title:
Effect of Ambient Gas Pressure on the Thermal Exfoliation of Graphite
  Oxide: Tuning the Number of Graphene Sheets

abstract:
  We have investigated the effect of ambient gas pressure (Argon) used during
thermal exfoliation of graphite oxide on the number of graphene sheets in the
resulting graphene. The ambience gas Ar pressures used are 80, 25, 1 atmosphere
and 10-3 as well as 10-5 torr. We have found curious result that the number of
graphene sheets in exfoliated graphene stack is dependent on the applied
pressure for exfoliation of graphite oxide (GO). By lowering the exfoliation
pressure, the numbers of sheets get reduced. The numbers of sheets in
exfoliated graphene stack have been determined by Lorentzian fit of their
respective 002 peak of XRD profile. The numbers of sheets have also been
confirmed with high resolution transmission electron microscopy (HRTEM). The
numbers of sheets in exfoliated graphene stack samples have been found to be
28, 12, 8, 5 and 3 at 80 atm, 25 atm, 1 atm, 10-3 torr and 10-5 torr pressures
respectively. The results of present investigation suggest a simple but
effective method for synthesizing graphene with a specific number of sheets.


title:
Extremal domains for the first eigenvalue in a general Riemannian
  manifold

abstract:
  We prove the existence of extremal domains with small prescribed volume for
the first eigenvalue of the Laplace-Beltrami operator in any compact Riemannian
manifold. This result generalizes a results of F. Pacard and the second author
where the existence of a nondegenerate critical point of the scalar curvature
of the Riemannian manifold was required.


title: The radius of convexity of normalized Bessel functions of the first kind

abstract:
  In this paper we determine the radius of convexity for three kind of
normalized Bessel functions of the first kind. In the mentioned cases the
normalized Bessel functions are starlike-univalent and convex-univalent,
respectively, on the determined disks. The key tools in the proofs of the main
results are some new Mittag-Leffler expansions for quotients of Bessel
functions of the first kind, special properties of the zeros of Bessel
functions of the first kind and their derivative, and the fact that the
smallest positive zeros of some Dini functions are less than the first positive
zero of the Bessel function of the first kind. Moreover, we find the optimal
parameters for which these normalized Bessel functions are convex in the open
unit disk. In addition, we disprove a conjecture of Baricz and Ponnusamy
concerning the convexity of the Bessel function of the first kind.


title:
Influence by small dispersive coal dust particles of different
  fractional consistence on characteristics of iodine air filter at nuclear
  power plant

abstract:
  The main purpose of research is to determine the influence by the small
dispersive coal dust particles of the different fractional consistence on the
technical characteristics of the vertical iodine air filter at nuclear power
plant. The research on the transport properties of the small dispersive coal
dust particles in the granular filtering medium of absorber in the vertical
iodine air filter is completed in the case, when the modeled aerodynamic
conditions are similar to the real aerodynamic conditions. It is shown that the
appearance of the different fractional consistence of small dispersive coal
dust particles with the decreasing dimensions down to the micro and nano sizes
at the action of the air dust aerosol stream normally results in a significant
change of distribution of the small dispersive coal dust particles masses in
the granular filtering medium of an absorber in the vertical iodine air filter,
changing the vertical iodine air filter aerodynamic characteristics. The
precise characterization of the aerodynamic resistance of a model of the
vertical iodine air filter is completed. The comparative analysis of the
technical characteristics of the vertical and horizontal iodine air filters is
also made.

categories: physics.ao-ph cond-mat.mtrl-sci cond-mat.soft physics.chem-ph physics.ins-det


title:
Existence of piecewise weak solutions of a discrete Cucker-Smale's
  flocking model with a singular communication weight

abstract:
  We prove existence of global $C^1$ piecewise weak solutions for the discrete
Cucker-Smale's flocking model with the communication weight
$\psi(s)=s^{-\alpha}, 0<\alpha<1.$ We also discuss the possibility of finite in
time alignment of the velocities of the particles.


title:
Impact of Pointing Errors on the Performance of Mixed RF/FSO Dual-Hop
  Transmission Systems

abstract:
  In this work, the performance analysis of a dual-hop relay transmission
system composed of asymmetric radio-frequency (RF)/free-space optical (FSO)
links with pointing errors is presented. More specifically, we build on the
system model presented in [1] to derive new exact closed-form expressions for
the cumulative distribution function, probability density function, moment
generating function, and moments of the end-to-end signal-to-noise ratio in
terms of the Meijer's G function. We then capitalize on these results to offer
new exact closed-form expressions for the higher-order amount of fading,
average error rate for binary and M-ary modulation schemes, and the ergodic
capacity, all in terms of Meijer's G functions. Our new analytical results were
also verified via computer-based Monte-Carlo simulation results.


title:
Observation of large positive magnetoresistance and its sign reversal in
  GdRhGe

abstract:
  Magnetic properties, heat capacity and magnetoresistance (MR) of
polycrystalline GdRhGe are investigated. It shows two antiferromagnetic
transitions, one at T1=31.8 K and the other at T2=24 K, and field induced
metamagnetic transition over a wide temperature range. The ac susceptibility
data reveal that the transition at 24 K is not simple antiferromagnetic.
Dominant contributions to the heat capacity and the resistivity have been
identified. MR is found to show sign reversal just below T1 and attains a large
positive value of 48% at 2 K for 50 kOe. Like MR, the isothermal magnetic
entropy change also undergoes a sign reversal as the temperature is varied,
indicating a change of the magnetic structure and the moment amplitude in
determining these properties.


title:
Quantitative Study of Different Forms of Geometrical Scaling in Deep
  Inelastic Scattering at HERA

abstract:
  We use recently proposed method of ratios to assess the quality of
geometrical scaling in deep inelastic scattering for different forms of the
saturation scale. We consider original form of geometrical scaling (motivated
by the Balitski-Kovchegov (BK) equation with fixed coupling) studied in more
detail in our previous paper, and four new hypotheses: phenomenologically
motivated case with $Q^2$ dependent exponent $\lambda$ that governs small $x$
dependence of the saturation scale, two versions of scaling (running coupling 1
and 2) that follow from the BK equation with running coupling, and diffusive
scaling suggested by the QCD evolution equation beyond mean field
approximation. It turns out that more sophisticated scenarios: running coupling
scaling and diffusive scaling are disfavored by the combined HERA data on
$e^+p$ deep inelastic structure function $F_2$.


title: The Copenhagen Interpretation as an Emergent Phenomenon

abstract:
  The Copenhagen interpretation has been remarkably successful but seems at
odds with the underlying linearity of quantum mechanics. We show how it can
emerge in a simple way from the underlying microscopic quantum world governed
by Schrodinger's equation without the need for observers or their brains. In
order to achieve this, we assemble pieces of various pre-existing ideas.
Firstly, we adopt a relational approach and use the eigenvectors of the reduced
density matrix of a quantum sub-system, or equivalently the Schmidt
decomposition, to define the `internal state' of a sub-system. Previous work
has identified serious objections to such an interpretation because it
apparently leads to macroscopic superpositions and physically unacceptable
instabilities near degeneracies. We show that both these problems are solved if
the sub-system consists of a large number of coarse grained degrees of freedom
as one expects in order to make contact with the classical world. We further
argue that coarse graining is a necessary ingredient because measuring devices
have both finite spatial and temporal resolutions. What results is an
interpretation in which both decoherence and coarse graining play key roles and
from which the rules of the Copenhagen interpretation are seen to emerge in
realistic situations that include the measurement of the position of a particle
and a decay process.


title: Grothendieck Rings of Theories of Modules

abstract:
  The model-theoretic Grothendieck ring of a first order structure, as defined
by Krajic\v{e}k and Scanlon, captures some combinatorial properties of the
definable subsets of finite powers of the structure. In this paper we compute
the Grothendieck ring, $K_0(M_\mathcal R)$, of a right $R$-module $M$, where
$\mathcal R$ is any unital ring. As a corollary we prove a conjecture of Prest
that $K_0(M)$ is non-trivial, whenever $M$ is non-zero. The main proof uses
various techniques from the homology theory of simplicial complexes.


title:
Spontaneous Mirror Symmetry Breaking in the Limited Enantioselective
  Autocatalysis Model: Abyssal Hydrothermal Vents as Scenario for the Emergence
  of Chirality in Prebiotic Chemistry

abstract:
  The emergence of chirality in enantioselective autocatalysis for compounds
unable to transform according to the Frank-like reaction network is discussed
with respect to the controversial limited enantioselectivity (LES) model
composed of coupled enantioselective and non-enantioselective autocatalyses.
The LES model cannot lead to spontaneous mirror symmetry breaking (SMSB) either
in closed systems with a homogeneous temperature distribution nor in closed
systems with a stationary non-uniform temperature distribution. However,
simulations of chemical kinetics in a two-compartment model demonstrate that
SMSB may occur if both autocatalytic reactions are spatially separated at
different temperatures in different compartments but coupled under the action
of a continous internal flow. In such conditions the system can evolve, for
certain reaction and system parameters, towards a chiral stationary state,
i.e., the system is able to reach a bifurcation point leading to SMSB.
Numerical simulations using reasonable chemical parameters suggest that an
adequate scenario for such a SMSB would be that of abyssal hydrothermal vents,
by virtue of the typical temperature gradients found there and the role of
inorganic solids mediating chemical reactions in an enzyme-like role.


title:
Eigenvalue statistics of reduced density matrix during driving and
  relaxation

abstract:
  We study a subsystem of an isolated one-dimensional correlated metal when it
is driven by a steady electric field or when it relaxes after driving. We
obtain numerically exact reduced density matrix $\rho$ for subsystems which are
sufficiently large to give significant eigenvalue statistics and spectra of
$\log(\rho)$. We show that both for generic as well as for the integrable model
the statistics follows the universality of Gaussian unitary and orthogonal
ensembles for driven and equilibrium systems, respectively. Moreover, the
spectra of modestly driven subsystems are well described by the Gibbs thermal
distribution with the entropy determined by the time-dependent energy only.


title:
On the effects of the evolution of microbial mats and land plants on the
  Earth as a planet. Photometric and spectroscopic light curves of paleo-Earths

abstract:
  Understanding the spectral and photometric variability of the Earth and the
rest of the solar system planets has become of the utmost importance for the
future characterization of rocky exoplanets. As this is not only interesting at
present times but also along the planetary evolution, we studied the effect
that the evolution of microbial mats and plants over land has had on the way
our planet looks from afar. As life evolved, continental surfaces changed
gradually and non- uniformly from deserts through microbial mats to land
plants, modifying the reflective properties of the ground and most probably the
distribution of moisture and cloudiness. Here, we used a radiative transfer
model of the Earth, together with geological paleo-records of the continental
distribution and a reconstructed cloud distribution, to simulate the visible
and near-IR radiation reflected by our planet as a function of Earth's
rotation. We found that the evolution from deserts to microbial mats and to
land plants produces detectable changes in the globally-averaged Earth's
reflectance. The variability of each surface type is located in different bands
and can induce reflectance changes of up to 40% in period of hours. We conclude
that using photometric observations of an Earth- like planet at different
photometric bands, it would be possible to discriminate between different
surface types. While recent literature proposes the red edge feature of
vegetation near 0.7 {\mu}m as a signature for land plants, observations in
near-IR bands can be equally or even better suited for this purpose.


