title:
AGN driven perturbations in the intra-cluster medium of cool core
  cluster ZwCl 2701

abstract:
  We present the results obtained from a total of 123 ks X-ray (Chandra) and 8
hrs of 1.4 GHz radio (Giant Metrewave Radio Telescope - GMRT) observations of
the cool core cluster ZwCl 2701 (z = 0.214). These observations of ZwCl 2701
showed the presence of an extensive pair of ellipsoidal cavities along the East
and West directions within the central region < 20 kpc. Detection of bright
rims around the cavities suggested that the radio lobes displaced X-ray
emitting hot gas forming shell-like structures. The total cavity power
(mechanical power) that directly heated the surrounding gas and cooling
luminosity of the cluster were estimated to be ~2.27 x 10^{45} erg\s and 3.5 x
10^{44} erg\s, respectively. Comparable values of cavity power and cooling
luminosity of ZwCL 2701 suggested that the mechanical power of the AGN outburst
is large enough to balance the radiative cooling in the system. The star
formation rate derived from the H_alpha luminosity was found to be ~0.60 M_sun
yr^{-1} which is about three orders of magnitude lower than the cooling rate of
~196 M_sun yr^{-1}. Detection of the floor in entropy profile of ZwCl 2701
suggested the presence of an alternative heating mechanism at the centre of the
cluster. Lower value of the ratio (~10^{-2}) between black hole mass accretion
rate and Eddington mass accretion rate suggested that launching of jet from the
super massive black hole is efficient in ZwCl 2701. However, higher value of
ratio (~10^{3}) between black hole mass accretion rate and Bondi accretion rate
indicated that the accretion rate required to create cavities is well above the
Bondi accretion rate.


title:
Uniformly accurate exponential-type integrators for klein-gordon
  equations with asymptotic convergence to classical splitting schemes in the
  nonlinear schroedinger limit

abstract:
  We introduce efficient and robust exponential-type integrators for
Klein-Gordon equations which resolve the solution in the relativistic regime as
well as in the highly-oscillatory non-relativistic regime without any step-size
restriction, and under the same regularity assumptions on the initial data
required for the integration of the corresponding limit system. In contrast to
previous works we do not employ any asymptotic/multiscale expansion of the
solution. This allows us derive uniform convergent schemes under far weaker
regularity assumptions on the exact solution. In particular, the newly derived
exponential-type integrators of first-, respectively, second-order converge in
the non-relativistic limit to the classical Lie, respectively, Strang splitting
in the nonlinear Schr{\"o}dinger limit.


title:
A Polymer Model with Epigenetic Recolouring Reveals a Pathway for the de
  novo Establishment and 3D Organisation of Chromatin Domains

abstract:
  One of the most important problems in development is how epigenetic domains
can be first established, and then maintained, within cells. To address this
question, we propose a framework which couples 3D chromatin folding dynamics,
to a "recolouring" process modelling the writing of epigenetic marks. Because
many intra-chromatin interactions are mediated by bridging proteins, we
consider a "two-state" model with self-attractive interactions between two
epigenetic marks which are alike (either active or inactive). This model
displays a first-order-like transition between a swollen, epigenetically
disordered, phase, and a compact, epigenetically coherent, chromatin globule.
If the self-attraction strength exceeds a threshold, the chromatin dynamics
becomes glassy, and the corresponding interaction network freezes. By modifying
the epigenetic read-write process according to more biologically-inspired
assumptions, our polymer model with recolouring recapitulates the
ultrasensitive response of epigenetic switches to perturbations, and accounts
for multi-domain conformations, strikingly similar to the
topologically-associating-domains observed in eukaryotic chromosomes.


title: Iron K$\alpha$ line of Kerr black holes with scalar hair

abstract:
  Recently, a family of hairy black holes in 4-dimensional Einstein gravity
minimally coupled to a complex, massive scalar field was discovered~\cite{hbh}.
Besides the mass $M$ and spin angular momentum $J$, these objects are
characterized by a Noether charge $Q$, measuring the amount of scalar hair,
which is not associated to a Gauss law and cannot be measured at spatial
infinity. Introducing a dimensionless scalar hair parameter $q$, ranging from 0
to 1, we recover (a subset of) Kerr black holes for $q=0$ and a family of
rotating boson stars for $q=1$. In the present paper, we explore the
possibility of measuring $q$ for astrophysical black holes with current and
future X-ray missions. We study the iron K$\alpha$ line expected in the
reflection spectrum of such hairy black holes and we simulate observations with
Suzaku and eXTP. As a proof of concept, we point out, by analyzing a sample of
hairy black holes, that current observations can already constrain the scalar
hair parameter $q$, because black holes with $q$ close to 1 would have iron
lines definitively different from those we observe in the available data. We
conclude that a detailed scanning of the full space of solutions, together with
data from the future X-ray missions, like eXTP, will be able to put relevant
constraints on the astrophysical realization of Kerr black holes with scalar
hair.


title:
Jenkins-Strebel Differentials on the Riemann Sphere with Four Simple
  Poles

abstract:
  A celebrated and deep theorem in the theory of Riemann surfaces states the
existence and uniqueness of the Jenkins-Strebel differentials on a Riemann
surface under some conditions, but the proof is non-constructive and examples
are difficult to find. This paper deals with an example of a simple case,
namely Jenkins-Strebel differentials on the Riemann sphere with four fixed
simple poles. We will give explicit expressions of these Jenkins-Strebel
differentials by means of the Weierstrass $\wp$ function and expose a simple
algorithm determining the correspondence between these differentials and some
classes of simple closed curves on the Riemann sphere with four points removed.


title: Gyrokinetic stability theory of electron-positron plasmas

abstract:
  The linear gyrokinetic stability properties of magnetically confined
electron-positron plasmas are investigated in the parameter regime most likely
to be relevant for the first laboratory experiments involving such plasmas,
where the density is small enough that collisions can be ignored and the Debye
length substantially exceeds the gyroradius. Although the plasma beta is very
small, electromagnetic effects are retained, but magnetic compressibility can
be neglected. The work of a previous publication (Helander, 2014) is thus
extended to include electromagnetic instabilities, which are of importance in
closed-field-line configurations, where such instabilities can occur at
arbitrarily low pressure. It is found that gyrokinetic instabilities are
completely absent if the magnetic field is homogeneous: any instability must
involve magnetic curvature or shear. Furthermore, in dipole magnetic fields,
the stability threshold for interchange modes with wavelengths exceeding the
Debye radius coincides with that in ideal MHD. Above this threshold, the
quasilinear particle flux is directed inward if the temperature gradient is
sufficiently large, leading to spontaneous peaking of the density profile.


title:
Photoluminescence of InGaAs/GaAsBi/InGaAs type-II quantum well grown by
  gas source molecular beam epitaxy

abstract:
  InGaAs/GaAsBi/InGaAs quantum wells (QWs) were grown on GaAs substrates by gas
source molecular beam epitaxy for realizing the type II band-edge line-up. Both
type I and type II transitions were observed in the Bi containing W QWs and the
photoluminescence intensity was enhanced in the sample with a high Bi content,
which is mainly due to the improvement of carrier confinement. Blue-shift of
type II transitions at high excitation power density was observed and ascribed
to the band-bending effect. The calculated transition energies based on 8 band
k.p model fit well with the experiment results. The experimental and
theoretical results show that the type-II QW design is a new promising
candidate for realizing long wavelength GaAs-based light emitting devices near
1.3 um.


title:
Pressure effect on magnetic susceptibility of SmS in semiconducting
  phase: experimental study

abstract:
  Magnetic susceptibility $\chi$ of the polycrystalline sample of samarium
monosulfide was measured as a function of the hydrostatic pressure $P$ up to 2
kbar at liquid nitrogen and room temperatures using a pendulum-type
magnetometer. A pronounced magnitude of the pressure effect is found to be
positive in sign and strongly temperature dependent: the pressure derivatives
of $\chi$, d\,ln$\chi$/d$P$, are $6.3\pm0.5$ and $14.2\pm1$ Mbar$^{-1}$ at 300
and 78 K, respectively. The obtained experimental results are discussed within
phenomenological approaches.


title: Qubit state tomography in superconducting circuit via weak measurements

abstract:
  The standard method of "measuring" quantum wavefunction is the technique of
{\it indirect} quantum state tomography. Owing to conceptual novelty and
possible advantages, an alternative {\it direct} scheme was proposed and
demonstrated recently in quantum optics system. In this work we present a study
on the direct scheme of measuring qubit state in the circuit QED system, based
on weak measurement and weak value concepts. To be applied to generic parameter
conditions, our formulation and analysis are carried out for finite strength
weak measurement, and in particular beyond the bad-cavity and weak-response
limits. The proposed study is accessible to the present state-of-the-art
circuit-QED experiments.


title:
Error analysis of a variational multiscale stabilization for
  convection-dominated diffusion equations in 2d

abstract:
  We formulate a stabilized quasi-optimal Petrov-Galerkin method for singularly
perturbed convection-diffusion problems based on the variational multiscale
method. The stabilization is of Petrov-Galerkin type with a standard finite
element trial space and a problem-dependent test space based on pre-computed
fine-scale correctors. The exponential decay of these correctors and their
localisation to local patch problems, which depend on the direction of the
velocity field and the singular perturbation parameter, is rigorously
justified. Under moderate assumptions, this stabilization guarantees stability
and quasi-optimal rate of convergence for arbitrary mesh P\'eclet numbers on
fairly coarse meshes at the cost of additional inter-element communication.


title:
Throughput Maximization for Decode-and-Forward Relay Channels with
  Non-Ideal Circuit Power

abstract:
  This paper studies the throughput maximization problem for a three-node relay
channel with non-ideal circuit power. In particular, the relay operates in a
half-duplex manner, and the decode-and-forward (DF) relaying scheme is adopted.
Considering the extra power consumption by the circuits, the optimal power
allocation to maximize the throughput of the considered system over an infinite
time horizon is investigated. First, two special scenarios, i.e., the direct
link transmission (only use the direct link to transmit) and the relay assisted
transmission (the source and the relay transmit with equal probability), are
studied, and the corresponding optimal power allocations are obtained. By
transforming two non-convex problems into quasiconcave ones, the closed-form
solutions show that the source and the relay transmit with certain probability,
which is determined by the average power budgets, circuit power consumptions,
and channel gains. Next, based on the above results, the optimal power
allocation for both the cases with and without direct link is derived, which is
shown to be a mixed transmission scheme between the direct link transmission
and the relay assisted transmission.


