title:
Frequency Stabilization of a 369 nm Diode Laser by Nonlinear
  Spectroscopy of Ytterbium Ions in a Discharge

abstract:
  We demonstrate stabilisation of an ultraviolet diode laser via Doppler free
spectroscopy of Ytterbium ions in a discharge. Our technique employs
polarization spectroscopy, which produces a natural dispersive lineshape whose
zero-crossing is largely immune to environmental drifts, making this signal an
ideal absolute frequency reference for Yb$^+$ ion trapping experiments. We
stabilise an external-cavity diode laser near 369 nm for cooling Yb$^+$ ions,
using amplitude-modulated polarisation spectroscopy and a commercial PID
feedback system. We achieve stable, low-drift locking with a standard deviation
of measured laser frequency ~400 kHz over 10 minutes, limited by the
instantaneous linewidth of the diode laser. These results and the simplicity of
our optical setup makes our approach attractive for stabilization of laser
sources in atomic-physics applications.


title: Sunquakes: helioseismic response to solar flares

abstract:
  Sunquakes observed in the form of expanding wave ripples on the surface of
the Sun during solar flares represent packets of acoustic waves excited by
flare impacts and traveling through the solar interior. The excitation impacts
strongly correlate with the impulsive flare phase, and are caused by the energy
and momentum transported from the energy release sites. The flare energy is
released in the form of energetic particles, waves, mass motions, and
radiation. However, the exact mechanism of the localized hydrodynamic impacts
which generate sunquakes is unknown. Solving the problem of the sunquake
mechanism will substantially improve our understanding of the flare physics. In
addition, sunquakes offer a unique opportunity for studying the interaction of
acoustic waves with magnetic fields and flows in flaring active regions, and
for developing new approaches to helioseismic acoustic tomography.


title: Magnetic frustration in iridium spinel compound CuIr$_2$S$_4$

abstract:
  We demonstrate via a muon spin rotation experiment that the electronic ground
state of the iridium spinel compound, CuIr$_2$S$_4$, is not the presumed
spin-singlet state but a novel paramagnetic state, showing a quasistatic spin
glass-like magnetism below ~100 K. Considering the earlier indication that
IrS$_6$ octahedra exhibit dimerization associated with the metal-to-insulator
transition below 230 K, the present result suggests that a strong spin-orbit
interaction may be playing an important role in determining the ground state
that accompanies magnetic frustration.


title:
Constraining ${\cal N}=1$ supergravity inflation with non-minimal
  K\"ahler operators using $\delta N$ formalism

abstract:
  In this paper I provide a general framework based on $\delta N$ formalism to
study the features of unavoidable higher dimensional non-renormalizable
K\"ahler operators for ${\cal N}=1$ supergravity (SUGRA) during primordial
inflation from the combined constraint on non-Gaussianity, sound speed and CMB
dipolar asymmetry as obtained from the recent Planck data. In particular I
study the nonlinear evolution of cosmological perturbations on large scales
which enables us to compute the curvature perturbation, $\zeta$, without
solving the exact perturbed field equations. Further I compute the non-Gaussian
parameters $f_{NL}$, $\tau_{NL}$ and $g_{NL}$ for local type of
non-Gaussianities and CMB dipolar asymmetry parameter, $ A_{CMB}$, using the
$\delta N$ formalism for a generic class of sub-Planckian models induced by the
Hubble-induced corrections for a minimal supersymmetric D-flat direction where
inflation occurs at the point of inflection within the visible sector. Hence by
using multi parameter scan I constrain the non-minimal couplings appearing in
non-renormalizable K\"ahler operators within, ${\cal O}(1)$, for the speed of
sound, $0.02\leq c_s\leq 1$, and tensor to scalar, $10^{-22} \leq r_{\star}
\leq 0.12$. Finally applying all of these constraints I will fix the lower as
well as the upper bound of the non-Gaussian parameters within, ${\cal
O}(1-5)\leq f_{NL}\leq 8.5$, ${\cal O}(75-150)\leq\tau_{NL}\leq 2800$ and
${\cal O}(17.4-34.7)\leq g_{NL}\leq 648.2$, and CMB dipolar asymmetry parameter
within the range, $0.05\leq A_{CMB}\leq 0.09$.


title:
A Survey on an Effective Defense Mechanism against Reactive Jamming
  Attacks in WSN

abstract:
  A Wireless Sensor Network (WSN) is a self-configure network of sensor nodes
communicate among themselves using radio signals and deployed in quantity to
sense, monitor and to understand the physical world. A jammer is an entity
which interferes with the physical transmission and reception of wireless
communications. Reactive jamming attack is a major security problem in the
wireless sensor network. The reactive jammer stays quiet when the channel is
idle. The jammer starts transmitting a radio signal as soon as it senses
activity on the channel. The reactive jammer nodes will be deactivated by
identifying all the trigger nodes, at the same time a jammer node is localized
by exploiting the changes in the neighbor nodes. The affected node can be
identified, by analyzing the changes in its communication range, compared to
its neighbors. The paper proposes a survey on trigger node identification and a
detailed survey on techniques to identify trigger nodes and highly concentrated
on the reactive jammer.


title:
An Ensemble Kushner-Stratonovich (EnKS) Nonlinear Filter: Additive
  Particle Updates in Non-Iterative and Iterative Forms

abstract:
  Despite the cheap availability of computing resources enabling faster Monte
Carlo simulations, the potential benefits of particle filtering in revealing
accurate statistical information on the imprecisely known model parameters or
modeling errors of dynamical systems, based on limited time series data, have
not been quite realized. A major numerical bottleneck precipitating this
under-performance, especially for higher dimensional systems, is the
progressive particle impoverishment owing to weight collapse and the aim of the
current work is to address this problem by replacing weight-based updates
through additive ones. Thus, in the context of nonlinear filtering problems, a
novel additive particle update scheme, in its non-iterative and iterative
forms, is proposed based on manipulations of the innovation integral in the
governing Kushner-Stratonovich equation. Numerical evidence for the
identification of nonlinear and large dimensional dynamical systems indicates a
substantively superior performance of the non- iterative version of the EnKS
vis-\`a-vis most existing filters. The costlier iterative version, though
conceptually elegant, mostly appears to effect a marginal improvement in the
reconstruction accuracy over its non-iterative counterpart. Prominent in the
reported numerical comparisons are variants of the Ensemble Kalman Filter
(EnKF) that also use additive updates, albeit with many inherent limitations of
a Kalman filter.


title:
Taylor particle dispersion during transition to fully developed
  two-dimensional turbulence

abstract:
  We report new measurements of single particle dispersion in turbulent
two-dimensional (2D) flows. Laboratory experiments in electromagnetically
driven and Faraday wave driven turbulence reveal a transition from weakly
dispersing superdiffusive regime to strongly dispersing Brownian diffusion as
the flow energy is increased in a broad range. The transition to fully
developed 2D turbulence is characterized by the topological changes in the
fluid particle trajectories and the development of self-similar diffusion. The
degree of 2D turbulence development can be quantified by a parameter describing
the deviation of single particle dispersion from the Taylor dispersion.


title: Option Pricing, Historical Volatility and Tail Risks

abstract:
  We revisit the problem of pricing options with historical volatility
estimators. We do this in the context of a generalized GARCH model with
multiple time scales and asymmetry. It is argued that the reason for the
observed volatility risk premium is tail risk aversion. We parametrize such
risk aversion in terms of three coefficients: convexity, skew and kurtosis risk
premium. We propose that option prices under the real-world measure are not
martingales, but that their drift is governed by such tail risk premia. We then
derive a fair-pricing equation for options and show that the solutions can be
written in terms of a stochastic volatility model in continuous time and under
a martingale probability measure. This gives a precise connection between the
pricing and real-world probability measures, which cannot be obtained using
Girsanov Theorem. We find that the convexity risk premium, not only shifts the
overall implied volatility level, but also changes its term structure.
Moreover, the skew risk premium makes the skewness of the volatility smile
steeper than a pure historical estimate. We derive analytical formulas for
certain implied moments using the Bergomi-Guyon expansion. This allows for very
fast calibrations of the models. We show examples of a particular model which
can reproduce the observed SPX volatility surface using very few parameters.


title: The T7 flavor symmetry in 3-3-1 model with neutral leptons

abstract:
  We construct a 3-3-1 model based on non-Abelian discrete symmetry $T_7$
responsible for the fermion masses. Neutrinos get masses from only anti-sextets
which are in triplets $\underline{3}$ and $\underline{3}^*$ under $T_7$. The
flavor mixing patterns and mass splitting are obtained without perturbation.
The tribimaximal form obtained with the breaking $T_7 \rightarrow Z_3$ in
charged lepton sector and both $T_7 \rightarrow Z_3$ and $Z_3 \rightarrow
\{\mathrm{Identity}\}$ must be taken place in neutrino sector but only apart in
breakings $Z_3 \rightarrow \{\mathrm{Identity}\}$ (without contribution of
$\si'$), and the upper bound on neutrino mass $\sum_{i=1}^3m_i$ at the level is
presented. The Dirac CP violation phase $\delta$ is predicted to either
  $\frac{\pi}{2}$ or $\frac{3\pi}{2}$ which is maximal CP violation. From the
Dirac CP violation phase we obtain the relation between Euler's angles which is
consistent with the experimental in PDG 2012. On the other hand, the realistic
lepton mixing can be obtained if both the direction for breakings $T_7
\rightarrow Z_3$ and $Z_3 \rightarrow \{\mathrm{Identity}\}$ are taken place in
neutrino sectors. The CKM matrix is the identity matrix at the tree-level.


title: Incremental classification using Feature Tree

abstract:
  In recent years, stream data have become an immensely growing area of
research for the database, computer science and data mining communities. Stream
data is an ordered sequence of instances. In many applications of data stream
mining data can be read only once or a small number of times using limited
computing and storage capabilities. Some of the issues occurred in classifying
stream data that have significant impact in algorithm development are size of
database, online streaming, high dimensionality and concept drift. The concept
drift occurs when the properties of the historical data and target variable
change over time abruptly in such a case that the predictions will become
inaccurate as time passes. In this paper the framework of incremental
classification is proposed to solve the issues for the classification of stream
data. The Trie structure based incremental feature tree, Trie structure based
incremental FP (Frequent Pattern) growth tree and tree based incremental
classification algorithm are introduced in the proposed framework.


