title: Driven interfaces: from flow to creep through model reduction

abstract:
  The response of spatially extended systems to a force leading their steady
state out of equilibrium is strongly affected by the presence of disorder. We
focus on the mean velocity induced by a constant force applied on
one-dimensional interfaces. In the absence of disorder, the velocity is linear
in the force. In the presence of disorder, it is widely admitted, as well as
experimentally and numerically verified, that the velocity presents a stretched
exponential dependence in the force (the so-called 'creep law'), which is out
of reach of linear response, or more generically of direct perturbative
expansions at small force. In dimension one, there is no exact analytical
derivation of such a law, even from a theoretical physical point of view. We
propose an effective model with two degrees of freedom, constructed from the
full spatially extended model, that captures many aspects of the creep
phenomenology. It provides a justification of the creep law form of the
velocity-force characteristics, in a quasistatic approximation. It allows,
moreover, to capture the non-trivial effects of short-range correlations in the
disorder, which govern the low-temperature asymptotics. It enables us to
establish a phase diagram where the creep law manifests itself in the vicinity
of the origin in the force--system-size--temperature coordinates. Conjointly,
we characterise the crossover between the creep regime and a linear-response
regime that arises due to finite system size.


title:
The Projective Parabolic Geometry of Riemannian, K\"ahler and
  Quaternion-K\"ahler Metrics

abstract:
  We present a uniform framework generalising and extending the classical
theories of projective differential geometry, c-projective geometry, and almost
quaternionic geometry. Such geometries, which we call \emph{projective
parabolic geometries}, are abelian parabolic geometries whose flat model is an
R-space $G\cdot\mathfrak{p}$ in the infinitesimal isotropy representation
$\mathbb{W}$ of a larger self-dual symmetric R-space $H\cdot\mathfrak{q}$. We
also give a classification of projective parabolic geometries with
$H\cdot\mathfrak{q}$ irreducible which, in addition to the aforementioned
classical geometries, includes a geometry modelled on the Cayley plane
$\mathbb{OP}^2$ and conformal geometries of various signatures.
  The larger R-space $H\cdot\mathfrak{q}$ severely restricts the Lie-algebraic
structure of a projective parabolic geometry. In particular, by exploiting a
Jordan algebra structure on $\mathbb{W}$, we obtain a $\mathbb{Z}^2$-grading on
the Lie algebra of $H$ in which we have tight control over Lie brackets between
various summands. This allows us to generalise known results from the classical
theories. For example, which riemannian metrics are compatible with the
underlying geometry is controlled by the first BGG operator associated to
$\mathbb{W}$.
  In the final chapter, we describe projective parabolic geometries admitting a
$2$-dimensional family of compatible metrics. This is the usual setting for the
classical projective structures; we find that many results which hold in these
settings carry over with little to no changes in the general case.


title: An observation on Asanov's Unicorn metrics

abstract:
  Finsleroid-Finsler metrics form an important class of singular (y-local)
Finslerian metrics. They were introduced by G. S. Asanov in 2006. As a special
case Asanov produced examples of Landsberg spaces of dimension at least three
that are not of Berwald type. These are called Unicorns [5]. The existence of
regular (y - global) Landsberg metrics that are not of Berwald type is an open
problem up to this day. In this paper we prove that Asanov's Unicorns belong to
the class of generalized Berwald manifolds. More precisely we prove the
following theorems: a Finsleroid-Finsler space is a generalized Berwald space
if and only if the Finsleroid charge is constant. Especially a
Finsleroid-Finsler space is a Landsberg space if and only if it is a
generalized Berwald manifold with a semi-symmetric compatible linear
connection.


title:
Controlling Morphology-Structure of Gold Tiny Particles, Nanoparticles
  and Particles at Different Pulse Rates and Pulse Polarity

abstract:
  Controlling the shape and structure of metallic colloids is an important
topic. Here, different morphology-structures of colloidal gold particles are
investigated with different process parameters in a pulse-based electron-photon
and solution interface process. Different tiny-shaped particles of gold
developed for different packets of supplied nano-energy as per set pulse OFF to
ON time. Depending on the set ratios of pulse OFF to ON times and pulse
polarity, packets of nano-energy bind transitional state gold atoms resting at
electronically-flat solution surface that is controlled in their own shapes.
Tiny particles of joined triangular shape in each case developed under set
tuned ratio of bipolar pulses OFF to ON time. At unipolar pulse, tiny particles
in triangular shape developed directly. When the ratio of bipolar pulse OFF to
ON time was large, distorted shapes of the particles developed. Geometrical
shapes of particles developed under significant ratios of pulse OFF to ON
times. When the ratio of bipolar pulse OFF to ON time was 3, particles
developed in low aspect ratio. But under the fraction of this ratio, particles
tend to develop in high aspect ratio. For longer pulse ON time, structures of
smooth elements get developed in width less than inter-spacing distance and
forcing energy of travelling photons along the interface to flatten them
further. Morphology and structure of tiny particles, nanoparticles and
particles are discussed for different process parameters opening multiple
routes for materials research and their counterparts. This is the overall
attained orientation of electrons in elongated atoms forming colloidal
particles of different size and shape maintaining the certain color of their
solution under sunlight.


title: Higgs bundles over elliptic curves for real groups

abstract:
  We study topologically trivial $G$-Higgs bundles over an elliptic curve $X$
when the structure group $G$ is a connected real form of a complex semisimple
Lie group $G^{\mathbb{C}}$. We achieve a description of their (reduced) moduli
space, the associated Hitchin fibration and the finite morphism to the moduli
space of $G^{\mathbb{C}}$-Higgs bundles.


title: Optimizations of GaAs Nanowire Solar Cells

abstract:
  The efficiency of GaAs nanowire solar cells can be significantly improved
without any new processing steps or material requirements. We report coupled
optoelectronic simulations of a GaAs nanowire (NW) solar cell with vertical
p-i-n junction and high band gap AlInP passivating shell. Our
frequency-dependent model facilitates calculation of quantum efficiency for the
first time in NW solar cells. For passivated NWs, we find that short-wavelength
photons can be most effectively harnessed by using a thin emitter while
long-wavelength photons are best utilized by extending the intrinsic region to
the nanowire/substrate interface, and using the substrate as a base. These two
easily implemented changes, coupled with the increase of NW height to 3.5 um
with realistic surface recombination in the presence of a passivation shell,
result in a NW solar cell with greater than 19% efficiency.


title: On generalizations of Boehmian space and Hartley transform

abstract:
  Boehmians are quotients of sequences which are constructed by using a set of
axioms. In particular, one of these axioms states that the set $S$ from which
the {\it denominator} sequences are formed should be a commutative semigroup
with respect to a binary operation. In this paper, we introduce a
generalization of abstract Boehmian space, called $G$-Boehmian space, in which
$S$ is not necessarily a commutative semigroup. Next, we provide an example of
a $G$-Boehmian space and we discuss an extension of the Hartley transform on
it. Finally, we compare the Hartley transform in this paper with the existing
works on Hartley transform of Boehmians.


title: High perfomance selectable value transportable high dc Voltage standard

abstract:
  At National Institute of Metrological Research (INRIM), a selectable-value
Transportable High dcVoltage Standard (THVS) operating in the range from 10 V
to 100 V in steps of 10 V, was developed. This Standard was built to cover the
lack of high level dc Voltage Standards at voltages higher than 10 V to employ
as laboratory (local) or travelling Standards for Inter-Laboratory Comparisons
(ILCs). A ground-mobile electronic technique was used to enhance the accuracy
of the THVS at the higher values. The THVS shows better noise, better
short-mid-term stability than top level dc Voltage and multifunction
calibrators (MFCs) and better suitability and insensibility to be transported
than these instruments. The project is extensible to 1000 V.


title:
Self-diffusion constants of non-colliding interacting Brownian motions
  in one spatial dimension

abstract:
  We prove that self-diffusion constants of interacting Brownian particles in $
\mathbb{R}$ always vanish if the particles do not collide with each other. We
represent self-diffusion constants by additive functionals of reversible Markov
processes as obtained in O. 1998.


title: Moment matching for bilinear systems with nice selections

abstract:
  The paper develops a method for model reduction of bilinear control systems.
It leans upon the observation that the input-output map of a bilinear system
has a particularly simple Fliess series expansion. Subsequently, a model
reduction algorithm is formulated such that the coefficients of Fliess series
expansion for the original and reduced systems match up to certain predefined
sets - nice selections. Algorithms for computing matrix representations of
unobservability and reachability spaces complying with a nice selection are
provided. Subsequently, they are used for calculating a partial realization of
a given input-output map.


title: Every planar graph is $1$-defective $(9,2)$-paintable

abstract:
  Assume $L$ is a $k$-list assignment of a graph $G$. A $d$-defective $m$-fold
$L$-colouring $\phi$ of $G$ assigns to each vertex $v$ a set $\phi(v)$ of $m$
colours, so that $\phi(v) \subseteq L(v)$ for each vertex $v$, and for each
colour $i$, the set $\{v: i \in \phi(v)\}$ induces a subgraph of maximum degree
at most $d$. In this paper, we consider on-line list $d$-defective $m$-fold
colouring of graphs, where the list assignment $L$ is given on-line, and the
colouring is constructed on-line. To be precise, the $d$-defective
$(k,m)$-painting game on a graph $G$ is played by two players: Lister and
Painter. Initially, each vertex has $k$ tokens and is uncoloured. In each
round, Lister chooses a set $M$ of vertices and removes one token from each
chosen vertex. Painter colours a subset $X$ of $M$ which induces a subgraph
$G[X]$ of maximum degree at most $d$. A vertex $v$ is fully coloured if $v$ has
received $m$ colours. Lister wins if at the end of some round, there is a
vertex with no more tokens left and is not fully coloured. Otherwise, at some
round, all vertices are fully coloured and Painter wins. We say $G$ is
$d$-defective $(k,m)$-paintable if Painter has a winning strategy in this game.
This paper proves that every planar graph is $1$-defective $(9,2)$-paintable.


title: On the similarity of AB and BA for normal and other matrices

abstract:
  It is well-known that $AB$ and $BA$ are similar when $A$ and $B$ are complex
square Hermitian matrices. In this note we answer a question of F. Zhang by
demonstrating that similarity can fail if $A$ is Hermitian and $B$ is normal.
Perhaps surprisingly, similarity does hold when $A$ is positive semidefinite
and $B$ is normal.


title: Stochastic differential equations related to random matrix theory

abstract:
  In this note we review recent results on existence and uniqueness of
solutions of infinite-dimensional stochastic differential equations describing
interacting Brownian motions on $\R^d$.


