title: Multilayer motif analysis of brain networks

abstract:
  In the last decade, network science has shed new light both on the structural
(anatomical) and on the functional (correlations in the activity) connectivity
among the different areas of the human brain. The analysis of brain networks
has made possible to detect the central areas of a neural system, and to
identify its building blocks by looking at overabundant small subgraphs, known
as motifs. However, network analysis of the brain has so far mainly focused on
anatomical and functional networks as separate entities. The recently developed
mathematical framework of multi-layer networks allows to perform an analysis of
the human brain where the structural and functional layers are considered
together. In this work we describe how to classify the subgraphs of a multiplex
network, and we extend motif analysis to networks with an arbitrary number of
layers. We then extract multi-layer motifs in brain networks of healthy
subjects by considering networks with two layers, anatomical and functional,
respectively obtained from diffusion and functional magnetic resonance imaging.
Results indicate that subgraphs in which the presence of a physical connection
between brain areas (links at the structural layer) coexists with a non-trivial
positive correlation in their activities are statistically overabundant.
Finally, we investigate the existence of a reinforcement mechanism between the
two layers by looking at how the probability to find a link in one layer
depends on the intensity of the connection in the other one. Showing that
functional connectivity is non-trivially constrained by the underlying
anatomical network, our work contributes to a better understanding of the
interplay between structure and function in the human brain.


title:
Adaptive PMU-based Distribution System State Estimation exploiting the
  Cloud-based IoT paradigm

abstract:
  This paper presents an adaptive Distribution System State Estimation (DSSE)
which relies on a Cloud-based IoT paradigm. The methodology is adaptive in
terms of the rate of execution of the estimation process which varies depending
on the indications of the distributed measurement system. The system is
composed, in particular, of Phasor Measurement Units (PMUs). PMUs are
virtualized with respect to the physical devices and the corresponding
virtualizing modules run in the communication network edge (i.e. closer to the
physical objects). PMUs are set at a higher measurement rate, while the
estimation process works at a given slower rate, for example once per second,
in normal operative conditions. A local decision algorithm implemented in the
virtualized module, monitors the measured quantities in order to detect and
address possible unexpected dynamics. In particular, different metrics can be
applied: the variations and the trend of variation of the rms voltage values,
but also the Rate Of Change Of Frequency (ROCOF) of the monitored signals can
be used to trigger rate variation in the DSSE.In case dynamics are detected,
the measurement data is sent to the DSSE at higher rates and the estimation
process runs consequently on a finer time scale. In the considered system only
application level entities are located in the Cloud, thus allowing to obtain a
bandwidth-efficient and smart data transmission. The results obtained on a
13-bus systems prove the goodness of the proposed methodologies.


title: Study of Beam Synchronization at JLEIC

abstract:
  The ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC)
accommodates a wide range of ion energies, from 20 to 100 GeV for protons or
from 8 to 40 GeV per nucleon for lead ions. In this medium energy range, ions
are not fully relativistic, which means values of their relativistic beta are
slightly below 1, leading to an energy dependence of revolution time of the
collider ring. On the other hand, electrons with energy 3 GeV and above are
already ultra-relativistic such that their speeds are effectively equal to the
speed of light. The difference in speeds of colliding electrons and ions in
JLEIC, when translated into a path-length difference necessary to maintain the
same timing between electron and ion bunches, is quite large. In this paper, we
explore schemes for synchronizing the electron and ion bunches at a collision
point as the ion energy is varied.


title:
A spectral-spatial fusion model for robust blood pulse waveform
  extraction in photoplethysmographic imaging

abstract:
  Photoplethysmographic imaging is a camera-based solution for non-contact
cardiovascular monitoring from a distance. This technology enables monitoring
in situations where contact-based devices may be problematic or infeasible,
such as ambulatory, sleep, and multi-individual monitoring. However, extracting
the blood pulse waveform signal is challenging due to the unknown mixture of
relevant (pulsatile) and irrelevant pixels in the scene. Here, we design and
implement a signal fusion framework, FusionPPG, for extracting a blood pulse
waveform signal with strong temporal fidelity from a scene without requiring
anatomical priors (e.g., facial tracking). The extraction problem is posed as a
Bayesian least squares fusion problem, and solved using a novel probabilistic
pulsatility model that incorporates both physiologically derived spectral and
spatial waveform priors to identify pulsatility characteristics in the scene.
Experimental results show statistically significantly improvements compared to
the FaceMeanPPG method ($p<0.001$) and DistancePPG ($p<0.001$) methods. Heart
rates predicted using FusionPPG correlated strongly with ground truth
measurements ($r^2=0.9952$). FusionPPG was the only method able to assess
cardiac arrhythmia via temporal analysis.


title:
A Tale of Two Fractals: The Hofstadter Butterfly and The Integral
  Apollonian Gaskets

abstract:
  This paper unveils a mapping between a quantum fractal that describes a
physical phenomena, and an abstract geometrical fractal. The quantum fractal is
the Hofstadter butterfly discovered in 1976 in an iconic condensed matter
problem of electrons moving in a two-dimensional lattice in a transverse
magnetic field. The geometric fractal is the integer Apollonian gasket
characterized in terms of a 300 BC problem of mutually tangent circles. Both of
these fractals are made up of integers. In the Hofstadter butterfly, these
integers encode the topological quantum numbers of quantum Hall conductivity.
In the Apollonian gaskets an infinite number of mutually tangent circles are
nested inside each other, where each circle has integer curvature. The mapping
between these two fractals reveals a hidden threefold symmetry embedded in the
kaleidoscopic images that describe the asymptotic scaling properties of the
butterfly. This paper also serves as a mini review of these fractals,
emphasizing their hierarchical aspects in terms of Farey fractions.


title:
Free-space spectro-temporal and spatio-temporal conversion for pulsed
  light

abstract:
  We present an apparatus that converts every pulse of a pulsed light source to
a pulse train in which the intensities of the different pulses are samples of
the spatial or temporal frequency spectrum of the original pulse. In this way,
the spectrum of the incident light can be measured by following the temporal
response of a single detector. The apparatus is based on multiple round-trips
inside a 2f- cavity-like mirror arrangement in which the spectrum is spread on
the back focal plane, where after each round-trip a small section of the
spectrum is allowed to escape. The apparatus is fibre-free, offers easy
wavelength range tunability, and a prototype built achieves over 10% average
efficiency in the near infra red. We demonstrate the application of the
prototype for the efficient measurement of the joint spectrum of a
non-degenerate bi-photon source in which one of the photons is in the near
infra red.


title: The Ricci flow with metric torsion on closed surfaces

abstract:
  The famous Uniformization Theorem states that on closed Riemannian surfaces
there always exists a metric of constant curvature for the Levi-Cevita
connection. In this article we prove that an analogue of the uniformization
theorem also holds for connections with metric torsion in the case of
non-positive Euler characteristic. Our main tool is an adapted form of the
Ricci flow.


title:
Exact Bethe ansatz spectrum of a tight-binding chain with dephasing
  noise

abstract:
  We construct an exact map between a tight-binding model on any bipartite
lattice in presence of dephasing noise and a Hubbard model with imaginary
interaction strength. In one dimension, the exact many-body Liouvillian
spectrum can be obtained by application of the Bethe ansatz method. We find
that both the non-equilibrium steady state and the leading decay modes
describing the relaxation at late times are related to the eta-pairing symmetry
of the Hubbard model. We show that there is a remarkable relation between the
time-evolution of an arbitrary k-point correlation function in the dissipative
system and k-particle states of the corresponding Hubbard model.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el nlin.SI


title:
Adapting censored regression methods to adjust for the limit of
  detection in the calibration of diagnostic rules for clinical mass
  spectrometry proteomic data

abstract:
  Despite the recent advances in mass spectrometry (MS), summarizing and
analyzing high-throughput mass-spectrometry data remains a challenging task.
This is, on the one hand, due to the complexity of the spectral signal which is
measured, and on the other, due to the limit of detection (LOD). The LOD is
related to the limitation of instruments in measuring markers at a relatively
low level. As a consequence, the outcome data set from the quantification step
of proteomic analysis often consists of a reduced list of peaks where any peak
intensities below the detection limit threshold are reported as missings. In
this work, we propose the use of censored data methodology to handle spectral
measurements within the presence of LOD, recognizing that those have been
censored due to left-censoring mechanisms on low-abundance proteins. We apply
this approach to the particular problem of calibrating prediction rules through
prior estimation of the average isotope expression in MALDI-FTICR
mass-spectrometry data, collected in the context of a pancreatic cancer
case-control study. Our idea is to replace the set of incomplete spectral
measurements with the average intensity estimates and use those as new input to
a prediction model. We evaluate the proposed methods, with respect to their
predictive ability, by comparing their performance with the one achieved using
the complete information as well as alternative/competitive methods to deal
with the LOD.


title: Internally heated convection beneath a poor conductor

abstract:
  We consider convection in an internally heated layer of fluid that is bounded
below by a perfect insulator and above by a poor conductor. The poorly
conducting boundary is modelled by a fixed heat flux. Using solely analytical
methods, we find linear and energy stability thresholds for the static state,
and we construct a lower bound on the mean temperature that applies to all
flows. The linear stability analysis yields a Rayleigh number above which the
static state is linearly unstable ($R_L$), and the energy analysis yields a
Rayleigh number below which it is globally stable ($R_E$). For various boundary
conditions on the velocity, exact expressions for $R_L$ and $R_E$ are found
using long-wavelength asymptotics. Each $R_E$ is strictly smaller than the
corresponding $R_L$ but is within 1%. The lower bound on the mean temperature
is proven for no-slip velocity boundary conditions using the background method.
The bound guarantees that the mean temperature of the fluid, relative to that
of the top boundary, grows with the heating rate ($H$) no slower than
$H^{2/3}$.


title: Multiple quantum wells for PT-symmetric phononic crystals

abstract:
  We demonstrate that the parity-time symmetry for sound is realized in the
laser-pumped multiple-quantum-well structure. Breaking of the parity-time
symmetry for the phonons with wave vectors corresponding to the Bragg condition
makes the structure a highly-selective acoustic wave amplifier. Single-mode
distributed feedback phonon lasing is predicted for structures with realistic
parameters.


