title:
Local correlations in the attractive 1D Bose gas: from Bethe ansatz to
  the Gross-Pitaevskii equation

abstract:
  We consider the ground-state properties of an extended one-dimensional Bose
gas with pointwise attractive interactions. We take the limit where the
interaction strength goes to zero as the system size increases at fixed
particle density. In this limit the gas exhibits a quantum phase transition. We
compute local correlation functions at zero temperature, both at finite and
infinite size. We provide analytic formulas for the experimentally relevant
one-point functions $g_2$, $g_3$ and analyze their finite-size corrections. Our
results are compared to the mean-field approach based on the Gross-Pitaevskii
equation which yields the exact results in the infinite system size limit, but
not for finite systems.


title:
Dynamic atomic reconstruction: how Fe3O4 thin films evade polar
  catastrophe for epitaxy

abstract:
  Polar catastrophe at the interface of oxide materials with strongly
correlated electrons has triggered a flurry of new research activities. The
expectations are that the design of such advanced interfaces will become a
powerful route to engineer devices with novel functionalities. Here we
investigate the initial stages of growth and the electronic structure of the
spintronic Fe3O4/MgO (001) interface. Using soft x-ray absorption spectroscopy
we have discovered that the so-called A-sites are completely missing in the
first Fe3O4 monolayer. This allows us to develop an unexpected but elegant
growth principle in which during deposition the Fe atoms are constantly on the
move to solve the divergent electrostatic potential problem, thereby ensuring
epitaxy and stoichiometry at the same time. This growth principle provides a
new perspective for the design of interfaces.


title:
The Szeged Index and the Wiener Index of Partial Cubes with Applications
  to Chemical Graphs

abstract:
  In this paper we study the Szeged index of partial cubes and hence generalize
the result proved by V. Chepoi and S. Klav\v{z}ar, who calculated this index
for benzenoid systems. It is proved that the problem of calculating the Szeged
index of a partial cube can be reduced to the problem of calculating the Szeged
indices of weighted quotient graphs with respect to a partition coarser than
$\Theta$-partition. Similar result for the Wiener index was recently proved by
S. Klav\v{z}ar and M. J. Nadjafi-Arani. Furthermore, we show that such quotient
graphs of partial cubes are again partial cubes. Since the results can be used
to efficiently calculate the Wiener index and the Szeged index for specific
families of chemical graphs, we consider $C_4C_8$ systems and show that the two
indices of these graphs can be computed in linear time.


title: Non-Autonomous Forms and Invariance

abstract:
  We generalize the Beurling--Deny--Ouhabaz criterion for parabolic evolution
equations governed by forms to the non-autonomous, non-homogeneous and
semilinear case. Let $V, H$ are Hilbert spaces such that $V$ is continuously
and densely embedded in $H$ and let $\mathcal{A}(t)\colon V\to V^\prime$ be the
operator associated with a bounded $H$-elliptic form $\mathfrak{a}(t,.,.)\colon
V\times V \to \mathbb{C}$ for all $t \in [0,T]$. Suppose $\mathcal{C} \subset
H$ is closed and convex and $P \colon H \to H$ the orthogonal projection onto
$\mathcal{C}$. Given $f \in L^2(0,T;V')$ and $u_0\in \mathcal{C}$, we
investigate whenever the solution of the non-autonomous evolutionary problem \[
u'(t)+\mathcal{A}(t)u(t)=f(t), \quad u(0)=u_0, \] remains in $\mathcal{C}$ and
show that this is the case if
  Pu(t) \in V \quad \text{and} \quad \operatorname{Re}
\mathfrak{a}(t,Pu(t),u(t)-Pu(t)) \ge \operatorname{Re} \langle f(t), u(t)-Pu(t)
\rangle for a.e.\ $t \in [0,T]$. Moreover, we examine necessity of this
condition and apply this result to a semilinear problem.


title:
Recent changes in a flickering variability of the black hole X-ray
  transient V616 Mon = A0620-00

abstract:
  V616 Mon = A0620-00 is a prototype of black hole transient X-ray binaries.
Our 2003-16 optical photometry of the object during X-ray quiescence, obtained
by 50-250 cm telescopes in Crimea, Caucasus Mountains and Slovakia, consists of
~ 7660 CCD frames in Johnson-Cousins $V,R,R_C,I$ bands and the integral light.
During 2003, 2008-9 and 2015-16 passive states, the phase light curve of the
binary exhibited mainly variations caused by an ellipsoidal shape of the red
dwarf component. During 2004-6 and 2009-14 active states a significant
aperiodic broad-band variability (flickering) was present, arising in a black
hole accretion disk and a bright spot, where the mass transfer stream hits the
outer edge of the disk. Long term photometry of our minima times, together with
available positions of superior conjunctions of the red dwarf found from
spectroscopy, allowed us to refine the orbital period of V616 Mon to
0.32301407(5) days.


title: Extension of Configurational Polyhedra to Finite Temperature Property

abstract:
  Configurational polyhedora (CP) is a hyperpolyhedra on multidimensional
configuration space, whose vertex (and edges) corresponds to upper or lower
limit value of correlation functions for all possible atomic configuration on
given lattice. In classical systems where physical property including internal
energy and elastic modulus can be a linear map for structures considered, it is
known that atomic configuration having highest (or lowerst) physical quantity
should always locate on one of the vertices at absolute zero temperature. The
present study extend the idea of CP to finite-temperature property (especially,
focusing on internal energy), and successfully provides demonstration of how
temperature dependence of internal energy in equilibrium state for alloys is
interpreted in terms of the density of states for non-interacting system along
specially selected direction on cofiguration space.


title:
High-precision limit on variation in the fine-structure constant from a
  single quasar absorption system

abstract:
  The brightest southern quasar above redshift $z=1$, HE 0515$-$4414, with its
strong intervening metal absorption-line system at $z_{abs}=1.1508$, provides a
unique opportunity to precisely measure or limit relative variations in the
fine-structure constant ($\Delta\alpha/\alpha$). A variation of just $\sim$3
parts per million (ppm) would produce detectable velocity shifts between its
many strong metal transitions. Using new and archival observations from the
Ultraviolet and Visual Echelle Spectrograph (UVES) we obtain an extremely high
signal-to-noise ratio spectrum (peaking at S/N $\approx250$ pix$^{-1}$). This
provides the most precise measurement of $\Delta\alpha/\alpha$ from a single
absorption system to date, $\Delta\alpha/\alpha=-1.42\pm0.55_{\rm
stat}\pm0.65_{\rm sys}$ ppm, comparable with the precision from previous, large
samples of $\sim$150 absorbers. The largest systematic error in all (but one)
previous similar measurements, including the large samples, was long-range
distortions in the wavelength calibration. These would add a $\sim$2 ppm
systematic error to our measurement and up to $\sim$10 ppm to other
measurements using Mg and Fe transitions. However, we corrected the UVES
spectra using well-calibrated spectra of the same quasar from the High Accuracy
Radial velocity Planet Searcher (HARPS), leaving a residual 0.59 ppm systematic
uncertainty, the largest contribution to our total systematic error. A similar
approach, using short observations on future, well-calibrated spectrographs to
correct existing, high S/N spectra, would efficiently enable a large sample of
reliable $\Delta\alpha/\alpha$ measurements. The high S/N UVES spectrum also
provides insights into analysis difficulties, detector artifacts and systematic
errors likely to arise from 25-40-m telescopes.


title:
Optimal boundary control of a simplified Ericksen--Leslie system for
  nematic liquid crystal flows in $2D$

abstract:
  In this paper, we investigate an optimal boundary control problem for a two
dimensional simplified Ericksen--Leslie system modelling the incompressible
nematic liquid crystal flows. The hydrodynamic system consists of the
Navier--Stokes equations for the fluid velocity coupled with a convective
Ginzburg--Landau type equation for the averaged molecular orientation. The
fluid velocity is assumed to satisfy a no-slip boundary condition, while the
molecular orientation is subject to a time-dependent Dirichlet boundary
condition that corresponds to the strong anchoring condition for liquid
crystals. We first establish the existence of optimal boundary controls. Then
we show that the control-to-state operator is Fr\'echet differentiable between
appropriate Banach spaces and derive first-order necessary optimality
conditions in terms of a variational inequality involving the adjoint state
variables.


title:
Induction and physical theory formation as well as universal computation
  by machine learning

abstract:
  Machine learning presents a general, systematic framework for the generation
of formal theoretical models for physical description and prediction.
Tentatively standard linear modeling techniques are reviewed; followed by a
brief discussion of generalizations to deep forward networks for approximating
nonlinear phenomena and universal computers.


title: Lorentzian Kleinian Groups

abstract:
  Classical Kleinian groups are discrete subgroups of isometries of H n. The
well-known theory of Kleinian groups starts with the definition of their
associated limit set in the boundary of H n , and includes the geometric
properties of the quotient hyperbolic space. This approach, naively applied,
fails in the Lorentzian analogue anti-de Sitter space: discrete subgroups do
not act properly discontinuously, and in many cases the set of accumulation
points of orbits at the conformal boundary at infinity depends on the orbit. In
this survey, we point out a way to extend this classical theory by introducing
causality notions: the theory of limit sets and regularity domains extend
naturally to achronal subgroups. This is closely related to the notions of
globally hyper-bolic spacetimes, and we present what is known about the
classification of globally hyperbolic spacetimes of constant curvature. We also
review the close connection revealed by G. Mess ([79]) between globally
hyperbolic spacetimes of dimension 2 + 1 and Teichm{\"u}ller space. This link
can be understood via the space of time-like geodesics of anti-de Sitter space,
and this space has also an interesting role, presented here, in the recent
works about proper group actions on spacetimes of constant curvature.


title:
$f_0(500)$, $f_0(980)$ and $a_0(980)$ production in the $\chi_{c1} \to
  \eta \pi^+\pi^-$ reaction

abstract:
  We study the $\chi_{c1} \to \eta \pi^+ \pi^-$ decay, paying attention to the
production of $f_0(500)$, $f_0(980)$ and $a_0(980)$ from the final state
interaction of pairs of mesons that can lead to these three mesons in the final
state, which is implemented using the chiral unitary approach. Very clean and
strong signals are obtained for the $a_0(980)$ excitation in the $\eta \pi$
invariant mass distribution and for the $f_0(500)$ in the $\pi^+ \pi^-$ mass
distribution. A smaller, but also clear signal for the $f_0(980)$ excitation is
obtained. The results are contrasted with experimental data and the agreement
found is good, providing yet one more test in support of the picture where
these resonances are dynamically generated from the meson-meson interaction.


