title:
Dimensional reduction in numerical relativity: Modified cartoon
  formalism and regularization

abstract:
  We present in detail the Einstein equations in the
Baumgarte-Shapiro-Shibata-Nakamura formulation for the case of $D$ dimensional
spacetimes with $SO(D-d)$ isometry based on a method originally introduced in
Ref.1. Regularized expressions are given for a numerical implementation of this
method on a vertex centered grid including the origin of the quasi-radial
coordinate that covers the extra dimensions with rotational symmetry.
Axisymmetry, corresponding to the value $d=D-2$, represents a special case with
fewer constraints on the vanishing of tensor components and is conveniently
implemented in a variation of the general method. The robustness of the scheme
is demonstrated for the case of a black-hole head-on collision in $D=7$
spacetime dimensions with $SO(4)$ symmetry.


title:
Enhancement of crossed Andreev reflection in a superconducting ladder
  connected to normal metal leads

abstract:
  Crossed Andreev reflection (cAR) is a scattering process that happens in a
quantum transport set-up consisting of two normal metals (NM) attached to a
superconductor (SC), where an electron incident from one NM results in a hole
emerging in the other. Typically, an electron tunnelling through the
superconductor from one NM to the other (ET) competes with cAR and masks the
signature of cAR in the conductance spectrum. We propose a novel scheme to
enhance cAR, in which SC part of the NM-SC-NM is side-coupled to another SC
having a different SC phase to form a Josephson junction in the transverse
direction. At strong enough coupling and adequate phase difference, one can
smoothly traverse between highly ET-dominant to highly cAR-dominant transport
regimes by tuning chemical potential, due to the appearance of subgap Andreev
states that are extended in the longitudinal direction. We also discuss
connections to realistic systems.


title: D-instantons in Klebanov-Witten model

abstract:
  We study D-instanton solutions in type IIB supergravity on $AdS_5\times
T^{1,1}$, which has a dual ${\cal N}=1$ $SU(N)\times SU(N)$ super Yang-Mills
theory. Apart from ordinary D(-1)-brane instantons, we discuss wrapped
D1-branes over minimal 2-cycles and derive explicit solutions preserving half
the supersymmetries. These solutions are identified with Yang-Mills instantons
which are (anti)self-dual in both gauge group factors with instanton charge
$(k,k')$. By examining the boundary behaviour of the solutions we discuss the
coupling to the corresponding dual boundary operators, and identify their
vacuum expectation values. We also discuss the boundary terms and compute the
action for these solutions.


title:
A third-moment theorem and precise asymptotics for variations of
  stationary Gaussian sequences

abstract:
  In two new papers (Bierme et al., 2013) and (Nourdin and Peccati, 2015),
sharp general quantitative bounds \ are given to complement the well-known
fourth moment theorem of Nualart and Peccati, by which a sequence in a fixed
Wiener chaos converges to a normal law if and only if its fourth cumulant
converges to $0$. The bounds show that the speed of convergence is precisely of
order the maximum of the fourth cumulant and the absolute value of the third
moment (cumulant). Specializing to the case of normalized centered quadratic
variations for stationary Gaussian sequences, we show that a third moment
theorem holds: convergence occurs if and only if the sequence's third moments
tend to $0$. This is proved for sequences with general decreasing covariance,
by using the result of (Nourdin and Peccati, 2015), and finding the exact speed
of convergence to $0$ of the quadratic variation's third and fourth cumulants.
(Nourdin and Peccati, 2015) also allows us to derive quantitative estimates for
the speeds of convergence in a class of log-modulated covariance structures,
which puts in perspective the notion of critical Hurst parameter when studying
the convergence of fractional Brownian motion's quadratic variation. We also
study the speed of convergence when the limit is not Gaussian but rather a
second-Wiener-chaos law. Using a log-modulated class of spectral densities, we
recover a classical result of Dobrushin-Major/Taqqu whereby the limit is a
Rosenblatt law, and we provide new convergence speeds. The conclusion in this
case is that the price to pay to obtain a Rosenblatt limit despite a slowly
varying modulation is a very slow convergence speed, roughly of the same order
as the modulation.


title: The 3He spectral function in light-front dynamics

abstract:
  A distorted spin-dependent spectral function for 3He is considered for the
extraction of the transverse-momentum dependent parton distributions in the
neutron from semi-inclusive deep inelastic electron scattering off polarized
3He at finite momentum transfers, where final state interactions are taken into
account. The generalization of the analysis to a Poincar\'e covariant framework
within the light-front dynamics is outlined.


title: Gluing formulas for the $L^2$-Alexander torsions

abstract:
  We prove a Torres-like formula for the $L^2$-Alexander torsions of links, as
well as formulas for connected sums and cablings of links. Along the way we
compute explicitly the $L^2$-Alexander torsions of torus links inside the
three-sphere, the solid torus and the thickened torus.


title:
On the connection between radio mini-halos and gas heating in cool core
  clusters

abstract:
  In this work, we present a study of the central regions of cool-core clusters
hosting radio mini-halos, which are di use synchrotron sources extended on
cluster-scales surrounding the radio-loud brightest galaxy. We aim to
investigate the interplay between the thermal and non-thermal components in the
intracluster medium in order to get more insights into these radio sources,
whose nature is still unclear. It has recently been proposed that turbulence
plays a role for heating the gas in cool cores. A correlation between the radio
luminosity of mini-halos, $\nu P_{\nu}$, and the cooling flow power, $P_{\rm
CF}$, is expected in the case that this turbulence also plays a role for the
acceleration of the relativistic particles. We carried out a homogeneous
re-analysis of X-ray Chandra data of the largest sample of cool-core clusters
hosting radio mini-halos currently available ($\sim20$ objects), finding a
quasi-linear correlation, $\nu P_{\nu} \propto P_{\rm CF}^{0.8}$. We show that
the scenario of a common origin of radio mini-halos and gas heating in
cool-core clusters is energetically viable, provided that mini-halos trace
regions where the magnetic field strength is $B \gg 0.5 \mu G$.


title: Realizing nonholonomic dynamics as limit of friction forces

abstract:
  The classical question whether nonholonomic dynamics is realized as limit of
friction forces was first posed by Carath\'eodory. It is known that, indeed,
when friction forces are scaled to infinity, then nonholonomic dynamics is
obtained as a singular limit.
  Our results are twofold. First, we formulate the problem in a differential
geometric context. Using modern geometric singular perturbation theory in our
proof, we then obtain a sharp statement on the convergence of solutions on
infinite time intervals. Secondly, we set up an explicit scheme to approximate
systems with large friction by a perturbation of the nonholonomic dynamics. The
theory is illustrated in detail by studying analytically and numerically the
Chaplygin sleigh as example. This approximation scheme offers a reduction in
dimension and has potential use in applications.


title:
Scalable Metric Learning via Weighted Approximate Rank Component
  Analysis

abstract:
  We are interested in the large-scale learning of Mahalanobis distances, with
a particular focus on person re-identification.
  We propose a metric learning formulation called Weighted Approximate Rank
Component Analysis (WARCA). WARCA optimizes the precision at top ranks by
combining the WARP loss with a regularizer that favors orthonormal linear
mappings, and avoids rank-deficient embeddings. Using this new regularizer
allows us to adapt the large-scale WSABIE procedure and to leverage the Adam
stochastic optimization algorithm, which results in an algorithm that scales
gracefully to very large data-sets. Also, we derive a kernelized version which
allows to take advantage of state-of-the-art features for re-identification
when data-set size permits kernel computation.
  Benchmarks on recent and standard re-identification data-sets show that our
method beats existing state-of-the-art techniques both in term of accuracy and
speed. We also provide experimental analysis to shade lights on the properties
of the regularizer we use, and how it improves performance.


title:
Modeling the behavior of signal-to-noise ratio for repeated snapshot
  imaging

abstract:
  For imaging of static object by the means of sequential repeated independent
measurements, a theoretical modeling of the behavior of signal-to-noise ratio
(SNR) with varying number of measurement is developed, based on the information
capacity of optical imaging systems. Experimental veritification of imaging
using pseudo-thermal light source is implemented, for both the direct average
of multiple measurements, and the image reconstructed by second order
fluctuation correlation (SFC) which is closely related to ghost imaging.
Successful curve fitting of data measured under different conditions verifies
the model.


title: The possibility to predict crack patterns on dynamic fracture

abstract:
  The Maximum Energy Dissipation Principle (MEDP) for dynamics fracture, far
from equilibrium, proposed by Slepyan was modified. This modification includes
a decoupling between the injected and dissipated energy by adding of a time
delay and a description of the ruggedness produced by dissipation patterns. A
time delayed energy conservation equation is deduced and dynamical equations
that describe the dynamical system evolution were obtained in analogous way to
the Slepyan's calculations. The conditions for the rising of the instability
process were presented by a bifurcation map. These results shown that the
theoretical framework proposed can describe the instability process along with
dissipation patterns formation. This proposal was applied to dynamics fracture
where it was possible to explain the results obtained by Fineberg-Gross for the
fast crack propagation in PMMA. For unstable or dynamical crack propagation it
is shown the possibility to predict crack patterns using this MEDP for other
experimental configurations.


title: Rigidity of 2-step Carnot groups

abstract:
  In the present paper we study the rigidity of 2-step Carnot groups, or
equivalently, of graded 2-step nilpotent Lie algebras. We prove the alternative
that depending on bi-dimensions of the algebra, the Lie algebra structure makes
it either always of infinite type or generically rigid, and we specify the
bi-dimensions for each of the choices. Explicit criteria for rigidity of pseudo
$H$- and $J$-type algebras are given. In particular, we establish the relation
of the so-called $J^2$-condition to rigidity, and we explore these conditions
in relation to pseudo $H$-type algebras.


title:
On the Second Moment Estimate Involving the $\lambda$-Primitive Roots
  Modulo $n$

abstract:
  Artin's Conjecture on Primitive Roots states that a non-square nonunit
integer $a$ is a primitive root modulo $p$ for the positive proportion of $p$.
This conjecture remains open, but on average, there are many results due to P.
J. Stephens. There is a natural generalization of the conjecture for composite
moduli. We can consider $a$ as the primitive root modulo,
$(\mathbb{Z}/n\mathbb{Z})^{*}$ if $a$ is an element of the maximal exponent in
the group. The behavior is more complex for composite moduli, and the
corresponding average results are provided by S. Li and C. Pomerance, and
recently by the author. P. J. Stephens included the second moment results in
his work, but for composite moduli, there were no such results previously. We
prove that the corresponding second moment results in this case.


