title:
The spatial meaning of Pareto's scaling exponent of city-size
  distribution

abstract:
  The scaling exponent of a hierarchy of cities used to be regarded as a
fractal parameter. The Pareto exponent was treated as the fractal dimension of
size distribution of cities, while the Zipf exponent was treated as the
reciprocal of the fractal dimension. However, this viewpoint is not exact. In
this paper, I will present a new interpretation of the scaling exponent of
rank-size distributions. The ideas from fractal measure relation and the
principle of dimension consistency are employed to explore the essence of
Pareto's and Zipf's scaling exponents. The Pareto exponent proved to be a ratio
of the fractal dimension of a network of cities to the average dimension of
city population. Accordingly, the Zipf exponent is the reciprocal of this
dimension ratio. On a digital map, the Pareto exponent can be defined by the
scaling relation between a map scale and the corresponding number of cities
based on this scale. The cities of the United States of America in 1900, 1940,
1960, and 1980 and Indian cities in 1981, 1991, and 2001 are utilized to
illustrate the geographical spatial meaning of Pareto's exponent. The results
suggest that the Pareto exponent of city-size distribution is not a fractal
dimension, but a ratio of the urban network dimension to the city population
dimension. This conclusion is revealing for scientists to understand Zipf's law
and fractal structure of hierarchy of cities.


title: Hierarchical Bass model

abstract:
  We propose a new model about diffusion of a product which includes a memory
of how many adopters or advertisements a non-adopter met, where (non-)adopters
mean people (not) possessing the product. This effect is lacking in the Bass
model. As an application, we utilize the model to fit the iPod sales data, and
so the better agreement is obtained than the Bass model.


title:
A simple bootstrap method for constructing nonparametric confidence
  bands for functions

abstract:
  Standard approaches to constructing nonparametric confidence bands for
functions are frustrated by the impact of bias, which generally is not
estimated consistently when using the bootstrap and conventionally smoothed
function estimators. To overcome this problem it is common practice to either
undersmooth, so as to reduce the impact of bias, or oversmooth, and thereby
introduce an explicit or implicit bias estimator. However, these approaches,
and others based on nonstandard smoothing methods, complicate the process of
inference, for example, by requiring the choice of new, unconventional
smoothing parameters and, in the case of undersmoothing, producing relatively
wide bands. In this paper we suggest a new approach, which exploits to our
advantage one of the difficulties that, in the past, has prevented an
attractive solution to the problem - the fact that the standard bootstrap bias
estimator suffers from relatively high-frequency stochastic error. The high
frequency, together with a technique based on quantiles, can be exploited to
dampen down the stochastic error term, leading to relatively narrow,
simple-to-construct confidence bands.


title:
Instrumental neutron activation analysis of an enriched 28Si
  single-crystal

abstract:
  The determination of the Avogadro constant plays a key role in the
redefinition of the kilogram in terms of a fundamental constant. The present
experiment makes use of a silicon single-crystal highly enriched in 28Si that
must have a total impurity mass fraction smaller than a few parts in 109. To
verify this requirement, we previously developed a relative analytical method
based on neutron activation for the elemental characterization of a sample of
the precursor natural silicon crystal WASO 04. The method is now extended to
fifty-nine elements and applied to a monoisotopic 28Si single-crystal that was
grown to test the achievable enrichment. Since this crystal was likely
contaminated, this measurement tested also the detection capabilities of the
analysis. The results quantified contaminations by Ge, Ga, As, Tm, Lu, Ta, W
and Ir and, for a number of the detectable elements, demonstrated that we can
already reach the targeted 1 ng/g detection limit.


title: Linear Structures in the Core of the Coma Cluster of Galaxies

abstract:
  The hot X-ray emitting plasma in galaxy clusters is predicted to have
turbulent motions which can contribute around ten percent of the cluster's
central energy density. We report deep Chandra X-ray Observatory observations
of the Coma cluster core, showing the presence of quasi-linear high-density
arms spanning 150 kpc, consisting of low-entropy material likely stripped from
merging subclusters. Two appear to be connected with a subgroup of galaxies at
650 kpc radius that is merging into the cluster, implying coherence over
several hundred Myr. Such long lifetime implies that strong isotropic
turbulence and conduction are suppressed in the core, despite the unrelaxed
state of the cluster. Magnetic fields are presumably responsible. The
structures seen in Coma present insight into the past Gyr of subcluster merger
activity.


title:
Fisher-Hartwig expansion for the transverse correlation function in the
  XX spin-1/2 chain

abstract:
  Motivated by the recent results on the asymptotic behavior of Toeplitz
determinants with Fisher-Hartwig singularities, we develop an asymptotic
expansion for transverse spin correlations in the XX spin-1/2 chain. The
coefficients of the expansion can be calculated to any given order using the
relation to discrete Painleve equations. We present explicit results up to
eleventh order and compare them with a numerical example.

categories: cond-mat.str-el cond-mat.stat-mech math-ph math.MP


title:
Existence result for a strongly coupled problem with heat convection
  term and Tresca's law

abstract:
  We study a problem describing the motion of an incompressible, nonisothermal
and non-Newtonian uid, taking into account the heat convection term. The
novelty here is that uid viscosity depends on the temperature, the velocity of
the uid, and also of the deformation tensor, but not explicitly. The boundary
conditions take into account the slip phenomenon on a part of the boundary of
the domain. By using the notion of pseudo-monotone operators and xed point
Theorem we prove an existence result of its weak solution.


title:
Existence, Uniqueness, and Convergence of optimal control problems
  associated with Parabolic variational inequalities of the second kind

abstract:
  Let $u_{g}$ the unique solution of a parabolic variational inequality of
second kind, with a given $g$. Using a regularization method, we prove, for all
$g_{1}$ and $g_{2}$, a monotony property between $\mu u_{g_{1}} +
(1-\mu)u_{g_{2}}$ and $u_{\mu g_{1} + (1-\mu)g_{2}}$ for $\mu \in [0, 1]$. This
allowed us to prove the existence and uniqueness results to a family of optimal
control problems over $g$ for each heat transfer coefficient $h>0$, associated
to the Newton law, and of another optimal control problem associated to a
Dirichlet boundary condition. We prove also, when $h\to +\infty$, the strong
convergence of the optimal controls and states associated to this family of
optimal control problems with the Newton law to that of the optimal control
problem associated to a Dirichlet boundary condition.


title:
Systematic study of defect-related quenching of NV luminescence in
  diamond with time correlated single photon counting spectroscopy

abstract:
  We report on the systematic characterization of photoluminescence (PL)
lifetimes in NV- and NV0 centers in 2 MeV H+ implanted type Ib diamond samples
by means of a time correlated single photon counting (TCSPC) microscopy
technique. A dipole-dipole resonant energy transfer model was applied to
interpret the experimental results, allowing a quantitative correlation of the
concentration of both native (single substitutional nitrogen atoms) and
ion-induced (isolated vacancies) PL-quenching defects with the measured PL
lifetimes. The TCSPC measurements were carried out in both frontal (i.e. laser
beam probing the main sample surface along the same normal direction of the
previously implanted ions) and lateral (i.e. laser beam probing the lateral
sample surface orthogonally with respect to the same ion implantation
direction) geometries. In particular, the latter geometry allowed a direct
probing of the centers lifetime along the strongly nonuniform damage profiles
of MeV ions in the crystal. The extrapolation of empirical quasi-exponential
decay parameters allowed the systematic estimation of the mean quantum
efficiency of the centers as a function of intrinsic and ion-induced defect
concentration, which is of direct relevance for the current studies on the use
of diamond color centers for photonic applications.


title:
Multivariate ratio estimation with known population proportion of two
  auxiliary characters for finite population

abstract:
  In the present study, we propose estimators based on geometric and harmonic
mean for estimating population mean using information on two auxiliary
attributes in simple random sampling. We have shown that, when we have
multi-auxiliary attributes, estimators based on geometric mean and harmonic
mean are less biased than Olkin (1958), Naik and Gupta (1996) and Singh (1967)
type- estimator under certain conditions. However, the MSE of Olkin(1958)
estimator and geometric and harmonic estimators are same up to the first order
of approximation.


title:
Study of the strong prolongation equation for the construction of
  statically admissible stress fields: implementation and optimization

abstract:
  This paper focuses on the construction of statically admissible stress fields
(SA-fields) for a posteriori error estimation. In the context of verification,
the recovery of such fields enables to provide strict upper bounds of the
energy norm of the discretization error between the known finite element
solution and the unavailable exact solution. The reconstruction is a difficult
and decisive step insofar as the effectiveness of the estimator strongly
depends on the quality of the SA-fields. This paper examines the strong
prolongation hypothesis, which is the starting point of the Element
Equilibration Technique (EET). We manage to characterize the full space of
SA-fields satisfying the prolongation equation so that optimizing inside this
space is possible. The computation exploits topological properties of the mesh
so that implementation is easy and costs remain controlled. In this paper, we
describe the new technique in details and compare it to the classical EET and
to the flux-free technique for different 2D mechanical problems. The method is
explained on first degree triangular elements, but we show how extensions to
different elements and to 3D are straightforward.


title:
Sub-Stream Fairness and Numerical Correctness in MIMO Interference
  Channels

abstract:
  Stream fairness, fairness between all streams in the system, is a more
restrictive condition than sub-stream fairness, fairness between all streams of
each user. Thus sub-stream fairness alleviates utility loss as well as
complexity and overhead compared to stream fairness. Moreover, depending on
algorithmic parameters, conventional algorithms including distributed
interference alignment (DIA) may not provide sub-stream fairness, and generate
sub-streams with poor signal-to-interference plus noise ratios (SINRs), thus
with poor bit error rates (BERs). To this end, we propose a distributed power
control algorithm to render sub-stream fairness in the system, and establish
initiatory connections between sub-stream SINRs, BERs, and rates. Algorithms
have particular responses to parameters. In the paper, important algorithmic
parameters are analyzed to exhibit numerical correctness in benchmarking. The
distinction between separate filtering schemes that design each stream of a
user separately and group filtering schemes that jointly design the streams of
a user is also underscored in the paper. Finally, the power control law used in
the proposed algorithm is proven to linearly converge to a unique fixed-point,
and the algorithm is shown to achieve feasible SINR targets.


title:
Convergence of optimal control problems governed by second kind
  parabolic variational inequalities

abstract:
  We consider a family of optimal control problems where the control variable
is given by a boundary condition of Neumann type. This family is governed by
parabolic variational inequalities of the second kind. We prove the strong
convergence of the optimal controls and state systems associated to this family
to a similar optimal control problem. This work solves the open problem left by
the authors in IFIP TC7 CSMO2011.


