title:
Qualitative changes in spike-based neural coding and synchronization at
  the saddle-node loop bifurcation

abstract:
  Information processing in the brain crucially depends on encoding properties
of single neurons, with particular relevance of the spike-generation mechanism.
The latter hinges upon the bifurcation type at the transition point between
resting state and limit cycle spiking. Prominent qualitative changes in
encoding have previously been attributed to a specific switch of such a
bifurcation at the Bogdanov-Takens (BT) point. This study unveils another,
highly relevant and so far underestimated transition point: the saddle-node
loop bifurcation. As we show, this bifurcation turns out to induce even more
drastic changes in spike-based coding than the BT transition. This result
arises from a direct effect of the saddle-node loop bifurcation on the limit
cycle and hence spike dynamics, in contrast to the BT bifurcation, whose
immediate influence is exerted upon the subthreshold dynamics and hence only
indirectly relates to spiking. We specifically demonstrate that the saddle-node
loop bifurcation (i) ubiquitously occurs in planar neuron models with a
saddle-node on invariant cycle onset bifurcation, and (ii) results in a
symmetry breaking of the system's phase-response curve. The latter entails
close to optimal coding and synchronization properties in event-based
information processing units, such as neurons. The saddle-node loop bifurcation
leads to a peak in synchronization range and provides an attractive mechanism
for the so far unresolved facilitation of high frequencies in neuronal
processing. The derived bifurcation structure is of interest in any system for
which a relaxation limit is admissible, such as Josephson junctions and
chemical oscillators. On the experimental side, our theory applies to optical
stimulation of nerve cells, and reveals that these techniques could manipulate
a variety of information processing characteristics in nerve cells beyond pure
activation.


title: jInv -- a flexible Julia package for PDE parameter estimation

abstract:
  Estimating parameters of Partial Differential Equations (PDEs) from noisy and
indirect measurements often requires solving ill-posed inverse problems. These
so called parameter estimation or inverse medium problems arise in a variety of
applications such as geophysical, medical imaging, and nondestructive testing.
Their solution is computationally intense since the underlying PDEs need to be
solved numerous times until the reconstruction of the parameters is
sufficiently accurate. Typically, the computational demand grows significantly
when more measurements are available, which poses severe challenges to
inversion algorithms as measurement devices become more powerful.
  In this paper we present jInv, a flexible framework and open source software
that provides parallel algorithms for solving parameter estimation problems
with many measurements. Being written in the expressive programming language
Julia, jInv is portable, easy to understand and extend, cross-platform tested,
and well-documented. It provides novel parallelization schemes that exploit the
inherent structure of many parameter estimation problems and can be used to
solve multiphysics inversion problems as is demonstrated using numerical
experiments motivated by geophysical imaging.


title:
Rashba-Dresselhaus spin-splitting in the bulk ferroelectric oxide
  BiAlO$_3$

abstract:
  It has been recently suggested that the coexistence of ferroelectricity and
Rashba-like spin-splitting effects due to spin-orbit coupling in a single
material may allow for a non-volatile electric control of spin degrees of
freedom. In the present work, we compared the structural and ferroelectric
properties of tetragonal and rhombohedral phases of ferroelectric BiAlO$_3$ by
means of density-functional calculations. In both phases, we carefully
investigated Rashba and Dresselhaus effects, giving rise to spin-splitting in
their bulk electronic structure, particularly near the conduction band minimum,
supplementing our first-principles results with an effective $ k\cdot p$ model
analysis. The full reversal of the spin texture with ferroelectric polarization
switching was also predicted. BiAlO$_3$ can therefore be considered as the
first known oxide to exhibit a coexistence of ferroelectricity and
Rashba-Dresselhaus effects.


title: On specification and measure expansiveness

abstract:
  We relate the local specification and periodic shadowing properties. We also
clarify the relation between local weak specification and local specification
if the system is measure expansive. The notion of strong measure expansiveness
is introduced, and an example of a non-expansive systems with the strong
measure expansive property is given. Moreover, we find a family of examples
with the $N$-expansive property, which are not strong measure expansive. We
finally show a spectral decomposition theorem for strong measure expansive
dynamical systems with shadowing.


title:
Dispersing artifacts in FT-STS: a comparison of set point effects across
  acquisition modes

abstract:
  Fourier transform scanning tunneling spectroscopy (FT-STS), or quasiparticle
interference (QPI), has become an influential tool for the study of a wide
range of important materials in condensed matter physics. However, FT-STS in
complex materials is often challenging to interpret, requiring significant
theoretical input in many cases, making it crucial to understand potential
artifacts of the measurement. Here, we compare the most common modes of
acquiring FT-STS data and show through both experiment and simulations that
artifact features can arise that depend on how the tip height is stabilized
throughout the course of the measurement. The most dramatic effect occurs when
a series of dI/dV maps at different energies are acquired with simultaneous
constant current feedback; here a feature that disperses in energy appears that
is not observed in other measurement modes. Such artifact features are similar
to those arising from real physical processes in the sample and are susceptible
to misinterpretation.


title: Do alien particles exist, and can they be detected?

abstract:
  We may call "alien particles" those particles belonging to the matter/field
content of a $d$-dimensional brane other than the $3$-brane (or stack of
branes) sweeping the space-time in which we live. They can appear in our
space-time at the regions of intersection between our and their brane. They can
be identified (or not) as alien matter depending on their properties, on the
physical laws governing their evolution in the "homeland" brane, and on the
details of our detection techniques.


title: Lasing in dark and bright modes of a finite-sized plasmonic lattice

abstract:
  Lasing at the nanometre scale promises strong light-matter interactions and
ultrafast operation. Plasmonic resonances supported by metallic nanoparticles
have extremely small mode volumes and high field enhancements, making them an
ideal platform for studying nanoscale lasing. At visible frequencies, however,
the applicability of plasmon resonances is limited due to strong ohmic and
radiative losses. Intriguingly, plasmonic nanoparticle arrays support
non-radiative dark modes that offer longer life-times but are inaccessible to
far-field radiation. Here, we show lasing both in dark and bright modes of an
array of silver nanoparticles combined with optically pumped dye molecules.
Linewidths of 0.2 nanometers at visible wavelengths and room temperature are
observed. Access to the dark modes is provided by a coherent out-coupling
mechanism based on the finite size of the array. The results open a route to
utilize all modes of plasmonic lattices, also the high-Q ones, for studies of
strong light-matter interactions, condensation and photon fluids.


title:
The Formation of Bulges, Discs and Two Component Galaxies in the CANDELS
  Survey at z < 3

abstract:
  We examine a sample of 1495 galaxies in the CANDELS fields to determine the
evolution of two component galaxies, including bulges and discs, within massive
galaxies at the epoch 1 < z < 3 when the Hubble sequence forms. We fit all of
our galaxies' light profiles with a single S\'ersic fit, as well as with a
combination of exponential and S\'ersic profiles. The latter is done in order
to describe a galaxy with an inner and an outer component, or bulge and disc
component. We develop and use three classification methods (visual, F-test and
the RFF) to separate our sample into 1-component galaxies (disc/spheroids-like
galaxies) and 2-component galaxies (galaxies formed by an 'inner part' or bulge
and an 'outer part' or disc). We then compare the results from using these
three different ways to classify our galaxies. We find that the fraction of
galaxies selected as 2-component galaxies increases on average 50 per cent from
the lowest mass bin to the most massive galaxies, and decreases with redshift
by a factor of four from z = 1 to z = 3. We find that single S\'ersic
'disc-like' galaxies have the highest relative number densities at all
redshifts, and that 2-component galaxies have the greatest increase and become
at par with S\'ersic discs by z = 1. We also find that the systems we classify
as 2-component galaxies have an increase in the sizes of their outer
components, or 'discs', by about a factor of three from z = 3 to z = 1.5, while
the inner components or 'bulges' stay roughly the same size. This suggests that
these systems are growing from the inside out, whilst the bulges or protobulges
are in place early in the history of these galaxies. This is also seen to a
lesser degree in the growth of single 'disc-like' galaxies vs. 'spheroid-like'
galaxies over the same epoch.


title: Polymer-Fourier quantization of the scalar field revisited

abstract:
  The Polymer Quantization of the Fourier modes of the real scalar field is
studied within algebraic scheme. We replace the positive linear functional of
the standard Poincar\'e invariant quantization by a singular one. This singular
positive linear functional is constructed as mimicking the singular limit of
the complex structure of the Poincar\'e invariant Fock quantization. The
resulting symmetry group of such Polymer Quantization is the subgroup
$\mbox{SDiff}(\mathbb{R}^4)$ which is a subgroup of $\mbox{Diff}(\mathbb{R}^4)$
formed by spatial volume preserving diffeomorphisms. In consequence, this
yields an entirely different irreducible representation of the Canonical
Commutation Relations, non-unitary equivalent to the standard Fock
representation. We also compared the Poincar\'e invariant Fock vacuum with the
Polymer Fourier vacuum.


title: High-Dimensional Sparse Fourier Algorithms

abstract:
  In this paper, we discuss the development of a sublinear sparse Fourier
algorithm for high-dimensional data. In ``Adaptive Sublinear Time Fourier
Algorithm" by D. Lawlor, Y. Wang and A. Christlieb (2013), an efficient
algorithm with $\Theta(k\log k)$ average-case runtime and $\Theta(k)$
average-case sampling complexity for the one-dimensional sparse FFT was
developed for signals of bandwidth $N$, where $k$ is the number of significant
modes such that $k\ll N$.
  In this work we develop an efficient algorithm for sparse FFT for higher
dimensional signals, extending some of the ideas in the paper mentioned above.
Note a higher dimensional signal can always be unwrapped into a one dimensional
signal, but when the dimension gets large, unwrapping a higher dimensional
signal into a one dimensional array is far too expensive to be realistic. Our
approach here introduces two new concepts: ``partial unwrapping'' and
``tilting''. These two ideas allow us to efficiently compute the sparse FFT of
higher dimensional signals.


title:
Birch's theorem: if f(n) is multiplicative and has a non-decreasing
  normal order then f(n)=n^{alpha}

abstract:
  For pedagogical purposes (inclusion in lecture notes) we review the proof of
the theorem stated in the title. At the end we state a problem.


title: Raman tensor elements of $\beta\text{-Ga}_2\text{O}_3$

abstract:
  The Raman spectrum and particularly the Raman scattering intensities of
monoclinic $\beta\text{-Ga}_2\text{O}_3$ are investigated by experiment and
theory. The low symmetry of $\beta\text{-Ga}_2\text{O}_3$ results in a complex
dependence of the Raman intensity for the individual phonon modes on the
scattering geometry which is additionally affected by birefringence. We
measured the Raman spectra in dependence on the polarization direction for
backscattering on three crystallographic planes of
$\beta\text{-Ga}_2\text{O}_3$ and modeled these dependencies using a modified
Raman tensor formalism which takes birefringence into account. The spectral
position of all 15 Raman-active phonon modes and the Raman tensor elements of
13 modes were determined and are compared to results from ab-initio
calculations.


