title: Convective heat transfer to Sisko fluid over a rotating disk

abstract:
  This article deals with study of the steady flow and heat transfer
characteristics of Sisko fluid over a rotating infinite disk. The flow and heat
transfer aspects are thoroughly investigated encompassing highly shear
thinning/thickening Sisko fluids. The modeled boundary layer equations are
reduced to a system of nonlinear ordinary differential equations using the
appropriate transformation. The resulting equations are then solved numerically
by shooting method in the domain . The numerical data for the velocity and
temperature fields are graphically sketched and effects of the relevant
parameters are discussed in detail. In addition, the velocity gradients at the
disk surface and the local Nusselt number for different values of the
pertaining parameters are given in tabulated form. Further, the flow and
temperature fields of power-law and Newtonian fluids are also compared with
those Sisko fluid. Moreover, a comparison with previously published work, as a
special case of the problem, has been provided and the results are found to be
in excellent agreement.


title:
Tuning of few-electron states and optical absorption anisotropy in GaAs
  quantum rings

abstract:
  The electronic and optical properties of a GaAs quantum ring (QR) with few
electrons in the presence of the Rashba spin-orbit interaction (RSOI) and the
Dresselhaus spin-orbit interaction (DSOI) have been investigated theoretically.
Configuration interaction (CI) method is employed to calculate the eigenvalues
and eigenstates of the multiple-electron QR accurately. Our numerical results
demonstrate that the symmetry breaking induced by the RSOI and DSOI leads to an
anisotropic distribution of multi-electron states. The Coulomb interaction
offers additional modulation of the electron distribution and thus the optical
absorption indices in the quantum rings. By tuning the magnetic/electric fields
and/or electron numbers in a quantum ring, one can change its optical property
significantly. Our theory provides a new way to control multi-electron states
and optical properties of QR by hybrid modulations or by electrical means only.


title: Inferring collective dynamical states from widely unobserved systems

abstract:
  When assessing spatially-extended complex systems, one can rarely sample the
states of all components. We show that this spatial subsampling typically leads
to severe underestimation of the risk of instability in systems with
propagating events. We derive a subsampling-invariant estimator, and
demonstrate that it correctly infers the infectiousness of various diseases
under subsampling, making it particularly useful in countries with unreliable
case reports. In neuroscience, recordings are strongly limited by subsampling.
Here, the subsampling-invariant estimator allows to revisit two prominent
hypotheses about the brain's collective spiking dynamics:
asynchronous-irregular or critical. We identify consistently for rat, cat and
monkey a state that combines features of both and allows input to reverberate
in the network for hundreds of milliseconds. Overall, owing to its ready
applicability, the novel estimator paves the way to novel insight for the study
of spatially-extended dynamical systems.


title:
System Reliability, Fault Tolerance and Design Metrics Tradeoffs in the
  Distributed Minority and Majority Voting Based Redundancy Scheme

abstract:
  The distributed minority and majority voting based redundancy (DMMR) scheme
was recently proposed as an efficient alternative to the conventional N-modular
redundancy (NMR) scheme for the physical design of mission/safety-critical
circuits and systems. The DMMR scheme enables significant improvements in fault
tolerance and design metrics compared to the NMR scheme albeit at the expense
of a slight decrease in the system reliability. In this context, this paper
studies the system reliability, fault tolerance and design metrics tradeoffs in
the DMMR scheme compared to the NMR scheme when the majority logic group of the
DMMR scheme is increased in size relative to the minority logic group. Some
example DMMR and NMR systems were realized using a 32/28nm CMOS process and
compared. The results show that 5-of-M DMMR systems have a similar or better
fault tolerance whilst requiring similar or fewer function modules than their
counterpart NMR systems and simultaneously achieve optimizations in design
metrics. Nevertheless, 3-of-M DMMR systems have the upper hand with respect to
fault tolerance and design metrics optimizations than the comparable NMR and
5-of-M DMMR systems. With regard to system reliability, NMR systems are closely
followed by 5-of-M DMMR systems which are closely followed by 3-of-M DMMR
systems. The verdict is 3-of-M DMMR systems are preferable to implement higher
levels of redundancy from a combined system reliability, fault tolerance and
design metrics perspective to realize mission/safety-critical circuits and
systems.


title:
Displacive model of deformation twinning in hexagonal close-packed
  metals. Case of the (90 deg, a) and (86 deg, a) extension twins in magnesium

abstract:
  A crystallographic displacive model is proposed for the extension twins in
magnesium. It is based on a hard-sphere assumption previously used for
martensitic transformations. The atomic displacements are established, and the
homogeneous lattice distortion is analytically expressed as a continuous
angular-distortive matrix that takes the usual form of shear when the
distortion is complete. The calculations prove that a volume change of 3
percents occurs for the intermediate states and that the twinning plane, even
if untilted and restored when the distortion is complete, is not fully
invariant during the transient states. The crystallographic calculations also
show that the (90 deg, a) twins observed in magnesium nano-pillars and the (86
deg, a) twins observed in bulk samples come from the same mechanism, the only
difference being the existence of a slight obliquity angle (+/- 3.4 deg)
required to reduce the strains in the latter case. Continuous features in the
pole figures between the low-misoriented (86 deg, a) twin variants are
expected; they are confirmed by EBSD maps acquired on a deformed magnesium
single crystal. As the continuous mechanism of extension twinning is not a
simple shear, a "virtual work" criterion using the value of the intermediate
distortion matrix at the maximum volume change is proposed in place of the
usual Schmid's law. It allows predicting the formation of extension twins for
crystal orientations associated with negative Schmid factors.


title: The (minimum) rank of typical fooling set matrices

abstract:
  A fooling-set matrix has nonzero diagonal, but at least one in every pair of
diagonally opposite entries is 0. Dietzfelbinger et al. '96 proved that the
rank of such a matrix is at least $\sqrt n$. It is known that the bound is
tight (up to a multiplicative constant).
  We ask for the "typical" minimum rank of a fooling-set matrix: For a
fooling-set zero-nonzero pattern chosen at random, is the minimum rank of a
matrix with that zero-nonzero pattern over a field $\mathbb F$ closer to its
lower bound $\sqrt{n}$ or to its upper bound $n$? We study random patterns with
a given density $p$, and prove an $\Omega(n)$ bound for the cases when: (a) $p$
tends to $0$ quickly enough, (b) $p$ tends to $0$ slowly, and $|\mathbb
F|=O(1)$, (c) $p\in(0,1]$ is a constant.
  We have to leave open the case when $p\to 0$ slowly and $\mathbb F$ is a
large or infinite field (e.g., $\mathbb F=GF(2^n)$, $F=\mathbb{R}$).


title: Cosmological constraints on coupled dark energy

abstract:
  The coupled dark energy model provides a possible approach to mitigate the
coincidence problem of cosmological standard model. Here, the coupling term is
assumed as $\bar{Q}=3H\xi_x\bar{\rho}_x$, which is related to the interaction
rate and energy density of dark energy. We derive the background and
perturbation evolution equations for several coupled models. Then, we test
these models by currently available cosmic observations which include cosmic
microwave background radiation from Planck 2015, baryon acoustic oscillation,
type Ia supernovae, $f\sigma_8(z)$ data points from redshift-space distortions,
and weak gravitational lensing. The constraint results tell us there is no
evidence of interaction at 2$\sigma$ level, it is very hard to distinguish
different coupled models from other ones.


title:
Charged dust grain dynamics subject to solar wind, Poynting-Robertson
  drag, and the interplanetary magnetic field

abstract:
  We investigate the combined effect of solar wind, Poynting-Robertson drag,
and the frozen-in interplanetary magnetic field on the motion of charged dust
grains in our solar system. For this reason we derive a secular theory of
motion by the means of averaging method and validate it with numerical
simulations of the un-averaged equations of motions. The theory predicts that
the secular motion of charged particles is mainly affected by the z-component
of the solar magnetic axis, or the normal component of the interplanetary
magnetic field. The normal component of the interplanetary magnetic field leads
to an increase or decrease of semi-major axis depending on its functional form
and sign of charge of the dust grain. It is generally accepted that the
combined effects of solar wind and photon absorption and re-emmision
(Poynting-Robertson drag) lead to a decrease in semi-major axis on secular time
scales. On the contrary, we demonstrate that the interplanetary magnetic field
may counteract these drag forces under certain circumstances. We derive a
simple relation between the parameters of the magnetic field, the physical
properties of the dust grain as well as the shape and orientation of the
orbital ellipse of the particle, which is a necessary conditions for the
stabilization in semi-major axis.


title: Stopped nucleons in configuration space

abstract:
  In this note, using the colour string model, we study the configuration space
distribution of stopped nucleons in heavy-ion collisions. We find that the
stopped nucleons from the target and the projectile end up separated from each
other by the distance increasing with the collision energy. In consequence, for
the center of mass energies larger than 6 or 10 GeV (depending on the details
of the model) it appears that the system created is not in thermal and chemical
equilibrium, and the net baryon density reached is likely not much higher than
that already present in the colliding nuclei.


title:
Abundance ratios and IMF slope in the dwarf elliptical galaxy NGC~1396
  with MUSE

abstract:
  Deep observations of the dwarf elliptical (dE) galaxy NGC 1396 (M$_V =
-16.60$, Mass $\sim 4\times10^8$ M$_\odot$), located in the Fornax cluster,
have been performed with the VLT/ MUSE spectrograph in the wavelength region
from $4750-9350$ \AA{}. In this paper we present a stellar population analysis
studying chemical abundances, the star formation history (SFH) and the stellar
initial mass function (IMF) as a function of galacto-centric distance.
Different, independent ways to analyse the stellar populations result in a
luminosity-weighted age of $\sim$ 6 Gyr and a metallicity [Fe/H]$\sim$ $-0.4$,
similar to other dEs of similar mass. We find unusually overabundant values of
[Ca/Fe] $\sim +0.1$, and under-abundant Sodium, with [Na/Fe] values around
$-0.1$, while [Mg/Fe] is overabundant at all radii, increasing from $\sim+0.1$
in the centre to $\sim +0.2$ dex. We notice a significant metallicity and age
gradient within this dwarf galaxy. To constrain the stellar IMF of NGC 1396, we
find that the IMF of NGC 1396 is consistent with either a Kroupa-like or a
top-heavy distribution, while a bottom-heavy IMF is firmly ruled out. An
analysis of the abundance ratios, and a comparison with galaxies in the Local
Group, shows that the chemical enrichment history of NGC 1396 is similar to the
Galactic disc, with an extended star formation history. This would be the case
if the galaxy originated from a LMC-sized dwarf galaxy progenitor, which would
lose its gas while falling into the Fornax cluster.


