title: Retracts and algebraic properties of cut algebras

abstract:
  We study cut algebras which are toric rings associated to graphs. The key
idea is to consider suitable retracts to understand algebraic properties and
invariants of such algebras like being a complete intersection, having a linear
resolution, or the Castelnuovo-Mumford regularity. Throughout the paper, we
discuss several examples and pose some problems as well.


title: Wormholes leading to extra dimensions

abstract:
  In 6D general relativity with a scalar field as a source of gravity, a new
type of static wormhole solutions is presented: such wormholes connect our
universe with a small 2D extra subspace with a universe where this extra
subspace is large, and the whole space-time is effectively 6-dimensional. We
consider manifolds with the structure M0 x M1 x M2 , where M0 is 2D Lorentzian
space-time while each of M1 an M2 can be a 2-sphere or a 2-torus. After
selecting possible asymptotic behaviors of the metric functions compatible with
the field equations, we give two explicit examples of wormhole solutions with
spherical symmetry in our space-time and toroidal extra dimensions. In one
example, with a massless scalar field (it is a special case of a well-known
more general solution), the extra dimensions have a large constant size at the
"far end"; the other example contains a nonzero potential $V(\phi)$ which
provides a 6D anti-de Sitter asymptotic, where all spatial dimensions are
infinite.


title:
Incompressible Navier-Stokes Equations: Example of no solution at $R^3$
  and $t=0$

abstract:
  We provide an example of a smooth, divergence-free $\nabla \cdot
\vec{u}(\vec{x})=0$ velocity vector field $\vec{u}(\vec{x})$ for incompressible
fluid occupying all of $R^{3}$ space, and smooth vector field $\vec{f}(\vec{x},
t)$ for which the Navier-Stokes equation for incompressible fluid does not have
a solution for any position in space $\vec{x}\in R^{3} $ at $t=0$. The velocity
vector field $u_{i} (\vec{x})=2\frac{x_{h(i-1)} -x_{h(i+1)} }{\left(1+\sum
_{j=1}^{3}x_{j}^{2} \right)^{2} }$ ; $i=\{ 1,2,3\} $ where
$h(l)=\left\{\begin{array}{ccc} {l} & {;1\le l\le 3} & {} \\ {1} & {;l=4} & {}
\\ {3} & {;l=0} & {} \end{array}\right.$ is smooth, divergence-free,
continuously differentiable $u(\vec{x})\in C^{\infty }$, has bounded energy
$\int _{R^{3} }\left|\vec{u}\right|^{2} dx=\pi ^{2}$, zero velocity at
coordinate origin, and velocity converges to zero for $\left|\vec{x}\right|\to
\infty$. The vector field $\vec{f}(\vec{x},t)=(0,0,\frac{1}{1+t^{2} (\sum
_{j=1}^{3}x_{j} )^{2} )} $ is smooth, continuously differentiable
$f(\vec{x},t)\in C^{\infty }$, converging to zero for $\left|\vec{x}\right|\to
\infty$. Applying $\vec{u}(\vec{x})$ and $\vec{f}(\vec{x}, t)$ in the
Navier-Stokes equation for incompressible fluid results with three mutually
different solutions for pressure $p(\vec{x}, t)$, one of which includes zero
division with zero $\frac{0}{0}$ term at $t=0$, which is indeterminate for all
positions $\vec{x} \in R^{3}$.


title: Packing Hamilton Cycles Online

abstract:
  It is known that w.h.p. the hitting time $\tau_{2\sigma}$ for the random
graph process to have minimum degree $2\sigma$ coincides with the hitting time
for $\sigma$ edge disjoint Hamilton cycles. In this paper we prove an online
version of this property. We show that, for a fixed integer $\sigma\geq 2$, if
random edges of $K_n$ are presented one by one then w.h.p. it is possible to
color the edges online with $\sigma$ colors so that at time $\tau_{2\sigma}$,
each color class is Hamiltonian.


title: Passivity and practical work extraction using Gaussian operations

abstract:
  Quantum states that can yield work in a cyclical Hamiltonian process form one
of the primary resources in the context of quantum thermodynamics. Conversely,
states whose average energy cannot be lowered by unitary transformations are
called passive. However, while work may be extracted from non-passive states
using arbitrary unitaries, the latter may be hard to realize in practice. It is
therefore pertinent to consider the passivity of states under restricted
classes of operations that can be feasibly implemented. Here, we ask how
restrictive the class of Gaussian unitaries is for the task of work extraction.
We investigate the notion of Gaussian passivity, that is, we present necessary
and sufficient criteria identifying all states whose energy cannot be lowered
by Gaussian unitaries. For all other states we give a prescription for the
Gaussian operations that extract the maximal amount of energy. Finally, we show
that the gap between passivity and Gaussian passivity is maximal, i.e.,
Gaussian-passive states may still have a maximal amount of energy that is
extractable by arbitrary unitaries, even under entropy constraints.


title:
Orbital and physical parameters of eclipsing binaries from the ASAS
  catalogue -- IX. Spotted pairs with red giants

abstract:
  We present spectroscopic and photometric solutions for three spotted systems
with red giant components. Absolute physical and orbital parameters for these
double-lined detached eclipsing binary stars are presented for the first time.
These were derived from the V-, and I-band ASAS and WASP photometry, and new
radial velocities calculated from high quality optical spectra we obtained with
a wide range of spectrographs and using the two-dimensional cross-correlation
technique (TODCOR). All of the investigated systems (ASAS J184949-1518.7, BQ
Aqr, and V1207 Cen) show the differential evolutionary phase of their
components consisting of a main sequence star or a subgiant and a red giant,
and thus constitute very informative objects in terms of testing stellar
evolution models. Additionally, the systems show significant chromospheric
activity of both components. They can be also classified as classical RS
CVn-type stars. Besides the standard analysis of radial velocities and
photometry, we applied spectral disentangling to obtain separate spectra for
both components of each analysed system which allowed for a more detailed
spectroscopic study. We also compared the properties of red giant stars in
binaries that show spots, with those that do not, and found that the activity
phenomenon is substantially suppressed for stars with Rossby number higher than
$\sim$1 and radii larger than $\sim$20 R$_\odot$.


title:
Ultrafast spin-flip dynamics in transition metal complexes triggered by
  soft X-ray light

abstract:
  Recent advances in attosecond physics provide access to the correlated motion
of valence and core electrons on their intrinsic timescales. For valence
excitations, processes related to the electron spin are usually driven by
nuclear motion. For core-excited states, where the core hole has a nonzero
angular momentum, spin-orbit coupling is strong enough to drive spin-flips on a
much shorter time scale. Here, unprecedented short spin-crossover driven by
spin-orbit coupling is demonstrated for L-edge (2p$\rightarrow$3d) excited
states of a prototypical Fe(II) complex. It occurs on a time scale, which is
faster than the core hole lifetime of about 4~fs. A detailed analysis of such
phenomena will


title: Mollifying Networks

abstract:
  The optimization of deep neural networks can be more challenging than
traditional convex optimization problems due to the highly non-convex nature of
the loss function, e.g. it can involve pathological landscapes such as
saddle-surfaces that can be difficult to escape for algorithms based on simple
gradient descent. In this paper, we attack the problem of optimization of
highly non-convex neural networks by starting with a smoothed -- or
\textit{mollified} -- objective function that gradually has a more non-convex
energy landscape during the training. Our proposition is inspired by the recent
studies in continuation methods: similar to curriculum methods, we begin
learning an easier (possibly convex) objective function and let it evolve
during the training, until it eventually goes back to being the original,
difficult to optimize, objective function. The complexity of the mollified
networks is controlled by a single hyperparameter which is annealed during the
training. We show improvements on various difficult optimization tasks and
establish a relationship with recent works on continuation methods for neural
networks and mollifiers.


title:
Generalized SIR Analysis for Stochastic Heterogeneous Wireless Networks:
  Theory and Applications

abstract:
  This paper provides an analytically tractable framework of investigating the
statistical properties of the signal-to-interference power ratio (SIR) with a
general distribution in a heterogeneous wireless ad hoc network in which there
are K different types of transmitters (TXs) communicating with their unique
intended receiver (RX). The TXs of each type form an independent homogeneous
Poisson point process. In the first part of this paper, we introduce a novel
approach to deriving the Laplace transform of the reciprocal of the SIR and use
it to characterize the distribution of the SIR. Our main findings show that the
closed-form expression of the distribution of the SIR can be obtained whenever
the receive signal power has an Erlang distribution, and an almost closed-form
expression can be found if the power-law pathloss model has a pathloss exponent
of four. In the second part of this paper, we aim to apply the derived
distribution of the SIR in finding the two important performance metrics: the
success probability and ergodic link capacity. For each type of the RXs, the
success probability with (without) interference cancellation and that with
(without) the proposed stochastic power control are found in a compact form.
With the aid of the derived Shannon transform identity, the ergodic link
capacities of K-type RXs are derived with low complexity, and they can be
applied to many transmitting scenarios, such as multi-antenna communication and
stochastic power control. Finally, we analyze the spatial throughput capacity
of the heterogeneous network defined based on the derived K success
probabilities and ergodic link capacities and show the existence of its
maximum.


title: Stability and accuracy control of $\mathbf{k \cdot p}$ parameters

abstract:
  The $\mathbf{k \cdot p}$ method is a successful approach to obtain band
structure, optical and transport properties of semiconductors, and it depends
on external parameters that are obtained either from experiments, tight binding
or ab initio calculations. Despite the widespread use of the $\mathbf{k \cdot
p}$ method, a systematic analysis of the stability and the accuracy of its
parameters is not usual in the literature. In this work, we report a
theoretical framework to determine the $\mathbf{k \cdot p}$ parameters from
state-of-the-art hybrid density functional theory including spin-orbit
coupling, providing a calculation where the gap and spin-orbit energy splitting
are in agreement with the experimental values. The accuracy of the set of
parameters is enhanced by fitting over several directions at once, minimizing
the overall deviation from the original data. This strategy allows us to
systematically evaluate the stability, preserving the accuracy of the
parameters, providing a tool to determine optimal parameters for specific
ranges around the ${\Gamma}$-point. To prove our concept, we investigate the
zinc blende GaAs that shows results in excellent agreement with the most
reliable data in the literature.