title:
Iterated proportional fitting procedure and infinite products of
  stochastic matrices

abstract:
  The iterative proportional fitting procedure, introduced in 1937 by Kruithof,
aims to adjust the elements of an array to satisfy specified row and column
sums. Given a rectangular non-negative matrix $X_0$ and two positive marginals
$a$ and $b$, the algorithm generates a sequence of matrices $(X_n)$ starting at
$X_0$, supposed to converge to a biproportional fitting, that is, to a matrix
$Y$ whose marginals are $a$ and $b$ and of the form $Y=D_1X_0D_2$, for some
diagonal matrices $D_1$ and $D_2$ with positive diagonal entries.
  When a biproportional fitting does exist, it is unique and the sequence
$(X_n)$ converges to it at an at least geometric rate. More generally, when
there exists some matrix with marginal $a$ and $b$ and with support included in
the support of $X_0$, the sequence $(X_n)$ converges to the unique matrix whose
marginals are $a$ and $b$ and which can be written as a limit of matrices of
the form $D_1X_0D_2$. In the opposite case, the sequence $(X_n)$ diverges but
both subsequences $(X_{2n})$ and $(X_{2n+1})$ converge.
  In the present paper, we use a new method to prove again these results and
determine the two limit-points in the case of divergence. Our proof relies on a
new convergence theorem for backward infinite products $\cdots M_2M_1$ of
stochatic matrices $M_n$, with diagonal entries $M_n(i,i)$ bounded away from
$0$ and with bounded ratios $M_n(j,i)/M_n(i,j)$. This theorem generalizes
Lorenz' stabilization theorem.
  We also provide an alternative proof of Touric and Nedi\'c's theorem on
backward infinite products of doubly-stochatic matrices, with diagonal entries
bounded away from $0$. In both situations, we improve slightly the conclusion,
since we establish not only the convergence of the sequence $(M_n \cdots M_1)$,
but also its finite variation.


title:
How radiation affects superbubbles: Through momentum injection in early
  phase and photo-heating thereafter

abstract:
  Energetic winds and radiation from massive star clusters push the surrounding
gas and blow superbubbles in the interstellar medium (ISM). Using 1-D
hydrodynamic simulations, we study the role of radiation in the dynamics of
superbubbles driven by a young star cluster of mass $10^{6}$ M$_{\odot}$. We
have considered a realistic time evolution of the mechanical power as well as
radiation power of the star cluster, and detailed heating and cooling
processes. We find that the ratio of the radiation pressure on the shell
(shocked ISM) to the thermal pressure ($\sim10^{7}$ K) of the shocked wind
region is almost independent of the ambient density, and it is greater than
unity before $\lesssim 1$ Myr. We explore the parameter space of density and
dust opacity of the ambient medium, and find that the size of the hot gas
($\sim$ 10$^{7}$ K) cavity is insensitive to the dust opacity
($\sigma_{d}\approx(0.1-1.5)\times 10^{-21}$ cm$^{2}$), but the structure of
the photoionized ($\sim10^4$ K) gas depends on it. Most of the radiative losses
occur at $\sim10^{4}$ K, with sub-dominant losses at $\lesssim 10^3$ K and
$\sim10^{6}-10^{8}$ K. The superbubbles can retain as high as $\sim 10\%$ of
its input energy, for an ambient density of $10^{3}\,m{\rm_{H}\,cm^{-3}}$. We
discuss the role of ionization parameter and recombination-averaged density in
understanding the dominant feedback mechanism. Finally, we compare our results
with the observations of 30 Doradus.


title:
The Train Wreck Cluster Abell 520 and the Bullet Cluster 1E0657-558 in a
  Generalized Theory of Gravitation

abstract:
  A major hurdle for modified gravity theories is to explain the dynamics of
galaxy clusters. A case is made for a generalized gravitational theory called
Scalar-Tensor-Vector-Gravity (STVG) or MOG (modified gravity) to explain
merging cluster dynamics. The paper presents the results of a re-analysis of
the Bullet Cluster, as well as an analysis of the Train Wreck Cluster in the
weak gravitational field limit without dark matter. The King-$\beta$ model is
used to fit the X-ray data of both clusters, and the $\kappa$-maps are computed
using the parameters of this fit. The amount of galaxies in the clusters is
estimated by subtracting the predicted $\kappa$-map from the $\kappa$-map data.
The estimate for the Bullet Cluster is that $14.1\%$ of the cluster is composed
of galaxies. For the Train Wreck Cluster, if the Jee et al. data are used,
$25.7\%$ of the cluster is composed of galaxies. The baryon matter in the
galaxies and the enhanced strength of gravitation in MOG, shift the lensing
peaks making them offset from the gas. The work demonstrates that this
generalized gravitational theory can explain merging cluster dynamics without
dark matter.


title:
Estimating $r_{B}^{D\pi}$ as an input to the determination of the CKM
  angle $\gamma$

abstract:
  The interference between Cabibbo-favoured and Cabibbo-suppressed $B\to D\pi$
decay amplitudes provides sensitivity to the CKM angle $\gamma$. The relative
size of the interfering amplitudes is an important ingredient in the
determination of $\gamma$. Using branching fractions from various $B\to Dh$
decays, and the measured value for $r_{B}^{DK}$, the magnitude of the amplitude
ratio of $B^+\to D^0\pi^+$ and $B^+\to \bar{D}^0\pi^+$ decays is estimated to
be $r_{B}^{D\pi} = 0.0053 \pm 0.0007$.


title: On noncommutative equivariant bundles

abstract:
  We discuss a possible noncommutative generalization of the notion of an
equivariant vector bundle. Let $A$ be a $\mathbb{K}$-algebra, $M$ a left
$A$-module, $H$ a Hopf $\mathbb{K}$-algebra, $\delta:A\to H\otimes
A:=H\otimes_{\mathbb{K}} A$ an algebra coaction, and let $(H\otimes A)_\delta$
denote $H\otimes A$ with the right $A$-module structure induced by~$\delta$.
The usual definitions of an equivariant vector bundle naturally lead, in the
context of $\mathbb{K}$-algebras, to an $(H\otimes A)$-module homomorphism
\[\Theta:H\otimes M\to (H\otimes A)_\delta\otimes_AM\] that fulfills some
appropriate conditions. On the other hand, sometimes an $(A,H)$-Hopf module is
considered instead, for the same purpose. When $\Theta$ is invertible, as is
always the case when $H$ is commutative, the two descriptions are equivalent.
We point out that the two notions differ in general, by giving an example of a
noncommutative Hopf algebra $H$ for which there exists such a $\Theta$ that is
not invertible and a left-right $(A,H)$-Hopf module whose corresponding
homomorphism $M\otimes H\to (A\otimes H)_\delta\otimes_AM$ is not an
isomorphism.


title: An uplink-downlink duality for cloud radio access network

abstract:
  Uplink-downlink duality refers to the fact that the Gaussian broadcast
channel has the same capacity region as the dual Gaussian multiple-access
channel under the same sumpower constraint. This paper investigates a similar
duality relationship between the uplink and downlink of a cloud radio access
network (C-RAN), where a central processor (CP) cooperatively serves multiple
mobile users through multiple remote radio heads (RRHs) connected to the CP
with finite-capacity fronthaul links. The uplink of such a C-RAN model
corresponds to a multipleaccess relay channel; the downlink corresponds to a
broadcast relay channel. This paper considers compression-based relay
strategies in both uplink and downlink C-RAN, where the quantization noise
levels are functions of the fronthaul link capacities. If the fronthaul
capacities are infinite, the conventional uplinkdownlink duality applies. The
main result of this paper is that even when the fronthaul capacities are
finite, duality continues to hold for the case where independent compression is
applied across each RRH in the sense that when the transmission and compression
designs are jointly optimized, the achievable rate regions of the uplink and
downlink remain identical under the same sum-power and individual fronthaul
capacity constraints. As an application of the duality result, the power
minimization problem in downlink C-RAN can be efficiently solved based on its
uplink counterpart.


title: Narayana, Mandelbrot, and A New Kind of Companion Matrix

abstract:
  We demonstrate a new kind of companion matrix, for polynomials of the form
$c(\lambda) = \lambda a(\lambda)b(\lambda) + c_0$ where upper Hessenberg
companions are known for the polynomials $a(\lambda)$ and $b(\lambda)$. This
construction can generate companion matrices with smaller entries than the
Fiedler or Frobenius forms. This generalizes Piers Lawrence's Mandelbrot
companion matrix. We motivate the construction by use of Narayana-Mandelbrot
polynomials, which are also new to this paper.


title:
'Perfectly' curvilinear profiles for binding as determined by ITC may in
  fact be multiphasic

abstract:
  In a structural analysis of the proteasome activator PafE in Mycobacterium
tuberculosis, the binding of the activator or shorter constructs to the 20S
proteasome core particle (20S CP) or derivatives was measured by isothermal
titration calorimetry (Bai et al. Proc Natl Acad Sci USA 113: E1983-E1992.
2016). The data were fitted by the authors by nonlinear least squares to give
curvilinear profiles that, at least in part, appear to fit the data very well.
However, reanalysis of the data shows that the profiles are much better (P <
0.001) represented as multiphasic, i.e. by a series of straight lines separated
by discontinuous transitions, often in the form jumps, than by the conventional
curvilinear profiles.


title:
Probing quantum vacuum fluctuations over a charged particle near a
  reflecting wall

abstract:
  We investigate the influence of the vacuum fluctuations of a background
electric field over a charged test particle in the presence of a perfectly
reflecting flat wall. A switching function connecting different stages of the
system is implemented in such a way that its functional dependence is
determined by the ratio between the measuring time and the switching duration.
The dispersions of the velocity components of the particle are found to be
smooth functions of time, and have maximum magnitudes for a measuring time
corresponding to about one round trip of a light signal between the particle
and the wall. Typical divergences reported in the literature and linked with an
oversimplification in modeling this system are naturally regularized in our
approach. Estimates suggest that this sort of manifestation of quantum vacuum
fluctuations over the motion of the particle could be tested in laboratories.


title:
Optimal Zero Delay Coding of Markov Sources: Stationary and Finite
  Memory Codes

abstract:
  The optimal zero delay coding of a finite state Markov source is considered.
The existence and structure of optimal codes are studied using a stochastic
control formulation. Prior results in the literature established the optimality
of deterministic Markov (Walrand-Varaiya type) coding policies for finite time
horizon problem, and the optimality of both deterministic nonstationary and
randomized stationary policies for the infinite time horizon problem. Our main
result here shows that for any irreducible and aperiodic Markov source with a
finite alphabet, \emph{deterministic and stationary} Markov coding policies are
optimal for the infinite horizon problem. In addition, the finite blocklength
(time horizon) performance on an optimal (stationary and Markov) coding policy
is shown to approach the infinite time horizon optimum at a rate $O(1/T)$. The
results are extended to systems where zero delay communication takes place
across a noisy channel with noiseless feedback.