title:
Full Optical Control of Topological Transitions in Polariton Chern
  Insulator Analog

abstract:
  Exciton-polariton lattices allow to implement topologically protected
photonic edge states at optical frequencies. Taking advantage of the
interacting character of polaritons, we show that several topological phases,
belonging to the Quantum Anomalous Hall family, can occur in polariton graphene
with the TE-TM spin-orbit coupling and an effective Zeeman field. This Zeeman
field can be entirely controlled by the non-linearity of the macro-occupied
mode created by circularly polarized resonant pumping. The topological phases
found are distinct from the ones of normal graphene in presence of a
combination of Rashba and Zeeman field.


title: Fragmentation of a Jet with Small Radius

abstract:
  In this paper we consider the fragmentation of a parton into a jet with small
jet radius $R$. Perturbatively, logarithms of $R$ can appear, which for narrow
jets can lead to large corrections. Using soft-collinear effective theory, we
introduce the fragmentation function to a jet (FFJ), which describes the
fragmentation of a parton into a jet. We discuss how these objects are related
to the standard jet functions. Calculating the FFJ to next-to-leading order, we
show that these objects satisfy the standard
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations, with a natural
scale that depends upon $R$. By using the standard renormalization group
evolution, we can therefore resum logarithms of $R$. We further use the
soft-collinear effective theory to prove a factorization theorem where the FFJs
naturally appear, for the fragmentation of a hadron within a jet with small
$R$. Finally, we also show how this formalism can be used to resum the ratio of
jet radii for a subjet to be emitted from within a fat jet.


title: Magnetic Skyrmions on a Two-Lane Racetrack

abstract:
  Magnetic skyrmions are particle-like textures in the magnetization,
characterized by a topological winding number. Nanometer-scale skyrmions have
been observed at room temperature in magnetic multilayer structures. The
combination of small size, topological quantization, and their efficient
electric manipulation makes them interesting candidates for information
carriers in high-performance memory devices. A skyrmion racetrack memory has
been suggested where information is encoded in the distance between skyrmions
moving in a one-dimensional nanostrip. Here, we propose an alternative design
where skyrmions move in two (or more) parallel lanes and the information is
stored in the lane number of each skyrmion. Such a multilane track can be
constructed by controlling the height profile of the nanostrip. Repulsive
skyrmion-skyrmion interactions in narrow nanostrips guarantee that skyrmions on
different lanes cannot pass each other. Current pulses can be used to induce a
lane change. Combining these elements provides a robust, efficient design of
skyrmion-based storage devices.


title: Parallelizing quantum circuit synthesis

abstract:
  Quantum circuit synthesis is the process in which an arbitrary unitary
operation is decomposed into a sequence of gates from a universal set,
typically one which a quantum computer can implement both efficiently and
fault-tolerantly. As physical implementations of quantum computers improve, the
need is growing for tools which can effectively synthesize components of the
circuits and algorithms they will run. Existing algorithms for exact,
multi-qubit circuit synthesis scale exponentially in the number of qubits and
circuit depth, leaving synthesis intractable for circuits on more than a
handful of qubits. Even modest improvements in circuit synthesis procedures may
lead to significant advances, pushing forward the boundaries of not only the
size of solvable circuit synthesis problems, but also in what can be realized
physically as a result of having more efficient circuits.
  We present a method for quantum circuit synthesis using deterministic walks.
Also termed pseudorandom walks, these are walks in which once a starting point
is chosen, its path is completely determined. We apply our method to construct
a parallel framework for circuit synthesis, and implement one such version
performing optimal $T$-count synthesis over the Clifford+$T$ gate set. We use
our software to present examples where parallelization offers a significant
speedup on the runtime, as well as directly confirm that the 4-qubit 1-bit full
adder has optimal $T$-count 7 and $T$-depth 3.


title:
Multiplierless 16-point DCT Approximation for Low-complexity Image and
  Video Coding

abstract:
  An orthogonal 16-point approximate discrete cosine transform (DCT) is
introduced. The proposed transform requires neither multiplications nor
bit-shifting operations. A fast algorithm based on matrix factorization is
introduced, requiring only 44 additions---the lowest arithmetic cost in
literature. To assess the introduced transform, computational complexity,
similarity with the exact DCT, and coding performance measures are computed.
Classical and state-of-the-art 16-point low-complexity transforms were used in
a comparative analysis. In the context of image compression, the proposed
approximation was evaluated via PSNR and SSIM measurements, attaining the best
cost-benefit ratio among the competitors. For video encoding, the proposed
approximation was embedded into a HEVC reference software for direct comparison
with the original HEVC standard. Physically realized and tested using FPGA
hardware, the proposed transform showed 35% and 37% improvements of area-time
and area-time-squared VLSI metrics when compared to the best competing
transform in the literature.


title: Find your Way by Observing the Sun and Other Semantic Cues

abstract:
  In this paper we present a robust, efficient and affordable approach to
self-localization which does not require neither GPS nor knowledge about the
appearance of the world. Towards this goal, we utilize freely available
cartographic maps and derive a probabilistic model that exploits semantic cues
in the form of sun direction, presence of an intersection, road type, speed
limit as well as the ego-car trajectory in order to produce very reliable
localization results. Our experimental evaluation shows that our approach can
localize much faster (in terms of driving time) with less computation and more
robustly than competing approaches, which ignore semantic information.


title: Noncommutative Brownian motion

abstract:
  We investigate the classical Brownian motion of a particle in a
two-dimensional noncommutative (NC) space. Using the standard NC algebra
embodied by the sympletic Weyl-Moyal formalism we find that noncommutativity
induces a non-vanishing correlation between both coordinates at different
times. The effect stands out as a signature of spatial noncommutativity and
thus could offer a way to experimentally detect the phenomena. We further
discuss some limiting scenarios and the trade-off between the scale imposed by
the NC structure and the parameters of the Brownian motion itself.


title:
Axial acoustic radiation force on rigid oblate and prolate spheroids in
  Bessel vortex beams of progressive, standing and quasi-standing waves

abstract:
  The analysis using the partial-wave series expansion (PWSE) method in
spherical coordinates is extended to evaluate the acoustic radiation force
experienced by rigid oblate and prolate spheroids centered on the axis of wave
propagation of high-order Bessel vortex beams composed of progressive, standing
and quasi-standing waves, respectively. A coupled system of linear equations is
derived after applying the Neumann boundary condition for an immovable surface
in a non-viscous fluid, and solved numerically by matrix inversion after
performing a single numerical integration procedure. The system of linear
equations depends on the partial-wave index n and the order of the Bessel
vortex beam m using truncated but converging PWSEs in the least-squares sense.
Numerical results for the radiation force function, which is the radiation
force per unit energy density and unit cross-sectional surface, are computed
with particular emphasis on the amplitude ratio describing the transition from
the progressive to the pure standing waves cases, the aspect ratio (i.e., the
ratio of the major axis over the minor axis of the spheroid), the half-cone
angle and order of the Bessel vortex beam, as well as the dimensionless size
parameter. A generalized expression for the radiation force function is derived
for cases encompassing the progressive, standing and quasi-standing waves of
Bessel vortex beams. This expression can be reduced to other types of
beams/waves such as the zeroth-order Bessel non-vortex beam or the infinite
plane wave case by appropriate selection of the beam parameters. The results
for progressive waves reveal a tractor beam behavior, characterized by the
emergence of an attractive pulling force acting in opposite direction of wave
propagation. Moreover, the transition to the quasi-standing and pure standing
wave cases shows the acoustical tweezers behavior in dual-beam Bessel vortex
beams.


title: Priority-based Riemann solver for traffic flow on networks

abstract:
  In this article we introduce a new Riemann solver for traffic flow on
networks. The Priority Riemann solver (PRS) provides a solution at junctions by
taking into consideration priorities for the incoming roads and maximization of
through flux. We prove existence of solutions for the solver for junctions with
up to two incoming and two outgoing roads and show numerically the comparison
with previous Riemann solvers. Additionally, we introduce a second version of
the solver that considers the priorities as softer constraints and illustrate
numerically the differences between the two solvers.


title: Learning to Poke by Poking: Experiential Learning of Intuitive Physics

abstract:
  We investigate an experiential learning paradigm for acquiring an internal
model of intuitive physics. Our model is evaluated on a real-world robotic
manipulation task that requires displacing objects to target locations by
poking. The robot gathered over 400 hours of experience by executing more than
100K pokes on different objects. We propose a novel approach based on deep
neural networks for modeling the dynamics of robot's interactions directly from
images, by jointly estimating forward and inverse models of dynamics. The
inverse model objective provides supervision to construct informative visual
features, which the forward model can then predict and in turn regularize the
feature space for the inverse model. The interplay between these two objectives
creates useful, accurate models that can then be used for multi-step decision
making. This formulation has the additional benefit that it is possible to
learn forward models in an abstract feature space and thus alleviate the need
of predicting pixels. Our experiments show that this joint modeling approach
outperforms alternative methods.


title:
On Calabi-Yau generalized complete intersections from Hirzebruch
  varieties and novel K3-fibrations

abstract:
  We consider the construction of Calabi-Yau varieties recently generalized to
where the defining equations may have negative degrees over some projective
space factors in the embedding space. Within such "generalized complete
intersection" Calabi-Yau ("gCICY") three-folds, we find several sequences of
distinct manifolds. These include both novel elliptic and K3-fibrations and
involve Hirzebruch surfaces and their higher dimensional analogues. En route,
we generalize the standard techniques of cohomology computation to these
generalized complete intersection Calabi-Yau varieties.


title: The Albedo Distribution of Near Earth Asteroids

abstract:
  The cryogenic WISE mission in 2010 was extremely sensitive to asteroids and
not biased against detecting dark objects. The albedos of 428 Near Earth
Asteroids (NEAs) observed by WISE during its fully cryogenic mission can be fit
quite well by a 3 parameter function that is the sum of two Rayleigh
distributions. The Rayleigh distribution is zero for negative values, and
follows $f(x) = x \exp[-x^2/(2\sigma^2)]/\sigma^2$ for positive x. The peak
value is at x=\sigma, so the position and width are tied together. The three
parameters are the fraction of the objects in the dark population, the position
of the dark peak, and the position of the brighter peak. We find that 25.3% of
the NEAs observed by WISE are in a very dark population peaking at $p_V =
0.03$, while the other 74.7% of the NEAs seen by WISE are in a moderately dark
population peaking at $p_V = 0.168$. A consequence of this bimodal distribution
is that the Congressional mandate to find 90% of all NEAs larger than 140 m
diameter cannot be satisfied by surveying to H=22 mag, since a 140 m diameter
asteroid at the very dark peak has H=23.7 mag, and more than 10% of NEAs are
darker than p_V = 0.03.


