title: A Strongly Quasiconvex PAC-Bayesian Bound

abstract:
  We propose a new PAC-Bayesian bound and a way of constructing a hypothesis
space, so that the bound is convex in the posterior distribution and also
convex in a trade-off parameter between empirical performance of the posterior
distribution and its complexity. The complexity is measured by the
Kullback-Leibler divergence to a prior. We derive an alternating procedure for
minimizing the bound. We show that the bound can be rewritten as a
one-dimensional function of the trade-off parameter and provide sufficient
conditions under which the function has a single global minimum. When the
conditions are satisfied the alternating minimization is guaranteed to converge
to the global minimum of the bound. We provide experimental results
demonstrating that rigorous minimization of the bound is competitive with
cross-validation in tuning the trade-off between complexity and empirical
performance. In all our experiments the trade-off turned to be quasiconvex even
when the sufficient conditions were violated.


title: Nonlinear light-matter interaction at terahertz frequencies

abstract:
  Strong optical pulses at mid-infrared and terahertz frequencies have recently
emerged as a powerful tool to manipulate and control the solid state and
especially complex condensed matter systems with strongly correlated electrons.
The recent developments in high-power sources in the 0.1-30 THz frequency
range, both from table-top laser systems and Free-Electron Lasers, has provided
access to excitations of molecules and solids, which can be stimulated at their
resonance frequencies. Amongst these, we discuss free electrons in metals,
superconducting gaps and Josephson plasmons in layered superconductors,
vibrational modes of the crystal lattice (phonons), as well as magnetic
excitations. This Review provides an overview and illustrative examples of how
intense THz transients can be used to resonantly control matter, with
particular focus on strongly correlated electron systems and high-temperature
superconductors.


title:
A BKR operation for events occurring for disjoint reasons with high
  probability

abstract:
  Given events $A$ and $B$ on a product space $S=\prod_{i=1}^n S_i$, the set $A
\Box B$ consists of all vectors ${\bf x}=(x_1,\ldots,x_n) \in S$ for which
there exist disjoint coordinate subsets $K$ and $L$ of $\{1,\ldots,n\}$ such
that given the coordinates $x_i, i \in K$ one has that ${\bf x} \in A$
regardless of the values of ${\bf x}$ on the remaining coordinates, and
likewise that ${\bf x} \in B$ given the coordinates {$x_j, j \in L$}.
  For a finite product of discrete spaces endowed with a product measure, the
BKR inequality
  $$
  P(A \Box B) \le P(A)P(B) \quad (1)
  $$
  was conjectured by van den Berg and Kesten [3] and proved by Reimer [13].
  In [7] inequality (1) was extended to general product probability spaces,
replacing $A \Box B$ by the set $A \Box_{11} B$ consisting of those outcomes
${\bf x}$ which only assure with probability one that ${\bf x} \in A$ and ${\bf
x} \in B$ based only on the revealed coordinates in $K$ and $L$ as above. A
strengthening of the original BKR inequality (1) results, due to the fact that
$A \Box B \subseteq A \Box_{11} B$. In particular, it may be the case that $A
\Box B$ is empty, while $A \Box_{11} B$ is not.
  We propose the further extension $A \Box_{st} B$ depending on probability
thresholds $s$ and $t$, where $A \Box_{11} B$ is the special case where both
$s$ and $t$ take the value one. The outcomes ${\bf x}$ in $A \Box_{st} B$ are
those for which disjoint sets of coordinates $K$ and $L$ exist such that given
the values of $\bf x$ on the revealed set of coordinates $K$, the probability
that $A$ occurs is at least $s$, and given the coordinates of $\bf x$ in $L$,
the probability of $B$ is at least $t$. We provide simple examples that
illustrate the utility of these extensions.


title: A short-key one-time pad cipher

abstract:
  A process for the secure transmission of data is presented that has to a
certain degree the advantages of the one-time pad (OTP) cipher, that is,
simplicity, speed, and information-theoretically security, but overcomes its
fundamental weakness, the necessity of securely exchanging a key that is as
long as the message. For each transmission, a dedicated one-time pad is
generated for encrypting and decrypting the plaintext message. This one-time
pad is built from a randomly chosen set of basic keys taken from a public
library. Because the basic keys can be chosen and used multiple times, the
method is called multiple-time pad (MTP) cipher. The information on the choice
of basic keys is encoded in a short keyword that is transmitted by secure
means. The process is made secure against known-plaintext attack by additional
design elements. The process is particularly useful for high-speed transmission
of mass data and video or audio streaming.


title:
All measurements in a probabilistic theory are compatible if and only if
  the state space is a simplex

abstract:
  We study the compatibility of measurements on finite-dimensional compact
convex state space in the framework of general probabilistic theory. Our main
emphasis is on formulation of necessary and sufficient conditions for
two-outcome measurements to be compatible and we use these conditions to show
that there exist incompatible measurements whenever the state space is not a
simplex. We also formulate the linear programming problem for the compatibility
of two-outcome measurements.


title:
Neutron matter from chiral two- and three-nucleon calculations up to
  N$^3$LO

abstract:
  Neutron matter is an ideal laboratory for nuclear interactions derived from
chiral effective field theory since all contributions are predicted up to
next-to-next-to-next-to-leading order (N$^3$LO) in the chiral expansion. By
making use of recent advances in the partial-wave decomposition of three-
nucleon (3N) forces, we include for the first time N$^3$LO 3N interactions in
many-body perturbation theory (MBPT) up to third order and in self-consistent
Green's function theory (SCGF). Using these two complementary many-body
frameworks we provide improved predictions for the equation of state of neutron
matter at zero temperature and also analyze systematically the many-body
convergence for different chiral EFT interactions. Furthermore, we present an
extension of the normal-ordering framework to finite temperatures. These
developments open the way to improved calculations of neutron-rich matter
including estimates of theoretical uncertainties for astrophysical
applications.


title: Observation of a dynamical topological phase transition

abstract:
  Phase transitions are a fundamental concept in science describing diverse
phenomena ranging from, e.g., the freezing of water to Bose-Einstein
condensation. While the concept is well-established in equilibrium, similarly
fundamental concepts for systems far from equilibrium are just being explored,
such as the recently introduced dynamical phase transition (DPT). Here we
report on the first observation of a DPT in the dynamics of a fermionic
many-body state after a quench between two lattice Hamiltonians. With
time-resolved state tomography in a system of ultracold atoms in optical
lattices, we obtain full access to the evolution of the wave function. We
observe the appearance, movement, and annihilation of vortices in reciprocal
space. We identify their number as a dynamical topological order parameter,
which suddenly changes its value at the critical times of the DPT. Our
observation of a DPT is an important step towards a more comprehensive
understanding of non-equilibrium dynamics in general.


title: CurryCheck: Checking Properties of Curry Programs

abstract:
  We present CurryCheck, a tool to automate the testing of programs written in
the functional logic programming language Curry. CurryCheck executes unit tests
as well as property tests which are parameterized over one or more arguments.
In the latter case, CurryCheck tests these properties by systematically
enumerating test cases so that, for smaller finite domains, CurryCheck can
actually prove properties. Unit tests and properties can be defined in a Curry
module without being exported. Thus, they are also useful to document the
intended semantics of the source code. Furthermore, CurryCheck also supports
the automated checking of specifications and contracts occurring in source
programs. Hence, CurryCheck is a useful tool that contributes to the property-
and specification-based development of reliable and well tested declarative
programs.


title:
Non-perturbative linked-cluster expansions in long-range ordered quantum
  systems

abstract:
  We introduce a generic scheme to perform non-perturbative linked cluster
expansions in long-range ordered quantum phases. Clusters are considered to be
surrounded by an ordered reference state leading to effective edge-fields in
the exact diagonalization on clusters which break the associated symmetry of
the ordered phase. Two approaches, based either on a self-consistent solution
of the order parameter or on minimal sensitivity with respect to the
ground-state energy per site, are formulated to find the optimal edge-field in
each NLCE order. Furthermore, we investigate the scaling behavior of the NLCE
data sequences towards the infinite-order limit. We apply our scheme to gapped
and gapless ordered phases of XXZ Heisenberg models on various lattices and for
spins 1/2 and 1 using several types of cluster expansions ranging from a
full-graph decomposition, rectangular clusters, up to more symmetric square
clusters. It is found that the inclusion of edge-fields allows to regularize
non-perturbative linked-cluster expansions in ordered phases yielding
convergent data sequences. This includes the long-range spin-ordered ground
state of the spin-1/2 and spin-1 Heisenberg model on the square and triangular
lattice as well as the trimerized valence bond crystal of the spin-1 Heisenberg
model on the kagome lattice.


title: Symbolic Abstract Contract Synthesis in a Rewriting Framework

abstract:
  We propose an automated technique for inferring software contracts from
programs that are written in a non-trivial fragment of C, called KernelC, that
supports pointer-based structures and heap manipulation. Starting from the
semantic definition of KernelC in the K framework, we enrich the symbolic
execution facilities recently provided by K with novel capabilities for
assertion synthesis that are based on abstract subsumption. Roughly speaking,
we define an abstract symbolic technique that explains the execution of a
(modifier) C function by using other (observer) routines in the same program.
We implemented our technique in the automated tool KindSpec 2.0, which
generates logical axioms that express pre- and post-condition assertions by
defining the precise input/output behaviour of the C routines.


title:
Weak convergence to extremal processes and record events for
  non-uniformly hyperbolic dynamical systems

abstract:
  For a measure preserving dynamical system $(\mathcal{X},f, \mu)$, we consider
the time series of maxima $M_n=\max\{X_1,\ldots,X_n\}$ associated to the
process $X_n=\phi(f^{n-1}(x))$ generated by the dynamical system for some
observable $\phi:\mathcal{X}\to\mathbb{R}$. Using a point process approach we
establish weak convergence of the process $Y_n(t)=a_n(M_{[nt]}-b_n)$ to an
extremal process $Y(t)$ for suitable scaling constants $a_n,b_n\in\mathbb{R}$.
Convergence here taking place in the Skorokhod space $\mathbb{D}(0,\infty)$
with the $J_1$ topology. We also establish distributional results for the
record times and record values of the corresponding maxima process.


