title:
An extension of the standard model in which parity is conserved at high
  energies

abstract:
  To be compatible with general relativity, every fundamental theory should be
invariant under general coordinate transformations including spatial
reflection. This paper describes an extension of the standard model in which
the action is invariant under spatial reflection, and the vacuum spontaneously
breaks parity by giving a mean value to a pseudoscalar field. This field and
the scalar Higgs field make the gauge bosons, the known fermions, and a set of
mirror fermions suitably massive while avoiding flavor-changing neutral
currents. In the model, there is no strong-CP problem, there are no anomalies,
fermion number (quark-plus-lepton number) is conserved, and heavy mirror
fermions form heavy neutral mirror atoms which are dark-matter candidates. In
models with extended gauge groups, nucleons slowly decay into pions, leptons,
and neutrinos.


title: Thermodynamics of polarized relativistic matter

abstract:
  We give the free energy of equilibrium relativistic matter subject to
external gravitational and electromagnetic fields, to one-derivative order in
the gradients of the external fields. The free energy allows for a
straightforward derivation of bound currents and bound momenta in equilibrium.
At leading order, the energy-momentum tensor admits a simple expression in
terms of the polarization tensor. Beyond the leading order, electric and
magnetic polarization vectors are intrinsically ambiguous. The physical effects
of polarization, such as the correlation between the magneto-vortically induced
surface charge and the electro-vortically induced surface current, are not
ambiguous.


title: Zorich conjecture for hyperelliptic Rauzy-Veech groups

abstract:
  We describe the structure of hyperelliptic Rauzy diagrams and hyperelliptic
Rauzy-Veech groups. In particular, this provides a solution of the
hyperelliptic cases of a conjecture of Zorich on the Zariski closure of
Rauzy-Veech groups.


title:
Electromagnetic effects on the light pseudoscalar mesons and
  determination of $m_u/m_d$

abstract:
  The MILC Collaboration has completed production running of electromagnetic
effects on light mesons using asqtad improved staggered quarks. In these
calculations, we use quenched photons in the noncompact formalism. We study
four lattice spacings from $\approx\!0.12\:$fm to $\approx\!0.045\:$fm. To
study finite-volume effects, we used six spatial lattice sizes $L/a=12$, 16,
20, 28, 40, and 48, at $a\!\approx\!0.12\:$fm. We update our preliminary values
for the correction to Dashen's theorem ($\epsilon$) and the quark-mass ratio
$m_u/m_d$.


title: A detailed framework to incorporate dust in hydrodynamical simulations

abstract:
  Dust plays a key role in the evolution of the ISM and its correct modelling
in numerical simulations is therefore fundamental. We present a new and
self-consistent model that treats grain thermal coupling with the gas,
radiation balance, and surface chemistry for molecular hydrogen. This method
can be applied to any dust distribution with an arbitrary number of grain types
without affecting the overall computational cost. In this paper we describe in
detail the physics and the algorithm behind our approach, and in order to test
the methodology, we present some examples of astrophysical interest, namely (i)
a one-zone collapse with complete gas chemistry and thermochemical processes,
(ii) a 3D model of a low-metallicity collapse of a minihalo starting from
cosmological initial conditions, and (iii) a turbulent molecular cloud with
H-C-O chemistry (277 reactions), together with self-consistent cooling and
heating solved on the fly. Although these examples employ the publicly
available code KROME, our approach can be easily integrated into any
computational framework.


title:
A tight bound for Green's arithmetic triangle removal lemma in vector
  spaces

abstract:
  Let $p$ be a fixed prime. A triangle in $\mathbb{F}_p^n$ is an ordered triple
$(x,y,z)$ of points satisfying $x+y+z=0$. Let $N=p^n=|\mathbb{F}_p^n|$. Green
proved an arithmetic triangle removal lemma which says that for every
$\epsilon>0$ and prime $p$, there is a $\delta>0$ such that if $X,Y,Z \subset
\mathbb{F}_p^n$ and the number of triangles in $X \times Y \times Z$ is at most
$\delta N^2$, then we can delete $\epsilon N$ elements from $X$, $Y$, and $Z$
and remove all triangles. Green posed the problem of improving the quantitative
bounds on the arithmetic triangle removal lemma, and, in particular, asked
whether a polynomial bound holds. Despite considerable attention, prior to this
paper, the best known bound, due to the first author, showed that $1/\delta$
can be taken to be an exponential tower of twos of height logarithmic in
$1/\epsilon$.
  We solve Green's problem, proving an essentially tight bound for Green's
arithmetic triangle removal lemma in $\mathbb{F}_p^n$. We show that a
polynomial bound holds, and further determine the best possible exponent.
Namely, there is a computable number $C_p$ such that we may take $\delta =
(\epsilon/3)^{C_p}$, and we must have $\delta \leq \epsilon^{C_p-o(1)}$. In
particular, $C_2=1+1/(5/3 - \log_2 3) \approx 13.239$, and $C_3=1+1/c_3$ with
$c_3=1-\frac{\log b}{\log 3}$, $b=a^{-2/3}+a^{1/3}+a^{4/3}$, and
$a=\frac{\sqrt{33}-1}{8}$, which gives $C_3 \approx 13.901$. The proof uses
Kleinberg, Sawin, and Speyer's essentially sharp bound on multicolored sum-free
sets, which builds on the recent breakthrough on the cap set problem by
Croot-Lev-Pach, and the subsequent work by Ellenberg-Gijswijt,
Blasiak-Church-Cohn-Grochow-Naslund-Sawin-Umans, and Alon.


title: The MCPM, a two-Higgs-doublet model with maximal CP symmetry, and LHC13

abstract:
  We continue our investigation of the phenomenological consequences of the
MCPM for the LHC experiments. As in any two-Higgs-doublet model we have in the
MCPM three neutral Higgs bosons and one charged Higgs-boson pair $H^\pm$. Here
we discuss the two-photon production in proton-proton collisions. We find that
in the MCPM a resonance-type structure in the $\gamma\gamma$ invariant mass
distribution is predicted around twice the $H^\pm$ mass $m_{H^\pm}$ with a
width $2\; \Gamma_H$ where $\Gamma_H$ is the $H^\pm$ width. If we set
$m_{H^\pm} = 375$ GeV, the above resonance structure appears at 750 GeV with a
width of about 45 GeV. We point out various predictions of the MCPM which
follow in such a scenario and which can be checked at the LHC.


title: Ergodic properties of generalized Ornstein--Uhlenbeck processes

abstract:
  We investigate ergodic properties of generalized Ornstein--Uhlenbeck
processes. In particular, we provide sufficient conditions for ergodicity, and
for subexponential and exponential convergence to the invariant probability
measure. We use the Foster--Lyapunov method. The drift conditions are obtained
using the explicit form of the generator of the continuous process. In some
special cases the optimality of our results can be shown.


title: Global solutions to the Porous medium equations on singular manifolds

abstract:
  The main objective of the present work is to discuss the global existence and
stability of solutions to the porous medium equations on Riemannian manifolds
with singularities. Several different types of solutions are considered. Our
proof is based on a Poincare inequality on function space defined on manifolds
with singularities.


title: NGC 2440 : A morpho-kinematical model

abstract:
  This work describes the modelling of the 3D structure and position-velocity
(P-V) diagrams of NGC 2440, a well known planetary nebula, aiming to describe
the morphology of this object, specially its core. We have used high resolution
spectra and P-V diagrams to reproduce the 3D structure of the nebula using
SHAPE, a software that allows 3D modelling. HST high angular resolution images
were used as reference to the model.
  The observational data point to a segmented core, and the simulations confirm
this assumption; the best model for the nebula is a torus segmented in three
pieces. The simulated P-V diagrams agree with the observations. We suggest that
the torus was torn apart by interaction with the surrounding medium, either as
winds or the radiation field.
  For the two bipolar lobes, orientation angles to the plane of the sky of
$27\pm$5 and $-5\pm3$ degrees, respectively for the bipolar components with PA
of 85 and 35 degrees, were derived. No additional bipolar lobes were required
to model the observed features of NGC 2440. A distance of $1.8 \pm 0.5$ kpc was
derived for the nebula using our velocity field for the toroidal structure.
These results are the first derived for NGC 2440 from modelling in a 3D
environment.


title:
Quantum Transitions of Nematic Phases in a Spin-$1$ Bilinear-Biquadratic
  Model and Their Implications for FeSe

abstract:
  Since its discovery, iron-based superconductivity has been known to develop
near an antiferromagnetic order, but this paradigm fails in the iron
chalcogenide FeSe, whose single-layer version holds the record for the highest
superconducting transition temperature in the iron-based superconductors. The
striking puzzle that FeSe displays nematic order (spontaneously broken lattice
rotational symmetry) while being non-magnetic, has led to several competing
proposals for its origin in terms of either the $3d$-electron's orbital degrees
of freedom or spin physics in the form of frustrated magnetism. Here we argue
that the phase diagram of FeSe under pressure could be qualitatively described
by a quantum spin model with highly frustrated interactions. We implement both
the site-factorized wave-function analysis and the large-scale density matrix
renormalization group (DMRG) in cylinders to study the spin-$1$
bilinear-biquadratic model on the square lattice, and identify quantum
transitions from the well-known $(\pi,0)$ antiferromagnetic state to an exotic
$(\pi,0)$ antiferroquadrupolar order, either directly or through a
$(\pi/2,\pi)$ antiferromagnetic state. These many phases, while distinct, are
all nematic. We also discuss our theoretical ground-state phase diagram for the
understanding of the experimental low-temperature phase diagram obtained by the
NMR [P. S. Wang {\it et al.}, Phys. Rev. Lett. 117, 237001 (2016)] and X-ray
scattering [K. Kothapalli {\it et al.}, Nature Communications 7, 12728 (2016)]
measurements in pressurized FeSe. Our results suggest that superconductivity in
a wide range of iron-based materials has a common origin in the
antiferromagnetic correlations of strongly correlated electrons.


title: The 25 Parsec Local White Dwarf Population

abstract:
  We have extended our detailed survey of the local white dwarf population from
20 pc to 25 pc, effectively doubling the sample volume, which now includes 232
stars. In the process new stars within 20 pc have been added, a more uniform
set of distance estimates as well as improved spectral and binary
classifications are available. The present 25 pc sample is estimated to be
about 68% complete (the corresponding 20 pc sample is now 86\% complete). The
space density of white dwarfs is unchanged at 4.8 \pm 0.5 x 10^{-3} pc^{-3}.
This new study includes a white dwarf mass distribution and luminosity function
based on the 232 stars in the 25 pc sample. We find a significant excess of
single stars over systems containing one or more companions (74\% vs 26\%).
This suggests mechanisms that result in the loss of companions during binary
system evolution. In addition this updated sample exhibits a pronounced
deficiency of nearby Sirius-Like systems. Eleven such systems were found within
the 20 pc volume vs, only one additional system found in the volume between 20
pc and 25 pc. An estimate of white dwarf birth rates during the last 8 Gyr is
derived from individual remnant cooling ages. A discussion of likely ways new
members of the local sample may be found is provided.


