title:
Anytime Bi-Objective Optimization with a Hybrid Multi-Objective CMA-ES
  (HMO-CMA-ES)

abstract:
  We propose a multi-objective optimization algorithm aimed at achieving good
anytime performance over a wide range of problems. Performance is assessed in
terms of the hypervolume metric. The algorithm called HMO-CMA-ES represents a
hybrid of several old and new variants of CMA-ES, complemented by BOBYQA as a
warm start. We benchmark HMO-CMA-ES on the recently introduced bi-objective
problem suite of the COCO framework (COmparing Continuous Optimizers),
consisting of 55 scalable continuous optimization problems, which is used by
the Black-Box Optimization Benchmarking (BBOB) Workshop 2016.


title: Calabi-Yau structures on topological Fukaya categories

abstract:
  We develop a local-to-global formalism for constructing Calabi-Yau structures
for global sections of constructible sheaves or cosheaves of categories. The
required data - an isomorphism of the sheafified Hochschild homology with the
topological dualizing sheaf - specializes to the classical notion of
orientation when applied to the category of local systems on a manifold. We
apply this construction to the cosheaves on arboreal skeleta arising in the
microlocal approach to the A-model.


title:
The Kinematic Sunyaev-Zel'dovich Effect with Projected Fields II:
  prospects, challenges, and comparison with simulations

abstract:
  The kinematic Sunyaev-Zel'dovich (kSZ) signal is a powerful probe of the
cosmic baryon distribution. The kSZ signal is proportional to the integrated
free electron momentum rather than the electron pressure (which sources the
thermal SZ signal). Since velocities should be unbiased on large scales, the
kSZ signal is an unbiased tracer of the large-scale electron distribution, and
thus can be used to detect the "missing baryon" that evade most observational
techniques. While most current methods for kSZ extraction rely on the
availability of very accurate redshifts, we revisit a method that allows
measurements even in the absence of redshift information for individual
objects. It involves cross-correlating the square of an appropriately filtered
cosmic microwave background (CMB) temperature map with a projected density map
constructed from a sample of large-scale structure tracers. We show that this
method will achieve high signal-to-noise when applied to the next generation of
high-resolution CMB experiments, provided that component separation is
sufficiently effective at removing foreground contamination. Considering
statistical errors only, we forecast that this estimator can yield $S/N \approx
$ 3, 120 and over 150 for Planck, Advanced ACTPol, and hypothetical Stage-IV
CMB experiments, respectively, in combination with a galaxy catalog from WISE,
and about 20% larger $S/N$ for a galaxy catalog from the proposed SPHEREx
experiment. This work serves as a companion paper to the first kSZ measurement
with this method, where we used CMB temperature maps constructed from Planck
and WMAP data, together with galaxies from the WISE survey, to obtain a 3.8 -
4.5$\sigma$ detection of the kSZ$^2$ amplitude.


title:
Representation of the Dirac delta function in $\mathcal{C}(R^{\infty})$
  in terms of infinite-dimensional Lebesgue measures

abstract:
  A representation of the Dirac delta function in $ \mathcal{C}(R^{\infty})$ in
terms of infinite-dimensional Lebesgue measures in $R^{\infty}$ is obtained and
some it's properties are studied in this paper.


title:
A Stochastic Closure for Two-Moment Bulk Microphysics of Warm Clouds:
  Part II, Validation

abstract:
  The representation of clouds and associated processes of rain and snow
formation remains one of the major uncertainties in climate and weather
prediction models. In a companion paper (Part I), we systematically derived a
two moment bulk cloud microphysics model for collision and coalescence in warm
rain based on the kinetic coalescence equation (KCE) and used stochastic
approximations to close the higher order moment terms, and do so independently
of the collision kernel. Conservation of mass and consistency of droplet number
concentration of the evolving cloud properties were combined with numerical
simulations to reduce the parametrization problem to three key parameters.
  Here, we constrain these three parameters based on the physics of collision
and coalescence resulting in a "region of validity." Furthermore, we
theoretically validate the new bulk model by deriving a subset of the "region
of validity" that contains stochastic parameters that skillfully reproduces an
existing model based on an a priori droplet size distribution by Seifert and
Beheng (2001). The stochastic bulk model is empirically validated against this
model, and parameter values that faithfully reproduce detailed KCE results are
identified.
  Furthermore, sensitivity tests indicate that the stochastically derived model
can be used with a time step as large as 30 seconds without significantly
compromising accuracy, which makes it very attractive to use in medium to long
range weather prediction models. These results can be explored in the future to
select parameters in the "region of validity" that are conditional on
environmental conditions and the age of the cloud.


title: Unifying Dynamical and Structural Stability of Equilibriums

abstract:
  We exhibit a fundamental relationship between measures of dynamical and
structural stability of equilibriums, arising from real dynamical systems. We
show that dynamical stability, quantified via systems local response to
external perturbations, coincides with the minimal internal perturbation able
to destabilize the equilibrium. First, by reformulating a result of control
theory, we explain that harmonic external perturbations reflect the spectral
sensitivity of the Jacobian matrix at the equilibrium, with respect to constant
changes of its coefficients. However, for this equivalence to hold, imaginary
changes of the Jacobian's coefficients have to be allowed. The connection with
dynamical stability is thus lost for real dynamical systems. We show that this
issue can be avoided, thus recovering the fundamental link between dynamical
and structural stability, by considering stochastic noise as external and
internal perturbations. More precisely, we demonstrate that a system's local
response to white-noise perturbations directly reflects the intensity of
internal white noise that it can accommodate before asymptotic mean-square
stability of the equilibrium is lost.


title: K-essence in Horndeski models

abstract:
  In this paper, we investigate a simple class of Horndeski models where the
scalar field plays the role of a k-essence fluid. We present several solutions
for early-time universe, namely inflation and cosmological bounce, by making
use of some reconstruction technique. Moreover, we furnish the formalism to
calculate perturbations in FRW space-time and we compute the spectral index and
the tensor-to-scalar ratio during inflation.


title: Good variation theory: a tauberian approach to the Riemann Hypothesis

abstract:
  In this short note I present a tauberian conjecture that I consider to be the
simplest and the best tauberian reformulation of RH using good variation
theory. The method applies also to the Grand Riemann Hypothesis.


title:
Integrals and Series Representations of $q$-Polynomials and Functions:
  Part II Schur Polynomials and the Rogers-Ramanujan Identities

abstract:
  We give several expansion and identities involving the Ramanujan function
$A_q$ and the Stieltjes--Wigert polynomials. Special values of our idenitities
give $m$-versions of some of the items on the Slater list of Rogers-Ramanujan
type identities. We also study some bilateral extensions of certain
transformations in the theory of basic hypergeometric functions.


title:
The Effect of Features on the Functional Form of the Scalar Power
  Spectrum

abstract:
  We study how the scalar power spectrum of single-scalar inflation depends
functionally on models with features which have been proposed to explain
anomalies in the data. We exploit a new formalism based on evolving the
norm-squared of the scalar mode functions, rather than the mode functions
themselves.


title: Onto Interpolating Sequences for the Dirichlet Space

abstract:
  We describe two new classes of onto interpolating sequences for the Dirichlet
space, in particular resolving a question of Bishop. We also give a complete
description of the analogous sequences for a discrete model of the Dirichlet
space.


title: Imaging Extrasolar Giant Planets

abstract:
  High-contrast adaptive optics imaging is a powerful technique to probe the
architectures of planetary systems from the outside-in and survey the
atmospheres of self-luminous giant planets. Direct imaging has rapidly matured
over the past decade and especially the last few years with the advent of
high-order adaptive optics systems, dedicated planet-finding instruments with
specialized coronagraphs, and innovative observing and post-processing
strategies to suppress speckle noise. This review summarizes recent progress in
high-contrast imaging with particular emphasis on observational results,
discoveries near and below the deuterium-burning limit, and a practical
overview of large-scale surveys and dedicated instruments. I conclude with a
statistical meta-analysis of deep imaging surveys in the literature. Based on
observations of 384 unique and single young ($\approx$5--300~Myr) stars
spanning stellar masses between 0.1--3.0~\Msun, the overall occurrence rate of
5--13~\Mjup \ companions at orbital distances of 30--300~AU is
0.6$^{+0.7}_{-0.5}$\% assuming hot-start evolutionary models. The most massive
giant planets regularly accessible to direct imaging are about as rare as hot
Jupiters are around Sun-like stars. Dividing this sample into individual
stellar mass bins does not reveal any statistically-significant trend in planet
frequency with host mass: giant planets are found around 2.8$^{+3.7}_{-2.3}$\%
of BA stars, $<$4.1\% of FGK stars, and $<$3.9\% of M dwarfs. Looking forward,
extreme adaptive optics systems and the next generation of ground- and
space-based telescopes with smaller inner working angles and deeper detection
limits will increase the pace of discovery to ultimately map the demographics,
composition, evolution, and origin of planets spanning a broad range of masses
and ages.


title: Protostars at Low Extinction in Orion A

abstract:
  In the list of young stellar objects compiled by Megeath et al. (2012) for
the Orion A molecular cloud, only 44 out of 1208 sources found projected onto
low extinction (Ak<0.8 mag) gas are identified as protostars. These objects are
puzzling because protostars are not typically expected to be associated with
extended low extinction material. Here, we use high resolution extinction maps
generated from Herschel data, optical/infrared and Spitzer Space Telescope
photometry and spectroscopy of the low extinction protostellar candidate
sources to determine if they are likely true protostellar sources or
contaminants. Out of 44 candidate objects, we determine that 10 sources are
likely protostars, with the rest being more evolved young stellar objects (18),
galaxies (4), false detections of nebulosity and cloud edges (9), or real
sources for which more data are required to ascertain their nature (3). We find
none of the confirmed protostars to be associated with recognizable dense cores
and we briefly discuss possible origins for these orphaned objects.


title: Transport of Correlations in a Harmonic Chain

abstract:
  We study the propagation of different types of correlations through a quantum
bus formed by a chain of coupled harmonic oscillators. This includes steering,
entanglement, mutual information, quantum discord, and Bell-like nonlocality.
The whole system consists of the quantum bus (propagation medium) and other
quantum harmonic oscillators (sources and receivers of quantum correlations)
weakly coupled to the chain. We are particularly interested in using the point
of view of transport to spot distinctive features displayed by different kinds
of correlations. We found, for instance, that there are fundamental differences
in the way steering and discord propagate, depending on the way they are
defined with respect to the parties involved in the initial correlated state.
We analyzed both the closed- and open-system dynamics as well as the role
played by thermal excitations in the propagation of the correlations.


