title:
Adaptive finite element methods for an optimal control problem involving
  Dirac measures

abstract:
  The purpose of this work is the design and analysis of a reliable and
efficient a posteriori error estimator for the so-called pointwise tracking
optimal control problem. This linear-quadratic optimal control problem entails
the minimization of a cost functional that involves point evaluations of the
state, thus leading to an adjoint problem with Dirac measures on the right hand
side; control constraints are also considered. The proposed error estimator
relies on a posteriori error estimates in the maximum norm for the state and in
Muckenhoupt weighted Sobolev spaces for the adjoint state. We present an
analysis that is valid for two and three-dimensional domains. We conclude by
presenting several numerical experiments which reveal the competitive
performance of adaptive methods based on the devised error estimator.


title:
Improved limits on interactions of low-mass spin-0 dark matter from
  atomic clock spectroscopy

abstract:
  Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently
oscillating classical field $\phi = \phi_0 \cos(m_\phi t)$, can induce
oscillating variations in the fundamental constants through their interactions
with the Standard Model sector. We calculate the effects of such possible
interactions, which may include the linear interaction of $\phi$ with the Higgs
boson, on atomic and molecular transitions. Using recent atomic clock
spectroscopy measurements, we derive new limits on the linear interaction of
$\phi$ with the Higgs boson, as well as its quadratic interactions with the
photon and light quarks. For the linear interaction of $\phi$ with the Higgs
boson, our derived limits improve on existing constraints by up to $2-3$ orders
of magnitude.

categories: physics.atom-ph astro-ph.CO hep-ph nucl-th


title: Simple, Scalable and Accurate Posterior Interval Estimation

abstract:
  There is a lack of simple and scalable algorithms for uncertainty
quantification. Bayesian methods quantify uncertainty through posterior and
predictive distributions, but it is difficult to rapidly estimate summaries of
these distributions, such as quantiles and intervals. Variational Bayes
approximations are widely used, but may badly underestimate posterior
covariance. Typically, the focus of Bayesian inference is on point and interval
estimates for one-dimensional functionals of interest. In small scale problems,
Markov chain Monte Carlo algorithms remain the gold standard, but such
algorithms face major problems in scaling up to big data. Various modifications
have been proposed based on parallelization and approximations based on
subsamples, but such approaches are either highly complex or lack theoretical
support and/or good performance outside of narrow settings. We propose a very
simple and general posterior interval estimation algorithm, which is based on
running Markov chain Monte Carlo in parallel for subsets of the data and
averaging quantiles estimated from each subset. We provide strong theoretical
guarantees and illustrate performance in several applications.


title: Experimental quantum data locking

abstract:
  Classical correlation can be locked via quantum means--quantum data locking.
With a short secret key, one can lock an exponentially large amount of
information, in order to make it inaccessible to unauthorized users without the
key. Quantum data locking presents a resource-efficient alternative to one-time
pad encryption which requires a key no shorter than the message. We report
experimental demonstrations of quantum data locking scheme originally proposed
by DiVincenzo et al. [Phys. Rev. Lett. 92, 067902 (2004)] and a loss-tolerant
scheme developed by Fawzi, Hayde, and Sen [J. ACM. 60, 44 (2013)]. We observe
that the unlocked amount of information is larger than the key size in both
experiments, exhibiting strong violation of the incremental proportionality
property of classical information theory. As an application example, we show
the successful transmission of a photo over a lossy channel with quantum data
(un)locking and error correction.


title:
Robin Hood Hashing really has constant average search cost and variance
  in full tables

abstract:
  Thirty years ago, the Robin Hood collision resolution strategy was introduced
for open addressing hash tables, and a recurrence equation was found for the
distribution of its search cost. Although this recurrence could not be solved
analytically, it allowed for numerical computations that, remarkably, suggested
that the variance of the search cost approached a value of $1.883$ when the
table was full. Furthermore, by using a non-standard mean-centered search
algorithm, this would imply that searches could be performed in expected
constant time even in a full table.
  In spite of the time elapsed since these observations were made, no progress
has been made in proving them. In this paper we introduce a technique to work
around the intractability of the recurrence equation by solving instead an
associated differential equation. While this does not provide an exact
solution, it is sufficiently powerful to prove a bound for the variance, and
thus obtain a proof that the variance of Robin Hood is bounded by a small
constant for load factors arbitrarily close to 1. As a corollary, this proves
that the mean-centered search algorithm runs in expected constant time.
  We also use this technique to study the performance of Robin Hood hash tables
under a long sequence of insertions and deletions, where deletions are
implemented by marking elements as deleted. We prove that, in this case, the
variance is bounded by $1/(1-\alpha)+O(1)$, where $\alpha$ is the load factor.
  To model the behavior of these hash tables, we use a unified approach that
can be applied also to study the First-Come-First-Served and
Last-Come-First-Served collision resolution disciplines, both with and without
deletions.


title: Topological Spin and Valley Pumping in Silicene

abstract:
  We propose an experimental scheme to realize adiabatic topological spin and
valley pumping by using silicene subject to an in-plane $ac$ electric field
with amplitude $E_{y}$ and a vertical electric field consisting of an
electrostatic component and an $ac$ component with amplitudes $E_{z}^{0}$ and
$E_{z}^{1}$. By tuning $E_{z}^{0}$ and $E_{z}^{1}$, topological valley pumping
or spin-valley pumping can be achieved. The noisefree valley and spin currents
generated could be useful in valleytronic and spintronic applications. This
work demonstrates that bulk topological spin or valley pumping is a general
characteristic effect of two-dimensional topological insulators, irrelevant to
the edge state physics.


title:
Structural Pathways Supporting Swift Acquisition of New Visuo-Motor
  Skills

abstract:
  Human skill learning requires fine-scale coordination of distributed networks
of brain regions that are directly linked to one another by white matter tracts
to allow for effective information transmission. Yet how individual differences
in these anatomical pathways may impact individual differences in learning
remains far from understood. Here, we test the hypothesis that individual
differences in the organization of structural networks supporting task
performance predict individual differences in the rate at which humans learn a
visuo-motor skill. Over the course of 6 weeks, twenty-two healthy adult
subjects practiced a discrete sequence production task, where they learned a
sequence of finger movements based on discrete visual cues. We collected
structural imaging data during four MRI scanning sessions spaced approximately
two weeks apart, and using deterministic tractography, structural networks were
generated for each participant to identify streamlines that connect cortical
and sub-cortical brain regions. We observed that increased white matter
connectivity linking early visual (but not motor) regions was associated with a
faster learning rate. Moreover, we observed that the strength of multi-edge
paths between motor and visual modules was also correlated with learning rate,
supporting the role of polysynaptic connections in successful skill
acquisition. Our results demonstrate that the combination of diffusion imaging
and tractography-based connectivity can be used to predict future individual
differences in learning capacity, particularly when combined with methods from
network science and graph theory.


abstract:
  Most existing learning to hash methods assume that there are sufficient data,
either labeled or unlabeled, on the domain of interest (i.e., the target
domain) for training. However, this assumption cannot be satisfied in some
real-world applications. To address this data sparsity issue in hashing,
inspired by transfer learning, we propose a new framework named Transfer
Hashing with Privileged Information (THPI). Specifically, we extend the
standard learning to hash method, Iterative Quantization (ITQ), in a transfer
learning manner, namely ITQ+. In ITQ+, a new slack function is learned from
auxiliary data to approximate the quantization error in ITQ. We developed an
alternating optimization approach to solve the resultant optimization problem
for ITQ+. We further extend ITQ+ to LapITQ+ by utilizing the geometry structure
among the auxiliary data for learning more precise binary codes in the target
domain. Extensive experiments on several benchmark datasets verify the
effectiveness of our proposed approaches through comparisons with several
state-of-the-art baselines.


title: Afterburner: The Case for In-Browser Analytics

abstract:
  This paper explores the novel and unconventional idea of implementing an
analytical RDBMS in pure JavaScript so that it runs completely inside a browser
with no external dependencies. Our prototype, called Afterburner, generates
compiled query plans that exploit typed arrays and asm.js, two relatively
recent advances in JavaScript. On a few simple queries, we show that
Afterburner achieves comparable performance to MonetDB running natively on the
same machine. This is an interesting finding in that it shows how far
JavaScript has come as an efficient execution platform. Beyond a mere technical
curiosity, we discuss how our techniques could support ubiquitous in-browser
interactive analytics (potentially integrating with browser-based notebooks)
and also present interesting opportunities for split-execution strategies where
query operators are distributed between the browser and backend servers.


title:
A nonlinear small-deformation theory for transient droplet
  electrohydrodynamics

abstract:
  The deformation of a viscous liquid droplet suspended in another liquid and
subject to an applied electric field is a classic multiphase flow problem best
described by the Melcher-Taylor leaky dielectric model. The main assumption of
the model is that any net charge in the system is concentrated on the interface
between the two liquids as a result of the jump in Ohmic currents from the
bulk. Upon application of the field, the drop can either attain a steady
prolate or oblate shape with toroidal circulating flows both inside and outside
arising from tangential stresses on the interface due to action of the field on
the surface charge distribution. Since the pioneering work of
\cite{taylor1966}, there have been numerous computational and theoretical
studies to predict the deformations measured in experiments. Most existing
theoretical models, however, have either neglected transient charge relaxation
or nonlinear charge convection by the interfacial flow. In this work, we
develop a novel small-deformation theory accurate to second order in electric
capillary number ${O}(Ca_E^2)$ for the complete Melcher-Taylor model that
includes transient charge relaxation, charge convection by the flow, as well as
transient shape deformation. The main result of the paper is the derivation of
coupled evolution equations for the induced electric multipoles and for the
shape functions describing the deformations on the basis of spherical
harmonics. Our results, which are consistent with previous models in the
appropriate limits, show excellent agreement with fully nonlinear numerical
simulations based on an axisymmetric boundary-element formulation and with
existing experimental data in the small-deformation regime.