title:
Symmetrical-geometry constructions defining helicoidal biostructures.
  The case of alpha-helix

abstract:
  The chain of algebraic geometry constructions permits to transfer from the
minimal surface with zero instability index, and from the lattice over the ring
of cyclotomic integers to the tetra-block helix. The tetra-block is the
7-vertex joining of four tetrahedra sharing common faces; it is considered as a
building unit for structures approximated by the chains of regular tetrahedra.
The minimality condition of the 7 - vertex tetrablock as a building unit is the
consequence of its unique mapping by the Klein's quartic (which is
characterized by the minimal hyperbolic Schwartz triangle) into the minimal
finite projective geometry. The topological stability of this helix provided by
the pitch to radius ratio H/R of 2{\pi}/({\tau}+1) ({\tau} is the golden
section) and by the local rotation axis order of 40/11=40exp(-H/R). These
parameters determine the helix of C{\alpha} atoms inside the alpha - helix with
the accuracy of up to 2%. They explain also the bonding relationship i -- i+4
between the i-th amide group and the (i+4)-th carbonil group of the residues in
the peptide chain and the observed value of the average segment length of the
alpha-helix which is equal to 11 residues. The tetra-block helix with the N,
C{\alpha}, C', O, H atoms in the symmetrically selected positions, determines
the structure of the alpha - helix. The proposed approach can display
adequately the symmetry of the helicoidal biopolymers.


title:
On the dependence of QCD splitting functions on the choice of the
  evolution variable

abstract:
  We show that already at the NLO level the DGLAP evolution kernel Pqq starts
to depend on the choice of the evolution variable. We give an explicit example
of such a variable, namely the maximum of transverse momenta of emitted partons
and we identify a class of evolution variables that leave the NLO Pqq kernel
unchanged with respect to the known standard MS-bar results. The kernels are
calculated using a modified Curci-Furmanski-Petronzio method which is based on
a direct Feynman-graphs calculation.


title: Grid-like structure is optimal for path integration

abstract:
  Grid cells in medial entorhinal cortex are believed to play a key role in
path integration. However, the relation between path integration and the
grid-like arrangement of their firing field remains unclear. We provide
theoretical evidence that grid-like structure and path integration are closely
related. In one dimension, the grid-like structure provides the optimal
solution for path integration assuming that the noise correlation structure is
Gaussian. In two dimensions, assuming that the noise is Gaussian, rectangular
grid-like structure is the optimal solution provided that 1- both noise
correlation and receptive field structures of the neurons can be
multiplicatively decomposed into orthogonal components and 2- the eigenvalues
of the decomposed correlation matrices decrease faster than the square of the
frequency of the corresponding eigenvectors. We will also address the decoding
mechanism and show that the problem of decoding reduces to the problem of
extracting task relevant information in the presence of task irrelevant
information. Change-based Population Coding provides the optimal solution for
this problem.


title:
Fast launch speeds in radio flares, from a new determination of the
  intrinsic motions of SS 433's jet bolides

abstract:
  We present new high-resolution, multi-epoch, VLBA radio images of the
Galactic microquasar SS 433. We are able to observe plasma knots in the
milliarcsecond-scale jets more than 50 days after their launch. This
unprecedented baseline in time allows us to determine the bulk launch speed of
the radio-emitting plasma during a radio flare, using a new method which we
present here, and which is completely independent of optical spectroscopy. We
also apply this method to an earlier sequence of 39 short daily VLBA
observations, which cover a period in which SS 433 moved from quiescence into a
flare. In both datasets we find, for the first time at radio wavebands, clear
evidence that the launch speeds of the milliarcsecond-scale jets rise as high
as 0.32c during flaring episodes. By comparing these images of SS 433 with
photometric radio monitoring from the RATAN telescope, we explore further
properties of these radio flares.


title:
A Better Method for Volume Determination of Regularly and Irregularly
  Shaped Nanoparticles with Enhanced Accuracy

abstract:
  Nanoparticles (NPs) are widely used in diverse application areas, such as
medicine, engineering, and cosmetics. The size (or volume) of NPs is one of the
most important parameters for their successful application. It is relatively
straightforward to determine the volume of regular NPs such as spheres and
cubes from a one-dimensional or two-dimensional measurement. However, due to
the three-dimensional nature of NPs, it is challenging to determine the proper
physical size of many types of regularly and irregularly-shaped NPs (IS-NPs) at
high-throughput using a single tool. Here, we present a relatively simple
method that statistically determines a better volume estimate of many types of
NPs by combining measurements from their top-down projection areas and
peak-heights using two tools. The proposed method is significantly faster and
more economical than the electron tomography method. We demonstrate the
improved accuracy of the combined method over scanning electron microscopy
(SEM) and atomic force microscopy (AFM) by using both modeling and
measurements. This study also shows that SEM provides a more accurate estimate
of size than AFM for most IS-NP size measurements. The method provides a much
needed, proper high-throughput volumetric measurement method useful for many
applications.


title: Enhanced Momentum Feedback from Clustered Supernovae

abstract:
  Young stars typically form in star clusters, so the supernovae (SNe) they
produce are clustered in space and time. This clustering of SNe may alter the
momentum per SN deposited in the interstellar medium (ISM) by affecting the
local ISM density, which in turn affects the cooling rate. We study the effect
of multiple SNe using idealized 1D hydrodynamic simulations which explore a
large parameter space of the number of SNe, and the background gas density and
metallicity. The results are provided as a table and an analytic fitting
formula. We find that for clusters with up to ~100 SNe the asymptotic momentum
scales super-linearly with the number of SNe, resulting in a momentum per SN
that can be an order of magnitude larger than for a single SN, with a maximum
efficiency for clusters with 10-100 SNe. We argue that additional physical
processes not included in our simulations -- self-gravity, breakout from a
galactic disk, and galactic shear -- can slightly reduce the momentum
enhancement from clustering, but the average momentum per SN still remains a
factor of 4 larger than the isolated SN value when averaged over a realistic
cluster mass function for a star-forming galaxy. We conclude with a discussion
of the possible role of mixing between hot and cold gas, induced by
multi-dimensional instabilities or preexisting density variations, as a
limiting factor in the buildup of momentum by clustered SNe, and suggest future
numerical experiments to explore these effects.


title: BES with FEM: Building Energy Simulation using Finite Element Methods

abstract:
  An overall objective of energy efficiency in the built environment is to
improve building and systems performances in terms of durability, comfort and
economics. In order to predict, improve and meet a certain set of performance
requirements related to the indoor climate of buildings and the associated
energy demand, building energy simulation (BES) tools are indispensable. Due to
the rapid development of FEM software and the Multiphysics approaches, it
should possible to build and simulate full 3D models of buildings regarding the
energy demand. The paper presents a methodology for performing building energy
simulation with Comsol. The method was applied to an international test box
experiment. The results showed an almost perfect agreement between the used BES
model and Comsol. These preliminary results confirm the great opportunities to
use FEM related software for building energy performance simulation.


title: A principle of similarity for nonlinear vibration absorbers

abstract:
  This paper develops a principle of similarity for the design of a nonlinear
absorber, the nonlinear tuned vibration absorber (NLTVA), attached to a
nonlinear primary system. Specifically, for effective vibration mitigation, we
show that the NLTVA should feature a nonlinearity possessing the same
mathematical form as that of the primary system. A compact analytical formula
for the nonlinear coefficient of the absorber is then derived. The formula,
valid for any polynomial nonlinearity in the primary system, is found to depend
only on the mass ratio and on the nonlinear coefficient of the primary system.
When the primary system comprises several polynomial nonlinearities, we
demonstrate that the NLTVA obeys a principle of additivity, i.e., each
nonlinear coefficient can be calculated independently of the other nonlinear
coefficients using the proposed formula.


title: Scalable Algorithms for Tractable Schatten Quasi-Norm Minimization

abstract:
  The Schatten-p quasi-norm $(0<p<1)$ is usually used to replace the standard
nuclear norm in order to approximate the rank function more accurately.
However, existing Schatten-p quasi-norm minimization algorithms involve
singular value decomposition (SVD) or eigenvalue decomposition (EVD) in each
iteration, and thus may become very slow and impractical for large-scale
problems. In this paper, we first define two tractable Schatten quasi-norms,
i.e., the Frobenius/nuclear hybrid and bi-nuclear quasi-norms, and then prove
that they are in essence the Schatten-2/3 and 1/2 quasi-norms, respectively,
which lead to the design of very efficient algorithms that only need to update
two much smaller factor matrices. We also design two efficient proximal
alternating linearized minimization algorithms for solving representative
matrix completion problems. Finally, we provide the global convergence and
performance guarantees for our algorithms, which have better convergence
properties than existing algorithms. Experimental results on synthetic and
real-world data show that our algorithms are more accurate than the
state-of-the-art methods, and are orders of magnitude faster.


title:
Unification of the Fundamental Plane and Super-Massive Black Holes
  Masses

abstract:
  According to the Virial Theorem, all gravitational systems in equilibrium sit
on a plane in the 3D parameter space defined by their mass, size and second
moment of the velocity tensor. While these quantities cannot be directly
observed, there are suitable proxies: the luminosity Lk, half-light radius Re
and dispersion sigma_e. These proxies indeed lie on a very tight Fundamental
Plane (FP). How do the black holes in the centers of galaxies relate to the FP?
Their masses are known to exhibit no strong correlation with total galaxy mass,
but they do correlate weakly with bulge mass (when present), and extremely well
with the velocity dispersion through the Mbh = sigma_e^5.4 relation. These
facts together imply that a tight plane must also exist defined by black hole
mass, total galaxy mass and size. Here I show that this is indeed the case
using a heterogeneous set of 230 black holes. The sample includes BHs from zero
to 10 billion solar masses and host galaxies ranging from low surface
brightness dwarfs, through bulge-less disks, to brightest cluster galaxies. The
resulting BH-size-luminosity Mbh=(Lk/Re)^3.8 has the same amount of scatter as
the M-sigma relation and is aligned with the galaxy FP, such that it is just a
re-projection of sigma. The inferred BH-size-mass relation is
Mbh=(M_star/Re)^2.9. These relationships are universal and extend to galaxies
without bulges. This implies that the black hole is primarily correlated with
its global velocity dispersion and not with the properties of the bulge. I show
that the classical bulge--mass relation is a projection of the M-sigma
relation. When the velocity dispersion cannot be measured (at high-z or low
dispersions), the BH-size-mass relation should be used as a proxy for black
hole mass in favor of just galaxy or bulge mass.