title: In-Memory Database Systems - A Paradigm Shift

abstract:
  In today world, organizations like Google, Yahoo, Amazon, Facebook etc. are
facing drastic increase in data. This leads to the problem of capturing,
storing, managing and analyzing terabytes or petabytes of data, stored in
multiple formats, from different internal and external sources. Moreover, new
applications scenarios like weather forecasting, trading, artificial
intelligence etc. need huge data processing in real time. These requirements
exceed the processing capacity of traditional on-disk database management
systems to manage this data and to give speedy real time results. Therefore,
data management needs new solutions for coping with the challenges of data
volumes and processing data in real-time. An in-memory database system (IMDS)
is a latest breed of database management system which is becoming answer to
above challenges with other supporting technologies. IMDS is capable to process
massive data distinctly faster. This paper explores IMDS approach and its
associated design issues and challenges. It also investigates some famous
commercial and open-source IMDS solutions available in the market.


title:
Efficient method for localized functions using domain transformation and
  Fourier sine series

abstract:
  An efficient approach to handle localized states by using spectral methods
(SM) in one and three dimensions is presented. The method consists of
transformation of the infinite domain to the bounded domain in $(0, \pi)$ and
using the Fourier sine series as a set of basis functions for the SM. It is
shown that with an appropriate choice of transformation functions, this method
manages to preserve the good properties of original SMs; more precisely, superb
computational efficiency when high level of accuracy is necessary. This is made
possible by analytically exploiting the properties of the transformation
function and the Fourier sine series. An especially important property of this
approach is the possibility of calculating the Hartree energy very efficiently.
This is done by exploiting the positive properties of the sine series as a
basis set and conducting an extinctive part of the calculations analytically.
We illustrate the efficiency of this method and implement it to solve the
Poisson's and Helmholtz equations in both one and three dimensions. The
efficiency of the method is verified through a comparison to recently published
results for both one and three dimensional problems.


title: Lattice structure of torsion classes for hereditary artin algebras

abstract:
  Let A be a connected hereditary artin algebra. We show that the set of
functorially finite torsion classes of A-modules is a lattice if and only if A
is either representation-finite (thus a Dynkin algebra) or A has only two
simple modules. For the case of A being the path algebra of a quiver, this
result has recently been established by Iyama-Reiten-Thomas-Todorov and our
proof follows closely their considerations.


title: Long-term evolution of broken wakefields in finite radius plasmas

abstract:
  A novel effect of fast heating and charging a finite-radius plasma is
discovered in the context of plasma wakefield acceleration. As the plasma wave
breaks, the most of its energy is transferred to plasma electrons which create
strong charge-separation electric field and azimuthal magnetic field around the
plasma. The slowly varying field structure is preserved for hundreds of
wakefield periods and contains (together with hot electrons) up to 80% of the
initial wakefield energy.


title: Crystal image analysis using $2D$ synchrosqueezed transforms

abstract:
  We propose efficient algorithms based on a band-limited version of 2D
synchrosqueezed transforms to extract mesoscopic and microscopic information
from atomic crystal images. The methods analyze atomic crystal images as an
assemblage of non-overlapping segments of 2D general intrinsic mode type
functions, which are superpositions of non-linear wave-like components. In
particular, crystal defects are interpreted as the irregularity of local
energy; crystal rotations are described as the angle deviation of local wave
vectors from their references; the gradient of a crystal elastic deformation
can be obtained by a linear system generated by local wave vectors. Several
numerical examples of synthetic and real crystal images are provided to
illustrate the efficiency, robustness, and reliability of our methods.


title: Localized epidemic detection in networks with overwhelming noise

abstract:
  We consider the problem of detecting an epidemic in a population where
individual diagnoses are extremely noisy. The motivation for this problem is
the plethora of examples (influenza strains in humans, or computer viruses in
smartphones, etc.) where reliable diagnoses are scarce, but noisy data
plentiful. In flu/phone-viruses, exceedingly few infected people/phones are
professionally diagnosed (only a small fraction go to a doctor) but less
reliable secondary signatures (e.g., people staying home, or
greater-than-typical upload activity) are more readily available. These
secondary data are often plagued by unreliability: many people with the flu do
not stay home, and many people that stay home do not have the flu. This paper
identifies the precise regime where knowledge of the contact network enables
finding the needle in the haystack: we provide a distributed, efficient and
robust algorithm that can correctly identify the existence of a spreading
epidemic from highly unreliable local data. Our algorithm requires only
local-neighbor knowledge of this graph, and in a broad array of settings that
we describe, succeeds even when false negatives and false positives make up an
overwhelming fraction of the data available. Our results show it succeeds in
the presence of partial information about the contact network, and also when
there is not a single "patient zero", but rather many (hundreds, in our
examples) of initial patient-zeroes, spread across the graph.


title:
Relativistic coupled cluster calculations on hyperfine structures and
  electromagnetic transition amplitudes of In III

abstract:
  Hyperfine constants and anomalies of ground as well as few low lying excited
states of $^{113,115,117}$In III are studied with highly correlated
relativistic coupled-cluster theory. The ground state hyperfine splitting of
$^{115}$In III is estimated to be 106.8 GHz. A shift of almost 1.9 GHz of the
above frequency has been calculated due to modified nuclear dipole moment. This
splitting result shows its applicability as communication band and frequency
standards at $10^{-11}$ sec. Correlations study of hyperfine constants
indicates a few distinct features of many-body effects in the wave-functions in
and near the nuclear region of this ion. Astrophysically important forbidden
transition amplitudes are estimated for the first time in the literature to our
knowledge. The calculated oscillator strengths of few allowed transitions are
compared with recent experimental and theoretical results wherever available.


title: Exactly solvable extended potentials in arbitrary dimensions

abstract:
  We apply a simple transformation method to construct a set of new exactly
solvable potentials (ESP) which gives rise to bound state solution of
$D$-dimensional Schr\"odinger equation. The important property of such exactly
solvable quantum systems is that their normalized eigenfunctions can be written
in terms of recently introduced exceptional orthogonal polynomials (EOP).


title:
Photo-thermoelectric and photoelectric contributions to light detection
  in metal-graphene-metal photodetectors

abstract:
  Graphene's high mobility and Fermi velocity, combined with its constant light
absorption in the visible to far-infrared range, make it an ideal material to
fabricate high-speed and ultra-broadband photodetectors. However, the precise
mechanism of photodetection is still debated. Here, we report wavelength and
polarization dependent measurements of metal-graphene-metal photodetectors.
This allows us to quantify and control the relative contributions of both
photo-thermo- and photoelectric effects, both contributing to the overall
photoresponse. This paves the way for a more efficient photodetector design for
ultra-fast operating speeds.


title:
Statistical-Computational Tradeoffs in Planted Problems and Submatrix
  Localization with a Growing Number of Clusters and Submatrices

abstract:
  We consider two closely related problems: planted clustering and submatrix
localization. The planted clustering problem assumes that a random graph is
generated based on some underlying clusters of the nodes; the task is to
recover these clusters given the graph. The submatrix localization problem
concerns locating hidden submatrices with elevated means inside a large
real-valued random matrix. Of particular interest is the setting where the
number of clusters/submatrices is allowed to grow unbounded with the problem
size. These formulations cover several classical models such as planted clique,
planted densest subgraph, planted partition, planted coloring, and stochastic
block model, which are widely used for studying community detection and
clustering/bi-clustering.
  For both problems, we show that the space of the model parameters
(cluster/submatrix size, cluster density, and submatrix mean) can be
partitioned into four disjoint regions corresponding to decreasing statistical
and computational complexities: (1) the \emph{impossible} regime, where all
algorithms fail; (2) the \emph{hard} regime, where the computationally
expensive Maximum Likelihood Estimator (MLE) succeeds; (3) the \emph{easy}
regime, where the polynomial-time convexified MLE succeeds; (4) the
\emph{simple} regime, where a simple counting/thresholding procedure succeeds.
Moreover, we show that each of these algorithms provably fails in the previous
harder regimes.
  Our theorems establish the minimax recovery limit, which are tight up to
constants and hold with a growing number of clusters/submatrices, and provide a
stronger performance guarantee than previously known for polynomial-time
algorithms. Our study demonstrates the tradeoffs between statistical and
computational considerations, and suggests that the minimax recovery limit may
not be achievable by polynomial-time algorithms.


title: Optimal implementations for reliable circadian clocks

abstract:
  Circadian rhythms are acquired through evolution to increase the chances for
survival through synchronizing with the daylight cycle. Reliable
synchronization is realized through two trade-off properties: regularity to
keep time precisely, and entrainability to synchronize the internal time with
daylight. We found by using a phase model with multiple inputs that achieving
the maximal limit of regularity and entrainability entails many inherent
features of the circadian mechanism. At the molecular level, we demonstrate the
role sharing of two light inputs, phase advance and delay, as is well observed
in mammals. At the behavioral level, the optimal phase-response curve
inevitably contains a dead zone, a time during which light pulses neither
advance nor delay the clock. We reproduce the results of phase-controlling
experiments entrained by two types of periodic light pulses. Our results
indicate that circadian clocks are designed optimally for reliable clockwork
through evolution.


title:
Influence of the variations of potential on autolocalization of the
  surface electrons over helium in the conditions of quasi - one-dimensionality

abstract:
  The feature of interaction electrons with neutral matter attracts large
attention of physicists many directions. The exchange interaction in particular
leads to creating of bubbles - spherical cavities with electron in center. Good
object for such study is system of surface electrons formed over surface of
dielectric with small permittivity. Investigation of the autolocalization of SE
on liquid helium surface attracts high attention, because system is the
extremely clear and easily governed. Bubbles have small mobility relatively of
free electrons and that is used for monitoring of the transition process. As
has recently been investigated the quasi-one-dimensional electrons over liquid
helium form the autolocalized states at smaller gas density in compared to 3D
and 2D situations. The process significantly depends from a substrate and its
quality. The autolocalization of one-dimensional electrons in a gas phase over
liquid helium covering a substrate at both situations with or without the
potential variations is theme of present study. The features of conductivity in
presence of potential variations the authors explain by both the dynamic
processes of changing the subsystem energy at appear or disappear electron
autolocalization and by thermo-insulation of electron subsystem from
thermostat.


title:
Vers une interface pour l enrichissement des requetes en arabe dans un
  systeme de recherche d information

abstract:
  This presentation focuses on the automatic expansion of Arabic request using
morphological analyzer and Arabic Wordnet. The expanded request is sent to
Google.


