title:
A Novel Data-Driven Situation Awareness Approach for Future Grids--Using
  Large Random Matrices for Big Data Modeling

abstract:
  Data-driven approaches, when tasked with situation awareness, are suitable
for complex grids with massive datasets. It is a challenge, however, to
efficiently turn these massive datasets into useful big data analytics. To
address such a challenge, this paper, based on random matrix theory (RMT),
proposes a datadriven approach. The approach models massive datasets as large
random matrices; it is model-free and requiring no knowledge about physical
model parameters. In particular, the large data dimension N and the large time
span T, from the spatial aspect and the temporal aspect respectively, lead to
favorable results. The beautiful thing lies in that these linear eigenvalue
statistics (LESs) built from data matrices follow Gaussian distributions for
very general conditions, due to the latest breakthroughs in probability on the
central limit theorems of those LESs. Numerous case studies, with both
simulated data and field data, are given to validate the proposed new
algorithms.


title:
Probing Nuclear Effects at the T2K Near Detector Using Single-Transverse
  Kinematic Imbalance

abstract:
  In order to make precision measurements of neutrino oscillations using
few-GeV neutrino beams a detailed understanding of nuclear effects in neutrino
scattering is essential. Recent studies have revealed that single-transverse
kinematic imbalance (STKI), defined in the plane transverse to an incoming
neutrino beam, can act as a unique probe of these nuclear effects. This work
first illustrates that an exclusive measurement of STKI at the off-axis near
detector of the T2K experiment (ND280) is expected distinguish the presence of
interactions with two nucleons producing two holes (2p-2h) from alterations of
the predominant underlying cross-section parameter ($M_A$ - the nucleon axial
mass). Such a measurement is then demonstrated with fake data, showing
substantial nuclear model separation potential.


title: Entanglement distribution and quantum discord

abstract:
  Establishing entanglement between distant parties is one of the most
important problems of quantum technology, since long-distance entanglement is
an essential part of such fundamental tasks as quantum cryptography or quantum
teleportation. In this lecture we review basic properties of entanglement and
quantum discord, and discuss recent results on entanglement distribution and
the role of quantum discord therein. We also review entanglement distribution
with separable states, and discuss important problems which still remain open.
One such open problem is a possible advantage of indirect entanglement
distribution, when compared to direct distribution protocols.


title:
Molten o-H3PO4 - A New Electrolyte for the Anodic Synthesis of
  Self-Organized Oxide Structures: WO3 Nanochannel Layers and Others

abstract:
  We introduce the use of pure molten ortho-phosphoric acid (o-H3PO4) as an
electrolyte for selforganizing electrochemistry. This electrolyte allows for
the formation of self-organized oxide architectures (one-dimensional nanotubes,
nanochannels, nanopores) on metals such as tungsten that up to now were
regarded as very difficult to grow self-ordered anodic oxide structures. In
this work, we show particularly the fabrication of thick, vertically aligned
tungsten oxide nanochannel layers, with pore diameter of ca. 10 nm, and
illustrate their potential use in some typical applications.


title:
Non-Hermitian matter wave mixing in Bose Einstein condensates:
  dissipation induced amplification

abstract:
  We investigate the nonlinear scattering dynamics in interacting atomic
Bose-Einstein condensates under non-Hermitian dissipative conditions. We show
that by carefully engineering a momentum-dependent atomic loss profile one can
achieve matter-wave amplification through four wave mixing in a one-dimensional
quasi free-space setup - a process that is forbidden in the counterpart
Hermitian systems due to energy mismatch. Additionally, we show that similar
effects lead to rich nonlinear dynamics in higher dimensions. Finally, we
propose a physical realization for selectively tailoring the momentum-dependent
atomic dissipation. Our strategy is based on a two step process: (i) exciting
atoms to narrow Rydberg- or metastable excited states, and (ii) introducing
loss through recoil; all while leaving the bulk condensate intact due to
protection by quantum interference.


title: Outer automorphisms of classical algebraic groups

abstract:
  The so-called Tits class, associated to an adjoint absolutely almost simple
algebraic group, provides a cohomological obstruction for this group to admit
an outer automorphism. If the group has inner type, this obstruction is the
only one. In this paper, we prove this is not the case for classical groups of
outer type, except for groups of type $^2\mathsf{A}_n$ with $n$ even, or $n=5$.
More precisely, we prove a descent theorem for exponent $2$ and degree $6$
algebras with unitary involution, which shows that their automorphism groups
have outer automorphisms. In all other relevant classical types, namely
$^2\mathsf{A}_n$ with $n$ odd, $n\geq3$ and $^2\mathsf{D}_n$, we provide
explicit examples where the Tits class obstruction vanishes, and yet the group
does not have outer automorphism. As a crucial tool, we use "generic" sums of
algebras with involution.


title: Weighted dependency graphs and the Ising model

abstract:
  Weighted dependency graphs have been recently introduced by the second
author, as a toolbox to prove central limit theorems. In this paper, we prove
that spins in the $d$-dimensional Ising model display such a weighted
dependency structure. We use this to obtain various central limit theorems for
the number of occurrences of local and global patterns in a growing box.


title: Efficient Metric Learning for the Analysis of Motion Data

abstract:
  We investigate metric learning in the context of dynamic time warping (DTW),
the by far most popular dissimilarity measure used for the comparison and
analysis of motion capture data. While metric learning enables a
problem-adapted representation of data, the majority of methods has been
proposed for vectorial data only. In this contribution, we extend the popular
principle offered by the large margin nearest neighbors learner (LMNN) to DTW
by treating the resulting component-wise dissimilarity values as features. We
demonstrate that this principle greatly enhances the classification accuracy in
several benchmarks. Further, we show that recent auxiliary concepts such as
metric regularization can be transferred from the vectorial case to
component-wise DTW in a similar way. We illustrate that metric regularization
constitutes a crucial prerequisite for the interpretation of the resulting
relevance profiles.


title:
Exact results for power spectrum and susceptibility of a leaky
  integrate-and-fire neuron with two-state noise

abstract:
  The response properties of excitable systems driven by colored noise are of
great interest, but are usually mathematically only accessible via
approximations. For this reason, dichotomous noise, a rare example of a colored
noise leading often to analytically tractable problems, has been extensively
used in the study of stochastic systems. Here, we calculate exact expressions
for the power spectrum and the susceptibility of a leaky integrate-and-fire
neuron driven by asymmetric dichotomous noise. While our results are in
excellent agreement with simulations, they also highlight a limitation of using
dichotomous noise as a simple model for more complex fluctuations: Both power
spectrum and susceptibility exhibit an undamped periodic structure, the origin
of which we discuss in detail.


title:
Optimal response to non-equilibrium disturbances under truncated
  Burgers-Hopf dynamics

abstract:
  We model and compute the average response of truncated Burgers-Hopf dynamics
to finite perturbations away from the Gibbs equipartition energy spectrum using
a dynamical optimization framework recently conceptualized in a series of
papers. Non-equilibrium averages are there approximated in terms of geodesic
paths in probability space that best-fit the Liouvillean dynamics over a family
of quasi-equilibrium trial densities. By recasting the geodesic principle as an
optimal control problem, we solve numerically for the non-equilibrium responses
using an augmented Lagrangian, non-linear conjugate gradient descent method.
For moderate perturbations, we find an excellent agreement between the optimal
predictions and the direct numerical simulations of the truncated Burgers-Hopf
dynamics. In this near-equilibrium regime, we argue that the optimal response
theory provides an approximate yet predictive counterpart to
fluctuation-dissipation identities.


title:
Double-parton scattering effects in double charm production within gluon
  fragmentation scenario

abstract:
  We discuss charm $D^0 D^0$ meson-meson pair production in the forward
rapidity region related to the LHCb experimental studies at $\sqrt{s}$ = 7 TeV.
We consider double-parton scattering mechanisms of double $c \bar c$ production
and subsequent standard $cc \to D^{0}D^{0}$ scale-independent hadronization as
well as new double $g$ and mixed $g c\bar c $ production mechanisms with $gg
\to D^{0}D^{0}$ and $gc \to D^{0}D^{0}$ scale-dependent hadronization. The new
scenario with gluon fragmentation components results also in a new
single-parton scattering mechanism of $gg$ production which is also taken here
into account. Results of the numerical calculations are compared with the LHCb
data for several correlation observables. The new mechanisms lead to a larger
cross sections and to slightly different shapes of the calculated correlation
observables.


title:
Distribution questions for trace functions with values in cyclotomic
  integers and their reductions

abstract:
  We consider $\ell$-adic trace functions over finite fields taking values in
cyclotomic integers, such as characters and exponential sums. Through ideas of
Deligne and Katz, we explore probabilistic properties of the reductions modulo
a prime ideal, exploiting especially the determination of their integral
monodromy groups. In particular, this gives a generalization of a result of
Lamzouri-Zaharescu on the distribution of short sums of the Legendre symbol
reduced modulo an integer to all multiplicative characters and to
hyper-Kloosterman sums.


title:
Search for triboson $W^{\pm}W^{\pm}W^{\mp}$ production in $pp$
  collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

abstract:
  This paper reports a search for triboson $W^{\pm}W^{\pm}W^{\mp}$ production
in two decay channels ($W^{\pm}W^{\pm}W^{\mp}\rightarrow
\ell^{\pm}\nu\ell^{\pm}\nu\ell^{\mp}\nu$ and $W^{\pm}W^{\pm}W^{\mp}\rightarrow
\ell^{\pm}\nu\ell^{\pm}\nu{}jj$ with $\ell=e, \mu$) in proton-proton collision
data corresponding to an integrated luminosity of 20.3 fb$^{-1}$ at a
centre-of-mass energy of 8 TeV with the ATLAS detector at the Large Hadron
Collider. Events with exactly three charged leptons, or two leptons with the
same electric charge in association with two jets, are selected. The total
number of events observed in data is consistent with the Standard Model (SM)
predictions. The observed 95 % confidence level upper limit on the SM
$W^{\pm}W^{\pm}W^{\mp}$ production cross section is found to be 730 fb with an
expected limit of 560 fb in the absence of SM $W^{\pm}W^{\pm}W^{\mp}$
production. Limits are also set on $WWWW$ anomalous quartic gauge couplings.