title:
The Robust Digital Image Watermarking using Quantization and Fuzzy Logic
  Approach in DWT Domain

abstract:
  In this paper a novel approach to embed watermark into the host image using
quantization with the help of Dynamic Fuzzy Inference System (DFIS) is
proposed. The cover image is decomposed up to 3- levels using quantization and
Discrete Wavelet Transform (DWT). A bitmap of size 64x64 pixels is embedded
into the host image using DFIS rule base. The DFIS is utilized to generate the
watermark weighting function to embed the imperceptible watermark. The
implemented watermarking algorithm is imperceptible and robust to some normal
attacks such as JPEG Compression, salt&pepper noise, median filtering, rotation
and cropping.
  Keywords: Watermark, Quantization, Dynamic Fuzzy Inference System,
Imperceptible, Robust, JPEG Compression, Cropping.


title:
Nonexistence of the final first integral in the Zipoy-Voorhees
  space-time

abstract:
  We show that the geodesic motion in the Zipoy-Voorhees space-time is not
Liouville integrable, in that there does not exist an additional first integral
meromorphic in the phase space variables.


title: A special class of Hankel determinants

abstract:
  In this expository paper we compute Hankel determinants of some sequences
whose generating functions are given by C-fractions and derive orthogonality
properties for associated polynomials.


title:
Crystal structure of dense pseudo-cubic boron allotrope, pc-B52, by
  powder X-ray diffraction

abstract:
  During past years, a number of reports have been published on synthesis of
tetragonal allotrope of boron, t-B52 phase. However, no unambiguous
characterization of the crystal structure has been performed to the present
time, while remarkable variation of the a/c lattice-parameter ratio raises
strong doubts about its uniqueness. Here the Rietveld refinement of the crystal
structure of the high pressure - high temperature boron phase synthesized by a
direct solid-state transformation of rhombohedral beta-B106 at 20 GPa and 2500
K has been reported for the first time. Although this boron allotrope belongs
to the t-B52 type, its structure can be considered as pseudo-cubic with the a/c
ratio of sqr(2).


title:
Shallow and diffuse spin-orbit potential for proton elastic scattering
  from neutron-rich helium isotopes at 71 MeV/nucleon

abstract:
  Vector analyzing powers for proton elastic scattering from 8He at 71
MeV/nucleon have been measured using a solid polarized proton target operated
in a low magnetic field of 0.1 T. The spin-orbit potential obtained from a
phenomenological optical model analysis is found to be significantly shallower
and more diffuse than the global systematics of stable nuclei, which is an
indication that the spin-orbit potential is modified for scattering involving
neutron-rich nuclei. A close similarity between the matter radius and the
root-mean-square radius of the spin-orbit potential is also identified.


title: The proper geometric dimension of the mapping class group

abstract:
  We show that the mapping class group of a closed surface admits a cocompact
classifying space for proper actions of dimension equal to its virtual
cohomological dimension.


title: Recurrences for some sequences of binomial sums II: A simpler approach

abstract:
  Due to some results by John P. D Angelo and Dusty Grundmeier about CR-
mappings the main results of my 2001 paper about recurrences for some sequences
of binomial sums can be simplified.


title:
Iron porphyrin molecules on Cu(001): Influence of adlayers and ligands
  on the magnetic properties

abstract:
  The structural and magnetic properties of Fe octaethylporphyrin (OEP)
molecules on Cu(001) have been investigated by means of density functional
theory (DFT) methods and X-ray absorption spectroscopy. The molecules have been
adsorbed on the bare metal surface and on an oxygen-covered surface, which
shows a $\sqrt{2}\times2\sqrt{2}R45^{\circ}$ reconstruction. In order to allow
for a direct comparison between magnetic moments obtained from sum-rule
analysis and DFT we calculate the dipolar term $7< T_z>$, which is also
important in view of the magnetic anisotropy of the molecule. The measured
X-ray magnetic circular dichroism shows a strong dependence on the photon
incidence angle, which we could relate to a huge value of $7< T_z>$, e.g. on
Cu(001) $7< T_z>$ amounts to -2.07\,\mbo{} for normal incidence leading to a
reduction of the effective spin moment $m_s + 7< T_z>$. Calculations have also
been performed to study the influence of possible ligands such as Cl and O
atoms on the magnetic properties of the molecule and the interaction between
molecule and surface, because the experimental spectra display a clear
dependence on the ligand, which is used to stabilize the molecule in the gas
phase. Both types of ligands weaken the hybridization between surface and
porphyrin molecule and change the magnetic spin state of the molecule, but the
changes in the X-ray absorption are clearly related to residual Cl ligands.


title:
Stability of inverse nodal problem for energy-dependent sturm liouville
  equation

abstract:
  Inverse nodal problem on diffusion operator is the problem of finding the
potential functions and parameters in the boundary conditions by using nodal
data. In particular, we solve the reconstruction and stability problems using
nodal set of eigenfunctions. Furthermore, we show that the space of all
potential functions q is homeomorphic to the partition set of all
asymptotically equivalent nodal sequences induced by an equivalence relation.
To show this stability which is known Lipschitz stability, we have to construct
two metric spaces and a map {\Phi}_{dif} between these spaces. We find that
{\Phi}_{dif} is a homeomorphism when the corresponding metrics are magnified by
the derivatives of q. Basically, this method is similar to Tsay and Cheng which
is given for Sturm-Liouville and Hill operators, respectively and depends on
the explicit asymptotic expansions of nodal points and nodal lengths.


title: Metrics for Multivariate Dictionaries

abstract:
  Overcomplete representations and dictionary learning algorithms kept
attracting a growing interest in the machine learning community. This paper
addresses the emerging problem of comparing multivariate overcomplete
representations. Despite a recurrent need to rely on a distance for learning or
assessing multivariate overcomplete representations, no metrics in their
underlying spaces have yet been proposed. Henceforth we propose to study
overcomplete representations from the perspective of frame theory and matrix
manifolds. We consider distances between multivariate dictionaries as distances
between their spans which reveal to be elements of a Grassmannian manifold. We
introduce Wasserstein-like set-metrics defined on Grassmannian spaces and study
their properties both theoretically and numerically. Indeed a deep experimental
study based on tailored synthetic datasetsand real EEG signals for
Brain-Computer Interfaces (BCI) have been conducted. In particular, the
introduced metrics have been embedded in clustering algorithm and applied to
BCI Competition IV-2a for dataset quality assessment. Besides, a principled
connection is made between three close but still disjoint research fields,
namely, Grassmannian packing, dictionary learning and compressed sensing.


title:
Photovoltaic effect of light carrying orbital angular momentum on a
  semiconducting stripe

abstract:
  We investigate the influence of a light beam carrying an orbital angular
momentum on the current density of an electron wave packet in a semiconductor
stripe. It is shown that due to the photo-induced torque the electron density
can be deflected to one of the stripe sides. The direction of the deflection is
controlled by the direction of the light orbital momentum. In addition the net
current density can be enhanced. This is a photovoltaic effect that can be
registered by measuring the generated voltage drop across the stripe and/or the
current increase.


title: Quantile regression in high-dimension with breaking

abstract:
  The paper considers a linear regression model in high-dimension for which the
predictive variables can change the influence on the response variable at
unknown times (called change-points). Moreover, the particular case of the
heavy-tailed errors is considered. In this case, least square method with LASSO
or adaptive LASSO penalty can not be used since the theoretical assumptions do
not occur or the estimators are not robust. Then, the quantile model with SCAD
penalty or median regression with LASSO-type penalty allows, in the same time,
to estimate the parameters on every segment and eliminate the irrelevant
variables. We show that, for the two penalized estimation methods, the oracle
properties is not affected by the change-point estimation. Convergence rates of
the estimators for the change-points and for the regression parameters, by the
two methods are found. Monte-Carlo simulations illustrate the performance of
the methods.


title: Gaussian Process Kernels for Pattern Discovery and Extrapolation

abstract:
  Gaussian processes are rich distributions over functions, which provide a
Bayesian nonparametric approach to smoothing and interpolation. We introduce
simple closed form kernels that can be used with Gaussian processes to discover
patterns and enable extrapolation. These kernels are derived by modelling a
spectral density -- the Fourier transform of a kernel -- with a Gaussian
mixture. The proposed kernels support a broad class of stationary covariances,
but Gaussian process inference remains simple and analytic. We demonstrate the
proposed kernels by discovering patterns and performing long range
extrapolation on synthetic examples, as well as atmospheric CO2 trends and
airline passenger data. We also show that we can reconstruct standard
covariances within our framework.


title:
Effect of Mg diffusion on bilayer photoluminescence spectra of
  Mg0.29Zn0.71O/ZnO interface at different annealing temperatures

abstract:
  Mg0.29Zn0.71O/ZnO (MZO/ZnO) bilayers were grown on sapphire substrates by
pulsed laser deposition at ~ 400 C and were subsequently annealed at different
temperatures ranging from ~ 500 to 900 C to allow diffusion of Mg across the
interface. The diffusion of Mg was confirmed from secondary ion mass
spectroscopy (SIMS) and Photo-absorption measurements on the samples. As a
result of Mg diffusion the photoluminescence (PL) spectra of the bilayers got
significantly modified. Whereas the as grown structure had two distinct near
band edge UV luminescence peaks corresponding to the ZnO and MZO layer, the one
annealed at ~ 900 C had a single near band edge PL peak corresponding to a
complete intermixed layer. At the intermediate annealing temperature of ~800 C
the PL peak position corresponding to the MZO layer red-shifted while that
corresponding to the ZnO layer blue-shifted, implying a diffused interface and
partial intermixing. A theoretical model has been developed and numerically
simulated to correlate the PL spectra of the bilayers with the Mg diffusion
profile across the interface, as measured by SIMS.