title:
Bourbaki Seminar 1081 : Min-max methods and the Willmore conjecture,
  after Fernando Cod\'a Marques and Andr\'e Arroja Neves

abstract:
  Two years ago, F.C. Marques and A.A. Neves implemented, in the framework of
closed rectifiable 2-dimensional currents of the 3-dimensional sphere, a
min-max method in geometric measure theory due to F. Almgren and J. Pitts.
Using this approach they succeeded in proving that the famous Clifford torus
minimizes the area among all closed minimal surfaces of non-zero genus in
$S^3$. Another spectacular consequence of their work is to provide a proof of
the Willmore conjecture. The goal of this talk is to discuss first the general
framework of these two theorems of Marques and Neves. We shall then present the
structures and some key details of their proofs. We will then address the scope
of this remarkable contribution to the calculus of variations on surfaces in a
3-dimensional space.


title:
On the Convergence and Summability of double Walsh-Fourier series of
  functions of bounded generalized variation

abstract:
  The convergence of partial sums and Ces\'aro means of negative order of
double Walsh-Fourier series of functions of bounded \ generalized variation is
investigated.


title:
Unicity of graded covers of the Category $\mathcal O$ of
  Bernstein-Gelfand-Gelfand

abstract:
  We show that the standard graded cover of the well-known category $\mathcal
O$ of Bernstein-Gelfand-Gelfand can be characterized by its compatibility with
the action of the center of the enveloping algebra.


title:
Thermal response of double-layered metal films after ultrashort pulsed
  laser irradiation: the role of nonthermal electron dynamics

abstract:
  The thermal response of a Cu-Ti double-layered film is investigated after
laser irradiation with ultrashort pulses (pulse duration {\tau}p=50fs, 800nm
laser wavelength) in submelting conditions by including the influence of
nonthermal electrons. A revised two-temperature model is employed to account
for the contribution of nonthermal electron distribution while the variation of
the optical properties of the material during the laser beam irradiation is
also incorporated into the model. Theoretical results can provide significant
insight into the physical mechanism that characterize electron dynamics and can
facilitate production of controllable ultra-high strength Cu-Ti alloys with
promising applications.

categories: cond-mat.mtrl-sci cond-mat.mes-hall physics.comp-ph physics.optics


title:
On the Validity of the Effective Field Theory for Dark Matter Searches
  at the LHC, Part II: Complete Analysis for the s-channel

abstract:
  We generalize in several directions our recent analysis of the limitations to
the use of the effective field theory approach to study dark matter at the LHC.
Firstly, we study the full list of operators connecting fermion DM to quarks
and gluons, corresponding to integrating out a heavy mediator in the
$s$-channel; secondly, we provide analytical results for the validity of the
EFT description for both $\sqrt{s}=8$ {\rm TeV} and $14$ {\rm TeV}; thirdly, we
make use of a MonteCarlo event generator approach to assess the validity of our
analytical conclusions. We apply our results to revisit the current collider
bounds on the ultraviolet cut-off scale of the effective field theory and show
that these bounds are weakened once the validity conditions of the effective
field theory are imposed.


title:
Scattering mechanisms in textured FeGe thin films: magnetoresistance and
  the anomalous Hall effect

abstract:
  A textured thin film of FeGe was grown by magnetron sputtering with a
helimagnetic ordering temperature of TN = 276 +/- 2 K. From 5 K to room
temperature a variety of scattering processes contribute towards the overall
longitudinal and Hall resistivities. These were studied by combining
magnetometry and magnetotransport measurements. The high-field
magnetoresistance (MR) displays three clear temperature regimes: Lorentz force
MR dominates at low temperatures, above T ~ 80 K scattering from spin-waves
predominates, whilst finally for T > 200 K scattering from fluctuating local
moments describes the MR. At low fields, where the magnetisation is no longer
technically saturated, we find a scaling of magnetoresistance with the square
of the magnetisation, indicating that the MR due to the unwinding of spins in
the conical phase arises from a similar mechanism to that in magnetic domain
walls. This MR is only visible up to a temperature of about 200 K. No features
can be found in the temperature or field dependence of the longitudinal
resistivity that belie the presence of the underlying magnetic phase transition
at TN: the marked changes in behavior are at much lower temperatures. The
anomalous Hall effect has a dramatic temperature dependence in which the
anomalous Hall resistivity scales quadratically with the longitudinal
resistivity: comparison with anomalous Hall scaling theory shows that our
system is in the intrinsic 'moderately dirty' regime. Lastly, we find evidence
of a topological Hall effect of size 100 ~Ohm cm.


title:
Conservation laws protect dynamic spin correlations from decay: Limited
  role of integrability in the central spin model

abstract:
  Mazur's inequality renders statements about persistent correlations possible.
We generalize it in a convenient form applicable to any set of linearly
independent constants of motion. This approach is used to show rigorously that
a fraction of the initial spin correlations persists indefinitely in the
isotropic central spin model unless the average coupling vanishes. The central
spin model describes a major mechanism of decoherence in a large class of
potential realizations of quantum bits. Thus the derived results contribute
significantly to the understanding of the preservation of coherence. We will
show that persisting quantum correlations are not linked to the integrability
of the model, but caused by a finite operator overlap with a finite set of
constants of motion.


title:
Interaction quench in a Lieb-Liniger model and the KPZ equation with
  flat initial conditions

abstract:
  Recent exact solutions of the 1D Kardar-Parisi-Zhang equation make use of the
1D integrable Lieb-Liniger model of interacting bosons. For flat initial
conditions, it requires the knowledge of the overlap between the uniform state
and arbitrary exact Bethe eigenstates. The same quantity is also central in the
study of the quantum quench from a 1D non-interacting Bose-Einstein condensate
upon turning interactions. We compare recent advances in both domains, i.e. our
previous exact solution, and a new conjecture by De Nardis et al.. This leads
to new exact results and conjectures for both the quantum quench and the KPZ
problem.

categories: cond-mat.dis-nn cond-mat.quant-gas cond-mat.stat-mech math-ph math.MP


title: Molecular Split-Ring Resonators Based on Metal String Complexes

abstract:
  Metal string complexes or extended metal atom chains (EMACs) belong to a
family of molecules that consist of a linear chain of directly bonded metal
atoms embraced helically by four multidentate organic ligands. These four
organic ligands are usually made up of repeating pyridyl units,
single-nitrogen-substituted heterocyclic annulenes, bridged by independent
amido groups. Here, in this paper, we show that these heterocyclic annulenes
are actually nanoscale molecular split-ring resonators (SRRs) that can exhibit
simultaneous negative electric permittivity and magnetic permeability in the
UV-Vis region. Moreover, a monolayer of self-assembled EMACs is a periodic
array of molecular SRRs which can be considered as a negative refractive index
material. In the molecular scale, where the quantum-size effect is significant,
we apply the tight-binding method to obtain the frequency-dependent
permittivity and permeability of these molecular SRRs with their tensorial
properties carefully considered.

categories: physics.optics cond-mat.mes-hall cond-mat.mtrl-sci quant-ph


title: A Chandra Grating Observation of the Dusty Wolf-Rayet Star WR48a

abstract:
  We present results of a Chandra High Energy Transmission Grating (HETG)
observation of the carbon-rich Wolf-Rayet (WR) star WR48a. These are the first
high-resolution spectra of this object in X-rays. Blue-shifted centroids of the
spectral lines of about -360 km/s and line widths of 1000 - 1500 km/s (FWHM)
were deduced from the analysis of the line profiles of strong emission lines.
The forbidden line of Si XIII is strong and not suppressed, indicating that the
rarefied 10-30 MK plasma forms far from strong sources of far-UV emission, most
likely in a wind collision zone. Global spectral modeling showed that the X-ray
spectrum of WR48a suffered higher absorption in the October 2012 Chandra
observation compared to a previous January 2008 XMM-Newton observation. The
emission measure of the hot plasma in WR48a decreased by a factor ~ 3 over the
same period of time. The most likely physical picture that emerges from the
analysis of the available X-ray data is that of colliding stellar winds in a
wide binary system with an elliptical orbit. We propose that the unseen
secondary star in the system is another WR star or perhaps a luminous blue
variable.


title:
Crossing Stocks and the Positive Grassmannian I: The Geometry behind
  Stock Market

abstract:
  It seems to be very unlikely that all relevant information in the stock
market could be fully encoded in a geometrical shape. Still,the present paper
will reveal the geometry behind the stock market transactions. The prices of
market index (DJIA) stock components are arranged in ascending order from the
smallest one in the left to the highest in the right. In such arrangement, as
stock prices changes due to daily market quotations, it could be noticed that
the price of a certain stock get over /under the price of a neighbor stock.
These stocks are crossing. Arranged this way, the diagram of successive stock
crossings is nothing else than a permutation diagram. From this point on the
financial and combinatorial concepts are netted together to build a bridge
connecting the stock market to a beautiful geometrical object that will be
called stock market polytope. The stock market polytope is associated with the
remarkable structure of positive Grassmannian . This procedure makes all the
relevant information about the stock market encoded in the geometrical shape of
the stock market polytope more readable.


title: Covariant phase space, constraints, gauge and the Peierls formula

abstract:
  It is well known that both the symplectic structure and the Poisson brackets
of classical field theory can be constructed directly from the Lagrangian in a
covariant way, without passing through the non-covariant canonical Hamiltonian
formalism. This is true even in the presence of constraints and gauge
symmetries. These constructions go under the names of the covariant phase space
formalism and the Peierls bracket. We review both of them, paying more careful
attention, than usual, to the precise mathematical hypotheses that they
require, illustrating them in examples. Also an extensive historical overview
of the development of these constructions is provided. The novel aspect of our
presentation is a significant expansion and generalization of an elegant and
quite recent argument by Forger & Romero showing the equivalence between the
resulting symplectic and Poisson structures without passing through the
canonical Hamiltonian formalism as an intermediary. We generalize it to cover
theories with constraints and gauge symmetries and formulate precise sufficient
conditions under which the argument holds. These conditions include a local
condition on the equations of motion that we call hyperbolizability, and some
global conditions of cohomological nature. The details of our presentation may
shed some light on subtle questions related to the Poisson structure of gauge
theories and their quantization.


title: A Hierarchical fuzzy controller for a biped robot

abstract:
  In this paper the investigation is placed on the hierarchic neuro-fuzzy
systems as a possible solution for biped control. An hierarchic controller for
biped is presented, it includes several sub-controllers and the whole structure
is generated using the adaptive Neuro-fuzzy method. The proposed hierarchic
system focus on the key role that the centre of mass position plays in biped
robotics, the system sub-controllers generate their outputs taken into
consideration the position of that key point.


