title:
On the interactions of the high energy photoelectrons with the fullerene
  shell

abstract:
  The probability that photoionization of the caged atom in an endohedral
system is accompanied by excitation of the fullerene shell is shown to be close
to unity in broad intervals of the photoelectron energies. The result is
obtained by summation of the perturbative series for the interaction between
the photoelectron and the fullerene shell. This result means that the
interaction between the photoelectron ejected from the cage atom and the
fullerene shell cannot be described by a static potential, since inelastic
processes become decisively important.


title:
Grain boundary segregation of C, N and O in hcp titanium from
  first-principles

abstract:
  It is believed that grain boundary segregation of light interstitials can
serve as possible mechanism of thermal stability in commercially pure
nanostructured titanium alloys. In this paper, using first-principles
calculations, we show that independent segregation of C, N and O atoms at
\Sigma 7 high angle grain boundary in \alpha-Ti is energetically unfavourable.
The presence of interstitial elements near and at the grain boundary interface
results in the increase of the grain boundary width and specific formation
energy.


title:
Polycyclic aromatic hydrocarbons in spatially resolved extragalactic
  star forming complexes

abstract:
  The abundance of polycyclic aromatic hydrocarbons (PAHs) in low- and
high-metallicity galaxies has been widely discussed since the time when
detailed infrared data for extragalactic objects were first obtained. On the
scales of entire galaxies, a smaller PAH abundance in lower-metallicity
galaxies is often observed. We study this relationship for star-forming regions
in nearby galaxies, for a sample containing more than 200 HII complexes, using
spatially-resolved observations from the Herschel Space Observatory and Spitzer
Space Telescope. We use a model for the dust emission to estimate the physical
parameters (PAH abundance, metallicity, ultraviolet radiation field, etc.) of
these complexes. The same correlation of PAH abundance with metallicity, as
seen for entire galaxies, is apparently preserved at smaller scales, at least
when the Kobulnicky & Kewley metallicity calibration is used. We discuss
possible reasons for this correlation, noting that traces of less-effective PAH
formation in low-metallicity AGB stars should be smeared out by radial mixing
in galactic disks. Effective destruction by the harder and more intensive
ultraviolet field in low-metallicity environments is qualitatively consistent
with our data, as the ultraviolet field intensity, derived from the infrared
photometry, is indeed smaller in HII complexes with lower metallicity.


title: Multielectron processes in endohedral atoms at high energies

abstract:
  We analyze the role of shake-off and of the final state interactions in
inelastic processes in the fullerene shell which follow ionization of the caged
atom. We demonstrate that in the broad interval of the photon energies the
process is dominated by the final state interactions. Its contribution is
calculated in a model-independent way. In the large energy intervals the cross
section of the process is close to that of photoionization of isolated atom.


title: Securing coherence rephasing with a pair of adiabatic rapid passages

abstract:
  Coherence rephasing is an essential step in quantum storage protocols that
use echo-based strategies. We present a thorough analysis on how two adiabatic
rapid passages (ARP) are able to rephase atomic coherences in an
inhomogeneously broadened ensemble. We consider both the cases of optical and
spin coherences, rephased by optical or radio-frequency (rf) ARPs,
respectively. We show how a rephasing sequence consisting of two ARPs in a
double-echo scheme is equivalent to the identity operator (any state can be
recovered), as long as certain conditions are fulfilled. Our mathematical
treatment of the ARPs leads to a very simple geometrical interpretation within
the Bloch sphere that permits a visual comprehension of the rephasing process.
We also identify the conditions that ensure the rephasing, finding that the
phase of the optical or rf ARP fields plays a key role in the capability of the
sequence to preserve the phase of the superposition state. This settles a
difference between optical and rf ARPs, since field phase control is not
readily guaranteed in the former case. We also provide a quantitative
comparison between $\pi$-pulse and ARP rephasing efficiencies, showing the
superiority of the latter. We experimentally verify the conclusions of our
analysis through rf ARP rephasing sequencies performed on the rare-earth
ion-doped crystal Tm$^{3+}$:YAG, of interest in quantum memories.


title:
Joint Physical Network Coding and LDPC decoding for Two Way Wireless
  Relaying

abstract:
  In this paper, we investigate the joint design of channel and network coding
in bi-directional relaying systems and propose a combined low complexity
physical network coding and LDPC decoding scheme. For the same LDPC codes
employed at both source nodes, we show that the relay can decodes the network
coded codewords from the superimposed signal received from the BPSK-modulated
multiple-access channel. Simulation results shown that this novel joint
physical network coding and LDPC decoding method outperforms the existing MMSE
network coding and LDPC decoding method over AWGN and complex MAC channel.


title: A.E.C. with not too many models

abstract:
  Consider an a.e.c. (abstract elementary class), that is, a class K of models
with a partial order refining inclusion (submodel) which satisfy the most basic
properties of an elementary class. Our test question is trying to show that the
function dot I (lambda, K), counting the number of models in K of cardinality
lambda up to isomorphism, is "nice", not chaotic, even without assuming it is
sometimes 1, i.e. categorical in some lambda's. We prove here that for some
closed unbounded class C of cardinals we have (a), (b) or (c) where (a) for
every lambda in C of cofinality aleph_0, dot I (lambda, K) greater than or
equal to lambda, (b) for every lambda in C of cofinality aleph_0 and M belongs
to K_lambda, for every cardinal kappa greater than or equal to lambda there is
N_kappa of cardinality kappa extending M (in the sense of our a.e.c.), (c)
mathfrak k is bounded; that is, dot I (lambda, K) = 0 for every lambda large
enough (equivalently lambda greater than or equal to beth_{delta_*} where
delta_* = (2^{LST(mathfrak k)})^+).
  Recall that an important difference of non-elementary classes from the
elementary case is the possibility of having models in K, even of large
cardinality, which are maximal, or just failing clause (b).


title:
Ray trajectories, binomial of a new type, and the binary system; on
  binomial distribution of the second (nonlinear) type for big binomial power

abstract:
  The paper describes a new algorithm of construction of the nonlinear
arithmetic triangle on the basis of numerical simulation and the binary system.
It demonstrates that the numbers that fill the nonlinear arithmetic triangle
may be binomial coefficients of a new type. An analogy has been drawn with the
binomial coefficients calculated with the use of the Pascal triangle. The paper
provides a geometrical interpretation of binomials of different types in
considering the branching systems of rays. Results of numerical calculations of
binomial distribution of the second (nonlinear) type for big power of a
binomial are given. Difference of geometrical properties of linear and
nonlinear arithmetic triangles and envelopes of binomial distributions of the
first and second types is drawn. The empirical formula for half-sums of
binomial coefficients of the second (nonlinear) type is offered. Comparison of
envelopes of binomial coefficients sums is carried out. It is shown that at big
degrees of a binomial a form of envelops of these sums are close.


title:
Exact solution for a binary system of unequal counter-rotating black
  holes

abstract:
  A complete solution describing a binary system constituted by two unequal
counter-rotating black holes with a massless strut inbetween is presented. It
is expressed in terms of four arbitrary parameters: the half length of the two
rods representing the black hole horizons sigma1 and sigma2, the total mass M,
and the relative distance R between the centers of the horizons. The explicit
form of this solution in terms of physical parameters, i.e., the Komar masses
M1 and M2, the Komar angular momenta per unit mass a1 and a2, having a1 and a2
opposite signs, and the coordinate distance R, led us to a 4-parameter subclass
of solutions in which a set of five physical parameters satisfy a simple
algebraic relation. Moreover, the interaction force, provided by the strut,
between the black holes results to be of same form as it is for the static
double-Schwarzschild case.


title:
General position of a projection and its image under a free unitary
  Brownian motion

abstract:
  Given an orthogonal projection $P$ and a free unitary Brownian motion $Y =
(Y_t)_{t \geq 0}$ in a $W^{\star}$-non commutative probability space such that
$Y$ and $P$ are $\star$-free in Voiculescu's sense, the main result of this
paper states that $P$ and $Y_tPY_t^{\star}$ are in general position at any time
$t$. To this end, we study the dynamics of the unitary operator
$SY_tSY_t^{\star}$ where $S = 2P-1$. More precisely, we derive a partial
differential equation for the Herglotz transform of its spectral distribution,
say $\mu_t$. Then, we provide a flow on the interval $[-1,1]$ in such a way
that the Herglotz transform of $\mu_t$ composed with this flow is governed by
both the Herglotz transforms of the initial ($t=0$) and the stationary ($t =
\infty)$ distributions. This fact allows to compute the weight that $\mu_t$
assigns to $z=1$ leading to the main result. As a by-product, the weight that
the spectral distribution of the free Jacobi process assigns to $x=1$ follows
after a normalization. In the last part of the paper, we use combinatorics of
non crossing partitions in order to analyze the term corresponding to the
exponential decay $e^{-nt}$ in the expansion of the $n$-th moment of
$SY_tSY_t^{\star}$.