title: Easy-First Dependency Parsing with Hierarchical Tree LSTMs

abstract:
  We suggest a compositional vector representation of parse trees that relies
on a recursive combination of recurrent-neural network encoders. To demonstrate
its effectiveness, we use the representation as the backbone of a greedy,
bottom-up dependency parser, achieving state-of-the-art accuracies for English
and Chinese, without relying on external word embeddings. The parser's
implementation is available for download at the first author's webpage.


title: Mesoscale Modeling of Impact Compaction of Primitive Solar System Solids

abstract:
  We have developed a method for simulating the mesoscale compaction of early
solar system solids in low velocity impact events, using the iSALE shock
physics code. Chondrules are represented by nonporous disks, placed within a
porous matrix. By simulating impacts into bimodal mixtures over a wide range of
parameter space (including the chondrule-to-matrix ratio, the matrix porosity
and composition and the impact velocity), we have shown how each of these
parameters influences the shock processing of heterogeneous materials. The
temperature after shock processing shows a strong dichotomy: matrix
temperatures are elevated much higher than the chondrules, which remain largely
cold. Chondrules can protect some matrix from shock compaction, with shadow
regions in the lee side of chondrules exhibiting higher porosity that elsewhere
in the matrix. Using the results from this mesoscale modelling, we show how the
$\varepsilon-\alpha$ porous compaction model parameters depend on initial bulk
porosity. We also show that the timescale for the temperature dichotomy to
equilibrate is highly dependent on the porosity of the matrix after the shock,
and will be on the order of seconds for matrix porosities of less than 0.1, and
on the order of 10's to 100's seconds for matrix porosities of $\sim$ 0.3--0.5.
Finally, we have shown that the composition of the post-shock material is able
to match the bulk porosity and chondrule-to-matrix ratios of meteorite groups
such as carbonaceous chondrites and unequilibrated ordinary chondrites.


title: Spin relaxation in phase space

abstract:
  We have treated numerous illustrative examples of spin relaxation problems
using Wigner's phase-space formulation of quantum mechanics of particles and
spins. The merit of the phase space formalism as applied to spin relaxation
problems is that only master equations for the phase-space distributions akin
to Fokker-Planck equations for the evolution of classical phase-space
distributions in configuration space are involved so that operators are
unnecessary. The explicit solution of these equations can be expanded for an
arbitrary spin Hamiltonian in a finite series of spherical harmonics like in
the classical case. The expansion coefficients (statistical moments or averages
of the spherical harmonics which are obviously by virtue of the
Wigner-Stratonovich map the averages of the polarization operators) may be
determined from differential-recurrence relations in a manner similar to the
classical case. Furthermore, the phase space representation via the Weyl
symbols of the relevant spin operators suggests how powerful computation
techniques developed for Fokker-Planck equations (matrix continued fractions,
mean first passage time, etc.) may be transparently extended to the quantum
domain.


title: Dropwise Condensation on Hydrophobic Cylinders

abstract:
  In this work, we studied the effect of the diameter of horizontal hydrophobic
cylinders on droplet growth. We postulate that the concentration gradient
created by natural convection around a horizontal circular cylinder is related
to the droplet growth on the cylinder by condensation. We derive a simple
scaling law of droplet growth and compare it with experimental results. The
predicted negative exponent of drop diameter (d) as a function of cylinder
diameter (D) at different time points is similar to the general trend of
experimental data. Further, this effect of cylinder diameter on droplet growth
is observed to be stronger than the supersaturation conditions created by
different surface temperatures.


title: Brendle's inequality on static manifolds

abstract:
  We generalize Brendle's geometric inequality considered in \cite{B} to static
manifolds. The inequality bounds the integral of inverse mean curvature of an
embedded mean-convex hypersurface by geometric data of the horizon. As a
consequence, we obtain a reverse Penrose inequality on static asymptotically
locally hyperbolic manifolds in the spirit of Chru\'{s}ciel and Simon
\cite{CS}.


title: Blocking transport resonances via Kondo entanglement in quantum dots

abstract:
  Many-body entanglement is at the heart of the Kondo effect, which has its
hallmark in quantum dots as a zero-bias conductance peak at low temperatures.
It signals the emergence of a conducting singlet state formed by a localized
dot degree of freedom and conduction electrons. Carbon nanotubes offer the
possibility to study the emergence of the Kondo entanglement by tuning
many-body correlations with a gate voltage. Here we quantitatively show an
undiscovered side of
  Kondo correlations, which counterintuitively tend to block conduction
channels: inelastic cotunneling lines in the magnetospectrum of a carbon
nanotube strikingly disappear when tuning the gate voltage. Considering the
global \SUT\ $\otimes $ \SUT\ symmetry of a carbon nanotube coupled to leads,
we find that only resonances involving flips of the Kramers pseudospins,
associated to this symmetry, are observed at temperatures and voltages below
the corresponding Kondo scale. Our results demonstrate the robust formation of
entangled many-body states with no net pseudospin.


title:
Composite pulses in Hyper-Ramsey spectroscopy for the next generation of
  atomic clocks

abstract:
  The next generation of atomic frequency standards based on an ensemble of
neutral atoms or a single-ion will provide very stringent tests in metrology,
applied and fundamental physics requiring a new step in very precise control of
external systematic corrections. In the proceedings of the 8th Symposium on
Frequency Standards and Metrology, we present a generalization of the recent
Hyper-Ramsey spectroscopy with separated oscillating fields using composites
pulses in order to suppress field frequency shifts induced by the interrogation
laser itself. Sequences of laser pulses including specific selection of phases,
frequency detunings and durations are elaborated to generate spectroscopic
signals with a strong reduction of the light-shift perturbation by off resonant
states. New optical clocks based on weakly allowed or completely forbidden
transitions in atoms, ions, molecules and nuclei will benefit from these
generalized Ramsey schemes to reach relative accuracies well below the
10$^{-18}$ level.


title: Spectrally unstable domains

abstract:
  Let $H$ be a separable Hilbert space, $A_c:\mathcal D_c\subset H\to H$ a
densely defined unbounded operator, bounded from below, let $\mathcal D_{\min}$
be the domain of the closure of $A_c$ and $\mathcal D_{\max}$ that of the
adjoint. Assume that $\mathcal D_{\max}$ with the graph norm is compactly
contained in $H$ and that $\mathcal D_{\min}$ has finite positive codimension
in $\mathcal D_{\max}$. Then the set of domains of selfadjoint extensions of
$A_c$ has the structure of a finite-dimensional manifold $\mathfrak {SA}$ and
the spectrum of each of its selfadjoint extensions is bounded from below. If
$\zeta$ is strictly below the spectrum of $A$ with a given domain $\mathcal
D_0\in \mathfrak {SA}$, then $\zeta$ is not in the spectrum of $A$ with domain
$\mathcal D\in \mathfrak {SA}$ near $\mathcal D_0$. But $\mathfrak {SA}$
contains elements $\mathcal D_0$ with the property that for every neighborhood
$U$ of $\mathcal D_0$ and every $\zeta\in \mathbb R$ there is $\mathcal D\in U$
such that $\mathrm{spec}(A_\mathcal D)\cap (-\infty,\zeta)\ne \emptyset$. We
characterize these "spectrally unstable" domains as being those satisfying a
nontrivial relation with the domain of the Friedrichs extension of $A_c$.


title: Magnetic field dependence of the neutron spin resonance in CeB6

abstract:
  In zero magnetic field, the famous neutron spin resonance in the f-electron
superconductor CeCoIn5 is similar to the recently discovered exciton peak in
the non-superconducting CeB6. Magnetic field splits the resonance in CeCoIn5
into two components, indicating that it is a doublet. Here we employ inelastic
neutron scattering (INS) to scrutinize the field dependence of spin
fluctuations in CeB6. The exciton shows a markedly different behavior without
any field splitting. Instead, we observe a second field-induced magnon whose
energy increases with field. At the ferromagnetic zone center, however, we find
only a single mode with a non-monotonic field dependence. At low fields, it is
initially suppressed to zero together with the antiferromagnetic order
parameter, but then reappears at higher fields inside the hidden-order phase,
following the energy of an electron spin resonance (ESR). This is a unique
example of a ferromagnetic resonance in a heavy-fermion metal seen by both ESR
and INS consistently over a broad range of magnetic fields.


title:
Une remarque \`a propos de l'\'equivalence bilipschitzienne entre des
  ensembles de Delone. (A remark concerning bi-Lipschitz equivalence between
  Delone sets.)

abstract:
  Linearly repetitive Delone sets are shown to be rectifiable by a bi-Lipschitz
homeomorphisms of the Euclidean space that sends the Delone set to the set of
points with integer coordinates.


title:
On the two-loop virtual QCD corrections to Higgs boson pair production
  in the Standard Model

abstract:
  We compute the next-to-leading order virtual QCD corrections to Higgs pair
production via gluon fusion. We present analytic results for the two-loop
contributions to the spin-0 and spin-2 form factors in the amplitude. The
reducible contributions, given by the double-triangle diagrams, are evaluated
exactly while the two-loop irreducible diagrams are evaluated by an asymptotic
expansion in heavy top quark mass up to and including terms of
$\mathcal{O}(1/m_t^8)$. Assuming that the finite top-quark mass effects are of
similar size in the entire range of partonic energies we estimate that mass
effects can reduce the hadronic cross section by at most $10\%$.


title: Forman curvature for complex networks

abstract:
  We adapt Forman's discretization of Ricci curvature to the case of undirected
networks, both weighted and unweighted, and investigate the measure in a
variety of model and real-world networks. We find that most nodes and edges in
model and real networks have a negative curvature. Furthermore, the
distribution of Forman curvature of nodes and edges is narrow in random and
small-world networks, while the distribution is broad in scale-free and
real-world networks. In most networks, Forman curvature is found to display
significant negative correlation with degree and centrality measures. However,
Forman curvature is uncorrelated with clustering coefficient in most networks.
Importantly, we find that both model and real networks are vulnerable to
targeted deletion of nodes with highly negative Forman curvature. Our results
suggest that Forman curvature can be employed to gain novel insights on the
organization of complex networks.


