title:
Field-insensitive heavy fermion features and phase transition in the
  caged-structure quasi-skutterudite Sm$_3$Ru$_4$Ge$_{13}$

abstract:
  The robust field-insensitive heavy fermion features in Sm$_3$Ru$_4$Ge$_{13}$
and the magnetic phase transition at $T_N \approx$ 5~K are studied using
magnetization $M(T)$, specific heat $C_p(T)$, resistivity $\rho(T)$ and thermal
conductivity $\kappa_T(T)$. The average crystal structure of
Sm$_3$Ru$_4$Ge$_{13}$ conforms to the cubic space group $Pm\bar{3}n$ however,
signatures of subtle structural distortions are obtained from the x ray data.
The magnetic susceptibility, $\chi(T)$, follows a modified Curie-Weiss law
indicating the presence of crystal fields of Sm$^{3+}$ and the significance of
van Vleck terms. No sign of ferromagnetism is observed in $M(H)$ of
Sm$_3$Ru$_4$Ge$_{13}$ which yields only 0.025~$\mu_\mathrm{B}$/f.u.-Sm at 2~K,
7~T. The Sommerfeld coefficient, $\gamma \approx$ 220~mJ/mol-Sm K$^2$,
estimated from the analysis of low temperature specific heat suggests the
formation of heavy quasi particles at low temperature. Though a ln$T$
dependence of $\rho(T)$ is observed till 60~K, the resistivity behavior is
accounted for by assuming a two-band model for activated behavior of charge
carriers. The field scans of resistivity, $\rho(H)$, below $T_N$ display
significant nonlinearity while those above the $T_N$ are more metal-like. Low
values of thermal conductivity, $\kappa_T(T)$, are observed in
Sm$_3$Ru$_4$Ge$_{13}$ however, displaying an anomaly at $T_N$ which signifies
magnetoelastic coupling. A fairly high value of Seebeck coefficient, $S
\approx$ 40~$\mu$V/K is observed at 300~K. We identify Sm$_3$Ru$_4$Ge$_{13}$ as
a low charge carrier density system with unusual field-insensitive heavy
fermion features very similar to the filled skutterudites.


title: A finitedimensional version of Fredholm representations

abstract:
  We consider pairs of maps from a discrete group to the unitary group. The
deficiencies of these maps from being homomorphisms may be great, but if they
are close to each other then we call such pairs balanced. We show that balanced
pairs determine elements in the K-theory group of the classifying space of the
discrete group. We also show that a Fredholm representation determines balanced
pairs.


title: Unique local determination of convex bodies

abstract:
  Barker and Larman asked the following. Let $K' \subset {\Bbb{R}}^d$ be a
convex body, whose interior contains a given convex body $K \subset
{\Bbb{R}}^d$, and let, for all supporting hyperplanes $H$ of $K$, the
$(d-1)$-volumes of the intersections $K' \cap H$ be given. Is $K'$ then
uniquely determined? Yaskin and Zhang asked the analogous question when, for
all supporting hyperplanes $H$ of $K$, the $d$-volumes of the "caps" cut off
from $K'$ by $H$ are given. We give local positive answers to both of these
questions, for small $C^2$-perturbations of $K$, provided the boundary of $K$
is $C^2_+$. In both cases, $(d-1)$-volumes or $d$-volumes can be replaced by
$k$-dimensional quermassintegrals for $1 \le k \le d-1$ or for $1 \le k \le d$,
respectively. Moreover, in the first case we can admit, rather than hyperplane
sections, sections by $l$-dimensional affine planes, where $1 \le k \le l \le
d-1$. In fact, here not all $l$-dimensional affine subspaces are needed, but
only a small subset of them (actually, a $(d-1)$-manifold), for unique local
determination of $K'$.


title:
How do difference bodies in complex vector spaces look like? A
  geometrical approach

abstract:
  We investigate geometrical properties and inequalities satisfied by the
complex difference body, in the sense of studying which of the classical ones
for the difference body have an analog in the complex framework. Among others
we give an equivalent expression for the support function of the complex
difference body and prove that, unlike the classical case, the dimension of the
complex difference body depends on the position of the body with respect to the
complex structure of the vector space. We use spherical harmonics to
characterize the bodies for which the complex difference body is a ball, we
prove that it is a polytope if and only if the two bodies involved in the
construction are polytopes and provide several inequalities for classical
magnitudes of the complex difference body, as volume, quermassintegrals and
diameter, in terms of the corresponding ones for the involved bodies.


title:
Conditional gradient type methods for composite nonlinear and stochastic
  optimization

abstract:
  In this paper, we present a conditional gradient type (CGT) method for
solving a class of composite optimization problems where the objective function
consists of a (weakly) smooth term and a (strongly) convex regularization term.
While including a strongly convex term in the subproblems of the classical
conditional gradient (CG) method improves its rate of convergence, it does not
cost per iteration as much as general proximal type algorithms. More
specifically, we present a unified analysis for the CGT method in the sense
that it achieves the best-known rate of convergence when the weakly smooth term
is nonconvex and possesses (nearly) optimal complexity if it turns out to be
convex. While implementation of the CGT method requires explicitly estimating
problem parameters like the level of smoothness of the first term in the
objective function, we also present a few variants of this method which relax
such estimation. Unlike general proximal type parameter free methods, these
variants of the CGT method do not require any additional effort for computing
(sub)gradients of the objective function and/or solving extra subproblems at
each iteration. We then generalize these methods under stochastic setting and
present a few new complexity results. To the best of our knowledge, this is the
first time that such complexity results are presented for solving stochastic
weakly smooth nonconvex and (strongly) convex optimization problems.


title:
Anomalous spectral shift of near- and far-field plasmonic resonances in
  nano-gaps

abstract:
  The near-field and far-field spectral response of plasmonic systems are often
assumed to be identical, due to the lack of methods that can directly compare
and correlate both responses under similar environmental conditions. We develop
a widely-tuneable optical technique to probe the near-field resonances within
individual plasmonic nanostructures that can be directly compared to the
corresponding far-field response. In tightly-coupled nanoparticle-on-mirror
constructs with nanometer-sized gaps we find >40meV blueshifts of the
near-field compared to the dark-field scattering peak, which agrees with full
electromagnetic simulations. Using a transformation optics approach, we show
such shifts arise from the different spectral interference between different
gap modes in the near- and far-field. The control and tuning of near-field and
far-field responses demonstrated here is of paramount importance in the design
of optical nanostructures for field-enhanced spectroscopy, as well as to
control near-field activity monitored through the far-field of nano-optical
devices.


title:
Algorithms and Heuristics for Scalable Betweenness Centrality
  Computation on Multi-GPU Systems

abstract:
  Betweenness Centrality (BC) is steadily growing in popularity as a metrics of
the influence of a vertex in a graph. The BC score of a vertex is proportional
to the number of all-pairs-shortest-paths passing through it. However, complete
and exact BC computation for a large-scale graph is an extraordinary challenge
that requires high performance computing techniques to provide results in a
reasonable amount of time. Our approach combines bi-dimensional (2-D)
decomposition of the graph and multi-level parallelism together with a suitable
data-thread mapping that overcomes most of the difficulties caused by the
irregularity of the computation on GPUs. Furthermore, we propose novel
heuristics which exploit the topology information of the graph in order to
reduce time and space requirements of BC computation. Experimental results on
synthetic and real-world graphs show that the proposed techniques allow the BC
computation of graphs which are too large to fit in the memory of a single
computational node along with a significant reduction of the computing time.


title: Generalized Gravitational Entropy from Various Matter Fields

abstract:
  The generalized gravitational entropy proposed in recent by Lewkowycz and
Maldacena [1] is extended to the systems of Boson fields, Fermion fields and
Maxwell fields which have arbitrary frequency and mode numbers on the BTZ
spacetime. We find the associated regular wave solution in each case and use it
to calculate the exact gravitational entropy. The results show that there is a
threshold frequency below which the Fermion fields could not contribute the
generalized gravitational entropy. Also, the static and zero-mode solutions
have no entropy, contrast to that in scalar fields. We also find that the
entropy of the static scalar fields and non-static fermions is an increasing
function of mode numbers and, after arriving the maximum entropy, it becomes a
deceasing function approaching to a constant value. We calculate the
gravitational entropy of Maxwell fields and use the duality between EM and
scalar fields to explain its result. The gravitational entropy from DBI action
is also studied.


title:
Lensing-induced morphology changes in CMB temperature maps in modified
  gravity theories

abstract:
  Lensing of the Cosmic Microwave Background (CMB) changes the morphology of
pattern of temperature fluctuations, so topological descriptors such as
Minkowski Functionals can probe the gravity model responsible for the lensing.
We show how the recently introduced two-to-two and three-to-one kurt-spectra
(and their associated correlation functions), which depend on the power
spectrum of the lensing potential, can be used to probe modified gravity
theories such as $f({R})$ theories of gravity and quintessence models. We also
investigate models based on effective field theory, which include the
constant-$\Omega$ model, and low-energy Ho\vrava theories. Estimates of the
cumulative signal-to-noise for detection of lensing-induced morphology changes,
reaches ${\cal O}(10^3)$ for the future planned CMB polarization mission
COrE$^{+}$. Assuming foreground removal is possible to $\ell_{max}=3000$, we
show that many modified gravity theories can be rejected with a high level of
significance, making this technique comparable in power to galaxy weak lensing
or redshift surveys. These topological estimators are also useful in
distinguishing {\em lensing} from other scattering secondaries at the level of
the four-point function or trispectrum. Examples include the kinetic
Sunyaev-Zel'dovich (kSZ) effect which shares, with lensing, a lack of spectral
distortion. We also discuss the complication of foreground contamination from
unsubtracted point sources.


