title: A note on Serrin's overdetermined problem

abstract:
  We consider the solution of the torsion problem $-\Delta u=1$ in $\Omega$ and
$u=0$ on $\partial \Omega$. Serrin's celebrated symmetry theorem states that,
if the normal derivative $u_\nu$ is constant on $\partial \Omega$, then
$\Omega$ must be a ball. In a recent paper, it has been conjectured that
Serrin's theorem may be obtained {\it by stability} in the following way:
first, for the solution $u$ of the torsion problem prove the estimate $$
r_e-r_i\leq C_t\,\Bigl(\max_{\Gamma_t} u-\min_{\Gamma_t} u\Bigr) $$ for some
constant $C_t$ depending on $t$, where $r_e$ and $r_i$ are the radii of an
annulus containing $\partial\Omega$ and $\Gamma_t$ is a surface parallel to
$\partial\Omega$ at distance $t$ and sufficiently close to $\partial\Omega$;
secondly, if in addition $u_\nu$ is constant on $\partial\Omega$, show that $$
\max_{\Gamma_t} u-\min_{\Gamma_t} u=o(C_t)\ \mbox{as} \ t\to 0^+. $$ In this
paper, we analyse a simple case study and show that the scheme is successful if
the admissible domains $\Omega$ are ellipses.


title: Near-infrared spectropolarimetry of a delta-spot

abstract:
  Sunspots harboring umbrae of both magnetic polarities within a common
penumbra (delta-spots) are often but not always related to flares. We present
first near-infrared (NIR) observations (Fe I 1078.3 nm and Si I 1078.6 nm
spectra) obtained with the Tenerife Infrared Polarimeter (TIP) at the Vacuum
Tower Telescope (VTT) in Tenerife on 2012 June 17, which afford accurate and
sensitive diagnostics to scrutinize the complex fields along the magnetic
neutral line of a delta-spot within active region NOAA 11504. We examine the
vector magnetic field, line-of-sight (LOS) velocities, and horizontal proper
motions of this rather inactive delta-spot. We find a smooth transition of the
magnetic vector field from the main umbra to that of opposite polarity
(delta-umbra), but a discontinuity of the horizontal magnetic field at some
distance from the delta-umbra on the polarity inversion line. The magnetic
field decreases faster with height by a factor of two above the delta-umbra.
The latter is surrounded by its own Evershed flow. The Evershed flow coming
from the main umbra ends at a line dividing the spot into two parts. This line
is marked by the occurrence of central emission in the Ca II 854.2 nm line.
Along this line, high chromospheric LOS-velocities of both signs appear. We
detect a shear flow within the horizontal flux transport velocities parallel to
the dividing line.


title: A Multiple Network Approach to Corporate Governance

abstract:
  In this work, we consider Corporate Governance (CG) ties among companies from
a multiple network perspective. Such a structure naturally arises from the
close interrelation between the Shareholding Network (SH) and the Board of
Directors network (BD). In order to capture the simultaneous effects of both
networks on CG, we propose to model the CG multiple network structure via
tensor analysis. In particular, we consider the TOPHITS model, based on the
PARAFAC tensor decomposition, to show that tensor techniques can be
successfully applied in this context. By providing some empirical results from
the Italian financial market in the univariate case, we then show that a
tensor--based multiple network approach can reveal important information.


title:
HESS J1640-465 - an exceptionally luminous TeV gamma-ray supernova
  remnant

abstract:
  The results of follow-up observations of the TeV gamma-ray source HESSJ
1640-465 from 2004 to 2011 with the High Energy Stereoscopic System (H.E.S.S.)
are reported in this work. The spectrum is well described by an exponential
cut-off power law with photon index Gamma=2.11 +/- 0.09_stat +/- 0.10_sys, and
a cut-off energy of E_c = (6.0 +2.0 -1.2) TeV. The TeV emission is
significantly extended and overlaps with the north-western part of the shell of
the SNR G338.3-0.0. The new H.E.S.S. results, a re-analysis of archival
XMM-Newton data, and multi-wavelength observations suggest that a significant
part of the gamma-ray emission from HESS J1640-465 originates in the SNR shell.
In a hadronic scenario, as suggested by the smooth connection of the GeV and
TeV spectra, the product of total proton energy and mean target density could
be as high as W_p n_H ~ 4 x 10^52 (d/10kpc)^2 erg cm^-3.


title: Comapactness Conditions in Universal Algebraic Geometry

abstract:
  In this article, the properties of being equational noetherian, $q_{\omega}$
and $u_{\omega}$-compactness, and equational Artinian are studied from the
perspective of the Zariski topology. The equational conditions on the relative
free algebras of arbitrary varieties are also investigated.


title: Imaginary-time theory for triple-alpha reaction rate

abstract:
  Using imaginary-time theory, it is shown that the triple-alpha reaction rate
can be reliably calculated without the need to solve scattering problems
involving three charged particles. The calculated reaction rate is found to
agree well with the empirical NACRE rate, which is widely adopted in stellar
evolution calculations. The reason for this is explained using $R$-matrix
theory. Extremely slow convergence is found to occur when a coupled-channel
expansion is introduced, which helps to explain the very different reaction
rates obtained using different theoretical approaches.


title:
Topologically protected conduction state at carbon foam surfaces:An
  ab-initio study

abstract:
  We report results of \textit{ab initio} electronic structure and quantum
conductance calculations indicating the emergence of conduction at the surface
of semiconducting carbon foams. Occurrence of new conduction states is
intimately linked to the topology of the surface and not limited to foams of
elemental carbon. Our interpretation based on rehybridization theory indicates
that conduction in the foam derives from first- and second-neighbor
interactions between $p_\|$ orbitals lying in the surface plane, which are
related to $p_\perp$ orbitals of graphene. The topologically protected
conducting state occurs on bare and hydrogen-terminated foam surfaces and is
thus unrelated to dangling bonds. Our results for carbon foam indicate that the
conductance behavior may be further significantly modified by surface
patterning.


title: Low Momentum Particle Detector for the NA61 Experiment at CERN

abstract:
  The NA61 Experiment at CERN SPS is a large acceptance hadron spectrometer,
aimed to studying of hadron-hadron, hadron-nucleus, and nucleus-nucleus
interactions in a fixed target environment. The present paper discusses the
construction and performance of the Low Momentum Particle Detector (LMPD), a
small time projection chamber unit which has been added to the NA61 setup in
2012. The LMPD considerably extends the detector acceptance towards the
backward region, surrounding the target in hadron-nucleus interactions. The
LMPD features simultaneous range and ionization measurements, which allows for
particle identification and momentum measurement in the 0.1-0.25 GeV/c momentum
range for protons. The possibility of Z=1 particle identification in this range
is directly demonstrated.


title: Reduction in mechanical systems with symmetry

abstract:
  The first part of the article is, in fact, the classical Routh method
delivered in the language of contemporary theory of Lagrangian systems. But the
Routh method deals only with concrete equations and, therefore, can be applied
only in the case when the configuration spaces of the initial and the reduced
systems are open submanifolds in Euclidean spaces. The global approach gives a
possibility to find the structure of these manifolds in the general case and
also to reveal some properties of the reduced system, first of all, the
existence for this system of a global Lagrange function. We use the notion of a
mechanical system introduced by S. Smale. The described method is applied to
the global reduction in the problem of the motion of a rigid body having a
fixed point in the potential force field with an axial symmetry. We present the
complete proof of the theorem formulated by G.V. Kolosov on the equivalence of
the reduced system in this case to the problem of the motion of a material
point over an ellipsoid and also some corollaries of this theorem based on the
results of L.A. Lyusternik and L.G. Shnirelman.


title: On the 2D zero modes' algebra of the SU(n) WZNW model

abstract:
  A quantum group covariant extension of the chiral parts of the
Wess-Zumino-Novikov-Witten model on a compact Lie group G gives rise to two
matrix algebras with non-commutative entries. These are generated by "chiral
zero modes" which combine in the 2D model into "Q-operators" which encode
information about the internal symmetry and the fusion ring. We review earlier
results about the SU(n) WZNW Q-algebra and its Fock representation for n=2 and
display the first steps towards their generalization to higher n.


abstract:
  The CAMbridge Emission Line Surveyor (CAMELS) is a pathfinder program to
demonstrate on-chip spectrometry at millimetre wavelengths. CAMELS will observe
at frequencies from 103-114.7 GHz, providing 512 channels with a spectral
resolution of R = 3000. In this paper we describe the science goals of CAMELS,
the current system level design for the instrument and the work we are doing on
the detailed designs of the individual components. In addition, we will discuss
our efforts to understand the impact that the design and calibration of the
filter bank on astronomical performance. The shape of the filter channels, the
degree of overlap and the nature of the noise all effect how well the
parameters of a spectral line can be recovered. We have developed a new and
rigorous method for analysing performance, based on the concept of Fisher
information. This can in be turn coupled to a detailed model of the science
case, allowing design trade-offs to be properly investigated.


title: Towards plant wires

abstract:
  In experimental laboratory studies we evaluate a possibility of making
electrical wires from living plants. In scoping experiments we use lettuce
seedlings as a prototype model of a plant wire. We approximate an electrical
potential transfer function by applying direct current voltage to the lettuce
seedlings and recording output voltage. We analyse oscillation frequencies of
the output potential and assess noise immunity of the plant wires. Our findings
will be used in future designs of self-growing wetware circuits and devices,
and integration of plant-based electronic components into future and emergent
bio-hybrid systems.


title:
Co2FeAl Heusler thin films grown on Si and MgO substrates: annealing
  temperature effect

abstract:
  10 nm and 50 nm Co$_{2}$FeAl (CFA) thin films have been deposited on MgO(001)
and Si(001) substrates by magnetron sputtering and annealed at different
temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth
(according to the relation CFA(001)[110]//MgO(001)[100] epitaxial relation),
respectively for CFA films grown on a Si and on a MgO substrate. For these
later, the chemical order varies from the A2 phase to the B2 phase when
increasing the annealing temperature (Ta) while only the A2 disorder type has
been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR)
measurements revealed that the in-plane anisotropy results from the
superposition of a uniaxial and of a fourfold symmetry term for CFA grown on
MgO substrates. This fourfold anisotropy, which disappears completely for
samples grown on Si, is in accord with the crystal structure of the samples.
The fourfold anisotropy field decreases when increasing Ta while the uniaxial
anisotropy field is nearly unaffected by Ta within the investigated range. The
MS-FMR data also allow for concluding that the gyromagnetic factor remains
constant and that the exchange stiffness constant increases with $T_{a}$.
Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement
of the chemical order. We derive a very low intrinsic damping parameter
(1.3*10^-3 and 1.1*10^-3 for films of 50 nm thickness annealed at 615 {\deg}C
grown on MgO and on Si, respectively).


