title:
Inter-Edge Backscattering in Buried Split-Gate-Defined Graphene Quantum
  Point Contacts

abstract:
  Quantum Hall effects offer a formidable playground for the investigation of
quantum transport phenomena. Edge modes can be detected, branched, and mixed by
designing a suitable potential landscape in a two-dimensional conducting system
subject to a strong magnetic field. In the present work, we demonstrate a
buried split-gate architecture and use it to control electron conduction in
large-scale single-crystal monolayer graphene grown by chemical vapor
deposition. The control of the edge trajectories is demonstrated by the
observation of various fractional quantum resistances, as a result of a
controllable inter-edge scattering. Experimental data are successfully modeled
both numerically and within the Landauer-Buettiker formalism. Our architecture
is particularly promising and unique in view of the investigation of quantum
transport via scanning probe microscopy, since graphene constitutes the topmost
layer of the device. For this reason, it can be approached and perturbed by a
scanning probe down to the limit of mechanical contact.


title:
Hopf-Hecke algebras, infinitesimal Cherednik algebras, and Dirac
  cohomology

abstract:
  Hopf-Hecke algebras and Barbasch-Sahi algebras were defined by the first
named author (2016) in order to provide a general framework for the study of
Dirac cohomology. The aim of this paper is to explore new examples of these
definitions and to contribute to their classification. Hopf-Hecke algebras are
distinguished by an orthogonality condition and a PBW property. The PBW
property for algebras such as the ones considered here has been of great
interest in the literature and we extend this discussion by further results on
the classification of such deformations and by a class of hitherto unexplored
examples. We study infinitesimal Cherednik algebras of $GL_n$ as defined by
Etingof, Gan, and Ginzburg in [Transform. Groups, 2005] as new examples of
Hopf-Hecke algebras with a generalized Dirac cohomology. We show that they are
in fact Barbasch-Sahi algebras, that is, a version of Vogan's conjecture
analogous to the results of Huang and Pand\v{z}i\'{c} in [J. Amer. Math. Soc.,
2002] is available for them. We derive an explicit formula for the square of
the Dirac operator and use it to study the finite-dimensional irreducible
modules. We find that the Dirac cohomology of these modules is non-zero and
that it, in fact, determines the modules uniquely.


title: A Note on the Practicality of Maximal Planar Subgraph Algorithms

abstract:
  Given a graph $G$, the NP-hard Maximum Planar Subgraph problem (MPS) asks for
a planar subgraph of $G$ with the maximum number of edges. There are several
heuristic, approximative, and exact algorithms to tackle the problem, but---to
the best of our knowledge---they have never been compared competitively in
practice. We report on an exploratory study on the relative merits of the
diverse approaches, focusing on practical runtime, solution quality, and
implementation complexity. Surprisingly, a seemingly only theoretically strong
approximation forms the building block of the strongest choice.


title: General Construction of Tubular Geometry

abstract:
  We consider the problem of locally describing tubular geometry around a
submanifold embedded in a (pseudo)Riemannian manifold in its general form.
Given the geometry of ambient space in an arbitrary coordinate system and
equations determining the submanifold in the same system, we compute the
tubular expansion coefficients in terms of this {\it a priori data}. This is
done by using an indirect method that crucially applies the tubular expansion
theorem for vielbein previously derived. With an explicit construction
involving the relevant coordinate and non-coordinate frames we verify
consistency of the whole method up to quadratic order in vielbein expansion.
Furthermore, we perform certain (long and tedious) higher order computation
which verifies the first non-trivial spin connection term in the expansion for
the first time. Earlier a similar method was used to compute tubular geometry
in loop space. We explain this work in the light of our general construction.


title: Stochastic Electrochemical Kinetics

abstract:
  A new tool for modeling electrochemical kinetics is presented. An extension
of the Stochastic Simulation Algorithm framework to electrochemical systems is
proposed. The physical justifications and constraints for the derivation of a
chemical master equation are provided and discussed. The electrochemical
driving forces are included in the mathematical framework, and equations are
provided for the associated electric responses. The implementation for
potentiostatic and galvanostatic systems is presented, with results pointing
out the stochastic nature of the algorithm. The electric responses presented
are in line with the expected results from the deterministic theory.


title: Highly Sensitive Gas Sensors Based on Silicene Nanoribbons

abstract:
  Inspired by the recent successes in the development of two-dimensional based
gas sensors capable of single gas molecule detection, we investigate the
adsorption of gas molecules such as N2, NO, NO2, NH3, CO, CO2, CH4, SO2, and
H2S on silicene nanoribbons using density functional theory and nonequilibrium
Green's function methods. The most stable adsorption configurations, adsorption
sites, adsorption energies, charge transfer, quantum conductance modulation,
and electronic band structures of all studied gas molecules on SiNRs are
studied. Our results indicate that NO, NO2, and SO2 are chemisorbed on SiNRs
via strong covalent bonds, suggesting its potential application for disposable
gas sensors. In addition, CO and NH3 are chemisorbed on SiNRs with moderate
adsorption energy, alluding to its suitability as a highly sensitive gas
sensor. The quantum conductance is detectably modulated by chemisorption of gas
molecules which can be attributed to the charge transfer from the gas molecule
to the SiNR. Other studied gases are physisorbed on SiNRs via van der Waals
interactions. It is also found that the adsorption energies are enhanced by
doping SiNRs with either B or N atom. Our results suggest that SiNRs show
promise in gas molecule sensing applications.


title: Barbasch-Sahi algebras and Dirac cohomology

abstract:
  We define a class of algebras which are distinguished by a PBW property and
an orthogonality condition, and which we call Hopf-Hecke algebras, since they
generalize the Drinfeld Hecke algebras defined by Drinfeld. In the course of
studying the orthogonality condition and in analogy to the orthogonal group we
show the existence of a pin cover for cocommutative Hopf algebras over
$\mathbb{C}$ with an orthogonal module or, more generally, pointed
cocommutative Hopf algebras over a field of characteristic $0$ with an
orthogonal module.
  Following the suggestion of Dan Barbasch and Siddhartha Sahi, we define a
Dirac operator and Dirac cohomology for modules of Hopf-Hecke algebras,
generalizing those concepts for connected semisimple Lie groups, graded affine
Hecke algebras and symplectic reflection algebras. Using the pin cover, we
prove a general theorem for a class of Hopf-Hecke algebras which we call
Barbasch-Sahi algebras, which relates the central character of an irreducible
module with non-vanishing Dirac cohomology to the central characters occurring
in its Dirac cohomology, generalizing a result called "Vogan's conjecture" for
connected semisimple Lie groups, analogous results for graded affine Hecke
algebras and for symplectic reflection algebras and Drinfeld Hecke algebras.


title:
Mass enhancement in multiple bands approaching optimal doping in a
  high-temperature superconductor

abstract:
  Pnictides provide an opportunity to study the effects of quantum criticality
in a multi-band high temperature superconductor. Quasiparticle mass divergence
near optimal doping, observed in two major classes of high-temperature
superconductors, pnictides and cuprates, is a direct experimental indicator of
enhanced electronic interactions that accompany quantum criticality. Whether
quasiparticles on all Fermi surface pockets in BaFe2(As1-xPx)2 are affected by
quantum criticality is an open question, which specific heat measurements at
high magnetic fields can directly address. Here we report specific heat
measurements up to 35T in BaFe2(As1-xPx)2 over a broad doping range, 0.44 <= x
<= 0.6. We observe saturation of C/T in the normal state at all dopings where
superconductivity is fully suppressed. Our measurements demonstrate that
quasiparticle mass increases towards optimal doping in multiple pockets, some
of which exhibit even stronger mass enhancement than previously reported from
quantum oscillations of a single pocket.


title:
Why ghosts don't touch: a tale of two adventurers falling one after
  another into a black hole

abstract:
  The case for the utility of Kruskal-Szekeres coordinates in classroom made by
Augousti et al. in this journal (Eur. J. Phys. 33:1--11, 2012) is strengthened
by extending their discussion beyond the event horizon of the black hole.
Observations made by two adventurers following one another into a Schwarzschild
black hole are examined in terms of these nonsingular coordinates. Two
scenarios are considered, the first corresponding to one observer following the
other closely, the second to a significant distance between the two of them,
precluding the existence of a common inertial system. In particular, the
concepts of distance and temporal separation near the horizon and the redshift
of the first infaller's image as seen by the second are investigated. The
results show that the notion of "touching ghosts" does not correspond to the
local physics of two observers falling into a black hole. The story line is
interesting enough and the mathematical details are sufficiently simple to use
the example in a general relativity course, even at the undergraduate level.


title:
Atmospheric constituents and surface-level UVB: implications for a
  paleoaltimetry proxy and attempts to reconstruct UV exposure during volcanic
  episodes

abstract:
  Chemical and morphological features of spores and pollens have been linked to
changes in solar ultraviolet radiation (specifically UVB, 280-315 nm) at
Earth's surface. Variation in UVB exposure as inferred from these features has
been suggested as a proxy for paleoaltitude. While UVB irradiance does increase
with altitude above sea level, a number of other factors affect the irradiance
at any given place and time. In this modeling study we use the TUV atmospheric
radiative transfer model to investigate dependence of surface-level UVB
irradiance and relative biological impact on a number of constituents in
Earth's atmosphere that are variable over long and short time periods. We
consider changes in O3 column density, and SO2 and sulfate aerosols due to
periods of volcanic activity, including that associated with the formation of
the Siberian Traps. We find that UVB irradiance may be highly variable under
volcanic conditions and variations in several of these atmospheric constituents
can easily mimic or overwhelm changes in UVB irradiance due to changes in
altitude. On the other hand, we find that relative change with altitude is not
very sensitive to different sets of atmospheric conditions. Any paleoaltitude
proxy based on UVB exposure requires confidence that the samples under
comparison were located at roughly the same latitude, under very similar O3 and
SO2 columns, with similar atmospheric aerosol conditions. In general, accurate
estimates of the surface-level UVB exposure at any time and location require
detailed radiative transfer modeling taking into account a number of
atmospheric factors; this result is important for paleoaltitude proxies as well
as attempts to reconstruct the UV environment through geologic time and to tie
extinctions, such as the end-Permian mass extinction, to UVB irradiance
changes.