title: The initial abundance and distribution of 92Nb in the Solar System

abstract:
  Niobium-92 is an extinct proton-rich nuclide, which decays to 92Zr with a
half-life of 37 Ma. This radionuclide potentially offers a unique opportunity
to determine the timescales of early Solar System processes and the site(s) of
nucleosynthesis for p-nuclei, once its initial abundance and distribution in
the Solar System are well established. Here we present internal Nb-Zr isochrons
for three basaltic achondrites with known U-Pb ages: the angrite NWA 4590, the
eucrite Agoult, and the ungrouped achondrite Ibitira. Our results show that the
relative Nb-Zr isochron ages of the three meteorites are consistent with the
time intervals obtained from the Pb-Pb chronometer for pyroxene and
plagioclase, indicating that 92Nb was homogeneously distributed among their
source regions. The Nb-Zr and Pb-Pb data for NWA 4590 yield the most reliable
and precise reference point for anchoring the Nb-Zr chronometer to the absolute
timescale: an initial 92Nb/93Nb ratio of $(1.4 \pm 0.5) \times 10^{-5}$ at
$4557.93 \pm 0.36$ Ma, which corresponds to a 92Nb/93Nb ratio of $(1.7 \pm 0.6)
\times 10^{-5}$ at the time of the Solar System formation. On the basis of this
new initial ratio, we demonstrate the capability of the Nb-Zr chronometer to
date early Solar System objects including troilite and rutile, such as iron and
stony-iron meteorites. Furthermore, we estimate a nucleosynthetic production
ratio of 92Nb to the p-nucleus 92Mo between 0.0015 and 0.035. This production
ratio, together with the solar abundances of other p-nuclei with similar
masses, can be best explained if these light p-nuclei were primarily
synthesized by photodisintegration reactions in Type Ia supernovae.


title:
The role of the Rogers-Shephard inequality in the characterization of
  the difference body

abstract:
  The difference body operator enjoys different characterization results
relying on its basic properties such as continuity, SL(n)-covariance, Minkowski
valuation or symmetric image. The Rogers-Shephard and the Brunn-Minkowski
inequalities provide upper and lower bounds for the volume of the difference
body in terms of the volume of the body itself. In this paper we aim to
understand the role of the Rogers-Shephard inequality in characterization
results of the difference body and, at the same time, to study the interplay
among the different properties. Among others, we prove that the difference body
operator is the only continuous and GL(n)-covariant operator from the space of
convex bodies to the origin-symmetric ones which satisfies a Rogers-Shephard
type inequality while every continuous and GL(n)-covariant operator satisfies a
Brunn-Minkowski type inequality.


title: Majorana bound states in magnetic skyrmions

abstract:
  Magnetic skyrmions are highly mobile nanoscale topological spin textures. We
show, both analytically and numerically, that a magnetic skyrmion of an even
azimuthal winding number placed in proximity to an s-wave superconductor hosts
a zero-energy Majorana bound state in its core, when the exchange coupling
between the itinerant electrons and the skyrmion is strong. This Majorana bound
state is stabilized by the presence of a spin-orbit interaction. We propose the
use of a superconducting tri-junction to realize non-Abelian statistics of such
Majorana bound states.


title: Balanced Non-Transitive Dice

abstract:
  We study triples of labeled dice in which the relation "is a better die than"
is non-transitive. Focusing on such triples with an additional symmetry we call
"balance," we prove that such triples of $n$-sided dice exist for all $n \geq
3$. We then examine the sums of the labels of such dice, and use these results
to construct an $O(n^2)$ algorithm for verifying whether or not a triple of
$n$-sided dice is balanced and non-transitive. Finally, we consider
generalizations to larger sets of dice.


title: Visual descriptors for content-based retrieval of remote sensing images

abstract:
  In this paper we present an extensive evaluation of visual descriptors for
the content-based retrieval of remote sensing (RS) images. The evaluation
includes global hand-crafted, local hand-crafted, and Convolutional Neural
Network (CNNs) features coupled with four different Content-Based Image
Retrieval schemes. We conducted all the experiments on two publicly available
datasets: the 21-class UC Merced Land Use/Land Cover (LandUse) dataset and
19-class High-resolution Satellite Scene dataset (SceneSat). The content of RS
images might be quite heterogeneous, ranging from images containing fine
grained textures, to coarse grained ones or to images containing objects. It is
therefore not obvious in this domain, which descriptor should be employed to
describe images having such a variability. Results demonstrate that CNN-based
features perform better than both global and and local hand-crafted features
whatever is the retrieval scheme adopted. Features extracted from SatResNet-50,
a residual CNN suitable fine-tuned on the RS domain, shows much better
performance than a residual CNN pre-trained on multimedia scene and object
images. Features extracted from NetVLAD, a CNN that considers both CNN and
local features, works better than others CNN solutions on those images that
contain fine-grained textures and objects.


title:
On the crystalline structure of orthorhombic SrRuO$_3$: A benchmark
  study of DFT functionals

abstract:
  By investigating the crystalline structure of ground-state orthorhombic
SrRuO$_3$, we present a benchmark study of some of the most popular density
functional theory (DFT) approaches from the local density approximation (LDA),
generalized-gradient approximation (GGA), and hybrid functional families.
Recent experimental success in stabilizing tetragonal and monoclinic phases of
SrRuO$_3$ at room temperature sheds a new light on the ability to accurately
describe geometry of this material by applying first-principles calculations.
Therefore, our work is aimed to analyse the performance of different DFT
functionals and provide some recommendations for future research of SrRuO$_3$.
A comparison of the obtained results to the low-temperature experimental data
indicates that revised GGAs for solids are the best choice for the lattice
constants and volume due to their nice accuracy and low computational cost.
However, when tilting and rotation angles appear on the scene, a combination of
the revised GGAs with the hybrid scheme becomes the most preferable option. It
is important to note that a worse performance of LDA functional is somewhat
compensated by its realistic reproduction of electronic and magnetic structure
of SrRuO$_3$, making it a strong competitor if the physical features are also
taken into account.


title:
Some Results in the Theory of Low-lying Zeros: Determining the 1-level
  density, identifying the group symmetry and the arithmetic of moments of
  Satake parameters

abstract:
  While Random Matrix Theory has successfully modeled many quantities of
families of L-functions, it frequently cannot see the family's arithmetic. In
some situations this requires an extended theory that inserts arithmetic
factors depending on the family, while in other cases these factors result in
contributions which vanish in the limit, and are thus not detected. We review
the general theory associated to one of the most important statistics, the
n-level density of zeros near the central point. According to the Katz-Sarnak
density conjecture, to each family of L-functions there is a corresponding
symmetry group such that the behavior of zeros near the central point as the
conductors tend to infinity agrees with the behavior of eigenvalues near 1 as
the matrix size tends to infinity. We show how these calculations are done,
emphasizing the techniques, methods and obstructions to improving the results,
by considering in full detail a family of Dirichlet characters. We then
describe how we may associate a symmetry constant to each family, and how to
determine the symmetry group of a compound family in terms of the symmetries of
the constituents. These calculations explain the remarkable universality of
behavior, where the main terms are independent of the arithmetic (only the
first two moments of the Satake parameters contribute in the limit; similar to
the Central Limit Theorem, the higher moments are only felt in the rate of
convergence). We end by exploring lower order terms in families of elliptic
curves. We present evidence supporting a conjecture that the average second
moment in one-parameter families without complex multiplication has, when
appropriately viewed, a negative bias, and end with a discussion of the
consequences of this bias on the distribution of low-lying zeros, in particular
relations between such a bias and the observed excess rank in families.


title:
Rate and Aging Time Dependent Static Friction of a Soft and Hard Solid
  Interface

abstract:
  In this article, we present a mathematical model that answers a classical
question concerning how much force, which is generally called static friction
force, will it require to initiate the motion of a soft solid block such as
gel, rubber or elastomer on a hard surface for instance glass surface. The
model uses population balance of the bonds between the polymer chains of the
soft solid and the hard surface to estimate rate and aging time dependent
static friction. The model predicts that under certain range of the pulling
velocity, the friction stress at the onset of sliding (static friction stress)
varies as the logarithm of the pulling velocity, as well as the logarithm of
the aging time. These predictions are consistent with the experimental
observations.


title:
Efficient mode conversion in an optical nanoantenna mediated by quantum
  emitters

abstract:
  Converting signals between different electromagnetic modes is an asset for
future information technologies. In general, slightly asymmetric optical
nanoantennas enable the coupling between bright and dark modes sustained by an
optical nanoantenna. However, the conversion efficiency might be very low.
Here, we show that the additional incorporation of a quantum emitter allows to
tremendously enhance this efficiency. The enhanced local density of states
cycles the quantum emitter between its upper and lower level at an extremely
hight rate; hence converting the energy very efficient. The process is robust
with respect to possible experimental tolerances and adds a new ingredient to
be exploited while studying and applying coupling phenomena in optical
nanosystems.


title: BotOrNot: A System to Evaluate Social Bots

abstract:
  While most online social media accounts are controlled by humans, these
platforms also host automated agents called social bots or sybil accounts.
Recent literature reported on cases of social bots imitating humans to
manipulate discussions, alter the popularity of users, pollute content and
spread misinformation, and even perform terrorist propaganda and recruitment
actions. Here we present BotOrNot, a publicly-available service that leverages
more than one thousand features to evaluate the extent to which a Twitter
account exhibits similarity to the known characteristics of social bots. Since
its release in May 2014, BotOrNot has served over one million requests via our
website and APIs.


title: Solutions of perturbed Hammerstein integral equations with applications

abstract:
  By means of topological methods, we provide new results on the existence,
non-existence, localization and multiplicity of nontrivial solutions for
systems of perturbed Hammerstein integral equations. In order to illustrate our
theoretical results, we study some problems that occur in applied mathematics,
namely models of chemical reactors, beams and thermostats. We also apply our
theory in order to prove the existence of nontrivial radial solutions of
systems of elliptic boundary value problems subject to nonlocal, nonlinear
boundary conditions.


title: Systematic Study of Diphoton Resonance at 750 GeV from Sgoldstino

abstract:
  The ATLAS and CMS Collaborations of the Large Hadron Collider (LHC) have
reported an excess of events in diphoton channel with invariant mass of about
750 GeV. With low energy supersymmetry breaking, we systematically consider the
sgoldstino scalar $S$ as the new resonance, which is a linear combination of
the CP-even scalar $s$ and CP-odd pseudoscalar $a$. Because we show that $s$
and $a$ can be degenerated or have large mass splitting, we consider two cases
for all the following three scenarios: (1) Single resonance. $s$ is the 750 GeV
resonance decays to a pair of 1 GeV pseudoscalar $a$. With suitable decay
length, these two $a$ decay into collimated pair of photons which cannot be
distinguished at the LHC and may appear as diphotons instead of four photons.
(2) Twin resonances. $m_{s}\approx m_{a}$ with a mass difference of about 40
GeV and both $s$ and $a$ decay into diphoton pairs. For productions, we
consider three scenarios: (I) vector boson fusion; (II) gluon gluon fusion;
(III) $q{\bar q}$ pair production. In all these scenarios with two kinds of
resonances, we find the parameter space that satisfies the diphoton production
cross section from 3 to 13 ${\rm fb}$ and all the other experimental
constraints. And we address the decay width as well. In particular, in the
third scenario, we observe that the production cross section is small but the
decay width of $s$ or $a$ can be from 40 to 60 GeV.