title:
Asymptotic analysis of a micropolar fluid flow in a thin domain with a
  free and rough boundary

abstract:
  Motivated by lubrication problems, we consider a micropolar uid ow in a 2D
domain with a rough and free boundary. We assume that the thickness and the
roughness are both of order 0 < " << 1. We prove the existence and uniqueness
of a solution of this problem for any value of " and we establish some a priori
estimates. Then we use the two-scale convergence technique to derive the limit
problem when " tends to zero. Moreover we show that the limit velocity and
micro-rotation elds are uniquely determined via auxiliary well-posed problems
and the limit pressure is given as the unique solution of a Reynolds equation.


title:
Convergence of Distributed Optimal Control Problems Governed by Elliptic
  Variational Inequalities

abstract:
  First, let $u_{g}$ be the unique solution of an elliptic variational
inequality with source term $g$. We establish, in the general case, the error
estimate between $u_{3}(\mu)=\mu u_{g_{1}}+ (1-\mu)u_{g_{2}}$ %(the convex
combination of two solutions) and $u_{4}(\mu)=u_{\mu g_{1}+ (1-\mu) g_{2}}$
%(the solution corresponding to the convex combination of two data) for $\mu\in
[0, 1]$. Secondly, we consider a family of distributed optimal control problems
governed by elliptic variational inequalities over the internal energy $g$ for
each positive heat transfer coefficient $h$ given on a part of the boundary of
the domain. For a given cost functional and using some monotony property
between $u_{3}(\mu)$ and $u_{4}(\mu)$ given in F. Mignot, J. Funct. Anal., 22
(1976), 130-185, we prove the strong convergence of the optimal controls and
states associated to this family of distributed optimal control problems
governed by elliptic variational inequalities to a limit Dirichlet distributed
optimal control problem, governed also by an elliptic variational inequality,
when the parameter $h$ goes to infinity. We obtain this convergence without
using the adjoint state problem (or the Mignot's conical differentiability)
which is a great advantage with respect to the proof given in C.M. Gariboldi -
D.A. Tarzia, Appl. Math. Optim., 47 (2003), 213-230, for optimal control
problems governed by elliptic variational equalities.


title: A Holographic P-wave Superconductor Model

abstract:
  We study a holographic p-wave superconductor model in a four dimensional
Einstein-Maxwell-complex vector field theory with a negative cosmological
constant. The complex vector field is charged under the Maxwell field. We solve
the full coupled equations of motion of the system and find black hole
solutions with the vector hair. The vector hairy black hole solutions are dual
to a thermal state with the U(1) symmetry as well as the spatial rotational
symmetry breaking spontaneously. Depending on two parameters, the mass and
charge of the vector field, we find a rich phase structure: zeroth order, first
order and second order phase transitions can happen in this model. We also find
"retrograde condensation" in which the hairy black hole solution exists only
for the temperatures above a critical value with the free energy much larger
than the black hole without hair. We construct the phase diagram for this
system in terms of the temperature and charge of the vector field.


title: On weak interaction between a ground state and a non-trapping potential

abstract:
  We show that ground states of the NLS moving at nonzero speed are
asymptotically stable if they either stay far from the potential, or the
potential is small, or the ground state has large speed.


title: Disquisitiones 235

abstract:
  Section 235 of Gauss' fundamental treatise "Disquisitiones Arithmeticae"
establishes basic properties that compositions of binary quadratic forms must
satisfy. Although this section is very technical, it contains truly important
results. We review section 235 using a more invariant language and simplifying
the arguments. We also make the statements slightly stronger by removing
unnecessary assumptions.


title: Markov chains for tensor network states

abstract:
  Markov chains for probability distributions related to matrix product states
and 1D Hamiltonians are introduced. With appropriate 'inverse temperature'
schedules, these chains can be combined into a random approximation scheme for
ground states of such Hamiltonians. Numerical experiments suggest that a
linear, i.e. fast, schedule is possible in non-trivial cases. A natural
extension of these chains to 2D settings is next presented and tested. The
obtained results compare well with Euclidean evolution. The proposed Markov
chains are easy to implement and are inherently sign problem free (even for
fermionic degrees of freedom).


title:
"Tomography" of the cluster structure of light nuclei via relativistic
  dissociation

abstract:
  These lecture notes present the capabilities of relativistic nuclear physics
for the development of the physics of nuclear clusters. Nuclear track emulsion
continues to be an effective technique for pilot studies that allows one, in
particular, to study the cluster dissociation of a wide variety of light
relativistic nuclei within a common approach. Despite the fact that the
capabilities of the relativistic fragmentation for the study of nuclear
clustering were recognized quite a long time ago, electronic experiments have
not been able to come closer to an integrated analysis of ensembles of
relativistic fragments. The continued pause in the investigation of the "fine"
structure of relativistic fragmentation has led to resumption of regular
exposures of nuclear emulsions in beams of light nuclei produced for the first
time at the Nuclotron of the Joint Institute for Nuclear Research (JINR,
Dubna). To date, an analysis of the peripheral interactions of relativistic
isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones,
with nuclei of the emulsion composition, has been performed, which allows the
clustering pattern to be presented for a whole family of light nuclei.


title: Approximation Theory and the Design of Fast Algorithms

abstract:
  We survey key techniques and results from approximation theory in the context
of uniform approximations to real functions such as e^{-x}, 1/x, and x^k. We
then present a selection of results demonstrating how such approximations can
be used to speed up primitives crucial for the design of fast algorithms for
problems such as simulating random walks, graph partitioning, solving linear
system of equations, computing eigenvalues and combinatorial approaches to
solve semi-definite programs.


title:
Giant electroresistance and tunable magnetoelectricity in a multiferroic
  junction

abstract:
  First-principles density functional calculations show that the
$\textrm{SrRuO}_{3}/\textrm{PbTiO}_{3}/\textrm{SrRuO}_{3}$ multiferroic
junction with asymmetric (RuO$_{2}$/PbO and TiO$_{2}$/SrO) interfaces has a
large ferroelectric depolarizing field, whose switching changes the interface
transmission probabilities for tunneling electrons, leading to
electroresistance modulation over several orders of magnitude. The switching
further affects the interface spin density, naturally driving magnetoresistance
as well as modulated spin-dependent in-plane resistivity, which may be
exploited in field-effect devices.


title: On typical leaves of a measured foliated 2-complex of thin type

abstract:
  It is known that all but finitely many leaves of a measured foliated
2-complex of thin type are quasi-isometric to an infinite tree with at most two
topological ends. We show that if the foliation is cooriented, and the
associated R-tree is self-similar, then a typical leaf has exactly one
topological end. We also construct the first example of a foliated 2-complex of
thin type whose typical leaf has exactly two topological ends. `Typical' means
that the property holds with probability one in a natural sense.


title: High-throughput synthesis of thermoelectric Ca$_3$Co$_4$O$_9$ films

abstract:
  Properties of complex oxide thin films can be tuned over a range of values as
a function of mismatch, composition, orientation, and structure. Here, we
report a strategy for growing structured epitaxial thermoelectric thin films
leading to improved Seebeck coefficient. Instead of using single-crystal
sapphire substrates to support epitaxial growth, Ca$_3$Co$_4$O$_9$ films are
deposited, using the Pulsed Laser Deposition technique, onto Al$_2$O$_3$
polycrystalline substrates textured by Spark Plasma Sintering. The structural
quality of the 2000 \AA thin film was investigated by Transmission Electron
Microscopy, while the crystallographic orientation of the grains and the
epitaxial relationships were determined by Electron Back Scatter Diffraction.
The use of a polycrystalline ceramic template leads to structured films that
are in good local epitaxial registry. The Seebeck coefficient is about 170
$\mu$V/K at 300 K, a typical value of misfit material with low carrier density.
This high-throughput process, called combinatorial substrate epitaxy, appears
to facilitate the rational tuning of functional oxide films, opening a route to
the epitaxial synthesis of high quality complex oxides.


title:
The Araucaria Project : the Baade-Wesselink projection factor of
  pulsating stars

abstract:
  The projection factor used in the Baade-Wesselink methods of determining the
distance of Cepheids makes the link between the stellar physics and the
cosmological distance scale. A coherent picture of this physical quantity is
now provided based on several approaches. We present the lastest news on the
expected projection factor for different kinds of pulsating stars in the
Hertzsprung-Russell diagram.


title: iDataCool: HPC with Hot-Water Cooling and Energy Reuse

abstract:
  iDataCool is an HPC architecture jointly developed by the University of
Regensburg and the IBM Research and Development Lab B\"oblingen. It is based on
IBM's iDataPlex platform, whose air-cooling solution was replaced by a custom
water-cooling solution that allows for cooling water temperatures of 70C/158F.
The system is coupled to an adsorption chiller by InvenSor that operates
efficiently at these temperatures. Thus a significant portion of the energy
spent on HPC can be recovered in the form of chilled water, which can then be
used to cool other parts of the computing center. We describe the architecture
of iDataCool and present benchmarks of the cooling performance and the energy
(reuse) efficiency.


title: Kepler RR Lyrae stars: beyond period doubling

abstract:
  We examined the complete short cadence sample of Kepler RR Lyrae stars to
further investigate the recently discovered dynamical effects such as period
doubling and additional modes. Here we present the findings on four stars. V450
Lyr may be a non-classical double-mode RR Lyrae star pulsating in the
fundamental mode and the second overtone. In three cases we observe the
interaction of three different modes. Since the period ratios are close to
resonant values, we observe quasi-repetiting patterns in the pulsation cycles
in the stars. These findings support the mode-resonance explanations of the
Blazhko effect.


title:
Optimal sparse volatility matrix estimation for high-dimensional It\^{o}
  processes with measurement errors

abstract:
  Stochastic processes are often used to model complex scientific problems in
fields ranging from biology and finance to engineering and physical science.
This paper investigates rate-optimal estimation of the volatility matrix of a
high-dimensional It\^{o} process observed with measurement errors at discrete
time points. The minimax rate of convergence is established for estimating
sparse volatility matrices. By combining the multi-scale and threshold
approaches we construct a volatility matrix estimator to achieve the optimal
convergence rate. The minimax lower bound is derived by considering a subclass
of It\^{o} processes for which the minimax lower bound is obtained through a
novel equivalent model of covariance matrix estimation for independent but
nonidentically distributed observations and through a delicate construction of
the least favorable parameters. In addition, a simulation study was conducted
to test the finite sample performance of the optimal estimator, and the
simulation results were found to support the established asymptotic theory.