title: Joint product numerical range and geometry of reduced density matrices

abstract:
  The reduced density matrices of a many-body quantum system form a convex set,
whose three-dimensional projection $\Theta$ is convex in $\mathbb{R}^3$. The
boundary $\partial\Theta$ of $\Theta$ may exhibit nontrivial geometry, in
particular ruled surfaces. Two physical mechanisms are known for the origins of
ruled surfaces: symmetry breaking and gapless. In this work, we study the
emergence of ruled surfaces for systems with local Hamiltonians in infinite
spatial dimension, where the reduced density matrices are known to be separable
as a consequence of the quantum de Finetti's theorem. This allows us to
identify the reduced density matrix geometry with joint product numerical range
$\Pi$ of the Hamiltonian interaction terms. We focus on the case where the
interaction terms have certain structures, such that ruled surface emerge
naturally when taking a convex hull of $\Pi$. We show that, a ruled surface on
$\partial\Theta$ sitting in $\Pi$ has a gapless origin, otherwise it has a
symmetry breaking origin. As an example, we demonstrate that a famous ruled
surface, known as the oloid, is a possible shape of $\Theta$, with two boundary
pieces of symmetry breaking origin separated by two gapless lines.


title:
Aharonov-Bohm effect in a helical ring with long-range hopping: Effects
  of Rashba spin-orbit interaction and disorder

abstract:
  We study Aharonov-Bohm effect in a two-terminal helical ring with long-range
hopping in presence of Rashba spin-orbit interaction. We explore how the spin
polarization behavior changes depending on the applied magnetic flux and the
incoming electron energy. The most interesting feature that we articulate in
this system is that zero-energy crossings appear in the energy spectra at
$\Phi=0$ and also at integer multiples of half-flux quantum values ($n
\Phi_0/2$, $n$ being an integer) of the applied magnetic flux. We investigate
the transport properties of the ring using Green's function formalism and find
that the zero energy transmission peaks corresponding to those zero energy
crossings vanish in presence of Rashba spin-orbit interaction. We also
incorporate static random disorder in our system and show that the zero energy
crossings and transmission peaks are not immune to disorder even in absence of
Rashba spin-orbit interaction. The latter prevents the possibility of behaving
these helical states in the ring like topological insulator edge states.


title:
Enhanced production of multi-strange hadrons in high-multiplicity
  proton-proton collisions

abstract:
  At sufficiently high temperature and energy density, nuclear matter undergoes
a transition to a phase in which quarks and gluons are not confined: the
Quark-Gluon Plasma (QGP) [1]. Such an extreme state of strongly-interacting QCD
(Quantum Chromo-Dynamics) matter is produced in the laboratory with high-energy
collisions of heavy nuclei, where an enhanced production of strange hadrons is
observed [2-6]. Strangeness enhancement, originally proposed as a signature of
QGP formation in nuclear collisions [7], is more pronounced for multi-strange
baryons. Several effects typical of heavy-ion phenomenology have been observed
in high-multiplicity proton-proton (pp) collisions [8,9]. Yet, enhanced
production of multi-strange particles has not been reported so far. Here we
present the first observation of strangeness enhancement in high-multiplicity
pp collisions. We find that the integrated yields of strange and multi-strange
particles relative to pions increases significantly with the event
charged-particle multiplicity. The measurements are in remarkable agreement
with p-Pb collision results [10,11] indicating that the phenomenon is related
to the final system created in the collision. In high-multiplicity events
strangeness production reaches values similar to those observed in Pb-Pb
collisions, where a QGP is formed.


title: Generalized Preconditioning and Network Flow Problems

abstract:
  We consider approximation algorithms for the problem of finding $x$ of
minimal norm $\|x\|$ satisfying a linear system $\mathbf{A} x = \mathbf{b}$,
where the norm $\|\cdot \|$ is arbitrary and generally non-Euclidean. We show a
simple general technique for composing solvers, converting iterative solvers
with residual error $\|\mathbf{A} x - \mathbf{b}\| \leq t^{-\Omega(1)}$ into
solvers with residual error $\exp(-\Omega(t))$, at the cost of an increase in
$\|x\|$, by recursively invoking the solver on the residual problem
$\tilde{\mathbf{b}} = \mathbf{b} - \mathbf{A} x$. Convergence of the composed
solvers depends strongly on a generalization of the classical condition number
to general norms, reducing the task of designing algorithms for many such
problems to that of designing a \emph{generalized preconditioner} for
$\mathbf{A}$. The new ideas significantly generalize those introduced by the
author's earlier work on maximum flow, making them more widely applicable.
  As an application of the new technique, we present a nearly-linear time
approximation algorithm for uncapacitated minimum-cost flow on undirected
graphs. Given an undirected graph with $m$ edges labelled with costs, and $n$
vertices labelled with demands, the algorithm takes
$\epsilon^{-2}m^{1+o(1)}$-time and outputs a flow routing the demands with
total cost at most $(1+\epsilon)$ times larger than minimal, along with a dual
solution proving near-optimality. The generalized preconditioner is obtained by
embedding the cost metric into $\ell_1$, and then considering a simple
hierarchical routing scheme in $\ell_1$ where demands initially supported on a
dense lattice are pulled from a sparser lattice by randomly rounding unaligned
coordinates to their aligned neighbors. Analysis of the generalized condition
number for the preconditioner follows that of the classical multigrid algorithm
for lattice Laplacian systems.


title: On the Poisson relation for compact Lie groups

abstract:
  Intuition drawn from quantum mechanics and geometric optics raises the
following long-standing question: can the length spectrum of a closed
Riemannian manifold be recovered from its Laplace spectrum? The Poisson
relation states that for any closed Riemannian manifold $(M,g)$ the singular
support of the trace of its wave group---a spectrally determined tempered
distribution---is contained in the set consisting of $\pm \tau$, where $\tau$
is the length of a smoothly closed geodesic in $(M,g)$. Therefore, in cases
where the Poisson relation is an equality, we obtain a method for retrieving
the length spectrum of a manifold from its Laplace spectrum. The Poisson
relation is known to be an equality for sufficiently "bumpy" Riemannian
manifolds and there are no known counterexamples.
  We demonstrate that the Poisson relation is an equality for a compact Lie
group equipped with a generic bi-invariant metric. Consequently, the length
spectrum of a generic bi-invariant metric (and the rank of its underlying Lie
group) can be recovered from its Laplace spectrum. Furthermore, we exhibit a
substantial collection $\mathscr{G}$ of compact Lie groups---including those
that are either tori, simple, simply-connected, or products thereof---with the
property that for each group $U \in \mathscr{G}$ the Laplace spectrum of any
bi-invariant metric $g$ carried by $U$ encodes the length spectrum of $g$ and
the rank of $U$. The preceding statements are special cases of results
concerning compact globally symmetric spaces for which the semi-simple part of
the universal cover is split-rank. The manifolds considered herein join a short
list of families of non-"bumpy" Riemannian manifolds for which the Poisson
relation is known to be an equality.


title:
Special Values of Motivic $L$-Functions and Zeta-Polynomials for
  Symmetric Powers of Elliptic Curves

abstract:
  Let $\mathcal{M}$ be a pure motive over $\mathbb{Q}$ of odd weight $w\geq 3$,
even rank $d\geq 2$, and global conductor $N$ whose $L$-function
$L(s,\mathcal{M})$ coincides with the $L$-function of a self-dual algebraic
tempered cuspidal symplectic representation of
$\mathrm{GL}_{d}(\mathbb{A}_{\mathbb{Q}})$. We show that a certain polynomial
which generates special values of $L(s,\mathcal{M})$ (including all of the
critical values) has all of its zeros equidistributed on the unit circle,
provided that $N$ or $w$ are sufficiently large with respect to $d$. These
special values have arithmetic significance in the context of the Bloch-Kato
conjecture. We focus on applications to symmetric powers of semistable elliptic
curves over $\mathbb{Q}$. Using the Rodriguez-Villegas transform, we use these
results to construct large classes of "zeta-polynomials" (in the sense of
Manin) arising from symmetric powers of semistable elliptic curves; these
polynomials have a functional equation relating $s\mapsto 1-s$, and all of
their zeros on the line $\operatorname{Re}(s)=1/2$.


title:
An integral equation formulation for rigid bodies in Stokes flow in
  three dimensions

abstract:
  We present a new derivation of a boundary integral equation (BIE) for
simulating the three-dimensional dynamics of arbitrarily-shaped rigid particles
of genus zero immersed in a Stokes fluid, on which are prescribed forces and
torques. Our method is based on a single-layer representation and leads to a
simple second-kind integral equation. It avoids the use of auxiliary sources
within each particle that play a role in some classical formulations. We use a
spectrally accurate quadrature scheme to evaluate the corresponding layer
potentials, so that only a small number of spatial discretization points per
particle are required. The resulting discrete sums are computed in
$\mathcal{O}(n)$ time, where $n$ denotes the number of particles, using the
fast multipole method (FMM). The particle positions and orientations are
updated by a high-order time-stepping scheme. We illustrate the accuracy,
conditioning and scaling of our solvers with several numerical examples.


title:
Constructing and proving the ground state of a generalized Ising model
  by the cluster tree optimization algorithm

abstract:
  Generalized Ising models, also known as cluster expansions, are an important
tool in many areas of condensed-matter physics and materials science, as they
are often used in the study of lattice thermodynamics, solid-solid phase
transitions, magnetic and thermal properties of solids, and fluid mechanics.
However, the problem of finding the global ground state of generalized Ising
model has remained unresolved, with only a limited number of results for simple
systems known. We propose a method to efficiently find the periodic ground
state of a generalized Ising model of arbitrary complexity by a new algorithm
which we term cluster tree optimization. Importantly, we are able to show that
even in the case of an aperiodic ground state, our algorithm produces a
sequence of states with energy converging to the true ground state energy, with
a provable bound on error. Compared to the current state-of-the-art polytope
method, this algorithm eliminates the necessity of introducing an exponential
number of variables to counter frustration, and thus significantly improves
tractability. We believe that the cluster tree algorithm offers an intuitive
and efficient approach to finding and proving ground states of generalized
Ising Hamiltonians of arbitrary complexity, which will help validate
assumptions regarding local vs. global optimality in lattice models, as well as
offer insights into the low-energy behavior of highly frustrated systems.