title: Routing Memento Requests Using Binary Classifiers

abstract:
  The Memento protocol provides a uniform approach to query individual web
archives. Soon after its emergence, Memento Aggregator infrastructure was
introduced that supports querying across multiple archives simultaneously. An
Aggregator generates a response by issuing the respective Memento request
against each of the distributed archives it covers. As the number of archives
grows, it becomes increasingly challenging to deliver aggregate responses while
keeping response times and computational costs under control. Ad-hoc heuristic
approaches have been introduced to address this challenge and research has been
conducted aimed at optimizing query routing based on archive profiles. In this
paper, we explore the use of binary, archive-specific classifiers generated on
the basis of the content cached by an Aggregator, to determine whether or not
to query an archive for a given URI. Our results turn out to be readily
applicable and can help to significantly decrease both the number of requests
and the overall response times without compromising on recall. We find, among
others, that classifiers can reduce the average number of requests by 77%
compared to a brute force approach on all archives, and the overall response
time by 42% while maintaining a recall of 0.847.


title:
Control-Data Separation across Edge and Cloud for Uplink Communications
  in C-RAN

abstract:
  Fronthaul limitations in terms of capacity and latency motivate the growing
interest in the wireless industry for the study of alternative functional
splits between cloud and edge nodes in Cloud Radio Access Network (C-RAN). This
work contributes to this line of work by investigating the optimal functional
split of control and data plane functionalities at the edge nodes and at the
Remote Cloud Center (RCC) as a function of the fronthaul latency. The model
under study consists of a two-user time-varying uplink channel in which the RCC
has global but delayed channel state information (CSI) due to fronthaul
latency, while edge nodes have local but timely CSI. Adopting the adaptive
sum-rate as the performance criterion, functional splits whereby the control
functionality of rate selection and the decoding of the data-plane frames are
carried out at either the edge nodes or at the RCC are compared through
analysis and numerical results.


title:
Classical formulae on projective surfaces and $3$-folds with ordinary
  singularities, revisited

abstract:
  As an application of universal polynomials for local and multi-singularities
of maps, we revisit classical enumerative formulae of Salmon-Cayley-Zeuthen for
projective surfaces and analogous formulae of Segre-(B.)Severi-Roth for
projective $3$-folds. In particular, several examples of actual computation are
given using universal polynomials for computing weighted Euler characteristics
of singularity loci.


title: Post-Newtonian celestial mechanics in scalar-tensor cosmology

abstract:
  Applying the recently developed dynamical perturbation formalism on
cosmological background to scalar-tensor theory, we provide a solid theoretical
basis and a rigorous justification for phenomenological models of orbital
dynamics that are currently used to interpret experimental measurements of the
time-dependent gravitational constant. We derive the field equations for the
scalar-tensor perturbations and study their gauge freedom associated with the
cosmological expansion. We find a new gauge eliminating a prohibitive number of
gauge modes in the field equations and significantly simplifying post-Newtonian
equations of motion for localized astronomical systems in the universe with
time-dependent gravitational constant. We identify several new post-Newtonian
terms and calculate their effect on secular cosmological evolution of the
osculating orbital elements.


title: Algebraic foundations for qualitative calculi and networks

abstract:
  A qualitative representation $\phi$ is like an ordinary representation of a
relation algebra, but instead of requiring $(a; b)^\phi = a^\phi | b^\phi$, as
we do for ordinary representations, we only require that $c^\phi\supseteq
a^\phi | b^\phi \iff c\geq a ; b$, for each $c$ in the algebra. A constraint
network is qualitatively satisfiable if its nodes can be mapped to elements of
a qualitative representation, preserving the constraints. If a constraint
network is satisfiable then it is clearly qualitatively satisfiable, but the
converse can fail. However, for a wide range of relation algebras including the
point algebra, the Allen Interval Algebra, RCC8 and many others, a network is
satisfiable if and only if it is qualitatively satisfiable.
  Unlike ordinary composition, the weak composition arising from qualitative
representations need not be associative, so we can generalise by considering
network satisfaction problems over non-associative algebras. We prove that
computationally, qualitative representations have many advantages over ordinary
representations: whereas many finite relation algebras have only infinite
representations, every finite qualitatively representable algebra has a finite
qualitative representation; the representability problem for (the atom
structures of) finite non-associative algebras is NP-complete; the network
satisfaction problem over a finite qualitatively representable algebra is
always in NP; the validity of equations over qualitative representations is
co-NP-complete. On the other hand we prove that there is no finite
axiomatisation of the class of qualitatively representable algebras.


title:
Linear Superposition of Minimal Surfaces: Generalized Helicoids and
  Minimal Cones

abstract:
  Observing a linear superposition principle, a family of new minimal
hypersurfaces in Euclidean space is found, as well as that linear combinations
of generalized helicoids induce new algebraic minimal cones of arbitrarily high
degree.


title: Hitting times distribution and extreme value law for flows

abstract:
  For flows whose return map on a cross section has sufficient mixing property,
we show that the hitting time distribution of the flow to balls is exponential
in limit. We also establish a link between the extreme value distribution of
the flow and its hitting time distribution, generalizing a previous work by
Freitas et al. in the discrete time case. Finally we show that for maps that
can be modeled by Young`s tower with polynomial tail, the extreme value law
holds.


title:
A Beurling Theorem for Generalized Hardy Spaces on a Multiply Connected
  Domain

abstract:
  The object of this paper is to prove a version of the
Beurling-Helson-Lowdenslager invariant subspace theorem for operators on
certain Banach spaces of functions on a multiply connected domain in the
complex plane. The norms for these spaces are either the usual Lebesgue and
Hardy space norms or certain continuous gauge norms. In the Hardy space case
the expected corollaries include the characterization of the cyclic vectors as
the outer functions in this context, a demonstration that the set of analytic
multiplication operators is maximal abelian and reflexive, and a determination
of the closed operators that commute with all analytic multiplication
operators.


title: A note on the differential operator on generalized Fock spaces

abstract:
  It has long been known that the differential operator $D$ represents a
typical examples of unbounded operators in many Banach spaces including the
classical Fock spaces, the Fock--Sobolev spaces, and the generalized Fock
spaces where the weight decays faster than the Gaussian weight. In this note we
identify Fock type spaces where the operator admits some basic spectral
structures including compactness and membership in the Schatten $\mathcal{S}_p$
classes. We also showed that its nontrivial spectrum while acting on such
spaces is precisely the closed unit disk $\D$ in the complex plane.


title: Chern-Moser-Weyl Tensor and Embeddings into Hyperquadrics

abstract:
  The first part of the article surveys some work on the Chern-Moser-Weyl
tensor and its application in the embeddability problem into hyperquadrics. In
the last section, we give a negative answer to a folklore conjecture concerning
the embeddability of compact, strongly pseudoconvex, real algebraic
hypersurfaces into a sphere of sufficiently high dimension.


title: Physical background for parameters of the quantum Rabi model

abstract:
  We investigate the applicability of the two major approximations which are
most commonly employed in the study of the quantum Rabi model, namely the
description of a resonant cavity mode as a single-mode quantized field and the
use of the rotating wave approximation. Starting from the Hamiltonian of a
two-level system interacting with a multi-mode quantized field, we perform the
canonical transformation of the field operators. This allows one to partition
the Hamiltonian of the system into two parts. The first part is the interaction
of the two-level system with a single collective field mode, while the second
one describes the interaction with field fluctuations. The first part is
usually associated with the resonant cavity mode. This division enables us to
determine the applicability condition of the single-mode approximation. In
addition we identify simple approximate relations for the description of the
eigenstates, eigenfunctions and the time evolution of the quantum Rabi model
beyond the rotating wave approximation.


title:
Thom polynomials in $\mathcal{A}$-classification I: counting singular
  projections of a surface

abstract:
  We study universal polynomials of characteristic classes associated to the
$\mathcal{A}$-classification (i.e. up to right-left equivalence) of holomorphic
map-germs $(\mathbb{C}^2,0) \to (\mathbb{C}^n, 0)$ $(n=2,3)$. That enables us
to systematically treat with classical enumerative problems of lines of
prescribed contact with a given projective surface in $3$ and $4$-spaces.


title: Preparational Uncertainty Relations for $N$ Continuous Variables

abstract:
  A smooth function of the second moments of $N$ continuous variables gives
rise to an uncertainty relation if it is bounded from below. We present a
method to systematically derive such bounds by generalizing an approach applied
previously to a single continuous variable. New uncertainty relations are
obtained for multi-partite systems which allow one to distinguish entangled
from separable states. We also investigate the geometry of the "uncertainty
region" in the $N(2N+1)$-dimensional space of moments. It is shown to be a
convex set for any number continuous variables, and the points on its boundary
found to be in one-to-one correspondence with pure Gaussian states of minimal
uncertainty. For a single degree of freedom, the boundary can be visualized as
one sheet of a "Lorentz-invariant" hyperboloid in the three-dimensional pace of
second moments.


title:
Activity indicators and stellar parameters of the Kepler targets. An
  application of the ROTFIT pipeline to LAMOST-Kepler stellar spectra

abstract:
  The LAMOST-Kepler survey, whose spectra are analyzed in the present paper, is
the first large spectroscopic project aimed at characterizing these sources.
Our work is focused at selecting emission-line objects and chromospherically
active stars and on the evaluation of the atmospheric parameters. We have used
a version of the code ROTFIT that exploits a wide and homogeneous collection of
real star spectra, i.e. the Indo US library. We provide a catalog with the
atmospheric parameters (Teff, logg, [Fe/H]), the radial velocity (RV) and an
estimate of the projected rotation velocity (vsini). For cool stars (Teff<6000
K) we have also calculated the H-alpha and CaII-IRT chromospheric fluxes. We
have derived the RV and the atmospheric parameters for 61,753 spectra of 51,385
stars. Literature data for a few hundred stars have been used to do a quality
control of our results. The final accuracy of RV, Teff, logg, and [Fe/H]
measurements is about 14 km/s, 3.5%, 0.3 dex, and 0.2 dex, respectively.
However, while the Teff values are in very good agreement with the literature,
we noted some issues with the determination of [Fe/H] of metal poor stars and
the tendency, for logg, to cluster around the values typical for main sequence
and red giant stars. We propose correction relations based on these comparison.
The RV distribution is asymmetric and shows an excess of stars with negative
RVs which is larger at low metallicities. We could identify stars with variable
RV, ultrafast rotators, and emission-line objects. Based on the H-alpha and
CaII-IRT fluxes, we have found 442 chromospherically active stars, one of which
is a likely accreting object. The availability of precise rotation periods from
the Kepler photometry has allowed us to study the dependency of the
chromospheric fluxes on the rotation rate for a quite large sample of field
stars.