title:
Microscopic Calculations of Vortex-Nucleus Interaction in the Neutron
  Star Crust

abstract:
  We investigate the dynamics of a quantized vortex and a nuclear impurity
immersed in a neutron superfluid within a fully microscopic time-dependent
three-dimensional approach. The magnitude and even the sign of the force
between the quantized vortex and the nuclear impurity have been a matter of
debate for over four decades. We determine that the vortex and the impurity
repel at neutron densities, 0.014 fm$^{-3}$ and 0.031 fm$^{-3}$, which are
relevant to the neutron star crust and the origin of glitches, while previous
calculations have concluded that the force changes its sign between these two
densities and predicted contradictory signs. The magnitude of the force
increases with the density of neutron superfluid, while the magnitude of the
pairing gap decreases in this density range.

categories: nucl-th astro-ph.HE cond-mat.quant-gas cond-mat.supr-con


title: Individual Particle Localization per Relativistic de Broglie-Bohm

abstract:
  The significance of the de Broglie-Bohm hidden-particle position in the
relativistic regime is addressed, seeking connection to the (orthodox)
single-particle Newton-Wigner position. The effect of non-positive excursions
of the ensemble density for extreme cases of positive-energy waves is easily
computed using an integral of the equations of motion developed here for free
spin-0 particles in 1+1 dimensions and is interpreted in terms of virtual-like
pair creation and annihilation beneath the Compton wavelength. A Bohmtheoretic
description of the acausal explosion of a specific Newton-Wigner-localized
state is presented in detail. The presence of virtual pairs found is
interpreted as the Bohm picture of the spatial extension beyond single point
particles proposed in the 1960s as to why space-like hyperplane dependence of
the Newton-Wigner wavefunctions may be needed to achieve Lorentz covariance.
For spin-1/2 particles the convective current is speculatively utilized for
achieving parity with the spin-0 theory. The spin-0 improper quantum potential
is generalized to an improper stress tensor for spin-1/2 particles.


title: Predicting the phase behavior of mixtures of active spherical particles

abstract:
  An important question in the field of active matter is whether or not it is
possible to predict the phase behavior of these systems. Here, we study the
phase coexistence of binary mixtures of torque-free active Brownian particles,
for both systems with purely repulsive interactions and systems with
attractions. Using Brownian dynamics simulations, we show that phase
coexistences can be predicted quantitatively for these systems by measuring the
pressure and "reservoir densities". Specifically, in agreement with previous
literature, we find that the coexisting phases are in mechanical equilibrium,
i.e. the two phases have the same pressure. Importantly, we also demonstrate
that the coexisting phases are in chemical equilibrium by bringing each phase
into contact with particle reservoirs, and showing that for each species these
reservoirs are characterized by the same density for both phases. Using this
requirement of mechanical and chemical equilibrium we accurately construct the
phase boundaries from properties which can be measured purely from the
individual coexisting phases. This result highlights that torque-free active
Brownian systems follow simple coexistence rules, thus shedding new light on
their thermodynamics.


title: Probabilistic Saliency Estimation

abstract:
  In this paper, we model the salient object detection problem under a
probabilistic framework encoding the boundary connectivity saliency cue and
smoothness constraints in an optimization problem. We show that this problem
has a closed form global optimum which estimates the salient object. We further
show that along with the probabilistic framework, the proposed method also
enjoys a wide range of interpretations, i.e. graph cut, diffusion maps and
one-class classification. With an analysis according to these interpretations,
we also find that our proposed method provides approximations to the global
optimum to another criterion that integrates local/global contrast and large
area saliency cues. The proposed approach achieves mostly leading performance
compared to the state-of-the-art algorithms over a large set of salient object
detection datasets including around 17k images for several evaluation metrics.
Furthermore, the computational complexity of the proposed method is
favorable/comparable to many state-of-the-art techniques.


title: Twisted Radiation by Electrons in Spiral Motion

abstract:
  We theoretically show that a single free electron in circular/spiral motion
radiates an electromagnetic wave possessing helical phase structure and
carrying orbital angular momentum. We experimentally demonstrate it by
double-slit diffraction on radiation from relativistic electrons in spiral
motion. We show that twisted photons should be created naturally by
cyclotron/synchrotron radiations or Compton scatterings in various situations
in cosmic space. We propose promising laboratory vortex photon sources in
various wavelengths ranging from radio wave to gamma-rays.


title:
The matrix function $e^{tA+B}$ is representable as the Laplace transform
  of a matrix measure

abstract:
  Given a pair $A,B$ of matrices of size $n\times n$, we consider the matrix
function $e^{At+B}$ of the variable $t\in\mathbb{C}$. If the matrix $A$ is
Hermitian, the matrix function $e^{At+B}$ is representable as the bilateral
Laplace transform of a matrix-valued measure $M(d\lambda)$ compactly supported
on the real axis: $$e^{At+B}=\int{}e^{\lambda t}\,M(d\lambda).$$
  The values of the measure $M(d\lambda)$ are matrices of size $n\times n$, the
support of this measure is contained in the convex hull of the spectrum of $A$.
If the matrix $B$ is also Hermitian, then the values of the measure
$M(d\lambda)$ are Hermitian matrices. The measure M(d{\lambda}) is not
necessarily non-negative.


title:
Three dimensional simulations of viscous folding in diverging
  microchannels

abstract:
  Three dimensional simulations on the viscous folding in diverging
microchannels reported by Cubaud and Mason are performed using the parallel
code BLUE for multi-phase flows. The more viscous liquid L_1 is injected into
the channel from the center inlet, and the less viscous liquid L_2 from two
side inlets. Liquid L_1 takes the form of a thin filament due to hydrodynamic
focusing in the long channel that leads to the diverging region. The thread
then becomes unstable to a folding instability, due to the longitudinal
compressive stress applied to it by the diverging flow of liquid L_2. Given the
long computation time, we were limited to a parameter study comprising five
simulations in which the flow rate ratio, the viscosity ratio, the Reynolds
number, and the shape of the channel were varied relative to a reference model.
In our simulations, the cross section of the thread produced by focusing is
elliptical rather than circular. The initial folding axis can be either
parallel or perpendicular to the narrow dimension of the chamber. In the former
case, the folding slowly transforms via twisting to perpendicular folding, or
it may remain parallel. The direction of folding onset is determined by the
velocity profile and the elliptical shape of the thread cross section in the
channel that feeds the diverging part of the cell. Due to the high viscosity
contrast and very low Reynolds numbers, direct numerical simulations of this
two-phase flow are very challenging and to our knowledge these are the first
three-dimensional direct parallel numerical simulations of viscous threads in
microchannels. Our simulations provide good qualitative comparison of the early
time onset of the folding instability however since the computational time for
these simulations is quite long, for such viscous threads, long-time
comparisons with experiments for quantities such as folding frequency are
limited.


title: On generalized modular forms with a cuspidal divisor

abstract:
  In [6], Kohnen proves that if $\Gamma=\Gamma_0(N)$ where $N$ is a square-free
integer, then any modular function of weight $0$ for $\Gamma$ having a divisor
supported at the cusps is an $\eta$-product. Under the condition of having
rational Fourier coefficients, we are able to extend Kohnen's result to the
case where $N$ is the square of a prime. If the rationality condition does not
hold, we show that the statement is no longer true by providing a family of
counter-examples that generalizes naturally the Dedekind $\eta$-function. This
paper fits within the framework of generalized modular forms in the sense of
Knopp and Mason.


title:
SU(N) gauge theories in 2+1 dimensions: glueball spectra and k-string
  tensions

abstract:
  We calculate the low-lying glueball spectrum and various string tensions in
SU(N) lattice gauge theories in 2+1 dimensions, and extrapolate the results to
the continuum limit. We do so for for the range N=2 to N=16 so as to control
the N-dependence with a useful precision. We observe a number of striking
near-degeneracies in the various J^PC sectors of the glueball spectrum, in
particular between C=+ and C=- states. We calculate the string tensions of flux
tubes in a number of representations, and provide evidence that the leading
correction to the N-dependence of the k-string tensions varies as 1/N rather
than 1/N^2, and that the dominant binding of k fundamental flux tubes into a
k-string is via pairwise interactions. We comment on the possible implications
of our results for the dynamics of these gauge theories.


title: Image Decomposition Using a Robust Regression Approach

abstract:
  This paper considers how to separate text and/or graphics from smooth
background in screen content and mixed content images and proposes an algorithm
to perform this segmentation task. The proposed methods make use of the fact
that the background in each block is usually smoothly varying and can be
modeled well by a linear combination of a few smoothly varying basis functions,
while the foreground text and graphics create sharp discontinuity. This
algorithm separates the background and foreground pixels by trying to fit pixel
values in the block into a smooth function using a robust regression method.
The inlier pixels that can be well represented with the smooth model will be
considered as background, while remaining outlier pixels will be considered
foreground. We have also created a dataset of screen content images extracted
from HEVC standard test sequences for screen content coding with their ground
truth segmentation result which can be used for this task. The proposed
algorithm has been tested on the dataset mentioned above and is shown to have
superior performance over other methods, such as the hierarchical k-means
clustering algorithm, shape primitive extraction and coding, and the least
absolute deviation fitting scheme for foreground segmentation.


title:
Modelling high-resolution spatially-resolved Supernova Remnant spectra
  with the Sardinia Radio Telescope

abstract:
  Supernova Remnants (SNRs) exhibit spectra featured by synchrotron radio
emission arising from the relativistic electrons, and high-energy emission from
both leptonic (Bremsstrahlung and Inverse Compton) and hadronic processes
(${\pi}^0$ mesons decay) which are a direct signature of cosmic rays
acceleration. Thanks to radio single-dish imaging observations obtained in
three frequency bands (1.6, 7, 22 GHz) with the Sardinia Radio Telescope
(www.srt.inaf.it), we can model different SNR regions separately. Indeed, in
order to disentangle interesting and peculiar hadron contributions in the
high-energy spectra (gamma-ray band) and better constrain SNRs as cosmic rays
emitters, it is crucial to fully constrain lepton contributions first through
radio-observed parameters. In particular, the Bremsstrahlung and Inverse
Compton bumps observed in gamma-rays are bounded to synchrotron spectral slope
and cut-off in the radio domain. Since these parameters vary for different SNR
regions and electron populations, spatially-resolved radio spectra are then
required for accurate multi-wavelength modelling.


title: C-ITS Deployment in Europe - Current Status and Outlook

abstract:
  Cooperative Intelligent Transport Systems (C-ITS) refers to applications
using vehicle-to-vehicle and vehicle-to-infrastructure communications at a
carrier frequency of 5.9 GHz to increase road traffic safety and road traffic
efficiency in Europe (a.k.a. connected vehicle technology in the US). This
article will shed some light on the current status of C-ITS in Europe and what
is left before deployment can commence in 2019 as announced by C2C-CC. Even
though there is an immense activity for the launch of C-ITS in Europe, the
automotive industry is also planning for the future.