title:
Classification of "Real" Bloch-bundles: Topological quantum systems of
  type AI

abstract:
  We provide a classification of type AI topological quantum systems in
dimension d=1,2,3,4 which is based on the equivariant homotopy properties of
"Real" vector bundles. This allows us to produce a fine classification able to
take care also of the non stable regime which is usually not accessible via
K-theoretic techniques. We prove the absence of non-trivial phases for one-band
AI free or periodic quantum particle systems in each spatial dimension by
inspecting the second equivariant cohomology group which classifies "Real" line
bundles. We also show that the classification of "Real" line bundles suffices
for the complete classification of AI topological quantum systems in dimension
d<4. In dimension d=4 the determination of different topological phases (for
free or periodic systems) is fixed by the second "Real Chern class which
provides an even labeling identifiable with the degree of a suitable map.
Finally, we provide explicit realizations of non trivial 4-dimensional free
models for each given topological degree.


title:
Constructing Performance Models for Dense Linear Algebra Algorithms on
  Cray XE Systems

abstract:
  Hiding or minimizing the communication cost is key in order to obtain good
performance on large-scale systems. While communication overlapping attempts to
hide communications cost, 2.5D communication avoiding algorithms improve
performance scalability by reducing the volume of data transfers at the cost of
extra memory usage. Both approaches can be used together or separately and the
best choice depends on the machine, the algorithm and the problem size. Thus,
the development of performance models is crucial to determine the best option
for each scenario. In this paper, we present a methodology for constructing
performance models for parallel numerical routines on Cray XE systems. Our
models use portable benchmarks that measure computational cost and network
characteristics, as well as performance degradation caused by simultaneous
accesses to the network. We validate our methodology by constructing the
performance models for the 2D and 2.5D approaches, with and without
overlapping, of two matrix multiplication algorithms (Cannon's and SUMMA),
triangular solve (TRSM) and Cholesky. We compare the estimations provided by
these models with the experimental results using up to 24,576 cores of a Cray
XE6 system and predict the performance of the algorithms on larger systems.
Results prove that the estimations significantly improve when taking into
account network contention.


title: Compactness and compactifications in generalized topology

abstract:
  A generalized topology in a set $X$ is a collection $\text{Cov}_X$ of
families of subsets of $X$ such that the triple $(X,\bigcup
\text{Cov}_X,\text{Cov}_X)$ is a generalized topological space in the sense of
Delfs and Knebusch. In this work, notions of topological and admissible
compactness of generalized topologies are introduced to begin and investigate a
theory of compactifications, in particular, of Wallman type in the category of
weakly normal generalized topological spaces. Among other facts, we prove in ZF
that the ultrafilter theorem (in abbreviation UFT) holds if and only if all
Wallman extensions of every weakly normal generalized topological space are
compact. In consequence, we develop the theory of compactifications in ZF+UFT
when it is not necessary to use AC, while ZF is not enough.


title:
Towards High Performance Computing (Hpc) Through Parallel Programming
  Paradigms and Their Principles

abstract:
  Nowadays, we are to find out solutions to huge computing problems very
rapidly. It brings the idea of parallel computing in which several machines or
processors work cooperatively for computational tasks. In the past decades,
there are a lot of variations in perceiving the importance of parallelism in
computing machines. And it is observed that the parallel computing is a
superior solution to many of the computing limitations like speed and density;
non-recurring and high cost; and power consumption and heat dissipation etc.
The commercial multiprocessors have emerged with lower prices than the
mainframe machines and supercomputers machines. In this article the high
performance computing (HPC) through parallel programming paradigms (PPPs) are
discussed with their constructs and design approaches.


title: Market impact as anticipation of the order flow imbalance

abstract:
  In this paper, we assume that the permanent market impact of metaorders is
linear and that the price is a martingale. Those two hypotheses enable us to
derive the evolution of the price from the dynamics of the flow of market
orders. For example, if the market order flow is assumed to follow a nearly
unstable Hawkes process, we retrieve the apparent long memory of the flow
together with a power law impact function which is consistent with the
celebrated square root law. We also link the long memory exponent of the sign
of market orders with the impact function exponent. One of the originalities of
our approach is that our results are derived without assuming that market
participants are able to detect the beginning of metaorders.


title:
High-performance ferroelectric memory based on fully patterned tunnel
  junctions

abstract:
  In tunnel junctions with ferroelectric barriers, switching the polarization
direction modifies the electrostatic potential profile and the associated
average tunnel barrier height. This results in strong changes of the tunnel
transmission and associated resistance. The information readout in
ferroelectric tunnel junctions (FTJs) is thus resistive and non-destructive,
which is an advantage compared to the case of conventional ferroelectric
memories (FeRAMs). Initially, endurance limitation (i.e. fatigue) was the main
factor hampering the industrialization of FeRAMs. Systematic investigations of
switching dynamics for various ferroelectric and electrode materials have
resolved this issue, with endurance now reaching $10^{14}$ cycles. Here we
investigate data retention and endurance in fully patterned submicron
Co/BiFeO$_3$/Ca$_{0.96}$Ce$_{0.04}$MnO$_3$ FTJs. We report good reproducibility
with high resistance contrasts and extend the maximum reported endurance of
FTJs by three orders of magnitude ($4\times10^6$ cycles). Our results indicate
that here fatigue is not limited by a decrease of the polarization or an
increase of the leakage but rather by domain wall pinning. We propose
directions to access extreme and intermediate resistance states more reliably
and further strengthen the potential of FTJs for non-volatile memory
applications.


title: A solution of the puzzling symbiotic X-ray system 4U 1700+24

abstract:
  A circumstellar corona is proposed for a strange quark-cluster star during an
accretion phase, that could be essential to understand the observations of the
puzzling symbiotic X-ray system, 4U 1700+24. The state of cold matter at
supranuclear density is still an important matter of debate, and one of the
certain consequences of strange star as the nature of pulsars is the self-bound
on surface which makes extremely low-mass compact objects unavoidable. In
principle, both the redshifted O VIII Ly-$\alpha$ emission line and the change
of the black-body radiation area could be understood naturally if 4U 1700+24 is
a low-mass quark-cluster star in case of wind-accretion.


title:
Kondo impurity between superconducting and metallic reservoir: the flow
  equation approach

abstract:
  It is well established that a correlated quantum impurity embedded in a
metallic host can form the many-body Kondo state with itinerant electrons due
to the effective antiferromagnetic coupling. Such effect is manifested
spectroscopically by a narrow Abrikosov-Suhl peak appearing at the Fermi level
below a characteristic temperature T_K. Recent experiments using nanoscopic
heterojunctions where the correlated quantum impurities (dots) are coupled to
superconducting reservoirs revealed that the Kondo-type correlations are
substantially weaker because: i) the single-particle states of superconductors
are depleted around the Fermi level and ii) the on-dot pairing (proximity
effect) competes with the spin ordering. Within the Anderson impurity scenario
we study here influence of such induced on-dot paring on the exchange
interaction adopting the continuous unitary transformation, which goes beyond
the perturbative framework. Our analytical and numerical results show strong
detrimental influence of the electron pairing on the effective
antiferromagnetic coupling thereby suppressing the Kondo temperature in
agreement with the experimental observations.


title: Parity and symmetry in intersection and ordinary cohomology

abstract:
  In this paper, we show that the Galois representations provided by
$\ell$-adic cohomology of proper smooth varieties, and more generally by
$\ell$-adic intersection cohomology of proper varieties, over any field, are
orthogonal or symplectic according to the degree. We deduce this from a
preservation result of orthogonal and symplectic pure perverse sheaves by
proper direct image. We show moreover that the subgroup of the Grothendieck
group generated by orthogonal pure perverse sheaves of even weights and
symplectic pure perverse sheaves of odd weights are preserved by Grothendieck's
six operations. Over a finite field, we deduce parity and symmetry results for
Jordan blocks appearing in the Frobenius action on intersection cohomology of
proper varieties, and virtual parity results for the Frobenius action on
ordinary cohomology of arbitrary varieties.


title:
Thermodynamic relations for entropy and temperature of multi-horizons
  black holes

abstract:
  We present some entropy and temperature relations of multi-horizons, even
including the "virtual" horizon. These relations are related to product,
division and sum of entropy and temperature of multi-horizons. We obtain the
additional thermodynamic relations of both static and rotating black holes in
three and four dimensional (A)dS spacetime. Especially, a new dimensionless,
charges-independence and $T_+S_+=T_-S_-$ like relation is presented. This
relation does not depend on the mass, electric charge, angular momentum and
cosmological constant, as it is always a constant. These relations lead us to
get some interesting thermodynamic bound of entropy and temperature, including
the Penrose inequality which is the first geometrical inequality of black
holes. Besides, based on these new relations, one can obtain the first law of
thermodynamics and Smarr relation for all horizons of black hole.


title:
A new scheme for color confinement due to violation of the non-Abelian
  Bianchi identities

abstract:
  A new scheme for color confinement in QCD due to violation of the non-Abelian
Bianchi identities is discussed. The violation of the non-Abelian Bianchi
identities (VNABI) $J_{\mu}$ is equal to Abelian-like monopole currents
$k_{\mu}$ defined by the violation of the Abelian-like Bianchi identities.
Although VNABI is an adjoint operator satisfying the covariant conservation
rule $D_{\mu}J_{\mu}=0$, it gives us, at the same time, the Abelian-like
conservation rule $\partial_{\mu}J_{\mu}=0$. The Abelian-like conservation rule
$\partial_{\mu}J_{\mu}=0$ is also gauge-covariant. There are $N^2-1$ conserved
magnetic charges in the case of color $SU(N)$. The charge of each component of
VNABI is quantized \`{a} la Dirac. VNABI satisfying the Dirac quantization
condition could be defined on lattice as lattice Abelian-like monopole currents
without any gauge-fixing. Previous studies of the Abelian-like monopoles
$k_{\mu}$ on lattice show that non-Abelian color confinement could be
understood by the Abelian-like dual Meissner effect due to condensation of
VNABI.