title: Scalar Multiplet Recombination at Large N and Holography

abstract:
  We consider the coupling of a free scalar to a single-trace operator of a
large N CFT in d dimensions. This is equivalent to a double-trace deformation
coupling two primary operators of the CFT, in the limit when one of the two
saturates the unitarity bound. At leading order, the RG-flow has a non-trivial
fixed point where multiplets recombine. We show this phenomenon in field
theory, and provide the holographic dual description. Free scalars correspond
to singleton representations of the AdS algebra. The double-trace interaction
is mapped to a boundary condition mixing the singleton with the bulk field dual
to the single-trace operator. In the IR, the singleton and the bulk scalar
merge, providing just one long representation of the AdS algebra.


title: Spectrum formation in Superluminous Supernovae (Type I)

abstract:
  The near-maximum spectra of most superluminous supernovae that are not
dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue
spectral peak and a series of absorption lines which have been identified as
OII. SN2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also
had a blue peak but a featureless optical/UV spectrum. Radiation transport
methods are used to show that the spectra (not including SN2007bi, which has a
redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather
steep density distribution of the ejecta, whose composition appears to be
typical of carbon-oxygen cores of massive stars which can have low metal
content. If the photospheric velocity is ~10000-15000 km/s, several lines form
in the UV. OII lines, however, arise from very highly excited lower levels,
which require significant departures from Local Thermodynamic Equilibrium to be
populated. These SLSNe are not thought to be powered primarily by 56Ni decay.
An appealing scenario is that they are energised by X-rays from the shock
driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of
line velocity with time that characterises SLSNe up to about maximum is another
argument in favour of the magnetar scenario. The smooth UV continuum of
SN2011kl requires higher ejecta velocities (~20000 km/s): line blanketing leads
to an almost featureless spectrum. Helium is observed in some SLSNe after
maximum. The high ionization near maximum implies that both He and H may be
present but not observed at early times. The spectroscopic classification of
SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is
required for an accurate classification.


title: Multi-Information Source Optimization

abstract:
  We consider Bayesian optimization of an expensive-to-evaluate black-box
objective function, where we also have access to cheaper approximations of the
objective. In general, such approximations arise in applications such as
reinforcement learning, engineering, and the natural sciences, and are subject
to an inherent, unknown bias. This model discrepancy is caused by an inadequate
internal model that deviates from reality and can vary over the domain, making
the utilization of these approximations a non-trivial task.
  We present a novel algorithm that provides a rigorous mathematical treatment
of the uncertainties arising from model discrepancies and noisy observations.
Its optimization decisions rely on a value of information analysis that extends
the Knowledge Gradient factor to the setting of multiple information sources
that vary in cost: each sampling decision maximizes the predicted benefit per
unit cost.
  We conduct an experimental evaluation that demonstrates that the method
consistently outperforms other state-of-the-art techniques: it finds designs of
considerably higher objective value and additionally inflicts less cost in the
exploration process.


title:
Parameter Estimation for the Langevin Equation with Stationary-Increment
  Gaussian Noise

abstract:
  We study the Langevin equation with stationary-increment Gaussian noise. We
show the strong consistency and the asymptotic normality with Berry--Esseen
bound of the so-called alternative estimator of the mean reversion parameter.
The conditions and results are stated in terms of the variance function of the
noise. We consider both the case of continuous and discrete observations. As
examples we consider fractional and bifractional Ornstein--Uhlenbeck processes.
Finally, we discuss the maximum likelihood and the least squares estimators.


title: Noisy Activation Functions

abstract:
  Common nonlinear activation functions used in neural networks can cause
training difficulties due to the saturation behavior of the activation
function, which may hide dependencies that are not visible to vanilla-SGD
(using first order gradients only). Gating mechanisms that use softly
saturating activation functions to emulate the discrete switching of digital
logic circuits are good examples of this. We propose to exploit the injection
of appropriate noise so that the gradients may flow easily, even if the
noiseless application of the activation function would yield zero gradient.
Large noise will dominate the noise-free gradient and allow stochastic gradient
descent toexplore more. By adding noise only to the problematic parts of the
activation function, we allow the optimization procedure to explore the
boundary between the degenerate (saturating) and the well-behaved parts of the
activation function. We also establish connections to simulated annealing, when
the amount of noise is annealed down, making it easier to optimize hard
objective functions. We find experimentally that replacing such saturating
activation functions by noisy variants helps training in many contexts,
yielding state-of-the-art or competitive results on different datasets and
task, especially when training seems to be the most difficult, e.g., when
curriculum learning is necessary to obtain good results.


title:
Tidal Decay and Stable Roche-Lobe Overflow of Short-Period Gaseous
  Exoplanets

abstract:
  Many gaseous exoplanets in short-period orbits are on the verge or are in the
process of Roche-lobe overflow (RLO). Moreover, orbital stability analysis
shows tides can drive many hot Jupiters to spiral inevitably toward their host
stars. Thus, the coupled processes of orbital evolution and RLO likely shape
the observed distribution of close-in exoplanets and may even be responsible
for producing some of the short-period rocky planets. However, the exact
outcome for an overflowing planet depends on its internal response to mass
loss, and the accompanying orbital evolution can act to enhance or inhibit RLO.
In this study, we apply the fully-featured and robust Modules for Experiments
in Stellar Astrophysics (MESA) suite to model RLO of short-period gaseous
planets. We show that, although the detailed evolution may depend on several
properties of the planetary system, it is largely determined by the core mass
of the overflowing gas giant. In particular, we find that the orbital expansion
that accompanies RLO often stops and reverses at a specific maximum period that
depends on the core mass. We suggest that RLO may often strand the remnant of a
gas giant near this orbital period, which provides an observational prediction
that can corroborate the hypothesis that short-period gas giants undergo RLO.
We conduct a preliminary comparison of this prediction to the observed
population of small, short-period planets and find some planets in orbits that
may be consistent with this picture. To the extent that we can establish some
short-period planets are indeed the remnants of gas giants, that population can
elucidate the properties of gas giant cores, the properties of which remain
largely unconstrained.


title:
On the Design and use of Ensembles of Multi-model Simulations for
  Forecasting

abstract:
  Probability forecasting is common in the geosciences, the finance sector, and
elsewhere. It is sometimes the case that one has multiple probability-forecasts
for the same target. How is the information in these multiple forecast systems
best "combined"? Assuming stationary, then in the limit of a very large
forecast-outcome archive, each model-based probability density function can be
weighted to form a "multi-model forecast" which will, in expectation, provide
the most information. In the case that one of the forecast systems yields a
probability distribution which reflects the distribution from which the outcome
will be drawn, then Bayesian Model Averaging will identify this model as the
number of forecast-outcome pairs goes to infinity. In many applications, like
those of seasonal forecasting, data are precious: the archive is often limited
to fewer than $2^6$ entries. And no perfect model is in hand. In this case, it
is shown that forming a single "multi-model probability forecast" can be
expected to prove misleading. These issues are investigated using probability
forecasts of a simple mathematical system, which allows most limiting
behaviours to be quantified.


title: Complexity Methods Applied to Turbulence in Plasma Astrophysics

abstract:
  In this review many of the well known tools for the analysis of Complex
systems are used in order to study the global coupling of the turbulent
convection zone with the solar atmosphere where the magnetic energy is
dissipated explosively. Several well documented observations are not easy to
interpret with the use of Magnetohydrodynamic (MHD) and/or Kinetic numerical
codes. Such observations are: (1) The size distribution of the Active Regions
(AR) on the solar surface, (2) The fractal and multi fractal characteristics of
the observed magnetograms, (3) The Self-Organised characteristics of the
explosive magnetic energy release and (4) the very efficient acceleration of
particles during the flaring periods in the solar corona. We review briefly the
work published the last twenty five years on the above issues and propose
solutions by using methods borrowed from the analysis of complex systems. The
scenario which emerged is as follows: (a) The fully developed turbulence in the
convection zone generates and transports magnetic flux tubes to the solar
surface. Using probabilistic percolation models we were able to reproduce the
size distribution and the fractal properties of the emerged and randomly moving
magnetic flux tubes. (b) Using a Non Linear Force Free (NLFF) magnetic
extrapolation numerical code we can explore how the emerged magnetic flux tubes
interact nonlinearly and form thin and Unstable Current Sheets (UCS) inside the
coronal part of the AR. (c) The fragmentation of the UCS and the redistribution
of the magnetic field locally, when the local current exceeds a Critical
threshold, is a key process which drives avalanches and forms coherent
structures. This local reorganization of the magnetic field, enhances the
energy dissipation and influences the global evolution of the complex magnetic
topology.


title: General Tensor Spectral Co-clustering for Higher-Order Data

abstract:
  Spectral clustering and co-clustering are well-known techniques in data
analysis, and recent work has extended spectral clustering to square, symmetric
tensors and hypermatrices derived from a network. We develop a new tensor
spectral co-clustering method that applies to any non-negative tensor of data.
The result of applying our method is a simultaneous clustering of the rows,
columns, and slices of a three-mode tensor, and the idea generalizes to any
number of modes. The algorithm we design works by recursively bisecting the
tensor into two pieces. We also design a new measure to understand the role of
each cluster in the tensor. Our new algorithm and pipeline are demonstrated in
both synthetic and real-world problems. On synthetic problems with a planted
higher-order cluster structure, our method is the only one that can reliably
identify the planted structure in all cases. On tensors based on n-gram text
data, we identify stop-words and semantically independent sets; on tensors from
an airline-airport multimodal network, we find worldwide and regional
co-clusters of airlines and airports; and on tensors from an email network, we
identify daily-spam and focused-topic sets.


title: The Exact SL(K+3,C) Symmetry of String Scattering Amplitudes

abstract:
  We discover that the 26D open bosonic string scattering amplitudes (SSA) of
three tachyons and one arbitrary string state can be expressed in terms of the
D-type Lauricella functions with associated SL(K+3,C) symmetry. As a result,
SSA and symmetries or relations among SSA of different string states at various
limits calculated previously can be rederived. These include the linear
relations conjectured by Gross [1-3] and proved in [4-9] in the hard scattering
limit, the recurrence relations in the Regge scattering limit [14-16] and the
extended recurrence relations in the nonrelativistic scattering limit [19]
discovered recently. Finally, as an application, we calculate a new recurrence
relation of SSA which is valid for all energies.


title: A Langevin model for complex cardiological time series

abstract:
  There has been considerable efforts to understand the underlying complex
dynamics in physiological time series. Methods originated from statistical
physics revealed a non-Gaussian statistics and long range correlations in those
signals. This suggests that the regulatory system operates out of equilibrium.
Herein the complex fluctuations in blood pressure time series were successful
described by physiological motivated Langevin equation under a sigmoid
restoring force with multiplicative noise.