title:
Exciton Brightening in Monolayer Phosphorene via Dimensionality
  Modification

abstract:
  Two-dimensional (2D) monolayer phosphorene, a 2D system with
quasi-one-dimensional (quasi-1D) excitons, provides a unique 2D platform for
investigating the dynamics of excitons in reduced dimensions and fundamental
many-body interactions. However, on the other hand, the quasi-1D excitonic
nature can limit the luminescence quantum yield significantly. Here, we report
exciton brightening in monolayer phosphorene achieved via the dimensionality
modification of excitons from quasi-1D to zero-dimensional (0D), through the
transference of monolayer phosphorene samples onto defect-rich oxide substrate
deposited by plasma-enhanced chemical vapor deposition (PECVD). The resultant
interfacial luminescent local states lead to exciton localization and trigger
efficient photon emissions at a new wavelength of ~920 nm. The luminescence
quantum yield of 0D-like localized excitons is measured to be at least 33.6
times larger than that of intrinsic quasi-1D free excitons in monolayer
phosphorene. This is primarily due to the reduction of non-radiative decay rate
and the possibly enhanced radiative recombination probability. Owing to the
large trapping energy, this new photon emission from the localized excitons in
monolayer phosphorene can be observed at elevated temperature, which contrasts
markedly with defect-induced photon emission from transition metal
dichalcogenide (TMD) semiconductor monolayers that can only be observed at
cryogenic temperatures. Our findings introduce new avenues for the development
of novel photonic devices based on monolayer phosphorene, such as near-infrared
lighting devices that are operable at elevated temperature. More importantly,
2D phosphorene with quasi-1D free excitons and 0D-like localized excitons
provides a unique platform to investigate the fundamental phenomena in the
ideal 2D-1D-0D hybrid system.


title:
Sudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep
  optical lattices

abstract:
  We determine the exact dynamics of an initial Bardeen-Cooper-Schrieffer (BCS)
state of ultra-cold atoms in a deep hexagonal optical lattice. The dynamical
evolution is triggered by a quench of the lattice potential, such that the
interaction strength $U_f$ is much larger than the hopping amplitude $J_f$. The
quench initiates collective oscillations with frequency $|U_f|/(2\pi)$ in the
momentum occupation numbers and imprints an oscillating phase with the same
frequency on the BCS order parameter $\Delta$. The oscillation frequency of
$\Delta$ is not reproduced by treating the time evolution in mean-field theory.
In our theory, the momentum noise (i.e. density-density) correlation functions
oscillate at frequency $|U_f|/2\pi$ as well as at its second harmonic. For a
very deep lattice, with zero tunneling energy, the oscillations of momentum
occupation numbers are undamped. Non-zero tunneling after the quench leads to
dephasing of the different momentum modes and a subsequent damping of the
oscillations. The damping occurs even for a finite-temperature initial BCS
state, but not for a non-interacting Fermi gas. Furthermore, damping is
stronger for larger order parameter and may therefore be used as a signature of
the BCS state. Finally, our theory shows that the noise correlation functions
in a honeycomb lattice will develop strong anti-correlations near the Dirac
point.

categories: cond-mat.quant-gas cond-mat.str-el physics.atom-ph quant-ph


title:
On the number of fibrations transversal to a rational curve in a complex
  surface

abstract:
  We investigate the existence, and lack of unicity, of a holomorphic fibration
by discs transversal to a rational curve in a complex surface.


title: CPL: A Core Language for Cloud Computing -- Technical Report

abstract:
  Running distributed applications in the cloud involves deployment. That is,
distribution and configuration of application services and middleware
infrastructure. The considerable complexity of these tasks resulted in the
emergence of declarative JSON-based domain-specific deployment languages to
develop deployment programs. However, existing deployment programs unsafely
compose artifacts written in different languages, leading to bugs that are hard
to detect before run time. Furthermore, deployment languages do not provide
extension points for custom implementations of existing cloud services such as
application-specific load balancing policies.
  To address these shortcomings, we propose CPL (Cloud Platform Language), a
statically-typed core language for programming both distributed applications as
well as their deployment on a cloud platform. In CPL, application services and
deployment programs interact through statically typed, extensible interfaces,
and an application can trigger further deployment at run time. We provide a
formal semantics of CPL and demonstrate that it enables type-safe, composable
and extensible libraries of service combinators, such as load balancing and
fault tolerance.


title: Some generalisations of the inequalities for positive linear maps

abstract:
  We obtain generalisations of some inequalities for positive unital linear
maps on matrix algebra. This also provides several positive semidefinite
matrices and we get some old and new inequalities involving the eigenvalues of
a Hermitian matrix.


title: A bundling problem revisited

abstract:
  It was conjectured by M. Glasser and S. Davison and later proved by A.
Eremenko that the certain animals should gather close to each other in order to
decrease the total heat loss. In this paper we show that it is not always true
for the individual heat loss. This gives a negative answer to a question posed
by A. Eremenko.


title:
The Influence of the Java Collection Framework on Overall Energy
  Consumption

abstract:
  This paper presents a detailed study of the energy consumption of the
different Java Collection Framework (JFC) implementations. For each method of
an implementation in this framework, we present its energy consumption when
handling different amounts of data. Knowing the greenest methods for each
implementation, we present an energy optimization approach for Java programs:
based on calls to JFC methods in the source code of a program, we select the
greenest implementation. Finally, we present preliminary results of optimizing
a set of Java programs where we obtained 6.2% energy savings.


title: Mental State Recognition via Wearable EEG

abstract:
  The increasing quality and affordability of consumer electroencephalogram
(EEG) headsets make them attractive for situations where medical grade devices
are impractical. Predicting and tracking cognitive states is possible for tasks
that were previously not conducive to EEG monitoring. For instance, monitoring
operators for states inappropriate to the task (e.g. drowsy drivers), tracking
mental health (e.g. anxiety) and productivity (e.g. tiredness) are among
possible applications for the technology. Consumer grade EEG headsets are
affordable and relatively easy to use, but they lack the resolution and quality
of signal that can be achieved using medical grade EEG devices. Thus, the key
questions remain: to what extent are wearable EEG devices capable of mental
state recognition, and what kind of mental states can be accurately recognized
with these devices? In this work, we examined responses to two different types
of input: instructional (logical) versus recreational (emotional) videos, using
a range of machine-learning methods. We tried SVMs, sparse logistic regression,
and Deep Belief Networks, to discriminate between the states of mind induced by
different types of video input, that can be roughly labeled as logical vs.
emotional. Our results demonstrate a significant potential of wearable EEG
devices in differentiating cognitive states between situations with large
contextual but subtle apparent differences.


title:
Revenue maximization in an optical router node - allocation of service
  windows

abstract:
  In this paper we study a revenue maximization problem for optical routing
nodes. We model the routing node as a single server polling model with the aim
to assign visit periods (service windows) to the different stations (ports)
such that the mean profit per cycle is maximized. Under reasonable assumptions
regarding retrial and dropping probabilities of packets the optimization
problem becomes a separable concave resource allocation problem, which can be
solved using existing algorithms.


title:
A Search for Brief Optical Flashes Associated with the SETI Target KIC
  8462852

abstract:
  The F-type star KIC 8462852 has recently been identified as an exceptional
target for SETI (search for extraterrestrial intelligence) observations. We
describe an analysis methodology for optical SETI, which we have used to
analyse nine hours of serendipitous archival observations of KIC 8462852 made
with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of
pulsed optical beacons, above a pulse intensity at the Earth of approximately 1
photon per m^2, is found. We also discuss the potential use of imaging
atmospheric Cherenkov telescope arrays in searching for extremely short
duration optical transients in general.


title:
Measurement of the charged-particle multiplicity inside jets from
  $\sqrt{s}=8$ TeV $pp$ collisions with the ATLAS detector

abstract:
  The number of charged particles inside jets is a widely used discriminant for
identifying the quark or gluon nature of the initiating parton and is sensitive
to both the perturbative and non-perturbative components of fragmentation. This
paper presents a measurement of the average number of charged particles with
$p_\text{T}>500$ MeV inside high-momentum jets in dijet events using 20.3
fb$^{-1}$ of data recorded with the ATLAS detector in $pp$ collisions at
$\sqrt{s}=8$ TeV collisions at the LHC. The jets considered have transverse
momenta from 50 GeV up to and beyond 1.5 TeV. The reconstructed
charged-particle track multiplicity distribution is unfolded to remove
distortions from detector effects and the resulting charged-particle
multiplicity is compared to several models. Furthermore, quark and gluon jet
fractions are used to extract the average charged-particle multiplicity for
quark and gluon jets separately.


title:
Quantifying Artifacts over Time: Interval Estimation of a Poisson
  Distribution using the Jeffreys Prior

abstract:
  This article presents a new method for estimating the amount of an artifact
class in use at a given moment in the past from a random assemblage of
archaeological finds. This method is based on the use of simulation, since an
analytical solution is computationally impractical. Estimating the number of
artifacts in use at any time $t$ is shown to follow a Poisson distribution,
which allows for credible intervals to be established using the Jeffreys prior.
This estimator works from minimal assumptions about the dating and duration of
finds, as well as the intensity of collection, and is applied to coinage from
four Roman-period sites excavated by the Roman Peasant Project (2009-2014). The
result provides for an estimation of the abundance of material according to an
interval of certainty.


title:
Engineering of frustration in colloidal artificial ices realized on
  microfeatured grooved lattices

abstract:
  Artificial spin ice systems, namely lattices of interacting single domain
ferromagnetic islands, have been used to date as microscopic models of
frustration induced by lattice topology, allowing for the direct visualization
of spin arrangements and textures. However, the engineering of frustrated ice
states in which individual spins can be manipulated in situ and the real-time
observation of their collective dynamics remain both challenging tasks.
Inspired by recent theoretical advances, here we realize a colloidal version of
an artificial spin ice system using interacting polarizable particles confined
to lattices of bistable gravitational traps. We show quantitatively that
ice-selection rules emerge in this frustrated soft matter system by tuning the
strength of the pair interactions between the microscopic units. Via
independent control of particle positioning and dipolar coupling, we introduce
monopole-like defects and strings and use loops with defined chirality as an
elementary unit to store binary information.