title:
Search for supersymmetry in a final state containing two photons and
  missing transverse momentum in $\sqrt{s}$ = 13 TeV $pp$ collisions at the LHC
  using the ATLAS detector

abstract:
  A search has been made for supersymmetry in a final state containing two
photons and missing transverse momentum using the ATLAS detector at the Large
Hadron Collider. The search makes use of 3.2 fb$^{-1}$ of proton-proton
collision data collected at a centre-of-mass energy of 13 TeV in 2015. Using a
combination of data-driven and Monte-Carlo-based approaches, the Standard Model
background is estimated to be $0.27^{+0.22}_{-0.10}$ events. No events are
observed in the signal region; considering the expected background and its
uncertainty, this observation implies a model-independent 95% CL upper limit of
0.93 fb (3.0 events) on the visible cross section due to physics beyond the
Standard Model. In the context of a generalized model of gauge-mediated
supersymmetry breaking with a bino-like next-to-lightest supersymmetric
particle, this leads to a lower limit of 1650 GeV on the mass of a degenerate
octet of gluino states, independent of the mass of the lighter bino-like
neutralino.


title: Revised Thomas-Fermi Approximation for Singular Potentials

abstract:
  Approximations to the many-fermion free energy density functional that
include the Thomas-Fermi (TF) form for the non-interacting part lead to
singular densities for singular external potentials (e.g. attractive Coulomb).
This limitation of the TF approximation is addressed here by a formal map of
the exact Euler equation for the density onto an equivalent TF form
characterized by a modified Kohn-Sham potential. It is shown to be a
"regularized" version of the Kohn-Sham potential, tempered by convolution with
a finite-temperature response function. The resulting density is non-singular,
with the equilibrium properties obtained from the total free energy functional
evaluated at this density. This new representation is formally exact.
Approximate expressions for the regularized potential are given to leading
order in a non-locality parameter and the limiting behavior at high and low
temperatures is described. The non-interacting part of the free energy in this
approximation is the usual Thomas-Fermi functional. These results generalize
and extend to finite temperatures the ground-state regularization by Parr and
Ghosh (Proc. Nat. Acad. Sci. 83, 3577 (1986)) and by Pratt, Hoffman, and Harris
(J. Chem. Phys. 92, 1818 (1988)) and formally systematize the
finite-temperature regularization given by the latter authors.


title:
Actor-critic versus direct policy search: a comparison based on sample
  complexity

abstract:
  Sample efficiency is a critical property when optimizing policy parameters
for the controller of a robot. In this paper, we evaluate two state-of-the-art
policy optimization algorithms. One is a recent deep reinforcement learning
method based on an actor-critic algorithm, Deep Deterministic Policy Gradient
(DDPG), that has been shown to perform well on various control benchmarks. The
other one is a direct policy search method, Covariance Matrix Adaptation
Evolution Strategy (CMA-ES), a black-box optimization method that is widely
used for robot learning. The algorithms are evaluated on a continuous version
of the mountain car benchmark problem, so as to compare their sample
complexity. From a preliminary analysis, we expect DDPG to be more sample
efficient than CMA-ES, which is confirmed by our experimental results.


title:
QCD Phase-transition and chemical freezeout in nonzero magnetic field at
  NICA

abstract:
  Because of relativistic off-center motion of the charged spectators and the
local momentum-imbalance experienced by the participants, a huge magnetic field
is likely generated in high-energy collisions. The influence of such
short-lived magnetic field on the QCD phase-transition(s) shall be analysed.
From Polyakov linear-sigma model, we study the chiral phase-transition and the
magnetic response and susceptibility in dependence on temperature, density and
magnetic field strength. The systematic measurements of the phase-transition
characterizing signals, such as the fluctuations, the dynamical correlations
and the in-medium modifications of rho-meson, for instance, in different
interacting systems and collision centralities are conjectured to reveal an
almost complete description for the QCD phase-structure and the chemical
freezeout. We limit the discussion to NICA energies.


title: Exeptional set estimates for the Hausdorff dimension of intersections

abstract:
  For Borel subsets A and B of the Euclidean n-space the intersection of A with
generic rotations and translations of B has often Hausdorff dimension at least
dim A + dim B - n. Estimates for the exceptional set of rotations are derived.


title:
Accelerated first-order primal-dual proximal methods for linearly
  constrained composite convex programming

abstract:
  Motivated by big data applications, first-order methods have been extremely
popular in recent years. However, naive gradient methods generally converge
slowly. Hence, much efforts have been made to accelerate various first-order
methods. This paper proposes two accelerated methods towards solving structured
linearly constrained convex programming, for which we assume composite convex
objective.
  The first method is the accelerated linearized augmented Lagrangian method
(LALM). At each update to the primal variable, it allows linearization to the
differentiable function and also the augmented term, and thus it enables easy
subproblems. Assuming merely weak convexity, we show that LALM owns $O(1/t)$
convergence if parameters are kept fixed during all the iterations and can be
accelerated to $O(1/t^2)$ if the parameters are adapted, where $t$ is the
number of total iterations.
  The second method is the accelerated linearized alternating direction method
of multipliers (LADMM). In addition to the composite convexity, it further
assumes two-block structure on the objective. Different from classic ADMM, our
method allows linearization to the objective and also augmented term to make
the update simple. Assuming strong convexity on one block variable, we show
that LADMM also enjoys $O(1/t^2)$ convergence with adaptive parameters. This
result is a significant improvement over that in [Goldstein et. al, SIIMS'14],
which requires strong convexity on both block variables and no linearization to
the objective or augmented term.
  Numerical experiments are performed on quadratic programming, image
denoising, and support vector machine. The proposed accelerated methods are
compared to nonaccelerated ones and also existing accelerated methods. The
results demonstrate the validness of acceleration and superior performance of
the proposed methods over existing ones.


title: Convergence rates for upwind schemes with rough coefficients

abstract:
  This paper is concerned with the numerical analysis of the explicit upwind
finite volume scheme for numerically solving continuity equations. We are
interested in the case where the advecting velocity field has spatial Sobolev
regularity and initial data are merely integrable. We estimate the error
between approximate solutions constructed by the upwind scheme and
distributional solutions of the continuous problem in a Kantorovich-Rubinstein
distance, which was recently used for stability estimates for the continuity
equation by Seis [23]. Restricted to Cartesian meshes, our estimate shows that
the rate of weak convergence is at least of order $1/2$ in the mesh size. The
proof relies on a probabilistic interpretation of the upwind scheme Delarue and
Lagouti\`ere [9]. We complement the weak convergence result with an example
that illustrates that for rough initial data no rates can be expected in strong
norms. The same example suggests that the weak order $1/2$ rate is optimal.


title:
Spectroscopy of the neutron-rich hypernucleus $^{7}_{\Lambda}$He from
  electron scattering

abstract:
  The missing mass spectroscopy of the $^{7}_{\Lambda}$He hypernucleus was
performed, using the $^{7}$Li$(e,e^{\prime}K^{+})^{7}_{\Lambda}$He reaction at
the Thomas Jefferson National Accelerator Facility Hall C. The $\Lambda$
binding energy of the ground state (1/2$^{+}$) was determined with a smaller
error than that of the previous measurement, being $B_{\Lambda}$ = 5.55 $\pm$
0.10(stat.) $\pm$ 0.11(sys.) MeV. The experiment also provided new insight into
charge symmetry breaking in p-shell hypernuclear systems. Finally, a peak at
$B_{\Lambda}$ = 3.65 $\pm$ 0.20(stat.) $\pm$ 0.11(sys.) MeV was observed and
assigned as a mixture of 3/2$^{+}$ and 5/2$^{+}$ states, confirming the
"gluelike" behavior of $\Lambda$, which makes an unstable state in $^{6}$He
stable against neutron emission.


title:
Partial sum of matrix entries of representations of the symmetric group
  and its asymptotics

abstract:
  Many aspects of the asymptotics of Plancherel distributed partitions have
been studied in the past fifty years, in particular the limit shape, the
distribution of the longest rows, connections with random matrix theory and
characters of the representation matrices of the symmetric group. Regarding the
latter, we expand a celebrated result of Kerov on the asymptotic of Plancherel
distributed characters by studying partial trace and partial sum of a
representation matrix. We decompose these objects into a main term and a
reminder, proving a central limit theorem for both main terms and a law of
large numbers for the partial sum itself. Our main tool is the expansion of
symmetric functions evaluated on Jucys-Murphy elements.


title:
Small optic suspensions for Advanced LIGO input optics and other
  precision optical experiments

abstract:
  We report on the design and performance of small optic suspensions developed
to suppress seismic motion of out-of-cavity optics in the Input Optics
subsystem of the Advanced LIGO interferometric gravitational wave detector.
These compact single stage suspensions provide isolation in all six degrees of
freedom of the optic, local sensing and actuation in three of them, and passive
damping for the other three.


title:
Simple solutions of fireball hydrodynamics for rotating and expanding
  triaxial ellipsoids and final state observables

abstract:
  We present a class of analytic solutions of non-relativistic fireball
hydrodynamics for a fairly general class of equation of state. The presented
solution describes the expansion of a triaxial ellipsoid that rotates around
one of the principal axes. We calculate the hadronic final state observables
such as single-particle spectra, directed, elliptic and third flows, as well as
HBT correlations and corresponding radius parameters, utilizing simple analytic
formulas. We call attention to the fact that the final tilt angle of the
fireball, an important observable quantity, is not independent on the exact
definition of it: one gets different angles from the single-particle spectra
and from HBT measurements. Taken together, it is pointed out that these
observables may be sufficient for the determination of the magnitude of the
rotation of the fireball. We argue that observing this rotation and its
dependence on collision energy would reveal the softness of the equation of
state. Thus determining the rotation may be a powerful tool for the
experimental search for the critical point in the phase diagram of strongly
interacting matter.