title:
Highly spin-polarized deuterium atoms from the UV dissociation of
  Deuterium Iodide

abstract:
  We report the production of highly spin-polarized Deuterium atoms via
photodissociation of deuterium iodide at 270 nm. The velocity distribution of
both the deuterium and iodine photodissociation products is performed via
velocity mapping slice-imaging. Additionally, the angular momentum polarization
of the iodine products is studied using polarization-sensitive ionization
schemes. The results are consistent with excitation of the $A^1\Pi_1$ state
followed by adiabatic dissociation. The process produces $\sim$100\%
electronically polarized deuterium atoms at the time of dissociation, which is
then converted to $\sim 60\%$ nuclear D polarization after $\sim 1.6$ ns. These
production times for hyperpolarized deuterium allow collision-limited densities
of $\sim 10^{18}$ cm$^{-3}$, which is $\sim 10^6$ times higher than
conventional (Stern-Gerlach separation) methods. We discuss how such
high-density hyperpolarized deuterium atoms can be combined with laser fusion
to measure polarized D-D fusion cross sections.


title: Strong energy condition and complexity growth bound in holography

abstract:
  This paper proves that if eternal neutral black holes satisfy some general
conditions and matter fields only appear in the outside of the Killing horizon,
the strong energy condition is a sufficient condition to insure that the vacuum
Schwarzschild black hole has the fastest action growth of the same total
energy. This result is consistent with the bound of computational complexity
growth rate and gives a strong evidence for the holographic complexity-action
conjecture.


title: Stabilization of vortex beams in Kerr media by nonlinear absorption

abstract:
  We elaborate a new solution for the problem of stable propagation of
transversely localized vortex beams in homogeneous optical media with
self-focusing Kerr nonlinearity. Stationary nonlinear Bessel-vortex states are
stabilized against azimuthal breakup and collapse by multiphoton absorption,
while the respective power loss is offset by the radial influx of the power
from an intrinsic reservoir. A linear stability analysis and direct numerical
simulations reveal a region of stability of these vortices. Beams with multiple
vorticities have their stability regions too. These beams can then form robust
tubular filaments in transparent dielectrics as common as air, water and
optical glasses at sufficiently high intensities. We also show that the
tubular, rotating and speckle-like filamentation regimes, previously observed
in experiments with axicon-generated Bessel beams, can be explained as
manifestations of the stability or instability of a specific nonlinear
Bessel-vortex state, which is fully identified.


title: The electrostatic limit for the 3D Zakharov system

abstract:
  We consider the vectorial Zakharov system describing Langmuir waves in a
weakly magnetized plasma. In its original derivation the evolution for the
electric field envelope is governed by a Schr\"odinger type equation with a
singular parameter which is usually large in physical applications. Motivated
by this, we study the rigorous limit as this parameter goes to infinity. By
using some Strichartz type estimates to control separately the fast and slow
dynamics in the problem, we show that the evolution of the electric field
envelope is asymptotically constrained onto the space of irrotational vector
fields.


title: Increasing spanning forests in graphs and simplicial complexes

abstract:
  Let G be a graph with vertex set {1,...,n}. A spanning forest F of G is
increasing if the sequence of labels on any path starting at the minimum vertex
of a tree of F form an increasing sequence. Hallam and Sagan showed that the
generating function ISF(G,t) for increasing spanning forests of G has all
nonpositive integral roots. Furthermore they proved that, up to a change of
sign, this polynomial equals the chromatic polynomial of G precisely when
1,...,n is a perfect elimination order for G. We give new, purely combinatorial
proofs of these results which permit us to generalize them in several ways. For
example, we are able to bound the coefficients of ISF(G,t) using broken
circuits. We are also able to extend these results to simplicial complexes
using the new notion of a cage-free complex. A generalization to labeled
multigraphs is also given. We end by exploring spanning forests where the
increasing condition is replaced by having the label sequences avoid the
patterns 231, 312, and 321.


title:
Estimation of Received Signal Strength Distribution for Smart Meters
  with Biased Measurement Data Set

abstract:
  This letter presents an experimental study and a novel modelling approach of
the wireless channel of smart utility meters placed in basements or sculleries.
The experimental data consist of signal strength measurements of consumption
report packets. Since such packets are only registered if they can be decoded
by the receiver, the part of the signal strength distribution that falls below
the receiver sensitivity threshold is not observable. We combine a Rician
fading model with a bias function that captures the cut-off in the observed
signal strength measurements. Two sets of experimental data are analysed. It is
shown that the proposed method offers an approximation of the distribution of
the signal strength measurements that is better than a na\"ive Rician fitting.


title: The incorporation site of Er in nanosized CaF 2

abstract:
  The incorporation site of Er dopants inserted at high and low concentration
(respectively 5 and 0.5 mol %) in nanoparticles of CaF 2 is studied by X-ray
Absorption Spectroscopy (XAS) at the Er L III edge. The experimental data are
compared with the results of structural modeling based on Density Functional
Theory (DFT). DFT-based molecular dynamics is also used to simulate complete
theoretical EXAFS spectra of the model structures. The results is that Er
substitutes for Ca in the structure and in the low concentration case the
dopant ions are isolated. At high concentration the rare earth ions cluster
together binding Ca vacancies.


title: Sur une erreur dans les EGA

abstract:
  A mistake is pointed out in EGA I, Elements of algebraic geometry, concerning
corollary (2.4.4) which is not correct. Quite likely, the hitch has already
been noticed, and reported, but we know not who, nor where. New research is
recommended to find out if the error has spread or not, in the book and,
further, in the literature.


title:
Analytical approximation to the dynamics of a binary stars system with
  time depending mass variation

abstract:
  We study the classical dynamics of a binary stars when there is an
interchange of mass between them. Assuming that one of the star is more massive
than the other, the dynamics of the lighter one is analyzed as a function of
its time depending mass variation. Within our approximations and models for
mass transference, we obtain a general result which establishes that if the
lightest star looses mass, its period increases. If the lightest star win mass,
its period decreases.


title: On neutrinoless double electron capture

abstract:
  We found the probability for the neutrinoless double electron capture in the
case of $KK$ capture. We clarified the mechanism of the energy transfer from
the nucleus to the bound electrons. This enabled us to obtain the equations for
the probability of the $2EC0\nu$ process which modify those obtained earlier.
We found that the probability of the process is three orders of magnitude
larger than it was supposed earlier.


title:
Electromagnetic-Power-based Characteristic Mode Theory for Perfect
  Electric Conductors

abstract:
  In this paper, an ElectroMagnetic-Power-based Characteristic Mode Theory
(CMT) for PEC systems (PEC-EMP-CMT) is built. The PEC-EMP-CMT is valid for the
PEC systems which are surrounded by any electromagnetic environment, and it can
construct the complex characteristic currents and non-radiative Characteristic
Modes (CMs). In this paper, some traditional concepts, such as the system input
impedance and modal input impedance etc., are redefined; the traditional
characteristic quantity, Modal Significance (MS), is generalized; a series of
new power-based CM sets are introduced. It is proven in this paper that various
power-based CM sets of a certain objective PEC structure are independent of the
external environment and excitation; the non-radiative space constituted by all
non-radiative modes is identical to the interior resonance space constituted by
all interior resonant modes of closed PEC structures, and the non-radiative CMs
constitute a basis of the space. Based on above these, the normal Eigen-Mode
Theory (EMT) for closed PEC structures is classified into the PEC-EMP-CMT
framework. In addition, a variational formulation for the external scattering
problem of PEC structures is provided in this paper, based on the conservation
law of energy.


title:
Modified Bohm's theory for abstruse measurements: application to layer
  depth profiling by Auger spectroscopy

abstract:
  Modified Bohm formalism is applied to solve a problem of abstruse layer depth
profiles measured by the Auger electron spectroscopy technique in real physical
systems, i.e., the desorbed carbon/passive layer on NiTi substrate and the
adsorbed oxygen/surface of NiTi alloy. It is shown that abstruse layer profiles
may be converted to real layer structures using the modified Bohm theory, where
the quantum potential is due to an Auger electron effect. It is also pointed
out that the stationary probability density predicts multilayer structures of
abstruse depth profiles caused by carbon desorption and oxygen adsorption
processes. The criterion for a kind of break between the physical and
unphysical multilayer systems was found. We have concluded that the physics is
also characterized by the abstruse measurement and the modified Bohm formalism


title: Four-jet production in the $k_t$-factorisation

abstract:
  We discuss the single-parton and double-parton scattering (SPS or DPS)
effects in four-jet production at the LHC. The calculations of both
single-parton and double-parton scattering components are done in the
high-energy (or $k_{T}$)-factorization approach. Here we follow our recent
developments of relevant methods and tools. The calculations are performed for
kinematical situations relevant for two experimental measurements (ATLAS and
CMS) at the LHC. We compare our results to those reported by the ATLAS and CMS
collaborations for different sets of kinematical cuts. A special attention is
given to the optimization of kinematical conditions in order to enhance the
relative contribution of DPS in four-jet sample. Several differential
distributions are calculated and carefully discussed in the context of recent
and future searches for DPS effects at the LHC. The dependences of the relative
DPS amount is studied as a function of rapidity of jets, rapidity distance, and
various azimuthal correlations between jets. The regions with an enhanced DPS
contribution are identified.


title:
Ruled and quadric surfaces in the 3-dimensional Euclidean space
  satisfying $\Delta ^{III}\boldsymbol{x} = \varLambda \boldsymbol{x}$

abstract:
  We consider ruled and quadric surfaces in the 3-dimensional Euclidean space
which are of coordinate finite type with respect to the third fundamental form
$III$, i.e., their position vector $\boldsymbol{x}$ satisfies the relation
$\Delta ^{III}\boldsymbol{x}=\varLambda \boldsymbol{x}$ where $\varLambda $ is
a square matrix of order 3. We show that helicoids and spheres are the only
surfaces in $E^3$ satisfying the preceding relation.


title:
Modelling large-deforming fluid-saturated porous media using an Eulerian
  incremental formulation

abstract:
  The paper deals with modelling fluid saturated porous media subject to large
deformation. An Eulerian incremental formulation is derived using the problem
imposed in the spatial configuration in terms of the equilibrium equation and
the mass conservation. Perturbation of the hyperelastic porous medium is
described by the Biot model which involves poroelastic coefficients and the
permeability governing the Darcy flow. Using the material derivative with
respect to a convection velocity field we obtain the rate formulation which
allows for linearization of the residuum function. For a given time
discretization with backward finite difference approximation of the time
derivatives, two incremental problems are obtained which constitute the
predictor and corrector steps of the implicit time-integration scheme.
Conforming mixed finite element approximation in space is used. Validation of
the numerical model implemented in the SfePy code is reported for an isotropic
medium with a hyperelastic solid phase. The proposed linearization scheme is
motivated by the two-scale homogenization which will provide the local material
poroelastic coefficients involved in the incremental formulation.


