title:
The rotation of planets hosting atmospheric tides: from Venus to
  habitable super-earths

abstract:
  The competition between the torques induced by solid and thermal tides drives
the rotational dynamics of Venus-like planets and super-Earths orbiting in the
habitable zone of low-mass stars. The tidal responses of the atmosphere and
telluric core are related to their respective physical properties and strongly
depend on the tidal frequency. The resulting torque determines the possible
equilibrium states of the planet's spin. We compute here an analytic expression
for the total tidal torque exerted on a Venus-like planet. This expression is
used to characterize the equilibrium rotation of the body. Close to the star,
the solid tide dominates. Far from it, the thermal tide drives the rotational
dynamics of the planet. The transition regime corresponds to the habitable
zone, where prograde and retrograde equilibrium states appear. We demonstrate
the strong impact of the atmospheric properties and of the rheology of the
solid part on the rotational dynamics of Venus-like planets, highlighting the
key role played by dissipative mechanisms in the stability of equilibrium
configurations.


title: Key polynomials and pseudo-convergent sequences

abstract:
  In this paper we introduce a new concept of key polynomials for a given
valuation $\nu$ on $K[x]$. We prove that such polynomials have many of the
expected properties of key polynomials as those defined by MacLane and
Vaqui\'e, for instance, that they are irreducible and that the truncation of
$\nu$ associated to each key polynomial is a valuation. Moreover, we prove that
every valuation $\nu$ on $K[x]$ admits a sequence of key polynomials that
completely determines $\nu$ (in the sense which we make precise in the paper).
We also establish the relation between these key polynomials and
pseudo-convergent sequences defined by Kaplansky.


title:
Asymptotic shape optimization for Riesz means of the Dirichlet Laplacian
  over convex domains

abstract:
  For $\Omega \subset \mathbb{R}^n$, a convex and bounded domain, we study the
spectrum of $-\Delta_\Omega$ the Dirichlet Laplacian on $\Omega$. For
$\Lambda\geq0$ and $\gamma \geq 0$ let $\Omega_{\Lambda, \gamma}(\mathcal{A})$
denote any extremal set of the shape optimization problem $$
  \sup\{ \mathrm{Tr}(-\Delta_\Omega-\Lambda)_-^\gamma: \Omega \in \mathcal{A},
|\Omega|=1\}, $$ where $\mathcal{A}$ is an admissible family of convex domains
in $\mathbb{R}^n$. If $\gamma \geq 1$ and $\{\Lambda_j\}_{j\geq1}$ is a
positive sequence tending to infinity we prove that $\{\Omega_{\Lambda_j,
\gamma}(\mathcal{A})\}_{j\geq1}$ is a bounded sequence, and hence contains a
convergent subsequence. Under an additional assumption on $\mathcal{A}$ we
characterize the possible limits of such subsequences as minimizers of the
perimeter among domains in $\mathcal{A}$ of unit measure. For instance if
$\mathcal{A}$ is the set of all convex polygons with no more than $m$ faces,
then $\Omega_{\Lambda, \gamma}$ converges, up to rotation and translation, to
the regular $m$-gon.
  This is a revised version of the paper published in the Journal of Spectral
Theory (2019) which has been updated in accordance with an erratum published in
2021. The results of the paper remain unchanged, but the proofs of Theorem 2.4
and Corollary 5.3 have been amended.


title:
InSb Nanowires with Built-In GaxIn1-xSb Tunnel Barriers for Majorana
  Devices

abstract:
  Majorana zero modes (MZMs), prime candidates for topological quantum bits,
are detected as zero bias conductance peaks (ZBPs) in tunneling spectroscopy
measurements. Implementation of a narrow and high tunnel barrier in the next
generation of Majorana devices can help to achieve the theoretically predicted
quantized height of the ZBP. We propose a material-oriented approach to
engineer a sharp and narrow tunnel barrier by synthesizing a thin axial segment
of GaxIn1-xSb within an InSb nanowire. By varying the precursor molar fraction
and the growth time, we accurately control the composition and the length of
the barriers. The height and the width of the GaxIn1-xSb tunnel barrier are
extracted from the Wentzel-Kramers-Brillouin (WKB)-fits to the experimental I-V
traces.


title: Observation of mode-locked spatial laser solitons

abstract:
  A stable nonlinear wave packet, self-localized in all three dimensions, is an
intriguing and much sought after object in nonlinear science in general and in
nonlinear photonics in particular. We report on the experimental observation of
mode-locked spatial laser solitons in a vertical-cavity surface-emitting laser
with frequency-selective feedback from an external cavity. These spontaneously
emerging and long-term stable spatio-temporal structures have a pulse length
shorter than the cavity round trip time and may pave the way to completely
independent cavity light bullets.


title: Toward Accurate Adsorption Energetics on Clay Surfaces

abstract:
  Clay minerals are ubiquitous in nature, and the manner in which they interact
with their surroundings has important industrial and environmental
implications. Consequently, a molecular-level understanding of the adsorption
of molecules on clay surfaces is crucial. In this regard computer simulations
play an important role, yet the accuracy of widely used empirical force fields
(FF) and density functional theory (DFT) exchange-correlation functionals is
often unclear in adsorption systems dominated by weak interactions. Herein we
present results from quantum Monte Carlo (QMC) for water and methanol
adsorption on the prototypical clay kaolinite. To the best of our knowledge,
this is the first time QMC has been used to investigate adsorption at a
complex, natural surface such as a clay. As well as being valuable in their own
right, the QMC benchmarks obtained provide reference data against which the
performance of cheaper DFT methods can be tested. Indeed using various DFT
exchange-correlation functionals yields a very broad range of adsorption
energies, and it is unclear a priori which evaluation is better. QMC reveals
that in the systems considered here it is essential to account for van der
Waals (vdW) dispersion forces since this alters both the absolute and relative
adsorption energies of water and methanol. We show, via FF simulations, that
incorrect relative energies can lead to significant changes in the interfacial
densities of water and methanol solutions at the kaolinite interface. Despite
the clear improvements offered by the vdW-corrected and the vdW-inclusive
functionals, absolute adsorption energies are often overestimated, suggesting
that the treatment of vdW forces in DFT is not yet a solved problem.


title: Dynamical friction on hot bodies in opaque, gaseous media

abstract:
  We consider the gravitational force exerted on a point-like perturber of mass
$M$ travelling within a uniform gaseous, opaque medium at constant velocity
$V$. The perturber irradiates the surrounding gas with luminosity $L$. The
diffusion of the heat released is modelled with a uniform thermal diffusivity
$\chi$. Using linear perturbation theory, we show that the force exerted by the
perturbed gas on the perturber differs from the force without radiation (or
standard dynamical friction). Hot, underdense gas trails the mass, which gives
rise to a new force component, the heating force, with direction $+V$, thus
opposed to the standard dynamical friction. In the limit of low Mach numbers,
the heating force has expression $F_\mathrm{heat}=\gamma(\gamma-1)GML/(2\chi
c_s^2)$, $c_s$ being the sound speed and $\gamma$ the ratio of specific heats.
In the limit of large Mach numbers, $F_\mathrm{heat}=(\gamma-1)GML/(\chi
V^2)f(r_\mathrm{min}V/4\chi)$, where $f$ is a function that diverges
logarithmically as $r_\mathrm{min}$ tends to zero. Remarkably, the force in the
low Mach number limit does not depend on the velocity. The equilibrium speed,
when it exists, is set by the cancellation of the standard dynamical friction
and heating force. In the low Mach number limit, it scales with the luminosity
to mass ratio of the perturber. Using the above results suggests that Mars- to
Earth-sized planetary embryos heated by accretion in a gaseous protoplanetary
disc should have eccentricities and inclinations that amount to a sizeable
fraction of the disc's aspect ratio, for conditions thought to prevail at a few
astronomical units.


title: Teichm\"uller polynomials of fibered alternating links

abstract:
  We give an algorithm for computing the Teichm\"uller polynomial for a certain
class of fibered alternating links associated to trees. Furthermore, we exhibit
a mutant pair of such links distinguished by the Teichm\"uller polynomial.


title:
The interstellar medium in Andromeda's dwarf spheroidal galaxies: II.
  Multi-phase gas content and ISM conditions

abstract:
  We make an inventory of the interstellar medium material in three
low-metallicity dwarf spheroidal galaxies of the Local Group (NGC147, NGC185
and NGC205). Ancillary HI, CO, Spitzer IRS spectra, H{\alpha} and X-ray
observations are combined to trace the atomic, cold and warm molecular, ionised
and hot gas phases. We present new Nobeyama CO(1-0) observations and Herschel
SPIRE FTS [CI] observations of NGC205 to revise its molecular gas content.
  We derive total gas masses of M_gas = 1.9-5.5x10^5 Msun for NGC185 and M_gas
= 8.6-25.0x10^5 Msun for NGC205. Non-detections combine to an upper limit on
the gas mass of M_gas =< 0.3-2.2x10^5 Msun for NGC147. The observed gas
reservoirs are significantly lower compared to the expected gas masses based on
a simple closed-box model that accounts for the gas mass returned by planetary
nebulae and supernovae. The gas-to-dust mass ratios GDR~37-107 and GDR~48-139
are also considerably lower compared to the expected GDR~370 and GDR~520 for
the low metal abundances in NGC 185 (0.36 Zsun) and NGC205 (0.25 Zsun),
respectively.
  To simultaneously account for the gas deficiency and low gas-to-dust ratios,
we require an efficient removal of a large gas fraction and a longer dust
survival time (~1.6 Gyr). We believe that efficient galactic winds (combined
with heating of gas to sufficiently high temperatures in order for it to escape
from the galaxy) and/or environmental interactions with neighbouring galaxies
are responsible for the gas removal from NGC147, NGC185 and NGC205.


title:
Non-Hermitian approach of edge states and quantum transport in a
  magnetic field

abstract:
  We develop a manifest non-Hermitian approach of spectral and transport
properties of two- dimensional mesoscopic systems in strong magnetic field. The
finite system to which several ter- minals are attached constitutes an open
system that can be described by an effective Hamiltonian. The life time of the
quantum states expressed by the energy imaginary part depends specifically on
the lead-system coupling and makes the difference among three regimes:
resonant, integer quan- tum Hall effect and superradiant. The discussion is
carried on in terms of edge state life time in different gaps, channel
formation, role of hybridization, transmission coefficients quantization. A toy
model helps in understanding non-Hermitian aspects in open systems.


title:
The Tragedy of Your Upstairs Neighbors: Is the Airbnb Negative
  Externality Internalized?