title: Wave Mechanics without Probability

abstract:
  The behavior of monochromatic electromagnetic waves in stationary media is
shown to be ruled by a frequency dependent function, which we call Wave
Potential, encoded in the structure of the Helmholtz equation. Contrary to the
common belief that the very concept of "ray trajectory" is reserved to the
eikonal approximation, a general and exact ray-based Hamiltonian treatment,
reducing to the eikonal approximation in the absence of Wave Potential, shows
that its presence induces a mutual, perpendicular ray-coupling, which is the
one and only cause of any typically wave-like phenomenon, such as diffraction
and interference. Recalling, then, that the time-independent Schroedinger and
Klein-Gordon equations (associating stationary "matter waves" to mono-energetic
particles) are themselves Helmholtz-like equations, the exact, ray-based
treatment developed for classical electromagnetic waves is extended - without
resorting to statistical concepts - to the exact, trajectory-based Hamiltonian
dynamics of mono-energetic point-like particles, both in the non-relativistic
and in the relativistic case. The trajectories turn out to be perpendicularly
coupled, once more, by an exact, stationary, energy-dependent Wave Potential,
coinciding in the form, but not in the physical meaning, with the statistical,
time-varying, energy-independent "Quantum Potential" of Bohm's theory, which
views particles, just like the standard Copenhagen interpretation, as traveling
wave-packets. These results, together with the connection which is shown to
exist between Wave Potential and Uncertainty Principle, suggest a novel,
non-probabilistic interpretation of Wave Mechanics.


title: Looking at Mean-Payoff and Total-Payoff through Windows

abstract:
  We consider two-player games played on weighted directed graphs with
mean-payoff and total-payoff objectives, two classical quantitative objectives.
While for single-dimensional games the complexity and memory bounds for both
objectives coincide, we show that in contrast to multi-dimensional mean-payoff
games that are known to be coNP-complete, multi-dimensional total-payoff games
are undecidable. We introduce conservative approximations of these objectives,
where the payoff is considered over a local finite window sliding along a play,
instead of the whole play. For single dimension, we show that (i) if the window
size is polynomial, deciding the winner takes polynomial time, and (ii) the
existence of a bounded window can be decided in NP $\cap$ coNP, and is at least
as hard as solving mean-payoff games. For multiple dimensions, we show that (i)
the problem with fixed window size is EXPTIME-complete, and (ii) there is no
primitive-recursive algorithm to decide the existence of a bounded window.


title: On a generalization of Kelly's combinatorial lemma

abstract:
  Kelly's combinatorial lemma is a basic tool in the study of Ulam's
reconstruction conjecture. A generalization in terms of a family of t-elements
subsets of a v-element set was given by Pouzet. We consider a version of this
generalization modulo a prime p. We give illustrations to graphs and
tournaments.


title:
Resistive wall mode and neoclassical tearing mode coupling in rotating
  tokamak plasmas

abstract:
  A model system of equations has been derived to describe a toroidally
rotating tokamak plasma, unstable to Resistive Wall Modes (RWMs) and metastable
to Neoclassical Tearing Modes (NTMs), using a linear RWM model and a nonlinear
NTM model. If no wall is present, the NTM growth shows the typical
threshold/saturation island widths, whereas a linearly unstable kink mode grows
exponentially in this model plasma system. When a resistive wall is present,
the growth of the linearly unstable RWM is accelerated by an unstable island: a
form of coupled RWM-NTM mode. Crucially, this coupled system has no threshold
island width, giving the impression of a triggerless NTM, observed in high beta
tokamak discharges. Increasing plasma rotation at the island location can
mitigate its growth, decoupling the modes to yield a conventional RWM with no
threshold width.


title: A metrical lower bound on the star discrepancy of digital sequences

abstract:
  In this paper we study uniform distribution properties of digital sequences
over a finite field of prime order. In 1998 it was shown by Larcher that for
almost all $s$-dimensional digital sequences the star discrepancy $D_N^\ast$
satisfies an upper bound of the form $D_N^\ast=O((\log N)^s (\log \log
N)^{2+\varepsilon})$ for any $\varepsilon>0$. Generally speaking it is much
more difficult to obtain good lower bounds for specific sequences than upper
bounds. Here we show that Larchers result is best possible up to some $\log
\log N$ term. More detailed, we prove that for almost all $s$-dimensional
digital sequences the star discrepancy satisfies $D_N^\ast \ge c(q,s) (\log
N)^s \log \log N$ for infinitely many $N \in \NN$, where $c(q,s)>0$ only
depends on $q$ and $s$ but not on $N$.


title: Representations of nodal algebras of type A

abstract:
  We define nodal finite dimensional algebras and describe their structure over
an algebraically closed field. For a special class of such algebras (type A) we
find a criterion of tameness.


title:
Weighted Sobolev spaces for the Laplace equation in periodic infinite
  strips

abstract:
  This paper establishes isomorphisms for the Laplace operator in weighted
Sobolev spaces (WSS). These spaces are similar to standard Sobolev spaces, but
they are endowed with weights prescribing functions growth or decay at
infinity. Although well established in the whole space, these weighted results
do not apply in the specific hypothesis of periodicity. This kind of problem
appears when studying singularly perturbed domains (roughness, sieves, porous
media, etc). When zooming on a single perturbation pattern, one often ends with
a periodic problem set on an infinite strip. We present a unified framework
that enables a systematic treatment of such problems. We provide existence and
uniqueness of solutions in our WSS. This gives a refined description of
solutions behavior at infinity which is of importance in the mutli-scale
context. These isomorphism results hold for any weight exponent and any
regularity index. We then identify these solutions with the convolution of a
Green function (specific to periodical infinite strips) and the given data.
This identification is valid again for any weight and any regularity index
modulo some harmonic polynomials.


title: Market viability and martingale measures under partial information

abstract:
  We consider a financial market model with a single risky asset whose price
process evolves according to a general jump-diffusion with locally bounded
coefficients and where market participants have only access to a partial
information flow. For any utility function, we prove that the partial
information financial market is locally viable, in the sense that the optimal
portfolio problem has a solution up to a stopping time, if and only if the
(normalised) marginal utility of the terminal wealth generates a partial
information equivalent martingale measure (PIEMM). This equivalence result is
proved in a constructive way by relying on maximum principles for stochastic
control problems under partial information. We then characterize a global
notion of market viability in terms of partial information local martingale
deflators (PILMDs). We illustrate our results by means of a simple example.


title: On Levi extensions of nilpotent Lie algebras

abstract:
  Levi's theorem decomposes any arbitrary Lie algebra over a field of
characteristic zero, as a direct sum of a semisimple Lie algebra (named Levi
factor) and its solvable radical. Given a solvable Lie algebra $R$, a
semisimple Lie algebra $S$ is said to be a Levi extension of $R$ in case a Lie
structure can be defined on the vector space $S\oplus R$. The assertion is
equivalent to $\rho(S)\subseteq \mathrm{Der}(R)$, where $\mathrm{Der}(R)$ is
the derivation algebra of $R$, for some representation $\rho$ of $S$ onto $R$.
Our goal in this paper, is to present some general structure results on
nilpotent Lie algebras admitting Levi extensions based on free nilpotent Lie
algebras and modules of semisimple Lie algebras. In low nilpotent index a
complete classification will be given. The results are based on linear algebra
methods and leads to computational algorithms.


title:
Complex-Scaling Calculation of Three-Body Resonances Using Complex-Range
  Gaussian Basis Functions --- Application to 3$\alpha$ resonances in 12C ---

abstract:
  We propose to use the complex-range Gaussian basis functions, {r^l e^{-(1 \pm
i\omega)(r/r_n)^2}Y_{lm}(\hat{r}); r_n in a geometric progression}, in the
calculation of three-body resonances with the complex-scaling method (CSM) in
which use is often made of the real-range Gaussian basis functions, {r^l
e^{-(r/r_n)^2}Y_{lm}(\hat{r})}, that are suitable for describing the
short-distance structure and the asymptotic decaying behavior of few-body
systems. The former basis set is more powerful than the latter when describing
the resonant and nonresonant continuum states with highly oscillating amplitude
at large scaling angles \theta. We applied the new basis functions to the CSM
calculation of the 3\alpha resonances with J=0^+, 2^+ and 4^+ in 12C. The
eigenvalue distribution of the complex scaled Hamiltonian becomes more precise
and the maximum scaling angle becomes drastically larger (\theta_{max}=16 deg.
\arrow 36 deg.) than those given by the use of the real-range Gaussians. Owing
to these advantages, we were able to confirm the prediction by Kurokawa and
Kato [Phys. Rev. C 71, 021301 (2005)] on the appearance of the new broad 0^+_3
state; we show it as an explicit resonance pole isolated from the 3$\alpha$
continuum.

categories: nucl-th nucl-ex physics.atm-clus physics.atom-ph


title:
Features of the second-order visual filters sensitive to the spatial
  frequency modulations

abstract:
  We investigated selectivity of 2nd order visual filters sensitive to the
spatial frequency (SF) modulations to orientation and to SF of modulation. We
carried out psychophysical experiment using masking paradigm. It was found that
2nd order filters are selective to SF of modulation (with bandwidth +1.5
octaves), and do not show any selectivity to orientation of modulation. We
suppose receptive fields of 2nd order mechanisms have concentric form.


title: Phase Retrieval via Structured Modulations in Paley-Wiener Spaces

abstract:
  This paper considers the recovery of continuous time signals from the
magnitude of its samples. It uses a combination of structured modulation and
oversampling and provides sufficient conditions on the signal and the sampling
system such that signal recovery is possible. In particular, it is shown that
an average sampling rate of four times the Nyquist rate is sufficient to
reconstruct a signal from its magnitude measurements.


title: Two-qubit non-Markovianity induced by a common environment

abstract:
  We study non-Markovianity as backflow of information in two-qubit systems. We
consider a setting where, by changing the distance between the qubits, one can
interpolate between independent reservoir and common reservoir scenarios. We
demonstrate that non-Markovianity can be induced by the common reservoir and
single out the physical origin of this phenomenon. We show that two-qubit
non-Markovianity coincides with instances of non-divisibility of the
corresponding dynamical map, and we discuss the pair of states maximizing
information flowback. We also discuss the issue of additivity for the measure
we use and in doing so, give an indication of its usefulness as a resource for
multipartite quantum systems.


title: Non-Markovian qubit dynamics induced by Coulomb crystals

abstract:
  We investigate the back-flow of information in a system with a second-order
structural phase transition, namely a quasi one-dimensional Coulomb crystal.
Using standard Ramsey interferometry which couples a target ion (the system) to
the rest of the chain (a phononic environment), we study the non-Markovian
character of the resulting open system dynamics. We study two different
time-scales and show that the back-flow of information pinpoints both the phase
transition and different dynamical features of the chain as it approaches
criticality. We also establish an exact link between the back-flow of
information and the Ramsey fringe visibility.