title: Efficient sequential compression of multi-channel biomedical signals

abstract:
  This work proposes lossless and near-lossless compression algorithms for
multi-channel biomedical signals. The algorithms are sequential and efficient,
which makes them suitable for low-latency and low-power signal transmission
applications. We make use of information theory and signal processing tools
(such as universal coding, universal prediction, and fast online
implementations of multivariate recursive least squares), combined with simple
methods to exploit spatial as well as temporal redundancies typically present
in biomedical signals. The algorithms are tested with publicly available
electroencephalogram and electrocardiogram databases, surpassing in all cases
the current state of the art in near-lossless and lossless compression ratios.


title:
Nonlinear Preconditioning: How to use a Nonlinear Schwarz Method to
  Precondition Newton's Method

abstract:
  For linear problems, domain decomposition methods can be used directly as
iterative solvers, but also as preconditioners for Krylov methods. In practice,
Krylov acceleration is almost always used, since the Krylov method finds a much
better residual polynomial than the stationary iteration, and thus converges
much faster. We show in this paper that also for non-linear problems, domain
decomposition methods can either be used directly as iterative solvers, or one
can use them as preconditioners for Newton's method. For the concrete case of
the parallel Schwarz method, we show that we obtain a preconditioner we call
RASPEN (Restricted Additive Schwarz Preconditioned Exact Newton) which is
similar to ASPIN (Additive Schwarz Preconditioned Inexact Newton), but with all
components directly defined by the iterative method. This has the advantage
that RASPEN already converges when used as an iterative solver, in contrast to
ASPIN, and we thus get a substantially better preconditioner for Newton's
method. The iterative construction also allows us to naturally define a coarse
correction using the multigrid full approximation scheme, which leads to a
convergent two level non-linear iterative domain decomposition method and a two
level RASPEN non-linear preconditioner. We illustrate our findings with
numerical results on the Forchheimer equation and a non-linear diffusion
problem.


title: Development of the RFQ Cooler SHIRaC: beam transport and nuclearization

abstract:
  The development of the new RFQ Cooler, called SHIRaC, was carried out. As a
part of SPIRAL 2 facility, SHIRaC aims to handle and cool typical SPIRAL 2
beams with large emittances (up to 80 pi.mm.mrad) and high currents (up to 1
uA). Its purposes are to enhance as much as possible the beam quality
(transverse geometric emittance of less than 3 pi.mm.mrad and longitudinal
energy spread close to 1 eV) and to transmit more than 60 % of ions.
  Numerical simulations and experimental studies have shown that the required
beam quality can be reached only in term of the emittance. The energy spread is
very far from expected values. It is sensitive to the space charge and the
buffer gas diffusion and more importantly to the RF field derivative effect.
The latter arises at the RFQ exit and increases with the RF parameters (the
frequency and the amplitude of the RF voltage).
  Studies allowing to enhance the cooled beam quality, mainly the energy spread
reduction, are presented and discussed along this paper. They consist in
implementing a miniature RFQ at the RFQ exit. Using this method, it becomes
possible to improve the cooled beam quality and to reach 1 eV of longitudinal
energy spread and around 1.75 {\pi}.mm.mrad of transverse geometric emittance
for beam currents going up to 1 uA.
  The transport of the cooled beam from SHIRaC towards a HRS has been done with
an electrostatic quadrupole triplet. Simulations and first experimental tests
showed that more than 95 % of cooled beams can reach the HRS.
  Finally, developments related to the nuclearization protection methods aiming
to avoid the escape of any nuclear matter from the SHIRaC beamline are studied.


title: RLZAP: Relative Lempel-Ziv with Adaptive Pointers

abstract:
  Relative Lempel-Ziv (RLZ) is a popular algorithm for compressing databases of
genomes from individuals of the same species when fast random access is
desired. With Kuruppu et al.'s (SPIRE 2010) original implementation, a
reference genome is selected and then the other genomes are greedily parsed
into phrases exactly matching substrings of the reference. Deorowicz and
Grabowski (Bioinformatics, 2011) pointed out that letting each phrase end with
a mismatch character usually gives better compression because many of the
differences between individuals' genomes are single-nucleotide substitutions.
Ferrada et al. (SPIRE 2014) then pointed out that also using relative pointers
and run-length compressing them usually gives even better compression. In this
paper we generalize Ferrada et al.'s idea to handle well also short insertions,
deletions and multi-character substitutions. We show experimentally that our
generalization achieves better compression than Ferrada et al.'s implementation
with comparable random-access times.


title:
An introduction to Multitrace Formulations and Associated Domain
  Decomposition Solvers

abstract:
  Multitrace formulations (MTFs) are based on a decomposition of the problem
domain into subdomains, and thus domain decomposition solvers are of interest.
The fully rigorous mathematical MTF can however be daunting for the
non-specialist. We introduce in this paper MTFs on a simple model problem using
concepts familiar to researchers in domain decomposition. This allows us to get
a new understanding of MTFs and a natural block Jacobi iteration, for which we
determine optimal relaxation parameters. We then show how iterative multitrace
formulation solvers are related to a well known domain decomposition method
called optimal Schwarz method: a method which used Dirichlet to Neumann maps in
the transmission condition. We finally show that the insight gained from the
simple model problem leads to remarkable identities for Calderon projectors and
related operators, and the convergence results and optimal choice of the
relaxation parameter we obtained is independent of the geometry, the space
dimension of the problem{\color{black}, and the precise form of the spatial
elliptic operator, like for optimal Schwarz methods. We illustrate our analysis
with numerical experiments.


title: L-Borderenergetic graphs

abstract:
  The energy of a graph is defined as the sum the absolute values of the
eigenvalues of its adjacency matrix. A graph G on n vertices is said to be
borderenergetic if its energy equals the energy of the complete graph Kn. In
this paper, we promote this concept for the Laplacian matrix, introduced by
Gutman and Zhou [5]. We say G to be L-borderenergetic if LE(G) = LE(Kn).
Several classes of L-borderenergetic graphs are obtained including result that
for each positive integer r; there are 2r +1 graphs, of order n = 4r + 4;
pairwise L-noncospectral and L-bordernergetic graphs.


title:
Hanbury-Brown and Twiss effect without quantum interference in photon
  counting regime

abstract:
  Usually HBT effect can be interpreted by classical (intensity fluctuation
correlation) and quantum (interference of two-photon probability amplitudes)
theories properly at the same time. In this manuscript, we report a
deliberately designed experiment in which two chaotic light beams has the same
intensity fluctuation but mutual-orthogonal polarizations to each other so
there will be no interference of two-photon probability amplitudes. Classical
and quantum theory give different predictions on if there should be HBT (photon
bunching) effect or not in the experiment. The experiment results are used to
test the two different predictions. At the end, both the temporal and spatial
HBT effects are observed.


title: Characterizing maximally singular phase-space distributions

abstract:
  Phase-space distributions are widely applied in quantum optics to access the
nonclassical features of radiations fields. In particular, the inability to
interpret the Glauber-Sudarshan distribution in terms of a classical
probability density is the fundamental benchmark for quantum light. However,
this phase-space distribution cannot be directly reconstructed for arbitrary
states, because of its singular behavior. In this work, we perform a
characterization of the Glauber-Sudarshan representation in terms of
distribution theory. We address important features of such distributions: (i)
the maximal degree of their singularities is studied, (ii) the ambiguity of
representation is shown, and (iii) their dual space for nonclassicality tests
is specified. In this view, we reconsider the methods for regularizing the
Glauber-Sudarshan distribution for verifying its nonclassicality. This
treatment is supported with comprehensive examples and counterexamples.


title: High Temperature Superconductivity in FeSe Monolayers

abstract:
  This review discusses the main experiments and theoretical views related to
observation of high-temperature superconductivity in intercalated FeSe
compounds and single layer films of FeSe on substrates like SrTiO_3. We
consider in detail the electronic structure of these systems, both theoretical
calculations of this structure at hand and their correspondence with ARPES
experiments. It is stressed that electronic spectrum of these systems is
qualitatively different from typical picture of the spectrum in well studied
FeAs superconductors and the related problems of theoretical description of
spectrum formation are also discussed. We also discuss the possible mechanisms
of Cooper pairing in monolayers of FeSe and problems appearing here. As single
layer films of FeSe on SrTiO_3 can be represented as typical Ginzburg
"sandwiches", we analyze the possibility of rising the critical temperature of
superconducting transition T_c due to different variants of "excitonic"
mechanism of superconductivity. It is shown, that in its classic variant (as
proposed for such systems by Allender, Bray and Bardeen) this mechanism is
unable to explain the observed values of T_c, but situation is different when
we consider instead of "excitons" the optical phonons in SrTiO_3 (with energy
of the order of 100 meV). We consider both the simplest model of T_c
enhancement due to interaction with such phonons and more specific models with
dominant "forward" scattering, which allow to understand the growth of T_c as
compared with the case of bulk FeSe and intercalated FeSe systems. We also
discuss the problems connected with antiadiabatic nature of superconductivity
due to such mechanism.


title:
An Elementary Integrality Proof of Rothblum's Stable Matching
  Formulation

abstract:
  In this paper we provide a short new proof for the integrality of Rothblum's
linear description of the convex hull of incidence vectors of stable matchings
in bipartite graphs. In the spirit of iterative rounding proofs, the key
feature of our proof is to show that extreme points of the formulation must
have a 0, 1-component.


title: Hadronic resonances enhanced by thresholds

abstract:
  We present a neat example of a meson--baryon system where the vicinity of two
different thresholds enhances the binding of a hadronic resonance, a
pentaquark. As a consequence the pattern of states may change when moving among
different flavor sectors, what poses a warning on naive extrapolations to heavy
flavor sectors based on systematic expansions. For this purpose we
simultaneously analyze the $N\bar D$ and $NB$ two-hadron systems looking for
possible bound states or resonances. When a resonance is controlled by a
coupled-channel effect, going to a different flavor sector may enhance or
diminish the binding. This effect may, for example, generate significant
differences between the charmonium and bottomonium spectra above open-flavor
thresholds or pentaquark states in the open-charm and open-bottom sectors.