abstract:
  A commonly expressed concern about the rise of the peer-to-peer rental market
Airbnb is that hosts---those renting out their properties---impose costs on
their unwitting neighbors. I consider the question of whether apartment
building owners will, in a competitive rental market, set a building-specific
Airbnb hosting policy that is socially efficient. I find that if tenants can
sort across apartments based on the owners policy then the equilibrium fraction
of buildings allowing Airbnb listing would be socially efficient.


title:
End-to-end Learning of Cost-Volume Aggregation for Real-time Dense
  Stereo

abstract:
  We present a new deep learning-based approach for dense stereo matching.
Compared to previous works, our approach does not use deep learning of pixel
appearance descriptors, employing very fast classical matching scores instead.
At the same time, our approach uses a deep convolutional network to predict the
local parameters of cost volume aggregation process, which in this paper we
implement using differentiable domain transform. By treating such transform as
a recurrent neural network, we are able to train our whole system that includes
cost volume computation, cost-volume aggregation (smoothing), and
winner-takes-all disparity selection end-to-end. The resulting method is highly
efficient at test time, while achieving good matching accuracy. On the KITTI
2015 benchmark, it achieves a result of 6.34\% error rate while running at 29
frames per second rate on a modern GPU.


title:
A decomposition algorithm for computing income taxes with pass-through
  entities and its application to the Chilean case

abstract:
  Income tax systems with pass-through entities transfer a firm's incomes to
the shareholders, which are taxed individually. In 2014, a Chilean tax reform
introduced this type of entity and changed to an accrual basis that distributes
incomes (but not losses) to shareholders. A crucial step for the Chilean
taxation authority is to compute the final income of each individual, given the
complex network of corporations and companies, usually including cycles between
them. In this paper, we show the mathematical conceptualization and the
solution to the problem, proving that there is only one way to distribute
incomes to taxpayers. Using the theory of absorbing Markov chains, we define a
mathematical model for computing the taxable incomes of each taxpayer, and we
propose a decomposition algorithm for this problem. This allows us to compute
the solution accurately and with the efficient use of computational resources.
Finally, we present some characteristics of the Chilean taxpayers' network and
computational results of the algorithm using this network.


title:
Gauge-theoretic invariants for topological insulators: A bridge between
  Berry, Wess-Zumino, and Fu-Kane-Mele

abstract:
  We establish a connection between two recently-proposed approaches to the
understanding of the geometric origin of the Fu-Kane-Mele invariant
$\mathrm{FKM} \in \mathbb{Z}_2$, arising in the context of 2-dimensional
time-reversal symmetric topological insulators. On the one hand, the
$\mathbb{Z}_2$ invariant can be formulated in terms of the Berry connection and
the Berry curvature of the Bloch bundle of occupied states over the Brillouin
torus. On the other, using techniques from the theory of bundle gerbes it is
possible to provide an expression for $\mathrm{FKM}$ containing the square root
of the Wess-Zumino amplitude for a certain $U(N)$-valued field over the
Brillouin torus.
  We link the two formulas by showing directly the equality between the above
mentioned Wess-Zumino amplitude and the Berry phase, as well as between their
square roots. An essential tool of independent interest is an equivariant
version of the adjoint Polyakov-Wiegmann formula for fields $\mathbb{T}^2 \to
U(N)$, of which we provide a proof employing only basic homotopy theory and
circumventing the language of bundle gerbes.

categories: math-ph cond-mat.mes-hall hep-th math.MP


title: New estimates of the deceleration parameter in weak gravity

abstract:
  We consider weak gravity at accelerations $\alpha<a_H$ when Rindler and
cosmological horizon collude at $R_H=c/H$, where $c$ is the velocity of light
and $H$ is the Hubble parameter. This is manifest in reduced inertia $m$, below
the value $m_0$ in Newtonian gravity. Striking evidence for a sharp transition
to weak gravity is found in galaxy rotation curves. Their sensitivity to the
cosmological background is expressed by correlations to the deceleration
parameter $q=1-(4\pi a_0/cH)^{2}$ and $q=-1/2 -3
(\Omega_b/\sqrt{2}\sqrt{\pi})^{1/2}$, where $a_0$ is Milgrom's scale in the
baryonic Tully-Fisher relation of spiral galaxies and $\Omega_b$ is the
baryonic matter density. The Planck value $\Omega_b=0.048$ with $H\simeq 73$ km
s$^{-1}$ Mpc$^{-1}$ shows $q\simeq-0.85$. Future surveys may determine
$Q_0=\left.dq(z)/dz\right|_{z=0}$ to provide a direct test for dynamical dark
energy ($Q_0>2.5$) versus $\Lambda$CDM ($Q_0<1$).


title: Mapping brain activity with flexible graphene micro-transistors

abstract:
  Establishing a reliable communication interface between the brain and
electronic devices is of paramount importance for exploiting the full potential
of neural prostheses. Current microelectrode technologies for recording
electrical activity, however, evidence important shortcomings, e.g. challenging
high density integration. Solution-gated field-effect transistors (SGFETs), on
the other hand, could overcome these shortcomings if a suitable transistor
material were available. Graphene is particularly attractive due to its
biocompatibility, chemical stability, flexibility, low intrinsic electronic
noise and high charge carrier mobilities. Here, we report on the use of an
array of flexible graphene SGFETs for recording spontaneous slow waves, as well
as visually evoked and also pre-epileptic activity in vivo in rats. The
flexible array of graphene SGFETs allows mapping brain electrical activity with
excellent signal-to-noise ratio (SNR), suggesting that this technology could
lay the foundation for a future generation of in vivo recording implants.


title: Long-range interacting systems in the unconstrained ensemble

abstract:
  Completely open systems can exchange heat, work, and matter with the
environment. While energy, volume, and number of particles fluctuate under
completely open conditions, the equilibrium states of the system, if they
exist, can be specified using the temperature, pressure, and chemical potential
as control parameters. The unconstrained ensemble is the statistical ensemble
describing completely open systems and the replica energy is the appropriate
free energy for these control parameters from which the thermodynamics must be
derived. It turns out that macroscopic systems with short-range interactions
cannot attain equilibrium configurations in the unconstrained ensemble, since
temperature, pressure, and chemical potential cannot be taken as a set of
independent variables in this case. In contrast, we show that systems with
long-range interactions can reach states of thermodynamic equilibrium in the
unconstrained ensemble. To illustrate this fact, we consider a modification of
the Thirring model and compare the unconstrained ensemble with the canonical
and grand canonical ones: the more the ensemble is constrained by fixing the
volume or number of particles, the larger the space of parameters defining the
equilibrium configurations.


title:
Free Energy of the Uniform Electron Gas: Testing Analytical Models
  against First Principle Results

abstract:
  The uniform electron gas is a key model system in the description of matter,
including dense plasmas and solid state systems. However, the simultaneous
occurence of quantum, correlation, and thermal effects makes the theoretical
description challenging. For these reasons, over the last half century many
analytical approaches have been developed the accuracy of which has remained
unclear. We have recently obtained the first \textit{ab initio} data for the
exchange correlation free energy of the uniform electron gas [T. Dornheim
\textit{et al.}, Phys.~Rev.~Lett.~\textbf{117}, 156403 (2016)] which now
provides the opportunity to assess the quality of the mentioned approaches and
parametrizations. Particular emphasis is put on the warm dense matter regime,
where we find significant discrepancies between the different approaches.


title:
Laplace-type integral representations of the generalized Bessel function
  and of the Dunkl kernel of type $B_2$

abstract:
  In this paper, we derive a Laplace-type integral representations for both the
generalized Bessel function and the Dunkl kernel associated with the rank-two
root system of type B_2. The derivation of the first one elaborates on the
integral representation of the generalized Bessel function proved in
\cite{Demni} through the modified Bessel function of the first kind. In
particular, we recover an expression of the density of the Duistermaat-Heckman
measure for the dihedral group of order eight. As to the integral
representation of the corresponding Dunkl kernel, it follows from an
application of the shift principle to the generalized Bessel function.


title: Laser-Induced Linear Electron Acceleration in Free Space

abstract:
  Linear acceleration in free space is a topic that has been studied for over
20 years, and its ability to eventually produce high-quality, high energy
multi-particle bunches has remained a subject of great interest. Arguments can
certainly be made that such an ability is very doubtful. Nevertheless, we chose
to develop an accurate and truly predictive theoretical formalism to explore
this remote possibility in a computational experiment. The formalism includes
exact treatment of Maxwell's equations, exact relativistic treatment of the
interaction among the multiple individual particles, and exact treatment of the
interaction at near and far field. Several surprising results emerged. For
example, we find that 30 keV electrons (2.5% energy spread) can be accelerated
to 7.7 MeV (2.5% spread) and to 205 MeV (0.25% spread) using 25 mJ and 2.5 J
lasers respectively. These findings should hopefully guide and help develop
compact, high-quality, ultra-relativistic electron sources, avoiding
conventional limits imposed by material breakdown or structural constraints.


title: Asteroseismic modelling of the Binary HD 176465

abstract:
  The detection and analysis of oscillations in binary star systems is critical
in understanding stellar structure and evolution. This is partly because such
systems have the same initial chemical composition and age. Solar-like
oscillations have been detected by Kepler in both components of the
asteroseismic binary HD 176465. We present an independent modelling of each
star in this binary system. Stellar models generated using MESA (Modules for
Experiments in Stellar Astrophysics) were fitted to both the observed
individual frequencies and complementary spectroscopic parameters. The
individual theoretical oscillation frequencies for the corresponding stellar
models were obtained using GYRE as the pulsation code. A Bayesian approach was
applied to find the probability distribution functions of the stellar
parameters using AIMS (Asteroseismic Inference on a Massive Scale) as the
optimisation code. The ages of HD 176465 A and HD 176465 B were found to be
2.81 $\pm$ 0.48 Gyr and 2.52 $\pm$ 0.80 Gyr, respectively. These results are in
agreement when compared to previous studies carried out using other
asteroseismic modelling techniques and gyrochronology.


title:
The $\beta$-model for Random Graphs --- Regression, Cram\'er-Rao Bounds,
  and Hypothesis Testing

abstract:
  We develop a maximum-likelihood based method for regression in a setting
where the dependent variable is a random graph and covariates are available on
a graph-level. The model generalizes the well-known $\beta$-model for random
graphs by replacing the constant model parameters with regression functions.
Cram\'er-Rao bounds are derived for the undirected $\beta$-model, the directed
$\beta$-model, and the generalized $\beta$-model. The corresponding maximum
likelihood estimators are compared to the bounds by means of simulations.
Moreover, examples are given on how to use the presented maximum likelihood
estimators to test for directionality and significance. Last, the applicability
of the model is demonstrated using dynamic social network data describing
communication among healthcare workers.