title:
A self-consistent model for the evolution of the gas produced in the
  debris disc of $\beta$ Pictoris

abstract:
  This paper presents a self-consistent model for the evolution of gas produced
in the debris disc of $\beta$ Pictoris. Our model proposes that atomic carbon
and oxygen are created from the photodissociation of CO, which is itself
released from volatile-rich bodies in the debris disc due to grain-grain
collisions or photodesorption. While the CO lasts less than one orbit, the
atomic gas evolves by viscous spreading resulting in an accretion disc inside
the parent belt and a decretion disc outside. The temperature, ionisation
fraction and population levels of carbon and oxygen are followed with the
photodissociation region model Cloudy, which is coupled to a dynamical viscous
$\alpha$ model. We present new gas observations of $\beta$ Pic, of C I observed
with APEX and O I observed with Herschel, and show that these along with
published C II and CO observations can all be explained with this new model.
Our model requires a viscosity $\alpha$ > 0.1, similar to that found in
sufficiently ionised discs of other astronomical objects; we propose that the
magnetorotational instability is at play in this highly ionised and dilute
medium. This new model can be tested from its predictions for high resolution
ALMA observations of C I. We also constrain the water content of the
planetesimals in $\beta$ Pic. The scenario proposed here might be at play in
all debris discs and this model could be used more generally on all discs with
C, O or CO detections.


title: Weak annihilation cusp inside the dark matter spike about a black hole

abstract:
  We reinvestigate the effect of annihilations on the distribution of
collisionless dark matter (DM) in a spherical density spike around a massive
black hole. We first construct a very simple, pedagogic, analytic model for an
isotropic phase space distribution function that accounts for annihilation and
reproduces the "weak cusp" found by Vasiliev for DM deep within the spike and
away from its boundaries. The DM density in the cusp varies as $r^{-1/2}$ for
$s$-wave annihilation, where $r$ is the distance from the central black hole,
and is not a flat "plateau" profile. We then extend this model by incorporating
a loss cone that accounts for the capture of DM particles by the hole. The loss
cone is implemented by a boundary condition that removes capture orbits,
resulting in an anisotropic distribution function. Finally, we evolve an
initial spike distribution function by integrating the Boltzmann equation to
show how the weak cusp grows and its density decreases with time. We treat two
cases, one for $s$-wave and the other for $p$-wave DM annihilation, adopting
parameters characteristic of the Milky Way nuclear core and typical WIMP models
for DM. The cusp density profile for $p$-wave annihilation is weaker, varying
like $\sim r^{-0.34}$, but is still not a flat plateau.


title:
Quasiclassical theory for the superconducting proximity effect in Dirac
  materials

abstract:
  We derive the quasiclassical non-equilibrium Eilenberger and Usadel equations
to first order in quantities small compared to the Fermi energy, valid for
Dirac edge and surface electrons with spin-momentum locking, as relevant for
topological insulators. We discuss in detail several of the key technical
points and assumptions of the derivation, and provide a Riccati-parametrization
of the equations. Solving first the equilibrium equations for S/N and S/F
bilayers and Josephson junctions, we study the superconducting proximity effect
in Dirac materials. Similarly to related works, we find that the effect of an
exchange field depends strongly on the direction of the field. Only components
normal to the transport direction lead to attenuation of the Cooper pair
wavefunction inside the F. Fields parallel to the transport direction lead to
phase-shifts in the dependence on the superconducting phase difference for both
the charge current and density of states in an S/F/S-junction. Moreover, we
compute the differential conductance in S/N and S/F bilayers with an applied
voltage bias, and determine the dependence on the length of the N and F regions
and the exchange field.


title:
Consistent Higher Derivative Gravitational theories with stable de
  Sitter and Anti-de Sitter Backgrounds

abstract:
  In this paper we provide the criteria for any generally covariant, parity
preserving, and torsion free theory of gravity to possess a stable de Sitter
(dS) or anti-de Sitter (AdS) background. By stability we mean the absence of
tachyonic or ghost-like states in the perturbative spectrum that can lead to
classical instabilities and violation of quantum unitarity. While we find that
the usual suspects, the F(R) and F(G) theories, can indeed possess consistent
(A)dS backgrounds, G being the Gauss-Bonnet term, another interesting class of
theories, string-inspired infinite derivative gravity, can also be consistent
around such curved vacuum solutions. Our study should not only be relevant for
quantum gravity and early universe cosmology involving ultraviolet physics, but
also for modifications of gravity in the infra-red sector vying to replace dark
energy .


title:
A Multi-Wavelength Photometric Census of AGN and Star Formation Activity
  in the Brightest Cluster Galaxies of X-ray Selected Clusters

abstract:
  Despite their reputation as being "red and dead", the unique environment
inhabited by Brightest Cluster Galaxies (BCGs) can often lead to a
self-regulated feedback cycle between radiatively cooling intracluster gas and
star formation and AGN activity in the BCG. However the prevalence of "active"
BCGs, and details of the feedback involved, are still uncertain. We have
performed an optical, UV and Mid-IR photometric analysis of the BCGs in 981
clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using
Pan-STARRS PS1 3pi, GALEX and WISE survey data we look for BCGs with
photometric colours which deviate from that of the bulk population of passive
BCGs - indicative of AGN and/or star formation activity within the BCG. We find
that whilst the majority of BCGs are consistent with being passive, at least
14% of our BCGs show a significant colour offset from passivity in at least one
colour index. And, where available, supplementary spectroscopy reveals the
majority of these particular BCGs show strong optical emission lines. On
comparing BCG "activity" with the X-ray luminosity of the host cluster, we find
that BCGs showing a colour offset are preferentially found in the more X-ray
luminous clusters, indicative of the connection between BCG "activity" and the
intracluster medium.


title:
Superconductivity near a quantum-critical point: The special role of the
  first Matsubara frequency

abstract:
  Near a quantum-critical point in a metal strong fermion-fermion interaction
mediated by a soft collective boson gives rise to incoherent, non-Fermi liquid
behavior. It also often gives rise to superconductivity which masks the
non-Fermi liquid behavior. We analyze the interplay between superconductivity
and fermionic incoherence for a set of quantum-critical models with effective
dynamical interaction between low-energy fermions. We argue that
superconductivity always develops above a quantum-critical point, no matter how
strong the fermionic self-energy is. We argue that superconductivity should not
be viewed as a pairing of incoherent fermions, as previously thought. Rather,
$T_c$ is non-zero due to the fact that the self-energy is suppressed at the two
lowest fermionic Matsubara frequencies $\omega_m = \pm \pi T$. We obtain the
analytic formula for $T_c$ which reproduces well numerical results for the
electron-phonon model at vanishing Debye frequency.


title:
Spatially Offset Active Galactic Nuclei I: Selection and Spectroscopic
  Properties

abstract:
  We present a sample of 18 optically-selected and X-ray detected spatially
offset active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS).
In 9 systems, the X-ray AGN is spatially offset from the galactic stellar core
that is located within the 3'' diameter SDSS spectroscopic fiber. In 11
systems, the X-ray AGN is spatially offset from a stellar core that is located
outside the fiber, with an overlap of 2. To build the sample, we cross-matched
Type II AGN selected from the SDSS galaxy catalogue with archival Chandra
imaging and employed our custom astrometric and registration procedure. The
projected angular (physical) offsets span a range of 0."6 (0.8 kpc) to 17."4
(19.4 kpc), with a median value of 2."7 (4.6 kpc). The offset nature of an AGN
is an unambiguous signature of a galaxy merger, and these systems can be used
to study the properties of AGN in galaxy mergers without the biases introduced
by morphological merger selection techniques. In this paper (Paper I), we use
our sample to assess the kinematics of AGN photoionized gas in galaxy mergers.
We find that spectroscopic offset AGN selection may be up to 89% incomplete due
to small projected velocity offsets. We also find that the magnitude of the
velocity offsets are generally larger than expected if our spatial selection
introduces a bias toward face-on orbits, suggesting the presence of complex
kinematics in the emission line gas of AGN in galaxy mergers.


title: Warped $AdS_6\times S^2$ in Type IIB supergravity I: Local solutions

abstract:
  We investigate the existence of solutions with 16 residual supersymmetries to
Type IIB supergravity on a space-time of the form $AdS_6 \times S^2$ warped
over a two-dimensional Riemann surface $\Sigma$. The $SO(2,5) \times SO(3)$
isometry extends to invariance under the exceptional Lie superalgebra $F(4)$.
In the present paper, we construct the general Ansatz compatible with these
symmetries, derive the corresponding reduced BPS equations, and obtain their
complete local solution in terms of two locally holomorphic functions ${\cal
A}_\pm$ on $\Sigma$, subject to certain positivity and regularity conditions.
Globally, $({\cal A}_+, {\cal A}_-)$ are allowed to be multiple-valued on
$\Sigma$ and be holomorphic sections of a holomorphic bundle over $\Sigma$ with
structure group contained in $SU(1,1) \times { C}$. Globally regular solutions
are expected to provide the near-horizon geometry of $(p,q)$ 5-brane and
7-brane webs which are holographic duals to five-dimensional conformal field
theories. A preliminary analysis of the positivity and regularity conditions
will be presented here, leaving the construction of globally regular solutions
to a subsequent paper.


title:
Applications for edge detection techniques using Chandra and XMM-Newton
  data: galaxy clusters and beyond

abstract:
  The unrivalled spatial resolution of the Chandra X-ray observatory has
allowed many breakthroughs to be made in high energy astrophysics. Here we
explore applications of Gaussian Gradient Magnitude (GGM) filtering to X-ray
data, which dramatically improves the clarity of surface brightness edges in
X-ray observations, and maps gradients in X-ray surface brightness over a range
of spatial scales. In galaxy clusters, we find that this method is able to
reveal remarkable substructure behind the cold fronts in Abell 2142 and Abell
496, possibly the result of Kelvin Helmholtz instabilities. In Abell 2319 and
Abell 3667, we demonstrate that the GGM filter can provide a straightforward
way of mapping variations in the widths and jump ratios along the lengths of
cold fronts. We present results from our ongoing programme of analysing the
Chandra and XMM-Newton archives with the GGM filter. In the Perseus cluster we
identify a previously unseen edge around 850 kpc from the core to the east,
lying outside a known large scale cold front, which is possibly a bow shock. In
MKW 3s we find an unusual 'V' shape surface brightness enhancement starting at
the cluster core, which may be linked to the AGN jet. In the Crab nebula a new,
moving feature in the outer part of the torus is identified which moves across
the plane of the sky at a speed of ~0.1c, and lies much further from the
central pulsar than the previous motions seen by Chandra.