title: Distributed dual gradient methods and error bound conditions

abstract:
  In this paper we propose distributed dual gradient algorithms for linearly
constrained separable convex problems and analyze their rate of convergence
under different assumptions. Under the strong convexity assumption on the
primal objective function we propose two distributed dual fast gradient schemes
for which we prove sublinear rate of convergence for dual suboptimality but
also primal suboptimality and feasibility violation for an average primal
sequence or for the last generated primal iterate. Under the additional
assumption of Lipshitz continuity of the gradient of the primal objective
function we prove a global error bound type property for the dual problem and
then we analyze a dual gradient scheme for which we derive global linear rate
of convergence for both dual and primal suboptimality and primal feasibility
violation. We also provide numerical simulations on optimal power flow
problems.


title:
The $^3$He$(e,e^\prime p)^2$H and $^4$He$(e,e^\prime p)^3$H reactions at
  high momentum transfer

abstract:
  We present updated calculations for observables in the processes
$^3$He($e,e^\prime p$)$^2$H, $^4$He($e,e^\prime p$)$^3$H, and
$^4$He($\vec{e},e^\prime \vec{p}\,$)$^3$H. This update entails the
implementation of improved nucleon-nucleon ($NN$) amplitudes to describe final
state interactions (FSI) within a Glauber approximation and includes full
spin-isospin dependence in the profile operator. In addition, an optical
potential, which has also been updated since previous work, is utilized to
treat FSI for the $^4$He($e,e^\prime p$)$^3$H and $^4$He($\vec{e},e^\prime
\vec{p}\,$)$^3$H reactions. The calculations are compared with experimental
data and show good agreement between theory and experiment. Comparisons are
made between the various approximations in the Glauber treatment, including
model dependence due to the $NN$ scattering amplitudes, rescattering
contributions, and spin dependence. We also analyze the validity of the Glauber
approximation at the kinematics the data is available, by comparing to the
results obtained with the optical potential.


title: Remarks on two fourth order elliptic problems in whole space

abstract:
  We are interested in entire solutions for the semilinear biharmonic equation
$\Delta^{2}u=f(u)$ in $\R^N$, where $f(u)=e^{u}$ or $-u^{-p}\ (p>0)$. For the
exponential case, we prove that any classical entire solution verifies $-\Delta
u>0$ without any restriction, which completes the results in \cite{Dupaigne,
xu-wei} and yields a nonexistence result in $\R^2$ ; we obtain also a refined
asymptotic expansion of radial separatrix solution for $N=3$, which answers a
question in \cite{Berchio}. For the negative power case, we show the
nonexistence of the classical entire solution for any $0<p\leq1$.


title:
Emergence of massless Dirac fermions in graphene's Hofstadter butterfly
  at switches of the quantum Hall phase connectivity

abstract:
  The fractal spectrum of magnetic minibands (Hofstadter butterfly), induced by
the moir\'e super- lattice of graphene on an hexagonal crystal substrate, is
known to exhibit gapped Dirac cones. We show that the gap can be closed by
slightly misaligning the substrate, producing a hierarchy of conical
singularities (Dirac points) in the band structure at rational values Phi =
(p/q)(h/e) of the magnetic flux per supercell. Each Dirac point signals a
switch of the topological quantum number in the connected component of the
quantum Hall phase diagram. Model calculations reveal the scale invariant
conductivity sigma = 2qe^2 / pi h and Klein tunneling associated with massless
Dirac fermions at these connectivity switches.


title: Correlating correlation functions of primordial perturbations

abstract:
  We explore the correlations between correlation functions of the primordial
curvature perturbation produced during inflation. We find that for general
single field inflation, other than the source terms which depend on the model
details, higher order correlation functions are characterized by the power
spectrum, its spectral index and running. The correlation between the
bispectrum and power spectrum is presented as an explicit example of our
systematic approach.


title:
Fermi Surface of KFe$_2$As$_2$ from Quantum Oscillations in
  Magnetostriction

abstract:
  We present a study of the Fermi surface of KFe$_2$As$_2$ single crystals.
Quantum oscillations were observed in magnetostriction measured down to 50 mK
and in magnetic fields $H$ up to 14 T. For $H \parallel c$, the calculated
effective masses are in agreement with recent de Haas-van Alphen and ARPES
experiments, showing enhanced values with respect to the ones obtained from
previous band calculations. For $H \parallel a$, we observed a small orbit at a
cyclotron frequency of 64 T, characterized by an effective mass of $\sim 0.8
m_e$, supporting the presence of a three-dimensional pocket at the Z-point.


title:
Comparison of Expanded Preequilibrium CEM Model with CEM03.03 and
  Experimental Data, FY2013

abstract:
  Emission of light fragments (LF) from nuclear reactions is an open question.
Different reaction mechanisms contribute to their production; the relative
roles of each, and how they change with incident energy, mass number of the
target, and the type and emission energy of the fragments is not completely
understood.
  None of the available models are able to accurately predict emission of LF
from arbitrary reactions. However, the ability to describe production of LF
(especially at energies $\gtrsim 30$ MeV) from many reactions is important for
different applications, such as cosmic-ray-induced Single Event Upsets (SEUs),
radiation protection, and cancer therapy with proton and heavy-ion beams, to
name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los
Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event
generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe
quite well the spectra of fragments with sizes up to $^{4}$He across a broad
range of target masses and incident energies (up to $\sim 5$ GeV for CEM and up
to $\sim 1$ TeV/A for LAQGSM). However, they do not predict the high-energy
tails of LF spectra heavier than $^4$He well. Most LF with energies above
several tens of MeV are emitted during the precompound stage of a reaction. The
current versions of the CEM and LAQGSM event generators do not account for
precompound emission of LF larger than $^{4}$He.
  The aim of our work is to extend the precompound model in them to include
such processes, leading to an increase of predictive power of LF-production in
MCNP6. Extending our models to include emission of fragments heavier than
$^4$He at the precompound stage has already provided preliminary results that
have much better agreement with experimental data.


title: The Generalized Schr\"odinger-Langevin equation

abstract:
  In this work, we derive a generalization of the so-called
Schr\"odinger-Langevin or Kostin equation for a Brownian particle interacting
with a heat bath. This generalization is based on a nonlinear interaction model
providing a state-dependent dissipation process exhibiting multiplicative
noise. Two straightforward applications to the measurement process are then
analyzed, continuous and weak measurements in terms of the quantum Bohmian
trajectory formalism. Finally, it is also shown that the generalized
uncertainty principle, which appears in some approaches to quantum gravity, can
be expressed in terms of this generalized equation


title: Anisotropic Inflation with the non-Vacuum Initial State

abstract:
  In this work we study models of anisotropic inflation with the generalized
non-vacuum initial states for the inflaton field and the gauge field. The
effects of non Bunch-Davies initial condition on the anisotropic power spectrum
and bispectrum are calculated. We show that the non Bunch-Davies initial state
can help to reduce the fine-tuning on the anisotropic power spectrum while
reducing the level of anisotropic bispectrum.


title: Jet-like QED processes : on general properties of impact factors

abstract:
  In this article, general properties of impact factors involved in jet-like
QED processes are explored. In particular, a general link is established
between their helicity properties and their order of magnitude as defined by
jet-like kinematics. Exact results are given for some processes in the strict
forward direction and a general method is proposed to track orders in the
calculation of multi-bremsstrahlung processes.


title: Embedding Graphs under Centrality Constraints for Network Visualization

abstract:
  Visual rendering of graphs is a key task in the mapping of complex network
data. Although most graph drawing algorithms emphasize aesthetic appeal,
certain applications such as travel-time maps place more importance on
visualization of structural network properties. The present paper advocates two
graph embedding approaches with centrality considerations to comply with node
hierarchy. The problem is formulated first as one of constrained
multi-dimensional scaling (MDS), and it is solved via block coordinate descent
iterations with successive approximations and guaranteed convergence to a KKT
point. In addition, a regularization term enforcing graph smoothness is
incorporated with the goal of reducing edge crossings. A second approach
leverages the locally-linear embedding (LLE) algorithm which assumes that the
graph encodes data sampled from a low-dimensional manifold. Closed-form
solutions to the resulting centrality-constrained optimization problems are
determined yielding meaningful embeddings. Experimental results demonstrate the
efficacy of both approaches, especially for visualizing large networks on the
order of thousands of nodes.


title:
p-Pb collisions at 5.02 TeV in the Parton-Hadron-String-Dynamics
  transport approach

abstract:
  The Parton-Hadron-String-Dynamics (PHSD) transport model is employed for p-Pb
collisions at $\sqrt{s_{NN}}=$ 5.02 TeV and compared to recent experimental
data from the LHC as well as to alternative models. We focus on the question of
initial state dynamics, i.e. if the initial state might be approximated by a
superposition of independent nucleon-nucleon collisions or should be considered
as a coherent gluon field as predicted within the color glass condensate (CGC)
framework. We find that the PHSD approach provides correlations between the
charged particle multiplicity at midrapidity and the number of participant
nucleons close to results from the CGC and differs substantially from results
calculated with independent Glauber initial conditions. However, a sizeable
difference is found between the PHSD approach and CGC models with respect to
the rapidity dependence of the average transverse momentum. Accordingly,
related measurements at LHC should allow to prove or disprove the presence of
coherent colour fields in the initial phase of the collisions.


title: Finite-gap solutions of the Sine-Gordon equation

abstract:
  This paper contains first results on the finite-gap integration of the
Sine-Gordon equation. They were published on Russian in 1976. The papers
\cite{Koz}, \cite{KK}, \cite{KK02} have been rewritten in the English language
with small modifications for a convenience. Such a translation was made due to
requests of some interested readers.
  In those papers, the method of constructing of the finite-gap solutions of
the equation $u_{tt}-u_{xx}+\sin u=0$ was proposed. The explicit formulae were
obtained for these solutions. The formulae are constructed in terms of
$\theta$-functions and they are analogous to the formulae obtained by A.R.Its
and V.B.Matveev \cite{IM}, B.A.Dubrovin and S.P.Novikov \cite{DN} for periodic
and almost periodic solutions to the Korteweg de Vries equation.