title:
Trace formulas for Wiener--Hopf operators with applications to entropies
  of free fermionic equilibrium states

abstract:
  We consider non-smooth functions of (truncated) Wiener--Hopf type operators
on the Hilbert space $L^2(\mathbb R^d)$. Our main results are uniform estimates
for trace norms ($d\ge 1$) and quasiclassical asymptotic formulas for traces of
the resulting operators ($d=1$). Here, we follow Harold Widom's seminal ideas,
who proved such formulas for smooth functions decades ago. The extension to
non-smooth functions and the uniformity of the estimates in various (physical)
parameters rest on recent advances by one of the authors (AVS). We use our
results to obtain the large-scale behaviour of the local entropy and the
spatially bipartite entanglement entropy (EE) of thermal equilibrium states of
non-interacting fermions in position space $\mathbb R^d$ ($d\ge 1$) at positive
temperature, $T>0$. In particular, our definition of the thermal EE leads to
estimates that are simultaneously sharp for small $T$ and large scaling
parameter $\alpha>0$ provided that the product $T\alpha$ remains bounded from
below. Here $\alpha$ is the reciprocal quasiclassical parameter. For $d=1$ we
obtain for the thermal EE an asymptotic formula which is consistent with the
large-scale behaviour of the ground-state EE (at $T=0$), previously established
by the authors for $d\ge 1$.


title:
Search for a massive invisible particle $X^0$ in $B^{+}\to e^{+}X^{0}$
  and $B^{+}\to \mu^{+}X^{0}$ decays

abstract:
  We present a search for a non-Standard-Model invisible particle $X^0$ in the
mass range $0.1\textrm{-}1.8 \,{\rm GeV}/{c^2}$ in $B^{+}\to e^{+} X^{0}$ and
$B^{+}\to \mu^{+} X^{0}$ decays. The results are obtained from a $711~{\rm
fb}^{-1}$ data sample that corresponds to $772 \times 10^{6} B\bar{B}$ pairs,
collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB
$e^+ e^-$ collider. One $B$ meson is fully reconstructed in a hadronic mode to
determine the momentum of the lepton of the signal decay in the rest frame of
the recoiling partner $B$ meson. We find no evidence of a signal and set upper
limits on the order of $10^{-6}$.


title: The holiest grail

abstract:
  I will discuss to what degree the cosmic microwave background (CMB) can be
used to constrain primordial non-Gaussianity involving one tensor and two
scalar fluctuations, focusing on the correlation of one $B$-mode polarization
fluctuation with two temperature fluctuations (BTT). In the simplest models of
inflation, the tensor-scalar-scalar primordial bispectrum is non-vanishing and
is of the same order in slow-roll parameters as the scalar-scalar-scalar
bispectrum. I will show that constraints from an experiment like CMB-Stage IV
using this observable are more than an order of magnitude better than those on
the same primordial coupling obtained from temperature measurements alone. I
will argue that $B$-mode non-Gaussianity opens up an as-yet-unexplored window
into the early Universe, demonstrating that significant information on
primordial physics remains to be harvested from CMB anisotropies. BTT presents
a measure of both primordial tensors and primordial non-Gaussianity, two of the
most sought after signatures of the inflationary paradigm.


title: Limitations for nonlinear stabilization over uncertain channels

abstract:
  We study the problem of mean-square exponential incremental stabilization of
nonlinear systems over uncertain communication channels. We show the ability to
stabilize a system over such channels is fundamentally limited and the channel
uncertainty must provide a minimal Quality of Service (QoS) to support
stabilization. The smallest QoS necessary for stabilization is shown as a
function of the positive Lyapunov exponents of uncontrolled nonlinear systems.
The positive Lyapunov exponent is a measure of dynamical complexity and
captures the rate of exponential divergence of nearby system trajectories. One
of the main highlights of our results is the role played by nonequilibrium
dynamics to determine the limitation for incremental stabilization over
networks with uncertainty.


title: Normalizer of the Chevalley group of type $E_7$

abstract:
  We consider the simply connected Chevalley group $G(E_7,R)$ of type $E_7$ in
the 56-dimensional representation. The main objective of the paper is to prove
that the following four groups coincide: the normalizer of the elementary
Chevalley group $E(E_7,R)$, the normalizer of the Chevalley group $G(E_7,R)$
itself, the transporter of $E(E_7,R)$ into $G(\mathrm E_7,R)$, and the extended
Chevalley group $\overline G(E_7,R)$. This holds over an arbitrary commutative
ring $R$, with all normalizers and transporters being calculated in $GL(56,R)$.
Moreover, we characterize $\overline G(E_7,R)$ as the stabilizer of a system of
quadrics. This last result is classically known over algebraically closed
fields, here we prove that the corresponding group scheme is smooth over
$\mathbb Z$, which implies that it holds over arbitrary commutative rings.
These results are one of the key steps in our subsequent paper, dedicated to
the overgroups of exceptional groups in minimal representations.


title: Establishing Multiple Survivable Connections (Extended Version)

abstract:
  We consider the establishment of connections in survivable networks, where
each connection is allocated with a working (primary) path and a protection
(backup) path. While many optimal solutions have been found for the
establishment of a single connection, only heuristics have been proposed for
the multi-connection case. We investigate the algorithmic tractability of
multi-connection establishment problems, both in online and offline frameworks.
First, we focus on the special case of two connections, and study the
tractability of three variants of the problem. We show that only one variant is
tractable, for which we establish an optimal solution of polynomial complexity.
For the other variants, which are shown to be NP-hard, heuristic schemes are
proposed. These heuristics are designed based on the insight gained from our
study. Through simulations, we indicate the advantages of these heuristics over
more straightforward alternatives. We extend our study to K connections, for a
fixed K that is larger than 2. We prove the tractability of online and offline
variants of the problem, in which sharing links along backup paths is allowed,
and we establish corresponding optimal solutions. On the other hand, we show
that, if the number of connections is not fixed (i.e., K is not O(1)), then the
problem is, in general, NP-hard.


title:
Proceedings of the 5th Workshop on Machine Learning and Interpretation
  in Neuroimaging (MLINI) at NIPS 2015

abstract:
  This volume is a collection of contributions from the 5th Workshop on Machine
Learning and Interpretation in Neuroimaging (MLINI) at the Neural Information
Processing Systems (NIPS 2015) conference. Modern multivariate statistical
methods developed in the rapidly growing field of machine learning are being
increasingly applied to various problems in neuroimaging, from cognitive state
detection to clinical diagnosis and prognosis. Multivariate pattern analysis
methods are designed to examine complex relationships between high-dimensional
signals, such as brain images, and outcomes of interest, such as the category
of a stimulus, a type of a mental state of a subject, or a specific mental
disorder. Such techniques are in contrast with the traditional mass-univariate
approaches that dominated neuroimaging in the past and treated each individual
imaging measurement in isolation.
  We believe that machine learning has a prominent role in shaping how
questions in neuroscience are framed, and that the machine-learning mind set is
now entering modern psychology and behavioral studies. It is also equally
important that practical applications in these fields motivate a rapidly
evolving line or research in the machine learning community. In parallel, there
is an intense interest in learning more about brain function in the context of
rich naturalistic environments and scenes. Efforts to go beyond highly specific
paradigms that pinpoint a single function, towards schemes for measuring the
interaction with natural and more varied scene are made. The goal of the
workshop is to pinpoint the most pressing issues and common challenges across
the neuroscience, neuroimaging, psychology and machine learning fields, and to
sketch future directions and open questions in the light of novel methodology.


title:
Measurement of the double-differential inclusive jet cross section in
  proton-proton collisions at sqrt(s) = 13 TeV

abstract:
  A measurement of the double-differential inclusive jet cross section as a
function of jet transverse momentum pT and absolute jet rapidity |y| is
presented. The analysis is based on proton-proton collisions collected by the
CMS experiment at the LHC at a centre-of-mass energy of 13 TeV. The data
samples correspond to integrated luminosities of 71 and 44 inverse picobarns
for |y| < 3 and 3.2 < |y| < 4.7, respectively. Jets are reconstructed with the
anti-kt clustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase
space region covering jet pT up to 2 TeV and jet rapidity up to |y| = 4.7.
Predictions of perturbative quantum chromodynamics at next-to-leading order
precision, complemented with electroweak and nonperturbative corrections, are
used to compute the absolute scale and the shape of the inclusive jet cross
section. The cross section difference in R, when going to a smaller jet size of
0.4, is best described by Monte Carlo event generators with next-to-leading
order predictions matched to parton showering, hadronisation, and multiparton
interactions. In the phase space accessible with the new data, this measurement
provides a first indication that jet physics is as well understood at sqrt(s) =
13 TeV as at smaller centre-of-mass energies.


title: A reproducible method to determine the meteoroid mass index

abstract:
  Context. The determination of meteoroid mass indices is central to flux
measurements and evolutionary studies of meteoroid populations. However,
different authors use different approaches to fit observed data, making results
difficult to reproduce and the resulting uncertainties difficult to justify.
The real, physical, uncertainties are usually an order of magnitude higher than
the reported values.
  Aims. We aim to develop a fully automated method that will measure meteoroid
mass indices and associated uncertainty. We validate our method on large radar
and optical datasets and compare results to obtain a best estimate of the true
meteoroid mass index.
  Methods. Using MultiNest, a Bayesian inference tool that calculates the
evidence and explores the parameter space, we search for the best fit of
cumulative number vs. mass distributions in a four-dimensional space of
variables ($a,b,X_1,X_2$). We explore biases in meteor echo distributions using
optical meteor data as a calibration dataset to establish the systematic offset
in measured mass index values.
  Results. Our best estimate for the average de-biased mass index for the
sporadic meteoroid complex, as measured by radar appropriate to the mass range
$10^{-3} > \mathrm{m} > 10^{-5}$ g, was $s=-2.10 \pm 0.08$. Optical data in the
$10^{-1} > \mathrm{m} > 10^{-3}$ g range, with the shower meteors removed,
produced $s=-2.08 \pm 0.08$. We find the mass index used by Grun et al. 1985 is
substantially larger than we measure in the $10^{-4} < m < 10^{-1}$ g range.


title:
Curvilinear polyhedra as dynamical arenas, illustrated by an example of
  self-organized locomotion

abstract:
  Experiment shows that dumbbells, placed inside a tilted hollow cylindrical
drum that rotates slowly around its axis, climb uphill by forming dynamically
stable pairs, seemingly against the pull of gravity. Analysis of this
experiment shows that the dynamics takes place in an underlying space which is
a curvilinear polyhedron inside a six dimensional manifold, carved out by
unilateral constraints that arise from the non-interpenetrability of the
dumbbells. The energetics over this polyhedron localizes the configuration
point within the close proximity of a corner of the polyhedron. This results
into a strong entrapment, which provides the configuration of the dumbbells
with its observed shape that leads to its functionality -- uphill locomotion.
The stability of the configuration is a consequence of the strong entrapment in
the corner of the polyhedron.