title: Deep Tracking: Seeing Beyond Seeing Using Recurrent Neural Networks

abstract:
  This paper presents to the best of our knowledge the first end-to-end object
tracking approach which directly maps from raw sensor input to object tracks in
sensor space without requiring any feature engineering or system identification
in the form of plant or sensor models. Specifically, our system accepts a
stream of raw sensor data at one end and, in real-time, produces an estimate of
the entire environment state at the output including even occluded objects. We
achieve this by framing the problem as a deep learning task and exploit
sequence models in the form of recurrent neural networks to learn a mapping
from sensor measurements to object tracks. In particular, we propose a learning
method based on a form of input dropout which allows learning in an
unsupervised manner, only based on raw, occluded sensor data without access to
ground-truth annotations. We demonstrate our approach using a synthetic dataset
designed to mimic the task of tracking objects in 2D laser data -- as commonly
encountered in robotics applications -- and show that it learns to track many
dynamic objects despite occlusions and the presence of sensor noise.


title: Virasoro and KdV

abstract:
  We investigate the structure of representations of the (positive half of the)
Virasoro algebra and situations in which they decompose as a tensor product of
Lie algebra representations. As an illustration, we apply these results to the
differential operators defined by the Virasoro conjecture and obtain some
factorization properties of the solutions as well as a link to the
multicomponent KP hierarchy.


title:
Merged or monolithic? Using machine-learning to reconstruct the
  dynamical history of simulated star clusters

abstract:
  Context. Machine-Learning (ML) solves problems by learning patterns from
data, with limited or no human guidance. In Astronomy, it is mainly applied to
large observational datasets, e.g. for morphological galaxy classification.
Aims. We apply ML to gravitational N-body simulations of star clusters that are
either formed by merging two progenitors or evolved in isolation, planning to
later identify Globular Clusters (GCs) that may have a history of merging from
observational data. Methods. We create mock-observations from simulated GCs,
from which we measure a set of parameters (also called features in the
machine-learning field). After dimensionality reduction on the feature space,
the resulting datapoints are fed to various classification algorithms. Using
repeated random subsampling validation we check whether the groups identified
by the algorithms correspond to the underlying physical distinction between
mergers and monolithically evolved simulations. Results. The three algorithms
we considered (C5.0 trees, k-nearest neighbour, and support-vector machines)
all achieve a test misclassification rate of about 10% without parameter
tuning, with support-vector machines slightly outperforming the others. The
first principal component of feature space correlates with cluster
concentration. If we exclude it from the regression, the performance of the
algorithms is only slightly reduced.


title: Automatic City Region Analysis for Urban Routing

abstract:
  There are different functional regions in cities such as tourist attractions,
shopping centers, workplaces and residential places. The human mobility
patterns for different functional regions are different, e.g., people usually
go to work during daytime on weekdays, and visit shopping centers after work.
In this paper, we analyse urban human mobility patterns and infer the functions
of the regions in three cities. The analysis is based on three large taxi GPS
datasets in Rome, San Francisco and Beijing containing 21 million, 11 million
and 17 million GPS points respectively. We categorized the city regions into
four kinds of places, workplaces, entertainment places, residential places and
other places. First, we provide a new quad-tree region division method based on
the taxi visits. Second, we use the association rule to infer the functional
regions in these three cities according to temporal human mobility patterns.
Third, we show that these identified functional regions can help us deliver
data in network applications, such as urban Delay Tolerant Networks (DTNs),
more efficiently. The new functional-regions-based DTNs algorithm achieves up
to 183% improvement in terms of delivery ratio.


title:
Stochastic collocation methods via $L_1$ minimization using randomized
  quadratures

abstract:
  In this work, we discuss the problem of approximating a multivariate function
via $\ell_1$ minimization method, using a random chosen sub-grid of the
corresponding tensor grid of Gaussian points. The independent variables of the
function are assumed to be random variables, and thus, the framework provides a
non-intrusive way to construct the generalized polynomial chaos expansions,
stemming from the motivating application of Uncertainty Quantification (UQ). We
provide theoretical analysis on the validity of the approach. The framework
includes both the bounded measures such as the uniform and the Chebyshev
measure, and the unbounded measures which include the Gaussian measure. Several
numerical examples are given to confirm the theoretical results.


title: Construction of simple non-weight sl(2)-modules of arbitrary rank

abstract:
  We study simple non-weight ${\mathfrak{sl}}(2)$-modules which are finitely
generated as ${\mathbb C}[z]$-modules. We show that they are described in terms
of semilinear endomorphisms and prove that the Smith type induces a
stratification on the set of these ${\mathfrak{sl}}(2)$-modules, providing thus
new invariants. Moreover, we show that there is a notion of duality for these
type of ${\mathfrak{sl}}(2)$-modules. Finally, we show that there are simple
non-weight ${\mathfrak{sl}}(2)$-modules of arbitrary rank by constructing a
whole new family of them.


title: Head Pose Estimation of Occluded Faces using Regularized Regression

abstract:
  This paper presents regression methods for estimation of head pose from
occluded 2-D face images. The process primarily involves reconstructing a face
from its occluded image, followed by classification. Typical methods for
reconstruction assume that the pixel errors of the occluded regions are
independent. However, such an assumption is not true in the case of occlusion,
because of its inherent contiguous nature. Hence, we use nuclear norm as a
metric that can describe well the structure of the error. We also use LASSO
Regression based l1 - regularization to improve reconstruction. Next, we
implement Nuclear Norm Regularized Regression (NR), and also our proposed
method, for reconstruction and subsequent classification. Finally, we compare
the performance of the methods in terms of accuracy of head pose estimation of
occluded faces.


title:
A combinatorial approach to certain topological spaces based on minimum
  complement S-approximation spaces

abstract:
  An S-approximation space is a novel approach to study systems with
uncertainty that are not expressible in terms of inclusion relations. In this
work, we further examined these spaces, mostly from a topological point of view
by a combinatorial approach. This work also identifies a subclass of these
approximation spaces, called $S_\mathcal{MC}$-approximations. Topological
properties of this subclass are investigated and finally, the topologies formed
by $S_\mathcal{MC}$-approximations are enumerated up to homeomorphism.


title: Geometrization of the local Langlands correspondence: an overview

abstract:
  This article is an overview of the geometrization conjecture for the local
Langlands correspondence formulated by the author.


title: The polar family of webs and foliations

abstract:
  We define the polar curves and the polar family associated to a projective
web and obtain some results about the geometry of the generic element of this
family. We also deal with the particular case of foliations and prove the
constancy of the topological embedded type of the generic polar.


title:
Spontaneous symmetry breaking of self-trapped and leaky modes in
  quasi-double-well potentials

abstract:
  We investigate competition between two phase transitions of the second kind
induced by the self-attractive nonlinearity, viz., self-trapping of the leaky
modes, and spontaneous symmetry breaking (SSB) of both fully trapped and leaky
states. We use a one-dimensional mean-field model, which combines the cubic
nonlinearity and a double-well-potential (DWP) structure with an elevated
floor, which supports leaky modes (quasi-bound states) in the linear limit. The
setting can be implemented in nonlinear optics and BEC. The order in which the
SSB and self-trapping transitions take place with the growth of the
nonlinearity strength depends on the height of the central barrier of the DWP:
the SSB happens first if the barrier is relatively high, while self-trapping
comes first if the barrier is lower. The SSB of the leaky modes is
characterized by specific asymmetry of their radiation tails, which, in
addition, feature a resonant dependence on the relation between the total size
of the system and radiation wavelength. As a result of the SSB, the instability
of symmetric modes initiates spontaneous Josephson oscillations. Collisions of
freely moving solitons with the DWP structure admit trapping of an incident
soliton into a state of persistent shuttle motion, due to emission of
radiation. The study is carried out numerically, and basic results are
explained by means of analytical considerations.


title:
The Role of Short-Range Order and Hyperuniformity in the Formation of
  Band Gaps in Disordered Photonic Materials

abstract:
  We study photonic band gap formation in two-dimensional high refractive index
disordered materials where the dielectric structure is derived from packing
disks in real and reciprocal space. Numerical calculations of the photonic
density of states demonstrate the presence of a band gap for all polarizations
in both cases. We find that the band gap width is controlled by the increase in
positional correlation inducing short-range order and hyperuniformity
concurrently. Our findings suggest that the optimization of short-range order,
in particular the tailoring of Bragg scattering at the isotropic Brillouin
zone, are of key importance for designing disordered PBG materials.

categories: physics.optics cond-mat.mtrl-sci cond-mat.soft cond-mat.stat-mech


title:
Using Node Centrality and Optimal Control to Maximize Information
  Diffusion in Social Networks

abstract:
  We model information dissemination as a susceptible-infected epidemic process
and formulate a problem to jointly optimize seeds for the epidemic and time
varying resource allocation over the period of a fixed duration campaign
running on a social network with a given adjacency matrix. Individuals in the
network are grouped according to their centrality measure and each group is
influenced by an external control function---implemented through
advertisements---during the campaign duration. The aim is to maximize an
objective function which is a linear combination of the reward due to the
fraction of informed individuals at the deadline, and the aggregated cost of
applying controls (advertising) over the campaign duration. We also study a
problem variant with a fixed budget constraint. We set up the optimality system
using Pontryagin's Maximum Principle from optimal control theory and solve it
numerically using the forward-backward sweep technique. Our formulation allows
us to compare the performance of various centrality measures (pagerank, degree,
closeness and betweenness) in maximizing the spread of a message in the optimal
control framework. We find that degree---a simple and local measure---performs
well on the three social networks used to demonstrate results: scientific
collaboration, Slashdot and Facebook. The optimal strategy targets central
nodes when the resource is scarce, but non-central nodes are targeted when the
resource is in abundance. Our framework is general and can be used in similar
studies for other disease or information spread models---that can be modeled
using a system of ordinary differential equations---for a network with a known
adjacency matrix.