title:
Aspects of reduction and transformation of Lagrangian systems with
  symmetry

abstract:
  This paper contains results on geometric Routh reduction and it is a
continuation of a previous paper where a new class of transformations is
introduced between Lagrangian systems obtained after Routh reduction. In
general, these reduced Lagrangian systems have magnetic force terms and are
singular in the sense that the Lagrangian does not depend on some velocity
components. The main purpose of this paper is to show that the Routh reduction
process itself is entirely captured by the application of such a new
transformation on the initial Lagrangian system with symmetry.


title: Mnemonical Body Shortcuts: Gestural Interface for Mobile Devices

abstract:
  Mobile devices' user interfaces are still quite similar to traditional
interfaces offered by desktop computers, but those can be highly problematic
when used in a mobile context. Human gesture recognition in mobile interaction
appears as an important area to provide suitable on-the-move usability. We
present a body space based approach to improve mobile device interaction and
mobile performance, which we named as Mnemonical Body Shortcuts. The human body
is presented as a rich repository of meaningful relations which are always
available to interact with. These body-based gestures allow the user to
naturally interact with mobile devices with no movement limitations.
Preliminary studies using Radio Frequency Identification (RFID) technology were
performed, validating Mnemonical Body Shortcuts as an appropriate new mobile
interaction mechanism. Following those studies, we developed inertial sensing
prototypes using an accelerometer, ending in the construction and user testing
of a gestural interface for mobile devices capable of properly recognizing
Mnemonical Body Shortcuts and also providing suitable user control mechanisms
and audio, visual and haptic feedback.


title: Conformal Newton-Hooke symmetry of Pais-Uhlenbeck oscillator

abstract:
  It is demonstrated that the Pais-Uhlenbeck oscillator in arbitrary dimension
enjoys the l-conformal Newton-Hooke symmetry provided frequencies of
oscillation form the arithmetic sequence omega_k=(2k-1) omega_1, where
k=1,...,n, and l is the half-integer (2n-1)/2. The model is shown to be
maximally superintegrable. A link to n decoupled isotropic oscillators is
discussed and an interplay between the l-conformal Newton-Hooke symmetry and
symmetries characterizing each individual isotropic oscillator is analyzed.


title:
Phase transitions and sample complexity in Bayes-optimal matrix
  factorization

abstract:
  We analyse the matrix factorization problem. Given a noisy measurement of a
product of two matrices, the problem is to estimate back the original matrices.
It arises in many applications such as dictionary learning, blind matrix
calibration, sparse principal component analysis, blind source separation, low
rank matrix completion, robust principal component analysis or factor analysis.
It is also important in machine learning: unsupervised representation learning
can often be studied through matrix factorization. We use the tools of
statistical mechanics - the cavity and replica methods - to analyze the
achievability and computational tractability of the inference problems in the
setting of Bayes-optimal inference, which amounts to assuming that the two
matrices have random independent elements generated from some known
distribution, and this information is available to the inference algorithm. In
this setting, we compute the minimal mean-squared-error achievable in principle
in any computational time, and the error that can be achieved by an efficient
approximate message passing algorithm. The computation is based on the
asymptotic state-evolution analysis of the algorithm. The performance that our
analysis predicts, both in terms of the achieved mean-squared-error, and in
terms of sample complexity, is extremely promising and motivating for a further
development of the algorithm.

categories: cs.NA cond-mat.stat-mech cs.IT cs.LG math.IT stat.ML


title: Three-level superadiabatic quantum driving

abstract:
  The superadiabatic quantum driving, producing a perfect adiabatic transfer on
a given Hamitonian by introducing an additional Hamiltonian, is theoretically
analysed for transfers within a three-level system. Our starting point is the
stimulated Raman adiabatic passage, realized through different schemes of laser
pulses. We determine the superadiabatic correction for each scheme. The
fidelity, robustness and transfer time of all the superadiabatic transfer
schemes are discussed. We derive that all superadiabatic corrections are based
on a $\pi$- (or near-$\pi$)-area pulse coupling between the initial and final
states. The benefits in the protocol robustness overcome the difficulties
associated to the actual implementation of the three-level superadiabatic
transfer.


title: On super form factors of half-BPS operators in N=4 super Yang-Mills

abstract:
  We compute form factors of half-BPS operators in N=4 super Yang-Mills dual to
massive Kaluza-Klein modes in supergravity. These are appropriate
supersymmetrisations T_k of the scalar operators Tr(\phi^k) for any k, which
for k=2 give the chiral part of the stress-tensor multiplet operator. Using
harmonic superspace, we derive simple Ward identities for these form factors,
which we then compute perturbatively at tree level and one loop. We propose a
novel on-shell recursion relation which links form factors with different
numbers of fields. Using this, we conjecture a general formula for the n-point
MHV form factors of T_k for arbitrary k and n. Finally, we use supersymmetric
generalised unitarity to derive compact expressions for all one-loop MHV form
factors of T_k in terms of one-loop triangles and finite two-mass easy box
functions.


title: Exciton-polariton wakefields in semiconductor microcavities

abstract:
  We consider the excitation of polariton wakefields due to a propagating
source in a semiconductor micro cavity. We show that two kinds of wakes are
possible, depending on the constituents fraction (either exciton or photon) of
the polariton wavefunction. The nature of the wakefields (pure excitonic or
polaritonic) can be controled by changing the speed of propagation of the
external pump. This process could be used as a diagnostic for the internal
parameters of the microcavity.


title: Volume fluctuations of random analytic varieties in the unit ball

abstract:
  Given a Gaussian analytic function $f_L$ of intesity $L$ in the unit ball of
$\mathbb C^n$, $n\geq 2$, consider its (random) zero variety $Z(f_L)$. We study
the variance of the $(n-1)$-dimensional volume of $Z(f_L)$ inside a
pseudo-hyperbolic ball of radius $r$. We first express this variance as an
integral of a positive function in the unit disk. Then we study its asymptotic
behaviour as $L\to\infty$ and as $r\to 1^{-}$. Both the results and the proofs
generalise to the ball those given by Jeremiah Buckley for the unit disk.


title: Demkov-Kunike model in cold molecule formation

abstract:
  We study the dynamics of cold molecule formation via photo- or
magneto-association of quantum degenerate atomic gases for the case when the
field configuration is defined by the quasi-linear level crossing Demkov-Kunike
model, which is characterized by a bell-shaped pulse and finite variation of
the frequency detuning. We generalize the approach developed for the
Landau-Zener model and propose a cubic polynomial equation for the asymptotic
transition probability at infinity applicable in the large detuning regime of
the interaction process. The proposed approximation applies to all values of
the Rabi frequency; hence, it presents a unified description of previously
noticed weak, moderate, and strong interaction limits of the fast sweep regime.
This cubic equation for the transition probability provides improvement of
previous results by an order of the magnitude.


title: Zero-two law for cosine families

abstract:
  For $\left(C(t)\right)_{t \geq 0}$ being a strongly continuous cosine family
on a Banach space, we show that the estimate $\limsup_{t\to 0^{+}}\|C(t) - I\|
<2$ implies that $C(t)$ converges to $I$ in the operator norm. This implication
has become known as the zero-two law. We further prove that the stronger
assumption of $\sup_{t\geq0}\|C(t)-I\|<2$ yields that $C(t)=I$ for all
$t\geq0$. Additionally, we derive alternative proofs for similar results for
$C_{0}$-semigroups.


title:
Fisher Information and Exponential Families Parametrized by a Segment of
  Means

abstract:
  We consider natural and general exponential families $(Q_m)_{m\in M}$ on
$\mathbb{R}^d$ parametrized by the means. We study the submodels $(Q_{\theta
m_1+(1-\theta)m_2})_{\theta\in[0,1]}$ parametrized by a segment in the means
domain, mainly from the point of view of the Fisher information. Such a
parametrization allows for a parsimonious model and is particularly useful in
practical situations when hesitating between two parameters $m_1$ and $m_2$.
The most interesting examples are obtained when $\mathbb{R}^d$ is a linear
space of matrices, in particular for Gaussian and Wishart models.


title:
Magneto-elastic couplings in the distorted diamond-chain compound
  azurite

abstract:
  We present results of ultrasonic measurements on a single crystal of the
distorted diamond-chain compound azurite Cu$_3$(CO$_3$)$_2$(OH)$_2$. Pronounced
elastic anomalies are observed in the temperature dependence of the
longitudinal elastic mode $c_{22}$ which can be assigned to the relevant
magnetic interactions in the system and their couplings to the lattice degrees
of freedom. From a quantitative analysis of the magnetic contribution to
$c_{22}$ the magneto-elastic coupling $G$ = $\partial J_2$/$\partial
\epsilon_b$ can be determined, where $J_2$ is the intra-dimer coupling constant
and $\epsilon_b$ the strain along the intra-chain $b$ axis. We find an
exceptionally large coupling constant of $|G| \sim ($3650 $\pm$ 150) K
highlighting an extraordinarily strong sensitivity of $J_2$ against changes of
the $b$-axis lattice parameter. These results are complemented by measurements
of the hydrostatic pressure dependence of $J_2$ by means of thermal expansion
and magnetic susceptibility measurements performed both at ambient and finite
hydrostatic pressure. We propose that a structural peculiarity of this
compound, in which Cu$_2$O$_6$ dimer units are incorporated in an unusually
stretched manner, is responsible for the anomalously large magneto-elastic
coupling.


title:
In-line extraction of an ultra-stable frequency signal over an optical
  fiber link

abstract:
  We demonstrate in-line extraction of an ultra-stable frequency signal over an
optical link of 92-km of installed telecommunication fibers, following the
proposition of G. Grosche in 2010. We show that the residual frequency noise at
the extraction end is noticeably below that at the main link output when the
extraction is near the input end, as expected from a simple model of the noise
compensation. We obtain relative frequency instabilities, expressed as
overlapping Allan deviation, of 8x10-16 at 1 s averaging time and a few 10-19
at 1 day. These results are at the state-of-the-art for a link using urban
telecommunication fibers. We also propose an improved scheme which delivers an
ultra-stable signal of higher power, in order to feed a secondary link. In-line
extraction opens the way to a broad distribution of an ultra-stable frequency
reference, enabling a wide range of applications beyond metrology.


title: Convergence of logarithmic means of Multiple Walsh-Fourier series

abstract:
  The maximal Orlicz spaces such that the mixed logarithmic means of multiple
Walsh-Fourier series for the functions from these spaces converge in measure
and in norm are found.