title:
Non-collinear antiferromagnetism of coupled spins and pseudospins in the
  double perovskite La2CuIrO6

abstract:
  We report the structural, magnetic and thermodynamic properties of the double
perovskite compound La2CuIrO6 from X-ray, neutron diffraction, neutron
depolarization, dc magnetization, ac susceptibility, specific heat,
muon-spin-relaxation (uSR), electron-spin-resonance (ESR) and nuclear magnetic
resonance (NMR) measurements. Below ~113 K, short-range spin-spin correlations
occur within the Cu2+ sublattice. With decreasing temperature, the Ir4+
sublattice progressively involves in the correlation process. Below T = 74 K,
the magnetic sublattices of Cu (spin s = 1/2) and Ir (pseudospin j = 1/2) in
La2CuIrO6 are strongly coupled and exhibit an antiferromagnetic phase
transition into a non-collinear magnetic structure accompanied by a small
uncompensated transverse moment. A weak anomaly in ac-susceptibility as well as
in the NMR and {\mu}SR spin lattice relaxation rates at 54 K is interpreted as
a cooperative ordering of the transverse moments which is influenced by the
strong spin-orbit coupled 5d ion Ir4+. We argue that the rich magnetic
behaviour observed in La2CuIrO6 is related to complex magnetic interactions
between the strongly correlated spin-only 3d ions with the strongly spin-orbit
coupled 5d transition ions where a combination of the spin-orbit coupling and
the low-symmetry of the crystal lattice plays a special role for the spin
structure in the magnetically ordered state.


title: The logical strength of B\"uchi's decidability theorem

abstract:
  We study the strength of axioms needed to prove various results related to
automata on infinite words and B\"uchi's theorem on the decidability of the MSO
theory of $(N, {\le})$. We prove that the following are equivalent over the
weak second-order arithmetic theory $RCA_0$:
  (1) the induction scheme for $\Sigma^0_2$ formulae of arithmetic,
  (2) a variant of Ramsey's Theorem for pairs restricted to so-called additive
colourings,
  (3) B\"uchi's complementation theorem for nondeterministic automata on
infinite words,
  (4) the decidability of the depth-$n$ fragment of the MSO theory of $(N,
{\le})$, for each $n \ge 5$.
  Moreover, each of (1)-(4) implies McNaughton's determinisation theorem for
automata on infinite words, as well as the "bounded-width" version of K\"onig's
Lemma, often used in proofs of McNaughton's theorem.


title: Thermal Infrared Sky Background for a High-Arctic Mountain Observatory

abstract:
  Nighttime zenith sky spectral brightness in the 3.3 to 20 micron wavelength
region is reported for an observatory site nearby Eureka, on Ellesmere Island
in the Canadian High Arctic. Measurements derive from an automated
Fourier-transform spectrograph which operated continuously there over three
consecutive winters. During that time the median through the most transparent
portion of the Q window was 460 Jy/square-arcsec, falling below 32
Jy/square-arcsec in N band, and to sub-Jansky levels by M and shortwards;
reaching only 36 mJy/square-arcsec within L. Nearly six decades of twice-daily
balloonsonde launches from Eureka, together with contemporaneous meteorological
data plus a simple model allows characterization of background stability and
extrapolation into K band. This suggests the study location has dark skies
across the whole thermal infrared spectrum, typically sub-200
micro-Jy/square-arcsec at 2.4 microns. That background is comparable to South
Pole, and more than an order of magnitude less than estimates for the best
temperate astronomical sites, all at much higher elevation. Considerations
relevant to future facilities, including for polar transient surveys, are
discussed.


title:
Local characterizations for the matrix monotonicity and convexity of
  fixed order

abstract:
  We establish local characterizations of matrix monotonicity and convexity of
fixed order by giving integral representations connecting the Loewner and Kraus
matrices, previously known to characterize these properties, to respective
Hankel matrices. Our results are new already in the general case of matrix
convexity and our approach significantly simplifies the corresponding work on
matrix monotonicity. We also obtain an extension of the original
characterization for matrix convexity by Kraus, and tighten the relationship
between monotonicity and convexity.


title:
First-Principles Prediction of the Softening of the Silicon Shock
  Hugoniot Curve

abstract:
  Shock compression of silicon (Si) under extremely high pressures (>100 Mbar)
was investigated by using two first-principles methods of orbital-free
molecular dynamics (OFMD) and path integral Monte Carlo (PIMC). While pressures
from the two methods agree very well, PIMC predicts a second compression
maximum because of 1s electron ionization that is absent in OFMD calculations
since Thomas-Fermi-based theories lack shell structure. The Kohn-Sham density
functional theory is used to calculate the equation of state (EOS) of warm
dense silicon for low-pressure loadings (P < 100 Mbar). Combining these
first-principles EOS results, the principal shock Hugoniot curve of silicon for
pressures varying from 1 Mbar to above 10 Gbar was derived. We find that
silicon is 20% or more softer than what was predicted by widely-used EOS
models. Existing high-pressure experimental data (P = 1 - 2 Mbar) seem to
indicate this softening behavior of Si, which calls for future strong-shock
experiments (P > 10 Mbar) to benchmark our results.


title:
Minimizing Outage Probability by Exploiting CSI in Wireless Powered
  Cooperative Networks

abstract:
  In this work, we address the relay selection problem for the wireless powered
communication networks, where the relays harvest energy from the source radio
frequency signals. A single source-destination pair is considered without a
direct link. The connecting relay nodes are equipped with storage batteries of
infinite size. We assume that the channel state information (CSI) on the
source-relay link is available at the relay nodes. Depending on the
availability of the CSI on the relay-destination link at the relay node, we
propose different relay selection schemes and evaluate the outage probability.
The availability of the CSI at the relay node on the relay-destination link
considerably improves the performance due to additional flexibility in the
relay selection mechanism. We numerically quantify the performance for the
proposed schemes and compare the outage probability for fixed and equal number
of wireless powered forwarding relays.


title: Phase Diagram of the Two-Dimensional Complex Ginzburg-Landau Equation

abstract:
  After a brief introduction to the complex Ginzburg-Landau equation, some of
its important features in two space dimensions are reviewed. A comprehensive
study of the various phases observed numerically in large systems over the
whole parameter space is then presented. The nature of the transitions between
these phases is investigated and some theoretical problems linked to the phase
diagram are discussed.


title: Logarithmic coefficients of close-to-convex functions

abstract:
  For an analytic and univalent function $f$ in the unit disk
$\mathbb{D}:=\{z\in\mathbb{C}:|z|<1\}$ with the normalization $f(0)=0=f'(0)-1$,
the logarithmic coefficients $\gamma_n$ are defined by $\log \frac{f(z)}{z}=
2\sum_{n=1}^{\infty} \gamma_n z^n$. In the present paper, we consider the class
of close-to-convex functions (with argument $0$), and determine the sharp upper
bound of $|\gamma_3|$ for such functions $f$, which proves a recent conjecture
of the first and third authors [1].


title:
Unique continuation from infinity in asympotically Anti-de Sitter
  spacetimes II: Non-static boundaries

abstract:
  We generalize our unique continuation results recently established for a
class of linear and nonlinear wave equations $\Box_g \phi + \sigma \phi =
\mathcal{G} ( \phi, \partial \phi )$ on asymptotically anti-de Sitter (aAdS)
spacetimes to aAdS spacetimes admitting non-static boundary metrics. The new
Carleman estimates established in this setting constitute an essential
ingredient in proving unique continuation results for the full nonlinear
Einstein equations, which will be addressed in forthcoming papers. Key to the
proof is a new geometrically adapted construction of foliations of pseudoconvex
hypersurfaces near the conformal boundary.


title:
Long-term implications of observing an expanding cosmological
  civilization

abstract:
  Suppose that advanced civilizations, separated by a cosmological distance and
time, wish to maximize their access to cosmic resources by rapidly expanding
into the universe. How does the presence of one limit the expansionistic
ambitions of another, and what sort of boundary forms between their expanding
domains? We describe a general scenario for any expansion speed, separation
distance, and time. We then specialize to a question of particular interest:
What are the future prospects for a young and ambitious civilization if they
can observe the presence of another at a cosmological distance? We treat cases
involving the observation of one or two expanding domains. In the
single-observation case, we find that almost any plausible detection will limit
one's future cosmic expansion to some extent. Also, practical technological
limits to expansion speed (well below the speed of light) play an interesting
role. If a domain is visible at the time one embarks on cosmic expansion,
higher practical limits to expansion speed are beneficial only up to a certain
point. Beyond this point, a higher speed limit means that gains in the ability
to expand are more than offset by the first-mover advantage of the observed
domain. In the case of two visible domains, it is possible to be "trapped" by
them if the practical speed limit is high enough and their angular separation
in the sky is large enough, i.e. one's expansion in any direction will
terminate at a boundary with the two visible civilizations. Detection at an
extreme cosmological distance has surprisingly little mitigating effect on our
conclusions.


title: Homogenization of Stokes System using Bloch Waves

abstract:
  In this work, we study the Bloch wave homogenization for the Stokes system
with periodic viscosity coefficient. In particular, we obtain the spectral
interpretation of the homogenized tensor. The presence of the incompressibility
constraint in the model raises new issues linking the homogenized tensor and
the Bloch spectral data. The main difficulty is a lack of smoothness for the
bottom of the Bloch spectrum, a phenomenon which is not present in the case of
the elasticity system. This issue is solved in the present work, completing the
homogenization process of the Stokes system via the Bloch wave method.


title:
Recurring sets of recurring starspot occultations on exoplanet-host
  Qatar-2

abstract:
  We announce the detection of recurring sets of recurring starspot occultation
events in the short-cadence K2 lightcurve of Qatar-2, a K dwarf star transited
every 1.34 d by a hot Jupiter. In total we detect 34 individual starspot
occultation events, caused by five different starspots, occulted in up to five
consecutive transits or after a full stellar rotation. The longest recurring
set of recurring starspot occultations spans over three stellar rotations,
setting a lower limit for the longest starspot lifetime of 58 d. Starspot
analysis provided a robust stellar rotational period measurement of
$18.0\pm0.2$ d and indicates that the system is aligned, having a sky-projected
obliquity of $0\pm8^{\circ}$. A pronounced rotational modulation in the
lightcurve has a period of $18.2\pm1.6$ d, in agreement with the rotational
period derived from the starspot occultations. We tentatively detect an
ellipsoidal modulation in the phase-curve, with a semi-amplitude of 18 ppm, but
cannot exclude the possibility that this is the result of red noise or
imperfect removal of the rotational modulation. We detect no transit-timing and
transit-duration variations with upper limits of 15 s and 1 min, respectively.
We also reject any additional transiting planets with transit depths above 280
ppm in the orbital period region 0.5-30 d.


title: Precision analysis of the photomultiplier response to ultra low signals

abstract:
  A new computational model for the description of the photon detector response
functions measured in conditions of low light is presented, together with
examples of the observed photomultiplier signal amplitude distributions,
successfully described using the parameterized model equation. In extension to
the previously known approximations, the new model describes the underlying
discrete statistical behavior of the photoelectron cascade multiplication
processes in photon detectors with complex non-uniform gain structure of the
first dynode. Important features of the model include the ability to represent
the true single-photoelectron spectra from different photomultipliers with a
variety of parameterized shapes, reflecting the variability in the design and
in the individual parameters of the detectors. The new software tool is
available for evaluation of the detectors' performance, response, and
efficiency parameters that may be used in various applications including the
ultra low background experiments such as the searches for Dark Matter and rare
decays, underground neutrino studies, optimizing operations of the Cherenkov
light detectors, help in the detector selection procedures, and in the
experiment simulations.