title: Rationally trivial quadratic spaces are locally trivial:III

abstract:
  Let R be a regular semi-local domain containing a field such that all the
residue fields are infinite. Let K be the fraction field of R. Let q be a
quadratic space over R on a free rank n R-module P such that the projective
quadric q=0 is smooth over R. It is proved that if the quadratic space q is
isotropic over K, then there is a unimodular vector v in the free rank n
R-module P such that q(v)=0.
  If characteristic of R is 2, then in the case of even n our assumption on q
is equivalent to the one that q is a non-singular space in the sense of
\cite{Kn} and in the case of odd n > 2 our assumption on q is equivalent to the
one that q is a semi-regular in the sense of \cite{Kn}.


title:
Dissipative structures of quantized vortices in a coherently pumped
  polariton superfluid

abstract:
  Steady states reached in a coherently pumped exciton-polariton superfluid are
investigated. As the pump parameter is changed, the translational symmetry of
the uniform system is spontaneously broken, and various steady patterns of
quantized vortices are formed. This is peculiar to nonequilibrium dissipative
systems with continuous pumping.


title: INTEGRAL Results on Gamma-Ray Bursts

abstract:
  Despite being a general observatory, and not a Gamma-Ray Bursts (GRBs)
oriented mission, INTEGRAL has contributed to several important discoveries in
the GRB field. This has been obtained thanks to its unprecedented localization
capabilities, and sensitivity in the soft gamma-ray domain. In this paper I
will review the main results obtained during the last 10 years with, and thanks
to, INTEGRAL GRBs, including the discovery of one of the few GRBs
spectroscopically associated with a Supernova, the first measurement of
variable polarization in the GRB prompt emission, the indication of the
existence of a low-luminosity population of GRBs, as well as the recent
application of GRBs as probes for the fundamental physics. I will mention the
main global characteristics of the INTEGRAL sample, and make the point on the
lessons learnt from INTEGRAL in the perspective of designing future GRB
dedicated missions.


title:
Time dependence of X-ray diffraction intensity of a crystal induced by
  an intense femtosecond X-ray pulse

abstract:
  The time evolution of the electron density and the resulting time dependence
of X-ray diffraction peak intensity in a crystal irradiated by highly intense
femtosecond pulses of an XFEL is investigated theoretically on the basis of
rate equations for bound electrons and the Boltzmann equation for the kinetics
of the unbound electron gas that plays an essential role in the time evolution
of the electron density of a crystal. The photoionization, Auger process,
electron-impact ionization, electron--electron scattering, and three-body
recombination have been implemented in the system of rate equations. An
algorithm for the numerical solution of the rate equations was simplified by
incorporating analytical expressions for the cross sections of all the electron
configurations in ions within the framework of the effective charge model.
Using this approach we evaluate the time dependence of the inner shell
population and electronic kinetic energy during the time of XFEL pulse
propagation through the crystal for photon energies between 3 and 12 keV and a
pulse width of 40 fs considering a flux of 10^12 ph/pulse (focusing on a spot
size of ~ 1 mum^2, this flux corresponds to a fluence ranging between 0.6 and
1.6 mJ/mum^2). The time evolution of the atomic scattering factor and its
fluctuation is numerically analyzed for the case of a Silicon crystal taking
into account the decrease of the bound electron density during the pulse
propagation. The time integrated intensity drops dramatically if the fluence of
the XFEL pulse exceeds 1.6 mJ/mum^2.


title: Norms of idempotent Schur multipliers

abstract:
  Let D be a masa in B(H) where H is a separable Hilbert space. We find real
numbers \eta_0 < \eta_1 < \eta_2 < ... < \eta_6 so that for every bounded,
normal D-bimodule map {\Phi} on B(H) either ||\Phi|| > \eta_6, or ||\Phi|| =
\eta_k for some k <= 6. When D is totally atomic, these maps are the idempotent
Schur multipliers and we characterise those with norm \eta_k for 0 <= k <= 6.
We also show that the Schur idempotents which keep only the diagonal and
superdiagonal of an n x n matrix, or of an n x (n+1) matrix, both have norm
2/(n+1) cot(pi/(n+1)), and we consider the average norm of a random idempotent
Schur multiplier as a function of dimension. Many of our arguments are framed
in the combinatorial language of bipartite graphs.


title: Radial Solutions of Non-Archimedean Pseudo-Differential Equations

abstract:
  We consider a class of equations with the fractional differentiation operator
$D^\alpha$, $\alpha >0$, for complex-valued functions $x\mapsto f(|x|_K)$ on a
non-Archimedean local field $K$ depending only on the absolute value $|\cdot
|_K$. We introduce a right inverse $I^\alpha$ to $D^\alpha$, such that the
change of an unknown function $u=I^\alpha v$ reduces the Cauchy problem for an
equation with $D^\alpha$ (for radial functions) to an integral equation whose
properties resemble those of classical Volterra equations. This contrasts much
more complicated behavior of $D^\alpha$ on other classes of functions.


title: Spectral analysis on interior transmission eigenvalues

abstract:
  In this paper we prove some results on interior transmission eigenvalues.
First, under rea- sonable assumptions, we prove that the spectrum is a discrete
countable set and the generalized eigenfunctions spanned a dense space in the
range of resolvent. This is a consequence of spectral theory of Hilbert-Schmidt
operators. The main ingredient is to prove a smoothing property of resolvent.
This allows to prove that a power of the resolvent is Hilbert-Schmidt. We
obtain an estimate of the number of eigenvalues, counting with multiplicities,
with modulus less than t2 when t is large. We prove also some estimate on the
resolvent near the real axe when the square of the index of refraction is not
real. Under some assumptions we obtain lower bound on the resolvent using the
results obtained by Dencker, Sj\"ostrand and Zworski on the pseudospectra.


title: Rare Kaon decays

abstract:
  Rare Kaon decays and CP violation are important tools to test the Standard
Model and its extensions. We describe kaon physics observables testing CP
violation and more generally short distance physics. Channels under
consideration will be K -> pi nu nubar, K -> pi l+ l-, K+- > pi 3 pi, K+- ->
pi+- pi gamma, KS -> mu mu and K+- -> pi+- pi0 e+ e-


title: Consistency of Online Random Forests

abstract:
  As a testament to their success, the theory of random forests has long been
outpaced by their application in practice. In this paper, we take a step
towards narrowing this gap by providing a consistency result for online random
forests.


title: An Explicit Martingale Version of Brenier's Theorem

abstract:
  By investigating model-independent bounds for exotic options in financial
mathematics, a martingale version of the Monge-Kantorovich mass transport
problem was introduced in \cite{BeiglbockHenry
LaborderePenkner,GalichonHenry-LabordereTouzi}. In this paper, we extend the
one-dimensional Brenier's theorem to the present martingale version. We provide
the explicit martingale optimal transference plans for a remarkable class of
coupling functions corresponding to the lower and upper bounds. These explicit
extremal probability measures coincide with the unique left and right monotone
martingale transference plans, which were introduced in \cite{BeiglbockJuillet}
by suitable adaptation of the notion of cyclic monotonicity. Instead, our
approach relies heavily on the (weak) duality result stated in
\cite{BeiglbockHenry-LaborderePenkner}, and provides, as a by-product, an
explicit expression for the corresponding optimal semi-static hedging
strategies. We finally provide an extension to the multiple marginals case.


title:
Large transport critical currents and magneto-optical imaging of
  textured Sr1-xKxFe2As2 superconducting tapes

abstract:
  We report the temperature dependence of the transport critical current
density (Jc) in textured Sr1-xKxFe2As2/Fe (Sr122) tapes fabricated by an ex
situ powder-in-tube process. Critical currents were measured in magnetic fields
up to 0-15 T and/or the temperature range 4.2-30 K by using a dc four-probe
method. It was found that textured Sr122 tapes heat-treated at low temperatures
showed higher transport Jc performance due to much improved intergrain
connections. At temperatures of 20 K, easily obtained using a cryocooler, Jc
reached ~ 10^4 A/cm^2 in self field, which is the highest transport value of
ferropnictide wires and tapes reported so far. Magneto-optical imaging
observations further revealed significant and well distributed global Jc at 20
K in our tapes. These results demonstrate that 122 type superconducting tapes
are promising for high-field applications at around 20 K.