title:
Learning Relevant Features for Manipulation Skills using Meta-Level
  Priors

abstract:
  Robots can generalize manipulation skills between different scenarios by
adapting to the features of the objects being manipulated. Selecting the set of
relevant features for generalizing skills has usually been performed manually
by a human. Alternatively, a robot can learn to select relevant features
autonomously. However, feature selection usually requires a large amount of
training data, which would require many demonstrations. In order to learn the
relevant features more efficiently, we propose using a meta-level prior to
transfer the relevance of features from previously learned skills. The
experiments show that the meta-level prior more than doubles the average
precision and recall of the feature selection when compared to a standard
uniform prior. The proposed approach was used to learn a variety of
manipulation skills, including pushing, cutting, and pouring.


title: Rydberg dressing of a one-dimensional Bose-Einstein condensate

abstract:
  We study the influence of Rydberg dressed interactions in a one-dimensional
(1D) Bose-Einstein Condensate (BEC). We show that a 1D geometry offers several
advantages over 3D for observing BEC Rydberg dressing. The effects of dressing
are studied by investigating collective BEC dynamics after a rapid switch-off
of the Rydberg dressing interaction. The results can be interpreted as an
effective modification of the s-wave scattering length. We include this
modification in an analytical model for the 1D BEC, and compare it to numerical
calculations of Rydberg dressing under realistic experimental conditions.


title: A Note on $4$-colorings of Quadrangulations

abstract:
  Let $G$ be a quadrangulation on an orientable surface and let $g$ be a proper
vertex-$4$-coloring of $G$. A face $F$ of $G$ is said to be a rainbow-face if
all four distinct colors appear on its boundary. A $(c_1,c_2,c_3,c_4)$-face in
$G$ is a rainbow face with colors $c_i$, $i=1,2,3,4$ on the boundary in
clockwise order. We show that the number of $(c_1,c_2,c_3,c_4)$-faces in $G$
equals the number of $(c_4,c_3,c_2,c_1)$-faces. This implies in particular that
the number of rainbow-faces of $G$ is even.


title:
Prospects for a lattice computation of rare kaon decay amplitudes II
  $K\to\pi\nu\bar{\nu}$ decays

abstract:
  The rare kaon decays $K\to\pi\nu\bar{\nu}$ are strongly suppressed in the
standard model and widely regarded as processes in which new phenomena, not
predicted by the standard model, may be observed. Recognizing such new
phenomena requires precise standard model prediction for the braching ratio of
$K\to\pi\nu\bar{\nu}$ with controlled uncertainty for both short-distance and
long-distance contributions. In this work we demonstrate the feasibility of
lattice QCD calculation of the long-distance contribution to rare kaon decays
with the emphasis on $K^+\to\pi^+\nu\bar{\nu}$. Our methodology covers the
calculation of both $W$-$W$ and $Z$-exchange diagrams. We discuss the
estimation of the power-law, finite-volume corrections and two methods to
consistently combine the long distance contribution determined by the lattice
methods outlined here with the short distance parts that can be reliably
determined using perturbation theory. It is a subsequent work of our first
methodology paper on $K\to\pi\ell^+\ell^-$, where the focus was made on the
$\gamma$-exchange diagrams.


title:
Amplitude Variability in gamma Dor and delta Scuti stars observed by the
  Kepler Spacecraft

abstract:
  The NASA Kepler spacecraft data revealed a large number of multimode
nonradially pulsating gamma Dor and delta Sct variable star candidates. The
high precision long time-series photometry makes it possible to study amplitude
variations of the frequencies. We summarize recent literature on amplitude and
frequency variations in pulsating variables. We are searching for amplitude
variability in several dozen faint gamma Doradus or delta Scuti variable-star
candidates observed as part of the Kepler Guest Observer program. We apply
several methods, including a Matlab-script wavelet analysis developed by J.
Jackiewicz, and the wavelet technique of the VSTAR software
(http://www.aavso.org/vstar-overview). Here we show results for two stars, KIC
2167444 and KIC 2301163. We discuss the magnitude and timescale of the
amplitude variations, and the presence or absence of correlations between
amplitude variations for different frequencies of a given star. Amplitude
variations may be detectable using Kepler data even for stars with Kepler
magnitude >14 with low-amplitude frequencies (around 100 ppm) using only one or
a few quarters of long-cadence data. We discuss proposed causes of amplitude
spectrum variability that will require further investigation.


title: Chern classes from Morava K-theories to Chow groups

abstract:
  In this paper we calculate the ring of unstable (possibly non-additive)
operations from algebraic Morava K-theory K(n) to Chow groups with
$\mathbb{Z}_{(p)}$-coefficients. More precisely, we prove that it is a formal
power series ring on generators $c_i:K(n)\rightarrow CH^i \otimes
\mathbb{Z}_{(p)}$, which satisfy a Cartan-type formula.


title:
Temperature Dependence of Wavelength Selectable Zero-Phonon Emission
  from Single Defects in Hexagonal Boron Nitride

abstract:
  We investigate the distribution and temperature-dependent optical properties
of sharp, zero-phonon emission from defect-based single photon sources in
multilayer hexagonal boron nitride (h-BN) flakes. We observe sharp emission
lines from optically active defects distributed across an energy range that
exceeds 500 meV. Spectrally-resolved photon-correlation measurements verify
single photon emission, even when multiple emission lines are simultaneously
excited within the same h-BN flake. We also present a detailed study of the
temperature-dependent linewidth, spectral energy shift, and intensity for two
different zero-phonon lines centered at 575 nm and 682 nm, which reveals a
nearly identical temperature dependence despite a large difference in
transition energy. Our temperature-dependent results are best described by a
lattice vibration model that considers piezoelectric coupling to in-plane
phonons. Finally, polarization spectroscopy measurements suggest that whereas
the 575 nm emission line is directly excited by 532 nm excitation, the 682 nm
line is excited indirectly.


title:
Divide and Conquer in Non-standard Problems and the Super-efficiency
  Phenomenon

abstract:
  We study how the divide and conquer principle --- partition the available
data into subsamples, compute an estimate from each subsample and combine these
appropriately to form the final estimator --- works in non-standard problems
where rates of convergence are typically slower than $\sqrt{n}$ and limit
distributions are non-Gaussian, with a special emphasis on the least squares
estimator (and its inverse) of a monotone regression function. We find that the
pooled estimator, obtained by averaging non-standard estimates across the
mutually exclusive subsamples, outperforms the non-standard estimator based on
the entire sample in the sense of pointwise inference. We also show that, under
appropriate conditions, if the number of subsamples is allowed to increase at
appropriate rates, the pooled estimator is asymptotically normally distributed
with a variance that is empirically estimable from the subsample-level
estimates. Further, in the context of monotone function estimation we show that
this gain in pointwise efficiency comes at a price --- the pooled estimator's
performance, in a uniform sense (maximal risk) over a class of models worsens
as the number of subsamples increases, leading to a version of the
super-efficiency phenomenon. In the process, we develop analytical results for
the order of the bias in isotonic regression, which are of independent
interest.


title: A New Method for Parallel Monte Carlo Tree Search

abstract:
  In recent years there has been much interest in the Monte Carlo tree search
algorithm, a new, adaptive, randomized optimization algorithm. In fields as
diverse as Artificial Intelligence, Operations Research, and High Energy
Physics, research has established that Monte Carlo tree search can find good
solutions without domain dependent heuristics. However, practice shows that
reaching high performance on large parallel machines is not so successful as
expected. This paper proposes a new method for parallel Monte Carlo tree search
based on the pipeline computation pattern.


title: The non-semisimple Verlinde formula and pseudo-trace functions

abstract:
  We point out that results of Shimizu on internal characters imply a useful
non-semisimple variant of the categorical Verlinde formula for factorisable
finite tensor categories. When combined with results on pseudo-trace functions
by Miyamoto and Arike-Nagatomo, one can make a precise conjecture for a
non-semisimple modular Verlinde formula which relates modular properties of
pseudo-trace functions and the product in the Grothendieck ring of the
corresponding vertex operator algebra.


title:
Chemical distances for percolation of planar Gaussian free fields and
  critical random walk loop soups

abstract:
  We initiate the study on chemical distances of percolation clusters for level
sets of two-dimensional discrete Gaussian free fields as well as loop clusters
generated by two-dimensional random walk loop soups. One of our results states
that the chemical distance between two macroscopic annuli away from the
boundary for the random walk loop soup at the critical intensity is of
dimension 1 with positive probability. Our proof method is based on an
interesting combination of a theorem of Makarov, isomorphism theory and an
entropic repulsion estimate for Gaussian free fields in the presence of a hard
wall.


title:
A four dimensional map for escape from resonance: negative energy modes
  and nonlinear instability

abstract:
  Positive definiteness of a Hamiltonian expanded about an equilibrium point
provides only a necessary condition for stability, a criterion known as
Dirichlet's theorem. The reason that this criterion is not necessary for
stability is because of the possible existence of negative energy modes, which
are linearly stable modes of oscillation that have negative energy. When such
modes are present, the Hamiltonian is, in general, indefinite. Although such
systems with negative energy modes are linearly stable (spectral stable), they
are unstable to infinitesimal perturbations under the nonlinear dynamics. In
the present work we study this kind of nonlinear instability with the simplest
nontrivial four dimensional area-preserving map, which has a cubic degree of
freedom, that was designed to mimic the behavior of a Hamiltonian system with
one positive and one negative energy mode, and a quadratic degree of freedom,
that allows eventual escapes in phase space, usually called as Arnold
diffusion.


title:
Topological invariants for three dimensional Dirac semimetals and four
  dimensional topological rotational insulators

abstract:
  Dirac semimetal is a class of semi-metallic phase protected by certain types
of crystalline symmetries, and its low-energy effective Hamiltonian is
described by Dirac equations in three dimensions (3D). Despite of various
theoretical studies, theories that describe the topological nature of Dirac
semimetals have not been well established. In this work, we define a
topological invariant for 3D Dirac semimetals by establishing a mapping between
a 3D Dirac semimetal and a topological crystalline insulator in four dimension
(4D). We demonstrate this scheme by constructing a tight-binding model for 4D
topological crystalline insulators that are protected by rotational symmetry. A
new type of topological invariant, "rotational Chern number", is shown to
characterize the topology of this system. As a consequence of the rotational
Chern number, gapless Dirac points are found on the 3D surface of this 4D
system. For a slab with two surfaces, we find that the corresponding low-energy
effective theory of two surface states can be directly mapped to that of a 3D
Dirac semimetal, suggesting that topological nature of 3D Dirac semimetals can
be characterized by rotational Chern number which is defined in 4D. Our scheme
provides a new systematic approach to extract topological nature for
topological semimetal phases.