title: Cosmological signatures of time-asymmetric gravity

abstract:
  We develop the model proposed by Cort\^es, Gomes & Smolin, to predict
cosmological signatures of time-asymmetric extensions of general relativity
they proposed recently. Within this class of models the equation of motion of
chiral fermions is modified by a torsion term. This term leads to a dispersion
law for neutrinos that associates a new time-varying energy with each particle.
We find a new neutrino contribution to the Friedmann equation resulting from
the torsion term in the Ashtekar connection. In this note we explore the
phenomenology of this term and observational consequences for cosmological
evolution. We show that constraints on the critical energy density will
ordinarily render this term unobservably small, a maximum of order $10^{-25}$
of the neutrino energy density today. However, if the time-asymmetric dark
energy is tuned to cancel the cosmological constant, the torsion effect may be
a dark matter candidate.


title:
Noise Response Data Reveal Novel Controllability Gramian for Nonlinear
  Network Dynamics

abstract:
  Control of nonlinear large-scale dynamical networks, e.g., collective
behavior of agents interacting via a scale-free connection topology, is a
central problem in many scientific and engineering fields. For the linear
version of this problem, the so-called controllability Gramian has played an
important role to quantify how effectively the dynamical states are reachable
by a suitable driving input. In this paper, we first extend the notion of the
controllability Gramian to nonlinear dynamics in terms of the Gibbs
distribution. Next, we show that, when the networks are open to environmental
noise, the newly defined Gramian is equal to the covariance matrix associated
with randomly excited, but uncontrolled, dynamical state trajectories. This
fact theoretically justifies a simple Monte Carlo simulation that can extract
effectively controllable subdynamics in nonlinear complex networks. In
addition, the result provides a novel insight into the relationship between
controllability and statistical mechanics.


title: Sterile neutrino portal to Dark Matter I: The $U(1)_{B-L}$ case

abstract:
  In this paper we explore the possibility that the sterile neutrino and Dark
Matter sectors in the Universe have a common origin. We study the consequences
of this assumption in the simple case of coupling the dark sector to the
Standard Model via a global $U(1)_{B-L}$, broken down spontaneously by a dark
scalar. This dark scalar provides masses to the dark fermions and communicates
with the Higgs via a Higgs portal coupling. We find an interesting interplay
between Dark Matter annihilation to dark scalars - the CP-even that mixes with
the Higgs and the CP-odd which becomes a Goldstone boson, the Majoron - and
heavy neutrinos, as well as collider probes via the coupling to the Higgs.
Moreover, Dark Matter annihilation into sterile neutrinos and its subsequent
decay to gauge bosons and quarks, charged leptons or neutrinos lead to indirect
detection signatures which are close to current bounds on the gamma ray flux
from the galactic center and dwarf galaxies.


title:
The Relation Between [OIII]/H$\beta$ and Specific Star Formation Rate in
  Galaxies at $z \sim 2$

abstract:
  Recent surveys have identified a seemingly ubiquitous population of galaxies
with elevated [OIII]/H$\beta$ emission line ratios at $z > 1$, though the
nature of this phenomenon continues to be debated. The [OIII]/H$\beta$ line
ratio is of interest because it is a main component of the standard diagnostic
tools used to differentiate between active galactic nuclei (AGN) and
star-forming galaxies, as well as the gas-phase metallicity indicators $O_{23}$
and $R_{23}$. Here, we investigate the primary driver of increased
[OIII]/H$\beta$ ratios by median-stacking rest-frame optical spectra for a
sample of star-forming galaxies in the 3D-HST survey in the redshift range
$z\sim1.4-2.2$. Using $N = 4220$ star-forming galaxies, we stack the data in
bins of mass and specific star formation rates (sSFR) respectively. After
accounting for stellar Balmer absorption, we measure
[OIII]$\lambda5007$\AA/H$\beta$ down to $\mathrm{M} \sim 10^{9.2} \
\mathrm{M_\odot}$ and sSFR $\sim 10^{-9.6} \ \mathrm{yr}^{-1}$, more than an
order of magnitude lower than previous work at similar redshifts. We find an
offset of $0.59\pm0.05$ dex between the median ratios at $z\sim2$ and $z\sim0$
at fixed stellar mass, in agreement with existing studies. However, with
respect to sSFR, the $z \sim 2$ stacks all lie within 1$\sigma$ of the median
SDSS ratios, with an average offset of only $-0.06\pm 0.05$. We find that the
excitation properties of galaxies are tightly correlated with their sSFR at
both $z\sim2$ and $z\sim0$, with a relation that appears to be roughly constant
over the last 10 Gyr of cosmic time.


title:
Bimodal entanglement entropy distribution in the many-body localization
  transition

abstract:
  We introduce the cut averaged entanglement entropy in disordered periodic
spin chains and prove it to be a concave function of subsystem size for
individual eigenstates. This allows us to identify the entanglement scaling as
a function of subsystem size for individual states in inhomogeneous systems.
Using this quantity, we probe the critical region between the many-body
localized (MBL) and ergodic phases in finite systems.
  In the middle of the spectrum, we show evidence for bimodality of the
entanglement distribution in the MBL critical region, finding both volume law
and area law eigenstates over disorder realizations as well as within
\emph{single disorder realizations}. The disorder averaged entanglement entropy
in this region then scales as a volume law with a coefficient below its thermal
value. We discover in the critical region, as we approach the thermodynamic
limit, that the cut averaged entanglement entropy density falls on a
one-parameter family of curves. Finally, we also show that without averaging
over cuts the slope of the entanglement entropy \vs subsystem size can be
negative at intermediate and strong disorder, caused by rare localized regions
in the system.


title:
Minimizing Regret on Reflexive Banach Spaces and Learning Nash
  Equilibria in Continuous Zero-Sum Games

abstract:
  We study a general version of the adversarial online learning problem. We are
given a decision set $\mathcal{X}$ in a reflexive Banach space $X$ and a
sequence of reward vectors in the dual space of $X$. At each iteration, we
choose an action from $\mathcal{X}$, based on the observed sequence of previous
rewards. Our goal is to minimize regret, defined as the gap between the
realized reward and the reward of the best fixed action in hindsight. Using
results from infinite dimensional convex analysis, we generalize the method of
Dual Averaging (or Follow the Regularized Leader) to our setting and obtain
general upper bounds on the worst-case regret that subsume a wide range of
results from the literature. Under the assumption of uniformly continuous
rewards, we obtain explicit anytime regret bounds in a setting where the
decision set is the set of probability distributions on a compact metric space
$S$ whose Radon-Nikodym derivatives are elements of $L^p(S)$ for some $p > 1$.
Importantly, we make no convexity assumptions on either the set $S$ or the
reward functions. We also prove a general lower bound on the worst-case regret
for any online algorithm. We then apply these results to the problem of
learning in repeated continuous two-player zero-sum games, in which players'
strategy sets are compact metric spaces. In doing so, we first prove that if
both players play a Hannan-consistent strategy, then with probability 1 the
empirical distributions of play weakly converge to the set of Nash equilibria
of the game. We then show that, under mild assumptions, Dual Averaging on the
(infinite-dimensional) space of probability distributions indeed achieves
Hannan-consistency. Finally, we illustrate our results through numerical
examples.


title:
Directly comparing GW150914 with numerical solutions of Einstein's
  equations for binary black hole coalescence

abstract:
  We compare GW150914 directly to simulations of coalescing binary black holes
in full general relativity, accounting for all the spin-weighted quadrupolar
modes, and separately accounting for all the quadrupolar and octopolar modes.
Consistent with the posterior distributions reported in LVC_PE[1] (at 90%
confidence), we find the data are compatible with a wide range of nonprecessing
and precessing simulations. Followup simulations performed using
previously-estimated binary parameters most resemble the data. Comparisons
including only the quadrupolar modes constrain the total redshifted mass Mz \in
[64 - 82M_\odot], mass ratio q = m2/m1 \in [0.6,1], and effective aligned spin
\chi_eff \in [-0.3, 0.2], where \chi_{eff} = (S1/m1 + S2/m2) \cdot\hat{L} /M.
Including both quadrupolar and octopolar modes, we find the mass ratio is even
more tightly constrained. Simulations with extreme mass ratios and effective
spins are highly inconsistent with the data, at any mass. Several nonprecessing
and precessing simulations with similar mass ratio and \chi_{eff} are
consistent with the data. Though correlated, the components' spins (both in
magnitude and directions) are not significantly constrained by the data. For
nonprecessing binaries, interpolating between simulations, we reconstruct a
posterior distribution consistent with previous results. The final black hole's
redshifted mass is consistent with Mf,z between 64.0 - 73.5M_\odot and the
final black hole's dimensionless spin parameter is consistent with af = 0.62 -
0.73. As our approach invokes no intermediate approximations to general
relativity and can strongly reject binaries whose radiation is inconsistent
with the data, our analysis provides a valuable complement to LVC_PE[1].


title:
NH$_3$(3,3) and CH$_3$OH near Supernova Remnants: GBT and VLA
  Observations

abstract:
  We report on Green Bank Telescope 23.87 GHz NH$_3$(3,3), emission
observations in five supernova remnants interacting with molecular clouds
(G1.4$-$0.1, IC443, W44, W51C, and G5.7$-$0.0). The observations show a clumpy
gas density distribution, and in most cases the narrow line widths of
$\sim3-4$\,km\,s$^{-1}$ are suggestive of maser emission. Very Large Array
observations reveal 36~GHz and/or 44~GHz CH$_3$OH, maser emission in a majority
(72\%) of the NH$_3$, peak positions towards three of these SNRs. This good
positional correlation is in agreement with the high densities required for the
excitation of each line. Through these observations we have shown that
CH$_3$OH, and NH$_3$, maser emission can be used as indicators of high density
clumps of gas shocked by supernova remnants, and provide density estimates
thereof. Modeling of the optical depth of the NH$_3$(3,3) emission is compared
to that of CH$_3$OH, constraining the densities of the clumps to a typical
density of the order of $10^5$~cm$^{-3}$ for cospatial masers. Regions of gas
with this density are found to exist in the post-shocked gas quite close to the
SNR shock front, and may be associated with sites where cosmic rays produce
gamma-ray emission via neutral pion decay.