title:
Physics of plasma burn-through and DYON simulations for the JET
  ITER-like wall

abstract:
  This paper presents the DYON simulations of the plasma burn-through phase at
Joint European Torus (JET) with the ITER-like wall. The main purpose of the
study is to validate the simulations with the ITER-like wall, made of
beryllium. Without impurities, the burn-through process of a pure deuterium
plasma is described using DYON simulations, and the criterion for deuterium
burn-through is derived analytically. The plasma burn-through with impurities
are simulated using wall-sputtering models in the DYON code, which are modified
for the ITER-like wall. The wall-sputtering models and the validation against
JET data are presented. The impact of the assumed plasma parameters in DYON
simulations are discussed by means of parameter scans. As a result, the
operation space of prefill gas pressure and toroidal electric field for plasma
burn-through in JET is compared to the Townsend avalanche criterion.


title:
The Mid-Infrared Light Curve of Nearby Core-Collapse Supernova SN2011dh
  (PTF11eon)

abstract:
  We present Spitzer observations at 3.6 and 4.5um of the supernova SN2011dh
(PTF11eon) in M51 from 18 days to 625 days after explosion. The mid-infrared
emission peaks at 24 days after explosion at a few times 10^7 Lsun, and decays
more slowly than the visible-light bolometric luminosity. The infrared color
temperature cools for the first 90 days and then is constant. Simple numerical
models of a thermal echo can qualitatively reproduce the early behavior. At
late times, the mid-IR light curve cannot be explained by a simple thermal echo
model, suggesting additional dust heating or line emission mechanisms. We also
propose that thermal echoes can serve as effective probes to uncover supernovae
in heavily obscured environments, and speculate that under the right
conditions, integrating the early epoch of the mid-infrared light curve may
constrain the total energy in the shock breakout flash.


title:
Microscopic identification of dissipative modes in relativistic field
  theories

abstract:
  We present an argument to support the existence of dissipative modes in
relativistic field theories. In an O(N) $\varphi^4$ theory in spatial dimension
$d\le 3$, a relaxation constant $\Gamma$ of a two-point function in an infrared
region is shown to be finite within the two-particle irreducible (2PI)
framework at the next-leading order (NLO) of 1/N expansion. This immediately
implies that a slow dissipative mode with a dispersion $p_0\sim i\Gamma \p^2$
is microscopically identified in the two-point function. Contrary, NLO
calculation in the one-particle irreducible (1PI) framework fails to yield a
finite relaxation constant. Comparing the results in 1PI and 2PI frameworks,
one concludes that dissipation emerges from multiple scattering of a particle
with a heat bath, which is appropriately treated in the 2PI-NLO calculation
through the resummation of secular terms to improve long-time behavior of the
two-point function. Assuming that this slow dissipative mode survives at the
critical point, one can identify the dynamic critical exponent $z$ for the
two-point function as $z=2-\eta$. We also discuss possible improvement of the
result.


title: Mechanical Therapy as a Potential Green Way to Attack Cancer Disease

abstract:
  Mechanical force is tightly connected to human health status, and the
occurrence of disease can generally be ascribed to certain loss of force
balance. However, the role of mechanical approaches in tumor therapy is largely
neglected, while the currently available cancer prevention and treatment
methods are generally either expensive or just cause too much side effect. In
this article, we present a systematic interpretation on a promising strategy
which was termed here as Mechanical Therapy for the first time based on the
fact that mechanical force closely accompanies the whole life (growth and
death) of a cell, and plays a crucial role in biological functions. In order to
mold the mechanical force as a practical tool for cancer therapy, we expound
the effects of the mechanical force related to the tumors from molecule to
tissue level and evaluate its feasibility for treatment purpose. It can be
conceived that given enough investigations, the mechanical therapy may generate
big potential to open new windows for cancer prevention, relieving or even
destroying if well administrated. As an easy going and convenient method, a
systematic and thorough study of mechanical therapy may clarify more options
for future clinical practices. Besides, when patients encounter various forces
in daily life, they can at least identify the good or bad forces for a better
and healthy life style based on the mechanisms thus disclosed.


title: The direct enstrophy cascade of two-dimensional soap film flows

abstract:
  We investigate the direct enstrophy cascade of two-dimensional decaying
turbulence in a flowing soap film channel. We use a coarse-graining approach
that allows us to resolve the nonlinear dynamics and scale-coupling
simultaneously in space and in scale. From our data, we verify an exact
relation due to Eyink (1995) between traditional 3rd-order structure function
and the enstrophy flux obtained by coarse-graining. We also present
experimental evidence that enstrophy cascades to smaller (larger) scales with a
60% (40%) probability, in support of theoretical predictions by Merilees & Warn
(1975) which appear to be valid in our flow owing to the ergodic nature of
turbulence. We conjecture that their kinematic arguments break down in
quasi-laminar 2D flows. We find some support for these ideas by using an
Eulerian coherent structure identification technique, which allows us to
determine the effect of flow topology on the enstrophy cascade. A key finding
is that "centers" are inefficient at transferring enstrophy between scales, in
contrast to "saddle" regions which transfer enstrophy to small scales with high
efficiency.


title: Relativistic Solar Cells

abstract:
  Hybrid AMX3 perovskites (A=Cs, CH3NH3; M=Sn, Pb; X=halide) have
revolutionized the scenario of emerging photovoltaic technologies. Introduced
in 2009 by Kojima et al., a rapid evolution very recently led to 15% efficient
solar cells. CH3NH3PbI3 has so far dominated the field, while the similar
CH3NH3SnI3 has not been explored for photovoltaic applications, despite the
reduced band-gap. Replacement of Pb by the more environment-friendly Sn would
facilitate the large uptake of perovskite-based photovoltaics. Despite the
extremely fast progress, the materials electronic properties which are key to
the photovoltaic performance are relatively little understood. Here we develop
an effective GW method incorporating spin-orbit coupling which allows us to
accurately model the electronic, optical and transport properties of CH3NH3SnI3
and CH3NH3PbI3, opening the way to new materials design. The different
CH3NH3SnI3 and CH3NH3PbI3 properties are discussed in light of their
exploitation for solar cells, and found to be entirely due to relativistic
effects.


title: Zero-curvature condition in Calogero model

abstract:
  We consider the mutual commutativity of Dunkl operators of the rational
Calogero model as zero-curvature condition and calculate the non-local
operator, related to these flat connections. This operator has physical meaning
of particular scattering matrix of Calogero model and maps the eigenfunctions
of Dunkl operator to the wave function of $N$ free particles (plane waves).


title:
Van der Waals Coefficients for the Alkali-metal Atoms in the Material
  Mediums

abstract:
  The damping coefficients for the alkali atoms are determined very accurately
by taking into account the optical properties of the atoms and three distinct
types of trapping materials such as Au (metal), Si (semi-conductor) and
vitreous SiO2 (dielectric). Dynamic dipole polarizabilities are calculated
precisely for the alkali atoms that reproduce the damping coefficients in the
perfect conducting medium within 0.2% accuracy. Upon the consideration of the
available optical data of the above wall materials, the damping coefficients
are found to be substantially different than those of the ideal conductor. We
also evaluated dispersion coefficients for the alkali dimers and compared them
with the previously reported values. These coefficients are fitted into a
ready-to-use functional form to aid the experimentalists the interaction
potentials only with the knowledge of distances.


title:
Extreme Low Thermal Conductivity in Nanoscale 3D Si Phononic Crystal
  with Spherical Pores

abstract:
  Thermoelectric material provides a high hope for converting harmful and
useless heat into useful energy, electricity. It can also be used as solid
state Peltier coolers in integrated circuits, an outstanding challenge for
electronic engineers. The desire for a high efficient thermoelectric material
has never been so keen. Although many works have been done, we are still far
from having a recipe for thermoelectric materials. Nano-structuring provides an
effective way to increase figure of merit (ZT) by reducing the thermal
conductivity without affecting electronic property.1 Here, we propose a novel
nanoscale three-dimensional (3D) Si phononic crystal (PnC) with spherical
pores, which can reduce the thermal conductivity of bulk Si by a factor up to
10,000 times at room temperature. The extreme-low thermal conductivity could
lead to a larger value of ZT than unity. The thermal conductivity changes
little when temperature increases from room temperature to 1100 K. The phonon
participation ratio spectra show there are more phonon localizations as the
porosity of PnC increases.


title:
An expansion formula with higher-order derivatives for fractional
  operators of variable order

abstract:
  We obtain approximation formulas for fractional integrals and derivatives of
Riemann-Liouville and Marchaud types with a variable fractional order. The
approximations involve integer-order derivatives only. An estimation for the
error is given. The efficiency of the approximation method is illustrated with
examples. As applications, we show how the obtained results are useful to solve
differential equations and problems of the calculus of variations that depend
on fractional derivatives of Marchaud type.


title: Conformally coupled inflation

abstract:
  A massive scalar field in a curved spacetime can propagate along the light
cone, a causal pathology, which can, in principle, be eliminated only if the
scalar couples conformally to the Ricci curvature of spacetime. This property
mandates conformal coupling for the field driving inflation in the early
universe. During slow-roll inflation, this coupling can cause
super-acceleration and, as a signature, a blue spectrum of primordial
gravitational waves.


title: On the Stability of Quantum Hall Kagome-ice Insulator

abstract:
  The stability of the kagome-ice insulator against the three dimensionality
and the canting angle of the spin anisotropy axes is studied numerically using
the exact diagonalization method. The kagome-ice insulator, which was recently
found at 2/3 electron filling in the double-exchange model on a kagome lattice,
is a Chern insulator showing a quantized Hall response despite the absence of
magnetic long-range order. We find that this peculiar state remains stable when
the lattice is extended to three dimensions in an anisotropic pyrochlore
lattice in the weak interlayer coupling region. On the other hand, we show that
the kagome-ice insulator is also stable against the change of the canting
angle. Furthermore, we find another kagome-ice insulator at 1/3 filling in a
different range of the canting angle. Our results indicate that the quantum
anomalous Hall response is widely observed in the variants of the kagome-ice
double-exchange systems.


title:
Probing quantum transport by engineering correlations in a speckle
  potential

abstract:
  We develop a procedure to modify the correlations of a speckle potential.
This procedure, that is suitable for spatial light modulator devices, allows
one to increase the localization efficiency of the speckle in a narrow energy
region whose position can be easily tuned. This peculiar energy-dependent
localization behavior is explored by pulling the potential through a
cigar-shaped Bose-Einstein condensate. We show that the percentage of dragged
atoms as a function of the pulling velocity depends on the potential
correlations below a threshold of the disorder strength. Above this threshold,
interference effects are no longer clearly observable during the condensate
drag.