title:
Sound speed and oscillation frequencies for solar models evolved with
  Los Alamos ATOMIC opacities

abstract:
  Los Alamos National Laboratory has calculated a new generation of radiative
opacities (OPLIB data using the ATOMIC code) for elements with atomic number
Z=1-30 with improved physics input, updated atomic data, and finer temperature
grid to replace the Los Alamos LEDCOP opacities released in the year 2000. We
calculate the evolution of standard solar models including these new opacities,
and compare with models evolved using the Lawrence Livermore National
Laboratory OPAL (Iglesias and Rogers 1996) opacities. We use the solar
abundance mixture of Asplund et al. (2009). The new Los Alamos ATOMIC opacities
have steeper opacity derivatives than those of OPAL for temperatures and
densities of the solar interior radiative zone. We compare the calculated
nonadiabatic solar oscillation frequencies and solar interior sound speed to
observed frequencies and helioseismic inferences. The calculated sound-speed
profiles are similar for models evolved using either the updated Iben evolution
code (see \cite{Guzik2010}), or the MESA evolution code (Paxton et al., 2015).
The LANL ATOMIC opacities partially mitigate the "solar abundance problem".


title:
Heavy Quark Entropy shift: From the Hadron Resonance Gas to Power
  Corrections

abstract:
  A heavy quark placed in the medium modifies its specific heat. Using a
renormalization group argument we show a low energy theorem in terms of the
defect in the trace of the energy-momentum tensor which allows the unambiguous
determination of the corresponding entropy shift after imposing the third
principle of thermodynamics for degenerate states. We show how recent lattice
QCD data can be understood in the confined phase in terms of a single-heavy
hadronic spectrum and above the phase transition through power corrections
which are analyzed by means of a dimension 2 gluon condensate of the
dimensionally reduced theory.


title:
Odd-frequency superconductivity in a nanowire coupled to Majorana zero
  modes

abstract:
  Odd-frequency superconductivity, originally proposed by Berezinskii in 1974,
is an exotic phase of matter in which Cooper pairing between electrons is
entirely dynamical in nature. The pair potential is an odd function of
frequency, leading to a vanishing static superconducting order parameter and
exotic types of pairing seemingly inconsistent with Fermi statistics. Motivated
by recent experimental progress in the realization of Majorana zero modes in
semiconducting nanowires, we show that odd-frequency superconductivity
generically appears in a spin-polarized nanowire coupled to Majorana zero
modes. We explicitly calculate the superfluid response and show that it is
characterized by a paramagnetic Meissner effect.


title:
2-D and 3-D Models of Convective Turbulence and Oscillations in
  Intermediate-Mass Main-Sequence Stars

abstract:
  We present multidimensional modeling of convection and oscillations in
main-sequence stars somewhat more massive than the Sun, using three separate
approaches: 1) Using the 3-D planar StellarBox radiation hydrodynamics code to
model the envelope convection zone and part of the radiative zone. Our goals
are to examine the interaction of stellar pulsations with turbulent convection
in the envelope, excitation of acoustic modes, and the role of convective
overshooting; 2) Applying the spherical 3-D MHD ASH (Anelastic Spherical
Harmonics) code to simulate the core convection and radiative zone. Our goal is
to determine whether core convection can excite low-frequency gravity modes,
and thereby explain the presence of low frequencies for some hybrid gamma
Doradus/delta Scuti variables for which the envelope convection zone is too
shallow for the convective blocking mechanism to drive gravity modes; 3)
Applying the ROTORC 2-D stellar evolution and dynamics code to calculate
evolution with a variety of initial rotation rates and extents of core
convective overshooting. The nonradial adiabatic pulsation frequencies of these
nonspherical models are calculated using the 2-D pulsation code NRO. We present
new insights into pulsations for stars of one to two solar masses gained by
multidimensional modeling.


title: Single-photon absorber based on strongly interacting Rydberg atoms

abstract:
  Removing exactly one photon from an arbitrary input pulse is an elementary
operation in quantum optics and enables applications in quantum information
processing and quantum simulation. Here we demonstrate a deterministic
single-photon absorber based on the saturation of an optically thick free-space
medium by a single photon due to Rydberg blockade. Single-photon subtraction
adds a new component to the Rydberg quantum optics toolbox, which already
contains photonic logic building-blocks such as single-photon sources,
switches, transistors, and conditional $\pi$-phase shifts. Our approach is
scalable to multiple cascaded absorbers, essential for preparation of
non-classical light states for quantum information and metrology applications,
and, in combination with the single-photon transistor, high-fidelity
number-resolved photon detection.


title:
Linear identification of nonlinear systems: A lifting technique based on
  the Koopman operator

abstract:
  We exploit the key idea that nonlinear system identification is equivalent to
linear identification of the socalled Koopman operator. Instead of considering
nonlinear system identification in the state space, we obtain a novel linear
identification technique by recasting the problem in the infinite-dimensional
space of observables. This technique can be described in two main steps. In the
first step, similar to the socalled Extended Dynamic Mode Decomposition
algorithm, the data are lifted to the infinite-dimensional space and used for
linear identification of the Koopman operator. In the second step, the obtained
Koopman operator is "projected back" to the finite-dimensional state space, and
identified to the nonlinear vector field through a linear least squares
problem. The proposed technique is efficient to recover (polynomial) vector
fields of different classes of systems, including unstable, chaotic, and open
systems. In addition, it is robust to noise, well-suited to model low sampling
rate datasets, and able to infer network topology and dynamics.


title:
Discovery of an extremely weak magnetic field in the white dwarf LTT
  16093 = WD2047+372

abstract:
  Magnetic fields have been detected in several hundred white dwarfs, with
strengths ranging from a few kG to several hundred MG. Only a few of the known
fields have a mean magnetic field modulus below about 1 MG.
  We are searching for new examples of magnetic white dwarfs with very weak
fields, and trying to model the few known examples. Our search is intended to
be sensitive enough to detect fields at the few kG level.
  We have been surveying bright white dwarfs for very weak fields using
spectropolarimeters at the Canada-France-Hawaii telescope, the William Herschel
telescope, the European Southern Observatory, and the Russian Special
Astrophysical Observatory. We discuss in some detail tests of the WHT
spectropolarimeter ISIS using the known magnetic strong-field Ap star HD 215441
(Babcock's star) and the long-period Ap star HD 201601 (gamma Equ).
  We report the discovery of a field with a mean field modulus of about 57 kG
in the white dwarf LTT 16093 = WD2047+372. The field is clearly detected
through the Zeeman splitting of Halpha seen in two separate circularly
polarised spectra from two different spectropolarimeters. Zeeman circular
polarisation is also detected, but only barely above the 3 sigma level.
  The discovery of this field is significant because it is the third weakest
field ever unambiguously discovered in a white dwarf, while still being large
enough that we should be able to model the field structure in some detail with
future observations.


title: Vector bundles on genus 2 curves and trivectors

abstract:
  Given a complex curve C of genus 2, there is a well-known relationship
between the moduli space of rank 3 semistable bundles on C and a cubic
hypersurface known as the Coble cubic. Some of the aspects of this is known to
be related to the geometric invariant theory of the third exterior power of a
9-dimensional complex vector space. We extend this relationship to arbitrary
fields and study some of the connections to invariant theory, which will be
studied more in-depth in a followup paper.


title: Detecting Damped Lyman-$\alpha$ Absorbers with Gaussian Processes

abstract:
  We develop an automated technique for detecting damped Lyman-$\alpha$
absorbers (DLAs) along spectroscopic lines of sight to quasi-stellar objects
(QSOs or quasars). The detection of DLAs in large-scale spectroscopic surveys
such as SDSS-III sheds light on galaxy formation at high redshift, showing the
nucleation of galaxies from diffuse gas. We use nearly 50 000 QSO spectra to
learn a novel tailored Gaussian process model for quasar emission spectra,
which we apply to the DLA detection problem via Bayesian model selection. We
propose models for identifying an arbitrary number of DLAs along a given line
of sight. We demonstrate our method's effectiveness using a large-scale
validation experiment, with excellent performance. We also provide a catalog of
our results applied to 162 858 spectra from SDSS-III data release 12.


title: Galactic Energetic Particles and Their Radiative Yields in Clusters

abstract:
  As energetic particles diffuse out of radio and star-forming galaxies (SFGs),
their intracluster density builds up to a level that could account for a
substantial part or all the emission from a radio halo. We calculate the
particle time-dependent, spectro-spatial distributions from a solution of a
diffusion equation with radio galaxies as sources of electrons, and SFGs as
sources of both electrons and protons. Whereas strong radio galaxies are
typically found in the cluster (e.g., Coma) core, the fraction of SFGs
increases with distance from the cluster center. Scaling particle escape rates
from their sources to the reasonably well determined Galactic rates, and for
realistic gas density and magnetic field spatial profiles, we find that
predicted spectra and spatial profiles of radio emission from primary and
secondary electrons are roughly consistent with those deduced from current
measurements of the Coma halo (after subtraction of emission from the relic
Coma A). Nonthermal X-ray emission is predicted to be mostly by Compton
scattering of electrons from radio galaxies off the CMB, whereas $\gamma$-ray
emission is primarily from the decay of neutral pions produced in interactions
of protons from SFGs with protons in intracluster gas.


title:
Large-scale Analysis of Counseling Conversations: An Application of
  Natural Language Processing to Mental Health

abstract:
  Mental illness is one of the most pressing public health issues of our time.
While counseling and psychotherapy can be effective treatments, our knowledge
about how to conduct successful counseling conversations has been limited due
to lack of large-scale data with labeled outcomes of the conversations. In this
paper, we present a large-scale, quantitative study on the discourse of
text-message-based counseling conversations. We develop a set of novel
computational discourse analysis methods to measure how various linguistic
aspects of conversations are correlated with conversation outcomes. Applying
techniques such as sequence-based conversation models, language model
comparisons, message clustering, and psycholinguistics-inspired word frequency
analyses, we discover actionable conversation strategies that are associated
with better conversation outcomes.