title: Transiting exoplanet candidates from K2 Campaigns 5 and 6

abstract:
  We introduce a new transit search and vetting pipeline for observations from
the K2 mission, and present the candidate transiting planets identified by this
pipeline out of the targets in Campaigns 5 and 6. Our pipeline uses the
Gaussian Process-based K2SC code to correct for the K2 pointing systematics and
simultaneously model stellar variability. The systematics-corrected,
variability-detrended light curves are searched for transits with the Box Least
Squares method, and a period-dependent detection threshold is used to generate
a preliminary candidate list. Two or three individuals vet each candidate
manually to produce the final candidate list, using a set of
automatically-generated transit fits and assorted diagnostic tests to inform
the vetting. We detect 147 single-planet system candidates and 5 multi-planet
systems, independently recovering the previously-published hot~Jupiters EPIC
212110888b, WASP-55b (EPIC 212300977b) and Qatar-2b (EPIC 212756297b). We also
report the outcome of reconnaissance spectroscopy carried out for all
candidates with Kepler magnitude Kp < 13, identifying 12 targets as likely
false positives. We compare our results to those of other K2 transit search
pipelines, noting that ours performs particularly well for variable and/or
active stars, but that the results are very similar overall. All the light
curves and code used in the transit search and vetting process are publicly
available, as are the follow-up spectra.


title:
Gaussian process emulators for computer experiments with inequality
  constraints

abstract:
  Physical phenomena are observed in many fields (sciences and engineering) and
are often studied by time-consuming computer codes. These codes are analyzed
with statistical models, often called emulators. In many situations, the
physical system (computer model output) may be known to satisfy inequality
constraints with respect to some or all input variables. Our aim is to build a
model capable of incorporating both data interpolation and inequality
constraints into a Gaussian process emulator. By using a functional
decomposition, we propose to approximate the original Gaussian process by a
finite-dimensional Gaussian process such that all conditional simulations
satisfy the inequality constraints in the whole domain. The mean, mode (maximum
a posteriori) and prediction intervals (uncertainty quantification) of the
conditional Gaussian process are calculated. To investigate the performance of
the proposed model, some conditional simulations with inequality constraints
such as boundary, monotonicity or convexity conditions are given. 1.
Introduction. In the engineering activity, runs of a computer code can be
expensive and time-consuming. One solution is to use a statistical surrogate
for conditioning computer model outputs at some input locations (design
points). Gaussian process (GP) emulator is one of the most popular choices
[23]. The reason comes from the property of the GP that uncertainty
quantification can be calculated. Furthermore, it has several nice properties.
For example, the conditional GP at observation data (linear equality
constraints) is still a GP [5]. Additionally, some inequality constraints (such
as monotonicity and convexity) of output computer responses are related to
partial derivatives. In such cases, the partial derivatives of the GP are also
GPs. Incorporating an infinite number of linear inequality constraints into a
GP emulator, the problem becomes more difficult. The reason is that the
resulting conditional process is not a GP. In the literature of interpolation
with inequality constraints, we find two types of meth-ods. The first one is
deterministic and based on splines, which have the advantage that the
inequality constraints are satisfied in the whole input domain (see e.g. [16],
[24] and [25]). The second one is based on the simulation of the conditional GP
by using the subdivision of the input set (see e.g. [1], [6] and [11]). In that
case, the inequality constraints are satisfied in a finite number of input
locations. Notice that the advantage of such method is that un-certainty
quantification can be calculated. In previous work, some methodologies have
been based on the knowledge of the derivatives of the GP at some input
locations ([11], [21] and [26]). For monotonicity constraints with noisy data,
a Bayesian approach was developed in [21]. In [11] the problem is to build a GP
emulator by using the prior monotonicity


title: The Vaserstein symbol on real smooth affine threefolds

abstract:
  We give a necessary and sufficient topological condition for the Vaserstein
symbol to be injective on smooth affine real threefolds. More precisely, we
show that the Vaserstein symbol is a bijection for such a threefold X if and
only if the set of compact connected components of the real points of X
(endowed with the Euclidean topology) is empty.


title: Holographic Space-time, Newton's Law and the Dynamics of Black Holes

abstract:
  We revisit the construction of models of quantum gravity in d dimensional
Minkowski space in terms of random tensor models, and correct some mistakes in
our previous treatment of the subject. We find a large class of models in which
the large impact parameter scattering scales with energy and impact parameter
like Newton`s law. These same models also have emergent energy, momentum and
angular conservation laws, despite being based on time dependent Hamiltonians.
Many of the scattering amplitudes have a Feynman diagram like structure: local
interaction vertices connected by propagation of free particles (really
Sterman-Weinberg jets of particles). However, there are also amplitudes where
jets collide to form large meta-stable objects, with all the scaling properties
of black holes: energy, entropy and temperature, as well as the characteristic
time scale for the decay of perturbations. We generalize the conjecture of
Sekino and Susskind, to claim that all of these models are fast scramblers. The
rationale for this claim is that the interactions are invariant under fuzzy
subgroups of the group of volume preserving diffeomorphisms, so that they are
highly non-local on the holographic screen. We review how this formalism
resolves the Firewall Paradox.


title:
Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of
  SDSS J1224+5555

abstract:
  There is mounting evidence that supermassive black holes form and grow in
bulgeless galaxies. However, a robust determination of the fraction of AGNs in
bulgeless galaxies, an important constraint to models of supermassive black
hole seed formation and merger-free models of AGN fueling, is unknown, since
optical studies have been shown to be incomplete for low mass AGNs. In a recent
study using the Wide-field Infrared Survey Explorer, we discovered hundreds of
bulgeless galaxies that display mid-infrared signatures of extremely hot dust
suggestive of powerful accreting massive black holes, despite having no
signatures of black hole activity at optical wavelengths. Here we report X-ray
follow-up observations of J122434.66+555522.3, a nearby (z=0.052) isolated
bulgeless galaxy that contains an unresolved X-ray source detected at the 3
sigma level by XMM-Newton with an observed luminosity uncorrected for intrinsic
absorption of L{2-10~keV}=1.1+/-0.4 10^40 ergs/s. Ground-based near-infrared
spectroscopy with the Large Binocular Telescope together with multiwavelength
observations from ultraviolet to millimeter wavelengths together suggest that
J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of ~NH
>10^24 cm^-2. The hard X-ray luminosity of the putative AGN corrected for
absorption is L{2-10~keV}~3x10^42 ergs/s, which, depending on the bolometric
correction factor, corresponds to a bolometric luminosity of the AGN of
6x10^43ergs/s - 3x10^44 erg/s, and a lower mass limit for the black hole of
MBH~2x10^6 Msun, based on the Eddington limit.


title:
End-to-end LSTM-based dialog control optimized with supervised and
  reinforcement learning

abstract:
  This paper presents a model for end-to-end learning of task-oriented dialog
systems. The main component of the model is a recurrent neural network (an
LSTM), which maps from raw dialog history directly to a distribution over
system actions. The LSTM automatically infers a representation of dialog
history, which relieves the system developer of much of the manual feature
engineering of dialog state. In addition, the developer can provide software
that expresses business rules and provides access to programmatic APIs,
enabling the LSTM to take actions in the real world on behalf of the user. The
LSTM can be optimized using supervised learning (SL), where a domain expert
provides example dialogs which the LSTM should imitate; or using reinforcement
learning (RL), where the system improves by interacting directly with end
users. Experiments show that SL and RL are complementary: SL alone can derive a
reasonable initial policy from a small number of training dialogs; and starting
RL optimization with a policy trained with SL substantially accelerates the
learning rate of RL.


title:
A data driven network approach to rank countries production diversity
  and food specialization

abstract:
  The easy access to large data sets has allowed for leveraging methodology in
network physics and complexity science to disentangle patterns and processes
directly from the data, leading to key insights in the behavior of systems.
Here we use to country specific food production data to study binary and
weighted topological properties of the bipartite country-food production
matrix. This country-food production matrix can be: 1) transformed into overlap
matrices which embed information regarding shared production of products among
countries, and or shared countries for individual products, 2) identify subsets
of countries which produce similar commodities or subsets of commodities shared
by a given country allowing for visualization of correlations in large
networks, and 3) used to rank country's fitness (the ability to produce a
diverse array of products weighted on the type of food commodities) and food
specialization (quantified on the number of countries producing that food
product weighted on their fitness). Our results show that, on average,
countries with high fitness producing highly specialized food commodities also
produce low specialization goods, while nations with low fitness producing a
small basket of diverse food products, typically produce low specialized food
commodities.


title: Fermi-LAT kills dark matter interpretations of AMS-02 data. Or not?

abstract:
  A number of papers attempt to explain the positron anomaly in cosmic rays,
observed by PAMELA and AMS-02, in terms of dark matter (DM) decays or
annihilations. However, the recent progress in cosmic gamma-ray studies
challenges these attempts. Indeed, as we show, any rational DM model explaining
the positron anomaly abundantly produces final state radiation and Inverse
Compton gamma rays, which inevitably leads to a contradiction with Fermi-LAT
isotropic diffuse gamma-ray background measurements. Furthermore, the Fermi-LAT
observation of Milky Way dwarf satellites, supposed to be rich in DM, revealed
no significant signal in gamma rays. We propose a generic approach in which the
major contribution to cosmic rays comes from the dark matter disc and prove
that the tension between the DM origin of the positron anomaly and the cosmic
gamma-ray observations can be relieved. We consider both a simple model, in
which DM decay/annihilate into charged leptons, and a model-independent minimal
case of particle production, and we estimate the optimal thickness of DM disk.
Possible mechanisms of formation and its properties are briefly discussed.


title: Bypassing damaged nervous tissue

abstract:
  It is shown the principal possibility of bypassing damaged demyelinated
portions of the nervous tissue, thereby restoring its normal function for the
passage of action potentials.


title:
Nuclear energy gradients for internally contracted complete active space
  second-order perturbation theory: Multistate extensions

abstract:
  We report the development of the theory and computer program for analytical
nuclear energy gradients for (extended) multi-state complete active space
perturbation theory (CASPT2) with full internal contraction. The vertical
shifts are also considered in this work. This is an extension of the fully
internally contracted CASPT2 nuclear gradient program, recently developed for a
state-specific variant by us [MacLeod and Shiozaki, J. Chem. Phys. 142, 051103
(2015)]; in this extension, the so-called {\lambda} equation is solved to
account for the variation of the multi-state CASPT2 energies with respect to
the change in the amplitudes obtained in the preceding state-specific CASPT2
calculations, and the Z-vector equations are modified accordingly. The program
is parallelized using the MPI3 remote memory access protocol that allows us to
perform efficient one-sided communication. The optimized geometries of the
ground and excited states of a copper corrole and benzophenone are presented as
numerical examples. The code is publicly available under the GNU General Public
License.