title:
Characterization of charge-exchange collisions between ultracold
  $\rm{^6Li}$ atoms and $\rm{^{40}Ca^+}$ ions

abstract:
  We investigate the energy dependence and the internal-state dependence of the
charge-exchange collision cross sections in a mixture of $^6$Li atoms and
$^{40}$Ca$^+$ ions in the collision energy range from 0.2 mK to 1 K.
Deliberately excited ion micromotion is used to control the collision energy of
atoms and ions. The energy dependence of the charge-exchange collision cross
section obeys the Langevin model in the temperature range of the current
experiment, and the measured magnitude of the cross section is correlated to
the internal state of the $^{40}$Ca$^+$ ions. Revealing the relationship
between the charge-exchange collision cross sections and the interaction
potentials is an important step toward the realization of the full quantum
control of the chemical reactions at an ultralow temperature regime.


title: Modification of the Porter-Thomas distribution by rank-one interaction

abstract:
  The Porter-Thomas (PT) distribution of resonance widths is one of the oldest
and simplest applications of statistical ideas in nuclear physics. Previous
experimental data confirmed it quite well but recent and more careful
investigations show clear deviations from this distribution. To explain these
discrepancies the authors of [PRL \textbf{115}, 052501 (2015)] argued that to
get a realistic model of nuclear resonances is not enough to consider one of
the standard random matrix ensembles which leads immediately to the PT
distribution but it is necessary to add a rank-one interaction which couples
resonances to decay channels. The purpose of the paper is to solve this model
analytically and to find explicitly the modifications of the PT distribution
due to such interaction. Resulting formulae are simple, in a good agreement
with numerics, and could explain experimental results.


title: The dilemma of turbulence modelling

abstract:
  A new construction technique of multiple solutions of the Euler equa- tion in
strong spaces is introduced which reveals the relationship to multi- ple Navier
Stokes equation solutions with special force terms while avoid- ing viscosity
limit constructions. This shows that severe restrictions have to be imposed on
time dependent external force terms in order to ob- tain uniqueness for the
Navier Stokes equation Cauchy problem. Such restrictions are imposed in the
statement of the so-called millenium prob- lem. Minimal turbulence models
should arguably incorporate weaker force terms in order to account for boundary
conditions and forces. However, we show that models of this type which have
been proposed recently, do not have a unique solution. This lack of determinism
of mimimal turbu- lence models indicates a dilemma: either models are too
simple to capture turbulence but may have unique smooth solutions, or there is
a modelling gap as the model does not determine a unique solution.


title: Transient performance analysis of zero-attracting LMS

abstract:
  Zero-attracting least-mean-square (ZA-LMS) algorithm has been widely used for
online sparse system identification. It combines the LMS framework and
$\ell_1$-norm regularization to promote sparsity, and relies on subgradient
iterations. Despite the significant interest in ZA-LMS, few works analyzed its
transient behavior. The main difficulty lies in the nonlinearity of the update
rule. In this work, a detailed analysis in the mean and mean-square sense is
carried out in order to examine the behavior of the algorithm. Simulation
results illustrate the accuracy of the model and highlight its performance
through comparisons with an existing model.


title:
Influence of strain relaxation in axial (In,Ga)N/GaN nanowire
  heterostructures on their electronic properties

abstract:
  We present a systematic study of the influence of elastic strain relaxation
on the built-in electrostatic potentials and the electronic properties of axial
(In,Ga)N/GaN nanowire heterostructures. We employ and evaluate analytical and
numerical approaches to compute strain and polarization potentials. These two
ingredients then enter an eight-band k.p model to compute electron and hole
ground states and energies. Our analysis reveals that for a sufficiently large
ratio between the thickness of the (In,Ga)N disk and the diameter of the
nanowire, the elastic relaxation leads to a significant reduction of the
built-in electrostatic potential in comparison to a planar system of similar
layer thickness and In content. However, a complete elimination of the built-in
potential cannot be achieved in axial nanowire heterostructures. Nevertheless,
the reduction of the built-in electrostatic potential leads to a significant
modification of the electron and hole energies. Our findings indicate that the
range of accessible ground state transition energies in an axial (In,Ga)N/GaN
nanowire heterostructure is limited due to the reduced influence of
polarization potentials for thicker disks. Additionally, we find that strain
and polarization potentials induce complex confinement features of electrons
and holes, which depend on the In content, shape, and dimensions of the
heterostructure.


title:
On the application of higher order symplectic integrators in Hamiltonian
  Monte Carlo

abstract:
  We explore the construction of new symplectic numerical integration schemes
to be used in Hamiltonian Monte Carlo and study their efficiency. Two
integration schemes from Blanes et al. (2014), and a new scheme based on
optimal acceptance probability, are considered as candidates to the commonly
used leapfrog method. All integration schemes are tested within the framework
of the No-U-Turn sampler (NUTS), both for a logistic regression model and a
student $t$-model. The results show that the leapfrog method is inferior to all
the new methods both in terms of asymptotic expected acceptance probability for
a model problem and the and efficient sample size per computing time for the
realistic models.


title:
Consequences of a strong phase transition in the dense matter equation
  of state for the rotational evolution of neutron stars

abstract:
  We explore the implications of a strong first-order phase transition region
in the dense matter equation of state in the interiors of rotating neutron
stars, and the resulting creation of two disjoint families of neutron-star
configurations (the so-called high-mass twins). We numerically obtained
rotating, axisymmetric, and stationary stellar configurations in the framework
of general relativity, and studied their global parameters and stability. The
instability induced by the equation of state divides stable neutron star
configurations into two disjoint families: neutron stars (second family) and
hybrid stars (third family), with an overlapping region in mass, the high-mass
twin-star region. These two regions are divided by an instability strip. Its
existence has interesting astrophysical consequences for rotating neutron
stars. We note that it provides a natural explanation for the rotational
frequency cutoff in the observed distribution of neutron star spins, and for
the apparent lack of back-bending in pulsar timing. It also straightforwardly
enables a substantial energy release in a mini-collapse to another neutron-star
configuration (core quake), or to a black hole.


title: Null surgery on knots in L-spaces

abstract:
  Let $K$ be a knot in an L-space $Y$ with a Dehn surgery to a surface bundle
over $S^1$. We prove that $K$ is rationally fibered, that is, the knot
complement admits a fibration over $S^1$. As part of the proof, we show that if
$K\subset Y$ has a Dehn surgery to $S^1 \times S^2$, then $K$ is rationally
fibered. In the case that $K$ admits some $S^1 \times S^2$ surgery, $K$ is
Floer simple, that is, the rank of $\hat{HFK}(Y,K)$ is equal to the order of
$H_1(Y)$. By combining the latter two facts, we deduce that the induced contact
structure on the ambient manifold $Y$ is tight.
  In a different direction, we show that if $K$ is a knot in an L-space $Y$,
then any Thurston norm minimizing rational Seifert surface for $K$ extends to a
Thurston norm minimizing surface in the manifold obtained by the null surgery
on $K$ (i.e., the unique surgery on $K$ with $b_1>0$).


title: Learning Points and Routes to Recommend Trajectories

abstract:
  The problem of recommending tours to travellers is an important and broadly
studied area. Suggested solutions include various approaches of
points-of-interest (POI) recommendation and route planning. We consider the
task of recommending a sequence of POIs, that simultaneously uses information
about POIs and routes. Our approach unifies the treatment of various sources of
information by representing them as features in machine learning algorithms,
enabling us to learn from past behaviour. Information about POIs are used to
learn a POI ranking model that accounts for the start and end points of tours.
Data about previous trajectories are used for learning transition patterns
between POIs that enable us to recommend probable routes. In addition, a
probabilistic model is proposed to combine the results of POI ranking and the
POI to POI transitions. We propose a new F$_1$ score on pairs of POIs that
capture the order of visits. Empirical results show that our approach improves
on recent methods, and demonstrate that combining points and routes enables
better trajectory recommendations.


title:
The interaction of intense ultrashort laser pulses with cryogenic He
  jets

abstract:
  We study the interaction of intense ultrashort laser pulses with cryogenic He
jets using 2d/3v relativistic Particle-in-Cell simulations (XOOPIC). Of
particular interest are laser intensities $(10^{15}-10^{20})$ W/cm$^2$, pulse
lengths $\le 100$ fs, and the frequency regime $\sim 800$ nm for which the jets
are initially transparent and subsequently not homogeneously ionized. Pulses
$\ge 10^{16}$ W/cm$^2$ are found to drive ionization along the jet and outside
the laser spot, the ionization-front propagates along the jet at a fraction of
the speed of light. Within the ionized region, there is a highly transient
field, which may be interpreted as two-surface wave decay and as a result of
the charge-neutralizing disturbance at the jet-vacuum interface. The ionized
region has solid-like densities and temperatures of few to hundreds of eV,
i.e., warm and hot dense matter regimes. Such extreme conditions are relevant
for high-energy densities as found, e.g., in shock-wave experiments and
inertial confinement fusion studies. The temporal evolution of the ionization
is studied considering theoretically a pump-probe x-ray Thomson scattering
(XRTS) scheme. We observe plasmon and non-collective modes that are generated
in the jet, and their amplitude is proportional to the ionized volume. Our
theoretical findings could be tested at free-electron laser facilities such as
FLASH and the European XFEL (Hamburg) and the LCLS (Stanford).


title:
Noise modeling and analysis of an IMU-based attitude sensor: improvement
  of performance by filtering and sensor fusion

abstract:
  We describe the characterization and removal of noise present in the Inertial
Measurement Unit (IMU) MPU-6050. This IMU was initially used in an attitude
sensor (AS) developed in-house, and subsequently implemented in a pointing and
stabilization platform developed for small balloon-borne astronomical payloads.
We found that the performance of the IMU degrades with time due to the
accumulation of different errors. Using the Allan variance analysis method, we
identified the different components of noise present in the IMU and verified
the results using a power spectral density analysis (PSD). We tried to remove
the high-frequency noise using smoothing filters, such as moving average filter
and Savitzky-Golay filter. Although we did manage to filter some of the
high-frequency noise, the performance of these filters was not satisfactory for
our application. We found the distribution of the random noise present in the
IMU using a probability density analysis, and identified the noise to be white
Gaussian in nature which we successfully removed by a Kalman filter in real
time.