title: Anomalous Hooke's law in disordered graphene

abstract:
  The discovery of graphene, a single monolayer of graphite, has closed the
discussion on stability of 2D crystals. Although thermal fluctuations of such
crystals tend to destroy the long-range order in the system, the crystal can be
stabilized by strong anharmonicity effects. This competition is the central
issue of the crumpling transition, i.e., a transition between flat and crumpled
phases. We show that anharmonicity-controlled fluctuations of a graphene
membrane around equilibrium flat phase lead to unusual elastic properties. In
particular, we demonstrate that stretching $\xi$ of a flake of graphene is a
nonlinear function of the applied tension at small tension:
${\xi\propto\sigma^{\eta/(2-\eta)}}$ and ${\xi\propto\sigma^{\eta/(8-\eta)}}$
for clean and strongly disordered graphene, respectively. Conventional linear
Hooke's law, ${\xi\propto\sigma}$ is realized at sufficiently large tensions:
${\sigma\gg\sigma_*},$ where $\sigma_*$ depends both on temperature and on the
disorder strength.


title: Weighted Rogers-Ramanujan Partitions and Dyson Crank

abstract:
  In this paper we refine a weighted partition identity of Alladi. We write
explicit formulas of generating functions for the number of partitions grouped
with respect to a partition statistic other than the norm. We tie our weighted
results and the different statistics with the crank of a partition. In
particular, we prove that the number of partitions into even number of distinct
parts whose odd-indexed parts' sum is n is equal to the number of partitions of
n with non-negative crank.


title: A Fast Randomized Algorithm for Multi-Objective Query Optimization

abstract:
  Query plans are compared according to multiple cost metrics in
multi-objective query optimization. The goal is to find the set of Pareto plans
realizing optimal cost tradeoffs for a given query. So far, only algorithms
with exponential complexity in the number of query tables have been proposed
for multi-objective query optimization. In this work, we present the first
algorithm with polynomial complexity in the query size.
  Our algorithm is randomized and iterative. It improves query plans via a
multi-objective version of hill climbing that applies multiple transformations
in each climbing step for maximal efficiency. Based on a locally optimal plan,
we approximate the Pareto plan set within the restricted space of plans with
similar join orders. We maintain a cache of Pareto-optimal plans for each
potentially useful intermediate result to share partial plans that were
discovered in different iterations. We show that each iteration of our
algorithm performs in expected polynomial time based on an analysis of the
expected path length between a random plan and local optima reached by hill
climbing. We experimentally show that our algorithm can optimize queries with
hundreds of tables and outperforms other randomized algorithms such as the
NSGA-II genetic algorithm over a wide range of scenarios.


title: Division Polynomials and Intersection of Projective Torsion Points

abstract:
  Given two elliptic curves, each of which is associated with a projection map
that identifies opposite elements with respect to the natural group structure,
we investigate how their corresponding projective images of torsion points
intersect.


title:
Iterative Phase Optimisation of Elementary Quantum Error Correcting
  Codes

abstract:
  Performing experiments on small-scale quantum computers is certainly a
challenging endeavor. Many parameters need to be optimized to achieve
high-fidelity operations. This can be done efficiently for operations acting on
single qubits as errors can be fully characterized. For multi-qubit operations,
though, this is no longer the case as in the most general case analyzing the
effect of the operation on the system requires a full state tomography for
which resources scale exponentially with the system size. Furthermore, in
recent experiments additional electronic levels beyond the two-level system
encoding the qubit have been used to enhance the capabilities of quantum
information processors, which additionally increases the number of parameters
that need to be controlled. For the optimization of the experimental system for
a given task (e.g.~a quantum algorithm), one has to find a satisfactory error
model and also efficient observables to estimate the parameters of the model.
In this manuscript we demonstrate a method to optimize the encoding procedure
for a small quantum error correction code in the presence of unknown but
constant phase shifts. The method, which we implement here on a small-scale
linear ion-trap quantum computer, is readily applicable to other AMO platforms
for quantum information processing.


title: Hyperk\"ahler fourfolds and Kummer surfaces

abstract:
  We show that a Hilbert scheme of conics on a Fano fourfold double cover of
$\mathbb{P}^2\times\mathbb{P}^2$ ramified along a divisor of bidegree $(2,2)$
admits a $\mathbb{P}^1$-fibration with base being a hyper-K\"{a}hler fourfold.
We investigate the geometry of such fourfolds relating them with degenerated
EPW cubes, with elements in the Brauer groups of $K3$ surfaces of degree $2$,
and with Verra threefolds studied in [Ver04]. These hyper-K\"{a}hler fourfolds
admit natural involutions and complete the classification of geometric
realizations of anti-symplectic involutions on hyper-K\"{a}hler $4$-folds of
type $K3^{[2]}$.
  As a consequence we present also three constructions of quartic Kummer
surfaces in $\mathbb{P}^3$: as Lagrangian and symmetric degeneracy loci and as
the base of a fibration of conics in certain threefold quadric bundles over
$\mathbb{P}^1$.


title:
Multi-pass oscillator layout for high-energy mode-locked thin-disk
  lasers

abstract:
  A novel optical layout for a multi-pass resonator is presented paving the way
for pulse energy scaling of mode-locked thin-disk lasers. The multi-pass
resonator we are proposing consists of a concatenation of nearly identical
optical segments. Each segment corresponds to a round-trip in an optically
stable cavity containing an active medium exhibiting soft aperture effects.
This scheme is apt for energy and power scaling because the stability region of
this multi-pass resonator contrarily to the 4f-based schemes does not shrink
with the number of passes. Simulation of the eigen-mode of this multi-segment
resonator requires considering aperture effects. This has been achieved by
implementing effective Gaussian apertures into the ABCD-matrix formalism as
lenses with imaginary focal length. We conclude proposing a simple way to
double the stability region of the state-of-the-art layouts used in industry
achievable by a minimal rearrangement of the used optical components.


title:
Quasi-two-dimensional metallic hydrogen inside di-phosphide at high
  pressure

abstract:
  The method of mathematical modeling was used for the calculation of the
structural, electronic, phonon, and other characteristics of various normal
phases of phosphorus hydrides with stoichiometry PHk. It was shown that the
di-phosphine may form 2D lattice of the metallic hydrogen, stabilized by
phosphorus atoms under high hydrostatic compressive pressure. The resulting
structure with the elements of H-P-H is a locally stable one in the phonon
spectrum (or metastable). The properties of di-phosphine with the properties of
similar structures such as thesulphur hydrides were compared.


title: Distributed Load Management Algorithms in Anycast-based CDNs

abstract:
  Anycast is an internet addressing protocol where multiple hosts share the
same IP-address. A popular architecture for modern Content Distribution
Networks (CDNs) for geo-replicated services consists of multiple layers of
proxy nodes for service and co-located DNS-servers for load-balancing among
different proxies. Both the proxies and the DNS-servers use anycast addressing,
which offers simplicity of design and high availability of service at the cost
of partial loss of routing control. Due to the very nature of anycast,
redirection actions by a DNS-server also affects loads at nearby proxies in the
network. This makes the problem of optimal distributed load management highly
challenging. In this paper, we propose and evaluate an analytical framework to
formulate and solve the load-management problem in this context. We consider
two distinct algorithms. In the first half of the paper, we pose the
load-management problem as a convex optimization problem. Following a
Kelly-type dual decomposition technique, we propose a fully-distributed
load-management algorithm by introducing FastControl packets. This algorithm
utilizes the underlying anycast mechanism itself to enable effective
coordination among the nodes, thus obviating the need for any external control
channel. In the second half of the paper, we consider an alternative greedy
load-management heuristic, currently in production in a major commercial CDN.
We study its dynamical characteristics and analytically identify its
operational and stability properties. Finally, we critically evaluate both the
algorithms and explore their optimality-vs-complexity trade-off using
trace-driven simulations.


title: On the computation of torus link homology

abstract:
  We introduce a new method for computing triply graded link homology, which is
particularly well-adapted to torus links. Our main application is to the
(n,n)-torus links, for which we give an exact answer for all n. In several
cases, our computations verify conjectures of Gorsky et al relating homology of
torus links with Hilbert schemes.


title: Collision model for non-Markovian quantum dynamics

abstract:
  We study the applicability of collisional models for non-Markovian dynamics
of open quantum systems. By allowing interactions between the separate
environmental degrees of freedom in between collisions we are able to construct
a collision model that allows to study quantum memory effects in open system
dynamics. We also discuss the possibility to embed non-Markovian collision
model dynamics into Markovian collision model dynamics in an extended state
space. As a concrete example we show how using the proposed class of collision
models we can discretely model non- Markovian amplitude damping of a qubit. In
the time-continuous limit, we obtain the well-known results for spontaneous
decay of a two level system in to a structured zero-temperature reservoir


title: Coherent cavity-enhanced dual-comb spectroscopy

abstract:
  Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of
high-resolution spectra without the need for moving parts or low-resolution
dispersive optics. This method of broadband spectroscopy is most often
accomplished via tight phase locking of two mode-locked lasers or via
sophisticated signal processing algorithms, and therefore, long integration
times of phase coherent signals are difficult to achieve. Here we demonstrate
an alternative approach to dual-comb spectroscopy using two phase modulator
combs originating from a single continuous-wave laser capable of > 2 hours of
coherent real-time averaging. The dual combs were generated by driving the
phase modulators with step-recovery diodes where each comb consisted of > 250
teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared.
The step-recovery diodes are passive devices that provide low-phase-noise
harmonics for efficient coupling into an enhancement cavity at picowatt optical
powers. With this approach, we demonstrate the sensitivity to simultaneously
monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at
a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely
tunable dual-comb systems could enable a network of distributed multiplexed
optical sensors.


title: A universal property for sequential measurement

abstract:
  We study the sequential product, the operation $p * q = \sqrt{p} q \sqrt{p}$
on the set of effects of a von Neumann algebra that represents sequential
measurement of first $p$ and then $q$. We give four axioms which completely
determine the sequential product.


title: On the stability of regular algebras

abstract:
  We characterize which quadratic regular algebras of global dimension 3 are
stable in the sense of Behrend-Noohi. (This notion of stability is a
non-commutative analogue of Hilbert stability.) We describe the
quasi-projective stack of stable quadratic regular algebras of dimension 3.
This provides the first non-trivial, non-commutative examples of stability a la
Behrend-Noohi.