title:
Asymmetric nanowire SQUID: linear CPR, stochastic switching, and
  symmetries

abstract:
  We study nanodevices based on ultrathin superconducting nanowires connected
in parallel to form nanowire SQUIDs. The function of the critical current
versus magnetic field, $I_{C}(B)$, is multivalued, asymmetric and its maxima
and minima are shifted from the usual integer and half integer flux quantum
points. The nanowire interference device is qualitatively distinct from
conventional SQUIDs because nanowires do not obey the same current-phase
relationship (CPR) as Josephson junctions. We demonstrate that the results can
be explained assuming that (i) the CPR is linear and (ii) that each wire is
characterized by a sample-specific critical phase, which is usually much larger
than $\pi/2$. Our proposed model offers accurate fits to $I_{C}(B)$. It
explains the single-valuedness regions where only one vorticity (i.e., the
order parameter winding number) is stable as well as regions where multiple
vorticity values are allowed for the SQUIDs. We also observe and explain
regions in which the standard deviation of the switching current is independent
of the magnetic field. We develop a technique that allows a reliable detection
of hidden phase-slips. Using this technique we find that our model correctly
predicts the boundaries of vorticity regions, even at low currents where
$I_C(B)$ is not directly measurable.


title: Di-Jet Imbalance Measurements at $\sqrt{s_{NN}} = 200$ GeV at STAR

abstract:
  We report the first di-jet transverse momentum asymmetry measurements from
Au+Au and p+p collisions at RHIC. The two highest-energy back-to-back jets
reconstructed from fragments with transverse momenta above 2 GeV/c display a
significantly stronger momentum imbalance in heavy-ion collisions than in the
p+p reference. When re-examined with correlated soft particles included, we
observe that these di-jets then exhibit a unique new feature -- momentum
balance is restored to that observed in p+p for a jet resolution parameter of
R=0.4, while re-balancing is not attained with a smaller value of R=0.2.


title:
Extraction of $t$-slopes from experimental $\gamma p\rightarrow
  K^+\Lambda$ and $\gamma p\rightarrow K^+\Sigma_0$ cross section data

abstract:
  We analyze recent $K^+$ meson photoproduction data from the CLAS
collaboration for the reactions $\gamma p\rightarrow K^+\Lambda$ and $\gamma
p\rightarrow K^+\Sigma_0$, fitting measured forward-angle differential cross
sections to the form $Ae^{Bt}$. We develop a quantitative scheme for
determining the kinematic region where the fit is to be done, and, from the
extracted $t$-slope $B$, determine whether single-Reggeon exchange can explain
the production mechanism. We find that, in the region $5 < s < 8.1$ GeV$^2$,
production of the $K^+\Lambda$ channel can be explained by single $K^+$ Reggeon
exchange, but the $K^+\Sigma_0$ production channel cannot. We verify these
conclusions by fitting the data to a differential cross section produced by the
interfering sum of two exponential amplitudes.


title:
$\phi$ meson self-energy in nuclear matter from $\phi N$ resonant
  interactions

abstract:
  The $\phi$-meson properties in cold nuclear matter are investigated by
implementing resonant $\phi N$ interactions as described in effective
approaches including the unitarization of scattering amplitudes. Several
$N^*$-like states are dynamically generated in these models around $2$ GeV, in
the vicinity of the $\phi N$ threshold. We find that both these states and the
non-resonant part of the amplitude contribute sizably to the $\phi$ collisional
self-energy at finite nuclear density. These contributions are of a similar
strength as the widely studied medium effects from the $\bar K K$ cloud.
Depending on model details (position of the resonances and strength of the
coupling to $\phi N$) we report a $\phi$ broadening up to about $40$-$50$ MeV,
to be added to the $\phi\to\bar K K$ in-medium decay width, and an attractive
optical potential at threshold up to about $35$ MeV at normal matter density.
The $\phi$ spectral function develops a double peak structure as a consequence
of the mixing of resonance-hole modes with the $\phi$ quasi-particle peak. The
former results point in the direction of making up for missing absorption as
reported in $\phi$ nuclear production experiments.


title:
Quantum Pseudo-Telepathy in Spin Systems: Magic Square Game Under
  Magnetic Fields and Dzyaloshinskii-Moriya Interaction

abstract:
  Dzyaloshinskii-Moriya (DM) interaction has been proven to excite entanglement
of spin systems, enhancing the capability of realizing various quantum tasks
such as teleportation. In this work, we consider the DM interaction -to the
best of our knowledge, for the first time in quantum game theory. We study the
winning probability of magic square game played with the thermal entangled
state of spin models under external magnetic fields and DM interaction. We
analytically show that although DM interaction excites the entanglement of the
system as expected, it surprizingly reduces the winning probability of the
game, acting like temperature or magnetic fields, and also show that the
effects of DM interaction and inhomogeneous magnetic field on the winning
probability are identical. In addition, we show that XXZ model is considerably
more robust than XX model against destructive effects. Our results can open new
insights for quantum information processing with spin systems.


title: Observations of Supernova Remnants with the Sardinia Radio Telescope

abstract:
  In the frame of the Astronomical Validation activities for the 64m Sardinia
Radio Telescope, we performed 5-22 GHz imaging observations of the
complex-morphology supernova remnants (SNRs) W44 and IC443. We adopted
innovative observing and mapping techniques providing unprecedented accuracy
for single-dish imaging of SNRs at these frequencies, revealing morphological
details typically available only at lower frequencies through interferometry
observations. High-frequency studies of SNRs in the radio range are useful to
better characterize the spatially-resolved spectra and the physical parameters
of different regions of the SNRs interacting with the ISM. Furthermore,
synchrotron-emitting electrons in the high-frequency radio band are also
responsible for the observed high-energy phenomenology as -e.g.- Inverse
Compton and bremsstrahlung emission components observed in gamma-rays, to be
disentangled from hadron emission contribution (providing constraints on the
origin of cosmic rays).


title: Powers and Magnetization of Blazar Jets

abstract:
  In this work I review the observational constraints imposed on the energetics
and magnetisation of quasar jets, in the context of theoretical expectations.
The discussion is focused on issues regarding the jet production efficiency,
matter content, and particle acceleration. I show that if the ratio of
electron-positron-pairs to protons is of order $15$, as is required to achieve
agreement between jet powers computed using blazar spectral fits and those
computed using radio-lobe calorimetry, the magnetization of blazar jets in
flat-spectrum-radio-quasars (FSRQ) must be significant. This result favors the
reconnection mechanism for particle acceleration and explains the large
Compton-dominance of blazar spectra that is often observed, without the need to
postulate very low jet magnetization.


title:
Optimal Ultra-wide Spatial-Spectral Windows for Hyperentangled
  Two-photon Emission

abstract:
  While being optimally compensated for spatial phase variations, the
two-photon state produced by the two-crystal emission exhibits spatial and
spectral decoherence off the central emission modes. In this paper, we present
an experimentally convenient method to optimize the ultra-wide spatial and
spectral windows; allowing the minimum spatial-spectral decoherence for a
required two-photon flux.


title: Non-equilibrium quantum chains under multi-site Lindblad baths

abstract:
  We study a quantum XX chain coupled to two heat reservoirs that act on
multiple-sites and are kept at different temperatures and chemical potentials.
The baths are described by Lindblad dissipators which are constructed by direct
coupling to the fermionic normal modes of the chain. Using a perturbative
method, we are able to find analytical formulas for all steady-state properties
of the system. We compute both the particle/magnetization current and the
energy current, both of which are found to have the structure of Landauer's
formula. We also obtain exact formulas for the Onsager coefficients. All
properties are found to differ substantially from those of a single-site bath.
In particular, we find a strong dependence on the intensity of the bath
couplings. In the weak coupling regime, we show that the Onsager reciprocal
relations are satisfied.


title: Precise predictions for Dirac neutrino mixing

abstract:
  The neutrino mixing parameters are thoroughly studied using
renormalization-group evolution of Dirac neutrinos with recently proposed
parametrization of the neutrino mixing angles referred as `high-scale mixing
relations'. The correlations among all neutrino mixing and $CP$ violating
observables are investigated. The predictions for the neutrino mixing angle
$\theta_{23}$ are precise, and could be easily tested by ongoing and future
experiments. We observe that the high scale mixing unification hypothesis is
incompatible with Dirac neutrinos due to updated experimental data.


title:
A high-resolution CMOS imaging detector for the search of neutrinoless
  double $\beta$ decay in $^{82}$Se

abstract:
  We introduce high-resolution solid-state imaging detectors for the search of
neutrinoless double $\beta$ decay. Based on the present literature, imaging
devices from amorphous $^{82}$Se evaporated on a complementary
metal-oxide-semiconductor (CMOS) active pixel array could have the energy and
spatial resolution to produce two-dimensional images of ionizing tracks of
utmost quality, effectively akin to an electronic bubble chamber in the double
$\beta$ decay energy regime. Still to be experimentally demonstrated, a
detector consisting of a large array of these devices could have very low
backgrounds, possibly reaching $10^{-7}$/(kg y) in the neutrinoless decay
region of interest (ROI), as it may be required for the full exploration of the
neutrinoless double $\beta$ decay parameter space in the most unfavorable
condition of a strongly quenched nucleon axial coupling constant.


title: Hadron Spectroscopy, exotics and $B_c^+$ physics at LHCb

abstract:
  The LHCb experiment is designed to study properties and decays of heavy
flavored hadrons produced from $pp$ collisions at the LHC. During Run~1, it has
recorded the world's largest data sample of beauty and charm hadrons, enabling
precision spectroscopy studies of such particles. Several important results
obtained by LHCb, such as the discovery of the first pentaquark states and the
first unambiguous determination of the $Z_c(4430)^-$ as an exotic state, have
dramatically increased the interest on spectroscopy of heavy hadrons. An
overview of the latest LHCb results on the subject, including the discovery of
four strange exotic states decaying as $X \to J/\psi \phi$, is presented. LHCb
has also made significant contributions to the field of $B_c^+$ physics, the
lowest bound state of the heavy flavor $\bar{b}$ and $c$ quarks. A synopsis of
the the latest results is given.


title: Muckenhoupt-Wheeden conjectures for sparse operators

abstract:
  We provide an example of a pair of weights $(u,v)$ for which the
Hardy-Littlewood maximal function is bounded from $L^p(v)$ to $L^p(u)$ and from
$L^{p'}(u^{1-p'})$ to $L^{p'}(v^{1-p'})$ while a dyadic sparse operator is not
bounded on the same domain and range. Our construction also provides an example
of a single weight for which the weak-type endpoint does not hold for sparse
operators.