title:
Variational study for the equation of state of asymmetric nuclear matter
  at finite temperatures

abstract:
  An equation of state (EOS) for uniform asymmetric nuclear matter (ANM) is
constructed at zero and finite temperatures by the variational method starting
from the nuclear Hamiltonian that is composed of the Argonne v18 and Urbana IX
potentials. At zero temperature, the two-body energy is calculated with the
Jastrow wave function in the two-body cluster approximation which is
supplemented by Mayer's condition and the healing-distance condition so as to
reproduce the result by Akmal, Pandharipande and Ravenhall. The energy caused
by the three-body force is treated somewhat phenomenologically so that the
total energy reproduces the empirical saturation conditions. The masses and
radii of neutron stars obtained with the EOS are consistent with recent
observational data. At finite temperatures, thermodynamic quantities such as
free energy, internal energy, entropy, pressure and chemical potentials are
calculated with an extension of the method by Schmidt and Pandharipande. The
validity of the frozen-correlation approximation employed in this work is
confirmed as compared with the result of the fully minimized calculation. The
quadratic proton-fraction-dependence of the energy of ANM is confirmed at zero
temperature, whereas the free energy of ANM deviates from the quadratic
proton-fraction-dependence markedly at finite temperatures. The obtained EOS of
ANM will be an important ingredient of a new nuclear EOS for supernova
numerical simulations.


title:
Direct measurement of the van der Waals interaction between two Rydberg
  atoms

abstract:
  We report on the direct measurement of the van der Waals interaction between
two isolated, single Rydberg atoms separated by a controlled distance of a few
micrometers. By working in a regime where the single-atom Rabi frequency of the
laser used for excitation to the Rydberg state is comparable to the interaction
energy, we observe a \emph{partial} Rydberg blockade, whereby the
time-dependent populations of the various two-atom states exhibit coherent
oscillations with several frequencies. A quantitative comparison of the data
with a simple model based on the optical Bloch equations allows us to extract
the van der Waals energy, and to observe its characteristic $C_6/R^6$
dependence. The magnitude of the measured $C_6$ coefficient agrees well with an
\emph{ab-initio} theoretical calculation, and we observe its dramatic increase
with the principal quantum number $n$ of the Rydberg state. Our results not
only allow to test an important physical law, but also demonstrate a degree of
experimental control which opens new perspectives in quantum information
processing and quantum simulation using long-range interactions between the
atoms.


title: Deep optical imaging of AGB circumstellar envelopes

abstract:
  We report results of a program to image the extended circumstellar envelopes
of asymptotic giant branch (AGB) stars in dust-scattered Galactic light. The
goal is to characterize the shapes of the envelopes to probe the mass-loss
geometry and the presence of hidden binary companions. The observations consist
of deep optical imaging of 22 AGB stars with high mass loss rates: 16 with the
ESO 3.5 m NTT telescope, and the remainder with other telescopes. The
circumstellar envelopes are detected in 15 objects, with mass loss rates > 2E-6
Msun/year. The surface brightness of the envelopes shows a strong decrease with
Galactic radius, which indicates a steep radial gradient in the interstellar
radiation field. The envelopes range from circular to elliptical in shape, and
we characterize them by the ellipticity (E = major/minor axis) of iso-intensity
contours. We find that about 50 percent of the envelopes are close to circular
with E < 1.1, and others are more elliptical with about 20 percent with E >
1.2. We interpret the shapes in terms of populations of single stars and
binaries whose envelopes are flattened by a companion. The distribution of E is
qualitatively consistent with expectations based on population synthesis models
of binary AGB stars. We also find that about 50 percent of the sample exhibit
small-scale, elongated features in the central regions. We interpret these as
the escape of light from the central star through polar holes, which are also
likely produced by companions. Our observations of envelope flattening and
polar holes point to a hidden population of companions within the circumstellar
envelopes of AGB stars. These companions are expected to play an important role
in the transition to post-AGB stars and the formation of planetary nebulae.


title: Crystalline color superconductors

abstract:
  Inhomogeneous superconductors and inhomogeneous superfluids appear in a
variety of contexts including quark matter at extreme densities, fermionic
systems of cold atoms, type-II cuprates, and organic superconductors. In the
present review the focus is on properties of quark matter at high baryonic
density, which may exist in the interior of compact stars. The conditions
realized in these stellar objects tend to disfavor standard symmetric BCS
pairing and may favor an inhomogeneous color superconducting phase. The
properties of inhomogeneous color superconductors are discussed in detail and
in particular of crystalline color superconductors. The possible astrophysical
signatures associated with the presence of crystalline color superconducting
phases within the core of compact stars are also reviewed.

categories: hep-ph astro-ph.SR cond-mat.quant-gas cond-mat.supr-con


title:
Hyperbolic Relaxation of Reaction Diffusion Equations with Dynamic
  Boundary Conditions

abstract:
  Under consideration is the hyperbolic relaxation of a semilinear
reaction-diffusion equation on a bounded domain, subject to a dynamic boundary
condition. We also consider the limit parabolic problem with the same dynamic
boundary condition. Each problem is well-posed in a suitable phase space where
the global weak solutions generate a Lipschitz continuous semiflow which admits
a bounded absorbing set. We prove the existence of a family of global
attractors of optimal regularity. After fitting both problems into a common
framework, a proof of the upper-semicontinuity of the family of global
attractors is given as the relaxation parameter goes to zero. Finally, we also
establish the existence of exponential attractors.


title: Model Checking Lower Bounds for Simple Graphs

abstract:
  A well-known result by Frick and Grohe shows that deciding FO logic on trees
involves a parameter dependence that is a tower of exponentials. Though this
lower bound is tight for Courcelle's theorem, it has been evaded by a series of
recent meta-theorems for other graph classes. Here we provide some additional
non-elementary lower bound results, which are in some senses stronger. Our goal
is to explain common traits in these recent meta-theorems and identify barriers
to further progress. More specifically, first, we show that on the class of
threshold graphs, and therefore also on any union and complement-closed class,
there is no model-checking algorithm with elementary parameter dependence even
for FO logic. Second, we show that there is no model-checking algorithm with
elementary parameter dependence for MSO logic even restricted to paths (or
equivalently to unary strings), unless E=NE. As a corollary, we resolve an open
problem on the complexity of MSO model-checking on graphs of bounded max-leaf
number. Finally, we look at MSO on the class of colored trees of depth d. We
show that, assuming the ETH, for every fixed d>=1 at least d+1 levels of
exponentiation are necessary for this problem, thus showing that the (d+1)-fold
exponential algorithm recently given by Gajarsk\`{y} and Hlin\u{e}n\`{y} is
essentially optimal.


title:
Mutation Rules and the Evolution of Sparseness and Modularity in
  Biological Systems

abstract:
  Biological systems exhibit two structural features on many levels of
organization: sparseness, in which only a small fraction of possible
interactions between components actually occur; and modularity - the near
decomposability of the system into modules with distinct functionality. Recent
work suggests that modularity can evolve in a variety of circumstances,
including goals that vary in time such that they share the same subgoals
(modularly varying goals), or when connections are costly. Here, we studied the
origin of modularity and sparseness focusing on the nature of the mutation
process, rather than on connection cost or variations in the goal. We use
simulations of evolution with different mutation rules. We found that commonly
used sum-rule mutations, in which interactions are mutated by adding random
numbers, do not lead to modularity or sparseness except for in special
situations. In contrast, product-rule mutations in which interactions are
mutated by multiplying by random numbers - a better model for the effects of
biological mutations - led to sparseness naturally. When the goals of evolution
are modular, in the sense that specific groups of inputs affect specific groups
of outputs, product-rule mutations also lead to modular structure; sum-rule
mutations do not. Product-rule mutations generate sparseness and modularity
because they tend to reduce interactions, and to keep small interaction terms
small.


title:
Re-Encoding Techniques for Interpolation-Based Decoding of Reed-Solomon
  Codes

abstract:
  We consider interpolation-based decoding of Reed-Solomon codes using the
Guruswami-Sudan algorithm (GSA) and investigate the effects of two modification
techniques for received vectors, i.e., the re-encoding map and the newly
introduced periodicity projection. After an analysis of the latter, we track
the benefits (that is low Hamming weight and regular structure) of modified
received vectors through the interpolation step of the GSA and show how the
involved homogeneous linear system of equations can be compressed. We show that
this compression as well as the recovery of the interpolated bivariate
polynomial is particularly simple when the periodicity projection was applied.


title:
Anisotropic finite elements with high aspect ratio for an Asymptotic
  Preserving method for highly anisotropic elliptic equation

abstract:
  The concern of this work is the generalization of an Asymptotic Preserving
method for the highly anisotropic elliptic equations presented in [P. Degond,
A. Lozinski, J. Narski, and C. Negulescu. An asymptotic-preserving method for
highly anisotropic elliptic equations based on a micro-macro decomposition. J.
Comput. Phys., 231(7):2724{2740, 2012]. The limitations of the method
introduced there in are omitted by the introduction of a stabilization term in
the Asymptotic Reformulation. Furthermore, anisotropic error indicators and
mesh adaptation algorithms are proposed and tested allowing to reduce
considerably the number of mesh points required to achieve prescribed
precision. Reported meshes have maximum aspect ratio greater than 500.


title: Additive and multiplicative structure of c$^{\star}$-sets

abstract:
  It is known that for an IP${^\star}$ set $A$ in $\mathbb{N}$ and a sequence
$< x_{n}>_{n=1}^{\infty}$ there exists a sum subsystem $<
y_{n}>_{n=1}^{\infty}$ of $< x_{n}>_{n=1}^{\infty}$ such that
  $FS(< y_n>_{n=1}^\infty)\cup FP(< y_n>_{n=1}^\infty)\subseteq A$. Similar
types of results also have been proved for central* sets where the sequences
have been taken from the class of minimal sequences. In this present work we
will prove some analogues results for C$^{\star}$-sets for a more general class
of sequences.


title:
Disentangling glass and jamming physics in the rheology of soft
  materials

abstract:
  The shear rheology of soft particles systems becomes complex at large density
because crowding effects may induce a glass transition for Brownian particles,
or a jamming transition for non-Brownian systems. Here we successfully explore
the hypothesis that the shear stress contributions from glass and jamming
physics are `additive'. We show that the experimental flow curves measured in a
large variety of soft materials (colloidal hard spheres, microgel suspensions,
emulsions, aqueous foams) as well as numerical flow curves obtained for soft
repulsive particles in both thermal and athermal limits are well described by a
simple model assuming that glass and jamming rheologies contribute linearly to
the shear stress, provided that the relevant scales for time and stress are
correctly identified in both sectors. Our analysis confirms that the dynamics
of colloidal hard spheres is uniquely controlled by glass physics while aqueous
foams are only sensitive to jamming effects. We show that for micron-sized
emulsions both contributions are needed to successfully account for the flow
curves, which reveal distinct signatures of both phenomena. Finally, for two
systems of soft microgel particles we show that the flow curves are
representative of the glass transition of colloidal systems, and deduce that
microgel particles are not well suited to studying the jamming transition
experimentally.