title:
Solar Energetic Particle drifts and the energy dependence of 1 AU charge
  states

abstract:
  The event-averaged charge state of heavy ion Solar Energetic Particles
(SEPs), measured at 1 AU from the Sun, typically increases with the ions'
kinetic energy. The origin of this behaviour has been ascribed to processes
taking place within the acceleration region. In this paper we study the
propagation through interplanetary space of SEP Fe ions, injected near the Sun
with a variety of charge states that are uniformly distributed in energy, by
means of a 3D test particle model. In our simulations, due to gradient and
curvature drifts associated with the Parker spiral magnetic field, ions of
different charge propagate with very different efficiencies to an observer that
is not magnetically well connected to the source region. As a result we find
that, for many observer locations, the 1 AU event-averaged charge state <Q>, as
obtained from our model, displays an increase with particle energy E, in
qualitative agreement with spacecraft observations. We conclude that
drift-associated propagation is a possible explanation for the observed
distribution of <Q> versus E in SEP events, and that the distribution measured
in interplanetary space cannot be taken to represent that at injection.


title:
Mean field dynamics of graphs I: Evolution of probabilistic cellular
  automata for random and small-world graphs

abstract:
  It was recently shown how graphs can be used to provide descriptions of
psychopathologies, where symptoms of, say, depression, affect each other and
certain configurations determine whether someone could fall into a sudden
depression. To analyse changes over time and characterise possible future
behaviour is rather difficult for large graphs. We describe the dynamics of
networks using one-dimensional discrete time dynamical systems theory obtained
from a mean field approach to (elementary) probabilistic cellular automata
(PCA). Often the mean field approach is used on a regular graph (a grid or
torus) where each node has the same number of edges and the same probability of
becoming active. We show that we can use variations of the mean field of the
grid to describe the dynamics of the PCA on a random and small-world graph.
Bifurcation diagrams for the mean field of the grid, random, and small-world
graphs indicate possible phase transitions for certain parameter settings.
Extensive simulations indicate for different graph sizes (number of nodes) that
the mean field approximation is accurate. The mean field approach allows us to
provide possible explanations of 'jumping' behaviour in depression.


title:
The projective translation equation and rational plane flows. II.
  Corrections and additions

abstract:
  In this second part of the work, we correct the flaw which was left in the
proof of the main Theorem in the first part. This affects only a small part of
the text in this first part and two consecutive papers. Yet, some additional
arguments and additions are needed to claim the validity of the classification
results.
  With these new results in a disposition, algebraic and rational flows can be
much more easily and transparently classified. It also turns out that the
notion of an algebraic projective flow is a very natural one. For example, we
give an inductive (on dimension) method to build algebraic projective flows
with rational vector fields, and ask whether these account for all such flows.
  Further, we expand on results concerning rational flows in dimension $2$.
Previously we found such flows symmetric with respect to a linear involution
$i(x,y)=(y,x)$. Here we find all rational flows symmetric with respect to a
non-linear $1$-homogeneous involution $i(x,y)=(\frac{y^2}{x},y)$. We also find
all solenoidal rational flows. Up to linear conjugation, there appears to be
exactly two non-trivial examples.


title: Discrepancy bounds for $\boldsymbol{\beta}$-adic Halton sequences

abstract:
  Van der Corput and Halton sequences are well-known low-discrepancy sequences.
Almost twenty years ago Ninomiya defined analogues of van der Corput sequences
for $\beta$-numeration and proved that they also form low-discrepancy sequences
if $\beta$ is a Pisot number. Only very recently Robert Tichy and his
co-authors succeeded in proving that $\boldsymbol{\beta}$-adic Halton sequences
are equidistributed for certain parameters
$\boldsymbol{\beta}=(\beta_1,\ldots,\beta_s)$ using methods from ergodic
theory. In the present paper we continue this research and give discrepancy
estimates for $\boldsymbol{\beta}$-adic Halton sequences for which the
components $\beta_i$ are $m$-bonacci numbers. Our methods are quite different
and use dynamical and geometric properties of Rauzy fractals that allow to
relate $\boldsymbol{\beta}$-adic Halton sequences to rotations on high
dimensional tori. The discrepancies of these rotations can then be estimated by
classical methods relying on W.~M.~Schmidt's Subspace Theorem.


title: The xyz algorithm for fast interaction search in high-dimensional data

abstract:
  When performing regression on a dataset with $p$ variables, it is often of
interest to go beyond using main linear effects and include interactions as
products between individual variables. For small-scale problems, these
interactions can be computed explicitly but this leads to a computational
complexity of at least $\mathcal{O}(p^2)$ if done naively. This cost can be
prohibitive if $p$ is very large. We introduce a new randomised algorithm that
is able to discover interactions with high probability and under mild
conditions has a runtime that is subquadratic in $p$. We show that strong
interactions can be discovered in almost linear time, whilst finding weaker
interactions requires $\mathcal{O}(p^\alpha)$ operations for $1 < \alpha < 2$
depending on their strength. The underlying idea is to transform interaction
search into a closestpair problem which can be solved efficiently in
subquadratic time. The algorithm is called $\mathit{xyz}$ and is implemented in
the language R. We demonstrate its efficiency for application to genome-wide
association studies, where more than $10^{11}$ interactions can be screened in
under $280$ seconds with a single-core $1.2$ GHz CPU.


title:
Controlling energy transfer time between two coupled magnetic
  vortex-state disks

abstract:
  The influence of the in-plane uniaxial anisotropy (IPUA) in the mutual energy
transfer time ($\tau$) between two identical coupled nanodisks was studied.
Using an analytical dipolar model we obtained the interactions between the
disks along x and y directions (the coupling integrals) as a function of the
uniaxial anisotropy constant (K$_{\sigma}$) and the distance. We find that the
IPUA increases the interaction between the disks allowing shorter energy
transfer times. For our range of K$_{\sigma}$ values we get a drop in the
values of $\tau$ of up to about 70$\%$. From the lagrangian of the system we
obtained the equations of motion and the coupling frequencies of the dynamic
system as a function of distance and K$_{\sigma}$. The coupling frequencies
were also obtained from micromagnetic simulations. Our results of the
simulations are in agreement with the analytical results.


title:
Tunable bandgap and spin-orbit coupling by composition control of
  MoS$_{2}$ and MoO$_{x}$ (X=2 and 3) compounds

abstract:
  We report on composition controlled MoS$_{2}$ and MoO$_{x}$ (x=2 and 3)
compounds electrodeposited on Flourine dopped Tin Oxide (FTO) substrate. It was
observed that the relative content has systematic electrical and optical
changes for different thicknesses of layers ranging from $\approx$20 to 540 nm.
Optical and electrical bandgaps reveals a tuneable behavior by controlling the
relative content of compounds as well as a sharp transition from p to n-type of
semiconductivity. Moreover, spin-orbit interaction of Mo 3d doublet enhances by
reduction of MoO$_{3}$ content in thicker films. Our results convey path-way of
applying such compounds in optoelectronics and nanoelectronics devices.


title: Measurement of Fast Neutron Rate for NEOS Experiment

abstract:
  The fast neutron rate is measured at the site of NEOS experiment, a short
baseline neutrino experiment located in a tendon gallery of a commercial
nuclear power plant, using a 0.78-liter liquid scintillator detector. A pulse
shape discrimination technique is used to identify neutron signals. The
measurements are performed during the nuclear reactor-on and off periods and
found to be ~20 per day for both periods. The fast neutron rate is also
measured at an overground site with a negligible overburden and is found to be
~100 times higher than that at the NEOS experiment site.


title:
Harmonic Sum-based Method for Heart Rate Estimation using PPG Signals
  Affected with Motion Artifacts

abstract:
  Wearable photoplethysmography (WPPG) has recently become a common technology
in heart rate (HR) monitoring. General observation is that the motion artifacts
change the statistics of the acquired PPG signal. Consequently, estimation of
HR from such a corrupted PPG signal is challenging. However, if an
accelerometer is also used to acquire the acceleration signal simultaneously,
it can provide helpful information that can be used to reduce the motion
artifacts in the PPG signal. By dint of repetitive movements of the subjects
hands while running, the accelerometer signal is found to be quasi-periodic.
Over short-time intervals, it can be modeled by a finite harmonic sum (HSUM).
Using the harmonic sum (HSUM) model, we obtain an estimate of the instantaneous
fundamental frequency of the accelerometer signal. Since the PPG signal is a
composite of the heart rate information (that is also quasi-periodic) and the
motion artifact, we fit a joint harmonic sum (HSUM) model to the PPG signal.
One of the harmonic sums corresponds to the heart-beat component in PPG and the
other models the motion artifact. However, the fundamental frequency of the
motion artifact has already been determined from the accelerometer signal.
Subsequently, the HR is estimated from the joint HSUM model. The mean absolute
error in HR estimates was 0.7359 beats per minute (BPM) with a standard
deviation of 0.8328 BPM for 2015 IEEE Signal Processing (SP) cup data. The
ground-truth HR was obtained from the simultaneously acquired ECG for
validating the accuracy of the proposed method. The proposed method is compared
with four methods that were recently developed and evaluated on the same
dataset.


title: Humans: the hyper-dense species

abstract:
  Humans, like all organisms, are subject to fundamental biophysical laws. Van
Valen predicted that, because of zero-sum dynamics, all populations of all
species in a given environment flux the same amount of energy on average.
Damuth's 'energetic equivalence rule' supported Van Valen's conjecture by
showing a trade off between few big animals per area with high individual
metabolic rates compared to abundant small species with low energy
requirements. We use established metabolic scaling theory to compare variation
in densities and individual energy use in human societies to other land
mammals. We show that hunter-gatherers occurred at lower densities than a
mammal of our size. Most modern humans, in contrast, concentrate in large
cities at densities that are up to four orders of magnitude greater than
hunter-gatherers yet cities consume up to two orders of magnitude greater
energy per capita. Today, cities across the globe flux greater energy than net
primary productivity on a per area basis. This is possible through enormous
fluxes of energy and materials across urban boundaries to sustain hyper-dense,
modern humans. The metabolic rift with nature created by hyper-dense cities
supported by fossil fuel energy poses formidable challenges for establishing a
sustainable relationship on a rapidly urbanizing, yet finite planet.


title: Towards an Accurate Mathematical Model of Generic Nominally-Typed OOP

abstract:
  The construction of GNOOP as a domain-theoretic model of generic
nominally-typed OOP is currently underway. This extended abstract presents the
concepts of `nominal intervals' and `full generication' that are likely to help
in building GNOOP as an accurate mathematical model of generic nominally-typed
OOP. The abstract also presents few related category-theoretic suggestions. The
presented concepts and suggestions are particularly geared towards enabling
GNOOP to offer a precise and simple view of so-far-hard-to-analyze features of
generic OOP such as variance annotations (e.g., Java wildcard types) and erased
generics (e.g., Java type erasure).