title:
Acceleration of Statistical Detection of Zero-day Malware in the Memory
  Dump Using CUDA-enabled GPU Hardware

abstract:
  This paper focuses on the anticipatory enhancement of methods of detecting
stealth software. Cyber security detection tools are insufficiently powerful to
reveal the most recent cyber-attacks which use malware. In this paper, we will
present first an idea of the highest stealth malware, as this is the most
complicated scenario for detection because it combines both existing
anti-forensic techniques together with their potential improvements. Second, we
present new detection methods, which are resilient to this hidden prototype. To
help solve this detection challenge, we have analyzed Windows memory content
using a new method of Shannon Entropy calculation; methods of digital
photogrammetry; the Zipf Mandelbrot law, as well as by disassembling the memory
content and analyzing the output. Finally, we present an idea and architecture
of the software tool, which uses CUDA enabled GPU hardware to speed-up memory
forensics. All three ideas are currently a work in progress.


title:
A rigorous sharp interface limit of a diffuse interface model related to
  tumor growth

abstract:
  In this paper we study the rigorous sharp interface limit of a diffuse
interface model related to the dynamics of tumor growth, when a parameter
$\epsilon$, representing the interface thickness between the tumorous and non
tumorous cells, tends to zero. More in particular, we analyze here a
gradient-flow type model arising from a modification of the recently introduced
model for tumor growth dynamics in [A. Hawkins-Daruud, K. G. van der Zee, J. T.
Oden, Numerical simulation of a thermodynamically consistent four-species tumor
growth model, Int. J. Numer. Math. Biomed. Engng. 28 (2011), 3--24.] (cf. also
[D. Hilhorst, J. Kampmann, T. N. Nguyen, K. G. van der Zee, Formal asymptotic
limit of a diffuse-interface tumor-growth model, Math. Models Methods Appl.
Sci. 25 (2015), 1011--1043.]). Exploiting the techniques related to both
gradient-flows and gamma convergence, we recover a condition on the interface
$\Gamma$ relating the chemical and double-well potentials, the mean curvature,
and the normal velocity.


title:
Local existence of a fourth order dispersive curve flow on locally
  hermitian symmetric spaces and the application

abstract:
  This paper is concerned with a fourth order nonlinear dispersive partial
differential equation for closed curve flow on a K\"ahler manifold. The main
results is that the initial value problem has a solution locally in time if the
K\"ahler manifold is a compact locally hermitian symmetric space. The proof is
based on the geometric energy method combined with a nice gauge transformation
to eliminate the loss of derivatives. Interestingly, the results can be applied
to construct a generalized bi-Schr\"odinger flow proposed by Ding and Wang. The
assumption on the manifold plays a crucial role both to enjoy a good solvable
structure of the problem and to reduce the generalized bi-Schr\"odinger flow
equation to the one considered in the present paper.


title: Periodic waves in unsaturated porous media with hysteresis

abstract:
  We consider a PDE system with degenerate hysteresis describing unsaturated
flow in 3D porous media. Assuming that a time periodic forcing is prescribed on
the boundary, we prove that a time periodic response exists as long as the
amplitude of the forcing terms is small enough to keep the solution within the
convexity domain of the hysteresis operator.


title: The essential role of time in network-based recommendation

abstract:
  Random walks on bipartite networks have been used extensively to design
personalized recommendation methods. While aging has been identified as a key
component in the growth of information networks, most research has focused on
the networks' structural properties and neglected the often available time
information. Time has been largely ignored both by the investigated
recommendation methods as well as by the methodology used to evaluate them. We
show that this time-unaware approach overestimates the methods' recommendation
performance. Motivated by microscopic rules of network growth, we propose a
time-aware modification of an existing recommendation method and show that by
combining the temporal and structural aspects, it outperforms the existing
methods. The performance improvements are particularly striking in systems with
fast aging.


title:
Exploring AGN - starburst coexistence in galaxies at z$\sim$ 0.8 by the
  [OIII]4959+5007/[OIII]4363 line ratio

abstract:
  We analyze by detailed modelling the spectra observed from the sample
galaxies at z$\sim$0.8 presented by Ly et al (2015), constraining the models by
the [OIII]5007+4959/[OIII]4363 line ratios. Composite models accounting for
shock and photoionization by AGN or starburst are adopted. O/H are about solar
for all the objects, except for a few AGN clouds with O/H= 0.3 -0.5 solar.
Starburst models reproduce most of the data within the observational errors.
About half of the object spectra are well fitted by an accreting AGN. Some
galaxies show multiple radiation sources, such as starburst+AGN, or a double
AGN.


title: Holographic superfluid flows with a localized repulsive potential

abstract:
  We investigate a holographic model of superfluid flows with an external
repulsive potential. When the strength of the potential is sufficiently weak,
we analytically construct two steady superfluid flow solutions. As the strength
of the potential is increased, the two solutions merge into a single critical
solution at a critical strength, and then disappear above the critical value,
as predicted by a saddle-node bifurcation theory. We also analyze the spectral
function of fluctuations around the solutions under a certain decoupling
approximation.


title: Parallel Space Saving on Multi and Many-Core Processors

abstract:
  Given an array $\mathcal{A}$ of $n$ elements and a value $2 \leq k \leq n$, a
frequent item or $k$-majority element is an element occurring in $\mathcal{A}$
more than $n/k$ times. The $k$-majority problem requires finding all of the
$k$-majority elements. In this paper we deal with parallel shared-memory
algorithms for frequent items; we present a shared-memory version of the Space
Saving algorithm and we study its behavior with regard to accuracy and
performance on many and multi-core processors, including the Intel Phi
accelerator. We also investigate a hybrid MPI/OpenMP version against a pure MPI
based version. Through extensive experimental results we prove that the
MPI/OpenMP parallel version of the algorithm significantly enhances the
performance of the earlier pure MPI version of the same algorithm. Results also
prove that for this algorithm the Intel Phi accelerator does not introduce any
improvement with respect to the Xeon octa-core processor.


title:
Redundancy Optimization of Finite-Dimensional Structures: A Concept and
  a Derivative-Free Algorithm

abstract:
  Redundancy is related to the amount of functionality that the structure can
sustain in the worst-case scenario of structural degradation. This paper
proposes a widely-applicable concept of redundancy optimization of
finite-dimensional structures. The concept is consistent with the robust
structural optimization, as well as the quantitative measure of structural
redundancy based on the information-gap theory. A derivative-free algorithm is
proposed based on the sequential quadratic programming (SQP) method, where we
use the finite-difference method with adaptively varying the difference
increment. Preliminary numerical experiments show that an optimal solution of
the redundancy optimization problem possibly has multiple worst-case scenarios.


title: Progressive Neural Networks

abstract:
  Learning to solve complex sequences of tasks--while both leveraging transfer
and avoiding catastrophic forgetting--remains a key obstacle to achieving
human-level intelligence. The progressive networks approach represents a step
forward in this direction: they are immune to forgetting and can leverage prior
knowledge via lateral connections to previously learned features. We evaluate
this architecture extensively on a wide variety of reinforcement learning tasks
(Atari and 3D maze games), and show that it outperforms common baselines based
on pretraining and finetuning. Using a novel sensitivity measure, we
demonstrate that transfer occurs at both low-level sensory and high-level
control layers of the learned policy.


title: Constitutional Precedent of Amicus Briefs

abstract:
  We investigate shared language between U.S. Supreme Court majority opinions
and interest groups' corresponding amicus briefs. Specifically, we evaluate
whether language that originated in an amicus brief acquired legal precedent
status by being cited in the Court's opinion. Using plagiarism detection
software, automated querying of a large legal database, and manual analysis, we
establish seven instances where interest group amici were able to formulate
constitutional case law, setting binding legal precedent. We discuss several
such instances for their implications in the Supreme Court's creation of case
law.


title: Symmetric identities for an analogue of Catalan polynomials

abstract:
  In this paper, we consider an analogue of Catalan polynomials and give some
identities of symmetry for those polynomials by using fermionic $p$-adic
integrals on the ring of $p$-adic integers


title: Star clusters as tracers of galactic nuclei properties

abstract:
  We present a series of $N$-body simulations representing the evolution of a
galactic nucleus and its stellar content in a nearly one-to-one representation.
The aim of this suite of simulations is to shed light on the interplay between
nuclear clusters (NCs), super-massive black holes (SMBH) and the galactic
nuclei in which they are contained. We modelled galaxies with masses from few
times $10^8$ to $10^{11}$ M$_\odot$, hosting in their nucleus a number of
globular clusters and, in some cases, a central SMBH.


title:
Parametrization of pair correlation function and static structure factor
  of the one component plasma across coupling regimes

abstract:
  We present a parametrization of the pair correlation function and the static
structure factor of the Coulomb one component plasma (OCP) from the weakly
coupled regime to the strongly coupled regime. Recent experiments strongly
suggest that the OCP model can play the role of a reference system for warm
dense matter. It can provide the ionic static structure factor that is
necessary to interpret the x-ray Thomson scattering measurements, for instance.
We illustrate this with the interpretation of a x-ray diffraction spectrum
recently measured, using a Bayesian method that requires many evaluations of
the static structure factor to automatically calibrate the parameters. For
strongly coupled dusty plasmas, the proposed parametrization of the Coulomb OCP
pair correlation function can be related to the Yukawa one, including
screening. Further prospects to parametrize the static structure of Yukawa
systems are also discussed.


title:
Photometric and H-alpha studies of two extreme mass-ratio short period
  contact binaries in the direction of open cluster Praesepe

abstract:
  We present the high precession photometric studies in V band and
spectroscopic studies centered around H-alpha line for two extreme mass-ratio
short period contact binaries ASAS J082243+1927.0 (V1) and ASAS J085710+1856.8
(V2). The variables in study are in the direction of open cluster Praesepe.
From the light curve analysis V1 was found to be a low mass-ratio over-contact
binary of A-type, with a mass ratio q 0.121 and fill-out factor f 72%, and V2
was found to be a low mass contact binary of W-type, with a mass-ratio q 1.29
and fill-out factor f 11% (marginal contact). The study of H-alpha absorption
line profile of both the variables shows variation in equivalent widths (EWs)
with orbital phases. The mean EWs of the H-alpha line were obtained as
1.6+or-0.13 A and 1.18+or-0.12 A for V1 and V2 respectively. The variation of
H-alpha absorption with respect to phase is explained to be due to
chromospheric activity in V1, as evident from the O Connell effect and that due
to chromospheric flares, winds or photospheric source in V2. The parameters for
both the binaries are also studied with respect to the large sample of
well-studied contact binaries and possible mechanisms for merger in contact
binaries of both low and high mass ratios emphasized.