title:
Interaction-Induced Topological and Magnetic Phases in the
  Hofstadter-Hubbard Model

abstract:
  Interaction effects have been a subject of contemporary interest in
topological phases of matter. But in the presence of interactions, the accurate
determination of topological invariants in their general form is difficult due
to their dependence on multiple integrals containing Green's functions and
their derivatives. Here we employ the recently proposed "effective topological
Hamiltonian" approach to explore interaction-induced topological phases in the
time-reversal-invariant Hofstadter-Hubbard model. Within this approach, the
zero-frequency part of the self-energy is sufficient to determine the correct
topological invariant. We combine the topological Hamiltonian approach with the
local self-energy approximation, both for the static and the full dynamical
self-energy evaluated using dynamical mean field theory (DMFT), and present the
resulting phase diagram in the presence of many-body interactions. We
investigate the emergence of quantum spin Hall (QSH) states for different
interaction strengths by calculating the $\mathbb{Z}_2$ invariant. The
interplay of strong correlations and a staggered potential also induces
magnetic long-range order with an associated first order transition. We present
results for the staggered magnetization ( $m_s$ ), staggered occupancy ( $n_s$
), and double occupancy across the transition.


title: Correlation function of four spins in the percolation model

abstract:
  By using the Coulomb gas technics we calculate the four-spin correlation
function in the percolation $q\rightarrow 1$ limit of the Potts model.
  It is known that the four-point functions define the actual fusion rules of a
particular model. In this respect, we find that fusion of two spins, of
dimension $\Delta_{\sigma}=\frac{5}{96}$, produce a new channel, in the 4-point
function, which is due to the operator with dimension $\Delta=5/8$.


title:
Optimising The Input Window Alignment in CD-DNN Based Phoneme
  Recognition for Low Latency Processing

abstract:
  We present a systematic analysis on the performance of a phonetic recogniser
when the window of input features is not symmetric with respect to the current
frame. The recogniser is based on Context Dependent Deep Neural Networks
(CD-DNNs) and Hidden Markov Models (HMMs). The objective is to reduce the
latency of the system by reducing the number of future feature frames required
to estimate the current output. Our tests performed on the TIMIT database show
that the performance does not degrade when the input window is shifted up to 5
frames in the past compared to common practice (no future frame). This
corresponds to improving the latency by 50 ms in our settings. Our tests also
show that the best results are not obtained with the symmetric window commonly
employed, but with an asymmetric window with eight past and two future context
frames, although this observation should be confirmed on other data sets. The
reduction in latency suggested by our results is critical for specific
applications such as real-time lip synchronisation for tele-presence, but may
also be beneficial in general applications to improve the lag in human-machine
spoken interaction.


title:
Number Fields in Fibers: the Geometrically Abelian Case with Rational
  Critical Values

abstract:
  Let X be an algebraic curve over Q and t a non-constant Q-rational function
on X such that Q(t) is a proper subfield of Q(X). For every integer n pick a
point P_n on X such that t(P_n)=n. We conjecture that, for large N, among the
number fields Q(P_1), ..., Q(P_N) there are at least cN distinct. We prove this
conjecture in the special case when t defines a geometrically abelian covering
of the projective line, and the critical values of t are all rational. This
implies, in particular, that our conjecture follows from a famous conjecture of
Schinzel.


title:
The Cayley Trick for Tropical Hypersurfaces With a View Toward Ricardian
  Economics

abstract:
  The purpose of this survey is to summarize known results about tropical
hypersurfaces and the Cayley Trick from polyhedral geometry. This allows for a
systematic study of arrangements of tropical hypersurfaces and, in particular,
arrangements of tropical hyperplanes. A recent application to the Ricardian
theory of trade from econometrics is explored.


title: Ricci solitons on low-dimensional generalized symmetric spaces

abstract:
  We consider three- and four-dimensional pseudo-Riemannian generalized
symmetric spaces, whose invariant metrics were explicitly described in [15].
While four-dimensional pseudo-Riemannian generalized symmetric spaces of types
A, C and D are algebraic Ricci solitons, the ones of type B are not so. The
Ricci soliton equation for their metrics yields a system of partial
differential equations. Solving such system, we prove that almost all the
four-dimensional pseudo-Riemannian generalized symmetric spaces of type B are
Ricci solitons. These examples show some deep differences arising for the Ricci
soliton equation between the Riemannian and the pseudo-Riemannian cases, as any
homogeneous Riemannian Ricci soliton is algebraic [21]. We also investigate
three-dimensional generalized symmetric spaces of any signature and prove that
they are Ricci solitons.


title: Statistics of fully turbulent impinging jets

abstract:
  Direct numerical simulations of sub- and supersonic impinging jets with
Reynolds numbers of 3300 and 8000 are carried out to analyse their statistical
properties. The influence of the parameters Mach number, Reynolds number and
ambient temperature on the mean velocity and temperature fields are studied.
For the compressible subsonic cold impinging jets into a heated environment,
different Reynolds analogies are assesses. It is shown, that the (original)
Reynolds analogy as well as the Chilton Colburn analogy are in good agreement
with the DNS data outside the impinging area. The generalised Reynolds analogy
(GRA) and the Crocco-Busemann relation are not suited for the estimation of the
mean temperature field based on the mean velocity field of impinging jets.
Furthermore, the prediction of fluctuating temperatures according to the GRA
fails. On the contrary, the linear relation between thermodynamic fluctuations
of entropy, density and temperature as suggested by Lechner et al. (2001) can
be confirmed for the entire wall jet. The turbulent heat flux and Reynolds
stress tensor are analysed and brought into coherence with the primary and
secondary ring vortices of the wall jet. Budget terms of the Reynolds stress
tensor are given as data base for the improvement of turbulence models.


title: Heat content for convolution semigroups

abstract:
  Let $\mathbf{X}=\{X_t\}_{t\geq 0}$ be a L\'evy process in $\mathbb{R}^d$ and
$\Omega$ be an open subset of $\mathbb{R}^d$ with finite Lebesgue measure. In
this article we consider the quantity $H (t) = \int_{\Omega}\mathbb{P}_{x}
(X_t\in \Omega ^c) dx$ which is called the heat content. We study its
asymptotic behaviour as $t$ goes to zero for isotropic L\'evy processes under
some mild assumptions on the characteristic exponent. We also treat the class
of L\'evy processes with finite variation in full generality.


title: New Algebraic Properties of Middle Bol Loops

abstract:
  A loop $(Q,\cdot,\backslash,/)$ is called a middle Bol loop if it obeys the
identity $x(yz\backslash x)=(x/z)(y\backslash x)$. In this paper, some new
algebraic properties of a middle Bol loop are established. Four bi-variate
mappings $f_i,g_i,~i=1,2$ and four $j$-variate mappings
$\alpha_j,\beta_j,\phi_j,\psi_j,~j\in\mathbb{N}$ are introduced and some
interesting properties of the former are found. Neccessary and sufficient
conditons in terms of $f_i,g_i,~i=1,2$, for a middle Bol loop to have the
elasticity property, RIP, LIP, right alternative property (RAP) and left
alternative property (LAP) are establsihed. Also, neccessary and sufficient
conditons in terms of $\alpha_j,\beta_j,\phi_j,\psi_j,~j\in\mathbb{N}$, for a
middle Bol loop to have power RAP and power LAP are establsihed. Neccessary and
sufficient conditons in terms of $f_i,g_i,~i=1,2$ and
$\alpha_j,\beta_j,\phi_j,\psi_j,~j\in\mathbb{N}$, for a middle Bol loop to be a
group, Moufang loop or extra loop are established. A middle Bol loop is shown
to belong to some classes of loops whose identiites are of the J.D. Phillips'
RIF-loop and WRIF-loop (generalizations of Moufang and Steiner loops) and WIP
power associative conjugacy closed loop types if and only if some identities
defined by $g_1$ and $g_2$ are obeyed.


title:
Gradient methods for variational optimization of projected
  entangled-pair states

abstract:
  We present a conjugate-gradient method for the ground-state optimization of
projected entangled-pair states (PEPS) in the thermodynamic limit, as a direct
implementation of the variational principle within the PEPS manifold. Our
optimization is based on an efficient and accurate evaluation of the gradient
of the global energy functional by using effective corner environments, and is
robust with respect to the initial starting points. It has the additional
advantage that physical and virtual symmetries can be straightforwardly
implemented. We provide the tools to compute static structure factors directly
in momentum space, as well as the variance of the Hamiltonian. We benchmark our
method on Ising and Heisenberg models, and show a significant improvement on
the energies and order parameters as compared to algorithms based on
imaginary-time evolution.


title:
The dynamics of a spinning particle in a linear in spin Hamiltonian
  approximation

abstract:
  We investigate for order and chaos the dynamical system of a spinning test
particle of mass $m$ moving in the spacetime background of a Kerr black hole of
mass M. This system is approximated in our investigation by the linear in spin
Hamiltonian function provided in [E. Barausse, and A. Buonanno, Phys.Rev. D 81,
084024 (2010)]. We study the corresponding phase space by using 2D projections
on a surface of section and the method of color and rotation on a 4D Poincar\'e
section. Various topological structures coming from the non-integrability of
the linear in spin Hamiltonian are found and discussed. Moreover, an
interesting result is that from the value of the dimensionless spin $S/(m
M)=10^{-4}$ of the particle and below, the impact of the non-integrability of
the system on the motion of the particle seems to be negligible.


title:
Lightning climatology of exoplanets and brown dwarfs guided by Solar
  System data

abstract:
  Clouds form on extrasolar planets and brown dwarfs where lightning could
occur. Lightning is a tracer of atmospheric convection, cloud formation and
ionization processes as known from the Solar System, and may be significant for
the formation of prebiotic molecules. We study lightning climatology for the
different atmospheric environments of Earth, Venus, Jupiter and Saturn. We
present lightning distribution maps for Earth, Jupiter and Saturn, and flash
densities for these planets and Venus, based on optical and/or radio
measurements from the WWLLN and STARNET radio networks, the LIS/OTD satellite
instruments, the Galileo, Cassini, New Horizons and Venus Express spacecraft.
We also present flash densities calculated for several phases of two volcano
eruptions, Eyjafjallaj\"okull's (2010) and Mt Redoubt's (2009). We estimate
lightning rates for sample, transiting and directly imaged extrasolar planets
and brown dwarfs. Based on the large variety of exoplanets, six categories are
suggested for which we use the lightning occurrence information from the Solar
System. We examine lightning energy distributions for Earth, Jupiter and
Saturn. We discuss how strong stellar activity may support lightning activity.
We provide a lower limit of the total number of flashes that might occur on
transiting planets during their full transit as input for future studies. We
find that volcanically very active planets might show the largest lightning
flash densities. When applying flash densities of the large Saturnian storm
from 2010/11, we find that the exoplanet HD 189733b would produce high
lightning occurrence even during its short transit.