title: Nef cone volumes and discriminants of abelian surfaces

abstract:
  The nef cone volume appeared first in work of Peyre in a number-theoretic
context on Del Pezzo surfaces, and it was studied by Derenthal and co-authors
in a series of papers. The idea was subsequently extended to also measure the
Zariski chambers of Del Pezzo surfaces. We start in this paper to explore the
possibility to use this attractive concept to effectively measure the size of
the nef cone on algebraic surfaces in general. This provides an interesting way
of measuring in how big a space an ample line bundle can be moved without
destroying its positivity. We give here complete results for simple abelian
surfaces that admit a principal polarization and for products of elliptic
curves.


title: PALMA, an improved algorithm for DOSY signal processing

abstract:
  NMR is a tool of choice for the measure of diffusion coefficients of species
in solution. The DOSY experiment, a 2D implementation of this measure, has
proven to be particularly useful for the study of complex mixtures, molecular
interactions, polymers, etc. However, DOSY data analysis requires to resort to
inverse Laplace transform, in particular for polydisperse samples. This is a
known difficult numerical task, for which we present here a novel approach. A
new algorithm based on a splitting scheme and on the use of proximity operators
is introduced. Used in conjunction with a Maximum Entropy and $\ell_1$ hybrid
regularisation, this algorithm converges rapidly and produces results robust
against experimental noise. This method has been called PALMA. It is able to
reproduce faithfully monodisperse as well as polydisperse systems, and numerous
simulated and experimental examples are presented. It has been implemented on
the server http://palma.labo.igbmc.fr where users can have their datasets
processed automatically.


title: Multi-Colored Spanning Graphs

abstract:
  We study a problem proposed by Hurtado et al. (2016) motivated by sparse set
visualization. Given $n$ points in the plane, each labeled with one or more
primary colors, a \emph{colored spanning graph} (CSG) is a graph such that for
each primary color, the vertices of that color induce a connected subgraph. The
\textsc{Min-CSG} problem asks for the minimum sum of edge lengths in a colored
spanning graph. We show that the problem is NP-hard for $k$ primary colors when
$k\ge 3$ and provide a $(2-\frac{1}{3+2\varrho})$-approximation algorithm for
$k=3$ that runs in polynomial time, where $\varrho$ is the Steiner ratio.
Further, we give a $O(n)$ time algorithm in the special case that the input
points are collinear and $k$ is constant.


title:
Dynamical analysis of the complex radio structure in 3C 293: Clues on a
  rapid jet realignment in X-shaped radio galaxies

abstract:
  Radio galaxies classified as X-shaped/winged, are characterised by two pairs
of extended and misaligned lobes, which suggest a rapid realignment of the jet
axis, for which a potential cause is still under debate. Here we analyse the
complex radio structure of 3C 293 winged source hosted by the post-merger
galaxy, which uniquely displays a significant asymmetry between the sizes of
the two pairs of lobes, indicating that an episode of jet realignment took
place only very recently. Based on all the available radio data for 3C 293, we
have performed a detailed spectral modelling for the older and younger lobes in
the system. In this way we derived the lobes' ages and jet energetics, which we
then compared to the accretion power in the source. We found that the 200
kpc-scale outer lobes of 3C 293 are ~60 Myr old and that jet activity related
to the formation of the outer lobes ceased within the last Myr. Meanwhile, the
inner 4 kpc-scale lobes, tilted by ~40 deg with respect to the outer ones, are
only about ~0.3 Myr old. The best model fits also return identical values of
the jet power supplying the outer and the inner structures. This power is of
the order of the maximum kinetic luminosity of a Blandford-Znajek jet for a
given black hole mass and accretion rate, but only in the case of relatively
low values of a black hole spin, a~0.2. The derived jet energetics and
timescales, along with the presence of two optical nuclei in 3C 293, all
provide a strong support to the Lense-Thirring precession model in which the
supermassive black hole spin, and therefore the jet axis, flips rapidly owing
to the interactions with the tilted accretion disk in a new tidal interaction
episode of the merging process. We further speculate that, in general, X-shape
radio morphology forms in post-merger systems that are rich in cold molecular
gas, and only host slowly spinning supermassive black holes.


title:
matLeap: A fast adaptive Matlab-ready tau-leaping implementation
  suitable for Bayesian inference

abstract:
  Background: Species abundance distributions in chemical reaction network
models cannot usually be computed analytically. Instead, stochas- tic
simulation algorithms allow sample from the the system configuration. Although
many algorithms have been described, no fast implementation has been provided
for {\tau}-leaping which i) is Matlab-compatible, ii) adap- tively alternates
between SSA, implicit and explicit {\tau}-leaping, and iii) provides summary
statistics necessary for Bayesian inference. Results: We provide a
Matlab-compatible implementation of the adap- tive explicit-implicit
{\tau}-leaping algorithm to address the above-mentioned deficits. matLeap
provides equal or substantially faster results compared to two widely used
simulation packages while maintaining accuracy. Lastly, matLeap yields summary
statistics of the stochastic process unavailable with other methods, which are
indispensable for Bayesian inference. Conclusions: matLeap addresses
shortcomings in existing Matlab-compatible stochastic simulation software,
providing significant speedups and sum- mary statistics that are especially
useful for researchers utilizing particle- filter based methods for Bayesian
inference. Code is available for download at
https://github.com/claassengroup/matLeap. Contact:
justin.feigelman@imsb.biol.ethz.ch


title:
Exact solutions and symmetry analysis for the limiting probability
  distribution of quantum walks

abstract:
  In the literature, there are numerous studies of one-dimensional
discrete-time quantum walks (DTQWs) using a moving shift operator. However,
there is no exact solution for the limiting probability distributions of DTQWs
on cycles using a general coin or swapping shift operator. In this paper, we
derive exact solutions for the limiting probability distribution of quantum
walks using a general coin and swapping shift operator on cycles for the first
time. Based on the exact solutions, we show how to generate symmetric quantum
walks and determine the condition under which a symmetric quantum walk appears.
Our results suggest that choosing various coin and initial state parameters can
achieve a symmetric quantum walk. By defining a quantity to measure the
variation of symmetry, deviation and mixing time of symmetric quantum walks are
also investigated.


title:
Structural properties of LPV to LFR transformation: minimality,
  input-output behavior and identifiability

abstract:
  In this paper, we introduce and study important properties of the
transformation of Affine Linear Parameter-Varying (ALPV) state-space
representations into Linear Fractional Representations (LFR). More precisely,
we show that $(i)$ state minimal ALPV representations yield minimal LFRs, and
vice versa, $(ii)$ the input-output behavior of the ALPV represention
determines uniquely the input-output behavior of the resulting LFR, $(iii)$
structurally identifiable ALPVs yield structurally identifiable LFRs, and vice
versa. We then characterize LFR models which correspond to equivalent ALPV
models based on their input-output maps. As illustrated all along the paper,
these results have important consequences for identification and control of
systems described by LFRs.


title:
Scaling limit of the subdiffusive random walk on a Galton-Watson tree in
  random environment

abstract:
  We consider a random walk on a Galton-Watson tree in random environment, in
the subdiffusive case. We prove the convergence of the renormalised height
function of the walk towards the continuous-time height process of a spectrally
positive strictly stable L\'evy process, jointly with the convergence of the
renormalised range of the walk towards the real tree coded by the latter
continuous-time height process.


title:
On a non-homogeneous eigenvalue problem involving a potential: an
  Orlicz-Sobolev space setting

abstract:
  In this paper we study a non-homogeneous eigenvalue problem involving
variable growth conditions and a potential $V$. The problem is analyzed in the
context of Orlicz-Sobolev spaces. Connected with this problem we also study the
optimization problem for the particular eigenvalue given by the infimum of the
Rayleigh quotient associated to the problem with respect to the potential $V$
when $V$ lies in a bounded, closed and convex subset of a certain variable
exponent Lebesgue space.


title:
On double shifted convolution sum of $SL(2, \mathbb{Z})$ Hecke eigen
  forms

abstract:
  Let $\lambda_i (n)$ $i= 1, 2, 3$ denote the normalised Fourier coefficients
of holomorphic eigenform or Maass cusp form. In this paper we shall consider
the sum: \[ S:= \frac{1}{H}\sum_{h\leq H} V\left( \frac{h}{H}\right)\sum_{n\leq
N} \lambda_1 (n) \lambda_2 (n+h) \lambda_3 (n+ 2h)W\left( \frac{n}{N} \right),
\] \noindent where $V$ and $W$ are smooth bump functions, supported on $[1,
2]$. We shall prove a nontrivial upper bound, under the assumption that $H\geq
N^{1/2+ \epsilon}$.


title:
Existence of solutions for a class of nonlinear Choquard equations with
  critical growth

abstract:
  In this paper, we consider a class of nonlinear Choquard equations with
critical growth, and we show the existence of solutions of the equations.
Besides, we consider the corresponding minimizing problem and prove the
existence of a minimizer.


title:
Persistence as Order Parameter in Generalized Pair Contact Process with
  Diffusion

abstract:
  The question of universality class of pair contact process with diffusion
(PCPD) is revisited with an alternative approach. We study persistence in
Generalized Pair-Contact Process with diffusion (GPCPD) introduced by Noh and
Park, (Phys. Rev. E 69,016122(2004)). This model allows us to interpolate
between directed percolation (DP) and PCPD universality classes. We find that
transition to nonzero persistence is at same parameter value as transition to
zero number density. We obtain finite size scaling and off-critical scaling
collapse for persistence and find critical exponents by fitting
phenomenological scaling laws to persistence. While the dynamic scaling
exponent $z$ varies continuously in GPCPD, the correlation-time exponent
$\nu_\parallel$ matches with directed percolation universality class.


title: Extended vector-tensor theories

abstract:
  Recently, several extensions of massive vector theory in curved space-time
have been proposed in many literatures. In this paper, we consider the most
general vector-tensor theories that contain up to two derivatives with respect
to metric and vector field. By imposing a degeneracy condition of the
Lagrangian in the context of ADM decomposition of space-time to eliminate an
unwanted mode, we construct a new class of massive vector theories where five
degrees of freedom can propagate, corresponding to three for massive vector
modes and two for massless tensor modes. We find that the generalized Proca and
the beyond generalized Proca theories up to the quartic Lagrangian, which
should be included in this formulation, are degenerate theories even in curved
space-time. Finally, introducing new metric and vector field transformations,
we investigate the properties of thus obtained theories under such
transformations.