title: Backtracking algorithms for service selection

abstract:
  In this paper, we explore the automation of services' compositions. We focus
on the service selection problem. In the formulation that we consider, the
problem's inputs are constituted by a behavioral composition whose abstract
services must be bound to concrete ones. The objective is to find the binding
that optimizes the {\it utility} of the composition under some services level
agreements. We propose a complete solution. Firstly, we show that the service
selection problem can be mapped onto a Constraint Satisfaction Problem (CSP).
The benefit of this mapping is that the large know-how in the resolution of the
CSP can be used for the service selection problem. Among the existing
techniques for solving CSP, we consider the backtracking. Our second
contribution is to propose various backtracking-based algorithms for the
service selection problem. The proposed variants are inspired by existing
heuristics for the CSP. We analyze the runtime gain of our framework over an
intuitive resolution based on exhaustive search. Our last contribution is an
experimental evaluation in which we demonstrate that there is an effective gain
in using backtracking instead of some comparable approaches. The experiments
also show that our proposal can be used for finding in real time, optimal
solutions on small and medium services' compositions.


title:
Feasibility-Seeking and Superiorization Algorithms Applied to Inverse
  Treatment Planning in Radiation Therapy

abstract:
  We apply the recently proposed superiorization methodology (SM) to the
inverse planning problem in radiation therapy. The inverse planning problem is
represented here as a constrained minimization problem of the total variation
(TV) of the intensity vector over a large system of linear two-sided
inequalities. The SM can be viewed conceptually as lying between
feasibility-seeking for the constraints and full-fledged constrained
minimization of the objective function subject to these constraints. It is
based on the discovery that many feasibility-seeking algorithms (of the
projection methods variety) are perturbation-resilient, and can be proactively
steered toward a feasible solution of the constraints with a reduced, thus
superiorized, but not necessarily minimal, objective function value.


title:
Higher order transmission resonances in above-barrier reflection of
  ultra-cold atoms

abstract:
  The reflectionless transmission resonances in above-barrier reflection of
Bose-Einstein condensates by the Rosen-Morse potential are considered using the
mean field Gross-Pitaevskii approach. Applying an exact third order nonlinear
differential equation obeyed by the condensate's density, the exact solution of
the problem for the first resonance is derived. It is shown that in the
nonlinear case the total transmission is possible for positive potential
heights, i.e., for potential barriers. Further, it is shown that an appropriate
approximation for higher-order resonances can be constructed using a limit
solution of the equation for the density written as a root of a polynomial
equation of the third degree. Using this limit function and the solution for
the first resonance, a simple approximation for the shift of the nonlinear
resonance potential's depth from the corresponding linear resonance's position
is constructed for higher order resonances. The result is written as a linear
function of the resonance order. This behavior notably differs from the case of
the rectangular barrier for which the nonlinear shift is approximately constant
for all the resonance orders.


title:
A non-singular transformation whose spectrum has Lebesgue component of
  multiplicity one

abstract:
  In this note we give an example of an ergodic non-singular map whose unitary
operator admits a Lebesgue component of multiplicity one in its spectrum.


title:
Solution to a parabolic differential equation in Hilbert space via
  Feynman formula - parts I and II

abstract:
  A parabolic partial differential equation $u'_t(t,x)=Lu(t,x)$ is considered,
where $L$ is a linear second-order differential operator with time-independent
coefficients, which may depend on $x$. We assume that the spatial coordinate
$x$ belongs to a finite- or infinite-dimensional real separable Hilbert space
$H$.
  Assuming the existence of a strongly continuous resolving semigroup for this
equation, we construct a representation of this semigroup by a Feynman formula,
i.e. we write it in the form of the limit of a multiple integral over $H$ as
the multiplicity of the integral tends to infinity. This representation gives a
unique solution to the Cauchy problem in the uniform closure of the set of
smooth cylindrical functions on $H$. Moreover, this solution depends
continuously on the initial condition. In the case where the coefficient of the
first-derivative term in $L$ vanishes we prove that the strongly continuous
resolving semigroup exists (this implies the existence of the unique solution
to the Cauchy problem in the class mentioned above) and that the solution to
the Cauchy problem depends continuously on the coefficients of the equation.


title: Study the function of building blocks in SHA Family

abstract:
  In this paper we analyse the role of some of the building blocks in SHA-256.
We show that the disturbance correction strategy is applicable to the SHA-256
architecture and we prove that functions $\Sigma$, $\sigma$ are vital for the
security of SHA-256 by showing that for a variant without them it is possible
to find collisions with complexity 2 64 hash operations. As a step towards an
analysis of the full function, we present the results of our experiments on
Hamming weights of expanded messages for different variants of the message
expansion and show that there exist low-weight expanded messages for
XOR-linearised variants.


title:
Matter wave propagation above a step potential within the
  cubic-nonlinear Schr\"odinger equation

abstract:
  We analyze the matter wave transmission above a step potential within the
framework of the cubic-nonlinear Schr\"odinger equation. We present a
comprehensive analysis of the corresponding stationary problem based on an
exact second-order nonlinear differential equation for the probability density.
The exact solution of the problem in terms of the Jacobi elliptic sn-function
is presented and analyzed. Qualitatively distinct types of wave propagation
picture are classified depending on the input parameters of the system.
Analyzing the 2D space of involved dimensionless parameters, the nonlinearity
and the reflecting potential's height/depth given in the units of the chemical
potential, we show that the region of the parameters that does not sustain
restricted solutions is given by a closed curve consisting of a segment of an
elliptic curve and two line intervals. We show that there exists a specific
singular point, belonging to the elliptic curve, which causes a jump from one
evolution scenario to another one. The position of this point is determined and
the peculiarities of the evolution scenarios (oscillatory, non-oscillatory and
diverging) for all the allowed regions of involved parameters are described and
analyzed in detail.


title:
Hole transport and valence band dispersion law in a HgTe quantum well
  with normal energy spectrum

abstract:
  The results of an experimental study of the energy spectrum of the valence
band in a HgTe quantum well of width d<6.3 nm with normal spectrum in the
presence of a strong spin-orbit splitting are reported. The analysis of the
temperature, magnetic field and gate voltage dependences of the Shubnikov-de
Haas oscillations allows us to restore the energy spectrum of the two valence
band branches, which are split by the spin-orbit interaction. The comparison
with the theoretical calculation shows that a six-band kP theory well describes
all the experimental data in the vicinity of the top of the valence band.


title: Localization sequences for logarithmic topological Hochschild homology

abstract:
  We study the logarithmic topological Hochschild homology of ring spectra with
logarithmic structures and establish localization sequences for this theory.
Our results apply, for example, to connective covers of periodic ring spectra
like real and complex topological K-theory.


title: New relations for the derivative of the confluent Heun function

abstract:
  The cases when the equation for the derivative of the confluent Heun function
has only three singularities (in general, the equation has four such points)
are examined. It is shown that this occurs only in three specific cases.
Further, it is shown that in all these three cases this equation is reduced to
some confluent Heun equation with changed parameters. This means that in these
cases the derivative of the confluent Heun function is expressed via some other
confluent Heun function. The analysis of the obtained relations shows that they
can be useful for the construction of some exact solutions of the confluent
Heun equation for specific values of involved parameters. Several examples of
such cases are presented; and for all the cases the final solutions in terms of
simpler special functions are explicitly presented. In addition, it is shown
that in the mentioned three cases, the solution can be expanded as a series in
terms of generalized hypergeometric functions of Goursat or Clausen.


title:
Equality of diffusion-limited chronoamperometric currents to equal area
  spherical and cubic nanoparticles on a supporting electrode surface

abstract:
  We computationally investigate the chronoamperometric current response of
spherical and cubic particles on a supporting insulating surface. By using the
method of finite differences and random walk simulations, we can show that both
systems exhibit identical responses on all time scales if their exposed surface
areas are equal. This result enables a simple and computationally effcient
method to treat certain spherical geometries in random walk based noise
investigations.


title:
Low-frequency High-resolution Radio Observations of the TeV-emitting
  Blazar SHBLJ001355.9-185406

abstract:
  In the framework of the unification scheme of radio-loud active galactic
nuclei, BL Lac objects and quasars are the beamed end-on counterparts of
low-power (FRI) and high-power (FRII) radio galaxies, respectively. Some BL
Lacs have been found to possess the FRII-type large-scale radio morphology,
suggesting that the parent population of BL Lacs is a mixture of low- and
high-power radio galaxies. This seems to apply only to `low frequency-peaked'
BL Lacs, since all the `high frequency-peaked' BL Lacs studied so far were
shown to host exclusively the FRI-type radio jets. While analyzing the NVSS
survey maps of the TeV detected BL Lacs, we have however discovered that the
high frequency-peaked object SHBL J001355.9-185406 is associated uniquely with
the one-sided, arcmin-scale, and edge-brightened jet/lobe-like feature
extending to the south-west from the blazar core. In order to investigate in
detail the large-scale morphology of SHBL J001355.9-185406, we have performed
low-frequency and high-resolution observations of the source at 156, 259 and
629 MHz using the Giant Metrewave Radio Telescope. Our analysis indicates that
no diffuse arcmin-scale emission is present around the unresolved blazar core,
and that the arcmin-scale structure seen on the NVSS map breaks into three
distinct features unrelated to the blazar, but instead associated with
background AGN. The upper limits for the extended radio halo around the
TeV-emitting BL Lac object SHBL J001355.9-185406 read as < 10% - 1% at
$156-629$ MHz. The fact that the integrated radio spectrum of the unresolved
blazar core is flat down to 156 MHz indicates that a self-similar character of
the jet in the source holds up to relatively large distances from the jet base.


title:
Complete-return spectrum for a generalized Rosen-Zener two-state
  term-crossing model

abstract:
  The general semiclassical time-dependent two-state problem is considered for
a specific field configuration referred to as the generalized Rosen-Zener
model. This is a rich family of pulse amplitude- and phase-modulation functions
describing both non-crossing and term-crossing models with one or two crossing
points. The model includes the original constant-detuning non-crossing
Rosen-Zener model as a particular case. We show that the governing system of
equations is reduced to a confluent Heun equation. When inspecting the
conditions for returning the system to the initial state at the end of the
interaction with the field, we reformulate the problem as an eigenvalue problem
for the peak Rabi frequency and apply the Rayleigh-Schr\"odinger perturbation
theory. Further, we develop a generalized approach for finding the higher-order
approximations, which is applicable for the whole variation region of the
involved input parameters of the system. We examine the general surface in the
3D space of input parameters, which defines the position of the n-th order
return-resonance, and show that the section of the general surface is
accurately approximated by an ellipse. We find a highly accurate analytic
description through the zeros of a Kummer confluent hypergeometric function.
From the point of view of the generality, the analytical description of
mentioned curve for the whole variation range of all involved parameters is the
main result of the present paper.