title: Gapless chiral excitons in thin films of topological insulators

abstract:
  In a nanoscopic thin film of a strong topological insulator (TI) the Coulomb
interaction in the channel that exchanges the two electrons with the same
chirality in two different planes of the slab takes advantage of the minus sign
resulting from such "exchange" and gives rise to a bound state between the
positive energy states in one surface and the negative energy states in the
opposite surfaces. Therefore particle and hole pairs in the {\em undoped} Dirac
cone of the TI thin film form an inter-surface spin-singlet state that lies
below the continuum of free particle-hole pairs. This mode is similar to the
excitons of semiconductors, albeit formed between the electron and hole pairs
from two different two-dimensional surfaces. For low-momenta the dispersion
relation characterizing this collective mode is linear. Experimental comparison
of two slabs with different thicknesses can capture the exponential dependence
of the present effect on the slab thickness.


title: A high-precision mechanical absolute-rotation sensor

abstract:
  We have developed a mechanical absolute-rotation sensor capable of resolving
ground rotation angle of less than 1 nrad$/\sqrt{\text{Hz}}$ above $30$ mHz and
0.2 nrad$/\sqrt{\text{Hz}}$ above $100$ mHz about a single horizontal axis. The
device consists of a meter-scale beam balance, suspended by a pair of flexures,
with a resonance frequency of 10.8 mHz. The center of mass is located 3 $\mu$m
above the pivot, giving an excellent horizontal displacement rejection of
better than $3\times10^{-5}$ rad/m. The angle of the beam is read out optically
using a high-sensitivity autocollimator. We have also built a tiltmeter with
better than 1 nrad$/\sqrt{\text{Hz}}$ sensitivity above 30 mHz. Co-located
measurements using the two instruments allowed us to distinguish between
background rotation signal at low frequencies and intrinsic instrument noise.
The rotation sensor is useful for rotational seismology and for rejecting
background rotation signal from seismometers in experiments demanding high
levels of seismic isolation, such as Advanced LIGO.


title:
Soft modes in jammed hard spheres (I): Mean field theory of the
  isostatic transition

abstract:
  In this paper we consider different models for soft modes in jammed hard
spheres. We show how one can construct mean field models that can be solved
analytically. The analytic solution of these models displays an excess of low
energy soft modes that become more and more localized by decreasing the energy.
A simple solution of these models is found in the infinite dimensional limit.


title: Single Rotating Stars and the Formation of Bipolar Planetary Nebula

abstract:
  We have computed new stellar evolution models that include the effects of
rotation and magnetic torques under different hypothesis. The goal is to test
if a single star can sustain in the envelope the rotational velocities needed
for the magneto hydrodynamical (MHD) simulations to shape bipolar Planetary
Nebulae (PNe) when the high mass-loss rates take place. Stellar evolution
models with main sequence masses of 2.5 and 5 Mo, and initial rotational
velocities of 250 km/s have been followed all the way to the PNe formation
phase. We find that stellar cores have to be spun down using magnetic torques
in order to reproduce the rotation rates observed for white dwarfs. During the
asymptotic giant branch phase and beyond, the magnetic braking of the core has
a practically null effect in increasing the rotational velocity of the envelope
since the stellar angular momentum is removed efficiently by the wind. We have,
as well, tested best possible case scenarios in rather non-physical contexts to
give enough angular momentum to the envelope. We find that we cannot get the
envelope of a single star rotating at the speeds needed by the MHD simulations
to form bipolar PNe. We conclude that single stellar rotators are unlikely to
be the progenitors of bipolar PNe under the current MHD model paradigm.


title: Aluthge transforms of weighted shifts on directed trees

abstract:
  Aluthge transform of a bounded operator is generalized to the case of
unbounded one. A formula for the Aluthge transform of a weighted shift on a
directed tree is established and it is used to construct an example of a
hyponormal operator whose Aluthge transform has trivial domain. It is proven
that such an example can be also constructed in the class of composition
operators. It is also shown that Aluthge transform of a closed, densely defined
operator is not necessarily closable.


title:
Quantum control and process tomography of a semiconductor quantum dot
  hybrid qubit

abstract:
  The similarities between gated quantum dots and the transistors in modern
microelectronics - in fabrication methods, physical structure, and voltage
scales for manipulation - have led to great interest in the development of
quantum bits (qubits) in semiconductor quantum dots. While quantum dot spin
qubits have demonstrated long coherence times, their manipulation is often
slower than desired for important future applications, such as factoring.
Further, scalability and manufacturability are enhanced when qubits are as
simple as possible. Previous work has increased the speed of spin qubit
rotations by making use of integrated micromagnets, dynamic pumping of nuclear
spins, or the addition of a third quantum dot. Here we demonstrate a new qubit
that offers both simplicity - it requires no special preparation and lives in a
double quantum dot with no added complexity - and is very fast: we demonstrate
full control on the Bloch sphere with $\pi$-rotation times less than 100 ps in
two orthogonal directions. We report full process tomography, extracting high
fidelities equal to or greater than 85% for X-rotations and 94% for
Z-rotations. We discuss a path forward to fidelities better than the threshold
for quantum error correction.


title: Non-standard discretization of biological models

abstract:
  We consider certain types of discretization schemes for differential
equations with quadratic nonlinearities, which were introduced by Kahan, and
considered in a broader setting by Mickens. These methods have the property
that they preserve important structural features of the original systems, such
as the behaviour of solutions near to fixed points, and also, where appropriate
(e.g. for certain mechanical systems), the property of being volume-preserving,
or preserving a symplectic/Poisson structure. Here we focus on the application
of Kahan's method to models of biological systems, in particular to reaction
kinetics governed by the Law of Mass Action, and present a general approach to
birational discretization, which is applied to population dynamics of
Lotka-Volterra type.


title: Cosmology of F(R) nonlinear massive gravity

abstract:
  The theory of nonlinear massive gravity can be extended into the F(R) form as
developed in Phys.Rev.D90, 064051 (2014). Being free of the Boulware-Deser
ghost, such a construction has the additional advantage of exhibiting no linear
instabilities around a cosmological background. We investigate various
cosmological evolutions of a universe governed by this generalized massive
gravitational theory. Specifically, under the Starobinsky ansantz, this model
provides a unified description of the cosmological history, from early-time
inflation to late-time self-acceleration. Moreover, under viable F(R) forms,
the scenario leads to a very interesting dark-energy phenomenology, including
the realization of the quintom scenario without any pathology. Finally, we
provide a detailed analysis of the cosmological perturbations at linear order,
as well as the Hamiltonian constraint analysis, in order to examine the
physical degrees of freedom.


title: On Edgeworth Expansions in Generalized Urn Models

abstract:
  The random vector of frequencies in a generalized urn model is viewed as
conditionally independent random variables, given their sum. Such a
representation is exploited to derive Edgeworth expansions for a sum of
functions of such frequencies. Applying these results to urn models such as
with- and without-replacement sampling schemes as well as the multicolor
Polya-Egenberger model, new results are obtained for the chi-square statistic,
for the sample sum in a without replacement scheme, and for the so-called Dixon
statistic that is useful in comparing two samples.


title:
On the Succinctness of Query Rewriting over OWL 2 QL Ontologies with
  Shallow Chases

abstract:
  We investigate the size of first-order rewritings of conjunctive queries over
OWL 2 QL ontologies of depth 1 and 2 by means of hypergraph programs computing
Boolean functions. Both positive and negative results are obtained. Conjunctive
queries over ontologies of depth 1 have polynomial-size nonrecursive datalog
rewritings; tree-shaped queries have polynomial positive existential
rewritings; however, in the worst case, positive existential rewritings can
only be of superpolynomial size. Positive existential and nonrecursive datalog
rewritings of queries over ontologies of depth 2 suffer an exponential blowup
in the worst case, while first-order rewritings are superpolynomial unless
$\text{NP} \subseteq \text{P}/\text{poly}$. We also analyse rewritings of
tree-shaped queries over arbitrary ontologies and observe that the query
entailment problem for such queries is fixed-parameter tractable.


title: Compressed absorbing boundary conditions via matrix probing

abstract:
  Absorbing layers are sometimes required to be impractically thick in order to
offer an accurate approximation of an absorbing boundary condition for the
Helmholtz equation in a heterogeneous medium. It is always possible to reduce
an absorbing layer to an operator at the boundary by layer-stripping
elimination of the exterior unknowns, but the linear algebra involved is
costly. We propose to bypass the elimination procedure, and directly fit the
surface-to-surface operator in compressed form from a few exterior Helmholtz
solves with random Dirichlet data. The result is a concise description of the
absorbing boundary condition, with a complexity that grows slowly (often,
logarithmically) in the frequency parameter.


title:
Energy Loss of a Heavy Particle near 3D Charged Rotating Hairy Black
  Hole

abstract:
  In this paper we consider charged rotating black hole in 3 dimensions with an
scalar charge and discuss about energy loss of heavy particle moving near the
black hole horizon. We also study quasi-normal modes and find dispersion
relations. We find that the effect of scalar charge and electric charge is
increasing energy loss.


title: Real dimensional spaces in noncommutative geometry

abstract:
  In this paper we will extend the product of spectral triples to a product of
semifinite spectral triples. We will prove that finite summability and
regularity are preserved under taking products. Connes and Marcolli constructed
for each $z\in(0,\infty)$ a type ${\rm II}_\infty$-semifinite spectral triple
which can be considered as a geometric space of dimension $z$. A small adaption
of their construction yields a type ${\rm I}$-semifinite spectral triple. We
will investigate the properties of these semifinite spectral triples. At the
same time we will also avoid the need for an infra-red cutoff to compute the
dimension spectrum. Using this collection of semifinite spectral triples and
the product of semifinite spectral triples one can construct a mathematical
tool for dimensional and zeta-function regularisation in quantum field theory.


title: Dynamics of Vapor Layer Under a Leidenfrost Drop

abstract:
  In the Leidenfrost effect a small drop of fluid is levitated above a
sufficiently hot surface, on a persistent vapor layer generated by evaporation
from the drop. The vapor layer thermally insulates the drop from the surface
leading to extraordinarily long drop lifetimes. The top-view shape of the
levitated drops can exhibit persistent star-like vibrations. I extend recent
work [Burton et al. PRL 2012] to study the bottom surface of the drop using
interference-imaging. In this work I use a high-speed camera and automated
image analysis to image, locate and classify the interference fringes. From the
interference fringes I reconstruct the shape and height profile of the rim
where the drop is closest to the surface. I measure the drop-size dependence of
the planar vibrational mode frequencies, which agree well with previous work. I
observe a distinct breathing mode in the average radius of the drop, the
frequency of which scales differently with drop size than the other modes. This
breathing mode can be tightly coupled to a vertical motion of the drop. I
further observe a qualitative difference in the structure and dynamics of the
vertical profile of the rim between large and small drops.