title:
Tropical Vertex-Disjoint Cycles of a Vertex-Colored Digraph: Barter
  Exchange with Multiple Items Per Agent

abstract:
  In a barter exchange market, agents bring items and seek to exchange their
items with one another. Agents may agree to a k-way exchange involving a cycle
of k agents. A barter exchange market can be represented by a digraph where the
vertices represent items and the edges out of a vertex indicate the items that
an agent is willing to accept in exchange for that item. It is known that the
problem of finding a set of vertex-disjoint cycles with the maximum total
number of vertices (MAX-SIZE-EXCHANGE) can be solved in polynomial time. We
consider a barter exchange where each agent may bring multiple items, and items
of the same agent are represented by vertices with the same color. A set of
cycles is said to be tropical if for every color there is a cycle that contains
a vertex of that color. We show that the problem of determining whether there
exists a tropical set of vertex-disjoint cycles in a digraph
(TROPICAL-EXCHANGE) is NP-complete and APX-hard. This is equivalent to
determining whether it is possible to arrange an exchange of items among agents
such that every agent trades away at least one item. TROPICAL-MAX-SIZE-EXCHANGE
is a similar problem, where the goal is to find a set of vertex-disjoint cycles
that contains the maximum number of vertices and also contains all of the
colors in the graph. We show that this problem is likewise NP-complete and
APX-hard. For the restricted case where there are at most two vertices of each
color (corresponding to a restriction that each agent may bring at most two
items), both problems remain NP-hard but are in APX. Finally, we consider
MAX-SIZE-TROPICAL-EXCHANGE, where the set of cycles must primarily include as
many colors as possible and secondarily include as many vertices as possible.
We show that this problem is NP-hard.


title: Fault Tolerant Frequent Pattern Mining

abstract:
  FP-Growth algorithm is a Frequent Pattern Min- ing (FPM) algorithm that has
been extensively used to study correlations and patterns in large scale
datasets. While several researchers have designed distributed memory FP-Growth
algorithms, it is pivotal to consider fault tolerant FP-Growth, which can
address the increasing fault rates in large scale systems. In this work, we
propose a novel parallel, algorithm-level fault-tolerant FP-Growth algorithm.
We leverage algorithmic properties and MPI advanced features to guarantee an
O(1) space complexity, achieved by using the dataset memory space itself for
checkpointing. We also propose a recovery algorithm that can use in-memory and
disk-based checkpointing, though in many cases the recovery can be completed
without any disk access, and incurring no memory overhead for checkpointing. We
evaluate our FT algorithm on a large scale InfiniBand cluster with several
large datasets using up to 2K cores. Our evaluation demonstrates excellent
efficiency for checkpointing and recovery in comparison to the disk-based
approach. We have also observed 20x average speed-up in comparison to Spark,
establishing that a well designed algorithm can easily outperform a solution
based on a general fault-tolerant programming model.


title:
Deconstruction and differentiation of squeezed kitten states in a
  qubit-oscillator system

abstract:
  We study the evolution of the hybrid entangled squeezed states of the
qubit-oscillator system in the strong coupling domain. Following the adiabatic
approximation we obtain the reduced density matrices of the qubit and the
oscillator degrees of freedom. The oscillator reduced density matrix is
utilized to calculate the quasiprobability distributions such as the
Sudarshan-Glauber diagonal P -representation, the Wigner W -distribution, and
the nonnegative Husimi Q-function. The negativity associated with the W
-distribution acts as a measure of the nonclassicality of the state. The
existence of the multiple time scales induced by the interaction introduces
certain features in the bipartite system. In the strong coupling regime the
transient evolution to low entropy configurations reveals brief emergence of
nearly pure kitten states that may be regarded as superposition of uniformly
separated distinguishable squeezed coherent states. However, the quantum
fluctuations with a short time period engender bifurcation and subsequent
rejoining of these peaks in the phase space. The abovementioned doubling of the
number of peaks increases the entropy to its near maximal value. Nonetheless,
these states characterized by high entropy values, are endowed with a large
negativity of the W -distribution that points towards their non-Gaussian
behavior. This may be ascertained by the significantly large Hilbert-Schmidt
distance between the oscillator state and an ensemble of most general
statistical mixture of squeezed Gaussian states possessing nearly identical
second order quadrature moments as that of the oscillator.


title:
Analysis of the modernization prospects of the WLCG monitoring
  framework's messaging subsystem

abstract:
  The purpose of the project is an analysis of the modernization prospects of
the WLCG monitoring framework's messaging subsystem based on Nagios monitoring
software and Apache ActiveMQ technologies. The modernization process demands
thorough examination of the existing subsystem to determine the vital upgrade
requirements. Thus the work is focused on research of the main underlying
technologies, the existing subsystem's structure and revision of its design and
used software.


title:
High-Temperature Annealing of TiO2 Nanotube Membranes for Efficient
  Dye-Sensitized Solar Cells

abstract:
  We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in
tube-top-down configuration on FTO glass, and use them for constructing
frontside illuminated dye-sensitized solar cells. Prior to solar cell
construction, the tube-based photo-anodes are crystallized at different
temperatures (400-800{\deg}C), and the effects of tube electron transport
properties on the photovoltaic performance of the solar cells are investigated.
We show that improved solar cell efficiencies (up to ca. 8.0%) can be reached
by high-temperature treatment of the tube membranes. Consistently with electron
transport time measurements, remarkably enhanced electron mobility is enabled
when tube membranes are crystallized at 600{\deg}C.


title: Lazifying Conditional Gradient Algorithms

abstract:
  Conditional gradient algorithms (also often called Frank-Wolfe algorithms)
are popular due to their simplicity of only requiring a linear optimization
oracle and more recently they also gained significant traction for online
learning. While simple in principle, in many cases the actual implementation of
the linear optimization oracle is costly. We show a general method to lazify
various conditional gradient algorithms, which in actual computations leads to
several orders of magnitude of speedup in wall-clock time. This is achieved by
using a faster separation oracle instead of a linear optimization oracle,
relying only on few linear optimization oracle calls.


title: Parallel Stream Processing Against Workload Skewness and Variance

abstract:
  Key-based workload partitioning is a common strategy used in parallel stream
processing engines, enabling effective key-value tuple distribution over worker
threads in a logical operator. While randomized hashing on the keys is capable
of balancing the workload for key-based partitioning when the keys generally
follow a static distribution, it is likely to generate poor balancing
performance when workload variance occurs on the incoming data stream. This
paper presents a new key-based workload partitioning framework, with practical
algorithms to support dynamic workload assignment for stateful operators. The
framework combines hash-based and explicit key-based routing strategies for
workload distribution, which specifies the destination worker threads for a
handful of keys and assigns the other keys with the hashing function. When
short-term distribution fluctuations occur to the incoming data stream, the
system adaptively updates the routing table containing the chosen keys, in
order to rebalance the workload with minimal migration overhead within the
stateful operator. We formulate the rebalance operation as an optimization
problem, with multiple objectives on minimizing state migration costs,
controlling the size of the routing table and breaking workload imbalance among
worker threads. Despite of the NP-hardness nature behind the optimization
formulation, we carefully investigate and justify the heuristics behind key
(re)routing and state migration, to facilitate fast response to workload
variance with ignorable cost to the normal processing in the distributed
system. Empirical studies on synthetic data and real-world stream applications
validate the usefulness of our proposals and prove the huge advantage of our
approaches over state-of-the-art solutions in the literature.


title: Symmetrizing Cost of Quantum States

abstract:
  We introduce and analyze a task that we call symmetrization, in which a state
of a quantum system, associated with a symmetry group, is transformed by a
random unitary operation to a symmetric state. Each element of the unitary
ensemble is required to be symmetry preserving, in the sense that it keeps the
set of symmetric states invariant. We consider an asymptotic limit of
infinitely many copies and vanishingly small error, and analyze the
symmetrizing cost, that is, the minimum cost of randomness per copy required
for symmetrization. We prove that the symmetrizing cost of an arbitrary quantum
state is equal to the relative entropy of frameness, thereby providing it with
a direct operational meaning.


title:
Drell-Yan production at forward rapidities: a hybrid factorization
  approach

abstract:
  We discuss the Drell-Yan production of dileptons at high energies in the
forward rapidity region of proton-proton collisions in a hybrid high-energy
approach. This approach uses unintegrated gluon distributions in one proton and
collinear quark/antiquark distributions in the second proton.
  We compute various distributions for the case of low-mass dilepton production
and compare to the LHCb and ATLAS experimental data on dilepton mass
distributions. In distinction to dipole approaches, we include four Drell-Yan
structure functions as well as cuts at the level of lepton kinematics. The
impact of the interference structure functions is rather small for typical
experimental cuts. We find that both side contributions ($g q/\bar q$ and
$q/\bar q g$) have to be included even for the LHCb rapidity coverage which is
in contradiction with what is usually done in the dipole approach. We present
results for different unintegrated gluon distributions from the literature.
Some of them include saturation effects, but we see no clear hints of
saturation even at small $M_{ll}$.


title:
Thickness-Dependent and Magnetic-Field-Driven Suppression of
  Antiferromagnetic Order in Thin V$_{5}$S$_{8}$ Single Crystals

abstract:
  With materials approaching the 2d limit yielding many exciting systems with
intriguing physical properties and promising technological functionalities,
understanding and engineering magnetic order in nanoscale, layered materials is
generating keen interest. One such material is V$_{5}$S$_{8}$, a metal with an
antiferromagnetic ground state below the N\'eel temperature $T_{N} \sim$ 32 K
and a prominent spin-flop signature in the magnetoresistance (MR) when $H||c
\sim$ 4.2 T. Here we study nanoscale-thickness single crystals of
V$_{5}$S$_{8}$, focusing on temperatures close to $T_{N}$ and the evolution of
material properties in response to systematic reduction in crystal thickness.
Transport measurements just below $T_{N}$ reveal magnetic hysteresis that we
ascribe to a metamagnetic transition, the first-order magnetic field-driven
breakdown of the ordered state. The reduction of crystal thickness to $\sim$ 10
nm coincides with systematic changes in the magnetic response: $T_{N}$ falls,
implying that antiferromagnetism is suppressed; and while the spin-flop
signature remains, the hysteresis disappears, implying that the metamagnetic
transition becomes second order as the thickness approaches the 2d limit. This
work demonstrates that single crystals of magnetic materials with nanometer
thicknesses are promising systems for future studies of magnetism in reduced
dimensionality and quantum phase transitions.