title: Evolutionary games on the lattice: death and birth of the fittest

abstract:
  This paper investigates the long-term behavior of an interacting particle
system of interest in the hot topic of evolutionary game theory. Each site of
the $d$-dimensional integer lattice is occupied by a player who is
characterized by one of two possible strategies. Following the traditional
modeling approach of spatial games, the configuration is turned into a payoff
landscape that assigns a payoff to each player based on her strategy and the
strategy of her neighbors. The payoff is then interpreted as a fitness, by
having each player independently update their strategy at rate one by mimicking
their neighbor with the largest payoff. With these rules, the mean-field
approximation of the spatial game exhibits the same asymptotic behavior as the
popular replicator equation. Except for a coexistence result that shows an
agreement between the process and the mean-field model, our analysis reveals
that the two models strongly disagree in many aspects, showing in particular
that the presence of a spatial structure in the form of local interactions
plays a key role. More precisely, in the parameter region where both strategies
are evolutionary stable in the replicator equation, in the spatial model either
one strategy wins or the system fixates to a configuration where both
strategies are present. In addition, while defection is evolutionary stable for
the prisoner's dilemma game in the replicator equation, space favors
cooperation in our model.


title: Controlling Kondo-like Scattering at the SrTiO3-based Interfaces

abstract:
  The observation of magnetic interaction at the interface between nonmagnetic
oxides has attracted much attention in recent years. In this report, we show
that the Kondo-like scattering at the SrTiO3-based conducting interface is
enhanced by increasing the lattice mismatch and growth oxygen pressure PO2. For
the 26-unit-cell LaAlO3/SrTiO3 (LAO/STO) interface with lattice mismatch being
3.0%, the Kondo-like scattering is observed when PO2 is beyond 1 mTorr. By
contrast, when the lattice mismatch is reduced to 1.0% at the
(La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) interface, the metallic state is
always preserved up to PO2 of 100 mTorr. The data from Hall measurement and
X-ray absorption near edge structure (XANES) spectroscopy reveal that the
larger amount of localized Ti3+ ions are formed at the LAO/STO interface
compared to LSAT/STO. Those localized Ti3+ ions with unpaired electrons can be
spin-polarized to scatter mobile electrons, responsible for the Kondo-like
scattering observed at the LAO/STO interface.


title:
Cross-Domain Visual Matching via Generalized Similarity Measure and
  Feature Learning

abstract:
  Cross-domain visual data matching is one of the fundamental problems in many
real-world vision tasks, e.g., matching persons across ID photos and
surveillance videos. Conventional approaches to this problem usually involves
two steps: i) projecting samples from different domains into a common space,
and ii) computing (dis-)similarity in this space based on a certain distance.
In this paper, we present a novel pairwise similarity measure that advances
existing models by i) expanding traditional linear projections into affine
transformations and ii) fusing affine Mahalanobis distance and Cosine
similarity by a data-driven combination. Moreover, we unify our similarity
measure with feature representation learning via deep convolutional neural
networks. Specifically, we incorporate the similarity measure matrix into the
deep architecture, enabling an end-to-end way of model optimization. We
extensively evaluate our generalized similarity model in several challenging
cross-domain matching tasks: person re-identification under different views and
face verification over different modalities (i.e., faces from still images and
videos, older and younger faces, and sketch and photo portraits). The
experimental results demonstrate superior performance of our model over other
state-of-the-art methods.


title:
Absorption variability as a probe of the multiphase interstellar media
  surrounding active galaxies

abstract:
  We examine a model for the variable free-free and neutral hydrogen absorption
inferred towards the cores of some compact radio galaxies in which a spatially
fluctuating medium drifts in front of the source. We relate the
absorption-induced intensity fluctuations to the statistics of the underlying
opacity fluctuations. We investigate models in which the absorbing medium
consists of either discrete clouds or a power-law spectrum of opacity
fluctuations. We examine the variability characteristics of a medium comprised
of Gaussian-shaped clouds in which the neutral and ionized matter are
co-located, and in which the clouds comprise spherical constant-density neutral
cores enveloped by ionized sheaths. The cross-power spectrum indicates the
spatial relationship between neutral and ionized matter, and distinguishes the
two models, with power in the Gaussian model declining as a featureless
power-law, but that in the ionized sheath model oscillating between positive
and negative values. We show how comparison of the HI and free-free power
spectra reveals information on the ionization and neutral fractions of the
medium. The background source acts as a low-pass filter of the underlying
opacity power spectrum, which limits temporal fluctuations to frequencies
$\omega < \dot{\theta}_v / \theta_{\rm src}$, where $\dot{\theta}_v$ is the
angular drift speed of the matter in front of the source, and it quenches the
observability of opacity structures on scales smaller than the source size
$\theta_{\rm src}$. For drift speeds of $\sim 10^3\,$km s$^{-1}$ and source
brightness temperatures $\sim 10^{12}\,$K, this limitation confines temporal
opacity fluctuations to timescales of order several months to decades.


title:
Schistosoma mansoni cercariae exploit an elastohydrodynamic coupling to
  swim efficiently

abstract:
  The motility of many parasites is critical for the infection process of their
host, as exemplified by the transmission cycle of the blood fluke Schistosoma
mansoni. In their human infectious stage, immature, submillimetre-scale forms
of the parasite known as cercariae swim in freshwater and infect humans by
penetrating through the skin. This infection causes Schistosomiasis, a
parasitic disease that is comparable to malaria in its global socio-economic
impact. Given that cercariae do not feed and hence have a finite lifetime of
around 12 hours, efficient motility is crucial for the parasite's survival and
transmission of Schistosomiasis. However, a first-principles understanding of
how cercariae swim is lacking. Via a combined experimental, theoretical and
robotics based approach, we demonstrate that cercariae propel themselves
against gravity by exploiting a unique elastohydrodynamic coupling. We show
that cercariae beat their tail in a periodic fashion while maintaining a fixed
flexibility near their posterior and anterior ends. The flexibility in these
regions allows an interaction between the fluid drag and bending resistance: an
elastohydrodynamic coupling, to naturally break time-reversal symmetry and
enable locomotion at small length-scales. We present a theoretical model, a
'T-swimmer', which captures the key swimming phenotype of cercariae. We further
validate our results experimentally through a macro-scale robotic realization
of the 'T-swimmer', explaining the unique forked-tail geometry of cercariae.
Finally, we find that cercariae maintain the flexibility at their posterior and
anterior ends at an optimal regime for efficient swimming, as predicted by our
theoretical model. We anticipate that our work sets the ground for linking the
swimming of S. mansoni cercariae to disease transmission and enables
explorations of novel strategies for Schistosomiasis prevention.


title:
Sum Degrees of Freedom of the $K$-user Interference Channel with Blind
  CSI

abstract:
  In this paper, we consider the problem of the interference alignment for the
$K$-user SISO interference channel (IC) with blind channel state information
(CSI) at transmitters. Our achievement in contrast to the traditional $K-$user
interference alignment (IA) scheme has more practical notions. In this case,
every receiver is equipped with one reconfigurable antenna which tries to place
its desired signal in a subspace which is linearly independent of interference
signals. We show that if the channel values are known to the receivers only,
the sum degrees-of-freedom (DoF) of the linear blind IA (BIA) with
reconfigurable antenna is $\frac{Kr}{r^2-r+K}$, where $r = \left
\lceil{\frac{\sqrt{1+4K}-1}{2}} \right \rceil$. The result indicates that the
optimum sum DoF for the $K-$user IC is to achieve the sum DoF of $\lim_{K
\rightarrow \infty} {\frac{Kr}{r^2-r+K}}=\frac{\sqrt{K}}{2}$ for an
asymptotically large interference network. Thus, the DoF of the $K$-user IC
using reconfigurable antenna grows sublinearly with the number of the users,
whereas it grows linearly in the case where transmitters access to the CSI. In
addition, we propose both achievability and converse proof so as to show that
this is the sum DoF of linear BIA with the reconfigurable antenna.


title: From Extended theories of Gravity to Dark Matter

abstract:
  In this work, we propose different models of extended theories of gravity,
which are minimally coupled to the SM fields, to explain the possibility of a
dark matter (DM) candidate, without ad-hoc additions to the Standard Model
(SM). We modify the gravity sector by allowing quantum corrections motivated
from local $f(R)$ gravity, and non-minimally coupled gravity with SM sector and
dilaton field. Using an effective field theory (EFT) framework, we constrain
the scale of the EFT and DM mass. We consider two cases-Light DM (LDM) and
Heavy DM (HDM), and deduce upper bounds on the DM annihilation cross section to
SM particles.


title: Network Traffic Obfuscation and Automated Internet Censorship

abstract:
  Internet censors seek ways to identify and block internet access to
information they deem objectionable. Increasingly, censors deploy advanced
networking tools such as deep-packet inspection (DPI) to identify such
connections. In response, activists and academic researchers have developed and
deployed network traffic obfuscation mechanisms. These apply specialized
cryptographic tools to attempt to hide from DPI the true nature and content of
connections.
  In this survey, we give an overview of network traffic obfuscation and its
role in circumventing Internet censorship. We provide historical and technical
background that motivates the need for obfuscation tools, and give an overview
of approaches to obfuscation used by state of the art tools. We discuss the
latest research on how censors might detect these efforts. We also describe the
current challenges to censorship circumvention research and identify concrete
ways for the community to address these challenges.


title:
Epitaxial growth of hexagonal tungsten bronze CsxWO3 films in
  superconducting phase region exceeding bulk limit

abstract:
  We report epitaxial synthesis of superconducting CsxWO3 (x = 0.11, 0.20,
0.31) films on Y-stabilized ZrO2 (111) substrates. The hexagonal crystal
structure was verified not only for composition within the stable region of
bulk (x = 0.20, 0.31), but also for the out-of-range composition (x = 0.11).
The onset of superconducting transition temperature (TC) was recorded 5.8 K for
x = 0.11. We found strong correlation between TC and c-axis length,
irrespective of the Cs content. The results indicate that hidden
superconducting phase region of hexagonal tungsten bronze is accessible by
using epitaxial synthesis of lightly doped films.


title: Track Extraction with Hidden Reciprocal Chain Models

abstract:
  This paper develops Bayesian track extraction algorithms for targets modelled
as hidden reciprocal chains (HRC). HRC are a class of finite-state random
process models that generalise the familiar hidden Markov chains (HMC). HRC are
able to model the "intention" of a target to proceed from a given origin to a
destination, behaviour which cannot be properly captured by a HMC. While
Bayesian estimation problems for HRC have previously been studied, this paper
focusses principally on the problem of track extraction, of which the primary
task is confirming target existence in a set of detections obtained from
thresholding sensor measurements. Simulation examples are presented which show
that the additional model information contained in a HRC improves detection
performance when compared to HMC models.