title:
Ensemble of Jointly Trained Deep Neural Network-Based Acoustic Models
  for Reverberant Speech Recognition

abstract:
  Distant speech recognition is a challenge, particularly due to the corruption
of speech signals by reverberation caused by large distances between the
speaker and microphone. In order to cope with a wide range of reverberations in
real-world situations, we present novel approaches for acoustic modeling
including an ensemble of deep neural networks (DNNs) and an ensemble of jointly
trained DNNs. First, multiple DNNs are established, each of which corresponds
to a different reverberation time 60 (RT60) in a setup step. Also, each model
in the ensemble of DNN acoustic models is further jointly trained, including
both feature mapping and acoustic modeling, where the feature mapping is
designed for the dereverberation as a front-end. In a testing phase, the two
most likely DNNs are chosen from the DNN ensemble using maximum a posteriori
(MAP) probabilities, computed in an online fashion by using maximum likelihood
(ML)-based blind RT60 estimation and then the posterior probability outputs
from two DNNs are combined using the ML-based weights as a simple average.
Extensive experiments demonstrate that the proposed approach leads to
substantial improvements in speech recognition accuracy over the conventional
DNN baseline systems under diverse reverberant conditions.


title:
A note on the statistical sampling aspect of delayed choice entanglement
  swapping

abstract:
  Quantum and classical models for delayed choice entanglement swapping by
postselection of measurements are discussed.


title: Going Up and Lying Over in Congruence--modular Algebras

abstract:
  In this paper, we extend properties Going Up and Lying Over from ring theory
to the general setting of congruence--modular equational classes, using the
notion of prime congruence defined through the commutator. We show how these
two properties relate to each other, prove that they are preserved by finite
direct products and quotients and provide algebraic and topological
characterizations for them. We also point out many kinds of varieties in which
these properties always hold.


title: On the history of Levi-Civita's parallel transport

abstract:
  In this historical note, we wish to highlight the crucial conceptual role
played by the principle of virtual work of analytical mechanics, in working out
the fundamental notion of parallel transport on a Riemannian manifold, which
opened the way to the theory of connections and gauge theories. Moreover, after
a detailed historical-technical reconstruction of the original Levi-Civita's
argument, a further historiographical deepening and a related critical
discussion of the question, are pursued.


title: Sustainable theory of a logistic model - Fisher Information approach

abstract:
  Information theory provides a useful tool to understand the evolution of
complex nonlinear systems and their sustainability. In particular, Fisher
Information (FI) has been evoked as a useful measure of sustainability and the
variability of dynamical systems including self-organising systems. By
utilising FI, we investigate the sustainability of the logistic model for
different perturbations in the positive and/or negative feedback. Specifically,
we consider different oscillatory modulations in the parameters for positive
and negative feedbacks and investigate their effect on the evolution of the
system and Probability Density Functions (PDFs). Depending on the relative time
scale of the perturbation to the response time of the system (the linear growth
rate), we demonstrate the maintenance of the initial condition for a long time,
manifested by a broad bimodal PDF. We present the analysis of FI in different
cases and elucidate its implications for the sustainability of population
dynamics. We also show that a purely oscillatory growth rate can lead to a
finite amplitude solution while self-organisation of these systems can break
down with an exponentially growing solution due to the fluctuation in negative
feedback.


title: Sloan Great Wall as a complex of superclusters with collapsing cores

abstract:
  In the cosmic web, galaxy superclusters or their high-density cores are the
largest objects that may collapse at present or during the future evolution. We
study the dynamical state and possible future evolution of galaxy superclusters
from the Sloan Great Wall (SGW), the richest galaxy system in the nearby
Universe. We calculated supercluster masses using dynamical masses of galaxy
groups and stellar masses of galaxies. We employed normal mixture modelling to
study the structure of rich SGW superclusters and search for components (cores)
in superclusters. We analysed the radial mass distribution in the high-density
cores of superclusters centred approximately at rich clusters and used the
spherical collapse model to study their dynamical state. We found that the
lower limit of the total mass of the SGW is approximately $M =
2.5\times~10^{16}h^{-1}M_\odot$. Different mass estimators of superclusters
agree well, the main uncertainties in masses of superclusters come from missing
groups and clusters. We detected three high-density cores in the richest SGW
supercluster (SCl~027) and two in the second richest supercluster (SCl~019).
They have masses of $1.2 - 5.9 \times~10^{15}h^{-1}M_\odot$ and sizes of up to
$\approx 60 h^{-1}$ Mpc. The high-density cores of superclusters are very
elongated, flattened perpendicularly to the line of sight. The comparison of
the radial mass distribution in the high-density cores with the predictions of
spherical collapse model suggests that their central regions with radii smaller
than $8 h^{-1}$Mpc and masses of up to $M = 2\times~10^{15}h^{-1}M_\odot$ may
be collapsing. The rich SGW superclusters with their high-density cores
represent dynamically evolving environments for studies of the properties of
galaxies and galaxy systems.


title:
Symbolic estimation of distances between eigenvalues of Hermitian
  operator

abstract:
  We find out a method for symbolic estimation of a minimal (maximal) distance
between eigenvalues of a Hermitian matrix (or roots of a polynomial with real
(maybe degenerated) roots), using Hankel matrices formalism. The range of
location of eigenvalues is symbolically estimated too. All estimations can be
done with any precision.


title:
Generalized theta functions, strange duality, and odd orthogonal bundles
  on curves

abstract:
  This paper studies spaces of generalized theta functions for odd orthogonal
bundles with nontrivial Stiefel-Whitney class and the associated space of
twisted spin bundles. In particular, we prove a Verlinde type formula and a
dimension equality that was conjectured by Oxbury-Wilson. Modifying Hitchin's
argument, we also show that the bundle of generalized theta functions for
twisted spin bundles over the moduli space of curves admits a flat projective
connection. We furthermore address the issue of strange duality for odd
orthogonal bundles, and we demonstrate that the naive conjecture fails in
general. A consequence of this is the reducibility of the projective
representations of spin mapping class groups arising from the Hitchin
connection for these moduli spaces. Finally, we answer a question of
Nakanishi-Tsuchiya about rank-level duality for conformal blocks on the pointed
projective line with spin weights.


title:
Room temperature dynamic correlation between methylammonium molecules in
  lead-iodine based perovskites: An ab-initio molecular dynamics perspective

abstract:
  The high efficiency of lead organo-metal-halide perovskite solar cells has
raised many questions about the role of the methylammonium (MA) molecules in
the Pb-I framework. Experiments indicate that the MA molecules are able to
'freely' spin around at room temperature even though they carry an intrinsic
dipole moment. We have performed large supercell (2592 atoms) finite
temperature ab-initio molecular dynamics calculations to study the correlation
between the molecules in the framework. An underlying long range
anti-ferroelectric ordering of the molecular dipoles is observed. The dynamical
correlation between neighboring molecules shows a maximum around room
temperature in the mid-temperature phase. In this phase, the rotations are slow
enough to (partially) couple to neighbors via the Pb-I cage. This results in a
collective motion of neighboring molecules in which the cage acts as the
mediator. At lower and higher temperatures the motions are less correlated.


title:
The Cherenkov Telescope Array On-Site integral sensitivity: observing
  the Crab

abstract:
  The Cherenkov Telescope Array (CTA) is the future large observatory in the
very high energy (VHE) domain. Operating from 20 GeV to 300 TeV, it will be
composed of tens of Imaging Air Cherenkov Telescopes (IACTs) displaced in a
large area of a few square kilometers in both the southern and northern
hemispheres. The CTA/DATA On-Site Analysis (OSA) is the system devoted to the
development of dedicated pipelines and algorithms to be used at the CTA site
for the reconstruction, data quality monitoring, science monitoring and
realtime science alerting during observations. The OSA integral sensitivity is
computed here for the most studied source at Gamma-rays, the Crab Nebula, for a
set of exposures ranging from 1000 seconds to 50 hours, using the full CTA
Southern array. The reason for the Crab Nebula selection as the first example
of OSA integral sensitivity is twofold: (i) this source is characterized by a
broad spectrum covering the entire CTA energy range; (ii) it represents, at the
time of writing, the standard candle in VHE and it is often used as unit for
the IACTs sensitivity. The effect of different Crab Nebula emission models on
the CTA integral sensitivity is evaluated, to emphasize the need for
representative spectra of the CTA science targets in the evaluation of the OSA
use cases. Using the most complete model as input to the OSA integral
sensitivity, we obtain a significant detection of the Crab nebula (about 10% of
flux) even for a 1000 second exposure, for an energy threshold less than 10
TeV.


title: Unstructured Inversion of New Hope

abstract:
  Introduced as a new protocol first implemented in Google Chrome Canary, New
Hope is engineered as post-quantum cryptography for the TLS 1.2 protocol. The
structure of the exchange is lattice based, implementing Peikert's key
encapsulation mechanism as a modified form of ring learning with errors. The
search space used to introduce the closest-vector problem is generated by the
intersection of a tesseract and hexadecachoron. This intersection results in a
24-cell Voronoi tessellation. With respect to this tessellation, New Hope may
not withstand inversion attempts augmented with Grover's search algorithm.


title:
A Survey of the Local Group of Galaxies for Symbiotic Binary Stars. I.
  First detection of symbiotic stars in M33

abstract:
  We present and discuss initial selection criteria and first results in M33
from a systematic search for extragalactic symbiotic stars. We show that the
presence of diffuse interstellar gas emission can significantly contaminate the
spectra of symbiotic star candidates. This important effect forces upon us a
more stringent working definition of an extragalactic symbiotic star. We report
the first detections and spectroscopic characterisation of 12 symbiotic
binaries in M33. We found that four of our systems contain carbon-rich giants.
In another two of them the giant seems to be a Zr-enhanced MS star, while the
remaining six objects host M-type giants. The high number ratio of C to M
giants in these binaries is consistent with the low metallicity of M33. The
spatial and radial velocity distributions of these new symbiotic binaries are
consistent with a wide range of progenitor star ages.


title:
Zimmer's conjecture: Subexponential growth, measure rigidity, and strong
  property (T)

abstract:
  We prove several cases of Zimmer's conjecture for actions of higher-rank
cocompact lattices on low dimensional manifolds. For example, if $\Gamma$ is a
cocompact lattice in $\mathrm{Sl}(n, \mathbb R)$, $M$ is a compact manifold,
and $\omega$ a volume form on $M$ we show that any homomorphism $\rho\colon
\Gamma \rightarrow \mathrm{Diff}(M)$ has finite image if the dimension of $M$
is less than $n-1$ and that any homomorphism $\rho\colon \Gamma \rightarrow
\mathrm{Diff}(M,\omega)$ has finite image if the dimension of $M$ is less than
$n$. The key step in the proof is to show any such action has uniform
subexponential growth of derivatives. This is established using ideas from the
smooth ergodic theory of higher-rank abelian groups, structure theory of
semisimple groups and results from homogeneous dynamics. Having established
uniform subexponential growth of derivatives, we apply Lafforgue's strong
property (T) to establish the existence of an invariant Riemannian metric.