title: Polaronic behavior in a weak coupling superconductor

abstract:
  The nature of superconductivity in the dilute semiconductor SrTiO$_3$ has
remained an open question for more than 50 years. The extremely low carrier
densities ($10^{18}$ - $10^{20}$ cm$^{-3}$) at which superconductivity occurs
suggests an unconventional origin of superconductivity outside of the adiabatic
limit on which the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg (ME)
theories are based. We take advantage of a newly developed method for
engineering band alignments at oxide interfaces and access the electronic
structure of Nb-doped SrTiO$_3$ using high resolution tunneling spectroscopy.
We observe strong coupling to the highest energy longitudinal optic (LO) phonon
branch and estimate the doping evolution of the dimensionless electron-phonon
interaction strength ($\lambda$). Upon cooling below the superconducting
transition temperature ($T_{\mathrm{c}}$), we observe a single superconducting
gap corresponding to the weak-coupling limit of BCS theory, indicating an order
of magnitude smaller coupling ($\lambda_{\textrm{BCS}} \approx 0.1$). These
results suggest that despite the strong normal state interaction with
electrons, the highest LO phonon does not provide a dominant contribution to
pairing. They further demonstrate that SrTiO$_3$ is an ideal system to probe
superconductivity over a wide range of carrier density, adiabatic parameter,
and electron-phonon coupling strength.


title: Scalability of frames generated by dynamical operators

abstract:
  Let $A$ be an operator on {a separable } Hilbert space $\cH$, and let $G
\subset \cH$. It is known that - under appropriate conditions on $A$ and $G$ -
the set of iterations $F_G(A)= \{A^j \gbf \; | \; \gbf \in G, \; 0 \leq j \leq
L(\gbf) \} $ is a frame for $\cH$. We call $F_G(A)$ a dynamical frame for
$\cH$, and explore further its properties; in particular, we show that the
canonical dual frame of $F_G(A)$ also has an iterative set structure.
  We explore the relations between the operator $A$, the set $G$ and the number
of iterations $L$ which ensure that the system $F_G(A)$ is a scalable frame. We
give a general statement on frame scalability, We and study in detail the case
when $A$ is a normal operator, utilizing the unitary diagonalization in finite
dimensions. In addition, we answer the question of when $F_G(A)$ is a scalable
frame in several special cases involving block-diagonal and companion
operators.


title:
Electromagnetic reflection, transmission and energy density at
  boundaries of nonlocal media

abstract:
  We consider a semi-infinite spatially dispersive dielectric with unequal
transverse and longitudinal susceptibilities. The effect of the boundary is
characterized by arbitrary reflection coefficients for polarization waves in
the material that propagate to the surface. Specific values of these
coefficients correspond to various additional boundary conditions (ABC) for
Maxwell's equations. We derive the electromagnetic reflection and transmission
coefficients at the boundary and investigate their dependence on material
parameters and ABC. We also investigate the electromagnetic zero-point and
thermal spectral energy density outside the dielectric. The nonlocal response
removes the boundary divergence of the spectral energy density that is present
in a local model. The spectral energy density shows a large dependence on the
difference between the transverse and longitudinal susceptibilities, even at
distances up to 10nm from the boundary.


title: Stream-subhalo interactions in the Aquarius simulations

abstract:
  We perform the first self-consistent measurement of the rate of interactions
between stellar tidal streams created by disrupting satellites and dark
subhalos in a cosmological simulation of a Milky-Way-mass galaxy. Using a
retagged version of the Aquarius A dark-matter-only simulation, we selected 18
streams of tagged star particles that appear thin at the present day and
followed them from the point their progenitors accrete onto the main halo,
recording in each snapshot the characteristics of all dark-matter subhalos
passing within several distance thresholds of any tagged star particle in each
stream. We considered distance thresholds corresponding to constant impact
parameters (1, 2, and 5 kpc), as well as those proportional to the region of
influence of each subhalo (one and two times its half-mass radius $r_{1/2}$).
We then measured the age and present-day, phase-unwrapped length of each stream
in order to compute the interaction rate in different mass bins and for
different thresholds, and compared these to analytic predictions from the
literature. We measure a median rate of $1.5^{+3.0}_{-1.1}\
(9.1^{+17.5}_{-7.1},\ 61.8^{+211}_{-40.6})$ interactions within 1 (2, 5) kpc of
the stream per 10 kpc of stream length per 10 Gyr. Resolution effects (both
time and particle number) affect these estimated rates by lowering them.


title: The maximal excess charge in M\"uller density-matrix-functional theory

abstract:
  We consider an atom described by M\"uller theory, which is similar to
Hartree-Fock theory, but with a modified exchange term. We prove that a nucleus
of charge Z can bind at most Z+C electrons, where C is a universal constant.
Our proof proceeds by comparison with Thomas-Fermi theory and a key ingredient
is a novel bound on the number of electrons far from the nucleus.


title:
Activation of new Raman modes by inversion symmetry breaking in type II
  Weyl semimetal candidate T'-MoTe2

abstract:
  We synthesized distorted octahedral(T') molybdenum ditelluride (MoTe2) and
investigated its vibrational properties with Raman spectroscopy, density
functional theory and symmetry analysis. Compared to the results from high
temperature centrosymmetric monoclinic (T'mo) phase, four new Raman bands
emerge in the low temperature orthorhombic (T'or) phase, which was recently
predicted to be a type II Weyl semimetal. Crystal-angle-dependent,
light-polarization-resolved measurements indicate that all the observed Raman
peaks belong to two categories: those vibrating along the zigzag Mo atomic
chain (z-mode) and those vibrating in the mirror plane (m-mode) perpendicular
to the zigzag chain. Interestingly the low energy shear z-mode and shear
m-mode, absent from the T'mo spectra, become activated when sample cooling
induces a phase transition to the T'or crystal structure. We interpret this
observation as a consequence of inversion-symmetry breaking, which is crucial
for the existence of Weyl fermions in the layered crystal. Our temperature
dependent Raman measurements further show that both the high energy m-mode at
130 cm-1 and the low energy shear m-mode at 12 cm-1 provide useful gauges for
monitoring the broken inversion symmetry in the crystal.


title:
Automorphisms of positive entropy on some hyperKahler manifolds via
  derived automorphisms of K3 surfaces

abstract:
  We construct examples of hyperKahler manifolds of Picard number two with
automorphisms of positive entropy via derived automorphisms of K3 surfaces of
Picard number one. Our hyperKahler manifolds are constructed as moduli spaces
of Bridgeland stable objects in derived categories of K3 surfaces. Then
automorphisms of positive entropy are induced by derived automorphisms of
positive entropy on K3 surfaces.


title:
Competing Exchange Interactions in the Multiferroic and Ferrimagnetic
  CaBaCo$_4$O$_7$

abstract:
  Competing exchange interactions can produce complex magnetic states together
with spin-induced electric polarizations. With competing interactions on
alternating triangular and kagome layers, the swedenborgite CBO may have one of
the largest measured spin-induced polarizations of about 1700 nC/cm$^2$ below
its ferrimagnetic transition temperature at 70 K. Powder neutron-diffraction
data, magnetization measurements, and spin-wave resonance frequencies in the
THz range reveal that the complex spin order of multiferroic CBO can be
described as a triangular array of c-axis chains ferrimagnetically coupled to
each other in the ab plane. Magnetostriction on bonds that couple those chains
produces the large spin-induced polarization of CBO.


title: Simplicial Complexes are Game Complexes

abstract:
  Strong placement games (SP-games) are a class of combinatorial games whose
structure allows one to describe the game via simplicial complexes. A natural
question is whether well-known invariants of combinatorial games, such as "game
value", appear as invariants of the simplicial complexes. This paper is the
first step in that direction. We show that every simplicial complex encodes a
certain type of SP-game (called an "invariant SP-game") whose ruleset is
independent of the board it is played on. We also show that in the class of
SP-games isomorphic simplicial complexes correspond to isomorphic game trees,
and hence equal game values. We also study a subclass of SP-games corresponding
to flag complexes, showing that there is always a game whose corresponding
complex is a flag complex no matter which board it is played on.


title: Asymptotic dynamics, large gauge transformations and infrared symmetries

abstract:
  Infrared divergences in QED and other theories with massless particles show
that in such theories the $S$ matrix cannot be defined in the usual way.
Typically, this is not viewed as a big problem since one is interested in cross
sections, in which the divergences cancel. Recently, one particular type of
divergences known as soft theorems was connected to a symmetry principle - the
antipodal matching of large gauge transformations. However, there is a way to
define an IR finite $S$ matrix in QED and similar theories by dropping the
assumption of trivial asymptotic dynamics. In the present paper we investigate
the role of soft theorems and invariance under large gauge transformations in
the context of the finite $S$ matrix. Before doing so, the construction of
asymptotic dynamics is reviewed and extended. The key results are that
subleading soft factors can be included in a natural way in the asymptotic
dynamics. Once this is done, soft modes decouple from the IR finite $S$ matrix
and this decoupling, which can be understood as a spontaneously broken
symmetry, is equivalent to the invariance under large gauge transformations (or
in other words to the antipodal matching). To show this equivalence a special
property for field operators at null infinity, i.e. for the program of
asymptotic quantization, is assumed. Finally, we speculate about the
modification of the decoupling of soft modes in the presence of black holes.


title: Phase Singularities in Complex Arithmetic Random Waves

abstract:
  Complex arithmetic random waves are stationary Gaussian complex-valued
solutions of the Helmholtz equation on the two-dimensional flat torus. We use
Wiener-It\^o chaotic expansions in order to derive a complete characterization
of the second order high-energy behaviour of the total number of phase
singularities of these functions. Our main result is that, while such random
quantities verify a universal law of large numbers, they also exhibit
non-universal and non-central second order fluctuations that are dictated by
the arithmetic nature of the underlying spectral measures. Such fluctuations
are qualitatively consistent with the cancellation phenomena predicted by Berry
(2002) in the case of complex random waves on compact planar domains. Our
results extend to the complex setting recent pathbreaking findings by Rudnick
and Wigman (2008), Krishnapur, Kurlberg and Wigman (2013) and Marinucci,
Peccati, Rossi and Wigman (2016). The exact asymptotic characterization of the
variance is based on a fine analysis of the Kac-Rice kernel around the origin,
as well as on a novel use of combinatorial moment formulae for controlling
long-range weak correlations.


title:
The KdV, the Burgers, and the Whitham limit for a spatially periodic
  Boussinesq model

abstract:
  We are interested in the Korteweg-de Vries (KdV), the Burgers, and the
Whitham limit for a spatially periodic Boussinesq model with non-small
contrast. We prove estimates between the KdV, the Burgers, and the Whitham
approximation and true solutions of the original system which guarantee that
these amplitude equations make correct predictions about the dynamics of the
spatially periodic Boussinesq model over the natural time scales of the
amplitude equations. The proof is based on Bloch wave analysis and energy
estimates. The result is the first justification result of the KdV, the
Burgers, and the Whitham approximation for a dispersive PDE posed in a
spatially periodic medium of non-small contrast.


