title:
Visualization of three-dimensional incompressible flows by
  quasi-two-dimensional divergence-free projections

abstract:
  A visualization of three-dimensional incompressible flows by divergence-free
quasi-two-dimensional projections of velocity field on three coordinate planes
is proposed. It is argued that such divergence-free projections satisfying all
the velocity boundary conditions are unique for a given velocity field. It is
shown that the projected fields and their vector potentials can be calculated
using divergence-free Galerkin bases. Using natural convection flow in a
laterally heated cube as an example, it is shown that the projection proposed
allow for a better understanding of similarities and differences of
three-dimensional flows and their two-dimensional likenesses. An arbitrary
choice of projection planes is further illustrated by a lid-driven flow in a
cube, where the lid moves parallel either to a sidewall or a diagonal plane.


title: The Goldman-Turaev Lie bialgebra and the Johnson homomorphisms

abstract:
  We survey a geometric approach to the Johnson homomorphisms using the
Goldman-Turaev Lie bialgebra.


title: Derivation of Hamiltonian mechanics from determinism and reversibility

abstract:
  We put forth the idea that Hamilton's equations coincide with deterministic
and reversible evolution. We explore the idea from five different perspectives
(mathematics, measurements, thermodynamics, information theory and state
mapping) and we show how they in the end coincide. We concentrate on a single
degree of freedom at first, then generalize. We also discuss possible
philosophical reasons why the laws of physics can only describe such processes,
even if others must exist.


title: On particle Gibbs sampling

abstract:
  The particle Gibbs sampler is a Markov chain Monte Carlo (MCMC) algorithm to
sample from the full posterior distribution of a state-space model. It does so
by executing Gibbs sampling steps on an extended target distribution defined on
the space of the auxiliary variables generated by an interacting particle
system. This paper makes the following contributions to the theoretical study
of this algorithm. Firstly, we present a coupling construction between two
particle Gibbs updates from different starting points and we show that the
coupling probability may be made arbitrarily close to one by increasing the
number of particles. We obtain as a direct corollary that the particle Gibbs
kernel is uniformly ergodic. Secondly, we show how the inclusion of an
additional Gibbs sampling step that reselects the ancestors of the particle
Gibbs' extended target distribution, which is a popular approach in practice to
improve mixing, does indeed yield a theoretically more efficient algorithm as
measured by the asymptotic variance. Thirdly, we extend particle Gibbs to work
with lower variance resampling schemes. A detailed numerical study is provided
to demonstrate the efficiency of particle Gibbs and the proposed variants.


title:
The complexity of interior point methods for solving discounted
  turn-based stochastic games

abstract:
  We study the problem of solving discounted, two player, turn based,
stochastic games (2TBSGs). Jurdzinski and Savani showed that 2TBSGs with
deterministic transitions can be reduced to solving $P$-matrix linear
complementarity problems (LCPs). We show that the same reduction works for
general 2TBSGs. This implies that a number of interior point methods for
solving $P$-matrix LCPs can be used to solve 2TBSGs. We consider two such
algorithms. First, we consider the unified interior point method of Kojima,
Megiddo, Noma, and Yoshise, which runs in time $O((1+\kappa)n^{3.5}L)$, where
$\kappa$ is a parameter that depends on the $n \times n$ matrix $M$ defining
the LCP, and $L$ is the number of bits in the representation of $M$. Second, we
consider the interior point potential reduction algorithm of Kojima, Megiddo,
and Ye, which runs in time $O(\frac{-\delta}{\theta}n^4\log \epsilon^{-1})$,
where $\delta$ and $\theta$ are parameters that depend on $M$, and $\epsilon$
describes the quality of the solution. For 2TBSGs with $n$ states and discount
factor $\gamma$ we prove that in the worst case $\kappa =
\Theta(n/(1-\gamma)^2)$, $-\delta = \Theta(\sqrt{n}/(1-\gamma))$, and $1/\theta
= \Theta(n/(1-\gamma)^2)$. The lower bounds for $\kappa$, $-\delta$, and
$1/\theta$ are obtained using the same family of deterministic games.


title:
X-ray spectral cut-off and the lack of hard X-ray emission from two
  ultraluminous X-ray sources M81 X-6 and Holmberg IX X-1

abstract:
  We present broadband X-ray spectral study of two ultraluminous X-ray sources
(ULXs), M81 X-6 and Holmberg IX X-1 based on Suzaku & XMM-Newton observations.
We perform joint broadband spectral analysis of the brightest sources in the
field, i.e. the two ULXs and the active galactic nucleus (AGN) in M81, and
demonstrate that the X-ray spectra of the ULXs cut off at energies more than
about 3keV with negligible contribution at high energies in the Suzaku HXD/PIN
band. The 90% upper limit on the 10-30keV band luminosity of an underlying
broadband power-law component is 3.5e38 ergs/s for M81 X-6 and 1.2e39ergs/s for
Holmberg IX X-1. These limits are more than an order of magnitude lower than
the bolometric (0.1-30 keV) luminosity of 6.8e39ergs/s for M81 X-6 and 1.9e40
ergs/s for Holmberg IX X-1. Our results confirm earlier indications of spectral
cut-offs inferred from the XMM-Newton observations of bright ULXs and show that
there isn't an additional high energy power-law component contributing
significantly to the X-ray emission. The spectral form of the two ULXs are very
different from those of Galactic black hole X-ray binaries (BHBs) or AGNs. This
implies that the ULXs are neither simply scaled-up versions of stellar mass
BHBs or scaled-down versions of AGNs.


title: Noether's problem for abelian extensions of cyclic $p$-groups II

abstract:
  Let $K$ be a field and $G$ be a finite group. Let $G$ act on the rational
function field $K(x(g):g\in G)$ by $K$ automorphisms defined by $g\cdot
x(h)=x(gh)$ for any $g,h\in G$. Denote by $K(G)$ the fixed field $K(x(g):g\in
G)^G$. Noether's problem then asks whether $K(G)$ is rational (i.e., purely
transcendental) over $K$. Let $p$ be any prime and let $G$ be a $p$-group of
exponent $p^e$. Assume also that {\rm (i)} char $K = p>0$, or {\rm (ii)} char
$K \ne p$ and $K$ contains a primitive $p^e$-th root of unity. In this paper we
prove that if $G$ is any $p$-group of nilpotency class 2, which has the ABC
(Abelian-By-Cyclic) property, then $K(G)$ is rational over $K$. We also prove
the rationality of $K(G)$ over $K$ for two 3-generator $p$-groups $G$ of
arbitrary nilpotency class.


title:
Reggeometry of deeply virtual Compton scattering (DVCS) and exclusive
  vector meson production (VMP) at HERA

abstract:
  A Reggeometric (Regge+Geometry) model, based on the observed proportionality
between the forward slope of the differential cross section and the interaction
radius, the latter depending on virtuality Q2 of the incoming virtual photon
and on the mass M 2 of the produced particle, is constructed. The objective of
this study is the dependence of the Regge-pole amplitude on the virtuality Q2
and masses of the external particles, which remains an open problem for the
theory. The present analysis is based on the HERA data on Deeply Virtual
Compton Scattering (DVCS) and exclusive diffractive Vector Meson Production
(VMP). We treat each class of reactions separately, anticipating a further
study that will include both a soft and a hard component of the unique pomeron.


title:
Proposal for a computation procedure based on continuous-variable
  post-selected teleportation

abstract:
  In this paper, we analyze a potential procedure based on the combination of
an alternative information encoding system inside the state of an
electromagnetic mode and on continuous-variable post-selected teleportation,
for speed up computational power of a classic architecture up to resolution of
problems in PSPACE.


title:
Helical Andreev bound states and superconducting Klein tunneling in
  topological insulator Josephson junctions

abstract:
  Currently, much effort is being put into detecting unconventional p-wave
superconductivity in Josephson junctions based on topological insulators (TIs).
For that purpose we propose to use superconducting Klein tunneling, i.e. the
reflectionless passage of Cooper pairs through a potential barrier in a gated
ballistic junction. This phenomenon occurs due to the fact that the
supercurrent is carried by helical Andreev bound states (ABSs) characterized by
spin-momentum locking similar to the normal-state carriers. We derive the
spectrum of the helical ABSs and the corresponding Josephson current for a
junction made on the surface of a three-dimensional TI. The superconducting
Klein tunneling is predicted to yield a non-sinusoidal current-phase relation
and an anomalous critical current $I_c$ that does not vanish with increasing
barrier strength. We also analyze the dependence of the I_cR_n product (where
R_n is the normal-state junction resistance) on the microscopic parameters of
the superconductor/TI interface, which leads to lower I_cR_n values than
expected from previous models of the proximity-effect Josephson junctions.


title: The CDMS view on molecular data needs of Herschel, SOFIA, and ALMA

abstract:
  The catalog section of the Cologne Database for Molecular Spectroscopy, CDMS,
contains mostly rotational transition frequencies, with auxiliary information,
of molecules observable in space. The frequency lists are generated mostly from
critically evaluated laboratory data employing established Hamiltonian models.
The CDMS has been online publicly for more than 12 years, e.g., via the
short-cut http://www.cdms.de. Initially constructed as ascii tables, its
inclusion into a database environment within the Virtual Atomic and Molecular
Data Centre (VAMDC, http://www.vamdc.eu) has begun in June 2008. A test version
of the new CDMS is about to be released. The CDMS activities have been part of
the extensive laboratory spectroscopic investigations in Cologne. Moreover,
these activities have also benefit from collaborations with other laboratory
spectroscopy groups as well as with astronomers. We will provide some basic
information on the CDMS and its participation in the VAMDC project. In
addition, some recent detections of molecules as well as spectroscopic studies
will be discussed to evaluate the spectroscopic data needs of Herschel, SOFIA,
and ALMA in particular in terms of light hydrides, complex molecules, and metal
containing species

categories: astro-ph.GA astro-ph.CO astro-ph.IM physics.atm-clus


title: De- and Re-constructing Introductory Physics for the Life Sciences

abstract:
  Teaching physics to biologists requires far more than making the course for
engineers mathematically less rigorous and adding in a few superficial
biological problems. What is needed is for physicists to work closely with
biologists to learn not only what physics topics and habits of mind that are
useful to biologists, but how biologists work is fundamentally different from
ours, and how to bridge that gap. In this article, we discussed what we have
learned about these issues from years of conversations with colleagues in
biology.