title:
Open Problem: Approximate Planning of POMDPs in the class of Memoryless
  Policies

abstract:
  Planning plays an important role in the broad class of decision theory.
Planning has drawn much attention in recent work in the robotics and sequential
decision making areas. Recently, Reinforcement Learning (RL), as an
agent-environment interaction problem, has brought further attention to
planning methods. Generally in RL, one can assume a generative model, e.g.
graphical models, for the environment, and then the task for the RL agent is to
learn the model parameters and find the optimal strategy based on these learnt
parameters. Based on environment behavior, the agent can assume various types
of generative models, e.g. Multi Armed Bandit for a static environment, or
Markov Decision Process (MDP) for a dynamic environment. The advantage of these
popular models is their simplicity, which results in tractable methods of
learning the parameters and finding the optimal policy. The drawback of these
models is again their simplicity: these models usually underfit and
underestimate the actual environment behavior. For example, in robotics, the
agent usually has noisy observations of the environment inner state and MDP is
not a suitable model.
  More complex models like Partially Observable Markov Decision Process (POMDP)
can compensate for this drawback. Fitting this model to the environment, where
the partial observation is given to the agent, generally gives dramatic
performance improvement, sometimes unbounded improvement, compared to MDP. In
general, finding the optimal policy for the POMDP model is computationally
intractable and fully non convex, even for the class of memoryless policies.
The open problem is to come up with a method to find an exact or an approximate
optimal stochastic memoryless policy for POMDP models.


title:
Ideas for best teaching integrals: we're teaching wrongly and how to do
  it right

abstract:
  We discuss some problems with the indefinite integral notation and the way of
teaching of integrals in Calculus. Based on the discussion, and in order to
avoid mistakes, we propose another notation for indefinite integrals.


title: A Unified Finite Element Method for Fluid-Structure Interaction

abstract:
  In this article, we present a new unified finite element method (UFEM) for
simulation of general Fluid-Structure interaction (FSI) which has the same
generality and robustness as monolithic methods but is significantly more
computationally efficient and easier to implement. Our proposed approach has
similarities with classical immersed finite element methods (IFEMs), by
approximating a single velocity and pressure field in the entire domain (i.e.
occupied by fluid and solid) on a single mesh, but differs by treating the
corrections due to the solid deformation on the left-hand side of the modified
fluid flow equations (i.e. implicitly). The method is described in detail,
followed by the presentation of multiple computational examples in order to
validate it across a wide range of fluid and solid parameters and interactions.


title: $\mu$Puppet: A Declarative Subset of the Puppet Configuration Language

abstract:
  Puppet is a popular declarative framework for specifying and managing complex
system configurations. The Puppet framework includes a domain-specific language
with several advanced features inspired by object-oriented programming,
including user-defined resource types, 'classes' with a form of inheritance,
and dependency management. Like most real-world languages, the language has
evolved in an ad hoc fashion, resulting in a design with numerous features,
some of which are complex, hard to understand, and difficult to use correctly.
  We present an operational semantics for $\mu$Puppet, a representative subset
of the Puppet language that covers the distinctive features of Puppet, while
excluding features that are either deprecated or work-in-progress. Formalising
the semantics sheds light on difficult parts of the language, identifies
opportunities for future improvements, and provides a foundation for future
analysis or debugging techniques, such as static typechecking or provenance
tracking. Our semantics leads straightforwardly to a reference implementation
in Haskell. We also discuss some of Puppet's idiosyncrasies, particularly its
handling of classes and scope, and present an initial corpus of test cases
supported by our formal semantics.


title: Hairy Lovelock black holes and Stueckelberg mechanism for Weyl symmetry

abstract:
  Lovelock theory of gravity -and, in particular, Einstein theory- admits black
hole solutions that can be equipped with a hair by conformally coupling the
theory to a real scalar field. This is a secondary hair, meaning that it does
not endow the black hole with new quantum numbers. It rather consists of a
non-trivial scalar field profile of fixed intensity which turns out to be
regular everywhere outside and on the horizon and, provided the cosmological
constant is negative, behaves at large distance in a way compatible with the
Anti-de Sitter (AdS) asymptotic. In this paper, we review the main features of
these hairy black hole solutions, such as their geometrical and thermodynamical
properties. The conformal coupling to matter in dimension $D>4$ in principle
includes higher-curvature terms. These couplings are obtained from the Lovelock
action through the Stueckelberg strategy. As a consequence, the resulting
scalar-tensor theory exhibits a self-duality under field redefinition that
resembles T-duality. Through this field redefinition, the matter content of the
theory transforms into a Lovelock action for a dual geometry. Since the hairy
black holes only exist for special relations between the dual Lovelock coupling
constants, it is natural to compare those relations with the causality bounds
coming from AdS/CFT. We observe that, while the lower causality bound is always
obeyed, the upper causality bound is violated. The latter, however, is
saturated in the large $D$ limit.


title: An image compression and encryption scheme based on deep learning

abstract:
  Stacked Auto-Encoder (SAE) is a kind of deep learning algorithm for
unsupervised learning. Which has multi layers that project the vector
representation of input data into a lower vector space. These projection
vectors are dense representations of the input data. As a result, SAE can be
used for image compression. Using chaotic logistic map, the compression ones
can further be encrypted. In this study, an application of image compression
and encryption is suggested using SAE and chaotic logistic map. Experiments
show that this application is feasible and effective. It can be used for image
transmission and image protection on internet simultaneously.


title: Bayesian Posteriors For Arbitrarily Rare Events

abstract:
  We study how much data a Bayesian observer needs to correctly infer the
relative likelihoods of two events when both events are arbitrarily rare. Each
period, either a blue die or a red die is tossed. The two dice land on side $1$
with unknown probabilities $p_1$ and $q_1$, which can be arbitrarily low. Given
a data-generating process where $p_1\ge c q_1$, we are interested in how much
data is required to guarantee that with high probability the observer's
Bayesian posterior mean for $p_1$ exceeds $(1-\delta)c$ times that for $q_1$.
If the prior densities for the two dice are positive on the interior of the
parameter space and behave like power functions at the boundary, then for every
$\epsilon>0,$ there exists a finite $N$ so that the observer obtains such an
inference after $n$ periods with probability at least $1-\epsilon$ whenever
$np_1\ge N$. The condition on $n$ and $p_1$ is the best possible. The result
can fail if one of the prior densities converges to zero exponentially fast at
the boundary.


title:
Gate-Tunable Negative Longitudinal Magnetoresistance in the Predicted
  Type-II Weyl Semimetal WTe2

abstract:
  The progress in exploiting new electronic materials and devices has been a
major driving force in solid-state physics. As a new state of matter, a Weyl
semimetal (WSM), particularly a type-II WSM, hosts Weyl fermions as emergent
quasiparticles and may harbor novel electrical transport properties because of
the exotic Fermi surface. Nevertheless, such a type-II WSM material has not
been experimentally observed in nature. In this work, by performing systematic
magneto-transport studies on thin films of a predicted material candidate WTe2,
we observe notable angle-sensitive (between the electric and magnetic fields)
negative longitudinal magnetoresistance (MR), which can likely be attributed to
the chiral anomaly in WSM. This phenomenon also exhibits strong planar
orientation dependence with the absence of negative longitudinal MR along the
tungsten chains (a axis), which is consistent with the distinctive feature of a
type-II WSM. By applying a gate voltage, we demonstrate that the Fermi energy
can be tuned through the Weyl points via the electric field effect; this is the
first report of controlling the unique transport properties in situ in a WSM
system. Our results have important implications for investigating simulated
quantum field theory in solid-state systems and may open opportunities for
implementing new types of electronic applications, such as field-effect chiral
electronic devices.


title:
Role of medium modifications for neutrino-pair processes from
  nucleon-nucleon bremsstrahlung - Impact on the protoneutron star
  deleptonization

abstract:
  In this article the neutrino-pair production from nucleon-nucleon (NN)
bremsstrahlung is explored via medium-modifications of the strong interactions
at the level of the one-pion exchange approximation. It governs the bulk part
of the NN interaction at low densities relevant for the neutrino physics in
core-collapse supernova studies. The resulting medium modified one-pion
exchange rate for the neutrino-pair processes is implemented in simulations of
core collapse supernovae in order to study the impact on the neutrino signal
emitted from the deleptonization of the nascent proto-neutron star.
Consequences for the nucleosynthesis of heavy elements of the material ejected
from the PNS surface are discussed.


title: The properties of squeezed optical states created in lossy cavities

abstract:
  We investigate theoretically the properties of squeezed states generated
using degenerate parametric down conversion in lossy cavities. We show that the
Lindblad master equation, which governs the evolution of this system, has as
its solution a squeezed thermal state with an effective temperature and
squeezing parameter that depends on time. We derive analytical solutions for
the time-evolution of quadrature noise, thermal photon number, squeezing
parameter, and total photon number under different pumping regimes. We also
find the steady state limits of the quadrature noises and discuss the $ g^{(2)}
$ factor of the generated light inside the cavity in the steady state.


title:
Automaticity in Computation and Student Success in Introductory Physical
  Science Courses

abstract:
  Between 1984 and 2011, the percentage of US bachelor degrees awarded in
physics declined by 25%, in chemistry declined by 33%, and overall in physical
sciences and engineering fell 40%. Data suggest that these declines are
correlated to a deemphasis in most states of practicing computation skills in
mathematics. Analysis of state standards put into place between 1990 and 2010
find that most states directed teachers to deemphasize both memorization and
student practice in computational problem solving. Available state test score
data show a significant decline in student computation skills. In recent
international testing, scores for US 16 to 24 year olds in numeracy finished
last among 22 tested nations in the OECD. Recent studies in cognitive science
have found that to solve well-structured problems in the sciences, students
must first memorize fundamental facts and procedures in mathematics and science
until they can be recalled with automaticity, then practice applying those
skills in a variety of distinctive contexts. Actions are suggested to improve
US STEM graduation rates by aligning US math and science curricula with the
recommendations of cognitive science.


title: A Fast Pseudo-Stochastic Sequential Cipher Generator Based on RBMs

abstract:
  Based on Restricted Boltzmann Machines (RBMs), an improved pseudo-stochastic
sequential cipher generator is proposed. It is effective and efficient because
of the two advantages: this generator includes a stochastic neural network that
can perform the calculation in parallel, that is to say, all elements are
calculated simultaneously; unlimited number of sequential ciphers can be
generated simultaneously for multiple encryption schemas. The periodicity and
the correlation of the output sequential ciphers meet the requirements for the
design of encrypting sequential data. In the experiment, the generated
sequential cipher is used to encrypt the image, and better performance is
achieved in terms of the key space analysis, the correlation analysis, the
sensitivity analysis and the differential attack. The experimental result is
promising that could promote the development of image protection in computer
security.