title: Epimorphisms between $2$-bridge knot groups and their crossing numbers

abstract:
  Suppose that there exists an epimorphism from the knot group of a $2$-bridge
knot $K$ onto that of another knot $K'$. In this paper, we study the
relationship between their crossing numbers $c(K)$ and $c(K')$. Especially it
is shown that $c(K)$ is greater than or equal to $3 c(K')$ and we estimate how
many knot groups a $2$-bridge knot group maps onto. Moreover, we formulate the
generating function which determines the number of $2$-bridge knot groups
admitting epimorphisms onto the knot group of a given $2$-bridge knot.


title:
Strong Converse Theorems for Multimessage Networks with Tight Cut-Set
  Bound

abstract:
  This paper considers a multimessage network where each node may send a
message to any other node in the network. Under the discrete memoryless model,
we prove the strong converse theorem for any network whose cut-set bound is
tight, i.e., achievable. Our result implies that for any fixed rate vector that
resides outside the capacity region, the average error probabilities of any
sequence of length-$n$ codes operated at the rate vector must tend to $1$ as
$n$ approaches infinity. The proof is based on the method of types and is
inspired by the work of Csisz\'{a}r and K\"{o}rner in 1982 which fully
characterized the reliability function of any discrete memoryless channel (DMC)
with feedback for rates above capacity. In addition, we generalize the strong
converse theorem to the Gaussian model where each node is subject to an
almost-sure power constraint. Important consequences of our results are new
strong converses for the Gaussian multiple access channel (MAC) with feedback
and the following relay channels under both models: The degraded relay channel
(RC), the RC with orthogonal sender components, and the general RC with
feedback.


title:
Space-Efficient Biconnected Components and Recognition of Outerplanar
  Graphs

abstract:
  We present space-efficient algorithms for computing cut vertices in a given
graph with $n$ vertices and $m$ edges in linear time using $O(n+\min\{m,n\log
\log n\})$ bits. With the same time and using $O(n+m)$ bits, we can compute the
biconnected components of a graph. We use this result to show an algorithm for
the recognition of (maximal) outerplanar graphs in $O(n\log \log n)$ time using
$O(n)$ bits.


title:
Fair Simulation for Nondeterministic and Probabilistic Buechi Automata:
  a Coalgebraic Perspective

abstract:
  Notions of simulation, among other uses, provide a computationally tractable
and sound (but not necessarily complete) proof method for language inclusion.
They have been comprehensively studied by Lynch and Vaandrager for
nondeterministic and timed systems; for B\"{u}chi automata the notion of fair
simulation has been introduced by Henzinger, Kupferman and Rajamani. We
contribute to a generalization of fair simulation in two different directions:
one for nondeterministic tree automata previously studied by Bomhard; and the
other for probabilistic word automata with finite state spaces, both under the
B\"{u}chi acceptance condition. The former nondeterministic definition is
formulated in terms of systems of fixed-point equations, hence is readily
translated to parity games and is then amenable to Jurdzi\'{n}ski's algorithm;
the latter probabilistic definition bears a strong ranking-function flavor.
These two different-looking definitions are derived from one source, namely our
coalgebraic modeling of B\"{u}chi automata. Based on these coalgebraic
observations, we also prove their soundness: a simulation indeed witnesses
language inclusion.


title: Internal structure of hexagonal skyrmion lattices in cubic helimagnets

abstract:
  We have utilised a high spatial resolution imaging method, Differential Phase
Contrast (DPC) performed in a scanning transmission electron microscope (STEM),
for precise measurement of the magnetic induction distribution in skyrmion
states in noncentrosymmetric magnetically ordered materials. Applied to
investigate the internal structure of hexagonal skyrmion lattice cells,
stabilised by an out-plane applied magnetic field in an FeGe nanowedge
specimen, mapping of the in-plane component of magnetic induction has yielded
"average" skyrmion profiles and observation of internal six-fold symmetry. With
increasing field strength, the diameter of "average" skyrmion cores was
observed to decrease accompanied by a non-linear variation of the lattice
periodicity. Variations in structure for individual skyrmions were studied
utilising an advanced DPC detection scheme with a variety of symmetry lowering
distortions being observed. Our observations are consistent with a theoretical
phenomenological model, which has predicted the structure of hexagonal skyrmion
lattice cells and also that twisting states near to the material surfaces
provide a basis for energetic stabilisation of the skyrmion lattice over the
conical phase. There was good agreement with experiment for predictions of bulk
skyrmion structure and their response (core-size & lattice periodicity
variation) to an applied field.


title: TUnit - Unit Testing For Template-based Code Generators

abstract:
  Template-based code generator development as part of model-drivendevelopment
(MDD) demands for strong mechanisms and tools that support developers to
improve robustness, i.e., the desired code is generated for the specified
inputs. Although different testing methods have been proposed,a method for
testing only parts of template-based code generators that can be employed in
the early stage of development is lacking. Thus, in this paper we present an
approach and an implementation based on JUnit to test template-based code
generators. Rather than testing a complete code generator,it facilitates
partial testing by supporting the execution of templates with a mocked
environment. This eases testing of code generators in early stages of
development as well as testing new orchanged parts of a code generator. To test
the source code generated by the templates under test, different methods are
presented including string comparisons, API-based assertions, and abstract
syntax tree based assertions.


title: Probing Ionospheric Structures using the LOFAR radio telescope

abstract:
  LOFAR is the LOw Frequency Radio interferometer ARray located at mid-latitude
($52^{\circ} 53'N$). Here, we present results on ionospheric structures derived
from 29 LOFAR nighttime observations during the winters of 2012/2013 and
2013/2014. We show that LOFAR is able to determine differential ionospheric TEC
values with an accuracy better than 1 mTECU over distances ranging between 1
and 100 km. For all observations the power law behavior of the phase structure
function is confirmed over a long range of baseline lengths, between $1$ and
$80$ km, with a slope that is in general larger than the $5/3$ expected for
pure Kolmogorov turbulence. The measured average slope is $1.89$ with a one
standard deviation spread of $0.1$. The diffractive scale, i.e. the length
scale where the phase variance is $1\, \mathrm{rad^2}$, is shown to be an
easily obtained single number that represents the ionospheric quality of a
radio interferometric observation. A small diffractive scale is equivalent to
high phase variability over the field of view as well as a short time coherence
of the signal, which limits calibration and imaging quality. For the studied
observations the diffractive scales at $150$ MHz vary between $3.5$ and $30\,$
km. A diffractive scale above $5$ km, pertinent to about $90 \%$ of the
observations, is considered sufficient for the high dynamic range imaging
needed for the LOFAR Epoch of Reionization project. For most nights the
ionospheric irregularities were anisotropic, with the structures being aligned
with the Earth magnetic field in about $60\%$ of the observations.


title: Suppressing photochemical reactions with quantized light fields

abstract:
  Photoisomerization, i.e., a change of molecular structure after absorption of
a photon, is one of the most fundamental photochemical processes. It can
perform desirable functionality, e.g., as the primary photochemical event in
human vision, where it stores electronic energy in the molecular structure, or
for possible applications in solar energy storage and as memories, switches,
and actuators; but it can also have detrimental effects, for example as an
important damage pathway under solar irradiation of DNA, or as a limiting
factor for the efficiency of organic solar cells. While photoisomerization can
be avoided by shielding the system from light, this is of course not a viable
pathway for approaches that rely on the interaction with external light (such
as solar cells or solar energy storage). Here, we show that strong coupling of
organic molecules to a confined light mode can be used to strongly suppress
photoisomerization, and thus convert molecules that normally show fast
photodegradation into photostable forms.


title: Coherence of the ring of periodic distributions

abstract:
  It is shown that the ring of periodic distributions is a coherent ring (with
the operations of pointwise addition and convolution) by showing that the
isomorphic ring $s'$ of the Fourier coefficients (of sequences of at most
polynomial growth) with termwise operations is coherent. Moreover, it is shown
that the subring $\ell^\infty$ of $s'$ of all bounded sequences is coherent
too, while the subring $c$ of $\ell^\infty$ of all convergent sequences is not
coherent. It is also observed that $s'$ is a Hermite ring, but not a projective
free ring.


title:
Natural Language Generation as Planning under Uncertainty Using
  Reinforcement Learning

abstract:
  We present and evaluate a new model for Natural Language Generation (NLG) in
Spoken Dialogue Systems, based on statistical planning, given noisy feedback
from the current generation context (e.g. a user and a surface realiser). We
study its use in a standard NLG problem: how to present information (in this
case a set of search results) to users, given the complex trade- offs between
utterance length, amount of information conveyed, and cognitive load. We set
these trade-offs by analysing existing MATCH data. We then train a NLG pol- icy
using Reinforcement Learning (RL), which adapts its behaviour to noisy feed-
back from the current generation context. This policy is compared to several
base- lines derived from previous work in this area. The learned policy
significantly out- performs all the prior approaches.


title:
Distances between homotopy classes of $W^{s,p}({\mathbb S}^N;{\mathbb
  S}^N)$

abstract:
  We introduce an equivalence relation on $W^{s,p}({\mathbb S}^N;{\mathbb
S}^N)$ involving the topological degree, and we evaluate the distances (in the
usual sense and in the Hausdorff sense) between the equivalence classes. In
some special cases we even obtain exact formulas.


title:
A holomorphic vertex operator algebra of central charge $24$ whose
  weight one Lie algebra has type $A_{6,7}$

abstract:
  In this article, we describe a construction of a holomorphic vertex operator
algebras of central charge $24$ whose weight one Lie algebra has type
$A_{6,7}$.


title: Low field magnetoelectric effect in Fe substituted Co4Nb2O9

abstract:
  Co4Nb2O9 (CNO) having {\alpha}-Al2O3 crystal structure with Co chains along
c-direction shows gigantic magnetoelelctric coupling below antiferromagnetic
ordering temperature of 27 K but above a spin flop field of 1.6 T. We have
investigated structural, magnetic and magnetoelectric properties of Fe
substituted (10% and 20%) samples and compared with the parent one. In fact
magnetic and specific heat measurements have revealed an additional magnetic
transition below 10 K and presence of short range magnetic ordering above ~ 50
K in parent as well as in Fe substituted samples. Linear magnetoelelctric and
ferroelectric behaviours are evidenced in the Fe substituted samples where an
electric field of 5 kV/m is sufficient to align the dipoles and the
magnetoelelctric coupling is ensured for magnetic fields as low as 0.25 T, far
below the spin flop field.