title: Screening and Collective Modes in Disordered Graphene Antidot Lattices

abstract:
  The excitation spectrum and the collective modes of graphene antidot lattices
(GALs) are studied in the context of a $\pi$-band tight-binding model. The
dynamical polarizability and dielectric function are calculated within the
random phase approximation. The effect of different kinds of disorder, such as
geometric and chemical disorder, are included in our calculations. We highlight
the main differences of GALs with respect to single-layer graphene (SLG). Our
results show that, in addition to the well-understood bulk plasmon in doped
samples, inter-band plasmons appear in GALs. We further show that the static
screening properties of undoped and doped GALs are quantitatively different
from SLG.


title: Pulsations as a mass-loss trigger in evolved hot stars

abstract:
  During the post-main sequence evolution massive stars pass through several
short-lived phases, in which they experience enhanced mass loss in the form of
clumped winds and mass ejection events of unclear origin. The discovery that
stars populating the blue, luminous part of the Hertzsprung-Russell diagram can
pulsate hence suggests that stellar pulsations might influence or trigger
enhanced mass loss and eruptions. We present recent results for two objects in
different phases: a B[e] star at the end of the main sequence and a B-type
supergiant.


title:
Transverse and longitudinal gradients of the spin magnetization in
  Spin-Density-Functional Theory

abstract:
  We derive the gradient expansion for the exchange energy of a spin-polarized
electron gas by perturbing the uniformly spin polarized state and thus inducing
a small non-collinearity that is slowly varying in space. We show that the
exchange-energy contribution due to the induced longitudinal gradient of the
spin polarization to the exchange energy differs from the contribution due to
the transverse gradient. The difference is present at any non-vanishing spin
polarization and becomes larger with increasing spin polarization. We argue
that improved generalized gradient approximations of Spin-Density-Functional
Theory must account for the difference between the longitudinal and transverse
spin stiffness.


title: Dense cores in the dark cloud complex LDN1188

abstract:
  We present a molecular line emission study of the LDN1188 dark cloud complex
located in Cepheus. In this work we focused on the densest parts of the cloud
and on the close neighbourhood of infrared point sources. We made ammonia
mapping with the Effelsberg 100-m radio telescope and identified 3 dense cores.
CS(1--0), CS(2--1) and HCO$^{+}$(1--0) measurements performed with the Onsala
20\,m telescope revealed the distribution of dense molecular material. The
molecular line measurements were supplemented by mapping the dust emission at
1.2\,mm in some selected directions using the IRAM 30\,m telescope. With these
data we could work out a likely evolutionary sequence in this dark clould
complex.


title:
On Adaptive Measurement Inclusion Rate In Real-Time Moving-Horizon
  Observers

abstract:
  This paper investigates a self adaptation mechanism regarding the rate with
which new measurements have to be incorporated in Moving-Horizon state
estimation algorithms. This investigation can be viewed as the dual of the one
proposed by the author in the context of real-time model predictive control. An
illustrative example is provided in order to assess the relevance of the
proposed updating rule.


title:
Fabrication and Response of High Concentration SIMPLE Superheated
  Droplet Detectors with Different Liquids

abstract:
  The combined measurement of dark matter interactions with different
superheated liquids has recently been suggested as a cross-correlation
technique in identifying WIMP candidates. We describe the fabrication of high
concentration superheated droplet detectors based on the light nuclei liquids
C3F8, C4F8, C4F10 and CCl2F2, and investigation of their irradiation response
with respect to C2ClF5. The results are discussed in terms of the basic physics
of superheated liquid response to particle interactions, as well as the
necessary detector qualifications for application in dark matter search
investigations. The possibility of heavier nuclei SDDs is explored using the
light nuclei results as a basis, with CF3I provided as an example.


title:
Star formation and accretion in the circumnuclear disks of active
  galaxies

abstract:
  We explore the evolution of supermassive black holes (SMBH) centered in a
circumnuclear disk (CND) as a function of the mass supply from the host galaxy
and considering different star formation laws, which may give rise to a
self-regulation via the injection of supernova-driven turbulence. A system of
equations describing star formation, black hole accretion and angular momentum
transport was solved for an axisymmetric disk in which the gravitational
potential includes contributions from the black hole, the disk and the hosting
galaxy. Our model extends the framework provided by Kawakatu et al. (2008) by
separately considering the inner and outer part of the disk, and by introducing
a potentially non-linear dependence of the star formation rate on the gas
surface density and the turbulent velocity. The star formation recipes are
calibrated using observational data for NGC 1097, while the accretion model is
based on turbulent viscosity as a source of angular momentum transport in a
thin viscous accretion disk. We find that current data provide no strong
constraint on the star formation recipe, and can in particular not distinguish
between models entirely regulated by the surface density, and models including
a dependence on the turbulent velocity. The evolution of the black hole mass,
on the other hand, strongly depends on the applied star formation law, as well
as the mass supply from the host galaxy. We suggest to explore the star
formation process in local AGN with high-resolution ALMA observations to break
the degeneracy between different star formation models.


title: Coherent exciton dynamics in the presence of underdamped vibrations

abstract:
  Recent ultrafast optical experiments show that excitons in large biological
light-harvesting complexes are coupled to molecular vibration modes. These
high-frequency vibrations will not only affect the optical response, but also
drive the exciton transport. Here, using a model dimer system, the frequency of
the underdamped vibration is shown to have a strong effect on the exciton
dynamics such that quantum coherent oscillations in the system can be present
even in the case of strong noise. Two mechanisms are identified to be
responsible for the enhanced transport efficiency: critical damping due to the
tunable effective strength of the coupling to the bath, and resonance coupling
where the vibrational frequency coincides with the energy gap in the system.
The interplay of these two mechanisms determines parameters responsible for the
most efficient transport, and these optimal control parameters are comparable
to those in realistic light-harvesting complexes. Interestingly, oscillations
in the excitonic coherence at resonance are suppressed in comparison to the
case of an off-resonant vibration.


title:
A Framework for Phasor Measurement Placement in Hybrid State Estimation
  via Gauss-Newton

abstract:
  In this paper, we study the placement of Phasor Measurement Units (PMU) for
enhancing hybrid state estimation via the traditional Gauss-Newton method,
which uses measurements from both PMU devices and Supervisory Control and Data
Acquisition (SCADA) systems. To compare the impact of PMU placements, we
introduce a useful metric which accounts for three important requirements in
power system state estimation: {\it convergence}, {\it observability} and {\it
performance} (COP). Our COP metric can be used to evaluate the estimation
performance and numerical stability of the state estimator, which is later used
to optimize the PMU locations. In particular, we cast the optimal placement
problem in a unified formulation as a semi-definite program (SDP) with integer
variables and constraints that guarantee observability in case of measurements
loss. Last but not least, we propose a relaxation scheme of the original
integer-constrained SDP with randomization techniques, which closely
approximates the optimum deployment. Simulations of the IEEE-30 and 118 systems
corroborate our analysis, showing that the proposed scheme improves the
convergence of the state estimator, while maintaining optimal asymptotic
performance.


title: Involutions of real intervals

abstract:
  This paper shows a simple construction of the continuous involutions of real
intervals in terms of the continuous even functions. We also study the smooth
involutions defined by symmetric equations. Finally, we review some
applications, in particular the characterization of the isochronous potentials
by means of smooth involutions.


title:
X-Shooter GTO: evidence for a population of extremely metal-poor,
  alpha-poor stars

abstract:
  The extremely metal-poor stars are the direct descendants of the first
generation stars. They carry the chemical signature of the pristine Universe at
the time they formed, shortly after the Big Bang. We aim to derive information
about extremely metal-poor stars from their observed spectra. Four extremely
metal-poor stars were selected from the Sloan Digital Sky Survey (SDSS) and
observed during the guaranteed observing time of X-Shooter. The X-Shooter
spectra were analysed using an automatic code, MyGIsFOS, which is based on a
traditional analysis method. It makes use of a synthetic grid computed from
one-dimensional, plane-parallel, hydrostatic model atmospheres. The low
metallicity derived from the SDSS spectra is confirmed here. Two kinds of stars
are found. Two stars are confirmed to be extremely metal-poor, with no evidence
of any enhancement in carbon. The two other stars are strongly enhanced in
carbon. We could not derive iron abundance for one of them, while [Ca/H] is
below -4.5. Two of the stars are members of the rare population of extremely
metal-poor stars low in alpha elements.


title: Cohomology of large semiprojective hyperkaehler varieties

abstract:
  In this paper we survey geometric and arithmetic techniques to study the
cohomology of semiprojective hyperkaehler manifolds including toric
hyperkaehler varieties, Nakajima quiver varieties and moduli spaces of Higgs
bundles on Riemann surfaces. The resulting formulae for their Poincare
polynomials are combinatorial and representation theoretical in nature. In
particular we will look at their Betti numbers and will establish some results
and expectations on their asymptotic shape.


title:
Evolving black hole horizons in General Relativity and alternative
  gravity

abstract:
  From the microscopic point of view, realistic black holes are time-dependent
and the teleological concept of event horizon fails. At present, the apparent
or the trapping horizon seem its best replacements in various areas of black
hole physics. We discuss the known phenomenology of apparent and trapping
horizons for analytical solutions of General Relativity and alternative
theories of gravity. These specific examples (we focus on spherically symmetric
inhomogeneities in a background cosmological spacetime) may be useful as toy
models for research on various aspects of black hole physics.


title: Hedging under an expected loss constraint with small transaction costs

abstract:
  We consider the problem of option hedging in a market with proportional
transaction costs. Since super-replication is very costly in such markets, we
replace perfect hedging with an expected loss constraint. Asymptotic analysis
for small transactions is used to obtain a tractable model. A general expansion
theory is developed using the dynamic programming approach. Explicit formulae
are also obtained in the special cases of an exponential or power loss
function. As a corollary, we retrieve the asymptotics for the exponential
utility indifference price.