title:
Parenclitic networks: a multilayer description of heterogeneous and
  static data-sets

abstract:
  Describing a complex system is in many ways a problem akin to identifying an
object, in that it involves defining boundaries, constituent parts and their
relationships by the use of grouping laws. Here we propose a novel method which
extends the use of complex networks theory to a generalized class of
non-Gestaltic systems, taking the form of collections of isolated, possibly
heterogeneous, scalars, e.g. sets of biomedical tests. The ability of the
method to unveil relevant information is illustrated for the case of gene
expression in the response to osmotic stress of {\it Arabidopsis thaliana}. The
most important genes turn out to be the nodes with highest centrality in
appropriately reconstructed networks. The method allows predicting a set of 15
genes whose relationship with such stress was previously unknown in the
literature. The validity of such predictions is demonstrated by means of a
target experiment, in which the predicted genes are one by one artificially
induced, and the growth of the corresponding phenotypes turns out to feature
statistically significant differences when compared to that of the wild-type.


title:
Ferromagnetic Quantum Critical Point in FeGa3 Tuned by Mixed-Valence Fe
  Dimers

abstract:
  The magnetic, transport, and thermal properties of single crystals of the
series Fe(Ga1-xGex)3 are reported. Pure FeGa3 is a nonmagnetic semiconductor,
that when doped with small concentrations of Ge (extrinsic electrons), passes
through an insulator-to-metal transition and displays non-Fermi liquid (NFL)
behavior. Moreover, we observer clear signatures of a ferromagnetic quantum
critical point (FM-QCP) in this system at x = 0.052. The mechanism of the local
moment formation is consistent with a one-electron reduction of Fe dimer
singlets, a unique structural feature in FeGa3, where the density of these
mixed valence (Fe(III)-Fe(II)) dimers provides a unique tuning parameter of
quantum criticality.


title: Socio-inspired ICT - Towards a socially grounded society-ICT symbiosis

abstract:
  Modern ICT (Information and Communication Technology) has developed a vision
where the "computer" is no longer associated with the concept of a single
device or a network of devices, but rather the entirety of situated services
originating in a digital world, which are perceived through the physical world.
It is observed that services with explicit user input and output are becoming
to be replaced by a computing landscape sensing the physical world via a huge
variety of sensors, and controlling it via a plethora of actuators. The nature
and appearance of computing devices is changing to be hidden in the fabric of
everyday life, invisibly networked, and omnipresent, with applications greatly
being based on the notions of context and knowledge. Interaction with such
globe spanning, modern ICT systems will presumably be more implicit, at the
periphery of human attention, rather than explicit, i.e. at the focus of human
attention. Socio-inspired ICT assumes that future, globe scale ICT systems
should be viewed as social systems. Such a view challenges research to identify
and formalize the principles of interaction and adaptation in social systems,
so as to be able to ground future ICT systems on those principles. This
position paper therefore is concerned with the intersection of social behaviour
and modern ICT, creating or recreating social conventions and social contexts
through the use of pervasive, globe-spanning, omnipresent and participative
ICT.


title:
Time-Dependent Schrodinger Equation for Black Hole Evaporation: no
  Information Loss

abstract:
  In 1976 S. Hawking claimed that "Because part of the information about the
state of the system is lost down the hole, the final situation is represented
by a density matrix rather than a pure quantum state" (Verbatim from ref. 2).
This was the starting point of the popular "black hole (BH) information
paradox". In a series of papers, together with collaborators, we naturally
interpreted BH quasi-normal modes (QNMs) in terms of quantum levels discussing
a model of excited BH somewhat similar to the historical semi-classical Bohr
model of the structure of a hydrogen atom. Here we explicitly write down, for
the same model, a time dependent Schr\"odinger equation for the system composed
by Hawking radiation and BH QNMs. The physical state and the correspondent wave
function are written in terms of an unitary evolution matrix instead of a
density matrix. Thus, the final state results to be a pure quantum state
instead of a mixed one. Hence, Hawking's claim is falsified because BHs result
to be well defined quantum mechanical systems, having ordered, discrete quantum
spectra, which respect 't Hooft's assumption that Schr\"oedinger equations can
be used universally for all dynamics in the universe. As a consequence,
information comes out in BH evaporation in terms of pure states in an unitary
time dependent evolution. In Section 4 of this paper we show that the present
approach permits also to solve the entanglement problem connected with the
information paradox.


title:
The implementation of the parallel shortest vector enumerate in the
  block Korkin-Zolotarev method

abstract:
  This article present a parallel CPU implementation of Kannan algorithm for
solving shortest vector problem in Block Korkin-Zolotarev lattice reduction
method. Implementation based on Native POSIX Thread Library and show linear
decrease of runtime from number of threads.


title:
Effect of activation procedure on Sm-Co-Fe-Zr-B compound for low
  temperature efficient hydrogen storage

abstract:
  The present research work is focused on the effect of activation procedure on
the hydrogen absorption-desorption properties of new rare earth transition
metal compound based on Sm(Co0.6Fe0.2Zr0.16B0.04)7.5 composition. Crystal
structure and composition is always connected to the maximum capacity of the
intermetallic hydrides. For composite materials the thermodynamic properties of
hydrogenation & dehydrogenation procedure are mostly explained through
microstructure-microchemistry characteristics. Efficient hydrogen storage is
direct connected to the desorbed hydrogen amount. The as hydrogenated material
Sm(Co0.6Fe0.2Zr0.16B0.04)7.5 seems to have in the desorption a pressure plateau
below the atmospheric pressure at room temperature while the absorbed hydrogen
almost remains in the material having capacity of ~0.8 wt. % at 0.1 MPa - 30
oC. After the proper activation procedure, the hydrogenated material desorbs
very high amount of hydrogen ~1.9 wt. % at 0.1 MPa - 100 oC. Subsequently, the
treatment of the composite materials before hydrogenation & dehydrogenation
procedures could play a crucial role on the efficiency.


title:
Multiparty Compatibility in Communicating Automata: Characterisation and
  Synthesis of Global Session Types

abstract:
  Multiparty session types are a type system that can ensure the safety and
liveness of distributed peers via the global specification of their
interactions. To construct a global specification from a set of distributed
uncontrolled behaviours, this paper explores the problem of fully
characterising multiparty session types in terms of communicating automata. We
equip global and local session types with labelled transition systems (LTSs)
that faithfully represent asynchronous communications through unbounded
buffered channels. Using the equivalence between the two LTSs, we identify a
class of communicating automata that exactly correspond to the projected local
types. We exhibit an algorithm to synthesise a global type from a collection of
communicating automata. The key property of our findings is the notion of
multiparty compatibility which non-trivially extends the duality condition for
binary session types.


title: Towards a living earth simulator

abstract:
  The Living Earth Simulator (LES) is one of the core components of the
FuturICT architecture. It will work as a federation of methods, tools,
techniques and facilities supporting all of the FuturICT simulation-related
activities to allow and encourage interactive exploration and understanding of
societal issues. Society-relevant problems will be targeted by leaning on
approaches based on complex systems theories and data science in tight
interaction with the other components of FuturICT. The LES will evaluate and
provide answers to real-world questions by taking into account multiple
scenarios. It will build on present approaches such as agent-based simulation
and modeling, multiscale modelling, statistical inference, and data mining,
moving beyond disciplinary borders to achieve a new perspective on complex
social systems.


title: Fate of chiral critical point under the strong isospin asymmetry

abstract:
  We study the influence of the isospin asymmetry on the phase structure of
strongly interacting quark matter near the critical point (CP) using a
Ginzburg-Landau approach. The effect is found to be drastic, not only bringing
about the shift of the location of the CP, but resulting in a rich phase
structure in the vicinity of the CP. In particular, new tricritical and triple
points emerge as soon as the isospin density becomes finite. Moreover, we find
the CP being washed out from the phase diagram due to the stabilization of a
homogeneous charged pion condensate when the isospin chemical potential exceeds
a critical value. We derive a model-independent universal relation between the
critical isospin chemical potential and the chiral condensate at the CP. We
also study the effect of the $\mathrm{U}(1)_\mathrm{A}$ anomaly on the phase
transition to the pion condensate in the vicinity of chiral crossover.


title: Mixed mock modular q-series

abstract:
  Mixed mock modular forms are functions which lie in the tensor space of mock
modular forms and modular forms. As q-hypergeometric series, mixed mock modular
forms appear to be much more common than mock theta functions. In this survey,
we discuss some of the ways such series arise.


title: Lines of axial curvature at critical points on surfaces mapped into R4

abstract:
  In this paper are studied the simplest patterns of axial curvature lines
(along which the normal curvature vector is at a vertex of the ellipse of
curvature) near a critical point of a surface mapped into R4. These critical
points, where the rank of the mapping drops from 2 to 1, occur isolated in
generic one parameter families of mappings of surfaces into R4. As the
parameter crosses a critical bifurcation value, at which the mapping has a
critical point, it is described how the axial umbilic points, which are the
singularities of the axial curvature configurations at regular points, move
along smooth arcs to reach the critical point. The numbers of such arcs and
their axial umbilic types are fully described for a typical family of mappings
with a critical point.


title:
Positive solutions to a supercritical elliptic problem which concentrate
  along a thin spherical hole

abstract:
  We consider the supercritical problem \[ -\Delta v=|v|^{p-2}v in
\Theta_{\epsilon}, v=0 on \partial\Theta_{\epsilon}, \] where $\Theta$ is a
bounded smooth domain in $\mathbb{R}^{N}$, $N\geq3$, $p>2^{\ast}:=2N/(N-2)$,
and $\Theta_{\epsilon}$ is obtained by deleting the $\epsilon$-neighborhood of
some sphere which is embedded in $\Theta$. In some particular situations we
show that, for $\epsilon>0$ small enough, this problem has a positive solution
$v_{\epsilon}$ and that these solutions concentrate and blow up along the
sphere as $\epsilon$ tends to 0.
  Our approach is to reduce this problem to a critical problem of the form \[
-\Delta u=Q(x)|u|^{4/(n-2)}u in \Omega_{\epsilon}, u=0 on
\partial\Omega_{\epsilon}, \] in a punctured domain
$\Omega_{\epsilon}:=\{x\in\Omega:|x-\xi_{0}|>\epsilon\}$ of lower dimension, by
means of some Hopf map. We show that, if $\Omega$ is a bounded smooth domain in
$\mathbb{R}^{n}$, $n\geq3$, $\xi_{0} is in\Omega,$ $Q is in
C^{2}(\b{\Oarmega})$ is positive and $\nabla Q(\xi_{0})\neq0$ then, for
$\epsilon>0$ small enough, this problem has a positive solution $u_{\epsilon}$,
and that these solutions concentrate and blow up at $\xi_{0}$ as $\epsilon$
goes to 0.