title: { Euclidean, Metric, and Wasserstein } Gradient Flows: an overview

abstract:
  This is an expository paper on the theory of gradient flows, and in
particular of those PDEs which can be interpreted as gradient flows for the
Wasserstein metric on the space of probability measures (a distance induced by
optimal transport). The starting point is the Euclidean theory, and then its
generalization to metric spaces, according to the work of Ambrosio, Gigli and
Savar{\'e}. Then comes an independent exposition of the Wasserstein theory,
with a short introduction to the optimal transport tools that are needed and to
the notion of geodesic convexity, followed by a precise desciption of the
Jordan-Kinderleher-Otto scheme, with proof of convergence in the easiest case:
the linear Fokker-Planck equation. A discussion of other gradient flows PDEs
and of numerical methods based on these ideas is also provided. The paper ends
with a new, theoretical, development, due to Ambrosio, Gigli, Savar{\'e},
Kuwada and Ohta: the study of the heat flow in metric measure spaces.


title: Geometry of Permutation Limits

abstract:
  This paper initiates a limit theory of permutation valued processes, building
on the recent theory of permutons. We apply this to study the asymptotic
behaviour of random sorting networks. We prove that the Archimedean path, the
conjectured limit of random sorting networks, is the unique path from the
identity to the reverse permuton having minimal energy in an appropriate
metric. Together with a recent large deviations result (Kotowski, 2016), it
implies the Archimedean limit for the model of relaxed random sorting networks.


title: VIPLFaceNet: An Open Source Deep Face Recognition SDK

abstract:
  Robust face representation is imperative to highly accurate face recognition.
In this work, we propose an open source face recognition method with deep
representation named as VIPLFaceNet, which is a 10-layer deep convolutional
neural network with 7 convolutional layers and 3 fully-connected layers.
Compared with the well-known AlexNet, our VIPLFaceNet takes only 20% training
time and 60% testing time, but achieves 40\% drop in error rate on the
real-world face recognition benchmark LFW. Our VIPLFaceNet achieves 98.60% mean
accuracy on LFW using one single network. An open-source C++ SDK based on
VIPLFaceNet is released under BSD license. The SDK takes about 150ms to process
one face image in a single thread on an i7 desktop CPU. VIPLFaceNet provides a
state-of-the-art start point for both academic and industrial face recognition
applications.


title:
Scalable Algorithms for Generating and Analyzing Structural Brain
  Networks with a Varying Number of Nodes

abstract:
  Diffusion Magnetic Resonance Imaging (MRI) exploits the anisotropic diffusion
of water molecules in the brain to enable the estimation of the brain's
anatomical fiber tracts at a relatively high resolution. In particular,
tractographic methods can be used to generate whole-brain anatomical
connectivity matrix where each element provides an estimate of the connectivity
strength between the corresponding voxels. Structural brain networks are built
using the connectivity information and a predefined brain parcellation, where
the nodes of the network represent the brain regions and the edge weights
capture the connectivity strengths between the corresponding brain regions.
This paper introduces a number of novel scalable methods to generate and
analyze structural brain networks with a varying number of nodes. In
particular, we introduce a new parallel algorithm to quickly generate large
scale connectivity-based parcellations for which voxels in a region possess
highly similar connectivity patterns to the rest of the regions. We show that
the corresponding regional structural consistency is always superior to
randomly generated parcellations over a wide range of parcellation sizes.
Corresponding brain networks with a varying number of nodes are analyzed using
standard graph-theorectic measures, as well as, new measures derived from
spectral graph theory. Our results indicate increasingly more statistical power
of brain networks with larger numbers of nodes and the relatively unique shape
of the spectral profile of large brain networks relative to other well-known
networks.


title: Crafting a multi-task CNN for viewpoint estimation

abstract:
  Convolutional Neural Networks (CNNs) were recently shown to provide
state-of-the-art results for object category viewpoint estimation. However
different ways of formulating this problem have been proposed and the competing
approaches have been explored with very different design choices. This paper
presents a comparison of these approaches in a unified setting as well as a
detailed analysis of the key factors that impact performance. Followingly, we
present a new joint training method with the detection task and demonstrate its
benefit. We also highlight the superiority of classification approaches over
regression approaches, quantify the benefits of deeper architectures and
extended training data, and demonstrate that synthetic data is beneficial even
when using ImageNet training data. By combining all these elements, we
demonstrate an improvement of approximately 5% mAVP over previous
state-of-the-art results on the Pascal3D+ dataset. In particular for their most
challenging 24 view classification task we improve the results from 31.1% to
36.1% mAVP.


title:
Lepton mass and mixing in a simple extension of the Standard Model based
  on T7 flavor symmetry

abstract:
  A simple Standard Model Extension based on $T_7$ flavor symmetry which
accommodates lepton mass and mixing with non-zero $\theta_{13}$ and CP
violation phase is proposed. At the tree- level, the realistic lepton mass and
mixing pattern is derived through the spontaneous symmetry breaking by just one
vacuum expectation value ($v$) which is the same as in the Standard Model.
Neutrinos get small masses from one $SU(2)_L$ doublet and two $SU(2)_L$
singlets in which one being in $\underline{1}$ and the two others in
$\underline{3}$ and $\underline{3}^*$ under $T_7$ , respectively. The model
also gives a remarkable prediction of Dirac CP violation
$\delta_{CP}=172.598^\circ$ in both normal and inverted hierarchies which is
still missing in the neutrino mixing matrix.


title:
HI Observations of Galaxies in the Southern Filament of the Virgo
  Cluster with the SKA Pathfinder KAT-7 and the WSRT

abstract:
  We map the Hi distribution of galaxies in a $\sim 1.5^\circ \times 2.5^\circ$
region located at the virial radius south of the Virgo cluster using the
KAT$-$7 and the WSRT interferometers. Because of the different beam sizes of
the two telescopes, a similar column density sensitivity of $\rm N_{Hi} \sim
10^{18}\,cm^{-2}$ was reached with the two observations over 16.5 km/s. We
pioneer a new approach to combine the observations and take advantage of their
sensitivity to both the large and small scale structures. Out to an
unprecedented extent, we detect an Hi tail of $\sim 60$ kpc being stripped off
NGC 4424, a peculiar spiral galaxy. The properties of the galaxy, together with
the shape of the tail, suggest that NGC 4424 is a post-merger galaxy undergoing
a ram pressure stripping as it falls towards the centre of the Virgo Cluster.
We detect a total of 14 galaxies and 3 Hi clouds lacking optical counterparts.
One of the clouds is a new detection with an Hi mass of $\rm 7\times10^7\,
M_\odot$ and a strong Hi profile with $W_{50} = 73$ km/s. We find that 10 out
of the 14 galaxies present Hi deficiencies not higher than those of the
cluster's late spirals, suggesting that the environmental effects are not more
pronounced in the region than elsewhere in the cluster.


title:
Design of a Ternary Edge-Triggered D Flip-Flap-Flop for Multiple-Valued
  Sequential Logic

abstract:
  Development of large computerized systems requires both combinational and
sequential circuits. Registers and counters are two important examples of
sequential circuits, which are widely used in practical applications like CPUs.
The basic element of sequential logic is Flip-Flop, which stores an input value
and returns two outputs (Q and Q_bar). This paper presents an innovative
ternary D Flip-Flap-Flop, which offers circuit designers to customize their
design by eliminating one of the outputs if it is not required. This unique
feature of the new design leads to considerable power reduction in comparison
with the previously presented structures. The proposed design is simulated and
tested by HSPICE and 45 nm CMOS technology.


title:
Measurement of electrons from beauty-hadron decays in p-Pb collisions at
  $\sqrt{s_{\rm NN}}=5.02$ TeV and Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$
  TeV

abstract:
  The production of beauty hadrons was measured via semi-leptonic decays at
mid-rapidity with the ALICE detector at the LHC in the transverse momentum
interval $1<p_{\rm T}<8$ GeV/$c$ in minimum-bias p-Pb collisions at
$\sqrt{s_{\rm NN}}=5.02$ TeV and in $1.3<p_{\rm T}<8$ GeV/$c$ in the 20% most
central Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV. The pp reference
spectra at $\sqrt{s}=5.02$ TeV and $\sqrt{s}=2.76$ TeV, needed for the
calculation of the nuclear modification factors $R_{\rm pPb}$ and $R_{\rm
PbPb}$, were obtained by a pQCD-driven scaling of the cross section of
electrons from beauty-hadron decays measured at $\sqrt{s}=7$ TeV. In the
$p_{\rm T}$ interval $3<p_{\rm T}<8$ GeV/$c$ a suppression of the yield of
electrons from beauty-hadron decays is observed in Pb-Pb compared to pp
collisions. Towards lower $p_{\rm T}$, the $R_{\rm PbPb}$ values increase with
large systematic uncertainties. The $R_{\rm pPb}$ is consistent with unity
within systematic uncertainties and is well described by theoretical
calculations that include cold nuclear matter effects in p-Pb collisions. The
measured $R_{\rm pPb}$ and these calculations indicate that cold nuclear matter
effects are small at high transverse momentum also in Pb-Pb collisions.
Therefore, the observed reduction of $R_{\rm PbPb}$ below unity at high $p_{\rm
T}$ may be ascribed to an effect of the hot and dense medium formed in Pb-Pb
collisions.


title:
Probing Acceleration and Turbulence at Relativistic Shocks in Blazar
  Jets

abstract:
  Diffusive shock acceleration (DSA) at relativistic shocks is widely thought
to be an important acceleration mechanism in various astrophysical jet sources,
including radio-loud active galactic nuclei such as blazars. Such acceleration
can produce the non-thermal particles that emit the broadband continuum
radiation that is detected from extragalactic jets. An important recent
development for blazar science is the ability of Fermi-LAT spectroscopy to pin
down the shape of the distribution of the underlying non-thermal particle
population. This paper highlights how multi-wavelength spectra spanning optical
to X-ray to gamma-ray bands can be used to probe diffusive acceleration in
relativistic, oblique, magnetohydrodynamic (MHD) shocks in blazar jets.
Diagnostics on the MHD turbulence near such shocks are obtained using thermal
and non-thermal particle distributions resulting from detailed Monte Carlo
simulations of DSA. These probes are afforded by the characteristic property
that the synchrotron $\nu F_{\nu}$ peak energy does not appear in the gamma-ray
band above 100 MeV. We investigate self-consistently the radiative synchrotron
and inverse Compton signatures of the simulated particle distributions.
Important constraints on the diffusive mean free paths of electrons, and the
level of electromagnetic field turbulence are identified for three different
case study blazars, Mrk 501, BL Lacertae and AO 0235+164. The X-ray excess of
AO 0235+164 in a flare state can be modelled as the signature of bulk Compton
scattering of external radiation fields, thereby tightly constraining the
energy-dependence of the diffusion coefficient for electrons. The concomitant
interpretations that turbulence levels decline with remoteness from jet shocks,
and the probable significant role for non-gyroresonant diffusion, are posited.