title:
Response Properties of Axion Insulators and Weyl Semimetals Driven by
  Screw Dislocations and Dynamical Axion Strings

abstract:
  In this paper, we investigate the theory of dynamical axion string emerging
from chiral symmetry breaking in three-dimensional Weyl semimetals. The chiral
symmetry is spontaneously broken by a charge density wave (CDW) order which
opens an energy gap and converts the Weyl semimetal into an axion insulator.
Indeed, the phase fluctuations of the CDW order parameter act as a dynamical
axion field $\theta({\vec{x}},t)$ and couples to electromagnetic field via
$\mathcal{L}_{\theta}=\frac{\theta(\vec{x},t)}{32\pi^2}
\epsilon^{\sigma\tau\nu\mu} F_{\sigma\tau} F_{\nu\mu}.$ Additionally, when the
axion insulator is coupled to the background geometry/strain fields via
torsional defects, i.e., screw dislocations, there is a novel interplay between
the crystal dislocations and dynamical axion strings (i.e., vortices of the CDW
order parameter). For example, the screw dislocation traps axial charge, and
there is a Berry phase accumulation when an axion string is braided with a
screw dislocation. In addition, a cubic coupling between the axial current and
the geometry fields is non-vanishing and indicates a Berry phase accumulation
during a particular three-loop braiding procedure where a dislocation loop is
braided with another dislocation and they are both threaded by an axion string.
We also observe a chiral magnetic effect induced by a screw dislocation density
in the absence of chemical potential imbalance between Weyl points and describe
an additional chiral geometric effect and a geometric Witten effect.


title: Radiation feedback in dusty clouds

abstract:
  We have investigated the impact of photoionization and radiation pressure on
a dusty star-forming cloud using one-dimensional radiation hydrodynamic
simulations, which include absorption and re-emission of photons by dust. We
find that, in a cloud of mass 10^5 Msun and radius 17 pc, the effect of
radiation pressure is negligible when star formation efficiency is 2%. The
importance of radiation pressure increases with increasing star formation
efficiency or an increasing dust-to-gas mass ratio. The net effect of radiation
feedback, however, becomes smaller with the increasing dust-to-gas mass ratio,
since the absorption of ultra-violet photons by dust grains suppresses
photoionization and hence photoheating.


title:
The evolution in the stellar mass of Brightest Cluster Galaxies over the
  past 10 billion years

abstract:
  Using a sample of 98 galaxy clusters recently imaged in the near infra-red
with the ESO NTT, WIYN and WHT telescopes, supplemented with 33 clusters from
the ESO archive, we measure how the stellar mass of the most massive galaxies
in the universe, namely Brightest Cluster Galaxies (BCG), increases with time.
Most of the BCGs in this new sample lie in the redshift range $0.2<z<0.6$,
which has been noted in recent works to mark an epoch over which the growth in
the stellar mass of BCGs stalls. From this sample of 132 clusters, we create a
subsample of 102 systems that includes only those clusters that have estimates
of the cluster mass. We combine the BCGs in this subsample with BCGs from the
literature, and find that the growth in stellar mass of BCGs from 10 billion
years ago to the present epoch is broadly consistent with recent semi-analytic
and semi-empirical models. As in other recent studies, tentative evidence
indicates that the stellar mass growth rate of BCGs may be slowing in the past
3.5 billion years. Further work in collecting larger samples, and in better
comparing observations with theory using mock images is required if a more
detailed comparison between the models and the data is to be made.


title: Factorization and Resummation for Jet Processes

abstract:
  From a detailed analysis of cone-jet cross sections in effective field
theory, we obtain novel factorization theorems which separate the physics
associated with different energy scales present in such processes. The relevant
low-energy physics is encoded in Wilson lines along the directions of the
energetic particles inside the jets. This multi-Wilson-line structure is
present even for narrow-cone jets due to the relevance of small-angle soft
radiation. We discuss the renormalization-group equations satisfied by these
operators. Their solution resums all logarithmically enhanced contributions to
such processes, including non-global logarithms. Such logarithms arise in many
observables, in particular whenever hard phase-space constraints are imposed,
and are not captured with standard resummation techniques. Our formalism
provides the basis for higher-order logarithmic resummations of jet and other
non-global observables. As a nontrivial consistency check, we use it to obtain
explicit two-loop results for all logarithmically enhanced terms in cone-jet
cross sections and verify those against numerical fixed-order computations.


title: Intergalactic Lyman continuum photon budget in the past 5 billion years

abstract:
  We constrain the H I photoionization rate $(\Gamma_{\rm HI})$ at $z \lesssim
0.45$ by comparing the flux probability distribution function and power
spectrum of the Ly-$\alpha$ forest data along 82 QSO sightlines obtained using
Cosmic Origins Spectrograph with models generated from smoothed particle
hydrodynamic simulations. We have developed a module named "Code for Ionization
and Temperature Evolution (CITE)" for calculating the intergalactic medium
(IGM) temperature evolution from high to low redshifts by post-processing the
GADGET-2 simulation outputs. Our method, that produces results consistent with
other simulations, is computationally less expensive thus allowing us to
explore a large parameter space. It also allows rigorous estimation of the
error covariance matrix for various statistical quantities of interest. We find
that the best-fit $\Gamma_{\rm HI}(z)$ increases with $z$ and follows $(4 \pm
0.1) \times 10^{-14}\:(1+z)^{4.99 \pm 0.12}$ s$^{-1}$. At any given $z$ the
typical uncertainties $\Delta \Gamma_{\rm HI} / \Gamma_{\rm HI}$ are $\sim 25$
per cent which contains not only the statistical errors but also those arising
from possible degeneracy with the thermal history of the IGM and cosmological
parameters and uncertainties in fitting the QSO continuum. These values of
$\Gamma_{\rm HI}$ favour the scenario where only QSOs contribute to the
ionizing background at $z<2$. Our derived $3\sigma$ upper limit on average
escape fraction is $0.008$, consistent with measurements of low-$z$ galaxies.


title:
Cos(4 phi) azimuthal anisotropy in small-x DIS dijet production beyond
  the leading power TMD limit

abstract:
  We determine the first correction to the quadrupole operator in high-energy
QCD beyond the TMD limit of Weizsaecker-Williams and linearly polarized gluon
distributions. These functions give rise to isotropic resp. ~ cos 2 phi angular
distributions in DIS dijet production. On the other hand, the correction
produces a ~ cos 4 phi angular dependence which is suppressed by one additional
power of the dijet transverse momentum scale (squared) P^2.


title: Joint transverse momentum and threshold resummation beyond NLL

abstract:
  To describe the transverse momentum spectrum of heavy color-singlet
production, the joint resummation of threshold and transverse momentum
logarithms is investigated. We obtain factorization theorems for various
kinematic regimes valid to all orders in the strong coupling, using
Soft-Collinear Effective Theory. We discuss how these enable resummation and
how to combine regimes. The new ingredients in the factorization theorems are
calculated at next-to-leading order, and a range of consistency checks is
performed. Our framework goes beyond the current next-to-leading logarithmic
accuracy (NLL).


title:
The Chandra Galactic Bulge Survey: optical catalogue and point-source
  counterparts to X-ray sources

abstract:
  As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue of
optical sources in the GBS footprint. This consists of two regions centered at
Galactic latitude b = 1.5 degrees above and below the Galactic Centre, spanning
(l x b) = (6x1) degrees. The catalogue consists of 2 or more epochs of
observations for each line of sight in r', i' and H{\alpha} filters. It is
complete down to r' = 20.2 and i' = 19.2 mag; the mean 5{\sigma} depth is r' =
22.5 and i' = 21.1 mag. The mean root-mean-square residuals of the astrometric
solutions is 0.04 arcsec. We cross-correlate this optical catalogue with the
1640 unique X-ray sources detected in Chandra observations of the GBS area, and
find candidate optical counterparts to 1480 X-ray sources. We use a false alarm
probability analysis to estimate the contamination by interlopers, and expect ~
10 per cent of optical counterparts to be chance alignments. To determine the
most likely counterpart for each X-ray source, we compute the likelihood ratio
for all optical sources within the 4{\sigma} X-ray error circle. This analysis
yields 1480 potential counterparts (~ 90 per cent of the sample). 584
counterparts have saturated photometry (r'<17, i'<16), indicating these objects
are likely foreground sources and the real counterparts. 171 candidate
counterparts are detected only in the i'-band. These sources are good qLMXB and
CV candidates as they are X-ray bright and likely located in the Bulge.


title:
Data-driven Model-independent Searches for Long-lived Particles at the
  LHC

abstract:
  Neutral long-lived particles (LLPs) are highly motivated by many BSM
scenarios, such as theories of supersymmetry, baryogenesis, and neutral
naturalness, and present both tremendous discovery opportunities and
experimental challenges for the LHC. A major bottleneck for current LLP
searches is the prediction of SM backgrounds, which are often impossible to
simulate accurately. In this paper, we propose a general strategy for obtaining
differential, data-driven background estimates in LLP searches, thereby notably
extending the range of LLP masses and lifetimes that can be discovered at the
LHC. We focus on LLPs decaying in the ATLAS Muon System, where triggers
providing both signal and control samples are available at the LHC Run-2. While
many existing searches require two displaced decays, a detailed knowledge of
backgrounds will allow for very inclusive searches that require just one
detected LLP decay. As we demonstrate for the $h \to X X$ signal model of LLP
pair production in exotic Higgs decays, this results in dramatic sensitivity
improvements for proper lifetimes $\gtrsim 10$ m. In theories of Neutral
Naturalness, this extends reach to glueball masses far below the $\bar b b$
threshold. Our strategy readily generalizes to other signal models, and other
detector subsystems. This framework therefore lends itself to the development
of a systematic, model-independent LLP search program, in analogy to the highly
successful simplified-model framework of prompt searches.


title: TeV-scale Pseudo-Dirac Seesaw Mechanisms in an E$_6$ Inspired Model

abstract:
  TeV-scale seesaw mechanisms are interesting due to their potential
testability at existing collider experiments. Herein we propose an
E$_6$-inspired model allowing a TeV-scale pseudo-Dirac singlet neutrino seesaw
mechanism with naturally sizeable Yukawa couplings of $\mathcal{O}(10^{-2})$.
The model also contains new U(1) gauge interactions (and associated $Z^\prime$
bosons with which the singlet neutrinos can be produced at colliders),
typically long-lived colour triplet fermions, SU(2) doublet fermions, and a
complex scalar - potentially all at the TeV-scale. Additionally we identify
three possible explanations for the 750 GeV di-photon excess.