title: Maximum Correntropy Unscented Filter

abstract:
  The unscented transformation (UT) is an efficient method to solve the state
estimation problem for a non-linear dynamic system, utilizing a derivative-free
higher-order approximation by approximating a Gaussian distribution rather than
approximating a non-linear function. Applying the UT to a Kalman filter type
estimator leads to the well-known unscented Kalman filter (UKF). Although the
UKF works very well in Gaussian noises, its performance may deteriorate
significantly when the noises are non-Gaussian, especially when the system is
disturbed by some heavy-tailed impulsive noises. To improve the robustness of
the UKF against impulsive noises, a new filter for nonlinear systems is
proposed in this work, namely the maximum correntropy unscented filter (MCUF).
In MCUF, the UT is applied to obtain the prior estimates of the state and
covariance matrix, and a robust statistical linearization regression based on
the maximum correntropy criterion (MCC) is then used to obtain the posterior
estimates of the state and covariance. The satisfying performance of the new
algorithm is confirmed by two illustrative examples.


title: Period relations and special values of Rankin-Selberg $L$-functions

abstract:
  This is a survey of recent work on values of Rankin-Selberg $L$-functions of
pairs of cohomological automorphic representations that are {\it critical} in
Deligne's sense. The base field is assumed to be a CM field. Deligne's
conjecture is stated in the language of motives over $\QQ$, and express the
critical values, up to rational factors, as determinants of certain periods of
algebraic differentials on a projective algebraic variety over homology
classes. The results that can be proved by automorphic methods express certain
critical values as (twisted) period integrals of automorphic forms. Using
Langlands functoriality between cohomological automorphic representations of
unitary groups, which can be identified with the de Rham cohomology of Shimura
varieties, and cohomological automorphic representations of $GL(n)$, the
automorphic periods can be interpreted as motivic periods. We report on recent
results of the two authors, of the first-named author with Grobner, and of
Guerberoff.


title:
Weak measurement og the composite Goo-Haenchen shift in the critical
  region

abstract:
  By using a weak measurement technique, we investigated the interplay between
the angular and lateral Goos-Haenchen shift of a focused He-Ne laser beam for
incidence near the critical angle. We verified that this interplay dramatically
affects the composite Goos-Haenchen shift of the propagated beam. The
experimental results confirm theoretical predictions that recently appeared in
the literature.


title: Inverse Diffusivity Problem via Homogenization Theory

abstract:
  Polarization tensor corresponding to near zero volume inhomogeneities was
introduced in the pioneering work by Capdeboscq-Vogelius \cite{CV1,CV2}. A
beautiful application of the polarization tensor to an inverse problem
involving inhomogeneities was also given by them. In this article, we take an
approach toward polarization tensor via homogenized tensor. Accordingly, we
introduce polarization tensor corresponding to inhomogeneities with positive
volume fraction.A relation between this tensor and the homogenized tensor is
found. Next, we proceed to examine the sense in which this tensor is continuous
as the volume fraction tends to zero. Our approach has its own advantages, as
we will see. In particular, it provides another method to deduce optimal
estimates on polarization tensors in any dimension from those on homogenized
tensors, along with the information on underlying microstructures.


title:
Constraining Dark Matter and Ultra-High Energy Cosmic Ray Sources with
  Fermi-LAT Diffuse Gamma Ray Background

abstract:
  We use the recent measurement of the isotropic $\gamma$-ray background (IGRB)
by Fermi LAT and analysis of the contribution of unresolved point $\gamma$-ray
sources to IGRB to build constraints on the models of ultra-high cosmic rays
(UHECR) origin. We also calculate the minimal expected diffuse $\gamma$-ray
flux produced by UHECR interactions with an interstellar photon background.
Finally, for the subclass of dark matter (DM) models with decaying weakly
interacting massive particles (WIMP), we build constraints on the particle
decay time using minimal expected contributions to the IGRB from unresolved
point $\gamma$-ray sources and UHECR.


title:
Syntax and semantics of the weak consistency model specification
  language cat

abstract:
  We provide the syntax and semantics of the cat language, a domain specific
language to describe consistency properties of parallel/distributed programs.
The language is implemented in the herd7 too
(http://diy.inria.fr/doc/herd.html)l.


title: A lower limit on the heat capacity of the neutron star core

abstract:
  We show that observations of the core temperature of transiently-accreting
neutron stars combined with observations of an accretion outburst give a lower
limit to the neutron star core heat capacity. For the neutron stars in the low
mass X-ray binaries KS 1731-260, MXB 1659-29, and XTE J1701-462, we show that
the lower limit is a factor of a few below the core heat capacity expected if
neutrons and protons in the core are paired, so that electrons provide the
dominant contribution to the heat capacity. This limit rules out a core
dominated by a quark color-flavor-locked (CFL) phase, which would have a much
lower heat capacity. Future observations of or limits on cooling during
quiescence will further constrain the core heat capacity.


title:
Near-Optimal Sensor Scheduling for Batch State Estimation: Complexity,
  Algorithms, and Limits

abstract:
  In this paper, we focus on batch state estimation for linear systems. This
problem is important in applications such as environmental field estimation,
robotic navigation, and target tracking. Its difficulty lies on that limited
operational resources among the sensors, e.g., shared communication bandwidth
or battery power, constrain the number of sensors that can be active at each
measurement step. As a result, sensor scheduling algorithms must be employed.
Notwithstanding, current sensor scheduling algorithms for batch state
estimation scale poorly with the system size and the time horizon. In addition,
current sensor scheduling algorithms for Kalman filtering, although they scale
better, provide no performance guarantees or approximation bounds for the
minimization of the batch state estimation error. In this paper, one of our
main contributions is to provide an algorithm that enjoys both the estimation
accuracy of the batch state scheduling algorithms and the low time complexity
of the Kalman filtering scheduling algorithms. In particular: 1) our algorithm
is near-optimal: it achieves a solution up to a multiplicative factor 1/2 from
the optimal solution, and this factor is close to the best approximation factor
1/e one can achieve in polynomial time for this problem; 2) our algorithm has
(polynomial) time complexity that is not only lower than that of the current
algorithms for batch state estimation; it is also lower than, or similar to,
that of the current algorithms for Kalman filtering. We achieve these results
by proving two properties for our batch state estimation error metric, which
quantifies the square error of the minimum variance linear estimator of the
batch state vector: a) it is supermodular in the choice of the sensors; b) it
has a sparsity pattern (it involves matrices that are block tri-diagonal) that
facilitates its evaluation at each sensor set.


title:
Well-Posedness and Stability for a Class of Stochastic Delay
  Differential Equations with Singular Drift

abstract:
  In this paper we prove well-posedness and stabibility of a class of
stochastic delay differential equations with singular drift. Moreover, we show
local well-posedness under localized assumptions.


title: Complex Network Analysis of Brazilian Power Grid

abstract:
  Power Grids and other delivery networks has been attracted some attention by
the network literature last decades. Despite the Power Grids dynamics has been
controlled by computer systems and human operators, the static features of this
type of network can be studied and analyzed. The topology of the Brazilian
Power Grid (BPG) was studied in this work. We obtained the spatial structure of
the BPG from the ONS (electric systems national operator), consisting of
high-voltage transmission lines, generating stations and substations. The local
low-voltage substations and local power delivery as well the dynamic features
of the network were neglected. We analyze the complex network of the BPG and
identify the main topological information, such as the mean degree, the degree
distribution, the network size and the clustering coefficient to caracterize
the complex network. We also detected the critical locations on the network
and, therefore, the more susceptible points to lead to a cascading failure and
even to a blackouts. Surprisely, due to the characteristic of the topology and
physical structure of the network, we show that the BPG is resilient against
random failures, since the random removal of links does not affect
significantly the size of the largest cluster. We observe that when a fraction
of the links are randomly removed, the network may disintegrates into smaller
and disconnected parts, however, the power grid largest component remains
connected. We believe that the even a static study of the network topology can
help to identify the critical situations and also prevent failures and possible
blackouts on the network.


title:
Leveraging over intact priors for boosting control and dexterity of
  prosthetic hands by amputees

abstract:
  Non-invasive myoelectric prostheses require a long training time to obtain
satisfactory control dexterity. These training times could possibly be reduced
by leveraging over training efforts by previous subjects. So-called domain
adaptation algorithms formalize this strategy and have indeed been shown to
significantly reduce the amount of required training data for intact subjects
for myoelectric movements classification. It is not clear, however, whether
these results extend also to amputees and, if so, whether prior information
from amputees and intact subjects is equally useful. To overcome this problem,
we evaluated several domain adaptation algorithms on data coming from both
amputees and intact subjects. Our findings indicate that: (1) the use of
previous experience from other subjects allows us to reduce the training time
by about an order of magnitude; (2) this improvement holds regardless of
whether an amputee exploits previous information from other amputees or from
intact subjects.


title: Updated baseline for a staged Compact Linear Collider

abstract:
  The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e-
collider under development. For an optimal exploitation of its physics
potential, CLIC is foreseen to be built and operated in a staged approach with
three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV.
The first stage will focus on precision Standard Model physics, in particular
Higgs and top-quark measurements. Subsequent stages will focus on measurements
of rare Higgs processes, as well as searches for new physics processes and
precision measurements of new states, e.g. states previously discovered at LHC
or at CLIC itself. In the 2012 CLIC Conceptual Design Report, a fully optimised
3 TeV collider was presented, while the proposed lower energy stages were not
studied to the same level of detail. This report presents an updated baseline
staging scenario for CLIC. The scenario is the result of a comprehensive study
addressing the performance, cost and power of the CLIC accelerator complex as a
function of centre-of-mass energy and it targets optimal physics output based
on the current physics landscape. The optimised staging scenario foresees three
main centre-of-mass energy stages at 380 GeV, 1.5 TeV and 3 TeV for a full CLIC
programme spanning 22 years. For the first stage, an alternative to the CLIC
drive beam scheme is presented in which the main linac power is produced using
X-band klystrons.


title: Higgs Physics at the CLIC Electron-Positron Linear Collider

abstract:
  The Compact Linear Collider (CLIC) is an option for a future e+e- collider
operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a
wide range of new physics phenomena and precision physics measurements at the
energy frontier. This paper is the first comprehensive presentation of the
Higgs physics reach of CLIC operating at three energy stages: sqrt(s) = 350
GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of
Higgs boson production in Higgsstrahlung (e+e- -> ZH) and WW-fusion (e+e- ->
Hnunu), resulting in precise measurements of the production cross sections, the
Higgs total decay width Gamma_H, and model-independent determinations of the
Higgs couplings. Operation at sqrt(s) > 1 TeV provides high-statistics samples
of Higgs bosons produced through WW-fusion, enabling tight constraints on the
Higgs boson couplings. Studies of the rarer processes e+e- -> ttH and e+e- ->
HHnunu allow measurements of the top Yukawa coupling and the Higgs boson
self-coupling. This paper presents detailed studies of the precision achievable
with Higgs measurements at CLIC and describes the interpretation of these
measurements in a global fit.