title: On partial sums of normalized Mittag-Leffler functions

abstract:
  This article deals with the ratio of normalized Mittag-Leffler function
$\mathbb{E}_{\alpha,\beta}(z)$ and its sequence of partial sums
$(\mathbb{E}_{\alpha,\beta})_m(z)$. Several examples which illustrate the
validity of our results are also given.


title: Cosmology and the neutrino mass ordering

abstract:
  We propose a simple method to quantify a possible exclusion of the inverted
neutrino mass ordering from cosmological bounds on the sum of the neutrino
masses. The method is based on Bayesian inference and allows for a calculation
of the posterior odds of normal versus inverted ordering. We apply the method
for a specific set of current data from Planck CMB data and large-scale
structure surveys, providing an upper bound on the sum of neutrino masses of
0.14 eV at 95% CL. With this analysis we obtain posterior odds for normal
versus inverted ordering of about 2:1. If cosmological data is combined with
data from oscillation experiments the odds reduce to about 3:2. For an
exclusion of the inverted ordering from cosmology at more than 95% CL, an
accuracy of better than 0.02 eV is needed for the sum. We demonstrate that such
a value could be reached with planned observations of large scale structure by
analysing artificial mock data for a EUCLID-like survey.


title: Generalized relativistic kinematics in Poincar\'e-invariant models

abstract:
  Assuming the validity of the relativity principle, we discuss the
implications on relativistic kinematics of a deformation of the Poincar\'e
invariance that preserves the Poincar\'e algebra, and only modifies its action
on phase space in a Lorentz-invariant way. We show that, in contrast to the
case where the Poincar\'e algebra is deformed, the action of boosts on
two-particle states is not affected, while the addition law of momenta is to a
large extent arbitrary. We give some nontrivial examples of this arising from
doubly special relativity and noncommutative geometry and show that
Hopf-algebra methods give equivalent results.


title: Invariance of the White Noise for the Ostrovsky equation

abstract:
  In this paper, we construct invariant measures for the Ostrovsky equation
associated with the norm $L^2$. On the other hand, we prove the local well-
posedness in the besov space $\hat{b}^s_{p,\infty}$ for $sp >-1$.


title: Scale Down Experiments for a Stellarator type Magnetostatic Storage Ring

abstract:
  The beam transport experiments in toroidal magnets were first described in
EPAC08 [1] within the framework of a proposed low energy ion storage ring at
Frankfurt University. The experiments with two room temperature 30 degree
toroids are needed to design the accumulator ring with closed longitudinal
magnetic field levels up to 6-8 T. The test setup aims on developing a ring
injection system. The primary beam line for the experiments was installed and
successfully commissioned in 2009. A special probe for ion beam detection was
installed. This modular technique allows online diagnostics of the ion beam
along the beam path. In this paper, we present new results on beam transport
experiments and discuss transport and transverse beam injection properties of
that system.


title: Strategic Attentive Writer for Learning Macro-Actions

abstract:
  We present a novel deep recurrent neural network architecture that learns to
build implicit plans in an end-to-end manner by purely interacting with an
environment in reinforcement learning setting. The network builds an internal
plan, which is continuously updated upon observation of the next input from the
environment. It can also partition this internal representation into contiguous
sub- sequences by learning for how long the plan can be committed to - i.e.
followed without re-planing. Combining these properties, the proposed model,
dubbed STRategic Attentive Writer (STRAW) can learn high-level, temporally
abstracted macro- actions of varying lengths that are solely learnt from data
without any prior information. These macro-actions enable both structured
exploration and economic computation. We experimentally demonstrate that STRAW
delivers strong improvements on several ATARI games by employing temporally
extended planning strategies (e.g. Ms. Pacman and Frostbite). It is at the same
time a general algorithm that can be applied on any sequence data. To that end,
we also show that when trained on text prediction task, STRAW naturally
predicts frequent n-grams (instead of macro-actions), demonstrating the
generality of the approach.


title: Geodesic Walks in Polytopes

abstract:
  We introduce the geodesic walk for sampling Riemannian manifolds and apply it
to the problem of generating uniform random points from polytopes in R^n
specified by m inequalities. The walk is a discrete-time simulation of a
stochastic differential equation (SDE) on the Riemannian manifold equipped with
the metric induced by the Hessian of a convex function; each step is the
solution of an ordinary differential equation (ODE). The resulting sampling
algorithm for polytopes mixes in O*(mn^{3/4}) steps. This is the first walk
that breaks the quadratic barrier for mixing in high dimension, improving on
the previous best bound of O*(mn) by Kannan and Narayanan for the Dikin walk.
We also show that each step of the geodesic walk (solving an ODE) can be
implemented efficiently, thus improving the time complexity for sampling
polytopes. Our analysis of the geodesic walk for general Hessian manifolds does
not assume positive curvature and might be of independent interest.


title: Quantum Computing with Acceptor Spins in Silicon

abstract:
  The states of a boron acceptor near a Si/SiO2 interface, which bind two
low-energy Kramers pairs, have exceptional properties for encoding quantum
information and, with the aid of strain, both heavy hole and light hole-based
spin qubits can be designed. Whereas a light-hole spin qubit was introduced
recently [Phys. Rev. Lett. 116, 246801 (2016)], here we present analytical and
numerical results proving that a heavy-hole spin qubit can be reliably
initialised, rotated and entangled by electrical means alone. This is due to
strong Rashba-like spin-orbit interaction terms enabled by the interface
inversion asymmetry. Single qubit rotations rely on electric-dipole spin
resonance (EDSR), which is strongly enhanced by interface-induced spin-orbit
terms. Entanglement can be accomplished by Coulomb exchange, coupling to a
resonator, or spin-orbit induced dipole-dipole interactions. By analysing the
qubit sensitivity to charge noise, we demonstrate that interface-induced
spin-orbit terms are responsible for sweet spots in the dephasing time T2* as a
function of the top gate electric field, which are close to maxima in the EDSR
strength, where the EDSR gate has high fidelity. We show that both qubits can
be described using the same starting Hamiltonian, and by comparing their
properties we show that the complex interplay of bulk and interface-induced
spin-orbit terms allows a high degree of electrical control and makes acceptors
potential candidates for scalable quantum computation in Si.


title: Invariant recognition drives neural representations of action sequences

abstract:
  Recognizing the actions of others from visual stimuli is a crucial aspect of
human visual perception that allows individuals to respond to social cues.
Humans are able to identify similar behaviors and discriminate between distinct
actions despite transformations, like changes in viewpoint or actor, that
substantially alter the visual appearance of a scene. This ability to
generalize across complex transformations is a hallmark of human visual
intelligence. Advances in understanding motion perception at the neural level
have not always translated in precise accounts of the computational principles
underlying what representation our visual cortex evolved or learned to compute.
Here we test the hypothesis that invariant action discrimination might fill
this gap. Recently, the study of artificial systems for static object
perception has produced models, CNNs, that achieve human level performance in
complex discriminative tasks. Within this class of models, architectures that
better support invariant object recognition also produce image representations
that match those implied by human and primate neural data. However, whether
these models produce representations of action sequences that support
recognition across complex transformations and closely follow neural
representations remains unknown. Here we show that spatiotemporal CNNs
appropriately categorize video stimuli into actions, and that deliberate model
modifications that improve performance on an invariant action recognition task
lead to data representations that better match human neural recordings. Our
results support our hypothesis that performance on invariant discrimination
dictates the neural representations of actions computed by human visual cortex.


title:
Q-factor and absorption enhancement for plasmonic anisotropic
  nanoparticles

abstract:
  We investigate the scattering and absorption properties of anisotropic
metal-dielectric core-shell nanoparticles. It is revealed that the radially
anisotropic dielectric layer can accelerate the evanescent decay of the
localized resonant surface modes, leading to Q-factor and absorption rate
enhancement. Moreover, the absorption cross section can be maximized to reach
the single resonance absorption limit. We further show that such artificial
anisotropic cladding materials can be realized by isotropic layered structures,
which may inspire many applications based on scattering and absorption of
plasmonic nanoparticles.


title:
Decay of density waves in coupled one-dimensional many-body-localized
  systems

abstract:
  The behavior of coupled disordered one-dimensional systems, as modelled by
identical fermionic Hubbard chains with the on-site potential disorder and
coupling emerging through the inter-chain hopping $t'$, is analysed. The study
is motivated by the experiment on fermionic cold atoms on a disordered lattice,
where a decay rate of the quenched density wave was measured. We present a
derivation of the decay rate $\Gamma$ within perturbation theory and show that
even at large disorder along the chains the interaction leads to finite $\Gamma
> 0$, the mechanism being the interaction-induced coupling of in-chain
localized and inter-chain extended single-fermion states. Explicit expressions
for $\Gamma$ are presented for a weak interaction $U < t,t'$, but extended also
to the regime $t > U >t'$. It is shown that in both regimes $\Gamma$ increases
with the inter-chain hopping $t'$, as well as decreases with increasing
disorder.


title:
Some stability problems to the Navier-Stokes equations in the periodic
  case

abstract:
  The Navier-Stokes motions in a box with periodic boundary conditions are
considered. First the existence of global regular two-dimensional solutions is
proved. The solutions are such that continuous with respect to time norms are
controlled by the same constant for all $t\in\mathbb{R}_+$. Assuming that the
initial velocity and the external force are sufficiently close to the initial
velocity and the external force of the two-dimensional solutions we prove
existence of global three-dimensional regular solutions which remain close to
the two-dimensional solutions for all time. In this way we mean stability of
two-dimensional solutions.


title:
DeepProposals: Hunting Objects and Actions by Cascading Deep
  Convolutional Layers

abstract:
  In this paper, a new method for generating object and action proposals in
images and videos is proposed. It builds on activations of different
convolutional layers of a pretrained CNN, combining the localization accuracy
of the early layers with the high informative-ness (and hence recall) of the
later layers. To this end, we build an inverse cascade that, going backward
from the later to the earlier convolutional layers of the CNN, selects the most
promising locations and refines them in a coarse-to-fine manner. The method is
efficient, because i) it re-uses the same features extracted for detection, ii)
it aggregates features using integral images, and iii) it avoids a dense
evaluation of the proposals thanks to the use of the inverse coarse-to-fine
cascade. The method is also accurate. We show that our DeepProposals outperform
most of the previously proposed object proposal and action proposal approaches
and, when plugged into a CNN-based object detector, produce state-of-the-art
detection performance.