title: Prefix frequency of lost positions

abstract:
  The concept of "lost positions" is a recently introduced tool for counting
the number of runs in words. We investigate the frequency of lost positions in
prefixes of words. This leads to an algorithm that allows to show, using an
extensive computer search, that the asymptotic density of runs in binary words
is less than $183/193\approx 0.9482$.


title: Predicting with Distributions

abstract:
  We consider a new learning model in which a joint distribution over vector
pairs $(x,y)$ is determined by an unknown function $c(x)$ that maps input
vectors $x$ not to individual outputs, but to entire {\em distributions\/} over
output vectors $y$. Our main results take the form of rather general reductions
from our model to algorithms for PAC learning the function class and the
distribution class separately, and show that virtually every such combination
yields an efficient algorithm in our model. Our methods include a randomized
reduction to classification noise and an application of Le Cam's method to
obtain robust learning algorithms.


title: Study of \chi_{bJ}(1P) Properties in the Radiative \Upsilon(2S) Decays

abstract:
  We report a study of radiative decays of \chi_{bJ}(1P)(J=0,1,2) mesons into
74 hadronic final states comprising charged and neutral pions, kaons, protons;
out of these, 41 modes are observed with at least 5 standard deviation
significance. Our measurements not only improve the previous measurements by
the CLEO Collaboration but also lead to first observations in many new modes.
The large sample allows us to probe the total decay width of the \chi_{b0}(1P).
In the absence of a statistically significant result, a 90% confidence-level
upper limit is set on the width at \Gamma_{total}< 2.4 MeV. Our results are
based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at
the \Upsilon(2S) resonance, corresponding to (157.8\pm3.6)\times10^6
\Upsilon(2S) decays.


title: Lattice study of large $N_c$ QCD

abstract:
  We present a lattice simulation study of large $N_c$ regularities of meson
and baryon spectroscopy in $SU(N_c)$ gauge theory with two flavors of dynamical
fundamental representation fermions. Systems investigated include $N_c=2$, 3,
4, and 5, over a range of fermion masses parametrized by a squared pseudoscalar
to vector meson mass ratio between about 0.2 to 0.7. Good agreement with large
$N_c$ scaling is observed in the static potential, in meson masses and decay
constants, and in baryon spectroscopy. This is an update of the published
version of the paper (Phys. Rev. D94 (2016) 034506).


title: Simple D-module components of local cohomology modules

abstract:
  For a projective variety V in P^n over a field of characteristic zero, with
homogeneous ideal I in A = k[x0,x1,...,xn], we consider the local cohomology
modules H^i_I(A). These have a structure of holonomic D-module over A, and we
investigate their filtration by simple D-modules. In case V is nonsingular, we
can describe completely these simple components in terms of the Betti numbers
of V.


title:
Generation of energy-entangled W states via parametric fluorescence in
  integrated devices

abstract:
  Tripartite entangled states, such as GHZ and W states, are typically
generated by manipulating two pairs of polarization-entangled photons in bulk
optics. Here we propose a scheme to generate W states that are entangled in the
energy degree of freedom in an integrated optical circuit. Our approach employs
photon pairs generated by spontaneous four-wave mixing (SFWM) in a micro- ring
resonator. We also present a feasible procedure for demonstrating the
generation of such a state, and we compare polarization-entangled and
energy-entangled schemes for the preparation of W states.


title: Dependency Parsing as Head Selection

abstract:
  Conventional graph-based dependency parsers guarantee a tree structure both
during training and inference. Instead, we formalize dependency parsing as the
problem of independently selecting the head of each word in a sentence. Our
model which we call \textsc{DeNSe} (as shorthand for {\bf De}pendency {\bf
N}eural {\bf Se}lection) produces a distribution over possible heads for each
word using features obtained from a bidirectional recurrent neural network.
Without enforcing structural constraints during training, \textsc{DeNSe}
generates (at inference time) trees for the overwhelming majority of sentences,
while non-tree outputs can be adjusted with a maximum spanning tree algorithm.
We evaluate \textsc{DeNSe} on four languages (English, Chinese, Czech, and
German) with varying degrees of non-projectivity. Despite the simplicity of the
approach, our parsers are on par with the state of the art.


title: Bicyclic graphs with extremal degree resistance distance

abstract:
  Let $r(u,v)$ be the resistance distance between two vertices $u, v$ of a
simple graph $G$, which is the effective resistance between the vertices in the
corresponding electrical network constructed from $G$ by replacing each edge of
$G$ with a unit resistor. The degree resistance distance of a simple graph $G$
is defined as ${D_R}(G) = \sum\limits_{\{u,v\} \subseteq V(G)} {[d(u) +
d(v)]r(u,v)},$ where $d(u)$ is the degree of the vertex $u$. In this paper, the
bicyclic graphs with extremal degree resistance distance are strong-minded. We
first determine the $n$-vertex bicyclic graphs having precisely two cycles with
minimum and maximum degree resistance distance. We then completely characterize
the bicyclic graphs with extremal degree resistance distance.


title:
Canonical formulation and path integral for local vacuum energy
  sequestering

abstract:
  We establish the Hamiltonian analysis and the canonical path integral for a
local formulation of vacuum energy sequestering. In particular, by considering
the state of the universe as a superposition of vacuum states corresponding to
different values of the cosmological and gravitational constants, the path
integral is extended to include integrations over the cosmological and
gravitational constants. The result is an extension of the Ng-van Dam form of
the path integral of unimodular gravity. It is argued to imply a relation
between the fraction of the most likely values of the gravitational and
cosmological constants and the average values of the energy density and
pressure of matter over spacetime. Finally, we construct and analyze a
BRST-exact formulation of the theory, which can be considered as a topological
field theory.


title:
Enhancing the LexVec Distributed Word Representation Model Using
  Positional Contexts and External Memory

abstract:
  In this paper we take a state-of-the-art model for distributed word
representation that explicitly factorizes the positive pointwise mutual
information (PPMI) matrix using window sampling and negative sampling and
address two of its shortcomings. We improve syntactic performance by using
positional contexts, and solve the need to store the PPMI matrix in memory by
working on aggregate data in external memory. The effectiveness of both
modifications is shown using word similarity and analogy tasks.


title:
Statistical Pattern Recognition for Driving Styles Based on Bayesian
  Probability and Kernel Density Estimation

abstract:
  Driving styles have a great influence on vehicle fuel economy, active safety,
and drivability. To recognize driving styles of path-tracking behaviors for
different divers, a statistical pattern-recognition method is developed to deal
with the uncertainty of driving styles or characteristics based on probability
density estimation. First, to describe driver path-tracking styles, vehicle
speed and throttle opening are selected as the discriminative parameters, and a
conditional kernel density function of vehicle speed and throttle opening is
built, respectively, to describe the uncertainty and probability of two
representative driving styles, e.g., aggressive and normal. Meanwhile, a
posterior probability of each element in feature vector is obtained using full
Bayesian theory. Second, a Euclidean distance method is involved to decide to
which class the driver should be subject instead of calculating the complex
covariance between every two elements of feature vectors. By comparing the
Euclidean distance between every elements in feature vector, driving styles are
classified into seven levels ranging from low normal to high aggressive.
Subsequently, to show benefits of the proposed pattern-recognition method, a
cross-validated method is used, compared with a fuzzy logic-based
pattern-recognition method. The experiment results show that the proposed
statistical pattern-recognition method for driving styles based on kernel
density estimation is more efficient and stable than the fuzzy logic-based
method.


title:
Spread of a Catalytic Branching Random Walk on a Multidimensional
  Lattice

abstract:
  For a supercritical catalytic branching random walk on Z^d (d is positive
integer) with an arbitrary finite catalysts set we study the spread of
particles population as time grows to infinity. Namely, we divide by t the
position coordinates of each particle existing at time t and then let t tend to
infinity. It is shown that in the limit there are a.s. no particles outside the
closed convex surface in R^d which we call the propagation front and, under
condition of infinite number of visits of the catalysts set, a.s. there exist
particles on the propagation front. We also demonstrate that the propagation
front is asymptotically densely populated and derive its alternative
representation. Recent strong limit theorems for total and local particles
numbers established by the author play an essential role. The results obtained
develop ones by Ph.Carmona and Y.Hu (2014) devoted to the spread of catalytic
branching random walk on Z.
  Keywords and phrases: branching random walk, supercritical regime, spread of
population, propagation front, many-to-one lemma.


title: Incorporating long-range consistency in CNN-based texture generation

abstract:
  Gatys et al. (2015) showed that pair-wise products of features in a
convolutional network are a very effective representation of image textures. We
propose a simple modification to that representation which makes it possible to
incorporate long-range structure into image generation, and to render images
that satisfy various symmetry constraints. We show how this can greatly improve
rendering of regular textures and of images that contain other kinds of
symmetric structure. We also present applications to inpainting and season
transfer.


title: Nonparametric hypersurfaces moving by powers of Gauss curvature

abstract:
  We study asymptotic behavior of nonparametric hypersurfaces moving by
$\alpha$ powers of Gauss curvature $\alpha > 1/n$. Our work generalizes the
results of V. Oliker [Oli91] for $\alpha= 1$.


title:
A Survey of Research on Control of Teams of Small Robots in Military
  Operations

abstract:
  While a number of excellent review articles on military robots have appeared
in existing literature, this paper focuses on a distinct sub-space of related
problems: small military robots organized into moderately sized squads,
operating in a ground combat environment. Specifically, we consider the
following: - Command of practical small robots, comparable to current
generation, small unmanned ground vehicles (e.g., PackBots) with limited
computing and sensor payload, as opposed to larger vehicle-sized robots or
micro-scale robots; - Utilization of moderately sized practical forces of 3-10
robots applicable to currently envisioned military ground operations; - Complex
three-dimensional physical environments, such as urban areas or mountainous
terrains and the inherent difficulties they impose, including limited and
variable fields of observation, difficult navigation, and intermittent
communication; - Adversarial environments where the active, intelligent enemy
is the key consideration in determining the behavior of the robotic force; and
- Purposeful, partly autonomous, coordinated behaviors that are necessary for
such a robotic force to survive and complete missions; these are far more
complex than, for example, formation control or field coverage behavior.