title:
Matter of Life & Death: The impact of environmental conditions on the
  origins of stars and supermassive black holes

abstract:
  Observational evidence suggests that some very large supermassive black holes
(SMBHs) already existed less than 1 Gyr after the Big Bang. Explaining the
formation and growth of the 'seeds' of these SMBHs is quite challenging. We
explore the formation of such seeds in the direct collapse scenario. Using 3D
hydrodynamical simulations, we investigate the impact of turbulence and
rotation on the fragmentation behavior of collapsing primordial gas in the
presence of a strong UV radiation background, which keeps the gas hot.
Additionally, we explore different ways in which the collapsing gas may be able
to stay hot, and thus limit fragmentation. Using a one-zone model, we examine
the interplay between magnetic fields, turbulence, and a UV radiation
background.
  Feedback processes from stars and black holes shape the interstellar medium
(ISM) out of which new generations of luminous objects form. To understand the
properties of these objects, e.g. the stellar initial mass function, it is
vital to have knowledge of the chemical and thermodynamical properties of the
feedback-regulated ISM. To better understand the chemo-thermal state and
fragmentation behavior of gas in high-redshift galaxies, we updated, improved,
and extended a photodissociation region code. Our computational code, PDR-Zz,
is described in detail. Using this code, a grid of models is run, covering a
sizable range in physical properties. This allows us to systematically explore
the overall impact of various feedback effects, both radiative and chemical, on
the chemical and thermal balance of the gas in different physical regimes.


title:
Atoms and Molecules in Cavities: From Weak to Strong Coupling in QED
  Chemistry

abstract:
  In this work, we provide an overview of how well-established concepts in the
fields of quantum chemistry and material sciences have to be adapted when the
quantum nature of light becomes important in correlated matter-photon problems.
Therefore, we analyze model systems in optical cavities, where the
matter-photon interaction is considered from the weak- to the strong coupling
limit and for individual photon modes as well as for the multi-mode case. We
identify fundamental changes in Born-Oppenheimer surfaces, spectroscopic
quantities, conical intersections and efficiency for quantum control. We
conclude by applying our novel recently developed quantum-electrodynamical
density-functional theory to single-photon emission and show how a
straightforward approximation accurately describes the correlated
electron-photon dynamics. This paves the road to describe matter-photon
interactions from first-principles and addresses the emergence of new states of
matter in chemistry and material science.


title: Quasinormal-mode expansion of the scattering matrix

abstract:
  It is well known that the quasinormal modes (or resonant states) of photonic
structures can be associated with the poles of the scattering matrix of the
system in the complex-frequency plane. In this work, the inverse problem, i.e.,
the reconstruction of the scattering matrix from the knowledge of the
quasinormal modes, is addressed. We develop a general and scalable
quasinormal-mode expansion of the scattering matrix, requiring only the complex
eigenfrequencies and the far-field properties of the eigenmodes. The theory is
validated by applying it to illustrative nanophotonic systems with multiple
overlapping electromagnetic modes. The examples demonstrate that our theory
provides an accurate first-principle prediction of the scattering properties,
without the need for postulating ad-hoc nonresonant channels.


title: A photo-evaporative gap in the closest planet forming disc

abstract:
  The dispersal of the circumstellar discs of dust and gas surrounding young
low- mass stars has important implications for the formation of planetary
systems. Photo- evaporation from energetic radiation from the central object is
thought to drive the dispersal in the majority of discs, by creating a gap
which disconnects the outer from the inner regions of the disc and then
disperses the outer disc from the inside-out, while the inner disc keeps
draining viscously onto the star. In this Letter we show that the disc around
TW Hya, the closest protoplanetary disc to Earth, may be the first object where
a photoevaporative gap has been imaged around the time at which it is being
created. Indeed the detected gap in the ALMA images is consistent with the
expectations of X-ray photoevaporation models, thus not requiring the presence
of a planet. The photoevaporation model is also consistent with a broad range
of properties of the TW Hya system, e.g. accretion rate and the location of the
gap at the onset of dispersal. We show that the central, unresolved 870 {\mu}m
continuum source might be produced by free free emission from the gas and/or
residual dust inside the gap.


title: Polynomial Hessians with small rank

abstract:
  In this paper, the results in [Singular Hessians, J. Algebra 282 (2004), no.
1, 195--204], for polynomial Hessians with determinant zero in small dimensions
$r+1$, are generalized to similar results in arbitrary dimension, for
polynomial Hessians with rank $r$. All of this is over a field $K$ of
characteristic zero. The results in [Singular Hessians, J. Algebra 282 (2004),
no. 1, 195--204] are also reproved in a different perspective.
  One of these results is the classification by Gordan and Noether of
homogeneous polynomials in $5$ variables, for which the Hessians determinant is
zero. This result is generalized to homogeneous polynomials in general, for
which the Hessian rank is 4. Up to a linear transformation, such a polynomial
is either contained in $K[x_1,x_2,x_3,x_4]$, or contained in $$
K[x_1,x_2,p_3(x_1,x_2)x_3+p_4(x_1,x_2)x_4+\cdots+p_n(x_1,x_2)x_n] $$ for
certain $p_3,p_4,\ldots,p_n \in K[x_1,x_2]$ which are homogeneous of the same
degree.
  Furthermore, a new result which is similar to those in [Singular Hessians, J.
Algebra 282 (2004), no. 1, 195--204], is added, namely about polynomials $h \in
K[x_1,x_2,x_3,x_4,x_5]$, for which the last four rows of the Hessian matrix of
$t h$ are dependent. Here, $t$ is a variable, which is not one of those with
respect to which the Hessian is taken. This result is generalized to arbitrary
dimension as well: the Hessian rank of $t h$ is $4$ and the first row of the
Hessian matrix of $t h$ is independent of the other rows.


title: Transits Probabilities Around Hypervelocity and Runaway Stars

abstract:
  In the blooming field of exoplanetary science, NASA's Kepler Space Telescope
has revolutionized our understanding of exoplanets. Kepler's very precise and
long-duration photometry is ideal for detecting planetary transits around
Sun-like stars. The forthcoming Transiting Exoplanet Survey Satellite (TESS) is
expected to continue Kepler's legacy. Along with transits, the Doppler
technique remains an invaluable tool for discovering planets. The next
generation of spectrographs, such as G-CLEF, promises precision radial velocity
measurements. In this paper, we explore the possibility of detecting planets
around hypervelocity and runaway stars, which should host a very compact system
as consequence of their turbulent origin. We find that the probability of a
multi-planetary transit is $10^{-3}\lesssim P\lesssim 10^{-1}$. We therefore
need to observe $\sim 10-1000$ high-velocity stars to spot a transit. However,
even if transits are rare around runaway and hypervelocity stars, the chances
of detecting such planets using radial velocity surveys is high. We predict
that the European Gaia satellite, along with TESS and the new-generation
spectrographs G-CLEF and ESPRESSO, will spot planetary systems orbiting
high-velocity stars.


title:
Potassium detection in the clear atmosphere of a hot-Jupiter: FORS2
  transmission spectroscopy of WASP-17b

abstract:
  We present FORS2 (attached to ESO's Very Large Telescope) observations of the
exoplanet WASP-17b during its primary transit, for the purpose of differential
spectrophotometry analysis. We use the instrument in its Mask eXchange Unit
(MXU) mode to simultaneously obtain low resolution spectra of the planet
hosting star, as well as several reference stars in the field of view. The
integration of these spectra within broadband and smaller 100$\AA$ bins
provides us with 'white' and spectrophotometric light curves, from 5700 to
8000$\AA$. Through modelling the white light curve, we obtain refined bulk and
transit parameters of the planet, as well as wavelength-dependent variations of
the planetary radius from smaller spectral bins through which the transmission
spectrum is obtained. The inference of transit parameters, as well as the noise
statistics, is performed using a Gaussian Process model. We achieve a typical
precision in the transit depth of a few hundred parts per million from various
transit light curves. From the transmission spectra we rule out a flat spectrum
at >3$\sigma$ and detect marginal presence of the pressure-broadened sodium
wings. Furthermore, we detect the wing of the potassium absorption line in the
upper atmosphere of the planet with 3$\sigma$ confidence, both facts pointing
to a relatively shallow temperature gradient of the atmosphere. These
conclusions are mostly consistent with previous studies of this exo-atmosphere,
although previous potassium measurements have been inconclusive.


title: A proposed very high energy electron-proton collider, VHEeP

abstract:
  The possibility of using plasma wakefield acceleration to build a very high
energy electron-proton (VHEeP) collider at a centre-of-mass energy of 9 TeV was
presented at the DIS2015 workshop. In this talk, the physics case was further
developed and the idea has since been published as a journal paper. A brief
summary is here given along with some details of the technical aspects not
covered in the paper, which focused on the physics motivation. It is
demonstrated that an $ep$ collider with a centre-of-mass energy a factor of 30
above HERA has sensitivity to new physical phenomena.


title:
A generalized bayesian inference method for constraining the interiors
  of super Earths and sub-Neptunes

abstract:
  We aim to present a generalized Bayesian inference method for constraining
interiors of super Earths and sub-Neptunes. Our methodology succeeds in
quantifying the degeneracy and correlation of structural parameters for high
dimensional parameter spaces. Specifically, we identify what constraints can be
placed on composition and thickness of core, mantle, ice, ocean, and
atmospheric layers given observations of mass, radius, and bulk refractory
abundance constraints (Fe, Mg, Si) from observations of the host star's
photospheric composition. We employed a full probabilistic Bayesian inference
analysis that formally accounts for observational and model uncertainties.
Using a Markov chain Monte Carlo technique, we computed joint and marginal
posterior probability distributions for all structural parameters of interest.
We included state-of-the-art structural models based on self-consistent
thermodynamics of core, mantle, high-pressure ice, and liquid water.
Furthermore, we tested and compared two different atmospheric models that are
tailored for modeling thick and thin atmospheres, respectively. First, we
validate our method against Neptune. Second, we apply it to synthetic
exoplanets of fixed mass and determine the effect on interior structure and
composition when (1) radius, (2) atmospheric model, (3) data uncertainties, (4)
semi-major axes, (5) atmospheric composition (i.e., a priori assumption of
enriched envelopes versus pure H/He envelopes), and (6) prior distributions are
varied. Our main conclusions are: [...]