title: Notes on socio-economic transparency mechanisms

abstract:
  Clearly, socio-economic freedom requires some extent of transparency
regarding the implications of choices. In this paper, we review some
established mechanisms for achieving such transparency, without any claim to
completeness, and briefly discuss potential future directions. Our
investigation is structured by four "challenges" under which we subsume the
various requirements on, and approaches to, socio-economic transparency
mechanisms. One main focus is on the inference, i.e., statistical, aspect of
such mechanisms.


title: The First Stars in the Universe

abstract:
  The basic processes of the formation of the first stars in the primordial
Universe are outlined and the implications for cosmological structure formation
discussed. By employing theoretical and numerical models of cosmic structure
evolution embedded within N-body hydrodynamical chemistry simulations,
predictions for the production of the first heavy elements in the Universe are
given. These results are then compared against measured data of UV luminosities
and metal abundances in different kinds of observations in order to draw
conclusions on the chemical and thermal state of the cosmic medium at different
cosmological epochs.


title: TwinCloud: Secure Cloud Sharing Without Explicit Key Management

abstract:
  With the advent of cloud technologies, there is a growing number of
easy-to-use services to store files and share them with other cloud users. By
providing security features, cloud service providers try to encourage users to
store personal files or corporate documents on their servers. However, their
server-side encryption solutions are not satisfactory when the server itself is
not trusted. Although, there are several client-side solutions to provide
security for cloud sharing, they are not used extensively because of usability
issues in key management.
  In this paper, we propose TwinCloud which is an innovative solution with the
goal of providing a secure system to users without compromising the usability
of cloud sharing. TwinCloud achieves this by bringing a novel solution to the
complex key exchange problem and by providing a simple and practical approach
to store and share files by hiding all the cryptographic and key-distribution
operations from users. Serving as a gateway, TwinCloud uses two or more cloud
providers to store the encryption keys and encrypted files in separate clouds
which ease the secure sharing without a need for trust to either of the cloud
service providers with the assumption that they do not collude with each other.
We implemented TwinCloud as a lightweight application and make it available as
open-source. The results of our usability study show the prospect of the secure
sharing solution of TwinCloud.


title:
Large Upper Critical Field of Superconductivity in the Single Crystal
  U6Co

abstract:
  We grew single crystals of U6Co by the self-flux method and measured the
magnetic susceptibility, resistivity, and specific heat. The magnetic
susceptibility shows very small anisotropy and weak temperature dependence,
indicating small spin-susceptibility. Superconductivity was clearly observed in
the resistivity, susceptibility, and specific heat at Tc~2.3K. The upper
critical field was remarkably large, 7.9 and 6.6T for H || [001] and [110],
respectively, in the tetragonal structure, indicating that the ellipsoidal
Fermi surface is slightly suppressed along the [001] direction according to the
effective mass model. The specific heat shows a large jump at Tc with Delta
C/gamma Tc = 1.58, and the field dependence of the specific heat at low
temperatures shows an almost linear increase. These experimental results are
well explained by the BCS model in the dirty limit condition. U6Co is most
likely a conventional s-wave superconductor with a full superconducting gap.


title: A conceptual approach to model co-evolution of urban structures

abstract:
  Urban structures encompass settlements, characterized by the spatial
distribution of built-up areas, but also transportation structures, to connect
these built-up areas. These two structures are very different in their origin
and function, fulfilling complementary needs: (i) to access space, and (ii) to
occupy space. Their evolution cannot be understood by looking at the dynamics
of urban aggregations and transportation systems separately. Instead, existing
built-up areas feed back on the further development of transportation
structures, and the availability of the latter feeds back on the future growth
of urban aggregations. To model this co-evolution, we propose an agent-based
approach that builds on existing agent-based models for the evolution of trail
systems and of urban settlements. The key element in these separate approaches
is a generalized communication of agents by means of an adaptive landscape.
This landscape is only generated by the agents, but once it exists, it feeds
back on their further actions. The emerging trail system or urban aggregation
results as a self-organized structure from these collective interactions. In
our co-evolutionary approach, we couple these two separate models by means of
meta-agents that represent humans with their different demands for housing and
mobility. We characterize our approach as a statistical ensemble approach,
which allows to capture the potential of urban evolution in a bottom-up manner,
but can be validated against empirical observations.


title: On endoscopic p-adic automorphic forms for SL(2)

abstract:
  We show the existence of some non-classical cohomological p-adic automorphic
eigenforms for SL(2) using endoscopy and the geometry of eigenvarieties. These
forms seem to account for some non-automorphic members of classical global
L-packets.


title:
Comment on "Creating in-plane pseudomagnetic fields in excess of 1000 T
  by misoriented stacking in a graphene bilayer"

abstract:
  In a recent paper [Phys. Rev. B 89, 125418 (2014)], the authors argue that it
is possible to map the electronic properties of twisted bilayer graphene to
those of bilayer graphene in an in-plane magnetic field. However, their
description of the low-energy dynamics of twisted bilayer graphene is
restricted to the extended zone scheme and therefore neglects the effects of
the superperiodic structure. If the energy spectrum is studied in the supercell
Brillouin zone, we find that the comparison with an in-plane magnetic field
fails because (i) the energy spectra of the two situations exhibit different
symmetries and (ii) the low-energy spectra are very different.


title:
Physical properties of Polyakov loop geometrical clusters in SU(2)
  gluodynamics

abstract:
  We apply the liquid droplet model to describe the clustering phenomenon in
SU(2) gluodynamics, especially, in the vicinity of the deconfinement phase
transition. In particular, we analyze the size distributions of clusters formed
by the Polyakov loops of the same sign. Within such an approach this phase
transition can be considered as the transition between two types of liquids
where one of the liquids (the largest droplet of a certain Polyakov loop sign)
experiences a condensation, while the other one (the next to largest droplet of
opposite Polyakov loop sign) evaporates. The clusters of smaller sizes form two
accompanying gases, and their size distributions are described by the liquid
droplet parameterization. By fitting the lattice data we have extracted the
value of Fisher exponent $\tau =$ 1.806 $\pm$ 0.008. Also we found that the
temperature dependences of the surface tension of both gaseous clusters are
entirely different below and above the phase transition and, hence, they can
serve as an order parameter. The critical exponents of the surface tension
coefficient in the vicinity of the phase transition are found. Our analysis
shows that the temperature dependence of the surface tension coefficient above
the critical temperature has a $T^2$ behavior in one gas of clusters and $T^4$
in the other one.


title:
Observations of three young gamma-ray pulsars with the Gran Telescopio
  Canarias

abstract:
  We report the analysis of the first deep optical observations of three
isolated $\gamma$-ray pulsars detected by the {\em Fermi Gamma-ray Space
Telescope}: the radio-loud PSR\, J0248+6021 and PSR\, J0631+1036, and the
radio-quiet PSR\, J0633+0632. The latter has also been detected in the X rays.
The pulsars are very similar in their spin-down age ($\tau \sim$40--60 kyrs),
spin-down energy ($\dot{E} \sim10^{35}$ erg s$^{-1}$), and dipolar surface
magnetic field ($B \sim 3$--$5\times10^{12}$ G). These pulsars are promising
targets for multi-wavelength observations, since they have been already
detected in $\gamma$ rays and in radio or X-rays. None of them has been
detected yet in the optical band. We observed the three pulsar fields in 2014
with the Spanish 10.4m Gran Telescopio Canarias (GTC). We could not find any
candidate optical counterpart to the three pulsars close to their most recent
radio or {\em Chandra} positions down to $3 \sigma$ limits of $g'\sim27.3$,
$g'\sim27$, $g'\sim27.3$ for PSR\, J0248+6021, J0631+1036, and J0633+0632,
respectively. From the inferred optical upper limits and estimated distance and
interstellar extinction, we derived limits on the pulsar optical luminosity. We
also searched for the X-ray counterpart to PSR\, J0248+6021 with \chan\ but we
did not detect the pulsar down to a 3$\sigma$ flux limit of $5 \times 10^{-14}$
erg cm$^{-2}$ s$^{-1}$ (0.3--10 keV). For all these pulsars, we compared the
optical flux upper limits with the extrapolations in the optical domain of the
$\gamma$-ray spectra and compared their multi-wavelength properties with those
of other $\gamma$-ray pulsars of comparable age.


title:
Weyl Representation of the Canonical Commutation Relations Algebras in a
  Krein Space

abstract:
  In the present article the existence of the Weyl representation for the
canonical commutation relations algebras was proved in a Krein space.


title: Does horizon entropy satisfy a Quantum Null Energy Conjecture?

abstract:
  A modern version of the idea that the area of event horizons gives $4G$ times
an entropy is the Hubeny-Rangamani Causal Holographic Information (CHI)
proposal for holographic field theories. Given a region $R$ of a holographic
QFTs, CHI computes $A/4G$ on a certain cut of an event horizon in the
gravitational dual. The result is naturally interpreted as a coarse-grained
entropy for the QFT. CHI is known to be finitely greater than the fine-grained
Hubeny-Rangamani-Takayanagi (HRT) entropy when $\partial R$ lies on a Killing
horizon of the QFT spacetime, and in this context satisfies other non-trivial
properties expected of an entropy. Here we present evidence that it also
satisfies the quantum null energy condition (QNEC), which bounds the second
derivative of the entropy of a quantum field theory on one side of a
non-expanding null surface by the flux of stress-energy across the surface. In
particular, we show CHI to satisfy the QNEC in 1+1 holographic CFTs when
evaluated in states dual to conical defects in AdS$_3$. This surprising result
further supports the idea that CHI defines a useful notion of coarse-grained
holographic entropy, and suggests unprecedented bounds on the rate at which
bulk horizon generators emerge from a caustic. To supplement our motivation, we
include an appendix deriving a corresponding coarse-grained generalized second
law for 1+1 holographic CFTs perturbatively coupled to dilaton gravity.