categories: cs.SI cs.MA cs.SY math.OC physics.soc-ph


title: Introduction to Galactic Chemical Evolution

abstract:
  In this lecture I will introduce the concept of galactic chemical evolution,
namely the study of how and where the chemical elements formed and how they
were distributed in the stars and gas in galaxies. The main ingredients to
build models of galactic chemical evolution will be described. They include:
initial conditions, star formation history, stellar nucleosynthesis and gas
flows in and out of galaxies. Then some simple analytical models and their
solutions will be discussed together with the main criticisms associated to
them. The yield per stellar generation will be defined and the hypothesis of
instantaneous recycling approximation will be critically discussed. Detailed
numerical models of chemical evolution of galaxies of different morphological
type, able to follow the time evolution of the abundances of single elements,
will be discussed and their predictions will be compared to observational data.
The comparisons will include stellar abundances as well as interstellar medium
ones, measured in galaxies. I will show how, from these comparisons, one can
derive important constraints on stellar nucleosynthesis and galaxy formation
mechanisms. Most of the concepts described in this lecture can be found in the
monograph by Matteucci (2012).


title: Deterministic Single-Phonon Source Triggered by a Single Photon

abstract:
  We propose a scheme that enables the deterministic generation of single
phonons at GHz frequencies triggered by single photons in the near infrared.
This process is mediated by a quantum dot embedded on-chip in an
opto-mechanical circuit, which allows for the simultaneous control of the
relevant photonic and phononic frequencies. We devise new opto-mechanical
circuit elements that constitute the necessary building blocks for the proposed
scheme and are readily implementable within the current state-of-the-art of
nano-fabrication. This will open new avenues for implementing quantum
functionalities based on phonons as an on-chip quantum bus.


title: A-expansion for multiple "hedgehog" shapes

abstract:
  Overlapping colors and cluttered or weak edges are common segmentation
problems requiring additional regularization. For example, star-convexity is
popular for interactive single object segmentation due to simplicity and
amenability to exact graph cut optimization. This paper proposes an approach to
multiobject segmentation where objects could be restricted to separate
"hedgehog" shapes. We show that a-expansion moves are submodular for our
multi-shape constraints. Each "hedgehog" shape has its surface normals
constrained by some vector field, e.g. gradients of a distance transform for
user scribbles. Tight constraint give an extreme case of a shape prior
enforcing skeleton consistency with the scribbles. Wider cones of allowed
normals gives more relaxed hedgehog shapes. A single click and +/-90 degrees
normal orientation constraints reduce our hedgehog prior to star-convexity. If
all hedgehogs come from single clicks then our approach defines multi-star
prior. Our general method has significantly more applications than standard
one-star segmentation. For example, in medical data we can separate multiple
non-star organs with similar appearances and weak or noisy edges.


title: Optimal Real-Time Bidding Frameworks Discussion

abstract:
  This note is a complementary material for the solution of optimal real-time
bidding function in paper "Optimal Real-Time Bidding for Display Advertising,
KDD 2014", where the estimated cost is taken as the bid price, i.e., the upper
bound of the true cost. Here we discuss a more general bid optimisation
framework with various utility and cost functions.


title:
A possible Chandra and Hubble Space Telescope detection of extragalactic
  WHIM towards PG 1116+215

abstract:
  (Abridged) We have analyzed Chandra LETG and XMM-Newton RGS spectra towards
the z=0.177 quasar PG 1116+215, a sightline that is rendered particularly
interesting by the HST detection of several OVI and HI broad Lyman-alpha
absorption lines that may be associated with the warm-hot intergalactic medium.
We performed a search for resonance K-alpha absorption lines from OVII and
OVIII at the redshifts of the detected far-ultraviolet lines. We detected an
absorption line in the Chandra spectra at 5.2 sigma confidence level at
wavelengths corresponding to OVIII K-alpha at z=0.0911+-0.0004+-0.0005
(statistical followed by systematic error). This redshift is within 3 sigma of
that of a HI broad Lyman-alpha of b=130 km/s at z=0.09279+-0.00005. We have
also analyzed the available XMM-Newton RGS data towards PG 1116+215.
Unfortunately, the XMM-Newton data are not suitable to investigate this line
because of instrumental features at the wavelengths of interest. At the same
redshift, the Chandra and XMM-Newton spectra have OVII K-alpha absorption line
features of significance 1.5 sigma and 1.8 sigma, respectively. We also
analyzed the available SDSS spectroscopic galaxy survey data towards PG
1116+215 in the redshift range of interest. We found evidence for a galaxy
filament that intersects the PG 1116+215 sightline and additional galaxy
structures that may host WHIM. The combination of HST, Chandra, XMM-Newton and
SDSS data indicates that we have likely detected a multi-temperature WHIM at
z=0.091-0.093 towards PG 1116+215.


title: Traffic flow densities in large transport networks

abstract:
  We consider transport networks with nodes scattered at random in a large
domain. At certain local rates, the nodes generate traffic flowing according to
some navigation scheme in a given direction. In the thermodynamic limit of a
growing domain, we present an asymptotic formula expressing the local traffic
flow density at any given location in the domain in terms of three fundamental
characteristics of the underlying network: the spatial intensity of the nodes
together with their traffic generation rates, and of the links induced by the
navigation. This formula holds for a general class of navigations satisfying a
link-density and a sub-ballisticity condition. As a specific example, we verify
these conditions for navigations arising from a directed spanning tree on a
Poisson point process with inhomogeneous intensity function.


title: Injectivity and Surjectivity of the Dress Map

abstract:
  For a nontrivial finite Galois extension $L/k$ (where the characteristic of
$k$ is different from 2) with Galois group $G$, we prove that the Dress map
$h_{L/k}: A(G) \to GW(k)$ is injective if and only if $L=k(\sqrt{\alpha})$
where $\alpha$ is not a sum of squares in $k^\times$. Furthermore, we prove
that $h_{L/k}$ is surjective if and only if $k$ is quadratically closed in $L$.
As a consequence, we give strong necessary conditions for faithfulness of the
Heller-Ormsby functor $c_{L/k}^* : \text{SH}_G\to \text{SH}_k$, as well as
strong necessary conditions for fullness of $c_{L/k}^*$.


title: Diophantine equations via cluster transformations

abstract:
  Motivated by Fomin and Zelevinsky's theory of cluster algebras we introduce a
variant of the Markov equation; we show that all natural solutions of the
equation arise from an initial solution by cluster transformations.


title:
Constraints on Dark Matter Annihilation/Decay from the Isotropic
  Gamma-Ray Background

abstract:
  In this work we study the constraints on dark matter (DM) annihilation/decay
from the Fermi-LAT Isotropic Gamma-Ray Background (IGRB) observation. We
consider the contributions from both extragalactic and galactic DM components.
For DM annihilation, the evolutions of extragalactic DM halos are taken into
account. We find that the IGRB constraints under some DM subhalo models can be
comparable to those derived from the observations of dwarf spheroidal galaxies.
We also use the IGRB results to constrain the parameter regions accounting for
the latest AMS-02 electron-positron anomaly. We find that the majority of DM
annihilation/decay channels are strongly disfavored by the latest Fermi-LAT
IGRB observation; only DM annihilation/decay to $\mu^+\mu^-$ may be valid.


title: Exploring limits to prediction in complex social systems

abstract:
  How predictable is success in complex social systems? In spite of a recent
profusion of prediction studies that exploit online social and information
network data, this question remains unanswered, in part because it has not been
adequately specified. In this paper we attempt to clarify the question by
presenting a simple stylized model of success that attributes prediction error
to one of two generic sources: insufficiency of available data and/or models on
the one hand; and inherent unpredictability of complex social systems on the
other. We then use this model to motivate an illustrative empirical study of
information cascade size prediction on Twitter. Despite an unprecedented volume
of information about users, content, and past performance, our best performing
models can explain less than half of the variance in cascade sizes. In turn,
this result suggests that even with unlimited data predictive performance would
be bounded well below deterministic accuracy. Finally, we explore this
potential bound theoretically using simulations of a diffusion process on a
random scale free network similar to Twitter. We show that although higher
predictive power is possible in theory, such performance requires a homogeneous
system and perfect ex-ante knowledge of it: even a small degree of uncertainty
in estimating product quality or slight variation in quality across products
leads to substantially more restrictive bounds on predictability. We conclude
that realistic bounds on predictive accuracy are not dissimilar from those we
have obtained empirically, and that such bounds for other complex social
systems for which data is more difficult to obtain are likely even lower.


title: Pseudospin induced chirality with Staggered Optical Graphene

abstract:
  Pseudospin plays a very important role in understanding various interesting
physical phenomena associated with 2D materials such as graphene. It has been
proposed that pseudospin is directly related to angular momentum, and it was
recently experimentally demonstrated that orbit angular momentum is an
intrinsic property of pseudospin in a photonic honeycomb lattice. However, in
photonics, the interaction between spin and pseudospin for light has never been
investigated. In this Letter, we propose that, in an optical analogue of
staggered graphene, i.e. a photonic honeycomb lattice waveguide with in-plane
inversion symmetry breaking, the pseudospin mode can strongly couple to the
spin of an optical beam incident along certain directions. The spin-pseudospin
coupling, caused by the spin-orbit conversion in the scattering process,
induces a strong optical chiral effect for the transmitted optical beam.
Spin-pseudospin coupling of light opens door to the design of
pseudospin-mediated spin or valley selective photonic devices.


title: Non-parametric reconstruction of cosmological matter perturbations

abstract:
  Perturbative quantities, such as the growth rate ($f$) and index ($\gamma$),
are powerful tools to distinguish different dark energy models or modified
gravity theories even if they produce the same cosmic expansion history. In
this work, without any assumption about the dynamics of the Universe, we apply
a non-parametric method to current measurements of the expansion rate $H(z)$
from cosmic chronometers and high-$z$ quasar data and reconstruct the growth
factor and rate of linearised density perturbations in the non-relativistic
matter component. Assuming realistic values for the matter density parameter
$\Omega_{m0}$, as provided by current CMB experiments, we also reconstruct the
evolution of the growth index $\gamma$ with redshift. We show that the
reconstruction of current $H(z)$ data constrains the growth index to
$\gamma=0.56 \pm 0.12$ (2$\sigma$) at $z = 0.09$, which is in full agreement
with the prediction of the $\Lambda$CDM model and some of its extensions.