categories: astro-ph.EP astro-ph.SR physics.ao-ph physics.geo-ph


title:
Approximation methods for the calculation of eigenvalues in ODE with
  periodic or anti periodic boundary conditions: Application to nanotubes

abstract:
  We compare three different methods to obtain solutions of Sturm-Liouville
problems: a successive approximation method and two other iterative methods. We
look for solutions with periodic or anti periodic boundary conditions. With
some numerical test over the Mathieu equation, we compare the efficiency of
these three methods. As an application, we make a numerical analysis on a model
for carbon nanotubes.


title: On the Formation and Chemical Composition of Super Earths

abstract:
  Super Earths are the largest population of exoplanets and are seen to exhibit
a rich diversity of compositions as inferred through their mean densities. Here
we present a model that combines equilibrium chemistry in evolving disks with
core accretion that tracks materials accreted onto planets during their
formation. In doing so, we aim to explain why super Earths form so frequently
and how they acquire such a diverse range of compositions. A key feature of our
model is disk inhomogeneities, or planet traps, that act as barriers to rapid
type-I migration. The traps we include are the dead zone, which can be caused
by either cosmic ray or X-ray ionization, the ice line, and the heat
transition. We find that in disks with sufficiently long lifetimes ($\gtrsim$ 4
Myr), all traps produce Jovian planets. In these disks, planet formation in the
heat transition and X-ray dead zone produces hot Jupiters while the ice line
and cosmic ray dead zones produce Jupiters at roughly 1 AU. Super Earth
formation takes place within short-lived disks ($\lesssim$ 2 Myr), whereby the
disks are photoevaporated while planets are in a slow phase of gas accretion.
We find that super Earth compositions range from dry and rocky ($<$ 6 % ice by
mass) to those with substantial water contents ($>$ 30 % ice by mass). The
traps play a crucial role in our results, as they dictate where in the disk
particular planets can accrete from, and what compositions they are able to
acquire.


title: Comments related to infinite wedge representations

abstract:
  We study the infinite wedge representation and show how it is related to the
universal extension of $g[t,t^{-1}]$ the loop algebra of a complex semi-simple
Lie algebra $g$. We also give an elementary proof of the boson-fermion
correspondence. Our approach to proving this result is based on a combinatorial
construction with partitions combined with an application of the
Murnaghan-Nakayama rule.


title:
Improved Lower Bounds on Mutual Information Accounting for Nonlinear
  Signal-Noise Interaction

abstract:
  In fiber-optic communications, evaluation of mutual information (MI) is still
an open issue due to the unavailability of an exact and mathematically
tractable channel model. Traditionally, lower bounds on MI are computed by
approximating the (original) channel with an auxiliary forward channel. In this
paper, lower bounds are computed using an auxiliary backward channel, which has
not been previously considered in the context of fiber-optic communications.
Distributions obtained through two variations of the stochastic digital
backpropagation (SDBP) algorithm are used as auxiliary backward channels and
these bounds are compared with bounds obtained through the conventional digital
backpropagation (DBP). Through simulations, higher information rates were
achieved with SDBP, {which can be explained by the ability of SDBP to account
for nonlinear signal--noise interactions


title: Measuring rare and exclusive Higgs boson decays into light resonances

abstract:
  We evaluate the LHC's potential of observing Higgs boson decays into light
elementary or composite resonances through their hadronic decay channels. We
focus on the Higgs boson production processes with the largest cross sections,
$pp\to h$ and $pp\to h+\mathrm{jet}$, with subsequent decays $h \to ZA$ or
$h\to Z\,\eta_c$, and comment on the production process $pp\to hZ$. By
exploiting track-based jet substructure observables and extrapolating to
$3000~\mathrm{fb}^{-1}$ we find ${\cal BR}(h \to ZA) \simeq {\cal BR}(h \to Z
\eta_c) \lesssim 0.02$ at 95% CL. We interpret this limit in terms of the 2HDM
Type 1. We find that searches for $h\to ZA$ are complementary to existing
measurements and can constrain large parts of the currently allowed parameter
space.


title:
High-frequency asymptotic compression of dense BEM matrices for general
  geometries without ray tracing

abstract:
  Wave propagation and scattering problems in acoustics are often solved with
boundary element methods. They lead to a discretization matrix that is
typically dense and large: its size and condition number grow with increasing
frequency. Yet, high frequency scattering problems are intrinsically local in
nature, which is well represented by highly localized rays bouncing around.
Asymptotic methods can be used to reduce the size of the linear system, even
making it frequency independent, by explicitly extracting the oscillatory
properties from the solution using ray tracing or analogous techniques.
However, ray tracing becomes expensive or even intractable in the presence of
(multiple) scattering obstacles with complicated geometries. In this paper, we
start from the same discretization that constructs the fully resolved large and
dense matrix, and achieve asymptotic compression by explicitly localizing the
Green's function instead. This results in a large but sparse matrix, with a
faster associated matrix-vector product and, as numerical experiments indicate,
a much improved condition number. Though an appropriate localisation of the
Green's function also depends on asymptotic information unavailable for general
geometries, we can construct it adaptively in a frequency sweep from small to
large frequencies in a way which automatically takes into account a general
incident wave. We show that the approach is robust with respect to non-convex,
multiple and even near-trapping domains, though the compression rate is clearly
lower in the latter case. Furthermore, in spite of its asymptotic nature, the
method is robust with respect to low-order discretizations such as piecewise
constants, linears or cubics, commonly used in applications. On the other hand,
we do not decrease the total number of degrees of freedom compared to a
conventional classical discretization. The combination of the ...


title: New debris disks in nearby young moving groups

abstract:
  A significant fraction of nearby young moving group members harbor
circumstellar debris dust disks. Due to their proximity and youth, these disks
are attractive targets for studying the early evolution of debris dust and
planetesimal belts. Here we present 70 and 160$\mu$m observations of 31 systems
in the $\beta$ Pic moving group, and in the Tucana-Horologium, Columba, Carina
and Argus associations, using the Herschel Space Observatory. None of these
stars were observed at far-infrared wavelengths before. Our Herschel
measurements were complemented by photometry from the WISE satellite for the
whole sample, and by submillimeter/millimeter continuum data for one source, HD
48370. We identified six stars with infrared excess, four of them are new
discoveries. By combining our new findings with results from the literature, we
examined the incidence and general characteristics of debris disks around
Sun-like members of the selected groups. With their dust temperatures of <45 K
the newly identified disks around HD 38397, HD 48370, HD 160305, and BD-20 951
represent the coldest population within this sample. For HD 38397 and HD 48370,
the emission is resolved in the 70$\mu$m PACS images, the estimated radius of
these disks is ~90 au. Together with the well-known disk around HD 61005, these
three systems represent the highest mass end of the known debris disk
population around young G-type members of the selected groups. In terms of dust
content, they resemble the hypothesized debris disk of the ancient Solar
System.


title:
All correlations must die: Assessing the significance of a stochastic
  gravitational-wave background in pulsar-timing arrays

abstract:
  We present two methods for determining the significance of a stochastic
gravitational-wave (GW) background affecting a pulsar-timing array, where
detection is based on evidence for quadrupolar spatial correlations between
pulsars. Rather than constructing noise simulations, we eliminate the GWB
spatial correlations in the true datasets to assess detection significance with
all real data features intact. In our first method, we perform random phase
shifts in the signal-model basis functions. This phase shifting eliminates
signal phase coherence between pulsars, while keeping the statistical
properties of the pulsar timing residuals intact. We then explore a method to
null correlations between pulsars by using a "scrambled" overlap-reduction
function in the signal model for the array. This scrambled function is
orthogonal to what we expect of a real GW background signal. We demonstrate the
efficacy of these methods using Bayesian model selection on a set of simulated
datasets that contain a stochastic GW signal, timing noise, undiagnosed
glitches, and uncertainties in the Solar system ephemeris. Finally, we
introduce an overarching formalism under which these two techniques are
naturally linked. These methods are immediately applicable to all current
pulsar-timing array datasets, and should become standard tools for future
analyses.


title:
Frequency-dependent dielectric function of semiconductors with
  application to physisorption

abstract:
  The dielectric function is one of the most important quantities that
describes the electrical and optical properties of solids. Accurate modeling of
the frequency-dependent dielectric function has great significance in the study
of the long-range van der Waals (vdW) interaction for solids and adsorption. In
this work, we calculate the frequency-dependent dielectric functions of
semiconductors and insulators using the $GW$ method with and without exciton
effects, as well as efficient semilocal density functional theory (DFT), and
compare these calculations with a model frequency-dependent dielectric
function. We find that for semiconductors with moderate band gaps, the model
dielectric functions, $GW$ values, and DFT calculations all agree well with
each other. However, for insulators with strong exciton effects, the model
dielectric functions have a better agreement with accurate $GW$ values than the
DFT calculations, particularly in high-frequency region. To understand this, we
repeat the DFT calculations with scissors correction, by shifting DFT Kohn-Sham
energy gap to match the experimental band gap. We find that scissors correction
only moderately improves the DFT dielectric function in low-frequency region.
Based on the dielectric functions calculated with different methods, we make a
comparative study by applying these dielectric functions to calculate the vdW
coefficients ($C_3$ and $C_5$) for adsorption of rare-gas atoms on a variety of
surfaces. We find that the vdW coefficients obtained with the nearly-free
electron gas-based model dielectric function agree quite well with those
obtained from the $GW$ dielectric function, in particular for adsorption on
semiconductors, leading to an overall error of less than 7% for $C_3$ and 5%
for $C_5$. This demonstrates the reliability of the model dielectric function
for the study of physisorption.


title:
Density Scaling and Decoupling in o-Terphenyl, Salol, and
  Dibutyphthalate

abstract:
  We present new viscosity and equation of state (EoS) results extending to
high pressures for o-terphenyl, salol, and dibutylphthalate. Using these and
data from the literature, we show that the three liquids all conform to density
scaling; that is, their reduce viscosities and reorientational relaxation times
are a function of the ratio of temperature and density with the latter raised
to a constant. Moreover, the functional form of the dependence on this ratio is
independent of the experimental probe of the dynamics. This means that there is
no decoupling of the viscosities and relaxation times over the measured range
of conditions. Previous literature at odds with these results were based on
erroneous extrapolations of the EoS or problematic diamond anvil viscosity
data. Thus, there are no exceptions to the experimental fact that every
non-associated liquid complies with density scaling with an invariant scaling
exponent.