title: On sequences of solutions for discrete anisotropic equations

abstract:
  Taking advantage of a recent critical point theorem, the existence of
infinitely many solutions for an anisotropic problem with a parameter is
established. More precisely, a concrete interval of positive parameters, for
which the treated problem admits infinitely many solutions, is determined
without symmetry assumptions on the nonlinear data. Our goal was achieved by
requiring an appropriate behavior of the nonlinear terms at zero, without any
additional conditions.


title: Title Generation for User Generated Videos

abstract:
  A great video title describes the most salient event compactly and captures
the viewer's attention. In contrast, video captioning tends to generate
sentences that describe the video as a whole. Although generating a video title
automatically is a very useful task, it is much less addressed than video
captioning. We address video title generation for the first time by proposing
two methods that extend state-of-the-art video captioners to this new task.
First, we make video captioners highlight sensitive by priming them with a
highlight detector. Our framework allows for jointly training a model for title
generation and video highlight localization. Second, we induce high sentence
diversity in video captioners, so that the generated titles are also diverse
and catchy. This means that a large number of sentences might be required to
learn the sentence structure of titles. Hence, we propose a novel sentence
augmentation method to train a captioner with additional sentence-only examples
that come without corresponding videos. We collected a large-scale Video Titles
in the Wild (VTW) dataset of 18100 automatically crawled user-generated videos
and titles. On VTW, our methods consistently improve title prediction accuracy,
and achieve the best performance in both automatic and human evaluation.
Finally, our sentence augmentation method also outperforms the baselines on the
M-VAD dataset.


title:
Microelectrode arrays of diamond-insulated graphitic channels for real
  time detection of exocytotic events from cultured chromaffin cells and slices
  of adrenal glands

abstract:
  A microstructured graphitic 4x4 multielectrode array was embedded in a single
crystal diamond substrate (4x4 {uG-SCD MEA) for real-time monitoring of
exocytotic events from cultured chromaffin cells and adrenal slices. The
current approach relies on the development of a parallel ion beam lithographic
technique, which assures the time effective fabrication of extended arrays with
reproducible electrode dimensions. The reported device is suitable for
performing amperometric and voltammetric recordings with high sensitivity and
temporal resolution, by simultaneously acquiring data from 16 rectangularly
shaped microelectrodes (20x3.5 um^2) separated by 200 um gaps. Taking advantage
of the array geometry we addressed the following specific issues: i) detect
both the spontaneous and KCl-evoked secretion simultaneously from several
chromaffin cells directly cultured on the device surface, ii) resolve the
waveform of different subsets of exocytotic events, iii) monitoring quantal
secretory events from thin slices of the adrenal gland. The frequency of
spontaneous release was low (0.12 Hz and 0.3 Hz respectively for adrenal slices
and cultured cells) and increased up to 0.9 Hz after stimulation with 30 mM KCl
in cultured cells. The spike amplitude as well as rise and decay time were
comparable with those measured by carbon fiber microelectrodes and allowed to
identify three different subsets of secretory events associated to "full
fusion" events, "kiss and-run" and "kiss-and-stay" exocytosis, confirming that
the device has adequate sensitivity and time resolution for real-time
recordings. The device offers the significant advantage of shortening the time
to collect data by allowing simultaneous recordings from cell populations
either in primary cell cultures or in intact tissues.


title:
Micro and nano-patterning of single-crystal diamond by swift heavy ion
  irradiation

abstract:
  This paper presents experimental data and analysis of the structural damage
caused by swift-heavy ion irradiation of single-crystal diamond. The patterned
buried structural damage is shown to generate, via swelling, a mirror-pattern
on the sample surface, which remains largely damage-free. While extensive
results are available for light ion implantations, this effect is reported here
for the first time in the heavy ion regime, where a completely different range
of input parameters (in terms of ion species, energy, stopping power, etc.) is
available for customized irradiation. The chosen ion species are Au and Br, in
the energy range 10-40 MeV. The observed patterns, as characterized by
profilometry and atomic force microscopy, are reported in a series of model
experiments, which show swelling patterns ranging from a few nm to above 200
nm. Moreover, a systematic phenomenological modelling is presented, in which
surface swelling measurements are correlated to buried crystal damage. A
comparison is made with data for light ion implantations, showing good
compatibility with the proposed models. The modelling presented in this work
can be useful for the design and realization of micropatterned surfaces in
single crystal diamond, allowing to generate highly customized structures by
combining appropriately chosen irradiation parameters and masks.


title:
Multiple solutions for elliptic equations involving a general operator
  in divergence form

abstract:
  In this paper, exploiting variational methods, the existence of three weak
solutions for a class of elliptic equations involving a general operator in
divergence form and with Dirichlet boundary condition is investigated. Several
special cases are analyzed. In conclusion, for completeness, a concrete example
of an application is presented by finding the existence of three nontrivial
weak solutions for an uniformly elliptic second-order problem on a bounded
Euclidean domain.


title: Distances in domino flip graphs

abstract:
  This article is about measuring and visualizing distances between domino
tilings. Given two tilings of a simply connected square tiled surface, we're
interested in the minimum number of flips between two tilings. Given a certain
shape, we're interested in computing the diameters of the flip graphs, meaning
the maximal distance between any two of its tilings. Building on work of
Thurston and others, we give geometric interpretations of distances which
result in formulas for the diameters of the flip graphs of rectangles or Aztec
diamonds.


title: Curve counting on elliptic Calabi-Yau threefolds via derived categories

abstract:
  We prove the elliptic transformation law of Jacobi forms for the generating
series of Pandharipande--Thomas invariants of an elliptic Calabi--Yau 3-fold
over a reduced class in the base. This proves part of a conjecture by Huang,
Katz, and Klemm. For the proof we construct an involution of the derived
category and use wall-crossing methods. We express the generating series of PT
invariants in terms of low genus Gromov--Witten invariants and universal Jacobi
forms.
  As applications we prove new formulas and recover several known formulas for
the PT invariants of $\mathrm{K3} \times E$, abelian 3-folds, and the
STU-model. We prove that the generating series of curve counting invariants for
$\mathrm{K3} \times E$ with respect to a primitive class on the $\mathrm{K3}$
is a quasi-Jacobi form of weight -10. This provides strong evidence for the
Igusa cusp form conjecture.


title: The effects of surface roughness on lunar Askaryan pulses

abstract:
  The effects of lunar surface roughness, on both small and large scales, on
Askaryan radio pulses generated by particle cascades beneath the lunar surface
has never been fully estimated. Surface roughness affects the chances of a
pulse escaping the lunar surface, its coherency, and the characteristic
detection geometry. It will affect the expected signal shape, the relative
utility of different frequency bands, the telescope pointing positions on the
lunar disk, and most fundamentally, the chances of detecting the known UHE
cosmic ray and any prospective UHE neutrino flux. Near-future radio-telescopes
such as FAST and the SKA promise to be able to detect the flux of cosmic rays,
and it is critical that surface roughness be treated appropriately in
simulations. of the lunar Askaryan technique. In this contribution, a facet
model for lunar surface roughness is combined with a method to propagate
coherent radio pulses through boundaries to estimate the full effects of lunar
surface roughness on neutrino-detection probabilities. The method is able to
produce pulses from parameterised particle cascades beneath the lunar surface
as would be viewed by an observer at Earth, including all polarisation and
coherency effects. Results from this calculation are presented for both
characteristic cosmic ray and neutrino cascades, and estimates of the effects
mentioned above - particularly signal shape, frequency-dependence, and
sensitivity - are presented.


title:
Influence of Hydrodynamic Fluctuations on the Phase Transition in Models
  E and F of Critical Dynamics

abstract:
  We use the renormalization group method to study model E of critical dynamics
in the presence of velocity fluctuations arising in accordance with the
stochastic Navier-Stokes equation. Using Martin-Siggia-Rose theorem, we obtain
a field- theoretical model that allows a perturbative renormalization group
analysis. By direct power counting and an analysis of ultraviolet divergences,
we show that the model is multiplicatively renormalizable, and we use a
two-parameter expansion in $\varepsilon$ and $\delta$ to calculate
renormalization constants. Here, $\varepsilon$ is a deviation from the critical
dimension four, and $\delta$ is a deviation from the Kolmogorov regime. We
present the results of the one-loop approximation and part of the fixed-point
structure. We briefly discuss the possible effect of velocity fluctuations on
the large-scale behavior of the model.


title: A Context-aware Natural Language Generator for Dialogue Systems

abstract:
  We present a novel natural language generation system for spoken dialogue
systems capable of entraining (adapting) to users' way of speaking, providing
contextually appropriate responses. The generator is based on recurrent neural
networks and the sequence-to-sequence approach. It is fully trainable from data
which include preceding context along with responses to be generated. We show
that the context-aware generator yields significant improvements over the
baseline in both automatic metrics and a human pairwise preference test.


title:
All-nitride and In-free Al$_x$Ga$_{1-x}$N:Mn/GaN distributed Bragg
  reflectors for the near-infrared

abstract:
  Since the technological breakthrough prompted by the inception of light
emitting diodes based on III-nitrides, these material systems have emerged as
strategic semiconductors not only for the lighting of the future, but also for
the new generation of high-power electronic and spintronic devices. While
III-nitride optoelectronics in the visible and ultraviolet spectral range is
widely established, all-nitride and In-free efficient devices in the
near-infrared (NIR) are still wanted. Here, through a comprehensive protocol of
design, modeling, epitaxial growth and in-depth characterization, we develop
Al$_x$Ga$_{1-x}$N:Mn/GaN NIR distributed Bragg reflectors and we show their
efficiency in combination with GaN:(Mn,Mg) layers containing Mn-Mg$_{k}$
complexes optically active in the telecommunication range of wavelengths.


title: An efficient and flexible Abel-inversion method for noisy data

abstract:
  We propose an efficient and flexible method for solving Abel integral
equation of the first kind, frequently appearing in many fields of
astrophysics, physics, chemistry, and applied sciences. This equation
represents an ill-posed problem, thus solving it requires some kind of
regularization. Our method is based on solving the equation on a so-called
compact set of functions and/or using Tikhonov's regularization. A priori
constraints on the unknown function, defining a compact set, are very loose and
can be set using simple physical considerations. Tikhonov's regularization on
itself does not require any explicit a priori constraints on the unknown
function and can be used independently of such constraints or in combination
with them. Various target degrees of smoothness of the unknown function may be
set, as required by the problem at hand. The advantage of the method, apart
from its flexibility, is that it gives uniform convergence of the approximate
solution to the exact solution, as the errors of input data tend to zero. The
method is illustrated on several simulated models with known solutions. An
example of astrophysical application of the method is also given.