title: A conjecture about Gauss sums and bentness of binomial Boolean functions

abstract:
  In this note, the polar decomposition of binary fields of even extension
degree is used to reduce the evaluation of the Walsh transform of binomial
Boolean functions to that of Gauss sums. In the case of extensions of degree
four times an odd number, an explicit formula involving a Kloosterman sum is
conjectured, proved with further restrictions, and supported by extensive
experimental data in the general case. In particular, the validity of this
formula is shown to be equivalent to a simple and efficient characterization
for bentness previously conjectured by Mesnager.


title: Angular Momentum of Dark Matter Black Holes

abstract:
  The putative black holes which may constitute all the dark matter are
described by a Kerr metric with only two parameters, mass M and angular
momentum J. There has been little discussion of J since it plays no role in the
upcoming attempt at detection by microlensing. Nevertheless J does play a
central role in understanding the previous lack of detection, especially of CMB
distortion. We explain why bounds previously derived from lack of CMB
distortion are too strong for primordial black holes with J non-vanishing.
Almost none of the dark matter black holes can be from stellar collapse, and
nearly all are primordial, to avoid excessive CMB distortion.


title:
State transition and electrocaloric effect of BaZr$_{x}$Ti$_{1-x}$O$_3$:
  simulation and experiment

abstract:
  The electrocaloric effect (ECE) of BaZr$_{x}$Ti$_{1-x}$O$_3$ (BZT) is closely
related to the relaxor state transition of the materials. This work presents a
systematic study on the ECE and the state transition of the BZT, using a
combined canonical and microcanonical Monte Carlo simulations based a
lattice-based on a Ginzburg-Landau-type Hamiltonian. For comparison and
verification, experimental measurements have been carried on BTO and BZT
($x=0.12$ and $0.2$) samples, including the ECE at various temperatures, domain
patterns by Piezoresponse Force Microscopy at room temperature, and the P-E
loops at various temperatures. Results show that the dependency of BZT behavior
of the Zr-concentration can be classified into three different stages. In the
composition range of $ 0 \leq x \leq 0.2 $, ferroelectric domains are visible,
but ECE peak drops with increasing Zr-concentration harshly. In the range of $
0.3 \leq x \leq 0.7 $, relaxor features become prominent, and the decrease of
ECE with Zr-concentration is moderate. In the high concentration range of $ x
\geq 0.8 $, the material is almost nonpolar, and there is no ECE peak visible.
Results suggest that BZT with certain low range of Zr-concentration around
$x=0.12 \sim 0.3 $ can be a good candidate with relatively high ECE and
simutaneously wide temperature application range at rather low temperature.


title: Introduction to the Case Management Model and Notation (CMMN)

abstract:
  This is a short tutorial of the Case Management Model and Notation (CMMN)
version 1.0. It is targeted to readers with knowledge of basic process or
workflow modeling, and it covers the complete CMMN notation. A simple
complaints process is used to demonstrate the notation. At the end of the
tutorial the reader will be able to understand and create CMMN models. An
appendix summarizing the notation is included for reference purposes.


title:
A Measure of Directional Outlyingness with Applications to Image Data
  and Video

abstract:
  Functional data covers a wide range of data types. They all have in common
that the observed objects are functions of of a univariate argument (e.g. time
or wavelength) or a multivariate argument (say, a spatial position). These
functions take on values which can in turn be univariate (such as the
absorbance level) or multivariate (such as the red/green/blue color levels of
an image). In practice it is important to be able to detect outliers in such
data. For this purpose we introduce a new measure of outlyingness that we
compute at each gridpoint of the functions' domain. The proposed Directional
Outlyingness} (DO) measure accounts for skewness in the data and only requires
O(n) computation time per direction. We derive the influence function of the DO
and compute a cutoff for outlier detection. The resulting heatmap and
functional outlier map reflect local and global outlyingness of a function. To
illustrate the performance of the method on real data it is applied to spectra,
MRI images, and video surveillance data.


title: Finiteness of Composed local cohomology modules

abstract:
  Cofiniteness of the generalized local cohomology modules Hai(M, N) of two
R-modules M and N with respect to an ideal a is studied for some i,s with a
specified property. Furthermore, Artinianness of Hbj 0(Hai(M, N)) is
investigated by using the above result, in certain graded situations, where b 0
is an ideal of R 0 such that b 0 + a 0 is an m 0-primary ideal.


title:
Path-based vs. Distributional Information in Recognizing Lexical
  Semantic Relations

abstract:
  Recognizing various semantic relations between terms is beneficial for many
NLP tasks. While path-based and distributional information sources are
considered complementary for this task, the superior results the latter showed
recently suggested that the former's contribution might have become obsolete.
We follow the recent success of an integrated neural method for hypernymy
detection (Shwartz et al., 2016) and extend it to recognize multiple relations.
The empirical results show that this method is effective in the multiclass
setting as well. We further show that the path-based information source always
contributes to the classification, and analyze the cases in which it mostly
complements the distributional information.


title: Cram\'er type moderate deviations for trimmed L-statistics

abstract:
  We establish Cram\'er type moderate deviation (MD}) results for heavy trimmed
L-statistics; we obtain our results under a very mild smoothness condition on
the inversion $F^{-1}$ ($F$ is the underlying distribution of i.i.d.
observations) near two points, where trimming occurs, we assume also some
smoothness of weights of the L-statistic. Our results complement previous work
on Cram\'er type large deviations (LD) for trimmed L-statistics by Gribkova
(2016) and Callaert et al. (1982).


title: The circumstellar environment of pre-SN Ia systems

abstract:
  Here we explore the possible preexisting circumstellar debris of supernova
type Ia systems. Classical, symbiotic and recurrent novae all accrete onto
roughly solar mass white dwarfs from main sequence or Mira type companions and
result in thermonuclear runaways and expulsion of the accreted material at high
velocity. The expelled material forms a fast moving shell that eventually slows
to planetary nebula expansion velocities within several hundred years. All such
systems are recurrent and thousands of shells (each of about 0.001 Mo) snow
plough into the environment. As these systems involve common envelope binaries
the material is distributed in a non-spherical shell. These systems could be
progenitors of some SN Ia and thus explode into environments with large amounts
of accumulated gas and dust distributed in thin non-spherical shells. Such
shells should be observable around 100 years after a SN Ia event in a radio
flash as the SN Ia debris meets that of the ejected material of the systems
previous incarnation.


title: Ice Grain Collisions in Comparison: CO$_2$, H$_2$O and their Mixtures

abstract:
  Collisions of ice particles play an important role in the formation of
planetesimals and comets. In recent work we showed, that CO$_2$ ice behaves
like silicates in collisions. The resulting assumption was that it should
therefore stick less efficiently than H$_2$O ice. Within this paper a
quantification of the latter is presented. We used the same experimental setup
to study collisions of pure CO$_2$ ice, pure water ice and 50\% mixtures by
mass between CO$_2$ and water at 80K, 1 mbar and an average particle size of
$\sim 90 \mu$m. The results show a strong increase of the threshold velocity
between sticking and bouncing with increasing water content. This supports the
idea that water ice is favorable for early growth phases of planets in a zone
within the H$_2$O and the CO$_2$ iceline.


title: Electronic properties of 8-Pmmn borophene

abstract:
  First-principles calculations on monolayer 8-{\it Pmmn} borophene are
reported to reveal unprecedented electronic properties in a two-dimensional
material. Based on a Born effective charge analysis, 8-{\it Pmmn} borophene is
the first single-element based monolayered material exhibiting two sublattices
with substantial ionic features. The observed Dirac cones are actually formed
by the p$_z$ orbitals of one of the inequivalent sublattices composed of
uniquely four atoms, yielding an underlying hexagonal network topologically
equivalent to distorted graphene. A significant physical outcome of this effect
includes the possibility of converting metallic 8-{\it Pmmn} borophene into an
indirect band gap semiconductor by means of external shear stress. The
stability of the strained structures are supported by a phonon frequency
analysis. The Dirac cones are sensitive to the formation of vacancies only in
the inequivalent sublattice electronically active at the Fermi level.


title: Dilational Symmetry-Breaking in Thermodynamics

abstract:
  Using thermodynamic relations and dimensional analysis we derive a general
formula for the thermodynamical trace $2\mathcal{E}-DP$ for non-relativistic
systems and $\mathcal{E-DP}$ for relativistic systems, where $D$ is the number
of spatial dimensions, in terms of the microscopic scales of the system within
the grand canonical ensemble. We demonstrate the formula for several cases,
including anomalous systems which develop scales through dimensional
transmutation. Using this relation, we make explicit the connection between
dimensional analysis and the virial theorem. This paper is focused mainly on
the non-relativistic aspects of this relation.


title:
Statistical Cosmological Fermion Systems With Interparticle Fantom
  Scalar Interaction

abstract:
  The article represents a research of the cosmological evolution of fermion
statistical systems with fantom scalar interaction where "kinetic" term's
contribution to the total energy of a scalar field is negative. As a result of
analytical and numerical simulation of such systems it has been revealed a
existence of four possible scenarios depending on parameters of the system and
initial conditions. Among these scenarios there are scenarios with an early,
intermediate and late non-relativistic stages of the cosmological evolution,
all of which also have necessary inflation stage.


title:
Competitive Heterogeneous Nucleation onto a Microscopic Impurity in a
  Potts Model

abstract:
  Many metastable systems can nucleate to multiple competing stable or
intermediate metastable states. In this work, a Potts model, subject to
external fields, is used to study the competitive nucleation of two phases
attempting to grow on a microscopic impurity. Monte Carlo simulations are used
to calculate the free energy surfaces for the system under different
conditions, where the relative stability of the phases is adjusted by changing
the interaction parameters, and the nucleation rates obtained using
multicomponent transition state theory are compared with the rates measured
using the survival probability method. We find that the two methods predict
similar nucleation rates when the free energy barrier used in the transition
state theory is defined as the work required to form a critical embryo from the
metastable phase. An analysis of the free energy surfaces also reveals that the
competition between the nucleating phases leads to an effective drying of the
impurity which slows down the nucleation rate compared to the single phase
case.