title: An algebraic approach to weak and delay bismulation in coalgebra

abstract:
  The aim of this paper is to introduce an algebraic structure on the set of
all coalgebras with the same state space over the given type which allows us to
present definitions of weak and delay bisimulation for coalgebras.
Additionally, we introduce an algebraic structure on the carrier set of the
final coalgebra and characterize a special subcoalgebra of the final coalgebra
which is used in the formulation of the weak coinduction principle. Finally,
the new algebraic setting allows us to present a definition of an approximated
weak bisimulation, study its properties and compare it with previously defined
weak bisimulation for coalgebras.


title: Expectation Maximization for Hard X-ray Count Modulation Profiles

abstract:
  This paper is concerned with the image reconstruction problem when the
measured data are solar hard X-ray modulation profiles obtained from the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI)} instrument. Our goal is
to demonstrate that a statistical iterative method classically applied to the
image deconvolution problem is very effective when utilized for the analysis of
count modulation profiles in solar hard X-ray imaging based on Rotating
Modulation Collimators. The algorithm described in this paper solves the
maximum likelihood problem iteratively and encoding a positivity constraint
into the iterative optimization scheme. The result is therefore a classical
Expectation Maximization method this time applied not to an image deconvolution
problem but to image reconstruction from count modulation profiles. The
technical reason that makes our implementation particularly effective in this
application is the use of a very reliable stopping rule which is able to
regularize the solution providing, at the same time, a very satisfactory
Cash-statistic (C-statistic). The method is applied to both reproduce synthetic
flaring configurations and reconstruct images from experimental data
corresponding to three real events. In this second case, the performance of
Expectation Maximization, when compared to Pixon image reconstruction, shows a
comparable accuracy and a notably reduced computational burden; when compared
to CLEAN, shows a better fidelity with respect to the measurements with a
comparable computational effectiveness. If optimally stopped, Expectation
Maximization represents a very reliable method for image reconstruction in the
RHESSI context when count modulation profiles are used as input data.


title: Trajectory generation and display for free flight

abstract:
  In this study a new approach is proposed for the generation of aircraft
trajectories. The relative guidance of an aircraft, which is aimed to join in
minimum time the track of a leader aircraft, is particularly considered. In a
first place, a minimum time relative convergence problem is considered and
optimal trajectories are characterized. Then the synthesis of a neural
approximator for optimal trajectories is discussed. Trained neural networks are
used in an adaptive manner to generate intent trajectories during operation.
Finally simulation results involving two wide body aircraft are presented.


title: On the waiting time till some patterns occur in i.i.d. sequences

abstract:
  In this paper we present some general solution of the system of linear
equations formed by Guibas and Odlyzko in Th.3.3 \cite{Gui}. We derive
probabilities for given patterns to be first to appear in random text and the
expected waiting time till one of them is observed and also till one of them
occurs given it is known which pattern appears first.


title: Subsonic Free Surface Waves in Linear Elasticity

abstract:
  For general anisotropic linear elastic solids with smooth boundaries,
Rayleigh-type surface waves are studied. Using spectral factorizations of
matrix polynomials, a self-contained exposition of the case of a homogeneous
half-space is given first. The main result is about inhomogeneous anisotropic
bodies with curved surfaces. The existence of subsonic free surface waves is
shown by giving ray series asymptotic expansions, including formulas for the
transport equation.


title:
Field effect doping of graphene in metal|dielectric|graphene
  heterostructures: a model based upon first-principles calculations

abstract:
  We study how the Fermi energy of a graphene monolayer separated from a
conducting substrate by a dielectric spacer depends on the properties of the
substrate and on an applied voltage. An analytical model is developed that
describes the Fermi level shift as a function of the gate voltage, of the
substrate work function, and of the type and thickness of the dielectric
spacer. The parameters of this model, that should describe the effect of gate
electrodes in field-effect devices, can be obtained from density functional
theory (DFT) calculations on single layers or interfaces. The doping of
graphene in metal|dielectric|graphene structures is found to be determined not
only by the difference in work function between the metal and graphene and the
dielectric properties of the spacer but potential steps that result from
details of the microscopic bonding at the interfaces also play an important
role. The doping levels predicted by the model agree very well with the results
obtained from first-principles DFT calculations on metal|dielectric|graphene
structures with the metals Al, Co, Ni, Cu, Pd, Ag, Pt or Au, and a h-BN or
vacuum dielectric spacer.


title: Bouncing of charged droplets: An explanation using mean curvature flow

abstract:
  Two oppositely charged droplets of (say) water in e.g. oil or air will tend
to drift together under the influence of their charges. As they make contact,
one might expect them to coalesce and form one large droplet, and this indeed
happens when the charge difference is sufficiently small. However, Ristenpart
et al discovered a remarkable physical phenomenon whereby for large enough
charge differentials, the droplets bounce off each other as they make contact.
Explanations based on minimisation of area under a volume constraint have been
proposed based on the premise that consideration of surface energy cannot be
sufficient. However, in this note we explain that on the contrary, the bouncing
phenomenon can be completely explained in terms of energy, including an
accurate prediction of the threshold charge differential between coalescence
and bouncing.


title:
A high-field 3He Metastability Exchange Optical Pumping polarizer
  operating in a 1.5 T medical scanner for lung MRI

abstract:
  After being hyperpolarized using the technique of Metastability Exchange
Optical Pumping (MEOP), 3He can be used as a contrast agent for lung magnetic
resonance imaging (MRI). MEOP is usually performed at low magnetic field (~ 1
mT) and low pressure (~ 1 mbar), which results in a low magnetization
production rate. A delicate polarization-preserving step of compression is also
required. It was demonstrated in sealed cells that high nuclear polarization
values can be obtained at higher pressures with MEOP, if performed at high
magnetic field (non-standard conditions). In this work the feasibility of
building a high-field polarizer that operates within a commercial 1.5 T scanner
was evaluated. Preliminary measurements of nuclear polarization with sealed
cells filled at different 3He gas pressures (1.33 to 267 mbar) were performed.
The use of an annular shape for the laser beam increased by 25 % the achievable
nuclear polarization equilibrium value (Meq) at 32 and 67 mbar as compared to a
Gaussian beam shape. Meq values of 66.4 and 31 % were obtained at 32 and 267
mbar respectively and the magnetization production rate was increased by a
factor of 10 compared to the best results obtained under standard conditions.
To study the reproducibility of the method in a polarizing system, the same
experiments were performed with small cells connected to a gas handling system.
The polarization build-up times were approximately 3 times longer in the 20-30
mbar range of pressure than those obtained for the 32 mbar sealed cell.
However, reasonable Meq values of 40-60 % were achieved in a 90 mL open cell.
Based on these findings, a novel compact polarizing system was designed and
built. Its typical output is a 3He gas flow rate of 15 sccm with a polarization
of 33 %. In-vivo lung MRI ventilation images were acquired to demonstrate the
polarizer s application.


title:
Technology Transfer and the End of the Bayh-Dole Effect: Patents as an
  Analytical Lens on University-Industry-Government Relations

abstract:
  Three periods can be distinguished in university patenting at the U.S. Patent
and Trade Office (USPTO) since the Bayh-Dole Act of 1980: (1) a first period of
exponential increase in university patenting till 1995 (filing date) or 1999
(issuing date); (2) a period of relative decline since 1999; and (3) in most
recent years -- since 2008 -- a linear increase in university patenting. We
argue that this last period is driven by specific non-US universities (e.g.,
Tokyo University and Chinese universities) patenting increasingly in the U.S.A.
as the most competitive market for high-tech patents.


title:
Bloch-wave homogenization on large time scales and dispersive effective
  wave equations

abstract:
  We investigate second order linear wave equations in periodic media, aiming
at the derivation of effective equations in $\R^n$, $n \in \{1, 2, 3\}$.
Standard homogenization theory provides, for the limit of a small periodicity
length $\eps>0$, an effective second order wave equation that describes
solutions on time intervals $[0,T]$. In order to approximate solutions on large
time intervals $[0,T\eps^{-2}]$, one has to use a dispersive, higher order wave
equation. In this work, we provide a well-posed, weakly dispersive effective
equation, and an estimate for errors between the solution of the original
heterogeneous problem and the solution of the dispersive wave equation. We use
Bloch-wave analysis to identify a family of relevant limit models and introduce
an approach to select a well-posed effective model under symmetry assumptions
on the periodic structure. The analytical results are confirmed and illustrated
by numerical tests.


title: Cosmological implications of Geometrothermodynamics

abstract:
  We use the formalism of Geometrothermodynamics to derive a series of
fundamental equations for thermodynamic systems. It is shown that all these
fundamental equations can be used in the context of relativistic cosmology to
derive diverse scenarios which include the standard cosmological model, a
unified model for dark energy and dark matter, and an effective inflationary
model.