title:
Network Clustering via Maximizing Modularity: Approximation Algorithms
  and Theoretical Limits

abstract:
  Many social networks and complex systems are found to be naturally divided
into clusters of densely connected nodes, known as community structure (CS).
Finding CS is one of fundamental yet challenging topics in network science. One
of the most popular classes of methods for this problem is to maximize Newman's
modularity. However, there is a little understood on how well we can
approximate the maximum modularity as well as the implications of finding
community structure with provable guarantees. In this paper, we settle
definitely the approximability of modularity clustering, proving that
approximating the problem within any (multiplicative) positive factor is
intractable, unless P = NP. Yet we propose the first additive approximation
algorithm for modularity clustering with a constant factor. Moreover, we
provide a rigorous proof that a CS with modularity arbitrary close to maximum
modularity QOPT might bear no similarity to the optimal CS of maximum
modularity. Thus even when CS with near-optimal modularity are found, other
verification methods are needed to confirm the significance of the structure.


title: An algebra of open continuous time dynamical systems and networks

abstract:
  Many systems of interest in science and engineering are made up of
interacting subsystems. These subsystems, in turn, could be made up of
collections of smaller interacting subsystems and so on. In a series of papers
David Spivak with collaborators formalized these kinds of structures (systems
of systems) as algebras over presentable colored operads.
  It is also very useful to consider maps between dynamical systems. This
amounts to viewing dynamical systems as objects in an appropriate category.
This is the point taken by DeVille and Lerman in the study of dynamics on
networks.
  The goal of this paper is to describe an algebraic structure that encompasses
both approaches to systems of systems. To this end we replace the monoidal
category of wiring diagrams by a monoidal double category whose objects are
surjective submersions. This allows us, on one hand, build new large open
systems out of collections of smaller open subsystems and on the other keep
track of maps between open systems. As a special case we recover the results of
DeVille and Lerman on fibrations of networks of manifolds.


title:
Faddeev-Jackiw Hamiltonian Reduction for Free and Gauged
  Rarita-Schwinger Theories

abstract:
  We study the Faddeev-Jackiw symplectic Hamiltonian reduction for
3+1-dimensional free and Abelian gauged Rarita-Schwinger theories that comprise
Grassmannian fermionic fields. We obtain the relevant fundamental brackets and
find that they are in convenient forms for quantization. The brackets are
independent of whether the theories contain mass or gauge fields, and the
structure of constraints and symplectic potentials largely determine
characteristic behaviors of the theories. We also note that, in contrast to the
free massive theory, the Dirac field equations for free massless
Rarita-Schwinger theory cannot be obtained in a covariant way.


title: Nakayama categories and groupoid quantization

abstract:
  We provide a precise description, albeit in the situation of standard
categories, of the quantization functor Sum proposed by D.S. Freed, M.J.
Hopkins, J. Lurie, and C. Teleman in a way enough abstract and flexible to
suggest that an extension of the construction to the general context of higher
categories should indeed be possible. Our method is in fact based primarily on
dualizability and adjunction data, and is well suited for the homotopical
setting. The construction also sheds light on the need of certain rescaling
automorphisms, and in particular on the nature and properties of the Nakayama
isomorphism.


title: On non-separable families of positive homothetic convex bodies

abstract:
  A finite family ${\mathcal B}$ of balls with respect to an arbitrary norm in
${\mathbb R}^d$ ($d\geq 2$) is called a non-separable family if there is no
hyperplane disjoint from $\bigcup {\mathcal B}$ that strictly separates some
elements of ${\mathcal B}$ from all the other elements of ${\mathcal B}$ in
${\mathbb R}^d$. In this paper we prove that if ${\mathcal B}$ is a
non-separable family of balls of radii $r_1, r_2,\ldots , r_n$ ($n\geq 2$) with
respect to an arbitrary norm in ${\mathbb R}^d$ ($d\geq 2$), then $\bigcup
{\mathcal B}$ can be covered by a ball of radius $\sum_{i=1}^n r_i$. This was
conjectured by Erdos for the Euclidean norm and was proved for that case by A.
W. Goodman and R. E. Goodman [Amer. Math. Monthly 52 (1945), 494-498]. On the
other hand, in the same paper A. W. Goodman and R. E. Goodman conjectured that
their theorem extends to arbitrary non-separable finite families of positive
homothetic convex bodies in ${\mathbb R}^d$, $d\ge2$. Besides giving a
counterexample to their conjecture, we prove that conjecture under various
additional conditions.


title: Universality of charge transport in weakly interacting fermionic systems

abstract:
  We review two rigorous results on the transport properties of weakly
interacting fermionic systems on $2d$ lattices, in the linear response regime.
First, we discuss the universality of the longitudinal conductivity for
interacting graphene. Then, we focus on the transverse conductivity of general
weakly interacting gapped fermionic systems, and we establish its universality.
This last result proves the stability of the integer quantum Hall effect
against weak interactions. The proofs are based on combinations of fermionic
cluster expansion techniques, renormalization group and lattice Ward
identities.


title: Cosets of Meromorphic CFTs and Modular Differential Equations

abstract:
  Some relations between families of two-character CFTs are explained using a
slightly generalised coset construction, and the underlying theories (whose
existence was only conjectured based on the modular differential equation) are
constructed. The same method also gives rise to interesting new examples of
CFTs with three and four characters.


title:
On the asymptotic behavior of the maximum absolute value of generalized
  Gegenbauer polynomials

abstract:
  Using well-known facts on Jacobi polynomials, we derive some asymptotic
estimates for the maximum absolute value of generalized Gegenbauer polynomials.


title: On Deep Multi-View Representation Learning: Objectives and Optimization

abstract:
  We consider learning representations (features) in the setting in which we
have access to multiple unlabeled views of the data for learning while only one
view is available for downstream tasks. Previous work on this problem has
proposed several techniques based on deep neural networks, typically involving
either autoencoder-like networks with a reconstruction objective or paired
feedforward networks with a batch-style correlation-based objective. We analyze
several techniques based on prior work, as well as new variants, and compare
them empirically on image, speech, and text tasks. We find an advantage for
correlation-based representation learning, while the best results on most tasks
are obtained with our new variant, deep canonically correlated autoencoders
(DCCAE). We also explore a stochastic optimization procedure for minibatch
correlation-based objectives and discuss the time/performance trade-offs for
kernel-based and neural network-based implementations.


title:
Stellar Open Clusters' Membership Probabilities: an N-Dimensional
  Geometrical Approach

abstract:
  We present a new geometrical method aimed at determining the members of open
clusters. The methodology estimates, in an N-dimensional space, the membership
probabilities by means of the distances between every star and the cluster
central overdensity. It can handle different sets of variables, which have to
satisfy the simple condition of being more densely distributed for the cluster
members than for the field stars (as positions, proper motions, radial
velocities and/or parallaxes are). Unlike other existing techniques, this fact
makes the method more flexible and so can be easily applied to different
datasets. To quantify how the method identifies the clus- ter members, we
design series of realistic simulations recreating sky regions in both position
and proper motion subspaces populated by clusters and field stars. The re-
sults, using different simulated datasets (N = 1, 2 and 4 variables), show that
the method properly recovers a very high fraction of simulated cluster members,
with a low number of misclassified stars. To compare the goodness of our
methodology, we also run other existing algorithms on the same simulated data.
The results show that our method has a similar or even better performance than
the other techniques. We study the robustness of the new methodology from
different subsamplings of the ini- tial sample, showing a progressive
deterioration of the capability of our method as the fraction of missing
objects increases. Finally, we apply all the methodologies to the real cluster
NGC 2682, indicating that our methodology is again in good agreement with
preceding studies.


title:
Resolution of the piecewise smooth visible-invisible two-fold
  singularity in $\mathbb{R}^3$ using regularization and blowup

abstract:
  Two-fold singularities in a piecewise smooth (PWS) dynamical system in
$\mathbb{R}^3$ have long been the subject of intensive investigation. The
interest stems from the fact that trajectories which enter the two-fold are
associated with forward non-uniqueness. The key questions are: How do we
continue orbits forward in time? Are there orbits that are distinguished among
all the candidates?
  We address these questions by regularizing the PWS dynamical system for the
case of the visible-invisible two-fold. Within this framework, we consider a
regularization function outside the class of Sotomayor and Teixera. We then
undertake a rigorous investigation, using geometric singular perturbation
theory and blowup. We show that there is indeed a forward orbit $U$ that is
distinguished amongst all the possible forward orbits leaving the two-fold.
Working with a normal form of the visible-invisible two-fold, we show that
attracting limit cycles can be obtained (due to the contraction towards $U$),
upon composition with a global return mechanism. We provide some illustrative
examples.


title:
Hadronic contributions to electroweak observables in the framework of
  DPT

abstract:
  The hadronic contributions to the muon anomalous magnetic moment and to the
shift of the electromagnetic fine structure constant at the scale of Z boson
mass are evaluated within dispersively improved perturbation theory (DPT). The
latter merges the corresponding perturbative input with intrinsically
nonperturbative constraints, which originate in the respective kinematic
restrictions. The obtained results conform with recent assessments of the
quantities on hand.


title:
A Provably Correct MPC Approach to Safety Control of Urban Traffic
  Networks

abstract:
  Model predictive control (MPC) is a popular strategy for urban traffic
management that is able to incorporate physical and user defined constraints.
However, the current MPC methods rely on finite horizon predictions that are
unable to guarantee desirable behaviors over long periods of time. In this
paper we design an MPC strategy that is guaranteed to keep the evolution of a
network in a desirable yet arbitrary -safe- set, while optimizing a finite
horizon cost function. Our approach relies on finding a robust controlled
invariant set inside the safe set that provides an appropriate terminal
constraint for the MPC optimization problem. An illustrative example is
included.


title:
Geometric properties of infinite graphs and the Hardy-Littlewood maximal
  operator

abstract:
  We study different geometric properties on infinite graphs, related to the
weak-type boundedness of the Hardy-Littlewood maximal averaging operator. In
particular, we analyze the connections between the doubling condition, having
finite dilation and overlapping indices, uniformly bounded degree, the
equidistant comparison property and the weak-type boundedness of the centered
Hardy-Littlewood maximal operator. Several non-trivial examples of infinite
graphs are given to illustrate the differences among these properties.


title:
Extracting constraints from direct detection searches of supersymmetric
  dark matter in the light of null results from the LHC in the squark sector

abstract:
  The comparison of the results of direct detection of Dark Matter, obtained
with various target nuclei, requires model-dependent, or even arbitrary,
assumptions. Indeed, to draw conclusions either the spin-dependent (SD) or the
spin-independent (SI) interaction has to be neglected. In the light of the null
results from supersymmetry searches at the LHC, the squark sector is pushed to
high masses. We show that for a squark sector at the TeV scale, the framework
used to extract contraints from direct detection searches can be redefined as
the number of free parameters is reduced. Moreover, the correlation observed
between SI and SD proton cross sections constitutes a key issue for the
development of the next generation of Dark Matter detectors.