title:
A targeted spectral interpolation algorithm for the detection of
  continuous gravitational waves

abstract:
  We present an improved method of targeting continuous gravitational-wave
signals in data from the LIGO and Virgo detectors with a higher efficiency than
the time-domain Bayesian pipeline used in many previous searches. Our spectral
interpolation algorithm, SplInter, removes the intrinsic phase evolution of the
signal from source rotation and relative detector motion. We do this in the
frequency domain and generate a time series containing only variations in the
signal due to the antenna pattern. Although less flexible than the classic
heterodyne approach, SplInter allows for rapid analysis of putative signals
from isolated (and some binary) pulsars, and efficient follow-up searches for
candidate signals generated by other search methods. The computational saving
over the heterodyne approach can be many orders of magnitude, up to a factor of
around fifty thousand in some cases, with a minimal impact on overall
sensitivity for most targets.


title:
Observations of $\Lambda_b^0 \to \Lambda K^+\pi^-$ and $\Lambda_b^0 \to
  \Lambda K^+K^-$ decays and searches for other $\Lambda_b^0$ and $\Xi_b^0$
  decays to $\Lambda h^+h^{\prime -}$ final states

abstract:
  A search is performed for the charmless three-body decays of the
$\Lambda_b^0$ and $\Xi_b^0$ baryons to the final states $\Lambda h^+h^{\prime
-}$, where $h^{(\prime)} = \pi$ or $K$. The analysis is based on a data sample,
corresponding to an integrated luminosity of $3 \rm fb^{-1}$ of $pp$
collisions, collected by the LHCb experiment. The $\Lambda_b^0 \to \Lambda
K^+\pi^-$ and $\Lambda_b^0 \to \Lambda K^+K^-$ decays are observed for the
first time and their branching fractions and $CP$ asymmetry parameters are
measured. Evidence is seen for the $\Lambda_b^0 \to \Lambda \pi^+\pi^-$ decay
and limits are set on the branching fractions of $\Xi_b^0$ baryon decays to the
$\Lambda h^+h^{\prime -}$ final states.


title:
On the origin of the sub-Jovian desert in the
  orbital-period--planetary-mass plane

abstract:
  Transit and radial velocity observations indicate a dearth of
sub-Jupiter--mass planets on short-period orbits, outlined roughly by two
oppositely sloped lines in the period--mass plane. We interpret this feature in
terms of high-eccentricity migration of planets that arrive in the vicinity of
the Roche limit, where their orbits are tidally circularized, long after the
dispersal of their natal disk. We demonstrate that the two distinct segments of
the boundary are a direct consequence of the different slopes of the empirical
mass--radius relation for small and large planets, and show that this relation
also fixes the mass coordinate of the intersection point. The period coordinate
of this point, as well as the detailed shape of the lower boundary, can be
reproduced with a plausible choice of a key parameter in the underlying
migration model. The detailed shape of the upper boundary, on the other hand,
is determined by the post-circularization tidal exchange of angular momentum
with the star and can be reproduced with a stellar tidal quality factor
$Q^\prime_*\sim10^6$.


title:
Transcranial Focused Ultrasound for BOLD fMRI Signal Modulation in
  Humans

abstract:
  Transcranial focused ultrasound (tFUS) is an emerging form of non-surgical
human neuromodulation that confers advantages over existing electro and
electromagnetic technologies by providing a superior spatial resolution on the
millimeter scale as well as the capability to target sub-cortical structures
non-invasively. An examination of the pairing of tFUS and blood oxygen level
dependent (BOLD) functional MRI (fMRI) in humans is presented here.


title: Scattering diagrams, Hall algebras and stability conditions

abstract:
  To any quiver with relations we associate a consistent scattering diagram
taking values in the motivic Hall algebra of its category of representations.
We show that the chamber structure of this scattering diagram coincides with
the natural chamber structure in an open subset of the space of stability
conditions on the associated triangulated category. In the three-dimensional
Calabi-Yau situation, when the relations arise from a potential, we can apply
an integration map to give a consistent scattering diagram taking values in a
tropical vertex group.


title: Degree bounds for semi-invariant rings of quivers

abstract:
  We use recent results on matrix semi-invariants to give degree bounds on
generators for the ring of semi-invariants for quivers with no oriented cycles.


title: Visualizing source code in 3D Maya software

abstract:
  In this paper is clarify the summaries codes for programmers through
three-dimensional shapes, and clearly programmers and developers, scholars and
researchers in the field of software engineering, as well as researchers from
the representative about threedimensional forms. Through a three-dimensional
drawing on a Maya scripts which are based on drawing shapes and
three-dimensional stereoscopic show every part of the code, for example,
classes, methods, coherence and homogeneity , In these drawings and show
clearly and useful.


title:
K2 Rotation Periods for low-mass Hyads and the Implications for
  Gyrochronology

abstract:
  As the closest open cluster to the Sun, the Hyades is an important benchmark
for many stellar properties, but its members are also scattered widely over the
sky. Previous studies of stellar rotation in the Hyades relied on targeted
observations of single stars or data from shallower all-sky variability
surveys. The re-purposed Kepler mission, K2, is the first opportunity to
measure rotation periods ($P_{rot}$) for many Hyads simultaneously while also
being sensitive to fully convective M dwarf members. We analyze K2 data for 65
Hyads and present $P_{rot}$ values for 48. Thirty-seven of these are new
measurements, including the first $P_{rot}$ measurements for fully convective
Hyads. For nine of the 11 stars with $P_{rot}$ in the literature and this work,
the measurements are consistent; we attribute the two discrepant cases to spot
evolution. Nearly all stars with masses $\le0.3M_\odot$ are rapidly rotating,
indicating a change in rotation properties at the boundary to full convection.
When confirmed and candidate binaries are removed from the mass-period plane,
only three rapid rotators with masses $\ge0.3M_\odot$ remain. This is in
contrast to previous results showing that the single-valued mass-period
sequence for $\approx$600 Myr-old stars ends at $\approx0.65M_\odot$ when
binaries are included. We also find that models of rotational evolution predict
faster rotation than is actually observed at $\approx$600 Myrs for stars
$\le0.9M_\odot$. The dearth of single rapid rotators more massive than
$\approx0.3M_\odot$ indicates that magnetic braking is more efficient than
previously thought, and that age-rotation studies must account for
multiplicity.


title: Generalizations of polylogarithms for Feynman integrals

abstract:
  In this talk, we discuss recent progress in the application of
generalizations of polylogarithms in the symbolic computation of multi-loop
integrals. We briefly review the Maple program MPL which supports a certain
approach for the computation of Feynman integrals in terms of multiple
polylogarithms. Furthermore we discuss elliptic generalizations of
polylogarithms which have shown to be useful in the computation of the massive
two-loop sunrise integral.


title:
Ionic liquid-based variable focus electrowetting optics with bandwidths
  spanning the visible to mid-infrared

abstract:
  Infrared optical materials and devices are important for a wide range of
applications in the defense, scientific, and consumer markets. For imaging,
spectroscopy, microscopy and persistent surveillance, adaptive optic systems
that span the visible to infrared region are particularly useful. We address
this need with novel electrowetting lens and prism elements that operate from
400 to 5000 nm. In contrast to conventional electrowetting devices that use
polar liquids, limited by high absorption in the infrared region, we present
room-temperature ionic liquid-based (RTIL, N-Propyl-Nmethylpyrrolidinium
Bis(fluorosulfonyl)imide, Pyr1333a, Solvionic) lens and prism elements with
unprecedented spectral bandwidths. Our electrowetting lenses tune over 20
diopters and have been demonstrated at 588, 1550 and 3000 nm wavelengths.
Additionally, we have demonstrated prism elements with a steering angle of
0.56{\deg} at 1550 nm.


title:
A rheological signature of frictional interactions in shear thickening
  suspensions

abstract:
  Colloidal shear thickening presents a significant challenge because the
macroscopic rheology becomes increasingly controlled by the microscopic details
of short ranged particle interactions in the shear thickening regime. Our
measurements here of the first normal stress difference over a wide range of
particle volume fraction elucidate the relative contributions from hydrodynamic
lubrication and frictional contact forces, which have been debated. At moderate
volume fractions we find $N_1<0$, consistent with hydrodynamic models, however
at higher volume fractions and shear stresses these models break down and we
instead observe dilation ($N_1>0$), indicating frictional contact networks.
Remarkably, there is no signature of this transition in the viscosity, instead
this change in the sign of $N_1$ occurs while the shear thickening remains
continuous. These results suggest a scenario where shear thickening is driven
primarily by the formation of frictional contacts, with hydrodynamic forces
playing a supporting role at lower concentrations. Motivated by this picture,
we introduce a simple model which combines these frictional and hydrodynamic
contributions and accurately fits the measured viscosity over a wide range of
particle volume fraction and shear stress.


title:
Quantifying the vanishing gradient and long distance dependency problem
  in recursive neural networks and recursive LSTMs

abstract:
  Recursive neural networks (RNN) and their recently proposed extension
recursive long short term memory networks (RLSTM) are models that compute
representations for sentences, by recursively combining word embeddings
according to an externally provided parse tree. Both models thus, unlike
recurrent networks, explicitly make use of the hierarchical structure of a
sentence. In this paper, we demonstrate that RNNs nevertheless suffer from the
vanishing gradient and long distance dependency problem, and that RLSTMs
greatly improve over RNN's on these problems. We present an artificial learning
task that allows us to quantify the severity of these problems for both models.
We further show that a ratio of gradients (at the root node and a focal leaf
node) is highly indicative of the success of backpropagation at optimizing the
relevant weights low in the tree. This paper thus provides an explanation for
existing, superior results of RLSTMs on tasks such as sentiment analysis, and
suggests that the benefits of including hierarchical structure and of including
LSTM-style gating are complementary.


title: Convergence along mean flows

abstract:
  We develop a technique of multiple scale asymptotic expansions along mean
flows and a corresponding notion of weak multiple scale convergence. These are
applied to homogenize convection dominated parabolic equations with rapidly
oscillating, locally periodic coefficients and $\mathcal{O}(\eps^{-1})$ mean
convection term. Crucial to our analysis is the introduction of a fast time
variable, $\tau=\frac{t}{\eps}$, not apparent in the heterogeneous problem. The
effective diffusion coefficient is expressed in terms of the average of
Eulerian cell solutions along the orbits of the mean flow in the fast time
variable. To make this notion rigorous, we use the theory of ergodic algebras
with mean value.