title:
Lifetimes of antiferromagnetic magnons in two and three dimensions:
  experiment, theory, and numerics

abstract:
  A high-resolution neutron spectroscopic technique is used to measure
momentum-resolved magnon lifetimes in the prototypical two- and
three-dimensional antiferromagnets Rb2MnF4 and MnF2, over the full Brillouin
zone and a wide range of temperatures. We rederived theories of the lifetime
resulting from magnon-magnon scattering, thereby broadening their applicability
beyond asymptotically small regions of wavevector and temperature.
Corresponding computations, combined with a small contribution reflecting
collisions with domain boundaries, yield excellent quantitative agreement with
the data.


title: Nonequilibrium glass transitions in driven and active matter

abstract:
  The glass transition, extensively studied in dense fluids, polymers, or
colloids, corresponds to a dramatic evolution of equilibrium transport
coefficients upon a modest change of control parameter, like temperature or
pressure. A similar phenomenology is found in many systems evolving far from
equilibrium, such as driven granular media, active and living matter. While
many theories compete to describe the glass transition at thermal equilibrium,
very little is understood far from equilibrium. Here, we solve the dynamics of
a specific, yet representative, class of glass models in the presence of
nonthermal driving forces and energy dissipation, and show that a dynamic
arrest can take place in these nonequilibrium conditions. While the location of
the transition depends on the specifics of the driving mechanisms, important
features of the glassy dynamics are insensitive to details, suggesting that an
`effective' thermal dynamics generically emerges at long time scales in
nonequilibrium systems close to dynamic arrest.


title: Non-magnetic doping induced magnetism in Li doped SnO2 nanoparticles

abstract:
  We address the possibility of non-magnetic doping induced magnetism, in Li
doped SnO2 nano-particles. The compounds have been prepared by solid state
route at equilibrium and were found to be crystallized in single rutile phase.
The magnetization measurements have shown that Li-doping induces magnetism in
SnO2 for a particular range of Li concentration. However, for other Li
concentrations, including pure SnO2, the samples exhibit diamagnetism. To
investigate the possible origin of the induced magnetism, we have studied the
variation of the magnetization as a function of the average nano-particle
radius. Possible scenarios for the appearance of magnetism in these compounds
are discussed.


title: Bar 1-Visibility Drawings of 1-Planar Graphs

abstract:
  A bar 1-visibility drawing of a graph $G$ is a drawing of $G$ where each
vertex is drawn as a horizontal line segment called a bar, each edge is drawn
as a vertical line segment where the vertical line segment representing an edge
must connect the horizontal line segments representing the end vertices and a
vertical line segment corresponding to an edge intersects at most one bar which
is not an end point of the edge. A graph $G$ is bar 1-visible if $G$ has a bar
1-visibility drawing. A graph $G$ is 1-planar if $G$ has a drawing in a
2-dimensional plane such that an edge crosses at most one other edge. In this
paper we give linear-time algorithms to find bar 1-visibility drawings of
diagonal grid graphs and maximal outer 1-planar graphs. We also show that
recursive quadrangle 1-planar graphs and pseudo double wheel 1-planar graphs
are bar 1-visible graphs.


title: Cosmographic reconstruction of $f(\mathcal{T})$ cosmology

abstract:
  A cosmographic reconstruction of $f(\mathcal T)$ models is here revised in a
model independent way by fixing observational bounds on the most relevant terms
of the $f(\mathcal T)$ Taylor expansion. We relate the $f(\mathcal T)$ models
and their derivatives to the cosmographic parameters and then adopt a Monte
Carlo analysis. The experimental bounds are thus independent of the choice of a
particular $f(\mathcal T)$ model. The advantage of such an analysis lies on
constraining the dynamics of the universe by reconstructing the form of
$f(\mathcal T)$, without any further assumptions apart from the validity of the
cosmological principle and the analyticity of the $f(\mathcal T)$ function. The
main result is to fix model independent cosmographic constraints on the
functional form of $f(\mathcal T)$ which are compatible with the theoretical
predictions. Furthermore, we infer a phenomenological expression for
$f(\mathcal T)$, compatible with the current cosmographic bounds and show that
small deviations are expected from a constant $f(\mathcal T)$ term, indicating
that the equation of state of dark energy could slightly evolve from the one of
the $\Lambda$CDM model.


title: Cohesion, consensus and extreme information in opinion dynamics

abstract:
  Opinion formation is an important element of social dynamics. It has been
widely studied in the last years with tools from physics, mathematics and
computer science. Here, a continuous model of opinion dynamics for multiple
possible choices is analysed. Its main features are the inclusion of
disagreement and possibility of modulating information, both from one and
multiple sources. The interest is in identifying the effect of the initial
cohesion of the population, the interplay between cohesion and information
extremism, and the effect of using multiple sources of information that can
influence the system. Final consensus, especially with external information,
depends highly on these factors, as numerical simulations show. When no
information is present, consensus or segregation is determined by the initial
cohesion of the population. Interestingly, when only one source of information
is present, consensus can be obtained, in general, only when this is extremely
mild, i.e. there is not a single opinion strongly promoted, or in the special
case of a large initial cohesion and low information exposure. On the contrary,
when multiple information sources are allowed, consensus can emerge with an
information source even when this is not extremely mild, i.e. it carries a
strong message, for a large range of initial conditions.


title: On the existence of (H,A)-stable sheaves on K3 or abelian surfaces

abstract:
  We give an existence result on (H,A)-stable sheaves on a K3 or abelian
surface X with primitive triple of invariants (rank,first Chern class,Euler
characteristics) in the integral cohomology lattice. Such a result yields the
existence of singular projective Q-factorial symplectic terminalisations of
certain moduli spaces of sheaves on X that are Gieseker semistable with respect
to a nongeneral ample divisor.


title: A Labeled Graph Kernel for Relationship Extraction

abstract:
  In this paper, we propose an approach for Relationship Extraction (RE) based
on labeled graph kernels. The kernel we propose is a particularization of a
random walk kernel that exploits two properties previously studied in the RE
literature: (i) the words between the candidate entities or connecting them in
a syntactic representation are particularly likely to carry information
regarding the relationship; and (ii) combining information from distinct
sources in a kernel may help the RE system make better decisions. We performed
experiments on a dataset of protein-protein interactions and the results show
that our approach obtains effectiveness values that are comparable with the
state-of-the art kernel methods. Moreover, our approach is able to outperform
the state-of-the-art kernels when combined with other kernel methods.


title:
Generalized spherically symmetric gravitational model: Hamiltonian
  dynamics in extended phase space and BRST charge

abstract:
  We construct Hamiltonian dynamics of the generalized spherically symmetric
gravitational model in extended phase space. We start from the Faddeev - Popov
effective action with gauge-fixing and ghost terms, making use of gauge
conditions in differential form. It enables us to introduce missing velocities
into the Lagrangian and then construct a Hamiltonian function according a usual
rule which is applied for systems without constraints. The main feature of
Hamiltonian dynamics in extended phase space is that it can be proved to be
completely equivalent to Lagrangian dynamics derived from the effective action.
We find a BRST invariant form of the effective action by adding terms not
affecting Lagrangian equations. After all, we construct the BRST charge
according to the Noether theorem. Our algorithm differs from that by Batalin,
Fradkin and Vilkovisky, but the resulting BRST charge generates correct
transformations for all gravitational degrees of freedom including gauge ones.
Generalized spherically symmetric model imitates the full gravitational theory
much better then models with finite number of degrees of freedom, so that one
can expect appropriate results in the case of the full theory.


title:
GRB 121027A: long-lasting, energetic X-ray flares and clues to radiation
  mechanism and progenitor star

abstract:
  GRB 121027A is un-usual with its extremely long-lasting, energetic X-ray
flares. The total energy release in X-ray flares is about one order of
magnitude higher than prompt gamma-rays, making it special from most long GRBs.
We show that while the prompt gamma-ray emission satisfies the empirical
E_{iso}-E_{p} relation of typical long GRBs, the X-ray flares, whose spectra
can be fit with a cutoff-power-law model with well-constrained E_p,
significantly deviate from such a relation. Nonetheless, a time-resolved
spectral analysis of X-ray flares suggest that the X-ray emission is consistent
with the L_{iso}-E_{p} relation of long GRBs. We constrain the minimum Lorentz
factor of the X-ray flares to be ~14, which is consistent with the
Gamma-L_{iso} relation. Our results imply that prompt gamma-ray emission and
late X-ray flares share the similar radiation mechanism, but originate from the
outflows with different Lorentz factors. We search for similar GRBs from the
Swift GRB archives, and find that the z=6.29 GRB 050904 is a carbon copy of GRB
121027A. The long-lasting, energetic X-ray flares in these GRBs demand
significant accretion at late times, which point towards a large-radius
progenitor star.