title:
On the global regularity of the 2D critical Boussinesq system with
  $\alpha>2/3$

abstract:
  This paper examines the question for global regularity for the Boussinesq
equation with critical fractional dissipation. The main result states that the
system admits global regular solutions for all (reasonably) smooth and decaying
data, as long as $\al>2/3$. This significantly improves upon some recent works.
The main new idea is the introduction of a new, second generation
Hmidi-Keraani-Rousset type, change of variables, which further improves the
linear derivative in temperature term in the vorticity equation. This approach
is then complemented by new set of commutator estimates, which may be of
independent interest.


title: Microscopic theory of a non-equilibrium open bosonic chain

abstract:
  Quantum master equations form an important tool in the description of
transport problems in open quantum systems. However, they suffer from the
difficulty that the shape of the Lindblad dissipator depends sensibly on the
system Hamiltonian. Consequently, most of the work done in this field has
focused on phenomenological dissipators which act locally on different parts of
the system. In this paper we show how to construct Lindblad dissipators for
quantum many-body systems starting from a microscopic theory of the system-bath
interaction. We consider specifically a one-dimensional bosonic tight-binding
chain connected to two baths at the first and last site, kept at different
temperatures and chemical potentials. We then shown that, even though the bath
coupling is local, the effective Lindblad dissipator stemming from this
interaction is inherently non-local, affecting all normal modes of the system.
We then use this formalism to study the current of particles and energy through
the system and find that they have the structure of Landauer's formula, with
the bath spectral density playing the role of the transfer integral. Finally,
we consider infinitesimal temperature and chemical potential gradients and show
that the currents satisfy Onsager's reciprocal relations, which is a
consequence of the fact that the microscopic quantum dynamics obeys detailed
balance.


title:
Compromise Solutions for Robust Combinatorial Optimization with
  Variable-Sized Uncertainty

abstract:
  In classic robust optimization, it is assumed that a set of possible
parameter realizations, the uncertainty set, is modeled in a previous step and
part of the input. As recent work has shown, finding the most suitable
uncertainty set is in itself already a difficult task. We consider robust
problems where the uncertainty set is not completely defined. Only the shape is
known, but not its size. Such a setting is known as variable-sized uncertainty.
  In this work we present an approach how to find a single robust solution,
that performs well on average over all possible uncertainty set sizes. We
demonstrate that this approach can be solved efficiently for min-max robust
optimization, but is more involved in the case of min-max regret, where
positive and negative complexity results for the selection problem, the minimum
spanning tree problem, and the shortest path problem are provided. We introduce
an iterative solution procedure, and evaluate its performance in an
experimental comparison.


title:
Topological Semimetal-Insulator Quantum Phase Transition in Zintl
  Compounds Ba2X (X=Si, Ge)

abstract:
  By first-principles calculations, we find that Ba2X(X=Si, Ge) hosts a
topological semimetal phase with one nodal ring in the kx=0 plane, which is
protected by the glide mirror symmetry when spin-orbit coupling (SOC) is
ignored. The corresponding drumheadlike surface flat band appears on the (100)
surface in surface Green function calculation. Furthermore, a
topological-semimetal-to-insulator transition (TSMIT) is found. The nodal line
semimetal would evolve into topological insulator as SOC is turned on. The
topologically protected metallic surface states emerge around the Gamma=0
point, which could be tuned into topologically-trivial insulator state by more
than 3% hydrostatic strain. These results reveal a new category of materials
showing quantum phase transition between topological semimetal and insulator,
and tunability through elastic strain engineering.


title: Risk-Aware Algorithms for Adversarial Contextual Bandits

abstract:
  In this work we consider adversarial contextual bandits with risk
constraints. At each round, nature prepares a context, a cost for each arm, and
additionally a risk for each arm. The learner leverages the context to pull an
arm and then receives the corresponding cost and risk associated with the
pulled arm. In addition to minimizing the cumulative cost, the learner also
needs to satisfy long-term risk constraints -- the average of the cumulative
risk from all pulled arms should not be larger than a pre-defined threshold. To
address this problem, we first study the full information setting where in each
round the learner receives an adversarial convex loss and a convex constraint.
We develop a meta algorithm leveraging online mirror descent for the full
information setting and extend it to contextual bandit with risk constraints
setting using expert advice. Our algorithms can achieve near-optimal regret in
terms of minimizing the total cost, while successfully maintaining a sublinear
growth of cumulative risk constraint violation.


title:
Symmetry Breaking of Frequency Comb in Varying Normal Dispersion Fiber
  Ring Cavity

abstract:
  We build on a previously reported frequency comb of mode spacing 0.136 nm in
a fiber ring cavity of varying normal dispersion [1], to generate, for the
first time, a frequency comb of mode spacing 0.144 nm centered at 978.544 nm to
demonstrate the symmetry-breaking. By controlling the birefringence of the
optical cavity through fiber stretching and polarization control, the spacing
of the comb lines increases from 0.136 nm to 0.144 nm, and this small change in
mode spacing generates very different spectral symmetry-breaking in the
frequency comb relative to the frequency comb of mode spacing 0.136 nm.
Interestingly, non-uniform depletion of primary modes is also observed. The
experimental results are an important contribution in the continuing effort of
understanding the dynamics of frequency combs involving large number of modes,
nontrivial nonlinear waves and deterministic chaos.


title: Stepwise Choice of Covariates in High Dimensional Regression

abstract:
  Given data y(n) and p(n)covariates x(n) one problem in linear regression is
to decide which if any of the covariates to include. There are many articles on
this problem but all are based on a stochastic model for the data. This paper
gives what seems to be a new approach which does not require any form of model.
It is conceptually and algorithmically simple and consistency results can be
proved under appropriate assumptions.


title:
Radiative corrections to the magnetic moments of the proton and the
  neutron

abstract:
  We estimate the radiative corrections of order $\alpha/\pi$ to the magnetic
moments of the proton and the neutron. The photon-loop diagram of the
vertex-correction type is evaluated with phenomenological nucleon vector form
factors. Infrared-finiteness and gauge-invariance require the inclusion of the
wave-function renormalization factor from the self-energy diagram. Using recent
empirical form factor parametrizations the corrections amount to
$\delta\kappa_p= -3.42 \cdot 10^{-3}$ and $\delta\kappa_n= 1.34 \cdot 10^{-3}$.
We study also the effects from photon-loops with internal
$\Delta(1232)$-isobars. For two customary versions of the $\Delta N\gamma
$-vertex and spin-3/2 propagator, these radiative corrections have values of
$\delta\kappa_p^{(\Delta)}= (-0.9,\, 0.0)\!\cdot\! 10^{-3}$ and
$\delta\kappa_n^{(\Delta)} = (1.2,\,-0.8)\!\cdot\! 10^{-3}$, respectively.


title:
Search for R-parity violating supersymmetry with displaced vertices in
  proton-proton collisions at sqrt(s) = 8 TeV

abstract:
  Results are reported from a search for R-parity violating supersymmetry in
proton-proton collision events collected by the CMS experiment at a
center-of-mass energy of sqrt(s) = 8 TeV. The data sample corresponds to an
integrated luminosity of 17.6 inverse femtobarns. This search assumes a minimal
flavor violating model in which the lightest supersymmetric particle is a
long-lived neutralino or gluino, leading to a signal with jets emanating from
displaced vertices. In a sample of events with two displaced vertices, no
excess yield above the expectation from standard model processes is observed,
and limits are placed on the pair production cross section as a function of
mass and lifetime of the neutralino or gluino. At 95% confidence level, the
analysis excludes cross sections above approximately 1 fb for neutralinos or
gluinos with mass between 400 and 1500 GeV and mean proper decay length between
1 and 30 mm. Gluino masses are excluded below 1 and 1.3 TeV for mean proper
decay lengths of 300 micrometers and 1 mm, respectively, and below 1.4 TeV for
the range 2-30 mm. The results are also applicable to other models in which
long-lived particles decay into multijet final states.


title: Sterile neutrino search at NEOS Experiment

abstract:
  An experiment to search for light sterile neutrinos was conducted at a
reactor with a thermal power of 2.8 GW located at the Hanbit nuclear power
complex. The search was done with a detector consisting of a ton of Gd-loaded
liquid scintillator in a tendon gallery approximately 24 m from the reactor
core. The measured antineutrino event rate is 1976 per day with a signal to
background ratio of about 22. The shape of the antineutrino energy spectrum
obtained from eight-month data-taking period is compared with a hypothesis of
oscillations due to active-sterile antineutrino mixing. It is found to be
consistent with no oscillation. An excess around 5 MeV prompt energy range is
observed as seen in existing longer baseline experiments. The parameter space
of $\sin^{2}2\theta_{14}$ down below 0.1 for $\Delta m^{2}_{41}$ ranging from
0.2 eV$^{2}$ to 2.3 eV$^{2}$ and the optimum point for the previously reported
reactor antineutrino anomaly are excluded with a confidence level higher than
90%.


title:
Well-posed continuum equations for granular flow with compressibility
  and $\mu(I)$-rheology

abstract:
  Continuum modelling of granular flow has been plagued with the issue of
ill-posed equations for a long time. Equations for incompressible,
two-dimensional flow based on the Coulomb friction law are ill-posed regardless
of the deformation, whereas the rate-dependent $\mu(I)$-rheology is ill-posed
when the non-dimensional strain-rate $I$ is too high or too low. Here,
incorporating ideas from Critical-State Soil Mechanics, we derive conditions
for well-posedness of PDEs that combine compressibility with $I$-dependent
rheology. When the $I$-dependence comes from a specific friction coefficient
$\mu(I)$, our results show that, with compressibility, the equations are
well-posed for all deformation rates provided that $\mu(I)$ satisfies certain
minimal, physically natural, inequalities.

categories: cond-mat.soft math-ph math.MP physics.flu-dyn


title:
Disorder-induced Revival of the Bose-Einstein Condensation in
  Ni(Cl$_{1-x}$Br$_x$)$_2$-4SC(NH$_2$)$_2$ at High Magnetic Fields

abstract:
  Building on recent NMR experiments [Phys. Rev. Lett. 118, 067203], we
theoretically investigate the high magnetic field regime of the disordered
quasi-one-dimensional $S=1$ antiferromagnetic material
Ni(Cl$_{1-x}$Br$_x$)$_2$-4SC(NH$_2$)$_2$. The interplay between disorder,
chemically controlled by Br-doping, interactions, and the external magnetic
field, leads to a very rich phase diagram. Beyond the well-known
antiferromagnetically ordered regime, analog of a Bose condensate of magnons,
which disappears when $H\ge 12.3$ T, we unveil a resurgence of phase coherence
at higher field $H\sim 13.6$ T, induced by the doping. Interchain couplings
stabilize finite temperature long-range order whose extension in the field -
temperature space is governed by the concentration of impurities $x$. Such a
"mini-condensation" contrasts with previously reported Bose-glass physics in
the same regime, and should be accessible to experiments.