title: Unifying neutron stars: getting to GUNS

abstract:
  The variety of the observational appearance of young isolated neutron stars
must find an explanation in the framework of some unifying approach. Nowadays
it is believed that such scenario must include magnetic field decay, the
possibility of magnetic field emergence on a time scale $\lesssim 10^4$--$10^5$
yrs, significant contribution of non-dipolar fields, and appropriate initial
parameter distributions. We present our results on the initial spin period
distribution, and suggest that inconsistences between distributions derived by
different methods for samples with different average ages can uncover field
decay or/and emerging field. We describe a new method to probe the magnetic
field decay in normal pulsars. The method is a modified pulsar current
approach, where we study pulsar flow along the line of increasing
characteristic age for constant field. Our calculations, performed with this
method, can be fitted with an exponential decay for ages in the range $8\times
10^4$--$3.5 \times 10^5$ yrs with a time scale $\sim 5 \times 10^5$ yrs. We
discuss several issues related to the unifying scenario. At first, we note that
the dichotomy, among local thermally emitting neutron stars, between normal
pulsars and the Magnificent Seven remains unexplained. Then we discuss the role
of high-mass X-ray binaries in the unification of neutron star evolution. We
note, that such systems allow to check evolutionary effects on a time scale
longer than what can be probed with normal pulsars alone. We conclude with a
brief discussion of importance of discovering old neutron stars accreting from
the interstellar medium.


title:
Imaging the Conductance of Integer and Fractional Quantum Hall Edge
  States

abstract:
  We measure the conductance of a quantum point contact (QPC) while the biased
tip of a scanning probe microscope induces a depleted region in the electron
gas underneath. At finite magnetic field we find plateaus in the real-space
maps of the conductance as a function of tip position at integer
(\nu=1,2,3,4,6,8) and fractional (\nu=1/3,2/3,5/3,4/5) values of transmission.
They resemble theoretically predicted compressible and incompressible stripes
of quantum Hall edge states. The scanning tip allows us to shift the
constriction limiting the conductance in real space over distances of many
microns. The resulting stripes of integer and fractional filling factors are
rugged on the micron scale, i.e. on a scale much smaller than the zero-field
elastic mean free path of the electrons. Our experiments demonstrate that
microscopic inhomogeneities are relevant even in high-quality samples and lead
to locally strongly fluctuating widths of incompressible regions even down to
their complete suppression for certain tip positions. The macroscopic
quantization of the Hall resistance measured experimentally in a non-local
contact configuration survives in the presence of these inhomogeneities, and
the relevant local energy scale for the \nu=2 state turns out to be independent
of tip position.


title:
Better Bounds for Online $k$-Frame Throughput Maximization in Network
  Switches

abstract:
  We consider a variant of the online buffer management problem in network
switches, called the $k$-frame throughput maximization problem ($k$-FTM). This
problem models the situation where a large frame is fragmented into $k$ packets
and transmitted through the Internet, and the receiver can reconstruct the
frame only if he/she accepts all the $k$ packets. Kesselman et al.\ introduced
this problem and showed that its competitive ratio is unbounded even when
$k=2$. They also introduced an "order-respecting" variant of $k$-FTM, called
$k$-OFTM, where inputs are restricted in some natural way. They proposed an
online algorithm and showed that its competitive ratio is at most
$\frac{2kB}{\lfloor B/k \rfloor} + k$ for any $B \ge k$, where $B$ is the size
of the buffer. They also gave a lower bound of $\frac{B}{\lfloor 2B/k \rfloor}$
for deterministic online algorithms when $2B \geq k$ and $k$ is a power of 2.
In this paper, we improve upper and lower bounds on the competitive ratio of
$k$-OFTM. Our main result is to improve an upper bound of $O(k^{2})$ by
Kesselman et al.\ to $\frac{5B + \lfloor B/k \rfloor - 4}{\lfloor B/2k \rfloor}
= O(k)$ for $B\geq 2k$. Note that this upper bound is tight up to a
multiplicative constant factor since the lower bound given by Kesselman et al.\
is $\Omega(k)$. We also give two lower bounds. First we give a lower bound of
$\frac{2B}{\lfloor {B/(k-1)} \rfloor} + 1$ on the competitive ratio of
deterministic online algorithms for any $k \geq 2$ and any $B \geq k-1$, which
improves the previous lower bound of $\frac{B}{\lfloor 2B/k \rfloor}$ by a
factor of almost four. Next, we present the first nontrivial lower bound on the
competitive ratio of randomized algorithms. Specifically, we give a lower bound
of $k-1$ against an oblivious adversary for any $k \geq 3$ and any $B$.


title: A higher limit approach to homology theories

abstract:
  A lot of well-known functors such as group homology, cyclic homology of
algebras can be described as limits of certain simply defined functors over
categories of presentations. In this paper, we develop technique for the
description of the higher limits over categories of presentations and show that
certain homological functors can be described in this way. In particular, we
give a description of Hochschild homology and the derived functors of tensor,
symmetric and exterior powers in the sense of Dold and Puppe as higher limits.


title:
Parameterized Norm and Parameterized Fixed-Point Theorem by Using Fuzzy
  Soft Set Theory

abstract:
  From last decade, when Molodtsov introduced the theory of soft set as a new
approach to deal with uncertainties, until now this theory was considered
sharply by a fair number of researchers. Combination of fuzzy set theory and
soft set theory, called fuzzy soft set theory, by Maji et.al opened a new way
for researchers whose frame work of study is soft sets and fuzzy sets. Although
published papers in this area have considered both application and theoretical
aspects of fuzzy soft set theory, the concept of norm for a fuzzy soft set has
not been studied yet. We begin this paper by introducing fuzzy soft real
numbers, which are needed for study fuzzy soft norm, and then continued by
considering fuzzy soft norm. Fixed-point theorem is also investigated for fuzzy
soft normed spaces.


title: Largest eigenvalues and eigenvectors of band or sparse matrices

abstract:
  In this text, we consider an N by N random matrix X such that all but o(N)
rows of X have W non identically zero entries, the other rows having lass than
$W$ entries (such as, for example, standard or cyclic band matrices). We always
suppose that 1 << W << N. We first prove that if the entries are independent,
centered, have variance one, satisfy a certain tail upper-bound condition and W
>> (\log N)^{6(1+\alpha)}, where \alpha is a positive parameter depending on
the distribution of the entries, then the largest eigenvalue of X/\sqrt{W}
converges to the upper bound of its limit spectral distribution, that is 2, as
for Wigner matrices. This extends some previous results by Khorunzhiy and Sodin
where less hypotheses were made on W, but more hypotheses were made about the
law of the entries and the structure of the matrix. Then, under the same
hypotheses, we prove a delocalization result for the eigenvectors of X,
precisely that most of them cannot be essentially localized on less than
W/\log(N) entries. This lower bound on the localization length has to be
compared to the recent result by Steinerberger, which states that either the
localization length in the edge is << W^{7/5} or there is strong interaction
between two eigenvectors in an interval of length W^{7/5}.


title: Quantum Walks in artificial electric and gravitational Fields

abstract:
  The continuous limit of quantum walks (QWs) on the line is revisited through
a recently developed method. In all cases but one, the limit coincides with the
dynamics of a Dirac fermion coupled to an artificial electric and/or
relativistic gravitational field. All results are carefully discussed and
illustrated by numerical simulations.

categories: quant-ph cs.IT gr-qc math-ph math.IT math.MP


title: Remarks on mechanical approach to observable Universe

abstract:
  We consider the Universe deep inside the cell of uniformity. At these scales,
the Universe is filled with inhomogeneously distributed discrete structures
(galaxies, groups and clusters of galaxies), which perturb the background
Friedmann model. Here, the mechanical approach (Eingorn & Zhuk, 2012) is the
most appropriate to describe the dynamics of the inhomogeneities which is
defined, on the one hand, by gravitational potentials of inhomogeneities and,
on the other hand, by the cosmological expansion of the Universe. In this
paper, we present additional arguments in favor of this approach. First, we
estimate the size of the cell of uniformity. With the help of the standard
methods of statistical physics and for the galaxies of the type of the Milky
Way and Andromeda, we get that it is of the order of 190 Mpc which is rather
close to observations. Then, we show that the nonrelativistic approximation
(with respect to the peculiar velocities) is valid for $z \lesssim 10$, i.e.
approximately for 13 billion years from the present moment. We consider scalar
perturbations and, within the $\Lambda$CDM model, justify the main equations.
Moreover, we demonstrate that radiation can be naturally incorporated into our
scheme. This emphasizes the viability of our approach. This approach gives a
possibility to analyze different cosmological models and compare them with the
observable Universe. For example, we indicate some problematic aspects of the
spatially flat models. Such models require a rather specific distribution of
the inhomogeneities to get a finite potential at any points outside gravitating
masses. We also criticize the application of the Schwarzschild-de Sitter
solution to the description of the motion of test bodies on the cosmological
background.


title: $Z_N$ twisted orbifold models with magnetic flux

abstract:
  We propose new backgrounds of extra dimensions to lead to four-dimensional
chiral models with three generations of matter fermions, that is $T^2/Z_N$
twisted orbifolds with magnetic fluxes. We consider gauge theory on
six-dimensional space-time, which contains the $T^2/Z_N$ orbifold with magnetic
flux, Scherk-Schwarz phases and Wilson line phases. We classify all the
possible Scherk-Schwarz and Wilson line phases on $T^2/Z_N$ orbifolds with
magnetic fluxes. The behavior of zero modes is studied. We derive the number of
zero modes for each eigenvalue of the $Z_N$ twist, showing explicitly examples
of wave functions. We also investigate Kaluza-Klein mode functions and mass
spectra.


title: The evolving polarised jet of black hole candidate Swift J1745-26

abstract:
  Swift J1745-26 is an X-ray binary towards the Galactic Centre that was
detected when it went into outburst in September 2012. This source is thought
to be one of a growing number of sources that display "failed outbursts", in
which the self-absorbed radio jets of the transient source are never fully
quenched and the thermal emission from the geometrically-thin inner accretion
disk never fully dominates the X-ray flux. We present multifrequency data from
the Very Large Array, Australia Telescope Compact Array and Karoo Array
Telescope (KAT- 7) radio arrays, spanning the entire period of the outburst.
Our rich data set exposes radio emission that displays a high level of large
scale variability compared to the X-ray emission and deviations from the
standard radio--X-ray correlation that are indicative of an unstable jet and
confirm the outburst's transition from the canonical hard state to an
intermediate state. We also observe steepening of the spectral index and an
increase of the linear polarization to a large fraction (~50%) of the total
flux, as well as a rotation of the electric vector position angle. These are
consistent with a transformation from a self-absorbed compact jet to
optically-thin ejecta -- the first time such a discrete ejection has been
observed in a failed outburst -- and may imply a complex magnetic field
geometry.