title: Transverse relativistic effects in paraxial wave interference

abstract:
  We consider relativistic deformations of interfering paraxial waves moving in
the transverse direction. Owing to superluminal transverse phase velocities,
noticeable deformations of the interference patterns arise when the waves move
with respect to each other with non-relativistic velocities. Similar
distortions also appear on a mutual tilt of the interfering waves, which causes
a phase delay analogous to the relativistic time delay. We illustrate these
observations by the interference between a vortex wave beam and a plane wave,
which exhibits a pronounced deformation of the radial fringes into a fork-like
pattern (relativistic Hall effect). Furthermore, we describe an additional
relativistic motion of the interference fringes (a counter-rotation in the
vortex case), which become noticeable at the same non-relativistic velocities.


title: Giant X-ray Bump in GRB 121027A: Evidence for Fall-back Disk Accretion

abstract:
  A particularly interesting discovery in observations of GRB 121027A is that
of a giant X-ray bump detected by the Swift/X-Ray Telescope. The X-ray
afterglow re-brightens sharply at about 1000 s after the trigger by more than
two orders of magnitude in less than 200 s. This X-ray bump lasts for more than
10 ks. It is quite different from typical X-ray flares. In this Letter we
propose a fall-back accretion model to interpret this X-ray bump within the
context of the collapse of a massive star for a long-duration gamma-ray burst.
The required fall-back radius of about 3.5e10 cm and mass of about 0.9-2.6
solar masses imply that a significant part of the helium envelope should
survive through the mass loss during the last stage of the massive progenitor
of GRB 121027A.


title: Burnett coefficients in quantum many-body systems

abstract:
  The Burnett coefficient B is investigated for transport in one-dimensional
quantum many-body systems. Extensive numerical computations in spin-1/2 chains
suggest a linear growth with time, B(t) \sim t, for non-integrable chains
exhibiting diffusive transport. For integrable spin chains in the metallic
regime, on the other hand, we find a cubic growth with time, B(t) \sim -D_m^2
t^3, with the proportionality constant being simply a square of the Drude
weight D_m. The results are corroborated with additional studies in
non-interacting quantum chains and in the classical limit of large-spin chains.


title: On the range of the attenuated ray transform for unitary connections

abstract:
  We describe the range of the attenuated ray transform of a unitary connection
on a simple surface acting on functions and 1-forms. We use this to determine
the range of the ray transform acting on symmetric tensor fields.


title:
Elliptical Insights: Understanding Statistical Methods through
  Elliptical Geometry

abstract:
  Visual insights into a wide variety of statistical methods, for both didactic
and data analytic purposes, can often be achieved through geometric diagrams
and geometrically based statistical graphs. This paper extols and illustrates
the virtues of the ellipse and her higher-dimensional cousins for both these
purposes in a variety of contexts, including linear models, multivariate linear
models and mixed-effect models. We emphasize the strong relationships among
statistical methods, matrix-algebraic solutions and geometry that can often be
easily understood in terms of ellipses.


title: Detection of Cooperative Black Hole Attack in Wireless Ad Hoc Networks

abstract:
  A mobile ad hoc network (MANET) is a collection of autonomous nodes that
communicate with each other by forming a multi-hop radio network and
maintaining connections in a decentralized manner. Security remains a major
challenge for these networks due to their features of open medium, dynamically
changing topologies, reliance on cooperative algorithms, absence of centralized
monitoring points, and lack of clear lines of defense. Protecting the network
layer of a MANET from malicious attacks is an important and challenging
security issue, since most of the routing protocols for MANETs are vulnerable
to various types of attacks. Ad hoc on-demand distance vector routing (AODV) is
a very popular routing algorithm. However, it is vulnerable to the well-known
black hole attack, where a malicious node falsely advertises good paths to a
destination node during the route discovery process but drops all packets in
the data forwarding phase. This attack becomes more severe when a group of
malicious nodes cooperate each other. The proposed mechanism does not apply any
cryptographic primitives on the routing messages. Instead, it protects the
network by detecting and reacting to malicious activities of the nodes.
Simulation results show that the scheme has a significantly high detection rate
with moderate network traffic overhead and computation overhead in the nodes.


title:
Innerness of continuous derivations on algebras of locally measurable
  operators

abstract:
  It is established that every derivation continuous with respect to the local
measure topology acting on the *-algebra $LS(\mathcal{M})$ of all locally
measurable operators affiliated with a von Neumann algebra $\mathcal{M}$ is
necessary inner. If $\mathcal{M}$ is a properly infinite von Neumann algebra,
then every derivation on $LS(\mathcal{M})$ is inner. In addition, it is proved
that any derivation on $\mathcal{M}$ with values in Banach
$\mathcal{M}$-bimodule of locally measurable operators is inner.


title: Spiraling eutectic dendrites

abstract:
  Eutectic dendrites forming in a model ternary system have been studied using
the phase-field theory. The eutectic and one-phase dendrites have similar
forms, and the tip radius scales with the interface free energy as for
one-phase dendrites. The steady-state eutectic patterns appearing on these
two-phase dendrites include concentric rings, and single- to multiarm spirals,
of which the fluctuations choose, a stochastic phenomenon characterized by a
peaked probability distribution. The number of spiral arms correlates with tip
radius and the kinetic anisotropy.


title: On free infinite divisibility for classical Meixner distributions

abstract:
  We prove that symmetric Meixner distributions, whose probability densities
are proportional to $|\Gamma(t+ix)|^2$, are freely infinitely divisible for
$0<t\leq\frac{1}{2}$. The case $t=\frac{1}{2}$ corresponds to the law of
L\'evy's stochastic area whose probability density is $\frac{1}{\cosh(\pi x)}$.
A logistic distribution, whose probability density is proportional to
$\frac{1}{\cosh^2(\pi x)}$, is freely infinitely divisible too.


title:
Fast methods for denoising matrix completion formulations, with
  applications to robust seismic data interpolation

abstract:
  Recent SVD-free matrix factorization formulations have enabled rank
minimization for systems with millions of rows and columns, paving the way for
matrix completion in extremely large-scale applications, such as seismic data
interpolation.
  In this paper, we consider matrix completion formulations designed to hit a
target data-fitting error level provided by the user, and propose an algorithm
called LR-BPDN that is able to exploit factorized formulations to solve the
corresponding optimization problem. Since practitioners typically have strong
prior knowledge about target error level, this innovation makes it easy to
apply the algorithm in practice, leaving only the factor rank to be determined.
  Within the established framework, we propose two extensions that are highly
relevant to solving practical challenges of data interpolation. First, we
propose a weighted extension that allows known subspace information to improve
the results of matrix completion formulations. We show how this weighting can
be used in the context of frequency continuation, an essential aspect to
seismic data interpolation. Second, we propose matrix completion formulations
that are robust to large measurement errors in the available data.
  We illustrate the advantages of LR-BPDN on the collaborative filtering
problem using the MovieLens 1M, 10M, and Netflix 100M datasets. Then, we use
the new method, along with its robust and subspace re-weighted extensions, to
obtain high-quality reconstructions for large scale seismic interpolation
problems with real data, even in the presence of data contamination.


title:
Limit theorems for the pre-averaged Hayashi-Yoshida estimator with
  random sampling

abstract:
  We will focus on estimating the integrated covariance of two diffusion
processes observed in a nonsynchronous manner. The observation data is
contaminated by some noise, which is possibly correlated with the returns of
the diffusion processes, while the sampling times also possibly depend on the
observed processes. In a high-frequency setting, we consider a modified version
of the pre-averaged Hayashi-Yoshida estimator, and we show that such a kind of
estimators has the consistency and the asymptotic mixed normality, and attains
the optimal rate of convergence.


title: Exploiting Social Tags for Cross-Domain Collaborative Filtering

abstract:
  One of the most challenging problems in recommender systems based on the
collaborative filtering (CF) concept is data sparseness, i.e., limited user
preference data is available for making recommendations. Cross-domain
collaborative filtering (CDCF) has been studied as an effective mechanism to
alleviate data sparseness of one domain using the knowledge about user
preferences from other domains. A key question to be answered in the context of
CDCF is what common characteristics can be deployed to link different domains
for effective knowledge transfer. In this paper, we assess the usefulness of
user-contributed (social) tags in this respect. We do so by means of the
Generalized Tag-induced Cross-domain Collaborative Filtering (GTagCDCF)
approach that we propose in this paper and that we developed based on the
general collective matrix factorization framework. Assessment is done by a
series of experiments, using publicly available CF datasets that represent
three cross-domain cases, i.e., two two-domain cases and one three-domain case.
A comparative analysis on two-domain cases involving GTagCDCF and several
state-of-the-art CDCF approaches indicates the increased benefit of using
social tags as representatives of explicit links between domains for CDCF as
compared to the implicit links deployed by the existing CDCF methods. In
addition, we show that users from different domains can already benefit from
GTagCDCF if they only share a few common tags. Finally, we use the three-domain
case to validate the robustness of GTagCDCF with respect to the scale of
datasets and the varying number of domains.