title:
A cellular basis of the $q$-Brauer algebra related with Murphy bases of
  the Hecke algebras

abstract:
  A new basis of the $q$-Brauer algebra is introduced, which is a lift of
Murphy bases of Hecke algebras of symmetric groups. This basis is a cellular
basis in the sense of Graham and Lehrer. Subsequently, using combinatorial
language we prove that the non-isomorphic simple $q$-Brauer modules are indexed
by the $e(q^2)$-restricted partitions of $n-2k$ where $k$ is an integer, $0 \le
k \le [n/2]$. When the $q$-Brauer algebra has low-dimension a criterion of
semisimplicity is given, which is used to show that the $q$-Brauer algebra is
in general not isomorphic to the BMW-algebra.}


title: Pulsed chaos synchronization in networks with adaptive couplings

abstract:
  Networks of chaotic units with static couplings can synchronize to a common
chaotic trajectory. The effect of dynamic adaptive couplings on the cooperative
behavior of chaotic networks is investigated. The couplings adjust to the
activities of its two units by two competing mechanisms: An exponential
decrease of the coupling strength is compensated by an increase due to
de-synchronized activity. This mechanism prevents the network from reaching a
steady state. Numerical simulations of a coupled map lattice show chaotic
trajectories of de-synchronized units interrupted by pulses of mutually
synchronized clusters. These pulses occur on all scales, sometimes extending to
the entire network. Clusters of synchronized units can be triggered by a small
group of synchronized units.

categories: nlin.CD cond-mat.stat-mech nlin.AO physics.comp-ph q-bio.NC


title:
Entanglement evolution across defects in critical anisotropic Heisenberg
  chains

abstract:
  We study the out-of-equilibrium time evolution after a local quench
connecting two anisotropic spin-1/2 XXZ Heisenberg open chains via an impurity
bond. The dynamics is obtained by means of the adaptive time-dependent
density-matrix renormalization group. We show that the entanglement entropies
(Von Neumann and R\'enyi), in the presence of a weakened bond depend on the
sign of the bulk interaction. For attractive interaction (\Delta< 0), the
defect turns out to be irrelevant and the evolution is asymptotically
equivalent to the one without defect obtained by conformal field theory. For
repulsive interaction (\Delta>0), the defect is relevant and the entanglement
saturates to a finite value. This out-of-equilibrium behavior generalizes the
well known results for the ground-state entanglement entropy of the model.


title: Measurement and simulation of the muon-induced neutron yield in lead

abstract:
  A measurement is presented of the neutron production rate in lead by high
energy cosmic-ray muons at a depth of 2850 m water equivalent (w.e.) and a mean
muon energy of 260 GeV. The measurement exploits the delayed coincidences
between muons and the radiative capture of induced neutrons in a highly
segmented tonne scale plastic scintillator detector. Detailed Monte Carlo
simulations reproduce well the measured capture times and multiplicities and,
within the dynamic range of the instrumentation, the spectrum of energy
deposits. By comparing measurements with simulations of neutron capture rates a
neutron yield in lead of (5.78^{+0.21}_{-0.28}) x 10^{-3}
neutrons/muon/(g/cm^{2}) has been obtained. Absolute agreement between
simulation and data is of order 25%. Consequences for deep underground rare
event searches are discussed.


title:
GAMA/H-ATLAS: Linking the Properties of Sub-mm Detected and Undetected
  Early-Type Galaxies: I. z$\le$0.06 Sample

abstract:
  We present two large, nearby (0.013$\le$z$\le$0.06) samples of Early-Type
Galaxies (ETGs): a visually classified sample of 220 ETGs, created using
source-matched data from the Galaxy and Mass Assembly (GAMA) database with
FIR/sub-mm detections from $Herschel$-ATLAS; and a visually classified sample
of 551 ETGs which are undetected with $Herschel$-ATLAS. Active galactic nuclei
(AGN) are removed from our samples using optical emission line diagnostics.
These samples are scrutinised to determine characteristics of sub-mm detected
versus undetected ETGs. We find similarities in the stellar mass distributions
of the two ETG samples but testing other properties uncovers significant
differences. The sub-mm detected sample is shown to have lower concentration
and S\'ersic indices than those in the undetected sample - a result which may
be linked to the presence of dust in the former. Optical and UV-optical colours
are also shown to be much bluer, indicating that the dust is linked with recent
star formation. The intrinsic effective radii are on average 1.5 times larger
for the sub-mm detected ETGs. Surface densities and groups data from the GAMA
database are examined for the two samples, leading to the conclusion that dusty
ETGs inhabit sparser environments than non-dusty ETGs in the nearby universe,
although environments of the brightest ETGs are shown to differ the least.
Modified Planck functions are fit to the H-ATLAS detected PACS and SPIRE fluxes
for ETGs with sub-mm flux densities of at least 3$\sigma$ in the 350$\mu$m
SPIRE band, giving a resultant mean cold dust temperature of T$_{d}$=22.1K,
with a range of 9-30K. The corresponding mean dust mass is
1.8$\times10^{7}$M$_{\odot}$, with a range of
(0.08-35.0)$\times10^{7}$M$_{\odot}$. The dust masses calculated from these
fits, normalised by stellar mass, are shown to increase with decreasing stellar
mass and bluer colours.


title:
HEROICA: an Underground Facility for the Fast Screening of Germanium
  Detectors

abstract:
  An infrastructure to characterize germanium detectors has been designed and
constructed at the HADES Underground Research Laboratory, located in Mol
(Belgium). Thanks to the 223m overburden of clay and sand, the muon flux is
lowered by four orders of magnitude. This natural shield minimizes the exposure
of radio-pure germanium material to cosmic radiation resulting in a significant
suppression of cosmogenic activation in the germanium detectors. The project
has been strongly motivated by a special production of germanium detectors for
the GERDA experiment. GERDA, currently collecting data at the Laboratori
Nazionali del Gran Sasso of INFN, is searching for the neutrinoless double beta
decay of 76Ge. In the near future, GERDA will increase its mass and sensitivity
by adding new Broad Energy Germanium (BEGe) detectors. The production of the
BEGe detectors is done at Canberra in Olen (Belgium), located about 30km from
the underground test site. Therefore, HADES is used both for storage of the
crystals over night, during diode production, and for the characterization
measurements. A full quality control chain has been setup and tested on the
first seven prototype detectors delivered by the manufacturer at the beginning
of 2012. The screening capabilities demonstrate that the installed setup
fulfills a fast and complete set of measurements on the diodes and it can be
seen as a general test facility for the fast screening of high purity germanium
detectors. The results are of major importance for a future massive production
and characterization chain of germanium diodes foreseen for a possible next
generation 1-tonne double beta decay experiment with 76Ge.


title: Weak Convergence Methods for Approximation of Path-dependent Functionals

abstract:
  This paper provides convergence analysis for the approximation of a class of
path-dependent functionals underlying a continuous stochastic process. In the
first part, given a sequence of weak convergent processes, we provide a
sufficient condition for the convergence of the path-dependent functional
underlying weak convergent processes to the functional of the original process.
In the second part, we study the weak convergence of Markov chain approximation
to the underlying process when it is given by a solution of stochastic
differential equation. Finally, we combine the results of the two parts to
provide approximation of option pricing for discretely monitoring barrier
option underlying stochastic volatility model. Different from the existing
literatures, the weak convergence analysis is obtained by means of metric
computations in the Skorohod topology together with the continuous mapping
theorem. The advantage of this approach is that the functional under study may
be a function of stopping times, projection of the underlying diffusion on a
sequence of random times, or maximum/minimum of the underlying diffusion.


title:
Logarithmic conformal field theories as limits of ordinary CFTs and some
  physical applications

abstract:
  We describe an approach to logarithmic conformal field theories as limits of
sequences of ordinary conformal field theories with varying central charge c.
Logarithmic behaviour arises from degeneracies in the spectrum of scaling
dimensions at certain values of c. The theories we consider are all invariant
under some internal symmetry group, and logarithmic behaviour occurs when the
decomposition of the physical observables into irreducible operators becomes
singular. Examples considered are quenched random magnets using the replica
formalism, self-avoiding walks as the n->0 of the O(n) model, and percolation
as the limit Q->1 of the Potts model. In these cases we identify logarithmic
operators and pay particular attention to how the c->0 paradox is resolved and
how the b-parameter is evaluated. We also show how this approach gives
information on logarithmic behaviour in the extended Ising model, uniform
spanning trees and the O(-2) model. Most of our results apply to general
dimensionality. We also consider massive logarithmic theories and, in two
dimensions, derive sum rules for the effective central charge and the
b-parameter.


title: Asynchronous MPI for the Masses

abstract:
  We present a simple library which equips MPI implementations with truly
asynchronous non-blocking point-to-point operations, and which is independent
of the underlying communication infrastructure. It utilizes the MPI profiling
interface (PMPI) and the MPI_THREAD_MULTIPLE thread compatibility level, and
works with current versions of Intel MPI, Open MPI, MPICH2, MVAPICH2, Cray MPI,
and IBM MPI. We show performance comparisons on a commodity InfiniBand cluster
and two tier-1 systems in Germany, using low-level and application benchmarks.
Issues of thread/process placement and the peculiarities of different MPI
implementations are discussed in detail. We also identify the MPI libraries
that already support asynchronous operations. Finally we show how our ideas can
be extended to MPI-IO.


title:
The transverse momentum dependent statistical parton distributions
  revisited

abstract:
  The extension of the statistical parton distributions to include their
transverse momentum dependence (TMD) is revisited by considering that the
proton target has a finite longitudinal momentum. The TMD will be generated by
means of a transverse energy sum rule. The new results are mainly relevant for
electron-proton inelastic collisions in the low $Q^2$ region. We take into
account the effects of the Melosh-Wigner rotation for the helicity
distributions.


title:
Heavy Quarkonium Production through the Semi-Exclusive $e^+ e^-$
  Annihilation Channels around the $Z^0$ Peak

abstract:
  Within the framework of the non-relativistic QCD, we present a detailed
discussion on the heavy quarkonium production at the leading order in
$\alpha_s$ at a $e^+ e^-$ collider with the collision energy around the $Z^0$
peak. Quarkonia are produced through the semi-exclusive channels $e^{+}e^{-}
\rightarrow |H_{Q\bar{Q}}\rangle +X$ with $X=Q\bar{Q}$ or $gg$, where $Q$
indicates a heavy quark (respectively $b$ or $c$). It is noted that in addition
to the color-singlet 1S-level quarkonium states, the 2S and 1P color-singlet
states and the color-octet $|(Q\bar{Q})[1^3S_1^{({\bf 8})}]g\rangle$ state also
provide sizable contributions. The heavy quarkonium transverse momentum and
rapidity distributions for the $e^+ e^-$ collision energy $E_{cm}=m_Z$ are
presented. For both charmonium and bottomonium production via the $Z^0$
propagator, there is approximate "spin degeneracy" between the spin-triplet and
spin-singlet quarkonium states. Uncertainties for the total cross sections are
estimated by taking $m_c=1.50\pm0.15$ GeV and $m_b=4.90\pm0.15$ GeV. Around
$E_{cm}=m_{Z}$, due to the $Z^0$-boson resonance effect, total cross sections
for the channels via the $Z^0$-propagator become much larger than the channels
via the virtual photon propagator. We conclude that, in addition to the $B$
factories as BaBar and Belle and the hadronic colliders as Tevatron and LHC,
such a super $Z$-factory will present an excellent platform for studying the
heavy quarkonium properties.