title:
Bayesian analysis of interiors of HD 219134b, Kepler-10b, Kepler-93b,
  CoRoT-7b, 55 Cnc e, and HD 97658b using stellar abundance proxies

abstract:
  Using a generalized Bayesian inference method, we aim to explore the possible
interior structures of six selected exoplanets for which planetary mass and
radius measurements are available in addition to stellar host abundances:
HD~219134b, Kepler-10b, Kepler-93b, CoRoT-7b, 55~Cnc~e, and HD~97658b. We aim
to investigate the importance of stellar abundance proxies for the planetary
bulk composition (namely Fe/Si and Mg/Si) on prediction of planetary interiors.
We performed a full probabilistic Bayesian inference analysis to formally
account for observational and model uncertainties while obtaining confidence
regions of structural and compositional parameters of core, mantle, ice layer,
ocean, and atmosphere. We determined how sensitive our parameter predictions
depend on (1) different estimates of bulk abundance constraints and (2)
different correlations of bulk abundances between planet and host star. [...]
Although the possible ranges of interior structures are large, structural
parameters and their correlations are constrained by the sparse data. The
probability for the tested exoplanets to be Earth-like is generally very low.
Furthermore, we conclude that different estimates of planet bulk abundance
constraints mainly affect mantle composition and core size.


title: The 5 MeV bump - a nuclear whodunit mystery

abstract:
  We perform a combined analysis of recent NEOS and Daya Bay data on the
reactor antineutrino spectrum. This analysis includes approximately 1.5 million
antineutrino events, which is the largest neutrino event sample analyzed to
date. We use a double ratio which cancels flux model dependence and related
uncertainties as well as the effects of the detector response model. We find at
3-4 standard deviation significance level, that plutonium-239 and plutonium-241
are disfavored as the single source for the the so-called 5 MeV bump. This
analysis method has general applicability and in particular with higher
statistics data sets will be able to shed significant light on the issue of the
bump. With some caveat this also should allow to improve the sensitivity for
sterile neutrino searches in NEOS.


title: Entanglement verification with detection-efficiency mismatch

abstract:
  The security analysis of quantum key distribution is difficult to perform
when there is efficiency mismatch between various threshold detectors involved
in an experimental setup. Even the verification that the device actually
performs in the quantum domain, referred to as the task of entanglement
verification, is hard to perform. In this article we provide such an
entanglement-verification method for characterized detection-efficiency
mismatch. Our method does not rely on a cut-off of photon numbers in the
optical signal. It can be applied independently of the degrees of freedom
involved, thus covering, for example, efficiency mismatch in polarization and
time-bin modes, but also in spatial modes. The evaluation of typical
experimental scenarios suggests that an increase of detection-efficiency
mismatch will drive the performance of a given setup out of the quantum domain.


title: Information Theoretic Structure Learning with Confidence

abstract:
  Information theoretic measures (e.g. the Kullback Liebler divergence and
Shannon mutual information) have been used for exploring possibly nonlinear
multivariate dependencies in high dimension. If these dependencies are assumed
to follow a Markov factor graph model, this exploration process is called
structure discovery. For discrete-valued samples, estimates of the information
divergence over the parametric class of multinomial models lead to structure
discovery methods whose mean squared error achieves parametric convergence
rates as the sample size grows. However, a naive application of this method to
continuous nonparametric multivariate models converges much more slowly. In
this paper we introduce a new method for nonparametric structure discovery that
uses weighted ensemble divergence estimators that achieve parametric
convergence rates and obey an asymptotic central limit theorem that facilitates
hypothesis testing and other types of statistical validation.


title:
Self-similar finite-time singularity formation in degenerate parabolic
  equations arising in thin-film flows

abstract:
  A thin liquid film coating a planar horizontal substrate may be unstable to
perturbations in the film thickness due to unfavourable intermolecular
interactions between the liquid and the substrate, which may lead to
finite-time rupture. The self-similar nature of the rupture has been studied
before by utilizing the standard lubrication approximation along with the
Derjaguin (or disjoining) pressure formalism used to account for the
intermolecular interactions, and a particular form of the disjoining pressure
with exponent $n=3$ has been used, namely, $\Pi(h)\propto -1/h^{3}$, where $h$
is the film thickness. In the present study, we use a numerical continuation
method to compute discrete solutions to self-similar rupture for a general
disjoining pressure exponent $n$. We focus on axisymmetric point-rupture
solutions and show that pairs of solution branches merge as $n$ decreases,
leading to a critical value $n_c \approx 1.485$ below which stable similarity
solutions do not appear to exist. We verify that this observation also holds
true for plane-symmetric line-rupture solutions for which the critical value
turns out to be slightly larger than for the axisymmetric case,
$n_c^{\mathrm{plane}}\approx 1.5$. Computation of the full time-dependent
problem also demonstrates the loss of stable similarity solutions and the
subsequent onset of cascading oscillatory structures.


title: On the dimension of triangular self-affine sets

abstract:
  As a continuation of a recent work of the same authors (arXiv:1504.07138), in
this note we study the dimension theory of diagonally homogeneous triangular
planar self-affine IFS.


title: Results on escaping set of an entire function and its composition

abstract:
  Given two permutable entire functions $f$ and $g,$ we establish vital
relationship between escaping sets of entire functions $f, g$ and their
composition. We provide some families of transcendental entire functions for
which Eremenko's conjecture holds. In addition, we investigate the dynamical
properties of the mapping $f(z)=z+1+e^{-z}.$


title: Conditions for the generation of spin currents in spin-Hall devices

abstract:
  We investigate the out-of-equilibrium stationary states of spin-Hall devices
on the basis of the least dissipation principle. We show that, for a bulk
paramagnet with spin-orbit interaction, in the case of the Hall bar geometry
the principle of minimum dissipated power prevents the generation of transverse
spin and charge currents while in the case of the Corbino disk geometry,
transverse currents can be produced. More generally, we show that electric
charge accumulation prevents the stationary spin to charge current conversion.


title:
Separation equations for 2D superintegrable systems on constant
  curvature spaces

abstract:
  Second-order conformal quantum superintegrable systems in 2 dimensions are
Laplace equations on a manifold with an added scalar potential and $3$
independent 2nd order conformal symmetry operators. They encode all the
information about 2D Helmholtz or time-independent Schr\"odinger
superintegrable systems in an efficient manner: Each of these systems admits a
quadratic symmetry algebra (not usually a Lie algebra) and is multiseparable.
We study the separation equations for the systems as a family rather than
separate cases. We show that the separation equations comprise all of the
various types of hypergeometric and Heun equations in full generality. In
particular, they yield all of the 1D Schr\"odinger exactly solvable (ES) and
quasi-exactly solvable (QES) systems related to the Heun operator. We focus on
complex constant curvature spaces and show explicitly that there are 8 pairs of
Laplace separation types and these types account for all separable coordinates
on the 20 flat space and 9 2-sphere Helmholtz superintegrable systems,
including those for the constant potential case. The different systems are
related by St\"ackel transforms, by the symmetry algebras and by B\"ocher
contractions of the conformal algebra so(4,C) to itself, which enables all
systems to be derived from a single one: the generic potential on the complex
2-sphere. This approach facilitates a unified view of special function theory,
incorporating hypergeometric and Heun functions in full generality.


title:
Selective Purcell enhancement of two closely linked zero-phonon
  transitions of a silicon carbide color center

abstract:
  Point defects in silicon carbide are rapidly becoming a platform of great
interest for single photon generation, quantum sensing, and quantum information
science. Photonic crystal cavities (PCC) can serve as an efficient light-matter
interface both to augment the defect emission and to aid in studying the
defects' properties. In this work, we fabricate 1D nanobeam PCCs in 4H-silicon
carbide with embedded silicon vacancy centers. These cavities are used to
achieve Purcell enhancement of two closely spaced defect zero-phonon lines
(ZPL). Enhancements of >80-fold are measured using multiple techniques.
Additionally, the nature of the cavity coupling to the different ZPLs is
examined.


title: Explicit Evaluation of Double Gauss Sums

abstract:
  We present an explicit evaluation of the double Gauss sum $\displaystyle
G(a,b,c;S;p^n):=\sum_{x,y=0}^{p^n-1} e^{2\pi i S(ax^2+bxy+cy^2)/p^n}$, where
$a, b, c$ are integers such that $\gcd(a,b,c)=1$, $p$ is a prime, $n$ is a
positive integer, and $S$ is an integer coprime to $p$.


title:
Measurement of the inclusive cross-sections of single top-quark and
  top-antiquark $t$-channel production in $pp$ collisions at $\sqrt{s}$ = 13
  TeV with the ATLAS detector

abstract:
  A measurement of the $t$-channel single-top-quark and single-top-antiquark
production cross-sections in the lepton+je ts channel is presented, using 3.2
fb$^{-1}$ of proton--proton collision data at a centre-of-mass energy of 13
TeV, recorded with the ATLAS detector at the LHC in 2015. Events are selected
by requiring one charged lepton (electron or muon), missing transverse
momentum, and two jets with high transverse momentum, exactly one of which is
required to be $b$-tagged. Using a binned maximum-likelihood fit to the
discriminant distribution of a neural network, the cross-sections are
determined to be $\sigma(tq) = 156 \pm 5 \, (\mathrm{stat.}) \pm 27 \,
(\mathrm{syst.}) \pm 3\,(\mathrm{lumi.})$ pb for single top-quark production
and $\sigma(\bar{t}q) = 91 \pm 4 \, (\mathrm{stat.}) \pm 18 \, (\mathrm{syst.})
\pm 2\,(\mathrm{lumi.})$ pb for single top-antiquark production, assuming a
top-quark mass of 172.5 GeV. The cross-section ratio is measured to be $R_t =
\sigma(tq)/\sigma(\bar{t}q) = 1.72 \pm 0.09 \, (\mathrm{stat.}) \pm 0.18 \,
(\mathrm{syst.})$.


title:
Elastic constants of hcp $^{4}$He: Path-integral Monte Carlo results
  versus experiment

abstract:
  The elastic constants of hcp $^{4}$He are computed using the path-integral
Monte Carlo (PIMC) method. The stiffness coefficients are obtained by imposing
different distortions to a periodic cell containing 180 atoms, followed by
measurement of the elements of the corresponding stress tensor. For this
purpose an appropriate path-integral expression for the stress tensor
observable is derived and implemented into the PIMC++ package. In addition to
allowing the determination of the elastic stiffness constants, this development
also opens the way to an explicit atomistic determination of the Peierls stress
for dislocation motion using the PIMC technique. A comparison of the results to
available experimental data shows an overall good agreement of the density
dependence of the elastic constants, with the single exception of C$_{13}$.
Additional calculations for the bcc phase, on the other hand, show good
agreement for \textit{all} elastic constants.