title: On Weyl's embedding problem in Riemannian manifolds

abstract:
  We consider a priori estimates of Weyl's embedding problem of $(\mathbb{S}^2,
g)$ in general $3$-dimensional Riemannian manifold $(N^3, \bar g)$. We
establish interior $C^2$ estimate under natural geometric assumption. Together
with a recent work by Li and Wang, we obtain an isometric embedding of
$(\mathbb{S}^2,g)$ in Riemannian manifold. In addition, we reprove Weyl's
embedding theorem in space form under the condition that $g\in C^2$ with $D^2g$
Dini continuous.


title:
Bloch wave spectral analysis in the class of generalized
  Hashin-Shtrikman micro-structures

abstract:
  In this paper, we use spectral methods by introducing the Bloch waves to
study the homogenization process in the non-periodic class of generalized
Hashin-Shtrikman micro-structures \cite[page no. 281]{T}, which incorporates
both translation and dilation with a family of scales, including one subclass
of laminates. We establish the classical homogenization result with providing
the spectral representation of the homogenized coefficients. It offers a new
lead towards extending the Bloch spectral analysis in the non-periodic,
non-commutative class of micro-structures.


title: Floer Cohomology, Multiplicity and the Log Canonical Threshold

abstract:
  Let f be a polynomial over the complex numbers with an isolated singularity
at 0. We show that the multiplicity and the log canonical threshold of f at 0
are invariants of the link of f viewed as a contact submanifold of the sphere.
  This is done by first constructing a spectral sequence converging to the
fixed point Floer cohomology of any iterate of the Milnor monodromy map whose
E^1 page is explicitly described in terms of a log resolution of f. This
spectral sequence is a generalization of a formula by A'Campo. By looking at
this spectral sequence, we get a purely Floer theoretic description of the
multiplicity and log canonical threshold of f.


title:
Optical amplitude and phase modulation dynamics at the single-photon
  level in a quantum dot ridge waveguide

abstract:
  The amplitude and phase of a material's nonlinear optical response provide
insight into the underlying electronic dynamics that determine its optical
properties. Phase-sensitive nonlinear spectroscopy techniques are widely
implemented to explore these dynamics through demodulation of the complex
optical signal field into its quadrature components; however, complete
reconstruction of the optical response requires measuring both the amplitude
and phase of each quadrature, which is often lost in standard detection
methods. Here, we implement a heterodyne-detection scheme to fully reconstruct
the amplitude and phase response of spectral hole-burning from InAs/GaAs
charged quantum dots. We observe an ultra-narrow absorption profile and a
corresponding dispersive lineshape of the phase, which reflect the nanosecond
optical coherence time of the charged exciton transition. Simultaneously, the
measurements are sensitive to electron spin relaxation dynamics on a
millisecond timescale, as this manifests as a magnetic-field dependent delay of
the amplitude and phase modulation. Appreciable amplitude modulation depth and
nonlinear phase shift up to 0.09$\times\pi$ radians (16$\deg$) are
demonstrated, providing new possibilities for quadrature modulation at faint
photon levels with several independent control parameters, including photon
number, modulation frequency, detuning, and externally applied fields.


title: Classification of Imprimitive Irreducible Finite Sugroups of O(7)

abstract:
  This work gives a classification of imprimitive irreducible finite subgroups
of the orthogonal group O(7) plus the number of conjugate classes for each
group.


title:
Prediction-Correction Interior-Point Method for Time-Varying Convex
  Optimization

abstract:
  In this paper, we develop an interior-point method for solving a class of
convex optimization problems with time-varying objective and constraint
functions. Using log-barrier penalty functions, we propose a continuous-time
dynamical system for tracking the (time-varying) optimal solution with an
asymptotically vanishing error. This dynamical system is composed of two terms:
(i) a correction term consisting of a continuous-time version of Newton's
method, and (ii) a prediction term able to track the drift of the optimal
solution by taking into account the time-varying nature of the objective and
constraint functions. Using appropriately chosen time-varying slack and barrier
parameters, we ensure that the solution to this dynamical system globally
asymptotically converges to the optimal solution at an exponential rate. We
illustrate the applicability of the proposed method in two practical
applications: a sparsity promoting least squares problem and a collision-free
robot navigation problem.


title:
Dispersion tensor and its unique minimizer in Hashin-Shtrikman
  micro-structures

abstract:
  In this paper, we introduce the macroscopic quantity, namely the dispersion
tensor or the \textit{Burnett coefficient}s in the class of generalized
Hashin-Shtrikman micro-structures \cite[page no. 281]{T}. In the case of
two-phase materials associated with the periodic Hashin-Shtrikman structures,
we settle the issue that the dispersion tensor has an unique minimizer, which
is so called Apollonian-Hashin-Shtrikman micro-structure.


title:
Spectroscopic mapping of the physical properties of supernova remnant
  N\,49

abstract:
  Physical conditions inside a supernova remnant can vary significantly between
different positions. However, typical observational data are integrated data or
contemplate specific portions of the remnant. We study the spatial variation in
the physical properties of the N\,49 supernova remnant based on a spectroscopic
mapping of the whole nebula. Long-slit spectra were obtained with the slit
($\sim4\arcmin \times 1.03\arcsec$) aligned along the east-west direction from
29 different positions spaced by $2\arcsec$ in declination. A total of 3248 1D
spectra were extracted from sections of $2\arcsec$ of the 2D spectra. More than
60 emission lines in the range 3550\,\AA{} to 8920\,\AA{} were measured in
these spectra. Maps of the fluxes and of intensity ratios of these emission
lines were built with a spatial resolution of $2\arcsec \times 2\arcsec$. An
electron density map has been obtained using the [S\,{\sc
ii}]\,$\lambda6716/\lambda6731$ line ratio. Values vary from
$\sim$500\,cm$^{-3}$ at the northeast region to more than 3500 cm$^{-3}$ at the
southeast border. We calculated electron temperature using line ratio sensors
for the ions S$^{+}$, O$^{++}$, O$^{+}$, and N$^{+}$. Values are about
3.6$\times10^{4}$\,K for the O$^{++}$ sensor and about 1.1$\times10^{4}$\,K for
other sensors. The H$\alpha$/H$\beta$ ratio map presents a ring structure with
higher values that may result from collisional excitation of hydrogen. We
detected an area with high values of [N\,{\sc ii}]\,$\lambda6583$/H$\alpha$
extending from the remnant center to its northeastern border, that can be
indicating an overabundance of nitrogen in the area due to contamination by the
progenitor star. We found a radial dependence in many line intensity ratio
maps. We observed an increase toward the remnant borders of the intensity ratio
of any two lines in which the numerator comes before in a sequence of lines.


title:
TriCheck: Memory Model Verification at the Trisection of Software,
  Hardware, and ISA

abstract:
  Memory consistency models (MCMs) which govern inter-module interactions in a
shared memory system, are a significant, yet often under-appreciated, aspect of
system design. MCMs are defined at the various layers of the hardware-software
stack, requiring thoroughly verified specifications, compilers, and
implementations at the interfaces between layers. Current verification
techniques evaluate segments of the system stack in isolation, such as proving
compiler mappings from a high-level language (HLL) to an ISA or proving
validity of a microarchitectural implementation of an ISA.
  This paper makes a case for full-stack MCM verification and provides a
toolflow, TriCheck, capable of verifying that the HLL, compiler, ISA, and
implementation collectively uphold MCM requirements. The work showcases
TriCheck's ability to evaluate a proposed ISA MCM in order to ensure that each
layer and each mapping is correct and complete. Specifically, we apply TriCheck
to the open source RISC-V ISA, seeking to verify accurate, efficient, and legal
compilations from C11. We uncover under-specifications and potential
inefficiencies in the current RISC-V ISA documentation and identify possible
solutions for each. As an example, we find that a RISC-V-compliant
microarchitecture allows 144 outcomes forbidden by C11 to be observed out of
1,701 litmus tests examined. Overall, this paper demonstrates the necessity of
full-stack verification for detecting MCM-related bugs in the hardware-software
stack.


title: Non Relativistic Limit of Integrable QFT and Lieb-Liniger Models

abstract:
  In this paper we study a suitable limit of integrable QFT with the aim to
identify continuous non-relativistic integrable models with local interactions.
This limit amounts to sending to infinity the speed of light c but
simultaneously adjusting the coupling constant g of the quantum field theories
in such a way to keep finite the energies of the various excitations. The QFT
considered here are Toda Field Theories and the O(N) non-linear sigma model. In
both cases the resulting non-relativistic integrable models consist only of
Lieb-Liniger models, which are fully decoupled for the Toda theories while
symmetrically coupled for the O(N) model. These examples provide explicit
evidence of the universality and ubiquity of the Lieb-Liniger models and, at
the same time, suggest that these models may exhaust the list of possible
non-relativistic integrable theories of bosonic particles with local
interactions.

categories: cond-mat.stat-mech hep-th math-ph math.MP


title:
Torsion subgroups of elliptic curves over quintic and sextic number
  fields

abstract:
  Let $\Phi^\infty(d)$ denote the set of finite abelian groups that occur
infinitely often as the torsion subgroup of an elliptic curve over a number
field of degree $d$. The sets $\Phi^\infty(d)$ are known for $d\le 4$. In this
article we determine $\Phi^\infty(5)$ and $\Phi^\infty(6)$.


title:
Automated alignment of a reconfigurable optical system using focal-plane
  sensing and Kalman filtering

abstract:
  Automation of alignment tasks can provide improved efficiency and greatly
increase the flexibility of an optical system. Current optical systems with
automated alignment capabilities are typically designed to include a dedicated
wavefront sensor. Here, we demonstrate a self-aligning method for a
reconfigurable system using only focal plane images. We define a two lens
optical system with eight degrees of freedom. Images are simulated given
misalignment parameters using ZEMAX software. We perform a principal component
analysis (PCA) on the simulated dataset to obtain Karhunen-Lo\`eve (KL) modes,
which form the basis set whose weights are the system measurements. A model
function which maps the state to the measurement is learned using nonlinear
least squares fitting and serves as the measurement function for the nonlinear
estimator (Extended and Unscented Kalman filters) used to calculate control
inputs to align the system. We present and discuss both simulated and
experimental results of the full system in operation.