title: On the Fly Self-Organized Base Station Placement

abstract:
  In this paper, we address the deployment of base stations (BSs) in a
one-dimensional network in which the users are randomly distributed.In order to
take into account the users' distribution to optimally place the BSs we
optimize the uplink MMSE sum rate. Moreover, given a massive number of antennas
at the BSs we propose a novel random matrix theory-based technique so as to
obtain tight approximations for the MMSE sum rate in the uplink. We investigate
a cooperative (CP) scenario where the BSs jointly decode the messages and a
non-cooperative (NCP) scheme in which the BS can only decode its own users. Our
results show that the CP strategy considerably outperforms the NCP case.
Moreover, we show that there exists a trade off in the BS deployment regarding
the position of each BS. Thus, through location games we can optimize the
position of each BS in order to maximize the system performance.


title:
Classical limits of quantum mechanics on a non-commutative configuration
  space

abstract:
  We consider a model of non-commutative Quantum Mechanics given by two
harmonic oscillators over a non-commutative two dimensional configuration
space. We study possible ways of removing the non-commutativity based on the
classical limit context known as anti-Wick quantization. We show that removal
of non-commutativity from the configuration space and from the canonical
operators are not commuting operations.


title:
On Witten multiple zeta-functions associated with semisimple Lie
  algebras V

abstract:
  We study the values of the zeta-function of the root system of type $G_2$ at
positive integer points. In our previous work we considered the case when all
integers are even, but in the present paper we prove several theorems which
include the situation when some of the integers are odd. The underlying reason
why we may treat such cases including odd integers is also discussed.


title:
Indications for a slow rotator in the Rapid Burster from its
  thermonuclear bursting behaviour

abstract:
  We perform time-resolved spectroscopy of all the type I bursts from the Rapid
Burster (MXB 1730-335) detected with the Rossi X-ray Timing Explorer. Type I
bursts are detected at high accretion rates, up to \sim 45% of the Eddington
luminosity. We find evidence that bursts lacking the canonical cooling in their
time-resolved spectra are, none the less, thermonuclear in nature. The type I
bursting rate keeps increasing with the persistent luminosity, well above the
threshold at which it is known to abruptly drop in other bursting low-mass
X-ray binaries. The only other known source in which the bursting rate keeps
increasing over such a large range of mass accretion rates is the 11 Hz pulsar
IGR J17480$-$2446. This may indicate a similarly slow spin for the neutron star
in the Rapid Burster.


title: Dynamics of gas and dust clouds in active galactic nuclei

abstract:
  We analyse the motion of single optically thick clouds in the potential of a
central mass under the influence of an anisotropic radiation field
~|cos(\theta)|, a model applicable to the inner region of active galactic
nuclei. Resulting orbits are analytically soluble for constant cloud column
densities. All stable orbits are closed, although they have non-trivial shapes.
Furthermore, there exists a stability criterion in the form of a critical
inclination, which depends on the luminosity of the central source and the
column density of the cloud.


title:
Coherent photoproduction of $\psi$ and $\Upsilon$ mesons in
  ultraperipheral pPb and PbPb collisions at the CERN LHC

abstract:
  Exclusive photoproduction of vector mesons in the perturbative two-gluon
exchange formalism depends significantly on nucleon and nuclear gluon
distributions. In the present study we calculate total cross sections and
rapidity distributions of $J/\psi(1s)$, $\psi(2s)$, $\Upsilon(1s)$,
$\Upsilon(2s)$, and $\Upsilon(3s)$ in ultraperipheral proton-lead (pPb) and
lead-lead (PbPb) collisions at the CERN Large Hadron Collider (LHC) at
$\sqrt{s_{_{NN}}}=5$ TeV and $\sqrt{s_{_{NN}}}=2.76$ TeV respectively. Effects
of gluon shadowing are investigated and potentials for constraining nuclear
gluon modifications are discussed.


title: From quantum quasi-shuffle algebras to braided Rota-Baxter algebras

abstract:
  In this letter, we use quantum quasi-shuffle algebras to construct
Rota-Baxter algebras, as well as tridendriform algebras. We also propose the
notion of braided Rota-Baxter algebras, which is the relevant object of
Rota-Baxter algebras in a braided tensor category. Examples of such new
algebras are provided by using quantum multi-brace algebras in a category of
Yetter-Drinfeld modules.


title: Perturbation theory in (2,2) signature

abstract:
  We identify a natural analytic continuation in four dimensions from Minkowski
signature to a signature with two time-like momentum components. For two, three
and four-point diagrams at fixed external momenta, this continuation can be
implemented as a countour deformation that leaves dependence on the momenta
unchanged. For arbitrary ultraviolet-finite scalar diagrams it is possible to
do two integrals per loop in terms of simple poles in the new signature. This
results in a representation of any such diagram as a sum of terms, each with
two remaining integrals per loop.


title:
A simple and accurate approximation for the Q stability parameter in
  multi-component and realistically thick discs

abstract:
  In this paper, we propose a Q stability parameter that is more realistic than
those commonly used, and is easy to evaluate [see Eq. (19)]. Using our Q_N
parameter, you can take into account several stellar and/or gaseous components
as well as the stabilizing effect of disc thickness, you can predict which
component dominates the local stability level, and you can do all that simply
and accurately. To illustrate the strength of Q_N, we analyse the stability of
a large sample of spirals from The HI Nearby Galaxy Survey (THINGS), treating
stars, HI and H_2 as three distinct components. Our analysis shows that H_2
plays a significant role in disc (in)stability even at distances as large as
half the optical radius. This is an important aspect of the problem, which was
missed by previous (two-component) analyses of THINGS spirals. We also show
that HI plays a negligible role up to the edge of the optical disc; and that
the stability level of THINGS spirals is, on average, remarkably flat and well
above unity.

categories: astro-ph.CO astro-ph.GA physics.flu-dyn physics.plasm-ph


title: Local support against gravity in magneto-turbulent fluids

abstract:
  Comparisons of the integrated thermal pressure support of gas against its
gravitational potential energy lead to critical mass scales for gravitational
instability such as the Jeans and the Bonnor-Ebert masses, which play an
important role in analysis of many physical systems, including the heuristics
of numerical simulations. In a strict theoretical sense, however, neither the
Jeans nor the Bonnor-Ebert mass are meaningful when applied locally to
substructure in a self-gravitating turbulent medium. For this reason, we
investigate the local support by thermal pressure, turbulence, and magnetic
fields against gravitational compression through an approach that is
independent of these concepts. At the centre of our approach is the dynamical
equation for the divergence of the velocity field. We carry out a statistical
analysis of the source terms of the local compression rate (the negative time
derivative of the divergence) for simulations of forced self-gravitating
turbulence in periodic boxes with zero, weak, and moderately strong mean
magnetic fields (measured by the averages of the magnetic and thermal
pressures). We also consider the amplification of the magnetic field energy by
shear and by compression. Thereby, we are able to demonstrate that the support
against gravity is dominated by thermal pressure fluctuations, although
magnetic pressure also yields a significant contribution. The net effect of
turbulence in the highly supersonic regime, however, is to enhance compression
rather than supporting overdense gas even if the vorticity is very high. This
is incommensurate with the support of the highly dynamical substructures in
magneto-turbulent fluids being determined by local virial equilibria of volume
energies without surface stresses.


title: Molecular theory of graphene

abstract:
  Odd electrons of benzenoid units and correlation of these electrons having
different spins are the main concepts of the molecular theory of graphene. In
contrast to the theory of aromaticity, the molecular theory is based on the
fact that odd electrons with different spins occupy different places in the
space so that the configuration interaction becomes the central point of the
theory. Consequently, a multi-determinant presentation of the wave function of
the system of weakly interacting odd electrons is absolutely mandatory on the
way of the theory realization at the computational level. However, the efficacy
of the available CI computational techniques is quite restricted in regards
large polyatomic systems, which does not allow performing extensive
computational experiments. Facing the problem, computationists have addressed
to standard single-determinant ones albeit not often being aware of how correct
are the obtained results. The current chapter presents the molecular theory of
graphene in terms of single-determinant computational schemes and discloses how
reliable information about electron-correlated system can be obtained by using
either UHF or UDFT computational schemes.


title:
Development of a Thermal Control System with Mechanically Pumped CO2
  Two-Phase Loops for the AMS-02 Tracker on the ISS

abstract:
  To provide a stable thermal environment for the AMS-Tracker, a thermal
control system based on mechanically pumped CO2 two-phase loops was developed.
It has been operating reliably in space since May 19, 2011. In this article, we
summarize the design, construction, tests, and performance of the AMS-Tracker
thermal control system (AMS-TTCS).


title: Probabilistic existence of regular combinatorial structures

abstract:
  We show the existence of regular combinatorial objects which previously were
not known to exist. Specifically, for a wide range of the underlying
parameters, we show the existence of non-trivial orthogonal arrays, t-designs,
and t-wise permutations. In all cases, the sizes of the objects are optimal up
to polynomial overhead. The proof of existence is probabilistic. We show that a
randomly chosen structure has the required properties with positive yet tiny
probability. Our method allows also to give rather precise estimates on the
number of objects of a given size and this is applied to count the number of
orthogonal arrays, t-designs and regular hypergraphs. The main technical
ingredient is a special local central limit theorem for suitable lattice random
walks with finitely many steps.


title:
Analytic and topological index maps with values in the K-theory of
  mapping cones

abstract:
  Index maps taking values in the $K$-theory of a mapping cone are defined and
discussed. The resulting index theorem can be viewed in analogy with the
Freed-Melrose index theorem. The framework of geometric $K$-homology is used in
a fundamental way. In particular, an explicit isomorphism from a geometric
model for $K$-homology with coefficients in a mapping cone, $C_{\phi}$, to
$KK(C(X),C_{\phi})$ is constructed.