title:
On the Characteristics of Footpoints of Solar Magnetic Flux Ropes during
  the Eruption

abstract:
  We investigate the footpoints of four erupted magnetic flux ropes (MFRs) that
appear as sigmoidal hot channels prior to the eruptions in the Atmospheric
Imaging Assembly high temperaure passbands. The simultaneous Helioseismic and
Magnetic Imager observations disclose that one footpoint of the MFRs originates
in the penumbra or penumbra edge with a stronger magnetic field, while the
other in the moss region with a weaker magnetic field. The significant
deviation of the axis of the MFRs from the main polarity inversion lines and
associated filaments suggests that the MFRs have ascended to a high altitude,
thus being distinguishable from the source sigmoidal ARs. The more interesting
thing is that, with the eruption of the MFRs, the average inclination angle and
direct current at the footpoints with stronger magnetic field tend to decrease,
which is suggestive of a straightening and untwisting of the magnetic field in
the MFR legs. Moreover, the associated flare ribbons also display an
interesting evolution. They initially appear as sporadical brightenings at the
two footpoints of and in the regions below the MFRs and then quickly extend to
two slender sheared J-shaped ribbons with the two hooks corresponding to the
two ends of the MFRs. Finally, the straight parts of the two ribbons separate
from each other, evolving into two widened parallel ones. These features mostly
conforms to and supports the recently proposed three-dimensional standard
CME/flare model, i.e., the twisted MFR eruption stretches and leads to the
reconnection of the overlying field that transits from a strong to weak shear
with the increasing height.


title:
Sensitivity of atom interferometry to ultralight scalar field dark
  matter

abstract:
  We discuss the use of atom interferometry as a tool to search for Dark Matter
(DM) composed of ultra-light scalar fields. Previous work on ultra-light DM
detection using accelerometers has considered the possibility of equivalence
principle violating effects whereby gradients in the dark matter field can
directly produce relative accelerations between media of differing composition.
In atom interferometers, we find that time-varying phase signals from
oscillatory, or dilaton-like, DM can also arise due to changes in the atom rest
mass that can occur between light-pulses throughout the interferometer sequence
as well as changes in the earth's gravitational field. We estimate that several
orders of magnitude of unexplored phase space for light DM fields can be probed
with our proposed method.


title:
Modeling and detecting change in temporal networks via a dynamic degree
  corrected stochastic block model

abstract:
  In many applications it is of interest to identify anomalous behavior within
a dynamic interacting system. Such anomalous interactions are reflected by
structural changes in the network representation of the system. We propose and
investigate the use of a dynamic version of the degree corrected stochastic
block model (DCSBM) to model and monitor dynamic networks that undergo a
significant structural change. We apply statistical process monitoring
techniques to the estimated parameters of the DCSBM to identify significant
structural changes in the network. Application of our surveillance strategy to
the dynamic U.S. Senate co-voting network reveals that we are able to detect
significant changes in the network that reflect both times of cohesion and
times of polarization among Republican and Democratic party members. These
findings provide valuable insight about the evolution of the bipartisan
political system in the United States. Our analysis demonstrates that the
dynamic DCSBM monitoring procedure effectively detects local and global
structural changes in dynamic networks. The DCSBM approach is an example of a
more general framework that combines parametric random graph models and
statistical process monitoring techniques for network surveillance.


title:
Topological nodal-line semimetals in alkaline-earth stannides,
  germanides and silicides

abstract:
  Based on first-principles calculations and an effective Hamiltonian analysis,
we systematically investigate the electronic and topological properties of
alkaline-earth compounds $AX_2$ ($A$=Ca, Sr, Ba; $X$=Si, Ge, Sn). Taking
BaSn$_2$ as an example, we find that when spin-orbit coupling is ignored, these
materials are three-dimensional topological nodal-line semimetals characterized
by a snake-like nodal loop in three-dimensional momentum space. Drumhead-like
surface states emerge either inside or outside the loop circle on the (001)
surface depending on surface termination, while complicated
double-drumhead-like surface states appear on the (010) surface. When
spin-orbit coupling is included, the nodal line is gapped and the system
becomes a topological insulator with Z$_2$ topological invariants (1;001).
Since spin-orbit coupling effects are weak in light elements, the nodal-line
semimetal phase is expected to be achievable in some alkaline-earth germanides
and silicides.


title:
Effect of Sb substitution on the Topological Surface States in
  Bi_{2}Se_{3} single crystals: a magneto-transport study

abstract:
  Magneto-transport measurements have been carried out on Bi2-xSbxSe3 (x = 0,
0.05, 0.1, 0.3, 0.5) single crystals at 4.2 K temperature in the magnetic field
range of -15 T to 15 T. Shubnikov-de Haas (SdH) oscillations of 2D nature were
observed in samples with Sb concentration upto x = 0.3. The analyses of SdH
oscillations observed in magneto-resistance data using Lifshitz-Kosevich
equation reveal a systematic decrease in the Fermi surface area with Sb
substitution. The Berry phase obtained from the Landau Level fan diagram
suggests the occurrence of 2D oscillations arising from a Topological Surface
State (TSS) for Sb concentrations of x = 0, 0.05 and 0.1; while 2D oscillation
seen at higher Sb concentration is attributed to surface 2D electron gas
consequent to downward band bending.


title: Bootstrap bound for conformal multi-flavor QCD on lattice

abstract:
  The recent work by Iha et al shows an upper bound on mass anomalous dimension
$\gamma_m$ of multi-flavor massless QCD at the renormalization group fixed
point from the conformal bootstrap in $SU(N_F)_V$ symmetric conformal field
theories under the assumption that the fixed point is realizable with the
lattice regularization based on staggered fermions. We show that the almost
identical but slightly stronger bound applies to the regularization based on
Wilson fermions (or domain wall fermions) by studying the conformal bootstrap
in $SU(N_f)_L \times SU(N_f)_R$ symmetric conformal field theories. For
$N_f=8$, our bound implies $\gamma_m < 1.31$ to avoid dangerously irrelevant
operators that are not compatible with the lattice symmetry.


title:
Distributed data processing and analysis environment for neutron
  scattering experiments at CSNS

abstract:
  China Spallation Neutron Source (CSNS) is the first high-performance pulsed
neutron source in China, which will meet the increasing fundamental research
and technique applications demands domestically and overseas. A new distributed
data processing and analysis environment has been developed, which has generic
functionalities for neutron scattering experiments. The environment consists of
three parts, an object-oriented data processing framework adopting a data
centered architecture, a communication and data caching system based on the C/S
paradigm, and data analysis and visualization software providing the 2D/3D
experimental data display. This environment will be widely applied in CSNS for
live data processing.


title:
Construction of nuclear envelope shape by a high-genus vesicle with
  pore-size constraint

abstract:
  Nuclear pores have an approximately uniform distribution in the nuclear
envelope of most living cells. Hence, the morphology of the nuclear envelope is
a spherical stomatocyte with a high genus. We have investigated the morphology
of high-genus vesicles under pore-size constraint using dynamically
triangulated membrane simulations. Bending-energy minimization without volume
or other constraints produces a circular-cage stomatocyte, where the pores are
aligned in a circular line on an oblate bud. As the pore radius is reduced, the
circular-pore alignment is more stabilized than a random pore distribution on a
spherical bud. However, we have clarified the conditions for the formation of a
spherical stomatocyte: a small perinuclear volume, osmotic pressure within
nucleoplasm, and repulsion between the pores. When area-difference elasticity
is taken into account, the formation of cylindrical or budded tubules from the
stomatocyte and discoidal stomatocyte is found.


title: Bayesian $D$-optimal designs for error-in-variables models

abstract:
  Bayesian optimality criteria provide a robust design strategy to parameter
misspecification. We develop an approximate design theory for Bayesian
$D$-optimality for non-linear regression models with covariates subject to
measurement errors. Both maximum likelihood and least squares estimation are
studied and explicit characterisations of the Bayesian $D$-optimal saturated
designs for the Michaelis-Menten, Emax and exponential regression models are
provided. Several data examples are considered for the case of no preference
for specific parameter values, where Bayesian $D$-optimal saturated designs are
calculated using the uniform prior and compared to several other designs,
including the corresponding locally $D$-optimal designs, which are often used
in practice.


title: Causal Discovery for Manufacturing Domains

abstract:
  Yield and quality improvement is of paramount importance to any manufacturing
company. One of the ways of improving yield is through discovery of the root
causal factors affecting yield. We propose the use of data-driven interpretable
causal models to identify key factors affecting yield. We focus on factors that
are measured in different stages of production and testing in the manufacturing
cycle of a product. We apply causal structure learning techniques on real data
collected from this line. Specifically, the goal of this work is to learn
interpretable causal models from observational data produced by manufacturing
lines.
  Emphasis has been given to the interpretability of the models to make them
actionable in the field of manufacturing. We highlight the challenges presented
by assembly line data and propose ways to alleviate them.We also identify
unique characteristics of data originating from assembly lines and how to
leverage them in order to improve causal discovery. Standard evaluation
techniques for causal structure learning shows that the learned causal models
seem to closely represent the underlying latent causal relationship between
different factors in the production process. These results were also validated
by manufacturing domain experts who found them promising. This work
demonstrates how data mining and knowledge discovery can be used for root cause
analysis in the domain of manufacturing and connected industry.


title:
Near Unity Absorption in Van der Waals Semiconductors for Ultrathin
  Optoelectronics

abstract:
  We demonstrate near unity, broadband absorbing optoelectronic devices using
sub-15 nm thick transition metal dichalcogenides (TMDCs) of molybdenum and
tungsten as van der Waals semiconductor active layers. Specifically, we report
that near-unity light absorption is possible in extremely thin (< 15 nm) Van
der Waals semiconductor structures by coupling to strongly damped optical modes
of semiconductor/metal heterostructures. We further fabricate Schottky junction
devices using these highly absorbing heterostructures and characterize their
optoelectronic performance. Our work addresses one of the key criteria to
enable TMDCs as potential candidates to achieve high optoelectronic efficiency.