title: Monte Carlo Simulation for Lasso-Type Problems by Estimator Augmentation

abstract:
  Regularized linear regression under the $\ell_1$ penalty, such as the Lasso,
has been shown to be effective in variable selection and sparse modeling. The
sampling distribution of an $\ell_1$-penalized estimator $\hat{\beta}$ is hard
to determine as the estimator is defined by an optimization problem that in
general can only be solved numerically and many of its components may be
exactly zero. Let $S$ be the subgradient of the $\ell_1$ norm of the
coefficient vector $\beta$ evaluated at $\hat{\beta}$. We find that the joint
sampling distribution of $\hat{\beta}$ and $S$, together called an augmented
estimator, is much more tractable and has a closed-form density under a normal
error distribution in both low-dimensional ($p\leq n$) and high-dimensional
($p>n$) settings. Given $\beta$ and the error variance $\sigma^2$, one may
employ standard Monte Carlo methods, such as Markov chain Monte Carlo and
importance sampling, to draw samples from the distribution of the augmented
estimator and calculate expectations with respect to the sampling distribution
of $\hat{\beta}$. We develop a few concrete Monte Carlo algorithms and
demonstrate with numerical examples that our approach may offer huge advantages
and great flexibility in studying sampling distributions in $\ell_1$-penalized
linear regression. We also establish nonasymptotic bounds on the difference
between the true sampling distribution of $\hat{\beta}$ and its estimator
obtained by plugging in estimated parameters, which justifies the validity of
Monte Carlo simulation from an estimated sampling distribution even when $p\gg
n\to \infty$.


title:
Non-Hermitian systems of Euclidean Lie algebraic type with real
  eigenvalue spectra

abstract:
  We study several classes of non-Hermitian Hamiltonian systems, which can be
expressed in terms of bilinear combinations of Euclidean Lie algebraic
generators. The classes are distinguished by different versions of antilinear
(PT)-symmetries exhibiting various types of qualitative behaviour. On the basis
of explicitly computed non-perturbative Dyson maps we construct metric
operators, isospectral Hermitian counterparts for which we solve the
corresponding time-independent Schroedinger equation for specific choices of
the coupling constants. In these cases general analytical expressions for the
solutions are obtained in the form of Mathieu functions, which we analyze
numerically to obtain the corresponding energy eigenspectra. We identify
regions in the parameter space for which the corresponding spectra are entirely
real and also domains where the PT symmetry is spontaneously broken and
sometimes also regained at exceptional points. In some cases it is shown
explicitly how the threshold region from real to complex spectra is
characterized by the breakdown of the Dyson maps or the metric operator. We
establish the explicit relationship to models currently under investigation in
the context of beam dynamics in optical lattices.


title:
Solution-Processable Graphene Oxide as an Efficient Hole Injection Layer
  for High Luminance Organic Light-Emitting Diodes

abstract:
  The application of solution-processable graphene oxide (GO) as hole injection
layer in organic light-emitting diodes (OLEDs) is demonstrated. High luminance
of over 53,000 cd m-2 is obtained at only 10 V. The results will unlock a route
of applying GO in flexible OLEDs and other electrode applications.


title: Diffuse Scattering on Graphs

abstract:
  We formulate and analyze difference equations on graphs analogous to
time-independent diffusion equations arising in the study of diffuse scattering
in continuous media. Moreover, we show how to construct solutions in the
presence of weak scatterers from the solution to the homogeneous (background
problem) using Born series, providing necessary conditions for convergence and
demonstrating the process through numerous examples. In addition, we outline a
method for finding Green's functions for Cayley graphs for both abelian and
non-abelian groups. Finally, we conclude with a discussion of the effects of
sparsity on our method and results, outlining the simplifications that can be
made provided that the scatterers are weak and well-separated.


title: Quantitative version of Beurling-Helson theorem

abstract:
  It is proved that any continuous function f on the unit circle such that the
sequence e^{in f}, n=1,2,... has small Wiener norm \| e^{in f} \|_A = o
(\frac{\log^{1/22} |n|}{(\log \log |n|)^{3/11}}), is linear. Moreover, we get
lower bounds for Wiener norm of characteristic functions of subsets from Z_p in
the case of prime p.


title:
Decay data of radionuclides along the valley of nuclear stability for
  astrophysical applications

abstract:
  Several directions of the demand of decay data in nuclear astrophysics are
discussed for radionuclides near the valley of nuclear stability. The current
decay data evaluation results have been presented for a number of radionuclides
of astrophysical interest. An extended list of such nuclides is offered for
their nuclear characteristics to be further evaluated by the Decay Data
Evaluation Project cooperation participants.


title: Quark structure of the $X(3872)$ and $\chi_b(3P)$ resonances

abstract:
  We discuss the nature of the $\chi_b(3P)$ and $X(3872)$ mesons: Are the
$\chi_b(3P)$'s standard $b \bar b$ mesons or $b \bar b$ states with a
significative continuum component? Is the $X(3872)$ a $c \bar c$ state with
continuum coupling effects or a meson-meson molecule? To do that, we compare
quark model and unquenched quark model results for the mass barycenter and
splittings of the $\chi_b(3P)$ multiplet. Future and more precise experimental
results will discriminate between the two interpretations. In the case of the
$X(3872)$, we interpret it a $c \bar c$ core plus higher Fock components due to
the coupling to the meson-meson continuum, thus we think that it is compatible
with the meson $\chi_{c1}(2P)$, with $J^{PC} = 1^{++}$. The $J^{PC} = 1^{++}$
quantum numbers are in agreement with the experimental results found by the
LHCb collaboration. In our view, the $X(3872)$'s mass is lower than the quark
model's predictions because of self energy shifts. We also provide an
estimation of the open charm/bottom strong decay modes of the $X(3872)$ and
$\chi_b(3P)$ mesons, such as $X(3872) \rightarrow D \bar D^*$ and
$\chi_{b2}(3P) \rightarrow B \bar B$, and radiative transitions.


title:
Distributed convex optimization via continuous-time coordination
  algorithms with discrete-time communication

abstract:
  This paper proposes a novel class of distributed continuous-time coordination
algorithms to solve network optimization problems whose cost function is a sum
of local cost functions associated to the individual agents. We establish the
exponential convergence of the proposed algorithm under (i) strongly connected
and weight-balanced digraph topologies when the local costs are strongly convex
with globally Lipschitz gradients, and (ii) connected graph topologies when the
local costs are strongly convex with locally Lipschitz gradients. When the
local cost functions are convex and the global cost function is strictly
convex, we establish asymptotic convergence under connected graph topologies.
We also characterize the algorithm's correctness under time-varying interaction
topologies and study its privacy preservation properties. Motivated by
practical considerations, we analyze the algorithm implementation with
discrete-time communication. We provide an upper bound on the stepsize that
guarantees exponential convergence over connected graphs for implementations
with periodic communication. Building on this result, we design a
provably-correct centralized event-triggered communication scheme that is free
of Zeno behavior. Finally, we develop a distributed, asynchronous
event-triggered communication scheme that is also free of Zeno with asymptotic
convergence guarantees. Several simulations illustrate our results.


title:
Studies of dijet transverse momentum balance and pseudorapidity
  distributions in pPb collisions at sqrt(s[NN]) = 5.02 TeV

abstract:
  Dijet production has been measured in pPb collisions at a nucleon-nucleon
centre-of-mass energy of 5.02 TeV. A data sample corresponding to an integrated
luminosity of 35 inverse nanobarns was collected using the Compact Muon
Solenoid detector at the Large Hadron Collider. The dijet transverse momentum
balance, azimuthal angle correlations, and pseudorapidity distributions are
studied as a function of the transverse energy in the forward calorimeters
(ETHFfour). For pPb collisions, the dijet transverse momentum ratio and the
width of the distribution of dijet azimuthal angle difference are comparable to
the same quantities obtained from a simulated pp reference and insensitive to
ETHFfour. In contrast, the mean value of the dijet pseudorapidity is found to
change monotonically with increasing ETHFfour, indicating a correlation between
the energy emitted at large pseudorapidity and the longitudinal motion of the
dijet frame. The pseudorapidity distribution of the dijet system in minimum
bias pPb collisions is compared with next-to-leading-order perturbative QCD
predictions obtained from both nucleon and nuclear parton distribution
functions, and the data more closely match the latter.


title:
Analytical Relation between Quark Confinement and Chiral Symmetry
  Breaking in QCD

abstract:
  We study the relation between quark confinement and spontaneous
chiral-symmetry breaking directly in QCD. In lattice QCD formalism, we derive
an analytical gauge-invariant relation between the Polyakov loop $\langle L_P
\rangle$ and the Dirac eigenvalues $\lambda_n$, i.e., $\langle L_P \rangle
\propto \sum_n \lambda_n^{N_t -1} \langle n|\hat U_4|n \rangle$, on a
temporally odd-number lattice, where the temporal lattice size $N_t$ is odd.
Here, $|n \rangle$ denotes the Dirac eigenmode, i.e., $\not D|n
\rangle=i\lambda_n|n \rangle$, and $\hat U_4$ the temporal link-variable
operator. We here use an ordinary square lattice with the normal periodic
boundary condition for link-variables $U_\mu(s)$ in the temporal direction.
Because of the factor $\lambda_n^{N_t -1}$ in the analytical relation, the
contribution of low-lying Dirac modes to the Polyakov loop is negligibly small
in both confined and deconfined phases, while the low-lying Dirac modes are
essential for chiral symmetry breaking. Also, in lattice QCD simulations, we
numerically confirm the analytical relation, non-zero finiteness of $\langle
n|\hat U_4|n \rangle$ for each Dirac mode, and negligibly small contribution of
low-lying Dirac modes to the Polyakov loop. Thus, we conclude that low-lying
Dirac modes are not essential for confinement, which indicates no direct
one-to-one correspondence between confinement and chiral symmetry breaking in
QCD.


title:
An Empirical Determination of the Intergalactic Background Light Using
  NIR Deep Galaxy Survey Data out to 5 microns and the Gamma-ray Opacity of the
  Universe

abstract:
  We extend our previous model-independent determination of the intergalactic
background light (IBL), based purely on galaxy survey data, out to a wavelength
of 5 microns. Our approach enables us to constrain the range of photon
densities, based on the uncertainties from observationally determined
luminosity densities and colors. We further determine a 68% confidence upper
and lower limit on the opacity of the universe to gamma-rays up to energies of
1.6/(1+z) TeV. A comparison of our lower limit redshift-dependent opacity
curves to the opacity limits derived from the results of both ground-based air
Cherenkov telescope and Fermi-LAT observations of PKS 1424+240 allows us to
place a new upper limit on the redshift of this source, independent of IBL
modeling.