title: Feature Multi-Selection among Subjective Features

abstract:
  When dealing with subjective, noisy, or otherwise nebulous features, the
"wisdom of crowds" suggests that one may benefit from multiple judgments of the
same feature on the same object. We give theoretically-motivated `feature
multi-selection' algorithms that choose, among a large set of candidate
features, not only which features to judge but how many times to judge each
one. We demonstrate the effectiveness of this approach for linear regression on
a crowdsourced learning task of predicting people's height and weight from
photos, using features such as 'gender' and 'estimated weight' as well as
culturally fraught ones such as 'attractive'.


title: Isocurvature Perturbations and Reheating in Multi-Field Inflation

abstract:
  Inflationary models involving more than one scalar field naturally produce
isocurvature perturbations. However, while these are fairly well studied, less
is known about their evolution through the reheating epoch, when the
inflationary fields decay into the standard constituents of the present
universe. In this paper, by modelling reheating perturbatively, we calculate
the power spectrum of the non-adiabatic pressure perturbation in three
different inflationary models. We show that the isocurvature can grow large
initially, but decays faster than the pressure perturbations. When reheating
ends, the isocurvature is negligible for the double quadratic and double
quartic inflationary models. For the product exponential potential, which
features large isocurvature at the end of inflation, the isocurvature decays
during reheating and is around five orders of magnitudes smaller than the
pressure perturbation at the end of reheating.


title:
Shape effects on localized surface plasmon resonances in metallic
  nanoparticles

abstract:
  The effect of smooth shape changes of metallic nanoparticles on localized
surface plasmon resonances is assessed with a boundary integral equation
method. The boundary integral equation method allows compact expressions of
nanoparticle polarizability which is expressed as an eigenmode sum of terms
that depends on the eigenvalues and eigenfunctions of the integral operator
associated to the boundary integral equation method. Shape variations change
not only the eigenvalues but also their coupling weights to the electromagnetic
field. Thus, rather small changes in the shape may induce large variations of
the coupling weights. It has been found that shape changes that bring volume
variations >12% induce structural changes in the extinction spectrum of
metallic nanoparticles. Also, the largest variations in eigenvalues and their
coupling weights are encountered by shape changes along the smallest
cross-sections of nanoparticles. These results are useful as guiding rules in
the process of designing plasmonic nanostrucrures.


title:
$f(R,{T_{\mu\nu} T^{\mu\nu}})$ gravity and Cardassian-like expansion as
  one of its consequences

abstract:
  We propose a new model of gravity where the Ricci scalar (R) in
Einstein-Hilbert action is replaced by an arbitrary function of R and of the
norm of energy-momentum tensor i.e., $f(R,T_{\mu\nu}T^{\mu\nu})$. Field
equations are derived in the metric formalism. We find that the equation of
motion of massive test particles is non-geodesic and these test particles are
acted upon by a force which is orthogonal to the four-velocity of the
particles. We also find the Newtonian limit of the model to calculate the extra
acceleration which can affect the perihelion of Mercury. There is a deviation
from the general relativistic(GR) result unless the energy density of fluid is
constant. Arranging $\alpha$ parameter gives an opportunity to cure the
inconsistency between the observational values for the abundance of light
elements and the standard Big Bang Nucleosynthesis results. Even the dust
dominated universe undergoes an accelerated expansion without using a
cosmological constant in Model II. With this specific choice of
$f(R,T_{\mu\nu}T^{\mu\nu})$, we get the a Cardassian-like expansion.


title:
Interaction for the trapped fermi gas from a unitary transformation of
  the exact two-body spectrum

abstract:
  We study systems of few two-component fermions interacting in a Harmonic
Oscillator trap. The fermion-fermion interaction is generated in a finite basis
with a unitary transformation of the exact two-body spectrum given by the Busch
formula. The few-body Schr\"odinger equation is solved with the formalism of
the No-Core Shell Model. We present results for a system of three fermions
interacting at unitarity as well as for finite values of the S-wave scattering
length $a_2$ and effective range $r_2$. Unitary systems with four and five
fermions are also considered. We show that the many-body energies obtained in
this approach are in excellent agreement with exact solutions for the
three-body problem, and results obtained by other methods in the other cases.


title: Expansions in non-integer bases: lower order revisited

abstract:
  Let $q\in(1,2)$ and $x\in[0,\frac1{q-1}]$. We say that a sequence
$(\varepsilon_i)_{i=1}^{\infty}\in\{0,1\}^{\mathbb{N}}$ is an expansion of $x$
in base $q$ (or a $q$-expansion) if \[
x=\sum_{i=1}^{\infty}\varepsilon_iq^{-i}. \] For any $k\in\mathbb N$, let
$\mathcal B_k$ denote the set of $q$ such that there exists $x$ with exactly
$k$ expansions in base $q$. In [12] it was shown that $\min\mathcal
B_2=q_2\approx 1.71064$, the appropriate root of $x^{4}=2x^{2}+x+1$. In this
paper we show that for any $k\geq 3$, $\min\mathcal B_k=q_f\approx1.75488$, the
appropriate root of $x^3=2x^2-x+1$.


title:
Adelic equidistribution, characterization of equidistribution, and a
  general equidistribution theorem in non-archimedean dynamics

abstract:
  We determine when the equidistribution property for possibly moving targets
holds for a rational function of degree more than one on the projective line
over an algebraically closed field of any characteristic and complete with
respect to a non-trivial absolute value. This characterization could be useful
in the positive characteristic case. Based on the variational argument, we give
a purely local proof of the adelic equidistribution theorem for possibly moving
targets, which is due to Favre and Rivera-Letelier, using a dynamical
Diophantine approximation theorem by Silverman and by Szpiro--Tucker. We also
give a proof of a general equidistribution theorem for possibly moving targets,
which is due to Lyubich in the archimedean case and due to Favre and
Rivera-Letelier for constant targets in the non-archimedean and any
characteristic case and for moving targets in the non-archimedean and 0
characteristic case.


title: Langlands parameters for epipelagic representations of $\text{\rm GL}_n$

abstract:
  Let $F$ be a non-Archimedean local field. An irreducible cuspidal
representation of $\text{\rm GL}_n(F)$ is epipelagic if its Swan conductor
equals 1. We give a full and explicit description of the Langlands parameters
of such representations.


title:
Preface to the 15th workshop "What comes beyond the standard models",
  Bled July 9--19, 2012, and links to the talks in the proceedings

abstract:
  The contribution contains the preface to the Proceedings to the 15 th
Workshop What Comes Beyond the Standard Models, Bled, July 9 - 19, 2012,
published in Bled workshops in physics, Vol.13, No. 2, DMFA-Zaloznistvo,
Ljubljana, Dec. 2012, and links to the published contributions.


title: Identical classical particles: half fermions and half bosons

abstract:
  We study the problem of particle indistinguishability for the three cases
known in nature: identical classical particles, identical bosons and identical
fermions. By exploiting the fact that different types of particles are
associated with Hilbert space vectors with different symmetries, we establish
some relations between the expectation value of several different operators, as
the particle number one and the interparticle correlation one, evaluated for
states of a pair of identical (a) classical particles, (b) bosons and (c)
fermions. We find that the quantum behavior of a pair of identical classical
particles has exactly half fermionic and half bosonic characteristics.


title: On moduli spaces of Ricci solitons

abstract:
  We study deformations of shrinking Ricci solitons on a compact manifold M,
generalising the classical theory of deformations of Einstein metrics. Using
appropriate notions of twisted slices S_f inside the space of all Riemannian
metrics on M, we define the infinitesimal solitonic deformations and the local
solitonic pre-moduli spaces. We prove the existence of a finite dimensional
submanifold of S_f x C^infty(M), which contains the pre-moduli space of
solitons around a fixed shrinking Ricci soliton as an analytic subset. We
define solitonic rigidity and give criteria which imply it.


title:
Interacting Galactic Neutral Hydrogen Filaments and Associated
  High-Frequency Continuum Emission

abstract:
  Galactic HI emission profiles in an area where several large-scale filaments
at velocities ranging from -46 km/s to 0 km/s overlap were decomposed into
Gaussian components. Eighteen families of components defined by similarities of
center velocity and line width were identified and related to small-scale
structure in the high-frequency continuum emission observed by the WMAP
spacecraft, as evidenced in the Internal Linear Combination (ILC) map of
Hinshaw et al. (2007). When the center velocities of the Gaussian families,
which summarize the properties of all the HI along the lines-of-sight in a
given area, are used to focus on HI channel maps the phenomenon of close
associations between HI and ILC peaks reported in previous papers is
dramatically highlighted. Of particular interest, each of two pairs of HI peaks
straddles a continuum peak. The previously hypothesized model for producing the
continuum radiation (Verschuur, 2010) involving free-free emission from
electrons is re-examined in the light of the new data. By choosing reasonable
values for the parameters required to evaluate the model, the distance for
associated HI-ILC features is of order 30 to 100 pc. No associated H-alpha
radiation is expected because the electrons involved exist throughout the Milky
Way. The mechanism for clumping and separation of neutrals and electrons needs
to be explored.


title:
Subharmonic solutions for nonautonomous sublinear first order
  Hamiltonian systems

abstract:
  In this paper, the existence of subharmonic solutions for a class of
non-autonomous first-order Hamiltonian systems is investigated. We also study
the minimality of periods for such solutions. Our results which extend and
improve many previous results will be illustrated by specific examples. Our
main tools are the minimax methods in critical point theory and the least
action principle. {\bf Key words.} Hamiltonian systems. Critical point theory.
Least action principle. Subharmonic solutions.


title: Experimental Quantum Computing to Solve Systems of Linear Equations

abstract:
  Solving linear systems of equations is ubiquitous in all areas of science and
engineering. With rapidly growing data sets, such a task can be intractable for
classical computers, as the best known classical algorithms require a time
proportional to the number of variables N. A recently proposed quantum
algorithm shows that quantum computers could solve linear systems in a time
scale of order log(N), giving an exponential speedup over classical computers.
Here we realize the simplest instance of this algorithm, solving 2*2 linear
equations for various input vectors on a quantum computer. We use four quantum
bits and four controlled logic gates to implement every subroutine required,
demonstrating the working principle of this algorithm.


title:
An inclination lemma for normally hyperbolic manifolds with an
  application to diffusion

abstract:
  Let ($M$, $\Omega$) be a smooth symplectic manifold and $f:M\rightarrow M$ be
a symplectic diffeomorphism of class $C^l$ ($l\geq 3$). Let $N$ be a compact
submanifold of $M$ which is boundaryless and normally hyperbolic for $f$. We
suppose that $N$ is controllable and that its stable and unstable bundles are
trivial. We consider a $C^1$-submanifold $\d$ of $M$ whose dimension is equal
to the dimension of a fiber of the unstable bundle of $T_NM$. We suppose that
$\d$ transversely intersects the stable manifold of $N$. Then, we prove that
for all $\varepsilon>0$, and for $n$ $\in$ $\N$ large enough, there exists
$x_n$ $\in$ $N$ such that $f^n(\d)$ is $\varepsilon$-close, in the $C^1$
topology, to the strongly unstable manifold of $x_n$.
  As an application of this $\lambda$-lemma, we prove the existence of
shadowing orbits for a finite family of invariant minimal sets (for which we do
not assume any regularity) contained in a normally hyperbolic manifold and
having heteroclinic connections. As a particular case, we recover classical
results on the existence of diffusion orbits (Arnold's example).