title:
Variation of constants formula and exponential dichotomy for non
  autonomous non densely defined Cauchy problems

abstract:
  In this paper we prove a variation of constants formula for a non autonomous
and non homogeneous Cauchy problems whenever the linear part is not densely
defined and is not a Hille-Yosida operator. By using this variation of
constants formula we derive a necessary and sufficient conditions for the
existence of exponential dichotomy for the evolution family generated by the
associated non autonomous homogeneous problem. We also prove a persistence
result of the exponential dichotomy for small perturbations. Finally we
illustrate our result by consider a parabolic equation with non local and non
autonomous boundary conditions.


title: Spin-asymmetric Josephson plasma oscillations

abstract:
  The spin-asymmetric Josephson effect is a proposed quantum-coherent
tunnelling phenomenon where Cooper-paired fermionic spin-$\frac{1}{2}$
particles, which are subjected to spin-dependent potentials across a Josephson
junction, undergo frequency-synchronized alternating-current Josephson
oscillations with spin-dependent amplitudes. Here, in line with present-day
techniques in ultracold Fermi gas setups, we consider the regime of small
Josephson oscillations and show that the Josephson plasma oscillation amplitude
becomes spin-dependent in the presence of spin-dependent potentials while the
Josephson plasma frequency is the same for both spin-components. Detecting
these spin-dependent Josephson plasma oscillations provides a possible means to
establish the yet-unobserved spin-asymmetric Josephson effect with ultracold
Fermi gases using existing experimental tools.


title: Complete $\alpha^6\,m$ corrections to the ground state of H$_2$

abstract:
  We perform the calculation of all relativistic and quantum electrodynamic
corrections of the order of $\alpha^6\,m$ to the ground electronic state of a
hydrogen molecule and present improved results for the dissociation and the
fundamental transitions energies. These results open the window for the
high-precision spectroscopy of H$_2$ and related low-energy tests of
fundamental interactions.


title: Instability of modes in a partially hinged rectangular plate

abstract:
  We consider a thin and narrow rectangular plate where the two short edges are
hinged whereas the two long edges are free. This plate aims to represent the
deck of a bridge, either a footbridge or a suspension bridge. We study a
nonlocal evolution equation modeling the deformation of the plate and we prove
existence, uniqueness and asymptotic behavior for the solutions for all initial
data in suitable functional spaces. Then we prove results on the
stability/instability of simple modes motivated by a phenomenon which is
visible in actual bridges and we complement these theorems with some numerical
experiments.


title:
Towards a uniform subword complex description of acyclic finite type
  cluster algebras

abstract:
  It has been established in recent years how to approach acyclic cluster
algebras of finite type using subword complexes. In this paper, we continue
this study by describing the c- and g-vectors, and by providing a conjectured
description of the Newton polytopes of the F-polynomials. In particular, we
show that this conjectured description would imply that finite type cluster
complexes are realized by the duals of the Minkowski sums of the Newton
polytopes of either the F-polynomials, or of the cluster variables,
respectively.


title:
Strengthened volume inequalities for L_p zonoids of even isotropic
  measures

abstract:
  We strengthen the volume inequalities for L_p zonoids of even isotropic
measures and for their duals, which are due to Ball, Barthe and Lutwak, Yang,
Zhang. Along the way, we prove a stronger version of the Brascamp-Lieb
inequality for a family of functions that can approximate arbitrary well some
Gaussians when equality holds. The special case p=\infty yields a stability
version of the reverse isoperimetric inequality for centrally symmetric bodies.


title:
Multimedia Storage in the Cloud using Amazon Web Services: Implications
  for Online Education

abstract:
  This report is divided into three parts. Firstly, an explanation of the cloud
storage products is given, in particular, the Amazon Simple Storage Service
(S3). Secondly, the report discusses a case study about SmugMug's migration to
the cloud hosted by Amazon. SmugMug is a premium online photo and video sharing
service business, and currently has billions of photos and videos from amateur
and professional photographers around the world. This report also includes a
step by step explanation of how to modify a website and use Amazon S3 to host
videos in the cloud. These findings are evaluated in terms of how useful Amazon
S3 can be for an e-learning institute, especially one that is geared towards
mobile delivery of content. Finally, the paper covers the copyright, and
privacy implications, in order to understand the larger context.


title: Why $\Xi(1690)$ and $\Xi(2120)$ are so narrow?

abstract:
  The $\Xi$ baryons are expected to be naturally narrower as compared to their
nonstrange and strange counterparts since they have only one light quark and,
thus, their decay involves producing either a light meson and doubly strange
baryon or both meson and baryon with strangeness which involves, relatively,
more energy. In fact, some $\Xi$'s have full widths of the order of even 10-20
MeV when, in principle, they have a large phase space to decay to some open
channels. Such is the case of $\Xi (1690)$, for which the width has been found
to be of the order of 10 MeV in the latest {\it BABAR} and BELLE data. In this
manuscript we study why some $\Xi$'s are so narrow. Based on a coupled channel
calculation of the pseudoscalar meson-baryon and vector meson-baryon systems
with chiral and hidden local symmetry Lagrangians, we find that the answer lies
in the intricate hadron dynamics. We find that the known mass, width,
spin-parity and branching ratios of $\Xi (1690)$ can be naturally explained in
terms of coupled channel meson-baryon dynamics. We find another narrow
resonance which can be related to $\Xi(2120)$. We also look for exotic states
$\Xi^{+}$ and $\Xi^{--}$ but find none. In addition we provide the cross
sections for $ \bar K \Lambda, \bar K \Sigma \rightarrow \pi \Xi$ which can be
useful for understanding the enhanced yield of $\Xi$ reported in recent studies
of heavy ion collisions.


title:
Softening the ultra-stiff: controlled variation of Young's modulus in
  single crystal diamond

abstract:
  A combined experimental and numerical study on the variation of the elastic
properties of defective single-crystal diamond is presented for the first time,
by comparing nano-indentation measurements on MeV-ion-implanted samples with
multi-scale modeling consisting of both ab initio atomistic calculations and
meso-scale Finite Element Method (FEM) simulations. It is found that by locally
introducing defects in the 2x10^18 - 5x10^21 cm-3 density range, a significant
reduction of, as well as of density, can be induced in the diamond crystal
structure without incurring in the graphitization of the material. Ab initio
atomistic simulations confirm the experimental findings with a good degree of
confidence. FEM simulations are further employed to verify the consistency of
measured deformations with a stiffness reduction, and to derive strain and
stress levels in the implanted region. Combining these experimental and
numerical results, we also provide insight into the mechanism responsible for
the depth dependence of the graphitization threshold in diamond. This work
prospects the possibility of achieving accurate tunability of the mechanical
properties of single-crystal diamond through defect engineering, with
significant technological applications, i.e. the fabrication and control of the
resonant frequency of diamond-based micromechanical resonators.


title: Do sound waves transport the AGN energy in the Perseus Cluster?

abstract:
  The level of random motions in the intracluster gas lying between 20 and 60
kpc radius in the core of the Perseus cluster has been measured by the Hitomi
Soft X-ray Spectrometer at 164 +/- 10 km/s. The maximum energy density in
turbulent motions on that scale is therefore low. If dissipated as heat the
turbulent energy will be radiated away in less than 80 Myr and cannot spread
across the core. A higher velocity is needed to prevent a cooling collapse.
Gravity waves are shown to travel too slowly in a radial direction. Here we
investigate propagation of energy by sound waves. The energy travels at about
1000 km/s and can cross the core in a cooling time. We show that the
displacement velocity amplitude of the gas required to carry the power is
consistent with the Hitomi result and that the inferred density and temperature
variations are consistent with Chandra observations.


title: Restricted volumes on K\"ahler manifolds

abstract:
  We study numerical restricted volumes of (1,1) classes on compact Kahler
manifolds, as introduced by Boucksom. Inspired by work of
Ein-Lazarsfeld-Mustata-Nakamaye-Popa on restricted volumes of line bundles on
projective manifolds, we pose a natural conjecture to the effect that
irreducible components of the non-Kahler locus of a big class should have
vanishing numerical restricted volume. We prove this conjecture when the class
has a Zariski decomposition, and give several applications.


title:
Hamiltonian Analysis of 3-Dimensional Connection Dynamics in Bondi-like
  Coordinates

abstract:
  The Hamiltonian analysis for a 3-dimensional connection dynamics of
$\frak{so}(1,2)$, spanned by $\{L_{-+},L_{-2},L_{+2}\}$ instead of $\{L_{01},
L_{02}, L_{12}\}$, is first conducted in a Bondi-like coordinate system.The
symmetry of the system is clearly presented. A null coframe with 3 independent
variables and 9 connection coefficients are treated as basic configuration
variables. All constraints and their consistency conditions, the solutions of
Lagrange multipliers as well as the equations of motion are presented. There is
no physical degree of freedom in the system. The Ba\~nados-Teitelboim-Zanelli
(BTZ) spacetime is discussed as an example to check the analysis. Unlike the
ADM formalism, where only non-degenerate geometries on slices are dealt with
and the Ashtekar formalism, where non-degenerate geometries on slices are
mainly concerned though the degenerate geometries may be studied as well, in
the present formalism the geometries on the slices are always degenerate though
the geometries for the spacetime are not degenerate.


title: Exact solution of the isotropic majority-vote model on complete graphs

abstract:
  The isotropic majority-vote (MV) model which, apart from the one-dimensional
case, is thought to be non-equilibrium and violating the detailed balance
condition. We show that this is not true, when the model is defined on a
complete graph. In the stationary regime, the MV model on a fully connected
graph fulfills the detailed balance. We derive the exact expression for the
probability distribution of finding the system in a given spin configuration.
We show that it only depends on the absolute value of magnetization. Our
theoretical predictions are validated by numerical simulations.


title:
Dramatic changes in DNA Conductance with stretching: Structural
  Polymorphism at a critical extension

abstract:
  In order to interpret recent experimental studies of the dependence of
conductance of ds-DNA as the DNA is pulled from the 3'end1-3'end2 ends, which
find a sharp conductance jump for a very short (4.5 %) stretching length, we
carried out multiscale modeling, to predict the conductance of dsDNA as it is
mechanically stretched to promote various structural polymorphisms. We
calculate the current along the stretched DNA using a combination of molecular
dynamics simulations, non-equilibrium pulling simulations, quantum mechanics
calculations, and kinetic Monte Carlo simulations. For 5'end1-5'end2
attachments we find an abrupt jump in the current within a very short
stretching length (6 $ \AA $ or 17 %) leading to a melted DNA state. In
contrast, for 3'end1-3'end2 pulling it takes almost 32$ \AA $ (84 %) of
stretching to cause a similar jump in the current. Thus, we demonstrate that
charge transport in DNA can occur over stretching lengths of several
nanometers. We find that this unexpected behaviour in the B to S conformational
DNA transition arises from highly inclined base pair geometries that result
from this pulling protocol. We find that the dramatically different conductance
behaviors for two different pulling protocols arise from the nature of how
hydrogen bonds of DNA base pairs break.