title: Relativistic tidal effects in non standard Kerr space-time

abstract:
  Astrophysical phenomena involving massive black holes (BHs) in close binaries
are expected to leave detectable signatures in the electromagnetic and
gravitational-wave spectrum. Such imprints may provide precious information to
probe the space-time around rotating BHs and to reveal new insights on the
nature of gravity in the strong-field regime. To support this observational
window, it is crucial to develop suitable tests to verify the predictions of
General Relativity. In this framework, the metric recently proposed by
Johannsen and Psaltis parametrizes strong-field deviations from a Kerr
space-time in a theory-independent way. In the following, we make use of this
approach to describe the tidal field produced by spinning BHs. We compute the
gravito-magnetic and gravito-electric tidal tensors for particles moving on
equatorial circular geodesics, comparing our results with those obtained in the
standard General Relativity scenario. Our calculations show significant
differences even for distances far form the last stable orbit, which may affect
the evolution of the binary and leave detectable signatures. We test our
framework computing quasiequilibrium sequences of BH-white dwarf systems by
means of the affine model, for different binary configurations.


title:
Exciton induced directed motion of unconstrained atoms in an ultracold
  gas

abstract:
  We demonstrate that through localised Rydberg excitation in a
three-dimensional cold atom cloud atomic motion can be rendered directed and
nearly confined to a plane, without spatial constraints for the motion of
individual atoms. This enables creation and observation of non-adiabatic
electronic Rydberg dynamics in atoms accelerated by dipole-dipole interactions
under natural conditions. Using the full $l=0,1$ $m=0,\pm1$ angular momentum
state space, our simulations show that conical intersection crossings are
clearly evident, both in atomic position information and excited state spectra
of the Rydberg system. Hence, flexible Rydberg aggregates suggest themselves
for probing quantum chemical effects in experiments on length scales much
inflated as compared to a standard molecular situation.


title: Spectral radius and Hamiltonicity of graphs with large minimum degree

abstract:
  This paper presents sufficient conditions for Hamiltonian paths and cycles in
graphs. Letting $\lambda\left( G\right) $ denote the spectral radius of the
adjacency matrix of a graph $G,$ the main results of the paper are:
  (1) Let $k\geq1,$ $n\geq k^{3}/2+k+4,$ and let $G$ be a graph of order $n$,
with minimum degree $\delta\left( G\right) \geq k.$ If \[ \lambda\left(
G\right) \geq n-k-1, \] then $G$ has a Hamiltonian cycle, unless
$G=K_{1}\vee(K_{n-k-1}+K_{k})$ or $G=K_{k}\vee(K_{n-2k}+\overline{K}_{k})$.
  (2) Let $k\geq1,$ $n\geq k^{3}/2+k^{2}/2+k+5,$ and let $G$ be a graph of
order $n$, with minimum degree $\delta\left( G\right) \geq k.$ If \[
\lambda\left( G\right) \geq n-k-2, \] then $G$ has a Hamiltonian path, unless
$G=K_{k}\vee(K_{n-2k-1}+\overline {K}_{k+1})$ or $G=K_{n-k-1}+K_{k+1}$
  In addition, it is shown that in the above statements, the bounds on $n$ are
tight within an additive term not exceeding $2$.


title:
Classical St\"uckelberg interferometry of a nanomechanical two-mode
  system at room temperature

abstract:
  The transition from classical to quantum mechanics has intrigued scientists
in the past and remains one of the most fundamental conceptual challenges in
state-of-the-art physics. Beyond the quantum mechanical correspondence
principle, quantum-classical analogies have attracted considerable interest. In
this work, we present classical two-mode interference for a nanomechanical
two-mode system, realizing classical St\"uckelberg interferometry. In the past,
St\"uckelberg interferometry has been investigated exclusively in quantum
mechanical two-level systems. Here, we experimentally demonstrate a classical
analog of St\"uckelberg interferometry taking advantage of coherent energy
exchange between two-strongly coupled, high quality factor nanomechanical
resonator modes. Furthermore, we provide an exact theoretical solution for the
double passage St\"uckelberg problem which reveals the analogy of the return
probabilities in the quantum mechanical and the classical version of the
problem. This result qualifies classical two-mode systems at large as a testbed
for quantum mechanical interferometry.


title: Sticky Cantor Sets in ${\mathbb R}^d$

abstract:
  A subset of ${\mathbb R}^d$ is called "sticky" if it cannot be isotoped off
of itself by a small ambient isotopy. Sticky wild Cantor sets are constructed
in ${\mathbb R}^d$ for each $d\geq 4$.


title: A note on cusp forms as $p$-adic limits

abstract:
  Several authors have recently proved results which express cusp forms as
$p$-adic limits of weakly holomorphic modular forms under repeated application
of Atkin's $U$-operator. The proofs involve techniques from the theory of weak
harmonic Maass forms, and in particular a result of Guerzhoy, Kent, and Ono on
the $p$-adic coupling of mock modular forms and their shadows. Here we obtain
strengthened versions of these results using techniques from the theory of
holomorphic modular forms.


title:
Optical resonance shifts in the fluorescence of thermal and cold atomic
  gases

abstract:
  We show that the resonance shifts in the fluorescence of a cold gas of
rubidium atoms substantially differ from those of thermal atomic ensembles that
obey the standard continuous medium electrodynamics. The analysis is based on
large-scale microscopic numerical simulations and experimental measurements of
the resonance shifts in a steady-state response in light propagation.

categories: physics.atom-ph cond-mat.quant-gas physics.optics quant-ph


title:
Interactive Multiple Model Estimation of Doubly-Selective Channels for
  OFDM systems

abstract:
  In this paper, we propose an algorithm for channel estimation, acquisition
and tracking, for orthogonal frequency division multiplexing (OFDM) systems.
The proposed algorithm is suitable for vehicular communications that encounter
very high mobility. A preamble sequence is used to derive an initial estimate
of the channel using least squares (LS). The temporal variation of the channel
within one OFDM symbol is approximated by two complex exponential basis
expansion models (CE-BEM). One of the Fourier-based BEMs is intended to capture
the low frequencies in the channel (slow variations corresponding to low
Doppler), while the other is destined to capture high frequencies (fast
variations corresponding to high Doppler). Kalman filtering is employed to
track the BEM coefficients iteratively on an OFDM symbol-by-symbol basis. An
interactive multiple model (IMM) estimator is implemented to dynamically mix
the estimates obtained by the two Kalman filters, each of which matched to one
of the BEMs. Extensive numerical simulations are conducted to signify the gain
obtained by the proposed combining technique.


title: Negative Coulomb Drag in Double Bilayer Graphene

abstract:
  Coulomb drag between parallel quantum wells provides a uniquely sensitive
measurement of electron correlations since the drag response depends on
interactions only. Recently it has been demonstrated that a new regime of
strong interactions can be accessed for devices consisting of two monlolayer
graphene (MLG) crystals, separated by few layer hexagonal boron-nitride. Here
we report measurement of Coulomb drag in a double bilayer graphene (BLG)
stucture, where the interaction potential is anticipated to be yet further
enhanced compared to MLG. At low temperatures and intermediate densities a new
drag response with inverse sign is observed, distinct from the momentum and
energy drag mechanisms previously reported in double MLG. We demonstrate that
by varying the device aspect ratio the negative drag component can be
suppressed and a response showing excellent agreement with the density and
temperature dependance predicted for momentum drag in double BLG is found. Our
results pave the way for pursuit of emergent phases in strongly interacting
bilayers, such as the exciton condensate.


title:
Scalable Ontological Query Processing over Semantically Integrated Life
  Science Datasets using MapReduce

abstract:
  To address the requirement of enabling a comprehensive perspective of
life-sciences data, Semantic Web technologies have been adopted for
standardized representations of data and linkages between data. This has
resulted in data warehouses such as UniProt, Bio2RDF, and Chem2Bio2RDF, that
integrate different kinds of biological and chemical data using ontologies.
Unfortunately, the ability to process queries over ontologically-integrated
collections remains a challenge, particularly when data is large. The reason is
that besides the traditional challenges of processing graph-structured data,
complete query answering requires inferencing to explicate implicitly
represented facts. Since traditional inferencing techniques like forward
chaining are difficult to scale up, and need to be repeated each time data is
updated, recent focus has been on inferencing that can be supported using
database technologies via query rewriting. However, due to the richness of most
biomedical ontologies relative to other domain ontologies, the queries
resulting from the query rewriting technique are often more complex than
existing query optimization techniques can cope with. This is particularly so
when using the emerging class of cloud data processing platforms for big data
processing due to some additional overhead which they introduce. In this paper,
we present an approach for dealing such complex queries on big data using
MapReduce, along with an evaluation on existing real-world datasets and
benchmark queries.


title: Gravitation Field Dynamics in Jeans Theory

abstract:
  Closed system of time equations for nonrelativistic gravitation field and
hydrodynamic medium was obtained by taking into account binary correlations of
the field, which is the generalization of Jeans theory. Distribution function
of the systemwas built on the basis of the Bogolyubov reduced description
method. Calculations were carried out up to the first order of a perturbation
theory in interaction. Adiabatic and enthropic types of perturbations were
corrected and two new types of perturbations were found.


title:
Improved Achievability and Converse Bounds for Erd\H{o}s-R\'enyi Graph
  Matching

abstract:
  We consider the problem of perfectly recovering the vertex correspondence
between two correlated Erd\H{o}s-R\'enyi (ER) graphs. For a pair of correlated
graphs on the same vertex set, the correspondence between the vertices can be
obscured by randomly permuting the vertex labels of one of the graphs. In some
cases, the structural information in the graphs allow this correspondence to be
recovered. We investigate the information-theoretic threshold for exact
recovery, i.e. the conditions under which the entire vertex correspondence can
be correctly recovered given unbounded computational resources.
  Pedarsani and Grossglauser provided an achievability result of this type.
Their result establishes the scaling dependence of the threshold on the number
of vertices. We improve on their achievability bound. We also provide a
converse bound, establishing conditions under which exact recovery is
impossible. Together, these establish the scaling dependence of the threshold
on the level of correlation between the two graphs. The converse and
achievability bounds differ by a factor of two for sparse, significantly
correlated graphs.