title: Embeddings of (proper) power graphs of finite groups

abstract:
  The (proper) power graph of a group is a graph whose vertex set is the set of
all (nontrivial) elements of the group and two distinct vertices are adjacent
if one is a power of the other. Various kinds of planarity of (proper) power
graphs of groups are discussed.


title: Anomalous critical fields in quantum critical superconductors

abstract:
  Fluctuations around an antiferromagnetic quantum critical point (QCP) are
believed to lead to unconventional superconductivity and in some cases to
high-temperature superconductivity. However, the exact mechanism by which this
occurs remains poorly understood. The iron-pnictide superconductor
BaFe$_2$(As$_{1-x}$P$_x$)$_2$ is perhaps the clearest example to date of a high
temperature quantum critical superconductor, and so it is a particularly
suitable system in which to study how the quantum critical fluctuations affect
the superconducting state. Here we show that the proximity of the QCP yields
unexpected anomalies in the superconducting critical fields. We find that both
the lower and upper critical fields strongly violate the expectations from the
conventional theory taking into account the observed mass enhancement near the
QCP. These anomalous behaviours of the critical fields imply that the energy of
superconducting vortices is enhanced, possibly due to a microscopic mixing of
antiferromagnetism and superconductivity, suggesting that a highly unusual
vortex state is realised in quantum critical superconductors.


title: UCAT: Ubiquitous Context Awareness Tools for The Blind

abstract:
  Visually impaired people are often confronted with new environments and they
find themselves face to face with an innumerous amount of difficulties when
facing these environments. Having to surpass and deal with these difficulties
that arise with their condition is something that we can help diminish. They
are one sense down when trying to understand their surrounding environments and
gather information about what is happening around them. Nowadays, mobile
devices present significant computing and technological capacity which has been
increasing to the point where it is very common for most people to have access
to a device with Bluetooth, GPS, Wi-Fi, and both high processing and storage
capacities. This allows us to think of applications that can do so much to help
people with difficulties. In the particular case of blind people, the lack of
visual information can be bypassed with other contextual information retrieved
by their own personal devices. Our goal is to provide information to blind
users, be able to give them information about the context that surrounds them.
We wanted to provide the blind users with the tools to create information and
be able to share this information between each other, information about people,
locations or objects. Our approach was to split the project into a data and
information gathering phase where we did our field search and interviewed and
elaborated on how is the situation of environment perception for blind users,
followed by a technical phase where we implement a system based on the first
stage. Our results gathered from both the collecting phase and our implementing
phase showed that there is potential to use these tools in the blind community
and that they welcome the possibilities and horizons that it opens them.


title: Synchronized Switching in a Josephson Junction Crystal

abstract:
  We consider a superconducting coplanar waveguide resonator where the central
conductor is interrupted by a series of uniformly spaced Josephson junctions.
The device forms an extended medium that is optically nonlinear on the single
photon level with normal modes that inherit the full nonlinearity of the
junctions but are nonetheless accessible via the resonator ports. For specific
plasma frequencies of the junctions a set of normal modes clusters in a narrow
band and eventually become entirely degenerate. Upon increasing the intensity
of a red detuned drive on these modes, we observe a sharp and synchronized
switching from low occupation quantum states to high occupation classical
fields, accompanied by a pronounced jump from low to high output intensity.


title:
Fifteen classes of solutions of the quantum two-state problem in terms
  of the confluent Heun function

abstract:
  We derive 15 classes of time-dependent two-state models solvable in terms of
the confluent Heun functions. These classes extend over all the known families
of three- and two-parametric models solvable in terms of the hypergeometric and
the confluent hypergeometric functions to more general four-parametric classes
involving three-parametric detuning modulation functions. In the case of
constant detuning the field configurations describe excitations of two-state
quantum systems by symmetric or asymmetric pulses of controllable width and
edge-steepness. The classes that provide constant detuning pulses of finite
area are identified and the factors controlling the corresponding pulse shapes
are discussed. The positions and the heights of the peaks are mostly defined by
two of the three parameters of the detuning modulation function, while the
pulse width is mainly controlled by the third one, the constant term. The
classes suggest numerous symmetric and asymmetric chirped pulses and a variety
of models with two crossings of the frequency resonance. We discuss the
excitation of a two-level atom by a pulse of Lorentzian shape with a detuning
providing one or two crossings of the resonance. We derive closed form
solutions for particular curves in the 3D space of the involved parameters
which compose the complete return spectrum of the considered two-state quantum
system.


title: A Survey on Spatial Co-location Patterns Discovery from Spatial Datasets

abstract:
  Spatial data mining or Knowledge discovery in spatial database is the
extraction of implicit knowledge, spatial relations and spatial patterns that
are not explicitly stored in databases. Co-location patterns discovery is the
process of finding the subsets of features that are frequently located together
in the same geographic area. In this paper, we discuss the different approaches
like Rule based approach, Join-less approach, Partial Join approach and
Constraint neighborhood based approach for finding co-location patterns.


title:
Low fine tuning in the MSSM with higgsino dark matter and unification
  constraints

abstract:
  We examine the issue of fine tuning in the MSSM with GUT-scale boundary
conditions. We identify specific unification patterns and mass relations that
can lead to a significant lowering of the fine tuning due to gauginos, scalars,
and the \mu\ parameter, relative to the simplest unification conditions. We
focus on a phenomenologically interesting region that is favored by the Higgs
mass and the relic density where the dark matter is a nearly pure higgsino with
mass given by \mu~1 TeV while the scalars and gauginos have masses in the
multi-TeV regime. There, we find that the fine tuning can be reduced to the
level of a few percent. Despite the gluino mass in the ballpark of 2 TeV,
resulting mass spectra will be hard to explore at the LHC, but good prospects
for detection come from dark matter direct detection experiments. Finally, we
demonstrate with a specific example how the conditions and mass relations
giving low fine tuning can originate in the context of supergravity and Grand
Unified Theories.


title: Critical configurations for a system of semidegenerate fermions

abstract:
  We study an isothermal system of semi-degenerate self-gravitating fermions in
general relativity. Such systems present mass density solutions with a central
degenerate core, a plateau and a tail which follows a power law behaviour
$r^{-2}$. The different solutions are governed by the free parameters of the
model: the degeneracy and temperature parameters at the center, and the
particle mass $m$. We then analyze in detail the free parameter space for a
fixed $m$ in the keV regime, by studying the one-parameter sequences of
equilibrium configurations up to the critical point, which is represented by
the maximum in a central density ($\rho_0$) Vs. core mass ($M_c$) diagram. We
show that for fully degenerate cores, the known expression for the critical
core mass $M_c^{cr}\propto m_{pl}^3/m^2$ is obtained, while instead for low
degenerate cores, the critical core mass increases showing the temperature
effects in a non linear way. The main result of this work is that when applying
this theory to model the distribution of dark matter in galaxies from the very
center up to the outer halos, we do not find any critical core-halo
configuration of self-gravitating fermions, which be able to explain the super
massive dark object in their centers together with an outer halo
simultaneously.


title:
Time-dependent level crossing models solvable in terms of the confluent
  Heun functions

abstract:
  We discuss the level-crossing field configurations for which the quantum
time-dependent two-state problem is solvable in terms of the confluent Heun
functions. We show that these configurations belong to fifteen four-parametric
families of models that generalize all the known 3- and 2-parametric families
for which the problem is solvable in terms of the Gauss hypergeometric and the
Kummer confluent hypergeometric functions. Analyzing the general case of
variable Rabi frequency and frequency detuning we mention that the most notable
features of the models provided by the derived classes are due to the extra
constant term in the detuning modulation function. Due to this term the classes
suggest numerous symmetric or asymmetric chirped pulses and a variety of models
with two crossings of the frequency resonance. The latter models are generated
by both real and complex transformations of the independent variable. In
general, the resulting detuning functions are asymmetric, the asymmetry being
controlled by the parameters of the detuning modulation function. In some
cases, however, the asymmetry may be additionally caused by the amplitude
modulation function. We present an example of the latter possibility and
additionally mention a constant amplitude model with periodically repeated
resonance-crossings. Finally, we discuss the excitation of a two-level atom by
a pulse of Lorentzian shape with a detuning providing one or two crossings of
the resonance. Using a series expansion of the solution of the confluent Heun
equation in terms of the Kummer hypergeometric functions we derive particular
closed form solutions of the two-state problem for this field configuration.
The particular sets of the involved parameters for which these solutions are
obtained define curves in the 3D space of the involved parameters belonging to
the complete return spectrum of the considered two-state quantum system.


title:
An Estimation Method of Measuring Image Quality for Compressed Images of
  Human Face

abstract:
  Nowadays digital image compression and decompression techniques are very much
important. So our aim is to calculate the quality of face and other regions of
the compressed image with respect to the original image. Image segmentation is
typically used to locate objects and boundaries (lines, curves etc.)in images.
After segmentation the image is changed into something which is more meaningful
to analyze. Using Universal Image Quality Index(Q),Structural Similarity
Index(SSIM) and Gradient-based Structural Similarity Index(G-SSIM) it can be
shown that face region is less compressed than any other region of the image.


title: Twisted Hilbert modular L-functions and spectral theory

abstract:
  These are notes for four lectures given at the 2010 CIMPA Research School
"Automorphic Forms and L-functions" in Weihai, China. The lectures focused on a
Burgess-like subconvex bound for twisted Hilbert modular L-functions published
jointly with Valentin Blomer in the same year. They discussed the proof in some
detail, especially how spectral theory can be used to estimate the relevant
shifted convolution sums efficiently. They also discussed briefly an
application for the number of representations by a totally positive ternary
quadratic form over a totally real number field.


title: Bernstein-Sato polynomials and test modules in positive characteristic

abstract:
  In analogy with the complex analytic case, Musta\c{t}\u{a} constructed (a
family of) Bernstein-Sato polynomials for the structure sheaf $\mathcal{O}_X$
and a hypersurface $(f=0)$ in $X$, where $X$ is a regular variety over an
$F$-finite field of positive characteristic (see arxiv:0711.3794). He shows
that the suitably interpreted zeros of his Bernstein-Sato polynomials
correspond to the jumping numbers of the test ideal filtration $\tau(X,f^t)$.
In the present paper we generalize Musta\c{t}\u{a}'s construction replacing
$\mathcal{O}_X$ by an arbitrary $F$-regular Cartier module $M$ on $X$ and show
an analogous correspondence of the zeros of our Bernstein-Sato polynomials with
the jumping numbers of the associated filtration of test modules $\tau(M,f^t)$
provided that $f$ is a non-zero divisor on $M$.