title: Hyperbolicity of minimal periodic orbits

abstract:
  For positive definite Lagrange systems with two degrees of freedom, it is a
typical phenomenon that all minimal periodic orbits are hyperbolic.


title: The eclipsing binary TY CrA revisited: What near-IR light curves tell us

abstract:
  New photometric observations of the hierarchical eclipsing TY CrA system were
taken in the optical with VYSOS6 and in the near-IR with SOFI and REMIR. They
are the first observations showing the deep eclipse minimum of the pre-main
sequence secondary in the near-IR. For the first time, the secondary minimum
can be reliably used in the calculation of the O-C diagram of TY CrA. By now,
the O-C diagram can be studied on a time basis of about two decades. We
confirm, that the O-C diagram cannot be explained by the spectroscopic
tertiary. For the first time, the light curve of the inner eclipsing binary is
analysed in both optical and near-IR bands simultaneously. In combination with
already published spectroscopic elements, precise absolute dimensions and
masses of the primary and the secondary component are obtained using the ROCHE
code. The inclusion of the near-IR data puts strong constraints on the third
light which is composed of the reflection nebula, the spectroscopic tertiary
and a visual fourth component. The absolute parameters of the inner eclipsing
binary agree very well with previous work except of the primary radius
(1.46+/-0.15 Rsun) and luminosity (40+/-10 Lsun) which are clearly smaller.
While the parameters of the secondary are well understood when assuming an age
of about 3-5 Myrs, the primary seems considerably undersized. Low metallicity
cannot explain the parameters of the primary.


title:
Quantum critical point of spin-boson model and infrared catastrophe in
  bosonic bath

abstract:
  An analytic ground state is proposed for the unbiased spin-boson Hamiltonian,
which is non-Gaussian and beyond the Silbey-Harris ground state with lower
ground state energy. The infrared catastrophe in Ohmic and sub-Ohmic bosonic
bath plays an important role in determining the degeneracy of the ground state.
We show that the infrared divergence associated with the displacement of the
nonadiabatic modes in bath may be removed from the proposed ground state for
the coupling $\alpha<\alpha_c$. Then $\alpha_c$ is the quantum critical point
of a transition from non-degenerate to degenerate ground state and our
calculated $\alpha_c$ agrees with previous numerical results.


title: Multiple Partonic Interactions in Herwig++

abstract:
  We review the implementation of a model for multiple partonic interactions in
Herwig++. Moreover, we show how recent studies on the colour structure of
events in Herwig++ led to a significant improvement in the description of soft
inclusive observables in pp interactions at the LHC.


title: Atmosphere above a large solar pore

abstract:
  A large solar pore with a granular light bridge was observed on October 15,
2008 with the IBIS spectrometer at the Dunn Solar Telescope and a 69-min long
time series of spectral scans in the lines Ca II 854.2 nm and Fe I 617.3 nm was
obtained. The intensity and Doppler signals in the Ca II line were separated.
This line samples the middle chromosphere in the core and the middle
photosphere in the wings. Although no indication of a penumbra is seen in the
photosphere, an extended filamentary structure, both in intensity and Doppler
signals, is observed in the Ca II line core. An analysis of morphological and
dynamical properties of the structure shows a close similarity to a
superpenumbra of a sunspot with developed penumbra. A special attention is paid
to the light bridge, which is the brightest feature in the pore seen in the Ca
II line centre and shows an enhanced power of chromospheric oscillations at 3-5
mHz. Although the acoustic power flux in the light bridge is five times higher
than in the "quiet" chromosphere, it cannot explain the observed brightness.


title: Lacunary Generating Functions for the Laguerre Polynomials

abstract:
  Symbolic methods of umbral nature play an important and increasing role in
the theory of special functions and in related fields like combinatorics. We
discuss an application of these methods to the theory of lacunary generating
functions for the Laguerre polynomials for which we give a number of new closed
form expressions. We present furthermore the different possibilities offered by
the method we have developed, with particular emphasis on their link to a new
family of special functions and with previous formulations, associated with the
theory of quasi monomials.


title: The Herschel census of infrared SEDs through cosmic time

abstract:
  Using Herschel data from the deepest SPIRE and PACS surveys (HerMES and PEP)
in COSMOS and GOODS (N+S), we examine the dust properties of IR-luminous
(L_IR>10^10 L_sun) galaxies at 0.1<z<2 and determine how these evolve with
cosmic time. The unique angle of this work is the rigorous analysis of survey
selection effects, making this the first study of the star-formation-dominated,
IR-luminous population within a framework almost entirely free of selection
biases. We find that IR-luminous galaxies have SEDs with broad far-IR peaks
characterised by cool/extended dust emission and average dust temperatures in
the 25-45K range. Hot (T>45K) SEDs and cold (T<25K), cirrus-dominated SEDs are
rare, with most sources being within the range occupied by warm starbursts such
as M82 and cool spirals such as M51. We observe a luminosity-temperature (L-T)
relation, where the average dust temperature of log[L_IR/L_sun]=12.5 galaxies
is about 10K higher than that of their log[L_IR/L_sun]=10.5 counterparts.
However, although the increased dust heating in more luminous systems is the
driving factor behind the L-T relation, the increase in dust mass and/or
starburst size with luminosity plays a dominant role in shaping it. Our results
show that the dust conditions in IR-luminous sources evolve with cosmic time:
at high redshift, dust temperatures are on average up to 10K lower than what is
measured locally. This is manifested as a flattening of the L-T relation,
suggesting that (U)LIRGs in the early Universe are typically characterised by a
more extended dust distribution and/or higher dust masses than local equivalent
sources. Interestingly, the evolution in dust temperature is luminosity
dependent, with the fraction of LIRGs with T<35K showing a 2-fold increase from
z~0 to z~2, whereas that of ULIRGs with T<35K shows a 6-fold increase.


title:
Hybrid heterostructures with superconducting/antiferromagnetic
  interfaces

abstract:
  We report on structural, DC, X-ray and neutron studies of hybrid
superconducting mesa-heterostructures with a cuprate antiferromagnetic
interlayer Ca1-xSrxCuO2 (CSCO). The upper electrode was bilayer Nb/Au
superconductor and copper oxide superconductor YBa2Cu3O7 (YBCO) was the bottom
electrode. It was experimentally shown that during the epitaxial growth of the
two films YBCO and CSCO a charge carrier doping takes place in the CSCO
interlayer with a depth about 20 nm. The conductivity of the doped part of CSCO
layer is close to the metal type, while the reference CSCO film, deposited
directly on NdGaO3 substrate, behaves as Mott insulator with the hopping
conductivity. The interface Au/CSCO is clearly seen on bright-field image of
the cross-section of heterostructure and gives the main contribution to the
total resistance of mesa-heterostructure.


title: Spatial entanglement of bosons in optical lattices

abstract:
  Entanglement is a fundamental resource for quantum information processing,
occurring naturally in many-body systems at low temperatures. The presence of
entanglement and, in particular, its scaling with the size of system partitions
underlies the complexity of quantum many-body states. The quantitative
estimation of entanglement in many-body systems represents a major challenge as
it requires either full state tomography, scaling exponentially in the system
size, or the assumption of unverified system characteristics such as its
Hamiltonian or temperature. Here we adopt recently developed approaches for the
determination of rigorous lower entanglement bounds from readily accessible
measurements and apply them in an experiment of ultracold interacting bosons in
optical lattices of approximately $10^5$ sites. We then study the behaviour of
spatial entanglement between the sites when crossing the superfluid-Mott
insulator transition and when varying temperature. This constitutes the first
rigorous experimental large-scale entanglement quantification in a scalable
quantum simulator.