title: Coupled-Beam and Coupled-Bunch Instabilities

abstract:
  A problem of coupled-beam instability is solved for two multibunch beams with
slightly different revolution frequencies, as in the Fermilab Recycler Ring
(RR). Sharing of the inter-bunch growth rates between the intra-bunch modes is
described. The general analysis is applied to the RR; possibilities to
stabilize the beams by means of chromaticity and feedback are considered.


title: Cluster dynamics largely shapes protoplanetary disc sizes

abstract:
  It is still on open question to what degree the cluster environment
influences the sizes of protoplanetary discs surrounding young stars.
Particularly so for the short-lived clusters typical for the solar
neighbourhood in which the stellar density and therefore the influence of the
cluster environment changes considerably over the first 10 Myr. In previous
studies often the effect of the gas on the cluster dynamics has been neglected,
this is remedied here. Using the code NBody6++ we study the stellar dynamics in
different developmental phases - embedded, expulsion, expansion - including the
gas and quantify the effect of fly-bys on the disc size. We concentrate on
massive clusters ($M_{\text{cl}} \geq 10^3 - 6 \cdot 10^4 M_{\text{Sun}}$),
which are representative for clusters like the Orion Nebula Cluster (ONC) or
NGC 6611. We find that not only the stellar density but also the duration of
the embedded phase matters. The densest clusters react fastest to the gas
expulsion and drop quickly in density, here 98% of relevant encounters happen
before gas expulsion. By contrast, discs in sparser clusters are initially less
affected but as they expand slower 13% of discs are truncated after gas
expulsion. For ONC-like clusters we find that usually discs larger than 500 AU
are affected by the environment, which corresponds to the observation that 200
AU-sized discs are common. For NGC 6611-like clusters disc sizes are cut-down
on average to roughly 100 AU. A testable hypothesis would be that the discs in
the centre of NGC 6611 should be on average ~20 AU and therefore considerably
smaller than in the ONC.


title:
Ultracold neutron detection with 6Li-doped glass scintillators, NANOSC:
  a fast ultracold neutron detector for the nEDM experiment at the Paul
  Scherrer Institute

abstract:
  This paper summarizes the results from measurements aiming to characterize
ultracold neutron detection with 6Li-doped glass scintillators. Single GS10 or
GS20 scintillators, with a thickness of 100-200 micrometer, fulfill the
ultracold neutron detection requirements with an acceptable neutron-gamma
discrimination. This discrimination is clearly improved with a stack of two
scintillators: a 6Li-depleted glass bonded to a 6Li-enriched glass. The optical
contact bonding is used between the scintillators in order to obtain a perfect
optical contact. The scintillator's detection efficiency is similar to that of
a 3He Strelkov gas detector. Coupled to a digital data acquisition system,
counting rates up to a few 10^5 counts/s can be handled. A detector based on
such a scintillator stack arrangement was built and has been used in the
neutron electric dipole moment experiment at the Paul Scherrer Institute since
2010. Its response for the regular runs of the neutron electric dipole moment
experiment is presented.


title: Deep XMM-Newton Observations of the NW Radio Relic Region of Abell 3667

abstract:
  The results of long XMM-Newton X-ray observations of the NW radio relic of
Abell 3667 are presented. A shock is detected at the sharp outer edge of the
radio relic, both in the X-ray surface brightness and the temperature profiles.
The Mach number is M = 2.54^+0.80_-0.43. The temperature jump at the shock is
larger than expected from the density jump, which may indicate that a
dynamically important magnetic field aligned primarily parallel to the shock
front is present. The gas temperature rises gradually over several arc minutes
within the shock region. This could indicate that the shock energy is initially
dissipated into some mix of thermal and nonthermal (e.g., turbulence)
components, and that the nonthermal energy decays into heat in the post-shock
region. The observed radio relic can be powered if ~0.2% of the energy
dissipated in the shock goes into the (re)acceleration of relativistic
electrons. We show that the observed steepening of the radio spectrum with
distance behind the shock is consistent with radiative losses by the
radio-emitting electrons. However, the radio spectrum immediately behind the
shock is flatter than expected for linear diffusive shock acceleration of
thermal electrons. This suggests that the shock re-accelerates a pre-existing
population of relativistic electrons. We also detect a bright, cool region (the
"Mushroom") to the south of the radio relic, which we propose is the remnant
cool core of a merging subcluster, and that this subcluster was the driver for
the observed NW shock. In this model, the properties of Abell 3667 are mainly
the result of an offset binary merger, and the cluster is being observed about
1 Gyr after first core passage. We predict that deeper X-ray or SZ observations
of the SE radio relic will reveal a second merger shock at the outer edge.


title: Cosmological Constraints with Clustering-Based Redshifts

abstract:
  We demonstrate that observations lacking reliable redshift information, such
as photometric and radio continuum surveys, can produce robust measurements of
cosmological parameters when empowered by clustering-based redshift estimation.
This method infers the redshift distribution based on the spatial clustering of
sources, using cross-correlation with a reference dataset with known redshifts.
Applying this method to the existing SDSS photometric galaxies, and projecting
to future radio continuum surveys, we show that sources can be efficiently
divided into several redshift bins, increasing their ability to constrain
cosmological parameters. We forecast constraints on the dark-energy
equation-of-state and on local non-gaussianity parameters. We explore several
pertinent issues, including the tradeoff between including more sources versus
minimizing the overlap between bins, the shot-noise limitations on binning, and
the predicted performance of the method at high redshifts. Remarkably, we find
that, once this technique is implemented, constraints on dynamical dark energy
from the SDSS imaging catalog can be competitive with, or better than, those
from the spectroscopic BOSS survey and even future planned experiments.
Further, constraints on primordial non-Gaussianity from future large-sky
radio-continuum surveys can outperform those from the Planck CMB experiment,
and rival those from future spectroscopic galaxy surveys. The application of
this method thus holds tremendous promise for cosmology.


title:
The Lyman-alpha luminosity function at z=5.7-6.6 and the steep drop of
  the faint end: implications for reionization

abstract:
  We present new results from the widest narrow band survey search for
Lyman-alpha (Lya) emitters at z=5.7, just after reionization. We survey a total
of 7 deg$^2$ spread over the COSMOS, UDS and SA22 fields. We find over 11,000
line emitters, out of which 514 are robust Lya candidates at z=5.7 within a
volume of 6.3x10$^6$ Mpc$^3$. Our Lya emitters span a wide range in Lya
luminosities, from faint to bright (L$_{\rm Ly\alpha}\sim10^{42.5-44}$ erg
s$^{-1}$) and rest-frame equivalent widths (EW$_0$~25-1000 \AA) in a single,
homogeneous data-set. By combining all our fields we find that the faint end
slope of the z=5.7 Lya luminosity function is very steep, with
$\alpha=-2.3^{+0.4}_{-0.3}$. We also present an updated z=6.6 Lya luminosity
function, based on comparable volumes and obtained with the same methods, which
we directly compare with that at z=5.7. We find a significant decline of the
number density of faint Lya emitters from z=5.7 to z=6.6 (by $0.5\pm0.1$ dex),
but no evolution at the bright end/no evolution in L*. Faint Lya emitters at
z=6.6 show much more extended haloes than those at z=5.7, suggesting that
neutral Hydrogen plays an important role, increasing the scattering and leading
to observations missing faint Lya emission within the epoch of reionization.
All together, our results suggest that we are observing patchy reionization
which happens first around the brightest Lya emitters, allowing the number
densities of those sources to remain unaffected by the increase of neutral
Hydrogen fraction from z~5 to z~7.


title:
Equilibrium model prediction for the scatter in the star-forming main
  sequence

abstract:
  The analytic "equilibrium model" for galaxy evolution using a mass balance
equation is able to reproduce mean observed galaxy scaling relations between
stellar mass, halo mass, star formation rate (SFR) and metallicity across the
majority of cosmic time with a small number of parameters related to feedback.
Here we aim to test this data-constrained model to quantify deviations from the
mean relation between stellar mass and SFR, i.e. the star-forming galaxy main
sequence (MS). We implement fluctuation in halo accretion rates parameterised
from merger-based simulations, and quantify the intrinsic scatter introduced
into the MS under the assumption that fluctuations in star formation follow
baryonic inflow fluctuations. We predict the 1-sigma MS scatter to be ~ 0.2 -
0.25 dex over the stellar mass range 10^8 Mo to 10^11 Mo and a redshift range
0.5 < z < 3 for SFRs averaged over 100 Myr. The scatter increases modestly at z
> 3, as well as by averaging over shorter timescales. The contribution from
merger-induced star formation is generally small, around 5% today and 10 - 15%
during the peak epoch of cosmic star formation. These results are generally
consistent with available observations, suggesting that deviations from the MS
primarily reflect stochasticity in the inflow rate owing to halo mergers.


title: Orbital eccentricities in primordial black holes binaries

abstract:
  It was recently suggested that the merger of $\sim30\,M_\odot$ primordial
black holes (PBHs) may provide a significant number of events in
gravitational-wave observatories over the next decade, if they make up an
appreciable fraction of the dark matter. Here we show that measurement of the
eccentricities of the inspiralling binary black holes can be used to
distinguish these binaries from those produced by more traditional
astrophysical mechanisms. These PBH binaries are formed on highly eccentric
orbits and can then merge on timescales that in some cases are years or less,
retaining some eccentricity in the last seconds before the merger. This is to
be contrasted with massive-stellar-binary, globular-cluster, or other
astrophysical origins for binary black holes (BBHs) in which the orbits have
very effectively circularized by the time the BBH enters the observable LIGO
window. Here we discuss the features of the gravitational-wave signals that
indicate this eccentricity and forecast the sensitivity of LIGO and the
Einstein Telescope to such effects. We show that if PBHs make up the dark
matter, then roughly one event should have a detectable eccentricity given
LIGO's expected sensitivity and observing time of six years. The Einstein
Telescope should see $O(10)$ such events after ten years.


title:
Secular dynamics of multiplanet systems: implications for the formation
  of hot and warm Jupiters via high-eccentricity migration

abstract:
  Hot Jupiters (HJs) are Jupiter-like planets that reside very closely to their
host star, within $\sim 0.1\,\mathrm{AU}$. Their formation is not well
understood. It is generally believed that they cannot have formed in situ,
implying that some form of migration must have occurred after their initial
formation. We study the production of HJs through secular evolution in
multiplanet systems with three to five planets. In this variant of high-$e$
migration, the eccentricity of the orbit of the innermost planet is excited on
secular time-scales, triggering orbital migration due to tidal dissipation. We
use a secular dynamics code and carry out a population synthesis study. We find
that HJs are only produced if the viscous time-scale is short ($\approx 0.014$
yr). In contrast, in up to $\approx 0.3$ of systems, the innermost planet is
tidally disrupted. The orbital period distribution is peaked around 5 d,
consistent with observations. The median HJ mass is $1\,M_\mathrm{J}$ with a
maximum of $\approx 2 \, M_\mathrm{J}$, similar to observed HJs. Approximately
0.1 of the HJs have retrograde orbits with respect to the stellar spin. We do
not find any warm Jupiters in our simulations, i.e. planets with semimajor axes
between 0.1 and 1 AU.