title:
Strong enhancement of superconductivity at high pressures within the
  charge-density-wave states of 2H-TaS 2 and 2H-TaSe 2

abstract:
  We present measurements of the superconducting and charge density wave
critical temperatures (Tc and TCDW) as a function of pressure in the transition
metal dichalchogenides 2H-TaSe2 and 2H-TaS2. Resistance and susceptibility
measurements show that Tc increases from temperatures below 1 K up to 8.5 K at
9.5 GPa in 2H-TaS2 and 8.2 K at 23 GPa in 2H-TaSe2. We observe a kink in the
pressure dependence of TCDW at about 4 GPa that we attribute to the lock-in
transition from incommensurate CDW to commensurate CDW. Above this pressure,
the commensurate TCDW slowly decreases coexisting with superconductivity within
our full pressure range.


title: Finite noncommutative geometries related to $F_p[x]$

abstract:
  It is known that irreducible noncommutative differential structures over
$\Bbb F_p[x]$ are classified by irreducible monics $m$. We show that the
cohomology $H_{\rm dR}^0(\Bbb F_p[x]; m)=\Bbb F_p[g_d]$ if and only if ${\rm
Tr}(m)\ne 0$, where $g_d=x^{p^d}-x$ and $d$ is the degree of $m$. This implies
that there are ${p-1\over pd}\sum_{k|d, p\nmid k}\mu_M(k)p^{d\over k}$ such
noncommutative differential structures ($\mu_M$ the M\"obius function).
Motivated by killing this zero'th cohomology, we consider the directed system
of finite-dimensional Hopf algebras $A_d=\Bbb F_p[x]/(g_d)$ as well as their
inherited bicovariant differential calculi $\Omega(A_d;m)$. We show that
$A_d=C_d\otimes_\chi A_1$ a cocycle extension where $C_d=A_d^\psi$ is the
subalgebra of elements fixed under $\psi(x)=x+1$. We also have a
Frobenius-fixed subalgebra $B_d$ of dimension $\frac{1}{d} \sum_{k | d} \phi(k)
p^\frac{d}{k}$ ($\phi$ the Euler totient function), generalising Boolean
algebras when $p=2$. As special cases, $A_1\cong \Bbb F_p(\Bbb Z/p\Bbb Z)$, the
algebra of functions on the finite group $\Bbb Z/p\Bbb Z$, and we show dually
that $\Bbb F_p\Bbb Z/p\Bbb Z\cong\Bbb F_p[L]/(L^p)$ for a `Lie algebra'
generator $L$ with $e^L$ group-like, using a truncated exponential. By
contrast, $A_2$ over $\Bbb F_2$ is a cocycle modification of $\Bbb F_2((\Bbb
Z/2\Bbb Z)^2)$ and is a 1-dimensional extension of the Boolean algebra on 3
elements. In both cases we compute the Fourier theory, the invariant metrics
and the Levi-Civita connections within bimodule noncommutative geometry.


title:
A Nonlinear Adaptive Filter Based on the Model of Simple Multilinear
  Functionals

abstract:
  Nonlinear adaptive filtering allows for modeling of some additional aspects
of a general system and usually relies on highly complex algorithms, such as
those based on the Volterra series. Through the use of the Kronecker product
and some basic facts of tensor algebra, we propose a simple model of
nonlinearity, one that can be interpreted as a product of the outputs of K FIR
linear filters, and compute its cost function together with its gradient, which
allows for some analysis of the optimization problem. We use these results it
in a stochastic gradient framework, from which we derive an LMS-like algorithm
and investigate the problems of multi-modality in the mean-square error surface
and the choice of adequate initial conditions. Its computational complexity is
calculated. The new algorithm is tested in a system identification setup and is
compared with other polynomial algorithms from the literature, presenting
favorable convergence and/or computational complexity.


title:
Transition waves for Fisher-KPP equations with general
  time-heterogeneous and space-periodic coefficients

abstract:
  This paper is devoted to existence and non-existence results for generalized
tran-sition waves solutions of space-time heterogeneous Fisher-KPP equations.
When the coefficients of the equation are periodic in space but otherwise
depend in a fairly gen-eral fashion on time, we prove that such waves exist as
soon as their speed is sufficiently large in a sense. When this speed is too
small, transition waves do not exist anymore, this result holds without
assuming periodicity in space. These necessary and sufficient conditions are
proved to be optimal when the coefficients are periodic both in space and time.
Our method is quite robust and extends to general non-periodic space-time
heterogeneous coefficients, showing that transition waves solutions of the
nonlinear equation exist as soon as one can construct appropriate solutions of
a given linearized equation.


title:
The impact of source terms in the variational representation of traffic
  flow

abstract:
  This paper revisits the variational theory of traffic flow, now under the
presence of continuum lateral inflows and outflows to the freeway say Eulerian
source terms. It is found that a VT solution exists only in Eulerian
coordinates when source terms are exogenous meaning that they only depend on
time and space, but not when they are a function of traffic conditions, as per
a merge model. In discrete time, however, these dependencies become exogenous,
which allowed us to propose improved numerical solution methods. In Lagrangian
and vehicle number-space coordinates, VT solutions may not exist even if source
terms are exogenous.


title:
Spreading speeds for one-dimensional monostable reaction-diffusion
  equations

abstract:
  We establish in this article spreading properties for the solutions of
equations of the type $\partial$ t u -- a(x)$\partial$ xx u -- q(x)$\partial$ x
u = f (x, u), where a, q, f are only assumed to be uniformly continuous and
bounded in x, the nonlinearity f is of monostable KPP type between two steady
states 0 and 1 and the initial datum is compactly sup-ported. Using
homogenization techniques, we construct two speeds w $\le$ w such that lim
t$\rightarrow$+$\infty$ sup 0$\le$x$\le$wt |u(t, x)--1| = 0 for all w $\in$ (0,
w) and lim t$\rightarrow$+$\infty$ sup x$\ge$wt |u(t, x)| = 0 for all w
\textgreater{} w. These speeds are characterized in terms of two new notions of
generalized principal eigenvalues for linear elliptic operators in unbounded
domains. In particu-lar, we derive the exact spreading speed when the
coefficients are random stationary ergodic, almost periodic or asymptotically
almost periodic (where w = w).


title: On GitHub's Programming Languages

abstract:
  GitHub is the most widely used social, distributed version control system. It
has around 10 million registered users and hosts over 16 million public
repositories. Its user base is also very active as GitHub ranks in the top 100
Alexa most popular websites. In this study, we collect GitHub's state in its
entirety. Doing so, allows us to study new aspects of the ecosystem. Although
GitHub is the home to millions of users and repositories, the analysis of
users' activity time-series reveals that only around 10% of them can be
considered active. The collected dataset allows us to investigate the
popularity of programming languages and existence of pattens in the relations
between users, repositories, and programming languages.
  By, applying a k-means clustering method to the users-repositories commits
matrix, we find that two clear clusters of programming languages separate from
the remaining. One cluster forms for "web programming" languages (Java Script,
Ruby, PHP, CSS), and a second for "system oriented programming" languages (C,
C++, Python). Further classification, allow us to build a phylogenetic tree of
the use of programming languages in GitHub. Additionally, we study the main and
the auxiliary programming languages of the top 1000 repositories in more
detail. We provide a ranking of these auxiliary programming languages using
various metrics, such as percentage of lines of code, and PageRank.


title:
Deviation inequalities for Banach space valued martingales differences
  sequences and random field

abstract:
  We establish deviation inequalities for the maxima of partial sums of a
martingale differences sequence, and of a strictly stationary orthomartingale
random field. These inequalities can be used to establish complete convergence
of normalized maxima of partial sums.


title: Non-Abelian Monopoles as the Origin of Dark Matter

abstract:
  We suggest that dark matter may be partially constituted by a dilute 't
Hooft-Polyakov monopoles gas. We reach this conclusion by using the
Georgi-Glashow model coupled to a dual kinetic mixing term $ F{\tilde {\cal
G}}$ where $F$ is the electromagnetic field and ${\cal G}$ the 't Hooft tensor.
We show that these monopoles carry both (Maxwell) electric and (Georgi-Glashow)
magnetic charges and the electric charge quantization condition is modified in
terms of a dimensionless real parameter. This parameter could be determined
from milli-charged particle experiments.


title:
Probing superfluidity in a quasi two-dimensional Bose gas through its
  local dynamics

abstract:
  We report direct evidence of superfluidity in a quasi two-dimensional Bose
gas by observing its dynamical response to a collective excitation. Relying on
a novel local correlation analysis, we are able to probe inhomogeneous clouds
and reveal their local dynamics. We identify in this way the superfluid and
thermal phases inside the gas and locate the boundary at which the
Berezinskii--Kosterlitz--Thouless crossover occurs. This new analysis also
allows to evidence the coupling of the two fluids which induces at finite
temperatures damping rates larger than the usual Landau damping.


title: Quadratic and pinczon algebras

abstract:
  Given a symmetric non degenerated bilinear form b on a vector space V, G.
Pinczon and R. Ushirobira defined a bracket {,} on the space of multilinear
skewsymmetric forms on V. With this bracket, the quadratic Lie algebra
structure equation on (V, b) becomes simply {\^a, \^a} = 0. We characterize
similarly quadratic associative, commutative or pre-Lie structures on (V, b) by
the same equation {\^a, \^a} = 0, but on different spaces of forms. These
definitions extend to quadratic up to homotopy algebras and allows to describe
the corresponding cohomologies.


title: An above-barrier narrow resonance in $^{15}$F

abstract:
  Intense and purified radioactive beam of post-accelerated $^{14}$O was used
to study the low-lying states in the unbound $^{15}$F nucleus. Exploiting
resonant elastic scattering in inverse kinematics with a thick target, the
second excited state, a resonance at E$\_R$=4.757(6)(10)~MeV with a width of
$\Gamma$=36(5)(14)~keV was measured for the first time with high precision. The
structure of this narrow above-barrier state in a nucleus located two neutrons
beyond the proton drip line was investigated using the Gamow Shell Model in the
coupled channel representation with a $^{12}$C core and three valence protons.
It is found that it is an almost pure wave function of two quasi-bound protons
in the $2s\_{1/2}$ shell.


title:
Technical Report: Band selection for nonlinear unmixing of hyperspectral
  images as a maximal clique problem

abstract:
  Kernel-based nonlinear mixing models have been applied to unmix spectral
information of hyperspectral images when the type of mixing occurring in the
scene is too complex or unknown. Such methods, however, usually require the
inversion of matrices of sizes equal to the number of spectral bands. Reducing
the computational load of these methods remains a challenge in large scale
applications. This paper proposes a centralized method for band selection (BS)
in the reproducing kernel Hilbert space (RKHS). It is based upon the coherence
criterion, which sets the largest value allowed for correlations between the
basis kernel functions characterizing the unmixing model. We show that the
proposed BS approach is equivalent to solving a maximum clique problem (MCP),
that is, searching for the biggest complete subgraph in a graph. Furthermore,
we devise a strategy for selecting the coherence threshold and the Gaussian
kernel bandwidth using coherence bounds for linearly independent bases.
Simulation results illustrate the efficiency of the proposed method.