title:
Self-adjointness of unbounded tridiagonal operators and spectra of their
  finite truncations

abstract:
  This paper addresses two different but related questions regarding an
unbounded symmetric tridiagonal operator: its self-adjointness and the
approximation of its spectrum by the eigenvalues of its finite truncations. The
sufficient conditions given in both cases improve and generalize previously
known results. It turns out that, not only self-adjointness helps to study
limit points of eigenvalues of truncated operators, but the analysis of such
limit points is a key help to prove self-adjointness. Several examples show the
advantages of these new results compared with previous ones. Besides, an
application to the theory of continued fractions is pointed out.


title: High Velocity Compact Clouds in the Sagittarius C Region

abstract:
  We report the detection of extremely broad emission toward two molecular
clumps in the Galactic central molecular zone. We have mapped the Sagittarius C
complex ($-0^\circ.61 < l < -0^\circ.27$, $-0^\circ.29 < b < 0^\circ.04$) in
the HCN $J$ = 4--3, $\mathrm{^{13}CO}$ $J$ = 3--2, and $\mathrm{H^{13}CN}$ $J$
= 1--0 lines with the ASTE 10 m and NRO 45 m telescopes, detecting bright
emission with $80\mbox{--}120$\ $\mathrm{km\,s^{-1}}$ velocity width (in
full-width at zero intensity) toward CO$-0.30$$-0.07$ and CO$-0.40$$-0.22$,
which are high velocity compact clouds (HVCCs) identified with our previous CO
$J$ = 3--2 survey. Our data reveal an interesting internal structure of
CO$-0.30$$-0.07$ comprising a pair of high velocity lobes. The spatial-velocity
structure of CO$-0.40$$-0.22$ can be also understood as multiple velocity
component, or a velocity gradient across the cloud. They are both located on
the rims of two molecular shells of about 10 pc in radius. Kinetic energies of
CO$-0.30$$-0.07$ and CO$-0.40$$-0.22$ are
$\left(0.8\mbox{--}2\right)\times10^{49}$ erg and
$\left(1\mbox{--}4\right)\times10^{49}$ erg, respectively. We propose several
interpretations of their broad emission: collision between clouds associated
with the shells, bipolar outflow, expansion driven by supernovae (SNe), and
rotation around a dark massive object. There scenarios cannot be discriminated
because of the insufficient angular resolution of our data, though the absence
of visible energy sources associated with the HVCCs seems to favor the
cloud--cloud collision scenario. Kinetic energies of the two molecular shells
are $1\times10^{51}$ erg and $0.7\times10^{51}$ erg, which can be furnished by
multiple SN or hypernova explosions in $2\times10^5$ yr. These shells are
candidates of molecular superbubbles created after past active star formation.


title: Controlled growth of bismuth ferrite multiferroic flowers

abstract:
  This study reports on the synthesis of ball-like bismuth ferrite BiFeO3
nanoflowers by means of microwave assisted hydrothermal process and also on
their composition and mechanism of growth. It turns out that the petals of the
nanoflowers are composed of the nanocrystals with the size about 35-39 nm
whereas their thickness and size depends on the concentration of surfactants.
The petals contain BiFeO3 phase and traces of Bi2O3 oxide and metallic Bi and
Fe deposited mainly at their surface. Amounts of impurity phases are more
pronounced in nanoflowers synthesized during short time, and become almost
negligible for longer microwave processing. The nanoflowers contain also mixed
Fe valence, with the Fe2+/Fe3+ ratio depending on the time of synthesis. The
growth and shape of the nanoflowers result from the process of diffusion in the
initial stages of hydrothermal reaction.


title: On graphs whose Hosoya indices are primitive Pythagorean triples

abstract:
  We discuss families of triples of graphs whose Hosoya indices are primitive
Pythagorean triples. Hosoya gave a method to construct such families of
caterpillars, i.e., trees whose vertices are within distance 1 of a central
path. He also pointed out a common structure to the families, and conjectured
the uniqueness of the structure. In this paper, we give an answer to his
conjecture.


title: Origins of Megalithic Astronomy in Britain

abstract:
  By c. 3000 BC, in the late Neolithic, there had been a significant change in
the way people materialized their cosmology across Scotland with the
introduction of free-standing stones. These were erected almost until the end
of the Bronze Age (Burl 2000, 1993). Significantly, a series of astronomical
patternings have been empirically verified for many Bronze Age monuments that
were erected between 1400-900 BC (Higginbottom et 14 al. 2013, 2003, 2001,
2000). Further, two series of complex landscape patternings associated with the
same monuments and their orientations have been identified (Higginbottom et al.
2013 & Higginbottom 'in preparation' - Bronze Age megalithic monuments on the
isle of Mull). However, when and where these patterns were first associated
with standing-stone structures was unknown. Through innovative statistics and
software we show that visible astronomical-landscape variables found at Bronze
Age sites on the inner isles and mainland of western Scotland were actually
first established nearly two millennia earlier, with the erection of the first
'great circles' in Britain: Callanish on the Isle of Lewis and Stenness on the
Isle of Orkney. In particular, we introduce our new statistical test that
enables the quantitative determination of astronomical connections of stone
circles. It is seen that, whilst different standing-stone monuments were
created over time (Burl 2000, 1993; 22 Higginbottom et al. 2013; Sheridan &
Brophy 2012) with a mixture of landscape variables (Higginbottom et al. 2013),
there are nevertheless highly relevant aspects that remained unchanged through
these years. This suggests that there is some continuity of this cosmological
system through time, despite the various radical material and social changes
that occurred from the late Neolithic to the Late Bronze Age (Lynch 2000;
Mullin 26 2001; Owoc 2001).


title: A model for the common origin of Jupiter family and Halley type comets

abstract:
  A numerical simulation of the Oort cloud is used to explain the observed
orbital distributions and numbers of Jupiter-family and Halley-type
short-period comets. Comets are given initial orbits with perihelion distances
between 5 and 36 AU, and evolve under planetary, stellar and Galactic
perturbations for 4.5 Gyr. This process leads to the formation of an Oort cloud
(which we define as the region of semimajor axes a>1000 AU), and to a flux of
cometary bodies from the Oort cloud returning to the planetary region at the
present epoch. The results are consistent with the dynamical characteristics of
short-period comets and other observed cometary populations: the near-parabolic
flux, Centaurs, and high-eccentricity trans-Neptunian objects. To achieve this
consistency with observations, the model requires that the number of comets
versus initial perihelion distance is concentrated towards the outer planetary
region. Moreover, the mean physical lifetime of observable comets in the inner
planetary region (q<2.5 AU) at the present epoch should be an increasing
function of the comets' initial perihelion distances. Virtually all observed
Halley-type comets and nearly half of observed Jupiter-family comets come from
the Oort cloud, and initially (4.5 Gyr ago) from orbits concentrated near the
outer planetary region. Comets that have been in the Oort cloud also return to
the Centaur (5<q<28 AU, a<1000 AU) and near-Neptune high-eccentricity regions.
Such objects with perihelia near Neptune are hard to discover, but Centaurs
with characteristics predicted by the model (e.g., large semimajor axes, above
60 au, or high inclinations, above 40 degrees) are increasingly being found by
observers. The model predicts that the mean physical lifetime of all comets in
the region q<1.5 AU is less than approximately 200 revolutions.


title:
Problematic aspects of Kaluza-Klein excitations in multidimensional
  models with Einstein internal spaces

abstract:
  We consider Kaluza-Klein (KK) models where internal spaces are compact
Einstein spaces. These spaces are stabilized by background matter (e.g.,
monopole form-fields). We perturb this background by a compact matter source
(e.g., the system of gravitating masses) with the zero pressure in the
external/our space and an arbitrary pressure in the internal space. We show
that the Einstein equations are compatible only if the matter source is smeared
over the internal space and perturbed metric components do not depend on
coordinates of extra dimensions. The latter means the absence of KK modes
corresponding to the metric fluctuations. Maybe, the absence of KK particles in
LHC experiments is explained by such mechanism.


title:
Observing and Reducing IFUs: INTEGRAL and PMAS -- Properties of the
  Ionized Gas in HH 202

abstract:
  The reduction of integral field spectroscopy (IFS) data requires several
stages and many repetitive operations to convert raw data into, typically, a
large number of spectra. Instead there are several semiautomatic data reduction
tools and here we present this data reduction process using some of the Image
Reduction and Analysis Facility (IRAF) tasks devoted to reduce spectroscopic
data. After explaining the whole process, we illustrate the power of this
instrumental technique with some results obtained for the object HH202 in the
Orion Nebula (Mesa-Delgado et al., 2009).


title: The Cross-correlation of MgII Absorption and Galaxies in BOSS

abstract:
  We present a measurement of the cross-correlation of MgII absorption and
massive galaxies, using the DR11 main galaxy sample of the Baryon Oscillation
Spectroscopic Survey of SDSS-III (CMASS galaxies), and the DR7 quasar spectra
of SDSS-II. The cross-correlation is measured by stacking quasar absorption
spectra shifted to the redshift of galaxies that are within a certain impact
parameter bin of the quasar, after dividing by a quasar continuum model. This
results in an average MgII equivalent width as a function of impact parameter
from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which
includes all MgII absorbers. We show that special care needs to be taken to use
an unbiased quasar continuum estimator, to avoid systematic errors in the
measurement of the mean stacked MgII equivalent width. The measured
cross-correlation follows the expected shape of the galaxy correlation
function, although measurement errors are large. We use the cross-correlation
amplitude to derive the bias factor of MgII absorbers, finding bMgII = 2.33
\pm? 0.19, where the error accounts only for the statistical uncertainty in
measuring the mean equivalent width. This bias factor is larger than that
obtained in previous studies and may be affected by modeling uncertainties that
we discuss, but if correct it suggests that MgII absorbers at redshift z \simeq
0:5 are spatially distributed on large scales similarly to the CMASS galaxies
in BOSS.
  Keywords: galaxies: haloes, galaxies: formation, quasars: absorption lines,
large-scale structure of universe