title:
Dust and gas density evolution at a radial pressure bump in
  protoplanetary disks

abstract:
  We investigate the simultaneous evolution of dust and gas density profiles at
a radial pressure bump located in a protoplanetary disk. If dust particles are
treated as test particles, a radial pressure bump traps dust particles that
drift radially inward. As the dust particles become more concentrated at the
gas pressure bump, however, the drag force from dust to gas (back-reaction),
which is ignored in a test-particle approach, deforms the pressure bump. We
find that the pressure bump is completely deformed by the back-reaction when
the dust-to-gas mass ratio reaches $\sim 1$ for a slower bump restoration. The
direct gravitational instability of dust particles is inhibited by the bump
destruction. In the dust-enriched region, the radial pressure support becomes
$\sim 10-100$ times lower than the global value set initially. Although the
pressure bump is a favorable place for streaming instability (SI), the
flattened pressure gradient inhibits SI from forming large particle clumps
corresponding to $100-1000$ km sized bodies, which has been previously
proposed. If SI occurs there, the dust clumps formed would be $10-100$ times
smaller, that is, of about $1 - 100$ km.


title: An exact limit of ABJM

abstract:
  We study planar ABJM in a limit where one coupling is negligible compared to
the other. We provide a recipe for exactly solving the expectation value of
bosonic BPS Wilson loops on arbitrary smooth contours, or the leading
divergence for cusped ones, using results from localization. As an application,
we compute the exact (generalized) cusp anomalous dimension and Bremsstrahlung
function and use it to determine the interpolating $h$-function. We finally
prove a conjecture on the exact form of the dilatation operator in a closed
sector, hinting at the integrability of this limit.


title:
Gas Loss by Ram Pressure Stripping and Internal Feedback From Low Mass
  Milky Way Satellites

abstract:
  The evolution of dwarf satellites of the Milky Way is affected by the
combination of ram pressure and tidal stripping, and internal feedback from
massive stars. We investigate gas loss processes in the smallest satellites of
the Milky Way using three-dimensional, high resolution, idealized wind tunnel
simulations, accounting for gas loss through both ram pressure stripping and
expulsion by supernova feedback. Using initial conditions appropriate for a
dwarf galaxy like Leo T, we investigate whether or not environmental gas
stripping and internal feedback can quench these low mass galaxies on the
expected timescales, shorter than 2 Gyr. We find that supernova feedback
contributes negligibly to the stripping rate for these low star formation rate
galaxies. However, we also find that ram pressure stripping is less efficient
than expected in the stripping scenarios we consider. Our work suggests that,
although ram pressure stripping can eventually completely strip these galaxies,
other physics is likely at play to reconcile our computed stripping times with
the rapid quenching timescales deduced from observations of low mass Milky Way
dwarf galaxies. We discuss the roles additional physics may play in this
scenario, including host-satellite tidal interactions, cored vs. cuspy dark
matter profiles, reionization, and satellite pre-processing. We conclude that a
proper accounting of these physics together is necessary to understand the
quenching of low mass Milky Way satellites.


title: Efficient state initialization by a quantum spectral filtering algorithm

abstract:
  An algorithm that initializes a quantum register to a state with a specified
energy range is given, corresponding to a quantum implementation of the
celebrated Feit-Fleck method. This is performed by introducing a
nondeterministic quantum implementation of a standard spectral filtering
procedure combined with an apodization technique, allowing for accurate state
initialization. It is shown that the implementation requires only two ancilla
qubits. A lower bound for the total probability of success of this algorithm is
derived, showing that this scheme can be realized using a finite, relatively
low number of trials. Assuming the time evolution can be performed efficiently
and using a trial state polynomially close to the desired states, it is
demonstrated that the number of operations required scales polynomially with
the number of qubits. Tradeoffs between accuracy and performance are
demonstrated in a simple example: the harmonic oscillator. This algorithm would
be useful for the initialization phase of the simulation of quantum systems on
digital quantum computers.


title: Weyl Consistency Conditions in Non-Relativistic Quantum Field Theory

abstract:
  Weyl consistency conditions have been used in unitary relativistic quantum
field theory to impose constraints on the renormalization group flow of certain
quantities. We classify the Weyl anomalies and their renormalization scheme
ambiguities for generic non-relativistic theories in 2+1 dimensions with
anisotropic scaling exponent z=2; the extension to other values of z are
discussed as well. We give the consistency conditions among these anomalies. As
an application we find several candidates for a C-theorem. We comment on
possible candidates for a $C$-theorem in higher dimensions.


title: Highly variable AGN from the XMM-Newton Slew Survey

abstract:
  We investigate the properties of a variability-selected complete sample of
AGN in order to identify the mechanisms which cause large amplitude X-ray
variability on time scales of years. A complete sample of 24 sources was
constructed, from AGN which changed their soft X-ray luminosity by more than
one order of magnitude over 5--20 years between ROSAT observations and the XMM
Slew Survey. Follow-up observations were obtained with the Swift satellite.
After removal of two probable spurious sources, we find that the sample has
global properties which differ little from a non-varying control sample drawn
from the wider XMM-Slew/ROSAT/Veron sample of all secure AGN detections. A wide
range of AGN types are represented in the varying sample. The black hole mass
distributions for the varying and non-varying sample are not significantly
different. This suggests that long timescale variability is not strongly
affected by black hole mass. There is marginal evidence that the variable
sources have a lower redshift (2$\sigma$) and X-ray luminosity (1.7$\sigma$).
Apart from two radio-loud sources, the sample have normal optical-X-ray ratios
($\alpha_{\rm OX}$) when at their peak but are X-ray weak during their lowest
flux measurements. Drawing on our results and other studies, we are able to
identify a variety of variability mechanisms at play: tidal disruption events,
jet activity, changes in absorption, thermal emission from the inner accretion
disc, and variable accretion disc reflection. Little evidence for strong
absorption is seen in the majority of the sample and single-component
absorption can be excluded as the mechanism for most sources.


title: Dual approach to circuit quantization using loop charges

abstract:
  The conventional approach to circuit quantization is based on node fluxes and
traces the motion of node charges on the islands of the circuit. However, for
some devices, the relevant physics can be best described by the motion of
polarization charges over the branches of the circuit that are in general
related to the node charges in a highly nonlocal way. Here, we present a
method, dual to the conventional approach, for quantizing planar circuits in
terms of loop charges. In this way, the polarization charges are directly
obtained as the differences of the two loop charges on the neighboring loops.
The loop charges trace the motion of fluxes through the circuit loops. We show
that loop charges yield a simple description of the flux transport across
phase-slip junctions. We outline a concrete construction of circuits based on
phase-slip junctions that are electromagnetically dual to arbitrary planar
Josephson junction circuits. We argue that loop charges also yield a simple
description of the flux transport in conventional Josephson junctions shunted
by large impedances. We show that a mixed circuit description in terms of node
fluxes and loop charges yields an insight into the flux decompactification of a
Josephson junction shunted by an inductor. As an application, we show that the
fluxonium qubit is well approximated as a phase-slip junction for the
experimentally relevant parameters. Moreover, we argue that the $0$-$\pi$ qubit
is effectively the dual of a Majorana Josephson junction.


title: Quantum tunneling from paths in complex time

abstract:
  We study quantum mechanical tunneling using complex solutions of the
classical field equations. Simple visualization techniques allow us to unify
and generalize previous treatments, and straightforwardly show the connection
to the standard approach using Euclidean instanton solutions. We demonstrate
that the negative modes of solutions along various contours in the complex time
plane reveal which paths give the leading contribution to tunneling and which
do not, and we provide a criterion for identifying the negative modes. Central
to our approach is the solution of the background and perturbation equations
not only along a single path, but over an extended region of the complex time
plane. Our approach allows for a fully continuous and coherent treatment of
classical evolution interspersed by quantum tunneling events, and is applicable
in situations where singularities are present and also where Euclidean
solutions might not exist.


title:
Non-hyperbolic Iterated Function Systems: attractors and stationary
  measures

abstract:
  We consider iterated function systems $\mathrm{IFS}(T_1,\dots,T_k)$
consisting of continuous self maps of a compact metric space $X$. We introduce
the subset $S_{\mathrm{t}}$ of {\emph{weakly hyperbolic sequences}}
$\xi=\xi_0\ldots\xi_n \ldots \in \Sigma_k^+$ having the property that
$\bigcap_n T_{\xi_{0}}\circ\cdots\circ T_{\xi_{n}}(X)$ is a point
$\{\pi(\xi)\}$. The target set $\pi(S_{\mathrm{t}})$ plays a role similar to
the semifractal introduced by Lasota-Myjak.
  Assuming that $S_{\mathrm{t}}\ne \emptyset$ (the only hyperbolic-like
condition we assume) we prove that the IFS has at most one strict attractor and
we state a sufficient condition guaranteeing that the strict attractor is the
closure of the target set. Our approach applies to a large class of genuinely
non-hyperbolic IFSs (e.g. with maps with expanding fixed points) and provides a
necessary and sufficient condition for the existence of a globally attracting
fixed point of the Barnsley-Hutchinson operator. We provide sufficient
conditions under which the disjunctive chaos game yields the target set (even
when it is not a strict attractor).
  We state a sufficient condition for the asymptotic stability of the Markov
operator of a recurrent IFS. For IFSs defined on $[0,1]$ we give a simple
condition for their asymptotic stability. In the particular case of IFSs with
probabilities satisfying a "locally injectivity" condition, we prove that if
the target set has at least two elements then the Markov operator is
asymptotically stable and its stationary measure is supported in the closure of
the target set.


title: Estimating the number of communities in a network

abstract:
  Community detection, the division of a network into dense subnetworks with
only sparse connections between them, has been a topic of vigorous study in
recent years. However, while there exist a range of powerful and flexible
methods for dividing a network into a specified number of communities, it is an
open question how to determine exactly how many communities one should use.
Here we describe a mathematically principled approach for finding the number of
communities in a network using a maximum-likelihood method. We demonstrate the
approach on a range of real-world examples with known community structure,
finding that it is able to determine the number of communities correctly in
every case.


title:
Analysis of Two-State Folding Using Parabolic Approximation III:
  Non-Arrhenius Kinetics of FBP28 WW Part-I

abstract:
  A model which treats the denatured and the native conformers as being
confined to harmonic Gibbs energy wells has been used to analyse the
non-Arrhenius behaviour of spontaneously folding fixed two-state systems. The
results demonstrate that when pressure and solvent are constant: (i) a
two-state system is physically defined only for a finite temperature range;
(ii)irrespective of the primary sequence, the 3-dimensional structure of the
native conformer, the residual structure in the denatured state, and the
magnitude of the folding and unfolding rate constants, the equilibrium
stability of a two-state system is a maximum when its denatured conformers bury
the least amount of solvent accessible surface area (SASA) to reach the
activated state; (iii) the Gibbs barriers to folding and unfolding are not
always due to the incomplete compensation of the activation enthalpies and
entropies; (iv) the difference in heat capacity between the reaction-states is
due to both the size of the solvent-shell and the noncovalent interactions; (v)
the position of the transition state ensemble along the reaction coordinate
(RC) depends on the choice of the RC; and (vi) the atomic structure of the
transiently populated reaction-states cannot be inferred from
perturbation-induced changes in their energetics.