title: Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3

abstract:
  We have investigated surface acoustic wave propagation in Ni/LiNbO$_3$ hybrid
devices. We have found the absorption and phase velocity are dependent on the
sign of wave vector in a device, which indicates the nonreciprocal propagation
characteristic of systems with time reversal and spatial inversion
simultaneously broken symmetries. The nonreciprocity is reversed by the
180$^\circ$ rotation of magnetic field. Nonreciprocity seems largely dependent
on the shape of ferromagnetic Ni film. The origin of these observations is
ascribed to film shape dependent magnetoelastic coupling.


title:
The $l_q$ consistency of the Dantzig Selector for Cox's Proportional
  Hazards Model

abstract:
  The Dantzig selector for the proportional hazards model proposed by D.R. Cox
is studied in a high-dimensional and sparse setting. We prove the $l_q$
consistency for all $q \geq 1$ of some estimators based on the compatibility
factor, the weak cone invertibility factor, and the restricted eigenvalue for
certain deterministic matrix which approximates the Hessian matrix of log
partial likelihood. Our matrix conditions for these three factors are weaker
than those of previous researches.


title: Superlens induced loss-insensitive optical force

abstract:
  A slab with relative permittivity $\epsilon = - 1 + i\delta$ and permeability
$\mu = - 1 + i\delta $ has a critical distance away from the slab where a small
particle will either be cloaked or imaged depending on whether it is located
inside or outside that critical distance. We find that the optical force acting
on a small cylinder under plane wave illumination reaches a maximum value at
this critical distance. Contrary to the usual observation that superlens
systems should be highly loss-sensitive, this maximum optical force remains a
constant when loss is changed within a certain range. For a fixed particle-slab
distance, increasing loss can even amplify the optical force acting on the
small cylinder, contrary to the usual belief that loss compromises the response
of supenlens.


title: Polynomial dynamical systems and Korteweg--de Vries equation

abstract:
  In this work we explicitly construct polynomial vector fields
$\mathcal{L}_k,\;k=0,1,2,3,4,6$ on the complex linear space $\mathbb{C}^6$ with
coordinates $X=(x_2,x_3,x_4)$ and $Z=(z_4,z_5,z_6)$. The fields $\mathcal{L}_k$
are linearly independent outside their discriminant variety $\Delta \subset
\mathbb{C}^6$ and tangent to this variety. We describe a polynomial Lie algebra
of the fields $\mathcal{L}_k$ and the structure of the polynomial ring
$\mathbb{C}[X, Z]$ as a graded module with two generators $x_2$ and $z_4$ over
this algebra. The fields $\mathcal{L}_1$ and $\mathcal{L}_3$ commute. Any
polynomial $P(X,Z) \in \mathbb{C}[X, Z]$ determines a hyperelliptic function
$P(X,Z)(u_1, u_3)$ of genus $2$, where $u_1$ and $u_3$ are coordinates of
trajectories of the fields $\mathcal{L}_1$ and $\mathcal{L}_3$. The function $2
x_2(u_1, u_3)$ is a 2-zone solution of the KdV hierarchy and
$\frac{\partial}{\partial u_1}z_4(u_1, u_3)=\frac{\partial}{\partial
u_3}x_2(u_1, u_3)$.


title:
Two-Carrier Transport Induced Hall Anomaly and Large Tunable
  Magnetoresistance in Dirac Semimetal Cd3As2 Nanoplates

abstract:
  Cd3As2 is a model material of Dirac semimetal with a linear dispersion
relation along all three directions in the momentum space. The unique band
structure of Cd3As2 makes it with both Dirac and topological properties. It can
be driven into a Weyl semimetal by the symmetry breaking or a topological
insulator by enhancing the spin-orbit coupling. Here we report the temperature
and gate voltage dependent magnetotransport properties of Cd3As2 nanoplates
with Fermi level near the Dirac point. The Hall anomaly demonstrates the
two-carrier transport accompanied by a transition from n-type to p-type
conduction with decreasing temperature. The carrier-type transition is
explained by considering the temperature dependent spin-orbit coupling. The
magnetoresistance exhibits a large non-saturating value up to 2000% at high
temperatures, which is ascribed to the electron-hole compensation in the
system. Our results are valuable for understanding the experimental
observations related to the two-carrier transport in Dirac/Weyl semimetals,
such as Na3Bi, ZrTe5, TaAs, NbAs, and HfTe5.


title: A construction of $q$-ary linear codes with two weights

abstract:
  Linear codes with a few weights are very important in coding theory and have
attracted a lot of attention. In this paper, we present a construction of
$q$-ary linear codes from trace and norm functions over finite fields. The
weight distributions of the linear codes are determined in some cases based on
Gauss sums. It is interesting that our construction can produce optimal or
almost optimal codes. Furthermore, we show that our codes can be used to
construct secret sharing schemes with interesting access structures and
strongly regular graphs with new parameters.


title:
On recurrence and transience of multivariate near-critical stochastic
  processes

abstract:
  We obtain complementary recurrence and transience criteria for processes
$X=(X_n)_{n \ge 0}$ with values in $\mathbb R^d_+$ fulfilling a non-linear
equation $X_{n+1}=MX_n+g(X_n)+ \xi_{n+1}$. Here $M$ denotes a primitive matrix
having Perron-Frobenius eigenvalue 1, and $g$ denotes some function. The
conditional expectation and variance of the noise $(\xi_{n+1})_{n \ge 0}$ are
such that $X$ obeys a weak form of the Markov property. The results generalize
criteria for the 1-dimensional case in [5].


title: On a theorem of Avez

abstract:
  For each symmetric, aperiodic probability measure $\mu$ on a finitely
generated group $G$, we define a subset $A_{\mu}$ consisting of group elements
$g$ for which the limit of the ratio ${\mu^{\ast n}(g)}/{\mu^{\ast n}(e)}$
tends to $1$. We prove that $A_\mu$ is a subgroup, is amenable, contains every
finite normal subgroup, and $G=A_\mu$ if and only if $G$ is amenable. For
non-amenable groups we show that $A_\mu$ is not always a normal subgroup, and
can depend on the measure. We formulate some conjectures relating $A_\mu$ to
the amenable radical.


title:
Blueshifted [OI] lines from protoplanetary discs: the smoking gun of
  X-ray photoevaporation

abstract:
  Photoevaporation of protoplanetary discs by high energy radiation from the
central young stellar object is currently the favourite model to explain the
sudden dispersal of discs from the inside out. While several theoretical works
have provided a detailed pictured of this process, the direct observational
validation is still lacking. Emission lines produced in these slow moving
protoplanetary disc winds may bear the imprint of the wind structure and thus
provide a potential diagnostic of the underlying dispersal process. In this
paper we primarily focus on the collisionally excited neutral oxygen line at
6300A. We compare our models predictions to observational data and demonstrate
a thermal origin for the observed blueshifted low-velocity component of this
line from protoplanetary discs. Furthermore our models show that while this
line is a clear tell-tale-sign of a warm, quasi-neutral disc wind, typical of
X-ray photoevaporation, its strong temperature dependence makes it unsuitable
to measure detailed wind quantities like mass-loss-rate.


title: Coherence of Superpositions

abstract:
  Quantum coherence is important in quantum mechanics, and its essence is from
superposition principle. We study the coherence of any two pure states and that
of their arbitrary superposition, and obtain the relationship between them. In
the case that the two states have support on orthogonal subspaces, the
relationship is simple, that is, the difference between the coherence of their
superposition state and the average coherence of them is smaller than 1. In
other cases, we obtain different and a little more complicated relationships.
Furthermore, we also obtain the lower bound of coherence of superpositions.


title:
Fast Semantic Image Segmentation with High Order Context and Guided
  Filtering

abstract:
  This paper describes a fast and accurate semantic image segmentation approach
that encodes not only the discriminative features from deep neural networks,
but also the high-order context compatibility among adjacent objects as well as
low level image features. We formulate the underlying problem as the
conditional random field that embeds local feature extraction, clique potential
construction, and guided filtering within the same framework, and provide an
efficient coarse-to-fine solver. At the coarse level, we combine local feature
representation and context interaction using a deep convolutional network, and
directly learn the interaction from high order cliques with a message passing
routine, avoiding time-consuming explicit graph inference for joint probability
distribution. At the fine level, we introduce a guided filtering interpretation
for the mean field algorithm, and achieve accurate object boundaries with 100+
faster than classic learning methods. The two parts are connected and jointly
trained in an end-to-end fashion. Experimental results on Pascal VOC 2012
dataset have shown that the proposed algorithm outperforms the
state-of-the-art, and that it achieves the rank 1 performance at the time of
submission, both of which prove the effectiveness of this unified framework for
semantic image segmentation.


abstract:
  Replica placement (RP) intended at producing a set of duplicated data items
across the nodes of a distributed system in order to optimize fault tolerance,
availability, system performance load balancing. Typically, RP formulations
employ dynamic methods to change the replica placement in the system
potentially upon user request profile. Continuous Replica Placement Problem
(CRPP) is an extension of replica placement problem that takes into
consideration the current replication state of the distributed system along
with user request profile to define a new replication scheme, subject to
optimization criteria and constraints. This paper proposes an alternative
technique, named Availability Aware Continuous Replica Placement Problem
(AACRPP).AACRPP can be defined as: Given an already defined replica placement
scheme, a user request profile, and a node failure profile define a new
replication scheme, subject to optimization criteria and constraints. In this
effort we use modified greedy heuristics from the CRPP and investigated the
proposed mechanism using a trace driven java based simulation.


title:
A Reinforcement Learning System to Encourage Physical Activity in
  Diabetes Patients

abstract:
  Regular physical activity is known to be beneficial to people suffering from
diabetes type 2. Nevertheless, most such people are sedentary. Smartphones
create new possibilities for helping people to adhere to their physical
activity goals, through continuous monitoring and communication, coupled with
personalized feedback.
  We provided 27 sedentary diabetes type 2 patients with a smartphone-based
pedometer and a personal plan for physical activity. Patients were sent SMS
messages to encourage physical activity between once a day and once per week.
Messages were personalized through a Reinforcement Learning (RL) algorithm
which optimized messages to improve each participant's compliance with the
activity regimen. The RL algorithm was compared to a static policy for sending
messages and to weekly reminders.
  Our results show that participants who received messages generated by the RL
algorithm increased the amount of activity and pace of walking, while the
control group patients did not. Patients assigned to the RL algorithm group
experienced a superior reduction in blood glucose levels (HbA1c) compared to
control policies, and longer participation caused greater reductions in blood
glucose levels. The learning algorithm improved gradually in predicting which
messages would lead participants to exercise.
  Our results suggest that a mobile phone application coupled with a learning
algorithm can improve adherence to exercise in diabetic patients. As a learning
algorithm is automated, and delivers personalized messages, it could be used in
large populations of diabetic patients to improve health and glycemic control.
Our results can be expanded to other areas where computer-led health coaching
of humans may have a positive impact.