title: The canonical join complex

abstract:
  In this paper, we study the combinatorics of a certain minimal factorization
of the elements in a finite lattice $L$ called the canonical join
representation. The join $\bigvee A =w$ is the canonical join representation of
$w$ if $A$ is the unique lowest subset of $L$ satisfying $\bigvee A=w$ (where
"lowest" is made precise by comparing order ideals under containment). When
each element in $L$ has a canonical join representation, we define the
canonical join complex to be the abstract simplicial complex of subsets $A$
such that $\bigvee A$ is a canonical join representation. We characterize the
class of finite lattices whose canonical join complex is flag, and show how the
canonical join complex is related to the topology of $L$.


title:
Anisotropic Boltzmann-Gibbs dynamics of strongly magnetized
  Vlasov-Fokker-Planck equations

abstract:
  We consider various sets of Vlasov-Fokker-Planck equations modeling the
dynamics of charged particles in a plasma under the effect of a strong magnetic
field. For each of them in a regime where the strength of the magnetic field is
effectively stronger than that of collisions we first formally derive
asymptotically reduced models. In this regime, strong anisotropic phenomena
occur; while equilibrium along magnetic field lines is asymptotically reached
our asymptotic models capture a non trivial dynamics in the perpendicular
directions. We do check that in any case the obtained asymptotic model defines
a well-posed dynamical system and when self consistent electric fields are
neglected we provide a rigorous mathematical justification of the formally
derived systems. In this last step we provide a complete control on solutions
by developing anisotropic hypocoercive estimates.


title: Spiral Density Waves in a Young Protoplanetary Disk

abstract:
  Gravitational forces are expected to excite spiral density waves in
protoplanetary disks, disks of gas and dust orbiting young stars. However,
previous observations that showed spiral structure were not able to probe disk
midplanes, where most of the mass is concentrated and where planet formation
takes place. Using the Atacama Large Millimeter/submillimeter Array we detected
a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding
the young star Elias 2-27. The arms extend to the disk outer regions and can be
traced down to the midplane. These millimeter-wave observations also reveal an
emission gap closer to the star than the spiral arms. We argue that the
observed spirals trace shocks of spiral density waves in the midplane of this
young disk.


title: Certified randomness between mistrustful players

abstract:
  It is known that if two players achieve a superclassical score at a nonlocal
game $G$, then their outputs are certifiably random - that is, regardless of
the strategy used by the players, a third party will not be able to perfectly
predict their outputs (even if he were given their inputs). We prove that for
any complete-support game $G$, there is an explicit nonzero function $F_G$ such
that if Alice and Bob achieve a superclassical score of $s$ at $G$, then Bob
has a probability of at most $1 - F_G ( s )$ of correctly guessing Alice's
output after the game is played. Our result implies that certifying global
randomness through such games must necessarily introduce local randomness.


title:
Efficient Random Sampling -- Parallel, Vectorized, Cache-Efficient, and
  Online

abstract:
  We consider the problem of sampling $n$ numbers from the range
$\{1,\ldots,N\}$ without replacement on modern architectures. The main result
is a simple divide-and-conquer scheme that makes sequential algorithms more
cache efficient and leads to a parallel algorithm running in expected time
$\mathcal{O}(n/p+\log p)$ on $p$ processors, i.e., scales to massively parallel
machines even for moderate values of $n$. The amount of communication between
the processors is very small (at most $\mathcal{O}(\log p)$) and independent of
the sample size. We also discuss modifications needed for load balancing,
online sampling, sampling with replacement, Bernoulli sampling, and
vectorization on SIMD units or GPUs.


title:
Online Thevenin Equivalent Parameter Estimation using Nonlinear and
  Linear Recursive Least Square Algorithm

abstract:
  This paper proposes method for detection, estimation of Thevenin equivalent
parameters to describe power system behavior. Thevenin equivalent estimation is
a challenge due to variation in system states caused by power flow in the
network. Thevenin equivalent calculation based on changes in system with
multiple sources integrated with grid, isolated distributed generator system is
analysed and nonlinear least square fit estimation technique for algorithm is
adopted. Linear least square fit is used with a linearized model. Performance
evaluation of proposed method is carried out through mathematical model,
nonlinear and linear least square fit based algorithm technique and simulation
through MATLAB/SIMULINK package. Accurate grid and source side impedance
estimation technique is applicable for distributed generation sources
interfaced with grid to improve dynamic response, stability, reliability when
subjected to faults or any other disturbances in network. Algorithm can
accurately estimate Thevenin equivalent of multiple sources connected in
parallel simultaneously with voltage and current phasor measurements at point
of common coupling. Mathematical analysis and simulation results validate the
effectiveness of proposed method.


title: Periodic energy transport and entropy production in quantum electronics

abstract:
  The problem of time-dependent particle transport in quantum conductors is
nowadays a well established topic. In contrast, the way in which energy and
heat flow in mesoscopic systems subjected to dynamical drivings is a relatively
new subject that cross-fertilize both fundamental developments of quantum
thermodynamics and practical applications in nanoelectronics and quantum
information. In this short review, we discuss from a thermodynamical
perspective recent investigations on nonstationary heat and work generated in
quantum systems, emphasizing open questions and unsolved issues.


title: CP violation during the electroweak sphaleron transitions

abstract:
  We suggest a specific semiclassical background field, the so called pure
gauge sphaleron explosion, to evaluate the magnitude of the CP violation
stemming from the standard phase of the CKM matrix. We use it to evaluate the
matrix elements of some next-to-leading order effective CP-violating operators
suggested in the literature. We also derive the scale dependence of the
corresponding coefficients. Finally, we discuss the expected magnitude of the
CP violation in the cold electroweak scenario.


title: Free globularily generated double categories

abstract:
  This is the first part of a two paper series studying free globularily
generated double categories. In this first installment we introduce the free
globularily generated double category construction. The free globularily
generated double category construction canonically associates to every
bicategory together with a possible category of vertical morphisms, a double
category fixing this set of initial data in a free and minimal way. We use the
free globularily generated double category to study length, free products, and
problems of internalization. We use the free globularily generated double
category construction to provide formal functorial extensions of the Haagerup
standard form construction and the Connes fusion operation to inclusions of
factors of not-necessarily finite Jones index.


title:
Gate-tunable, normally-on to normally-off memristance transition in
  patterned LaAlO3/SrTiO3 interfaces

abstract:
  We report gate-tunable memristive switching in patterned LaAlO3/SrTiO3
interfaces at cryogenic temperatures. The application of voltages in the order
of a few volts to the back gate of the device allows controlling and
switching-on and -off the inherent memory functionality (memristance). For
large and small gate voltages a simple non-linear resistance characteristic is
observed while a pinched hysteresis loop and memristive switching occurs in an
intermediate voltage range. The memristance is further controlled by the
density of oxygen vacancies, which is tuned by annealing the sample at 300
{\deg}C in nitrogen atmosphere. Depending on the annealing time the memristance
at zero gate voltage can be switched on and off leading to normally-on and
normally-off memristors. The presented device offers reversible and
irreversible control of memristive characteristics by gate voltages and
annealing, respectively, which may allow to compensate fabrication
variabilities of memristors that complicate the realization of large
memristor-based neural networks.


title: Computing the static potential using non-string-like trial states

abstract:
  We present a method for computing the static quark-antiquark potential, which
is not based on Wilson loops, but where the trial states are formed by
eigenvector components of the covariant lattice Laplace operator. We have
tested this method in SU(2) Yang-Mills theory and have obtained results with
statistical errors of similar magnitude compared to a standard Wilson loop
computation. The runtime of the method is, however, significantly smaller, when
computing the static potential not only for on-axis, but also for many off-axis
quark-antiquark separations, i.e. when a fine spatial resolution is required.


title: Calibration setup for ultralow-current transresistance amplifiers

abstract:
  We describe a calibration setup for the transresistance of low-current
amplifiers, based on the capacitance-charging method. The calibration can be
performed in the current range of typical interest for electron counting
experiments. The setup implementation is simple and rugged, and is suitable to
be embedded in larger experiments where the amplifier is employed. The
calibration is traceable to units of capacitance and of time. The base relative
accuracy of the implementation is in the 10^-5 range.


title: Modeling the reverberation of optical polarization in AGN

abstract:
  According to the standard paradigm, the strong and compact luminosity of
active galactic nuclei (AGN) is due to multi-temperature black body emission
originating from an accretion disk formed around a supermassive black hole.
This central engine is thought to be surrounded by a dusty region along the
equatorial plane and by ionized winds along the poles. The innermost regions
cannot yet be resolved neither in the optical nor in the infrared and it is
fair to say that we still lack a satisfactory understanding of the physical
processes, geometry and composition of the central (sub-parsec) components of
AGN. Like spectral or polarimetric observations, the reverberation data needs
to be modeled in order to infer constraints on the AGN geometry (such as the
inner radius or the half-opening angle of the dusty torus). In this research
note, we present preliminary modeling results using a time-dependent Monte
Carlo method to solve the radiative transfer in a simplified AGN set up. We
investigate different model configurations using both polarization and time
lags and find a high dependency on the geometry to the time-lag response. For
all models there is a clear distinction between edge-on or face-on viewing
angles for fluxes and time lags, the later showing a higher
wavelength-dependence than the former. Time lags, polarization and fluxes point
toward a clear dichotomy between the different inclinations of AGN, a method
that could help us to determine the true orientation of the nucleus in Seyfert
galaxies.


title: Neural Machine Translation Advised by Statistical Machine Translation

abstract:
  Neural Machine Translation (NMT) is a new approach to machine translation
that has made great progress in recent years. However, recent studies show that
NMT generally produces fluent but inadequate translations (Tu et al. 2016b; Tu
et al. 2016a; He et al. 2016; Tu et al. 2017). This is in contrast to
conventional Statistical Machine Translation (SMT), which usually yields
adequate but non-fluent translations. It is natural, therefore, to leverage the
advantages of both models for better translations, and in this work we propose
to incorporate SMT model into NMT framework. More specifically, at each
decoding step, SMT offers additional recommendations of generated words based
on the decoding information from NMT (e.g., the generated partial translation
and attention history). Then we employ an auxiliary classifier to score the SMT
recommendations and a gating function to combine the SMT recommendations with
NMT generations, both of which are jointly trained within the NMT architecture
in an end-to-end manner. Experimental results on Chinese-English translation
show that the proposed approach achieves significant and consistent
improvements over state-of-the-art NMT and SMT systems on multiple NIST test
sets.