title: Local cohomology of Du Bois singularities and applications to families

abstract:
  In this paper we study the local cohomology modules of Du Bois singularities.
Let $(R,m)$ be a local ring, we prove that if $R_{red}$ is Du Bois, then
$H_m^i(R)\to H_m^i(R_{red})$ is surjective for every $i$. We find many
applications of this result. For example we answer a question of Kov\'acs and
the second author on the Cohen-Macaulay property of Du Bois singularities. We
obtain results on the injectivity of $Ext$ that provide substantial partial
answers of questions of Eisenbud-Mustata-Stillman in characteristic $0$, and
these results can be viewed as generalizations of the Kodaira vanishing theorem
for Cohen-Macaulay Du Bois varieties. We prove results on the set-theoretic
Cohen-Macaulayness of the defining ideal of Du Bois singularities, which are
characteristic $0$ analog of results of Singh-Walther and answer some of their
questions. We extend results of Hochster-Roberts on the relation between Koszul
cohomology and local cohomology for $F$-injective and Du Bois singularities,
see Hochster-Roberts. We also prove that singularities of dense $F$-injective
type deform.


title:
Factoring with Qutrits: Shor's Algorithm on Ternary and Metaplectic
  Quantum Architectures

abstract:
  We determine the cost of performing Shor's algorithm for integer
factorization on a ternary quantum computer, using two natural models of
universal fault-tolerant computing:
  (i) a model based on magic state distillation that assumes the availability
of the ternary Clifford gates, projective measurements, classical control as
its natural instrumentation set; (ii) a model based on a metaplectic
topological quantum computer (MTQC). A natural choice to implement Shor's
algorithm on a ternary quantum computer is to translate the entire arithmetic
into a ternary form. However, it is also possible to emulate the standard
binary version of the algorithm by encoding each qubit in a three-level system.
We compare the two approaches and analyze the complexity of implementing Shor's
period finding function in the two models. We also highlight the fact that the
cost of achieving universality through magic states in MTQC architecture is
asymptotically lower than in generic ternary case.


title:
Highly Non-linear and Reliable Amorphous Silicon Based Back-to-Back
  Schottky Diode as Selector Device for Large Scale RRAM Arrays

abstract:
  In this work we present silicon process compatible, stable and reliable
($>10^{8}$cycles), high non-linearity ratio at half-read voltage ($>5\times
10^{5}$), high speed ($<60ns$) low operating voltage ($<2V$) back-to-back
Schottky diodes. Materials choice of electrode, thickness of semiconductor
layer and doping level are investigated by numerical simulation, experiments
and current-voltage equations to give a general design consideration when
back-to-back Schottky diodes are used as selector device for Resistive Random
Access Memory(RRAM) arrays.


title: Stallings folds for CAT(0) cube complexes and quasiconvex subgroups

abstract:
  We describe a higher dimensional analogue of the Stallings folding sequence
for group actions on CAT(0) cube complexes. We use it to give a
characterization of quasiconvex subgroups of hyperbolic groups which act
properly co-compactly on CAT(0) cube complexes via finiteness properties of
their hyperplane stabilizers.


title:
A stringent limit on the amplitude of Alfv\'enic perturbations in
  high-beta low-collisionality plasmas

abstract:
  It is shown that low-collisionality plasmas cannot support linearly polarized
shear-Alfv\'en fluctuations above a critical amplitude $\delta B_{\perp}/B_{0}
\sim \beta^{\,-1/2}$, where $\beta$ is the ratio of thermal to magnetic
pressure. Above this cutoff, a developing fluctuation will generate a pressure
anisotropy that is sufficient to destabilize itself through the parallel
firehose instability. This causes the wave frequency to approach zero,
interrupting the fluctuation before any oscillation. The magnetic field lines
rapidly relax into a sequence of angular zig-zag structures. Such a restrictive
bound on shear-Alfv\'en-wave amplitudes has far-reaching implications for the
physics of magnetized turbulence in the high-$\beta$ conditions prevalent in
many astrophysical plasmas, as well as for the solar wind at $\sim 1
\mathrm{AU}$ where $\beta \gtrsim 1$.

categories: physics.plasm-ph astro-ph.CO astro-ph.HE physics.space-ph


title: The Stability of F-star Brightness on Century Timescales

abstract:
  The century-long photometric record of the DASCH project provides a unique
window into the variability of stars normally considered to be photometrically
inactive. In this paper, we look for long-term trends in the brightness of F
stars, with particular attention to KIC 8462852,an F3 main sequence star that
has been identified as significant short-term variability according to Kepler
observations. Although a simple search for variability suggests long-term
dimming of a number of F stars, we find that such trends are artifacts of the
'Menzel Gap' in the DASCH data. That includes the behavior of KIC 8462852,
which we believe is consistent with constant flux over the full duration of
observations. We do, however, present a selection of F stars that do have
significant photometric trends, even after systematics are taken into account.


title:
Analysis of Two-State Folding Using Parabolic Approximation IV:
  Non-Arrhenius Kinetics of FBP28 WW Part-II

abstract:
  A model which treats the denatured and the native conformers as being
confined to harmonic Gibbs energy wells has been used to rationalize the
physical basis for the non-Arrhenius behaviour of spontaneously-folding fixed
two-state systems. It is shown that at constant pressure and solvent
conditions: (i) the rate constant for folding will be a maximum when the heat
released upon formation of net molecular interactions is exactly compensated by
the heat absorbed to desolvate net polar and non-polar solvent accessible
surface area (SASA), as the denatured conformers driven by thermal noise bury
their SASA and diffuse on the Gibbs energy surface to reach the activated
state; (ii) the rate constant for unfolding will be a minimum when the heat
absorbed by the native conformers to break various net backbone and sidechain
interactions is exactly compensated by the heat of hydration released due to
the net increase in SASA, as the native conformers unravel to reach the
activated state; (iii) the activation entropy for folding will be zero, and the
Gibbs barrier to folding will be a minimum, when the decrease in the backbone
and the sidechain mobility is exactly compensated by the increase in entropy
due to solvent-release, as the denatured conformers bury their SASA to reach
the activated state; and (iv) the activation entropy for unfolding will be
zero, and the Gibbs barrier to unfolding will be a maximum when the increase in
the backbone and sidechain mobility is exactly compensated by the negentropy of
solvent capture on the protein surface, as the native conformers unravel to
reach the activated state.


title:
Analysis of Two-State Folding Using Parabolic Approximation I:
  Hypothesis

abstract:
  A model which treats the denatured and native conformers of
spontaneously-folding fixed two-state systems as being confined to harmonic
Gibbs energy-wells has been developed.Within the assumptions of this model the
Gibbs energy functions of the denatured (DSE) and the native state (NSE)
ensembles are described by parabolas, with the mean length of the reaction
coordinate (RC) being given by the temperature-invariant denaturant m
value.Consequently, the ensemble-averaged position of the transition state
ensemble (TSE) along the RC, and the ensemble-averaged Gibbs energy of the TSE
are determined by the intersection of the DSE and the NSE-parabolas. The
equations derived enable equilibrium stability and the rate constants to be
rationalized in terms of the mean and the variance of the Gaussian distribution
of the solvent accessible surface area of the conformers in the DSE and the
NSE. The implications of this model for protein folding are discussed.


title:
Analysis of Two-State Folding Using Parabolic Approximation II:
  Temperature-Dependence

abstract:
  Equations that govern the temperature-dependence of the rate constants, Gibbs
energies,enthalpies, entropies and heat capacities of activation for folding
and unfolding of spontaneously-folding fixed two-state systems have been
derived using a procedure that treats the denatured and the native conformers
as being confined to harmonic Gibbs energy wells. The notion that a two-state
system is physically defined only for a set temperature range is introduced.
The implications of this novel treatment for protein folding are discussed.


title: Dynamics of Circumstellar Disks III: The case of GG Tau A

abstract:
  (abridged) We present 2-dimensional hydrodynamic simulations using the
Smoothed Particle Hydrodynamic (SPH) code, VINE, to model a self-gravitating
binary system similar to the GG Tau A system. We simulate systems configured
with semi-major axes of either $a=62$~AU (`wide') or $a=32$~AU (`close'), and
with eccentricity of either $e=0$ or $e=0.3$. Strong spiral structures are
generated with large material streams extending inwards. A small fraction
accretes onto the circumstellar disks, with most returning to the torus.
Structures also propagate outwards, generating net outwards mass flow and
eventually losing coherence at large distances. The torus becomes significantly
eccentric in shape. Accretion onto the stars occurs at a rate of a few
$\times10^{-8}$\msun/yr implying disk lifetimes shorter than $\sim10^4$~yr,
without replenishment. Only wide configurations retain disks by virtue of
robust accretion. In eccentric configurations, accretion is episodic, occurs
preferentially onto the secondary at wrates peaked near binary periapse. We
conclude that the \ggtaua\ torus is strongly self gravitating and that a major
contribution to its thermal energy is shock dissipation. We interpret its
observed features as manifestations of spiral structures and the low density
material surrounding it as an excretion disk created by outward mass flux. We
interpret GG Tau A as a coplanar system with an eccentric torus, and account
for its supposed mutual inclination as due to degeneracy between the
interpretation of inclination and eccentricity. Although the disks persist for
long enough to permit planet formation, the environment remains unfavorable due
to high temperatures. We conclude that the GG Tau A system is in an eccentric,
$a\sim62$~AU orbit.


title: Synthesizing Probabilistic Invariants via Doob's Decomposition

abstract:
  When analyzing probabilistic computations, a powerful approach is to first
find a martingale---an expression on the program variables whose expectation
remains invariant---and then apply the optional stopping theorem in order to
infer properties at termination time. One of the main challenges, then, is to
systematically find martingales.
  We propose a novel procedure to synthesize martingale expressions from an
arbitrary initial expression. Contrary to state-of-the-art approaches, we do
not rely on constraint solving. Instead, we use a symbolic construction based
on Doob's decomposition. This procedure can produce very complex martingales,
expressed in terms of conditional expectations.
  We show how to automatically generate and simplify these martingales, as well
as how to apply the optional stopping theorem to infer properties at
termination time. This last step typically involves some simplification steps,
and is usually done manually in current approaches. We implement our techniques
in a prototype tool and demonstrate our process on several classical examples.
Some of them go beyond the capability of current semi-automatic approaches.