title:
Surface Fermi arc connectivity in the type-II Weyl semimetal candidate
  WTe$_{2}$

abstract:
  We perform ultrahigh resolution angle-resolved photoemission experiments at a
temperature T=0.8 K on the type-II Weyl semimetal candidate WTe$_{2}$. We find
a surface Fermi arc connecting the bulk electron and hole pockets on the (001)
surface. Our results show that the surface Fermi arc connectivity to the bulk
bands is strongly mediated by distinct surface resonances dispersing near the
border of the surface-projected bulk band gap. By comparing the experimental
results to first-principles calculations we argue that the coupling to these
surface resonances, which are topologically trivial, is compatible with the
classification of WTe$_{2}$ as a type-II Weyl semimetal hosting topological
Fermi arcs. We further support our conclusion by a systematic characterization
of the bulk and surface character of the different bands and discuss the
similarity of our findings to the case of topological insulators.


title:
Thrill: High-Performance Algorithmic Distributed Batch Data Processing
  with C++

abstract:
  We present the design and a first performance evaluation of Thrill -- a
prototype of a general purpose big data processing framework with a convenient
data-flow style programming interface. Thrill is somewhat similar to Apache
Spark and Apache Flink with at least two main differences. First, Thrill is
based on C++ which enables performance advantages due to direct native code
compilation, a more cache-friendly memory layout, and explicit memory
management. In particular, Thrill uses template meta-programming to compile
chains of subsequent local operations into a single binary routine without
intermediate buffering and with minimal indirections. Second, Thrill uses
arrays rather than multisets as its primary data structure which enables
additional operations like sorting, prefix sums, window scans, or combining
corresponding fields of several arrays (zipping). We compare Thrill with Apache
Spark and Apache Flink using five kernels from the HiBench suite. Thrill is
consistently faster and often several times faster than the other frameworks.
At the same time, the source codes have a similar level of simplicity and
abstraction


title:
Long-range magnetic order and interchain interactions in the $S=2$ chain
  system MnCl$_3$(bpy)

abstract:
  A compound with very weakly interacting chains, MnCl$_3$(bpy), has attracted
a great deal of attention as a possible $S=2$ Haldane chain. However,
long-range magnetic order of the chains prevents the Haldane gap from
developing below 11.5~K. Based on a four-sublattice model, a description of the
antiferromagnetic resonance (AFMR) spectrum up to frequencies of 1.5~THz and
magnetic fields up to 50~T indicates that the interchain coupling is indeed
quite small but that the Dzaloshinskii-Moriya interaction produced by broken
inversion symmetry is substantial (0.12~meV). In addition, the
antiferromagnetic, nearest-neighbor interaction within each chain (3.3~meV) is
significantly stronger than previously reported. The excitation spectrum of
this $S=2$ compound is well-described by a $1/S$ expansion about the classical
limit.


title:
An autocorrelation and discrete spectrum for dynamical systems on metric
  spaces

abstract:
  We study dynamical systems $(X,G,m)$ with a compact metric space $X$ and a
locally compact, $\sigma$-compact, abelian group $G$. We show that such a
system has discrete spectrum if and only if a certain space average over the
metric is a Bohr almost periodic function. In this way, this average over the
metric plays for general dynamical systems a similar role as the
autocorrelation measure plays in the study of aperiodic order for special
dynamical systems based on point sets.


title:
Polynomial Kernels and Wideness Properties of Nowhere Dense Graph
  Classes

abstract:
  Nowhere dense classes of graphs are very general classes of uniformly sparse
graphs with several seemingly unrelated characterisations. From an algorithmic
perspective, a characterisation of these classes in terms of uniform
quasi-wideness, a concept originating in finite model theory, has proved to be
particularly useful. Uniform quasi-wideness is used in many fpt-algorithms on
nowhere dense classes. However, the existing constructions showing the
equivalence of nowhere denseness and uniform quasi-wideness imply a
non-elementary blow up in the parameter dependence of the fpt-algorithms,
making them infeasible in practice.
  As a first main result of this paper, we use tools from logic, in particular
from a subfield of model theory known as stability theory, to establish
polynomial bounds for the equivalence of nowhere denseness and uniform
quasi-wideness.
  A powerful method in parameterized complexity theory is to compute a problem
kernel in a pre-computation step, that is, to reduce the input instance in
polynomial time to a sub-instance of size bounded in the parameter only
(independently of the input graph size). Our new tools allow us to obtain for
every fixed value of $r$ a polynomial kernel for the distance-$r$ dominating
set problem on nowhere dense classes of graphs. This result is particularly
interesting, as it implies that for every class $\mathcal{C}$ of graphs which
is closed under subgraphs, the distance-$r$ dominating set problem admits a
kernel on $\mathcal{C}$ for every value of $r$ if, and only if, it admits a
polynomial kernel for every value of $r$ (under the standard assumption of
parameterized complexity theory that $\mathrm{FPT} \neq W[2]$).


title:
Measurements and analysis of current-voltage characteristic of a pn
  diode for an undergraduate physics laboratory

abstract:
  We show that in a simple experiment at undergraduate level, suitable to be
performed in classes of science and engineering students, it is possible to
test accurately, on a popular 1N4148 p-n diode, the range of the junction
currents where the Shockley equation model can be considered satisfactory. The
experiment benefits from a system of temperature control and data collection
driven in a LabVIEW environment. With these tools a large quantity of data can
be recorded in the temporal frame of a lab session. Significant deviations of
the experimental I-V with respect to the ideal behaviour curve predicted by the
Shockley equation are observed, both at low and high current. A better
agreement over the entire range is obtained introducing, as is customary, a
four parameters model, including a parallel and a series resistance. A new
iterative fitting procedure is presented which treats the I-V data of different
regimes on the same level, and allows a simultaneous determination of the four
parameters for each temperature selected. Moreover, the knowledge of the
temperature dependence of saturation current is used to estimate the energy gap
of silicon. The connection of a macroscopic measure with a microscopic quantity
is another valuable feature of this experiment, from an educational point of
view.


title:
Operator-Valued Bochner Theorem, Fourier Feature Maps for
  Operator-Valued Kernels, and Vector-Valued Learning

abstract:
  This paper presents a framework for computing random operator-valued feature
maps for operator-valued positive definite kernels. This is a generalization of
the random Fourier features for scalar-valued kernels to the operator-valued
case. Our general setting is that of operator-valued kernels corresponding to
RKHS of functions with values in a Hilbert space. We show that in general, for
a given kernel, there are potentially infinitely many random feature maps,
which can be bounded or unbounded. Most importantly, given a kernel, we present
a general, closed form formula for computing a corresponding probability
measure, which is required for the construction of the Fourier features, and
which, unlike the scalar case, is not uniquely and automatically determined by
the kernel. We also show that, under appropriate conditions, random bounded
feature maps can always be computed. Furthermore, we show the uniform
convergence, under the Hilbert-Schmidt norm, of the resulting approximate
kernel to the exact kernel on any compact subset of Euclidean space. Our
convergence requires differentiable kernels, an improvement over the
twice-differentiability requirement in previous work in the scalar setting. We
then show how operator-valued feature maps and their approximations can be
employed in a general vector-valued learning framework. The mathematical
formulation is illustrated by numerical examples on matrix-valued kernels.


title:
Measurement of the top quark properties in the production and decays of
  top anti-top pair events at CMS

abstract:
  Measurements of several top-quark properties obtained from CMS data collected
at various centre-of-mass energies are presented. The results include
measurements of the top pair charge asymmetry, $\textrm{t}\bar{\textrm{t}}$
spin correlation, CP violation and the cross section of
$\textrm{t}\bar{\textrm{t}}$ events produced in association with a W or a Z
boson. The results are compared with predictions from the standard model as
well as new physics models.


title:
Almost quantum correlations and their refinements in a tripartite Bell
  scenario

abstract:
  We study the set of almost quantum correlations and their refinements in the
simplest tripartite Bell scenario where each party is allowed to perform two
dichotomic measurements. In contrast to its bipartite counterpart, we find that
there already exist facet Bell inequalities that witness almost quantum
correlations beyond quantum theory in this simplest tripartite Bell scenario.
Furthermore, we study the relation between the almost quantum set and the
hierarchy of supersets to the quantum set due to Navascu\'es-Pironio-Ac\'in
(NPA) [Phys. Rev. Lett. 98, 010401 (2007)]. While the former lies between the
first and the third level of the NPA hierarchy, we find that its second level
does not contain and is not contained within the almost quantum set. Finally,
we investigate the hierarchy of refinements to the almost quantum set due to
Moroder et al. [Phys. Rev. Lett. 111, 030501 (2013)], which converges to the
set of quantum correlations producible by quantum states having positive
partial transposition. This allows us to consider (approximations of) the
"biseparable" subsets of the almost-quantum set as well as of the quantum set
of correlations, and thereby gain further insights on the subtle similarities
and differences between the two sets. In addition, they allow us to identify
candidate Bell-like inequalities that can serve as device-independent witnesses
for genuine tripartite entanglement.


title:
A class of invisible inhomogeneous media and the control of
  electromagnetic waves

abstract:
  We propose a general method to arbitrarily manipulate an electromagnetic wave
propagating in a two-dimensional medium, without introducing any scattering.
This leads to a whole class of isotropic spatially varying permittivity and
permeability profiles that are invisible while shaping the field magnitude
and/or phase. In addition, we propose a metamaterial structure working in the
infrared that demonstrates deep sub-wavelength control of the electric field
amplitude and strong reduction of the scattering. This work offers an
alternative strategy to achieve invisibility with isotropic materials and paves
the way for tailoring the propagation of light at the nanoscale


title:
Monitoring Electrostatically-Induced Deflection, Strain and Doping in
  Suspended Graphene using Raman Spectroscopy

abstract:
  Electrostatic gating offers elegant ways to simultaneously strain and dope
atomically thin membranes. Here, we report on a detailed \textit{in situ} Raman
scattering study on graphene, suspended over a Si/SiO$_2$ substrate. In such a
layered structure, the intensity of the Raman G- and 2D-mode features of
graphene are strongly modulated by optical interference effects and allow an
accurate determination of the electrostatically-induced membrane deflection, up
to irreversible collapse. The membrane deflection is successfully described by
an electromechanical model, which we also use to provide useful guidelines for
device engineering. In addition, electrostatically-induced tensile strain is
determined by examining the softening of the Raman features. Due to a small
residual charge inhomogeneity $\sim 5\times 10^{10}~\rm cm^{-2}$, we find that
non-adiabatic anomalous phonon softening is negligible compared to
strain-induced phonon softening. These results open perspectives for innovative
Raman scattering-based readout schemes in two-dimensional nanoreso


title: Characterisation of longitudinal variation in photonic crystal fibre

abstract:
  We present a method by which the degree of longitudinal variation in photonic
crystal fibre (PCF) may be characterised through seeded four-wave mixing (FWM).
Using an iterative numerical reconstruction, we created a model PCF that
displays similar FWM phasematching properties across all measured length
scales. Our results demonstrate that the structure of our PCF varies by less
than 1% and that the characteristic length of the variations is approximately
15 cm.


