sobolev spaces stably
and efficiently, for use in meshless methods to solve partial differential
equations via generalized finite differences (RBF-FD). Numerical examples are
included for illustration.


title: Interplay of Delay and multiplexing: Impact on Cluster Synchronization

abstract:
  Communication delays and multiplexing are ubiquitous features of real-world
networked systems. We here introduce a simple model where these two features
are simultaneously present, and report the rich phe- nomenology which is
actually due to their interplay on cluster synchronization. A delay in one
layer has non trivial impacts on the collective dynamics of the other layers,
enhancing or suppressing synchronization. At the same time, multiplexing may
also enhance cluster synchronization of delayed layers. We elucidate several
non trivial (and anti-intuitive) scenarios, which are of interest and potential
application in various real-world systems, where introduction of a delay may
render synchronization of a layer robust against changes in the properties of
the other layers.


title:
3D computation of non-linear eddy currents: variational method and
  superconducting cubic bulk

abstract:
  Computing the electric eddy currents in non-linear materials, such as
superconductors, is \E{not straightforward}. The design of superconducting
magnets and power applications needs electromagnetic computer modeling, being
in many cases a three-dimensional (3D) problem. Since 3D problems require high
computing times, novel time-efficient modeling tools are highly desirable. This
article presents a novel computing modeling method based on a variational
principle. The self-programmed implementation uses an original minimization
method, which divides the sample into sectors. This speeds-up the computations
with no loss of accuracy, while enabling efficient parallelization. This method
could also be applied to model transients in linear materials or networks of
non-linear electrical elements. As example, we analyze the magnetization
currents of a cubic superconductor. This 3D situation remains unknown, in spite
of the fact that it is often met in material characterization and bulk
applications. We found that below the penetration field and in part of the
sample, current flux lines are not rectangular and significantly bend in the
direction parallel to the applied field. In conclusion, the presented numerical
method is able to time-efficiently solve fully 3D situations without loss of
accuracy.


title: Non-archimedean gauge seminorms

abstract:
  This paper is intended to provide foundations to the theory of Witt-type
topological group and ring functors defined on a category of topological
algebras, and, in presence of Banach norms, to show how to topologically deal
with them. It is logically the first of a series of papers in preparation on
the use of Barsotti-Witt constructions to obtain Scholze's tilting equivalence
uniformly with respect to the perfectoid field K of characteristic 0 lifting a
particular perfectoid field F of characteristic p>0.
  The paper is basically self-contained and may have an independent interest
especially for specialists of topological algebra and non-archimedean
functional analysis: this accounts for its independent submission. We indicate
a new viewpoint in the theory of non-archimedean Banach algebras, based on a
higher-dimensional generalization of the notion of gauge-seminorm as explained
in P. Schneider "Non-archimedean Functional Analysis" Springer 2002


title: Manin's conjecture for certain spherical threefolds

abstract:
  We prove Manin's conjecture on the asymptotic behavior of the number of
rational points of bounded anticanonical height for a spherical threefold with
canonical singularities and two infinite families of spherical threefolds with
log terminal singularities. Moreover, we show that one of these families does
not satisfy a conjecture of Batyrev and Tschinkel on the leading constant in
the asymptotic formula. Our proofs are based on the universal torsor method,
using Brion's description of Cox rings of spherical varieties.


title:
Stabilization of structure-preserving power networks with market
  dynamics

abstract:
  This paper studies the problem of maximizing the social welfare while
stabilizing both the physical power network as well as the market dynamics. For
the physical power grid a third-order structure-preserving model is considered
involving both frequency and voltage dynamics. By applying the primal-dual
gradient method to the social welfare problem, a distributed dynamic pricing
algorithm in port-Hamiltonian form is obtained. After interconnection with the
physical system a closed-loop port-Hamiltonian system of differential-algebraic
equations is obtained, whose properties are exploited to prove local asymptotic
stability of the optimal points.


title: Memory and universality in interface growth

abstract:
  Understanding possible universal properties for systems far from equilibrium
is much less developed than for their equilibrium counterparts and poses a
major challenge to present day statistical physics. The study of aging
properties, and how the memory of the past is conserved by the time evolution
in presence of noise is a crucial facet of the problem. Recently, very robust
universal properties were shown to arise in one-dimensional growth processes
with local stochastic rules,leading to the Kardar-Parisi-Zhang universality
class. Yet it has remained essentially unknown how fluctuations in these
systems correlate at different times. Here we derive quantitative predictions
for the universal form of the two-time aging dynamics of growing interfaces,
which, moreover, turns out to exhibit a surprising breaking of ergodicity. We
provide corroborating experimental observations on a turbulent liquid crystal
system, which demonstrates universality. This may give insight into memory
effects in a broader class of far-from-equilibrium systems.