title:
Bayesian Network Structure Learning with Integer Programming: Polytopes,
  Facets, and Complexity

abstract:
  The challenging task of learning structures of probabilistic graphical models
is an important problem within modern AI research. Recent years have witnessed
several major algorithmic advances in structure learning for Bayesian
networks---arguably the most central class of graphical models---especially in
what is known as the score-based setting. A successful generic approach to
optimal Bayesian network structure learning (BNSL), based on integer
programming (IP), is implemented in the GOBNILP system. Despite the recent
algorithmic advances, current understanding of foundational aspects underlying
the IP based approach to BNSL is still somewhat lacking. Understanding
fundamental aspects of cutting planes and the related separation problem( is
important not only from a purely theoretical perspective, but also since it
holds out the promise of further improving the efficiency of state-of-the-art
approaches to solving BNSL exactly. In this paper, we make several theoretical
contributions towards these goals: (i) we study the computational complexity of
the separation problem, proving that the problem is NP-hard; (ii) we formalise
and analyse the relationship between three key polytopes underlying the
IP-based approach to BNSL; (iii) we study the facets of the three polytopes
both from the theoretical and practical perspective, providing, via exhaustive
computation, a complete enumeration of facets for low-dimensional
family-variable polytopes; and, furthermore, (iv) we establish a tight
connection of the BNSL problem to the acyclic subgraph problem.


title: Towards Empathetic Human-Robot Interactions

abstract:
  Since the late 1990s when speech companies began providing their
customer-service software in the market, people have gotten used to speaking to
machines. As people interact more often with voice and gesture controlled
machines, they expect the machines to recognize different emotions, and
understand other high level communication features such as humor, sarcasm and
intention. In order to make such communication possible, the machines need an
empathy module in them which can extract emotions from human speech and
behavior and can decide the correct response of the robot. Although research on
empathetic robots is still in the early stage, we described our approach using
signal processing techniques, sentiment analysis and machine learning
algorithms to make robots that can "understand" human emotion. We propose Zara
the Supergirl as a prototype system of empathetic robots. It is a software
based virtual android, with an animated cartoon character to present itself on
the screen. She will get "smarter" and more empathetic through its deep
learning algorithms, and by gathering more data and learning from it. In this
paper, we present our work so far in the areas of deep learning of emotion and
sentiment recognition, as well as humor recognition. We hope to explore the
future direction of android development and how it can help improve people's
lives.


title:
The hierarchies of "witnesses" and the properties and characterization
  of entangled states as super entanglement witnesses

abstract:
  Quantum entanglement lies at the heart of quantum mechanical and quantum
information processing. Following the question who \emph{witnesses}
entanglement witnesses, we show entangled states play as the role of super
entanglement witnesses. We show separable states play the role of "super super
entanglement witnesses" and "witness" other observables than entanglement
witnesses. We show that there exists a hierarchy structure of witnesses and
there exist "witnesses" everywhere. Furthermore, we show the properties and
characterization of entangled states as super entanglement witnesses. By the
role of super witnesses of entangled states, we immediately find the question
when different entanglement witnesses can detect the same entangled states
[{\it Phys. Lett. A }{\bf 356} 402 (2006)] is the same as the question when
different entangled states can be detected by the same entanglement witnesses
[{\it Phys. Rev. A} {\bf 75} 052333 (2007)]. By the role of "witnesses", we
define finer entangled states and optimal entangled states. The definition
gives a nonnumeric measurement of entanglement and an unambiguous
discrimination of entangled states, and the procedure of optimization for a
general entangled state $\rho$ is just finding the best separable approximation
(BSA) to $\rho$ in [ {\it Phys. Rev. Lett.} {\bf 80} 2261 (1998)].}


title: Wisdom of Crowds cluster ensemble

abstract:
  The Wisdom of Crowds is a phenomenon described in social science that
suggests four criteria applicable to groups of people. It is claimed that, if
these criteria are satisfied, then the aggregate decisions made by a group will
often be better than those of its individual members. Inspired by this concept,
we present a novel feedback framework for the cluster ensemble problem, which
we call Wisdom of Crowds Cluster Ensemble (WOCCE). Although many conventional
cluster ensemble methods focusing on diversity have recently been proposed,
WOCCE analyzes the conditions necessary for a crowd to exhibit this collective
wisdom. These include decentralization criteria for generating primary results,
independence criteria for the base algorithms, and diversity criteria for the
ensemble members. We suggest appropriate procedures for evaluating these
measures, and propose a new measure to assess the diversity. We evaluate the
performance of WOCCE against some other traditional base algorithms as well as
state-of-the-art ensemble methods. The results demonstrate the efficiency of
WOCCE's aggregate decision-making compared to other algorithms.


title: Laser-based X-ray and electron source for X-ray fluorescence studies

abstract:
  In this work we present a modification to conventional X-rays fluorescence
using electrons as excitation source, and compare it with the traditional X-ray
excitation for the study of pigments. For this purpose we have constructed a
laser-based source capable to produce X-rays as well as electrons. Because of
the large penetration depth of X-rays, the collected fluorescence signal is a
combination of several material layers of the artwork under study. However
electrons are stopped in the first layers allowing therefore a more superficial
analysis. We show that the combination of both excitation sources can provide
extremely valuable information about the structure of the artwork.


title:
Postprocessing of Non-Conservative Flux for Compatibility with Transport
  in Heterogeneous Media

abstract:
  A conservative flux postprocessing algorithm is presented for both
steady-state and dynamic flow models. The postprocessed flux is shown to have
the same convergence order as the original flux. An arbitrary flux
approximation is projected into a conservative subspace by adding a piecewise
constant correction that is minimized in a weighted $L^2$ norm. The application
of a weighted norm appears to yield better results for heterogeneous media than
the standard $L^2$ norm which has been considered in earlier works. We also
study the effect of different flux calculations on the domain boundary. In
particular we consider the continuous Galerkin finite element method for
solving Darcy flow and couple it with a discontinuous Galerkin finite element
method for an advective transport problem.


title: Normalized classes of generalized Burgers equations

abstract:
  A hierarchy of normalized classes of generalized Burgers equations is
studied. The equivalence groupoids of these classes are computed. The
equivalence groupoids of classes of linearizable generalized Burgers equations
are related to those of the associated linear counterparts using the Hopf--Cole
transformation.


title: Model-based Recursive Partitioning for Subgroup Analyses

abstract:
  The identification of patient subgroups with differential treatment effects
is the first step towards individualised treatments. A current draft guideline
by the EMA discusses potentials and problems in subgroup analyses and
formulated challenges to the development of appropriate statistical procedures
for the data-driven identification of patient subgroups. We introduce
model-based recursive partitioning as a procedure for the automated detection
of patient subgroups that are identifiable by predictive factors. The method
starts with a model for the overall treatment effect as defined for the primary
analysis in the study protocol and uses measures for detecting parameter
instabilities in this treatment effect. The procedure produces a segmented
model with differential treatment parameters corresponding to each patient
subgroup. The subgroups are linked to predictive factors by means of a decision
tree. The method is applied to the search for subgroups of patients suffering
from amyotrophic lateral sclerosis that differ with respect to their Riluzole
treatment effect, the only currently approved drug for this disease.


title:
Value function for regional control problems via dynamic programming and
  Pontryagin maximum principle

abstract:
  In this paper we focus on regional deterministic optimal control problems,
i.e., problems where the dynamics and the cost functional may be different in
several regions of the state space and present discontinuities at their
interface. Under the assumption that optimal trajectories have a locally finite
number of switchings (no Zeno phenomenon), we use the duplication technique to
show that the value function of the regional optimal control problem is the
minimum over all possible structures of trajectories of value functions
associated with classical optimal control problems settled over fixed
structures, each of them being the restriction to some submanifold of the value
function of a classical optimal control problem in higher dimension.The lifting
duplication technique is thus seen as a kind of desingularization of the value
function of the regional optimal control problem. In turn, we extend to
regional optimal control problems the classical sensitivity relations and we
prove that the regularity of this value function is the same (i.e., is not more
degenerate) than the one of the higher-dimensional classical optimal control
problem that lifts the problem.


title: Dirac's Equation in $R$-Minkowski Spacetime

abstract:
  We recently constructed the $R$-Poincar\'e algebra from an appropriate
deformed Poisson brackets which reproduce the Fock coordinate transformation.
We showed then that the spacetime of this transformation is the de Sitter one.
In this paper, we derive in the $R$-Minkowski spacetime the Dirac equation and
show that this is none other than the Dirac equation in the de Sitter spacetime
given by its conformally flat metric. Furthermore, we propose a new approach
for solving Dirac's equation in the de Sitter spacetime using the
Schr\"{o}dinger picture.


title: On the Torsion Anomalous Conjecture in CM abelian varieties

abstract:
  The Torsion Anomalous Conjecture (TAC) states that a subvariety V of an
abelian variety A has only finitely many maximal torsion anomalous
subvarieties. In this work we prove, with an effective method, some cases of
the TAC when the ambient variety A has CM, generalising our previous results in
products of CM elliptic curves. When V is a curve, we give new results and we
deduce some implications on the effective Mordell-Lang Conjecture.


title:
Entanglement Generation Between Two Mechanical Resonators in Two
  Optomechanical Cavities

abstract:
  A standard model is suggested to explore correlation features of two
spatially separated optomechanical cavities. The cavities are coupled through
the photon-hopping process. In particular, we investigate the generation of
entanglement between mechanical resonators in the strong coupling regime and
the two cavities are assumed to be driven by a coherent laser field. In order
to quantify entanglement we use the logarithmic negativity. The analytical
solutions are presented for the system in a parameter regime very close to the
current experimental results. We show that in the presence of the photon
hopping process between the cavities, the two mechanical resonators and the
field modes can be entangled. This shows clearly that the entanglement can be
transfer via radiation pressure of a photon hopping coupling from the
intracavity photon-phonon entanglements to an inter-cavity photon-photon or
phonon-phonon entanglement.