title:
Intermittency and energy fluxes in the surface layer of free-surface
  turbulence

abstract:
  By analyzing hot-wire velocity data taken in an open channel flow, an
unambiguous definition of surface-layer thickness is here provided in terms of
the cross-over scale between backward and forward energy fluxes. It is shown
that the turbulence in the surface layer does not conform to the classical
description of two-dimensional turbulence, since the direct energy cascade
persists at scales smaller than the cross-over scale, comparable with the
distance from the free-surface.
  The multifractal analysis of the one-dimensional surrogate of the turbulent
kinetic energy dissipation rate in terms of generalized dimensions and
singularity spectrum indicates that intermittency is strongly depleted in the
surface layer, as shown by the singularity spectrum contracted to a single
point.
  The combination of intermittency indicators and energy fluxes allowed to
identify the specific nature of the surface layer as alternative to classical
paradigms of three- and two-dimensional turbulence which cannot fully capture
the global behavior of turbulence near a free-surface.


title:
Tuning of large piezoelectric response in nanosheet-buffered lead
  zirconate titanate films on glass substrates

abstract:
  Renewed interest has been witnessed in utilizing the piezoelectric response
of $PbZr_{0.52}Ti_{0.48}O_{3}$ (PZT) films on glass substrates for applications
such as data storage and adaptive optics. Accordingly, new methodologies are
being explored to grow well-oriented PZT thin films to harvest a large
piezoelectric response. However, thin film piezoelectric response is
significantly reduced compared to intrinsic response due to substrate induced
clamping, even when films are well-oriented. Here, a novel method is presented
to grow preferentially (100)-oriented PZT films on glass substrates by
utilizing crystalline nanosheets as seed layers. Furthermore, increasing the
repetition frequency up to 20 Hz during pulsed laser deposition helps to tune
the film microstructure to hierarchically ordered columns that leads to reduced
clamping and enhanced piezoelectric response evidenced by transmission electron
microscopy and analytical calculations. A large piezoelectric response of 280
pm/V is observed in optimally tuned structure which almost triples the highest
reported piezoelectric response on glass. To confirm that the clamping
compromises the piezoelectric response, denser films are deposited using a
lower repetition frequency and a $BiFeO_{3}$ buffer layer resulting in
significantly reduced piezoelectric responses. This paper demonstrates a novel
method for PZT integration on glass substrates without compromising the large
piezoelectric response.


title: An Euler system for characters over an imaginary biquadratic field

abstract:
  Given a pair of modular forms with complex multiplication by distinct
imaginary quadratic fields, the four dimensional Galois representation
associated to their Rankin--Selberg convolution is induced from a character
over an imaginary biquadratic field $F$. Using the Euler system of Lei,
Loeffler and Zerbes we bound a Selmer group associated to this character, over
the unique $\mathbb{Z}_{p}^{3}$-extension of $F$.


title:
A stable partitioned FSI algorithm for rigid bodies and incompressible
  flow. Part II: General formulation

abstract:
  A stable partitioned algorithm is developed for fluid-structure interaction
(FSI) problems involving viscous incompressible flow and rigid bodies. This
{\em added-mass partitioned} (AMP) algorithm remains stable, without
sub-iterations, for light and even zero mass rigid bodies when added-mass and
viscous added-damping effects are large. The scheme is based on a generalized
Robin interface condition for the fluid pressure that includes terms involving
the linear acceleration and angular acceleration of the rigid body. Added mass
effects are handled in the Robin condition by inclusion of a boundary integral
term that depends on the pressure. Added-damping effects due to the viscous
shear forces on the body are treated by inclusion of added-damping tensors that
are derived through a linearization of the integrals defining the force and
torque. Added-damping effects may be important at low Reynolds number, or, for
example, in the case of a rotating cylinder or rotating sphere when the
rotational moments of inertia are small. In this second part of a two-part
series, the general formulation of the AMP scheme is presented including the
form of the AMP interface conditions and added-damping tensors for general
geometries. A fully second-order accurate implementation of the AMP scheme is
developed in two dimensions based on a fractional-step method for the
incompressible Navier-Stokes equations using finite difference methods and
overlapping grids to handle the moving geometry. The numerical scheme is
verified on a number of difficult benchmark problems.


title:
Integer conversions and estimation of the number of integer solutions of
  algebraic Diophantine equations

abstract:
  The paper assesses the top number of integer solutions for algebraic
Diophantine Thue diagonal equation of the degree $n \geq 2$ and number of
variables $k > 2$ and equations with explicit variable in the case when the
coefficients of the equation are of the opposite signs. The author found
integer conversions that maintain the asymptotic behavior of the number of
integer solutions of algebraic Diophantine equation in the case of the
conversion equation to diagonal form. The paper considers the estimation of the
number of integer solutions for some types of algebraic Diophantine equations
with nondiagonal form.


title: DSAC - Differentiable RANSAC for Camera Localization

abstract:
  RANSAC is an important algorithm in robust optimization and a central
building block for many computer vision applications. In recent years,
traditionally hand-crafted pipelines have been replaced by deep learning
pipelines, which can be trained in an end-to-end fashion. However, RANSAC has
so far not been used as part of such deep learning pipelines, because its
hypothesis selection procedure is non-differentiable. In this work, we present
two different ways to overcome this limitation. The most promising approach is
inspired by reinforcement learning, namely to replace the deterministic
hypothesis selection by a probabilistic selection for which we can derive the
expected loss w.r.t. to all learnable parameters. We call this approach DSAC,
the differentiable counterpart of RANSAC. We apply DSAC to the problem of
camera localization, where deep learning has so far failed to improve on
traditional approaches. We demonstrate that by directly minimizing the expected
loss of the output camera poses, robustly estimated by RANSAC, we achieve an
increase in accuracy. In the future, any deep learning pipeline can use DSAC as
a robust optimization component.


title: Triply periodic constant mean curvature surfaces

abstract:
  Given a closed flat 3-torus $N$, for each $H>0$ and each non-negative integer
$g$, we obtain area estimates for closed surfaces with genus $g$ and constant
mean curvature $H$ embedded in $N$. This result contrasts with the theorem of
Traizet [33], who proved that every flat 3-torus admits for every positive
integer $g$ with $g\neq 2$, connected closed embedded minimal surfaces of genus
$g$ with arbitrarily large area.


title: From cells to tissue: A continuum model of epithelial mechanics

abstract:
  A continuum model of epithelial tissue mechanics was formulated using
cellular-level mechanical ingredients and cell morphogenetic processes,
including cellular shape changes and cellular rearrangements. This model can
include finite deformation, and incorporates stress and deformation tensors,
which can be compared with experimental data. Using this model, we elucidated
dynamical behavior underlying passive relaxation, active
contraction-elongation, and tissue shear flow. This study provides an
integrated scheme for the understanding of the mechanisms that are involved in
orchestrating the morphogenetic processes in individual cells, in order to
achieve epithelial tissue morphogenesis.


title: Learning to Fuse 2D and 3D Image Cues for Monocular Body Pose Estimation

abstract:
  Most recent approaches to monocular 3D human pose estimation rely on Deep
Learning. They typically involve regressing from an image to either 3D joint
coordinates directly or 2D joint locations from which 3D coordinates are
inferred. Both approaches have their strengths and weaknesses and we therefore
propose a novel architecture designed to deliver the best of both worlds by
performing both simultaneously and fusing the information along the way. At the
heart of our framework is a trainable fusion scheme that learns how to fuse the
information optimally instead of being hand-designed. This yields significant
improvements upon the state-of-the-art on standard 3D human pose estimation
benchmarks.


title: Factorized Bilinear Models for Image Recognition

abstract:
  Although Deep Convolutional Neural Networks (CNNs) have liberated their power
in various computer vision tasks, the most important components of CNN,
convolutional layers and fully connected layers, are still limited to linear
transformations. In this paper, we propose a novel Factorized Bilinear (FB)
layer to model the pairwise feature interactions by considering the quadratic
terms in the transformations. Compared with existing methods that tried to
incorporate complex non-linearity structures into CNNs, the factorized
parameterization makes our FB layer only require a linear increase of
parameters and affordable computational cost. To further reduce the risk of
overfitting of the FB layer, a specific remedy called DropFactor is devised
during the training process. We also analyze the connection between FB layer
and some existing models, and show FB layer is a generalization to them.
Finally, we validate the effectiveness of FB layer on several widely adopted
datasets including CIFAR-10, CIFAR-100 and ImageNet, and demonstrate superior
results compared with various state-of-the-art deep models.


title: New Physics in Astrophysical Neutrino Flavor (NuFact 2016)

abstract:
  Astrophysical neutrinos are powerful tools to study fundamental properties of
particle physics. We perform a general new physics study on ultra high energy
neutrino flavor content by introducing effective operators. We find that at the
current limits on these operators, new physics terms cause maximal effects on
the flavor content, however, the flavor content at Earth is confined to a
region related to the initial flavor content.


title:
A stable partitioned FSI algorithm for rigid bodies and incompressible
  flow. Part I: Model problem analysis

abstract:
  A stable partitioned algorithm is developed for fluid-structure interaction
(FSI) problems involving viscous incompressible flow and rigid bodies. This
{\em added-mass partitioned} (AMP) algorithm remains stable, without
sub-iterations, for light and even zero mass rigid bodies when added-mass and
viscous added-damping effects are large. The scheme is based on a generalized
Robin interface condition for the fluid pressure that includes terms involving
the linear acceleration and angular acceleration of the rigid body. Added-mass
effects are handled in the Robin condition by inclusion of a boundary integral
term that depends on the pressure. Added-damping effects due to the viscous
shear forces on the body are treated by inclusion of added-damping tensors that
are derived through a linearization of the integrals defining the force and
torque. Added-damping effects may be important at low Reynolds number, or, for
example, in the case of a rotating cylinder or rotating sphere when the
rotational moments of inertia are small. In this first part of a two-part
series, the properties of the AMP scheme are motivated and evaluated through
the development and analysis of some model problems. The analysis shows when
and why the traditional partitioned scheme becomes unstable due to either
added-mass or added-damping effects. The analysis also identifies the proper
form of the added-damping which depends on the discrete time-step and the
grid-spacing normal to the rigid body. The results of the analysis are
confirmed with numerical simulations that also demonstrate a second-order
accurate implementation of the AMP scheme.