title:
Conforming restricted Delaunay mesh generation for piecewise smooth
  complexes

abstract:
  A Frontal-Delaunay refinement algorithm for mesh generation in piecewise
smooth domains is described. Built using a restricted Delaunay framework, this
new algorithm combines a number of novel features, including: (i) an
unweighted, conforming restricted Delaunay representation for domains specified
as a (non-manifold) collection of piecewise smooth surface patches and curve
segments, (ii) a protection strategy for domains containing curve segments that
subtend sharply acute angles, and (iii) a new class of off-centre refinement
rules designed to achieve high-quality point-placement along embedded curve
features. Experimental comparisons show that the new Frontal-Delaunay algorithm
outperforms a classical (statically weighted) restricted Delaunay-refinement
technique for a number of three-dimensional benchmark problems.


title:
Fluctuations of a surface relaxation model in interacting scale free
  networks

abstract:
  Isolated complex networks have been studied deeply in the last decades due to
the fact that many real systems can be modeled using these types of structures.
However, it is well known that the behavior of a system not only depends on
itself, but usually also depends on the dynamics of other structures. For this
reason, interacting complex networks and the processes developed on them have
been the focus of study of many researches in the last years. One of the most
studied subjects in this type of structures is the Synchronization problem,
which is important in a wide variety of processes in real systems. In this
manuscript we study the synchronization of two interacting scale-free networks,
in which each node has $ke$ dependency links with different nodes in the other
network. We map the synchronization problem with an interface growth, by
studying the fluctuations in the steady state of a scalar field defined in both
networks.
  We find that as $ke$ slightly increases from $ke=0$, there is a really
significant decreasing in the fluctuations of the system. However, this
considerable improvement takes place mainly for small values of $ke$, when the
interaction between networks becomes stronger there is only a slight change in
the fluctuations. We characterize how the dispersion of the scalar field
depends on the internal degree, and we show that a combination between the
decreasing of this dispersion and the integer nature of our growth model are
the responsible for the behavior of the fluctuations with $ke$.


title:
Minimal prospects for radio detection of extensive air showers in the
  atmosphere of Jupiter

abstract:
  One possible approach for detecting ultra-high-energy cosmic rays and
neutrinos is to search for radio emission from extensive air showers created
when they interact in the atmosphere of Jupiter, effectively utilizing Jupiter
as a particle detector. We investigate the potential of this approach. For
searches with current or planned radio telescopes we find that the effective
area for detection of cosmic rays is substantial (~3*10^7 km^2), but the
acceptance angle is so small that the typical geometric aperture (~10^3 km^2
sr) is less than that of existing terrestrial detectors, and cosmic rays also
cannot be detected below an extremely high threshold energy (~10^23 eV). The
geometric aperture for neutrinos is slightly larger, and greater sensitivity
can be achieved with a radio detector on a Jupiter-orbiting satellite, but in
neither case is this sufficient to constitute a practical detection technique.
Exploitation of the large surface area of Jupiter for detecting
ultra-high-energy particles remains a long-term prospect that will require a
different technique, such as orbital fluorescence detection.


title: An Attentional Neural Conversation Model with Improved Specificity

abstract:
  In this paper we propose a neural conversation model for conducting
dialogues. We demonstrate the use of this model to generate help desk
responses, where users are asking questions about PC applications. Our model is
distinguished by two characteristics. First, it models intention across turns
with a recurrent network, and incorporates an attention model that is
conditioned on the representation of intention. Secondly, it avoids generating
non-specific responses by incorporating an IDF term in the objective function.
The model is evaluated both as a pure generation model in which a help-desk
response is generated from scratch, and as a retrieval model with performance
measured using recall rates of the correct response. Experimental results
indicate that the model outperforms previously proposed neural conversation
architectures, and that using specificity in the objective function
significantly improves performances for both generation and retrieval.


title: Robust Inversion Methods for Aerosol Spectroscopy

abstract:
  The Fast Aerosol Spectrometer (FASP) is a device for spectral aerosol
measurements. Its purpose is to safely monitor the atmosphere inside a reactor
containment. First we describe the FASP and explain its basic physical laws.
Then we introduce our reconstruction methods for aerosol particle size
distributions designed for the FASP. We extend known existence results for
constrained Tikhonov regularization by uniqueness criteria and use those to
generate reasonable models for the size distributions. We apply a Bayesian
model-selection framework on these pre-generated models. We compare our
algorithm with classical inversion methods using simulated measurements. We
then extend our reconstruction algorithm for two-component aerosols, so that we
can simultaneously retrieve their particle-size distributions and unknown
volume fractions of their two components. Finally we present the results of a
numerical study for the extended algorithm.


title:
Congruence primes for automorphic forms on unitary groups and
  applications to the arithmetic of Ikeda lifts

abstract:
  In this paper we provide a sufficient condition for a prime to be a
congruence prime for an automorphic form $f$ on the unitary group $U(n,n)(A_F)$
for a large class of totally real fields $F$ via a divisibility of a special
value of the standard $L$-function associated to $f$. We also study $\ell$-adic
properties of the Fourier coefficients of an Ikeda lift $I_{\phi}$ (of an
elliptic modular form $\phi$) on $U(n,n)(A_{\mathbf{Q}})$ proving that they are
$\ell$-adic integers which do not all vanish modulo $\ell$. Finally we combine
these results to show that the condition of $\ell$ being a congruence prime for
$I_{\phi}$ is controlled by the $\ell$-divisibility of a product of special
values of the symmetric square $L$-function of $\phi$. We close the paper by
computing an example when our main theorem applies.


title:
Weighted $\ell_1$-Minimization for Sparse Recovery under Arbitrary Prior
  Information

abstract:
  Weighted $\ell_1$-minimization has been studied as a technique for the
reconstruction of a sparse signal from compressively sampled measurements when
prior information about the signal, in the form of a support estimate, is
available. In this work, we study the recovery conditions and the associated
recovery guarantees of weighted $\ell_1$-minimization when arbitrarily many
distinct weights are permitted. For example, such a setup might be used when
one has multiple estimates for the support of a signal, and these estimates
have varying degrees of accuracy. Our analysis yields an extension to existing
works that assume only a single support estimate set upon which a constant
weight is applied. We include numerical experiments, with both synthetic
signals and real video data, that demonstrate the benefits of allowing
non-uniform weights in the reconstruction procedure.


title:
Discriminants and Automorphism Groups of Veronese subrings of skew
  polynomial rings

abstract:
  We study important invariants and properties of the Veronese subalgebras of
$q$-skew polynomial rings, including their discriminant, center and
automorphism group, as well as cancellation property and the Tits alternative.


title: Coarse indices of twisted operators

abstract:
  Several formulas for computing coarse indices of twisted Dirac type operators
are introduced. One type of such formulas is by composition product in
$E$-theory. The other type is by module multiplications in $K$-theory, which
also yields an index theoretic interpretation of the duality between Roe
algebra and stable Higson corona.


title: Two Higgs doublet models augmented by a scalar color octet

abstract:
  The LHC is now studying in detail the couplings of the Higgs boson in order
to determine if there is new physics. Many recent studies have examined the
available fits to Higgs couplings from the perspective of constraining two
Higgs doublet models (2HDM). In this paper we extend those studies to include
constraints on the one loop couplings of the Higgs to gluons and photons. These
couplings are particularly sensitive to the existence of new colored particles
that are hard to detect otherwise and we use them to constrain a 2HDM augmented
with a color-octet scalar, a possibility motivated by minimal flavor violation.
We first study theoretical constraints on this model and then compare them with
LHC measurements.


title: RAISR: Rapid and Accurate Image Super Resolution

abstract:
  Given an image, we wish to produce an image of larger size with significantly
more pixels and higher image quality. This is generally known as the Single
Image Super-Resolution (SISR) problem. The idea is that with sufficient
training data (corresponding pairs of low and high resolution images) we can
learn set of filters (i.e. a mapping) that when applied to given image that is
not in the training set, will produce a higher resolution version of it, where
the learning is preferably low complexity. In our proposed approach, the
run-time is more than one to two orders of magnitude faster than the best
competing methods currently available, while producing results comparable or
better than state-of-the-art.
  A closely related topic is image sharpening and contrast enhancement, i.e.,
improving the visual quality of a blurry image by amplifying the underlying
details (a wide range of frequencies). Our approach additionally includes an
extremely efficient way to produce an image that is significantly sharper than
the input blurry one, without introducing artifacts such as halos and noise
amplification. We illustrate how this effective sharpening algorithm, in
addition to being of independent interest, can be used as a pre-processing step
to induce the learning of more effective upscaling filters with built-in
sharpening and contrast enhancement effect.


title:
Scale-free channeling patterns near the onset of erosion of sheared
  granular beds

abstract:
  Erosion shapes our landscape and occurs when a sufficient shear stress is
exerted by a fluid on a sedimented layer. What controls erosion at a
microscopic level remains debated, especially near the threshold forcing where
it stops. Here we study experimentally the collective dynamics of the moving
particles, using a set-up where the system spontaneously evolves toward the
erosion onset. We find that the spatial organization of the erosion flux is
heterogeneous in space, and occurs along channels of local flux $\sigma$ whose
distribution displays scaling near threshold and follows $P(\sigma)\sim
J/\sigma$, where $J$ is the mean erosion flux. Channels are strongly correlated
in the direction of forcing but not in the transverse direction. We show that
these results quantitatively agree with a model where the dynamics is governed
by the competition of disorder (which channels mobile particles) and particle
interactions (which reduces channeling). These observations support that for
laminar flows, erosion is a dynamical phase transition which shares similarity
with the plastic depinning transition occurring in dirty superconductors. The
methodology we introduce here could be applied to probe these systems as well.


title:
Vector magnetometry using silicon vacancies in 4H-SiC at ambient
  conditions

abstract:
  Point defects in solids promise precise measurements of various quantities.
Especially magnetic field sensing using the spin of point defects has been of
great interest recently. When optical readout of spin states is used, point
defects achieve optical magnetic imaging with high spatial resolution at
ambient conditions. Here, we demonstrate that genuine optical vector
magnetometry can be realized using the silicon vacancy in SiC, which has an
uncommon S=3/2 spin. To this end, we develop and experimentally test sensing
protocols based on a reference field approach combined with multi frequency
spin excitation. Our works suggest that the silicon vacancy in an
industry-friendly platform, SiC, has potential for various magnetometry
applications at ambient conditions.