title: Graphlike families of multiweights

abstract:
  Let ${\cal G}=(G,w)$ be a weighted graph , that is, a graph $G$ endowed with
a function $w$ from the edge set of $G$ to the set of real numbers; for any
subset $S$ of the vertex set of $G$, we define $D_S({\cal G})$ to be the
minimum of the weights of the subgraphs of $G$ whose vertex set contains $S$;
we call $D_S({\cal G})$ a multiweight of ${\cal G}$.
  Let $X$ be a finite set and let $\{D_S\}_{S \subset X, \; \sharp S \geq 2} $
be a family of positive real numbers. We find necessary and sufficient
conditions for the family to be the family of multiweights of a
positive-weighted graph with vertex set $X$. Moreover we study the analogous
problem for trees. Finally, we find a criterion to say if there exists a
nonnegative-weighted tree ${\cal T}$ with leaf set $X$ and such that $D_S
({\cal T})=D_S $ for any $S \subset X$.


title: Disease Trajectory Maps

abstract:
  Medical researchers are coming to appreciate that many diseases are in fact
complex, heterogeneous syndromes composed of subpopulations that express
different variants of a related complication. Time series data extracted from
individual electronic health records (EHR) offer an exciting new way to study
subtle differences in the way these diseases progress over time. In this paper,
we focus on answering two questions that can be asked using these databases of
time series. First, we want to understand whether there are individuals with
similar disease trajectories and whether there are a small number of degrees of
freedom that account for differences in trajectories across the population.
Second, we want to understand how important clinical outcomes are associated
with disease trajectories. To answer these questions, we propose the Disease
Trajectory Map (DTM), a novel probabilistic model that learns low-dimensional
representations of sparse and irregularly sampled time series. We propose a
stochastic variational inference algorithm for learning the DTM that allows the
model to scale to large modern medical datasets. To demonstrate the DTM, we
analyze data collected on patients with the complex autoimmune disease,
scleroderma. We find that DTM learns meaningful representations of disease
trajectories and that the representations are significantly associated with
important clinical outcomes.


title: Cognitive Control in the Controllable Connectome

abstract:
  Cognition is supported by neurophysiological processes that occur both in
local anatomical neighborhoods and in distributed large-scale circuits. Recent
evidence from network control theory suggests that white matter pathways
linking large-scale brain regions provide a critical substrate constraining the
ability of single areas to affect control on those processes. Yet, no direct
evidence exists for a relationship between brain network controllability and
cognitive control performance. Here, we address this gap by constructing
structural brain networks from diffusion tensor imaging data acquired in 125
healthy adult individuals. We define a simplified model of brain dynamics and
simulate network control to quantify modal and boundary controllability, which
together describe complementary features of a region's theoretically predicted
preference to drive the brain into different cognitive states. We observe that
individual differences in these control features derived from structural
connectivity are significantly correlated with individual differences in
cognitive control performance, as measured by a continuous performance
attention test, a color/shape switching task, the Stroop inhibition task, and a
spatial n-back working memory task. Indeed, control hubs like anterior
cingulate are distinguished from default mode and frontal association areas in
terms of the relationship between their control properties and individual
differences in cognitive function. These results provide the first empirical
evidence that network control forms a fundamental mechanism of cognitive
control.


title: Rainbow metric from quantum gravity: anisotropic cosmology

abstract:
  In this paper we present a construction of effective cosmological models
which describe the propagation of a massive quantum scalar field on a quantum
anisotropic cosmological spacetime. Each obtained effective model is
represented by a rainbow metric in which particles of distinct momenta
propagate on different classical geometries. Our analysis shows that upon
certain assumptions and conditions on the parameters determining such
anisotropic models, we surprisingly obtain a unique deformation parameter
$\beta$ in the modified dispersion relation of the modes. Hence inducing an
isotropic deformation despite the general starting considerations. We then
ensure the recovery of the dispersion relation realized in the isotropic case,
studied in [arXiv:1412.6000], when some proper symmetry constraints are
imposed, and we estimate the value of the deformation parameter for this case
in loop quantum cosmology context.


title: Object Boundary Detection and Classification with Image-level Labels

abstract:
  Semantic boundary and edge detection aims at simultaneously detecting object
edge pixels in images and assigning class labels to them. Systematic training
of predictors for this task requires the labeling of edges in images which is a
particularly tedious task. We propose a novel strategy for solving this task,
when pixel-level annotations are not available, performing it in an almost
zero-shot manner by relying on conventional whole image neural net classifiers
that were trained using large bounding boxes. Our method performs the following
two steps at test time. Firstly it predicts the class labels by applying the
trained whole image network to the test images. Secondly, it computes
pixel-wise scores from the obtained predictions by applying backprop gradients
as well as recent visualization algorithms such as deconvolution and layer-wise
relevance propagation. We show that high pixel-wise scores are indicative for
the location of semantic boundaries, which suggests that the semantic boundary
problem can be approached without using edge labels during the training phase.


title:
Three dimensional graph drawing with fixed vertices and one bend per
  edge

abstract:
  We prove that for every graph $G$, given fixed locations for the vertices of
$G$ in $\mathbb{Z}^3$, there is a three-dimensional grid-drawing of $G$ with
one bend per edge. The best previous bound was three bends per edge.


title:
Multiple mixing and parabolic divergence in smooth area-preserving flows
  on higher genus surfaces

abstract:
  We consider typical area preserving flows on higher genus surfaces and prove
that the flow restricted to mixing minimal components is mixing of all orders,
thus answering affimatively to Rohlin's multiple mixing question in this
context. The main tool is a variation of the Ratner property (a property
originally proved by Ratner for the horocycle flow), i.e. the switchable Ratner
property introduced by Fayad and Kanigowski for special flows over rotations.
This property, which is of independent interest, provides a quantitative
description of the parabolic behaviour of these flows and has implications to
joinings classification. The main result is formulated in the language of
special flows over interval exchange transformations with asymmetric
logarithmic singularities. We also prove a strengthening of one of Fayad and
Kanigowski's main results, by showing that Arnold's flows are mixing of all
orders for almost every location of the singularities.


title:
A Semi-Definite Programming approach to low dimensional embedding for
  unsupervised clustering

abstract:
  This paper proposes a variant of the method of Gu\'edon and Verhynin for
estimating the cluster matrix in the Mixture of Gaussians framework via
Semi-Definite Programming. A clustering oriented embedding is deduced from this
estimate. The procedure is suitable for very high dimensional data because it
is based on pairwise distances only. Theoretical garantees are provided and an
eigenvalue optimisation approach is proposed for computing the embedding. The
performance of the method is illustrated via Monte Carlo experiements and
comparisons with other embeddings from the literature.


title: Non-universal Z' models with protected flavour-changing interactions

abstract:
  We define a new class of Z' models with neutral flavour-changing interactions
at tree level in the down-quark sector. They are related in an exact way to
elements of the quark mixing matrix due to an underlying flavoured U(1)' gauge
symmetry, rendering these models particularly predictive. The same symmetry
implies lepton-flavour non-universal couplings, fully determined by the gauge
structure of the model. Our models allow to address several presently observed
deviations from the SM and specific correlations among the new physics
contributions to the Wilson coefficients C9,10(l) can be tested in b->sll
transitions. We furthermore predict lepton-universality violations in Z'
decays, testable at the LHC.


title:
Reorientation of the bicollinear antiferromagnetic structure at the
  surface of Fe$_{1+y}$Te bulk and thin films

abstract:
  Establishing the relation between the ubiquitous antiferromagnetism in the
non-superconducting parent compounds of unconventional superconductors and
their superconducting phase is believed to be important for the understanding
of the complex physics in these materials. Going from the bulk systems to thin
films strongly affects the phase diagram of unconventional superconductors. For
Fe$_{1+y}$Te, the parent compound of the Fe$_{1+y}$Se$_{1-x}$Te$_x$
superconductors, bulk sensitive neutron diffraction has revealed an in-plane
oriented bicollinear antiferromagnetic structure. Here, we show by
spin-resolved scanning tunneling microscopy that on the surfaces of bulk
Fe$_{1+y}$Te, as well as on thin films grown on the topological insulator
Bi$_2$Te$_3$, the spin direction is canted both away from the surface plane and
from the high-symmetry directions of the surface unit cell, while keeping the
bicollinear magnetic structure. Our results demonstrate that the magnetism at
the Fe-chalcogenide surface markedly deviates from a simple in-plane oriented
bicollinear antiferromagnetic structure, which implies that the pairing at the
surface of the related superconducting compounds might be different from that
in the bulk.


title: Small coherence implies the weak Null Space Property

abstract:
  In the Compressed Sensing community, it is well known that given a matrix $X
\in \mathbb R^{n\times p}$ with $\ell_2$ normalized columns, the Restricted
Isometry Property (RIP) implies the Null Space Property (NSP). It is also well
known that a small Coherence $\mu$ implies a weak RIP, i.e. the singular values
of $X_T$ lie between $1-\delta$ and $1+\delta$ for "most" index subsets $T
\subset \{1,\ldots,p\}$ with size governed by $\mu$ and $\delta$. In this short
note, we show that a small Coherence implies a weak Null Space Property, i.e.
$\Vert h_T\Vert_2 \le C \ \Vert h_{T^c}\Vert_1/\sqrt{s}$ for most $T \subset
\{1,\ldots,p\}$ with cardinality $|T|\le s$. We moreover prove some singular
value perturbation bounds that may also prove useful for other applications.


title: A multilayer approach for price dynamics in financial markets

abstract:
  We introduce a new Self-Organized Criticality (SOC) model for simulating
price evolution in an artificial financial market, based on a multilayer
network of traders. The model also implements, in a quite realistic way with
respect to previous studies, the order book dy- namics, by considering two
assets with variable fundamental prices. Fat tails in the probability
distributions of normalized returns are observed, together with other features
of real financial markets.


title: Toward unbiased estimations of the statefinder parameters

abstract:
  With the use of simulated supernova catalogs, we show that the statefinder
parameters turn out to be poorly and biased estimated by standard cosmography.
To this end, we compute their standard deviations and several bias statistics
on cosmologies near the concordance model, demonstrating that these are very
large, making standard cosmography unsuitable for future and wider compilations
of data. To overcome this issue, we propose a new method that consists in
introducing the series of the Hubble function into the luminosity distance,
instead of considering the usual direct Taylor expansions of the luminosity
distance. Moreover, in order to speed up the numerical computations, we
estimate the coefficients of our expansions in a hierarchical manner, in which
the order of the expansion depends on the redshift of every single piece of
data. In addition, we propose two hybrids methods that incorporates standard
cosmography at low redshifts. The methods presented here perform better than
the standard approach of cosmography both in the errors and bias of the
estimated statefinders. We further propose a one-parameter diagnostic to reject
non-viable methods in cosmography.