title:
Convolutional Patch Representations for Image Retrieval: an Unsupervised
  Approach

abstract:
  Convolutional neural networks (CNNs) have recently received a lot of
attention due to their ability to model local stationary structures in natural
images in a multi-scale fashion, when learning all model parameters with
supervision. While excellent performance was achieved for image classification
when large amounts of labeled visual data are available, their success for
un-supervised tasks such as image retrieval has been moderate so far. Our paper
focuses on this latter setting and explores several methods for learning patch
descriptors without supervision with application to matching and instance-level
retrieval. To that effect, we propose a new family of convolutional descriptors
for patch representation , based on the recently introduced convolutional
kernel networks. We show that our descriptor, named Patch-CKN, performs better
than SIFT as well as other convolutional networks learned by artificially
introducing supervision and is significantly faster to train. To demonstrate
its effectiveness, we perform an extensive evaluation on standard benchmarks
for patch and image retrieval where we obtain state-of-the-art results. We also
introduce a new dataset called RomePatches, which allows to simultaneously
study descriptor performance for patch and image retrieval.


title: Origin of the Lyman excess in early-type stars

abstract:
  Ionized regions around early-type stars are believed to be well-known
objects, but until recently, our knowledge of the relation between the
free-free radio emission and the IR emission has been observationally hindered
by the limited angular resolution in the far-IR. The advent of Herschel has now
made it possible to obtain a more precise comparison between the two regimes,
and it has been found that about a third of the young HII regions emit more
Lyman continuum photons than expected, thus presenting a Lyman excess. With the
present study we wish to distinguish between two scenarios that have been
proposed to explain the existence of the Lyman excess: (i) underestimation of
the bolometric luminosity, or (ii) additional emission of Lyman-continuum
photons from an accretion shock. We observed an outflow (SiO) and an infall
(HCO+) tracer toward a complete sample of 200 HII regions, 67 of which present
the Lyman excess. Our goal was to search for any systematic difference between
sources with Lyman excess and those without. While the outflow tracer does not
reveal any significant difference between the two subsamples of HII regions,
the infall tracer indicates that the Lyman-excess sources are more associated
with infall signposts than the other objects. Our findings indicate that the
most plausible explanation for the Lyman excess is that in addition to the
Lyman continuum emission from the early-type star, UV photons are emitted from
accretion shocks in the stellar neighbourhood. This result suggests that
high-mass stars and/or stellar clusters containing young massive stars may
continue to accrete for a long time, even after the development of a compact
HII region.


title: Quasilocal charges in integrable lattice systems

abstract:
  We review recent progress in understanding the notion of locality in
integrable quantum lattice systems. The central concept are the so-called
quasilocal conserved quantities, which go beyond the standard perception of
locality. Two systematic procedures to rigorously construct families of
quasilocal conserved operators based on quantum transfer matrices are outlined,
specializing on anisotropic Heisenberg XXZ spin-1/2 chain. Quasilocal conserved
operators stem from two distinct classes of representations of the auxiliary
space algebra, comprised of unitary (compact) representations, which can be
naturally linked to the fusion algebra and quasiparticle content of the model,
and non-unitary (non-compact) representations giving rise to charges,
manifestly orthogonal to the unitary ones. Various condensed matter
applications in which quasilocal conservation laws play an essential role are
presented, with special emphasis on their implications for anomalous transport
properties (finite Drude weight) and relaxation to non-thermal steady states in
the quantum quench scenario.

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


title: Crowdsourcing On-street Parking Space Detection

abstract:
  As the number of vehicles continues to grow, parking spaces are at a premium
in city streets. Additionally, due to the lack of knowledge about street
parking spaces, heuristic circling the blocks not only costs drivers' time and
fuel, but also increases city congestion. In the wake of recent trend to build
convenient, green and energy-efficient smart cities, we rethink common
techniques adopted by high-profile smart parking systems, and present a
user-engaged (crowdsourcing) and sonar-based prototype to identify urban
on-street parking spaces. The prototype includes an ultrasonic sensor, a GPS
receiver and associated Arduino micro-controllers. It is mounted on the
passenger side of a car to measure the distance from the vehicle to the nearest
roadside obstacle. Multiple road tests are conducted around Wheatley, Oxford to
gather results and emulate the crowdsourcing approach. By extracting parked
vehicles' features from the collected trace, a supervised learning algorithm is
developed to estimate roadside parking occupancy and spot illegal parking
vehicles. A quantity estimation model is derived to calculate the required
number of sensing units to cover urban streets. The estimation is
quantitatively compared to a fixed sensing solution. The results show that the
crowdsourcing way would need substantially fewer sensors compared to the fixed
sensing system.


title: Role of short-term dispersal on the dynamics of Zika virus

abstract:
  In November 2015, El Salvador reported their first case of Zika virus (Zv)
leading to an explosive outbreak that in just two months had over 6000
suspected cases. Many communities along with national agencies initiated the
process to implement control measures that ranged from vector control and the
use of repellents to the suggestion of avoiding pregnancies for two years, the
latter one, in response to the growing number of microcephaly cases in Brazil.
In our study, we explore the impact of short term mobility between two
idealized interconnected communities where disparities and violence contribute
to the Zv epidemic. Using a Lagrangian modeling approach in a two-patch
setting, it is shown via simulations that short term mobility may be beneficial
in the control of a Zv outbreak when risk is relative low and patch disparities
are not too extreme. However, when the reproductive number is too high, there
seems to be no benefits. This paper is dedicated to the inauguration of the
Centro de Modelamiento Matem\'{a}tico Carlos Castillo-Ch\'{a}vez at Universidad
Francisco Gavidia in San Salvador, El Salvador.


title: Mobile N\'eel skyrmions at room temperature: status and future

abstract:
  Magnetic skyrmions are topologically protected spin textures that exhibit
many fascinating features. As compared to the well-studied cryogenic Bloch
skyrmions in bulk materials, we focus on the room-temperature N\'eel skyrmions
in thin-film systems with an interfacial broken inversion symmetry in this
article. Specifically, we show the stabilization, the creation, and the
implementation of N\'eel skyrmions that are enabled by the electrical
current-induced spin-orbit torques. Towards the nanoscale N\'eel skyrmions, we
further discuss the challenges from both material optimization and imaging
characterization perspectives.


title: On divergences tests for composite hypotheses under composite likelihood

abstract:
  It is well-known that in some situations it is not easy to compute the
likelihood function as the datasets might be large or the model is too complex.
In that contexts composite likelihood, derived by multiplying the likelihoods
of subjects of the variables, may be useful. The extension of the classical
likelihood ratio test statistics to the framework of composite likelihoods is
used as a procedure to solve the problem of testing in the context of composite
likelihood. In this paper we introduce and study a new family of test
statistics for composite likelihood: Composite {\phi}-divergence test
statistics for solving the problem of testing a simple null hypothesis or a
composite null hypothesis. To do that we introduce and study the asymptotic
distribution of the restricted maximum composite likelihood estimate.


title: Axisymmetric equilibria with pressure anisotropy and plasma flow

abstract:
  A generalised Grad-Shafranov equation that governs the equilibrium of an
axisymmetric toroidal plasma with anisotropic pressure and incompressible flow
of arbitrary direction is derived. This equation includes six free surface
functions and recovers known Grad-Shafranov-like equations in the literature as
well as the usual static, isotropic one. The form of the generalised equation
indicates that pressure anisotropy and flow act additively on equilibrium. In
addition, two sets of analytical solutions, an extended Solovev one with a
plasma reaching the separatrix and an extended Hernegger-Maschke one for a
plasma surrounded by a fixed boundary possessing an X-point, are constructed,
particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the
impacts both of pressure anisotropy and plasma flow on these equilibria are
examined. It turns out that depending on the maximum value and the shape of an
anisotropy function, the anisotropy can act either paramagnetically or
diamagnetically. Also, in most of the cases considered both the anisotropy and
the flow have stronger effects on NSTX equilibria than on ITER ones.


title: Covariant perturbation expansion of off-diagonal heat kernel

abstract:
  Covariant perturbation expansion is an important method in quantum field
theory. In this paper an expansion up to arbitrary order for off-diagonal heat
kernels in flat space based on the covariant perturbation expansion is given.
In literature, only diagonal heat kernels are calculated based on the covariant
perturbation expansion.

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


title: BPS Boojums in N=2 supersymmetric gauge theories I

abstract:
  We study 1/4 Bogomol'nyi-Prasad-Sommerfield (BPS) composite solitons of
vortex strings, domain walls and boojums in ${\cal N}=2$ supersymmetric Abelian
gauge theories in four dimensions. We obtain solutions to the 1/4 BPS equations
with the finite gauge coupling constant. To obtain numerical solutions for
generic coupling constants, we construct globally correct approximate functions
which allow us to easily find fixed points of gradient flow equations. We
analytically/numerically confirm that the negative mass of a single boojum
appearingat the endpoint of the vortex string on the logarithmically bent
domain wall is equal to the half-mass of the 't Hooft-Polyakov monopole. We
examine various configurations and clarify how the shape of the boojum depends
on the coupling constants and moduli parameters. We also find analytic
solutions to the 1/4 BPS equations for specific values of the coupling
constants.


title:
Guided Cost Learning: Deep Inverse Optimal Control via Policy
  Optimization

abstract:
  Reinforcement learning can acquire complex behaviors from high-level
specifications. However, defining a cost function that can be optimized
effectively and encodes the correct task is challenging in practice. We explore
how inverse optimal control (IOC) can be used to learn behaviors from
demonstrations, with applications to torque control of high-dimensional robotic
systems. Our method addresses two key challenges in inverse optimal control:
first, the need for informative features and effective regularization to impose
structure on the cost, and second, the difficulty of learning the cost function
under unknown dynamics for high-dimensional continuous systems. To address the
former challenge, we present an algorithm capable of learning arbitrary
nonlinear cost functions, such as neural networks, without meticulous feature
engineering. To address the latter challenge, we formulate an efficient
sample-based approximation for MaxEnt IOC. We evaluate our method on a series
of simulated tasks and real-world robotic manipulation problems, demonstrating
substantial improvement over prior methods both in terms of task complexity and
sample efficiency.