title:
Cause Identification from Aviation Safety Incident Reports via Weakly
  Supervised Semantic Lexicon Construction

abstract:
  The Aviation Safety Reporting System collects voluntarily submitted reports
on aviation safety incidents to facilitate research work aiming to reduce such
incidents. To effectively reduce these incidents, it is vital to accurately
identify why these incidents occurred. More precisely, given a set of possible
causes, or shaping factors, this task of cause identification involves
identifying all and only those shaping factors that are responsible for the
incidents described in a report. We investigate two approaches to cause
identification. Both approaches exploit information provided by a semantic
lexicon, which is automatically constructed via Thelen and Riloffs Basilisk
framework augmented with our linguistic and algorithmic modifications. The
first approach labels a report using a simple heuristic, which looks for the
words and phrases acquired during the semantic lexicon learning process in the
report. The second approach recasts cause identification as a text
classification problem, employing supervised and transductive text
classification algorithms to learn models from incident reports labeled with
shaping factors and using the models to label unseen reports. Our experiments
show that both the heuristic-based approach and the learning-based approach
(when given sufficient training data) outperform the baseline system
significantly.


title:
The Gaia-ESO Survey: radial metallicity gradients and age-metallicity
  relation of stars in the Milky Way disk

abstract:
  We study the relationship between age, metallicity, and alpha-enhancement of
FGK stars in the Galactic disk. The results are based upon the analysis of
high-resolution UVES spectra from the Gaia-ESO large stellar survey. We explore
the limitations of the observed dataset, i.e. the accuracy of stellar
parameters and the selection effects that are caused by the photometric target
preselection. We find that the colour and magnitude cuts in the survey suppress
old metal-rich stars and young metal-poor stars. This suppression may be as
high as 97% in some regions of the age-metallicity relationship. The dataset
consists of 144 stars with a wide range of ages from 0.5 Gyr to 13.5 Gyr,
Galactocentric distances from 6 kpc to 9.5 kpc, and vertical distances from the
plane 0 < |Z| < 1.5 kpc. On this basis, we find that i) the observed
age-metallicity relation is nearly flat in the range of ages between 0 Gyr and
8 Gyr; ii) at ages older than 9 Gyr, we see a decrease in [Fe/H] and a clear
absence of metal-rich stars; this cannot be explained by the survey selection
functions; iii) there is a significant scatter of [Fe/H] at any age; and iv)
[Mg/Fe] increases with age, but the dispersion of [Mg/Fe] at ages > 9 Gyr is
not as small as advocated by some other studies. In agreement with earlier
work, we find that radial abundance gradients change as a function of vertical
distance from the plane. The [Mg/Fe] gradient steepens and becomes negative. In
addition, we show that the inner disk is not only more alpha-rich compared to
the outer disk, but also older, as traced independently by the ages and Mg
abundances of stars.


title: Integral closure of rings of integer-valued polynomials on algebras

abstract:
  Let $D$ be an integrally closed domain with quotient field $K$. Let $A$ be a
torsion-free $D$-algebra that is finitely generated as a $D$-module. For every
$a$ in $A$ we consider its minimal polynomial $\mu_a(X)\in D[X]$, i.e. the
monic polynomial of least degree such that $\mu_a(a)=0$. The ring ${\rm
Int}_K(A)$ consists of polynomials in $K[X]$ that send elements of $A$ back to
$A$ under evaluation. If $D$ has finite residue rings, we show that the
integral closure of ${\rm Int}_K(A)$ is the ring of polynomials in $K[X]$ which
map the roots in an algebraic closure of $K$ of all the $\mu_a(X)$, $a\in A$,
into elements that are integral over $D$. The result is obtained by identifying
$A$ with a $D$-subalgebra of the matrix algebra $M_n(K)$ for some $n$ and then
considering polynomials which map a matrix to a matrix integral over $D$. We
also obtain information about polynomially dense subsets of these rings of
polynomials.


title:
Nonreciprocal spin-wave channeling along textures driven by the
  Dzyaloshinskii-Moriya interaction

abstract:
  Ultrathin metallic ferromagnets on substrates with strong spin-orbit coupling
can exhibit induced chiral interactions of the Dzyaloshinskii-Moriya (DM) form.
For systems with perpendicular anisotropy, the presence of DM interactions has
important consequences for current-driven domain-wall motion and underpins
possible spintronic applications involving skyrmions. We show theoretically how
spin textures driven by the DM interaction allow nonreciprocal channeling of
spin waves, leading to measurable features in magnetic wires, dots, and domain
walls. Our results provide methods for detecting induced DM interactions in
metallic multilayers and controlling spin wave propagation in ultrathin
nanostructures.


title: Quantum driving and work

abstract:
  As quantum systems become more experimentally accessible, we are forced to
reconsider the notions of control and work to fully account for quantum
effects. To this end, we identify the work injected into a quantum system
during a general quantum-mechanical driving protocol and quantify the relevant
heat flows. The known results that are applicable in the limit of a classical
drive are shown to emerge from our equations as a special case. Using the
established framework, we show that the Bochkov--Kuzovlev identity for the
exclusive work distribution is modified in a nontrivial way by the accumulation
of system--drive correlations resulting from quantum backaction. Our results
accentuate the conceptual and discernible differences between a fully
quantum-mechanical and classical driving protocols of quantum systems.


title:
Avoiding Serialization Effects in Data-Dependency aware Task Parallel
  Algorithms for Spatial Decomposition

abstract:
  Spatial decomposition is a popular basis for parallelising code. Cast in the
frame of task parallelism, calculations on a spatial domain can be treated as a
task. If neighbouring domains interact and share results, access to the
specific data needs to be synchronized to avoid race conditions. This is the
case for a variety of applications, like most molecular dynamics and many
computational fluid dynamics codes. Here we present an unexpected problem which
can occur in dependency-driven task parallelization models like StarSs: the
tasks accessing a specific spatial domain are treated as interdependent, as
dependencies are detected automatically via memory addresses. Thus, the order
in which tasks are generated will have a severe impact on the dependency tree.
In the worst case, a complete serialization is reached and no two tasks can be
calculated in parallel. We present the problem in detail based on an example
from molecular dynamics, and introduce a theoretical framework to calculate the
degree of serialization. Furthermore, we present strategies to avoid this
unnecessary problem. We recommend treating these strategies as best practice
when using dependency-driven task parallel programming models like StarSs on
such scenarios.


title: Kosterlitz-Thouless and Potts transitions in a generalized XY model

abstract:
  We present extensive numerical simulations of a generalized XY model with
nematic-like terms recently proposed by Poderoso {\it et al} [PRL
106(2011)067202]. Using finite size scaling and focusing on the $q=3$ case, we
locate the transitions between the paramagnetic (P), the nematic-like (N) and
the ferromagnetic (F) phases. The results are compared with the recently
derived lower bounds for the P-N and P-F transitions. While the P-N transition
is found to be very close to the lower bound, the P-F transition occurs
significantly above the bound. Finally, the transition between the nematic-like
and the ferromagnetic phases is found to belong to the 3-states Potts
universality class.


title: Attacks And Counterattacks On Wireless Sensor Networks

abstract:
  WSN is formed by autonomous nodes with partial memory, communication range,
power, and bandwidth. Their occupation depends on inspecting corporal and
environmental conditions and communing through a system and performing data
processing. The application field is vast, comprising military, ecology,
healthcare, home or commercial and require a highly secured communication. The
paper analyses different types of attacks and counterattacks and provides
solutions for the WSN threats


title: Mesoscopic Models of Plants Composed of Metallic Nanowires

abstract:
  Various metallic structures of complex shape resembling living plant
organisms (biomimetics) are produced as a result of selfassembly of nanowires
growing on porous membranes in the course of pulse current electrodeposition.
These structures occur if the electroplating is continued after the nanowires
appear on the membrane surface. By varying the membrane ge- ometry, pulse
current electroplating parameters, and alternating electrodeposition from two
baths composed of a variety of electrolytes, diverse models were fabricated,
including a hollow container with a wall thickness of 10 nm to 20 nm. This
biomimetic method suggests an analogy between the shape forming processes of
plants and their metallic models. Nanostruc- tured mesostructures of various
metals (Ag, Pd, Ni), alloys (PdNi, PbIn) and hybrid structures (PdNiPb,
PdNiPbIn) were obtained. They can be of interest for fundamental research
(self-assembly, morphogenesis) as well as for applications in nanotechnology
(catalysis, nanoplasmonics, medicine, superhydrophobic surfaces).


title: Periodic problem for the nonlinear Schroedinger equation

abstract:
  The paper offers the method of discovering of some class of solutions for the
nonlinear Schroedinger equation. An algorithm of constructive solving of the
Cauchy periodic problem with a finite-gap initial condition was also obtained.


title: Humanoid Robot With Vision Recognition Control System

abstract:
  This paper presents a solution to controlling humanoid robotic systems. The
robot can be programmed to execute certain complex actions based on basic
motion primitives. The humanoid robot is programmed using a PC. The software
running on the PC can obtain at any given moment information about the state of
the robot, or it can program the robot to execute a different action, providing
the possibility of implementing a complex behavior. We want to provide the
robotic system the ability to understand more on the external real world. In
this paper we describe a method for detecting ellipses in real world images
using the Randomized Hough Transform with Result Clustering. Real world images
are preprocessed, noise reduction, greyscale transform, edge detection and
finaly binarization in order to be processed by the actual ellipse detector.
After all the ellipses are detected a post processing phase clusters the
results.


title: Leaf Classification Using Shape, Color, and Texture Features

abstract:
  Several methods to identify plants have been proposed by several researchers.
Commonly, the methods did not capture color information, because color was not
recognized as an important aspect to the identification. In this research,
shape and vein, color, and texture features were incorporated to classify a
leaf. In this case, a neural network called Probabilistic Neural network (PNN)
was used as a classifier. The experimental result shows that the method for
classification gives average accuracy of 93.75% when it was tested on Flavia
dataset, that contains 32 kinds of plant leaves. It means that the method gives
better performance compared to the original work.