title:
Accurate modeling of plasma acceleration with arbitrary order
  pseudo-spectral particle-in-cell methods

abstract:
  Particle in Cell (PIC) simulations are a widely used tool for the
investigation of both laser- and beam-driven plasma acceleration. It is a known
issue that the beam quality can be artificially degraded by numerical Cherenkov
radiation (NCR) resulting primarily from an incorrectly modeled dispersion
relation. Pseudo-spectral solvers featuring infinite order stencils can
strongly reduce NCR, or even suppress it, and are therefore well suited to
correctly model the beam properties. For efficient parallelization of the PIC
algorithm, however, localized solvers are inevitable. Arbitrary order
pseudo-spectral methods provide this needed locality. Yet, these methods can
again be prone to NCR. Here, we show that acceptably low solver orders are
sufficient to correctly model the physics of interest, while allowing for
parallel computation by domain decomposition.


title:
Localization Lifetime of a Many-Body System with Periodic Constructed
  Disorder

abstract:
  We show that, in a many-body system, all particles can be strongly confined
to the initially occupied sites for a time that scales as a high power of the
ratio of the bandwidth of site energies to the hopping amplitude. Such
time-domain formulation is complementary to the formulation of the many-body
localization of all stationary states with a large localization length. The
long localization lifetime is achieved by constructing a periodic sequence of
site energies with a large period in a one-dimensional chain. The scaling of
the localization lifetime is independent of the number of particles for a broad
range of the coupling strength. The analytical results are confirmed by
numerical calculations.


title:
Combining the AFLOW GIBBS and Elastic Libraries for efficiently and
  robustly screening thermo-mechanical properties of solids

abstract:
  Thorough characterization of the thermo-mechanical properties of materials
requires difficult and time-consuming experiments. This severely limits the
availability of data and it is one of the main obstacles for the development of
effective accelerated materials design strategies. The rapid screening of new
potential systems requires highly integrated, sophisticated and robust
computational approaches. We tackled the challenge by surveying more than 3,000
crystalline solids within the AFLOW framework with the newly developed
"Automatic Elasticity Library" combined with the previously implemented GIBBS
method. The first extracts the mechanical properties from automatic
self-consistent stress-strain calculations, while the latter employs those
mechanical properties to evaluate the thermodynamics within the Debye model.
The new thermo-elastic library is benchmarked against a set of 74
experimentally characterized systems to pinpoint a robust computational
methodology for the evaluation of bulk and shear moduli, Poisson ratios, Debye
temperatures, Gr\"uneisen parameters, and thermal conductivities of a wide
variety of materials. The effect of different choices of equations of state is
examined and the optimum combination of properties for the
Leibfried-Schl\"omann prediction of thermal conductivity is identified, leading
to improved agreement with experimental results than the GIBBS-only approach.


title: Testable Baryogenesis in Seesaw Models (NuFact 2016)

abstract:
  We revisit the production of baryon asymmetries in the minimal type I seesaw
model with heavy Majorana singlets in the GeV range. We include "washout"
effects from scattering processes with gauge bosons, higgs decays and inverse
decays, besides the dominant top scatterings. We show that in the minimal model
with two singlets, and for an inverted light neutrino ordering, future
measurements from SHiP and neutrinoless double beta decay could in principle
provide sufficient information to predict the matter-antimatter asymmetry in
the universe.


title: Cyclic Period in the CBE Model

abstract:
  In a cyclic entropy model in which the extroverse is jettisoned at turnaround
with a Come Back Empty (CBE) assumption, we address matching of the contaction
scale factor $\hat{a}(t)=f(t_T){a}(t)$ to the expansion scale factor $a(t)$,
where $f(t_T)$ is the ratio at turnaround of the introverse to extroverse
radii. Such matching is necessary for infinite cyclicity and fixes the CBE
period at $\sim 2.6Ty$.


title:
Convergence of the PML solution for elastic wave scattering by
  biperiodic structures

abstract:
  This paper is concerned with the analysis of elastic wave scattering of a
time-harmonic plane wave by a biperiodic rigid surface, where the wave
propagation is governed by the three-dimensional Navier equation. An exact
transparent boundary condition is developed to reduce the scattering problem
equivalently into a boundary value problem in a bounded domain. The perfectly
matched layer (PML) technique is adopted to truncate the unbounded physical
domain into a bounded computational domain. The well-posedness and exponential
convergence of the solution are established for the truncated PML problem by
developing a PML equivalent transparent boundary condition. The proofs rely on
a careful study of the error between the two transparent boundary operators.
The work significantly extend the results from the one-dimensional periodic
structures to the two-dimensional biperiodic structures. Numerical experiments
are included to demonstrate the competitive behavior of the proposed method.


title:
Linear commuting maps and skew-symmertric biderivations of the
  deformative Schrodinger-Virasoro Lie algebras

abstract:
  In this paper, we investigate the skew-symmertric biderivations of the
deformative Schrodinger-Virasoro Lie algebras which contain the twisted and
original deformative Schrodinger-Virasoro Lie algebras. As an application, we
give the explicit form of each linear commuting map on the deformative
Schrodinger-Virasoro Lie algebras. In particular, we obtain that there exist
non-inner biderivations and non-standard linear commuting maps for the certain
deformative Schrodinger-Virasoro Lie algebras.


title: On Diophantine exponents for Laurent series over a finite field

abstract:
  In this paper, we study properties of the Diophantine exponents $w_n$ and
$w_n^{*}$ for Laurent series over a finite field. We prove that for an integer
$n\geq 1$ and a rational number $w>2n-1$, there exist a strictly increasing
sequence of positive integers $(k_j)_{j\geq 1}$ and a sequence of algebraic
Laurent series $(\xi_j)_{j\geq 1}$ such that deg $\xi_j=p^{k_j}+1$ and
\begin{equation} w_1(\xi_j)=w_1 ^{*}(\xi_j)=\ldots =w_n(\xi_j)=w_n
^{*}(\xi_j)=w \end{equation} for any $j\geq 1$. For each $n\geq 2$, we give
explicit examples of Laurent series $\xi $ for which $w_n(\xi )$ and
$w_n^{*}(\xi )$ are different.


title: Hard-Aware Deeply Cascaded Embedding

abstract:
  Riding on the waves of deep neural networks, deep metric learning has also
achieved promising results in various tasks using triplet network or Siamese
network. Though the basic goal of making images from the same category closer
than the ones from different categories is intuitive, it is hard to directly
optimize due to the quadratic or cubic sample size. To solve the problem, hard
example mining which only focuses on a subset of samples that are considered
hard is widely used. However, hard is defined relative to a model, where
complex models treat most samples as easy ones and vice versa for simple
models, and both are not good for training. Samples are also with different
hard levels, it is hard to define a model with the just right complexity and
choose hard examples adequately. This motivates us to ensemble a set of models
with different complexities in cascaded manner and mine hard examples
adaptively, a sample is judged by a series of models with increasing
complexities and only updates models that consider the sample as a hard case.
We evaluate our method on CARS196, CUB-200-2011, Stanford Online Products,
VehicleID and DeepFashion datasets. Our method outperforms state-of-the-art
methods by a large margin.


title: Neutron stars in Scalar-Tensor-Vector Gravity

abstract:
  Scalar-Tensor-Vector Gravity (STVG), also referred as MOdified Gravity (MOG),
is an alternative theory of the gravitational interaction. Its weak field
approximation has been successfully used to described Solar System
observations, galaxy rotation curves, dynamics of clusters of galaxies, and
cosmological data, without the imposition of dark components. The theory was
formulated by John Moffat in 2006. In this work, we derive matter-sourced
solutions of STVG and construct neutron star models. We aim at exploring STVG
predictions about stellar structure in the strong gravity regime. Specifically,
we represent spacetime with a static, spherically symmetric manifold, and model
the stellar matter content with a perfect fluid energy-momentum tensor. We then
derive the modified Tolman-Oppenheimer-Volkoff equation in STVG and integrate
it for different equations of state. We find that STVG allows heavier neutron
stars than General Relativity (GR). Maximum masses depend on a normalized
parameter that quantifies the deviation from GR. The theory exhibits unusual
predictions for extreme values of this parameter. We conclude that STVG admits
suitable spherically symmetric solutions with matter sources, relevant for
stellar structure. Since recent determinations of neutron stars masses violate
some GR predictions, STVG appears as a viable candidate for a new gravity
theory.


title: GENESIM: genetic extraction of a single, interpretable model

abstract:
  Models obtained by decision tree induction techniques excel in being
interpretable.However, they can be prone to overfitting, which results in a low
predictive performance. Ensemble techniques are able to achieve a higher
accuracy. However, this comes at a cost of losing interpretability of the
resulting model. This makes ensemble techniques impractical in applications
where decision support, instead of decision making, is crucial.
  To bridge this gap, we present the GENESIM algorithm that transforms an
ensemble of decision trees to a single decision tree with an enhanced
predictive performance by using a genetic algorithm. We compared GENESIM to
prevalent decision tree induction and ensemble techniques using twelve publicly
available data sets. The results show that GENESIM achieves a better predictive
performance on most of these data sets than decision tree induction techniques
and a predictive performance in the same order of magnitude as the ensemble
techniques. Moreover, the resulting model of GENESIM has a very low complexity,
making it very interpretable, in contrast to ensemble techniques.


title: Achievable Uplink Rates for Massive MIMO with Coarse Quantization

abstract:
  The high hardware complexity of a massive MIMO base station, which requires
hundreds of radio chains, makes it challenging to build commercially. One way
to reduce the hardware complexity and power consumption of the receiver is to
lower the resolution of the analog-to-digital converters (ADCs). We derive an
achievable rate for a massive MIMO system with arbitrary quantization and use
this rate to show that ADCs with as low as 3 bits can be used without
significant performance loss at spectral efficiencies around 3.5 bpcu per user,
also under interference from stronger transmitters and with some imperfections
in the automatic gain control.


title: Unimodal Thompson Sampling for Graph-Structured Arms

abstract:
  We study, to the best of our knowledge, the first Bayesian algorithm for
unimodal Multi-Armed Bandit (MAB) problems with graph structure. In this
setting, each arm corresponds to a node of a graph and each edge provides a
relationship, unknown to the learner, between two nodes in terms of expected
reward. Furthermore, for any node of the graph there is a path leading to the
unique node providing the maximum expected reward, along which the expected
reward is monotonically increasing. Previous results on this setting describe
the behavior of frequentist MAB algorithms. In our paper, we design a Thompson
Sampling-based algorithm whose asymptotic pseudo-regret matches the lower bound
for the considered setting. We show that -as it happens in a wide number of
scenarios- Bayesian MAB algorithms dramatically outperform frequentist ones. In
particular, we provide a thorough experimental evaluation of the performance of
our and state-of-the-art algorithms as the properties of the graph vary.