title:
A finite axiomatization of conditional independence and inclusion
  dependencies

abstract:
  We present a complete finite axiomatization of the unrestricted implication
problem for inclusion and conditional independence atoms in the context of
dependence logic. For databases, our result implies a finite axiomatization of
the unrestricted implication problem for inclusion, functional, and embedded
multivalued dependencies in the unirelational case.


title:
On the equivalence of two expected average cost criteria for semi-
  Markov control processes

abstract:
  The two expected average costs used in the theory of semi-Markov control
processes with a Borel state space are considered. Under some stochastic
stability conditions, we prove that the two criteria are equivalent in the
sense that they lead to the same optimality equation.


title:
Multiplexed readout of MMC detector arrays using non-hysteretic
  rf-SQUIDs

abstract:
  Metallic magnetic calorimeters (MMCs) are widely used for various experiments
in fields ranging from atomic and nuclear physics to x-ray spectroscopy,
laboratory astrophysics or material science. Whereas in previous experiments
single pixel detectors or small arrays have been used, for future applications
large arrays are needed. Therefore, suitable multiplexing techniques for MMC
arrays are currently under development. A promising approach for the readout of
large arrays is the microwave SQUID multiplexer that operates in the frequency
domain and that employs non-hysteretic rf-SQUIDs to transduce the detector
signals into a frequency shift of high $Q$ resonators which can be monitored by
using standard microwave measurement techniques. In this paper we discuss the
design and the expected performance of a recently developed and fabricated 64
pixel detector array with integrated microwave SQUID multiplexer. First
experimental data were obtained characterizing dc-SQUIDs with virtually
identical washer design.


title: The Zero-Undetected-Error Capacity Approaches the Sperner Capacity

abstract:
  Ahlswede, Cai, and Zhang proved that, in the noise-free limit, the
zero-undetected-error capacity is lower bounded by the Sperner capacity of the
channel graph, and they conjectured equality. Here we derive an upper bound
that proves the conjecture.


title:
Novel behaviors of monolayer quantum gases on Graphene, Graphane and
  Fluorographene

abstract:
  This article discusses the behavior of submonolayer quantum films (He and H2)
on graphene and newly discovered surfaces that are derived from graphene. Among
these substrates are graphane (abbreviated GH), which has an H atom bonded to
each C atom, and fluorographene (GF). For the graphite case, extensive
experimental and theoretical investigations have revealed that the phase
diagrams of the bose gases 4He and para-H2 are qualitatively similar, differing
primarily in a higher characteristic temperature scale for H2 than for He. The
phase behaviors of these films on one side of pristine graphene, or both sides
of free-standing graphene, are expected to be similar to those on graphite. We
point out the possibility of novel phenomena in adsorption on graphene related
to the large flexibility of the graphene sheet, to the non--negligible
interaction between atoms adsorbed on opposite sides of the sheet and to the
perturbation effect of the adsorbed layer on the Dirac electrons. In contrast,
the behaviors predicted on GF and GH surfaces are very different from those on
graphite, a result of the different corrugation, i.e., the lateral variation of
the potential experienced by these gases. As a result of this novel geometry
and potential, distinct properties are observed. For example, the 4He film's
ground-state on graphite is a two-dimensional (2D) crystal commensurate with
the substrate; on GF and GH, instead, it is predicted to be an anisotropic
superfluid. On GF the anisotropy is so extreme that the roton excitations are
very anisotropic, as if the bosons are moving in a multiconnected space along
the bonds of a honeycomb lattice. Such a novel phase has not been predicted or
observed previously on any substrate. Also, in the case of 3He the film's
ground-state is a fluid, thus offering the possibility of studying an
anisotropic Fermi fluid with a tunable density.


title:
Developing a Robust Migration Workflow for Preserving and Curating
  Hand-held Media

abstract:
  Many memory institutions hold large collections of hand-held media, which can
comprise hundreds of terabytes of data spread over many thousands of
data-carriers. Many of these carriers are at risk of significant physical
degradation over time, depending on their composition. Unfortunately, handling
them manually is enormously time consuming and so a full and frequent
evaluation of their condition is extremely expensive. It is, therefore,
important to develop scalable processes for stabilizing them onto backed-up
online storage where they can be subject to highquality digital preservation
management. This goes hand in hand with the need to establish efficient,
standardized ways of recording metadata and to deal with defective
data-carriers. This paper discusses processing approaches, workflows, technical
set-up, software solutions and touches on staffing needs for the stabilization
process. We have experimented with different disk copying robots, defined our
metadata, and addressed storage issues to scale stabilization to the vast
quantities of digital objects on hand-held data-carriers that need to be
preserved. Working closely with the content curators, we have been able to
build a robust data migration workflow and have stabilized over 16 terabytes of
data in a scalable and economical manner.


title:
A multi-wavelength view of AB Dor's outer atmosphere - Simultaneous
  X-ray and optical spectroscopy at high cadence

abstract:
  We study the chromosphere and corona of the ultra-fast rotator AB Dor A at
high temporal and spectral resolution using simultaneous observations with
XMM-Newton in the X-rays, VLT/UVES in the optical, and the ATCA in the radio.
Our optical spectra have a resolving power of ~50 000 with a time cadence of ~1
min. Our observations continuously cover more than one rotational period and
include both quiescent periods and three flaring events of different strengths.
From the X-ray observations we investigated the variations in coronal
temperature, emission measure, densities, and abundance. We interpreted our
data in terms of a loop model. From the optical data we characterise the
flaring chromospheric material using numerous emission lines that appear in the
course of the flares. A detailed analysis of the line shapes and line centres
allowed us to infer physical characteristics of the flaring chromosphere and to
coarsely localise the flare event on the star. We specifically used the optical
high-cadence spectra to demonstrate that both, turbulent and Stark broadening
are present during the first ten minutes of the first flare. Also, in the first
few minutes of this flare, we find short-lived (one to several minutes)
emission subcomponents in the H{\alpha} and Ca ii K lines, which we interpret
as flare-connected shocks owing to their high intrinsic velocities. Combining
the space-based data with the results of our optical spectroscopy, we derive
flare-filling factors. Finally, comparing X-ray, optical broadband, and line
emission, we find a correlation for two of the three flaring events, while
there is no clear correlation for one event. Also, we do not find any
correlation of the radio data to any other observed data.


title: MHD waves in two-dimensional prominences embedded in coronal arcades

abstract:
  Solar prominence models used so far in the analysis of MHD waves in such
structures are quite elementary. In this work, we calculate numerically
magnetohydrostatic models in two-dimensional configurations under the presence
of gravity. Our interest is in models that connect the magnetic field to the
photosphere and include an overlying arcade. The method used here is based on a
relaxation process and requires solving the time-dependent nonlinear ideal MHD
equations. Once a prominence model is obtained, we investigate the properties
of MHD waves superimposed on the structure. We concentrate on motions purely
two-dimensional neglecting propagation in the ignorable direction. We
demonstrate how by using different numerical tools we can determine the period
of oscillation of stable waves. We find that vertical oscillations, linked to
fast MHD waves, are always stable and have periods in the 4-10 min range.
Longitudinal oscillations, related to slow magnetoacoustic-gravity waves, have
longer periods in the range of 28-40 min. These longitudinal oscillations are
strongly influenced by the gravity force and become unstable for short magnetic
arcades.


title:
On the continuity of the probabilistic representation of a semilinear
  Neumann-Dirichlet problem

abstract:
  In this article we prove the continuity of the deterministic function
$u:[0,T]\times \mathcal{\bar{D}}\rightarrow \mathbb{R}$, defined by
$u(t,x):=Y_{t}^{t,x}$, where the process $(Y_{s}^{t,x})_{s\in[t,T]}$ is given
by the generalized multivalued backward stochastic differential equation:
\begin{equation*} \left\{ \begin{array}{l} -dY_{s}^{t,x}+\partial
\varphi(Y_{s}^{t,x})ds+\partial\psi(Y_{s}^{t,x})dA_{s}^{t,x}\ni
f(s,X_{s}^{t,x},Y_{s}^{t,x})ds \\
\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;+g(s,X_{s}^{t,x},Y_{s}^{t,x})dA_{s}^{t,x}-Z_{s}^{t,x}dW_{s}~,\;t\leq
s < T, \\ {Y_{T}=h(X_{T}^{t,x}).} \end{array} \right. \end{equation*} The
process $(X_{s}^{t,x},A_{s}^{t,x})_{s\geq t}$ is the solution of a stochastic
differential equation with reflecting boundary conditions.


title: Dynamic optimization of metabolic networks coupled with gene expression

abstract:
  The regulation of metabolic activity by tuning enzyme expression levels is
crucial to sustain cellular growth in changing environments. Metabolic networks
are often studied at steady state using constraint-based models and
optimization techniques. However, metabolic adaptations driven by changes in
gene expression cannot be analyzed by steady state models, as these do not
account for temporal changes in biomass composition. Here we present a dynamic
optimization framework that integrates the metabolic network with the dynamics
of biomass production and composition, explicitly taking into account enzyme
production costs and enzymatic capacity. In contrast to the established dynamic
flux balance analysis, our approach allows predicting dynamic changes in both
the metabolic fluxes and the biomass composition during metabolic adaptations.
We applied our algorithm in two case studies: a minimal nutrient uptake
network, and an abstraction of core metabolic processes in bacteria. In the
minimal model, we show that the optimized uptake rates reproduce the empirical
Monod growth for bacterial cultures. For the network of core metabolic
processes, the dynamic optimization algorithm predicted commonly observed
metabolic adaptations, such as a diauxic switch with a preference ranking for
different nutrients, re-utilization of waste products after depletion of the
original substrate, and metabolic adaptation to an impending nutrient
depletion. These examples illustrate how dynamic adaptations of enzyme
expression can be predicted solely from an optimization principle.


title:
Classification of degree three polynomial solutions to the
  Polubarinova-Galin equation

abstract:
  The Polubarinova-Galin equation is derived from zero-surface-tension
Hele-Shaw flow driven by injection. In this paper, we classify degree three
polynomial solutions to the Polubarinova-Galin equation into three categories:
global solutions, solutions which can be continued after blow-up and solutions
which cannot be continued after blow-up. The coefficient region of the initial
functions in each category is obtained.