title:
Abundance trend with condensation temperature for stars with different
  Galactic birth places

abstract:
  During the past decade, several studies reported a correlation between
chemical abundances of stars and condensation temperature (also known as Tc
trend). However, the real astrophysical nature of this correlation is still
debated. The main goal of this work is to explore the possible dependence of
the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality
spectra of about 40 stars observed with the HARPS and UVES spectrographs to
derive precise stellar parameters, chemical abundances, and stellar ages. A
differential line-by-line analysis was applied to achieve the highest possible
precision in the chemical abundances. We confirm previous results that [X/Fe]
abundance ratios depend on stellar age and that for a given age, some elements
also show a dependence on Rmean. When using the whole sample of stars, we
observe a weak hint that the Tc trend depends on Rmean. The observed dependence
is very complex and disappears when only stars with similar ages are
considered. To conclude on the possible dependence of the Tc trend on the
formation place of stars, a larger sample of stars with very similar
atmospheric parameters and stellar ages observed at different Galactocentric
distances is needed


title: Fano congruences of index $3$ and alternating $3$-forms

abstract:
  We study congruences of lines $X_\omega$ defined by a sufficiently general
choice of an alternating 3-form $\omega$ in $n+1$ dimensions, as Fano manifolds
of index $3$ and dimension $n-1$. These congruences include the
$\mathrm{G}_2$-variety for $n=6$ and the variety of reductions of projected
$\mathbb{P}^2 \times \mathbb{P}^2$ for $n=7$.
  We compute the degree of $X_\omega$ as the $n$-th Fine number and study the
Hilbert scheme of these congruences proving that the choice of $\omega$
bijectively corresponds to $X_\omega$ except when $n=5$. The fundamental locus
of the congruence is also studied together with its singular locus: these
varieties include the Coble cubic for $n=8$ and the Peskine variety for $n=9$.
  The residual congruence $Y$ of $X_\omega$ with respect to a general linear
congruence containing $X_\omega$ is analysed in terms of the quadrics
containing the linear span of $X_\omega$. We prove that $Y$ is Cohen-Macaulay
but non-Gorenstein in codimension $4$. We also examine the fundamental locus
$G$ of $Y$ of which we determine the singularities and the irreducible
components.


title:
How to Measure Black Hole's Mass, Spin and Direction of Spin Axis in
  Kerr Lens Effect 1: test case with simple source emission near BH

abstract:
  We propose a theoretical principle to measure the mass, spin and direction of
spin axis of Kerr black holes (BHs) through observing 2 quantities of the
spinning strong gravitational lens effect of BHs. Those observable quantities
are generated by 2 light rays emitted at the same time by a source near the BH:
the primary and secondary rays that reach a distant observer, respectively, the
earliest and secondary temporally. The time delay between detection times and
the ratio of observed specific fluxes of those rays are the observable
quantities. Rigorously, our proposal is applicable to a single burst-like
(short duration) isotropic emission by the source. An extension of our
principle to cases of complicated emissions may be constructed by summing up
appropriately the result of this paper, which will be treated in future works.


title: Time-dependent density-functional description of nuclear dynamics

abstract:
  We present the basic concepts and recent developments in the time-dependent
density functional theory (TDDFT) for describing nuclear dynamics at low
energy. The symmetry breaking is inherent in nuclear energy density functionals
(EDFs), which provides a practical description of important correlations at the
ground state. Properties of elementary modes of excitation are strongly
influenced by the symmetry breaking and can be studied with TDDFT. In
particular, a number of recent developments in the linear response calculation
have demonstrated their usefulness in description of collective modes of
excitation in nuclei. Unrestricted real-time calculations have also become
available in recent years, with new developments for quantitative description
of nuclear collision phenomena. There are, however, limitations in the
real-time approach; for instance, it cannot describe the many-body quantum
tunneling. Thus, we treat the quantum fluctuations associated with slow
collective motions assuming that time evolution of densities are determined by
a few collective coordinates and momenta. The concept of collective submanifold
is introduced in the phase space associated with the TDDFT and used to quantize
the collective dynamics. Selected applications are presented to demonstrate the
usefulness and quality of the new approaches. Finally, conceptual differences
between nuclear and electronic TDDFT are discussed, with some recent
applications to studies of electron dynamics in the linear response and under a
strong laser field.


title:
Improved Space efficient linear time algorithms for BFS, DFS and
  applications

abstract:
  Recent work by Elmasry et al. (STACS 2015) and Asano et al. (ISAAC 2014),
reconsidered classical fundamental graph algorithms focusing on improving the
space complexity. We continue this line of work focusing on space. Our first
result is a simple data structure that can maintain any subset $S$ of a
universe of $n$ elements using $n+o(n)$ bits and support in constant time,
apart from the standard insert, delete and membership queries, the operation
{\it findany} that finds and returns any element of the set (or outputs that
the set is empty). Using this we give a BFS implementation that takes $O(m+n)$
time using at most $2n+o(n)$ bits. Later, we further improve the space
requirement of BFS to at most $1.585n + o(n)$ bits. We demonstrate the use of
our data structure by developing another data structure using it that can
represent a sequence of $n$ non-negative integers $x_1, x_2, \ldots x_n$ using
at most $\sum_{i=1}^n x_i + 2n + o(\sum_{i=1}^n x_i+n)$ bits and, in constant
time, determine whether the $i$-th element is $0$ or decrement it otherwise. We
also discuss an algorithm for finding a minimum weight spanning tree of a
weighted undirected graph using at most $n+o(n)$ bits. We also provide an
implementation for DFS that takes $O(m+n)$ time and $O(n \lg(m/n))$ bits. Using
this DFS algorithm and other careful implementations, we can test
biconnectivity, 2-edge connectivity, and determine cut vertices, bridges etc
among others, essentially within the same time and space bounds required for
DFS. These improve the space required for earlier implementations from $\Omega
(n\lg n)$ bits.


title:
Characterization of the Community Structure of Large Scale Functional
  Brain Networks During Ketamine-Medetomidine Anesthetic Induction

abstract:
  One of the central questions in neuroscience is to understand the way
communication is organized in the brain, trying to comprehend how cognitive
capacities or physiological states of the organism are potentially related to
brain activities involving interactions of several brain areas. One important
characteristic of the functional brain networks is that they are modularly
structured, being this modular architecture regarded to account for a series of
properties and functional dynamics. In the neurobiological context, communities
may indicate brain regions that are involved in one same activity, representing
neural segregated processes. Several studies have demonstrated the modular
character of organization of brain activities. However, empirical evidences
regarding to its dynamics and relation to different levels of consciousness
have not been reported yet. Within this context, this research sought to
characterize the community structure of functional brain networks during an
anesthetic induction process. The experiment was based on intra-cranial
recordings of neural activities of an old world macaque of the species Macaca
fuscata during a Ketamine-Medetomidine anesthetic induction process. Networks
were serially estimated in time intervals of five seconds. Changes were
observed within about one and a half minutes after the administration of the
anesthetics, revealing the occurrence of a transition on the community
structure. The awake state was characterized by the presence of large clusters
involving frontal and parietal regions, while the anesthetized state by the
presence of communities in the primary visual and motor cortices, being the
areas of the secondary associative cortex most affected. The results report the
influence of general anesthesia on the structure of functional clusters,
contributing for understanding some new aspects of neural correlates of
consciousness.


title:
Demand Engineering: IP Network Optimisation Through Intelligent Demand
  Placement

abstract:
  Traffic engineering has been used in IP and MPLS networks for a number of
years as a tool for making more efficient use of capacity by explicitly routing
traffic demands where there is available network capacity that would otherwise
be unused. Deployment of traffic engineering imposes an additional layer of
complexity to network design and operations, however, which has constrained its
adoption for capacity optimisation. The rise of Software Defined Networks has
renewed interest in the use of traffic engineering approaches leveraging
centralised network controllers for capacity optimisation. We argue that future
networks can realise the network optimisation benefits of traffic engineering
without incurring additional network complexity through closer coupling between
the network and the applications and services using the network. This can be
achieved through leveraging a network- and traffic-aware controller to directly
influence where applications and services site or locate service instances,
i.e. which implicitly impacts the paths that the applications or services
traffic demands take through the network. We call this technique Demand
Engineering. Demand Engineering has the additional benefit of providing an
admission control capability, i.e. which can provide an assurance that network
SLAs can be met. In this paper we describe the concept of Demand Engineering,
give examples of its use and present simulation results indicating its
potential benefits. We also compare demand engineering to traffic engineering.


title: Personality Traits and Echo Chambers on Facebook

abstract:
  In online social networks, users tend to select information that adhere to
their system of beliefs and to form polarized groups of like minded people.
Polarization as well as its effects on online social interactions have been
extensively investigated. Still, the relation between group formation and
personality traits remains unclear. A better understanding of the cognitive and
psychological determinants of online social dynamics might help to design more
efficient communication strategies and to challenge the digital misinformation
threat. In this work, we focus on users commenting posts published by US
Facebook pages supporting scientific and conspiracy-like narratives, and we
classify the personality traits of those users according to their online
behavior. We show that different and conflicting communities are populated by
users showing similar psychological profiles, and that the dominant personality
model is the same in both scientific and conspiracy echo chambers. Moreover, we
observe that the permanence within echo chambers slightly shapes users'
psychological profiles. Our results suggest that the presence of specific
personality traits in individuals lead to their considerable involvement in
supporting narratives inside virtual echo chambers.


title:
Bolt-on Differential Privacy for Scalable Stochastic Gradient
  Descent-based Analytics

abstract:
  While significant progress has been made separately on analytics systems for
scalable stochastic gradient descent (SGD) and private SGD, none of the major
scalable analytics frameworks have incorporated differentially private SGD.
There are two inter-related issues for this disconnect between research and
practice: (1) low model accuracy due to added noise to guarantee privacy, and
(2) high development and runtime overhead of the private algorithms. This paper
takes a first step to remedy this disconnect and proposes a private SGD
algorithm to address \emph{both} issues in an integrated manner. In contrast to
the white-box approach adopted by previous work, we revisit and use the
classical technique of {\em output perturbation} to devise a novel "bolt-on"
approach to private SGD. While our approach trivially addresses (2), it makes
(1) even more challenging. We address this challenge by providing a novel
analysis of the $L_2$-sensitivity of SGD, which allows, under the same privacy
guarantees, better convergence of SGD when only a constant number of passes can
be made over the data. We integrate our algorithm, as well as other
state-of-the-art differentially private SGD, into Bismarck, a popular scalable
SGD-based analytics system on top of an RDBMS. Extensive experiments show that
our algorithm can be easily integrated, incurs virtually no overhead, scales
well, and most importantly, yields substantially better (up to 4X) test
accuracy than the state-of-the-art algorithms on many real datasets.


title:
Weak-strong uniqueness for compressible Navier-Stokes system with slip
  boundary conditions on time dependent domains

abstract:
  We consider the compressible Navier-Stokes system on time-dependent domains
with prescribed motion of the boundary, supplemented with slip boundary
conditions for the velocity. We derive the relative entropy inequality in the
spirit of Feireisl et al. for the system on moving domain and use it to prove
the weak-strong uniqueness property.