abstract:
  Broadly speaking, this thesis is about nonlinear optics, quantum mechanics,
and computing. More specifically, it covers four main topics: Coherent LQG
Control, Free-Carrier Oscillations, Optical Ising Machines and Pulsed OPO
Dynamics. Tying them all together is a theory of open quantum systems called
the SLH model, which I introduce in Chapters 1-2. The SLH model is a general
framework for open quantum systems that interact through bosonic fields, and is
the basis for the quantum circuit theory developed in the text. Coherent LQG
control is discussed in Chapters 3-4, where I demonstrate that coherent
feedback outperforms measurement-based feedback for certain linear
quadratic-Gaussian (LQG) problems, and explain the discrepancy by the former's
simultaneous utilization of both light quadratures. Semiclassical
truncated-Wigner techniques for quantum-optical networks are discussed in
Chapter 5, leading to a thorough discussion of quantum noise in systems with
free-carrier nonlinearities (Chapter 6), comparison to the Kerr nonlinearity,
and potential applications for analog computing based on limit cycles and
amplification (Chapters 7-8). Ising machines based on optical parametric
oscillators (OPOs) are discussed in Chapters 9-10, the former focusing on large
1D and 2D networks of OPOs, and the latter on the dynamics of a single OPO in
the ultrafast, synchronously-pumped regime. Optical properties and design
considerations for silicon photonic waveguides are are treated in Chapter 11.


title: Bloch Wave Homogenization Relative to a Microstructure

abstract:
  In this work, we study the aspect of Bloch wave homogenization of the new
notion of convergence of microstructures represented by matrices $B^\epsilon$
related to the classical $H$-convergence of $A^\epsilon$ introduced in
\cite{TG-MV-1}. The new macro quantity $B^{#}$ appears to incorporate the
interaction between the two microstructures $A^\epsilon,B^\epsilon$. Here we
present its Bloch spectral representation along with the homogenization result.


title:
Time-dependent neo-deterministic seismic hazard scenarios: Preliminary
  report on the M6.2 Central Italy earthquake, 24th August 2016

abstract:
  A scenario-based Neo-Deterministic approach to Seismic Hazard Assessment
(NDSHA) is available nowadays, which permits considering a wide range of
possible seismic sources as the starting point for deriving scenarios by means
of full waveforms modeling. The method does not make use of attenuation
relations and naturally supplies realistic time series of ground shaking,
including reliable estimates of ground displacement, readily applicable to
complete engineering analysis. Based on the neo-deterministic approach, an
operational integrated procedure for seismic hazard assessment has been
developed that allows for the definition of time dependent scenarios of ground
shaking, through the routine updating of earthquake predictions, performed by
means of the algorithms CN and M8S. The integrated NDSHA procedure for seismic
input definition, which is currently applied to the Italian territory, combines
different pattern recognition techniques, designed for the space-time
identification of strong earthquakes, with algorithms for the realistic
modeling of ground motion. Accordingly, a set of deterministic scenarios of
ground motion at bedrock, which refers to the time interval when a strong event
is likely to occur within the alerted area, is defined both at regional and
local scale. CN and M8S predictions, as well as the related time-dependent
ground motion scenarios associated with the alarmed areas, are routinely
updated since 2006. The prospective application of the time-dependent NDSHA
approach provides information that can be useful in assigning priorities for
timely mitigation actions and, at the same time, allows for a rigorous
validation of the proposed methodology. The results from real-time testing of
the time-dependent NDSHA scenarios are illustrated with specific reference to
the August 24th, 2016 Central Italy earthquake.


title: Tools for CICYs in F-theory

abstract:
  We provide a set of tools for analyzing the geometry of elliptically fibered
Calabi-Yau manifolds, starting with a description of the total space rather
than with a Weierstrass model or a specified type of fiber/base. Such an
approach to the subject of F-theory compactification makes certain geometric
properties, which are usually hidden, manifest. Specifically, we review how to
isolate genus-one fibrations in such geometries and then describe how to find
their sections explicitly. This includes a full parameterization of the
Mordell-Weil group where non-trivial. We then describe how to analyze the
associated Weierstrass models, Jacobians and resolved geometries. We illustrate
our discussion with concrete examples which are complete intersections in
products of projective spaces (CICYs). The examples presented include cases
exhibiting non-abelian symmetries and higher rank Mordell-Weil group. We also
make some comments on non-flat fibrations in this context. In a companion paper
[1] to this one, these results will be used to analyze the consequences for
string dualities of the ubiquity of multiple fibrations in known constructions
of Calabi-Yau manifolds.


title: Multiple Fibrations in Calabi-Yau Geometry and String Dualities

abstract:
  In this work we explore the physics associated to Calabi-Yau (CY) n-folds
that can be described as a fibration in more than one way. Beginning with
F-theory vacua in various dimensions, we consider limits/dualities with
M-theory, type IIA, and heterotic string theories. Our results include many
M-/F-theory correspondences in which distinct F-theory vacua - associated to
different elliptic fibrations of the same CY n-fold - give rise to the same
M-theory limit in one dimension lower. Examples include 5-dimensional
correspondences between 6-dimensional theories with Abelian, non-Abelian and
superconformal structure, as well as examples of higher rank Mordell-Weil
geometries. In addition, in the context of heterotic/F-theory duality, we
investigate the role played by multiple K3- and elliptic fibrations in known
and novel string dualities in 8-, 6- and 4-dimensional theories. Here we
systematically summarize nested fibration structures and comment on the roles
they play in T-duality, mirror symmetry, and 4-dimensional compactifications of
F-theory with G-flux. This investigation of duality structures is made possible
by geometric tools developed in a companion paper [1].


title: Radiation Hardness of 30 cm Long CsI(Tl) Crystals

abstract:
  Measurements of the degradation in performance of 30 cm long CsI(Tl)
scintillation crystals exposed to 1 MeV photon doses of 2, 10, 35, 100 and 1000
Gy are presented. The light yield, light yield longitudinal non-uniformity,
scintillation decay times, energy resolution and timing resolution of a set of
spare crystals from the BABAR and Belle experiments are studied as a function
of these doses. In addition, a model that describes the plateau observed in the
light output loss as a function of dose in terms of increase in concentrations
of absorption centres with irradiation is presented.


title:
Non-Hermitian coupled-mode theory for incoherently pumped
  exciton-polariton condensates

abstract:
  The generalized Gross-Pitaevskii equation (gGPE) is an effective
phenomenological description for the dynamics of incoherently pumped
exciton-polariton condensates. However, a brute force numerical simulation of
the gGPE provides little physical insight into condensate formation under
arbitrary pumping configurations, and is demanding in terms of computational
resources. We introduce in this paper a modal description of polariton
condensation under incoherent pumping of arbitrary spatial profile, based on
eigenmodes of the non-Hermitian generator of the linearized dynamics. A
pump-dependent basis is then introduced to formulate a temporal coupled-mode
theory that captures condensate dynamics in the presence of all nonlinear
interactions. Simulations using a single set of modes for a given pumping and
trapping configuration agree very well with a full integration of the gGPE in
diverse dynamical regimes, supporting the validity of this modal description,
while also providing a speedup in simulation times.


title: Gradient expansion for anisotropic hydrodynamics

abstract:
  We compute the gradient expansion for anisotropic hydrodynamics. The results
are compared with the corresponding expansion of the underlying kinetic-theory
model with the collision term treated in the relaxation time approximation. We
find that a recent formulation of anisotropic hydrodynamics based on an
anisotropic matching principle yields the first three terms of the gradient
expansion in agreement with those obtained for the kinetic theory. This gives
further support for this particular hydrodynamic model as a good approximation
of the kinetic-theory approach. We further find that the gradient expansion of
anisotropic hydrodynamics is an asymptotic series, and the singularities of the
analytic continuation of its Borel transform indicate the presence of
non-hydrodynamic modes.


title:
Energy dependence of dissociative $\mathrm{J/}\psi$ photoproduction as a
  signature of gluon saturation at the LHC

abstract:
  We have developed a model in which the quantum fluctuations of the proton
structure are characterised by hot spots, whose number grows with decreasing
Bjorken-$x$. Our model reproduces the $F_2(x,Q^2)$ data from HERA at the
relevant scale, as well as the exclusive and dissociative $\mathrm{J/}\psi$
photoproduction data from H1 and ALICE. Our model predicts that for
$W_{\gamma\mathrm{p}} \approx 500$ GeV, the dissociative $\mathrm{J/}\psi$
cross section reaches a maximum and then decreases steeply with energy, which
is in qualitatively good agreement to a recent observation that the
dissociative $\mathrm{J/}\psi$ background in the exclusive $\mathrm{J/}\psi$
sample measured in photoproduction by ALICE decreases as energy increases. Our
prediction provides a clear signature for gluon saturation at LHC energies.


title:
The inverse scattering problem for a conductive boundary condition and
  transmission eigenvalues

abstract:
  In this paper, we consider the inverse scattering problem associated with an
inhomogeneous media with a conductive boundary. First, we discuss the inverse
conductivity problem of reconstructing the conductivity parameter from
scattering data. Next, we consider the corresponding interior transmission
eigenvalue problem. This is a new class of eigenvalue problem that is not
elliptic, not self-adjoint, and non-linear, which gives the possibility of
complex eigenvalues. We investigate the convergence of the eigenvalues as the
conductivity parameter tends to zero as well as prove existence and
discreteness for the case of an absorbing media. Lastly, several numerical and
analytical results support the theory and we show that the inside-outside
duality method can be used to reconstruct the interior conductive eigenvalues.


title:
Measurement of the production cross section of a W boson in association
  with two b jets in pp collisions at sqrt(s) = 8 TeV

abstract:
  The production cross section of a W boson in association with two b jets is
measured using a sample of proton-proton collisions at sqrt(s) = 8 TeV
collected by the CMS experiment at the CERN LHC. The data sample corresponds to
an integrated luminosity of 19.8 inverse femtobarns. The W bosons are
reconstructed via their leptonic decays, W to l nu, where l = mu or e. The
fiducial region studied contains exactly one lepton with transverse momentum
pt[l] > 30 GeV and pseudorapidity abs(eta[l]) < 2.1, with exactly two b jets
with pt > 25 GeV and abs(eta) < 2.4 and no other jets with pt > 25 GeV and
abs(eta) < 4.7. The cross section is measured to be sigma(pp to W (l nu)+
bb-bar) = 0.64 +/- 0.03 (stat) +/- 0.10 (syst) +/- 0.06 (theo) +/- 0.02 (lumi)
pb, in agreement with standard model predictions.