title:
Reconfigurable SDM Switching Using Novel Silicon Photonic Integrated
  Circuit

abstract:
  Space division multiplexing using multicore fibers is becoming a more and
more promising technology. In space-division multiplexing fiber network, the
reconfigurable switch is one of the most critical components in network nodes.
In this paper we for the first time demonstrate reconfigurable space-division
multiplexing switching using silicon photonic integrated circuit, which is
fabricated on a novel silicon-on-insulator platform with buried Al mirror. The
silicon photonic integrated circuit is composed of a 7x7 switch and low loss
grating coupler array based multicore fiber couplers. Thanks to the Al mirror,
grating couplers with ultra-low coupling loss with optical multicore fibers is
achieved. The lowest total insertion loss of the silicon integrated circuit is
as low as 4.5 dB, with low crosstalk lower than -30 dB. Excellent performances
in terms of low insertion loss and low crosstalk are obtained for the whole
C-band. 1 Tb/s/core transmission over a 2-km 7-core fiber and space-division
multiplexing switching is demonstrated successfully. Bit error rate performance
below 10-9 is obtained for all spatial channels with low power penalty. The
proposed design can be easily upgraded to reconfigurable optical add/drop
multiplexer capable of switching several multicore fibers.


title: Vibration of a Cantilever Beam in Ambient Fluid

abstract:
  Here we obtain analytical expressions for the frequency response of a
cantilever beam in the presence of ambient fluid. The advantage of our
approach, besides its simplicity of use, is that it explicitly contains the
viscosity and the density of the ambient fluid. Thus, if measuring the
frequency spectrum, the expression can be used in the design of viscometers.
Conversely, if the ambient fluid is known, the expression can be used in the
design of force gauges such as in Atomic Force Microscopy.


title:
Analysis of Transient Acoustic-Elastic Interaction in an Unbounded
  Structure

abstract:
  Consider the wave propagation in a two-layered medium consisting of a
homogeneous compressible air or fluid on top of a homogeneous isotropic elastic
solid. The interface between the two layers is assumed to be an unbounded rough
surface. This paper concerns the time-domain analysis of such an
acoustic-elastic interaction problem in an unbounded structure in three
dimensions. Using an exact transparent boundary condition and suitable
interface conditions, we study an initial-boundary value problem for the
coupling of the Helmholtz equation and the Navier equation. The well-posedness
and stability are established for the reduced problem. Our proof is based on
the method of energy, the Lax--Milgram lemma, and the inversion theorem of the
Laplace transform. Moreover, a priori estimates with explicit dependence on the
time are achieved for the quantities of acoustic pressure and elastic
displacement by taking special test functions for the time-domain variational
problem.


title:
Computing with Dynamical Systems Based on Insulator-Metal-Transition
  Oscillators

abstract:
  In this paper we review recent work on novel computing paradigms using
coupled oscillatory dynamical systems. We explore systems of relaxation
oscillators based on linear state transitioning devices, which switch between
two discrete states with hysteresis. By harnessing the dynamics of complex,
connected systems we embrace the philosophy of "let physics do the computing"
and demonstrate how complex phase and frequency dynamics of such systems can be
controlled, programmed and observed to solve computationally hard problems.
Although our discussion in this paper is limited to Insulator-to-Metallic (IMT)
state transition devices, the general philosophy of such computing paradigms
can be translated to other mediums including optical systems. We present the
necessary mathematical treatments necessary to understand the time evolution of
these systems and demonstrate through recent experimental results the potential
of such computational primitives.


title: Advanced boundary electrode modeling for tES and parallel tES/EEG

abstract:
  This paper explores advanced electrode modeling in the context of separate
and parallel transcranial electrical stimulation (tES) and
electroencephalography (EEG) measurements. We focus on boundary condition based
approaches that do not necessitate adding auxiliary elements, e.g. sponges, to
the computational domain. In particular, we investigate the complete electrode
model (CEM) which incorporates a detailed description of the skin-electrode
interface including its contact surface, impedance and normal current
distribution. The CEM can be applied for both tES and EEG electrodes which is
advantageous when a parallel system is used. In comparison to the CEM, we test
two important reduced approaches: the gap model (GAP) and the point electrode
model (PEM). We aim to find out the differences of these approaches for a
realistic numerical setting based on the stimulation of the auditory cortex.
The results obtained suggest, among other things, that GAP and GAP/PEM are
sufficiently accurate for the practical application of tES and parallel
tES/EEG, respectively. Differences between CEM and GAP were observed mainly in
the skin compartment, where only CEM explains the heating effects
characteristic to tES.


title: Poverty Index With Time Varying Consumption and Income Distributions

abstract:
  In a recent work (Chattopadhyay, A. K. et al, Europhys. Lett. {\bf 91},
58003, 2010) based on food consumption statistics, we showed how a stochastic
agent based model could represent the time variation of the income distribution
statistics in a developing economy, thereby defining an alternative
\enquote{poverty index} (PI) that largely agreed with poverty gap index data.
This PI used two variables, the probability density function of the income
statistics and a consumption deprivation (CD) function, representing the
shortfall in the minimum consumption needed for survival. Since the time
dependence of the CD function was introduced there through data extrapolation
only and not through an endogenous time dependent series, this model left
unexplained how the minimum consumption needed for survival varies with time.
The present article overcomes these limitations and arrives at a new unified
theoretical structure through time varying consumption and income distributions
where trade is only allowed when the income exceeds consumption deprivation
(CD). Our results reveal that such CD-dynamics reduces the threshold level of
consumption of basic necessities, suggesting a possible dietary transition in
terms of lower saturation level of food-grain consumption. The new poverty
index conforms to recently observed trends more closely than conventional
measures of poverty and allows probabilistic prediction of PI for future times.


title:
Campana points, Vojta's conjecture, and level structures on semistable
  abelian varieties

abstract:
  We introduce a qualitative conjecture, in the spirit of Campana, to the
effect that certain subsets of rational points on a variety over a number
field, or a Deligne-Mumford stack over a ring of S-integers, cannot be Zariski
dense. The conjecture interpolates, in a way that we make precise, between
Lang's conjecture for rational points on varieties of general type over number
fields, and the conjecture of Lang and Vojta that asserts that S-integral
points on a variety of logarithmic general type are not Zariski-dense. We show
our conjecture follows from Vojta's conjecture. Assuming our conjecture, we
prove the following theorem: Fix a number field K, a finite set S of places of
K containing the infinite places, and a positive integer g. Then there is an
integer m_0 such that, for any m > m_0, no principally polarized abelian
variety A/K of dimension g with semistable reduction outside of S has full
level-m structure.


title:
On direct and inverse spectral problems for sloshing of a two-layer
  fluid in an open container

abstract:
  We study direct and inverse eigenvalue problems for a pair of harmonic
functions with a spectral parameter in boundary and coupling conditions. The
direct problem is relevant to sloshing frequencies of free oscillations of a
two-layer fluid in a container. The upper fluid occupies a layer bounded above
by a free surface and below by a layer of fluid of greater density. Both fluids
are assumed to be inviscid, incompressible, and heavy, whereas the free surface
and the interface between fluids are supposed to be bounded.


title:
Temperature dependence of the electron spin resonance linewidth in
  magnetic insulators

abstract:
  We analyze the temperature dependence of the electron spin resonance
linewidth above the critical region in exchange-coupled magnetic insulators.
The focus is on separating the contributions to the linewidth from spin-spin
interactions, spin-one-phonon interactions and spin-two-phonon interactions at
temperatures where the spin-spin term is constant and the one- and two-phonon
terms vary as T and T^2, respectively. Taking Co3O4 as an example, we use a
least squares fit over the temperature range 50 K < T < 500 K to obtain values
of the three components. It is found that the spin-spin mechanism is dominant
below 100 K, while the two-phonon mechanism is most important above 250 K. In
the intermediate region, all three mechanisms make significant contributions.


title: POLYPATH: Supporting Multiple Tradeoffs for Interaction Latency

abstract:
  Modern mobile systems use a single input-to-display path to serve all
applications. In meeting the visual goals of all applications, the path has a
latency inadequate for many important interactions. To accommodate the
different latency requirements and visual constraints by different
interactions, we present POLYPATH, a system design in which application
developers (and users) can choose from multiple path designs for their
application at any time. Because a POLYPATH system asks for two or more path
designs, we present a novel fast path design, called Presto. Presto reduces
latency by judiciously allowing frame drops and tearing.
  We report an Android 5-based prototype of POLYPATH with two path designs:
Android legacy and Presto. Using this prototype, we quantify the effectiveness,
overhead, and user experience of POLYPATH, especially Presto, through both
objective measurements and subjective user assessment. We show that Presto
reduces the latency of legacy touchscreen drawing applications by almost half;
and more importantly, this reduction is orthogonal to that of other popular
approaches and is achieved without any user-noticeable negative visual effect.
When combined with touch prediction, Presto is able to reduce the touch latency
below 10 ms, a remarkable achievement without any hardware support.