title: A weak lensing view of the downsizing of star-forming galaxies

abstract:
  We describe a weak lensing view of the downsizing of star forming galaxies
based on cross correlating a weak lensing ($\kappa$) map with a predicted map
constructed from a redshift survey. Moderately deep and high resolution images
with Subaru/Hyper Suprime-Cam covering the 4 deg^2 DLS F2 field provide a
$\kappa$ map with 1 arcmin resolution. A dense complete redshift survey of the
F2 field including 12,705 galaxies with $R\leq20.6$ is the basis for
construction of the predicted map. The zero-lag cross-correlation between the
\kappa and predicted maps is significant at the $30\sigma$ level. The width of
the cross-correlation peak is comparable with the angular scale of rich cluster
at $z\sim0.3$, the median depth of the redshift survey. Slices of the predicted
map in $\delta{z} = 0.05$ redshift bins enable exploration of the impact of
structure as a function of redshift. The zero-lag normalised cross-correlation
has significant local maxima at redshifts coinciding with known massive X-ray
clusters. Even in slices where there are no known massive clusters, there is
significant signal in the cross-correlation originating from lower mass groups
that trace the large-scale of the universe. Spectroscopic $D_n4000$
measurements enable division of the sample into star-forming and quiescent
populations. The significance of the cross-correlation with structure
containing star-forming galaxies increases with redshift from $5\sigma$ at $z =
0.3$ to $7 \sigma$ at $z = 0.5$. The weak lensing results are consistent with
the downsizing view of galaxy evolution established on the basis of many other
independent studies.


title:
Lines and Boxes: Unmasking Dynamical Dark Matter through Correlations in
  the MeV Gamma-Ray Spectrum

abstract:
  Identifying signatures of dark matter at indirect-detection experiments is
generally more challenging for scenarios involving non-minimal dark sectors
such as Dynamical Dark Matter (DDM) than for scenarios involving a single dark
particle. This additional difficulty arises because the partitioning of the
total dark-matter abundance across an ensemble of different constituent
particles with different masses tends to "smear" the injection spectra of
photons and other cosmic-ray particles that are produced via dark-matter
annihilation or decay. As a result, the imprints of the dark sector on these
cosmic-ray flux spectra typically take the form of continuum features rather
than sharp peaks or lines. In this paper, however, we identify an unambiguous
signature of non-minimal dark sectors such as DDM which can overcome these
issues and potentially be observed at gamma-ray telescopes operating in the MeV
range. We discuss the specific situations in which this signature can arise,
and demonstrate that this signature can be exploited in order to significantly
enhance our ability to resolve the unique spectral features of DDM and other
non-minimal dark sectors at future gamma-ray facilities.


title:
Quantum Hall Edges with Hard Confinement: Exact Solution beyond
  Luttinger Liquid

abstract:
  We consider a Laughlin droplet in a confining potential which is very steep
but also weak compared to the ultra-short ranged inter-particle interactions.
We find that the eigenstates have a Jack polynomial structure, and have an
energy spectrum which is extremely different from the well-known Luttinger
liquid edge.


title: Deep Recurrent Neural Networks for Supernovae Classification

abstract:
  We apply deep recurrent neural networks, which are capable of learning
complex sequential information, to classify supernovae\footnote{Code available
at
\href{https://github.com/adammoss/supernovae}{https://github.com/adammoss/supernovae}}.
The observational time and filter fluxes are used as inputs to the network, but
since the inputs are agnostic additional data such as host galaxy information
can also be included. Using the Supernovae Photometric Classification Challenge
(SPCC) data, we find that deep networks are capable of learning about light
curves, however the performance of the network is highly sensitive to the
amount of training data. For a training size of 50\% of the representational
SPCC dataset (around $10^4$ supernovae) we obtain a type-Ia vs. non-type-Ia
classification accuracy of 94.7\%, an area under the Receiver Operating
Characteristic curve AUC of 0.986 and a SPCC figure-of-merit $F_1=0.64$. When
using only the data for the early-epoch challenge defined by the SPCC we
achieve a classification accuracy of 93.1\%, AUC of 0.977 and $F_1=0.58$,
results almost as good as with the whole light-curve. By employing
bidirectional neural networks we can acquire impressive classification results
between supernovae types -I,~-II and~-III at an accuracy of 90.4\% and AUC of
0.974. We also apply a pre-trained model to obtain classification probabilities
as a function of time, and show it can give early indications of supernovae
type. Our method is competitive with existing algorithms and has applications
for future large-scale photometric surveys.

categories: astro-ph.IM astro-ph.CO cs.LG physics.data-an


title:
Impact of Cosmic Variance on the Galaxy-Halo Connection for
  Lyman-$\alpha$ Emitters

abstract:
  In this paper we study the impact of cosmic variance and observational
uncertainties in constraining the mass and occupation fraction, $f_{\rm occ}$,
of dark matter halos hosting Ly-$\alpha$ Emitting Galaxies (LAEs) at high
redshift. To this end, we construct mock catalogs from an N-body simulation to
match the typical size of observed fields at $z=3.1$ ($\sim 1 {\rm deg^2}$). In
our model a dark matter halo with mass in the range $M_{\rm min}<M_{\mathrm
h}<M_{\rm max}$ can only host one detectable LAE at most. We proceed to explore
the parameter space determined by $M_{\rm min}$,$M_{\rm max}$ and $f_{\rm occ}$
with a Markov Chain Monte-Carlo algorithm using the angular correlation
function (ACF) and the LAEs number density as observational constraints. We
find that the preferred minimum and maximum masses in our model span a wide
range $10^{10.0}h^{-1}{\rm{M_{\odot}}}\leq M_{\rm min} \leq
10^{11.1}h^{-1}{\rm{M_{\odot}}}$ , $10^{11.0}h^{-1}{\rm{M_{\odot}}}\leq M_{\rm
max} \leq 10^{13.0}h^{-1}{\rm{M_{\odot}}}$; followed by a wide range in the
occupation fraction $0.02\leq f_{\rm occ} \leq 0.30$. As a consequence the
median mass, $M_{50}$, of all the consistent models has a large uncertainty
$M_{50} = 3.16^{+9.34}_{-2.37}\times 10^{10}$$h^{-1}{\rm{M_{\odot}}}$. However,
we find that the same individual models have a relatively tight $1\sigma$
scatter around the median mass $\Delta M_{1\sigma} = 0.55^{+0.11}_{-0.31}$ dex.
We are also able to show that \focc\ is uniquely determined by $M_{\rm min}$,
regardless of $M_{\rm max}$. We argue that upcoming large surveys covering at
least $25$ deg$^{2}$ should be able to put tighter constraints on $M_{\rm min}$
and $f_{\rm occ}$ through the LAE number density distribution width constructed
over several fields of $\sim 1$ deg$^{2}$.


title: Tall sections from non-minimal transformations

abstract:
  In previous work, we have shown that elliptic fibrations with two sections,
or Mordell-Weil rank one, can always be mapped birationally to a Weierstrass
model of a certain form, namely, the Jacobian of a $\mathbb{P}^{112}$ model.
Most constructions of elliptically fibered Calabi-Yau manifolds with two
sections have been carried out assuming that the image of this birational map
was a "minimal" Weierstrass model. In this paper, we show that for some
elliptically fibered Calabi-Yau manifolds with Mordell-Weil rank-one, the
Jacobian of the $\mathbb{P}^{112}$ model is not minimal. Said another way,
starting from a Calabi-Yau Weierstrass model, the total space must be blown up
(thereby destroying the "Calabi-Yau" property) in order to embed the model into
$\mathbb{P}^{112}$. In particular, we show that the elliptic fibrations studied
recently by Klevers and Taylor fall into this class of models.


title:
Nucleosynthesis in AGB stars traced by oxygen isotopic ratios. I -
  Determining the stellar initial mass by means of the $^{17}$O/$^{18}$O ratio

abstract:
  The aim of this paper is to investigate the $^{17}$O/$^{18}$O ratio for a
sample of AGB stars, containing M-, S- and C-type stars. These ratios are
evaluated in relation to fundamental stellar evolution parameters: the stellar
initial mass and pulsation period. Circumstellar $^{13}$C$^{16}$O,
$^{12}$C$^{17}$O and $^{12}$C$^{18}$O line observations were obtained for a
sample of nine stars with various single-dish long-wavelength facilities. Line
intensity ratios are shown to relate directly to the surface $^{17}$O/$^{18}$O
abundance ratio. Stellar evolution models predict the $^{17}$O/$^{18}$O ratio
to be a sensitive function of initial mass and to remain constant throughout
the entire TP-AGB phase for stars initially less massive than 5\,$M_{\odot}$.
This makes the measured ratio a probe of the initial stellar mass. Observed
$^{17}$O/$^{18}$O ratios are found to be well in the range predicted by stellar
evolution models that do not consider convective overshooting. From this,
accurate initial mass estimates are calculated for seven sources. For the
remaining two sources two mass solutions result, though with a larger
probability that the low-mass solution is the correct one. Finally, hints at a
possible separation between M/S- and C-type stars when comparing the
$^{17}$O/$^{18}$O ratio to the stellar pulsation period are presented.


title: The Nature of Active Galactic Nuclei with Velocity Offset Emission Lines

abstract:
  We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field
spectroscopy to probe the morphology and kinematics of the ionized gas in four
velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky
Survey. These objects possess optical emission lines that are offset in
velocity from systemic as measured from stellar absorption features. At a
resolution of ~0.18", OSIRIS allows us to distinguish which velocity offset
emission lines are produced by the motion of an AGN in a dual supermassive
black hole system, and which are produced by outflows or other kinematic
structures. In three galaxies, J1018+2941, J1055+1520 and J1346+5228, the
spectral offset of the emission lines is caused by AGN-driven outflows. In the
remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that
contains the peak of Pa$\alpha$ emission 0.2" from the center of the galaxy.
The most plausible explanation for the origin of this spatially and
kinematically offset peak is that it is a region of enhanced Pa$\alpha$
emission located at the intersection zone between the nuclear disk and the bar
of the galaxy. In all four objects, the peak of ionized gas emission is not
spatially coincident with the center of the galaxy as traced by the peak of the
near-IR continuum emission. The peaks of ionized gas emission are spatially
offset from the galaxy centers by 0.1"-0.4" (0.1-0.7 kpc). We find that the
velocity offset originates at the location of this peak of emission, and the
value of the offset can be directly measured in the velocity maps. The
emission-line ratios of these four velocity-offset AGNs can be reproduced only
with a mixture of shocks and AGN photoionization. Shocks provide a natural
explanation for the origin of the spatially and spectrally offset peaks of
ionized gas emission in these galaxies.