title: Detailed abundance analysis of a metal-poor giant in the Galactic Center

abstract:
  We report the first results from our program to examine the metallicity
distribution of the Milky Way nuclear star cluster connected to SgrA*, with the
goal of inferring the star formation and enrichment history of this system, as
well as its connection and relationship with the central 100 pc of the
bulge/bar system. We present the first high resolution (R~24,000), detailed
abundance analysis of a K=10.2 metal-poor, alpha-enhanced red giant projected
at 1.5 pc from the Galactic Center, using NIRSPEC on Keck II. A careful
analysis of the dynamics and color of the star locates it at about 26 pc
line-of-sight distance in front of the nuclear cluster. It probably belongs to
one of the nuclear components (cluster or disk), not to the bar-bulge or
classical disk. A detailed spectroscopic synthesis, using a new linelist in the
K band, finds [Fe/H]~-1.0 and [alpha/Fe]~+0.4, consistent with stars of similar
metallicity in the bulge. As known giants with comparable [Fe/H] and alpha
enhancement are old, we conclude that this star is most likely to be a
representative of the ~10 Gyr old population. This is also the most metal poor
confirmed red giant yet discovered in vicinity of the nuclear cluster of the
Galactic Center. We consider recent reports in the literature of a surprisingly
large number of metal poor giants in the Galactic Center, but the reported
gravities of log g ~4 for these stars calls into question their reported
metallicities.


title:
A monolithic 56 Gb/s silicon photonic pulse-amplitude modulation
  transmitter

abstract:
  Silicon photonics promises to address the challenges for next-generation
short-reach optical interconnects. Growing bandwidth demand in hyper-scale data
centers and high-performance computing motivates the development of faster and
more-efficient silicon photonics links. While it is challenging to raise the
serial line rate, further scaling of the data rate can be realized by, for
example, increasing the number of parallel fibers, increasing the number of
wavelengths per fiber, and using multi-level pulse-amplitude modulation (PAM).
Among these approaches, PAM has a unique advantage because it does not require
extra lasers or a costly overhaul of optical fiber cablings within the existing
infrastructure. Here, we demonstrate the first fully monolithically integrated
silicon photonic four-level PAM (PAM-4) transmitter operating at 56 Gb/s and
demonstrate error-free transmission (bit-error-rate < 10$^{-12}$) up to 50 Gb/s
without forward error correction. The superior PAM-4 waveform is enabled by
optimization of silicon traveling wave modulators and monolithic integration of
the CMOS driver circuits. Our results show that monolithic silicon photonics
technology is a promising platform for future ultrahigh data rate optical
interconnects.


title: #P- and $\oplus$P- completeness of counting roots of a sparse polynomial

abstract:
  We improve and simplify the result of the part 4 of "Counting curves and
their projections" (Joachim von zur Gathen, Marek Karpinski, Igor Shparlinski)
by showing that counting roots of a sparse polynomial over $\mathbb{F}_{2^n}$
is #P- and $\oplus$P-complete under deterministic reductions.


title: Patterns of Gendered Performance Difference in Introductory STEM Courses

abstract:
  Grades provide students with their primary performance feedback: signals
which affect academic choices. Variations in grading practice among courses
impose grade penalties (and bonuses) on students who take them. These grade
penalties are sometimes gendered. Using extensive data from the University of
Michigan, we report on patterns of grade penalty and gendered performance
difference across 116 large courses. We find that significant gendered
performance differences are ubiquitous in large introductory STEM lecture
courses. They are largely absent in both STEM labs and in lecture courses in
other disciplines. Exploring the features of these courses, we hypothesize that
evaluation methods used in STEM lecture courses interact with stereotype threat
to create these gendered performance differences.


title: On Sokhotski--Casorati--Weierstrass theorem on metric spaces

abstract:
  In a neighborhood of isolated point of a domain of a metric space, a behavior
of generalized quasiconformal mappings is studied. It is proved that, mappings
mentioned above have continuous extension to the domain at some additional
conditions. As consequence, an analog of Sokhotski--Weierstrass theorem is
obtained.


title: Bi-Local Holography in the SYK Model: Perturbations

abstract:
  We continue the study of the Sachdev-Ye-Kitaev model in the Large $N$ limit.
Following our formulation in terms of bi-local collective fields with dynamical
reparametrization symmetry, we perform perturbative calculations around the
conformal IR point.


title: Graphic TSP in cubic graphs

abstract:
  We present a polynomial-time 9/7-approximation algorithm for the graphic TSP
for cubic graphs, which improves the previously best approximation factor of
1.3 for 2-connected cubic graphs and drops the requirement of 2-connectivity at
the same time. To design our algorithm, we prove that every simple 2-connected
cubic n-vertex graph contains a spanning closed walk of length at most 9n/7-1,
and that such a walk can be found in polynomial time.


title:
Information-theoretic limitations on approximate quantum cloning and
  broadcasting

abstract:
  We prove new quantitative limitations on any approximate simultaneous cloning
or broadcasting of mixed states. The results are based on information-theoretic
(entropic) considerations and generalize the well known no-cloning and
no-broadcasting theorems. We also observe and exploit the fact that the
universal cloning machine on the symmetric subspace of $n$ qudits and
symmetrized partial trace channels are dual to each other. This duality
manifests itself both in the algebraic sense of adjointness of quantum channels
and in the operational sense that a universal cloning machine can be used as an
approximate recovery channel for a symmetrized partial trace channel and vice
versa. The duality extends to give control on the performance of generalized
UQCMs on subspaces more general than the symmetric subspace. This gives a way
to quantify the usefulness of a-priori information in the context of cloning.
For example, we can control the performance of an antisymmetric analogue of the
UQCM in recovering from the loss of $n-k$ fermionic particles.


title: A short proof of Hulanicki's Theorem

abstract:
  We outline a simple proof of Hulanicki's theorem, that a locally compact
group is amenable if and only if the left regular representation weakly
contains all unitary representations. This combines some elements of the
literature which have not appeared together, before.


title: The weak Harnack inequality for the Boltzmann equation without cut-off

abstract:
  In this paper, we obtain the weak Harnack inequality and H\"older estimates
for a large class of kinetic integro-differential equations. We prove that the
Boltzmann equation without cut-off can be written in this form and satisfies
our assumptions provided that the mass density is bounded away from vacuum and
mass, energy and entropy densities are bounded above. As a consequence, we
derive a local H\"older estimate and a quantitative lower bound for solutions
of the (inhomogeneous) Boltzmann equation without cut-off.


title:
Unexpectedly large difference of the electron density at the nucleus in
  the 4p $^2$P$_{1/2,3/2}$ fine-structure doublet of Ca$^+$

abstract:
  We measured the isotope shift in the $^2$S$_{1/2}$-$^2$P$_{3/2}$ (D2)
transition in singly-ionized calcium ions using photon recoil spectroscopy. The
high accuracy of the technique enables us to resolve the difference between the
isotope shifts of this transition to the previously measured isotopic shifts of
the $^2$S$_{1/2}$-$^2$P$_{1/2}$ (D1) line. This so-called splitting isotope
shift is extracted and exhibits a clear signature of field shift contributions.
From the data we were able to extract the small difference of the field shift
coefficient and mass shifts between the two transitions with high accuracy.
This J-dependence is of relativistic origin and can be used to benchmark atomic
structure calculations. As a first step, we use several ab initio atomic
structure calculation methods to provide more accurate values for the field
shift constants and their ratio. Remarkably, the high-accuracy value for the
ratio of the field shift constants extracted from the experimental data is
larger than all available theoretical predictions.


title: Containers for portable, productive and performant scientific computing

abstract:
  Containers are an emerging technology that hold promise for improving
productivity and code portability in scientific computing. We examine Linux
container technology for the distribution of a non-trivial scientific computing
software stack and its execution on a spectrum of platforms from laptop
computers through to high performance computing (HPC) systems. We show on a
workstation and a leadership-class HPC system that when deployed appropriately
there are no performance penalties running scientific programs inside
containers. For Python code run on large parallel computers, the run time is
reduced inside a container due to faster library imports. The software
distribution approach and data that we present will help developers and users
decide on whether container technology is appropriate for them. We also provide
guidance for the vendors of HPC systems that rely on proprietary libraries for
performance on what they can do to make containers work seamlessly and without
performance penalty.


title:
The Onset of Thermalisation in Finite-Dimensional Equations of
  Hydrodynamics: Insights from the Burgers Equation

abstract:
  Solutions to finite-dimensional (all spatial Fourier modes set to zero beyond
a finite wavenumber $K_G$), inviscid equations of hydrodynamics at long times
are known to be at variance with those obtained for the original infinite
dimensional partial differential equations or their viscous counterparts.
Surprisingly, the solutions to such Galerkin-truncated equations develop sharp
localised structures, called {\it tygers} [Ray, et al., Phys. Rev. E {\bf 84},
016301 (2011)], which eventually lead to completely thermalised states
associated with an equipartition energy spectrum. We now obtain, by using the
analytically tractable Burgers equation, precise estimates, theoretically and
via direct numerical simulations, of the time $\tau_c$ at which thermalisation
is triggered and show that $\tau_c \sim \kg^\xi$, with $\xi = -4/9$. Our
results have several implications including for the analyticity strip method to
numerically obtain evidence for or against blow-ups of the three-dimensional
incompressible Euler equations.

categories: physics.flu-dyn cond-mat.stat-mech math-ph math.MP nlin.CD


title: Strategic play in stable marriage problem

abstract:
  The stable marriage problem, as addressed by Gale and Shapely [1] consists of
providing a bipartite matching between n " boys " and n " girls "-each of whom
have a totally ordered preference list over the other set-such that there
exists no " boy " and no " girl " that would prefer each other over their
partner in the matching. In this paper, we analyze the cases of strategic play
by the " boys " in the game directly inspired by this problem. We provide an
O(n^3) algorithm for determining a matching which is not necessarily stable in
the Gale-Shapely sense, but it is coalition-stable, in that no player has a
selfish interest to leave the resulting grand coalition to join any potential
alternative one which might feasibly form, and is also man-optimal. Thus, under
a realistic assumption set, no player has an interest to " destabilize " the
matching, even though he theoretically could. The resulting matching is often
better than the na\"ive Gale-Shapely one for some (not all) of the " boys " ,
being no worse for the rest. This matching is more realistic (stable) than the
one produced by top-trading-cycles method, thus offering a qualitative
improvement over the latter. Furthermore, we analyze the situation when players
are allowed to make strategic threats (i.e. be willing to sacrifice their own
outcome to hurt others), offer a relevant example to illustrate the benefits of
this form of play, and ultimately provide an exponential time algorithm which
tries to determine a good threat-making strategy. We then briefly examine a few
other non-conventional possibilities a player has to affect his outcome. Most
common variations to the game model are also described and analyzed with regard
to applicability of the methods in this paper. Finally, a few examples of
real-life problems which can be modeled and solved with the methods in this
paper are presented.