title:
Electronic tunability of the frustrated triangular-lattice cluster
  magnet LiZn$_{2-x}$Mo$_3$O$_8$

abstract:
  LiZn$_2$Mo$_3$O$_8$ is an electrically insulating geometrically frustrated
antiferromagnet in which inorganic Mo$_3$O$_{13}$ clusters each behaves as a
single $S = 1/2$ unit, with the clusters arranged on a two-dimensional
triangular lattice. Prior results have shown that LiZn$_2$Mo$_3$O$_8$ does not
exhibit static magnetic order down to at least $T = 0.05\,K$, and instead
possesses a valence bond ground state. Here, we show that LiZn$_2$Mo$_3$O$_8$
can be hole doped by oxidation with $\mathrm{I}_2$ and subsequent removal of
$\mathrm{Zn}^{2+}$ cations to access the entire range of electron count, from
one to zero unpaired electrons per site on the triangular lattice. Contrary to
expectations, no metallic state is induced; instead, the primary effect is to
suppress the number of sites contributing to the condensed valence-bond state.
Further, diffraction and pair-distribution function analysis show no evidence
for local Jahn-Teller distortions or other deviations from the parent trigonal
symmetry as a function of doping or temperature. Taken together, the data and
density functional theory calculations indicate that removal of electrons from
the magnetic layers favors Anderson localization of the resulting hole and an
increase in the electrical band-gap over the formation of a metallic and
superconducting state. These results put strong constraints on the chemical
conditions necessary to realize metallic states from parent insulating
geometrically frustrated antiferromagnets.


title:
Field effect in stacked van der Waals heterostructures: Stacking
  sequence matters

abstract:
  Stacked van der Waals (vdW) heterostructures where semi-conducting
two-dimensional (2D) materials are contacted by overlayed graphene electrodes
enable atomically-thin, flexible electronics. We use first-principles quantum
transport simulations of graphene-contacted MoS2 devices to show how the
transistor effect critically depends on the stacking configuration relative to
the gate electrode. We can trace this behavior to the stacking-dependent
response of the contact region to the capacitive electric field induced by the
gate. The contact resistance is a central parameter and our observation
establish an important design rule for devices based on 2D atomic crystals.


title:
Risk reduction and Diversification within Markowitz's Mean-Variance
  Model: Theoretical Revisit

abstract:
  The conventional wisdom of mean-variance (MV) portfolio theory asserts that
the nature of the relationship between risk and diversification is a decreasing
asymptotic function, with the asymptote approximating the level of portfolio
systematic risk or undiversifiable risk. This literature assumes that investors
hold an equally-weighted or a MV portfolio and quantify portfolio
diversification using portfolio size. However, the equally-weighted portfolio
and portfolio size are MV optimal if and only if asset returns distribution is
exchangeable or investors have no useful information about asset expected
return and risk. Moreover, the whole of literature, absolutely all of it,
focuses only on risky assets, ignoring the role of the risk free asset in the
efficient diversification. Therefore, it becomes interesting and important to
answer this question: how valid is this conventional wisdom when investors have
full information about asset expected return and risk and asset returns
distribution is not exchangeable in both the case where the risk free rate is
available or not? Unfortunately, this question have never been addressed in the
current literature. This paper fills the gap.


title:
Effects of Backreaction on Power-Maxwell Holographic Superconductors in
  Gauss-Bonnet Gravity

abstract:
  We analytically and numerically investigate the properties of s-wave
holographic superconductors by considering the effects of scalar and gauge
fields on the background geometry in five dimensional Einstein-Gauss-Bonnet
gravity. We assume the gauge field to be in the form of the Power-Maxwell
nonlinear electrodynamics. We employ the Sturm-Liouville eigenvalue problem for
analytical calculation of the critical temperature and the shooting method for
the numerical investigation. Our numerical and analytical results indicate that
higher curvature corrections affect condensation of the holographic
superconductors with backreaction. We observe that the backreaction can
decrease the critical temperature of the holographic superconductors, while the
Power-Maxwell electrodynamics and Gauss-Bonnet coefficient term may increase
the critical temperature of the holographic superconductors. We find that the
critical exponent has the mean-field value $\beta=1/2$, regardless of the
values of Gauss-Bonnet coefficient, backreaction and Power-Maxwell parameters.


title: First image of the L1157 molecular jet by the CALYPSO IRAM-PdBI survey

abstract:
  Fast jets are thought to be a crucial ingredient of star formation because
they might extract angular momentum from the disk and thus allow mass accretion
onto the star. However, it is unclear whether jets are ubiquitous, and
likewise, their contribution to mass and angular momentum extraction during
protostar formation remains an open question.
  Our aim is to investigate the ejection process in the low-mass Class 0
protostar L1157. This source is associated with a spectacular bipolar outflow,
and the recent detection of high-velocity SiO suggests the occurrence of a jet.
  Observations of CO 2-1 and SiO 5-4 at 0.8" resolution were obtained with the
IRAM Plateau de Bure Interferometer as part of the CALYPSO large program. The
jet and outflow structure were fit with a precession model. We derived the
column density of CO and SiO, as well as the jet mass-loss rate and mechanical
luminosity.
  High-velocity CO and SiO emission resolve for the first time the first 200 au
of the outflow-driving molecular jet. The jet is strongly asymmetric, with the
blue lobe 0.65 times slower than the red lobe. This suggests that the
large-scale asymmetry of the outflow is directly linked to the jet velocity and
that the asymmetry in the launching mechanism has been at work for the past
1800 yr. Velocity asymmetries are common in T Tauri stars, which suggests that
the jet formation mechanism from Class 0 to Class II stages might be similar.
Our model simultaneously fits the inner jet and the clumpy 0.2 pc scale outflow
by assuming that the jet precesses counter-clockwise on a cone inclined by 73
degree to the line of sight with an opening angle of 8 degree on a period of
1640 yr. The estimated jet mass flux and mechanical luminosity are 7.7e-7
Msun/yr, and 0.9 Lsun, indicating that the jet could extract at least 25% of
the gravitational energy released by the forming star.


title:
Nekrasov and Argyres-Douglas theories in spherical Hecke algebra
  representation

abstract:
  AGT conjecture connects Nekrasov instanton partition function of 4D quiver
gauge theory with 2D Liouville conformal blocks. We re-investigate this
connection using the central extension of spherical Hecke algebra in
q-coordinate representation, q being the instanton expansion parameter. Based
on AFLT basis together with interwiners we construct gauge conformal state and
demonstrate its equivalence to the Liouville conformal state, with careful
attention to the proper scaling behavior of the state. Using the colliding
limit of regular states, we obtain the formal expression of irregular conformal
states corresponding to Argyres-Douglas theory, which involves summation of
functions over Young diagrams.


title:
The History of GRB Outflows: Ejection Lorentz Factor and Radiation
  Location of X-Ray Flares

abstract:
  We present time-resolved spectral analysis of the steep decay segments of 29
bright X-ray flares of gamma-ray bursts (GRBs) observed with the Swift/X-ray
telescope, and model their lightcurves and spectral index evolution behaviors
with the curvature effect model. Our results show that the observed rapid flux
decay and strong spectral index evolution with time can be well fit with this
model, and the derived characteristic timescales ($t_c$) are in the range of
$33\sim 264$ seconds. Using an empirical relation between the peak luminosity
and the Lorentz factor derived from the prompt gamma-rays, we estimate the
Lorentz factors of the flares ($\Gamma_{\rm X}$). We obtain $\Gamma_{\rm
X}=17\sim 87$ with a median value of $52$, which is smaller than the initial
Lorentz factors of prompt gamma-ray fireballs. With the derived $t_c$ and
$\Gamma_{\rm X}$, we constrain the radiating regions of 13 X-ray flares,
yielding $R_{\rm X}=(0.2\sim 1.1)\times 10^{16}$ cm, which are smaller than the
radii of the afterglow fireballs at the peak times of the flares. A long
evolution feature from prompt gamma-ray phase to the X-ray epoch is found by
incorporating our results with a sample of GRBs whose initial Lorentz factors
are available in literatures, i.e., $\Gamma\propto [t_{p}/(1+z)]^{-0.69\pm
0.06}$. These results may shed lights on the long term evolution of GRB central
engines.


title: Local structure of percolating gels at very low volume fractions

abstract:
  The formation of colloidal gels is strongly dependent on the volume fraction
of the system and the strength of the interactions between the colloids. Here
we explore very dilute solutions by the means of numerical simulations, and
show that, in the absence of hydrodynamic interactions and for sufficiently
strong interactions, percolating colloidal gels can be realised at very low
values of the volume fraction. Characterising the structure of the network of
the arrested material we find that, when reducing the volume fraction, the gels
are dominated by low-energy local structures, analogous to the isolated
clusters of the interaction potential. Changing the strength of the interaction
allows us to tune the compactness of the gel as characterised by the fractal
dimension, with low interaction strength favouring more chain-like structures.


title:
Turbulent thermal diffusion in strongly stratified turbulence: theory
  and experiments

abstract:
  Turbulent thermal diffusion is a combined effect of the temperature
stratified turbulence and inertia of small particles. It causes the appearance
of a non-diffusive turbulent flux of particles in the direction of the
turbulent heat flux. This non-diffusive turbulent flux of particles is
proportional to the product of the mean particle number density and the
effective velocity of inertial particles. The theory of this effect has been
previously developed only for small temperature gradients and small Stokes
numbers (Phys. Rev. Lett. {\bf 76}, 224, 1996). In this study a generalized
theory of turbulent thermal diffusion for arbitrary temperature gradients and
Stokes numbers has been developed. The laboratory experiments in the
oscillating grid turbulence and in the multi-fan produced turbulence have been
performed to validate the theory of turbulent thermal diffusion in strongly
stratified turbulent flows. It has been shown that the ratio of the effective
velocity of inertial particles to the characteristic vertical turbulent
velocity for large Reynolds numbers is less than 1. The effective velocity of
inertial particles as well as the effective coefficient of turbulent thermal
diffusion increase with Stokes numbers reaching the maximum at small Stokes
numbers and decreases for larger Stokes numbers. The effective coefficient of
turbulent thermal diffusion also decreases with the mean temperature gradient.
It has been demonstrated that the developed theory is in a good agreement with
the results of the laboratory experiments.

categories: physics.flu-dyn astro-ph.EP physics.ao-ph physics.geo-ph


title:
Learning Topology of Distribution Grids using only Terminal Node
  Measurements

abstract:
  Distribution grids include medium and low voltage lines that are involved in
the delivery of electricity from substation to end-users/loads. A distribution
grid is operated in a radial/tree-like structure, determined by switching on or
off lines from an underling loopy graph. Due to the presence of limited
real-time measurements, the critical problem of fast estimation of the radial
grid structure is not straightforward. This paper presents a new learning
algorithm that uses measurements only at the terminal or leaf nodes in the
distribution grid to estimate its radial structure. The algorithm is based on
results involving voltages of node triplets that arise due to the radial
structure. The polynomial computational complexity of the algorithm is
presented along with a detailed analysis of its working. The most significant
contribution of the approach is that it is able to learn the structure in
certain cases where available measurements are confined to only half of the
nodes. This represents learning under minimum permissible observability.
Performance of the proposed approach in learning structure is demonstrated by
experiments on test radial distribution grids.