title:
Nonstationary Spatial Prediction of Soil Organic Carbon: Implications
  for Stock Assessment Decision Making

abstract:
  The Rapid Carbon Assessment (RaCA) project was conducted by the US Department
of Agriculture's National Resources Conservation Service between 2010-2012 in
order to provide contemporaneous measurements of soil organic carbon (SOC)
across the US. Despite the broad extent of the RaCA data collection effort,
direct observations of SOC are not available at the high spatial resolution
needed for studying carbon storage in soil and its implications for important
problems in climate science and agriculture. As a result, there is a need for
predicting SOC at spatial locations not included as part of the RaCA project.
In this paper, we compare spatial prediction of SOC using a subset of the RaCA
data for a variety of statistical methods. We investigate the performance of
methods with off-the-shelf software available (both stationary and
nonstationary) as well as a novel nonstationary approach based on partitioning
relevant spatially-varying covariate processes. Our new method addresses open
questions regarding (1) how to partition the spatial domain for
segmentation-based nonstationary methods, (2) incorporating partially observed
covariates into a spatial model, and (3) accounting for uncertainty in the
partitioning. In applying the various statistical methods we find that there
are minimal differences in out-of-sample criteria for this particular data set,
however, there are major differences in maps of uncertainty in SOC predictions.
We argue that the spatially-varying measures of prediction uncertainty produced
by our new approach are valuable to decision makers, as they can be used to
better benchmark mechanistic models, identify target areas for soil restoration
projects, and inform carbon sequestration projects.


title: Physical Angular Momentum Separation for QED

abstract:
  We study the non-uniqueness problem of the gauge-invariant angular momentum
separation for the case of QED, which stems from the recent controversy
concerning the proper definitions of the orbital angular momentum and spin
operator of the individual parts of a gauge field system. For the free quantum
electrodynamics without matter, we show that the basic requirement of Euclidean
symmetry selects a unique physical angular momentum separation scheme from the
multitude of the possible angular momentum separation schemes constructed using
the various Gauge Invariant Extentions. Based on these results, we propose a
set of natural angular momentum separation schemes for the case of interacting
QED by invoking the formalism of asymptotic fields. Some perspectives on such a
problem for the case of QCD are briefly discussed.


title: Motzkin numbers and related sequences modulo powers of $2$

abstract:
  We show that the generating function $\sum_{n\ge0}M_n\,z^n$ for Motzkin
numbers $M_n$, when coefficients are reduced modulo a given power of $2$, can
be expressed as a polynomial in the basic series $\sum _{e\ge0} ^{} {z^{4^e}}/(
{1-z^{2\cdot 4^e}})$ with coefficients being Laurent polynomials in $z$ and
$1-z$. We use this result to determine $M_n$ modulo $8$ in terms of the binary
digits of~$n$, thus improving, respectively complementing earlier results by
Eu, Liu and Yeh [Europ. J. Combin. 29 (2008), 1449-1466] and by Rowland and
Yassawi [J. Th\'eorie Nombres Bordeaux 27 (2015), 245-288]. Analogous results
are also shown to hold for related combinatorial sequences, namely for the
Motzkin prefix numbers, Riordan numbers, central trinomial coefficients, and
for the sequence of hex tree numbers.


title: Variance of the volume of random real algebraic submanifolds

abstract:
  Let $\mathcal{X}$ be a complex projective manifold of dimension $n$ defined
over the reals and let $M$ denote its real locus. We study the vanishing locus
$Z\_{s\_d}$ in $M$ of a random real holomorphic section $s\_d$ of $\mathcal{E}
\otimes \mathcal{L}^d$, where $ \mathcal{L} \to \mathcal{X}$ is an ample line
bundle and $ \mathcal{E}\to \mathcal{X}$ is a rank $r$ Hermitian bundle. When
$r \in \{1,\dots , n -- 1\}$, we obtain an asymptotic of order $d^{r--
\frac{n}{2}}$, as $d$ goes to infinity, for the variance of the linear
statistics associated to $Z\_{s\_d}$, including its volume. Given an open set
$U \subset M$, we show that the probability that $Z\_{s\_d}$ does not intersect
$U$ is a $O$ of $d^{-\frac{n}{2}}$ when $d$ goes to infinity. When $n\geq 3$,
we also prove almost sure convergence for the linear statistics associated to a
random sequence of sections of increasing degree. Our framework contains the
case of random real algebraic submanifolds of $\mathbb{RP}^n$ obtained as the
common zero set of $r$ independent Kostlan--Shub--Smale polynomials.


title: Hyperpfaffians

abstract:
  We define and inverstigate a generalization of the pfaffian for multiple
array which interpolate between the hyperdeterminant and the hyperp-faffian.


title:
Coded Caching and Content Delivery with Heterogeneous Distortion
  Requirements

abstract:
  Cache-aided coded content delivery is studied for devices with diverse
quality-of-service (QoS) requirements, specified by a different average
distortion target. The network consists of a server holding a database of
independent contents, and users equipped with local caches of different
capacities. User caches are filled by the server during a low traffic period
without the knowledge of particular user demands. As opposed to the current
literature, which assumes that the users request files in their entirety, it is
assumed that the users in the system have distinct distortion requirements; and
therefore, each user requests a single file from the database to be served at a
different distortion level. Our goal in this work is to characterize the
minimum delivery rate the server needs to transmit over an error-free shared
link to satisfy all possible demand combinations at the requested distortion
levels, considering both centralized and decentralized cache placement.


title:
The Curious Case of the PDF Converter that Likes Mozart: Dissecting and
  Mitigating the Privacy Risk of Personal Cloud Apps

abstract:
  Third party apps that work on top of personal cloud services such as Google
Drive and Dropbox, require access to the user's data in order to provide some
functionality. Through detailed analysis of a hundred popular Google Drive apps
from Google's Chrome store, we discover that the existing permission model is
quite often misused: around two thirds of analyzed apps are over-privileged,
i.e., they access more data than is needed for them to function. In this work,
we analyze three different permission models that aim to discourage users from
installing over-privileged apps. In experiments with 210 real users, we
discover that the most successful permission model is our novel ensemble method
that we call Far-reaching Insights. Far-reaching Insights inform the users
about the data-driven insights that apps can make about them (e.g., their
topics of interest, collaboration and activity patterns etc.) Thus, they seek
to bridge the gap between what third parties can actually know about users and
users perception of their privacy leakage. The efficacy of Far-reaching
Insights in bridging this gap is demonstrated by our results, as Far-reaching
Insights prove to be, on average, twice as effective as the current model in
discouraging users from installing over-privileged apps. In an effort for
promoting general privacy awareness, we deploy a publicly available privacy
oriented app store that uses Far-reaching Insights. Based on the knowledge
extracted from data of the store's users (over 115 gigabytes of Google Drive
data from 1440 users with 662 installed apps), we also delineate the ecosystem
for third-party cloud apps from the standpoint of developers and cloud
providers. Finally, we present several general recommendations that can guide
other future works in the area of privacy for the cloud.


title:
Nonperturbative quantization \`a la Heisenberg for non-Abelian gauge
  theories: two-equation approximation

abstract:
  The nonperturbative quantization technique \`{a} la Heisenberg is applied for
non-Abelian gauge theories. The operator Yang-Mills equation is written, which
on the corresponding averaging gives an infinite set of equations for all Green
functions. We split all degrees of freedom into two groups: in the former, we
have $A^a_\mu \in \mathcal G \subset SU(N)$, and in the second group we have
coset degrees of freedom $SU(N) / \mathcal G$. Using such splitting and some
assumptions about 2- and 4-point Green functions, we truncate the infinite set
of equations to two equations. The first equation is for the gauge fields from
the subgroup $\mathcal G$, and the second equation is for a gluon condensate
which is the dispersion of quantum fluctuations of the coset fields. Two
examples are considered: The first one is a flux tube solution describing
longitudinal color electric fields stretched between quark and antiquark
located at the $\pm$ infinities. The second one is a flux tube stretched
between two quarks (antiquarks) located at $\pm \infty$. A special case is
considered when the longitudinal electric field produced by a quark located at
$+ \infty$ is equal and oppositely directed to the field generated by a quark
located at $- \infty$ that leads to zero total electric field. Both solutions
represents the dual Meissner effect: the electric field is pushed out from the
gluon condensate.


title:
Ion Beam radiation and temperature effect on Co/Si and CoO/Co/Si thin
  films

abstract:
  Co and CoO thin films were deposited by magnetron sputtering in the form of
multilayers. They were irradiated with Ar and Si ion beams of different
energies and fluences. The magnetic properties were investigated.


title: A family of linear codes with three weights

abstract:
  Recently, linear codes constructed by defining sets have attracted a lot of
study, and many optimal linear codes with a few weights have been produced. The
objective of this paper is to present a class of binary linear codes with three
weights.


title: Small-World Brain Networks Revisited

abstract:
  It is nearly 20 years since the concept of a small-world network was first
quantitatively defined, by a combination of high clustering and short path
length; and about 10 years since this metric of complex network topology began
to be widely applied to analysis of neuroimaging and other neuroscience data as
part of the rapid growth of the new field of connectomics. Here we review
briefly the foundational concepts of graph theoretical estimation and
generation of small-world networks. We take stock of some of the key
developments in the field in the past decade and we consider in some detail the
implications of recent studies using high-resolution tract-tracing methods to
map the anatomical networks of the macaque and the mouse. In doing so, we draw
attention to the important methodological distinction between topological
analysis of binary or unweighted graphs, which have provided a popular but
simple approach to brain network analysis in the past, and the topology of
weighted graphs, which retain more biologically relevant information and are
more appropriate to the increasingly sophisticated data on brain connectivity
emerging from contemporary tract-tracing and other imaging studies. We conclude
by highlighting some possible future trends in the further development of
weighted small-worldness as part of a deeper and broader understanding of the
topology and the functional value of the strong and weak links between areas of
mammalian cortex.


title: On non-primitive Weierstrass points

abstract:
  We give an upper bound on the codimension in $M_{g,1}$ of the variety
$M^S_{g,1}$ of marked curves $(C,p)$ with a given Weierstrass semigroup. The
bound is a combinatorial quantity which we call the effective weight of the
semigroup; it is a refinement of the weight of the semigroup, and differs from
it precisely when the semigroup is not primitive. We prove that whenever the
effective weight is less than g, the variety $M^S_{g,1}$ is nonempty and has a
component of the predicted codimension. These results extend previous results
of Eisenbud, Harris, and Komeda to the case of non-primitive semigroups. We
also survey other cases where the codimension of $M^S_{g,1}$ is known, as
evidence that the effective weight estimate is correct in much wider
circumstances.