title:
An efficient playout smoothing mechanism for layered streaming in P2P
  networks

abstract:
  Layered video streaming in peer-to-peer (P2P) networks has drawn great
interest, since it can not only accommodate large numbers of users, but also
handle peer heterogeneity. However, there's still a lack of comprehensive
studies on chunk scheduling for the smooth playout of layered streams in P2P
networks. In these situations, a playout smoothing mechanism can be used to
ensure the uniform delivery of the layered stream. This can be achieved by
reducing the quality changes that the stream undergoes when adapting to
changing network conditions. This paper complements previous efforts in
throughput maximization and delay minimization for P2P streaming by considering
the consequences of playout smoothing on the scheduling mechanisms for stream
layer acquisition. The two main problems to be considered when designing a
playout smoothing mechanism for P2P streaming are the fluctuation in available
bandwidth between peers and the unreliability of user-contributed
resources--particularly peer churn. Since the consideration of these two
factors in the selection and scheduling of stream layers is crucial to maintain
smooth stream playout, the main objective of our smoothing mechanism becomes
the determination of how many layers


title:
The Effects on Supernova Shock Breakout and Swift Light Curves Due to
  the Mass of the Hydrogen-Rich Envelope

abstract:
  Mass loss remains one of the primary uncertainties in stellar evolution. In
the most massive stars, mass loss dictates the circumstellar medium and can
significantly alter the fate of the star. Mass loss is caused by a variety of
wind mechanisms and also through binary interactions. Supernovae are excellent
probes of this mass loss, both the circumstellar material and the reduced mass
of the hydrogen-rich envelope. In this paper, we focus on the effects of
reducing the hydrogen-envelope mass on the supernova light curve, studying both
the shock breakout and peak light curve emission for a wide variety of mass
loss scenarios. Even though the trends of this mass loss will be masked
somewhat by variations caused by different progenitors, explosion energies, and
circumstellar media, these trends have significant effects on the supernova
light-curves that should be seen in supernova surveys. We conclude with a
comparison of our results to a few key observations.


title:
Computation of dynamical correlation functions of the spin-1
  Babujan-Takhtajan chain

abstract:
  The dynamical structure factor of the Babujan-Takhtajan antiferromagnetic
spin-1 chain is computed numerically at zero temperature and zero magnetic
field, using the higher-spin generalization of an Algebraic Bethe Ansatz-based
method previously used for spin-1/2 integrable chains. This method, which
consists in the explicit construction of eigenstates and the summation of the
Lehmann representation of the correlator, is here particularly challenging to
implement in view of the presence of strongly deviated string solutions to the
Bethe equations. We show that a careful treatment of these deviations makes it
possible to obtain perfect saturation of sum rules for small system sizes, and
extremely good saturation for large system sizes where the dynamical structure
factor is computed by including all two-spinon and four-spinon contributions.
The real-space spin-spin correlation, obtained by Fourier transforming our
results, displays asymptotics fitting predictions from conformal field theory.


title: Reliable, Deniable, and Hidable Communication over Multipath Networks

abstract:
  We consider the scenario wherein Alice wants to (potentially) communicate to
the intended receiver Bob over a network consisting of multiple parallel links
in the presence of a passive eavesdropper Willie, who observes an unknown
subset of links. A primary goal of our communication protocol is to make the
communication "deniable", {\it i.e.}, Willie should not be able to {\it
reliably} estimate whether or not Alice is transmitting any {\it covert}
information to Bob. Moreover, if Alice is indeed actively communicating, her
covert messages should be information-theoretically "hidable" in the sense that
Willie's observations should not {\it leak any information} about Alice's
(potential) message to Bob -- our notion of hidability is slightly stronger
than the notion of information-theoretic strong secrecy well-studied in the
literature, and may be of independent interest. It can be shown that
deniability does not imply either hidability or (weak or strong)
information-theoretic secrecy; nor does any form of information-theoretic
secrecy imply deniability. We present matching inner and outer bounds on the
capacity for deniable and hidable communication over {\it multipath networks}.


title: Black holes within Asymptotic Safety

abstract:
  Black holes are probably among the most fascinating objects populating our
universe. Their characteristic features found within general relativity,
encompassing spacetime singularities, event horizons, and black hole
thermodynamics, provide a rich testing ground for quantum gravity ideas. We
review the status of black holes within a particular proposal for quantum
gravity, Weinberg's asymptotic safety program. Starting from a brief survey of
the effective average action and scale setting procedures, an improved quantum
picture of the black hole is developed. The Schwarzschild black hole and its
generalizations including angular momenta, higher-derivative corrections and
the implications of extra dimensions are discussed in detail. In addition, the
quantum singularity emerging for the inclusion of a cosmological constant is
elucidated and linked to the phenomenon of a dynamical dimensional reduction of
spacetime.


title:
Resembling holographic dark energy with f(R)gravity as scalar field and
  ghost dark energy with tachyon scalar fields

abstract:
  In this article,the dynamics and potential of two different scalar field
models is presented in a at Friedmann-Lemaitre-Robertson-Walker(FLRW) universe.
One of those models is obtained from the corresponding relation between
holographic energy density (HED) with energy density of the corresponding
scalar field of f(R) gravity,and other models is achieved from connection
between the ghost energy density (GDE) with energy density of the tachyon field
model. Also, a f(R) model according to the the HDE model is calculated then
stability,anti -gravity and viable conditions on it are investigated.


title:
Simulations of cosmic rays in large-scale structures: numerical and
  physical effects

abstract:
  Non-thermal (relativistic) particles are injected into the cosmos by
structure formation shock waves, active galactic nuclei and stellar explosions.
We present a suite of unigrid cosmological simulations (up to $2048^3$) using a
two-fluid model in the grid code ENZO. The simulations include the dynamical
effects of cosmic-ray (CR) protons and cover a range of theoretically motivated
acceleration efficiencies. For the bulk of the cosmic volume the modelling of
CR processes is rather stable with respect to resolution, provided that a
minimum (cell) resolution of $\approx 100 ~\rm kpc/h$ is employed. However, the
results for the innermost cluster regions depend on the assumptions for the
baryonic physics. Inside clusters, non-radiative runs at high resolution tend
to produce an energy density of CRs that are below available upper limits from
the FERMI satellite, while the radiative runs are found to produce a higher
budget of CRs. We show that weak ($M \leq 3-5$) shocks and shock-reacceleration
are crucial to set the level of CRs in the innermost region of clusters, while
in the outer regions the level of CR energy is mainly set via direct injection
by stronger shocks, and is less sensitive to cooling and feedback from active
galactic nuclei and supernovae.


title: Nonlinear dynamics of trapped waves on jet currents and rogue waves

abstract:
  Nonlinear dynamics of surface gravity waves trapped by an opposing jet
current is studied analytically and numerically. For wave fields narrowband in
frequency but not necessarily with narrow angular distributions the developed
asymptotic weakly nonlinear theory based on the modal approach of (V. Shrira,
A. Slunyaev, J. Fluid. Mech, 738, 65, 2014) leads to the one-dimensional
modified nonlinear Schr\"{o}dinger equation of self-focusing type for a single
mode. Its solutions such as envelope solitons and breathers are considered to
be prototypes of rogue waves; these solutions, in contrast to waves in the
absence of currents, are robust with respect to transverse perturbations, which
suggests potentially higher probability of rogue waves. Robustness of the
long-lived analytical solutions in form of the modulated trapped waves and
solitary wave groups is verified by direct numerical simulations of potential
Euler equations.


title:
Efficiency Measurements and Installation of a New Grating for the OSIRIS
  Spectrograph at Keck Observatory

abstract:
  OSIRIS is a near-infrared integral field spectrograph operating behind the
adaptive optics system at W. M. Keck Observatory. While OSIRIS has been a
scientifically productive instrument to date, its sensitivity has been limited
by a grating efficiency that is less than half of what was expected. The
spatially averaged efficiency of the old grating, weighted by error, is
measured to be 39.5 +/- 0.8 % at {\lambda} = 1.310 {\mu}m, with large field
dependent variation of 11.7 % due to efficiency variation across the grating
surface. Working with a new vendor, we developed a more efficient and uniform
grating with a weighted average efficiency at {\lambda} = 1.310 {\mu}m of 78.0
+/- 1.6 %, with field variation of only 2.2 %. This is close to double the
average efficiency and five times less variation across the field. The new
grating was installed in December 2012, and on- sky OSIRIS throughput shows an
average factor of 1.83 improvement in sensitivity between 1 and 2.4 microns. We
present the development history, testing, and implementation of this new
near-infrared grating for OSIRIS and report the comparison with the
predecessors. The higher sensitivities are already having a large impact on
scientific studies with OSIRIS.


title: Scattering outcomes of close-in planets: constraints on planet migration

abstract:
  Many exoplanets in close-in orbits are observed to have relatively high
eccentricities and large stellar obliquities. We explore the possibility that
these result from planet-planet scattering by studying the dynamical outcomes
from a large number of orbit integrations in systems with two and three
gas-giant planets in close-in orbits (0.05 AU < a < 0.15 AU). We find that at
these orbital separations, unstable systems starting with low eccentricities
and mutual inclinations ($e\lesssim0.1$, $i\lesssim0.1$) generally lead to
planet-planet collisions in which the collision product is a planet on a
low-eccentricity, low-inclination orbit. This result is inconsistent with the
observations. We conclude that eccentricity and inclination excitation from
planet-planet scattering must precede migration of planets into short-period
orbits. This result constrains theories of planet migration: the semi-major
axis must shrink by 1-2 orders of magnitude without damping the eccentricity
and inclination.


title:
Toward Multi-Differential Cross Sections: Measuring Two Angularities on
  a Single Jet

abstract:
  The analytic study of differential cross sections in QCD has typically
focused on individual observables, such as mass or thrust, to great success.
Here, we present a first study of double differential jet cross sections
considering two recoil-free angularities measured on a single jet. By analyzing
the phase space defined by the two angularities and using methods from
soft-collinear effective theory, we prove that the double differential cross
section factorizes at the boundaries of the phase space. We also show that the
cross section in the bulk of the phase space cannot be factorized using only
soft and collinear modes, excluding the possibility of a global factorization
theorem in soft-collinear effective theory. Nevertheless, we are able to define
a simple interpolation procedure that smoothly connects the factorization
theorem at one boundary to the other. We present an explicit example of this at
next-to-leading logarithmic accuracy and show that the interpolation is unique
up to $\alpha_s^4$ order in the exponent of the cross section, under reasonable
assumptions. This is evidence that the interpolation is sufficiently robust to
account for all logarithms in the bulk of phase space to the accuracy of the
boundary factorization theorem. We compare our analytic calculation of the
double differential cross section to Monte Carlo simulation and find
qualitative agreement. Because our arguments rely on general structures of the
phase space, we expect that much of our analysis would be relevant for the
study of phenomenologically well-motivated observables, such as
$N$-subjettiness, energy correlation functions, and planar flow.