title:
Hyperbolic periodic orbits in nongradient systems and
  small-noise-induced metastable transitions

abstract:
  Small noise can induce rare transitions between metastable states, which can
be characterized by Maximum Likelihood Paths (MLPs). Nongradient systems
contrast gradient systems in that MLP does not have to cross the separatrix at
a saddle point, but instead possibly at a point on a hyperbolic periodic orbit.
A numerical approach for identifying such unstable periodic orbits is proposed
based on String method. In a special class of nongradient systems
(`orthogonal-type'), there are provably local MLPs that cross such saddle point
or hyperbolic periodic orbit, and the separatrix crossing location determines
the associated local maximum of transition rate. In general cases, however, the
separatrix crossing may not determine a unique local maximum of the rate, as we
numerically observed a counter-example in a sheared 2D-space Allen-Cahn SPDE.
It is a reasonable conjecture that there are always local MLPs associated with
each attractor on the separatrix, such as saddle point or hyperbolic periodic
orbit; our numerical experiments did not disprove so.


title:
Modeling the lowest-cost splitting of a herd of cows by optimizing a
  cost function

abstract:
  Animals live in groups to defend against predation and to obtain food.
However, for some animals --- especially ones that spend long periods of time
feeding --- there are costs if a group chooses to move on before their
nutritional needs are satisfied. If the conflict between feeding and keeping up
with a group becomes too large, it may be advantageous to some animals to split
into subgroups of animals with similar nutritional needs. We model the costs
and benefits of splitting by a herd of cows using a cost function (CF) that
quantifies individual variation in hunger, desire to lie down, and predation
risk. We model the costs associated with hunger and lying desire as the
standard deviations of individuals within a group, and we model predation risk
as an inverse exponential function of group size. We minimize the cost function
over all plausible groups that can arise from a given herd and study the
dynamics of group splitting. We explore our model using two examples: (1) we
consider group switching and group fission in a herd of relatively homogeneous
cows; and (2) we examine a herd with an equal number of adult males (larger
animals) and adult females (smaller animals).


title: Non-semigroup gradings of associative algebras

abstract:
  It is known that there are Lie algebras with non-semigroup gradings, i.e.
such that the binary operation on the grading set is not associative. We
provide a similar example in the class of associative algebras.


title:
The qualitative analysis of the impact of media delay on the control of
  infectious disease

abstract:
  In this paper, we consider the impact of time delay by media on the control
of the disease. We set up a class of SISM epidemic model with the time delay
and the cumulative density of awareness caused by media. The sufficient
condition of global asymptotic stability of disease-free equilibrium is
approved. We get the global stability of the epidemic equilibrium and the
existence conditions of Hopf bifurcation. Numerical simulations are presented
to illustrate the analytical results. Finally, we analyze the influence of
parameters on the control of infectious disease by combining the data of H1N1.
By shortening the time of media lag, increasing transmission rate of media and
the implementation rate of the media project, the spread of disease will be
controlled effectively.


title:
The Dynamic Behavior (Effects) of Impulsive Toxicant Input on a
  Single-Species Population in a Small Polluted Environment

abstract:
  In this paper, we study a single-species population model with pulse toxicant
input to a small polluted environment. The intrinsic rate of population is
affected by environment and toxin in organisms. The toxin in organisms is
influenced by toxin in environment and the food chain. A new mathematical model
is derived. By the Pulse Compare Theorem, we find the surviving threshold of
the population and obtain the sufficient conditions of persistence and
extinction of the population.


title:
Energy loss as the origin of an universal scaling law of the elliptic
  flow

abstract:
  It is shown that the excellent scaling of the elliptic flow found for all
centralities, species and energies from RHIC to the LHC for $p_{T}$ less than
the saturation momentum is a consequence of the energy lost by a parton
interacting with the color field produced in a nucleus-nucleus collision. In
particular, the deduced shape of the scaling curve describes correctly all the
data. We discuss the possible extensions to higher $p_{T}$, proton-nucleus and
proton-proton collisions as well as higher harmonics.


title:
Diffusion in plasma: the Hall effect, compositional waves, and chemical
  spots

abstract:
  We consider diffusion caused by a combined influence of the electric current
and the Hall effect, and argue that such diffusion can form inhomogeneities of
the chemical composition in plasma. The considered mechanism can be responsible
for a formation of element spots in laboratory and astrophysical plasmas. This
current-driven diffusion can be accompanied by propagation of a particular type
waves in which the impurity number density oscillate alone. These compositional
waves exist if the magnetic pressure in plasma is much greater than the gas
pressure,


title: The local magnetic ray transform of tensor fields

abstract:
  In this paper we study the local magnetic ray transform of symmetric tensor
fields up to rank two on a Riemannian manifold of dimension $\geq 3$ with
boundary. In particular, we consider the magnetic ray transform of the
combinations of tensors of different orders due to the nature of magnetic
flows. We show that such magnetic ray transforms can be stably inverted, up to
natural obstructions, near a strictly convex (with respect to magnetic
geodesics) boundary point. Moreover, a global invertibility result follows on a
compact Riemannian manifold with strictly convex boundary assuming that some
global foliation condition is satisfied.


title: Updated Core Libraries of the ALPS Project

abstract:
  The open source ALPS (Algorithms and Libraries for Physics Simulations)
project provides a collection of physics libraries and applications, with a
focus on simulations of lattice models and strongly correlated systems. The
libraries provide a convenient set of well-documented and reusable components
for developing condensed matter physics simulation code, and the applications
strive to make commonly used and proven computational algorithms available to a
non-expert community. In this paper we present an updated and refactored
version of the core ALPS libraries geared at the computational physics software
development community, rewritten with focus on documentation, ease of
installation, and software maintainability.


title: Paley-Wiener Theorem for the Weinstein Transform and applications

abstract:
  In this paper our aim is to establish the Paley-Wiener Theorems for the
Weinstein Transform. Furthermore, some applications are presents, in particular
some properties for the generalized translation operator associated with the
Weinstein operator are proved.


title:
Mapping the Similarities of Spectra: Global and Locally-biased
  Approaches to SDSS Galaxy Data

abstract:
  We apply a novel spectral graph technique, that of locally-biased
semi-supervised eigenvectors, to study the diversity of galaxies. This
technique permits us to characterize empirically the natural variations in
observed spectra data, and we illustrate how this approach can be used in an
exploratory manner to highlight both large-scale global as well as small-scale
local structure in Sloan Digital Sky Survey (SDSS) data. We use this method in
a way that simultaneously takes into account the measurements of spectral lines
as well as the continuum shape. Unlike Principal Component Analysis, this
method does not assume that the Euclidean distance between galaxy spectra is a
good global measure of similarity between all spectra, but instead it only
assumes that local difference information between similar spectra is reliable.
Moreover, unlike other nonlinear dimensionality methods, this method can be
used to characterize very finely both small-scale local as well as large-scale
global properties of realistic noisy data. The power of the method is
demonstrated on the SDSS Main Galaxy Sample by illustrating that the derived
embeddings of spectra carry an unprecedented amount of information. By using a
straightforward global or unsupervised variant, we observe that the main
features correlate strongly with star formation rate and that they clearly
separate active galactic nuclei. Computed parameters of the method can be used
to describe line strengths and their interdependencies. By using a
locally-biased or semi-supervised variant, we are able to focus on typical
variations around specific objects of astronomical interest. We present several
examples illustrating that this approach can enable new discoveries in the data
as well as a detailed understanding of very fine local structure that would
otherwise be overwhelmed by large-scale noise and global trends in the data.


title: The Trump phenomenon, an explanation from sociophysics

abstract:
  The Trump phenomenon is argued to depart from current populist rise in
Europe. According to a model of opinion dynamics from sociophysics the
machinery of Trump's amazing success obeys well-defined counter-intuitive
rules. Therefore, his success was in principle predictable from the start. The
model uses local majority rule arguments and obeys a threshold dynamics. The
associated tipping points are found to depend on the leading collective
beliefs, cognitive biases and prejudices of the social group which undertakes
the public debate. And here comes the sesame of the Trump campaign, which
develops along two successive steps. During a first moment, Trump's statement
produces a majority of voters against him. But at the same time, according to
the model the shocking character of the statement modifies the prejudice
balance. In case the prejudice is present even being frozen among voters, the
tipping point is lowered at Trump's benefit. Nevertheless, although the tipping
point has been lowered by the activation of frozen prejudices it is
instrumental to preserve enough support from openly prejudiced people to be
above the threshold. Then, as infuriated voters launch intense debate,
occurrence of ties will drive progressively hostile people to shift their
voting intention without needing to endorse the statement which has infuriated
them. The on going debate does drive towards a majority for Trump. The possible
Trump victory at November Presidential election is discussed. In particular,
the model shows that to eventually win the Presidential election, Trump must
not modify his past shocking attitude but to appeal to a different spectrum of
frozen prejudices, which are common to both Democrats and Republicans.


title: $3$-uniform hypergraphs and linear cycles

abstract:
  Gy\'arf\'as, Gy\H{o}ri and Simonovits proved that if a $3$-uniform hypergraph
with $n$ vertices has no linear cycles, then its independence number $\alpha
\ge \frac{2n} {5}$. The hypergraph consisting of vertex disjoint copies of a
complete hypergraph $K_5^3$ on five vertices, shows that equality can hold.
They asked whether this bound can be improved if we exclude $K_5^3$ as a
subhypergraph and whether such a hypergraph is $2$-colorable.
  In this paper we answer these questions affirmatively. Namely, we prove that
if a $3$-uniform linear-cycle-free hypergraph doesn't contain $K_5^3$ as a
subhypergraph, then it is $2$-colorable. This result clearly implies that its
independence number $\alpha \ge \lceil \frac{n}{2} \rceil$. We show that this
bound is sharp.
  Gy\'arf\'as, Gy\H{o}ri and Simonovits also proved that a linear-cycle-free
$3$-uniform hypergraph contains a vertex of strong degree at most 2. In this
context, we show that a linear-cycle-free $3$-uniform hypergraph has a vertex
of degree at most $n-2$ when $n \ge 10$.


title:
Suppression of blow up by a logistic source in $2$D Keller-Segel system
  with fractional dissipation

abstract:
  We consider a two dimensional parabolic-elliptic Keller-Segel equation with a
logistic forcing and a fractional diffusion of order $\alpha$. We obtain
existence of global in time regular solution for arbitrary initial data with no
size restrictions and $c<\alpha\leq 2$, where $c \in (0,2)$ depends on the
equation's parameters. For an even wider range of $\alpha's$, we prove
existence of global in time weak solution for general initial data.