title: A supercritical elliptic problem in a cylindrical shell

abstract:
  We consider the problem \[ -\Delta u=|u|^{p-2}u in \Omega, u=0 on
\partial\Omega, \] where
$\Omega:=\{(y,z)\in\mathbb{R}^{m+1}\times\mathbb{R}^{N-m-1}:
0<a<|y|<b<\infty\}$, $0\leq m\leq N-1$ and $N\geq2$. Let
$2_{N,m}^{\ast}:=2(N-m)/(N-m-2)$ if $m<N-2$ and $2_{N,m}^{\ast}:=\infty$ if
$m=N-2$ or $N-1$. We show that $2_{N,m}^{\ast}$ is the true critical exponent
for this problem, and that there exist nontrivial solutions if
$2<p<2_{N,m}^{\ast}$ but there are no such solutions if $p\geq2_{N,m}^{\ast}$.


title: Network Farthest-Point Diagrams

abstract:
  Consider the continuum of points along the edges of a network, i.e., an
undirected graph with positive edge weights. We measure distance between these
points in terms of the shortest path distance along the network, known as the
network distance. Within this metric space, we study farthest points.
  We introduce network farthest-point diagrams, which capture how the farthest
points---and the distance to them---change as we traverse the network. We
preprocess a network G such that, when given a query point q on G, we can
quickly determine the farthest point(s) from q in G as well as the farthest
distance from q in G. Furthermore, we introduce a data structure supporting
queries for the parts of the network that are farther away from q than some
threshold R > 0, where R is part of the query.
  We also introduce the minimum eccentricity feed-link problem defined as
follows. Given a network G with geometric edge weights and a point p that is
not on G, connect p to a point q on G with a straight line segment pq, called a
feed-link, such that the largest network distance from p to any point in the
resulting network is minimized. We solve the minimum eccentricity feed-link
problem using eccentricity diagrams. In addition, we provide a data structure
for the query version, where the network G is fixed and a query consists of the
point p.


title: Non-equilibrium dynamics of a system with Quantum Frustration

abstract:
  Using flow equations, equilibrium and non-equilibrium dynamics of a two-level
system are investigated, which couples via non-commuting components to two
independent oscillator baths. In equilibrium the two-level energy splitting is
protected when the TLS is coupled symmetrically to both bath. A critical
asymmetry angle separates the localized from the delocalized phase.
  On the other hand, real-time decoherence of a non-equilibrium initial state
is for a generic initial state faster for a coupling to two baths than for a
single bath.


title:
Superconducting-insulator transition in disordered Josephson junctions
  networks

abstract:
  The superconducting-insulator transition is simulated in disordered networks
of Josephson junctions with thermally activated Arrhenius-like resistive shunt.
By solving the conductance matrix of the network, the transition is reproduced
in different experimental conditions by tuning thickness, charge density and
disorder degree. In particular, on increasing fluctuations of the parameters
entering the Josephson coupling and the Coulomb energy of the junctions, the
transition occurs for decreasing values of the critical temperature Tc and
increasing values of the activation temperature To. The results of the
simulation compare well with recent experiments where the mesoscopic
fluctuations of the phase have been suggested as the mechanism underlying the
phenomenon of emergent granularity in otherwise homogeneous films. The proposed
approach is compared with the results obtained on TiN films and nanopatterned
arrays of weak-links, where the superconductor-insulator transition is directly
stimulated.


title: Compact extra dimensions in cosmologies with f(T) structure

abstract:
  The presence of compact extra dimensions in cosmological scenarios in the
context of f(T)-like gravities is discussed. For the case of toroidal
compactifications, the analysis is performed in an arbitrary number of extra
dimensions. Spherical topologies for the extra dimensions are then carefully
studied in six and seven spacetime dimensions, where the proper vielbein fields
responsible for the parallelization process are found.


title: Towards Efficient Abstractions for Concurrent Consensus

abstract:
  Consensus is an often occurring problem in concurrent and distributed
programming. We present a programming language with simple semantics and
build-in support for consensus in the form of communicating transactions. We
motivate the need for such a construct with a characteristic example of
generalized consensus which can be naturally encoded in our language. We then
focus on the challenges in achieving an implementation that can efficiently run
such programs. We setup an architecture to evaluate different implementation
alternatives and use it to experimentally evaluate runtime heuristics. This is
the basis for a research project on realistic programming language support for
consensus.


title:
Causal--Path Local Time--Stepping in the Discontinuous Galerkin Method
  for Maxwell's equations

abstract:
  We introduce a novel local time-stepping technique for marching-in-time
algorithms. The technique is denoted as Causal-Path Local Time-Stepping (CPLTS)
and it is applied for two time integration techniques: fourth order
low--storage explicit Runge--Kutta (LSERK4) and second order Leapfrog (LF2).
The CPLTS method is applied to evolve Maxwell's curl equations using a
Discontinuous Galerkin (DG) scheme for the spatial discretization. Numerical
results for LF2 and LSERK4 are compared with analytical solutions and the
Montseny's LF2 technique. The results show that the CPLTS technique improves
the dispersive and dissipative properties of LF2-LTS scheme.


title: Computing boundary extensions of conformal maps part 2

abstract:
  It is shown that there is a computable conformal map of the unit disk onto a
domain $D$ that has a computable extension to the closure of the unit disk even
though the boundary of $D$ is not effectively locally connected. The proof
encodes an arbitrary \emph{c.e.} set into the local connectivity of the
boundary of $D$.


title: Optimal Discrete Uniform Generation from Coin Flips, and Applications

abstract:
  This article introduces an algorithm to draw random discrete uniform
variables within a given range of size n from a source of random bits. The
algorithm aims to be simple to implement and optimal both with regards to the
amount of random bits consumed, and from a computational perspective---allowing
for faster and more efficient Monte-Carlo simulations in computational physics
and biology. I also provide a detailed analysis of the number of bits that are
spent per variate, and offer some extensions and applications, in particular to
the optimal random generation of permutations.

categories: cs.DS math.PR physics.comp-ph physics.data-an


title:
A Galois-theoretic proof of the differential transcendence of the
  incomplete Gamma function

abstract:
  We give simple necessary and sufficient conditions for the
$\frac{\partial}{\partial t}$-transcendence of the solutions to a parameterized
second order linear differential equation of the form \frac{\partial^2
Y}{\partial x^2} - p \frac{\partial Y}{\partial x} = 0, where $p\in F(x)$ is a
rational function in $x$ with coefficients in a $\frac{\partial}{\partial
t}$-field $F$. This result is crucial for the development of an efficient
algorithm to compute the parameterized Picard-Vessiot group of an arbitrary
parameterized second-order linear differential equation over $F(x)$. Our
criteria imply, in particular, the $\frac{\partial}{\partial t}$-transcendence
of the incomplete Gamma function $\gamma(t,x)$, generalizing a result of
Johnson, Reinhart, and Rubel [9].


title:
Double pion photoproduction off nuclei - are there effects beyond
  final-state interaction?

abstract:
  Photoproduction of $\pi^{0}\pi^{0}$ and $\pi^{0}\pi^{\pm}$ pairs from nuclei
has been measured over a wide mass range ($^2$H, $^{7}$Li, $^{12}$C, $^{40}$Ca,
and $^{\rm nat}$Pb) for photon energies from threshold to 600 MeV. The
experiments were performed at the MAMI accelerator in Mainz, using the Glasgow
photon tagging spectrometer and a 4$\pi$ electromagnetic calorimeter consisting
of the Crystal Ball and TAPS detectors. A shift of the pion-pion invariant mass
spectra for heavy nuclei to small invariant masses has been observed for
$\pi^0$ pairs but also for the mixed-charge pairs. The precise results allow
for the first time a model-independent analysis of the influence of pion
final-state interactions. The corresponding effects are found to be large and
must be carefully considered in the search for possible in-medium modifications
of the $\sigma$-meson. Results from a transport model calculation reproduce the
shape of the invariant-mass distributions for the mixed-charge pairs better
than for the neutral pairs, but also for the latter differences between model
results and experiment are not large, leaving not much room for
$\sigma$-in-medium modification.


title:
Measurement of the beam-helicity asymmetry $I^{\odot}$ in the
  photoproduction of $\pi^0$-pairs off the proton and off the neutron

abstract:
  Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz
for the photoproduction of neutral pion pairs in the reactions
$\vec{\gamma}p\rightarrow p\pi^0\pi^0$ and $\vec{\gamma}d\rightarrow
(n)p\pi^0\pi^0$, $\vec{\gamma}d\rightarrow (p)n\pi^0\pi^0$ off free protons and
off quasi-free nucleons bound in the deuteron for incident photon energies up
to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of
longitudinally polarized electrons and tagged with the Glasgow magnetic
spectrometer. Decay photons from the $\pi^0$ mesons, recoil protons, and recoil
neutrons were detected in the 4$\pi$ covering electromagnetic calorimeter
composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction
of the final state, excellent agreement was found between the results for free
and quasi-free protons. This demonstrates that the free-nucleon behavior of
such observables can be extracted from measurements with quasi-free nucleons,
which is the only possibility for the neutron. Contrary to expectations, the
measured asymmetries are very similar for reactions off protons and neutrons.
The results are compared to the predictions from the Two-Pion-MAID reaction
model and (for the proton) also to the Bonn-Gatchina coupled channel analysis.


title: Generalizing the No-U-Turn Sampler to Riemannian Manifolds

abstract:
  Hamiltonian Monte Carlo provides efficient Markov transitions at the expense
of introducing two free parameters: a step size and total integration time.
Because the step size controls discretization error it can be readily tuned to
achieve certain accuracy criteria, but the total integration time is left
unconstrained. Recently Hoffman and Gelman proposed a criterion for tuning the
integration time in certain systems with their No U-Turn Sampler, or NUTS. In
this paper I investigate the dynamical basis for the success of NUTS and
generalize it to Riemannian Manifold Hamiltonian Monte Carlo.


title:
Coronal loop physical parameters from the analysis of multiple observed
  transverse oscillations

abstract:
  The analysis of quickly damped transverse oscillations of solar coronal loops
using magneto-hydrodynamic seismology allow us to infer physical parameters
that are difficult to measure otherwise. Under the assumption that such damped
oscillations are due to the resonant conversion of global modes into Alfven
oscillations of the tube surface, we carry out a global seismological analysis
of a large set of coronal loops. A Bayesian hierarchical method is used to
obtain distributions for coronal loop physical parameters by means of a global
analysis of a large number of observations. The resulting distributions
summarise global information and constitute data-favoured information that can
be used for the inversion of individual events. The results strongly suggest
that internal Alfven travel times along the loop are larger than 100 s and
smaller than 540 s with 95% probability. Likewise, the density contrast between
the loop interior and the surrounding is larger than 2.3 and below 6.9 with 95%
probability.