title:
Contributions of the Cherenkov Telescope Array (CTA) to the 6th
  International Symposium on High-Energy Gamma-Ray Astronomy (Gamma 2016)

abstract:
  List of contributions from the Cherenkov Telescope Array (CTA) Consortium
presented at the 6th International Symposium on High-Energy Gamma-Ray Astronomy
(Gamma 2016), July 11-15, 2016, in Heidelberg, Germany.


title: Global solution curves for self-similar equations

abstract:
  We consider positive solutions of a semilinear Dirichlet problem \[ \Delta
u+\lambda f(u)=0, \;\; \mbox{for $|x|<1$}, \;\; u=0 , \;\; \mbox{when $|x|=1$}
\] on a unit ball in $R^n$. For four classes of self-similar equations it is
possible to parameterize the entire (global) solution curve through the
solution of a single initial value problem. This allows us to derive results on
the multiplicity of solutions, and on their Morse indices. In particular, we
easily recover the classical results of D.D. Joseph and T.S. Lundgren [6] on
the Gelfand problem. Surprisingly, the situation turns out to be different for
the generalized Gelfand problem, where infinitely many turns are possible for
any space dimension $n \geq 3$. We also derive detailed results for the
equation modeling electrostatic micro-electromechanical systems (MEMS), in
particular we easily recover the main result of Z. Guo and J. Wei [4], and we
show that the Morse index of the solutions increases by one at each turn. We
also consider the self-similar Henon's equation.


title:
Coherent Atom-Phonon Interaction through Mode Field Coupling in Hybrid
  Optomechanical Systems

abstract:
  We propose a novel type of optomechanical coupling which enables a tripartite
interaction between a quantum emitter, an optical mode and a macroscopic
mechanical oscillator. The interaction uses a mechanism we term mode field
coupling: mechanical displacement modifies the spatial distribution of the
optical mode field, which in turn modulates the atom-photon coupling rate. In
properly designed multimode optomechanical systems, we can achieve situations
in which mode field coupling is the only possible interaction pathway for the
system. This enables, for example, swapping of a single excitation between
emitter and phonon, creation of nonclassical states of motion and mechanical
ground-state cooling in the bad-cavity regime. Importantly, the emitter-phonon
coupling rate can be enhanced through an optical drive field, allowing active
control of strong atom-phonon coupling for realistic experimental parameters.


title:
Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic
  Oxidation of Benzyl Alcohol to Benzaldehyde under Visible Light

abstract:
  TiO2 nanotube arrays grown by anodization were coated with thin layers of
polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were
used as photocatalyst for selective oxidation of benzyl alcohol under
monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no
by-products could be detected. A maximized reaction yield was obtained in
O2-saturated acetonitrile. A mechanism is proposed that implies firstly the
charge carrier generation in polydopamine as a consequence of visible light
absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction
band, and subsequently transferred to dissolved O2 to form oxygen radical
anions. These radicals react with benzyl alcohol and lead to its selective
dehydrogenation oxidation towards benzaldehyde.


title:
Polylogarithmic Bounds on the Competitiveness of Min-cost (Bipartite)
  Perfect Matching with Delays

abstract:
  We consider the problem of online Min-cost Perfect Matching with Delays
(MPMD) recently introduced by Emek et al, (STOC 2016). This problem is defined
on an underlying $n$-point metric space. An adversary presents real-time
requests online at points of the metric space, and the algorithm is required to
match them, possibly after keeping them waiting for some time. The cost
incurred is the sum of the distances between matched pairs of points (the
connection cost), and the sum of the waiting times of the requests (the delay
cost). We present an algorithm with a competitive ratio of $O(\log n)$, which
improves the upper bound of $O(\log^2n+\log\Delta)$ of Emek et al, by removing
the dependence on $\Delta$, the aspect ratio of the metric space (which can be
unbounded as a function of $n$). The core of our algorithm is a deterministic
algorithm for MPMD on metrics induced by edge-weighted trees of height $h$,
whose cost is guaranteed to be at most $O(1)$ times the connection cost plus
$O(h)$ times the delay cost of every feasible solution. The reduction from MPMD
on arbitrary metrics to MPMD on trees is achieved using the result on embedding
$n$-point metric spaces into distributions over weighted hierarchically
separated trees of height $O(\log n)$, with distortion $O(\log n)$. We also
prove a lower bound of $\Omega(\sqrt{\log n})$ on the competitive ratio of any
randomized algorithm. This is the first lower bound which increases with $n$,
and is attained on the metric of $n$ equally spaced points on a line.
  The problem of Min-cost Bipartite Perfect Matching with Delays (MBPMD) is the
same as MPMD except that every request is either positive or negative, and
requests can be matched only if they have opposite polarity. We prove an upper
bound of $O(\log n)$ and a lower bound of $\Omega(\log^{1/3}n)$ on the
competitive ratio of MBPMD with a more involved analysis.


title: Reachability Analysis of Innermost Rewriting

abstract:
  We consider the problem of inferring a grammar describing the output of a
functional program given a grammar describing its input. Solutions to this
problem are helpful for detecting bugs or proving safety properties of
functional programs, and several rewriting tools exist for solving this
problem. However, known grammar inference techniques are not able to take
evaluation strategies of the program into account. This yields very imprecise
results when the evaluation strategy matters. In this work, we adapt the Tree
Automata Completion algorithm to approximate accurately the set of terms
reachable by rewriting under the innermost strategy. We formally prove that the
proposed technique is sound and precise w.r.t. innermost rewriting. We show
that those results can be extended to the leftmost and rightmost innermost
case. The algorithms for the general innermost case have been implemented in
the Timbuk reachability tool. Experiments show that it noticeably improves the
accuracy of static analysis for functional programs using the call-by-value
evaluation strategy.


title: A modular interpretation of various cubic towers

abstract:
  In this article we give a Drinfeld modular interpretation for various towers
of function fields meeting Zink's bound.


title:
Plasma beta dependence of the ion-scale spectral break of solar wind
  turbulence: high-resolution 2D hybrid simulations

abstract:
  We investigate properties of the ion-scale spectral break of solar wind
turbulence by means of two-dimensional high-resolution hybrid particle-in-cell
simulations. We impose an initial ambient magnetic field perpendicular to the
simulation box and add a spectrum of in-plane, large-scale, magnetic and
kinetic fluctuations. We perform a set of simulations with different values of
the plasma beta, distributed over three orders of magnitude, from 0.01 to 10.
In all the cases, once turbulence is fully developed, we observe a power-law
spectrum of the fluctuating magnetic field on large scales (in the inertial
range) with a spectral index close to -5/3, while in the sub-ion range we
observe another power-law spectrum with a spectral index systematically varying
with $\beta$ (from around -3.6 for small values to around -2.9 for large ones).
The two ranges are separated by a spectral break around ion scales. The length
scale at which this transition occurs is found to be proportional to the ion
inertial length, $d_i$, for $\beta \ll 1$ and to the ion gyroradius, $\rho_i =
d_i\sqrt{\beta}$, for $\beta \gg 1$, i.e., to the larger between the two scales
in both the extreme regimes. For intermediate cases, i.e., $\beta \sim 1$, a
combination of the two scales is involved. We infer an empiric relation for the
dependency of the spectral break on $\beta$ that provides a good fit over the
whole range of values. We compare our results with in situ observations in the
solar wind and suggest possible explanations for such a behavior.


title: Character varieties for real forms

abstract:
  Let $\Gamma$ be a finitely generated group and $G$ a real form of
$\mathrm{SL}_n(\mathbb{C})$. We propose a definition for the $G$-character
variety of $\Gamma$ as a subset of the $\mathrm{SL}_n(\mathbb{C})$-character
variety of $\Gamma$. We consider two anti-holomorphic involutions of the
$\mathrm{SL}_n(\mathbb{C})$ character variety and show that an irreducible
representation with character fixed by one of them is conjugate to a
representation taking values in a real form of $\mathrm{SL}_n(\mathbb{C})$. We
study in detail an example: the $\mathrm{SL}_n(\mathbb{C})$, $\mathrm{SU}(2,1)$
and $\mathrm{SU}(3)$ character varieties of the free product
$\mathbb{Z}/3\mathbb{Z} * \mathbb{Z}/3\mathbb{Z}$.


title: The Peaking Phenomenon in Semi-supervised Learning

abstract:
  For the supervised least squares classifier, when the number of training
objects is smaller than the dimensionality of the data, adding more data to the
training set may first increase the error rate before decreasing it. This,
possibly counterintuitive, phenomenon is known as peaking. In this work, we
observe that a similar but more pronounced version of this phenomenon also
occurs in the semi-supervised setting, where instead of labeled objects,
unlabeled objects are added to the training set. We explain why the learning
curve has a more steep incline and a more gradual decline in this setting
through simulation studies and by applying an approximation of the learning
curve based on the work by Raudys & Duin.


title: The reconstruction software for the MICE scintillating fibre trackers

abstract:
  The Muon Ionization Cooling Experiment (MICE) will demonstrate the principle
of muon beam phase-space reduction via ionization cooling. Muon beam cooling
will be required for the proposed Neutrino Factory or Muon Collider. The
phase-space before and after the cooling cell must be measured precisely. This
is achieved using two scintillating-fibre trackers, each placed in a solenoidal
magnetic field. This paper describes the software reconstruction for the fibre
trackers: the GEANT4 based simulation; the implementation of the geometry;
digitisation; space-point reconstruction; pattern recognition; and the final
track fit based on a Kalman filter. The performance of the software is
evaluated by means of Monte Carlo studies and the precision of the final track
reconstruction is evaluated.


title:
A Bourgain-Brezis-Mironescu characterization of higher order
  Besov-Nikol'skii spaces

abstract:
  We study a class of nonlocal functionals in the spirit of the recent
characterization of the Sobolev spaces $W^{1,p}$ derived by Bourgain, Brezis
and Mironescu. We show that it provides a common roof to the description of the
$BV(\mathbb{R}^N)$, $W^{1,p}(\mathbb{R}^N)$, $B_{p,\infty}^s(\mathbb{R}^N)$ and
$C^{0,1}(\mathbb{R}^N)$ scales and we obtain new equivalent characterizations
for these spaces. We also establish a non-compactness result for sequences and
new (non-)limiting embeddings between Lipschitz and Besov spaces which extend
the previous known results.