title: PolyNet: A Pursuit of Structural Diversity in Very Deep Networks

abstract:
  A number of studies have shown that increasing the depth or width of
convolutional networks is a rewarding approach to improve the performance of
image recognition. In our study, however, we observed difficulties along both
directions. On one hand, the pursuit for very deep networks is met with a
diminishing return and increased training difficulty; on the other hand,
widening a network would result in a quadratic growth in both computational
cost and memory demand. These difficulties motivate us to explore structural
diversity in designing deep networks, a new dimension beyond just depth and
width. Specifically, we present a new family of modules, namely the
PolyInception, which can be flexibly inserted in isolation or in a composition
as replacements of different parts of a network. Choosing PolyInception modules
with the guidance of architectural efficiency can improve the expressive power
while preserving comparable computational cost. The Very Deep PolyNet, designed
following this direction, demonstrates substantial improvements over the
state-of-the-art on the ILSVRC 2012 benchmark. Compared to Inception-ResNet-v2,
it reduces the top-5 validation error on single crops from 4.9% to 4.25%, and
that on multi-crops from 3.7% to 3.45%.


title: Conformally-modified gravity and vacuum energy

abstract:
  The paper deals with a modified theory of gravity and the cosmological
consequences. Instead of concerning the field equations directly, we modify a
conformally-related and equivalent equation, such that a spontaneous symmetry
breaking at Planck scale occurs in the trace equation. As the consequence the
cosmological constant problem is solved.


title: Who's afraid of the Unit Quaternion ?

abstract:
  Far from being just a 2-level Quantum system the Qubit is a Unit Quaternion,
also known as a Spinor. Therefore it follows that the Qubit is a 4-dimensional
vector which traces a path on the surface of the unit 3-sphere. This is the
meaning of the global phase.


title:
Component structure of the configuration model: barely supercritical
  case

abstract:
  We study near-critical behavior in the configuration model. Let $D_n$ be the
degree of a random vertex. We let $\nu_n={\mathbb E} [D_n(D_n-1)]/{\mathbb
E}[D_n]$ and, assuming that $\nu_n \to 1$ as $n \to \infty$, we write
$\varepsilon_n=\nu_n-1$. We call the setting where $\varepsilon_n
n^{1/3}/({\mathbb E}[D_n^3])^{2/3} \to \infty$ the {\it barely supercritical}
regime. We further assume that the variance of $D_n$ is uniformly bounded as $n
\to \infty$.
  Let $D_n^*$ denote the size-biased version of $D_n$. We prove that there is a
unique giant component of size $n \rho_n {\mathbb E} D_n (1+o(1))$, where
$\rho_n$ denotes the survival probability of a branching process with offspring
distribution $D_n^*-1$. This extends earlier results of Janson and
Luczak~\cite{JanLuc07}, as well as those of Janson, Luczak, Windridge and
House~\cite{SJ300} to the case where the third moment of $D_n$ is unbounded,
filling the gap in the literature.
  We further study the size of the largest component in the \emph{critical}
regime, where $\varepsilon_n = O(n^{-1/3} ({\mathbb E} D_n^3)^{2/3})$,
extending and complementing results of Hatami and Molloy~\cite{HatamiMolloy}.


title:
Unsteady Aerodynamics and Vortex-sheet Formation of A Two-dimensional
  Airfoil

abstract:
  Unsteady inviscid flow models of wings and airfoils have been developed to
study the aerodynamics of natural and man-made flyers. Vortex methods have been
extensively applied to reduce the dimensionality of these aerodynamic models,
based on the proper estimation of the strength and distribution of the vortices
in the wake. In such modeling approaches, one of the most fundamental questions
is how the vortex sheets are generated and released from sharp edges. To
determine the formation of the trailing-edge vortex sheet, the classical Kutta
condition can be extended to unsteady situations by realizing that a flow
cannot turn abruptly around a sharp edge. This condition can be readily applied
to a flat plate or an airfoil with cusped trailing edge since the direction of
the forming vortex sheet is known to be tangential to the trailing edge.
However, for a finite-angle trailing edge, or in the case of flow separation
away from a sharp corner, the direction of the forming vortex sheet is
ambiguous. To remove any ad-hoc implementation, the unsteady Kutta condition,
the conservation of circulation, as well as the conservation laws of mass and
momentum are coupled to analytically solve for the angle, strength, and
relative velocity of the trailing-edge vortex sheet. The two-dimensional
aerodynamic model together with the proposed vortex-sheet formation condition
is verified by comparing flow structures and force calculations with
experimental results for airfoils in steady and unsteady background flows.


title:
No double detonations but core carbon ignitions in high-resolution,
  grid-based simulations of binary white dwarf mergers

abstract:
  We study the violent phase of the merger of massive binary white dwarf
systems. Our aim is to characterize the conditions for explosive burning to
occur, and identify a possible explosion mechanism of Type Ia supernovae. The
primary components of our model systems are carbon-oxygen (C/O) white dwarfs,
while the secondaries are made either of C/O or of pure helium. We account for
tidal effects in the initial conditions in a self-consistent way, and consider
initially well-separated systems with slow inspiral rates. We study the merger
evolution using an adaptive mesh refinement, reactive, Eulerian code in three
dimensions, assuming symmetry across the orbital plane. We use a co-rotating
reference frame to minimize the effects of numerical diffusion, and solve for
self-gravity using a multi-grid approach. We find a novel detonation mechanism
in C/O mergers with massive primaries. Here the detonation occurs in the
primary's core and relies on the combined action of tidal heating, accretion
heating, and self-heating due to nuclear burning. The exploding structure is
compositionally stratified, with a reverse shock formed at the surface of the
dense ejecta. The existence of such a shock has not been reported elsewhere.
The explosion energy ($1.6\times 10^{51}$ erg) and $^{56}$Ni mass (0.86
M$_\odot$) are consistent with a SN Ia at the bright end of the luminosity
distribution, with an approximated decline rate of $\Delta m_{15}(B)\approx
0.99$. Our study does not support double-detonation scenarios in the case of a
system with a 0.6 M$_\odot$ helium secondary and a 0.9 M$_\odot$ primary.
Although the accreted helium detonates, it fails to ignite carbon at the base
of the boundary layer or in the primary's core.

categories: astro-ph.SR astro-ph.HE physics.comp-ph physics.flu-dyn physics.plasm-ph


title: Influence of the Centaurs and TNOs on the main belt and its families

abstract:
  Centaurs are objects whose orbits are found between those of the giant
planets. They are supposed to originate mainly from the TransNeptunian objects,
and they are among the sources of NearEarth Objects.TransNeptunian Objects
(TNOs) cross Neptune's orbit and produce the Centaurs. We investigate their
interactions with main belt asteroids to determine if chaotic scattering caused
by close encounters and impacts by these bodies may have played a role in the
dynamical evolution of the main belt. We find that Centaurs and TNOs that reach
the inner Solar System can modify the orbits of main belt asteroids, though
only if their mass is of the order of 1 billion less the mass of the sun for
single encounters or, one order less in the case of multiple close encounters.
Centaurs and TNOs are unlikely to have significantly dispersed young asteroid
families in the main belt, but they can have perturbed some old asteroid
families. Current main belt asteroids that originated as Centaurs or
Trans-Neptunian Objects may lie in the outer belt with short lifetime less than
4 My, most likely between 2.8 au and 3.2 au at larger eccentricities than
typical of main belt asteroids.


title: Revisiting the Amati and Yonetoku Correlations with Swift GRBs

abstract:
  We use a sample of \textit{Swift} gamma-ray bursts (GRBs) to analyze the
Amati and Yonetoku correlations. The first relation is between $E_{p,i}$, the
intrinsic peak energy of the prompt GRB emission, and $E_{iso}$, the equivalent
isotropic energy. The second relation is between $E_{p,i}$ and $L_{iso}$, the
isotropic peak luminosity. We select a sample of 71 \textit{Swift} GRBs that
have a measured redshift and whose observed $E^{obs}_p$ is within the interval
of energy 15-150 keV with a relative uncertainty of less than 70\%. We seek to
find correlation relations for long-duration GRBs (LGRBs) with a peak photon
flux $P_{ph}\geq 2.6~ \mathrm{ph/cm^{2}/s}$. Uncertainties (error bars) on the
values of the calculated energy flux \textit{P}, the energy $E_{iso}$, and the
peak isotropic luminosity $L_{iso}$ are estimated using a Monte Carlo approach.
We find 27 \textit{Swift} LGRBs that satisfy all our constraints. Results of
our analyses of the sample of 71 GRBs and the selected subsample (27 GRBs) are
in good agreement with published results. The plots of the two relations for
all bursts show a large dispersion around the best straight lines in the sample
of 71 LGRBs but not so much in the subsample of 27 GRBs.


title: Substitution-based sequences with absolutely continuous diffraction

abstract:
  Modifying Rudin's original construction of the Rudin-Shapiro sequence, we
derive a new substitution-based sequence with purely absolutely continuous
diffraction spectrum.


title:
Separable Representation of Multichannel Nucleon-Nucleus Optical
  Potentials

abstract:
  One important ingredient for many applications of nuclear physics to
astrophysics, nuclear energy, and stockpile stewardship are cross sections for
reactions of neutrons with rare isotopes. Since direct measurements are often
not feasible, indirect methods, e.g. (d,p) reactions, should be used. Those
(d,p) reactions may be viewed as three-body reactions and described with
Faddeev techniques. Faddeev equations in momentum space have a long tradition
of utilizing separable interactions in order to arrive at sets of coupled
integral equations in one variable. Optical potentials representing the
effective interactions in the neutron (proton) nucleus subsystem are usually
non-Hermitian as well as energy-dependent. Including excitations of the nucleus
in the calculation requires a multichannel optical potential. The purpose of
this paper is to introduce a separable, energy-dependent multichannel
representation of complex, energy-dependent optical potentials that contain
excitations of the nucleus and that fulfill reciprocity exactly. Momentum space
Lippmann-Schwinger integral equations are solved with standard techniques to
obtain the form factors for the separable representation. Starting from
energy-dependent multichannel optical potentials for neutron and proton
scattering from $^{12}$C, separable representations based on a generalization
of the Ernst-Shakin-Thaler (EST) scheme are constructed which fulfill
reciprocity exactly. Applications to n$+^{12}$C and p$+^{12}$C scattering are
investigated for energies from 0 to 50~MeV.