title: Blazar flares powered by plasmoids in relativistic reconnection

abstract:
  Powerful flares from blazars with short ($\sim$ min) variability timescales
are challenging for current models of blazar emission. Here, we present a
physically motivated ab initio model for blazar flares based on the results of
recent particle-in-cell (PIC) simulations of relativistic magnetic
reconnection. PIC simulations demonstrate that quasi-spherical plasmoids filled
with high-energy particles and magnetic fields are a self-consistent by-product
of the reconnection process. By coupling our PIC-based results (i.e., plasmoid
growth, acceleration profile, particle and magnetic content) with a kinetic
equation for the evolution of the electron distribution function we demonstrate
that relativistic reconnection in blazar jets can produce powerful flares whose
temporal and spectral properties are consistent with the observations. In
particular, our model predicts correlated synchrotron and synchrotron
self-Compton flares of duration of several hours--days powered by the largest
and slowest moving plasmoids that form in the reconnection layer. Smaller and
faster plasmoids produce flares of sub-hour duration with higher peak
luminosities than those powered by the largest plasmoids. Yet, the observed
fluence in both types of flares is similar. Multiple flares with a range of
flux-doubling timescales (minutes to several hours) observed over a longer
period of flaring activity (days or longer) may be used as a probe of the
reconnection layer's orientation and the jet's magnetization. Our model shows
that blazar flares are naturally expected as a result of magnetic reconnection
in a magnetically-dominated jet.


title: IMF shape constraints from stellar populations and dynamics from CALIFA

abstract:
  In this letter we describe how we use stellar dynamics information to
constrain the shape of the stellar IMF in a sample of 27 early-type galaxies
from the CALIFA survey. We obtain dynamical and stellar mass-to-light ratios,
$\Upsilon_\mathrm{dyn}$ and $\Upsilon_{\ast}$, over a homogenous aperture of
0.5~$R_{e}$. We use the constraint $\Upsilon_\mathrm{dyn} \ge \Upsilon_{\ast}$
to test two IMF shapes within the framework of the extended MILES stellar
population models. We rule out a single power law IMF shape for 75% of the
galaxies in our sample. Conversely, we find that a double power law IMF shape
with a varying high-mass end slope is compatible (within 1$\sigma$) with 95% of
the galaxies. We also show that dynamical and stellar IMF mismatch factors give
consistent results for the systematic variation of the IMF in these galaxies.


title: Universal behavior of coupled order parameters below three dimensions

abstract:
  We explore universal critical behavior in models with two competing order
parameters, and an O(N)+O(M) symmetry for dimensions $d \leq 3$. In d=3, there
is always exactly one stable Renormalization Group fixed point, corresponding
to bicritical or tetracritical behavior. Employing novel, pseudo-spectral
techniques to solve functional Renormalization Group equations in a
two-dimensional field space, we uncover a more intricate structure of fixed
points in d<3, where two additional bicritical fixed points play a role.
Towards d=2, we discover ranges of N=M with several simultaneously stable fixed
points, indicating the coexistence of several universality classes.


title: Ultra-deep Ks-band Imaging of the Hubble Frontier Fields

abstract:
  We present an overview of the "KIFF" project, which provides ultra-deep
Ks-band imaging of all six of the Hubble Frontier Fields clusters Abell 2744,
MACS-0416, Abell S1063, Abell 370, MACS-0717 and MACS-1149. All of these fields
have recently been observed with large allocations of Directors' Discretionary
Time with the HST and Spitzer telescopes covering 0.4 < lambda < 1.6 microns
and 3.6--4.5 microns, respectively. VLT/HAWK-I integrations of the first four
fields reach 5-sigma limiting depths of Ks~26.0 (AB, point sources) and have
excellent image quality (FWHM ~ 0."4). Shorter Keck/MOSFIRE integrations of the
MACS-0717 (MACS-1149) field better observable in the north reach limiting
depths Ks=25.5 (25.1) with seeing FWHM ~0."4 (0."5). In all cases the Ks-band
mosaics cover the primary cluster and parallel HST/ACS+WFC3 fields. The total
area of the Ks-band coverage is 490 arcmin^2. The Ks-band at 2.2 microns
crucially fills the gap between the reddest HST filter (1.6 micron ~ H-band)
and the IRAC 3.6 micron passband. While reaching the full depths of the
space-based imaging is not currently feasible from the ground, the deep Ks-band
images provide important constraints on both the redshifts and the stellar
population properties of galaxies extending well below the characteristic
stellar mass across most of the age of the universe, down to, and including,
the redshifts of the targeted galaxy clusters (z < 0.5).


title:
On the Boltzmann Equation with Stochastic Kinetic Transport: Global
  Existence of Renormalized Martingale Solutions

abstract:
  This article studies the Cauchy problem for the Boltzmann equation with
stochastic kinetic transport. Under a cut-off assumption on the collision
kernel and a coloring hypothesis for the noise coefficients, we prove the
global existence of renormalized (in the sense of DiPerna/Lions) martingale
solutions to the Boltzmann equation for large initial data with finite mass,
energy, and entropy. Our analysis includes a detailed study of weak martingale
solutions to a class of linear stochastic kinetic equations. This study
includes a criterion for renormalization, the weak closedness of the solution
set, and tightness of velocity averages in $L^1$.


title:
Early Quenching of Massive Protocluster Galaxies Around z=2.2 Radio
  Galaxies

abstract:
  Radio galaxies are among the most massive galaxies in the high redshift
universe and are known to often lie in protocluster environments. We have
studied the fields of seven z = 2.2 radio galaxies with HAWK-I narrow-band and
broad-band imaging in order to map out their environment using Halpha emitters
(HAEs). The results are compared to the blank field HAE survey HiZELS. All of
the radio galaxy fields are overdense in HAEs relative to a typical HiZELS
field of the same area and four of the seven are richer than all except one of
65 essentially random HiZELS subfields of the same size. The star formation
rates of the massive HAEs are lower than those necessary to have formed their
stellar population in the preceding Gyr - indicating that these galaxies are
likely to have formed the bulk of their stars at higher redshifts, and are
starting to quench.


title:
Heat-bath Configuration Interaction: An efficient selected CI algorithm
  inspired by heat-bath sampling

abstract:
  We introduce a new selected configuration interaction plus perturbation
theory algorithm that is based on a deterministic analog of our recent
efficient heat-bath sampling algorithm. This Heat-bath Configuration
Interaction (HCI) algorithm makes use of two parameters that control the
tradeoff between speed and accuracy, one which controls the selection of
determinants to add to a variational wavefunction, and one which controls the
the selection of determinants used to compute the perturbative correction to
the variational energy. We show that HCI provides an accurate treatment of both
static and dynamic correlation by computing the potential energy curve of the
multireference carbon dimer in the cc-pVDZ basis. We then demonstrate the speed
and accuracy of HCI by recovering the full configuration interaction energy of
both the carbon dimer in the cc-pVTZ basis and the strongly-correlated chromium
dimer in the Ahlrichs VDZ basis, correlating all electrons, to an accuracy of
better than 1 mHa, in just a few minutes on a single core. These systems have
full variational spaces of 3x10^14 and 2x10^22 determinants respectively.


title:
Rigorous ab initio quantum embedding for quantum chemistry using Green's
  function theory: screened interaction, non-local self-energy relaxation,
  orbital basis, and chemical accuracy

abstract:
  We present a detailed discussion of self-energy embedding theory (SEET) which
is a quantum embedding scheme allowing us to describe a chosen subsystem very
accurately while keeping the description of the environment at a lower cost. We
apply SEET to molecular examples where commonly our chosen subsystem is made
out of a set of strongly correlated orbitals while the weakly correlated
orbitals constitute an environment. Such a self-energy separation is very
general and to make this procedure applicable to multiple systems a detailed
and practical procedure for the evaluation of the system and environment
self-energy is necessary. We list all the intricacies for one of the possible
procedures while focusing our discussion on many practical implementation
aspects such as the choice of best orbital basis, impurity solver, and many
steps necessary to reach chemical accuracy. Finally, on a set of carefully
chosen molecular examples, we demonstrate that SEET which is a controlled,
systematically improvable Green's function method can be as accurate as
established wavefunction quantum chemistry methods.


title:
Relativistic correction to gluon fragmentation function into
  pseudoscalar quarkonium

abstract:
  Inspired by the recent measurements of the $\eta_c$ meson production at LHC,
we investigate the relativistic correction effect for the fragmentation
function of the gluon into $\eta_c$, which constitutes the crucial
nonperturbative elements to understand $\eta_c$ production at high $p_T$.
Employing three distinct methods, we calculate the leading relativistic
correction to the $g\to\eta_c$ fragmentation function in the NRQCD
factorization framework, as well as verify the existing NLO result for the
$c\to \eta_c$ fragmentation function. We also study the evolution behavior of
these fragmentation functions with the aid of DGLAP equation.


title: The Rapid Transient Surveyor

abstract:
  The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence
adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will
uniquely address the need for high-acuity and sensitive near-infrared spectral
follow-up observations of tens of thousands of objects in mere months by
combining an excellent observing site, unmatched robotic observational
efficiency, and an AO system that significantly increases both sensitivity and
spatial resolving power. We will initially use RTS to obtain the infrared
spectra of ~4,000 Type Ia supernovae identified by the Asteroid
Terrestrial-Impact Last Alert System over a two year period that will be
crucial to precisely measuring distances and mapping the distribution of dark
matter in the z < 0.1 universe. RTS will comprise an upgraded version of the
Robo-AO laser AO system and will respond quickly to target-of-opportunity
events, minimizing the time between discovery and characterization. RTS will
acquire simultaneous-multicolor images with an acuity of 0.07-0.10" across the
entire visible spectrum (20% i'-band Strehl in median conditions) and <0.16" in
the near infrared, and will detect companions at 0.5" at contrast ratio of
~500. The system will include a high-efficiency prism integral field unit
spectrograph: R = 70-140 over a total bandpass of 840-1830 nm with an 8.7" by
6.0" field of view (0.15" spaxels). The AO correction boosts the infrared
point-source sensitivity of the spectrograph against the sky background by a
factor of seven for faint targets, giving the UH 2.2-m the H-band sensitivity
of a 5.7-m telescope without AO.