title:
Diversity of emergent dynamics in competitive threshold-linear networks:
  a preliminary report

abstract:
  Threshold-linear networks consist of simple units interacting in the presence
of a threshold nonlinearity. Competitive threshold-linear networks have long
been known to exhibit multistability, where the activity of the network settles
into one of potentially many steady states. In this work, we find conditions
that guarantee the absence of steady states, while maintaining bounded
activity. These conditions lead us to define a combinatorial family of
competitive threshold-linear networks, parametrized by a simple directed graph.
By exploring this family, we discover that threshold-linear networks are
capable of displaying a surprisingly rich variety of nonlinear dynamics,
including limit cycles, quasiperiodic attractors, and chaos. In particular,
several types of nonlinear behaviors can co-exist in the same network. Our
mathematical results also enable us to engineer networks with multiple dynamic
patterns. Taken together, these theoretical and computational findings suggest
that threshold-linear networks may be a valuable tool for understanding the
relationship between network connectivity and emergent dynamics.


title: From Query to Usable Code: An Analysis of Stack Overflow Code Snippets

abstract:
  Enriched by natural language texts, Stack Overflow code snippets are an
invaluable code-centric knowledge base of small units of source code. Besides
being useful for software developers, these annotated snippets can potentially
serve as the basis for automated tools that provide working code solutions to
specific natural language queries.
  With the goal of developing automated tools with the Stack Overflow snippets
and surrounding text, this paper investigates the following questions: (1) How
usable are the Stack Overflow code snippets? and (2) When using text search
engines for matching on the natural language questions and answers around the
snippets, what percentage of the top results contain usable code snippets?
  A total of 3M code snippets are analyzed across four languages: C\#, Java,
JavaScript, and Python. Python and JavaScript proved to be the languages for
which the most code snippets are usable. Conversely, Java and C\# proved to be
the languages with the lowest usability rate. Further qualitative analysis on
usable Python snippets shows the characteristics of the answers that solve the
original question. Finally, we use Google search to investigate the alignment
of usability and the natural language annotations around code snippets, and
explore how to make snippets in Stack Overflow an adequate base for future
automatic program generation.


title:
Monotone Retargeting for Unsupervised Rank Aggregation with Object
  Features

abstract:
  Learning the true ordering between objects by aggregating a set of expert
opinion rank order lists is an important and ubiquitous problem in many
applications ranging from social choice theory to natural language processing
and search aggregation. We study the problem of unsupervised rank aggregation
where no ground truth ordering information in available, neither about the true
preference ordering between any set of objects nor about the quality of
individual rank lists. Aggregating the often inconsistent and poor quality rank
lists in such an unsupervised manner is a highly challenging problem, and
standard consensus-based methods are often ill-defined, and difficult to solve.
In this manuscript we propose a novel framework to bypass these issues by using
object attributes to augment the standard rank aggregation framework. We design
algorithms that learn joint models on both rank lists and object features to
obtain an aggregated rank ordering that is more accurate and robust, and also
helps weed out rank lists of dubious validity. We validate our techniques on
synthetic datasets where our algorithm is able to estimate the true rank
ordering even when the rank lists are corrupted. Experiments on three real
datasets, MQ2008, MQ2008 and OHSUMED, show that using object features can
result in significant improvement in performance over existing rank aggregation
methods that do not use object information. Furthermore, when at least some of
the rank lists are of high quality, our methods are able to effectively exploit
their high expertise to output an aggregated rank ordering of great accuracy.


title: Generalized Linear Models for Aggregated Data

abstract:
  Databases in domains such as healthcare are routinely released to the public
in aggregated form. Unfortunately, naive modeling with aggregated data may
significantly diminish the accuracy of inferences at the individual level. This
paper addresses the scenario where features are provided at the individual
level, but the target variables are only available as histogram aggregates or
order statistics. We consider a limiting case of generalized linear modeling
when the target variables are only known up to permutation, and explore how
this relates to permutation testing; a standard technique for assessing
statistical dependency. Based on this relationship, we propose a simple
algorithm to estimate the model parameters and individual level inferences via
alternating imputation and standard generalized linear model fitting. Our
results suggest the effectiveness of the proposed approach when, in the
original data, permutation testing accurately ascertains the veracity of the
linear relationship. The framework is extended to general histogram data with
larger bins - with order statistics such as the median as a limiting case. Our
experimental results on simulated data and aggregated healthcare data suggest a
diminishing returns property with respect to the granularity of the histogram -
when a linear relationship holds in the original data, the targets can be
predicted accurately given relatively coarse histograms.


title: On a nonlinear gravitational wave. Geodesics

abstract:
  An exact, plane wave solution of the gravitational field equations is
investigated. The source stress tensor is represented by an anisotropic null
fluid with energy flux to which the energy density $\rho$ and all pressures are
finite throughout the spacetime. They depend on a constant length (taken of the
order of the Planck length) and acquire Planck values close to the null surface
$t - z = 0$, the $z$-axis being the direction of propagation. The timelike
geodesics of a test particle are contained in a plane whose normal has constant
direction and the null trajectories are comoving with a plane of fixed
direction.


title: RNAiFold2T: Constraint Programming design of thermo-IRES switches

abstract:
  Motivation: RNA thermometers (RNATs) are cis-regulatory ele- ments that
change secondary structure upon temperature shift. Often involved in the
regulation of heat shock, cold shock and virulence genes, RNATs constitute an
interesting potential resource in synthetic biology, where engineered RNATs
could prove to be useful tools in biosensors and conditional gene regulation.
Results: Solving the 2-temperature inverse folding problem is critical for RNAT
engineering. Here we introduce RNAiFold2T, the first Constraint Programming
(CP) and Large Neighborhood Search (LNS) algorithms to solve this problem.
Benchmarking tests of RNAiFold2T against existent programs (adaptive walk and
genetic algorithm) inverse folding show that our software generates two orders
of magnitude more solutions, thus allow- ing ample exploration of the space of
solutions. Subsequently, solutions can be prioritized by computing various
measures, including probability of target structure in the ensemble, melting
temperature, etc. Using this strategy, we rationally designed two thermosensor
internal ribosome entry site (thermo-IRES) elements, whose normalized
cap-independent transla- tion efficiency is approximately 50% greater at 42?C
than 30?C, when tested in reticulocyte lysates. Translation efficiency is lower
than that of the wild-type IRES element, which on the other hand is fully
resistant to temperature shift-up. This appears to be the first purely
computational design of functional RNA thermoswitches, and certainly the first
purely computational design of functional thermo-IRES elements. Availability:
RNAiFold2T is publicly available as as part of the new re- lease RNAiFold3.0 at
https://github.com/clotelab/RNAiFold and http:
//bioinformatics.bc.edu/clotelab/RNAiFold, which latter has a web server as
well. The software is written in C++ and uses OR-Tools CP search engine.


title:
Rationale-Augmented Convolutional Neural Networks for Text
  Classification

abstract:
  We present a new Convolutional Neural Network (CNN) model for text
classification that jointly exploits labels on documents and their component
sentences. Specifically, we consider scenarios in which annotators explicitly
mark sentences (or snippets) that support their overall document
categorization, i.e., they provide rationales. Our model exploits such
supervision via a hierarchical approach in which each document is represented
by a linear combination of the vector representations of its component
sentences. We propose a sentence-level convolutional model that estimates the
probability that a given sentence is a rationale, and we then scale the
contribution of each sentence to the aggregate document representation in
proportion to these estimates. Experiments on five classification datasets that
have document labels and associated rationales demonstrate that our approach
consistently outperforms strong baselines. Moreover, our model naturally
provides explanations for its predictions.


title:
The Friendship Paradox and Systematic Biases in Perceptions and Social
  Norms

abstract:
  The "friendship paradox" (Feld1991) refers to the fact that, on average,
people have strictly fewer friends than their friends have. I show that this
over-sampling of the most popular people amplifies behaviors that involve
complementarities. People with more friends experience greater interactive
effects and hence engage more in socially influenced activities. Given the
friendship paradox, people then perceive more engagement when sampling their
friends than exists in the overall population. Given the complementarities,
this feeds back to amplify average engagement. In addition, people with the
greatest innate benefits from a behavior also tend to be the ones who choose to
interact the most, leading to further feedback and amplification. These results
are consistent with studies finding that people consistently overestimate peer
consumption of alcohol, cigarettes, and drugs; and, can help explain problems
with adolescent abuse of drugs and binge-drinking, as well as other behaviors.
I also discuss how these results change in cases of strategic substitutes,
where individuals overestimate free-riding by peers.


title: Designing Kitaev spin liquids in metal-organic frameworks

abstract:
  Kitaev's honeycomb lattice spin model is a remarkable exactly solvable model,
which has a particular type of spin liquid (Kitaev spin liquid) as the ground
state. Although its possible realization in iridates and $\alpha$-RuCl$_3$ has
been vigorously discussed recently, these materials have substantial non-Kitaev
direct exchange interactions and do not have a spin liquid ground state. We
propose metal-organic frameworks (MOFs) with Ru$^{3+}$ (or Os$^{3+}$) forming
the honeycomb lattice as promising candidates for a more ideal realization of
Kitaev-type spin models where the direct exchange interaction is strongly
suppressed. The great flexibility of MOFs allows generalization to other
three-dimensional lattices, for potential realization of a variety of spin
liquids such as a Weyl spin liquid.


title: Extended Hardness Results for Approximate Gr\"obner Basis Computation

abstract:
  Two models were recently proposed to explore the robust hardness of Gr\"obner
basis computation. Given a polynomial system, both models allow an algorithm to
selectively ignore some of the polynomials: the algorithm is only responsible
for returning a Gr\"obner basis for the ideal generated by the remaining
polynomials. For the $q$-Fractional Gr\"obner Basis Problem the algorithm is
allowed to ignore a constant $(1-q)$-fraction of the polynomials (subject to
one natural structural constraint). Here we prove a new strongest-parameter
result: even if the algorithm is allowed to choose a $(3/10-\epsilon)$-fraction
of the polynomials to ignore, and need only compute a Gr\"obner basis with
respect to some lexicographic order for the remaining polynomials, this cannot
be accomplished in polynomial time (unless $P=NP$). This statement holds even
if every polynomial has maximum degree 3. Next, we prove the first robust
hardness result for polynomial systems of maximum degree 2: for the
$q$-Fractional model a $(1/5-\epsilon)$ fraction of the polynomials may be
ignored without losing provable NP-Hardness. Both theorems hold even if every
polynomial contains at most three distinct variables. Finally, for the Strong
$c$-partial Gr\"obner Basis Problem of De Loera et al. we give conditional
results that depend on famous (unresolved) conjectures of Khot and Dinur, et
al.