title:
LightNet: A Versatile, Standalone Matlab-based Environment for Deep
  Learning

abstract:
  LightNet is a lightweight, versatile and purely Matlab-based deep learning
framework. The idea underlying its design is to provide an easy-to-understand,
easy-to-use and efficient computational platform for deep learning research.
The implemented framework supports major deep learning architectures such as
Multilayer Perceptron Networks (MLP), Convolutional Neural Networks (CNN) and
Recurrent Neural Networks (RNN). The framework also supports both CPU and GPU
computation, and the switch between them is straightforward. Different
applications in computer vision, natural language processing and robotics are
demonstrated as experiments.


title:
Exactly solvable nonequilibrium Langevin relaxation of a trapped
  nanoparticle

abstract:
  In this work, we study the nonequilibrium statistical properties of the
relaxation dynamics of a nanoparticle trapped in a harmonic potential. We
report an exact time-dependent analytical solution to the Langevin dynamics
that arises from the stochastic differential equation of our system's energy in
the underdamped regime. By utilizing this stochastic thermodynamics approach,
we are able to completely describe the heat exchange process between the
nanoparticle and the surrounding environment. As an important consequence of
our results, we observe the validity of the heat exchange fluctuation theorem
(XFT) in our setup, which holds for systems arbitrarily far from equilibrium
conditions. By extending our results for the case of $N$ noninterating
nanoparticles, we perform analytical asymptotic limits and direct numerical
simulations that corroborate our analytical predictions.


title:
Probing the early chemical evolution of the Sculptor dSph with purely
  old stellar tracers

abstract:
  We present the metallicity distribution of a sample of 471 RR Lyrae (RRL)
stars in the Sculptor dSph, obtained from the $I$-band Period-Luminosity
relation. It is the first time that the early chemical evolution of a dwarf
galaxy is characterized in such a detailed and quantitative way, using
photometric data alone. We find a broad metallicity distribution (FWHM=0.8 dex)
that is peaked at [Fe/H]$\simeq$-1.90 dex, in excellent agreement with
literature values obtained from spectroscopic data. Moreover, we are able to
directly trace the metallicity gradient out to a radius of $\sim$55 arcmin. We
find that in the outer regions (r$>\sim$32 arcmin) the slope of the metallicity
gradient from the RRLs (-0.025 dex arcmin$^{-1}$) is comparable to the
literature values based on red giant (RG) stars. However, in the central part
of Sculptor we do not observe the latter gradients. This suggests that there is
a more metal-rich and/or younger population in Sculptor that does not produce
RRLs. This scenario is strengthened by the observation of a metal-rich peak in
the metallicity distribution of RG stars by other authors, which is not present
in the metallicity distribution of the RRLs within the same central area.


title:
Low Lorentz Factor Jets from Compact Stellar Mergers - Candidate
  Electromagnetic Counterparts to Gravitational Wave Sources

abstract:
  Short gamma-ray bursts (GRBs) are believed to be produced by relativistic
jets from mergers of neutron-stars (NS) or neutron-stars and black-holes (BH).
If the Lorentz-factors $\Gamma$ of jets from compact-stellar-mergers follow a
similar power-law distribution to those observed for other high-energy
astrophysical phenomena (e.g. blazars, AGN), the population of jets would be
dominated by low-$\Gamma$ outflows. These jets will not produce the prompt
gamma-rays, but jet energy will be released as x-ray/optical/radio transients
when they collide with the ambient medium. Using Monte Carlo simulations, we
study the properties of such transients. Approximately $78\%$ of merger-jets
$<300~$Mpc result in failed-GRBs if the jet $\Gamma$ follows a power-law
distribution of index $-1.75$. X-ray/optical transients from failed-GRBs will
have broad distributions of their characteristics: light-curves peak
$t_p\sim0.1-10~$days after a merger; flux peaks for x-ray
$10^{-6}{\rm~mJy}\lesssim~F_x\lesssim10^{-2}~$mJy; and optical flux peaks at
$14\lesssim~m_g\lesssim22$. X-ray transients are detectable by Swift XRT, and
$\sim85\%$ of optical transients will be detectable by telescopes with limiting
magnitude $m_g \gtrsim 21$, for well localized sources on the sky.
X-ray/optical transients are followed by radio transients with peak times
narrowly clustered around $t_p\sim10~$days, and peak flux of $\sim~10-100~$mJy
at 10 GHz and $\sim~0.1~$mJy at 150 MHz. By considering the all-sky rate of
short GRBs within the LIGO/Virgo range, the rate of on-axis orphan afterglows
from failed-GRB would be 2.6(26) per year for NS-NS(NS-BH) mergers,
respectively. Since merger jets from gravitational-wave (GW) trigger events
tend to be directed to us, a significant fraction of GW events could be
associated with the on-axis orphan afterglow.


title:
The low abundance and insignificance of dark discs in simulated Milky
  Way galaxies

abstract:
  We investigate the presence and importance of dark matter discs in a sample
of 24 simulated Milky Way galaxies in the APOSTLE project, part of the EAGLE
programme of hydrodynamic simulations in Lambda-CDM cosmology. It has been
suggested that a dark disc in the Milky Way may boost the dark matter density
and modify the velocity modulus relative to a smooth halo at the position of
the Sun, with ramifications for direct detection experiments. From a kinematic
decomposition of the dark matter and a real space analysis of all 24 halos, we
find that only one of the simulated Milky Way analogues has a detectable dark
disc component. This unique event was caused by a merger at late time with an
LMC-mass satellite at very low grazing angle. Considering that even this rare
scenario only enhances the dark matter density at the solar radius by 35% and
affects the high energy tail of the dark matter velocity distribution by less
than 1%, we conclude that the presence of a dark disc in the Milky Way is
unlikely, and is very unlikely to have a significant effect on direct detection
experiments.


title:
The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet
  Imager

abstract:
  Using the Gemini Planet Imager (GPI), we have resolved the circumstellar
debris disk around HD 111520 at a projected range of ~30-100 AU in both total
and polarized $H$-band intensity. The disk is seen edge-on at a position angle
of ~165$^{\circ}$ along the spine of emission. A slight inclination or
asymmetric warping are covariant and alters the interpretation of the observed
disk emission. We employ 3 point spread function (PSF) subtraction methods to
reduce the stellar glare and instrumental artifacts to confirm that there is a
roughly 2:1 brightness asymmetry between the NW and SE extension. This specific
feature makes HD 111520 the most extreme examples of asymmetric debris disks
observed in scattered light among similar highly inclined systems, such as HD
15115 and HD 106906. We further identify a tentative localized brightness
enhancement and scale height enhancement associated with the disk at ~40 AU
away from the star on the SE extension. We also find that the fractional
polarization rises from 10 to 40% from 0.5" to 0.8" from the star. The
combination of large brightness asymmetry and symmetric polarization fraction
leads us to believe that an azimuthal dust density variation is causing the
observed asymmetry.


title: Querying Temporal Drifts at Multiple Granularities (Technical Report)

abstract:
  There exists a large body of work on online drift detection with the goal of
dynamically finding and maintaining changes in data streams. In this paper, we
adopt a query-based approach to drift detection. Our approach relies on {\em a
drift index}, a structure that captures drift at different time granularities
and enables flexible {\em drift queries}. We formalize different drift queries
that represent real-world scenarios and develop query evaluation algorithms
that use different materializations of the drift index as well as strategies
for online index maintenance. We describe a thorough study of the performance
of our algorithms on real-world and synthetic datasets with varying change
rates.


title:
The Entire Virial Radius of the Fossil Cluster RXJ1159+5531: II. Dark
  Matter and Baryon Fraction

abstract:
  In this second paper on the entire virial region of the relaxed fossil
cluster RXJ1159+5531, we present a hydrostatic analysis of the hot intracluster
medium (ICM). For a model consisting of ICM, stellar mass from the central
galaxy (BCG), and an NFW dark matter (DM) halo, we obtain good descriptions of
the projected radial profiles of ICM emissivity and temperature. The BCG
stellar mass is clearly detected with M_star/L_K = 0.61 +/- 0.11 solar,
consistent with stellar population synthesis models for a Milky-Way IMF. We
obtain a halo concentration, c_200 =8.4 +/- 1.0, and virial mass, M_200 = 7.9
+/- 0.6 x 10^13 M_sun. For its mass, the inferred concentration is larger than
most relaxed halos produced in cosmological simulations with Planck parameters,
consistent with RXJ1159+5531 forming earlier than the general halo population.
The baryon fraction at r_200, f_b,200 = 0.134 +/- 0.007, is slightly below the
Planck value (0.155) for the universe. When we account for the stellar baryons
associated with non-central galaxies and the uncertain intracluster light,
f_b,200 increases by ~0.015, consistent with the cosmic value. Performing our
analysis in the context of MOND still requires a large DM fraction (85.0% +/-
2.5% at r=100 kpc) similar to that obtained using the standard Newtonian
approach. The detection of a plausible stellar BCG mass component distinct from
the NFW DM halo in the total gravitational potential suggests that ~10^14 M_sun
represents the mass scale above which dissipation is unimportant in the
formation of the central regions of galaxy clusters. (Abridged)


title: Staggered Quantum Walks with Hamiltonians

abstract:
  Quantum walks are recognizably useful for the development of new quantum
algorithms, as well as for the investigation of several physical phenomena in
quantum systems. Actual implementations of quantum walks face technological
difficulties similar to the ones for quantum computers, though. Therefore,
there is a strong motivation to develop new quantum-walk models which might be
easier to implement. In this work, we present an extension of the staggered
quantum walk model that is fitted for physical implementations in terms of
time-independent Hamiltonians. We demonstrate that this class of quantum walk
includes the entire class of staggered quantum walk model, Szegedy's model, and
an important subset of the coined model.


title:
Image Classification of Grapevine Buds using Scale-Invariant Features
  Transform, Bag of Features and Support Vector Machines

abstract:
  In viticulture, there are several applications where bud detection in
vineyard images is a necessary task, susceptible of being automated through the
use of computer vision methods. A common and effective family of visual
detection algorithms are the scanning-window type, that slide a (usually) fixed
size window along the original image, classifying each resulting windowed-patch
as containing or not containing the target object. The simplicity of these
algorithms finds its most challenging aspect in the classification stage.
Interested in grapevine buds detection in natural field conditions, this paper
presents a classification method for images of grapevine buds ranging 100 to
1600 pixels in diameter, captured in outdoor, under natural field conditions,
in winter (i.e., no grape bunches, very few leaves, and dormant buds), without
artificial background, and with minimum equipment requirements. The proposed
method uses well-known computer vision technologies: Scale-Invariant Feature
Transform for calculating low-level features, Bag of Features for building an
image descriptor, and Support Vector Machines for training a classifier. When
evaluated over images containing buds of at least 100 pixels in diameter, the
approach achieves a recall higher than 0.9 and a precision of 0.86 over all
windowed-patches covering the whole bud and down to 60% of it, and scaled up to
window patches containing a proportion of 20%-80% of bud versus background
pixels. This robustness on the position and size of the window demonstrates its
viability for use as the classification stage in a scanning-window detection
algorithms.