title:
An uncertainty principle for star formation. I. Why galactic star
  formation relations break down below a certain spatial scale

abstract:
  Galactic scaling relations between the (surface densities of) the gas mass
and the star formation (SF) rate are known to develop substantial scatter or
even change form when considered below a certain spatial scale. We quantify how
this behaviour should be expected due to the incomplete statistical sampling of
independent star-forming regions. Other included limiting factors are the
incomplete sampling of SF tracers from the stellar initial mass function and
the spatial drift between gas and stars. We present a simple uncertainty
principle for SF, which can be used to predict and interpret the failure of
galactic SF relations on small spatial scales. This uncertainty principle
explains how the scatter of SF relations depends on the spatial scale and
predicts a scale-dependent bias of the gas depletion time-scale when centering
an aperture on gas or SF tracer peaks. We show how the scatter and bias are
sensitive to the physical size and time-scales involved in the SF process (such
as its duration or the molecular cloud lifetime), and illustrate how our
formalism provides a powerful tool to constrain these largely unknown
quantities. Thanks to its general form, the uncertainty principle can also be
applied to other astrophysical systems, e.g. addressing the time-evolution of
star-forming cores, protoplanetary discs, or galaxies and their nuclei.


title:
Comparing and Counting Logs in Direct and Effective Methods of
  Resummation

abstract:
  We compare methods to resum logarithms in event shape distributions as they
have been used in perturbative QCD directly and in effective field theory. We
demonstrate that they are equivalent. In showing this equivalence, we are able
to put standard soft-collinear effective theory (SCET) formulae for cross
sections in momentum space into a novel form more directly comparable with
standard QCD formulae, and endow the QCD formulae with dependence on separated
hard, jet, and soft scales, providing potential ways to improve estimates of
theoretical uncertainty. We show how to compute cross sections in momentum
space to keep them as accurate as the corresponding expressions in Laplace
space. In particular, we point out that that care is required in truncating
differential distributions at N$^k$LL accuracy to ensure they match the
accuracy of the corresponding cumulant or Laplace transform. We explain how to
avoid such mismatches at N$^k$LL accuracy, and observe why they can also be
avoided by working to N$^k$LL$'$ accuracy.


title:
Dynamical Models of Elliptical Galaxies -- II. M87 and its Globular
  Clusters

abstract:
  We study the Globular Cluster (GC) system of the nearby elliptical galaxy M87
using the newly available dataset with accurate kinematics (Strader et
al.2011). We find evidence for three distinct sub-populations of GCs in terms
of colours, kinematics and radial profiles. We show that a decomposition into
three populations (blue, intermediate and red GCs) is statistically preferred
to one with two or four populations, and relate them to the stellar profile. We
exploit the sub-populations to derive dynamical constraints on the mass and
Dark Matter (DM) content of M87 out to $\sim100$ kpc. We use a class of global
mass-estimators (from Paper I), obtaining mass measurements at different
locations. M87's DM fraction changes from $\approx$0.2 at the starlight's
effective radius (6 kpc) to $\approx$0.95 at the distance probed by the most
extended, blue GCs (135 kpc). We supplement this with \textit{virial
decompositions}, exploiting the dynamical model to produce a separation into
multiple components. These yield the luminous mass as $5.5^{+1.5}_{-2.0}\times
10^{11}M_\odot$ and the DM within 135 kpc as $8.0^{+1.0}_{-4.0}\times
10^{12}M_\odot.$ The inner DM density behaves as $\rho \sim r^{-\gamma}$ with
$\gamma\approx 1.6$. This is steeper than the cosmologically preferred cusp
$\rho \sim r^{-1},$ providing evidence of DM contraction. Finally, we combine
the GC separation into three sub-populations and the Jeans equations, obtaining
information on the orbits of the GC system. The centrally concentrated red GCs
exhibit tangential anisotropy, consistent with radial-orbit depletion by tidal
shredding. The most extended blue GCs have an isotropic velocity dispersion
tensor in the central parts, which becomes more tangential moving outwards,
consistent with adiabatic contraction of the DM halo.


title: Dynamical Models of Elliptical Galaxies -- I. Simple Methods

abstract:
  We study dynamical models for elliptical galaxies, deriving the projected
kinematic profiles in a form that is valid for general surface-brightness
profiles and (spherical) total mass profiles, without the need for any explicit
deprojection. We then show that an almost flat rotation curve, combined with
modest velocity anisotropy, is already sufficient to recover the kinematic
profiles of nearby ellipticals. As an application, we provide two different
sets of mass estimators for elliptical galaxies, based on either the velocity
dispersion at a specific location near the effective radius, or the
aperture-averaged velocity dispersion. In the large aperture (virial) limit,
mass estimators are naturally independent of anisotropy. The spherical mass
enclosed within the effective radius $R_{\rm e}$ can be estimated as $2.4
R_{\rm e} \langle \sigma^{2}_{\rm p} \rangle/ G$, where $\langle \sigma^2_{\rm
p} \rangle$ is the average of the squared velocity dispersion over a finite
aperture. This formula does not depend on assumptions such as
mass-follows-light, and is a compromise between the cases of small and large
apertures sizes. Its general agreement with results from other methods in the
literature makes it a reliable means to infer masses in the absence of detailed
kinematic information. If on the other hand the velocity dispersion profile is
available, tight mass estimates can be found that are independent of the
mass-model and anisotropy profile (within $\approx$ 10% accuracy). Explicit
formulae are given for small anisotropy, large radii and/or power-law total
densities. Motivated by recent observational claims, we also discuss the issue
of weak homology of elliptical galaxies, emphasizing the interplay between
morphology and orbital structure.


title: The two-point resistance of fan networks

abstract:
  The problem of the two-point resistance in various networks has recently
received considerable attention. Here we consider the problem on a fan-resistor
network, which is a segment of the cobweb network. Using a recently developed
approach, we obtain the exact resistance between two arbitrary nodes on such a
network. As a byproduct, the analysis also delivers the solution of the
spanning tree problem on the fan network.


title:
The Emergent 1.1-1.7 Micron Spectrum of the Exoplanet CoRoT-2b as
  Measured Using the Hubble Space Telescope

abstract:
  We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse
of the transiting very hot Jupiter CoRoT-2b in the 1.1-1.7$\mu$m spectral
region. We find an eclipse depth averaged over this band equal to
$395^{+69}_{-45}$ parts per million, equivalent to a blackbody temperature of
$1788\pm18$K. We study and characterize several WFC3 instrumental effects,
especially the "hook" phenomenon described by Deming et al. (2013). We use data
from several transiting exoplanet systems to find a quantitative relation
between the amplitude of the hook and the exposure level of a given pixel.
Although the uncertainties in this relation are too large to allow us to
develop an empirical correction for our data, our study provides a useful guide
for optimizing exposure levels in future WFC3 observations. We derive the
planet's spectrum using a differential method. The planet-to-star contrast
increases to longer wavelength within the WFC3 bandpass, but without water
absorption or emission to a $3\sigma$ limit of 85 ppm. The slope of the WFC3
spectrum is significantly less than the slope of the best-fit blackbody. We
compare all existing eclipse data for this planet to a blackbody spectrum, and
to spectra from both solar abundance and carbon-rich (C/O=1) models. A
blackbody spectrum is an acceptable fit to the full dataset. Extra continuous
opacity due to clouds or haze, and flattened temperature profiles, are strong
candidates to produce quasi-blackbody spectra, and to account for the amplitude
of the optical eclipses. Our results show ambiguous evidence for a temperature
inversion in this planet.


title:
Observations of "Fresh" and Weathered Surfaces on Asteroid Pairs and
  Their Implications on the Rotational-Fission Mechanism

abstract:
  The rotational-fission of a rubble-pile asteroid can result in an "asteroid
pair", two un-bound asteroids sharing similar orbits. This mechanism might
exposes material that previously had never have been exposed to the weathering
conditions of space. Therefore, the surfaces of asteroid pairs offer the
opportunity to observe non-weathered fresh spectra. We report near-IR
spectroscopic observations of 31 asteroids in pairs. We analyze their spectral
slopes, 1 {\mu}m absorption band, taxonomy, and estimate the time elapsed since
their separation. Analyzing the 19 S-complex objects in our sample, we find two
fresh Q-type asteroids that are the first of their kind to be observed in the
main-belt over the full visible and near-IR range. This solidly demonstrates
that Q-type objects are not limited to the NEA population. The pairs in our
sample present a range of fresh and weathered surfaces with no clear evidence
for a correlation with the ages of the pairs. However, our sample includes old
pairs (1 to 2 My) that present low spectral slopes. This illustrates a
timescale of at least ~2 My before an object develops high spectral slope that
is typical for S-type asteroids.
  We discuss mechanisms that explain the existence of weathered pairs with
young dynamical ages and find that the "secondary fission" model (Jacobson &
Scheeres 2011) is the most robust with our observations since: 1) the secondary
members in our sample present fresh parameters that tend to be fresher than
their weathered primaries; 2) most of the fresh pairs in our sample have low
size ratios between the secondary and the primary; 3) 33% of the primaries in
our sample are fresh, similar to the prediction set by this model; 4) known
satellites orbit two of the pairs in our sample with low size ratio and fresh
surface; 5) there is no correlation between the weathering state and the
primary shape as predicted by other models.


title: Quasi-Particle Theory for the Higgs Amplitude Mode

abstract:
  We present a generalized quasi-particle theory for bosonic lattice systems,
which naturally contains all relevant collective modes, including the Higgs
amplitude in the strongly correlated superfluid. In contrast to Bogoliubov
theory, this non-perturbative method does not rely on a small condensate
depletion and is valid for any interaction strength in three spatial
dimensions. It is based on an expansion around the bosonic Gutzwiller ground
state in terms of appropriately chosen fluctuation operators and lays the
foundation for the description of real-time dynamics in terms of the natural,
weakly interacting quasi-particles. Furthermore, it provides a systematic
framework for efficiently calculating observables beyond the Gutzwiller
approximation and for including external perturbations, as well as higher order
decay and interactions in terms of quasi-particle operators. It allows for the
construction of an alternative path integral approach in terms of
quasi-particle coherent states.