title:
Spatio-temporal Gaussian processes modeling of dynamical systems in
  systems biology

abstract:
  Quantitative modeling of post-transcriptional regulation process is a
challenging problem in systems biology. A mechanical model of the regulatory
process needs to be able to describe the available spatio-temporal protein
concentration and mRNA expression data and recover the continuous
spatio-temporal fields. Rigorous methods are required to identify model
parameters. A promising approach to deal with these difficulties is proposed
using Gaussian process as a prior distribution over the latent function of
protein concentration and mRNA expression. In this study, we consider a partial
differential equation mechanical model with differential operators and latent
function. Since the operators at stake are linear, the information from the
physical model can be encoded into the kernel function. Hybrid Monte Carlo
methods are employed to carry out Bayesian inference of the partial
differential equation parameters and Gaussian process kernel parameters. The
spatio-temporal field of protein concentration and mRNA expression are
reconstructed without explicitly solving the partial differential equation.


title: The amplitude mode in three-dimensional dimerized antiferromagnets

abstract:
  The amplitude (Higgs) mode is a ubiquitous collective excitation related to
spontaneous breaking of a continuous symmetry. We combine quantum Monte Carlo
(QMC) simulations with stochastic analytic continuation to investigate the
dynamics of the amplitude mode in a three-dimensional dimerized quantum spin
system. We characterize this mode by calculating the spin and dimer spectral
functions near the quantum critical point, finding that both the energies and
the intrinsic widths satisfy field-theoretical scaling predictions. While the
line width of the spin response is close to that observed in neutron scattering
experiments on TlCuCl$_3$, the dimer response is significantly broader. Our
results demonstrate that highly non-trivial dynamical properties are accessible
by modern QMC and analytic continuation methods.


title:
On the binary origin of FS CMa stars: young massive clusters as test
  beds

abstract:
  FS CMa stars are low-luminosity objects showing the B[e] phenomenon whose
evolutionary origin is yet to be unraveled. Various binary-related hypotheses
have been recently proposed, two of them involving the spiral-in evolution of
the binary orbit. The latter occurs more often in dense stellar environments
like young massive clusters (YMCs). Hence, a systematic study of FS CMa stars
in YMCs would be crucial to find out how these objects are created. In YMCs,
two FS CMa stars have been confirmed and three candidates have been found
through a search method based on narrow-band photometry at Paschen-$\alpha$ and
the neighboring continuum. We apply this method to archival data from the
Paschen-$\alpha$ survey of the Galactic Center region, yielding a new candidate
in the Quintuplet cluster. Limitations of this method and other alternatives
are briefly discussed.


title:
Microseconds, milliseconds and seconds: deconvoluting the dynamic
  behaviour of planar perovskite solar cells

abstract:
  Perovskite solar cells (PSC) are shown to behave as coupled ionic-electronic
conductors with strong evidence that the ionic environment moderates both the
rate of electron-hole recombination and the band offsets in planar PSC.
Numerous models have been presented to explain the behavior of perovskite solar
cells, but to date no single model has emerged that can explain both the
frequency and time dependent response of the devices. Here we present a
straightforward coupled ionic-electronic model that can be used to explain the
large amplitude transient behavior and the impedance response of PSC.


title:
Suspended Pt nanoparticles over TiO2 nanotubes for enhanced
  photocatalytic H2 evolution

abstract:
  In the present work we introduce a technique to form a photocatalyst, based
on Pt nanoparticles suspended over the mouth of TiO2 nanotubes. These
structures are obtained by the decoration of the top end of highly ordered TiO2
nanotubes with a web of TiO2 nanofibrils, followed by sputter deposition of a
minimum amount of Pt. A subsequent thermal dewetting step forms 3-6 nm-sized Pt
nanoparticles along the nanofibrils. These structures, when compared to
conventional Pt decoration techniques of TiO2 nanotubes, show a strongly
enhanced photocatalytic H2 evolution efficiency.


title:
Noble metals on anodic TiO2 nanotubes mouths: Thermal dewetting of
  minimal Pt co-catalyst loading leads to significantly enhanced photocatalytic
  H2 generation

abstract:
  The least is the best. We introduce a technique to strongly reduce Pt use for
photocatalytic hydrogen generation from TiO2 nanotubes. By site-selectively
depositing thin layers of Pt only at the mouth of the nanotubes and by a
subsequent thermal dewetting step, we achieve an outstanding photocatalytic
improvement with minimal amounts of co-catalyst.


title:
Highly Efficient Fuel Cell Electrodes from Few-Layer Graphene Sheets and
  Electrochemically Deposited Palladium Nanoparticles

abstract:
  An extremely efficient ethanol fuel cell electrode is produced by combining
the large surface area of vertically oriented and highly conductive few-layer
graphene sheets with electrochemically deposited palladium nanoparticles. The
electrodes show an extraordinary high catalyst activity of up to 7977 mA/(mg
Pd) at low catalyst loadings of 0.64 $\mu$g/cm$^2$ and a very high current
density of up to 106 mA/cm$^2$ at high catalyst loadings of 83 $\mu$g/cm$^2$.
Moreover, the low onset potentials combined with a good poisoning resistance
and long-term stability make these electrodes highly suitable for real
applications. These features are achieved by using a newly developed
electrochemical catalyst deposition process exploiting high voltages of up to
3.5 kV. This technique allows controlling the catalyst amount ranging from a
homogeneous widespread distribution of small ($\leq$ 10 nm) palladium
nanoparticles to rather dense layers of particles, while every catalyst
particle has electrical contact to the graphene electrode.


title: On cosmological constant of Generalized Robertson-Walker space-times

abstract:
  We study Einstein's equation in $(m+n)D$ and $(1+n)D$ warped spaces
$(\bar{M},\bar{g})$ and classify all such spaces satisfying Einstein equations
$\bar{G}=-\bar{\Lambda}\bar{g}$. We show that the warping function not only can
determine the cosmological constant $\bar{\Lambda}$ but also it can determine
the cosmological constant ${\Lambda}$ appearing in the induced Einstein
equations ${G}=-{\Lambda}{h}$ on $(M_2, h)$. Moreover, we discuss on the origin
of the $4D$ cosmological constant as an emergent effect of higher dimensional
warped spaces.


title: Urban-rural gap and poverty traps in China: A prefecture level analysis

abstract:
  Urban-rural gap and regional inequality are long standing problems in China
and result in considerable number of studies. This paper examines the dynamic
behaviors of incomes for both urban and rural areas with a prefectural data
set. The analysis is conducted by using a distribution dynamics approach, which
have advantages in examination on persistence, polarization and convergence
clubs. The results show that persistence and immobility are the dominant
characteristics in the income distribution dynamics. The prefectural urban and
rural areas converge into their own steady states differentiated in income
levels. This pattern of urban-rural gap also exists in three regional groups,
namely the eastern, central and western regions. Examination on the dynamics of
the poorest areas shows that geographical poverty traps exist in both urban and
rural prefectural areas. Our results indicate that more policy interventions
are required to narrow down the urban-rural gap and to eliminate the poverty
traps in China.


title: Monitoring the Variable Gamma-Ray Sky with HAWC

abstract:
  The High Altitude Water Cherenkov (HAWC) observatory monitors the gamma-ray
sky at energies between 100 GeV and 100 TeV with a wide field of view of $\sim
2$ steradians. A duty cycle of $\sim 90$% allows HAWC to scan two thirds of the
sky every day and has resulted in an unprecedented data set of unbiased and
evenly sampled daily TeV light curves, collected over more than one year of
operation since the completion of the array. These measurements highlight the
flaring activity of the blazars Markarian 421 and Markarian 501 and allow us to
discuss the frequency of high flux states and correlations with observations at
other wavelengths. We will present a first look at how we are using the HAWC
data to search for gamma-ray signals and variability from the directions of
possible TeV gamma-ray sources and the locations of high-energy neutrinos
observed by IceCube. For a selected list of objects, we perform a search for
flares in real time during data taking in order to quickly alert other
observatories when increased activity is detected. We include here the first
results from these flare trigger efforts, focused on monitoring blazars.


title: 3D Hydrodynamic Simulations of Carbon Burning in Massive Stars

abstract:
  We present the first detailed three-dimensional (3D) hydrodynamic implicit
large eddy simulations of turbulent convection of carbon burning in massive
stars. Simulations begin with radial profiles mapped from a carbon burning
shell within a 15$\,\textrm{M}_\odot$ one-dimensional stellar evolution model.
We consider models with $128^3$, $256^3$, $512^3$ and $1024^3$ zones. The
turbulent flow properties of these carbon burning simulations are very similar
to the oxygen burning case. We performed a mean field analysis of the kinetic
energy budgets within the Reynolds-averaged Navier-Stokes framework. For the
upper convective boundary region, we find that the numerical dissipation is
insensitive to resolution for linear mesh resolutions above 512 grid points.
For the stiffer, more stratified lower boundary, our highest resolution model
still shows signs of decreasing sub-grid dissipation suggesting it is not yet
numerically converged. We find that the widths of the upper and lower
boundaries are roughly 30% and 10% of the local pressure scale heights,
respectively. The shape of the boundaries is significantly different from those
used in stellar evolution models. As in past oxygen-shell burning simulations,
we observe entrainment at both boundaries in our carbon-shell burning
simulations. In the large P\'eclet number regime found in the advanced phases,
the entrainment rate is roughly inversely proportional to the bulk Richardson
number, Ri$_{\rm B}$ ($\propto $Ri${\rm_B}^{-\alpha}$, $0.5\lesssim \alpha
\lesssim 1.0$). We thus suggest the use of Ri$_{\rm B}$ as a means to take into
account the results of 3D hydrodynamics simulations in new 1D prescriptions of
convective boundary mixing.


title:
Spatio-temporal Co-Occurrence Characterizations for Human Action
  Classification

abstract:
  The human action classification task is a widely researched topic and is
still an open problem. Many state-of-the-arts approaches involve the usage of
bag-of-video-words with spatio-temporal local features to construct
characterizations for human actions. In order to improve beyond this standard
approach, we investigate the usage of co-occurrences between local features. We
propose the usage of co-occurrences information to characterize human actions.
A trade-off factor is used to define an optimal trade-off between vocabulary
size and classification rate. Next, a spatio-temporal co-occurrence technique
is applied to extract co-occurrence information between labeled local features.
Novel characterizations for human actions are then constructed. These include a
vector quantized correlogram-elements vector, a highly discriminative PCA
(Principal Components Analysis) co-occurrence vector and a Haralick texture
vector. Multi-channel kernel SVM (support vector machine) is utilized for
classification. For evaluation, the well known KTH as well as the challenging
UCF-Sports action datasets are used. We obtained state-of-the-arts
classification performance. We also demonstrated that we are able to fully
utilize co-occurrence information, and improve the standard bag-of-video-words
approach.