title:
Characterization of the recovery of mechanical properties of
  ion-implanted diamond after thermal annealing

abstract:
  Due to their outstanding mechanical properties, diamond and diamond-like
materials find significant technological applications ranging from
well-established industrial fields (cutting tools, coatings, etc.) to more
advanced mechanical devices as micro- and nano-electromechanical systems. The
use of energetic ions is a powerful and versatile tool to fabricate
three-dimensional micro-mechanical structures. In this context, it is of
paramount importance to have an accurate knowledge of the effects of
ion-induced structural damage on the mechanical properties of this material,
firstly to predict potential undesired side-effects of the ion implantation
process, and possibly to tailor the desired mechanical properties of the
fabricated devices. We present an Atomic Force Microscopy (AFM)
characterization of free-standing cantilevers in single-crystal diamond
obtained by a FIB-assisted lift-off technique, which allows a determination of
the Young's modulus of the diamond crystal after the MeV ion irradiation
process concurrent to the fabrication of the microstructures, and subsequent
thermal annealing. The AFM measurements were performed with the beam-bending
technique and show that the thermal annealing process allows for an effective
recovery of the mechanical properties of the pristine crystal.


title: A Novel Term_Class Relevance Measure for Text Categorization

abstract:
  In this paper, we introduce a new measure called Term_Class relevance to
compute the relevancy of a term in classifying a document into a particular
class. The proposed measure estimates the degree of relevance of a given term,
in placing an unlabeled document to be a member of a known class, as a product
of Class_Term weight and Class_Term density; where the Class_Term weight is the
ratio of the number of documents of the class containing the term to the total
number of documents containing the term and the Class_Term density is the
relative density of occurrence of the term in the class to the total occurrence
of the term in the entire population. Unlike the other existing term weighting
schemes such as TF-IDF and its variants, the proposed relevance measure takes
into account the degree of relative participation of the term across all
documents of the class to the entire population. To demonstrate the
significance of the proposed measure experimentation has been conducted on the
20 Newsgroups dataset. Further, the superiority of the novel measure is brought
out through a comparative analysis.


title:
Narrow C IV absorption doublets on quasar spectra of the Baryon
  Oscillation Spectroscopic Survey

abstract:
  In this paper, we extend our works of Papers I and II, which are assigned to
systematically survey \CIVab\ narrow absorption lines (NALs) with
\zabs$\ll$\zem\ on quasar spectra of the Baryon Oscillation Spectroscopic
Survey (BOSS), to collect \CIV\ NALs with \zabs$\approx$\zem\ from blue to red
wings of \CIVwave\ emission lines. Together with Papers I and II, we have
collected a total number of 41,479 \CIV\ NALs with $1.4544\le$\zabs$\le4.9224$
in surveyed spectral region redward of \lya\ until red wing of \CIVwave\
emission line. We find that the stronger \CIV\ NALs tend to be the more
saturated absorptions, and associated systems (\zabs$\approx$\zem) seem to have
larger absorption strengths when compared to intervening ones (\zabs$\ll$\zem).
The redshift density evolution behavior of absorbers (the number of absorbers
per redshift path) is similar to the history of the cosmic star formation. When
compared to the quasar-frame velocity ($\beta$) distribution of \MgII\
absorbers, the $\beta$ distribution of \CIV\ absorbers is broader at
$\beta\approx0$, shows longer extended tail, and exhibits a larger dispersion
for environmental absorptions. In addition, for associated \CIV\ absorbers, we
find that low-luminosity quasars seem to exhibit smaller $\beta$ and stronger
absorptions when compared to high-luminosity quasars.


title:
A New Class of Exponential Integrators for Stochastic Differential
  Equations With Multiplicative Noise

abstract:
  In this paper, we present new types of exponential integrators for Stochastic
Differential Equations (SDEs) that take the advantage of the exact solution of
(generalised) geometric Brownian motion. We examine both Euler and Milstein
versions of the scheme and prove strong convergence. For the special case of
linear noise we obtain an improved rate of convergence for the Euler version
over standard integration methods. We investigate the efficiency of the methods
compared with other exponential integrators and show that by introducing a
suitable homotopy parameter these schemes are competitive not only when the
noise is linear but also in the presence of nonlinear noise terms.


title:
Valley-Selective Topological Ordered States in Irradiated Bilayer
  Graphene

abstract:
  Gapless bilayer graphene is susceptible to a variety of spontaneously gapped
states. As predicted by theory and observed by experiment, the ground state is
however topologically trivial, because a valley-independent gap is
energetically favorable. Here, we show that under the application of interlayer
electric field and circularly polarized light, one valley can be selected to
exhibit the original interaction instability while the other is frozen out.
Tuning this Floquet system stabilizes multiple competing topological ordered
states, distinguishable by edge transport and circular dichroism. Notably,
quantized charge, spin, and valley Hall conductivities coexist in one
stabilized state.


title: Charge Transport in Dendrimer Melt using Multiscale Modeling Simulation

abstract:
  In this paper we present a theoretical calculation of the charge carrier
mobility in two different dendrimeric melt system (Dendritic phenyl azomethine
with Triphenyl amine core and Dendritic Carbazole with Cyclic Phenylazomethine
as core), which have recently been reported1 to increase the efficiency of
Dye-Sensitized solar cells (DSSCs) by interface modification. Our mobility
calculation, which is a combination of molecular dynamics simulation, first
principles calculation and kinetic Monte Carlo simulation, leads to mobilities
that are in quantitative agreement with available experimental data. We also
show how the mobility depends on the dendrimer generation. Furthermore, we
examine the variation of mobility with external electric field and external
reorganization energy. Physical mechanisms behind observed electric field and
generation dependencies of mobility are also explored.


title:
Measurement of the magnetic field profile in the atomic fountain clock
  FoCS-2 using Zeeman spectroscopy

abstract:
  We report the evaluation of the second order Zeeman shift in the continuous
atomic fountain clock FoCS-2. Because of the continuous operation and of its
geometrical constraints, the methods used in pulsed fountains are not
applicable. We use here time-resolved Zeeman spectroscopy to probe the magnetic
field profile in the clock. The pulses of ac magnetic excitation allow us to
spatially resolve the Zeeman frequency and to evaluate the Zeeman shift with a
relative uncertainty smaller than 10E-16.


title: Equations defining tangent cones of Gorenstein monomial curves

abstract:
  Let $C$ be a Gorenstein non complete intersection monomial curve in the
4-dimensional affine space. In this paper we study the minimal number of
generators of the tangent cone of $C$. Special attention will be paid to the
case where $C$ has Cohen-Macaulay tangent cone at the origin.


title: Solar-cycle variation of the rotational shear near the solar surface

abstract:
  Helioseismology has revealed that the angular velocity of the Sun increases
with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the
logarithmic radial gradient ($\rm d\ln\Omega/\rm d\ln r $) in the upper 10~Mm
is close to $-1$ from the equator to $60^\circ$ latitude.We aim to measure the
temporal variation of the rotational shear over solar cycle 23 and the rising
phase of cycle 24 (1996-2015). We used f mode frequency splitting data spanning
1996 to 2011 from the Michelson Doppler Imager (MDI) and 2010 to 2015 from the
Helioseismic Magnetic Imager (HMI). In a first for such studies, the f mode
frequency splitting data were obtained from 360-day time series. We used the
same method as in our previous work for measuring $\rm d\ln\Omega/d\ln r $ from
the equator to $80^\circ$ latitude in the outer 13~Mm of the Sun. Then, we
calculated the variation of the gradient at annual cadence relative to the
average over 1996 to 2015. We found the rotational shear at low latitudes
($0^\circ$ to $30^\circ$) to vary in-phase with the solar activity, varying by
$\sim \pm 10$\% over the period 1996 to 2015. At high latitudes ($60^\circ$ to
$80^\circ$), we found rotational shear to vary in anti-phase with the solar
activity. By comparing the radial gradient obtained from the splittings of the
360-day and the corresponding 72-day time series of HMI and MDI data, we
suggest that the splittings obtained from the 72-day HMI time series suffer
from systematic errors. We provide a quantitative measurement of the temporal
variation of the outer part of the near surface shear layer which may provide
useful constraints on dynamo models and differential rotation theory.


title: Multi-behavioral Sequential Prediction with Recurrent Log-bilinear Model

abstract:
  With the rapid growth of Internet applications, sequential prediction in
collaborative filtering has become an emerging and crucial task. Given the
behavioral history of a specific user, predicting his or her next choice plays
a key role in improving various online services. Meanwhile, there are more and
more scenarios with multiple types of behaviors, while existing works mainly
study sequences with a single type of behavior. As a widely used approach,
Markov chain based models are based on a strong independence assumption. As two
classical neural network methods for modeling sequences, recurrent neural
networks cannot well model short-term contexts, and the log-bilinear model is
not suitable for long-term contexts. In this paper, we propose a Recurrent
Log-BiLinear (RLBL) model. It can model multiple types of behaviors in
historical sequences with behavior-specific transition matrices. RLBL applies a
recurrent structure for modeling long-term contexts. It models several items in
each hidden layer and employs position-specific transition matrices for
modeling short-term contexts. Moreover, considering continuous time difference
in behavioral history is a key factor for dynamic prediction, we further extend
RLBL and replace position-specific transition matrices with time-specific
transition matrices, and accordingly propose a Time-Aware Recurrent
Log-BiLinear (TA-RLBL) model. Experimental results show that the proposed RLBL
model and TA-RLBL model yield significant improvements over the competitive
compared methods on three datasets, i.e., Movielens-1M dataset, Global
Terrorism Database and Tmall dataset with different numbers of behavior types.


title: Modelling and evaluation of a multi-tag LED-ID platform

abstract:
  An LED-ID system works like an electronic "tag" transmitting a short digital
broadcasted message. Low complexity LED-ID installations, being a subset of an
emerging class of visible light communication (VLC) systems, may be considered
as a replacement of popular RFID tags, Bluetooth tags and Wi-Fi beacons. In
this work, we focus on multi LED-ID environments with "dense" tag placement.
The problems that we focus on are estimating the level of cross-tag
interference and the issue of tag proximity: how closely can we place the tags
without making the system unusable? We present a theoretical model with a
numerical simulation of sample arrangements. We also describe the results of
experiments we conducted in a real- world test environment under different
external lighting conditions.