title:
Chebychev interpolations of the Gamma and Polygamma Functions and their
  analytical properties

abstract:
  Chebychev approximations are given for the Gamma and the Polygamma functions
in only one contiguous intervall [1..inf] with a definable maximal relative
error. The approximations need about three coefficients per decimal until a
checked precision of 100 decimal digits.


title:
Sobolev Spaces of Fractional Order, Lipschitz Spaces, Readapted
  Modulation Spaces and Their Interrelations; Applications

abstract:
  The purpose of this investigation is to extend basic equations and
inequalities which hold for functions $f$ in a Bernstein space $B_\sigma^2$ to
larger spaces by adding a remainder term which involves the distance of $f$
from $B_\sigma^2$.
  First we present a modification of the classical modulation space
$M^{2,1}(\mathbb{R})$, the so-called readapted modulation space
$M^{2,1}_\text{a}(\mathbb{R})$. Our approach to the latter space and its role
in functional analysis is novel. In fact, we establish several chains of
inclusion relations between $M^{2,1}_\text{a}(\mathbb{R})$ and the more common
Lipschitz and Sobolev spaces, including Sobolev spaces of fractional order.
  Next we introduce an appropriate metric for describing the distance of a
function belonging to one of the latter spaces from a Bernstein space. It will
be used for estimating remainders and studying rates of convergence.
  In the main part, we present the desired extensions. Our applications include
the classical Whittaker-Kotel'nikov-Shannon sampling formula, the reproducing
kernel formula, the Parseval decomposition formula, Bernstein's inequality for
derivatives, and Nikol'ski\u{\i}'s inequality estimating the $l^p(\mathbb{Z})$
norm in terms of the $L^p(\mathbb{R})$ norm.


title: Calculational Design of Information Flow Monitors (extended version)

abstract:
  Fine grained information flow monitoring can in principle address a wide
range of security and privacy goals, for example in web applications. But it is
very difficult to achieve sound monitoring with acceptable runtime cost and
sufficient precision to avoid impractical restrictions on programs and
policies. We present a systematic technique for design of monitors that are
correct by construction. It encompasses policies with downgrading. The
technique is based on abstract interpretation which is a standard basis for
static analysis of programs. This should enable integration of a wide range of
analysis techniques, enabling more sophisticated engineering of monitors to
address the challenges of precision and scaling to widely used programming
languages.


title: Thermodynamic and spectral properties of adiabatic Peierls chains

abstract:
  We present exact numerical results for the effects of thermal fluctuations on
the experimentally relevant thermodynamic and spectral properties of Peierls
chains. To this end, a combination of classical Monte Carlo sampling and exact
diagonalization is used to study adiabatic half-filled Holstein and
Su-Schrieffer-Heeger models. The classical nature of the lattice displacements
in combination with parallel tempering permit simulations on large system sizes
and a direct calculation of spectral functions in the frequency domain. Most
notably, the long-range order and the associated Peierls gap give rise to a
distinct low-temperature peak in the specific heat. The closing of the gap and
suppression of order by thermal fluctuations involves in-gap excitations in the
form of soliton-antisoliton pairs, and is also reflected in the dynamic density
and bond structure factors as well as in the optical conductivity. We compare
our data to the widely used mean-field approximation, and highlight relations
to symmetry-protected topological phases and disorder problems.


title: Energetic characterisation and statistics of solar coronal brightenings

abstract:
  To explain the high temperature of the corona, much attention has been paid
to the distribution of energy in dissipation events. Indeed, if the event
energy distribution is steep enough, the smallest, unobservable events could be
the largest contributors to the total energy dissipation in the corona.
Previous observations have shown a wide distribution of energies but remain
inconclusive about the precise slope. Furthermore, these results rely on a very
crude estimate of the energy. On the other hand, more detailed spectroscopic
studies of structures such as coronal bright points do not provide enough
statistical information to derive their total contribution to heating. We aim
at getting a better estimate of the distributions of the energy dissipated in
coronal heating events using high-resolution, multi-channel Extreme
Ultra-Violet (EUV) data. To estimate the energies corresponding to heating
events and deduce their distribution, we detect brightenings in five EUV
channels of the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics
Observatory (SDO). We combine the results of these detections and we use maps
of temperature and emission measure derived from the same observations to
compute the energies. We obtain distributions of areas, durations, intensities,
and energies (thermal, radiative, and conductive) of events. These
distributions are power-laws, and we find also power-law correlations between
event parameters. The energy distributions indicate that the energy from a
population of events like the ones we detect represents a small contribution to
the total coronal heating, even when extrapolating to smaller scales. The main
explanations for this are how heating events can be extracted from
observational data, and the incomplete knowledge of the thermal structure and
processes in the coronal plasma attainable from available observations.


title: Light Deflection with Torsion Effects Caused by a Spinning Cosmic String

abstract:
  Using a new geometrical method introduced by Werner, we find the deflection
angle in the weak limit approximation by a spinning cosmic string in the
context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the
String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the
optical geometry and derive the leading terms of the deflection angle in the
equatorial plane. Calculations shows that light deflection is affected by the
intrinsic spin of the cosmic string and torsion.


title: Hall viscosity and electromagnetic response of electrons in graphene

abstract:
  We derive an analytic expression for the geometric Hall viscosity of
non-interacting electrons in a single graphene layer in the presence of a
perpendicular magnetic field. We show that a recently-derived formula in [C.
Hoyos and D. T. Son, Phys. Rev. Lett. {\bf 108}, 066805 (2012)], which connects
the coefficient of $q^2$ in the wave vector expansion of the Hall conductivity
$\sigma_{xy}(q)$ of the two-dimensional electron gas (2DEG) to the Hall
viscosity and the orbital diamagnetic susceptibility of that system, continues
to hold for graphene -- in spite of the lack of Galilean invariance -- with a
suitable definition of the effective mass. We also show that, for a
sufficiently large number of occupied Landau levels in the positive energy
sector, the Hall conductivity of electrons in graphene reduces to that of a
Galilean-invariant 2DEG with an effective mass given by $\hbar k_F/v_F$
(cyclotron mass). Even in the most demanding case, i.e. when the chemical
potential falls between the zero-th and the first Landau level, the cyclotron
mass formula gives results accurate to better than 1$\%$. The connection
between the Hall conductivity and the viscosity provides a possible avenue to
measure the Hall viscosity in graphene.


title: Estimacion de carga muscular mediante imagenes

abstract:
  Un problema de gran interes en disciplinas como la ocupacional, ergonomica y
deportiva, es la medicion de variables biomecanicas involucradas en el
movimiento humano (como las fuerzas musculares internas y torque de
articulaciones). Actualmente este problema se resuelve en un proceso de dos
pasos. Primero capturando datos con dispositivos poco pr\'acticos, intrusivos y
costosos. Luego estos datos son usados como entrada en modelos complejos para
obtener las variables biomecanicas como salida. El presente trabajo representa
una alternativa automatizada, no intrusiva y economica al primer paso,
proponiendo la captura de estos datos a traves de imagenes. En trabajos futuros
la idea es automatizar todo el proceso de calculo de esas variables. En este
trabajo elegimos un caso particular de medicion de variables biomecanicas: el
problema de estimar el nivel discreto de carga muscular que estan ejerciendo
los musculos de un brazo. Para estimar a partir de imagenes estaticas del brazo
ejerciendo la fuerza de sostener la carga, el nivel de la misma, realizamos un
proceso de clasificacion. Nuestro enfoque utiliza Support Vector Machines para
clasificacion, combinada con una etapa de pre-procesamiento que extrae
caracter{\i}sticas visuales utilizando variadas tecnicas (Bag of Keypoints,
Local Binary Patterns, Histogramas de Color, Momentos de Contornos) En los
mejores casos (Local Binary Patterns y Momentos de Contornos) obtenemos medidas
de performance en la clasificacion (Precision, Recall, F-Measure y Accuracy)
superiores al 90 %.


title:
Identification of refugee influx patterns in Greece via model-theoretic
  analysis of daily arrivals

abstract:
  The refugee crisis is perhaps the single most challenging problem for Europe
today. Hundreds of thousands of people have already traveled across dangerous
sea passages from Turkish shores to Greek islands, resulting in thousands of
dead and missing, despite the best rescue efforts from both sides. One of the
main reasons is the total lack of any early warning-alerting system, which
could provide some preparation time for the prompt and effective deployment of
resources at the hot zones. This work is such an attempt for a systemic
analysis of the refugee influx in Greece, aiming at (a) the statistical and
signal-level characterization of the smuggling networks and (b) the formulation
and preliminary assessment of such models for predictive purposes, i.e., as the
basis of such an early warning-alerting protocol. To our knowledge, this is the
first-ever attempt to design such a system, since this refugee crisis itself
and its geographical properties are unique (intense event handling, little or
no warning). The analysis employs a wide range of statistical, signal-based and
matrix factorization (decomposition) techniques, including linear &
linear-cosine regression, spectral analysis, ARMA, SVD, Probabilistic PCA, ICA,
K-SVD for Dictionary Learning, as well as fractal dimension analysis. It is
established that the behavioral patterns of the smuggling networks closely
match (as expected) the regular burst and pause periods of store-and-forward
networks in digital communications. There are also major periodic trends in the
range of 6.2-6.5 days and strong correlations in lags of four or more days,
with distinct preference in the Sunday-Monday 48-hour time frame. These results
show that such models can be used successfully for short-term forecasting of
the influx intensity, producing an invaluable operational asset for planners,
decision-makers and first-responders.


title: Hagedorn temperature and physics of black holes

abstract:
  A mini-review devoted to some implications of the Hagedorn temperature for
black hole physics. The existence of a limiting temperature is a generic
feature of string models. The Hagedorn temperature was introduced first in the
context of hadronic physics. Nowadays, the emphasis is shifted to fundamental
strings which might be a necessary ingredient to obtain a consistent theory of
black holes. The point is that, in field theory, the local temperature close to
the horizon could be arbitrarily high, and this observation is difficult to
reconcile with the finiteness of the entropy of black holes. After preliminary
remarks, we review our recent attempt to evaluate the entropy of large black
holes in terms of fundamental strings. We also speculate on implications for
dynamics of large-N gauge theories arising within holographic models.