title: Inflation Expels Runaways

abstract:
  We argue that moduli stabilization generically restricts the evolution
following transitions between weakly coupled de Sitter vacua and can induce a
strong selection bias towards inflationary cosmologies. The energy density of
domain walls between vacua typically destabilizes Kahler moduli and triggers a
runaway towards large volume. This decompactification phase can collapse the
new de Sitter region unless a minimum amount of inflation occurs after the
transition. A stable vacuum transition is guaranteed only if the inflationary
expansion generates overlapping past light cones for all observable modes
originating from the reheating surface, which leads to an approximately flat
and isotropic universe. High scale inflation is vastly favored. Our results
point towards a framework for studying parameter fine-tuning and inflationary
initial conditions in flux compactifications.


title: Must Starforming Galaxies Rapidly Get Denser Before They Quench?

abstract:
  Using the deepest data yet obtained, we find no evidence preferring
compaction-triggered quenching---where rapid increases in galaxy density
truncate star formation---over a null hypothesis in which galaxies age at
constant surface density ($\Sigma_e\equiv M_*/2\pi r_{e}^{2}$). Results from
two fully empirical analyses and one quenching-free model calculation support
this claim at all $z\leq3$: (1) Qualitatively, galaxies' mean $U-V$ colors at
$6.5\lesssim\log\Sigma_e/{\rm M_\odot}\,{\rm kpc}^{-2}\lesssim10$ have reddened
at rates/times correlated with $\Sigma_e$, implying that there is no density
threshold at which galaxies turn red but that $\Sigma_e$ sets the pace of
maturation; (2) Quantitatively, the abundance of $\log M_*/{\rm
M_\odot}\geq9.4$ red galaxies never exceeds that of the total population a
quenching time earlier at any $\Sigma_e$, implying that galaxies need not
transit from low to high densities before quenching; (3) Applying $d\log
r_{e}/dt =1/2\,d\log M_*/dt$ to a suite of lognormal star formation histories
reproduces the evolution of the size--mass relation at $\log M_*\geq10$. All
results are consistent with evolutionary rates being set ab initio by global
densities, with denser objects evolving faster than less-dense ones towards a
terminal quiescence induced by gas depletion or other $\sim$Hubble-timescale
phenomena. Unless stellar ages demand otherwise, observed $\Sigma_e$ thresholds
need not bear any physical relation to quenching beyond this intrinsic
density--formation epoch correlation, adding to Lilly & Carollo's arguments to
that effect.


title:
The Vev Flip-Flop: Dark Matter Decay between Weak Scale Phase
  Transitions

abstract:
  We propose a new alternative to the Weakly Interacting Massive Particle
(WIMP) paradigm for dark matter. Rather than being determined by thermal
freeze-out, the dark matter abundance in this scenario is set by dark matter
decay, which is allowed for a limited amount of time just before the
electroweak phase transition. More specifically, we consider fermionic singlet
dark matter particles coupled weakly to a scalar mediator $S_3$ and to
auxiliary dark sector fields, charged under the Standard Model gauge groups.
Dark matter freezes out while still relativistic, so its abundance is initially
very large. As the Universe cools down, the scalar mediator develops a vacuum
expectation value (vev), which breaks the symmetry that stabilises dark matter.
This allows dark matter to mix with charged fermions and decay. During this
epoch, the dark matter abundance is reduced to give the value observed today.
Later, the SM Higgs field also develops a vev, which feeds back into the $S_3$
potential and restores the dark sector symmetry. In a concrete model we show
that this "vev flip-flop" scenario is phenomenologically successful in the most
interesting regions of its parameter space. We also comment on detection
prospects at the LHC and elsewhere.


title:
The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to
  far-infrared catalogs, medium-bandwidth photometric redshifts with improved
  accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5

abstract:
  The FourStar galaxy evolution survey (ZFOURGE) is a 45 night legacy program
with the FourStar near-infrared camera on Magellan and one of the most
sensitive surveys to date. ZFOURGE covers a total of $400\ \mathrm{arcmin}^2$
in cosmic fields CDFS, COSMOS and UDS, overlapping CANDELS. We present
photometric catalogs comprising $>70,000$ galaxies, selected from ultradeep
$K_s$-band detection images ($25.5-26.5$ AB mag, $5\sigma$, total), and $>80\%$
complete to $K_s<25.3-25.9$ AB. We use 5 near-IR medium-bandwidth filters
($J_1,J_2,J_3,H_s,H_l$) as well as broad-band $K_s$ at $1.05\ - 2.16\ \mu m$ to
$25-26$ AB at a seeing of $\sim0.5$". Each field has ancillary imaging in
$26-40$ filters at $0.3-8\ \mu m$. We derive photometric redshifts and stellar
population properties. Comparing with spectroscopic redshifts indicates a
photometric redshift uncertainty $\sigma_z={0.010,0.009}$, and 0.011 in CDFS,
COSMOS, and UDS. As spectroscopic samples are often biased towards bright and
blue sources, we also inspect the photometric redshift differences between
close pairs of galaxies, finding $\sigma_{z,pairs}= 0.01-0.02$ at $1<z<2.5$. We
quantify how $\sigma_{z,pairs}$ depends on redshift, magnitude, SED type, and
the inclusion of FourStar medium bands. $\sigma_{z,pairs}$ is smallest for
bright, blue star-forming samples, while red star-forming galaxies have the
worst $\sigma_{z,pairs}$. Including FourStar medium bands reduces
$\sigma_{z,pairs}$ by 50\% at $1.5<z<2.5$. We calculate SFRs based on
ultraviolet and ultradeep far-IR $Spitzer$/MIPS and Herschel/PACS data. We
derive rest-frame $U-V$ and $V-J$ colors, and illustrate how these correlate
with specific SFR and dust emission to $z=3.5$. We confirm the existence of
quiescent galaxies at $z\sim3$, demonstrating their SFRs are suppressed by
$>\times15$.


title: The fates of Solar system analogues with one additional distant planet

abstract:
  The potential existence of a distant planet ("Planet Nine") in the Solar
system has prompted a re-think about the evolution of planetary systems. As the
Sun transitions from a main sequence star into a white dwarf, Jupiter, Saturn,
Uranus and Neptune are currently assumed to survive in expanded but otherwise
unchanged orbits. However, a sufficiently-distant and sufficiently-massive
extra planet would alter this quiescent end scenario through the combined
effects of Solar giant branch mass loss and Galactic tides. Here, I estimate
bounds for the mass and orbit of a distant extra planet that would incite
future instability in systems with a Sun-like star and giant planets with
masses and orbits equivalent to those of Jupiter, Saturn, Uranus and Neptune. I
find that this boundary is diffuse and strongly dependent on each of the
distant planet's orbital parameters. Nevertheless, I claim that instability
occurs more often than not when the planet is as massive as Jupiter and
harbours a semimajor axis exceeding about 300 au, or has a mass of a
super-Earth and a semimajor axis exceeding about 3000 au. These results hold
for orbital pericentres ranging from 100 to at least 400 au. This instability
scenario might represent a common occurrence, as potentially evidenced by the
ubiquity of metal pollution in white dwarf atmospheres throughout the Galaxy.


title:
Cross-correlating Planck tSZ with RCSLenS weak lensing: Implications for
  cosmology and AGN feedback

abstract:
  We present measurements of the spatial mapping between (hot) baryons and the
total matter in the Universe, via the cross-correlation between the thermal
Sunyaev-Zeldovich (tSZ) map from Planck and the weak gravitational lensing maps
from the Red Sequence Cluster Survey (RCSLenS). The cross-correlations are
performed on the map level where all the sources (including diffuse
intergalactic gas) contribute to the signal. We consider two
configuration-space correlation function estimators, $\xi^{ y-\kappa}$ and
$\xi^ {y-\gamma_{t}}$, and a Fourier space estimator, $C_{\ell}^{y-\kappa}$, in
our analysis. We detect a significant correlation out to three degrees of
angular separation on the sky. Based on statistical noise only, we can report
13$\sigma$ and 17$\sigma$ detections of the cross-correlation using the
configuration-space $y-\kappa$ and $y-\gamma_{t}$ estimators, respectively.
Including a heuristic estimate of the sampling variance yields a detection
significance of 6$\sigma$ and 8$\sigma$, respectively. A similar level of
detection is obtained from the Fourier-space estimator, $C_{\ell}^{y-\kappa}$.
As each estimator probes different dynamical ranges, their combination improves
the significance of the detection. We compare our measurements with predictions
from the cosmo-OWLS suite of cosmological hydrodynamical simulations, where
different galactic feedback models are implemented. We find that a model with
considerable AGN feedback that removes large quantities of hot gas from galaxy
groups and WMAP-7yr best-fit cosmological parameters provides the best match to
the measurements. All baryonic models in the context of a Planck cosmology
over-predict the observed signal. Similar cosmological conclusions are drawn
when we employ a halo model with the observed `universal' pressure profile.


title:
Exceptional F(4) Higher-Spin Theory in AdS(6) at One-Loop and other
  Tests of Duality

abstract:
  We study the higher-spin gauge theory in six-dimensional anti-de Sitter space
$AdS_6$ that is based on the exceptional Lie superalgebra $F(4)$. The relevant
higher-spin algebra was constructed in arXiv:1409.2185 [hep-th]. We determine
the spectrum of the theory and show that it contains the physical fields of the
Romans $F(4)$ gauged supergravity. The full spectrum consists of an infinite
tower of unitary supermultiplets of $F(4)$ which extend the Romans multiplet to
higher spins plus a single short supermultiplet.
  Motivated by applications to this novel supersymmetric higher-spin theory as
well as to other theories, we extend the known one-loop tests of $AdS/CFT$
duality in various directions. The spectral zeta-function is derived for the
most general case of fermionic and mixed-symmetry fields, which allows one to
test the Type-A and B theories and supersymmetric extensions thereof in any
dimension. We also study higher-spin doubletons and partially-massless fields.
While most of the tests are successfully passed, the Type-B theory in all even
dimensional anti-de Sitter spacetimes presents an interesting puzzle: the free
energy as computed from the bulk is not equal to that of the free fermion on
the CFT side, though there is some systematics to the discrepancy.


title:
Palatable Leptoquark Scenarios for Lepton Flavor Violation in Exclusive
  $b\to s\ell_1\ell_2$ modes

abstract:
  We examine various scenarios that involve a light ${\cal O}(1 TeV)$
leptoquark state and select those which are compatible with the current
experimental values for $\mathcal{B}(B_s\to \mu\mu)$, $\mathcal{B}(B\to
K\mu\mu)_{\mathrm{large}-q^2}$, $R_K=\mathcal{B^\prime}(B\to
K\mu\mu)/\mathcal{B^\prime}(B\to Kee)$, and which lead to predictions
consistent with other experimental data. We show that two such scenarios are
phenomenologically plausible, namely the one with a doublet of scalar
leptoquarks of hypercharge $1/6$, and the one with a triplet of vector
leptoquarks of hypercharge $2/3$. We also argue that a model with a singlet
scalar leptoquark of hypercharge $1/3$ is not viable. Using the present
experimental data as constraints, it is shown that the exclusive lepton flavor
violating decays, $\mathcal{B}(B_s\to \mu\tau)$, $\mathcal{B}(B\to K \mu\tau)$
and $\mathcal{B}(B\to K^\ast \mu\tau)$, can be as large as
$\mathcal{O}(10^{-5})$.