title: Random self-similar trees and a hierarchical branching process

abstract:
  We study self-similarity in random binary rooted trees. In a well-understood
case of Galton-Watson trees, a distribution on a space of trees is said to be
self-similar if it is invariant with respect to the operation of pruning, which
cuts the tree leaves. This only happens for the critical Galton-Watson tree (a
constant process progeny), which also exhibits other special symmetries. We
extend the prune-invariance setup to arbitrary binary trees with edge lengths.
In this general case the class of self-similar processes becomes much richer
and covers a variety of practically important situations. The main result is
construction of the hierarchical branching processes that satisfy various
self-similarity definitions (including mean self-similarity and self-similarity
in edge-lengths) depending on the process parameters. Taking the limit of
averaged stochastic dynamics, as the number of trajectories increases, we
obtain a deterministic system of differential equations that describes the
process evolution. This system is used to establish a phase transition that
separates fading and explosive behavior of the average process progeny. We
describe a class of critical Tokunaga processes that happen at the phase
transition boundary. They enjoy multiple additional symmetries and include the
celebrated critical binary Galton-Watson tree with independent exponential edge
length as a special case. Finally, we discuss a duality between trees and
continuous functions, and introduce a class of extreme-invariant processes,
constructed as the Harris paths of a self-similar hierarchical branching
process, whose local minima has the same (linearly scaled) distribution as the
original process.


title:
Fluctuations of Ergodic Averages for Actions of Groups of Polynomial
  Growth

abstract:
  It was shown by S. Kalikow and B. Weiss that, given a measure-preserving
action of $\mathbb{Z}^d$ on a probability space $X$ and a nonnegative
measurable function $f$ on $X$, the probability that the sequence of ergodic
averages $$ \frac 1 {(2k+1)^d} \sum\limits_{g \in [-k,\dots,k]^d} f(g \cdot x)
$$ has at least $n$ fluctuations across an interval $(\alpha,\beta)$ can be
bounded from above by $c_1 c_2^n$ for some universal constants $c_1 \in
\mathbb{R}$ and $c_2 \in (0,1)$, which depend only on $d,\alpha,\beta$. The
purpose of this article is to generalize this result to measure-preserving
actions of groups of polynomial growth. As the main tool we develop a
generalization of effective Vitali covering theorem for groups of polynomial
growth.


title: Not-Post-Peierls compatibility under noisy channels

abstract:
  The Pusey-Barrett-Rudolph (PBR) theorem deals with the realism of the quantum
states. It establishes that every pure quantum state is real, in the context of
quantum ontological models. Specifically, by guaranteeing the property of
not-Post-Peierls ($\neg$PP) compatibility (or antidistinguishability) for a
particular set of states $P$, together with the ad hoc postulate known as
Preparation Independence Postulate (PIP), the theorem establishes that these
two properties imply the $\psi$-onticity (realism) of the set of all pure
states. This PBR result has triggered two particular lines of research: On the
one hand, it has been possible to derive similar results without the use of the
PIP, although at the expense of implying weaker properties than
$\psi$-onticity. On the other hand, it has also been proven that the property
of $\neg$PP compatibility alone is an explicit witness of usefulness for the
task known as conclusive exclusion of states. In this work, we explore the
$\neg$PP compatibility of the set of states $P$, when $P$ is under the
interaction of some noisy channels, which would consequently let us identify
some noisy scenarios where it is still possible to perform the task of
conclusive exclusion of states. Specifically, we consider the set $P$ of
$n$-qubit states in interaction with an environment by means of i) individual
and ii) collective couplings. In both cases, we analytically show that the
phenomenon of achieving $\neg$PP compatibility, although reduced, it is still
present. Searching for an optimisation of this phenomenon, we report numerical
experiments up to $n=4$ qubits.


title: Geometric estimates from spanning surfaces

abstract:
  We derive bounds on the length of the meridian and the cusp volume of
hyperbolic knots in terms of the topology of essential surfaces spanned by the
knot. We provide an algorithmically checkable criterion that guarantees that
the meridian length of a hyperbolic knot is below a given bound. As
applications we find knot diagrammatic upper bounds on the meridian length and
the cusp volume of hyperbolic adequate knots and we obtain new large families
of knots with meridian lengths bounded above by four. We also discuss
applications of our results to Dehn surgery.


title: Decoupling limit and throat geometry of non-susy D3 brane

abstract:
  In a previous work, we have shown that, like BPS Dp branes, bulk gravity gets
decoupled from the brane even for the non-susy Dp branes of type II string
theories indicating a possible extension of AdS/CFT correspondence for the
non-supersymmetric case. In that work, the decoupling of gravity on the
non-susy Dp branes has been shown numerically for the general case as well as
analytically for some special case. Here we discuss the decoupling limit and
the throat geometry of the non-susy D3 brane when the charge associated with
the brane is very large. We show that in the decoupling limit the throat
geometry of the non-susy D3 brane, under appropriate coordinate change, reduces
to the Constable-Myers solution and thus confirming that this solution is
indeed the holographic dual of a (non-gravitational) gauge theory discussed
there. We also show that when one of the parameters of the solution takes a
specific value, it reduces, under another coordinate change, to the
five-dimensional solution obtained by Csaki and Reece, again confirming its
gauge theory interpretation.


title: Impact of Nucleon-Nucleon Bremsstrahlung Rates Beyond One-Pion Exchange

abstract:
  Neutrino-pair production and annihilation through nucleon-nucleon
bremsstrahlung is included in current supernova simulations by rates that are
based on the one-pion-exchange approximation. Here we explore the consequences
of bremsstrahlung rates based on a modern nuclear interactions for
proto-neutron star cooling and the corresponding neutrino emission. We find
that despite a reduction of the bremsstrahlung emission by a factor of 2-5 in
the neutrinospheric region, models with the improved treatment exhibit only
$\lesssim$5% changes of the neutrino luminosities and an increase of
$\lesssim$0.7 MeV of the average energies of the radiated neutrino spectra,
with the largest effects for the antineutrinos of all flavors and at late
times. Overall, the proto-neutron star cooling evolution is slowed down
modestly by $\lesssim$0.5-1 s.


title: Electoral Stability and Rigidity

abstract:
  Some argue that political stability is best served through a two-party
system. This study refutes this. The author mathematically defines the
stability and rigidity of electoral systems comprised of any quantity of
electors and parties. In fact, stability is a function of the quantity of
electors - i.e., the number of occupied seats at the table. As the number of
electors increases, the properties of an electorate are increasingly well
resolved, and well described by those of an electorate that is least excessive
-- that is to say an electorate that is closest to equilibrium. Further,
electoral rigidity is a function of the quantity of parties and their
probabilities of representation. An absolutely rigid system admits no
fluctuations -- whatever happens to one elector will happen to all electors. As
the quantity of parties increases so does the number of party lines, and with
it the quantity of alternatives with which to respond to an external stimulus.
Rigidity is significant in a social system that places high value on party
loyalty. In conclusion, (i) electoral stability is best served by increasing
the quantity of electors; (ii) electoral rigidity is best served by decreasing
the quantity of parties, and by increasing the representation of some parties
at the expense of others; and (iii) the less stable a branch of government, the
more concern is placed on those who would hold those offices for the people.


title: Bounds for the number of points on curves over finite fields

abstract:
  Let $\mathcal{X}$ be a projective irreducible nonsingular algebraic curve
defined over a finite field $\mathbb{F}_q$. This paper presents a variation of
the St\"orh-Voloch theory and sets new bounds to the number of
$\mathbb{F}_{q^r}$-rational points on $\mathcal{X}$. In certain cases, where
comparison is possible, the results are shown to improve other bounds such as
Weil's, St\"orh-Voloch's and Ihara's.


title:
Hyperelastic bodies under homogeneous Cauchy stress induced by
  non-homogeneous finite deformations

abstract:
  We discuss whether homogeneous Cauchy stress implies homogeneous strain in
isotropic nonlinear elasticity. While for linear elasticity the positive answer
is clear, we exhibit, through detailed calculations, an example with
inhomogeneous continuous deformation but constant Cauchy stress. The example is
derived from a non rank-one convex elastic energy.


title:
Modelling duality between bound and resonant meson spectra by means of
  free quantum motions on the de Sitter space time dS4

abstract:
  We seek for a pair of a well and barrier potentials such that the real parts
of the complex energies of the resonances transmitted through the barrier equal
the energies of the states bound within the well and find the hyperbolic
Poeschl-Teller barrier, ~sech^2\rho, and the trigonometric Scarf well, ~
\sec^2\chi. The potentials are shown to be conformally symmetric by the aid of
the de Sitter space time, dS4, related to flat conformal space time by a
conformal map. Namely, we transform the quantum mechanical wave equations with
the above potentials to free quantum motions on the respective open time like
hyperbolic and the closed space like hyper spherical, S3, geodesics of dS4, the
former by itself is related to Minkowski space time by a conformal map.We
formulate a conformal symmetry respecting classification scheme for mesons seen
either as resonances in scattering, or as states bound within a potential,
according to trajectories in which the total spin of the meson, l-depends
linearly on the first power of the invariant mass, M, and not as in the
canonical Regge formalism on the squared mass.We analyze 71 reported mesons in
this scheme and in finding good agreement with data predict the masses of 12
missing mesons. We observe that on S3 the color quantum number of mesons is
limited to neutral. To the amount physics is independent of the choice of the
set of coordinates, this property remains valid in the flat geometry too. We
conclude on the usefulness of conformal maps of flat to curved space times as
tools for modelling and interpreting the color neutrality of hadrons required
by the confinement phenomenon and on the relevance of trigonometric and
hyperbolic potentials for constituent quark models. Finally, all involved
potentials have been motivated by Wilson loops with cusps.


title: Rules of Three for commutation relations

abstract:
  We investigate the following surprisingly widespread phenomenon which we call
The Rule of Three: in order for a particular kind of commutation relation to
hold for subsequences of elements of a ring labeled by any subset of indices,
it is enough that these relations hold for subsets of size one, two, and three.


title: On semiring complexity of Schur polynomials

abstract:
  Semiring complexity is the version of arithmetic circuit complexity that
allows only two operations: addition and multiplication. We show that when the
number of variables is fixed, the semiring complexity of a Schur polynomial
$s_\lambda$ is $O(log(\lambda_1))$; here $\lambda_1$ is the largest part of the
partition $\lambda$.