title:
Uniqueness in the Calder\'on problem via infinitesimally bounded
  potentials

abstract:
  The Calder\'on problem is an inverse problem with applications to electrical
impedance tomography and geophysical prospection. We prove uniqueness in the
Calder\'on problem in spatial dimension $n \geq 3$ for scalar conductivities in
the Sobolev space $W^{1,p}$ with $p \geq n$. This generalizes a result of
Haberman who considered the case $p \geq n$ and $n=3$ or $4$. Our method of
proof combines a Fourier series approach with an analytic criterion for
infinitesimal boundedness of potentials appearing in a Schr\"odinger equation
with respect to the Laplacian.


title:
Polarization measurement analysis III. Analysis of the polarization
  angle dispersion function with high precision polarization data

abstract:
  High precision polarization measurements open new opportunities for the study
of the magnetic field structure as traced by polarimetric measurements of the
interstellar dust emission. Polarization parameters suffer from bias in the
presence of measurement noise. It is critical to take into account all the
information available in the data in order to accurately derive these
parameters. The goal of this paper is to characterize the bias on the
polarization angle dispersion function that is used to study the spatial
coherence of the polarization angle. We characterize, for the first time, the
bias on the conventional estimator of the polarization angle dispersion
function (S hereafter) and show that it can be positive or negative depending
on the true value. Monte Carlo simulations are performed in order to explore
the impact of the noise properties of the polarization data, as well as the
impact of the distribution of the true polarization angles on the bias. We show
that in the case where the ellipticity of the noise in (Q, U) varies by less
than 10 percent, one can use simplified, diagonal approximation of the noise
covariance matrix. In other cases, the shape of the noise covariance matrix
should be taken into account in the estimation of S. We also study new
estimators such as the dichotomic and the polynomial estimators. Though the
dichotomic estimator cannot be directly used to estimate S, we show that, on
the one hand, it can serve as an indicator of the accuracy of the conventional
estimator and, on the other hand, it can be used for deriving the polynomial
estimator. We propose a method for determining the upper limit of the bias on
the conventional estimator of S. The method is applicable to any linear
polarization data set for which the noise covariance matrices are known.


title:
Influence of the electron beam emittance on the polarization of a
  laser--electron X-ray generator

abstract:
  In this paper we analyze the polarization of the X-ray radiation coming from
laser--electron X-ray generator (LEXG). We obtain general relations connecting
the polarization state of outgoing X-ray radiation to the polarization state of
laser beam as well as to the parameters of electron beam. We demonstrate that
finite electron beam emittance causes a partial depolarization of initially
fully polarized X-ray radiation even when the laser beam is fully polarized. We
demonstrate with a number of numerical experiments that finite electron beam
emittance can in some cases fundamentally alter the polarization state of X-ray
radiation as compared to the polarization state of X-ray radiation scattered by
electron beam with a zero emittance. Possible applications of polarized LEXG's
radiation are discussed.


title: Stellar classification of CoRoT targets

abstract:
  The CoRoT faint stars channel observed about 163 600 targets to detect
transiting planetary companions. Because CoRoT targets are faint (11< r <16)
and close to the galactic plane, only a small subsample has been observed
spectroscopically. We describe the latest classification scheme used to derive
the spectral type of CoRoT targets, which is based on broadband multi-colour
photometry. We assess the accuracy of this spectral classification for the
first time. We find that the classification method performs better for stars
that were observed during the mission-dedicated photometric ground-based
campaigns.The luminosity class is wrong for less than 7% of the targets.
Generally, the effective temperature of stars classified as early type (O, B,
and A) is overestimated. Conversely, the temperature of stars classified as
later type tends to be underestimated. This is mainly due to the adverse effect
of interstellar reddening. We find that the median error on the effective
temperature is less than 5% for dwarf stars classified with a spectral later
than F0, but it is worse for earlier type stars, with up to 20\% error for A
and late-B dwarfs, and up to 70% for early-B and O-type dwarfs. Similar results
are found for giants, with a median error that is lower than 7% for G- and
later type giants, but greater than 25% for earlier types. Overall, we find an
average median absolute temperature difference |Delta Teff| = 533+\-6 K for the
whole sample of stars classified as dwarfs and |Delta Teff| = 280+\-3 K for the
whole sample of giant stars. The corresponding standard deviation is of about
92+\-5 K for dwarfs and 304+\-4 K for giants. Typically for late-type stars,
this means that the classification is accurate to about half a class.


title:
Modelling the effect of curvature on the collective behaviour of cells
  growing new tissue

abstract:
  The growth of several biological tissues is known to be controlled in part by
local geometrical features, such as the curvature of the tissue interface. This
control leads to changes in tissue shape that in turn can affect the tissue's
evolution. Understanding the cellular basis of this control is highly
significant for bioscaffold tissue engineering, the evolution of bone
microarchitecture, wound healing, and tumour growth. While previous models have
proposed geometrical relationships between tissue growth and curvature, the
role of cell density and cell vigor remains poorly understood. We propose a
cell-based mathematical model of tissue growth to investigate the systematic
influence of curvature on the collective crowding or spreading of
tissue-synthesising cells induced by changes in local tissue surface area
during the motion of the interface. Depending on the strength of diffusive
damping, the model exhibits complex growth patterns such as undulating motion,
efficient smoothing of irregularities, and the generation of cusps. We compare
this model with in-vitro experiments of tissue deposition in bioscaffolds of
different geometries. By accounting for the depletion of active cells, the
model is able to capture both smoothing of initial substrate geometry and
tissue deposition slowdown as observed experimentally.


title: A single-atom quantum memory in silicon

abstract:
  Long coherence times and fast gate operations are desirable but often
conflicting requirements for physical qubits. This conflict can be resolved by
resorting to fast qubits for operations, and by storing their state in a
`quantum memory' while idle. The $^{31}$P donor in silicon comes naturally
equipped with a fast qubit (the electron spin) and a long-lived qubit (the
$^{31}$P nuclear spin), coexisting in a bound state at cryogenic temperatures.
Here, we demonstrate storage and retrieval of quantum information from a single
donor electron spin to its host phosphorus nucleus in isotopically-enriched
$^{28}$Si. The fidelity of the memory process is characterised via both state
and process tomography. We report an overall process fidelity of $F_p
=$81${\pm}$7%, a memory fidelity ($F_m$) of over 90%, and memory storage times
up to 80 ms. These values are limited by a transient shift of the electron spin
resonance frequency following high-power radiofrequency pulses.


title:
Interplay between Rashba spin-orbit coupling and adiabatic rotation in a
  two-dimensional Fermi gas

abstract:
  We explore the trap profiles of a two-dimensional atomic Fermi gas in the
presence of a Rashba spin-orbit coupling and under an adiabatic rotation. We
first consider a non-interacting gas and show that the competition between the
effects of Rashba coupling on the local density of single-particle states and
the Coriolis effects caused by rotation gives rise to a characteristic
ring-shaped density profile that survives at experimentally-accessible
temperatures. Furthermore, Rashba splitting of the Landau levels takes the
density profiles on a ziggurat shape in the rapid-rotation limit. We then
consider an interacting gas under the BCS mean-field approximation for local
pairing, and study the pair-breaking mechanism that is induced by the Coriolis
effects on superfluidity, where we calculate the critical rotation frequencies
both for the onset of pair breaking and for the complete destruction of
superfluidity in the system. In particular, by comparing the results of
fully-quantum-mechanical Bogoliubov-de Gennes approach with those of
semi-classical local-density approximation, we construct extensive phase
diagrams for a wide-range of parameter regimes in the trap where the
aforementioned competition may, e.g., favor an outer normal edge that is
completely phase separated from the central superfluid core by vacuum.


title:
Dwarf spheroidal J-factors without priors: A likelihood-based analysis
  for indirect dark matter searches

abstract:
  Line-of-sight integrals of the squared density, commonly called the J-factor,
are essential for inferring dark matter annihilation signals. The J-factors of
dark matter-dominated dwarf spheroidal satellite galaxies (dSphs) have
typically been derived using Bayesian techniques, which for small data samples
implies that a choice of priors constitutes a non-negligible systematic
uncertainty. Here we report the development of a new fully frequentist approach
to construct the profile likelihood of the J-factor. Using stellar kinematic
data from several classical and ultra-faint dSphs, we derive the maximum
likelihood value for the J-factor and its confidence intervals. We validate
this method, in particular its bias and coverage, using simulated data from the
Gaia Challenge. We find that the method possesses good statistical properties.
The J-factors and their uncertainties are generally in good agreement with the
Bayesian-derived values, with the largest deviations restricted to the systems
with the smallest kinematic datasets. We discuss improvements, extensions, and
future applications of this technique.

categories: astro-ph.CO astro-ph.GA astro-ph.HE hep-ph


title: Data-driven dissection of emission-line regions in Seyfert galaxies

abstract:
  Indirectly resolving the line-emitting gas regions in distant Active Galactic
Nuclei (AGN) requires both high-resolution photometry and spectroscopy (i.e.
through reverberation mapping). Emission in AGN originates on widely different
scales; the broad-line region (BLR) has a typical radius less than a few
parsec, the narrow-line region (NLR) extends out to hundreds of parsecs. But
emission also appears on large scales from heated nebulae in the host galaxies
(tenths of kpc).
  We propose a novel, data-driven method based on correlations between
emission-line fluxes to identify which of the emission lines are produced in
the same kind of emission-line regions. We test the method on Seyfert galaxies
from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and Galaxy Zoo
project.
  We demonstrate the usefulness of the method on Seyfert-1s and Seyfert-2
objects, showing similar narrow-line regions (NLRs). Preliminary results from
comparing Seyfert-2s in spiral and elliptical galaxy hosts suggest that the
presence of particular emission lines in the NLR depends both on host
morphology and eventual radio-loudness. Finally, we explore an apparent linear
relation between the final correlation coefficient obtained from the method and
time lags as measured in reverberation mapping for Zw229-015.