title:
Multi-Wavelength Polarimetry and Spectral Study of M87 Jet During
  2002-2008

abstract:
  We present a multi-wavelength polarimetric and spectral study of M87 jet
obtained at sub- arcsecond resolution between 2002 and 2008. The observations
include multi-band archival VLA polarimetry data sets along with the HST
imaging polarimetry. These observations have better angular resolution than
previous work by factors of 2-3 and in addition, allow us to explore the time
domain. These observations envelope the huge flare in HST-1 located at 0."86
from the nucleus (Cheung et al. 2007; Harris et al. 2009; Madrid 2009; Perlman
et al. 2011). The increased resolution enables us to view more structure in
each knot, showing several resolved sub-components. We also see apparent
helical structure in the polarization vectors in several knots, with
polarization vectors turning either clockwise or counterclockwise near the flux
maxima in various places as well as show filamentary undulations. Some of these
characteristics are correlated with flux and polarization maxima while others
are not. We also examine the total flux and fractional polarization and look
for changes in both radio and optical since the observations of Perlman et al.
(1999) and test them against various models based on shocks and instabilities
in the jet. Our results are broadly consistent with previous spine-sheath
models and recollimation shock models, however, they require additional
combinations of features to explain the observed complexity, e.g. shearing of
magnetic field lines near the jet surface and compression of the toroidal
component near shocks. In particular, in many regions we find apparently
helical features both in total flux and polarization. We discuss the physical
interpretation of these features.


title: Liquid quantum droplets of ultracold magnetic atoms

abstract:
  The simultaneous presence of two competing inter-particle interactions can
lead to the emergence of new phenomena in a many-body system. Among others,
such effects are expected in dipolar Bose-Einstein condensates, subject to
dipole-dipole interaction and short-range repulsion. Magnetic quantum gases and
in particular Dysprosium gases, offering a comparable short-range contact and a
long-range dipolar interaction energy, remarkably exhibit such emergent
phenomena. In addition an effective cancellation of mean-field effects of the
two interactions results in a pronounced importance of quantum-mechanical
beyond mean-field effects. For a weakly-dominant dipolar interaction the
striking consequence is the existence of a new state of matter equilibrated by
the balance between weak mean-field attraction and beyond mean-field repulsion.
Though exemplified here in the case of dipolar Bose gases, this state of matter
should appear also with other microscopic interactions types, provided a
competition results in an effective cancellation of the total mean-field. The
macroscopic state takes the form of so-called quantum droplets. We present the
effects of a long-range dipolar interaction between these droplets.


title: Envy-Free Division of Land

abstract:
  Classic cake-cutting algorithms enable people with different preferences to
divide among them a heterogeneous resource (``cake''), such that the resulting
division is fair according to each agent's individual preferences. However,
these algorithms either ignore the geometry of the resource altogether, or
assume it is one-dimensional. In practice, it is often required to divide
multi-dimensional resources, such as land-estates or advertisement spaces in
print or electronic media. In such cases, the geometric shape of the allotted
piece is of crucial importance. For example, when building houses or designing
advertisements, in order to be useful, the allotments should be squares or
rectangles with bounded aspect-ratio. We thus introduce the problem of fair
land division --- fair division of a multi-dimensional resource wherein the
allocated piece must have a pre-specified geometric shape. We present
constructive division algorithms that satisfy the two most prominent fairness
criteria, namely envy-freeness and proportionality. In settings where
proportionality cannot be achieved due to the geometric constraints, our
algorithms provide a partially-proportional division, guaranteeing that the
fraction allocated to each agent be at least a certain positive constant. We
prove that in many natural settings the envy-freeness requirement is compatible
with the best attainable partial-proportionality.


title:
Gravitational Waves as a New Probe of Bose-Einstein Condensate Dark
  Matter

abstract:
  There exists a class of ultralight Dark Matter (DM) models which could form a
Bose-Einstein condensate (BEC) in the early universe and behave as a single
coherent wave instead of individual particles in galaxies. We show that a
generic BEC DM halo intervening along the line of sight of a gravitational wave
(GW) signal could induce an observable change in the speed of GW, with the
effective refractive index depending only on the mass and self-interaction of
the constituent DM particles and the GW frequency. Hence, we propose to use the
deviation in the speed of GW as a new probe of the BEC DM parameter space. With
a multi-messenger approach to GW astronomy and/or with extended sensitivity to
lower GW frequencies, the entire BEC DM parameter space can be effectively
probed by our new method in the near future.


title: Demonstration of the Jaynes-Cummings ladder with Rydberg-dressed atoms

abstract:
  We observe the nonlinearity of the Jaynes-Cummings (JC) ladder in the
Autler-Townes spectroscopy of the hyperfine ground states for a Rydberg-dressed
two-atom system. Here the role of the two-level system in the JC model is
played by the presence or absence of a collective Rydberg excitation, and the
bosonic mode manifests as the number $n$ of single atom spin flips,
symmetrically distributed between the atoms. We measure the normal-mode
splitting and $\sqrt{n}$ nonlinearity as a function of detuning and Rabi
frequency, thereby experimentally establishing the isomorphism with the JC
model.


title:
Spectroscopic comparison between ultraluminous X-ray sources and
  magnetar bursts

abstract:
  Nearby galaxies host ultra-luminous X-ray sources (ULXs), whose nature
remains largely unknown. Until the discovery of the first ULX pulsar, M82 X-2,
the mechanism powering the large luminosities of most ULXs was thought to be
super-Eddington accretion onto black holes. The ULX pulsar clearly indicates
that this hypothesis is not universal, and the question arises if other ULXs
are as well powered by accretion onto neutron stars. One possibility to have
highly super-Eddington luminosity is by reducing the opacity by strong magnetic
fields as in magnetars, as proposed for M82 X-2. To study the link between ULXs
and magnetar bursts/flares, we have performed a comparative spectral study
between these classes, which both emit at similar super-Eddington luminosities
at around $L \sim 10^{40}$ erg s$^{-1}$. We find that, when their spectra are
fitted with dual thermal models, the long term spectral variations of ULXs are
similar to short term spectral variability seen during magnetar flares. In both
classes of sources the black body temperatures and radii follow similar
$R_\textrm{bb} \propto T_\textrm{bb}^{-2}$ trends, the only difference being
that the temperatures in ULXs are an order of magnitude lower and thus they
have much larger characteristic emission areas. Furthermore, the ratio between
the luminosities of the two black body components shows the same one-to-one
dependence in ULXs and magnetars. We discuss the possible origins of these
similarities, and speculate that the reason for the lack of pulsations in
"magnetar-ULXs" could be that their photospheres are extended far beyond the
neutron star surface.


title: Gravitation and cosmology with York time

abstract:
  [Shortened abstract:] In this thesis we investigate a solution to the
`problem of time' in canonical quantum gravity by splitting spacetime into
surfaces of constant mean curvature parameterised by York time. We argue that
there are reasons to consider York time a viable candidate for a physically
meaningful notion of time. We investigate a number York-time
Hamiltonian-reduced cosmological models and explore some technical aspects,
such as the non-canonical Poisson structure. We develop York-time
Hamiltonian-reduced cosmological perturbation theory by solving the Hamiltonian
constraint perturbatively around a homogeneous background for the physical
(non-vanishing) Hamiltonian that is the momentum conjugate to the York time
parameter. We proceed to canonically quantise the cosmological models and the
perturbation theory and discuss a number of conceptual and technical points,
such as volume eigenfunctions and the absence of a momentum representation due
to the non-standard commutator structure. We propose an alternative,
wavefunction-free method of quantisation based on an ensemble of trajectories
and a dynamical configuration-space geometry and discuss its application to
gravity. We conclude by placing the York-time theories explored in this thesis
in the wider context of a search for a satisfactory theory of quantum gravity.


title:
A Constraint Satisfaction Problem Algorithm for Certain
  2-Semilattice-over-Edge Algebras

abstract:
  To any fixed, finite relational structure, $\mathbb{D}$, there is an
associated decision problem, CSP$(\mathbb{D})$, which is a restricted version
of the constraint satisfaction problem. In [8], the so called "algebraic
approach" to the constraint satisfaction problem was established. The authors
showed that to any finite relational structure, there is a corresponding finite
algebra, and that the complexity of CSP$(\mathbb{D})$ depends only on this
algebra. Therefore, they associate a decision problem, CSP$({\bf D})$ to an
algebra, ${\bf D}$, and ignore the relational structure. Their "algebraic
dichotomy conjecture" suggests that a technical condition on ${\bf D}$ implies
CSP$({\bf D})$ has a polynomial time algorithm. A significant sub-problem is
the case when some reduct of ${\bf D}$ has a congruence, $\theta$ so that ${\bf
D}/\theta$ has operations implying the local consistency algorithm correctly
solves CSP$({\bf D}/\theta)$, and each $\theta$-equivalence class, $B$, has
operations implying the few subpowers algorithm correctly solves CSP$({\bf
B})$. We give an algorithm for the case when ${\bf D}$ has a binary term
operation which is a $2$-semilattice operation on some quotient, ${\bf
D}/\theta$ of ${\bf D}$, a projection on each $\theta$-class, and two other
technical conditions are satisfied. Using this, we confirm the conjecture in
the case that ${\bf D}$ is in the join of two varieties, one of which has an
edge term and the other is term equivalent to the variety of $2$-semilattices.


title: Lie 2-algebras of vector fields

abstract:
  We show that the category of vector fields on a geometric stack has the
structure of a Lie 2-algebra. This proves a conjecture of R.~Hepworth. The
construction uses a Lie groupoid that presents the geometric stack. We show
that the category of vector fields on the Lie groupoid is equivalent to the
category of vector fields on the stack. The category of vector fields on the
Lie groupoid has a Lie 2-algebra structure built from known (ordinary) Lie
brackets on multiplicative vector fields of Mackenzie and Xu and the global
sections of the Lie algebroid of the Lie groupoid. After giving a precise
formulation of Morita invariance of the construction, we verify that the Lie
2-algebra structure defined in this way is well-defined on the underlying
stack.


title: Convergence of coupled cluster perturbation theory

abstract:
  The convergence of a recently proposed coupled cluster (CC) family of
perturbation series [Eriksen, J. J. et al., J. Chem. Phys. 140, 064108 (2014)],
in which the energetic difference between two CC models - a low-level parent
and a high-level target model - is expanded in orders of the M{\o}ller-Plesset
(MP) fluctuation potential, is investigated for four prototypical closed-shell
systems (Ne, singlet methylene, distorted HF, and the fluoride anion) in
standard and augmented basis sets. In these investigations, energy corrections
of the various series have been calculated to high orders and their convergence
radii determined by probing for possible front- and back-door intruder states,
the existence of which would make the series divergent. In summary, we conclude
how it is primarily the choice of target state, and not the choice of parent
state, which ultimately governs the convergence behavior of a given series. For
example, restricting the target state to, say, triple or quadruple excitations
might remove intruders present in series that target the full configuration
interaction (FCI) limit, such as the standard MP series. Furthermore, we find
that whereas a CC perturbation series might converge within standard
correlation consistent basis sets, it may start to diverge whenever these
become augmented by diffuse functions, similar to the MP case. However, unlike
for the MP case, such potential divergences are not found to invalidate the
practical use of the low-order corrections of the CC perturbation series.