title: Nanocomposite si-c-n coatings

abstract:
  Coatings of ternary nanocomposite Si-C-N ceramic coatings have shown newer
and improved mechanical and functional properties over the coarser and
monolithic coatings. Properties like high hardness, wear resistance, oxidation
resistance, tunable band gap and chemical inertness have been observed for
Si-C-N which makes its potential for numerous applications. Although lot of
research has taken place in Si-C-N coatings, proper understanding of the effect
of different parameters on the coating properties are still not resolved. The
changes occurring in fraction of Si, C and N and the phases forming in the
coatings with variation in deposition conditions require investigations. This
research paper gives a systematic study of the role of different deposition
parameters like substrate temperature, pressure, power on the nucleation and
growth, structure, microstructural bonding and mechanical properties of the
film deposited by magnetron sputtering which adds significantly to the
fundamental knowledge of nanocomposite Si-C-N coatings as well as its
applications.


title: Assessing the Use of Social Media in Massive Open Online Courses

abstract:
  The study explores whether the use of Twitter in Massive Open Online Courses
(MOOCs) promotes the interaction among learners. The social network analysis
shows that instructors still play a very central role in the social media
communication and the communication network between students shrinking over
time. The mere use of social media fails to promote learner-learner
interaction. More research is needed for understanding learner motivation and
how instructional design can help increase their engagement and participation.


title:
The class of Eisenbud--Khimshiashvili--Levine is the local A1-Brouwer
  degree

abstract:
  Given a polynomial function with an isolated zero at the origin, we prove
that the local A1-Brouwer degree equals the Eisenbud-Khimshiashvili-Levine
class. This answers a question posed by David Eisenbud in 1978. We give an
application to counting nodes together with associated arithmetic information
by enriching Milnor's equality between the local degree of the gradient and the
number of nodes into which a hypersurface singularity degenerates to an
equality in the Grothendieck-Witt group.


title:
Change Point in Panel Data with Small Fixed Panel Size: Ratio and
  Non-Ratio Test Statistics

abstract:
  The main goal is to develop and, consequently, compare stochastic methods for
detection whether a structural change in panel data occurred at some unknown
time or not. Panel data of our interest consist of a moderate or relatively
large number of panels, while the panels contain a small number of
observations. Testing procedures to detect a possible common change in means of
the panels are established. Ratio and non-ratio type test statistics are
considered. Their asymptotic distributions under the no change null hypothesis
are derived. Moreover, we prove the consistency of the tests under the
alternative. The main advantage of the ratio type statistics compared to the
non-ratio ones is that the variance of the observations neither has to be known
nor estimated. A simulation study reveals that the proposed ratio statistic
outperforms the non-ratio one by keeping the significance level under the null,
mainly when stronger dependence within the panel is taken into account.
However, the non-ratio statistic rejects the null in the simulations more often
than it should, which yields higher power compared to the ratio statistic.


title: Dominating sets and ego-centered decompositions in social networks

abstract:
  Our aim here is to address the problem of decomposing a whole network into a
minimal number of ego-centered subnetworks. For this purpose, the network egos
are picked out as the members of a minimum dominating set of the network.
However, to find such an efficient dominating ego-centered construction, we
need to be able to detect all the minimum dominating sets and to compare all
the corresponding dominating ego-centered decompositions of the network. To
find all the minimum dominating sets of the network, we are developing a
computational heuristic, which is based on the partition of the set of nodes of
a graph into three subsets, the always dominant vertices, the possible dominant
vertices and the never dominant vertices, when the domination number of the
network is known. To compare the ensuing dominating ego-centered decompositions
of the network, we are introducing a number of structural measures that count
the number of nodes and links inside and across the ego-centered subnetworks.
Furthermore, we are applying the techniques of graph domination and
ego=centered decomposition for six empirical social networks.


title: Decoherent histories approach to the cosmological measure problem

abstract:
  The method of decoherent histories allows probabilities to be assigned to
sequences of quantum events in systems, such as the universe as a whole, where
there is no external observer to make measurements. This paper applies the
method of decoherent histories to address cosmological questions. Using a
series of simple examples, beginning with the harmonic oscillator, we show that
systems in a stationary state such as an energy eigenstate or thermal state can
exhibit decoherent histories with non-trivial dynamics. We then examine
decoherent histories in a universe that undergoes eternal inflation. Decoherent
histories that assign probabilities to sequences of events in the vicinity of a
timelike geodesic supply a natural cosmological measure. Under reasonable
conditions, such sequences of events do not suffer from the presence of
unlikely statistical fluctuations that mimic reality.


title:
Exploring the extended scalar sector with resonances in vector boson
  scattering

abstract:
  We show that the study of scalar resonances at various vector boson
scattering processes at the Large Hadron Collider can serve as a useful tool to
distinguish between different extensions of the scalar sector of the Standard
Model. The recent measurement of the Higgs boson properties leaves enough room
for the extended scalar sectors to be relevant for such studies. The shape of
the resonances, being model dependent, can shed light on the viable parameter
space of a number of theoretical models.


title: Diffractive di-jet production at the LHC with a Reggeon contribution

abstract:
  We study hard diffractive scattering in hadron-hadron collisions including,
on top of the standard Pomeron-initiated processes, contributions due to the
exchange of Reggeons. Using a simple model to describe the parton content of
the Reggeon, we compute di-jet production in single diffractive and central
diffractive events. We show that Reggeon contributions can be sizable at the
LHC, and even sometimes dominant, and we identify kinematic windows in which
they could be experimentally studied. We argue that suitable measurements must
be performed in order to properly constrain the model, and be able to correctly
account for Reggeon exchanges in the analysis of the many hard diffractive
observables to be measured at the LHC.


title: lpopt: A Rule Optimization Tool for Answer Set Programming

abstract:
  State-of-the-art answer set programming (ASP) solvers rely on a program
called a grounder to convert non-ground programs containing variables into
variable-free, propositional programs. The size of this grounding depends
heavily on the size of the non-ground rules, and thus, reducing the size of
such rules is a promising approach to improve solving performance. To this end,
in this paper we announce lpopt, a tool that decomposes large logic programming
rules into smaller rules that are easier to handle for current solvers. The
tool is specifically tailored to handle the standard syntax of the ASP language
(ASP-Core) and makes it easier for users to write efficient and intuitive ASP
programs, which would otherwise often require significant hand-tuning by expert
ASP engineers. It is based on an idea proposed by Morak and Woltran (2012) that
we extend significantly in order to handle the full ASP syntax, including
complex constructs like aggregates, weak constraints, and arithmetic
expressions. We present the algorithm, the theoretical foundations on how to
treat these constructs, as well as an experimental evaluation showing the
viability of our approach.


title:
Hierarchical Shape Abstraction for Analysis of Free-List Memory
  Allocators

abstract:
  We propose a hierarchical abstract domain for the analysis of free-list
memory allocators that tracks shape and numerical properties about both the
heap and the free lists. Our domain is based on Separation Logic extended with
predicates that capture the pointer arithmetics constraints for the heap-list
and the shape of the free-list. These predicates are combined using a
hierarchical composition operator to specify the overlapping of the heap-list
by the free-list. In addition to expressiveness, this operator leads to a
compositional and compact representation of abstract values and simplifies the
implementation of the abstract domain. The shape constraints are combined with
numerical constraints over integer arrays to track properties about the
allocation policies (best-fit, first-fit, etc). Such properties are out of the
scope of the existing analyzers. We implemented this domain and we show its
effectiveness on several implementations of free-list allocators.


title: Invariant Meromorphic Functions on the Wallpaper Groups

abstract:
  We construct the meromorphic functions invariant under the action of the
sense-preserving wallpaper groups on the complex plane. We discuss possible
generalisa-tions of this to the general wallpaper groups. This provides the
answer to a question posed on StackExchange regarding the possible symmetries
of elliptic functions.


title: Revisiting Reuse in Main Memory Database Systems

abstract:
  Reusing intermediates in databases to speed-up analytical query processing
has been studied in the past. Existing solutions typically require intermediate
results of individual operators to be materialized into temporary tables to be
considered for reuse in subsequent queries. However, these approaches are
fundamentally ill-suited for use in modern main memory databases. The reason is
that modern main memory DBMSs are typically limited by the bandwidth of the
memory bus, thus query execution is heavily optimized to keep tuples in the CPU
caches and registers. To that end, adding additional materialization operations
into a query plan not only add additional traffic to the memory bus but more
importantly prevent the important cache- and register-locality opportunities
resulting in high performance penalties.
  In this paper we study a novel reuse model for intermediates, which caches
internal physical data structures materialized during query processing (due to
pipeline breakers) and externalizes them so that they become reusable for
upcoming operations. We focus on hash tables, the most commonly used internal
data structure in main memory databases to perform join and aggregation
operations. As queries arrive, our reuse-aware optimizer reasons about the
reuse opportunities for hash tables, employing cost models that take into
account hash table statistics together with the CPU and data movement costs
within the cache hierarchy. Experimental results, based on our HashStash
prototype demonstrate performance gains of $2\times$ for typical analytical
workloads with no additional overhead for materializing intermediates.


title: The geometry of sloppiness

abstract:
  The use of mathematical models in the sciences often involves the estimation
of unknown parameter values from data. Sloppiness provides information about
the uncertainty of this task. In this paper, we develop a precise mathematical
foundation for sloppiness and define rigorously its key concepts, such as
`model manifold', in relation to concepts of structural identifiability. We
redefine sloppiness conceptually as a comparison between the premetric on
parameter space induced by measurement noise and a reference metric. This opens
up the possibility of alternative quantification of sloppiness, beyond the
standard use of the Fisher Information Matrix, which assumes that parameter
space is equipped with the usual Euclidean metric and the measurement error is
infinitesimal. Applications include parametric statistical models, explicit
time dependent models, and ordinary differential equation models.

categories: math.MG math.DS math.ST physics.data-an q-bio.QM stat.TH


title:
Formation of hypernuclei in heavy-ion collisions around the threshold
  energies

abstract:
  In relativistic ion collisions there are excellent opportunities to produce
and investigate hyper-nuclei. We have systematically studied the formation of
hypernuclear spectator residues in peripheral heavy-ion collisions with the
transport DCM and UrQMD models. The hyperon capture was calculated within the
potential and coalescence approaches. We demonstrate that even at the beam
energies around and lower than the threshold for producing Lambda hyperons in
binary nucleon-nucleon interactions a considerable amount of hypernuclei,
including multi-strange ones, can be produced. This is important for
preparation of new experiments on hypernuclei in the wide energy range. The
uncertainties of the predictions are investigated within the models, and the
comparison with the strangeness production measured in experiments is also
performed.