title:
On the dynamics of a non-local parabolic equation arising from the
  Gierer-Meinhardt system

abstract:
  The purpose of the current paper is to contribute to the comprehension of the
dynamics of the shadow system of an activator-inhibitor system known as a
Gierer-Meinhardt model. Shadow systems are intended to work as an intermediate
step between single equations and reaction-diffusion systems. In the case where
the inhibitor's response to the activator's growth is rather weak, then the
shadow system of the Gierer-Meinhardt model is reduced to a single though
non-local equation whose dynamics will be investigated. We mainly focus on the
derivation of blow-up results for this non-local equation which can be seen as
instability patterns of the shadow system. In particular, a {\it diffusion
driven instability (DDI)}, or {\it Turing instability}, in the neighbourhood of
a constant stationary solution, which it is destabilised via diffusion-driven
blow-up, is obtained. The latter actually indicates the formation of some
unstable patterns, whilst some stability results of global-in-time solutions
towards non-constant steady states guarantee the occurrence of some stable
patterns.


title: Applying Discrete Fourier Transform to the Hardy-Littlewood Conjecture

abstract:
  We study the asymptotic behaviour of the prime pair counting function
$\pi_{2k}(n)$ by the means of the discrete Fourier transform on $\mathbb{Z}/
n\mathbb{Z}$. The method we develop can be viewed as a discrete analog of the
Hardy-Littlewood circle method. We discuss some advantages this has over the
Fourier series on $\mathbb{R} /\mathbb{Z}$, which is used in the circle method.
We show how to recover the main term for $\pi_{2k}(n)$ predicted by the
Hardy-Littlewood Conjecture from the discrete Fourier series. The arguments
rely on interplay of Fourier transforms on $\mathbb{Z}/ n\mathbb{Z}$ and on its
subgroup $\mathbb{Z}/ Q\mathbb{Z},$ $Q \, | \, n.$


title: Higher order unfitted FEM for Stokes interface problems

abstract:
  We consider the discretization of a stationary Stokes interface problem in a
velocity-pressure formulation. The interface is described implicitly as the
zero level of a scalar function as it is common in level set based methods.
Hence, the interface is not aligned with the mesh. An unfitted finite element
discretization based on a Taylor-Hood velocity-pressure pair and an XFEM (or
CutFEM) modification is used for the approximation of the solution. This allows
for the accurate approximation of solutions which have strong or weak
discontinuities across interfaces which are not aligned with the mesh. To
arrive at a consistent, stable and accurate formulation we require several
additional techniques. First, a Nitsche-type formulation is used to implement
interface conditions in a weak sense. Secondly, we use the ghost penalty
stabilization to obtain an inf-sup stable variational formulation. Finally, for
the highly accurate approximation of the implicitly described geometry, we use
a combination of a piecewise linear interface reconstruction and a parametric
mapping of the underlying mesh. We introduce the method and discuss results of
numerical examples.


title:
Stable and convergent fully discrete interior-exterior coupling of
  Maxwell's equations

abstract:
  Maxwell's equations are considered with transparent boundary conditions, for
initial conditions and inhomogeneity having support in a bounded, not
necessarily convex three-dimensional domain or in a collection of such domains.
The numerical method only involves the interior domain and its boundary. The
transparent boundary conditions are imposed via a time-dependent boundary
integral operator that is shown to satisfy a coercivity property. The stability
of the numerical method relies on this coercivity and on an anti-symmetric
structure of the discretized equations that is inherited from a weak
first-order formulation of the continuous equations. The method proposed here
uses a discontinuous Galerkin method and the leapfrog scheme in the interior
and is coupled to boundary elements and convolution quadrature on the boundary.
The method is explicit in the interior and implicit on the boundary. Stability
and convergence of the spatial semidiscretization are proven, and with a
computationally simple stabilization term, this is also shown for the full
discretization.


title: Every filter is homeomorphic to its square

abstract:
  We show that every filter $\mathcal{F}$ on $\omega$, viewed as a subspace of
$2^\omega$, is homeomorphic to $\mathcal{F}^2$. This generalizes a theorem of
van Engelen, who proved that this holds for Borel filters.


title: Effect of Surface Grooves on the Static Friction of an Elastic Slider

abstract:
  Numerous studies have proved the usefulness of surface patterning for the
modification of tribological performances of sliding contacts. Here we
investigate the effects of patterning on the tribological properties of a
slider over a solid substrate. We show that, depending on the numerical density
of surface grooves, the tribological properties can change significantly. A low
density of surface patterning leads to a decrease of static friction force,
while a higher density weakens this effect. The decrease is related to a
non-uniform distribution of surface stress induced by patterning. We believe
these findings and approach to be relevant for technological applications and
related optimal design.


title: A self-similar solution for thermal disc winds

abstract:
  We derive a self-similar description for the 2D streamline topology and flow
structure of an axi-symmetric, thermally driven wind originating from a disc in
which the density is a power law function of radius. Our scale-free solution is
strictly only valid in the absence of gravity or centrifugal support;
comparison with 2D hydrodynamic simulations of winds from Keplerian discs
however demonstrates that the scale-free solution is a good approximation also
in the outer regions of such discs, and can provide a reasonable description
even for launch radii well within the gravitational radius of the flow.
Although other authors have considered the flow properties along streamlines
whose geometry has been specified in advance, this is the first isothermal
calculation in which the flow geometry and variation of flow variables along
streamlines is determined self-consistently. It is found that the flow
trajectory is very sensitive to the power-law index of radial density variation
in the disc: the steeper the density gradient, the stronger is the curvature of
streamlines close to the flow base that is required in order to maintain
momentum balance perpendicular to the flow. Steeper disc density profiles are
also associated with more rapid acceleration, and a faster fall-off of density,
with height above the disc plane. The derivation of a set of simple governing
equations for the flow structure of thermal winds from the outer regions of
power law discs offers the possibility of deriving flow observables without
having to resort to hydrodynamical simulation.


title:
Study of the phase diagram of dense two-color QCD within lattice
  simulation

abstract:
  In this paper we carry out a low-temperature scan of the phase diagram of
dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice
simulation with rooted staggered quarks. At small chemical potential we observe
the hadronic phase, where the theory is in a confining state, chiral symmetry
is broken, the baryon density is zero and there is no diquark condensate. At
the critical point $\mu = m_{\pi}/2$ we observe the expected second order
transition to Bose-Einstein condensation of scalar diquarks. In this phase the
system is still in confinement in conjunction with non-zero baryon density, but
the chiral symmetry is restored in the chiral limit. We have also found that in
the first two phases the system is well described by chiral perturbation
theory. For larger values of the chemical potential the system turns into
another phase, where the relevant degrees of freedom are fermions residing
inside the Fermi sphere, and the diquark condensation takes place on the Fermi
surface. In this phase the system is still in confinement, chiral symmetry is
restored and the system is very similar to the quarkyonic state predicted by
SU($N_c$) theory at large $N_c$.


title: Investigation of resonances in gravity-capillary wave turbulence

abstract:
  We report experimental results on nonlinear wave coupling in surface wave
turbulence on water at scales close to the crossover between surface gravity
waves and capillary waves. We study 3-wave correlations either in the frequency
domain or in wavevector domain. We observe that in a weakly nonlinear regime,
the dominant nonlinear interactions correspond to waves that are collinear or
close to collinear. Although the resonant coupling of pure gravity waves is
supposed to involve 4 waves, at the capillary crossover we observe a nonlocal
coupling between a gravity wave and 2 capillary waves. Furthermore nonlinear
spectral spreading permits 3-gravity wave coupling. These observations raise
the question of the relevance of these processes in the oceanographic context
and in particular the range of frequencies of gravity waves that may be
impacted.


title: The Emergence of Superconducting Systems in Anti-de Sitter Space

abstract:
  In this article, we investigate the mathematical relationship between a (3+1)
dimensional gravity model inside Anti-de Sitter space $\rm AdS_4$, and a (2+1)
dimensional superconducting system on the asymptotically flat boundary of $\rm
AdS_4$ (in the absence of gravity). We consider a simple case of the Type II
superconducting model (in terms of Ginzburg-Landau theory) with an external
perpendicular magnetic field ${\bf H}$. An interaction potential $V(r,\psi) =
\alpha(T)|\psi|^2/r^2+\chi|\psi|^2/L^2+\beta|\psi|^4/(2 r^k )$ is introduced
within the Lagrangian system. This provides more flexibility within the model,
when the superconducting system is close to the transition temperature $T_c$.
Overall, our result demonstrates that the two Ginzburg-Landau differential
equations can be directly deduced from Einstein's theory of general relativity.


title: Exotic finite functorial semi-norms on singular homology

abstract:
  Functorial semi-norms on singular homology give refined "size" information on
singular homology classes. A fundamental example is the l^1-semi-norm. We show
that there exist finite functorial semi-norms on singular homology that are
exotic in the sense that they are not carried by the l^1-semi-norm.


title:
SOS Methods for Multi-Delay Systems: A Dual Form of Lyapanov-Krasovskii
  Functional

abstract:
  We present a dual form of Lyapunov-Krasovskii functional which allows the
problem of controller synthesis of multi-delay systems to be formulated and
solved in a convex manner. First, we give a general form of dual stability
condition formulated in terms of Lyapunov operators which are positive,
self-adjoint and preserve the structure of the state-space. Second, we provide
a class of such operators and express the stability conditions as positivity
and negativity of quadratic Lyapunov-Krasovskii functional forms. Next, we
adapt the SOS methodology to express positivity and negativity of these forms
as LMIs, describing a new set of polynomial manipulation tools designed for
this purpose. Finally, we apply the resulting LMIs to a battery of numerical
examples and demonstrate that the stability conditions are not conservative.
The results of this paper are significant in that they open the way for dynamic
output H-infinity optimal control of systems with multiple time-delays.