title: Early stages of magnetization relaxation in superconductors

abstract:
  Magnetic flux dynamics in type-II superconductors is studied within the model
of a viscous nonlinear diffusion of vortices for various sample geometries. We
find that time dependence of magnetic moment relaxation after the field is
switched off can be accurately approximated by $m(t)\propto
1-\sqrt{t/\tilde\tau}$ in the narrow initial time interval and by $m(t)\propto
(1+t/\tau)^{-1}$ at later times before the flux creep sets in. The
characteristic times $\tilde\tau$ and $\tau$ are proportional to the viscous
drag coefficient $\eta$. Quantitative agreement with available experimental
data is obtained for both conventional and high-temperature superconductors
with $\eta$ exceeding by many orders of magnitude the Bardeen-Stephen
coefficient for free vortices. Huge enhancement of the drag, as well as its
exponential temperature dependence, indicates a strong influence of pinning
centers on the flux diffusion. Notwithstanding complexity of the vortex motion
in the presence of pinning and thermal agitation, we argue that the initial
relaxation of magnetization can still be considered as a viscous flux flow with
an effective drag coefficient.


title:
Post-processing of polymer foam tissue scaffolds with high power
  ultrasound: a route to increased pore interconnectivity, pore size and fluid
  transport

abstract:
  We expose thick polymer foam tissue scaffolds to high power ultrasound and
study its effect on the openness of the pore architecture and fluid transport
through the scaffold. Our analysis is supported by measurements of fluid uptake
during insonification and imaging of the scaffold microstructure via x-ray
computed tomography, scanning electron microscopy and acoustic microscopy. The
ultrasonic treatment is found to increase the mean pore size by over 10%. More
striking is the improvement in fluid uptake: for scaffolds with only 40% water
uptake via standard immersion techniques, we can routinely achieve full
saturation of the scaffold over approximately one hour of exposure. These
desirable modifications occur with no loss of scaffold integrity and negligible
mass loss, and are optimized when the ultrasound treatment is coupled to a
pre-wetting stage with ethanol. Our findings suggest that high power ultrasound
is a highly targetted and efficient means to promote pore interconnectivity and
fluid transport in thick foam tissue scaffolds.


title: PT symmetric lattices with a local degree of freedom

abstract:
  Recently, open systems with balanced, spatially separated loss and gain have
been realized and studied using non-Hermitian Hamiltonians that are invariant
under the combined parity and time-reversal ($\mathcal{PT}$) operations. Here,
we model and investigate the effects of a local, two-state, quantum degree of
freedom, called a pseudospin, on a one-dimensional tight-binding lattice with
position-dependent tunneling amplitudes and a single pair of non-Hermitian,
$\mathcal{PT}$-symmetric impurities. We show that if the resulting Hamiltonian
is invariant under exchange of two pseudospin labels, the system can be
decomposed into two uncoupled systems with tunable threshold for $\mathcal{PT}$
symmetry breaking. We discuss implications of our results to systems with
specific tunneling profiles, and open or periodic boundary conditions.


title:
Embedded triply periodic zero mean curvature surfaces of mixed type in
  Lorentz-Minkowski 3-space

abstract:
  We construct embedded triply periodic zero mean curvature surfaces of mixed
type in the Lorentz-Minkowski 3-space with the same topology as the Schwarz D
surface in the Euclidean 3-space.


title: Avalanche dynamics of elastic interfaces

abstract:
  Slowly driven elastic interfaces, such as domain walls in dirty magnets,
contact lines, or cracks proceed via intermittent motion, called avalanches. We
develop a field-theoretic treatment to calculate, from first principles, the
space-time statistics of instantaneous velocities within an avalanche. For
elastic interfaces at (or above) their (internal) upper critical dimension d >=
d_uc (d_uc = 2, 4 respectively for long-ranged and short-ranged elasticity) we
show that the field theory for the center of mass reduces to the motion of a
point particle in a random-force landscape, which is itself a random walk (ABBM
model). Furthermore, the full spatial dependence of the velocity correlations
is described by the Brownian-force model (BFM) where each point of the
interface sees an independent Brownian-force landscape. Both ABBM and BFM can
be solved exactly in any dimension d (for monotonous driving) by summing tree
graphs, equivalent to solving a (non-linear) instanton equation. This tree
approximation is the mean-field theory (MFT) for realistic interfaces in
short-ranged disorder. Both for the center of mass, and for a given Fourier
mode q, we obtain probability distribution functions (PDF's) of the velocity,
as well as the avalanche shape and its fluctuations (second shape). Within MFT
we find that velocity correlations at non-zero q are asymmetric under time
reversal. Next we calculate, beyond MFT, i.e. including loop corrections, the
1-time PDF of the center-of-mass velocity du/dt for dimension d< d_uc. The
singularity at small velocity P(du/dt) ~ 1/(du/dt)^a is substantially reduced
from a=1 (MFT) to a = 1 - 2/9 (4-d) + ... (short-ranged elasticity) and a = 1 -
4/9 (2-d) + ... (long-ranged elasticity). We show how the dynamical theory
recovers the avalanche-size distribution, and how the instanton relates to the
response to an infinitesimal step in the force.


title:
Introducing One Step Back Iterative Approach to Solve Linear and Non
  Linear Fixed Point Problem

abstract:
  In this paper, we introduce a new iterative method which we call one step
back approach: the main idea is to anticipate the consequence of the iterative
computation per coordinate and to optimize on the choice of the sequence of the
coordinates on which the iterative update computations are done. The method
requires the increase of the size of the state vectors and one iteration step
loss from the initial vector. We illustrate the approach in linear and non
linear iterative equations.


title: Sommes friables d'exponentielles et applications

abstract:
  An integer is said to be $y$-friable if its greatest prime factor is less
than $y$. In this paper, we obtain estimates for exponential sums over
$y$-friable numbers up to $x$ which are non-trivial when $y \geq \exp\{c
\sqrt{\log x} \log \log x\}$. As a consequence, we obtain an asymptotic formula
for the number of $y$-friable solutions to the equation $a+b=c$ which is valid
unconditionnally under the same assumption. We use a contour integration
argument based on the saddle point method, as developped in the context of
friable numbers by Hildebrand & Tenenbaum, and used by Lagarias, Soundararajan
and Harper to study exponential and character sums over friable numbers.


title:
Characterization of exponential distribution through equidistribution
  conditions for consecutive maxima

abstract:
  A characterization of the exponential distribution based on equidistribution
conditions for maxima of random samples with consecutive sizes n-1 and n for an
arbitrary and fixed n>2 is proved. This solves an open problem stated recently
in Arnold and Villasenor (2013).


title:
Non-Keplerian effects in precision radial velocity measurements of
  double-line spectroscopic binary stars: numerical simulations

abstract:
  Current precision in radial velocity (RV) measurements of binary stars
reaches $\sim$2 ms$^{-1}$. This level of precision means that RV models have to
take into account additional non-Keplerian effects such as tidal and rotational
distortion of the components of a binary star, relativistic effects and orbital
precession.
  We generate synthetic binaries using Yonsei-Yale stellar models. For typical
representatives we investigate the impact of various orbital orientations and
different non-Keplerian effects on the RV curves. To this end we simulate RV
observations with an added white noise of different scale. Subsequently we try
to reconstruct the input orbital parameters and their errors by fitting a model
using a standard least-squares method. In particular we investigate the
connection between the tidal distortion of the shape of the stars and the
best-fit orbital eccentricity, the possibility of deriving orbital inclination
of a non-eclipsing binary star by exploiting relativistic effects and the
circumstances in which the orbital precession can be detected.
  We confirm that the method proposed by to obtain orbital inclination with use
of the relativistic effect does work in favourable cases and that it can be
used even for orbital configurations far from an edge-on orientation. We show
that the RV variations imposed by tidally distorted stars can mimic non-zero
eccentricity in some binaries. The scale of such an effect depends on the RV
accuracy. Finally, we demonstrate that the apsidal precession can be easily
detected with precision RVs. In particular we can detect orbital precession of
$10^{-4}$ rad yr$^{-1}$, $10^{-3}$ rad yr$^{-1}$ for precision of RVs of 1
ms$^{-1}$ and 10 ms$^{-1}$ respectively.


title: Universal Landau Pole

abstract:
  Our understanding of quantum gravity suggests that at the Planck scale the
usual geometry loses its meaning. If so, the quest for grand unification in a
large non-abelian group naturally endowed with the property of asymptotic
freedom may also lose its motivation. Instead we propose an unification of all
fundamental interactions at the Planck scale in the form of a Universal Landau
Pole (ULP), at which all gauge couplings diverge. The Higgs quartic coupling
also diverges while the Yukawa couplings vanish. The unification is achieved
with the addition of fermions with vector gauge couplings coming in multiplets
and with hypercharges identical to those of the the Standard Model. The
presence of these particles also prevents the Higgs quartic coupling from
becoming negative, thus avoiding the instability (or metastability) of the SM
vacuum.


title:
Controlled coupling of photonic crystal cavities using photochromic
  tuning

abstract:
  We present a method to control the resonant coupling interaction in a
coupled-cavity photonic crystal molecule by using a local and reversible
photochromic tuning technique. We demonstrate the ability to tune both a
two-cavity and a three-cavity photonic crystal molecule through the resonance
condition by selectively tuning the individual cavities. Using this technique,
we can quantitatively determine important parameters of the coupled-cavity
system such as the photon tunneling rate. This method can be scaled to photonic
crystal molecules with larger numbers of cavities, which provides a versatile
method for studying strong interactions in coupled resonator arrays.


title: Engineering spin waves in a high-spin ultracold Fermi gas

abstract:
  We report on the detailed study of multi-component spin-waves in an s=3/2
Fermi gas where the high spin leads to novel tensorial degrees of freedom
compared to s = 1/2 systems. The excitations of a spin-nematic state are
investigated from the linear to the nonlinear regime, where the tensorial
character is particularly pronounced. By tuning the initial state we engineer
the tensorial spin-wave character, such that the magnitude and sign of the
counterflow spin-currents are effectively controlled. A comparison of our data
with numerical and analytical results shows excellent agreement.


title: Hall A Annual Report 2012

abstract:
  Report over the experimental activities in Hall A at Thomas Jefferson
National Accelerator Facility.