title: Improving Query Expansion Using WordNet

abstract:
  This study proposes a new way of using WordNet for Query Expansion (QE). We
choose candidate expansion terms, as usual, from a set of pseudo relevant
documents; however, the usefulness of these terms is measured based on their
definitions provided in a hand-crafted lexical resource like WordNet.
Experiments with a number of standard TREC collections show that this method
outperforms existing WordNet based methods. It also compares favorably with
established QE methods such as KLD and RM3. Leveraging earlier work in which a
combination of QE methods was found to outperform each individual method (as
well as other well-known QE methods), we next propose a combination-based QE
method that takes into account three different aspects of a candidate expansion
term's usefulness: (i) its distribution in the pseudo relevant documents and in
the target corpus, (ii) its statistical association with query terms, and (iii)
its semantic relation with the query, as determined by the overlap between the
WordNet definitions of the term and query terms. This combination of diverse
sources of information appears to work well on a number of test collections,
viz., TREC123, TREC5, TREC678, TREC robust new and TREC910 collections, and
yields significant improvements over competing methods on most of these
collections.


title:
A light Higgs scalar in the NMSSM confronted with the latest LHC Higgs
  data

abstract:
  In the Next-to-Minimal Supersymemtric Standard Model (NMSSM), one of the
neutral Higgs scalars (CP-even or CP-odd) may be lighter than half of the
SM-like Higgs boson. In this case, the SM-like Higgs boson h can decay into
such a light scalar pair and consequently the diphoton and ZZ signal rates at
the LHC will be suppressed. In this work, we examine the constraints of the
latest LHC Higgs data on such a possibility. We perform a comprehensive scan
over the parameter space of the NMSSM by considering various experimental
constraints and find that the LHC Higgs data can readily constrain the
parameter space and the properties of the light scalar, e.g., at 3 $\sigma$
level this light scalar should be highly singlet dominant and the branching
ratio of the SM-like Higgs boson decay into the scalar pair should be less than
about 30%. Also we investigate the detection of this scalar at various
colliders. Through a detailed Monte Carlo simulation we find that under the
constraints of the current Higgs data this light scalar can be accessible at
the LHC-14 with an integrated luminosity over 300 fb$^{-1}$.


title: Multicomponent Modified Boltzmann Equation and Thermalization

abstract:
  The existence of stationary distributions in a multicomponent Boltzmann
equation using a non-additive kinetic energy composition rule for binary
collisions is discussed. It is found that detailed balance is not achieved when
-- in contrast to the case of a single rule -- several different composition
rules are considered. The long-time behaviour of a simple momentum space model
is explored numerically: saturating, heating and cooling solutions are
presented.


title: $q\bar q$-potential: a critical reappraisal

abstract:
  We show how it is possible to define and compute the potential between $q$
and $\bar q$ external sources in the singlet and octet (adjoint) representation
of the colour group.


title:
HetNets and Massive MIMO: Modeling, Potential Gains, and Performance
  Analysis

abstract:
  We consider a heterogeneous cellular network (HetNet) where a macrocell tier
with a large antenna array base station (BS) is overlaid with a dense tier of
small cells (SCs). We investigate the potential benefits of incorporating a
massive MIMO BS in a TDD-based HetNet and we provide analytical expressions for
the coverage probability and the area spectral efficiency using stochastic
geometry. The duplexing mode in which SCs should operate during uplink
macrocell transmissions is optimized. Furthermore, we consider a reverse TDD
scheme, in which the massive MIMO BS can estimate the SC interference
covariance matrix. Our results suggest that significant throughput improvement
can be achieved by exploiting interference nulling and implicit coordination
across the tiers due to flexible and asymmetric TDD operation.


title: Limits to the power density of very large wind farms

abstract:
  A simple analysis is presented concerning an upper limit of the power density
(power per unit land area) of a very large wind farm located at the bottom of a
fully developed boundary layer. The analysis suggests that the limit of the
power density is about 0.38 times $\tau_{w0}U_{F0}$, where $\tau_{w0}$ is the
natural shear stress on the ground (that is observed before constructing the
wind farm) and $U_{F0}$ is the natural or undisturbed wind speed averaged
across the height of the farm to be constructed. Importantly, this implies that
the maximum extractable power from such a very large wind farm will not be
proportional to the cubic of the wind speed at the farm height, or even the
farm height itself, but be proportional to $U_{F0}$.


title:
Cryptanalysis and Improvement of Yan et al.'s Biometric-based
  authentication scheme for Telecare Medicine Information Systems

abstract:
  Remote user authentication is desirable for a Telecare medicine information
system (TMIS) to verify the correctness of remote users and server over the
insecure channel. We propose an authentication scheme for TMIS.


title: Differentiation of sets - The general case

abstract:
  In recent work by Khmaladze and Weil (2008) and by Einmahl and Khmaladze
(2011), limit theorems were established for local empirical processes near the
boundary of compact convex sets $K$ in $\R$. The limit processes were shown to
live on the normal cylinder $\Sigma$ of $K$, respectively on a class of
set-valued derivatives in $\Sigma$. The latter result was based on the concept
of differentiation of sets at the boundary $\partial K$ of $K$, which was
developed in Khmaladze (2007). Here, we extend the theory of set-valued
derivatives to boundaries $\partial F$ of rather general closed sets $F\subset
\R$, making use of a local Steiner formula for closed sets, established in Hug,
Last and Weil (2004).


title: Strongly continuous semigroups on some Fr\'echet spaces

abstract:
  We prove that for a strongly continuous semigroup on the Fr\'echet space of
all scalar sequences, its generator is a continuous linear operator and that
the semigroup can be represented as exp(tA) where the exponential series
converges in a very strong sense. This solves a problem posed by Conejero.
Moreover, we improve recent results of Albanese, Bonet, and Ricker about
semigroups on strict projective limits of Banach spaces.


title: Clusters, asters and collective oscillations in chemotactic colloids

abstract:
  The creation of synthetic systems that emulate the defining properties of
living matter, such as motility, gradient-sensing, signalling and replication,
is a grand challenge of biomimetics. Such imitations of life crucially contain
active components that transform chemical energy into directed motion. These
artificial realizations of motility point in the direction of a new paradigm in
en- gineering, through the design of emergent behavior by manipulating
properties at the scale of the individual components. Catalytic colloidal
swimmers are a particularly promising example of such systems. Here we present
a comprehensive theoretical description of gradient-sensing of an individual
swimmer, leading controllably to chemotactic or anti-chemotactic behavior, and
use it to construct a framework for studying their collective behavior. We find
that both the positional and the orientational degrees of freedom of the active
colloids can exhibit condensation, signalling formation of clusters and asters.
The kinetics of catalysis introduces a natural control parameter for the range
of the interaction mediated by the diffusing chemical species. For various
regimes in parameter space in the long-ranged limit our system displays precise
analogs to gravitational collapse, plasma oscillations and electrostatic
screening. We present prescriptions for how to tune the surface properties of
the colloids during fabrication to achieve each type of behavior.


title: Tomographic causal analysis of two-qubit states and tomographic discord

abstract:
  We study a behavior of two-qubit states subject to tomographic measurement.
We propose a novel approach to definition of asymmetry in quantum bipartite
state based on its tomographic Shannon entropies. We consider two types of
measurement bases: the first is one that diagonalizes density matrices of
subsystems and is used in a definition of tomographic discord, and the second
is one that maximizes Shannon mutual information and relates to symmetrical
form quantum discord. We show how these approaches relate to each other and
then implement them to the different classes of two-qubit states. Consequently,
new subclasses of X-states are revealed.


title:
Direct Connection between the R_{II} Chain and the Nonautonomous
  Discrete Modified KdV Lattice

abstract:
  The spectral transformation technique for symmetric R_{II} polynomials is
developed. Use of this technique reveals that the nonautonomous discrete
modified KdV (nd-mKdV) lattice is directly connected with the R_{II} chain.
Hankel determinant solutions to the semi-infinite nd-mKdV lattice are also
presented.


title:
Extreme differences between weakly open subsets and convex combinations
  of slices in Banach spaces

abstract:
  We show that every Banach space containing isomorphic copies of $c_0$ can be
equivalently renormed so that every nonempty relatively weakly open subset of
its unit ball has diameter 2 and, however, its unit ball still contains convex
combinations of slices with diameter arbitrarily small, which improves in a
optimal way the known results about the size of this kind of subsets in Banach
spaces.


title: Good Towers of Function Fields

abstract:
  In this paper, we will give an overview of known and new techniques on how
one can obtain explicit equations for candidates of good towers of function
fields. The techniques are founded in modular theory (both the classical
modular theory and the Drinfeld modular theory). In the classical modular
setup, optimal towers can be obtained, while in the Drinfeld modular setup,
good towers over any non-prime field may be found. We illustrate the theory
with several examples, thus explaining some known towers as well as giving new
examples of good explicitly defined towers of function fields.


title:
Cooperation between genetic mutations and phenotypic plasticity can
  bypass the Weismann barrier: The cooperative model of evolution

abstract:
  The Weismann barrier, or the impossibility of inheritance of acquired traits,
comprises a foundation of modern biology, and it has been a major obstacle in
establishing the connection between evolution and ontogenesis. We propose the
cooperative model based on the assumption that evolution is achieved by a
cooperation between genetic mutations and acquired changes (phenotypic
plasticity). It is also assumed in this model that natural selection operates
on phenotypes, rather than genotypes, of individuals, and that the relationship
between phenotypes and genotypes is one-to-many. In the simulations based on
these assumptions, individuals exhibited phenotypic changes in response to an
environmental change, corresponding multiple genetic mutations were
increasingly accumulated in individuals in the population, and phenotypic
plasticity was gradually replaced with genetic mutations. This result suggests
that Lamarck's law of use and disuse can effectively hold without conflicting
the Weismann barrier, and thus evolution can be logically connected with
ontogenesis.


title: A Near Optimal Approximation Algorithm for Vertex-Cover Problem

abstract:
  Recently, there has been increasing interest and progress in improvising the
approximation algorithm for well-known NP-Complete problems, particularly the
approximation algorithm for the Vertex-Cover problem. Here we have proposed a
polynomial time efficient algorithm for vertex-cover problem for more
approximate to the optimal solution, which lead to the worst time complexity
?{\theta}(V 2) and space complexity ?{\theta}(V + E). We show that our proposed
method is more approximate with example and theorem proof. Our algorithm also
induces improvement on previous algorithms for the independent set problem on
graphs of small and high degree.


title: Observing dipolar confinement-induced resonances in waveguides

abstract:
  We develop a theoretical framework for the quasi-low-dimensional
confinement-induced resonances (CIRs) of particles with the arbitrary
three-dimensional two-body interactions, based on the Huang-Yang
pseudopotential and the treatment of Feshbach resonances. Using this new
approach, we analytically obtain some universal properties of dipolar CIRs in
quasi-one-dimensional (1D) waveguides. We also show that the dipolar CIRs can
be induced by tuning the angle between the dipole moments and the waveguide,
which is experimentally observable in quasi-1D Cr and Dy atomic gases. We
expect that these tilting angle induced CIRs will open up a new simpler way to
control the resonant scatterings in quasi-low-dimensional systems.