title:
Being WISE II: Reducing the Influence of Star Formation History on the
  Mass-to-Light Ratio of Quiescent Galaxies

abstract:
  Stellar population synthesis models can now reproduce the photometry of old
stellar systems (age $>$ 2 Gyr) in the near-infrared (NIR) bands at 3.4 and
4.6$\mu$m (WISE W1 $\&$ W2 or IRAC 1 $\&$ 2). In this paper we derive stellar
mass-to-light ratios for these and optical bands, and confirm that the NIR M/L
shows dramatically reduced sensitivity to both age and metallicity compared to
optical bands, and further, that this behavior leads to significantly more
robust stellar masses for quiescent galaxies with [Fe/H] > -0.5 regardless of
star formation history (SFH). We then use realistic early-type galaxy SFHs and
metallicity distributions from the EAGLE simulations of galaxy formation to
investigate two methods to determine the appropriate M/L for a galaxy: 1) We
show that the uncertainties introduced by an unknown SFH can be largely removed
using a spectroscopically inferred luminosity-weighted age and metallicity for
the population to select the appropriate single stellar population (SSP)
equivalent M/L. Using this method, the maximum systematic error due to SFH on
the M/L of an early-type galaxy is $<$ 4$\%$ at 3.4 $\mu$m and typical
uncertainties due to errors in the age and metallicity create scatter of
$\lesssim$13$\%$. The equivalent values for optical bands are more than 2-3
times greater, even before considering uncertainties associated with internal
dust extinction. 2) We demonstrate that if the EAGLE SFHs and metallicities
accurately reproduce the true properties of early-type galaxies, the use of an
iterative approach to select a mass dependent M/L can provide even more
accurate stellar masses for early-type galaxies, with typical uncertainties $<$
9$\%$.


title:
First exploratory calculation of the long-distance contributions to the
  rare kaon decays $K\to\pi\ell^+\ell^-$

abstract:
  The rare decays of a kaon into a pion and a charged lepton/antilepton pair
proceed via a flavour changing neutral current and therefore may only be
induced beyond tree level in the Standard Model. This natural suppression makes
these decays sensitive to the effects of potential New Physics. The CP
conserving $K\to\pi \ell^+\ell^-$ decay channels however are dominated by a
single photon exchange; this involves a sizeable long-distance hadronic
contribution which represents the current major source of theoretical
uncertainty. Here we outline our methodology for the computation of the
long-distance contributions to these rare decay amplitudes using lattice QCD
and present the numerical results of the first exploratory studies of these
decays in which all but the disconnected diagrams are evaluated. The domain
wall fermion ensembles of the RBC and UKQCD collaborations are used, with a
pion mass of $M_{\pi}\sim 430\,\mathrm{MeV}$ and a kaon mass of $M_{K}\sim
625\,\mathrm{MeV}$. In particular we determine the form factor, $V(z)$, of the
$K^+\to\pi^+\ell^+\ell^-$ decay from the lattice at small values of
$z=q^2/M_{K}^{2}$, obtaining $V(z)=1.37(36),\, 0.68(39),\, 0.96(64)$ for the
three values of $z=-0.5594(12),\, -1.0530(34),\, -1.4653(82)$ respectively.


title:
Medipix3 Demonstration and understanding of near ideal detector
  performance for 60 & 80 keV electrons

abstract:
  In our article we report first quantitative measurements of imaging
performance for the current generation of hybrid pixel detector, Medipix3, as
direct electron detector. Utilising beam energies of 60 & 80 keV, measurements
of modulation transfer function (MTF) and detective quantum efficiency (DQE)
have revealed that, in single pixel mode (SPM), energy threshold values can be
chosen to maximize either the MTF or DQE, obtaining values near to, or even
exceeding, those for an ideal detector. We have demonstrated that the Medipix3
charge summing mode (CSM) can deliver simultaneous, near ideal values of both
MTF and DQE. To understand direct detection performance further we have
characterized the detector response to single electron events, building an
empirical model which can predict detector MTF and DQE performance based on
energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging
performance, recording a fully exposed electron diffraction pattern at 24-bit
depth and images in SPM and CSM modes. Taken together our findings highlight
that for transmission electron microscopy performed at low energies (energies
<100 keV) thick hybrid pixel detectors provide an advantageous and alternative
architecture for direct electron imaging


title: A note on extended Lorentzian recurrent manifolds

abstract:
  Extended recurrent pseudo-Riemannian manifolds were introduced by Mileva
Prvanovic'. We reconsider her work in the light of recent results and show that
the manifold is conformally flat, and it is a space of quasi-constant
curvature. We also show that an extended recurrent Lorentzian manifold, with
time-like associated covector, is a perfect fluid Robertson-Walker space-time.
We obtain the equation of state; in n = 4 and if the scalar curvature is zero,
a model for incoherent radiation is obtained.


title: Fast cycles detecting in non-linear discrete systems

abstract:
  In the paper below we consider a problem of stabilization of a priori unknown
unstable periodic orbits in non-linear autonomous discrete dynamical systems.
We suggest a generalization of a non-linear DFC scheme to improve the rate of
detecting T-cycles. Some numerical simulations are presented.


title:
An Einstein@home search for continuous gravitational waves from
  Cassiopeia A

abstract:
  We report the results of a directed search for continuous gravitational-wave
emission in a broad frequency range (between 50 and 1000 Hz) from the central
compact object of the supernova remnant Cassiopeia A (Cas A). The data comes
from the sixth science run of LIGO and the search is performed on the volunteer
distributed computing network Einstein@Home. We find no significant signal
candidate, and set the most constraining upper limits to date on the
gravitational-wave emission from Cas A, which beat the indirect age-based upper
limit across the entire search range. At around 170 Hz (the most sensitive
frequency range), we set 90% confidence upper limits on the gravitational wave
amplitude $h_0$ of $\sim\!\!~2.9\times 10^{-25}$, roughly twice as constraining
as the upper limits from previous searches on Cas A. The upper limits can also
be expressed as constraints on the ellipticity of Cas A; with a few reasonable
assumptions, we show that at gravitational-wave frequencies greater than
300~Hz, we can exclude an ellipticity of $\gtrsim\!\!~10^{-5}$.


title:
IBIC characterization of an ion-beam-micromachined multi-electrode
  diamond detector

abstract:
  Deep Ion Beam Lithography (DIBL) has been used for the direct writing of
buried graphitic regions in monocrystalline diamond with micrometric
resolution. Aiming at the development and the characterization of a fully
ion-beam-micromachined solid state ionization chamber, a device with
interdigitated electrodes was fabricated by using a 1.8 MeV He+ ion microbeam
scanning on a homoepitaxial, grown by chemical vapour deposition (CVD). In
order to evaluate the ionizing-radiation-detection performance of the device,
charge collection efficiency (CCE) maps were extracted from Ion Beam Induced
Charge (IBIC) measurements carried out by probing different arrangements of
buried microelectrodes. The analysis of the CCE maps allowed for an exhaustive
evaluation of the detector features, in particular the individuation of the
different role played by electrons and holes in the formation of the induced
charge pulses. Finally, a comparison of the performances of the detector with
buried graphitic electrodes with those relevant to conventional metallic
surface electrodes evidenced the formation of a dead layer overlying the buried
electrodes as a result of the fabrication process.


title:
Development and characterization of a diamond-insulated graphitic multi
  electrode array realized with ion beam lithography

abstract:
  The detection of quantal exocytic events from neurons and neuroendocrine
cells is a challenging task in neuroscience. One of the most promising
platforms for the development of a new generation of biosensors is diamond, due
to its biocompatibility, transparency and chemical inertness. Moreover, the
electrical properties of diamond can be turned from a perfect insulator into a
conductive material (resistivity Ohm cm) by exploiting the metastable nature of
this allotropic form of carbon. A 16 channels MEA (Multi Electrode Array)
suitable for cell culture growing has been fabricated by means of ion
implantation. A focused 1.2 MeV He+ beam was scanned on a IIa single-crystal
diamond sample (4.5x4.5x0.5 mm3) to cause highly damaged sub-superficial
structures that were defined with micrometric spatial resolution. After
implantation, the sample was annealed. This process provides the conversion of
the sub-superficial highly damaged regions to a graphitic phase embedded in a
highly insulating diamond matrix. Thanks to a three-dimensional masking
technique, the endpoints of the sub-superficial channels emerge in contact with
the sample surface, therefore being available as sensing electrodes. Cyclic
voltammetry and amperometry measurements of solutions with increasing
concentrations of adrenaline were performed to characterize the biosensor
sensitivity. The reported results demonstrate that this new type of biosensor
is suitable for in vitro detection of catecholamine release.


title:
A refined approach for non-negative entire solutions of $\Delta u + u^p
  = 0$ with subcritical Sobolev growth

abstract:
  Let $N\geq 2$ and $1 < p < (N+2)/(N-2)_{+}$. Consider the Lane-Emden equation
$\Delta u + u^p = 0$ in $\mathbb{R}^N$ and recall the classical Liouville type
theorem: if $u$ is a non-negative classical solution of the Lane-Emden
equation, then $u \equiv 0$. The method of moving planes combined with the
Kelvin transform provides an elegant proof of this theorem. A classical
approach of J. Serrin and H. Zou, originally used for the Lane-Emden system,
yields another proof but only in lower dimensions. Motivated by this, we
further refine this approach to find an alternative proof of the Liouville type
theorem in all dimensions.


title: Magnetic properties of the honeycomb oxide Na$_2$Co$_2$TeO$_6$

abstract:
  We have studied the magnetic properties of Na$_2$Co$_2$TeO$_6$, which
features a honeycomb lattice of magnetic Co$^{2+}$ ions, through macroscopic
characterization and neutron diffraction on a powder sample. We have shown that
this material orders in a zig-zag antiferromagnetic structure. In addition to
allowing a linear magnetoelectric coupling, this magnetic arrangement displays
very peculiar spatial magnetic correlations, larger in the honeycomb planes
than between the planes, which do not evolve with the temperature. We have
investigated this behavior by Monte Carlo calculations using the
$J_1$-$J_2$-$J_3$ model on a honeycomb lattice with a small interplane
interaction. Our model reproduces the experimental neutron structure factor,
although its absence of temperature evolution must be due to additional
ingredients, such as chemical disorder or quantum fluctuations enhanced by the
proximity to a phase boundary.