title: On the simplicity of Lie algebra of Leavitt path algebra

abstract:
  For a field $F$ and a row-finite directed graph $\Gamma$ let $L(\Gamma)$ be
the Leavitt path algebra. We find necessary and sufficient conditions for the
Lie algebra $[L(\Gamma),L(\Gamma)]$ to be simple.


title:
Properly immersed minimal surfaces in a slab of H(2)xR, H(2) the
  hyperbolic plane

abstract:
  We prove that the ends of a properly immersed simply or one connected minimal
surface in H(2)xR contained in a slab of height less than \pi of H(2)xR, are
multi-graphs. When such a surface is embedded then the ends are graphs. When
embedded and simply connected, it is an entire graph.


title:
Automatic Detection of Search Tactic in Individual Information Seeking:
  A Hidden Markov Model Approach

abstract:
  Information seeking process is an important topic in information seeking
behavior research. Both qualitative and empirical methods have been adopted in
analyzing information seeking processes, with major focus on uncovering the
latent search tactics behind user behaviors. Most of the existing works require
defining search tactics in advance and coding data manually. Among the few
works that can recognize search tactics automatically, they missed making sense
of those tactics. In this paper, we proposed using an automatic technique, i.e.
the Hidden Markov Model (HMM), to explicitly model the search tactics. HMM
results show that the identified search tactics of individual information
seeking behaviors are consistent with Marchioninis Information seeking process
model. With the advantages of showing the connections between search tactics
and search actions and the transitions among search tactics, we argue that HMM
is a useful tool to investigate information seeking process, or at least it
provides a feasible way to analyze large scale dataset.


title: Observation of flux tube crossings in the solar wind

abstract:
  Current sheets are ubiquitous in the solar wind.They are a major source of
the solar wind MHD turbulence intermittency. They may result from non-linear
interactions of the solar wind MHD turbulence or are the boundaries of flux
tubes that originate from the solar surface. Some current sheets appear in
pairs and are the boundaries of transient structures such as magnetic holes and
reconnection exhausts, or the edges of pulsed Alfv\'{e}n waves. For an
individual current sheet, discerning whether it is a flux tube boundary or due
to non-linear interactions, or the boundary of a transient structure is
difficult. In this work, using data from the {\sl Wind} spacecraft, we identify
two three-current-sheet events. Detailed examination of these two events
suggest that they are best explained by the flux tube crossing scenario. Our
study provides a convincing evidence supporting the scenario that the solar
wind consists of flux tubes where distinct plasmas reside.


title:
Distributed Space-Time Coding Based on Adjustable Code Matrices for
  Cooperative MIMO Relaying Systems

abstract:
  An adaptive distributed space-time coding (DSTC) scheme is proposed for
two-hop cooperative MIMO networks. Linear minimum mean square error (MMSE)
receive filters and adjustable code matrices are considered subject to a power
constraint with an amplify-and-forward (AF) cooperation strategy. In the
proposed adaptive DSTC scheme, an adjustable code matrix obtained by a feedback
channel is employed to transform the space-time coded matrix at the relay node.
The effects of the limited feedback and the feedback errors are assessed.
Linear MMSE expressions are devised to compute the parameters of the adjustable
code matrix and the linear receive filters. Stochastic gradient (SG) and
least-squares (LS) algorithms are also developed with reduced computational
complexity. An upper bound on the pairwise error probability analysis is
derived and indicates the advantage of employing the adjustable code matrices
at the relay nodes. An alternative optimization algorithm for the adaptive DSTC
scheme is also derived in order to eliminate the need for the feedback. The
algorithm provides a fully distributed scheme for the adaptive DSTC at the
relay node based on the minimization of the error probability. Simulation
results show that the proposed algorithms obtain significant performance gains
as compared to existing DSTC schemes.


title: A hierarchy of heuristic-based models of crowd dynamics

abstract:
  We derive a hierarchy of kinetic and macroscopic models from a noisy variant
of the heuristic behavioral Individual-Based Model of Moussaid et al, PNAS
2011, where the pedestrians are supposed to have constant speeds. This IBM
supposes that the pedestrians seek the best compromise between navigation
towards their target and collisions avoidance. We first propose a kinetic model
for the probability distribution function of the pedestrians. Then, we derive
fluid models and propose three different closure relations. The first two
closures assume that the velocity distribution functions are either a Dirac
delta or a von Mises-Fisher distribution respectively. The third closure
results from a hydrodynamic limit associated to a Local Thermodynamical
Equilibrium. We develop an analogy between this equilibrium and Nash equilibia
in a game theoretic framework. In each case, we discuss the features of the
models and their suitability for practical use.


title:
A probabilistic algorithm to compute the real dimension of a
  semi-algebraic set

abstract:
  Let $\RR$ be a real closed field (e.g. the field of real numbers) and
$\mathscr{S} \subset \RR^n$ be a semi-algebraic set defined as the set of
points in $\RR^n$ satisfying a system of $s$ equalities and inequalities of
multivariate polynomials in $n$ variables, of degree at most $D$, with
coefficients in an ordered ring $\ZZ$ contained in $\RR$. We consider the
problem of computing the {\em real dimension}, $d$, of $\mathscr{S}$. The real
dimension is the first topological invariant of interest; it measures the
number of degrees of freedom available to move in the set. Thus, computing the
real dimension is one of the most important and fundamental problems in
computational real algebraic geometry. The problem is ${\rm
NP}_{\mathbb{R}}$-complete in the Blum-Shub-Smale model of computation. The
current algorithms (probabilistic or deterministic) for computing the real
dimension have complexity $(s \, D)^{O(d(n-d))}$, that becomes $(s \,
D)^{O(n^2)}$ in the worst-case. The existence of a probabilistic or
deterministic algorithm for computing the real dimension with single
exponential complexity with a factor better than ${O(n^2)}$ in the exponent in
the worst-case, is a longstanding open problem. We provide a positive answer to
this problem by introducing a probabilistic algorithm for computing the real
dimension of a semi-algebraic set with complexity $(s\, D)^{O(n)}$.


title: Dimensional contraction via Markov transportation distance

abstract:
  It is now well known that curvature conditions \`a la Bakry-Emery are
equivalent to contraction properties of the heat semigroup with respect to the
classical quadratic Wasserstein distance. However, this curvature condition may
include a dimensional correction which up to now had not induced any
strenghtening of this contraction. We first consider the simplest example of
the Euclidean heat semigroup, and prove that indeed it is so. To consider the
case of a general Markov semigroup, we introduce a new distance between
probability measures, based on the semigroup, and adapted to it. We prove that
this Markov transportation distance satisfies the same properties for a general
Markov semigroup as the Wasserstein distance does in the specific case of the
Euclidean heat semigroup, namely dimensional contraction properties and
Evolutional variational inequalities.


title: Client-Driven Content Extraction Associated with Table

abstract:
  The goal of the project is to extract content within table in document images
based on learnt patterns. Real-world users i.e., clients first provide a set of
key fields within the table which they think are important. These are first
used to represent the graph where nodes are labelled with semantics including
other features and edges are attributed with relations. Attributed relational
graph (ARG) is then employed to mine similar graphs from a document image. Each
mined graph will represent an item within the table, and hence a set of such
graphs will compose a table. We have validated the concept by using a
real-world industrial problem.


title: On Gaussian Beams Described by Jacobi's Equation

abstract:
  Gaussian beams describe the amplitude and phase of rays and are widely used
to model acoustic propagation. This paper describes four new results in the
theory of Gaussian beams. (1) A new version of the \v{C}erven\'y equations for
the amplitude and phase of Gaussian beams is developed by applying the
equivalence of Hamilton-Jacobi theory with Jacobi's equation that connects
Riemannian curvature to geodesic flow. Thus the paper makes a fundamental
connection between Gaussian beams and an acoustic channel's so-called intrinsic
Gaussian curvature from differential geometry. (2) A new formula
$\pi(c/c")^{1/2}$ for the distance between convergence zones is derived and
applied to several well-known profiles. (3) A class of "model spaces" are
introduced that connect the acoustics of ducting/divergence zones with the
channel's Gaussian curvature $K=cc"-(c')^2$. The "model" SSPs yield constant
Gaussian curvature in which the geometry of ducts corresponds to great circles
on a sphere and convergence zones correspond to antipodes. The distance between
caustics $\pi(c/c")^{1/2}$ is equated with an ideal hyperbolic cosine SSP duct.
(4) An "intrinsic" version of \v{C}erven\'y's formulae for the amplitude and
phase of Gaussian beams is derived that does not depend on an "extrinsic"
arbitrary choice of coordinates such as range and depth. Direct comparisons are
made between the computational frameworks used by the three different
approaches to Gaussian beams: Snell's law, the extrinsic Frenet-Serret
formulae, and the intrinsic Jacobi methods presented here. The relationship of
Gaussian beams to Riemannian curvature is explained with an overview of the
modern covariant geometric methods that provide a general framework for
application to other special cases.

categories: math-ph math.DG math.MG math.MP physics.ao-ph physics.optics


title:
Generalized Reduced-Rank Decompositions Using Switching and Adaptive
  Algorithms for Space-Time Adaptive Processing

abstract:
  This work presents generalized low-rank signal decompositions with the aid of
switching techniques and adaptive algorithms, which do not require
eigen-decompositions, for space-time adaptive processing. A generalized scheme
is proposed to compute low-rank signal decompositions by imposing suitable
constraints on the filtering and by performing iterations between the computed
subspace and the low-rank filter. An alternating optimization strategy based on
recursive least squares algorithms is presented along with switching and
iterations to cost-effectively compute the bases of the decomposition and the
low-rank filter. An application to space-time interference suppression in
DS-CDMA systems is considered. Simulations show that the proposed scheme and
algorithms obtain significant gains in performance over previously reported
low-rank schemes.


title: Improvements to Kramers Turnover Theory

abstract:
  The Kramers turnover problem, that is obtaining a uniform expression for the
rate of escape of a particle over a barrier for any value of the external
friction was solved in the eighties. Two formulations were given, one by
Melnikov and Meshkov (MM) (J. Chem. Phys. 85, 1018 (1986)), which was based on
a perturbation expansion for the motion of the particle in the presence of
friction. The other, by Pollak, Grabert and Haenggi (PGH) (J. Chem. Phys. 91,
4073 (1989)), valid also for memory friction, was based on a perturbation
expansion for the motion along the collective unstable normal mode of the
particle. Both theories did not take into account the temperature dependence of
the average energy loss to the bath. Increasing the bath temperature will
reduce the average energy loss. In this paper, we analyse this effect, using a
novel perturbation theory. We find that within the MM approach, the thermal
energy gained from the bath diverges, the average energy gain becomes infinite,
implying an essential failure of the theory. Within the PGH approach increasing
the bath temperature reduces the average energy loss but only by a finite small
amount, of the order of the inverse of the reduced barrier height. This then
does not seriously affect the theory. Analysis and application for a cubic
potential and Ohmic friction are presented.