title: Focusing of world-lines in Weyl gravity

abstract:
  We study the evolution of time-like congruences in the vacuum solutions of
Weyl conformal theory of gravity. Using the Raycaudhuri equation, we show that
for positive values of the coeffcient of the linear term in the solution and in
the absence of the cosmological constant, the incoming rays converge. The
evolution of the congruence for negative values is investigated for different
values of the parameters. The behavior of the congruence under conformal
transformations is also studied.


title:
Stable core symmetries and confined textures for a vortex line in a
  spinor Bose-Einstein condensate

abstract:
  We show how a singly quantized vortex can exhibit energetically stable defect
cores with different symmetries in an atomic spin-1 polar Bose-Einstein
condensate, and how a stable topologically nontrivial Skyrmion texture of lower
dimensionality can be confined inside the core. The core isotropy and the
stability of the confined texture are sensitive to Zeeman level shifts. The
observed structures have analogies, respectively, in pressure-dependent
symmetries of superfluid liquid He-3 vortices and in the models of
superconducting cosmic strings.


title: Quantum Multiplicative Hypertoric Varieties and Localization

abstract:
  We consider q-deformations of multiplicative hypertoric varieties, for q a
non-zero element of an algebraically closed field of characteristic 0. We
construct an algebra Dq of q-difference operators as a Heisenberg double in a
braided monoidal category. We then focus on the case where q is specialized to
a root of unity. In this setting, we use Dq to construct an Azumaya algebra on
an l-twist of the multiplicative hypertoric variety, before showing that this
algebra splits over the fibers of both the moment and resolution maps. Finally,
we sketch a derived localization theorem for these Azumaya algebras.


title: On Riemannian Foliations over Positively Curved Manifolds

abstract:
  We prove that, under reasonable conditions, odd co-dimension Riemannian
foliations cannot occur in positively curved manifolds.


title: Theoretical Developments in QCD Jet Energy Loss

abstract:
  We review the recent developments in the theory of jet-quenching. First, we
analyze the coherent vacuum cascade and incoherent medium-induced cascade
separately. We then discuss the interplay between the two kinds of cascade and
the resulting partial decoherence of the inner jet structure. Finally, we
report on recent calculations of higher-order corrections. In particular, the
dominant radiative corrections to jet observables that yield the
renormalization of the jet-quenching parameter are addressed.


title:
Probing QED and fundamental constants through laser spectroscopy of
  vibrational transitions in HD+

abstract:
  The simplest molecules in nature, molecular hydrogen ions in the form of H2+
and HD+, provide an important benchmark system for tests of quantum
electrodynamics in complex forms of matter. Here, we report on such a test
based on a frequency measurement of a vibrational overtone transition in HD+ by
laser spectroscopy. We find that the theoretical and experimental frequencies
are equal to within 0.6(1.1) parts per billion, which represents the most
stringent test of molecular theory so far. Our measurement not only confirms
the validity of high-order quantum electrodynamics in molecules, but also
enables the long predicted determination of the proton-to-electron mass ratio
from a molecular system, as well as improved constraints on hypothetical fifth
forces and compactified higher dimensions at the molecular scale. With the
perspective of comparisons between theory and experiment at the 0.01
part-per-billion level, our work demonstrates the potential of molecular
hydrogen ions as a probe of fundamental physical constants and laws.

categories: physics.atom-ph physics.chem-ph physics.plasm-ph quant-ph


title:
Numerical precession in variational discretizations of the Kepler
  problem

abstract:
  Kepler's first law states that the orbit of a point mass with negative energy
in a classical gravitational potential is an ellipse with one of its foci at
the gravitational center. In numerical simulations of this system one often
observes a slight precession of the ellipse around the gravitational center.
Using the Lagrangian structure of modified equations and a perturbative version
of Noether's theorem, we provide leading order estimates of this precession for
the implicit MidPoint rule (MP) and the St\"ormer-Verlet method (SV). Based on
those estimates we construct some new numerical integrators that perform
significantly better than MP and SV on the Kepler problem.


title: Herschel Footprint Database and Service

abstract:
  We created the Herschel Footprint Database and web services for the Herschel
Space Observatory imaging data. For this database we set up a unified data
model for the PACS and SPIRE Herschel instruments, from the pointing and header
information of each observation, generated and stored sky coverages
(footprints) of the observations in their exact geometric form. With this tool
we extend the capabilities of the Herschel Science Archive by providing an
effective search tool that is able to find observations for selected sky
locations (objects), or even in larger areas in the sky.


title:
Control Function Instrumental Variable Estimation of Nonlinear Causal
  Effect Models

abstract:
  The instrumental variable method consistently estimates the effect of a
treatment when there is unmeasured confounding and a valid instrumental
variable. A valid instrumental variable is a variable that is independent of
unmeasured confounders and affects the treatment but does not have a direct
effect on the outcome beyond its effect on the treatment. Two commonly used
estimators for using an instrumental variable to estimate a treatment effect
are the two stage least squares estimator and the control function estimator.
For linear causal effect models, these two estimators are equivalent, but for
nonlinear causal effect models, the estimators are different. We provide a
systematic comparison of these two estimators for nonlinear causal effect
models and develop an approach to combing the two estimators that generally
performs better than either one alone. We show that the control function
estimator is a two stage least squares estimator with an augmented set of
instrumental variables. If these augmented instrumental variables are valid,
then the control function estimator can be much more efficient than usual two
stage least squares without the augmented instrumental variables while if the
augmented instrumental variables are not valid, then the control function
estimator may be inconsistent while the usual two stage least squares remains
consistent. We apply the Hausman test to test whether the augmented
instrumental variables are valid and construct a pretest estimator based on
this test. The pretest estimator is shown to work well in a simulation study.
An application to the effect of exposure to violence on time preference is
considered.


title:
Better safe than sorry: Risky function exploitation through safe
  optimization

abstract:
  Exploration-exploitation of functions, that is learning and optimizing a
mapping between inputs and expected outputs, is ubiquitous to many real world
situations. These situations sometimes require us to avoid certain outcomes at
all cost, for example because they are poisonous, harmful, or otherwise
dangerous. We test participants' behavior in scenarios in which they have to
find the optimum of a function while at the same time avoid outputs below a
certain threshold. In two experiments, we find that Safe-Optimization, a
Gaussian Process-based exploration-exploitation algorithm, describes
participants' behavior well and that participants seem to care firstly whether
a point is safe and then try to pick the optimal point from all such safe
points. This means that their trade-off between exploration and exploitation
can be seen as an intelligent, approximate, and homeostasis-driven strategy.


title: On $\mathbf {Cat}$-valued sheaves

abstract:
  Let ${\widetilde {\mathcal O}}(\mathbf B)$ be the category of (open)
subcategories of a topological groupoid ${\mathbf B}.$ This paper concerns with
the ${\mathbf {Cat}}$-valued sheaves over category ${\widetilde {\mathcal
O}}(\mathbf B).$ Since ${\mathbf {Cat}}$ is not a concrete category,
traditional definition of presheaf can not deal with the situation. [13]
proposes a new framework for the purpose. Starting from the definition given in
[13], we build-up the frame work for ${\mathbf {Cat}}$-valued sheaves. For that
purpose we introduce a notion of categorical union, such that categorical union
of subcategories is a subcategory, which is required for a meaningful
definition of a categorical cover of a topological category. The main result is
the following. For a fixed category $\mathbf C,$ the categories of local
functorial sections from $\mathbf B$ to $\mathbf C$ define a ${\mathbf
{Cat}}$-valued sheaf on ${\widetilde {\mathcal O}}(\mathbf B).$ Replacing
$\mathbf C$ with a categorical group $\mathcal G,$ we find a ${\mathbf
{CatGrp}}$-valued sheaf on ${\widetilde {\mathcal O}}(\mathbf B).$


title:
A recollection of Souriau's derivation of the Weyl equation via
  geometric quantization

abstract:
  These notes merely intend to memorialize Souriau's overlooked achievements
regarding geo\-metric quantization of Poincar\'e-elementary symplectic systems.
Restricting attention to his model of massless, spin-$\half$, particles, we
faithfully rephrase and expound here Sections (18.82)--(18.96) &
(19.122)--(19.134) of his book \cite{SSD} edited in 1969. Missing details about
the use of a preferred Poincar\'e-invariant polarizer are provided for
completeness.


title: A Pohozaev Identity on Warped Product Solitons

abstract:
  Warped product metrics are a class of Riemannian metrics on cross products $B
\times F$ which have been well studied and provide a rich set of examples. In
this paper we consider shrinking gradient Ricci solitons which are warped
product metrics. We prove that if the curvature of the metric is bounded and
the base $B$ has two dimensions, the metric must in fact be a cross product.
The theorem is a consequence of a Pohozaev-type identity. This closely
parallels results in the study of blow-ups of solutions to the reaction-
diffusion equation $\partial_t v = \Delta v + e^v$ in $\mathbb{R}^2$ .


title:
Optical magnetic detection of single-neuron action potentials using
  quantum defects in diamond

abstract:
  A key challenge for neuroscience is noninvasive, label-free sensing of action
potential (AP) dynamics in whole organisms with single-neuron resolution. Here,
we present a new approach to this problem: using nitrogen-vacancy (NV) quantum
defects in diamond to measure the time-dependent magnetic fields produced by
single-neuron APs. Our technique has a unique combination of features: (i) it
is noninvasive, as the light that probes the NV sensors stays within the
biocompatible diamond chip and does not enter the organism, enabling activity
monitoring over extended periods; (ii) it is label-free and should be widely
applicable to most organisms; (iii) it provides high spatial and temporal
resolution, allowing precise measurement of the AP waveforms and conduction
velocities of individual neurons; (iv) it directly determines AP propagation
direction through the inherent sensitivity of NVs to the associated AP magnetic
field vector; (v) it is applicable to neurons located within optically opaque
tissue or whole organisms, through which magnetic fields pass largely
unperturbed; and (vi) it is easy-to-use, scalable, and can be integrated with
existing techniques such as wide-field and superresolution imaging. We
demonstrate our method using excised single neurons from two invertebrate
species, marine worm and squid; and then by single-neuron AP magnetic sensing
exterior to whole, live, opaque marine worms for extended periods with no
adverse effect. The results lay the groundwork for real-time, noninvasive 3D
magnetic mapping of functional neuronal networks, ultimately with synapse-scale
(~10 nm) resolution and circuit-scale (~1 cm) field-of-view.

categories: quant-ph cond-mat.mes-hall physics.atom-ph q-bio.NC