title:
Flow field from transient bubble oscillation in a narrow gap: numerical
  simulations and effect on biological cells

abstract:
  The flow driven by a rapidly expanding and collapsing cavitation bubble in a
narrow cylindrical gap is studied with the volume of fluid method. The
simulations reveal a developing plug flow during the early expansion followed
by flow reversal at later stages. An adverse pressure gradient leads to
boundary layer separation and flow reversal, causing large shear stress near
the boundaries. Analytical solution to a planar pulsating flow shows
qualitative agreement with the CFD results. The shear stress close to
boundaries has implications to deformable objects located near the bubble:
experiments reveal that thin, flat biological cells entrained in the boundary
layer become stretched, while cells with a larger cross-section are mainly
transported with the flow.


title: Equivalence groupoid of generalized potential Burgers equations

abstract:
  We find the equivalence groupoid of a~class of $(1+1)$-dimensional
second-order evolution equations, which are called generalized potential
Burgers equations. This class is related via potentialization with two classes
of variable-coefficient generalized Burgers equations. Its equivalence groupoid
is of complicated structure and is described via partitioning the entire class
into three normalized subclasses such that there are no point transformations
between equations from different subclasses. For each of these subclasses we
construct its equivalence group of an appropriate kind.


title: A class of Banach algebras of generalized matrices

abstract:
  We introduce a class of Banach algebras of generalized matrices and study the
existence of approximate units, ideal structure, and derivations of them.


title: Lightweight LCP Construction for Very Large Collections of Strings

abstract:
  The longest common prefix array is a very advantageous data structure that,
combined with the suffix array and the Burrows-Wheeler transform, allows to
efficiently compute some combinatorial properties of a string useful in several
applications, especially in biological contexts. Nowadays, the input data for
many problems are big collections of strings, for instance the data coming from
"next-generation" DNA sequencing (NGS) technologies. In this paper we present
the first lightweight algorithm (called extLCP) for the simultaneous
computation of the longest common prefix array and the Burrows-Wheeler
transform of a very large collection of strings having any length. The
computation is realized by performing disk data accesses only via sequential
scans, and the total disk space usage never needs more than twice the output
size, excluding the disk space required for the input. Moreover, extLCP allows
to compute also the suffix array of the strings of the collection, without any
other further data structure is needed. Finally, we test our algorithm on real
data and compare our results with another tool capable to work in external
memory on large collections of strings.


title:
Exact Bethe ansatz solution for a quantum field model of interacting
  scalar fields in quasi-two dimensions

abstract:
  Integrable quantum field models are known to exist mostly in one
space-dimension. Exploiting the concept of multi-time in integrable systems and
a Lax matrix of higher scaling order, we construct a novel quantum field model
in quasi-two dimensions involving interacting fields. The Yang-Baxter
integrability is proved for the model by finding a new kind of commutation rule
for its basic fields, representing nonstandard scalar fields along the
transverse direction. In spite of a close link with the quantum Landau-Lifshitz
equation, the present model differs widely from it, in its content and the
result obtained. Using further the algebraic Bethe ansatz we solve exactly the
eigenvalue problem of this quantum field model for all its higher conserved
operators. The idea presented here should instigate the construction of a novel
class of integrable field and lattice models and exploration of a new type of
underlying algebras.

categories: nlin.SI cond-mat.stat-mech hep-th math-ph math.MP


title: Farthest point problem and M-compact sets

abstract:
  In this paper we give an elementary proof of the fact that every uniquely
remotal set is singleton in a finite dimensional strictly convex normed linear
space. We show that if A is a uniquely remotal M-compact subset with the
derived set of A non-empty then the derived set of A is M-compact and uniquely
remotal. We also show that if A is a uniquely remotal M-compact set and the
derived set of A is compact then A is singleton.


title:
Enhancement of electron hot spot relaxation in photoexcited plasmonic
  structures by thermal diffusion

abstract:
  We demonstrate that in confined plasmonic metal structures subject to
ultra-fast laser excitation electron thermal diffusion can provide relaxation
faster than the energy transfer to the lattice. This relaxation occurs due to
excitation of nanometer-sized hot spots in the confined structure and the
sensitivity of its optical parameters to the perturbation in these regions.
Both factors become essential when the plasmonic resonance condition is met for
both excitation and detection. A pump-probe experiment on plasmonic gold
lattices shows sub-picosecond relaxation with the characteristic times
well-described by a two-temperature model. The results suggest that dynamical
optical response in plasmonic structures can be tuned by selection of the
structural geometry as well as the choice of wavelength and polarization of the
excitation and detection light.


title: Limits on Non-Linear Electrodynamics

abstract:
  In this paper we set a framework in which experiments whose goal is to test
QED predictions can be used in a more general way to test non-linear
electrodynamics (NLED) which contains low-energy QED as a special case. We
review some of these experiments and we establish limits on the different free
parameters by generalizing QED predictions in the framework of NLED. We finally
discuss the implications of these limits on bound systems and isolated charged
particles for which QED has been widely and successfully tested.


title: A novel iterative method to approximate structured singular values

abstract:
  A novel method for approximating structured singular values (also known as
mu-values) is proposed and investigated. These quantities constitute an
important tool in the stability analysis of uncertain linear control systems as
well as in structured eigenvalue perturbation theory. Our approach consists of
an inner-outer iteration. In the outer iteration, a Newton method is used to
adjust the perturbation level. The inner iteration solves a gradient system
associated with an optimization problem on the manifold induced by the
structure. Numerical results and comparison with the well-known Matlab function
mussv, implemented in the Matlab Control Toolbox, illustrate the behavior of
the method.


title:
Evolution and control of the phase competition morphology in a manganite
  film

abstract:
  The competition among different phases in perovskite manganites is pronounced
since their energies are very close under the interplay of charge, spin,
orbital and lattice degrees of freedom. To reveal the roles of underlying
interactions, many efforts have been devoted towards directly imaging phase
transitions at microscopic scales. Here we show images of the charge-ordered
insulator (COI) phase transition from a pure ferromagnetic metal with reducing
field or increasing temperature in a strained phase-separated manganite film,
using a home-built magnetic force microscope. Compared with the COI melting
transition, this reverse transition is sharp, cooperative and martensitic-like
with astonishingly unique yet diverse morphologies. The COI domains show
variable-dimensional growth at different temperatures and their distribution
can illustrate the delicate balance of the underlying interactions in
manganites. Our findings also display how phase domain engineering is possible
and how the phase competition can be tuned in a controllable manner.


title: Raman fingerprints of atomically precise graphene nanoribbons

abstract:
  Bottom-up approaches allow the production of ultra-narrow and atomically
precise graphene nanoribbons (GNRs), with electronic and optical properties
controlled by the specific atomic structure. Combining Raman spectroscopy and
ab-initio simulations, we show that GNR width, edge geometry and functional
groups all influence their Raman spectra. The low-energy spectral region below
1000 cm-1 is particularly sensitive to edge morphology and functionalization,
while the D peak dispersion can be used to uniquely fingerprint the presence of
GNRs, and differentiates them from other sp2 carbon nanostructures.


title:
Curvilinear integral theorem for $G$-monogenic mappings in the algebra
  of complex quaternion

abstract:
  For $G$-monogenic mappings taking values in the algebra of complex quaternion
we prove a curvilinear analogue of the Cauchy integral theorem in the case
where a curve of integration lies on the boundary of a domain.


title: On the Origin of the $XYZ$ Mesons

abstract:
  In this talk we present a mechanism giving rise to exotic $XYZ$ four-quark
states in the meson spectra within a constituent quark model approach. We
discuss its generalization to five-quark states in the heavy baryon sector.
Finally, we revise some other works in the literature and experimental data
where this mechanism may be working.


title: Deeply bound $\Xi$ tribaryon

abstract:
  We have used realistic local interactions based on the recent update of the
strangeness $-2$ Nijmegen ESC08c potential to calculate the bound state problem
of the $\Xi NN$ system in the $(I)J^P=(\frac{1}{2})\frac{3}{2}^+$ state. We
found that this system presents a deeply bound state lying $13.5$ MeV below the
$\Xi d$ threshold. Since in lowest order, pure S$-$wave configuration, this
system can not decay into the open $\Lambda\Lambda N$ channel, its decay width
is expected to be very small. We have also recalculated the
$(I)J^P=(\frac{3}{2})\frac{1}{2}^+$ state and we have compared with results of
quark-model based potentials.


title:
Enhancement of the spin Hall voltage in a reverse-biased planar
  pn-junction

abstract:
  We report an experimental demonstration of a local amplification of the spin
Hall voltage using an expanding depletion zone at a pn-junction in GaAs/AlGaAs
Hall-bar microdevices. It is demonstrated that the depletion zone can be
spatially expanded by applying reverse bias by at least 10~$\mu$m at low
temperature. In the depleted regime, the spin Hall signals reached more than
one order of magnitude higher values than in the normal regime at the same
electrical current flowing through the micro-device. It is shown that the
pn-bias has two distinct effects on the detected spin Hall signal. It controls
the local drift field at the Hall cross which is highly non-linear in the
pn-bias due to the shift of the depletion front. Simultaneously, it produces a
change in the spin-transport parameters due to the non-linear change in the
carrier density at the Hall cross with the pn-bias.


title:
Optimal control of discrete-time linear fractional order systems with
  multiplicative noise

abstract:
  A finite horizon linear quadratic(LQ) optimal control problem is studied for
a class of discrete-time linear fractional systems (LFSs) affected by
multiplicative, independent random perturbations. Based on the dynamic
programming technique, two methods are proposed for solving this problem. The
first one seems to be new and uses a linear, expanded-state model of the LFS.
The LQ optimal control problem reduces to a similar one for stochastic linear
systems and the solution is obtained by solving Riccati equations. The second
method appeals to the Principle of Optimality and provides an algorithm for the
computation of the optimal control and cost by using directly the fractional
system. As expected, in both cases the optimal control is a linear function in
the state and can be computed by a computer program. Two numerical examples
proves the effectiveness of each method.


title: Energy Optimization of Memory Intensive Parallel workloads

abstract:
  Energy consumption is an important concern in modern multicore processors.
The energy consumed during the execution of an application can be minimized by
tuning the hardware state utilizing knobs such as frequency, voltage etc. The
existing theoretical work on energy mini- mization using Global DVFS (Dynamic
Voltage and Frequency Scaling), despite being thorough, ignores the energy
consumed by the CPU on memory accesses and the dynamic energy consumed by the
idle cores. This article presents an analytical model for the performance and
the overall energy consumed by the CPU chip on CPU instructions as well as the
memory accesses without ignoring the dynamic energy consumed by the idle cores.
We present an analytical framework around our energy-performance model to
predict the operating frequencies for global DVFS that minimize the overall CPU
energy consumption within a performance budget. Finally, we suggest a
scheduling criteria for energy aware scheduling of memory intensive parallel
applications.