title: Solving 1D Conservation Laws Using Pontryagin's Minimum Principle

abstract:
  This paper discusses a connection between scalar convex conservation laws and
Pontryagin's minimum principle. For flux functions for which an associated
optimal control problem can be found, a minimum value solution of the
conservation law is proposed. For scalar space-independent convex conservation
laws such a control problem exists and the minimum value solution of the
conservation law is equivalent to the entropy solution. This can be seen as a
generalization of the Lax--Oleinik formula to convex (not necessarily uniformly
convex) flux functions. Using Pontryagin's minimum principle, an algorithm for
finding the minimum value solution pointwise of scalar convex conservation laws
is given. Numerical examples of approximating the solution of both
space-dependent and space-independent conservation laws are provided to
demonstrate the accuracy and applicability of the proposed algorithm.
Furthermore, a MATLAB routine using Chebfun is provided (along with
demonstration code on how to use it) to approximately solve scalar convex
conservation laws with space-independent flux functions.


title:
A BHLS model based moment analysis of muon g-2, and its use for lattice
  QCD evaluations of $a_\mu^{\rm had}$

abstract:
  We present an up-to-date analysis of muon $g-2$ evaluations in terms of
Mellin-Barnes moments as they might be useful for lattice QCD calculations of
$a_\mu$. The moments up to 4th order are evaluated directly in terms of
$e^+e^-$--annihilation data and improved within the Hidden Local Symmetry (HLS)
Model, supplied with appropriate symmetry breaking mechanisms. The model
provides a reliable Effective Lagrangian (BHLS) estimate of the two-body
channels plus the $\pi\pi\pi$ channel up to 1.05~GeV, just including the $\phi$
resonance. The HLS piece accounts for 80\% of the contribution to $a_\mu$. The
missing pieces are evaluated in the standard way directly in terms of the data.
We find that the moment expansion converges well in terms of a few moments. The
two types of moments which show up in the Mellin-Barnes representation are
calculated in terms of hadronic cross--section data in the timelike region and
in terms of the hadronic vacuum polarization (HVP) function in the spacelike
region which is accessible to lattice QCD (LQCD). In the Euclidean the first
type of moments are the usual Taylor coefficients of the HVP and we show that
the second type of moments may be obtained as integrals over the appropriately
Taylor truncated HVP function. Specific results for the isovector part of
$a_\mu^{\rm had}$ are determined by means of HLS model predictions in close
relation to $\tau$--decay spectra.


title: Capturing divergence in dependency trees to improve syntactic projection

abstract:
  Obtaining syntactic parses is a crucial part of many NLP pipelines. However,
most of the world's languages do not have large amounts of syntactically
annotated corpora available for building parsers. Syntactic projection
techniques attempt to address this issue by using parallel corpora consisting
of resource-poor and resource-rich language pairs, taking advantage of a parser
for the resource-rich language and word alignment between the languages to
project the parses onto the data for the resource-poor language. These
projection methods can suffer, however, when the two languages are divergent.
In this paper, we investigate the possibility of using small, parallel,
annotated corpora to automatically detect divergent structural patterns between
two languages. These patterns can then be used to improve structural projection
algorithms, allowing for better performing NLP tools for resource-poor
languages, in particular those that may not have large amounts of annotated
data necessary for traditional, fully-supervised methods. While this detection
process is not exhaustive, we demonstrate that common patterns of divergence
can be identified automatically without prior knowledge of a given language
pair, and the patterns can be used to improve performance of projection
algorithms.


title: Atomic metasurfaces for manipulation of single photons

abstract:
  Metasurfaces are an emerging platform for manipulating light on a
two-dimensional plane. Existing metasurfaces comprise arrays of optical
resonators such as plasmonic antennas or high-index nanorods. In this letter,
we describe a new approach to realize metasurfaces based on electronic
transitions in two-level systems (TLSs). These metasurfaces can reproduce all
of the major results in conventional metasurfaces. In addition, since TLSs can
be lossless, tunable, and orders of magnitude smaller than optical resonators,
atomic metasurfaces can realize functions that are difficult to achieve with
optical resonators. Specifically, we develop quantum scattering theory to
describe the interaction between single photons and atomic metasurfaces. Based
on the theory, we use a sheet of three-level {\Lambda}-type atoms as an example
and theoretically demonstrate dynamically tunable single-photon steering. We
further show directional beaming of spontaneously emitted photons from atomic
metasurfaces.


title: Bounded Model Checking for Probabilistic Programs

abstract:
  In this paper we investigate the applicability of standard model checking
approaches to verifying properties in probabilistic programming. As the
operational model for a standard probabilistic program is a potentially
infinite parametric Markov decision process, no direct adaption of existing
techniques is possible. Therefore, we propose an on-the-fly approach where the
operational model is successively created and verified via a step-wise
execution of the program. This approach enables to take key features of many
probabilistic programs into account: nondeterminism and conditioning. We
discuss the restrictions and demonstrate the scalability on several benchmarks.


title: Gabor Barcodes for Medical Image Retrieval

abstract:
  In recent years, advances in medical imaging have led to the emergence of
massive databases, containing images from a diverse range of modalities. This
has significantly heightened the need for automated annotation of the images on
one side, and fast and memory-efficient content-based image retrieval systems
on the other side. Binary descriptors have recently gained more attention as a
potential vehicle to achieve these goals. One of the recently introduced binary
descriptors for tagging of medical images are Radon barcodes (RBCs) that are
driven from Radon transform via local thresholding. Gabor transform is also a
powerful transform to extract texture-based information. Gabor features have
exhibited robustness against rotation, scale, and also photometric
disturbances, such as illumination changes and image noise in many
applications. This paper introduces Gabor Barcodes (GBCs), as a novel framework
for the image annotation. To find the most discriminative GBC for a given query
image, the effects of employing Gabor filters with different parameters, i.e.,
different sets of scales and orientations, are investigated, resulting in
different barcode lengths and retrieval performances. The proposed method has
been evaluated on the IRMA dataset with 193 classes comprising of 12,677 x-ray
images for indexing, and 1,733 x-rays images for testing. A total error score
as low as $351$ ($\approx 80\%$ accuracy for the first hit) was achieved.


title:
Partial Dehn twists of free groups relative to local Dehn twists - a
  dichotomy

abstract:
  A criterion for quadratic or higher growth of group automorphisms is
established which are represented by graph-of-groups automorphisms with certain
well specified properties.
  As a consequence, it is derived (using results of a previous paper of the
author) that every partial Dehn twist automorphism of $\FN$ relative to local
Dehn twist automorphisms is either an honest Dehn twist automorphism, or else
has quadratic growth.


title: Optimal Mock Jacobi Theta Functions

abstract:
  We classify the optimal mock Jacobi forms of weight one with rational
coefficients. The space they span is thirty-four-dimensional, and admits a
distinguished basis parameterized by genus zero groups of isometries of the
hyperbolic plane. We show that their Fourier coefficients can be expressed
explicitly in terms of singular moduli, and obtain positivity conditions which
distinguish the optimal mock Jacobi forms that appear in umbral moonshine. We
find that all of Ramanujan's mock theta functions can be expressed simply in
terms of the optimal mock Jacobi forms with rational coefficients.


title: Anchoring and Agreement in Syntactic Annotations

abstract:
  We present a study on two key characteristics of human syntactic annotations:
anchoring and agreement. Anchoring is a well known cognitive bias in human
decision making, where judgments are drawn towards pre-existing values. We
study the influence of anchoring on a standard approach to creation of
syntactic resources where syntactic annotations are obtained via human editing
of tagger and parser output. Our experiments demonstrate a clear anchoring
effect and reveal unwanted consequences, including overestimation of parsing
performance and lower quality of annotations in comparison with human-based
annotations. Using sentences from the Penn Treebank WSJ, we also report
systematically obtained inter-annotator agreement estimates for English
dependency parsing. Our agreement results control for parser bias, and are
consequential in that they are on par with state of the art parsing performance
for English newswire. We discuss the impact of our findings on strategies for
future annotation efforts and parser evaluations.


title:
Primordial black holes as a novel probe of primordial gravitational
  waves. II: Detailed analysis

abstract:
  Recently we have proposed a novel method to probe primordial gravitational
waves from upper bounds on the abundance of primordial black holes (PBHs). When
the amplitude of primordial tensor perturbations generated in the early
Universe is fairly large, they induce substantial scalar perturbations due to
their second-order effects. If these induced scalar perturbations are too large
when they reenter the horizon, then PBHs are overproduced, their abundance
exceeding observational upper limits. That is, primordial tensor perturbations
on superhorizon scales can be constrained from the absence of PBHs. In our
recent paper we have only shown simple estimations of these new constraints,
and hence in this paper, we present detailed derivations, solving the Einstein
equations for scalar perturbations induced at second order in tensor
perturbations. We also derive an approximate formula for the probability
density function of induced density perturbations, necessary to relate the
abundance of PBHs to the primordial tensor power spectrum, assuming primordial
tensor perturbations follow Gaussian distributions. Our new upper bounds from
PBHs are compared with other existing bounds obtained from big bang
nucleosynthesis, cosmic microwave background, LIGO/Virgo and pulsar timing
arrays.


title:
The Vanishing Pressure Limits of Riemann Solutions to the Chaplygin
  Euler Equations

abstract:
  The Riemann solutions to Chaplygin Euler equations with a scaled pressure are
considered. When the pressure vanishes, there are three cases. The Riemann
solution containing two shock waves converges to the delta shock wave solution
of the transport equations. During this process, both the strength and
propagation speed of the delta shock are investigated in detail. We find that
there is something different from that for polytropic or isothermal gas. The
Riemann solution containing two rarefaction waves tends to the two contact
discontinuity solution to the transport equations as the pressure goes to zero.
The intermediate state between the two contact discontinuities is a vacuum
state. The Riemann solution containing one rarefaction wave and one shock wave
tends to the contact discontinuity solution to transport equations as the
pressure vanishes.


title: Relative exchangeability with equivalence relations

abstract:
  We describe an Aldous--Hoover-type characterization of random relational
structures that are exchangeable relative to a fixed structure which may have
various equivalence relations. Our main theorem gives the common generalization
of the results on relative exchangeability due to Ackerman \cite{Ackerman2015}
and Crane and Towsner \cite{CraneTowsner2015} and hierarchical exchangeability
results due to Austin and Panchenko \cite{AustinPanchenko2014}.