title: Nodal Uniformization of G-bundles

abstract:
  We give a survey of uniformization results for principal bundles on curves.
We provide a proof of uniformization for nodal curves; this result is a special
case of work of Belkale and Fakhruddin for uniformization on singular curves.
We use the uniformization result to give a construction of a compactification
of the moduli of G bundles on a family of nodal curves. Along the way we also
explain how to use equivariant compactifactions of a group to compactify the
moduli stack of bundles over a fixed nodal curve.


title: Finite temperature corrections to a NLO Nambu-Jona-Lasinio model

abstract:
  We derive the next-to-leading order correction to the Nambu-Jona-Lasinio
model starting from quantum chromodynamics. So, we are able to fix the
constants of the Nambu-Jona-Lasinio model from quantum chromodynamics and
analyze the behavior of strong interactions at low energies. The technique is
to expand in powers of currents the generating functional. We apply it to a
simple Yukawa model with self-interaction showing how this has a
Nambu-Jona-Lasinio model and its higher order corrections as a low-energy
limit. The same is shown to happen for quantum chromodynamics in the chiral
limit with two quarks. We prove that a consistent thermodynamic behaviour is
obtained as expected for the given parameters.


title: Surgery on Paracompact Manifolds

abstract:
  This is a TeX'ed version of the author's 1971 thesis from the University of
California at Berkeley under the supervision of J.~B.~Wagoner.


title:
Detecting Vanishing Points using Global Image Context in a Non-Manhattan
  World

abstract:
  We propose a novel method for detecting horizontal vanishing points and the
zenith vanishing point in man-made environments. The dominant trend in existing
methods is to first find candidate vanishing points, then remove outliers by
enforcing mutual orthogonality. Our method reverses this process: we propose a
set of horizon line candidates and score each based on the vanishing points it
contains. A key element of our approach is the use of global image context,
extracted with a deep convolutional network, to constrain the set of candidates
under consideration. Our method does not make a Manhattan-world assumption and
can operate effectively on scenes with only a single horizontal vanishing
point. We evaluate our approach on three benchmark datasets and achieve
state-of-the-art performance on each. In addition, our approach is
significantly faster than the previous best method.


title:
Accurate $ab~initio$ tight-binding Hamiltonians: effective tools for
  electronic transport and optical spectroscopy from first principles

abstract:
  The calculations of electronic transport coefficients and optical properties
require a very dense interpolation of the electronic band structure in
reciprocal space that is computationally expensive and may have issues with
band crossing and degeneracies. Capitalizing on a recently developed
pseudo-atomic orbital projection technique, we exploit the exact tight-binding
representation of the first principles electronic structure for the purposes of
(1) providing an efficient strategy to explore the full band structure
$E_n({\bf k})$, (2) computing the momentum operator differentiating directly
the Hamiltonian, and (3) calculating the imaginary part of the dielectric
function. This enables us to determine the Boltzmann transport coefficients and
the optical properties within the independent particle approximation. In
addition, the local nature of the tight-binding representation facilitates the
calculation of the ballistic transport within the Landauer theory for systems
with hundreds of atoms. In order to validate our approach we study the
multi-valley band structure of CoSb$_3$ and a large core-shell nanowire using
the ACBN0 functional. In CoSb$_3$ we point the many band minima contributing to
the electronic transport that enhance the thermoelectric properties; for the
core-shell nanowire we identify possible mechanisms for photo-current
generation and justify the presence of protected transport channels in the
wire.


title:
The effect of input phase modulation to a phase-sensitive optical
  amplifier

abstract:
  Many optical applications depend on amplitude modulating optical beams using
devices such as acousto-optical modulators (AOMs) or optical choppers. Methods
to add amplitude modulation (AM) often inadvertently impart phase modulation
(PM) onto the light as well. While this PM is of no consequence to many
phase-insensitive applications, phase-sensitive processes can be affected. Here
we study the effects of input phase and amplitude modulation on the output of a
quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot
$^{85}$Rb vapor. We investigate the dependence of PM on AOM alignment and
demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic
tool. We then use this method to measure the alignment-dependent PM of an
optical chopper which arises due to diffraction effects as the chopper blade
passes through the optical beam.


title: Traversable Wormholes via a Double Trace Deformation

abstract:
  After turning on an interaction that couples the two boundaries of an eternal
BTZ black hole, we find a quantum matter stress tensor with negative average
null energy, whose gravitational backreaction renders the Einstein-Rosen bridge
traversable. Such a traversable wormhole has an interesting interpretation in
the context of ER=EPR, which we suggest might be related to quantum
teleportation. However, it cannot be used to violate causality. We also discuss
the implications for the energy and holographic entropy in the dual CFT
description.


title:
Infinite horizon jump-diffusion forward-backward stochastic differential
  equations and their application to backward linear-quadratic problems

abstract:
  In this paper, we investigate infinite horizon jump-diffusion
forward-backward stochastic differential equations under some monotonicity
conditions. We establish an existence and uniqueness theorem, two stability
results and a comparison theorem for solutions to such kind of equations. Then
the theoretical results are applied to study a kind of infinite horizon
backward stochastic linear-quadratic optimal control problems, and then
differential game problems. The unique optimal controls for the control
problems and the unique Nash equilibrium points for the game problems are
obtained in closed forms.


title: A gap theorem for free boundary minimal surfaces in the three-ball

abstract:
  We show that, among free boundary minimal surfaces in the unit ball in the
three-dimensional Euclidean space, the flat equatorial disk and the critical
catenoid are characterised by a pinching condition on the length of their
second fundamental form.


title:
On Singular Equivalences of Morita Type and Universal Deformation Rings
  for Gorenstein Algebras

abstract:
  Let $\Lambda$ be a finite-dimensional algebra over a fixed algebraically
closed field $\mathbf{k}$ of arbitrary characteristic, and let $V$ be a
finitely generated $\Lambda$-module. It follows from results previously
obtained by F.M. Bleher and the third author that $V$ has a well-defined versal
deformation ring $R(\Lambda, V)$, which is a complete local commutative
Noetherian $\mathbf{k}$-algebra with residue field $\mathbf{k}$. The third
author also proved that if $\Lambda$ is a Gorenstein $\mathbf{k}$-algebra and
$V$ is a Cohen-Macaulay $\Lambda$-module whose stable endomorphism ring is
isomorphic to $\mathbf{k}$, then $R(\Lambda, V)$ is universal. In this article
we prove that the isomorphism class of a versal deformation ring is preserved
under singular equivalence of Morita type between Gorenstein
$\mathbf{k}$-algebras.


title: On a class of maximality principles

abstract:
  We study various classes of maximality principles, $\rm{MP}(\kappa,\Gamma)$,
introduced by J.D. Hamkins, where $\Gamma$ defines a class of forcing posets
and $\kappa$ is a cardinal. We explore the consistency strength and the
relationship of $\textsf{MP}(\kappa,\Gamma)$ with various forcing axioms when
$\kappa \in\{\omega,\omega_1\}$. In particular, we give a characterization of
bounded forcing axioms for a class of forcings $\Gamma$ in terms of maximality
principles MP$(\omega_1,\Gamma)$ for $\Sigma_1$ formulas. A significant part of
the paper is devoted to studying the principle MP$(\kappa,\Gamma)$ where
$\kappa\in\{\omega,\omega_1\}$ and $\Gamma$ defines the class of stationary set
preserving forcings. We show that MP$(\kappa,\Gamma)$ has high consistency
strength; on the other hand, if $\Gamma$ defines the class of proper forcings
or semi-proper forcings, then by Hamkins, it is shown that MP$(\kappa,\Gamma)$
is consistent relative to $V=L$.


title: The Maslov and Morse indices for Schr\"odinger operators on $\mathbb{R}$

abstract:
  Assuming a symmetric potential that approaches constant endstates with a
sufficient asymptotic rate, we relate the Maslov and Morse indices for
Schr\"odinger operators on $\mathbb{R}$. In particular, we show that with our
choice of convention, the Morse index is precisely the negative of the Maslov
index.


title: Diphoton Signal of light pseudoscalar in NMSSM at the LHC

abstract:
  We explore the detection possibility of light pseudoscalar Higgs boson in the
next-to-minimal supersymmetric Standard Model(NMSSM) at the LHC with the center
of mass energy, $\sqrt{S}=13$ TeV. We focus on the parameter space which
provides one of the Higgs boson as the SM-like with a mass of 125 GeV and some
of the non-SM-like Higgs bosons can be light having suppressed couplings with
fermions and gauge bosons due to their singlet nature. It is observed that for
certain region of model parameter space, the singlet like light pseudoscalar
can decay to di-photon($\gamma\gamma$) channel with a substantial branching
ratio. In this study, we consider this di-photon signal of light pseudoscalar
Higgs boson producing it through the chargino-neutralino production and the
subsequent decay of neutralino. We consider signal consisting of two photons
plus missing energy along with a lepton from the chargino decay. Performing a
detailed simulation of the signal and backgrounds including detector effects,
we present results for a few benchmark points corresponding to the pseudoscalar
Higgs boson mass in the range 60 -100 GeV. Our studies indicate that some of
the benchmark points in the parameter space can be probed with a reasonable
significance for 100 fb$^{-1}$ integrated luminosity. We also conclude that
exploiting this channel it is possible to distinguish the NMSSM from the other
supersymmetric models.


title:
The languages of actions, formal grammars and qualitive modeling of
  companies

abstract:
  In this paper we discuss methods of using the language of actions, formal
languages, and grammars for qualitative conceptual linguistic modeling of
companies as technological and human institutions. The main problem following
the discussion is the problem to find and describe a language structure for
external and internal flow of information of companies. We anticipate that the
language structure of external and internal base flows determine the structure
of companies. In the structure modeling of an abstract industrial company an
internal base flow of information is constructed as certain flow of words
composed on the theoretical parts-processes-actions language. The language of
procedures is found for an external base flow of information for an insurance
company. The formal stochastic grammar for the language of procedures is found
by statistical methods and is used in understanding the tendencies of the
health care industry. We present the model of human communications as a random
walk on the semantic tree


title: Legendrian satellites

abstract:
  In this paper we study Legendrian knots in the knot types of satellite knots.
In particular, we classify Legendrian Whitehead patterns and learn a great deal
about Legendrian braided patterns. We also show how the classification of
Legendrian patterns can lead to a classification of the associated satellite
knots if the companion knot is Legendrian simple and uniformly thick. This
leads to new Legendrian and transverse classification results for knots in the
3-sphere with its standard contact structure as well as a more general
perspective on some previous classification results.