title:
A candidate optical counterpart to the middle-aged gamma-ray pulsar PSR
  J1741-2054

abstract:
  We carried out deep optical observations of the middle-aged $\gamma$-ray
pulsar PSR J1741-2054 with the Very Large Telescope (VLT). We identified two
objects, of magnitudes $m_v=23.10\pm0.05$ and $m_v=25.32\pm0.08$, at positions
consistent with the very accurate Chandra coordinates of the pulsar, the
faintest of which is more likely to be its counterpart. From the VLT images we
also detected the known bow-shock nebula around PSR J1741-2054. The nebula is
displaced by $\sim 0\farcs9$ (at the $3\sigma$ confidence level) with respect
to its position measured in archival data, showing that the shock propagates in
the interstellar medium consistently with the pulsar proper motion. Finally, we
could not find evidence of large-scale extended optical emission associated
with the pulsar wind nebula detected by Chandra, down to a surface brightness
limit of $\sim 28.1$ magnitudes arcsec$^{-2}$. Future observations are needed
to confirm the optical identification of PSR J1741-2054 and characterise the
spectrum of its counterpart.


title: A Mordell-Weil theorem for cubic hypersurfaces of high dimension

abstract:
  Let $X$ be a smooth cubic hypersurface of dimension $n \ge 1$ over the
rationals. It is well-known that new rational points may be obtained from old
ones by secant and tangent constructions. In view of the Mordell--Weil theorem
for $n=1$, Manin (1968) asked if there exists a finite set $S$ from which all
other rational points can be thus obtained. We give an affirmative answer for
$n \ge 48$, showing in fact that we can take the generating set $S$ to consist
of just one point. Our proof makes use of a weak approximation theorem due to
Skinner, a theorem of Browning, Dietmann and Heath-Brown on the existence of
rational points on the intersection of a quadric and cubic in large dimension,
and some elementary ideas from differential geometry, algebraic geometry and
numerical analysis.


title:
On the smoothness of solutions to elliptic equations in domains with
  H\"older boundary

abstract:
  The dependence of the smoothness of variational solutions to the first
boundary value problems for second order elliptic operators are studied. The
results use Sobolev-Slobodetskii and Nikolskii-Besov spaces and their
properties. Methods are based on real interpolation technique and
generalization of Savar\'{e}-Nirenberg difference quotient technique.


title:
Far Infrared Edge Photoresponse and Persistent Edge Transport in an
  Inverted InAs/GaSb Heterostructure

abstract:
  Direct current (DC) transport and far infrared photoresponse were studied an
InAs/GaSb double quantum well with an inverted band structure. The DC transport
depends systematically upon the DC bias configuration and operating
temperature. Surprisingly, it reveals robust edge conduction despite prevalent
bulk transport in our device of macroscopic size. Under 180 GHz far infrared
illumination at oblique incidence, we measured a strong photovoltaic response.
We conclude that quantum spin Hall edge transport produces the observed
transverse photovoltages. Overall, our experimental results support a
hypothesis that the photoresponse arises from direct coupling of the incident
radiation field to edge states.


title: Photon pair shot noise in electron shot noise

abstract:
  There exists a fascinating dual representation of the electric ac current
flowing through a normal conductor. On the one hand, it can be understood in
terms of charge transport. On the other hand, it consists in an electomagnetic
field guided by conducting structures embedded in an insulator. The former
point of view, in its quantum version, is particularly adapted to describe the
electron shot noise in a coherent conductor, like a tunnel junction at
ultra-low temperature. However, when the junction is appropriately biased by a
dc and an ac voltage, the noise it generates is best analyzed using the latter
representation and the tools of quantum optics, as the radiation exhibits clear
signs of non-classicality. Herein, we report the measurement of the statistics
of photons emitted by such a tunnel junction. We observe a photon shot noise
characteristic of photon pair emission, as its Fano factor for small signal is
above unity. The theory of electron shot noise, dealing exclusively with the
tunneling of charges through the junction, quantitatively fits the data from
which photon shot noise is extracted. This experiment thus provides a clear
link between the dual representations.


title:
Radiative levitation in carbon-enhanced metal-poor stars with s-process
  enrichment

abstract:
  A significant fraction of all metal-poor stars are carbon-rich. Most of these
carbon-enhanced metal-poor (CEMP) stars also show enhancement in elements
produced mainly by the s-process (CEMP-s stars) and evidence suggests that the
origin of these non-standard abundances can be traced to mass transfer from a
binary asymptotic giant branch (AGB) companion. Thus, observations of CEMP-s
stars are commonly used to infer the nucleosynthesis output of low-metallicity
AGB stars. A crucial step in this exercise is understanding what happens to the
accreted material after mass transfer ceases. Here we present models of the
post-mass-transfer evolution of CEMP-s stars considering the physics of
thermohaline mixing and atomic diffusion, including radiative levitation. We
find that stars with typical CEMP-s star masses (M ~ 0.85 Msun) have very
shallow convective envelopes (Menv < 1e-7 Msun). Hence, the surface abundance
variations arising from the competition between gravitational settling and
radiative levitation should be orders of magnitude larger than observed (e.g.
[C/Fe]<-1 or [C/Fe]>+4). We are therefore unable to reproduce the spread in the
observed abundances with these models and conclude that some other physical
process must largely suppress atomic diffusion in the outer layers of CEMP-s
stars. We demonstrate that this could be achieved by some additional
(turbulent) mixing process operating at the base of the convective envelope, as
found by other authors. Alternatively, mass-loss rates around 1e-13 Msun/yr
could also negate most of the abundance variations by eroding the surface
layers and forcing the base of the convective envelope to move inwards in mass.
Since atomic diffusion cannot have a substantial effect on the surface
abundances of CEMP-s stars, the dilution of the accreted material, while
variable in degree from one star to the next, is most likely the same for all
elements.


title: Vaisman nilmanifolds

abstract:
  We prove that if a compact nilmanifold $\Gamma\backslash G$ is endowed with a
Vaisman structure, then $G$ is isomorphic to the Cartesian product of the
Heisenberg group with $\mathbb{R}$.


title:
Prospects for annihilating Dark Matter towards Milky Way's dwarf
  galaxies by the Cherenkov Telescope Array

abstract:
  We derive the Cherenkov Telescope Array (CTA) sensitivity to dark matter (DM)
annihilation in several primary channels, over a broad range of DM masses.
These sensitivities are estimated when CTA is pointed towards a large sample of
Milky Way's dwarf spheroidal galaxies (dSphs) with promising $J$-factors and
small statistical uncertainties. This analysis neglects systematic
uncertainties, which we estimate at the level of at least 1 dex. We also
present sensitivities on the annihilation cross section from a combined
analysis of 4 dSphs. We assess the CTA sensitivity by: $i)$ using, for each
dSph, a recent determination of the $J$-factor and its statistical error; $ii)$
considering the most up-to-date cosmic ray background; and $iii)$ including
both spatial and spectral terms in the likelihood analysis. We find that a
joint spectral and spatial analysis improves the CTA sensitivity, in particular
for primary channels with sharp features in the $\gamma$-ray energy spectrum
and for dSphs with steep $J$-factor profiles, as deduced from the internal
kinematics. The greatest sensitivities are obtained for observations of Ursa
Minor among the classical dSphs and of Ursa Major II for ultra-faint dSphs.


title:
$R(D^{(*)})$ and $\mathcal{B}r(B \rightarrow \tau\nu_{\tau})$ in a
  Flipped/Lepton-Specific 2HDM with anomalously enhanced charged Higgs coupling
  to $\tau$/b

abstract:
  Babar, Belle and recently LHCb has reported an excess in the measurements of
$R(D^{*})$, $R(D)$ and $\mathcal{B}r(B \rightarrow \tau \nu_{\tau} )$ than
expected from SM, a possible signature of lepton flavor universality violating
NP. In this work we analyze the phenomenological implications for these decay
modes in a Flipped/Lepton-Specific 2HDM with anomalously enhanced Yukawa
coupling of $H^{\pm}$ to $\tau$/b. When experimental and theoretical errors are
added in quadrature, we conclude that this phenomenological extension of SM can
give results in agreement within 1$\sigma$ deviation for the combination of
$R(D^{(*)})$ and $\mathcal{B}r(B \rightarrow \tau \nu_{\tau})$ compare to about
4$\sigma$ deviation from SM from the latest combined[Babar,Belle,LHCb]
experimental data for these observables.


title: Derived categories of noncommutative quadrics and Hilbert squares

abstract:
  A noncommutative deformation of a quadric surface is usually described by a
three-dimensional cubic Artin-Schelter regular algebra. In this paper we show
that for such an algebra its bounded derived category embeds into the bounded
derived category of a commutative deformation of the Hilbert scheme of two
points on the quadric. This is the second example in support of a conjecture by
Orlov. Based on this example, we formulate an infinitesimal version of the
conjecture, and provide some evidence in the case of smooth projective
surfaces.


title: Analysis of SQL Injection Detection Techniques

abstract:
  SQL Injection is one of the vulnerabilities in OWASPs Top Ten List for Web
Based Application Exploitation.These types of attacks takes place on Dynamic
Web applications as they interact with the databases for the various
operations.Current Content Management System like Drupal, Joomla or Wordpress
have all the information stored in their databases. A single intrusion into
these types of websites can lead to overall control of websites by the
attacker. Researchers are aware of the basic SQL Injection attacks but there
are numerous SQL Injection attacks which are yet to be Prevented and Detected.
Over here, we present the extensive review for the Advanced SQL Injection
attack such as Fast Flux Sql Injection, Compounded SQL Injection and Deep Blind
SQL Injection. We also analyze the detection and prevention using the classical
methods as well as modern approaches. We will be discussing the Comparative
Evaluation for prevention of SQL Injection.


title:
The BSM-AI project: SUSY-AI - Generalizing LHC limits on Supersymmetry
  with Machine Learning

abstract:
  A key research question at the Large Hadron Collider (LHC) is the test of
models of new physics. Testing if a particular parameter set of such a model is
excluded by LHC data is a challenge: It requires the time consuming generation
of scattering events, the simulation of the detector response, the event
reconstruction, cross section calculations and analysis code to test against
several hundred signal regions defined by the ATLAS and CMS experiment. In the
BSM-AI project we attack this challenge with a new approach. Machine learning
tools are thought to predict within a fraction of a millisecond if a model is
excluded or not directly from the model parameters. A first example is SUSY-AI,
trained on the phenomenological supersymmetric standard model (pMSSM). About
300,000 pMSSM model sets - each tested with 200 signal regions by ATLAS - have
been used to train and validate SUSY-AI. The code is currently able to
reproduce the ATLAS exclusion regions in 19 dimensions with an accuracy of at
least 93 percent. It has been validated further within the constrained MSSM and
a minimal natural supersymmetric model, again showing high accuracy. SUSY-AI
and its future BSM derivatives will help to solve the problem of recasting LHC
results for any model of new physics.
  SUSY-AI can be downloaded at http://susyai.hepforge.org/. An on-line
interface to the program for quick testing purposes can be found at
http://www.susy-ai.org/.