title:
Stein's method and a quantitative Lindeberg CLT for the Fourier
  transforms of random vectors

abstract:
  We use a multivariate version of Stein's method to establish a quantitative
Lindeberg CLT for the Fourier transforms of random $N$-vectors. We achieve this
by deducing a specific integral representation for the Hessian matrix of a
solution to the Stein equation with test function $e_t(x) = \exp(- i
\sum_{k=1}^N t_k x_k)$, where $t,x \in \mathbb{R}^N$.


title:
Interference Suppression and Group-Based Power Adjustment via
  Alternating Optimization for DS-CDMA Networks with Multihop Relaying

abstract:
  This work presents joint interference suppression and power allocation
algorithms for DS-CDMA networks with multiple hops and decode-and-forward (DF)
protocols. A scheme for joint allocation of power levels across the relays
subject to group-based power constraints and the design of linear receivers for
interference suppression is proposed. A constrained minimum mean-squared error
(MMSE) design for the receive filters and the power allocation vectors is
devised along with an MMSE channel estimator. In order to solve the proposed
optimization efficiently, a method to form an effective group of users and an
alternating optimization strategy are devised with recursive alternating least
squares (RALS) algorithms for estimating the parameters of the receiver, the
power allocation and the channels. Simulations show that the proposed
algorithms obtain significant gains in capacity and performance over existing
schemes.


title: A van der Waals density functional mapping of attraction in DNA dimers

abstract:
  The dispersion interaction between a pair of parallel DNA double-helix
structures is investigated by means of the van der Waals density functional
(vdW-DF) method. Each double-helix structure consists of an infinite repetition
of one B-DNA coil with 10 base pairs. This parameter-free density functional
theory (DFT) study illustrates the initial step in a proposed vdW-DF
computational strategy for large biomolecular problems. The strategy is to
first perform a survey of interaction geometries, based on the evaluation of
the van der Waals (vdW) attraction, and then limit the evaluation of the
remaining DFT parts (specifically the expensive study of the kinetic-energy
repulsion) to the thus identified interesting geometries. Possibilities for
accelerating this second step is detailed in a separate study. For the B-DNA
dimer, the variation in van der Waals attraction is explored at relatively
short distances (although beyond the region of density overlap) for a 360
degrees rotation. This study highlights the role of the structural motifs, like
the grooves, in enhancing or reducing the vdW interaction strength. We find
that to a first approximation, it is possible to compare the DNA double strand
at large wall-to-wall separations to the cylindrical shape of a carbon nanotube
(which is almost isotropic under rotation). We compare our first-principles
results with the atom-based dispersive interaction predicted by DFT-D2 [J.
Comp. Chem. 27, 1787 (2006)] and find agreement in the asymptotic region.
However, we also find that the differences in the enhancement that occur at
shorter distances reveal characteristic features that result from the fact that
the vdW-DF method is an electron-based (as opposed to atom-based) description.


title: Shape and symmetry of a fluid-supported elastic sheet

abstract:
  A connection between the dynamics of a sine-Gordon chain and a certain static
membrane folding problem was recently found. The one-dimensional membrane
profile is a cross-section of the position-time sine-Gordon amplitude profile.
Here we show that when one system is embedded in a higher-dimensional system in
this way, obvious symmetries in the larger system can lead to nontrivial
symmetries in the embedded system. In particular, a thin buckled membrane on a
fluid substrate has a continuous degeneracy that interpolates between a
symmetric and an antisymmetric fold. We find the Hamiltonian generator of this
symmetry and the corresponding conserved momentum by interpreting the simple
translational symmetries of the sine-Gordon chain in terms of the embedded
coordinates. We discuss possible extensions to other embedded dynamical
systems.


title:
Transfer of Energy, Potential, and Current by Alfv\'en Waves in Solar
  Flares

abstract:
  Alfv\'en waves play three related roles in the impulsive phase of a solar
flare: they transport energy from a generator region to an acceleration region;
they map the cross-field potential (associated with the driven energy release)
from the generator region onto the acceleration region; and within the
acceleration region they damp by setting up a parallel electric field that
accelerates electrons and transfers the wave energy to them. The Alfv\'en waves
may also be regarded as setting up new closed current loops, with field-aligned
currents that close across field lines at boundaries. A model is developed for
large-amplitude Alfv\'en waves that shows how Alfv\'en waves play these roles
in solar flares. A picket-fence structure for the current flow is incorporated
into the model to account for the "number problem" and the energy of the
accelerated electrons.


title: Growth of some transversely homogeneous foliations

abstract:
  For transversely homogeneous foliations on compact manifolds whose global
holonomy group has connected closure, it is shown that either all holonomy
covers of the leaves have polynomial growth with degree bounded by a common
constant, or all holonomy covers of the leaves have exponential growth. This is
an extension of a recent answer given by Breuillard and Gelander to a question
of Carri\`ere. Examples of transversely projective foliations satisfying the
above condition were constructed by Chihi and ben Ramdane.


title:
Ruin Probabilities for Risk Processes with Non-Stationary Arrivals and
  Subexponential Claims

abstract:
  In this paper, we obtain the finite-horizon and infinite-horizon ruin
probability asymptotics for risk processes with claims of subexponential tails
for non-stationary arrival processes that satisfy a large deviation principle.
As a result, the arrival process can be dependent, non-stationary and
non-renewal. We give three examples of non-stationary and non-renewal point
processes: Hawkes process, Cox process with shot noise intensity and
self-correcting point process. We also show some aggregate claims results for
these three examples.


title:
Singular eigenfunctions for the three-dimensional radiative transport
  equation

abstract:
  Case's method obtains solutions to the radiative transport equation as
superpositions of elementary solutions when the specific intensity depends on
one spatial variable. In this paper, we find elementary solutions when the
specific intensity depends on three spatial variables in three-dimensional
space. By using the reference frame whose z-axis lies in the direction of the
wave vector, the angular part of each elementary solution becomes the singular
eigenfunction for the one-dimensional radiative transport equation. Thus Case's
method is generalized.


title:
Variation of "The effect of caching on a model of content and access
  provider revenues in information-centric networks"

abstract:
  This is a variation of the two-sided market model of [10]: Demand D is
concave in \tilde{D} in (16) of [10] So, in (5) of [10] and after Theorem 2,
take the parametric case 0 < a <1. Thus, demand D is both decreasing and
concave in price p, and so the utilities (U=pD) are also concave in price.
Also, herein a simpler illustrative demand-response model is used in Appendix A
and B.


title: Exclusion processes on networks as models for cytoskeletal transport

abstract:
  We present a study of exclusion processes on networks as models for complex
transport phenomena and in particular for active transport of motor proteins
along the cytoskeleton. We argue that active transport processes on networks
spontaneously develop density heterogeneities at various scales. These
heterogeneities can be regulated through a variety of multi-scale factors, such
as the interplay of exclusion interactions, the non-equilibrium nature of the
transport process and the network topology.
  We show how an effective rate approach allows to develop an understanding of
the stationary state of transport processes through complex networks from the
phase diagram of one single segment. For exclusion processes we rationalize
that the stationary state can be classified in three qualitatively different
regimes: a homogeneous phase as well as inhomogeneous network and segment
phases.
  In particular, we present here a study of the stationary state on networks of
three paradigmatic models from non-equilibrium statistical physics: the totally
asymmetric simple exclusion process, the partially asymmetric simple exclusion
process and the totally asymmetric simple exclusion process with Langmuir
kinetics. With these models we can interpolate between equilibrium (due to
bi-directional motion along a network or infinite diffusion) and
out-of-equilibrium active directed motion along a network. The study of these
models sheds further light on the emergence of density heterogeneities in
active phenomena.


title: Symbolic Arithmetic and Integer Factorization

abstract:
  In this paper, we create a systematic and automatic procedure for
transforming the integer factorization problem into the problem of solving a
system of Boolean equations. Surprisingly, the resulting system of Boolean
equations takes on a "life of its own" and becomes a new type of integer, which
we call a generic integer.
  We then proceed to use the newly found algebraic structure of the ring of
generic integers to create two new integer factoring algorithms, called
respectively the Boolean factoring (BF) algorithm, and the multiplicative
Boolean factoring (MBF) algorithm. Although these two algorithms are not
competitive with current classical integer factoring algorithms, it is hoped
that they will become stepping stones to creating much faster and more
competitive algorithms, and perhaps be precursors of a new quantum algorithm
for integer factoring.


title:
Neutron-Proton-Converter Acceleration Mechanism at Subphotospheres of
  Relativistic Outflows

abstract:
  We study a type of particle acceleration that operates via neutron-proton
conversion in inelastic nuclear collisions. This mechanism can be expected for
relativistic shocks at subphotospheres if relativistic outflows contain
neutrons. Using a test-particle approximation, we numerically calculate the
energy spectrum and the efficiency of accelerated particles, and show that a
good energy fraction of the nucleons can be accelerated. This mechanism may
especially be relevant if the shock is radiation-mediated, and it would enhance
the detectability of GeV-TeV neutrinos.


title: The Least Supersymmetric Signals at the LHC

abstract:
  We study the implications at the LHC for the minimal (least) version of the
supersymmetric standard model. In this model supersymmetry is broken by gravity
and extra gauge interactions effects, providing a spectrum similar in several
aspects to that in natural supersymmetric scenarios. Having the first two
generations of sparticles partially decoupled means that any significant signal
can only involve gauginos and the third family of sfermions. In practice, the
signals are dominated by gluino production with subsequent decays into the stop
sector. As we show, for gluino masses below 2300 GeV, a discovery at the LHC is
possible at \sqrt{s}=14 TeV, but will require large integrated luminosities.


title: A high-power 626 nm diode laser system for Beryllium ion trapping

abstract:
  We describe a high-power, frequency-tunable, external cavity diode laser
(ECDL) system near 626 nm useful for laser cooling of trapped $^9$Be$^+$ ions.
A commercial single-mode laser diode with rated power output of 170 mW at 635
nm is cooled to $\approx - 31$ C, and a single longitudinal mode is selected
via the Littrow configuration. In our setup, involving multiple stages of
thermoelectric cooling, we are able to obtain $\approx$130 mW near 626 nm,
sufficient for efficient frequency doubling to the required Doppler cooling
wavelengths near 313 nm in ionized Beryllium. In order to improve nonlinear
frequency conversion efficiency, we achieve larger useful power via injection
locking of a slave laser. In this way the entirety of the slave output power is
available for frequency doubling, while analysis may be performed on the master
output. We believe that this simple laser system addresses a key need in the
ion trapping community and dramatically reduces the cost and complexity
associated with Beryllium ion trapping experiments.