title:
Device and Circuit Interaction Analysis of Stochastic Behaviors in
  Cross-Point RRAM Arrays

abstract:
  Stochastic behaviors of resistive random access memory (RRAM) play an
important role in the design of cross-point memory arrays. A Monte Carlo
compact model of oxide RRAM is developed and calibrated with experiments on
various device stack configurations. With Monte Carlo SPICE simulations, we
show that an increase in array size and interconnect wire resistance will
statistically deteriorate write functionality. Write failure probability (WFP)
has an exponential dependency on device uniformity and supply voltage (VDD),
and the array bias scheme is a key knob. Lowering array VDD leads to higher
effective energy consumption (EEC) due to the increase in WFP when the
variation statistics are included in the analysis. Random-access simulations
indicate that data sparsity statistically benefits write functionality and
energy consumption. Finally, we show that a pseudo-sub-array topology with
uniformly distributed pre-forming cells in the pristine high resistance state
is able to reduce both WFP and EEC, enabling higher net capacity for memory
circuits due to improved variation tolerance.


title: Closure of the Operator Product Expansion in the Non-Unitary Bootstrap

abstract:
  We use the numerical conformal bootstrap in two dimensions to search for
finite, closed sub-algebras of the operator product expansion (OPE), without
assuming unitarity. We find the minimal models as special cases, as well as
additional lines of solutions that can be understood in the Coulomb gas
formalism. All the solutions we find that contain the vacuum in the operator
algebra are cases where the external operators of the bootstrap equation are
degenerate operators, and we argue that this follows analytically from the
expressions in arXiv:1202.4698 for the crossing matrices of Virasoro conformal
blocks. Our numerical analysis is a special case of the "Gliozzi" bootstrap
method, and provides a simpler setting in which to study technical challenges
with the method.
  In the supplementary material, we provide a Mathematica notebook that
automates the calculation of the crossing matrices and OPE coefficients for
degenerate operators using the formulae of Dotsenko and Fateev.


title:
Simulation of a low-background proton detector for studying low-energy
  resonances relevant in thermonuclear reactions

abstract:
  A new detector is being developed at the National Superconducting Cyclotron
Laboratory (NSCL) to measure low energy charged-particles from beta-delayed
particle emission. These low energy particles are very important for nuclear
astrophysics studies. The use of a gaseous system instead of a solid state
detector decreases the sensitivity to betas while keeping high efficiency for
higher mass charged particles like protons or alphas. This low sensitivity to
betas minimizes their contribution to the background down to 150 keV. A
detailed simulation tool based on \textsc{Geant4} has been developed for this
future detector.


title: From $e$ to $\pi$: Derivation of the Wallis formula for $\pi$ from $e$

abstract:
  In this Note, we start off with the primary representation of e and from
there present an elementary short proof for the Wallis formula for $\pi$.


title:
LSTMVis: A Tool for Visual Analysis of Hidden State Dynamics in
  Recurrent Neural Networks

abstract:
  Recurrent neural networks, and in particular long short-term memory (LSTM)
networks, are a remarkably effective tool for sequence modeling that learn a
dense black-box hidden representation of their sequential input. Researchers
interested in better understanding these models have studied the changes in
hidden state representations over time and noticed some interpretable patterns
but also significant noise. In this work, we present LSTMVIS, a visual analysis
tool for recurrent neural networks with a focus on understanding these hidden
state dynamics. The tool allows users to select a hypothesis input range to
focus on local state changes, to match these states changes to similar patterns
in a large data set, and to align these results with structural annotations
from their domain. We show several use cases of the tool for analyzing specific
hidden state properties on dataset containing nesting, phrase structure, and
chord progressions, and demonstrate how the tool can be used to isolate
patterns for further statistical analysis. We characterize the domain, the
different stakeholders, and their goals and tasks.


title:
Teleparallel Conformal Killing Vector Fields of LRS Bianchi Type V
  Spacetimes in Teleparallel Gravity

abstract:
  The aim of this paper is to explore teleparallel conformal Killing vector
fields (CKVFs) of locally rotationally symmetric (LRS) Bianchi type V
spacetimes in the context of teleparallel gravity and compare the obtained
results with those of general relativity. The general solution of teleparallel
conformal Killing's equations is found in terms of some unknown functions of t
and x , along with a set of integrability conditions. The integrability
conditions are solved in some particular cases to get the final form of
teleparallel CKVFs. It is observed that the LRS Bianchi type V spacetimes admit
proper teleparallel CKVF in only one case, while in remaining cases the
teleparallel CKVFs reduce to teleparallel Killing vector fields (KVFs).
Moreover, it is shown that the LRS Bianchi type V spacetimes do not admit any
proper teleparallel homothetic vector field (HVF).


title: PPM: A Privacy Prediction Model for Online Social Networks

abstract:
  Online Social Networks (OSNs) have come to play an increasingly important
role in our social lives, and their inherent privacy problems have become a
major concern for users. Can we assist consumers in their privacy
decision-making practices, for example by predicting their preferences and
giving them personalized advice? To this end, we introduce PPM: a Privacy
Prediction Model, rooted in psychological principles, which can be used to give
users personalized advice regarding their privacy decision-making practices.
Using this model, we study psychological variables that are known to affect
users' disclosure behavior: the trustworthiness of the requester/information
audience, the sharing tendency of the receiver/information holder, the
sensitivity of the requested/shared information, the appropriateness of the
request/sharing activities, as well as several more traditional contextual
factors.


title:
Stochastic differential equations: loss of the Markov property by
  multiplicative noise

abstract:
  The solutions of SDEs with multiplicative noise are not Markovian. On a
coarse-grained time scale they still are, but only in the "anti-Ito" case. This
allows a simple computation of the most likely path. Any density peak moves
along such a path, and its shape evolves according to further analytical
formulas. This even provides some new insights into the asymptotic densities
for large times, e.g. the criterion for attaining a quiescent steady state.


title: The cocycle identity holds under stopping

abstract:
  In recent work of the authors, it was shown how to use any finite quantum
stop time to stop the CCR flow and its strongly continuous isometric cocycles
(Q. J. Math. 65:1145-1164, 2014). The stopped cocycle was shown to satisfy a
stopped form of the cocycle identity, valid for deterministic increments of the
time used for stopping. Here, a generalisation of this identity is obtained,
where both cocycle parameters are replaced with finite quantum stop times.


title: Chiral quantum optics with V-level atoms and coherent quantum feedback

abstract:
  We study the dissipative dynamics of an atom in a V-level configuration
driven by lasers and coupled to a semi-infinite waveguide. The coupling to the
waveguide is chiral, in that each transition interacts only with the modes
propagating in a given direction, and this direction is opposite for the two
transitions. The waveguide is terminated by a mirror which coherently feeds the
photon stream emitted by one transition back to the atom. First, we are
interested in the dynamics of the atom in the Markovian limit where the
time-delay in the feedback is negligible. Specifically, we study the conditions
under which the atom evolves towards a pure "dark" stationary state, where the
photons emitted by both transitions interfere destructively thanks to the
coherent feedback, and the overall emission vanishes. This is a single-atom
analog of the quantum dimer, where a pair of laser-driven two-level atoms is
coupled to a unidirectional waveguide and dissipates towards a pure entangled
dark state. Our setup should be feasible with current state-of-the-art
experiments. Second, we extend our study to non-Markovian regimes and
investigate the effect of the feedback retardation on the steady-state.


title: Efficient Analog Circuits for Boolean Satisfiability

abstract:
  Efficient solutions to NP-complete problems would significantly benefit both
science and industry. However, such problems are intractable on digital
computers based on the von Neumann architecture, thus creating the need for
alternative solutions to tackle such problems. Recently, a deterministic,
continuous-time dynamical system (CTDS) was proposed (Nat.Phys. {\bf 7}(12),
966 (2011)) to solve a representative NP-complete problem, Boolean
Satisfiability (SAT). This solver shows polynomial analog time-complexity on
even the hardest benchmark $k$-SAT ($k \geq 3$) formulas, but at an energy cost
through exponentially driven auxiliary variables. This paper presents a novel
analog hardware SAT solver, AC-SAT, implementing the CTDS via incorporating
novel, analog circuit design ideas. AC-SAT is intended to be used as a
co-processor and is programmable for handling different problem specifications.
It is especially effective for solving hard $k$-SAT problem instances that are
challenging for algorithms running on digital machines. Furthermore, with its
modular design, AC-SAT can readily be extended to solve larger size problems,
while the size of the circuit grows linearly with the product of the number of
variables and number of clauses. The circuit is designed and simulated based on
a 32nm CMOS technology. SPICE simulation results show speedup factors of
$\sim$10$^4$ on even the hardest 3-SAT problems, when compared with a
state-of-the-art SAT solver on digital computers. As an example, for hard
problems with $N=50$ variables and $M=212$ clauses, solutions are found within
from a few $ns$ to a few hundred $ns$.


title:
Detection of Explosives by Using a Neutron Source Based on a Proton
  Linac

abstract:
  The paper considers an opportunity of detecting explosives by using radiation
capture of a neutron with nitrogen nucleus. Proton LINAC is offered as the
neutron source with the following parameters: proton energy five Mega electron
Volts , beam pulse current one and seven-tenths milliampere, duration of the
current pulse two hundreds microseconds, repetition rate fifty Hertz. The
reaction in which neutrons are formed is lithium (p,n) beryllium. It is shown
that this neutron source will have the intensity of ten to the twelfth degree
neutron per second that will allow one to detect explosives of the size of a
tennis ball.


title: On singular generalized Berwald spacetimes and the equivalence principle

abstract:
  The notion of singular generalized Finsler spacetime and singular generalized
Berwald spacetime are introduced and their relevance for the description of
classical gravity discussed. A method to construct examples of such generalized
Berwald spacetimes is sketched. The method is applied at two different levels
of generality. First, a class of flat, singular generalized Berwald spacetimes
is obtained. Then in an attempt of further generalization, a class of non-flat
generalized Berwald spacetimes is presented and the associated Einstein field
equations are discussed. In this context, an argument in favour of a small
value of the cosmological constant is given. The physical significance of the
models is briefly discussed in the last section.


title:
NN-grams: Unifying neural network and n-gram language models for Speech
  Recognition

abstract:
  We present NN-grams, a novel, hybrid language model integrating n-grams and
neural networks (NN) for speech recognition. The model takes as input both word
histories as well as n-gram counts. Thus, it combines the memorization capacity
and scalability of an n-gram model with the generalization ability of neural
networks. We report experiments where the model is trained on 26B words.
NN-grams are efficient at run-time since they do not include an output soft-max
layer. The model is trained using noise contrastive estimation (NCE), an
approach that transforms the estimation problem of neural networks into one of
binary classification between data samples and noise samples. We present
results with noise samples derived from either an n-gram distribution or from
speech recognition lattices. NN-grams outperforms an n-gram model on an Italian
speech recognition dictation task.


title:
Comment on "Atmospheric ionization by high-fluence, hard spectrum solar
  proton events and their probable appearance in the ice core archive" by A.L.
  Melott et al

abstract:
  Melott et al. [2016] suggest that individual solar proton events (SPEs) are
detectable as nitrate ion spikes in ice cores. They use the high fluence, high
energy (hard spectrum) SPE of 23 February 1956 to calculate an enhancement of
HNO3 from the surface to 46 km that is equivalent to a ~120 ng cm-2 nitrate ion
spike observed in the GISP2H ice core. The Melott et al. [2016] approach is
fundamentally flawed, since it considers only the absolute column burden of
SPE-produced nitrate and not the pre-existing nitrate in the stratosphere.
Modeling studies supported by extensive observations [Duderstadt et al., 2014,
2016, and this comment] show background HNO3 in the lower and middle
stratosphere equivalent to 2000 to 3000 ng cm-2 nitrate. These high levels of
background nitrate must also be included when estimating SPE enhancements to
the deposition of nitrate ions that might eventually be preserved in an ice
core. The 1956 SPE results in less than a 5% increase in the column burden of
atmospheric HNO3, not large enough to explain the nitrate spike seen in the
GISP2H ice core. Even extreme SPE enhancements cannot explain nitrate peaks
(typically hundreds of percent increases) observed in the ice record
[Duderstadt et al., 2016]. Realistic mechanisms linking nitrate ions in ice
cores to SPEs have not been established. It is time to move the search for
indicators of SPEs away from nitrate ions: Nitrate ions cannot be used as
proxies for individual SPEs in the ice core record.