title:
Azimuthal asymmetries in high-energy collisions of protons with
  holographic shockwaves

abstract:
  Large azimuthal quadrupole and octupole asymmetries have recently been found
in p+Pb collisions at the LHC. We argue that these might arise from a
projectile dipole scattering off fluctuations in the target with a size on the
order of the dipole. In a holographic scenario, parity even angular moments
$v_{2n}$ are generated by the real part of the light-like Wilson loop due to
the contribution from the background metric to the Nambu-Goto action. On the
other hand, parity odd moments $v_{2n+1}$ must arise from the imaginary part of
the light-like Wilson loop, which is naturally induced by a fluctuating
Neveu-Schwarz 2-form.


title:
Power density spectra of modes of orbital motion in strongly curved
  spacetime: obtaining the observable signal

abstract:
  High frequency quasi-periodic oscillations (HF QPOs) appear in the X-ray
variability of several accreting low-mass binaries. In a series of works it was
suggested that these QPOs may have connection to inhomogeneities orbiting close
to an inner edge of the accretion disc. In this paper we explore the appearance
of an observable signal generated by small radiating circular hot spots moving
along quasi-elliptic trajectories close to the innermost stable circular orbit
in the Schwarzschild spacetime. Our consideration takes into account the
capabilities of observatories that have been operating in the past two decades
represented by the Rossi X-ray Timing Explorer (RXTE) and the proposed future
instruments represented by the Large Observatory for X-ray Timing (LOFT). For
these purposes we choose such model parameters that lead to lightcurves
comparable to those observed in Galactic black hole sources, in particular the
microquasar GRS 1915+105. We find that when a weak signal corresponding to the
hot-spot Keplerian frequency is around the limits of the RXTE detectability,
the LOFT observations can clearly reveal its first and second harmonics.
Moreover, in some specific situations the radial epicyclic frequency of the
spot can be detected as well. Finally, we also compare the signal produced by
the spots to the signal produced by axisymmetric epicyclic disc-oscillation
modes and discuss the key differences that could be identified via the proposed
future technology. We conclude that the ability to recognize the harmonic
content of the signal can help to distinguish between the different proposed
physical models.


title:
A cosmic web filament revealed in Lyman-alpha emission around a luminous
  high-redshift quasar

abstract:
  Simulations of structure formation in the Universe predict that galaxies are
embedded in a "cosmic web", where the majority of baryons reside as rarefied
and highly ionized gas. This material has been studied for decades in
absorption against background sources, but the sparseness of these inherently
one-dimensional probes preclude direct constraints on the three-dimensional
morphology of the underlying web. Here we report observations of a cosmic web
filament in Lyman-alpha emission, discovered during a survey for cosmic gas
fluorescently "illuminated" by bright quasars at z=2.3. With a projected size
of approximately 460 physical kpc, the Lyman-alpha emission surrounding the
radio-quiet quasar UM287 extends well beyond the virial radius of any plausible
associated dark matter halo. The estimated cold gas mass of the nebula from the
observed emission is at least ten times larger than what is typically found by
cosmological simulations, suggesting that a population of intergalactic gas
clumps with sub-kpc sizes may be missing within current numerical models.


title: Biquaternion formulation of relativistic tensor dynamics

abstract:
  In this paper we show how relativistic tensor dynamics and relativistic
electrodynamics can be formulated in a biquaternion tensor language. The
treatment is restricted to mathematical physics, known facts as the Lorentz
Force Law and the Lagrange Equation are presented in a relatively new
formalism. The goal is to fuse anti-symmetric tensor dynamics, as used for
example in relativistic electrodynamics, and symmetric tensor dynamics, as used
for example in introductions to general relativity, into one single formalism:
a specific kind of biquaternion tensor calculus.


title: Stability of Nonlinear Regime-switching Jump Diffusions

abstract:
  Motivated by networked systems, stochastic control, optimization, and a wide
variety of applications, this work is devoted to systems of switching jump
diffusions. Treating such nonlinear systems, we focus on stability issues.
First asymptotic stability in the large is obtained. Then the study on
exponential p-stability is carried out. Connection between almost surely
exponential stability and exponential p-stability is exploited. Also presented
are smooth-dependence on the initial data. Using the smooth-dependence,
necessary conditions for exponential p-stability are derived. Then criteria for
asymptotic stability in distribution are provided. A couple of examples are
given to illustrate our results.


title:
YASCA: A collective intelligence approach for community detection in
  complex networks

abstract:
  In this paper we present an original approach for community detection in
complex networks. The approach belongs to the family of seed-centric
algorithms. However, instead of expanding communities around selected seeds as
most of existing approaches do, we explore here applying an ensemble clustering
approach to different network partitions derived from ego-centered communities
computed for each selected seed. Ego-centered communities are themselves
computed applying a recently proposed ensemble ranking based approach that
allow to efficiently combine various local modularities used to guide a greedy
optimisation process. Results of first experiments on real world networks for
which a ground truth decomposition into communities are known, argue for the
validity of our approach.


title: The Impact of the Topology on Cascading Failures in Electric Power Grids

abstract:
  Cascading failures are one of the main reasons for blackouts in power
transmission grids. The topology of a power grid, together with its operative
state determine, for the most part, the robustness of the power grid against
cascading failures. Secure electrical power supply requires, together with
careful operation, a robust design of the electrical power grid topology. This
paper investigates the impact of a power grid topology on its robustness
against cascading failures. Currently, the impact of the topology on a grid
robustness is mainly assessed by using purely topological approaches that fail
to capture the essence of electric power flow. This paper proposes a metric,
the effective graph resistance, that relates the topology of a power grid to
its robustness against cascading failures by deliberate attacks, while also
taking the fundamental characteristics of the electric power grid into account
such as power flow allocation according to Kirchoff Laws. Experimental
verification shows that the proposed metric anticipates the grid robustness
accurately. The proposed metric is used to optimize a grid topology for a
higher level of robustness. To demonstrate its applicability, the metric is
applied on the IEEE 118 bus power system to improve its robustness against
cascading failures.


title: The solar chromosphere observed at 1 Hz and 0."2 resolution

abstract:
  We recently reported extremely rapid changes in chromospheric fine structure
observed using the IBIS instrument in the red wing of H alpha. Here, we examine
data obtained during the same observing run (August 7 2010), of a mature active
region NOAA 11094. We analyze more IBIS data including wavelength scans and
data from the Solar Dynamics Observatory, all from within a 30 minute interval.
Using a slab radiative transfer model, we investigate the physical nature of
fibrils in terms of tube-like vs. sheet-like structures. Principal Component
Analysis shows that the very rapid H alpha variations in the line wings depend
mostly on changes of line width and line shift, but for Ca II 854.2 the
variations are dominated by changes in column densities. The tube model must be
rejected for a small but significant class of fibrils undergoing very rapid
changes. If our wing data arise from the same structures leading to "type II
spicules", our analysis calls into question much recent work. Instead the data
do not reject the hypothesis that some fibrils are optical superpositions of
plasma collected into sheets. We review how Parker's theory of tangential
discontinuities naturally leads to plasma collecting into sheets, and show that
the sheet picture is falsifiable. Chromospheric fine structures seem to be
populated by both tubes and sheets. We assess the merits of spectral imaging
versus slit spectroscopy for future studies.


title: Controlled self-assembly of periodic and aperiodic cluster crystals

abstract:
  Soft particles are known to overlap and form stable clusters that
self-assemble into periodic crystalline phases with density-independent lattice
constants. We use molecular dynamics simulations in two dimensions to
demonstrate that, through a judicious design of an isotropic pair potential,
one can control the ordering of the clusters and generate a variety of phases,
including decagonal and dodecagonal quasicrystals. Our results confirm
analytical predictions based on a mean-field approximation, providing insight
into the stabilization of quasicrystals in soft macromolecular systems, and
suggesting a practical approach for their controlled self-assembly in
laboratory realizations using synthesized soft-matter particles.


title:
Near-Optimal Mean-Variance Controls under Two-time-scale Formulations
  and Applications

abstract:
  Although the mean-variance control was initially formulated for financial
portfolio management problems in which one wants to maximize expected return
and control the risk, our motivations also stem from highway vehicle platoon
controls that aim to maximize highway utility while ensuring zero accident.
This paper develops near-optimal mean-variance controls of switching diffusion
systems. To reduce the computational complexity, with motivations from earlier
work on singularly perturbed Markovian systems \cite{SethiZ94,Yin&Zhang,GZB},
we use a two-time-scale formulation to treat the underlying systems, which is
represented by use of a small parameter. As the small parameter goes to 0, we
obtain a limit problem. Using the limit problem as a guide, we construct
controls for the original problem, and show that the control so constructed is
nearly optimal.


title: A Hamiltonian splitting for the Vlasov-Maxwell system

abstract:
  A new splitting is proposed for solving the Vlasov-Maxwell system. This
splitting is based on a decomposition of the Hamiltonian of the Vlasov-Maxwell
system and allows for the construction of arbitrary high order methods by
composition (independent of the specific deterministic method used for the
discretization of the phase space). Moreover, we show that for a spectral
method in space this scheme satisfies Poisson's equation without explicitly
solving it. Finally, we present some examples in the context of the time
evolution of an electromagnetic plasma instability which emphasizes the
excellent behavior of the new splitting compared to methods from the
literature.


title:
Mean-Variance Type Controls Involving a Hidden Markov Chain: Models and
  Numerical Approximation

abstract:
  Motivated by applications arising in networked systems, this work examines
controlled regime-switching systems that stem from a mean-variance formulation.
A main point is that the switching process is a hidden Markov chain. An
additional piece of information, namely, a noisy observation of switching
process corrupted by white noise is available. We focus on minimizing the
variance subject to a fixed terminal expectation. Using the Wonham filter, we
convert the partially observed system to a completely observable one first.
Since closed-form solutions are virtually impossible be obtained, a Markov
chain approximation method is used to devise a computational scheme.
Convergence of the algorithm is obtained. A numerical example is provided to
demonstrate the results.


title:
Asymptotically locally AdS and flat black holes in the presence of an
  electric field in the Horndeski scenario

abstract:
  Asymptotically locally AdS and asymptotically flat black hole solutions are
found for a particular case of the Horndeski action. The action contains the
Einstein-Hilbert term with a cosmological constant, a real scalar field with a
non minimal kinetic coupling given by the Einstein tensor, the minimal kinetic
coupling and the Maxwell term. There is no scalar potential. The solution has
two integration constants related with the mass and the electric charge. The
solution is given for all dimensions. A new class of asymptotically locally
flat spherically symmetric black holes is found when the minimal kinetic
coupling vanishes and the cosmological constant is present. In this case we get
a solution which represents an electric Universe. The electric field at
infinity is only supported by $\Lambda$. When the cosmological constant
vanishes the black hole is asymptotically flat.