categories: physics.optics physics.atom-ph physics.ins-det quant-ph


title: On the foundations of partially quenched chiral perturbation theory

abstract:
  It has been widely assumed that partially quenched chiral perturbation theory
is the correct low-energy effective theory for partially quenched QCD. Here we
present arguments supporting this assumption. First, we show that, for
partially quenched QCD with staggered quarks, a transfer matrix can be
constructed. This transfer matrix is not Hermitian, but it is bounded, and it
can be used to construct correlation functions in the usual way. Combining
these observations with an extension of the Vafa--Witten theorem to the
partially quenched theory allows us to argue that the partially quenched theory
satisfies the cluster property. By extending Leutwyler's analysis of the
unquenched case to the partially quenched theory, we then conclude that the
existence and properties of the transfer matrix as well as clustering are
sufficient for partially quenched chiral perturbation theory to be the correct
low-energy theory for partially quenched QCD.


title: Radio polarization observations of large supernova remnants at 6cm

abstract:
  We have observed 79 supernova remnants (SNRs) with the Urumqi 25m telescope
at 6cm during the Sino-German 6cm polarization survey of the Galactic plane. We
measured flux densities of SNRs at 6cm, some of which are the first ever
measured or the measurements at the highest frequency, so that we can determine
or improve spectra of SNRs. Our observations have ruled out spectral breaks or
spectral flattening that were suggested for a few SNRs, and confirmed the
spectral break of S147. By combining our 6cm maps with 11cm and 21cm maps from
the Effelsberg 100 m telescope, we calculated the spectral index maps of
several large SNRs. For many remnants we obtained for the first time
polarization images, which show the intrinsic magnetic field structures at 6cm.
We disapproved three objects as being SNRs, OA184, G192.8-1.1 and G16.8-1.1,
which show a thermal spectrum and no polarization. We have discovered two large
supernova remnants, G178.2-4.2 and G25.1-2.3., in the survey maps.


title: A generalization of Schmidt number for multipartite states

abstract:
  The Schmidt number is of crucial importance in characterizing the bipartite
pure states. We explore and propose here a generalization of Schmidt number for
states in multipartite systems. It is shown to be entanglement monotonic and
valid for both pure and mixed states. In addition, the corresponding
generalization of multipartite Schmidt coefficients is introduced. Our approach
is applicable for systems with arbitrary number of parties and for arbitrary
dimensions.


title: Distinct Degrees and Their Distribution in Complex Networks

abstract:
  We investigate a variety of statistical properties associated with the number
of distinct degrees that exist in a typical network for various classes of
networks. For a single realization of a network with N nodes that is drawn from
an ensemble in which the number of nodes of degree k has an algebraic tail, N_k
~ N/k^nu for k>>1, the number of distinct degrees grows as N^{1/nu}. Such an
algebraic growth is also observed in scientific citation data. We also
determine the N dependence of statistical quantities associated with the
sparse, large-k range of the degree distribution, such as the location of the
first hole (where N_k=0), the last doublet (two consecutive occupied degrees),
triplet, dimer (N_k=2), trimer, etc.


title: Quantum Corrections to Thermopower and Conductivity in Graphene

abstract:
  The quantum corrections to the conductivity and the thermopower in monolayer
graphene are studied. We use the recursive Green's function method to calculate
numerically the conductivity and the thermopower of graphene. We then analyze
these weak localization corrections by fitting with the analytical theory as
function of the impurity parameters and the gate potential. As a result of the
quantum corrections to the thermopower, we find large magnetothermopower which
is shown to provide a very sensitive measure of the size and strength of the
impurities. We compare these analytical and numerical results with existing
experimental measurements of magnetoconductance of single layer graphene and
find that the average size and strength of the impurities in these samples can
thereby be determined. We suggest favorable parameter ranges for future
measurements of the magnetothermopower.


title: IDV Observations & Study of the Quasar 0917+624

abstract:
  We carried out intra-day variability (IDV) observations from August 2005 to
January 2010 with the Urumqi 25m radio telescope for a dozen IDV sources
including the quasar 0917+624. This target exhibited pronounced
centimeter-band, intra-day variability during the 1980s--1990s, but its strong
IDV phase ceased in 2000. The source showed no IDV in the majority of the
Urumqi observing sessions, although weak IDV activity was detected in some.
Multifrequency UMRAO data for 0917+624 show that the spectral index is steeper
during the weak and non-IDV phases than during the strong IDV phase, supporting
the idea that the size of the scintillating component may be enlarged in the
weak/non IDV phases.


title: A new approach to hom-Lie bialgebras

abstract:
  In this paper, we introduce a new definition of a hom-Lie bialgebra, which is
equivalent to a Manin triple of hom-Lie algebras. We also introduce a notion of
an $\mathcal O$-operator and then construct solutions of the classical
hom-Yang-Baxter equation in terms of $\mathcal O$-operators and
hom-left-symmetric algebras.


title: A search for binary black hole candidates from the VLBI images of AGNs

abstract:
  We have searched the core-jets pairs in the VLBI scales ($<$1 kpc), from
several VLBI catalogues, and find out 6 possible binary black hole (BBH)
candidates. We present the search result and analyze the candidates
preliminarily, and further study with multi-band VLBI observation and optical
line investigation would be carried out in the future.


title: Magnetic Fields and the Formation of Cores and Disks

abstract:
  We review recent results of non-ideal magnetohydrodynamic models for the
fragmentation of molecular clouds and the collapse of cloud cores to form
protostar-disk systems. Thin-disk models can elucidate many aspects of the
physical problem and allow the calculation of large dynamic range of time and
length scales.


title:
Simulation of nanostructure-based high-efficiency solar cells:
  challenges, existing approaches and future directions

abstract:
  Many advanced concepts for high-efficiency photovoltaic devices exploit the
peculiar optoelectronic properties of semiconductor nanostructures such as
quantum wells, wires and dots. While the optics of such devices is only
modestly affected due to the small size of the structures, the optical
transitions and electronic transport can strongly deviate from the simple bulk
picture known from conventional solar cell devices. This review article
discusses the challenges for an adequate theoretical description of the
photovoltaic device operation arising from the introduction of nanostructure
absorber and/or conductor components and gives an overview of existing device
simulation approaches.


title: Nucleon resonance production in $K^+N$ interactions

abstract:
  In this work, we discuss the possibility of studying nucleon resonances in
the $K^+N$ interactions. Based on our model calculations, it is found that the
hyperon exchange plays an important role for the excitation of nucleon
resonances in the $K^+N$ interactions. Therefore, the studies on nucleon
resonance production in the $K^+N$ interactions can offer us valuable
information about the couplings of nucleon resonances with strange particles.
By selecting suitable decay channels of nucleon resonances, some reactions are
also suitable to look for missing resonances.


title:
Polymer Stable Magnesium Nanocomposites Prepared by Laser Ablation for
  Efficient Hydrogen Storage

abstract:
  Hydrogen is a promising alternative energy carrier that can potentially
facilitate the transition from fossil fuels to sources of clean energy because
of its prominent advantages such as high energy density (142 MJ per kg), great
variety of potential sources (for example water, biomass, organic matter), and
low environmental impact (water is the sole combustion product). However, due
to its light weight, the efficient storage of hydrogen is still an issue
investigated intensely. Various solid media have been considered in that
respect among which magnesium hydride stands out as a candidate offering
distinct advantages. Recent theoretical work indicates that MgH2 becomes less
thermodynamically stable as particle diameter decreases below 2 nm. Our DFT
(density functional theory) modeling studies have shown that the smallest
enthalpy change, corresponding to 2 unit-cell thickness (1.6 {\AA} Mg/3.0{\AA}
MgH2) of the film, is 57.7 kJ/molMg. This enthalpy change is over 10 kJ per
molMg smaller than that of the bulk. It is important to note that the range of
enthalpy change for systems that are suitable for mobile storage applications
is 15 to 24 kJ permolH at 298 K. The important key for the development of
air/stable Mg/nanocrystals is the use of PMMA (polymethylmethacrylate) as an
encapsulation agent. In our work we use laser ablation, a non-electrochemical
method, for producing well dispersed nanoparticles without the presence of any
long range aggregation. The observed improved hydrogenation characteristics of
the polymer/stable Mg-nanoparticles are associated to the preparation procedure
and in any case the polymer laser ablation is a new approach for the production
of air/protected and inexpensive Mg/nanoparticles.


title: Initial Value Problem in General Relativity

abstract:
  This article, written to appear as a chapter in "The Springer Handbook of
Spacetime", is a review of the initial value problem for Einstein's
gravitational field theory in general relativity. Designed to be accessible to
graduate students who have taken a first course in general relativity, the
article first discusses how to reformulate the spacetime fields and spacetime
covariant field equations of Einstein's theory in terms of fields and field
equations compatible with a 3+1 foliation of spacetime with spacelike
hypersurfaces. It proceeds to discuss the arguments which show that the initial
value problem for Einstein's theory is well-posed, in the sense that for any
given set of initial data satisfying the Einstein constraint equations, there
is a (maximal) spacetime solution of the full set of Einstein equations,
compatible with the given set of data. The article then describes how to
generate initial data sets which satisfy the Einstein constraints, using the
conformal (and conformal thin sandwich) method, and using gluing techniques.
The article concludes with comments regarding stability and long term behavior
of solutions of Einstein's equations generated via the initial value problem.


title: Quintessence: A Review

abstract:
  Quintessence is a canonical scalar field introduced to explain the late-time
cosmic acceleration. The cosmological dynamics of quintessence is reviewed,
paying particular attention to the evolution of the dark energy equation of
state w. For the field potentials having tracking and thawing properties, the
evolution of w can be known analytically in terms of a few model parameters.
Using the analytic expression of w, we constrain quintessence models from the
observations of supernovae type Ia, cosmic microwave background, and baryon
acoustic oscillations. The tracking freezing models are hardly distinguishable
from the LCDM model, whereas in thawing models the today's field equation of
state is constrained to be w_0<-0.7 (95 % CL). We also derive an analytic
formula for the growth rate of matter density perturbations in dynamical dark
energy models, which allows a possibility to put further bounds on w from the
measurement of redshift-space distortions in the galaxy power spectrum. Finally
we review particle physics models of quintessence- such as those motivated by
supersymmetric theories. The field potentials of thawing models based on a
pseudo-Nambu-Goldstone boson or on extended supergravity theories have a nice
property that a tiny mass of quintessence can be protected against radiative
corrections.