title:
Optimal Dynamic Coverage Infrastructure for Large-Scale Fleets of
  Reconnaissance UAVs

abstract:
  Current state of the art in the field of UAV activation relies solely on
human operators for the design and adaptation of the drones' flying routes.
Furthermore, this is being done today on an individual level (one vehicle per
operators), with some exceptions of a handful of new systems, that are
comprised of a small number of self-organizing swarms, manually guided by a
human operator.
  Drones-based monitoring is of great importance in variety of civilian
domains, such as road safety, homeland security, and even environmental
control. In its military aspect, efficiently detecting evading targets by a
fleet of unmanned drones has an ever increasing impact on the ability of modern
armies to engage in warfare. The latter is true both traditional symmetric
conflicts among armies as well as asymmetric ones. Be it a speeding driver, a
polluting trailer or a covert convoy, the basic challenge remains the same --
how can its detection probability be maximized using as little number of drones
as possible.
  In this work we propose a novel approach for the optimization of large scale
swarms of reconnaissance drones -- capable of producing on-demand optimal
coverage strategies for any given search scenario. Given an estimation cost of
the threat's potential damages, as well as types of monitoring drones available
and their comparative performance, our proposed method generates an
analytically provable strategy, stating the optimal number and types of drones
to be deployed, in order to cost-efficiently monitor a pre-defined region for
targets maneuvering using a given roads networks.
  We demonstrate our model using a unique dataset of the Israeli transportation
network, on which different deployment schemes for drones deployment are
evaluated.


title: Hairpins in the conformations of a confined polymer

abstract:
  If a semiflexible polymer confined to a narrow channel bends around by 180
degrees, the polymer is said to exhibit a hairpin. The equilibrium extension
statistics of the confined polymer are well understood when hairpins are
vanishingly rare or when they are plentiful. Here we analyze the extension
statistics in the intermediate situation via experiments with DNA coated by the
protein RecA, which enhances the stiffness of the DNA molecule by approximately
one order of magnitude. We find that the extension distribution is highly
non-Gaussian, in good agreement with Monte Carlo simulations of confined
discrete wormlike chains. We develop a simple model that qualitatively explains
the form of the extension distribution. The model shows that the tail of the
distribution at short extensions is determined by conformations with one
hairpin.


title: Telekinetic Entanglement

abstract:
  A numerical thought experiment with two momentum correlated particles is
presented, in which particle A passes through a series of zig-zagging slits and
particle B moves unobstructedly. It is shown that, if particle A's meandering
path is monitored by successive non-detections, particle B will loosely adhere
to a similar trajectory without violating momentum conservation. The discussion
relates this apparent telekinetic influence, which is a standard quantum
mechanical result, to supposedly real telekinesis and to Stapp's hypothesis on
intention in quantum physics.


title: Universal locality of quantum thermal susceptibility

abstract:
  The ultimate precision of any measurement of the temperature of a quantum
system is the inverse of the local quantum thermal susceptibility [De Pasquale
et al., Nature Communications 7, 12782 (2016)] of the subsystem with whom the
thermometer interacts. If this subsystem can be described with the canonical
ensemble, such quantity reduces to the variance of the local Hamiltonian, that
is proportional to the heat capacity of the subsystem. However, the canonical
ensemble might not apply in the presence of interactions between the subsystem
and the rest of the system. In this work we address this problem in the
framework of locally interacting quantum systems. We prove that the local
quantum thermal susceptibility of any subsystem is close to the variance of its
local Hamiltonian, provided the volume to surface ratio of the subsystem is
much larger than the correlation length. This result greatly simplifies the
determination of the ultimate precision of any local estimate of the
temperature, and rigorously determines the regime where interactions can affect
this precision.


title:
Ionization and feedback in Ly$\alpha$ halos around two radio galaxies at
  z$\sim$2.5

abstract:
  We present new spectroscopic observations of two high redshift radio
galaxies, TXS 0211-122 (z=2.34) and TXS 0828+193 (z=2.57), known to be
associated with large Ly$\alpha$ halos. The observations were taken with the
slits placed perpendicularly to the radio axis. With access to pre-existing
Keck II observations taken with the slit placed along the radio axis we are
able to compare the properties of the gas in different regions of the galaxies.
  In both objects we detect spatially extended Ly$\alpha$ emission
perpendicularly to the radio axis. In TXS 0211-122, the flux and velocity
profiles of Ly$\alpha$ are strongly affected by HI absorption/scattering. In
line with previous studies, we find evidence for outflowing gas along the radio
axis which may be the result of jet-gas interactions. In the slit oriented
perpendicularly to the radio axis we find less perturbed gas kinematics,
suggesting outflows of ionized gas in this object are focused along the radio
jet axis. Additionally, we find evidence for a giant, UV-emitting arc or
shell-like structure surrounding the radio galaxy Ly$\alpha$ halo, possibly
resulting from feedback activity.
  In TXS 0828+193 a large Ly$\alpha$ halo ($\sim$56 kpc) is detected
perpendicularly to the radio axis. Along both slit position angles we find
evidence for outflowing gas, which we argue is part of an approximately
spherical, expanding shell or bubble of gas powered by feedback activity in the
central regions of the galaxy. Our results suggest a diversity in the spatial
distribution of ionized outflows in powerful radio galaxies at z$\sim$2.5.


title: Fast Non-Parametric Tests of Relative Dependency and Similarity

abstract:
  We introduce two novel non-parametric statistical hypothesis tests. The first
test, called the relative test of dependency, enables us to determine whether
one source variable is significantly more dependent on a first target variable
or a second. Dependence is measured via the Hilbert-Schmidt Independence
Criterion (HSIC). The second test, called the relative test of similarity, is
use to determine which of the two samples from arbitrary distributions is
significantly closer to a reference sample of interest and the relative measure
of similarity is based on the Maximum Mean Discrepancy (MMD). To construct
these tests, we have used as our test statistics the difference of HSIC
statistics and of MMD statistics, respectively. The resulting tests are
consistent and unbiased, and have favorable convergence properties. The
effectiveness of the relative dependency test is demonstrated on several
real-world problems: we identify languages groups from a multilingual parallel
corpus, and we show that tumor location is more dependent on gene expression
than chromosome imbalance. We also demonstrate the performance of the relative
test of similarity over a broad selection of model comparisons problems in deep
generative models.


title:
Estimation of reproduction number and non stationary spectral analysis
  of Dengue epidemic

abstract:
  In this work we analyze the post monsoon Dengue outbreaks by analyzing the
transient and long term dynamics of Dengue incidences and its environmental
correlates in Ahmedabad city in western India from 2005-2012. We calculate the
reproduction number $R_p$ using the growth rate of post monsoon Dengue
outbreaks and biological parameters like host and vector incubation periods and
vector mortality rate, and its uncertainties are estimated through Monte-Carlo
simulations by sampling parameters from their respective probability
distributions. Reduction in Female Aedes mosquito density required for an
effective prevention of Dengue outbreaks is also calculated. The non stationary
pattern of Dengue incidences and its climatic correlates like rainfall
temperature is analyzed through Wavelet based methods. We find that the mean
time lag between peak of monsoon and Dengue is 9 weeks. Monsoon and Dengue
cases are phase locked from 2008-2012 in the 16-32 weeks band. The duration of
post monsoon outbreak has been increasing every year, especially post 2008,
even though the intensity and duration of monsoon has been decreasing.
Temperature and Dengue incidences show correlations in the same band, but phase
lock is not stationary.


title: Building Deep Networks on Grassmann Manifolds

abstract:
  Learning representations on Grassmann manifolds is popular in quite a few
visual recognition tasks. In order to enable deep learning on Grassmann
manifolds, this paper proposes a deep network architecture by generalizing the
Euclidean network paradigm to Grassmann manifolds. In particular, we design
full rank mapping layers to transform input Grassmannian data to more desirable
ones, exploit re-orthonormalization layers to normalize the resulting matrices,
study projection pooling layers to reduce the model complexity in the
Grassmannian context, and devise projection mapping layers to respect
Grassmannian geometry and meanwhile achieve Euclidean forms for regular output
layers. To train the Grassmann networks, we exploit a stochastic gradient
descent setting on manifolds of the connection weights, and study a matrix
generalization of backpropagation to update the structured data. The
evaluations on three visual recognition tasks show that our Grassmann networks
have clear advantages over existing Grassmann learning methods, and achieve
results comparable with state-of-the-art approaches.


title: Relational Multi-Manifold Co-Clustering

abstract:
  Co-clustering targets on grouping the samples (e.g., documents, users) and
the features (e.g., words, ratings) simultaneously. It employs the dual
relation and the bilateral information between the samples and features. In
many realworld applications, data usually reside on a submanifold of the
ambient Euclidean space, but it is nontrivial to estimate the intrinsic
manifold of the data space in a principled way. In this study, we focus on
improving the co-clustering performance via manifold ensemble learning, which
is able to maximally approximate the intrinsic manifolds of both the sample and
feature spaces. To achieve this, we develop a novel co-clustering algorithm
called Relational Multi-manifold Co-clustering (RMC) based on symmetric
nonnegative matrix tri-factorization, which decomposes the relational data
matrix into three submatrices. This method considers the intertype relationship
revealed by the relational data matrix, and also the intra-type information
reflected by the affinity matrices encoded on the sample and feature data
distributions. Specifically, we assume the intrinsic manifold of the sample or
feature space lies in a convex hull of some pre-defined candidate manifolds. We
want to learn a convex combination of them to maximally approach the desired
intrinsic manifold. To optimize the objective function, the multiplicative
rules are utilized to update the submatrices alternatively. Besides, both the
entropic mirror descent algorithm and the coordinate descent algorithm are
exploited to learn the manifold coefficient vector. Extensive experiments on
documents, images and gene expression data sets have demonstrated the
superiority of the proposed algorithm compared to other well-established
methods.


title: Compensating for Large In-Plane Rotations in Natural Images

abstract:
  Rotation invariance has been studied in the computer vision community
primarily in the context of small in-plane rotations. This is usually achieved
by building invariant image features. However, the problem of achieving
invariance for large rotation angles remains largely unexplored. In this work,
we tackle this problem by directly compensating for large rotations, as opposed
to building invariant features. This is inspired by the neuro-scientific
concept of mental rotation, which humans use to compare pairs of rotated
objects. Our contributions here are three-fold. First, we train a Convolutional
Neural Network (CNN) to detect image rotations. We find that generic CNN
architectures are not suitable for this purpose. To this end, we introduce a
convolutional template layer, which learns representations for canonical
'unrotated' images. Second, we use Bayesian Optimization to quickly sift
through a large number of candidate images to find the canonical 'unrotated'
image. Third, we use this method to achieve robustness to large angles in an
image retrieval scenario. Our method is task-agnostic, and can be used as a
pre-processing step in any computer vision system.