title:
A data base of synthetic photometry in the GALEX ultraviolet bands for
  the stellar sources observed with the International Ultraviolet Explorer

abstract:
  The Galaxy Evolution Explorer (GALEX) has produced the largest photometric
catalogue of ultraviolet (UV) sources. As such, it has defined the new standard
bands for UV photometry: the near UV band (NUV) and the far UV band (FUV).
However, due to brightness limits, the GALEX mission has avoided the Galactic
plane which is crucial for astrophysical research and future space missions.
The International Ultraviolet Explorer (IUE) satellite obtained 63,755 spectra
in the low dispersion mode during its 18 years lifetime. We have derived the
photometry in the GALEX bands for the stellar sources in the IUE Archive to
extend the GALEX data base with observations including the Galactic plane.Good
quality spectra have been selected for all IUE classes of stellar sources. The
GALEX FUV and NUV magnitudes have been computed using the GALEX transmission
curves, as well as the conversion equations between flux and magnitudes
provided by the mission (galexgi.gsfc.nasa.gov). Consistency between GALEX and
IUE synthetic photometries has been tested using White Dwarfs (WD) contained in
both samples. The non-linear response performance of GALEX inferred from this
data agrees with the results from GALEX calibration. The photometric data base
is made available to the community through the services of the Centre de
Donn\'ees Stellaires at Strasbourg (CDS). The catalogue contains FUV magnitudes
for 1,631 sources, ranging from FUV=1.81 to FUV=18.65 mag. In the NUV band, the
catalogue includes observations for 1,005 stars ranging from NUV = 3.08 to NUV=
17.74 mag . UV photometry for 1,493 not included in the GALEX AIS GR5 catalogue
is provided; most of them are hot (O-A spectral type) stars. The sources in the
catalogue are distributed over the full sky, including the Galactic plane.


title:
Flexocoupling impact on the size effects of piezo- response and
  conductance in mixed-type ferroelectrics-semiconductors under applied
  pressure

abstract:
  Flexocoupling impact on the size effects of the spontaneous polarization,
effective piezo-response, elastic strain and compliance, carrier concentration
and piezo-conductance have been calculated in thin films of ferroelectric
semiconductors with mixed-type conductivity under applied pressure. Analysis of
the self-consistent calculation results revealed that the thickness dependences
of aforementioned physical quantities, calculated at zero and nonzero
flexoelectric couplings, are very similar under zero applied pressure, but
become strongly different under the application of external pressure pext. At
that the differences become noticeably stronger for the film surface under
compression than under tension. The impact of the Vegard mechanism on the size
effects is weaker in comparison with flexocoupling except for the thickness
dependence of the piezo-conductance. Without flexoelectric coupling the studied
physical quantities manifest conventional peculiarities that are characteristic
of the size-induced phase transitions. Namely, when the film thickness h
approaches the critical thickness hcr the transition to paraelectric phase
occurs. The combined effect of flexoelectric coupling and external pressure
induces polarizations at the film surfaces, which cause the electric built-in
field that destroys the thickness-induced phase transition to paraelectric
phase at h= hcr and induces the electret-like state with irreversible
spontaneous polarization at h<hcr. The built-in field leads to noticeable
increase of the average strain and elastic compliance under the film thickness
decrease below hcr that scales as 1/h at small thicknesses h. The changes of
the electron concentration by several orders of magnitude under positive or
negative pressures can lead to the occurrence of high- or low-conductivity
states, i.e. the nonvolatile piezo-resistive switching.


title: Magnetic edge states and magnetotransport in graphene antidot barriers

abstract:
  Magnetic fields are often used for characterizing transport in nanoscale
materials. Recent magnetotransport experiments have demonstrated that ballistic
transport is possible in graphene antidot lattices (GALs). These experiments
have inspired the present theoretical study of GALs in a perpendicular magnetic
field. We calculate magnetotransport through graphene antidot barriers (GABs),
which are finite rows of antidots arranged periodically in a pristine graphene
sheet, using a tight-binding model and the Landauer-B\"uttiker formula. We show
that GABs behave as ideal Dirac mass barriers for antidots smaller than the
magnetic length, and demonstrate the presence of magnetic edge states, which
are localized states on the periphery of the antidots due to successive
reflections on the antidot edge in the presence of a magnetic field. We show
that these states are robust against variations in lattice configuration and
antidot edge chirality. Moreover, we calculate the transmittance of disordered
GABs and find that magnetic edge states survive a moderate degree of disorder.
Due to the long phase-coherence length in graphene and the robustness of these
states, we expect magnetic edge states to be observable in experiments as well.


title: Every synaptic algebra has the monotone square root property

abstract:
  A synaptic algebra is a common generalization of several ordered algebraic
structures based on algebras of self-adjoint operators, including the
self-adjoint part of an AW*-algebra. In this paper we prove that a synaptic
algebra A has the monotone square property, i.e., if a and b are positive
elements, then if a is less or equal than b, then the square root of a is less
or equal than the square root of b.


title: Efficient conversion of light to charge and spin in Hall-bar microdevice


title: Non-degeneracy of the harmonic structure on Sierpinski Gaskets

abstract:
  We prove that the harmonic extension matrices for the level-k Sierpinski
Gasket are invertible for every k>2. This has been previously conjectured to be
true by Hino in [6] and [7] and tested numerically for k<50. We also give a
necessary condition for the non-degeneracy of the harmonic structure for
general finitely ramified self-similar sets based on the vertex connectivity of
their first graph approximation.


title: Division Rings with Ranks

abstract:
  Any superrosy division ring (i.e. a division ring equipped with an abstract
notion of rank) is shown to be centrally finite. Furthermore, division rings
satisfying a generalized chain condition on definable subgroups are studied. In
particular, a division ring of burden n has dimension at most n over its
center, and any definable group of definable automorphisms of a field of burden
n has size at most n. Additionally, interpretable division rings in o-minimal
structures are shown to be algebraically closed, real closed or the quaternions
over a real closed field.


title: Horosphere topology

abstract:
  We introduce a prime end-type theory on complete Kobayashi hyperbolic
manifolds using horosphere sequences. This allows to introduce a new notion of
boundary-new even in the unit disc in the complex space-the horosphere
boundary, and a topology on the manifold together with its horosphere boundary,
the horosphere topology. We prove that a bounded strongly pseudoconvex domain
endowed with the horosphere topology is homeomorphic to its Euclidean closure,
while for the polydisc such a horosphere topology is not even Hausdorff and is
different from the Gromov topology. We use this theory to study boundary
behavior of univalent maps from bounded strongly pseudoconvex domains. Among
other things, we prove that every univalent map of the unit ball whose image is
bounded and convex, extends as a homeomorphism up to the closure. Such a
result, relying in an essential way on our theory and on the Gromov
hyperbolicity theory, is completely new, dealing with non smooth domains.


title:
Chimera patterns induced by distance-dependent power-law coupling in
  ecological networks

abstract:
  This paper reports the occurrence of several chimera patterns and the
associated transitions among them in a network of coupled oscillators, which
are connected by a long range interaction that obeys a distance-dependent power
law. This type of interaction is common in physics and biology and constitutes
a general form of coupling scheme, where by tuning the power-law exponent of
the long range interaction the coupling topology can be varied from local via
nonlocal to global coupling. To explore the effect of the power-law coupling on
collective dynamics, we consider a network consisting of a realistic ecological
model of oscillating populations, namely the Rosenzweig--MacArthur model, and
show that the variation of the power-law exponent mediates transitions between
spatial synchrony and various chimera patterns. We map the possible
spatiotemporal states and their scenarios that arise due to the interplay
between the coupling strength and the power-law exponent.


title:
Exponential decay to equilibrium for a fibre lay-down process on a
  moving conveyor belt

abstract:
  We show existence and uniqueness of a stationary state for a kinetic
Fokker-Planck equation modelling the fibre lay-down process in the production
of non-woven textiles. Following a micro-macro decomposition, we use
hypocoercivity techniques to show exponential convergence to equilibrium with
an explicit rate assuming the conveyor belt moves slow enough. This work is an
extension of (Dolbeault et al., 2013), where the authors consider the case of a
stationary conveyor belt. Adding the movement of the belt, the global Gibbs
state is not known explicitly. We thus derive a more general hypocoercivity
estimate from which existence, uniqueness and exponential convergence can be
derived. To treat the same class of potentials as in (Dolbeault et al., 2013),
we make use of an additional weight function following the Lyapunov functional
approach in (Kolb et al., 2013).


title: Natural Language Semantics and Computability

abstract:
  This paper is a reflexion on the computability of natural language semantics.
It does not contain a new model or new results in the formal semantics of
natural language: it is rather a computational analysis of the logical models
and algorithms currently used in natural language semantics, defined as the
mapping of a statement to logical formulas - formulas, because a statement can
be ambiguous. We argue that as long as possible world semantics is left out,
one can compute the semantic representation(s) of a given statement, including
aspects of lexical meaning. We also discuss the algorithmic complexity of this
process.


title:
Lipschitz dependence of the coefficients on the resolvent and greedy
  approximation for scalar elliptic problems

abstract:
  We analyze the inverse problem of identifying the diffusivity coefficient of
a scalar elliptic equation as a function of the resolvent operator. We prove
that, within the class of measurable coefficients, bounded above and below by
positive constants, the resolvent determines the diffusivity in an unique
manner. Furthermore we prove that the inverse mapping from resolvent to the
coefficient is Lipschitz in suitable topologies. This result plays a key role
when applying greedy algorithms to the approximation of parameter-dependent
elliptic problems in an uniform and robust manner, independent of the given
source terms. In one space dimension the results can be improved using the
explicit expression of solutions, which allows to link distances between one
resolvent and a linear combination of finitely many others and the
corresponding distances on coefficients. These results are also extended to
multi-dimensional elliptic equations with variable density coefficients. We
also point out towards some possible extensions and open problems.