title:
Bounding the costs of quantum simulation of many-body physics in real
  space

abstract:
  We present a quantum algorithm for simulating the dynamics of a
first-quantized Hamiltonian in real space based on the truncated Taylor series
algorithm. We avoid the possibility of singularities by applying various
cutoffs to the system and using a high-order finite difference approximation to
the kinetic energy operator. We find that our algorithm can simulate $\eta$
interacting particles using a number of calculations of the pairwise
interactions that scales, for a fixed spatial grid spacing, as
$\tilde{O}(\eta^2)$, versus the $\tilde{O}(\eta^5)$ time required by previous
methods (assuming the number of orbitals is proportional to $\eta$), and scales
super-polynomially better with the error tolerance than algorithms based on the
Lie-Trotter-Suzuki product formula. Finally, we analyze discretization errors
that arise from the spatial grid and show that under some circumstances these
errors can remove the exponential speedups typically afforded by quantum
simulation.


title:
The number of $\mathbb{F}_p$-points on Dwork hypersurfaces and
  hypergeometric functions

abstract:
  We provide a formula for the number of $\mathbb{F}_{p}$-points on the Dwork
hypersurface $$x_1^n + x_2^n \dots + x_n^n - n \lambda \, x_1 x_2 \dots x_n=0$$
in terms of a $p$-adic hypergeometric function previously defined by the
author. This formula holds in the general case, i.e for any $n, \lambda \in
\mathbb{F}_p^{*}$ and for all odd primes $p$, thus extending results of Goodson
and Barman et al which hold in certain special cases.


title: Automata Theory Approach to Predicate Intuitionistic Logic

abstract:
  Predicate intuitionistic logic is a well established fragment of dependent
types. According to the Curry-Howard isomorphism proof construction in the
logic corresponds well to synthesis of a program the type of which is a given
formula. We present a model of automata that can handle proof construction in
full intuitionistic first-order logic. The automata are constructed in such a
way that any successful run corresponds directly to a normal proof in the
logic. This makes it possible to discuss formal languages of proofs or
programs, the closure properties of the automata and their connections with the
traditional logical connectives.


title:
Memory-efficient and Ultra-fast Network Lookup and Forwarding using
  Othello Hashing

abstract:
  Network algorithms always prefer low memory cost and fast packet processing
speed. Forwarding information base (FIB), as a typical network processing
component, requires a scalable and memory-efficient algorithm to support fast
lookups. In this paper, we present a new network algorithm, Othello Hashing,
and its application of a FIB design called Concise, which uses very little
memory to support ultra-fast lookups of network names. Othello Hashing and
Concise make use of minimal perfect hashing and relies on the programmable
network framework to support dynamic updates. Our conceptual contribution of
Concise is to optimize the memory efficiency and query speed in the data plane
and move the relatively complex construction and update components to the
resource-rich control plane. We implemented Concise on three platforms.
Experimental results show that Concise uses significantly smaller memory to
achieve much faster query speed compared to existing solutions of network name
lookups.


title: Statistics of fractionalized excitations through threshold spectroscopy

abstract:
  We show that the anyonic statistics of fractionalized excitations display
characteristic signatures in threshold spectroscopic measurements. Drawing
motivation from topologically ordered phases such as gapped quantum spin
liquids and fractional chern insulators which possess fractionalized
excitations, we consider gapped systems with abelian anyonic excitations. The
low energy onset of associated correlation functions near the threshold show
universal behaviour depending on the statistics of the anyons. This explains
some recent theoretical results in spin systems and also provides a route
towards detecting statistics in experiments such as neutron scattering and
tunneling spectroscopy.


title:
Pilot Testing an Artificial Intelligence Algorithm That Selects Homeless
  Youth Peer Leaders Who Promote HIV Testing

abstract:
  Objective. To pilot test an artificial intelligence (AI) algorithm that
selects peer change agents (PCA) to disseminate HIV testing messaging in a
population of homeless youth. Methods. We recruited and assessed 62 youth at
baseline, 1 month (n = 48), and 3 months (n = 38). A Facebook app collected
preliminary social network data. Eleven PCAs selected by AI attended a 1-day
training and 7 weekly booster sessions. Mixed-effects models with random
effects were used to assess change over time. Results. Significant change over
time was observed in past 6-month HIV testing (57.9%, 82.4%, 76.3%; p < .05)
but not condom use (63.9%, 65.7%, 65.8%). Most youth reported speaking to a PCA
about HIV prevention (72.0% at 1 month, 61.5% at 3 months). Conclusions. AI is
a promising avenue for implementing PCA models for homeless youth. Increasing
rates of regular HIV testing is critical to HIV prevention and linking homeless
youth to treatment.


title:
Measurement of single $\pi^0$ production by coherent neutral-current
  $\nu$ Fe interactions in the MINOS Near Detector

abstract:
  Forward single $\pi^0$ production by coherent neutral-current interactions,
$\nu \mathcal{A} \to \nu \mathcal{A} \pi^0$, is investigated using a 2.8$\times
10^{20}$ protons-on-target exposure of the MINOS Near Detector. For
single-shower topologies, the event distribution in production angle exhibits a
clear excess above the estimated background at very forward angles for visible
energy in the range~1-8 GeV. Cross sections are obtained for the detector
medium comprised of 80% iron and 20% carbon nuclei with $\langle \mathcal{A}
\rangle = 48$, the highest-$\langle \mathcal{A} \rangle$ target used to date in
the study of this coherent reaction. The total cross section for coherent
neutral-current single-$\pi^0$ production initiated by the $\nu_\mu$ flux of
the NuMI low-energy beam with mean (mode) $E_{\nu}$ of 4.9 GeV (3.0 GeV), is
$77.6\pm5.0\,(\text{stat})
^{+15.0}_{-16.8}\,(\text{syst})\times10^{-40}\,\text{cm}^2~\text{per nucleus}$.
The results are in good agreement with predictions of the Berger-Sehgal model.


title:
Kinetic stability and energetics of simulated glasses created by
  constant pressure cooling

abstract:
  We use computer simulations to study the cooling rate dependence of the
stability and energetics of model glasses created at constant pressure
conditions and compare the results with glasses formed at constant volume
conditions. To examine the stability, we determine the time it takes for a
glass cooled and reheated at constant pressure to transform back into a liquid,
$t_{\mathrm{trans}}$, and calculate the stability ratio $S =
t_{\mathrm{trans}}/\tau_\alpha$, where $\tau_\alpha$ is the equilibrium
relaxation time of the liquid. We find that, for slow enough cooling rates,
cooling and reheating at constant pressure results in a larger stability ratio
$S$ than for cooling and reheating at constant volume. We also compare the
energetics of glasses obtained by cooling while maintaining constant pressure
with those of glasses created by cooling from the same state point while
maintaining constant volume. We find that cooling at constant pressure results
in glasses with lower average potential energy and average inherent structure
energy. We note that in model simulations of the vapor deposition process
glasses are created under constant pressure conditions, and thus they should be
compared to glasses obtained by constant pressure cooling.


title: Photo-electrons unveil topological transitions in graphene-like systems

abstract:
  The topological structure of the wavefunctions of particles in periodic
potentials is characterized by the Berry curvature $\Omega_{kn}$ whose integral
on the Brillouin zone is a topological invariant known as the Chern number. The
bulk-boundary correspondence states that these numbers define the number of
edge or surface topologically protected states. It is then of primary interest
to find experimental techniques able to measure the Berry curvature. However,
up to now, there are no spectroscopic experiments that proved to be capable to
obtain information on $\Omega_{kn}$ to distinguish different topological
structures of the $\it{bulk}$ wavefunctions of semiconducting materials. Based
on experimental results of the dipolar matrix elements for graphene, here we
show that ARPES experiments with the appropriate x-ray energies and
polarization can unambiguously detect changes of the Chern numbers in
dynamically driven graphene and graphene-like materials opening new routes
towards the experimental study of topological properties of condensed matter
systems.


title: Exact Ramsey numbers of odd cycles via nonlinear optimisation

abstract:
  For a graph $G$, the $k$-colour Ramsey number $R_k(G)$ is the least integer
$N$ such that every $k$-colouring of the edges of the complete graph $K_N$
contains a monochromatic copy of $G$. Let $C_n$ denote the cycle on $n$
vertices. We show that for fixed $k\geq2$ and $n$ odd and sufficiently large,
\[ R_k(C_n)=2^{k-1}(n-1)+1. \] This resolves a conjecture of Bondy and
Erd\H{o}s [J. Combin. Th. Ser. B \textbf{14} (1973), 46--54] for large $n$. The
proof is analytic in nature, the first step of which is to use the regularity
method to relate this problem in Ramsey theory to one in nonlinear
optimisation. This allows us to prove a stability-type generalisation of the
above and establish a surprising correspondence between extremal $k$-colourings
for this problem and perfect matchings in the $k$-dimensional hypercube $Q_k$.


title: Robust information propagation through noisy neural circuits

abstract:
  Sensory neurons give highly variable responses to stimulation, which can
limit the amount of stimulus information available to downstream circuits. Much
work has investigated the factors that affect the amount of information encoded
in these population responses, leading to insights about the role of
covariability among neurons, tuning curve shape, etc. However, the
informativeness of neural responses is not the only relevant feature of
population codes; of potentially equal importance is how robustly that
information propagates to downstream structures. For instance, to quantify the
retina's performance, one must consider not only the informativeness of the
optic nerve responses, but also the amount of information that survives the
spike-generating nonlinearity and noise corruption in the next stage of
processing, the lateral geniculate nucleus. Our study identifies the set of
covariance structures for the upstream cells that optimize the ability of
information to propagate through noisy, nonlinear circuits. Within this optimal
family are covariances with "differential correlations", which are known to
reduce the information encoded in neural population activities. Thus,
covariance structures that maximize information in neural population codes, and
those that maximize the ability of this information to propagate, can be very
different.


title:
Fractional powers of sectorial operators via the Dirichlet-to-Neumann
  operator

abstract:
  In the very influential paper \cite{CS07} Caffarelli and Silvestre studied
regularity of $(-\Delta)^s$, $0<s<1$, by identifying fractional powers with a
certain Dirichlet-to-Neumann operator. Stinga and Torrea \cite{ST10} and
Gal\'e, Miana and Stinga \cite{GMS13} gave several more abstract versions of
this extension procedure. The purpose of this paper is to study precise
regularity properties of the Dirichlet and the Neumann problem in Hilbert
spaces. Then the Dirichlet-to-Neumann operator becomes an isomorphism between
interpolation spaces and its part in the underlying Hilbert space is exactly
the fractional power.