title:
Low Complexity MIMO Detection based on Belief Propagation over Pair-wise
  Graphs

abstract:
  This paper considers belief propagation algorithm over pair-wise graphical
models to develop low complexity, iterative multiple-input multiple-output
(MIMO) detectors. The pair-wise graphical model is a bipartite graph where a
pair of variable nodes are related by an observation node represented by the
bivariate Gaussian function obtained by marginalizing the posterior joint
probability density under the Gaussian input assumption. Specifically, we
consider two types of pair-wise models, the fully connected and ring-type. The
pair-wise graphs are sparse, compared to the conventional graphical model in
[18], insofar as the number of edges connected to an observation node (edge
degree) is only two. Consequently the computations are much easier than those
of maximum likelihood (ML) detection, which are similar to the belief
propagation (BP) that is run over the fully connected bipartite graph. The link
level performance for non-Gaussian input is evaluated via simulations, and the
results show the validity of the proposed algorithms. We also customize the
algorithm with Gaussian input assumption to obtain the Gaussian BP run over the
two pair-wise graphical models and, for the ring-type, we prove its convergence
in mean to the linear minimum mean square error (MMSE) estimates. Since the
maximum a posterior (MAP) estimator for Gaussian input is equivalent to the
linear MMSE estimator, it shows the optimality, in mean, of the scheme for
Gaussian input.


title: A new metric for routing in military wireless network

abstract:
  Wireless Ad-hoc network is generally employed in military and emergencies due
to its flexibility and easy-to-use. It's suitable for military wireless network
that has the characteristics of mobility and works effectively under severe
environment and electromagnetic interfering conditions. However, military
network cannot benefit from existing routing protocol directly; there exists
quite many features which are only typical for military network. This paper
presents a new metric for routing, which is employed in A* algorithm. The goal
of the metric is to choose a route of less distance and less transmission delay
between a source and a destination. Our metric is a function of the distance
between the ends and the bandwidth over the link. Moreover, we take frequency
selection into account since a node can work on multi-frequencies. This paper
proposed the new metric, and experimented it based on A* algorithm. The
simulation results show that this metric can find the optimal route which has
less transmission delay compared to the shortest path routing.


title: Remarks on a constrained optimization problem for the Ginibre ensemble

abstract:
  We study the limiting distribution of the eigenvalues of the Ginibre ensemble
conditioned on the event that a certain proportion lie in a given region of the
complex plane. Using an equivalent formulation as an obstacle problem, we
describe the optimal distribution and some of its monotonicity properties.


title:
Chiral charge order in 1$T$-TiSe$_2$: importance of lattice degrees of
  freedom

abstract:
  We address the question of the origin of the recently discovered chiral
property of the charge-density-wave phase in 1$T$-TiSe$_2$ which so far lacks a
microscopic understanding. We argue that the lattice degrees of freedom seems
to be crucial for this novel phenomenon. We motivate a theoretical model that
takes into account one valence and three conduction bands, a strongly screened
Coulomb interaction between the electrons, as well as the coupling of the
electrons to a transverse optical phonon mode. The Falicov-Kimball model
extended in this way possesses a charge-density-wave state at low temperatures,
which is accompanied by a periodic lattice distortion. The charge ordering is
driven by a lattice deformation and electron-hole pairing (excitonic)
instability in combination. We show that both electron-phonon interaction and
phonon-phonon interaction must be taken into account at least up to quartic
order in the lattice displacement to achieve a stable chiral charge order. The
chiral property is exhibited in the ionic displacements. Furthermore, we
provide the ground-state phase diagram of the model and give an estimate of the
electron-electron and electron-phonon interaction constants for 1$T$-TiSe$_2$.


title:
A Performance Comparison of Different Graphics Processing Units Running
  Direct N-Body Simulations

abstract:
  Hybrid computational architectures based on the joint power of Central
Processing Units and Graphic Processing Units (GPUs) are becoming popular and
powerful hardware tools for a wide range of simulations in biology, chemistry,
engineering, physics, etc..
  In this paper we present a comparison of performance of various GPUs
available on market when applied to the numerical integration of the classic,
gravitational, N-body problem. To do this, we developed an OpenCL version of
the parallel code (HiGPUs) to use for these tests, because this version is the
only apt to work on GPUs of different makes.
  The main general result is that we confirm the reliability, speed and
cheapness of GPUs when applied to the examined kind of problems (i.e. when the
forces to evaluate are dependent on the mutual distances, as it happens in
gravitational physics and molecular dynamics). More specifically, we find that
also the cheap GPUs built to be employed just for gaming applications are very
performant in terms of computing speed also in scientific applications and,
although with some limitations in central memory and in bandwidth, can be a
good choice to implement a machine for scientific use at a very good
performance to cost ratio.


title:
Deep and Wide Photometry of Two Open Clusters NGC 1245 and NGC 2506:
  Dynamical Evolution and Halo

abstract:
  We studied the structure of two old open clusters, NGC 1245 and NGC 2506,
from a wide and deep VI photometry data acquired using the CFH12K CCD camera at
CFHT. We devised a new method for assigning cluster membership probability to
individual stars using both spatial positions and positions in the
colour-magnitude diagram. From analyses of the luminosity functions at several
cluster-centric radii and the radial surface density profiles derived from
stars with different luminosity ranges, we found that the two clusters are
dynamically relaxed to drive significant mass segregation and evaporation of
some fraction of low-mass stars. There seems to be a signature of tidal tail in
NGC 1245 but the signal is too low to be confirmed.


title:
Evidence for a Cool Disk and Inhomogeneous Coronae from Wide-band
  Temporal Spectroscopy of Cygnus X-1 with Suzaku

abstract:
  Unified X-ray spectral and timing studies of Cygnus X-1 in the low/hard and
hard intermediate state were conducted in a model-independent manner, using
broadband Suzaku data acquired on 25 occasions from 2005 to 2009 with a total
exposure of ~ 450 ks. The unabsorbed 0.1--500 keV source luminosity changed
over 0.8--2.8% of the Eddington limit for 14.8 solar masses. Variations on
short (1--2 seconds) and long (days to months) time scales require at least
three separate components: a constant component localized below ~2 keV, a broad
soft one dominating in the 2--10 keV range, and a hard one mostly seen in
10--300 keV range. In view of the truncated disk/hot inner flow picture, these
are respectively interpreted as emission from the truncated cool disk, a soft
Compton component, and a hard Compton component. Long-term spectral evolution
can be produced by the constant disk increasing in temperature and luminosity
as the truncation radius decreases. The soft Compton component likewise
increases, but the hard Compton does not, so that the spectrum in the hard
intermediate state is dominated by the soft Compton component; on the other
hand, the hard Compton component dominates the spectrum in the dim low/hard
state, probably associated with a variable soft emission providing seed photons
for the Comptonization.


title: One-Bit Quantization Design and Adaptive Methods for Compressed Sensing

abstract:
  There have been a number of studies on sparse signal recovery from one-bit
quantized measurements. Nevertheless, little attention has been paid to the
choice of the quantization thresholds and its impact on the signal recovery
performance. This paper examines the problem of one-bit quantizer design for
sparse signal recovery. Our analysis shows that the magnitude ambiguity that
ever plagues conventional one-bit compressed sensing methods can be resolved,
and an arbitrarily small reconstruction error can be achieved by setting the
quantization thresholds close enough to the original data samples without being
quantized. Note that unquantized data samples are unaccessible in practice. To
overcome this difficulty, we propose an adaptive quantization method that
adaptively adjusts the quantization thresholds in a way such that the
thresholds converges to the optimal thresholds. Numerical results are
illustrated to collaborate our theoretical results and the effectiveness of the
proposed algorithm.


title:
Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft
  State Observed with Suzaku

abstract:
  We present observations of a transient He-like Fe K alpha absorption line in
Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near
superior conjunction during the high/soft state, which enable us to map the
full evolution from the start and the end of the episodic accretion phenomena
or dips for the first time. We model the X-ray spectra during the event and
trace their evolution. The absorption line is rather weak in the first half of
the observation, but instantly deepens for ~10 ks, and weakens thereafter. The
overall change in equivalent width is a factor of ~3, peaking at an orbital
phase of ~0.08. This is evidence that the companion stellar wind feeding the
black hole is clumpy. By analyzing the line with a Voigt profile, it is found
to be consistent with a slightly redshifted Fe XXV transition, or possibly a
mixture of several species less ionized than Fe XXV. The data may be explained
by a clump located at a distance of ~10^(10-12) cm with a density of
~10^((-13)-(-11)) g cm^-3, which accretes onto and/or transits the
line-of-sight to the black hole, causing an instant decrease in the observed
degree of the ionization and/or an increase in density of the accreting matter.
Continued monitoring for individual events with future X-ray calorimeter
missions such as ASTRO-H and AXSIO will allow us to map out the accretion
environment in detail and how it changes between the various accretion states.


title: Hofer metric from the contact point of view

abstract:
  Given a manifold $M$ endowed with a contact 1-form $\alpha$, a bi-invariant
pseudo-metric $\varrho_\alpha$ is introduced on $Cont(M,\alpha)$, the compactly
supported identity component of the group of all strict contactomorphisms of
$(M,\alpha)$. For $M$ open $\varrho_\alpha$ is a metric.


title: Facial transformations of ancient portraits: the face of Caesar

abstract:
  Some software solutions used to obtain the facial transformations can help
investigating the artistic metamorphosis of the ancient portraits of the same
person. An analysis with a freely available software of portraitures of Julius
Caesar is proposed, showing his several "morphs". The software helps enhancing
the mood the artist added to a portrait.


title: Partial wave analysis of $\psi(2S) \to p \bar{p}\eta$

abstract:
  Using a sample of $1.06 \times 10^{8}$ $\psi(2S)$ events collected with the
BESIII detector at BEPCII, the decay $\psi(2S) \to p \bar{p}\eta$ is studied. A
partial wave analysis determines that the intermediate state N(1535) with a
mass of $1524\pm5^{+10}_{-4}$ MeV/$c^2$ and a width of $130^{+27+57}_{-24-10}$
MeV/$c^2$ is dominant in the decay; the product branching fraction is
determined to be $B(\psi(2S) \to N(1535)\bar{p})\times B(N(1535)\to p\eta)+c.c.
= (5.2\pm0.3^{+3.2}_{-1.2})\times 10^{-5}$. Furthermore, the branching fraction
of $\psi(2S) \to \eta p \bar{p}$ is measured to be $(6.4\pm0.2\pm0.6)\times
10^{-5}$.