title: RENORM tensor-Pomeron diffractive predictions

abstract:
  Predictions of the elastic scattering, total-inetastic, and total
proton-proton cross sections, based on a Regge theory inspired tensor-Pomeron
implementation of the RENORM model for hadronic diffraction, are compared to
the latest experimental measurements at the LHC. The measured cross sections
are in good agreement within the experimental uncertainties of the data and the
theoretical uncertainties of the model, reaching down to the ~1% level.


title:
Experimental demonstration of acoustic wave induced magnetization
  switching of dipole coupled magnetostrictive nanomagnets for ultralow power
  computing

abstract:
  We report nanomagnetic switching with Acoustic Waves (AW) launched from
interdigitated electrodes that modulate the stress anisotropy of elliptical
cobalt nanoscale magnetostrictive magnets (340 nm x 270 nm x 12 nm) delineated
on 128 degree Y-cut lithium niobate. The dipole-coupled nanomagnet pairs are in
a single-domain state and are initially magnetized along the major axis of the
ellipse, with their magnetizations parallel to each other. The magnetizations
of nanomagnets having lower shape anisotropy are reversed upon acoustic wave
propagation. Thereafter, the magnetization of these nanomagnets remains in the
reversed state and demonstrate non-volatility. This executes a 'NOT' operation.
This proof of acoustic wave induced magnetic state reversal in dipole-coupled
nanomagnets implementing a 'NOT' gate operation could potentially lead to the
development of extremely energy-efficient nanomagnetic logic. Furthermore,
fabrication complexity is reduced immensely due to the absence of individual
contacts to the nanomagnets, leading to lower energy dissipation


title:
Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated
  Reionization Around Luminous Star Forming Systems?

abstract:
  We discuss new Keck/MOSFIRE spectroscopic observations of four luminous
galaxies at z~7-9 selected to have intense optical line emission by
Roberts-Borsani et al. (2016). Previous follow-up has revealed Lyman-alpha in
two of the four galaxies. Our new MOSFIRE observations confirm that Lyman-alpha
is present in the entire sample. We detect Lyman-alpha emission in COS-zs7-1,
confirming its redshift as z=7.154, and we detect Lyman-alpha in EGS-zs8-2 at
z=7.477, verifying a tentative detection presented in an earlier study. The
ubiquity of Lyman-alpha in this sample is puzzling given that the IGM is likely
significantly neutral over 7<z<9. To investigate this result in more detail, we
have initiated a campaign to target UV metal emission in the four Lyman-alpha
emitters as a probe of both the radiation field and the velocity offset of
Lyman-alpha. Here we present the detection of intense CIII] emission in
EGS-zs8-1, a galaxy from this sample previously shown to have Lyman-alpha at
z=7.73. Photoionization models indicate that an intense radiation field and low
metallicity are required to reproduce the intense CIII] and optical line
emission. We argue that this extreme radiation field is likely to affect the
local environment, increasing the transmission of Lyman-alpha through the
galaxy. Moreover, the centroid of CIII] indicates that Lyman-alpha is
redshifted from the systemic value by 340 km/s. This velocity offset is larger
than that seen in less luminous systems, providing an additional explanation
for the transmission of Lyman-alpha emission through the IGM. Since the
transmission is further enhanced by the likelihood that such systems are also
situated in the densest regions with the largest ionized bubbles, the
visibility of Lyman-alpha at z>7 is expected to be strongly
luminosity-dependent, with the most effective transmission occurring in systems
with intense star formation.


title: Zoneout: Regularizing RNNs by Randomly Preserving Hidden Activations

abstract:
  We propose zoneout, a novel method for regularizing RNNs. At each timestep,
zoneout stochastically forces some hidden units to maintain their previous
values. Like dropout, zoneout uses random noise to train a pseudo-ensemble,
improving generalization. But by preserving instead of dropping hidden units,
gradient information and state information are more readily propagated through
time, as in feedforward stochastic depth networks. We perform an empirical
investigation of various RNN regularizers, and find that zoneout gives
significant performance improvements across tasks. We achieve competitive
results with relatively simple models in character- and word-level language
modelling on the Penn Treebank and Text8 datasets, and combining with recurrent
batch normalization yields state-of-the-art results on permuted sequential
MNIST.


title:
Geometrical symmetries of nuclear systems: D(3h) and T(d) symmetries in
  light nuclei

abstract:
  The role of discrete (or point-group) symmetries in alpha-cluster nuclei is
discussed in the framework of the algebraic cluster model which describes the
relative motion of the alpha-particles. Particular attention is paid to the
discrete symmetry of the geometric arrangement of the alpha-particles, and the
consequences for the structure of the corresponding rotational bands. The
method is applied to study cluster states in the nuclei 12C and 16O. The
observed level sequences can be understood in a simple way as a consequence of
the underlying discrete symmetry that characterizes the geometrical
configuration of the alpha-particles, i.e. an equilateral triangle with D(3h)
symmetry for 12C, and a tetrahedron with T(d) symmetry for 16O. The structure
of rotational bands provides a fingerprint of the underlying geometrical
configuration of alpha-particles.


title: Scene Grammars, Factor Graphs, and Belief Propagation

abstract:
  We describe a general framework for probabilistic modeling of complex scenes
and inference from ambiguous observations. The approach is motivated by
applications in image analysis and is based on the use of priors defined by
stochastic grammars. We define a class of grammars that capture relationships
between the objects in a scene and provide important contextual cues for
statistical inference. The distribution over scenes defined by a probabilistic
scene grammar can be represented by a graphical model and this construction can
be used for efficient inference with loopy belief propagation.
  We show experimental results with two different applications. One application
involves the reconstruction of binary contour maps. Another application
involves detecting and localizing faces in images. In both applications the
same framework leads to robust inference algorithms that can effectively
combine local information to reason about a scene.


title:
Object Kinetic Monte Carlo Simulations of Radiation Damage in Bulk
  Tungsten Part-II: With a PKA Spectrum Corresponding to 14-MeV Neutrons

abstract:
  Object kinetic Monte Carlo was employed to study the effect of dose rate on
the evolution of vacancy microstructure in polycrystalline tungsten under
neutron bombardment. The evolution was followed up to 1.0 displacement per atom
(dpa) with point defects generated in accordance with a primary knock-on atom
(PKA) spectrum corresponding to 14-MeV neutrons. The present study includes the
effect of grain size (2.0 and 4.0 $\mu$m) but excludes the impact of
transmutation or pre-existing defects beyond grain boundary sinks. Vacancy
cluster density increases with dose rate, while the density of vacancies
decreases. Consequently, the average vacancy cluster size and the fraction of
vacancies in visible clusters decrease with increasing dose rate. The density
of vacancies and vacancy clusters decrease with grain size such that the
average size of the clusters remains similar. However, the average size is
larger for larger grains at dose rates < 4.5 x 10-7 dpa/s. The trend of vacancy
accumulation as a function of dose, dose rate, and grain size is similar to
that obtained with the High Flux Isotope Reactor (HFIR) PKA spectrum. However,
the amount of vacancy accumulation and the vacancy microstructure are quite
different. Compared to the HFIR case, we find that even though the dose rates
are 2.5 times higher, the density of vacancies and the average vacancy cluster
sizes are lower. In addition, a void lattice forms only for the lowest two dose
rates (4.5 x 10-8 and 4.5 x 10-9 dpa/s). In contrast, a void lattice formed at
all dose rates studied using the HFIR PKA spectrum. We discuss in detail the
factors that lead to these different microstructures.


title:
Orbital-Exchange and Fractional Quantum Number Excitations in an
  f-electron Metal Yb$_2$Pt$_2$Pb

abstract:
  Exotic quantum states and fractionalized magnetic excitations, such as
spinons in one-dimensional chains, are generally viewed as belonging to the
domain of 3d transition metal systems with spins 1/2. Our neutron scattering
experiments on the 4f-electron metal Yb$_2$Pt$_2$Pb overturn this common
wisdom. We observe broad magnetic continuum dispersing in only one direction,
which indicates that the underlying elementary excitations are spinons carrying
fractional spin-1/2. These spinons are the quantum dynamics of the anisotropic,
orbital-dominated Yb moments, and thus these effective quantum spins are
emergent variables that encode the electronic orbitals. The unique birthmark of
their unusual origin is that only longitudinal spin fluctuations are
measurable, while the transverse excitations such as spin waves are virtually
invisible to magnetic neutron scattering. The proliferation of these
orbital-spinons strips the electrons of their orbital identity, and we thus
report here a new electron fractionalization phenomenon, charge-orbital
separation.


title: The Unusual Galactic Center Radio Source N3

abstract:
  Here we report on new, multi-wavelength radio observations of the unusual
point source "N3" that appears to be located in the vicinity of the Galactic
Center. VLA observations between 2 and 50 GHz reveal that N3 is a compact and
bright source (56 mJy at 10 GHz) with a non-thermal spectrum superimposed upon
the non-thermal radio filaments (NTFs) of the Radio Arc. Our highest frequency
observations place a strict upper limit of 65 x 28 mas on the size of N3. We
compare our observations to those of Yusef-Zadeh & Morris (1987) and Lang et
al. (1997) and conclude that N3 is variable over long time scales.
Additionally, we present the detection of a compact molecular cloud located
adjacent to N3 in projection. CH3CN, CH3OH, CS, HC3N, HNCO, SiO, SO, and NH3
are detected in the cloud and most transitions have FWHM line widths of ~20
km/s. The rotational temperature determined from the metastable NH3 transitions
ranges from 79 K to 183 K depending on the transitions used. We present
evidence that this molecular cloud is interacting with N3. After exploring the
relationship between the NTFs, molecular cloud, and N3, we conclude that N3
likely lies within the Galactic Center. We are able to rule out the HII region,
young supernova, active star, AGN, and micro-quasar hypotheses for N3. While a
micro-blazar may provide a viable explanation for N3, additional observations
are needed to determine the physical counterpart of this mysterious source.


title: Validity and regularization of classical half-space equations

abstract:
  Recent result [Wu and Guo, Comm. Math. Phys., 2015] has shown that over the
2D unit disk, the classical half-space equation (CHS) for the neutron transport
does not capture the correct boundary layer behaviour as long believed. In this
paper we develop a regularization technique for CHS to any arbitrary order and
use its first-order regularization to show that in the case of the 2D unit
disk, although CHS misrepresents the boundary layer behaviour, it does give the
correct boundary condition for the interior macroscopic (Laplace) equation.
Therefore CHS is still a valid equation to recover the correct boundary
condition for the interior Laplace equation over the 2D unit disk.