title:
Dynamic localization in optical and Zeeman lattices in the presence of
  spin-orbit coupling

abstract:
  The dynamic localization of a two-level atom in a periodic potential under
the action of spin-orbit coupling and a weak harmonically-varying linear force
is studied. We consider optical and Zeeman potentials that are either in-phase
or out-of-phase in two spinor components, respectively. The expectation value
for the position of the atom after one oscillation period of the linear force
is recovered in authentic resonances or in pseudo-resonances. The frequencies
of the linear force corresponding to authentic resonances are determined by the
band structure of the periodic potential and are affected by the spin-orbit
coupling. The width/dispersion of the wavepacket in authentic resonances is
usually minimal. The frequencies corresponding to pseudo-resonances do not
depend on the type of potential and on the strength of the spin-orbit coupling,
while the evolution of excitations at the corresponding frequencies is usually
accompanied by significant dispersion. Pseudo-resonances are determined by the
initial phase of the linear force and by the quasi-momentum of the wavepacket.
Due to the spinor nature of the system, the motion of the atom is accompanied
by periodic, but not harmonic, spin oscillations. Under the action of
spin-orbit coupling the oscillations of the wavepacket can be nearly completely
suppressed in optical lattices. Dynamic localization in Zeeman lattices is
characterized by doubling of the resonant oscillation periods due to band
crossing at the boundary of the Brillouin zone. We also show that higher
harmonics in the Fourier expansion of the energy band lead to effective
dispersion, which can be strong enough to prevent dynamic localization of the
Bloch wavepacket.


title: Note on k-planar crossing numbers

abstract:
  The crossing number $cr(G)$ of a graph $G=(V,E)$ is the smallest number of
edge crossings over all drawings of $G$ in the plane. For any $k\ge 1$, the
$k$-planar crossing number of $G$, $cr_k(G)$, is defined as the minimum of
$cr(G_0)+cr(G_1)+\ldots+cr(G_{k-1})$ over all graphs $G_0, G_1,\ldots, G_{k-1}$
with $\cup_{i=0}^{k-1}G_i=G$. It is shown that for every $k\ge 1$, we have
$cr_k(G)\le \left(\frac{2}{k^2}-\frac1{k^3}\right)cr(G)$. This bound does not
remain true if we replace the constant $\frac{2}{k^2}-\frac1{k^3}$ by any
number smaller than $\frac1{k^2}$. Some of the results extend to the
rectilinear variants of the $k$-planar crossing number.


title: Landau Levels in Lattice QCD

abstract:
  The spectrum of the two-dimensional continuum Dirac operator in the presence
of a uniform background magnetic field consists of Landau levels, which are
degenerate and separated by gaps. On the lattice the Landau levels are spread
out by discretization artefacts, but a remnant of their structure is clearly
visible (Hofstadter butterfly). If one switches on a non-Abelian interaction,
the butterfly structure will be smeared out, but the lowest Landau level (LLL)
will still be separated by a gap from the rest of the spectrum. In this talk we
discuss how one can define the LLL in QCD and check how well certain physical
quantities are approximated by taking into account only the LLL.


title:
On global stability of the Lotka reactions with generalized mass-action
  kinetics

abstract:
  Chemical reaction networks with generalized mass-action kinetics lead to
power-law dynamical systems. As a simple example, we consider the Lotka
reactions with two chemical species and arbitrary power-law kinetics. We study
existence, uniqueness, and stability of the positive equilibrium, in
particular, we characterize its global asymptotic stability in terms of the
kinetic orders.


title:
Semiclassical Identification of Periodic Orbits in a Quantum Many-Body
  System

abstract:
  While a wealth of results has been obtained for chaos in single-particle
quantum systems, much less is known about chaos in quantum many-body systems.
We contribute to recent efforts to make a semiclassical analysis of such
systems feasible, which is nontrivial due to the exponential proliferation of
orbits with increasing particle number. Employing a recently discovered duality
relation, we focus on the collective, coherent motion that together with the
also present incoherent one typically leads to a mixture of regular and chaotic
dynamics. We investigate a kicked spin chain as an example of a presently
experimentally and theoretically much studied class of systems.


title: The determination of $\alpha_s$ by the ALPHA collaboration

abstract:
  We review the ALPHA collaboration strategy for obtaining the QCD coupling at
high scale. In the three-flavor effective theory it avoids the use of
perturbation theory at $\alpha > 0.2$ and at the same time has the physical
scales small compared to the cutoff $1/a$ in all stages of the computation. The
result $\Lambda_\overline{MS}^{(3)}=332(14)$~MeV is translated to
$\alpha_\overline{MS}(m_Z)=0.1179(10)(2)$ by use of (high order) perturbative
relations between the effective theory couplings at the charm and beauty quark
"thresholds". The error of this perturbative step is discussed and estimated as
$0.0002$.


title:
A Multi-Modal Graph-Based Semi-Supervised Pipeline for Predicting Cancer
  Survival

abstract:
  Cancer survival prediction is an active area of research that can help
prevent unnecessary therapies and improve patient's quality of life. Gene
expression profiling is being widely used in cancer studies to discover
informative biomarkers that aid predict different clinical endpoint prediction.
We use multiple modalities of data derived from RNA deep-sequencing (RNA-seq)
to predict survival of cancer patients. Despite the wealth of information
available in expression profiles of cancer tumors, fulfilling the
aforementioned objective remains a big challenge, for the most part, due to the
paucity of data samples compared to the high dimension of the expression
profiles. As such, analysis of transcriptomic data modalities calls for
state-of-the-art big-data analytics techniques that can maximally use all the
available data to discover the relevant information hidden within a significant
amount of noise. In this paper, we propose a pipeline that predicts cancer
patients' survival by exploiting the structure of the input (manifold learning)
and by leveraging the unlabeled samples using Laplacian support vector
machines, a graph-based semi supervised learning (GSSL) paradigm. We show that
under certain circumstances, no single modality per se will result in the best
accuracy and by fusing different models together via a stacked generalization
strategy, we may boost the accuracy synergistically. We apply our approach to
two cancer datasets and present promising results. We maintain that a similar
pipeline can be used for predictive tasks where labeled samples are expensive
to acquire.


title:
Recent results on collective effects in small systems from PHENIX at
  RHIC

abstract:
  Collisions of simple systems, such as $p$+$p$, or $p$+Nucleus have been used
as benchmarks for our understanding of heavy ion collsions, since it was
assumed they would be free of the effects from hot nuclear matter.
  Recently long range correlations and anisotropies of momentum spectra have
been seen in such collisions, challenging this assumption. Such phenomena have
been understood to be the result of the collective motion, which can best be
described by hydrodynamics, whose initial conditions are set by the geometry of
the colliding systems, together with their fluctuations. This talk will discuss
the recent results from the PHENIX experiment at RHIC using a variety of
colliding species ($p$+Au, $d$+Au, $^{3}$He+Au) that give a better
understanding of the origin of the observed correlations and anisotropies, thus
providing insight as to whether a quark gluon plasma is formed in these simple
systems.


title: Maximizing a Submodular Function with Viability Constraints

abstract:
  We study the problem of maximizing a monotone submodular function with
viability constraints. This problem originates from computational biology,
where we are given a phylogenetic tree over a set of species and a directed
graph, the so-called food web, encoding viability constraints between these
species. These food webs usually have constant {depth}. The goal is to select a
subset of $k$ species that satisfies the viability constraints and has maximal
phylogenetic diversity. As this problem is known to be NP-hard, we investigate
approximation algorithms. We present the first constant factor approximation
algorithm if the depth is constant. Its approximation ratio is
$(1-\frac{1}{\sqrt{e}})$. This algorithm not only applies to phylogenetic trees
with viability constraints but for arbitrary monotone submodular set functions
with viability constraints. Second, we show that there is no
$(1-1/e+\epsilon)$-approximation algorithm for our problem setting (even for
additive functions) and that there is no approximation algorithm for a slight
extension of this setting.


title: Separating quantum communication and approximate rank

abstract:
  One of the best lower bound methods for the quantum communication complexity
of a function H (with or without shared entanglement) is the logarithm of the
approximate rank of the communication matrix of H. This measure is essentially
equivalent to the approximate gamma_2 norm and generalized discrepancy, and
subsumes several other lower bounds. All known lower bounds on quantum
communication complexity in the general unbounded-round model can be shown via
the logarithm of approximate rank, and it was an open problem to give any
separation at all between quantum communication complexity and the logarithm of
the approximate rank.
  In this work we provide the first such separation: We exhibit a total
function H with quantum communication complexity almost quadratically larger
than the logarithm of its approximate rank. We construct H using the
communication lookup function framework of Anshu et al. (FOCS 2016) based on
the cheat sheet framework of Aaronson et al. (STOC 2016). From a starting
function F, this framework defines a new function H=F_G. Our main technical
result is a lower bound on the quantum communication complexity of F_G in terms
of the discrepancy of F, which we do via quantum information theoretic
arguments. We show the upper bound on the approximate rank of F_G by relating
it to the Boolean circuit size of the starting function F.


title:
Cross-Domain Face Verification: Matching ID Document and Self-Portrait
  Photographs

abstract:
  Cross-domain biometrics has been emerging as a new necessity, which poses
several additional challenges, including harsh illumination changes, noise,
pose variation, among others. In this paper, we explore approaches to
cross-domain face verification, comparing self-portrait photographs ("selfies")
to ID documents. We approach the problem with proper image photometric
adjustment and data standardization techniques, along with deep learning
methods to extract the most prominent features from the data, reducing the
effects of domain shift in this problem. We validate the methods using a novel
dataset comprising 50 individuals. The obtained results are promising and
indicate that the adopted path is worth further investigation.


title: Reversing and extended symmetries of shift spaces

abstract:
  The reversing symmetry group is considered in the setting of symbolic
dynamics. While this group is generally too big to be analysed in detail, there
are interesting cases with some form of rigidity where one can determine all
symmetries and reversing symmetries explicitly. They include Sturmian shifts as
well as classic examples such as the Thue--Morse system with various
generalisations or the Rudin--Shapiro system. We also look at generalisations
of the reversing symmetry group to higher-dimensional shift spaces, then called
the group of \emph{extended symmetries}. We develop their basic theory for
faithful $\mathbb{Z}^{d}$-actions, and determine the extended symmetry group of
the chair tiling shift, which can be described as a model set, and of
Ledrappier's shift, which is an example of algebraic origin.


title:
Disfavouring Electroweak Baryogenesis and a hidden Higgs in a
  CP-violating Two-Higgs-Doublet Model

abstract:
  A strongly first-order electroweak phase transition is a necessary
requirement for Electroweak Baryogenesis. We investigate the plausibility of
obtaining a strong phase transition in a Two-Higgs-Doublet Model of type II
with a minimal amount of $CP$ violation. By performing a Bayesian fit where we
constrain the scalar sector with indirect and direct measurements, we find that
current data disfavours a first-order phase transition in this model. This
result is mainly driven by the interplay of three effects: Constraints from the
LHC Higgs data on the magnitude of the quartic couplings, the requirement of a
$H^\pm$ heavier than around 490 GeV to avoid large contributions to $BR(b
\rightarrow s\gamma)$ and the fact that a first-order phase transition requires
relatively light scalar states in addition to the 125 GeV Higgs. For similar
reasons we find that a "hidden-Higgs" scenario, in which the 125 GeV state is
identified with the next-to-lightest scalar, is disfavoured by current data
independent of any requirement on the phase transition strength.