title: On finite $p$-groups with abelian automorphism group

abstract:
  We construct, for the first time, various types of specific non-special
finite $p$-groups having abelian automorphism group. More specifically, we
construct groups $G$ with abelian automorphism group such that $\gamma_2(G) <
\mathrm{Z}(G) < \Phi(G)$, where $\gamma_2(G)$, $\mathrm{Z}(G)$ and $\Phi(G)$
denote the commutator subgroup, the center and the Frattini subgroup of $G$
respectively. For a finite $p$-group $G$ with elementary abelian automorphism
group, we show that at least one of the following two conditions holds true:
(i) $\mathrm{Z}(G) = \Phi(G)$ is elementary abelian; (ii) $\gamma_2(G) =
\Phi(G)$ is elementary abelian, where $p$ is an odd prime. We construct
examples to show the existence of groups $G$ with elementary abelian
automorphism group for which exactly one of the above two conditions holds
true.


title: Centered weighted conditional type operators

abstract:
  In this paper, we give some necessary and sufficient conditions for weighted
conditional expectation type operators on L2 to be centered. Also, we
investigate the relation between normal and centered weighted con- ditional
type operators. Finally we give some applications.


title: Neutron capture by 15N nucleus at astrophysical energies

abstract:
  Within the potential cluster model with the forbidden states and an orbital
states classification according to the Young diagrams the possibility of
description of experimental data for the total cross-sections of radiative
n15N-capture at energies from 25 to 370 keV was considered. It was shown that
only on basis of the E1-transitions from the different states of
n15N-scattering to the ground state of 16N nucleus in n15N-channel it is well
succeed to explain the value of the total cross-sections in the considered
energy range and to prognosticate its behavior at energy E 1 eV. These
cross-sections at energies E 10 keV are approximated by the simple analytical
form.


title: Rapid Spectral Changes of Cygnus X-1 in the Low/Hard State with Suzaku

abstract:
  Rapid spectral changes in the hard X-ray on a time scale down to ~0.1 s are
studied by applying "shot analysis" technique to the Suzaku observations of the
black hole binary Cygnus X-1, performed on 2008 April 18 during the low/hard
state. We successfully obtained the shot profiles covering 10--200 keV with the
Suzaku HXD-PIN and HXD-GSO detector. It is notable that the 100-200 keV shot
profile is acquired for the first time owing to the HXD-GSO detector. The
intensity changes in a time-symmetric way, though the hardness does in a
time-asymmetric way. When the shot-phase-resolved spectra are quantified with
the Compton model, the Compton y-parameter and the electron temperature are
found to decrease gradually through the rising phase of the shot, while the
optical depth appears to increase. All the parameters return to their
time-averaged values immediately within 0.1 s past the shot peak. We have not
only confirmed this feature previously found in energies below ~60 keV, but
also found that the spectral change is more prominent in energies above ~100
keV, implying the existence of some instant mechanism for direct entropy
production. We discuss possible interpretations on the rapid spectral changes
in the hard X-ray band.


title: Constructing Low Star Discrepancy Point Sets with Genetic Algorithms

abstract:
  Geometric discrepancies are standard measures to quantify the irregularity of
distributions. They are an important notion in numerical integration. One of
the most important discrepancy notions is the so-called \emph{star
discrepancy}. Roughly speaking, a point set of low star discrepancy value
allows for a small approximation error in quasi-Monte Carlo integration. It is
thus the most studied discrepancy notion.
  In this work we present a new algorithm to compute point sets of low star
discrepancy. The two components of the algorithm (for the optimization and the
evaluation, respectively) are based on evolutionary principles. Our algorithm
clearly outperforms existing approaches. To the best of our knowledge, it is
also the first algorithm which can be adapted easily to optimize inverse star
discrepancies.


title: Limited communication capacity unveils strategies for human interaction

abstract:
  Social connectivity is the key process that characterizes the structural
properties of social networks and in turn processes such as navigation,
influence or information diffusion. Since time, attention and cognition are
inelastic resources, humans should have a predefined strategy to manage their
social interactions over time. However, the limited observational length of
existing human interaction datasets, together with the bursty nature of dyadic
communications have hampered the observation of tie dynamics in social
networks. Here we develop a method for the detection of tie
activation/deactivation, and apply it to a large longitudinal, cross-sectional
communication dataset ($\approx$ 19 months, $\approx$ 20 million people).
Contrary to the perception of ever-growing connectivity, we observe that
individuals exhibit a finite communication capacity, which limits the number of
ties they can maintain active. In particular we find that men have an overall
higher communication capacity than women and that this capacity decreases
gradually for both sexes over the lifespan of individuals (16-70 years). We are
then able to separate communication capacity from communication activity,
revealing a diverse range of tie activation patterns, from stable to
exploratory. We find that, in simulation, individuals exhibiting exploratory
strategies display longer time to receive information spreading in the network
those individuals with stable strategies. Our principled method to determine
the communication capacity of an individual allows us to quantify how
strategies for human interaction shape the dynamical evolution of social
networks.


title:
Observations that can unravel the coherent radio emission mechanism in
  pulsars

abstract:
  Searching for the physical mechanism that can excite the coherent radio
emission in pulsars is still an enigmatic problem. A wealth of high quality
observations exist, which over the years have been instrumental in putting
stringent constraints to pulsar emission models. In this article we will
discuss the observational results that strongly suggests that pulsar radio
emission is excited by coherent curvature radiation. We will also mention
issues that remain to be resolved.


title:
Auction-based Resource Allocation in MillimeterWave Wireless Access
  Networks

abstract:
  The resource allocation problem of optimal assignment of the clients to the
available access points in 60 GHz millimeterWave wireless access networks is
investigated. The problem is posed as a multiassignment optimisation problem.
The proposed solution method converts the initial problem to a minimum cost
flow problem and allows to design an efficient algorithm by a combination of
auction algorithms. The solution algorithm exploits the network optimization
structure of the problem, and thus is much more powerful than computationally
intensive general-purpose solvers. Theoretical and numerical results evince
numerous properties, such as optimality, convergence, and scalability in
comparison to existing approaches.


title: Deterministic vs Non-deterministic Graph Property Testing

abstract:
  A graph property P is said to be testable if one can check if a graph is
close or far from satisfying P using few random local inspections. Property P
is said to be non-deterministically testable if one can supply a "certificate"
to the fact that a graph satisfies P so that once the certificate is given its
correctness can be tested. The notion of non-deterministic testing of graph
properties was recently introduced by Lovasz and Vesztergombi, who proved that
(somewhat surprisingly) a graph property is testable if and only if it is
non-deterministically testable. Their proof used graph limits, and so it did
not supply any explicit bounds. They thus asked if one can obtain a proof of
their result which will supply such bounds. We answer their question positively
by proving their result using Szemeredi's regularity lemma.
  An interesting aspect of our proof is that it highlights the fact that the
regularity lemma can be interpreted as saying that all graphs can be
approximated by finitely many "template" graphs.


title:
Phenomenological model of anomalous magnon softening and damping in
  half-metallic manganites

abstract:
  To describe anomalous zone-boundary softening and damping of magnons in
manganites we present a phenomenological two-fluid model containing
ferromagnetic Fermi-liquid and non-Fermi-liquid components. The Fermi-liquid
component accounts for softening of zone-boundary magnons and for the Landau
damping of magnons in the Stoner continuum arising at low frequencies due to
zero-point effects. Coupling of the Fermi-liquid and non-Fermi-liquid fluids
yields conventional long wavelength magnons damped due to their coupling with
longitudinal spin fluctuations.


title: A Multi-Dimensional Block-Circulant Perfect Array Construction

abstract:
  We present a $N$-dimensional generalization of the two-dimensional
block-circulant perfect array construction by \cite{Blake2013}. As in
\cite{Blake2013}, the families of $N$-dimensional arrays possess pairwise
\textit{good} zero correlation zone (ZCZ) cross-correlation. Both constructions
use a perfect autocorrelation sequence with the array orthogonality property
(AOP).


title:
Origins and evolutionary genomics of the novel 2013 avian-origin H7N9
  influenza A virus in China: Early findings

abstract:
  In March and early April 2013, a new avian-origin influenza A (H7N9) virus
(A-OIV) emerged in the eastern China. During the first week of April, the 18
infection cases have been confirmed and 6 people have died since March. This
virus has caused global concern as a potential pandemic threat. Here we use
evolutionary analysis to reconstruct the origins and early development of the
A-OIV viruses. We found that A-OIV was derived from a reassortment of three
avian flu virus strains, and substantial mutations have been detected. Our
results highlight the need for systematic surveillance of influenza in birds,
and provide evidence that the mixing of new genetic elements in avian can
result in the emergence of viruses with pandemic potential in humans.


title: On growing connected beta-skeletons

abstract:
  A $\beta$-skeleton, $\beta \geq 1$, is a planar proximity undirected graph of
an Euclidean points set, where nodes are connected by an edge if their
lune-based neighbourhood contains no other points of the given set. Parameter
$\beta$ determines the size and shape of the lune-based neighbourhood. A
$\beta$-skeleton of a random planar set is usually a disconnected graph for
$\beta>2$. With the increase of $\beta$, the number of edges in the
$\beta$-skeleton of a random graph decreases. We show how to grow stable
$\beta$-skeletons, which are connected for any given value of $\beta$ and
characterise morphological transformations of the skeletons governed by $\beta$
and a degree of approximation. We speculate how the results obtained can be
applied in biology and chemistry.


title: A fifth-order bi-Hamiltonian system

abstract:
  In this work, we introduce a new two component fifth-order bi-Hamiltonian
sys- tem admitting the scalar Kupershmidt equation as a reduction.


title: Universal conductivity of graphene in the ultra-relativistic regime

abstract:
  We calculate the optical (cutoff >> frequency >> temperature) conductivity in
clean graphene in the ultimate low-energy regime, when retardation effects of
the electromagnetic interaction become important and when the full Lorentz
symmetry emerges. In contrast to what happens with the short range or with the
Coulomb long-range instantaneous interactions, the optical conductivity is now
no longer equal to its non interacting value, but acquires universal
corrections in powers of the fine structure constant. The coefficient of the
first order correction is computed, and found to be of order one. We also
present the result for the conductivity in the large-N limit, with $N$ as the
number of Dirac fermions species, to the order $1/N^2$.


title: Global solution to a cubic nonlinear Dirac equation in 1+1 dimensions

abstract:
  This paper studies a class of nonlinear Dirac equations with cubic terms in
$R^{1+1}$, which include the equations for the massive Thirring model and the
massive Gross-Neveu model. Under the assumptions that the initial data has
small charge, the global existence of the solution in $H^1$ are proved. The
proof is given by introducing some Bony functional to get the uniform estimates
on the nonlinear terms and the uniform bounds on the local smooth solution,
which enable us to extend the local solution globally in time. Then
$L^2$-stability estimates for these solutions are also established by a
Lyapunov functional and the global existence of weak solution in $L^2$ is
obtained.