title:
Effects of high-power laser irradiation on sub-superficial graphitic
  layers in single crystal diamond

abstract:
  We report on the structural modifications induced by a lambda = 532 nm
ns-pulsed high-power laser on sub-superficial graphitic layers in
single-crystal diamond realized by means of MeV ion implantation. A systematic
characterization of the structures obtained under different laser irradiation
conditions (power density, number of pulses) and subsequent thermal annealing
was performed by different electron microscopy techniques. The main feature
observed after laser irradiation is the thickening of the pre-existing
graphitic layer. Cross sectional SEM imaging was performed to directly measure
the thickness of the modified layers, and subsequent selective etching of the
buried layers was employed to both assess their graphitic nature and enhance
the SEM imaging contrast. In particular, it was found that for optimal
irradiation parameters the laser processing induces a six-fold increase the
thickness of sub superficial graphitic layers without inducing mechanical
failures in the surrounding crystal. TEM microscopy and EELS spectroscopy
allowed a detailed analysis of the internal structure of the laser irradiated
layers, highlighting the presence of different nano graphitic and amorphous
layers. The obtained results demonstrate the effectiveness and versatility of
high-power laser irradiation for an accurate tuning of the geometrical and
structural features of graphitic structures embedded in single crystal diamond,
and open new opportunities in diamond fabrication.


title: Molecular Beam Epitaxy of thin HfTe2 semimetal films

abstract:
  Epitaxial thin films of 1T-HfTe2 semimetal are grown by MBE on AlN(0001)
substrates. The measured in-plane lattice parameter indicates an unstrained
film which is also azimuthally aligned with the AlN substrate, albeit with an
in-plane mosaic spread, as it would be expected for van der Waals epitaxy.
Angle resolved photoemission spectroscopy combined with first principles
electronic band structure calculations show steep linearly dispersing
conduction and valence bands which cross near the Brillouin zone center,
providing evidence that HfTe2 /AlN is an epitaxial topological Dirac semimetal.


title:
Aligning Packed Dependency Trees: a theory of composition for
  distributional semantics

abstract:
  We present a new framework for compositional distributional semantics in
which the distributional contexts of lexemes are expressed in terms of anchored
packed dependency trees. We show that these structures have the potential to
capture the full sentential contexts of a lexeme and provide a uniform basis
for the composition of distributional knowledge in a way that captures both
mutual disambiguation and generalization.


title: On a Conjecture of Dao-Kurano

abstract:
  We prove a special case of a conjecture of Dao-Kurano concerning the
vanishing of Hochster's theta pairing. The proof uses Adams operations on both
topological $K$-theory and perfect complexes with support.


title: Modelling Chemical Reasoning to Predict Reactions

abstract:
  The ability to reason beyond established knowledge allows Organic Chemists to
solve synthetic problems and to invent novel transformations. Here, we propose
a model which mimics chemical reasoning and formalises reaction prediction as
finding missing links in a knowledge graph. We have constructed a knowledge
graph containing 14.4 million molecules and 8.2 million binary reactions, which
represents the bulk of all chemical reactions ever published in the scientific
literature. Our model outperforms a rule-based expert system in the reaction
prediction task for 180,000 randomly selected binary reactions. We show that
our data-driven model generalises even beyond known reaction types, and is thus
capable of effectively (re-) discovering novel transformations (even including
transition-metal catalysed reactions). Our model enables computers to infer
hypotheses about reactivity and reactions by only considering the intrinsic
local structure of the graph, and because each single reaction prediction is
typically achieved in a sub-second time frame, our model can be used as a
high-throughput generator of reaction hypotheses for reaction discovery.


title: Algebraic classification of Robinson-Trautman spacetimes

abstract:
  We consider a general class of four-dimensional geometries admitting a null
vector field that has no twist and no shear but has an arbitrary expansion. We
explicitly present the Petrov classification of such Robinson-Trautman (and
Kundt) gravitational fields, based on the algebraic properties of the Weyl
tensor. In particular, we determine all algebraically special subcases when the
optically privileged null vector field is a multiple principal null direction
(PND), as well as all the cases when it remains a single PND. No field
equations are a priori applied, so that our classification scheme can be used
in any metric theory of gravity in four dimensions. In the classic Einstein
theory this reproduces previous results for vacuum spacetimes, possibly with a
cosmological constant, pure radiation and electromagnetic field, but can be
applied to an arbitrary matter content. As non-trivial explicit examples we
investigate specific algebraic properties of the Robinson-Trautman spacetimes
with a free scalar field, and also black hole spacetimes in the pure
Einstein-Weyl gravity.


title:
Structural transformation of implanted diamond layers during high
  temperature annealing

abstract:
  In the recent years graphitization of ion-beam induced amorphous layers
became the basic tool for device fabrication in diamond. The etchable graphitic
layers can be removed to form free-standing membranes into which the desired
structures can be sculpted using FIB milling. The optical properties of the
devices fabricated using this method are assumed on the model of sharp
diamond-air interface. The real quality of this interface could depend on
degree of graphitization of the amorphous damage layers after annealing. In the
present work the graphitization process was studied using conventional and
analytical TEM. It was found that annealing at 550 {\deg}C results in a partial
graphitization of the implanted volume with formation of the nano-crystalline
graphitic phase sandwiched between layers of tetrahedral amorphous carbon.
Annealing at 1400 {\deg}C resulted in complete graphitization of the amorphous
layers. The average size of graphite nano-crystals did not exceed 5 nm with
predominant orientation of c-planes normal to the sample surface.


title: Dynamics of a single trapped ion immersed in a buffer gas

abstract:
  We provide a comprehensive theoretical framework for describing the dynamics
of a single trapped ion interacting with a neutral buffer gas, thus extending
our previous studies on buffer-gas cooling of ions beyond the critical mass
ratio [B. H\"oltkemeier et al., Phys. Rev. Lett. 116, 233003 (2016)]. By
transforming the collisional processes into a frame, where the ion's
micromotion is assigned to the buffer gas atoms, our model allows one to
investigate the influence of non-homogeneous buffer gas configurations as well
as higher multipole orders of the radio-frequency trap in great detail.
Depending on the neutral-to-ion mass ratio, three regimes of sympathetic
cooling are identified which are characterized by the form of the ion's energy
distribution in equilibrium. We provide analytic expressions and numerical
simulations of the ion's energy distribution, spatial profile and cooling rates
for these different regimes. Based on these findings, a method for actively
decreasing the ion's energy by reducing the spatial expansion of the buffer gas
arises (Forced Sympathetic Cooling).


title: The flow of weights and the Cuntz-Pimsner algebras

abstract:
  We describe the flows of weights for von Neumann algebras arising from KMS
states for the gauge actions of the Cuntz-Pimsner algebras in terms of Poisson
(tail) boundaries.


title:
Micro-beam and pulsed laser beam techniques for the micro-fabrication of
  diamond surface and bulk structures

abstract:
  Micro-fabrication in diamond is involved in a wide set of emerging
technologies, exploiting the exceptional characteristics of diamond for
application in bio-physics, photonics, radiation detection. Micro ion-beam
irradiation and pulsed laser irradiation are complementary techniques, which
permit the implementation of complex geometries, by modification and
functionalization of surface and/or bulk material, modifying the optical,
electrical and mechanical characteristics of the material. In this article we
summarize the work done in Florence (Italy) concerning ion beam and pulsed
laser beam micro-fabrication in diamond.


title: Temperature-field phase diagram of geometrically frustrated CePdAl

abstract:
  From the electrical resistivity and ac susceptibility measurements down to
$T$ = 40 mK, a rich temperature-field phase diagram has been constructed for
the geometrically frustrated heavy-fermion compound CePdAl. In the limit of
zero temperature, the field-induced suppression of the antiferromagnetism in
this compound results in a sequence of phase transitions/corssovers, rather
than a single critical point, in a critical region of field 3$-$5 T. In the
lowest temperature region, a power-law description of the temperature-dependent
resistivity yields $A$$\cdot$$T^n$ with $n$$>$2 for all applied fields.
However, a quadratic-in-temperature resistivity term can be extracted when
assuming an additional electron scattering channel from magnon-like
excitations, with $A$ diverging upon approaching the critical regime. Our
observations suggest CePdAl to be a new playground for exotic physics arising
from the competition between Kondo screening and geometrical frustration.


title:
A representation for the Kantorovich--Rubinstein distance on the
  abstract Wiener space

abstract:
  A representation for the Kantorovich--Rubinstein distance between probability
measures on an abstract Wiener space in terms of the extended stochastic
integral (or, divergence) operator is obtained.


title:
Eternal non-Markovianity: from random unitary to Markov chain
  realisations

abstract:
  The theoretical description of quantum dynamics in an intriguing way does not
necessarily imply the underlying dynamics is indeed intriguing. Here we show
how a known very interesting master equation with an always negative decay rate
[eternal non-Markovianity (ENM)] arises from simple stochastic Schr\"odinger
dynamics (random unitary dynamics). Equivalently, it may be seen as arising
from a mixture of Markov (semi-group) open system dynamics. Both these
approaches lead to a more general family of CPT maps, characterized by a point
within a parameter triangle. Our results show how ENM quantum dynamics can be
realised easily in the laboratory. Moreover, we find a quantum
time-continuously measured (quantum trajectory) realisation of the dynamics of
the ENM master equation based on unitary transformations and projective
measurements in an extended Hilbert space, guided by a classical Markov
process. Furthermore, a Gorini-Kossakowski-Sudarshan-Lindblad (GKSL)
representation of the dynamics in an extended Hilbert space can be found, with
a remarkable property: there is no dynamics in the ancilla state. Finally,
analogous constructions for two qubits extend these results from
non-CP-divisible to non-P-divisible dynamics.


title:
Kelvin probe characterization of buried graphitic microchannels in
  single-crystal diamond

abstract:
  In this work, we present an investigation by Kelvin Probe Microscopy (KPM) of
buried graphitic microchannels fabricated in single-crystal diamond by direct
MeV ion microbeam writing. Metal deposition of variable-thickness masks was
adopted to implant channels with emerging endpoints and high temperature
annealing was performed in order to induce the graphitization of the
highly-damaged buried region. When an electrical current was flowing through
the biased buried channel, the structure was clearly evidenced by KPM maps of
the electrical potential of the surface region overlying the channel at
increasing distances from the grounded electrode. The KPM profiling shows
regions of opposite contrast located at different distances from the endpoints
of the channel. This effect is attributed to the different electrical
conduction properties of the surface and of the buried graphitic layer. The
model adopted to interpret these KPM maps and profiles proved to be suitable
for the electronic characterization of buried conductive channels, providing a
non-invasive method to measure the local resistivity with a micrometer
resolution. The results demonstrate the potential of the technique as a
powerful diagnostic tool to monitor the functionality of all-carbon
graphite/diamond devices to be fabricated by MeV ion beam lithography.