title:
The magnetic field and turbulence of the cosmic web measured using a
  brilliant fast radio burst

abstract:
  Fast radio bursts (FRBs) are millisecond-duration events thought to originate
beyond the Milky Way galaxy. Uncertainty surrounding the burst sources, and
their propagation through intervening plasma, has limited their use as
cosmological probes. We report on a mildly dispersed (dispersion measure
266.5+-0.1 pc cm^-3), exceptionally intense (120+-30 Jy), linearly polarized,
scintillating burst (FRB 150807) that we directly localize to 9 arcmin^2. Based
on a low Faraday rotation (12.0+-0.7 rad m^-2), we infer negligible
magnetization in the circum-burst plasma and constrain the net magnetization of
the cosmic web along this sightline to <21 nG, parallel to the line-of-sight.
The burst scintillation suggests weak turbulence in the ionized intergalactic
medium.


title: Premetric equivalent of general relativity: Teleparallelism

abstract:
  In general relativity (GR), the metric tensor of spacetime is essential since
it represents the gravitational potential. In other gauge theories (such as
electromagnetism), the so-called premetric approach succeeds in separating the
purely topological field equation from the metric-dependent constitutive law.
We show here that GR allows for a premetric formulation, too. For this purpose,
we apply the teleparallel approach of gravity, which represents GR as a gauge
theory based on the translation group. We formulate the metric-free topological
field equation and a general linear constitutive law between the basic field
variables. The requirement of local Lorentz invariance turns the model into a
full equivalent of GR. Our approach opens a way for a natural extension of GR
to diverse geometrical structures of spacetime.


title: Examining the Impact of Blur on Recognition by Convolutional Networks

abstract:
  State-of-the-art algorithms for many semantic visual tasks are based on the
use of convolutional neural networks. These networks are commonly trained, and
evaluated, on large annotated datasets of artifact-free high-quality images. In
this paper, we investigate the effect of one such artifact that is quite common
in natural capture settings: optical blur. We show that standard network
models, trained only on high-quality images, suffer a significant degradation
in performance when applied to those degraded by blur due to defocus, or
subject or camera motion. We investigate the extent to which this degradation
is due to the mismatch between training and input image statistics.
Specifically, we find that fine-tuning a pre-trained model with blurred images
added to the training set allows it to regain much of the lost accuracy. We
also show that there is a fair amount of generalization between different
degrees and types of blur, which implies that a single network model can be
used robustly for recognition when the nature of the blur in the input is
unknown. We find that this robustness arises as a result of these models
learning to generate blur invariant representations in their hidden layers. Our
findings provide useful insights towards developing vision systems that can
perform reliably on real world images affected by blur.


title: Proposed experiment to test fundamentally binary theories

abstract:
  Fundamentally binary theories are nonsignaling theories in which measurements
of many outcomes are constructed by selecting from binary measurements. They
constitute a sensible alternative to quantum theory and have never been
directly falsified by any experiment. Here we show that fundamentally binary
theories are experimentally testable with current technology. For that, we
identify a feasible Bell-type experiment on pairs of entangled qutrits. In
addition, we prove that, for any n, quantum n-ary correlations are not
fundamentally (n-1)-ary. For that, we introduce a family of inequalities that
hold for fundamentally (n-1)-ary theories but are violated by quantum n-ary
correlations.


title: Heat kernels for non-symmetric diffusion operators with jumps

abstract:
  For $d\geq 2$, we establish the existence and uniqueness of heat kernels for
a large class of time-dependent second order diffusion operator with jumps,
which is the sum of time-dependent of a second order elliptic differential
operators non-divergence form and a non-local $\alpha$-stable-type operator
with bounded time-dependent coefficient. Moreover, we obtain sharp two-sided
estimates, gradient estimate and fractional derivative estimate for the heat
kernels under some mild conditions. Our approach is mainly analytic but also
uses some probabilistic techniques.


title: Learning to reinforcement learn

abstract:
  In recent years deep reinforcement learning (RL) systems have attained
superhuman performance in a number of challenging task domains. However, a
major limitation of such applications is their demand for massive amounts of
training data. A critical present objective is thus to develop deep RL methods
that can adapt rapidly to new tasks. In the present work we introduce a novel
approach to this challenge, which we refer to as deep meta-reinforcement
learning. Previous work has shown that recurrent networks can support
meta-learning in a fully supervised context. We extend this approach to the RL
setting. What emerges is a system that is trained using one RL algorithm, but
whose recurrent dynamics implement a second, quite separate RL procedure. This
second, learned RL algorithm can differ from the original one in arbitrary
ways. Importantly, because it is learned, it is configured to exploit structure
in the training domain. We unpack these points in a series of seven
proof-of-concept experiments, each of which examines a key aspect of deep
meta-RL. We consider prospects for extending and scaling up the approach, and
also point out some potentially important implications for neuroscience.


title:
A possible interaction between uncharged particles and the
  Electromagnetic field

abstract:
  Maxwell Electrodynamics can be described either in Minkowski space-time or in
a dynamically equivalent way in a curved geometry constructed in terms of the
electromagnetic field. For this the field must have a superior bound limited by
a maximum value of its energy. After showing such geometric equivalence we
investigate the possibility that new processes dependent on the metric
structure may appear. In particular for very high values of the field a direct
coupling of uncharged particles to the electromagnetic field is predicted.


title:
A new non-iterative self-referencing interferometer in optical phase
  imaging and holographic microscopy, HOLOCAM

abstract:
  Phase retrieval and imaging phase measurements are fields of intense
research. It has recently been shown that phase retrieval from self-referencing
interferograms (SRI) can be reformulated leading to a stable, linear equation
provided the amplitude of the field is known from prior measurement steps
(HOLOCAM). Consequently, the numerical solution thereof is straightforward.
This is a big achievement since convergence is otherwise not always guaranteed.
Applications are expected in X-ray microscopy, general phase retrieval,
holography, tomography and optical imaging.


title:
Constraining alternative theories of gravity using GW$150914$ and
  GW$151226$

abstract:
  The recently reported gravitational wave events GW$150914$ and GW$151226$
caused by the mergers of binary black holes
[arXiv:1602.03841],[arXiv:1606.04855],[arXiv:1606.04856] provide a formidable
way to set constraints on alternative metric theories of gravity in the strong
field regime. In this paper, we develop an approach where an arbitrary theory
of gravity can be parametrised by an effective coupling $G_{eff}$ and an
effective gravitational potential $\Phi(r)$. The standard Newtonian limit of
General Relativity is recovered as soon as $G_{eff}\rightarrow G_N$ and
$\Phi(r)\rightarrow \Phi_{N}$. The upper bound on the graviton mass and the
gravitational interaction length, reported by the LIGO-VIRGO collaboration, can
be directly recast in terms of the parameters of the theory which allows an
analysis where the gravitational wave frequency modulation sets constraints on
the range of possible alternative models of gravity. Numerical results based on
published parameters for the binary black hole mergers are also reported.
Comparison of the observed phase of the GW$150914$ and GW$151226$ with the
modulated phase in alternative theories of gravity does not give reasonable
constraints due the large uncertainties in the estimated parameters for the
coalescing black holes. In addition to these general considerations, we obtain
limits for the frequency dependence of the $\alpha$ parameter in scalar tensor
theories of gravity.


title: Non-degenerate Para-Complex Structures in 6D with Large Symmetry Groups

abstract:
  For an almost product structure $J$ on a manifold $M$ of dimension $6$ with
non-degenerate Nijenhuis tensor $N_J$, we show that the automorphism group
$G=Aut(M,J)$ has dimension at most 14. In the case of equality $G$ is the
exceptional Lie group $G_2^*$. The next possible symmetry dimension is proved
to be equal to 10, and $G$ has Lie algebra $sp(4,R)$. Both maximal and
submaximal symmetric structures are globally homogeneous and strictly nearly
para-K\"ahler. We also demonstrate that whenever the symmetry dimension is at
least 9, then the automorphism algebra acts locally transitively.


title: Distinct spreads in vector spaces over finite fields

abstract:
  In this short note, we study the distribution of spreads in a point set
$\mathcal{P} \subseteq \mathbb{F}_q^d$, which are analogous to angles in
Euclidean space. More precisely, we prove that, for any $\varepsilon > 0$, if
$|\mathcal{P}| \geq (1+\varepsilon) q^{\lceil d/2 \rceil}$, then $\mathcal{P}$
generates a positive proportion of all spreads. We show that these results are
tight, in the sense that there exist sets $\mathcal{P} \subset \mathbb{F}_q^d$
of size $|\mathcal{P}| = q^{\lceil d/2 \rceil}$ that determine at most one
spread.


title: Exceptional $\mathcal N=3$ theories

abstract:
  We present a new construction of four dimensional $\mathcal N=3$ theories,
given by M5 branes wrapping a $T^2$ in an M-theory U-fold background. The
resulting setup generalizes the one used in the usual class $\mathcal S$
construction of four dimensional theories by using an extra discrete symmetry
on the M5 worldvolume. Together with the M-theory U-fold description of $(0,2)$
$E$-type six-dimensional SCFTs, this allows to construct new, exceptional,
$\mathcal N=3$ theories.


title:
Squeezed back-to-back correlations of $\phi\phi$ in Au+Au and d+Au
  collisions at the Relativistic Heavy Ion Collider energies

abstract:
  We investigate the squeezed back-to-back correlations (BBC) of $\phi\phi$,
caused by the mass modification of the particles in the source medium, in the
heavy-ion collisions of Au+Au and d+Au at the Relativistic Heavy Ion Collider
(RHIC) energies. The BBC functions are calculated using the modified masses
extracted from experimental data and the source space-time distributions
provided by the viscous hydrodynamic code VISH2+1. Our investigations indicate
that the BBC of $\phi\phi$ may perhaps be observed in the collisions of d+Au
and the peripheral collisions of Au+Au at the RHIC. We suggest to measure the
BBC experimentally for understanding the mass modifications of the $\phi$ meson
in the collisions.


title: Phase transition in random distance graphs on the torus

abstract:
  We apply here methods of inhomogeneous random graphs to a class of random
distance graphs. This provides an example outside of the rank 1 models which is
still solvable as long as the largest connected component is concerned. In
particular, we show that some random distance graphs behave exactly as the
classical Erd\H{o}s-R\'enyi model not only in the supercritical phase (as was
already known) but in the subcritical case as well.