title:
The Role of Magnetic Helicity in the Structure and Heating of the Sun's
  Corona

abstract:
  Two of the most important features of the solar atmosphere are its hot,
smooth coronal loops and the concentrations of magnetic shear, known as
filament channels, that reside above photospheric polarity inversion lines
(PILs). The shear observed in filament channels represents magnetic helicity,
while the smoothness of the coronal loops indicates an apparent lack of
magnetic helicity in the rest of the corona. At the same time, models that
attempt to explain the high temperatures observed in these coronal loops
require magnetic energy, in the form of twist, to be injected at the
photosphere. In addition to magnetic energy, this twist also represents
magnetic helicity. Unlike magnetic energy, magnetic helicity is conserved under
reconnection, and is consequently expected to accumulate and be observed in the
corona. However, filament channels, rather than the coronal loops, are the
locations in the corona where magnetic helicity is observed, and it manifests
itself in the form of shear, rather than twist. This naturally raises the
question: if magnetic helicity needs to be injected to heat coronal loops, why
is it only observed in filament channels, while coronal loops are observed to
be laminar and smooth? This thesis addresses this question using a series of
numerical simulations that demonstrate that magnetic helicity is transported
throughout the solar corona by magnetic reconnection in such a way that it
accumulates above PILs, forming filament channels, and leaving the rest of the
corona generally smooth. In the process, it converts magnetic energy into heat,
accounting for the large observed temperatures. This thesis presents a model
for the formation of filament channels in the solar corona and the presence of
smooth, hot coronal loops, and shows how the transport of magnetic helicity
throughout the solar corona by magnetic reconnection is responsible for both of
these phenomena.


title:
Model-Free Trajectory-based Policy Optimization with Monotonic
  Improvement

abstract:
  Many of the recent trajectory optimization algorithms alternate between
linear approximation of the system dynamics around the mean trajectory and
conservative policy update. One way of constraining the policy change is by
bounding the Kullback-Leibler (KL) divergence between successive policies.
These approaches already demonstrated great experimental success in challenging
problems such as end-to-end control of physical systems. However, the linear
approximation of the system dynamics can introduce a bias in the policy update
and prevent convergence to the optimal policy. In this article, we propose a
new model-free trajectory-based policy optimization algorithm with guaranteed
monotonic improvement. The algorithm backpropagates a local, quadratic and
time-dependent \qfunc~learned from trajectory data instead of a model of the
system dynamics. Our policy update ensures exact KL-constraint satisfaction
without simplifying assumptions on the system dynamics. We experimentally
demonstrate on highly non-linear control tasks the improvement in performance
of our algorithm in comparison to approaches linearizing the system dynamics.
In order to show the monotonic improvement of our algorithm, we additionally
conduct a theoretical analysis of our policy update scheme to derive a lower
bound of the change in policy return between successive iterations.


title:
On the integrability of the isotropic almost complex structures and
  harmonic unit vector fields

abstract:
  Aguilar introduced isotropic almost complex structures $J_{\delta , \sigma}$
on the tangent bundle of a Riemannian manifold $(M, g)$. In this paper, some
results will be obtained on the integrability of these structures. These
structures with the Liouville 1-form define a class of Riemannian metrics
$g_{\delta , \sigma}$ on $T M$ which are a generalization of the Sasaki metric.
Moreover, the notion of a harmonic unit vector field is introduced with respect
to these metrics like as the Sasaki metric and the necessary and sufficient
conditions for a unit vector field to be a harmonic unit vector field are
obtained.


title: Inflation Model Selection meets Dark Radiation

abstract:
  We investigate how inflation model selection is affected by the presence of
additional free-streaming relativistic degrees of freedom, i.e. dark radiation.
We perform a full Bayesian analysis of both inflation parameters and
cosmological parameters taking reheating into account self-consistently. We
compute the Bayesian evidence for a few representative inflation scenarios in
both the standard $\Lambda$CDM model and an extension including dark radiation
parametrised by its effective number of relativistic species $N_\mathrm{eff}$.
Using a minimal dataset (Planck low-$\ell$ polarisation, temperature power
spectrum and lensing reconstruction), we find that the observational status of
most inflationary models is unchanged. The exceptions are potentials such as
power-law inflation that predict large values for the scalar spectral index
that can only be realised when $N_\mathrm{eff}$ is allowed to vary. Adding
baryon acoustic oscillations data and the B-mode data from BICEP2/Keck makes
power-law inflation disfavoured, while adding local measurements of the Hubble
constant $H_0$ makes power-law inflation slightly favoured compared to the best
single-field plateau potentials. This illustrates how the dark radiation
solution to the $H_0$ tension would have deep consequences for inflation model
selection.


title: Multiparty Delegated Quantum Computing

abstract:
  Quantum computing has seen tremendous progress in the past years. However,
due to limitations in scalability of quantum technologies, it seems that we are
far from constructing universal quantum computers for everyday users. A more
feasible solution is the delegation of computation to powerful quantum servers
on the network. This solution was proposed in previous studies of Blind Quantum
Computation, with guarantees for both the secrecy of the input and of the
computation being performed. In this work, we further develop this idea of
computing over encrypted data, to propose a multiparty delegated quantum
computing protocol in the measurement-based quantum computing framework.


title: Reconnection-Driven Coronal-Hole Jets with Gravity and Solar Wind

abstract:
  Coronal-hole jets occur ubiquitously in solar coronal holes, at EUV and X-ray
bright points associated with intrusions of minority magnetic polarity. The
embedded-bipole model for these jets posits that they are driven by explosive,
fast reconnection between the stressed closed field of the embedded bipole and
the open field of the surrounding coronal hole. Previous numerical studies in
Cartesian geometry, assuming uniform ambient magnetic field and plasma while
neglecting gravity and solar wind, demonstrated that the model is robust and
can produce jet-like events in simple configurations. We have extended these
investigations by including spherical geometry, gravity, and solar wind in a
nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that
the jet is initiated by the onset of a kink-like instability of the internal
closed field, which induces a burst of reconnection between the closed and
external open field, launching a helical jet. Our new results demonstrate that
the jet propagation is sustained through the outer corona, in the form of a
traveling nonlinear Alfven wave front trailed by slower-moving plasma density
enhancements that are compressed and accelerated by the wave. This finding
agrees well with observations of white-light coronal-hole jets, and can explain
microstreams and torsional Alfven waves detected in situ in the solar wind. We
also use our numerical results to deduce scaling relationships between
properties of the coronal source region and the characteristics of the
resulting jet, which can be tested against observations.


title: Tighter bounds lead to improved classifiers

abstract:
  The standard approach to supervised classification involves the minimization
of a log-loss as an upper bound to the classification error. While this is a
tight bound early on in the optimization, it overemphasizes the influence of
incorrectly classified examples far from the decision boundary. Updating the
upper bound during the optimization leads to improved classification rates
while transforming the learning into a sequence of minimization problems. In
addition, in the context where the classifier is part of a larger system, this
modification makes it possible to link the performance of the classifier to
that of the whole system, allowing the seamless introduction of external
constraints.


title: Bias-dependent local structure of water molecule at a metallic interface

abstract:
  Understanding the local structure of water at the interfaces of metallic
electrodes is a key problem in aqueous-based electrochemistry. Nevertheless, a
realistic simulation of such setup is challenging, particularly when the
electrodes are maintained at different potentials. To correctly compute the
effect of an external bias potential applied to truly semi-infinite surfaces,
we combine Density Functional Theory (DFT) and Non-Equilibrium Green's
Functions (NEGF) methods. This framework allows for the out-of-equilibrium
calculation of forces and dynamics, and directly correlates to the chemical
potential of the electrodes, which is the one introduced experimentally. In
this work, we apply this methodology to study the electronic properties and
atomic forces of one water molecule at the interface of gold surface. We find
that the water molecule tends to align its dipole moment with the electric
field, and it is either repelled or attracted to the metal depending on the
sign and magnitude of the applied bias, in an asymmetric fashion.


title: Extinction Law at a Distance up to 25 kpc toward the Galactic Poles

abstract:
  Photometry from the Tycho-2, 2MASS, and WISE catalogues for clump and branch
giants at a distance up to 25 kpc toward the Galactic poles has allowed the
variations of various characteristics of the infrared interstellar extinction
law with distance to be analyzed. The results obtained by the extinction law
extrapolation method are consistent for different classes of stars and
different characteristics as well as with previous studies. The conventional
extinction law with a low infrared extinction is characteristic of only a thin
layer no farther than 100 pc from the Galactic plane and of two thin layers
near $Z=-600$ and $+500$ pc. Far from the Galactic plane, in the Galactic halo,
the infrared extinction law is different: the extinction in the $Ks$, $W1$,
$W2$, $W3$, and $W4$ bands is, respectively, $0.17$, $0.16$, $0.16$, $0.07$,
and $0.03$ of the extinction in the $V$ band. The accuracy of these
coefficients is $0.03$. If the extinction law reflects primarily the grain size
distribution, then the fraction of large dust grains far from the Galactic
plane is greater than that in the circumsolar interstellar medium.


title: Next Generation Robotics

abstract:
  The National Robotics Initiative (NRI) was launched 2011 and is about to
celebrate its 5 year anniversary. In parallel with the NRI, the robotics
community, with support from the Computing Community Consortium, engaged in a
series of road mapping exercises. The first version of the roadmap appeared in
September 2009; a second updated version appeared in 2013. While not directly
aligned with the NRI, these road-mapping documents have provided both a useful
charting of the robotics research space, as well as a metric by which to
measure progress. This report sets forth a perspective of progress in robotics
over the past five years, and provides a set of recommendations for the future.
The NRI has in its formulation a strong emphasis on co-robot, i.e., robots that
work directly with people. An obvious question is if this should continue to be
the focus going forward? To try to assess what are the main trends, what has
happened the last 5 years and what may be promising directions for the future a
small CCC sponsored study was launched to have two workshops, one in Washington
DC (March 5th, 2016) and another in San Francisco, CA (March 11th, 2016). In
this report we brief summarize some of the main discussions and observations
from those workshops. We will present a variety of background information in
Section 2, and outline various issues related to progress over the last 5 years
in Section 3. In Section 4 we will outline a number of opportunities for moving
forward. Finally, we will summarize the main points in Section 5.