title:
Equilibration and aging of liquids of non-spherically interacting
  particles

abstract:
  The non-equilibrium self-consistent generalized Langevin equation theory of
irreversible processes in liquids is extended to describe the positional and
orientational thermal fluctuations of the instantaneous local concentration
profile $n(\mathbf{r},\Omega,t)$ of a suddenly-quenched colloidal liquid of
particles interacting through non spherically-symmetric pairwise interactions,
whose mean value $\overline{n}(\mathbf{r},\Omega,t)$ is constrained to remain
uniform and isotropic, $\overline{n}(\mathbf{r},\Omega,t)=\overline{n}(t)$.
Such self-consistent theory is cast in terms of the time-evolution equation of
the covariance $\sigma(t)=\overline{\delta n_{lm}(\mathbf{k};t) \delta
n^{\dagger}_{lm}(\mathbf{k};t)}$ of the fluctuations $\delta
n_{lm}(\mathbf{k};t)=n_{lm}(\mathbf{k};t) -\overline{n_{lm}}(\mathbf{k};t)$ of
the spherical harmonics projections $n_{lm}(\mathbf{k};t)$ of the Fourier
transform of $n(\mathbf{r},\Omega,t)$. The resulting theory describes the
non-equilibrium evolution after a sudden temperature quench of both, the static
structure factor projections $S_{lm}(k,t)$ and the two-time correlation
function $F_{lm}(k,\tau;t)\equiv\overline{\delta n_{lm}(\mathbf{k},t)\delta
n_{lm}(\mathbf{k},t+\tau)}$, where $\tau$ is the correlation \emph{delay} time
and $t$ is the \emph{evolution} or \emph{waiting} time after the quench. As a
concrete and illustrative application we use the resulting self-consistent
equations to describe the irreversible processes of equilibration or aging of
the orientational degrees of freedom of a system of strongly interacting
classical dipoles with quenched positional disorder.


title: Sending a Message with Unknown Noise

abstract:
  Alice and Bob are connected via a two-way channel, and Alice wants to send a
message of $L$ bits to Bob. An adversary flips an arbitrary but finite number
of bits, $T$, on the channel. This adversary knows our algorithm and Alice's
message, but does not know any private random bits generated by Alice or Bob,
nor the bits sent over the channel, except when these bits can be predicted by
knowledge of Alice's message or our algorithm. We want Bob to receive Alice's
message and for both players to terminate, with error probability at most
$\delta > 0$, where $\delta$ is a parameter known to both Alice and Bob.
Unfortunately, the value $T$ is unknown in advance to either Alice or Bob, and
the value $L$ is unknown in advance to Bob. We describe an algorithm to solve
the above problem while sending an expected $L + O \left( T + \min
\left(T+1,\frac{L}{\log L} \right) \log \left( \frac{L}{\delta} \right)
\right)$ bits. A special case is when $\delta = O(1/L^c)$, for some constant
$c$. Then when $T = o(L/\log L)$, the expected number of bits sent is $L +
o(L)$, and when $T = \Omega(L)$, the expected number of bits sent is $L +
O\left( T \right)$, which is asymptotically optimal.


title:
Study of Relay Selection for Physical-Layer Security in Buffer-Aided
  Relay Networks Based on the Secrecy Rate Criterion

abstract:
  In this paper, we investigate an opportunistic relay and jammer scheme along
with relay selection algorithms based on the secrecy rate criterion in
multiple-input multiple-output buffer-aided down link relay networks, which
consist of one source, a number of relay nodes, legitimate users and
eavesdroppers, with the constraints of physical layer security. The
opportunistic relay and jammer scheme is employed to improve the transmission
rate and different relay selection policies are performed to achieve better
secrecy rate with the consideration of eavesdroppers. Among all the
investigated relay selection policies, a relay selection policy which is
developed to maximize the secrecy rate based on exhaustive searches outperforms
other relay selection policies in terms of secrecy rate. Based on the secrecy
rate criterion, we develop a relay selection algorithm without knowledge of the
channels of the eavesdroppers. We also devise a greedy search algorithm based
on the secrecy rate criterion to reduce the computational complexity of the
exhaustive search technique. Simulations show the superiority of the secrecy
rate criterion over competing approaches.


title: The Accretion Flow - Discrete Ejection Connection in GRS 1915+105

abstract:
  The microquasar GRS~1915+105 is known for its spectacular discrete ejections.
They occur unexpectedly, thus their inception escapes direct observation. It
has been shown that the X-ray flux increases in the hours leading up to a major
ejection. In this article, we consider the serendipitous interferometric
monitoring of a modest version of a discrete ejection described in Reid et al.
(2014) that would have otherwise escaped detection in daily radio light curves.
The observation begins $\sim 1$ hour after the onset of the ejection, providing
unprecedented accuracy on the estimate of the ejection time. The astrometric
measurements allow us to determine the time of ejection as $\rm{MJD}\,
56436.274^{+0.016}_{-0.013}$, i.e., within a precision of 41 minutes (95\%
confidence). Just like larger flares, we find that the X-ray luminosity
increases in last 2 - 4 hours preceding ejection. Our finite temporal
resolution indicates that this elevated X-ray flux persists within
$21.8^{+22.6}_{-19.1}$ minutes of the ejection with 95\% confidence, the
highest temporal precision of the X-ray - superluminal ejection connection to
date. This observation provides direct evidence that the physics that launches
major flares occurs on smaller scales as well (lower radio flux and shorter
ejection episodes). The observation of a X-ray spike prior to a discrete
ejection, although of very modest amplitude suggests that the process linking
accretion behavior to ejection is general from the smallest scales to high
luminosity major superluminal flares.


title: Lax distributive laws for topology, II

abstract:
  For a small quantaloid $\mathcal{Q}$ we consider four fundamental 2-monads
$\mathbb{T}$ on $\mathcal{Q}\text{-}{\bf Cat}$, given by the presheaf 2-monad
$\mathbb{P}$ and the copresheaf 2-monad $\mathbb{P}^{\dagger}$, as well as by
their two composite 2-monads, and establish that they all laxly distribute over
$\mathbb{P}$. These four 2-monads therefore admit lax extensions to the
category $\mathcal{Q}\text{-}{\bf Dist}$ of $\mathcal{Q}$-categories and their
distributors. We characterize the corresponding
$(\mathbb{T},\mathcal{Q})$-categories in each of the four cases, leading us to
both known and novel categorical structures.


title:
Boundary conditions for General Relativity on AdS$_{3}$ and the KdV
  hierarchy

abstract:
  It is shown that General Relativity with negative cosmological constant in
three spacetime dimensions admits a new family of boundary conditions being
labeled by a nonnegative integer $k$. Gravitational excitations are then
described by "boundary gravitons" that fulfill the equations of the $k$-th
element of the KdV hierarchy. In particular, $k=0$ corresponds to the
Brown-Henneaux boundary conditions so that excitations are described by chiral
movers. In the case of $k=1$, the boundary gravitons fulfill the KdV equation
and the asymptotic symmetry algebra turns out to be infinite-dimensional,
abelian and devoid of central extensions. The latter feature also holds for the
remaining cases that describe the hierarchy ($k>1$). Our boundary conditions
then provide a gravitational dual of two noninteracting left and right KdV
movers, and hence, boundary gravitons possess anisotropic Lifshitz scaling with
dynamical exponent $z=2k+1$. Remarkably, despite spacetimes solving the field
equations are locally AdS, they possess anisotropic scaling being induced by
the choice of boundary conditions. As an application, the entropy of a rotating
BTZ black hole is precisely recovered from a suitable generalization of the
Cardy formula that is compatible with the anisotropic scaling of the chiral KdV
movers at the boundary, in which the energy of AdS spacetime with our boundary
conditions depends on $z$ and plays the role of the central charge. The
extension of our boundary conditions to the case of higher spin gravity and its
link with different classes of integrable systems is also briefly addressed.


title: Improved distance sensitivity oracles via tree partitioning

abstract:
  We introduce an improved structure of distance sensitivity oracle (DSO). The
task is to pre-process a non-negatively weighted graph so that a data structure
can quickly answer replacement path length for every triple of source, terminal
and failed vertex. The previous best algorithm constructs in time
$\tilde{O}(mn)$ a distance sensitivity oracle of size $O(n^2\log n)$ that
processes queries in $O(1)$ time. As an improvement, our oracle takes up
$O(n^2)$ space, while preserving $O(1)$ query efficiency and $\tilde{O}(mn)$
preprocessing time. One should notice that space complexity and query time of
our novel data structure are asymptotically optimal.


title:
Identifying and removing the cell-cycle effect from single-cell
  RNA-Sequencing data

abstract:
  Single-cell RNA-Sequencing (scRNA-Seq) is a revolutionary technique for
discovering and describing cell types in heterogeneous tissues, yet its
measurement of expression often suffers from large systematic bias. A major
source of this bias is the cell cycle, which introduces large within-cell-type
heterogeneity that can obscure the differences in expression between cell
types. The current method for removing the cell-cycle effect is unable to
effectively identify this effect and has a high risk of removing other
biological components of interest, compromising downstream analysis. We present
ccRemover, a new method that reliably identifies the cell-cycle effect and
removes it. ccRemover preserves other biological signals of interest in the
data and thus can serve as an important pre-processing step for many scRNA-Seq
data analyses. The effectiveness of ccRemover is demonstrated using simulation
data and three real scRNA-Seq datasets, where it boosts the performance of
existing clustering algorithms in distinguishing between cell types.


title:
Laser structuring for control of coupling between THz light and phonon
  modes

abstract:
  Modification of surface and volume of sapphire is shown to affect reflected
and transmitted light at THz spectral range. Structural modifications were made
using ultra-short 230 fs laser pulses at 1030 nm and 257.5 nm wavelengths
forming surface ripples of ~250 nm and 60 nm period, respectively. Softening of
the transverse optical phonon TO1 mode due to disorder was the most pronounced
in reflection from laser ablated surface. It is shown that sub-surface periodic
patterns of laser damage sites have also modified reflection spectrum due to
coupling of THz radiation with phonons. Application potential of laser
structuring and disordering for phononic engineering is discussed.


title:
Probabilistic Deep Spiking Neural Systems Enabled by Magnetic Tunnel
  Junction

abstract:
  Deep Spiking Neural Networks are becoming increasingly powerful tools for
cognitive computing platforms. However, most of the existing literature on such
computing models are developed with limited insights on the underlying hardware
implementation, resulting in area and power expensive designs. Although several
neuromimetic devices emulating neural operations have been proposed recently,
their functionality has been limited to very simple neural models that may
prove to be inefficient at complex recognition tasks. In this work, we venture
into the relatively unexplored area of utilizing the inherent device
stochasticity of such neuromimetic devices to model complex neural
functionalities in a probabilistic framework in the time domain. We consider
the implementation of a Deep Spiking Neural Network capable of performing high
accuracy and low latency classification tasks where the neural computing unit
is enabled by the stochastic switching behavior of a Magnetic Tunnel Junction.
Simulation studies indicate an energy improvement of $20\times$ over a baseline
CMOS design in $45nm$ technology.