title: Correlation Driven Transport Asymmetries Through Coupled Spins

abstract:
  Correlation is a fundamental statistical measure of order in interacting
quantum systems. In solids, electron correlations govern a diverse array of
material classes and phenomena such as heavy fermion compounds, Hunds metals,
high-Tc superconductors, and the Kondo effect. Spin-spin correlations, notably
investigated by Kaufman and Onsager in the 1940s 6, are at the foundation of
numerous theoretical models but are challenging to measure experimentally.
Reciprocal space methods can map correlations, but at the single atom limit new
experimental probes are needed. Here, we determine the correlations between a
strongly hybridized spin impurity and its electron bath by varying the coupling
to a second magnetic impurity in the junction of a scanning tunneling
microscope. Electronic transport through these coupled spins reveals an
asymmetry in the differential conductance reminiscent of spin-polarized
transport in a magnetic field. We show that at zero field, this asymmetry can
be controlled by the coupling strength and is directly related to either
ferromagnetic (FM) or antiferromagnetic (AFM) spin-spin correlations.


title:
Klein tunneling and magnetoresistance of \textit{p-n} junctions in Weyl
  semimetals

abstract:
  We study the zero temperature conductance and magnetoconductance of ballistic
\textit{p-n} junctions in Weyl semimetals. Electron transport is mediated by
Klein tunneling between \textit{n}- and \textit{p}- regions. The chiral anomaly
that is realized in Weyl semimetals plays a crucial role in the
magnetoconductance of the junction. With the exception of field orientations
where the angle between $\mathbf{B}$ and the junction plane is small,
magnetoconductance is positive and linear in $B$ at both weak and strong
magnetic fields. In contrast, magnetoconductance in conventional \textit{p-n}
junctions is always negative.


title: Around Property (T) for quantum groups

abstract:
  We study Property (T) for locally compact quantum groups, providing several
new characterisations, especially related to operator algebraic ergodic theory.
Quantum Property (T) is described in terms of the existence of various Kazhdan
type pairs, and some earlier structural results of Kyed, Chen and Ng are
strengthened and generalised. For second countable discrete unimodular quantum
groups with low duals Property (T) is shown to be equivalent to Property
(T)$^{1,1}$ of Bekka and Valette. This is used to extend to this class of
quantum groups classical theorems on 'typical' representations (due to Kerr and
Pichot), and on connections of Property (T) with spectral gaps (due to Li and
Ng) and with strong ergodicity of weakly mixing actions on a particular von
Neumann algebra (due to Connes and Weiss). Finally we discuss in the Appendix
equivalent characterisations of the notion of a quantum group morphism with
dense image.


title:
Self-referencing of an on-chip soliton Kerr frequency comb without
  external broadening

abstract:
  Self-referencing turns pulsed laser systems into self-referenced frequency
combs. Such frequency combs allow counting of optical frequencies and have a
wide range of applications. The required optical bandwidth to implement
self-referencing is typically obtained via nonlinear broadening in optical
fibers. Recent advances in the field of Kerr frequency combs have provided a
path towards the development of compact frequency comb sources that provide
broadband frequency combs, exhibit microwave repetition rates and that are
compatible with on-chip photonic integration. These devices have the potential
to significantly expand the use of frequency combs. Yet to date
self-referencing of such Kerr frequency combs has only been attained by
applying conventional, fiber based broadening techniques. Here we demonstrate
external broadening-free self-referencing of a Kerr frequency comb. An optical
spectrum that spans two-thirds of an octave is directly synthesized from a
continuous wave laser-driven silicon nitride microresonator using temporal
dissipative Kerr soliton formation and soliton Cherenkov radiation. Using this
coherent bandwidth and two continuous wave transfer lasers in a 2f-3f
self-referencing scheme, we are able to detect the offset frequency of the
soliton Kerr frequency comb. By stabilizing the repetition rate to a radio
frequency reference the self-referenced frequency comb is used to count and
track the continuous wave pump laser's frequency. This work demonstrates the
principal ability of soliton Kerr frequency combs to provide
microwave-to-optical clockworks on a chip.


title:
The realm of the Galactic globular clusters and the mass of their
  primordial clouds

abstract:
  By adopting the empirical constraints related to the estimates of Helium
enhancement ($\Delta Y$), present mass ratio between first and second stellar
generations ($M_{1G}/M_{2G}$) and the actual mass of Galactic globular clusters
($M_{GC}$), we envisage a possible scenario for the formation of these stellar
systems. Our approach allows for the possible loss of stars through evaporation
or tidal interactions and different star formation efficiencies. In our
approach the star formation efficiency of the first generation
($\epsilon_{1G}$) is the central factor that links the stellar generations as
it not only defines both the mass in stars of the first generation and the
remaining mass available for further star formation, but it also fixes the
amount of matter required to contaminate the second stellar generation. In this
way, $\epsilon_{1G}$ is fully defined by the He enhancement between successive
generations in a GC. We also show that globular clusters fit well within a
$\Delta Y$ {\it vs} $M_{1G}/M_{2G}$ diagram which indicates three different
evolutionary paths. The central one is for clusters that have not loss stars,
through tidal interactions, from either of their stellar generations, and thus
their present $M_{GC}$ value is identical to the amount of low mass stars ($M_*
\le$ 1 M$_\odot$) that resulted from both stellar generations. Other possible
evolutions imply either the loss of first generation stars or the combination
of a low star formation efficiency in the second stellar generation and/or a
loss of stars from the second generation. From these considerations we derive a
lower limit to the mass ($M_{tot}$) of the individual primordial clouds that
gave origin to globular clusters.


title:
Adiabatic corrections to holographic entanglement in thermofield doubles
  and confining ground states

abstract:
  We study entanglement in states of holographic CFTs defined by Euclidean path
integrals over geometries with slowly varying metrics. In particular, our CFT
spacetimes have $S^1$ fibers whose size $b$ varies along one direction ($x$) of
an ${\mathbb R}^{d-1}$ base. Such examples respect an ${\mathbb R}^{d-2}$
Euclidean symmetry. Treating the $S^1$ direction as time leads to a thermofield
double state on a spacetime with adiabatically varying redshift, while treating
another direction as time leads to a confining ground state with slowly varying
confinement scale. In both contexts the entropy of slab-shaped regions defined
by $|x - x_0| \le L$ exhibits well-known phase transitions at length scales $L=
L_{crit}$ characterizing the CFT entanglements. For the thermofield double, the
numerical coefficients governing the effect of variations in $b(x)$ on the
transition are surprisingly small and exhibit an interesting change of sign:
gradients reduce $L_{crit}$ for $d \le 3$ but increase $L_{crit}$ for $d\ge4$.
This means that, while for general $L > L_{crit}$ they significantly increase
the mutual information of opposing slabs as one would expect, for $d\ge 4$
gradients cause a small decrease near the phase transition. In contrast, for
the confining ground states gradients always decrease $L_{crit}$, with the
effect becoming more pronounced in higher dimensions.


title: Holographic confinement in inhomogenous backgrounds

abstract:
  As noted by Witten, compactifying a $d$-dimensional holographic CFT on an
$S^1$ gives a class of $(d-1)$-dimensional confining theories with gravity
duals. The prototypical bulk solution dual to the ground state is a double Wick
rotation of the AdS$_{d+1}$ Schwarzschild black hole known as the AdS soliton.
We generalize such examples by allowing slow variations in the size of the
$S^1$, and thus in the confinement scale. Coefficients governing the second
order response of the system are computed for $3 \le d \le 8$ using a
derivative expansion closely related to the fluid-gravity correspondence. The
primary physical results are that i) gauge-theory flux tubes tend to align
orthogonal to gradients and along the eigenvector of the Hessian with the
lowest eigenvalue, ii) flux tubes aligned orthogonal to gradients are attracted
to gradients for $d \le 6$ but repelled by gradients for $d \ge 7$, iii) flux
tubes are repelled by regions where the second derivative along the tube is
large and positive but are attracted to regions where the eigenvalues of the
Hessian are large and positive in directions orthogonal to the tube, and iv)
for $d > 3$, inhomogeneities act to raise the total energy of the confining
vacuum above its zeroth order value.


title:
Dynamics of interlacing peakons (and shockpeakons) in the Geng-Xue
  equation

abstract:
  We consider multipeakon solutions, and to some extent also multishockpeakon
solutions, of a coupled two-component integrable PDE found by Geng and Xue as a
generalization of Novikov's cubically nonlinear Camassa-Holm type equation. In
order to make sense of such solutions, we find it necessary to assume that
there are no overlaps, meaning that a peakon or shockpeakon in one component is
not allowed to occupy the same position as a peakon or shockpeakon in the other
component. Therefore one can distinguish many inequivalent configurations,
depending on the order in which the peakons or shockpeakons in the two
components appear relative to each other. Here we are in particular interested
in the case of interlacing peakon solutions, where the peakons alternatingly
occur in one component and in the other. Based on explicit expressions for
these solutions in terms of elementary functions, we describe the general
features of the dynamics, and in particular the asymptotic large-time
behaviour. As far as the positions are concerned, interlacing Geng-Xue peakons
display the usual scattering phenomenon where the peakons asymptotically travel
with constant velocities, which are all distinct, except that the two fastest
peakons will have the same velocity. However, in contrast to many other peakon
equations, the amplitudes of the peakons will not in general tend to constant
values; instead they grow or decay exponentially. Thus the logarithms of the
amplitudes (as functions of time) will asymptotically behave like straight
lines, and comparing these lines for large positive and negative times, one
observes phase shifts similar to those seen for the positions of the peakons.
In addition to these K+K interlacing pure peakon solutions, we also investigate
1+1 shockpeakon solutions, and collisions leading to shock formation in a 2+2
peakon-antipeakon solution.


title:
Self-heating effects of the surface oxidized FeCo nanoparticles colloid
  under alternating magnetic field

abstract:
  To evaluate the self-heating effects of FeCo magnetic nanoparticles, the
surface oxidized FeCo nanoparticles were synthesized by co-precipitation method
with the reduction reaction without any post treatments. As-synthesized FeCo
nanoparticles exhibited the mean diameter of about 39 nm with the oxidized
shell thickness of about 4-5 nm. The saturation magnetization and coercivity
were obtained 172 emu/g and 268 Oe at 300 K, respectively. The heat elevation
of the FeCo magnetic colloid was measured under alternating magnetic fields of
76, 102, and 127 Oe with selectable frequencies of 190, 250 and 355 kHz. The
heat temperature increased up to about 45 oC from initial temperature of 24 oC
under 127 Oe and 355 kHz, which the specific absorption exhibited about 35.7
W/g.


title:
Scattering solutions of Bethe-Salpeter equation in Minkowski and
  Euclidean spaces

abstract:
  We shortly review different methods to obtain the scattering solutions of the
Bethe-Salpeter equation in Minkowski space. We emphasize the possibility to
obtain the zero energy observables in terms of the Euclidean scattering
amplitude.