title: Transitions in Dilaton Holography with Global or Local Symmetries

abstract:
  We study various transitions in dilaton holography, including those
associated with the spontaneous breaking of a global (superfluid case) or local
(superconductor case) U(1) symmetry in diverse dimensions d. By analyzing the
thermodynamics of the dilaton-gravity system we find that scale invariance is
broken at low temperatures, as shown by a nontrivial hyperscaling violation
exponent in the infrared; increasing the temperature we recover scale symmetry
in a d dependent way: while for d=2+1 a phase transition is found, for d=3+1
the transition is rather a crossover. This is the expected behavior of QCD
where the number of colors N_c equals three (although in our holographic
calculations N_c goes to infinity). When the U(1) is preserved and at low
temperatures, the system is insulating for arbitrary d if the dilaton is
appropriately coupled to the gauge field; for other couplings we also find a
linear in temperature resistivity. We then determine the prediction of these
models for several quantities in the superconducting phase: the DC and AC
conductivity, the gap for charged excitations, the superfluid density, the
vortex profiles, the coherence length, the penetration depth and the critical
magnetic fields. We show that at low temperatures some of these quantities
differ qualitatively compared with the corresponding models without the
dilaton, although the superconductor is robustly of Type II. The ratio of the
gap over the critical temperature of the superconductor is studied in detail
varying d and the couplings of the dilaton and then compared with the BCS
value. A holographic renormalization is required in d>2+1 to compute some
quantities (such as the AC conductivity and the penetration depth) and we
explain in detail how to perform it.

categories: hep-th cond-mat.str-el cond-mat.supr-con gr-qc


title:
Periodic magnetization structures generated by transverse spin-current
  in magnetic nanowires

abstract:
  Magnetization behavior of long nanowires with square cross-section under
influence of strong perpendicular spin-polarized current is studied
theoretically. The study is based on Landau-Lifshitz-Slonczewski phenomenology.
In the no current case the wire is magnetized uniformly along its axis. For
small currents the wire magnetization remains uniform but it inclines with
respect to the wire axis within the plane perpendicular to the current
direction. With the current increasing the inclination angle increases up to
the maximum value $\pi/4$. Further current increase leads either to saturation
or to stable periodic multidomain structure depending on the wire thickness.
For thick wires a hysteresis is observed in the saturation process under the
action of current. All critical parameters of the current induced magnetization
behavior are determined theoretically. The study is carried out both
analytically and using micromagnetic simulations.


title: Compositional Quantum Logic

abstract:
  Quantum logic aims to capture essential quantum mechanical structure in
order-theoretic terms. The Achilles' heel of quantum logic is the absence of a
canonical description of composite systems, given descriptions of their
components. We introduce a framework in which order-theoretic structure comes
with a primitive composition operation. The order is extracted from a
generalisation of C*-algebra that applies to arbitrary dagger symmetric
monoidal categories, which also provide the composition operation. In fact, our
construction is entirely compositional, without any additional assumptions on
limits or enrichment. Interpreted in the category of finite-dimensional Hilbert
spaces, it yields the projection lattices of arbitrary finite-dimensional
C*-algebras. Interestingly, there are models that falsify standardly assumed
correspondences, most notably the correspondence between noncommutativity of
the algebra and nondistributivity of the order.


title: Turbulence-induced disc formation in strongly magnetised cloud cores

abstract:
  We present collapse simulations of strongly magnetised, turbulent molecular
cloud cores with masses ranging from 2.6 to 1000 M_sun in order to study the
influence of the initial conditions on the turbulence-induced disc formation
mechanism proposed recently by Seifried et al. 2012. We find that Keplerian
discs are formed in all cases independently of the core mass, the strength of
turbulence, or the presence of global rotation. The discs appear within a few
kyr after the formation of the protostar, are 50 - 150 AU in size, and have
masses between 0.05 and a few 0.1 M_sun. During the formation of the discs the
mass-to-flux ratio stays well below the critical value of 10 for Keplerian disc
formation. Hence, flux-loss alone cannot explain the formation of Keplerian
discs. The formation of rotationally supported discs at such early phases is
rather due to the disordered magnetic field structure and due to turbulent
motions in the surroundings of the discs, two effects lowering the classical
magnetic braking efficiency. Binary systems occurring in the discs are mainly
formed via the disc capturing mechanism rather than via disc fragmentation,
which is largely suppressed by the presence of magnetic fields.


title: Remark On Two Results due to Ramanujan on Hypergeometric Series

abstract:
  During the course of verifying the results of Ramanujan on hypergeometric
series, Berndt in his notebooks, Part II mentioned corrected forms of two of
the Ramanujan's results.
  The aim of this short research note is to point out that one of the results
obtained by Ramanujan is correct (and not of Berndt's result) and the second
result (which is slightly differ from Ramanujan's result and Berndt's result)
is given here in corrected form.


title:
Local thermodynamics and the generalized Gibbs-Duhem equation in systems
  with long-range interactions

abstract:
  The local thermodynamics of a system with long-range interactions in d
dimensions is studied using the mean-field approximation. Long-range
interactions are introduced through pair interaction potentials that decay as a
power law in the interparticle distance. We compute the local entropy,
Helmholtz free energy, and grand potential per particle in the microcanonical,
canonical, and grand canonical ensembles, respectively. From the local entropy
per particle we obtain the local equation of state of the system by using the
condition of local thermodynamic equilibrium. This local equation of state has
the form of the ideal gas equation of state, but with the density depending on
the potential characterizing long-range interactions. By volume integration of
the relation between the different thermodynamic potentials at the local level,
we find the corresponding equation satisfied by the potentials at the global
level. It is shown that the potential energy enters as a thermodynamic variable
that modifies the global thermodynamic potentials. As a result, we find a
generalized Gibbs-Duhem equation that relates the potential energy to the
temperature, pressure, and chemical potential. For the marginal case where the
power of the decaying interaction potential is equal to the dimension of the
space, the usual Gibbs-Duhem equation is recovered. As examples of the
application of this equation, we consider spatially uniform interaction
potentials and the self-gravitating gas. We also point out a close relationship
with the thermodynamics of small systems.


title:
Inverse simulated annealing for the determination of amorphous
  structures

abstract:
  We present a new and efficient optimization method to determine the structure
of disordered systems in agreement with available experimental data. Our
approach permits the application of accurate electronic structure calculations
within the structure optimization. The new technique is demonstrated within
density functional theory by the calculation of a model of amorphous carbon.

categories: cond-mat.mtrl-sci cond-mat.dis-nn cond-mat.stat-mech physics.chem-ph physics.comp-ph


title:
CdWO4 crystal scintillators from enriched isotopes for double beta decay
  experiments

abstract:
  Cadmium tungstate crystal scintillators enriched in 106Cd and 116Cd were
developed. The produced scintillators exhibit good optical and scintillation
properties, and a low level of radioactive contamination. Experiments to search
for double beta decay of 106Cd and 116Cd are in progress at the Gran Sasso
National Laboratories of the INFN (Italy). Prospects to further improve the
radiopurity of the detectors by recrystallization are discussed.


title: Anti-Invariant Riemannian Submersions from Sasakian Manifolds

abstract:
  We introduce anti-invariant Riemannian submersions from Sasakian manifolds
onto Riemannian manifolds. We survey main results of anti-invariant Riemannian
submersions defined on Sasakian manifolds. We investigate necessary and
sufficient condition for an anti-invariant Riemannian submersion to be totally
geodesic and harmonic. We give examples of anti-invariant submersions such that
characteristic vector field {\xi} is vertical or horizontal.


title: New Important Developments in Small Area Estimation

abstract:
  The problem of small area estimation (SAE) is how to produce reliable
estimates of characteristics of interest such as means, counts, quantiles,
etc., for areas or domains for which only small samples or no samples are
available, and how to assess their precision. The purpose of this paper is to
review and discuss some of the new important developments in small area
estimation methods. Rao [Small Area Estimation (2003)] wrote a very
comprehensive book, which covers all the main developments in this topic until
that time. A few review papers have been written after 2003, but they are
limited in scope. Hence, the focus of this review is on new developments in the
last 7-8 years, but to make the review more self-contained, I also mention
shortly some of the older developments. The review covers both design-based and
model-dependent methods, with the latter methods further classified into
frequentist and Bayesian methods. The style of the paper is similar to the
style of my previous review on SAE published in 2002, explaining the new
problems investigated and describing the proposed solutions, but without
dwelling on theoretical details, which can be found in the original articles. I
hope that this paper will be useful both to researchers who like to learn more
on the research carried out in SAE and to practitioners who might be interested
in the application of the new methods.


title:
Measurement of the Inclusive NuMu Charged Current Cross Section on
  Carbon in the Near Detector of the T2K Experiment

abstract:
  T2K has performed the first measurement of \nu{\mu} inclusive charged current
interactions on carbon at neutrino energies of ~1 GeV where the measurement is
reported as a flux-averaged double differential cross section in muon momentum
and angle. The flux is predicted by the beam Monte Carlo and external data,
including the results from the NA61/SHINE experiment. The data used for this
measurement were taken in 2010 and 2011, with a total of 10.8 x 10^{19}
protons-on-target. The analysis is performed on 4485 inclusive charged current
interaction candidates selected in the most upstream fine-grained scintillator
detector of the near detector. The flux-averaged total cross section is
<\sigma_CC>_\phi =(6.91 +/- 0.13 (stat) +/- 0.84 (syst)) x10^{-39} cm^2/nucleon
for a mean neutrino energy of 0.85 GeV.