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


title:
Quantum impurity in a Luttinger liquid: Exact solution of the
  Kane-Fisher model

abstract:
  A Luttinger Liquid coupled to a quantum impurity describes a large number of
physical systems. The Hamiltonian consists of left- and right-moving fermions
interacting among themselves via a density-density coupling and scattering off
a localised transmitting and reflecting impurity. We solve exactly the
Hamiltonian by means of an incoming-outgoing scattering Bethe basis which
properly incorporates all scattering processes. A related model, the
Weak-Tunnelling model, wherein the impurity is replaced by a tunnel junction,
is solved by the same method. The consistency of the construction is
established through a generalised Yang-Baxter relation. Periodic boundary
conditions are imposed and the resulting Bethe Ansatz equations are derived by
means of the Off Diagonal Bethe Ansatz approach. We derive the spectrum of the
model for all coupling constant regimes and calculate the impurity free energy.
We discuss the low energy behaviour of the systems for both repulsive and
attractive interactions.


abstract:
  The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to
measure 21 cm emission from the primordial intergalactic medium (IGM)
throughout cosmic reionization ($z=6-12$), and to explore earlier epochs of our
Cosmic Dawn ($z\sim30$). During these epochs, early stars and black holes
heated and ionized the IGM, introducing fluctuations in 21 cm emission. HERA is
designed to characterize the evolution of the 21 cm power spectrum to constrain
the timing and morphology of reionization, the properties of the first
galaxies, the evolution of large-scale structure, and the early sources of
heating. The full HERA instrument will be a 350-element interferometer in South
Africa consisting of 14-m parabolic dishes observing from 50 to 250 MHz.
Currently, 19 dishes have been deployed on site and the next 18 are under
construction. HERA has been designated as an SKA Precursor instrument.
  In this paper, we summarize HERA's scientific context and provide forecasts
for its key science results. After reviewing the current state of the art in
foreground mitigation, we use the delay-spectrum technique to motivate
high-level performance requirements for the HERA instrument. Next, we present
the HERA instrument design, along with the subsystem specifications that ensure
that HERA meets its performance requirements. Finally, we summarize the
schedule and status of the project. We conclude by suggesting that, given the
realities of foreground contamination, current-generation 21 cm instruments are
approaching their sensitivity limits. HERA is designed to bring both the
sensitivity and the precision to deliver its primary science on the basis of
proven foreground filtering techniques, while developing new subtraction
techniques to unlock new capabilities. The result will be a major step toward
realizing the widely recognized scientific potential of 21 cm cosmology.


title: A stability result using the matrix norm to bound the permanent

abstract:
  We prove a stability version of a general result that bounds the permanent of
a matrix in terms of its operator norm. More specifically, suppose $A$ is an $n
\times n$ matrix over $\mathbb{C}$ (resp. $\mathbb{R}$), and let $\mathcal{P}$
denote the set of $n \times n$ matrices over $\mathbb{C}$ (resp. $\mathbb{R}$)
that can be written as a permutation matrix times a unitary diagonal matrix.
Then it is known that the permanent of $A$ satisfies $|\text{perm}(A)| \leq
\Vert A \Vert_{2} ^n$ with equality iff $A/ \Vert A \Vert_{2} \in \mathcal{P}$
(where $\Vert A \Vert_2$ is the operator $2$-norm of $A$). We show a stability
version of this result asserting that unless $A$ is very close (in a particular
sense) to one of these extremal matrices, its permanent is exponentially
smaller (as a function of $n$) than $\Vert A \Vert_2 ^n$. In particular, for
any fixed $\alpha, \beta > 0$, we show that $|\text{perm}(A)|$ is exponentially
smaller than $\Vert A \Vert_2 ^n$ unless all but at most $\alpha n$ rows
contain entries of modulus at least $\Vert A \Vert_2 (1 - \beta)$.


title: Beam loading in the bubble regime in plasmas with hollow channels

abstract:
  Based on the already existing analytical theory of the strongly-nonlinear
wakefield (which is called "bubble") in transversely inhomogeneous plasmas, we
study particular behavior of non-loaded (empty) bubbles and bubbles with
accelerated bunches. We obtain an analytical expression for the shape of a
non-loaded bubble in a general case and verify it with particle-in-cell (PIC)
simulations. We derive a method of calculation of the acceleration efficiency
for arbitrary accelerated bunches. The influence of flat-top electron bunches
on the shape of a bubble is studied. It is also shown that it is possible to
achieve acceleration in a homogeneous longitudinal electric field by the
adjustment of the longitudinal density profile of the accelerated electron
bunch. The predictions of the model are verified by 3D PIC simulations and are
in a good agreement with them.


title:
An uncertainty principle and lower bounds for the Dirichlet Laplacian on
  graphs

abstract:
  We prove a quantitative uncertainty principle at low energies for the
Laplacian on fairly general weighted graphs with a uniform explicit control of
the constants in terms of geometric quantities. A major step consists in
establishing lower bounds for Dirichlet eigenvalues in terms of the geometry.


title:
Coleman-Weinberg symmetry breaking in $SU(8)$ induced by a third rank
  antisymmetric tensor scalar field II: the fermion spectrum

abstract:
  We continue our study of Coleman-Weinberg symmetry breaking induced by a
third rank antisymmetric tensor scalar, in the context of the $SU(8)$ model we
proposed earlier. We focus in this paper on qualitative features that will
determine whether the model can make contact with the observed particle
spectrum. We discuss the mechanism for giving the spin $\frac{3}{2}$ field a
mass by the BEH mechanism, and analyze the remaining massless spin
$\frac{1}{2}$ fermions, the global chiral symmetries, and the running couplings
after symmetry breaking. We note that the smallest gluon mass matrix eigenvalue
has an eigenvector suggestive of $U(1)_{B-L}$, and conjecture that the theory
runs to an infrared fixed point at which there is a massless gluon with 3 to -1
ratios in generator components. Assuming this, we discuss a mechanism for
making contact with the standard model, based on a conjectured asymmetric
breaking of $Sp(4)$ to $SU(2)$ subgroups, one of which is the electroweak
$SU(2)$, and the other of which is a "technicolor" group that binds the
original $SU(8)$ model fermions, which play the role of "preons", into
composites. Quarks can emerge as 5 preon composites and leptons as 3 preon
composites, with consequent stability of the proton against decay to a single
lepton plus a meson. A composite Higgs boson can emerge as a two preon
composite. Since anomaly matching for the relevant conserved global symmetry
current is not obeyed by three fermion families, emergence of three composite
families requires formation of a Goldstone boson with quantum numbers matching
this current, which can be a light dark matter candidate.


title: Maximal Newton points and the quantum Bruhat graph

abstract:
  We discuss a surprising relationship between the partially ordered set of
Newton points associated to an affine Schubert cell and the quantum cohomology
of the complex flag variety. The main theorem provides a combinatorial formula
for the unique maximum element in this poset in terms of paths in the quantum
Bruhat graph, whose vertices are indexed by elements in the finite Weyl group.
Key to establishing this connection is the fact that paths in the quantum
Bruhat graph encode saturated chains in the strong Bruhat order on the affine
Weyl group. This correspondence is also fundamental in the work of Lam and
Shimozono establishing Peterson's isomorphism between the quantum cohomology of
the finite flag variety and the homology of the affine Grassmannian. One
important geometric application of the present work is an inequality which
provides a necessary condition for non-emptiness of certain affine
Deligne-Lusztig varieties in the affine flag variety.


title: Wireless Application Protocol Architecture Overview

abstract:
  WAP protocol is a set of communication protocols application environment and
wireless devices. WAP model more than a WAP gateway. Suitable for wireless
communication environment.


title:
Performance Analysis and Scaling Law of MRC/MRT Relaying with CSI Error
  in Massive MIMO Systems

abstract:
  This work provides a comprehensive scaling law and performance analysis for
multi-user massive MIMO relay networks, where the relay is equipped with
massive antennas and uses MRC/MRT for low-complexity processing. CSI error is
considered. First, a sum-rate lower bound is derived which manifests the effect
of system parameters including the numbers of relay antennas and users, the CSI
quality, and the transmit powers of the sources and the relay. Via a general
scaling model on the system parameters with respect to the relay antenna
number, the asymptotic scaling law of the SINR as a function of the parameter
scalings is obtained, which shows quantitatively the tradeoff between the
network parameters and their effect on the network performance. In addition, a
sufficient condition on the parameter scalings for the SINR to be
asymptotically deterministic is given, which covers existing studies on such
analysis as special cases. Then, the scenario where the SINR increases linearly
with the relay antenna number is studied. The sufficient and necessary
condition on the parameter scaling for this scenario is proved. It is shown
that in this case, the interference power is not asymptotically deterministic,
then its distribution is derived, based on which the outage probability and
average bit error rate of the relay network are analysed.


title:
CUNI System for WMT16 Automatic Post-Editing and Multimodal Translation
  Tasks

abstract:
  Neural sequence to sequence learning recently became a very promising
paradigm in machine translation, achieving competitive results with statistical
phrase-based systems. In this system description paper, we attempt to utilize
several recently published methods used for neural sequential learning in order
to build systems for WMT 2016 shared tasks of Automatic Post-Editing and
Multimodal Machine Translation.