title:
Simulation of an Optional Strategy in the Prisoner's Dilemma in Spatial
  and Non-spatial Environments

abstract:
  This paper presents research comparing the effects of different environments
on the outcome of an extended Prisoner's Dilemma, in which agents have the
option to abstain from playing the game. We consider three different pure
strategies: cooperation, defection and abstinence. We adopt an evolutionary
game theoretic approach and consider two different environments: the first
which imposes no spatial constraints and the second in which agents are placed
on a lattice grid. We analyse the performance of the three strategies as we
vary the loner's payoff in both structured and unstructured environments.
Furthermore we also present the results of simulations which identify scenarios
in which cooperative clusters of agents emerge and persist in both
environments.


title: Large Angle based Skeleton Extraction for 3D Animation

abstract:
  In this paper, we present a solution for arbitrary 3D character deformation
by investigating rotation angle of decomposition and preserving the mesh
topology structure. In computer graphics, skeleton extraction and
skeleton-driven animation is an active areas and gains increasing interests
from researchers. The accuracy is critical for realistic animation and related
applications. There have been extensive studies on skeleton based 3D
deformation. However for the scenarios of large angle rotation of different
body parts, it has been relatively less addressed by the state-of-the-art,
which often yield unsatisfactory results. Besides 3D animation problems, we
also notice for many 3D skeleton detection or tracking applications from a
video or depth streams, large angle rotation is also a critical factor in the
regression accuracy and robustness. We introduced a distortion metric function
to quantify the surface curviness before and after deformation, which is a
major clue for large angle rotation detection. The intensive experimental
results show that our method is suitable for 3D modeling, animation, skeleton
based tracking applications.


title: Practical optimal experiment design with probabilistic programs

abstract:
  Scientists often run experiments to distinguish competing theories. This
requires patience, rigor, and ingenuity - there is often a large space of
possible experiments one could run. But we need not comb this space by hand -
if we represent our theories as formal models and explicitly declare the space
of experiments, we can automate the search for good experiments, looking for
those with high expected information gain. Here, we present a general and
principled approach to experiment design based on probabilistic programming
languages (PPLs). PPLs offer a clean separation between declaring problems and
solving them, which means that the scientist can automate experiment design by
simply declaring her model and experiment spaces in the PPL without having to
worry about the details of calculating information gain. We demonstrate our
system in two case studies drawn from cognitive psychology, where we use it to
design optimal experiments in the domains of sequence prediction and
categorization. We find strong empirical validation that our automatically
designed experiments were indeed optimal. We conclude by discussing a number of
interesting questions for future research.


title:
Sympathetic ground state cooling and time-dilation shifts in an
  $^{27}\text{Al}^+$ optical clock

abstract:
  We report on Raman sideband cooling of ${^{25}\text{Mg}^+}$ to
sympathetically cool the secular modes of motion in a
$^{25}\text{Mg}^+$-$^{27}\!\text{Al}^+$ two-ion pair to near the
three-dimensional (3D) ground state. The evolution of the Fock-state
distribution during the cooling process is studied using a rate-equation
simulation, and various heating sources that limit the efficiency of 3D
sideband cooling in our system are discussed. We characterize the residual
energy and heating rates of all of the secular modes of motion and estimate a
secular motion time-dilation shift of ${-(1.9 \pm 0.1)\times 10^{-18}}$ for an
${^{27}\text{Al}^+}$ clock at a typical clock probe duration of $150$ ms. This
is a 50-fold reduction in the secular motion time-dilation shift uncertainty in
comparison with previous ${^{27}\text{Al}^+}$ clocks.


title: A dynamical $\alpha$-cluster model of $^{16}$O

abstract:
  We calculate the low-lying spectrum of the $^{16}$O nucleus using an
$\alpha$-cluster model which includes the important tetrahedral and square
configurations. Our approach is motivated by the dynamics of $\alpha$-particle
scattering in the Skyrme model. We are able to replicate the large energy
splitting that is observed between states of identical spin but opposite
parities, as well as introduce states that were previously not found in other
cluster models, such as a $0^-$ state. We also provide a novel interpretation
of the first excited state of $^{16}$O and make predictions for the energies of
$6^-$ states that have yet to be observed experimentally.


title:
The driven Dicke Model: time-dependent mean field and quantum
  fluctuations in a non-equilibrium quantum many-body system

abstract:
  We establish a new theoretical framework, based on a time-dependent mean
field approach, to address the dynamics of the driven Dicke model. The joint
evolution of both mean fields and quantum fluctuations gives rise to a rich and
generally non-linear dynamics, featuring a normal (stable) regime and an
unstable, super-radiant one. Various dynamical phenomena emerge, such as the
spontaneous amplification of vacuum fluctuations, or the appearance of special
points around which the mean-field amplitudes rotate during driven time
evolution, signalling a dynamical symmetry breaking. We also provide a
characterization of the driving-induced photon production in terms of the work
done by the driving agent, of the non-adiabaticity of the process and of the
entanglement generated between the atomic system and the cavity mode.


title: Refined Heinz-Kato-L\"owner inequalities

abstract:
  A version of the Cauchy-Schwarz inequality in operator theory is the
following: for any two symmetric, positive definite matrices $A,B \in
\mathbb{R}^{n \times n}$ and arbitrary $X \in \mathbb{R}^{n \times n}$ $$
\|AXB\| \leq \|A^2 X\|^{\frac{1}{2}} \|X B^2\|^{\frac{1}{2}}.$$ This inequality
is classical and equivalent to the celebrated Heinz-L\"owner, Heinz-Kato and
Cordes inequalities. We characterize cases of equality: in particular, after
factoring out the symmetry coming from multiplication with scalars $ \|A^2 X\|
= 1 = \|X B^2\|$, the case of equality requires that $A$ and $B$ have a common
eigenvalue $\lambda_i = \mu_j$. We also derive improved estimates and show that
if either $\lambda_i \lambda_j = \mu_k^2$ or $\lambda_i^2 = \mu_j \mu_k$ does
not have a solution, i.e. if $d > 0$ where \begin{align*} d &= \min_{1 \leq
i,j,k \leq n} \{ | \log{ \lambda_i} + \log{ \lambda_j} - 2\log{
\mu_k}|:\lambda_i, \lambda_j \in \sigma(A), \mu_k \in \sigma(B) \} &+\min_{1
\leq i,j,k \leq n}\{ | 2\log{\lambda_i} - \log{ \mu_j} - \log{\mu_k }
|:\lambda_i \in \sigma(A), \mu_j, \mu_k \in \sigma(B) \}, \end{align*} then
there is an improved inequality $$ \|AXB\| \leq (1 - c_{n,d})\|A^2
X\|^{\frac{1}{2}} \|X B^2\|^{\frac{1}{2}}$$ for some $c_{n,d} > 0$ that only
depends only on $n$ and $d$. We obtain similar results for the McIntosh
inequality and the Cordes inequality and expect the method to have many further
applications.


title: Universal Zero Conductivity Condition for Optical Absorption

abstract:
  Harnessing information and energy from light within a nanoscale mode volume
is a fundamental challenge for nanophotonic applications ranging from solar
photovoltaics to single photon detectors. Here, we show the existence of a
universal condition in materials that sheds light on fundamental limits of
electromagnetic to matter energy conversion (transduction). We show that the
upper limit of absorption rate (transduction rate) in any nanoscale absorber
converting light to matter degrees of freedom is revealed by the zero of
optical conductivity at complex frequencies ($\sigma(\omega^\prime +
i\omega^{\prime\prime})= 0$). We trace the origin of this universal zero
conductivity condition to causality requirements on any passive linear response
function and propose an experiment of absorption resonances using plasmonic
nanoparticles to experimentally verify this universal zero conductivity
condition. Our work is widely applicable to linear systems across the
electromagnetic spectrum and allows for systematic optimization of optical
absorption in single photon detectors, solar cells, Coherent Perfect Absorbers
and SPASERS.


title: Hidden symmetries of black holes in five-dimensional supergravity

abstract:
  We consider a general charged, rotating black hole in five-dimensional STU
supergravity, and show that its six-dimensional Kaluza-Klein lift admits a
Killing-Yano 3-form with torsion. This underlies its known Killing tensors in
five dimensions, and is related to the separability of torsion-modified Dirac
equations. In the generalization to gauged supergravity, we present a
five-dimensional Killing-Yano 3-form with torsion when two of the gauge fields
are equal, and a Killing-Stackel tensor in the general 3-charge Wu solution.


title: A proposal for a minimal surface code experiment

abstract:
  Current quantum technology is approaching the system sizes and fidelities
required for quantum error correction. It is therefore important to determine
exactly what is needed for proof-of-principle experiments, which will be the
first major step towards fault-tolerant quantum computation. Here we propose a
surface code based experiment that is the smallest, both in terms of code size
and circuit depth, that would allow errors to be detected and corrected for
both the $X$ and $Z$ basis of a qubit. This requires $17$ physical qubits
initially prepared in a product state, on which $16$ two-qubit entangling gates
are applied before a final measurement of all qubits. A platform agnostic error
model is applied to give some idea of the noise levels required for success. It
is found that a true demonstration of quantum error correction will require
fidelities for the preparation and measurement of qubits and the entangling
gates to be above $99\%$.


title:
MT3S: Mobile Turkish Scene Text-to-Speech System for the Visually
  Impaired

abstract:
  Reading text is one of the essential needs of the visually impaired people.
We developed a mobile system that can read Turkish scene and book text, using a
fast gradient-based multi-scale text detection algorithm for real-time
operation and Tesseract OCR engine for character recognition. We evaluated the
OCR accuracy and running time of our system on a new, publicly available mobile
Turkish scene text dataset we constructed and also compared with
state-of-the-art systems. Our system proved to be much faster, able to run on a
mobile device, with OCR accuracy comparable to the state-of-the-art.


title: The Advanced LIGO Photon Calibrators

abstract:
  The two interferometers of the Laser Interferometry Gravitaional-wave
Observatory (LIGO) recently detected gravitational waves from the mergers of
binary black hole systems. Accurate calibration of the output of these
detectors was crucial for the observation of these events, and the extraction
of parameters of the sources. The principal tools used to calibrate the
responses of the second-generation (Advanced) LIGO detectors to gravitational
waves are systems based on radiation pressure and referred to as Photon
Calibrators. These systems, which were completely redesigned for Advanced LIGO,
include several significant upgrades that enable them to meet the calibration
requirements of second-generation gravitational wave detectors in the new era
of gravitational-wave astronomy. We report on the design, implementation, and
operation of these Advanced LIGO Photon Calibrators that are currently
providing fiducial displacements on the order of $10^{-18}$
m/$\sqrt{\textrm{Hz}}$ with accuracy and precision of better than 1 %.