title:
Universal Spin Hall Conductance Fluctuations in Chaotic Dirac Quantum
  Dots

abstract:
  We present complete analytical and numerical results that demonstrate the
anomalous universal fluctuations of the spin-Hall conductance in chiral
materials such as graphene and topological insulators. We investigated both the
corresponding fluctuations, the Universal Fractionated and the Universal
Quantized, and also the open channels orbital number crossover between the two
regimes. In particular, we show that the Wigner-Dyson symmetries does not
properly describe such conductances and the preponderant role of the chiral
classes on the Dirac quantum dots. The results are analytical and solve
outstanding issues.


title:
Polarization and valley switching in monolayer group-IV
  monochalcogenides

abstract:
  Group-IV monochalcogenides are a family of two-dimensional puckered materials
with an orthorhombic structure that is comprised of polar layers. In this
article, we use first principles calculations to show the multistability of
monolayer SnS and GeSe, two prototype materials where the direction of the
puckering can be switched by application of tensile stress or electric field.
Furthermore, the two inequivalent valleys in momentum space, which are dictated
by the puckering orientation, can be excited selectively using linearly
polarized light, and this provides an additional tool to identify the
polarization direction. Our findings suggest that SnS and GeSe monolayers may
have observable ferroelectricity and multistability, with potential
applications in information storage.


title:
Two classes of organization principle: quantum/topological phase
  transitions meet complete/in-complete devil staircases and their experimental
  realizations

abstract:
  There exists many quantum or topological phases in Nature. One well known
organization principle is through various quantum or topological phases
transitions between or among these phases. Another is through either complete
or in-complete devil staircases in their quantized forms. Here, we show that
both classes of organization principle appear in an experimentally accessible
system: strongly interacting spinor bosons subject to any of the linear
combinations of the Rashba and Dresselhaus spin-orbit coupling (SOC) in the
space of the two SOC parameters $ ( \alpha, \beta) $ in a square lattice. In
the strong coupling limit, it leads to a new quantum spin model called Rotated
Ferromagnetic Heisenberg model (RFHM). The RFHM leads to rich and
unconventional magnetic phases even in a bipartite lattice. For the first
class, by identifying a suitable low energy mode, we investigate a new quantum
Lifshitz transition from the Y-x to the IC-SkX-y phase. For the second class,
we introduce the topological rational and irrational winding numbers $ W $ to
characterize the incomplete or complete devil staircases and also perform their
quantizations. The IC-YZ-x/LQx phases form a Cantor set with a fractal
dimension along the complete devil staircase. They also take most of measures
in the incomplete devil staircases when $ \beta \ll \alpha $. Quantum chaos and
quantum information scramblings along the diagonal line $ \alpha=\beta $ are
discussed. Implications on un-conventional magnetic ordered phases detected in
the 4d- or 5d-orbital strongly correlated materials with SOC and in the current
or near future cold atom systems are presented.


title: On homology of complements of compact sets in Hilbert Cube

abstract:
  We introduce the notion of spaces with weak relative cohomology and show the
acyclicity of the complement $Q\setminus X$ in the Hilbert cube $Q$ of a
compactum $X$ with weak relative cohomology. As a corollary we obtain the
acyclicity of the complement results when
  (a) $X$ is weakly infinite dimensional;
  (b) $X$ has finite cohomological dimension.


title: Disordered Quivers and Cold Horizons

abstract:
  We analyze the low temperature structure of a supersymmetric quiver quantum
mechanics with randomized superpotential coefficients, treating them as
quenched disorder. These theories describe features of the low energy dynamics
of wrapped branes, which in large number backreact into extremal black holes.
We show that the low temperature theory, in the limit of a large number of
bifundamentals, exhibits a time reparametrization symmetry as well as a
specific heat linear in the temperature. Both these features resemble the
behavior of black hole horizons in the zero temperature limit. We demonstrate
similarities between the low temperature physics of the random quiver model and
a theory of large $N$ free fermions with random masses.


title:
There are no intermediate structures between the group of integers and
  Presburger arithmetic

abstract:
  We show that if a first-order structure $\mathcal{M}$, with universe
$\mathbb{Z}$, is an expansion of $(\mathbb{Z},+,0)$ and a reduct of
$(\mathbb{Z},+,<,0)$, then $\mathcal{M}$ must be interdefinable with
$(\mathbb{Z},+,0)$ or $(\mathbb{Z},+,<,0)$.


title:
Discovery of the Candidate Off-nuclear Ultrasoft Hyper-luminous X-ray
  Source 3XMM J141711.1+522541

abstract:
  We report the discovery of an off-nuclear ultrasoft hyper-luminous X-ray
source candidate 3XMM J141711.1+522541 in the inactive S0 galaxy SDSS
J141711.07+522540.8 (z=0.41827, d_L=2.3 Gpc) in the Extended Groth Strip. It is
located at a projected offset of ~1.0 (5.2 kpc) from the nucleus of the galaxy
and was serendipitously detected in five XMM-Newton observations in 2000 July.
Two observations have enough counts and can be fitted with a standard thermal
disk with an apparent inner disk temperature kT_MCD ~ 0.13 keV and a 0.28-14.2
keV unabsorbed luminosity L_X ~ 4X10^{43} erg/s in the source rest frame. The
source was still detected in three Chandra observations in 2002 August, with
similarily ultrasoft but fainter spectra (kT_MCD ~ 0.17 keV, L_X ~ 0.5X10^{43}
erg/s). It was not detected in later observations, including two by Chandra in
2005 October, one by XMM-Newton in 2014 January, and two by Chandra in 2014
September-October, implying a long-term flux variation factor of >14. Therefore
the source could be a transient with an outburst in 2000-2002. It has a faint
optical counterpart candidate, with apparent magnitudes of m_F606W=26.3 AB mag
and m_F814W=25.5 AB mag in 2004 December (implying an absolute V-band magnitude
of ~-15.9 AB mag). We discuss various explanations for the source and find that
it is best explained as a massive black hole (BH) embedded in the nucleus of a
possibly stripped satellite galaxy, with the X-ray outburst due to tidal
disruption of a surrounding star by the BH. The BH mass is ~10^5 Msun, assuming
the peak X-ray luminosity at around the Eddington limit.


title:
Observational constraints on the X-ray Bright supergiant B[e] stars LHA
  115-S18 \& LHA 120-S 134

abstract:
  We present the preliminary results of an ongoing series of spectroscopic
observations of the Small Magellanic Cloud star LHA 115-S 18 (S18), which has
demonstrated extreme photospheric and spectroscopic variability that, in some
respects, is reminiscent of Luminous Blue Variables (LBVs). In contrast to our
previously published results, between 2012-2015 S18 remained in an spectral
state intermediate between S18's "hot" and "cool" extremes. In conjunction with
contemporaneous OGLE-IV photometric monitoring of S18, these data will be used
to determine the characteristic timescale of the variability and search for
periodicities, in particular binary modulated periodicity. We also present the
results of a pilot study of the LMC star LHA 120-S 134.


title: VLT/SPHERE deep insight of NGC 3603's core: Segregation or confusion?

abstract:
  We present new near-infrared photometric measurements of the core of the
young massive cluster NGC 3603 obtained with extreme adaptive optics. The data
were obtained with the SPHERE instrument mounted on ESO Very Large Telescope,
and cover three fields in the core of this cluster. We applied a correction for
the effect of extinction to our data obtained in the J and K broadband filters
and estimated the mass of detected sources inside the field of view of
SPHERE/IRDIS, which is 13.5"x13.5". We derived the mass function (MF) slope for
each spectral band and field. The MF slope in the core is unusual compared to
previous results based on Hubble space telescope (HST) and very large telescope
(VLT) observations. The average slope in the core is estimated as
-1.06^{+0.26}_{-0.26} for the main sequence stars with 3.5 Msun < M < 120
Msun.Thanks to the SPHERE extreme adaptive optics, 814 low-mass stars were
detected to estimate the MF slope for the pre-main sequence stars with 0.6
Msun< M < 3.5 Msun , Gamma = -0.54^{+0.11}_{-0.11} in the K-band images in two
fields in the core of the cluster. For the first time, we derive the mass
function of the very core of the NGC 3603 young cluster for masses in the range
0.6 - 120 Msun. Previous studies were either limited by crowding, lack of
dynamic range, or a combination of both.


title:
Stochastic reacceleration of relativistic electrons by turbulent
  reconnection: a mechanism for cluster-scale radio emission ?

abstract:
  In this paper we investigate a situation where relativistic particles are
reaccelerated diffusing across regions of reconnection and magnetic dynamo in
super-Alfvenic, incompressible large-scale turbulence. We present an
exploratory study of this mechanism in the intra-cluster-medium (ICM). In view
of large-scale turbulence in the ICM we adopt a reconnection scheme that is
based on turbulent reconnection and MHD turbulence. In this case particles are
accelerated and decelerated in a systematic way in reconnecting and
magnetic-dynamo regions, respectively, and on longer time-scales undergo a
stochastic process diffusing across these sites (similar to second-order
Fermi). Our study extends on larger scales numerical studies that focused on
the acceleration in and around turbulent reconnecting regions. We suggest that
this mechanism may play a role in the reacceleration of relativistic electrons
in galaxy clusters providing a new physical scenario to explain the origin of
cluster-scale diffuse radio emission. Indeed differently from current turbulent
reacceleration models proposed for example for radio halos this mechanism is
based on the effect of large-scale incompressible and super-Alfvenic
turbulence. In this new model turbulence governs the interaction between
relativistic particles and magnetic field lines that diffuse, reconnect and are
stretched in the turbulent ICM.


title:
The Kinematics of Plant Nutation Reveals a Simple Relation Between
  Curvature and the Orientation of Differential Growth

abstract:
  Nutation is an oscillatory movement that plants display during their
development. Despite its ubiquity among plants movements, the relation between
the observed movement and the underlying biological mechanisms remains unclear.
Here we show that the kinematics of the full organ in 3D gives a simple picture
of plant nutation, where the orientation of the curvature along the main axis
of the organ aligns with the direction of maximal differential growth. Within
this framework we reexamine the validity of widely used experimental
measurements of the apical tip as markers of growth dynamics. We show that
though this relation is correct under certain conditions, it does not generally
hold, and is not sufficient to uncover the specific role of each mechanism. As
an example we re-interpret previously measured experimental observations using
our model.