title: Exact solutions for the biadjoint scalar field

abstract:
  Biadjoint scalar theories are novel field theories that arise in the study of
non-abelian gauge and gravity amplitudes. In this short paper, we present exact
nonperturbative solutions of the field equations, and compare their properties
with monopole-like solutions in non-abelian gauge theory. Our results may pave
the way for nonperturbative studies of the double copy.


title:
Effects on a Landau-type system for a neutral particle with no permanent
  electric dipole moment subject to the Kratzer potential in a rotating frame

abstract:
  The behaviour of a neutral particle (atom, molecule) with an induced electric
dipole moment in a region with a uniform effective magnetic field under the
influence of the Kratzer potential [A. Kratzer, Z. Phys. 3, 289 (1920)] and
rotating effects is analysed. It is shown that the degeneracy of the
Landau-type levels is broken and the angular frequency of the system acquires a
new contribution that stems from the rotation effects. Moreover, in the search
for bound states solutions, then, it is shown that the possible values of this
angular frequency of the system are determined by the quantum numbers
associated with the radial modes and the angular momentum, the angular velocity
of the rotating frame and by the parameters associated with the Kratzer
potential.


title: Adiabatic fission barriers in superheavy nuclei

abstract:
  Using the microscopic-macroscopic model based on the deformed Woods-Saxon
single-particle potential and the Yukawa-plus-exponential macroscopic energy we
calculated static fission barriers $B_{f}$ for 1305 heavy and superheavy nuclei
$98\leq Z \leq 126$, including even - even, odd - even, even - odd and odd -
odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces
were calculated by a minimization over configurations with one blocked neutron
or/and proton on a level from the 10-th below to the 10-th above the Fermi
level. The parameters of the model that have been fixed previously by a fit to
masses of even-even heavy nuclei were kept unchanged. A search for saddle
points has been performed by the "Imaginary Water Flow" method on a basic
five-dimensional deformation grid, including triaxiality. Two auxiliary grids
were used for checking the effects of the mass asymmetry and hexadecapole
non-axiallity. The ground states were found by energy minimization over
configurations and deformations. We find that the non-axiallity significantly
changes first and second fission barrier in many nuclei. The effect of the mass
- asymmetry, known to lower the second, very deformed barriers in actinides, in
the heaviest nuclei appears at the less deformed saddles in more than 100
nuclei. It happens for those saddles in which the triaxiallity does not play
any role, what suggests a decoupling between effects of the mass-asymmetry and
triaxiality. We studied also the influence of the pairing interaction strength
on the staggering of $B_f$ for odd- and even-particle numbers. Finally, we
provide a comparison of our results with other theoretical fission barrier
evaluations and with available experimental estimates.


title:
The generalized Kondo lattice model and its spin-polaron implementation
  for cuprates by projection method

abstract:
  It is shown that the spin-fermion model found to be an effective low-energy
implementation of the three-band Emery model after Wannier transformation of
$p_x$- and $p_y$-orbitals in the oxygen ions subsystem is reduced to the
generalized Kondo lattice model. Its essential feature is the presence of
spin-correlated hoppings of the current carriers between distant cells.
Numerical calculations of the spin-polaron spectrum demonstrate the important
role of the distant hoppings.


title: Quantum Circuit Refrigerator

abstract:
  Quantum technology promises revolutionizing applications in information
processing, communications, sensing, and modelling. However, efficient
on-demand cooling of the functional quantum degrees of freedom remains a major
challenge in many solid-state implementations, such as superconducting
circuits. Here, we demonstrate direct cooling of a superconducting resonator
mode using voltage-controllable quantum tunneling of electrons in a nanoscale
refrigerator. This result is revealed by a decreased electron temperature at a
resonator-coupled probe resistor, even when the electrons in the refrigerator
itself are at an elevated temperature. Our conclusions are verified by control
experiments and by a good quantitative agreement between a detailed theoretical
model and the direct experimental observations in a broad range of operation
voltages and phonon bath temperatures. In the future, the introduced
refrigerator can be integrated with different quantum electric devices,
potentially enhancing their performance. For the superconducting quantum
computer, for example, it may provide an efficient way of initializing the
quantum bits.


title: Spying on photons with photons: quantum interference and information

abstract:
  The quest to have both which-path knowledge and interference fringes in a
double-slit experiment dates back to the inception of quantum mechanics (QM)
and to the famous Einstein-Bohr debates. In this paper we propose and discuss
an experiment able to spy on one photon's path with another photon. We modify
the quantum state inside the interferometer as opposed to the traditional
physical modification of the "wave-like" or "particle-like" experimental setup.
We are able to show that it is the ability to harvest or not which-path
information that finally limits the visibility of the interference pattern and
not the "wave-like" or "particle-like" experimental setups. Remarkably, a full
"particle-like" experimental setup is able to show interference fringes with
100 % visibility if the quantum state is carefully engineered.


title: Pressure dependent friction on granular slopes close to avalanche

abstract:
  We investigate the sliding of objects on an inclined granular surface close
to the avalanche threshold. Our experiments show that the stability is driven
by the surface deformations. Heavy objects generate footprint-like deformations
which stabilize the objects on the slopes. Light objects do not disturb the
sandy surfaces and are also stable. For intermediate weights, the deformations
of the surface destabilize the objects and generate sliding. A characteristic
pressure for which the solid friction is minimal is evidenced. Applications to
the locomotion of devices and animals on sandy slopes as a function of their
mass are proposed.


title:
Measurements of the S-wave fraction in $B^{0}\rightarrow
  K^{+}\pi^{-}\mu^{+}\mu^{-}$ decays and the $B^{0}\rightarrow
  K^{\ast}(892)^{0}\mu^{+}\mu^{-}$ differential branching fraction

abstract:
  A measurement of the differential branching fraction of the decay
${B^{0}\rightarrow K^{\ast}(892)^{0}\mu^{+}\mu^{-}}$ is presented together with
a determination of the S-wave fraction of the $K^+\pi^-$ system in the decay
$B^{0}\rightarrow K^{+}\pi^{-}\mu^{+}\mu^{-}$. The analysis is based on
$pp$-collision data corresponding to an integrated luminosity of 3\,fb$^{-1}$
collected with the LHCb experiment. The measurements are made in bins of the
invariant mass squared of the dimuon system, $q^2$. Precise theoretical
predictions for the differential branching fraction of $B^{0}\rightarrow
K^{\ast}(892)^{0}\mu^{+}\mu^{-}$ decays are available for the $q^2$ region
$1.1<q^2<6.0\,{\rm GeV}^2/c^4$. In this $q^2$ region, for the $K^+\pi^-$
invariant mass range $796 < m_{K\pi} < 996\,{\rm MeV}/c^2$, the S-wave fraction
of the $K^+\pi^-$ system in $B^{0}\rightarrow K^{+}\pi^{-}\mu^{+}\mu^{-}$
decays is found to be \begin{equation*}
  F_{\rm S} = 0.101\pm0.017({\rm stat})\pm0.009 ({\rm syst}), \end{equation*}
and the differential branching fraction of $B^{0}\rightarrow
K^{\ast}(892)^{0}\mu^{+}\mu^{-}$ decays is determined to be \begin{equation*}
  {\rm d}\mathcal{B}/{\rm d} q^2 = (0.342_{\,-0.017}^{\,+0.017}({\rm
stat})\pm{0.009}({\rm syst})\pm0.023({\rm norm}))\times 10^{-7}c^{4}/{\rm
GeV}^{2}. \end{equation*} The differential branching fraction measurements
presented are the most precise to date and are found to be in agreement with
Standard Model predictions.


title: Double-slit experiment in momentum space

abstract:
  Young's classic double-slit experiment demonstrates the reality of
interference when waves and particles travel simultaneously along two different
spatial paths. Here, we propose a double-slit experiment in momentum space,
realized in the free-space elastic scattering of vortex electrons. We show that
this process proceeds along two paths in momentum space, which are well
localized and well separated from each other. For such vortex beams, the
(plane-wave) amplitudes along the two paths acquire adjustable phase shifts and
produce interference fringes in the final angular distribution. We argue that
this experiment can be realized with the present day technology. We show that
it gives experimental access to the Coulomb phase, a quantity which plays an
important role in all charged particle scattering but which usual scattering
experiments are insensitive to.


title: Steady streamwise transpiration control in turbulent pipe flow

abstract:
  A study of the the main features of low- and high amplitude steady streamwise
wall transpiration applied to pipe flow is presented. The effect of the two
transpiration parameters, amplitude and wavenumber, on the flow have been
investigated by means of direct numerical simulation at a moderate turbulent
Reynolds number. The behaviour of the three identified mechanisms that act in
the flow: modification of Reynolds shear stress, steady streaming and
generation of non-zero mean streamwise gradients, have been linked to the
transpiration parameters. The observed trends have permitted the identification
of wall transpiration configurations able to reduce or increase the overall
flow rate in -36.1% and 19.3% respectively. A resolvent analysis has been
carried out to obtain a description of the reorganization of the flow
structures induced by the transpiration.


title: Direct detection of relic active and sterile neutrinos

abstract:
  Both active and sterile sub-eV neutrinos can form the cosmic neutrino
background in the early Universe. We consider the beta-decaying (e.g., $^3$H)
and EC-decaying (e.g., $^{163}$Ho) nuclei as the promising targets to capture
relic neutrinos in the laboratory. We calculate the capture rates of relic
electron neutrinos and antineutrinos against the corresponding beta decay or
electron capture (EC) decay backgrounds in the (3+$N_{\rm s}$) flavor mixing
scheme, and discuss the future prospect in terms of the PTOLEMY project. We
stress that such direct measurements of hot DM might not be hopeless in the
long term.


title:
A reduced-order model of three-dimensional unsteady flow in a cavity
  based on the resolvent operator

abstract:
  A novel reduced-order model for nonlinear flows is presented. The model
arises from a resolvent decomposition in which the nonlinear advection terms of
the Navier-Stokes equation are considered as the input to a linear system in
Fourier space. Results show that Taylor-G\"ortler-like vortices can be
represented from a low-order resolvent decomposition of a nonlinear lid-driven
cavity flow. The present approach provides an approximation of the fluctuating
velocity given the time-mean and the time history of a single velocity probe.