title: On the reconstruction problem for Pascal lines

abstract:
  Given a sextuple of distinct points $A, B, C, D, E, F$ on a conic, arranged
into an array $\left[\begin{array}{ccc} A & B & C F & E & D
\end{array}\right]$, Pascal's theorem says that the points $AE \cap BF, BD \cap
CE, AD \cap CF$ are collinear. The line containing them is called the Pascal of
the array, and one gets altogether sixty such lines by permuting the points. In
this paper we prove that the initial sextuple can be explicitly reconstructed
from four specifically chosen Pascals. The reconstruction formulae are encoded
by some transvectant identities which are proved using the graphical calculus
for binary forms.


title: Transport in vertically stacked hetero-structures from 2D materials

abstract:
  In this work, the transport of tunnel field-effect transistor (TFET) based on
vertically stacked hereto-structures from 2D transition metal dichalcogenide
(TMD) materials is investigated by atomistic quantum transport simulations.
WTe2-MoS2 combination was chosen due to the formation of a broken gap
hetero-junction which is desirable for TFETs. There are two assumptions behind
the MoS2-WTe2 hetero-junction tight binding (TB) model: 1) lattice registry. 2)
The $S-Te$ parameters being the average of the $S-S$ and $Te-Te$ parameters of
bilayer MoS2 and WTe2. The computed TB bandstructure of the hetero-junction
agrees well with the bandstructure obtained from density functional theory
(DFT) in the energy range of interest for transport. NEGF (Non-Equilibrium
Green$'$s Function) equations within the tight binding description is then
utilized for device transfer characteristic calculation. Results show 1) energy
filtering is the switching mechanism; 2) the length of the extension region is
critical for device to turn off; 3) MoS2-WTe2 interlayer TFET can achieve a
large on-current of $1000 \mu A/\mu m$ with $V_{DD} = 0.3V$, which suggests
interlayer TFET can solve the low ON current problem of TFETs and can be a
promising candidate for low power applications.


title:
Globally Homogenous Mixture Components and Local Heterogeneity of Rank
  Data

abstract:
  The traditional methods of finding mixture components of rank data are mostly
based on distance and latent class models; these models may exhibit the
phenomenon of masking of groups of small sizes; probably due to the spherical
nature of rank data. Our approach diverges from the traditional methods; it is
directional and uses a logical principle, the law of contradiction. We discuss
the concept of a mixture for rank data essentially in terms of the notion of
global homogeneity of its group components. Local heterogeneities may appear
once the group components of the mixture have been discovered. This is done via
the exploratory analysis of rank data by taxicab correspondence analysis with
the nega coding: If the first factor is an affine function of the Borda count,
then we say that the rank data are globally homogenous, and local
heterogeneities may appear on the consequent factors; otherwise, the rank data
either are globally homogenous with outliers, or a mixture of globally
homogenous groups. Also we introduce a new coefficient of global homogeneity,
GHC. GHC is based on the first taxicab dispersion measure: it takes values
between 0 and 100\%, so it is easily interpretable. GHC measures the extent of
crossing of scores of voters between two or three blocks seriation of the items
where the Borda count statistic provides consensus ordering of the items on the
first axis. Examples are provided. Key words: Preferences; rankings; Borda
count; global homogeneity coefficient; nega coding; law of contradiction;
mixture; outliers; taxicab correspondence analysis; masking.


title:
Quantum-critical spin dynamics in a Tomonaga-Luttinger liquid studied
  with muon-spin relaxation

abstract:
  We demonstrate that quantum-critical spin dynamics can be probed in high
magnetic fields using muon-spin relaxation ($\mu^{+}$SR). Our model system is
the strong-leg spin ladder bis(2,3-dimethylpyridinium) tetrabromocuprate
(DIMPY). In the gapless Tomonaga-Luttinger liquid phase we observe
finite-temperature scaling of the $\mu^{+}$SR $1/T_1$ relaxation rate which
allows us to determine the Luttinger parameter $K$. We discuss the benefits and
limitations of local probes compared with inelastic neutron scattering.


title:
General Semi-Markov Model for Limit Order Books: Theory, Implementation
  and Numerics

abstract:
  The paper considers a general semi-Markov model for Limit Order Books with
two states, which incorporates price changes that are not fixed to one tick.
Furthermore, we introduce an even more general case of the semi-Markov model
for LimitOrder Books that incorporates an arbitrary number of states for the
price changes. For both cases the justifications, diffusion limits,
implementations and numerical results are presented for different Limit Order
Book data: Apple, Amazon, Google, Microsoft, Intel on 2012/06/21 and Cisco,
Facebook, Intel, Liberty Global, Liberty Interactive, Microsoft, Vodafone from
2014/11/03 to 2014/11/07.


title:
Observation of parity-time symmetry breaking transitions in a
  dissipative Floquet system of ultracold atoms

abstract:
  Open physical systems with balanced loss and gain, described by non-Hermitian
parity-time ($\mathcal{PT}$) reflection symmetric Hamiltonians, exhibit a
transition which could engenders modes that exponentially decay or grow with
time and thus spontaneously breaks the $\mathcal{PT}$-symmetry. Such
$\mathcal{PT}$-symmetry breaking transitions have attracted many interests
because of their extraordinary behaviors and functionalities absent in closed
systems. Here we report on the observation of $\mathcal{PT}$-symmetry breaking
transitions by engineering time-periodic dissipation and coupling, which are
realized through state-dependent atom loss in an optical dipole trap of
ultracold $^6$Li atoms. Comparing with a single transition appearing for static
dissipation, the time-periodic counterpart undergoes $\mathcal{PT}$-symmetry
breaking and restoring transitions at vanishingly small dissipation strength in
both single and multiphoton transition domains, revealing rich phase structures
associated to a Floquet open system. The results enable ultracold atoms to be a
versatile tool for studying $\mathcal{PT}$-symmetric quantum systems.


title: Spin Correlations in the Dipolar Pyrochlore Antiferromagnet Gd2Sn2O7

abstract:
  We investigate spin correlations in the dipolar Heisenberg antiferromagnet
Gd2Sn2O7 using polarised neutron-scattering measurements in the correlated
paramagnetic regime. Using Monte Carlo methods, we show that our data are
sensitive to weak further-neighbour exchange interactions of magnitude ~0.5% of
the nearest-neighbour interaction, and are compatible with either
antiferromagnetic next-nearest neighbour interactions, or ferromagnetic
third-neighbour interactions that connect spins across hexagonal loops.
Calculations of the magnetic scattering intensity reveal rods of diffuse
scattering along [111] reciprocal-space directions, which we explain in terms
of strong antiferromagnetic correlations parallel to the set of <110>
directions that connect a given spin with its nearest neighbours. Finally, we
demonstrate that the spin correlations in Gd2Sn2O7 are highly anisotropic, and
correlations parallel to third-neighbour separations are particularly sensitive
to critical fluctuations associated with incipient long-range order.


title:
Kinematics of the jet in M87 on scales of 100 -- 1000 Schwarzschild
  radii

abstract:
  Very long baseline interferometry (VLBI) imaging of radio emission from
extragalactic jets provides a unique probe of physical mechanisms governing the
launching, acceleration, and collimation of relativistic outflows. The
two-dimensional structure and kinematics of the jet in M\,87 (NGC\,4486) have
been studied by applying the Wavelet-based Image Segmentation and Evaluation
(WISE) method to 11 images obtained from multi-epoch Very Long Baseline Array
(VLBA) observations made in January-August 2007 at 43 GHz ($\lambda = 7$ mm).
The WISE analysis recovers a detailed two-dimensional velocity field in the jet
in M\,87 at sub-parsec scales. The observed evolution of the flow velocity with
distance from the jet base can be explained in the framework of MHD jet
acceleration and Poynting flux conversion. A linear acceleration regime is
observed up to $z_{obs} \sim 2$\,mas. The acceleration is reduced at larger
scales, which is consistent with saturation of Poynting flux conversion.
Stacked cross correlation analysis of the images reveals a pronounced
stratification of the flow. The flow consists of a slow, mildly relativistic
layer (moving at $\beta \sim 0.5\,c$), associated either with instability
pattern speed or an outer wind, and a fast, accelerating stream line (with
$\beta \sim 0.92$, corresponding to a bulk Lorentz factor $\gamma \sim 2.5$). A
systematic difference of the apparent speeds in the northern and southern limbs
of the jet is detected, providing evidence for jet rotation. The angular
velocity of the magnetic field line associated with this rotation suggests that
the jet in M87 is launched in the inner part of the disk, at a distance $r_0
\sim 5\, R_\mathrm{s}$ from the central engine. The combined results of the
analysis imply that MHD acceleration and conversion of Poynting flux to kinetic
energy play the dominant roles in collimation and acceleration of the flow in
M\,87.


title: Tractable Structure Learning in Radial Physical Flow Networks

abstract:
  Physical Flow Networks are different infrastructure networks that allow the
flow of physical commodities through edges between its constituent nodes. These
include power grid, natural gas transmission network, water pipelines etc. In
such networks, the flow on each edge is characterized by a function of the
nodal potentials on either side of the edge. Further the net flow in and out of
each node is conserved. Learning the structure and state of physical networks
is necessary for optimal control as well as to quantify its privacy needs. We
consider radial flow networks and study the problem of learning the operational
network from a loopy graph of candidate edges using statistics of nodal
potentials. Based on the monotonic properties of the flow functions, the key
result in this paper shows that if variance of the difference of nodal
potentials is used to weight candidate edges, the operational edges form the
minimum spanning tree in the loopy graph. Under realistic conditions on the
statistics of nodal injection (consumption or production), we provide a greedy
structure learning algorithm with quasilinear computational complexity in the
number of candidate edges in the network. Our learning framework is very
general due to two significant attributes. First it is independent of the
specific marginal distributions of nodal potentials and only uses order
properties in their second moments. Second, the learning algorithm is agnostic
to exact flow functions that relate edge flows to corresponding potential
differences and is applicable for a broad class of networks with monotonic flow
functions. We demonstrate the efficacy of our work through realistic
simulations on diverse physical flow networks and discuss possible extensions
of our work to other regimes.


title: The uniform Martin's conjecture for many-one degrees

abstract:
  We study functions from reals to reals which are uniformly degree-invariant
from Turing-equivalence to many-one equivalence, and compare them "on a cone."
We prove that they are in one-to-one correspondence with the Wadge degrees,
which can be viewed as a refinement of the uniform Martin's conjecture for
uniformly invariant functions from Turing- to Turing-equivalence. Our proof
works in the general case of many-one degrees on $\mathcal{Q}^\omega$ and Wadge
degrees of functions $\omega^\omega\to\mathcal{Q}$ for any better quasi
ordering $\mathcal{Q}$.