title:
Next generation KATRIN high precision voltage divider for voltages up to
  65kV

abstract:
  The KATRIN (KArlsruhe TRItium Neutrino) experiment aims to determine the mass
of the electron antineutrino with a sensitivity of 200meV by precisely
measuring the electron spectrum of the tritium beta decay. This will be done by
the use of a retarding spectrometer of the MAC-E-Filter type. To achieve the
desired sensitivity the stability of the retarding potential of -18.6kV has to
be monitored with a precision of 3ppm over at least two months. Since this is
not feasible with commercial devices, two ppm-class high voltage dividers were
developed, following the concept of the standard divider for DC voltages of up
to 100kV of the Physikalisch-Technische Bundesanstalt (PTB). In order to reach
such high accuracies different effects have to be considered. The two most
important ones are the temperature dependence of resistance and leakage
currents, caused by insulators or corona discharges. For the second divider
improvements were made concerning the high-precision resistors and the thermal
design of the divider. The improved resistors are the result of a cooperation
with the manufacturer. The design improvements, the investigation and the
selection of the resistors, the built-in ripple probe and the calibrations at
PTB will be reported here. The latter demonstrated a stability of about
0.1ppm/month over a period of two years.


title:
Synchrotron Lightcurves of blazars in a time-dependent synchrotron-self
  Compton cooling scenario

abstract:
  Blazars emit non-thermal radiation in all frequency bands from radio to
\gamma-rays. Additionally, they often exhibit rapid flaring events at all
frequencies with doubling time scale of the TeV and X-ray flux on the order of
minutes, and such rapid flaring events are hard to explain theoretically. We
explore the effect of the synchrotron-self Compton cooling, which is inherently
time-dependent, leading to a rapid cooling of the electrons. Having discussed
intensively the resulting effects of this cooling scenario on the spectral
energy distribution of blazars in previous papers, the effects of the
time-dependent approach on the synchrotron lightcurve are investigated here.
Taking into account the retardation due to the finite size of the source and
the source geometry, we show that the time-dependent synchrotron-self Compton
(SSC) cooling still has profound effects on the lightcurve compared to the
usual linear (synchrotron and external Compton) cooling terms. This is most
obvious if the SSC cooling takes longer than the light crossing time scale.
Then in most frequency bands the variability time scale is up to an order of
magnitude shorter than under linear cooling conditions. This is yet another
strong indication that the time-dependent approach should be taken into account
for modeling blazar flares from compact emission regions.


title: The role of the probability current for time measurements

abstract:
  Time measurements are routinely preformed in laboratories, nevertheless their
theoretical account presents some difficulties and for actual experiments an
approximate, semiclassical expression is always used. Here, we will discuss
their quantum description with particular emphasis on the role of the
probability current.


title: Approximation of smallest linear tree grammar

abstract:
  A simple linear-time algorithm for constructing a linear context-free tree
grammar of size O(rg + r g log (n/r g))for a given input tree T of size n is
presented, where g is the size of a minimal linear context-free tree grammar
for T, and r is the maximal rank of symbols in T (which is a constant in many
applications). This is the first example of a grammar-based tree compression
algorithm with a good, i.e. logarithmic in terms of the size of the input tree,
approximation ratio. The analysis of the algorithm uses an extension of the
recompression technique from strings to trees.


title: Four-Pose Synthesis of Angle-Symmetric 6R Linkages

abstract:
  We use the recently introduced factorization theory of motion polynomials
over the dual quaternions for the synthesis of closed kinematic loops with six
revolute joints that visit four prescribed poses. Our approach admits either no
or a one-parametric family of solutions. We suggest strategies for picking good
solutions from this family.


title: Long-Term Variations in Sunspot Characteristics

abstract:
  Relative variations in the number of sunspots and sunspot groups in activity
cycles have been analyzed based on data from the Kislovodsk Mountain
Astronomical Station and international indices. The following regularities have
been established: (1) The relative fraction of small sunspots decreases
linearly and that of large sunspots increase with increasing activity cycle
amplitude. (2) The variation in the average number of sunspots in one group has
a trend, and this number decreased from 12 in cycle 19 to 7.5 in cycle 24. (3)
The ratio of the sunspot index (Ri) to the sunspot group number index (Ggr)
varies with a period of about 100 years. (4) An analysis of the sunspot group
number index (Ggr) from 1610 indicates that the Gnevyshev-Ohl rule reverses at
the minimums of secular activity cycles. (5) The ratio of the total sunspot
area to the umbra area shows a long-term variation with a period about eight
cycles and minimum in cycles 16-17. (6) It has been indicated that the magnetic
field intensity and sunspot area in the current cycle are related to the
amplitude of the next activity cycle.


title: On 3-extra connectivity of k-ary n-cubes

abstract:
  Given a graph G, a non-negative integer h and a set of vertices S, the
h-extra connectivity of G is the cardinality of a minimum set S such that G-S
is disconnected and each component of G-S has at least h+1 vertices. The
2-extra connectivity of k-ary n-cube is gotten by Hsieh et al. in [Theoretical
Computer Science, 443 (2012) 63-69]. In this paper, we obtained the h-extra
connectivity of the k-ary n-cube networks for h=3.


title: HOL(y)Hammer: Online ATP Service for HOL Light

abstract:
  HOL(y)Hammer is an online AI/ATP service for formal (computer-understandable)
mathematics encoded in the HOL Light system. The service allows its users to
upload and automatically process an arbitrary formal development (project)
based on HOL Light, and to attack arbitrary conjectures that use the concepts
defined in some of the uploaded projects. For that, the service uses several
automated reasoning systems combined with several premise selection methods
trained on all the project proofs. The projects that are readily available on
the server for such query answering include the recent versions of the
Flyspeck, Multivariate Analysis and Complex Analysis libraries. The service
runs on a 48-CPU server, currently employing in parallel for each task 7 AI/ATP
combinations and 4 decision procedures that contribute to its overall
performance. The system is also available for local installation by interested
users, who can customize it for their own proof development. An Emacs interface
allowing parallel asynchronous queries to the service is also provided. The
overall structure of the service is outlined, problems that arise and their
solutions are discussed, and an initial account of using the system is given.


title:
Tensor renormalization group study of classical XY model on the square
  lattice

abstract:
  Using the tensor renormalization group method based on the higher-order
singular value decom- position, we have studied the thermodynamic properties of
the continuous XY model on the square lattice. The temperature dependence of
the free energy, the internal energy and the specific heat agree with the Monte
Carlo calculations. From the field dependence of the magnetic susceptibility,
we find the Kosterlitz-Thouless transition temperature to be 0.8921 \pm 0.0019,
consistent with the Monte Carlo as well as the high temperature series
expansion results. At the transition temperature, the critical exponent \delta
is estimated as 14.5, close to the analytic value by Kosterlitz.


title:
Doping-induced dimensional crossover and thermopower burst in Nb-doped
  SrTiO$_3$ superlattices

abstract:
  Using advanced ab-initio calculations, we describe the formation and
confinement of a two-dimensional electron gas in short-period ($\simeq$4 nm)
Nb-doped SrTiO$_3$ superlattices as function of Nb doping. We predict complete
two-dimensional confinement for doping concentrations higher than 70%. In
agreement with previous observations, we find a large thermopower enhancement
at room temperature. However, this effect is primarily determined by dilution
of the mobile charge over a multitude of weakly occupied bands. As a general
rule, we conclude that thermopower in similar heterostructures will be more
enhanced by weak, rathern than tight spatial confinement.


title:
Large band offset as driving force of 2-dimensional electron
  confinement: the case of SrTiO$_3$/SrZrO$_3$ interface

abstract:
  Using advanced first-principles calculations we predict that the non-polar
SrTiO$_3$/SrZrO$_3$ (001) interface, designed as either thin SrZrO$_3$ film
deposited on SrTiO$_3$ or short-period (SrTiO$_3$)$_m$/(SrZrO$_3$)$_n$
superlattice, host a 2-dimensionally confined electron gas. Mobile electron
charge due to native impurities, field-effect, or modulation doping remains
tightly trapped at the interface. Key ingredients for this occurrence are a)
the peculiar chemistry of 3d orbitals, b) the large band offset at
titanate-zirconate interface.


title:
Axial Magnetic Effect and Chiral Vortical Effect with free lattice
  chiral fermions

abstract:
  Following the recent work by Braguta et al., we perform an indirect
calculation of the chiral vortical conductivity with free lattice overlap
fermions by measuring the response of the energy flow to the constant axial
magnetic field. We find that the measurements are contaminated by very large
finite-volume artifacts. However, the continuum result for finite-temperature
contribution to the chiral vortical conductivity (T^2/12) is still reproduced
in the limit of infinite volume at fixed temperature.


title:
Re-appearance of McNeil's nebula (V1647 Orionis) and its outburst
  environment

abstract:
  We present a detailed study of McNeil's nebula (V1647 Ori) in its ongoing
outburst phase starting from September 2008 to March 2013. Our 124 nights of
photometric observations were carried out in optical V, R, I and near-infrared
J, H, K bands, and 59 nights of medium resolution spectroscopic observations
were done in 5200 - 9000 Ang wavelength range. All observations were carried
out with 2-m Himalayan Chandra Telescope and 2-m IUCAA Girawali Telescope. Our
observations show that over last four and a half years, V1647 Ori and the
region C near Herbig-Haro object, HH 22A, have been undergoing a slow dimming
at a rate of ~0.04 mag/yr and ~0.05 mag/yr respectively in R-band, which is 6
times slower than the rate during similar stage of V1647 Ori in 2003 outburst.
We detected change in flux distribution over the reflection nebula implying
changes in circumstellar matter distribution between 2003 and 2008 outbursts.
Apart from steady wind of velocity ~350 km/s we detected two episodic magnetic
reconnection driven winds. Forbidden [O I] 6300 Ang and [Fe II] 7155 Ang lines
were also detected implying shock regions probably from jets. We tried to
explain the outburst timescales of V1647 Ori using the standard models of FUors
kind of outburst and found that pure thermal instability models like Bell & Lin
(1994) cannot explain the variations in timescales. In the framework of various
instability models we conclude that one possible reason for sudden ending of
2003 outburst in 2005 November was due to a low density region or gap in the
inner region (~ 1 AU) of the disc.