title:
Coupling a single electron spin to a microwave resonator: Controlling
  transverse and longitudinal couplings

abstract:
  Microwave-frequency superconducting resonators are ideally suited to perform
dispersive qubit readout, to mediate two-qubit gates, and to shuttle states
between distant quantum systems. A prerequisite for these applications is a
strong qubit-resonator coupling. Strong coupling between an electron-spin qubit
and a microwave resonator can be achieved by correlating spin- and orbital
degrees of freedom. This correlation can be achieved through the Zeeman
coupling of a single electron in a double quantum dot to a spatially
inhomogeneous magnetic field generated by a nearby nanomagnet. In this paper,
we consider such a device and estimate spin-resonator couplings of order ~ 1
MHz with realistic parameters. Further, through realistic simulations, we show
that precise placement of the double dot relative to the nanomagnet allows to
select between a purely longitudinal coupling (commuting with the bare spin
Hamiltonian) and a purely transverse (spin non-conserving) coupling.
Additionally, we suggest methods to mitigate dephasing and relaxation channels
that are introduced in this coupling scheme. This analysis gives a clear route
toward the realization of coherent state transfer between a microwave resonator
and a single electron spin in a GaAs double quantum dot with a fidelity above
90%. Improved dynamical decoupling sequences, low-noise environments, and
longer-lived microwave cavity modes may lead to substantially higher fidelities
in the near future.


title: The number of real eigenvectors of a real polynomial

abstract:
  I investigate on the number t of real eigenvectors of a real symmetric
tensor. In particular, given a homogeneous polynomial f of degree d in 3
variables, i prove that t is greater or equal than 2c+1, if d is odd and t is
greater or equal than max(3,2c+1), is d is even, where c is the number of ovals
of the locus of zeros of f; for binary forms, i prove that t is greater or
equal than the number of real roots of f. Moreover, the above inequalities are
the best possible for binary forms of any degree and for ternary cubic and
quartic forms.


title: Comment on "Quantum Raychaudhuri equation"

abstract:
  We address the validity of the formalism and results presented in [ S. Das,
Phys. Rev. {\bf D89} 084068 (2014)] with regard to quantum Raychaudhuri
equation. The author obtained the so called quantum Raychaudhuri equation by
replacing classical geodesics with quantal trajectories arising from Bhommian
mechanics. The resulting modified equation was used to draw some conclusions
about the inevitability of focussing and the formation of conjugate points and
therefore singularity. We show that the whole procedure is full of problematic
points, on both physical relevancy and mathematical correctness. In particular,
we illustrate the problems associated with the technical derivation of the so
called quantum Raychaudhuri equation, as well as its invalid physical
implications.


title: Estimation of unsteady aerodynamic forces using pointwise velocity data

abstract:
  A novel method to estimate unsteady aerodynamic force coefficients from
pointwise velocity measurements is presented. The methodology is based on a
resolvent-based reduced-order model which requires the mean flow to obtain
physical flow structures and pointwise measurement to calibrate their
amplitudes. A computationally-affordable time-stepping methodology to obtain
resolvent modes in non-trivial flow domains is introduced and compared to
previous existing matrix-free and matrix-forming strategies. The technique is
applied to the unsteady flow around an inclined square cylinder at low Reynolds
number. The potential of the methodology is demonstrated through good agreement
between the fluctuating pressure distribution on the cylinder and the temporal
evolution of the unsteady lift and drag coefficients predicted by the model and
those computed by direct numerical simulation.


title: Direct and inverse solver for the 3D optoacoustic Volterra equation

abstract:
  The direct problem of optoacoustic signal generation in biological media
consists of solving the inhomogeneous optoacoustic wave equation for an initial
acoustic stress profile. In contrast, the mathematically challenging inverse
problem requires the reconstruction of the initial stress profile from a proper
set of observed signals. In this article, we consider the particular case of a
Gaussian transverse irradiation source profile in the paraxial approximation of
the wave equation, for which the direct problem along the beam axis can be cast
into a linear Volterra integral equation of the second kind. This integral
equation can be used in two ways: as a forward solver to predict optoacoustic
signals in terms of the direct problem, and as an inverse solver for which we
here devise highly efficient numerical schemes used for the reconstruction of
initial pressure profiles from observed signals, constituting a methodical
progress of computational aspects of optoacoustics. In this regard, we explore
the validity as well as the limits of the inversion scheme via numerical
experiments, with parameters geared towards actual optoacoustic problem
instances. The considered inversion input consists of synthetic data, obtained
by means of forward solvers based on the Volterra integral, and, more
generally, the optoacoustic Poisson integral. Regarding the latter, we
numerically invert signals that correspond to different detector-to-sample
distances and assess the convergence to the true initial stress profiles upon
approaching the far-field. Finally, we also address the effect of noise on the
quality of the reconstructed pressure profiles.


title: New Hamiltonian expansions adapted to the Trojan problem

abstract:
  A number of studies, referring to the observed Trojan asteroids of various
planets in our Solar System, or to hypothetical Trojan bodies in extrasolar
planetary systems, have emphasized the importance of so-called secondary
resonances in the problem of the long term stability of Trojan motions. Such
resonances describe commensurabilities between the fast, synodic, and secular
frequency of the Trojan body, and, possibly, additional slow frequencies
produced by more than one perturbing bodies. The presence of secondary
resonances sculpts the dynamical structure of the phase space. Hence,
identifying their location is a relevant task for theoretical studies. In the
present paper we combine the methods introduced in two recent papers (Paez &
Efthymiopoulos, 2015, Paez & Locatelli, 2015) in order to analytically predict
the location of secondary resonances in the Trojan problem (SEE FILE FOR
COMPLETE ABSTRACT)


title:
Systems of semilinear parabolic variational inequalities with
  time-dependent convex obstacles

abstract:
  We consider a system of seminlinear parabolic variational inequalities with
time-dependent convex obstacles. We prove the existence and uniqueness of its
solution. We also provide a stochastic representation of the solution and show
that it can be approximated by the penalization method. Our proofs are based
upon probabilistic methods from the theory of Markov processes and the theory
of backward stochastic differential equations.


title: Jiangmen Underground Neutrino Observatory: Status and Prospectives

abstract:
  The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid
scintillator (LS) detector, which is planed to determine the neutrino mass
hierarchy and measure the oscillation parameters at the sub-percent level using
reactor antineutrino oscillations. As a multipurpose neutrino experiment, JUNO
is also capable of measuring supernova burst neutrinos, the diffuse supernova
neutrino background, geo-neutrinos, solar neutrinos and atmospheric neutrinos.
After a brief introduction to the physics motivation, we discuss the status of
the JUNO project, including the design of the detector systems. Finally the
latest civil progress and future prospectives are also highlighted.


title: Matter and gravitons in the gravitational collapse

abstract:
  We consider the effects of gravitons in the collapse of baryonic matter that
forms a black hole. We first note that the effective number of (soft off-shell)
gravitons that account for the (negative) Newtonian potential energy generated
by the baryons is conserved and always in agreement with Bekenstein's area law
of black holes. Moreover, their (positive) interaction energy reproduces the
expected post-Newtonian correction and becomes of the order of the total ADM
mass of the system when the size of the collapsing object approaches its
gravitational radius. This result supports a scenario in which the
gravitational collapse of regular baryonic matter produces a corpuscular black
hole without central singularity, in which both gravitons and baryons are
marginally bound and form a Bose-Einstein condensate at the critical point. The
Hawking emission of baryons and gravitons is then described by the quantum
depletion of the condensate and we show the two energy fluxes are comparable,
albeit negligibly small on astrophysical scales.


title: A note on Willmore minimizing Klein bottles in Euclidean space

abstract:
  We show that Lawson's bipolar surface $\tilde\tau_{3,1}$ is after
stereographic projection the unique minimizer among immersed Klein bottles in
its conformal class. We conjecture that it actually is the unique minimizer
among immersed Klein bottles into $\mathbb{R}^n$, $n\geq 4$, whose existence
the authors and P. Breuning proved in a previous paper.


title:
Efficient data streaming multiway aggregation through concurrent
  algorithmic designs and new abstract data types

abstract:
  Data streaming relies on continuous queries to process unbounded streams of
data in a real-time fashion. It is commonly demanding in computation capacity,
given that the relevant applications involve very large volumes of data. Data
structures act as articulation points and maintain the state of data streaming
operators, potentially supporting high parallelism and balancing the work
between them. Prompted by this fact, in this work we study and analyze
parallelization needs of these articulation points, focusing on the problem of
streaming multiway aggregation, where large data volumes are received from
multiple input streams. The analysis of the parallelization needs, as well as
of the use and limitations of existing aggregate designs and their data
structures, leads us to identify needs for proper shared objects that can
achieve low-latency and high throughput multiway aggregation. We present the
requirements of such objects as abstract data types and we provide efficient
lock-free linearizable algorithmic implementations of them, along with new
multiway aggregate algorithmic designs that leverage them, supporting both
deterministic order-sensitive and order-insensitive aggregate functions.
Furthermore, we point out future directions that open through these
contributions. The paper includes an extensive experimental study, based on a
variety of aggregation continuous queries on two large datasets extracted from
SoundCloud, a music social network, and from a Smart Grid network. In all the
experiments, the proposed data structures and the enhanced aggregate operators
improved the processing performance significantly, up to one order of
magnitude, in terms of both throughput and latency, over the commonly-used
techniques based on queues.


title: A Note on the Existence of the Multivariate Gamma Distribution

abstract:
  The p-variate gamma distribution in the sense of Krishnamoorthy and
Parthasarathy exists for all positive integer degrees of freedom d and at least
for all real values d > p-2, p > 1. For special structures of the "associated"
covariance matrix it also exists for all positive d. In this paper a relation
between central and non-central multivariate gamma distributions is shown,
which implies the existence of the p-variate gamma distribution at least for
all non-integer d greater than the integer part of (p-1)/2 without any
additional assumptions for the associated covariance matrix.


title:
Realization of anomalous multiferroicity in free-standing graphene with
  magnetic adatoms

abstract:
  It is generally believed that free-standing graphene does not demonstrate any
ferroic properties. In the present work we revise this statement and show that
single graphene sheet with a pair of magnetic adatoms can be driven into
ferroelectric (FE) and multiferroic (MF) phases by tuning the Dirac cones
slope. The transition into the FE phase occurs gradually, but an anomalous MF
phase appears abruptly by means of a Quantum Phase Transition. Our findings
suggest that such features should exist in graphene recently investigated by
Scanning Tunneling Microscopy (Science 352, 437 (2016)).