title: Dynamical transitions in Markovian exciton transport

abstract:
  The large deviation theory has recently been applied to open quantum systems
to uncover dynamical crossovers in the space of quantum trajectories associated
to Markovian evolutions. Such dynamical crossovers are characterized by
qualitative changes in the fluctuations of rare quantum jump trajectories, and
have been observed in the statistics of coherently driven quantum systems. In
this article we investigate the counting statistics of rare quantum
trajectories of an undriven system undergoing a pure relaxation process,
namely, Markovian exciton transport. We find that dynamical crossovers occur in
systems with a minimum of three interacting molecules, and are strongly
activated by exciton delocalization and interference. Our results illustrate
how quantum features of the underlying system Hamiltonian can influence the
statistical properties of energy transfer processes in a non-trivial manner.


title:
A quantitative log-Sobolev inequality for a two parameter family of
  functions

abstract:
  We prove a sharp, dimension-free stability result for the classical
logarithmic Sobolev inequality for a two parameter family of functions. Roughly
speaking, our family consists of a certain class of log $C^{1,1}$ functions.
Moreover, we show how to enlarge this space at the expense of the dimensionless
constant and the sharp exponent. As an application we obtain new bounds on the
entropy.


title: Crooked surfaces and anti-de Sitter geometry

abstract:
  Crooked planes were defined by Drumm to bound fundamental polyhedra in
Minkowski space for Margulis spacetimes. They were extended by Frances to
closed polyhedral surfaces in the conformal compactification of Minkowski space
(Einstein space) which we call crooked surfaces. The conformal model of anti-de
Sitter space is the interior of the quotient of Einstein space by an involution
fixing an Einstein plane. The purpose of this note is to show that the crooked
planes defined in anti-de Sitter space recently by Danciger-Gu\'eritaud-Kassel
lift to restrictions of crooked surfaces in Einstein space which are adapted
under the involution of Einstein space defining anti-de Sitter space.


title:
Conditions for observable bi and tri-spectra in two-field slow-roll
  inflation

abstract:
  We find constraints on inflationary dynamics that yield a large local
bispectrum and/or trispectrum during two-field slow-roll inflation. This leads
to simple relations between the non-Gaussianity parameters, simplifying the
Suyama-Yamaguchi inequality and also producing a new result between the
trispectrum parameters tNL and gNL.


title:
A 10,000 star spectroscopic survey of the thick disk-halo interface :
  Phase-space sub-structure in the thick disk

abstract:
  We analyse a 10,000 star spectroscopic survey, focused on Galactic thick disk
stars typically 2-5 kpc from the Sun, carried out using the AAOmega
Spectrograph on the AAT. We develop methods for completeness-correction of the
survey based on SDSS photometry, and we derive star distances using an improved
isochrone-fitting method with accuracies better than 10%. We determine the
large-scale kinematic (Vphi=172 km/s and sigma(phi,r,z) = (49,51,40) km/s), and
abundance properties of the thick disk, showing these representative values are
a fair description within about 3 kpc of the sun, and in the range 1-3 kpc from
the Galactic Plane. We identify a substantial overdensity in lines of sight
towards the inner Galaxy, with metallicity [Fe/H] -1 dex, and higher line of
sight velocities than the thick disk, localised along the direction
(l,b)=(48,-26). This overdensity appears to be towards, but closer than, the
known Hercules-Aquila halo overdensity and may be related to the
Humphreys-Larsen inner galaxy thick disk asymmetry.


title: On the detectability of eccentric binary pulsars

abstract:
  By generalizing earlier work of Johnston & Kulkarni, we present a detailed
description of the reduction in the signal-to-noise ratio for observations of
binary pulsars. We present analytical expressions, and provide software, to
calculate the sensitivity reduction for orbits of arbitrary eccentricity. We
find that this reduction can be quite significant, especially in the case of a
massive companion like another neutron star or a black hole. On the other hand,
the reduction is less for highly eccentric orbits. We also demonstrate that
this loss of sensitivity can be recovered by employing "acceleration search" or
"acceleration-jerk search" algorithms.


title:
Group classification of variable coefficient quasilinear
  reaction-diffusion equations

abstract:
  The group classification of variable coefficient quasilinear
reaction-diffusion equations $u_t=u_{xx}+h(x)B(u)$ is carried out exhaustively.
This became possible due to usage of a conditional equivalence group found in
the course of the study of admissible point transformation within the class.


title: Stacking from Tags: Clustering Bookmarks around a Theme

abstract:
  Since very recently, users on the social bookmarking service Delicious can
stack web pages in addition to tagging them. Stacking enables users to group
web pages around specific themes with the aim of recommending to others.
However, users still stack a small subset of what they tag, and thus many web
pages remain unstacked. This paper presents early research towards
automatically clustering web pages from tags to find stacks and extend
recommendations.


title: Hadronic Screening in Improved Taste

abstract:
  We present our results on meson and nucleon screening masses in finite
temperature two flavour QCD using smeared staggered valence quarks and
staggered thin-link sea quarks with different lattice spacings and quark
masses. We investigate optimization of smearing by observing its effects on the
infrared (IR) and ultraviolet (UV) components of gluon and quark fields. The
application of smearing to screening at finite temperature also provides a
transparent window into the mechanism of the interplay of smearing and chiral
symmetry. The improved hadronic operators show that above the finite
temperature cross over, T_c, screening masses are consistent with weak-coupling
predictions. There is also evidence for a rapid opening up of a spectral gap of
the Dirac operator immediately above T_c.


title: NoN analyticity of Hanle effect at zero magnetic field in a quantum dot

abstract:
  Non analytic behaviour of Hanle effect in InGaAs quantum dots is described in
terms of a simple 4-level model. Despite simplicity the model makes it possible
to explain the observed fracture of Hanle curve at zero magnetic field and
obtain quantitative agreement with the experiment.


title: Volumes of polytopes in spaces of constant curvature

abstract:
  We overview the volume calculations for polyhedra in Euclidean, spherical and
hyperbolic spaces. We prove the Sforza formula for the volume of an arbitrary
tetrahedron in $H^3$ and $S^3$. We also present some results, which provide a
solution for Seidel problem on the volume of non-Euclidean tetrahedron.
Finally, we consider a convex hyperbolic quadrilateral inscribed in a circle,
horocycle or one branch of equidistant curve. This is a natural hyperbolic
analog of the cyclic quadrilateral in the Euclidean plane. We find a few
versions of the Brahmagupta formula for the area of such quadrilateral. We also
present a formula for the area of a hyperbolic trapezoid.


title:
Angular distribution of thick-target bremsstrahlung produced by
  electrons with initial energies ranging from 10 to 20-keV incident on Ag

abstract:
  Experimental results are presented comparing the intensity of the
bremsstrahlung produced by electrons with initial energies ranging from 10 to
20-keV incident on a thick Ag target, measured at forward angles in the range 0
degrees to 55 degrees. When the data are corrected for attenuation due to
photon absorption within the target, the results indicate that the detected
radiation is distributed anisotropically only at photon energies, k, that are
approximately equal to the initial energy of the incident electrons, Eo. The
results of our experiments suggest that as k /Eo goes to 0, the detected
radiation becomes essentially isotropic due primarily to the scattering of
electrons within the target. A comparison to the theoretical work of Kissel et
al. [At. Data Nucl. Data Tables 28, 381 (1983)] suggests that the angular
distribution of bremsstrahlung emitted by electrons incident on thick targets
is similar to the angular distribution of bremsstrahlung emitted by electrons
incident on free-atom targets only when k /Eo is approximately equal to 1. The
experimental data are also in approximate agreement with the angular
distribution predictions of the Monte Carlo program, PENELOPE.


title: Sheffer sequences of polynomials and their applications

abstract:
  In this paper, we investigate some properties of several Sheffer sequences of
several polynomials arising from umbral calculus. From our investigation, we
can derive many interesting identities of several polynomials


title:
Structure Discovery in Nonparametric Regression through Compositional
  Kernel Search

abstract:
  Despite its importance, choosing the structural form of the kernel in
nonparametric regression remains a black art. We define a space of kernel
structures which are built compositionally by adding and multiplying a small
number of base kernels. We present a method for searching over this space of
structures which mirrors the scientific discovery process. The learned
structures can often decompose functions into interpretable components and
enable long-range extrapolation on time-series datasets. Our structure search
method outperforms many widely used kernels and kernel combination methods on a
variety of prediction tasks.


title: On the Generalized Bloch Precession Equations

abstract:
  The Bloch equations, which describe spin precession and relaxation in
external magnetic fields, can be generalized to include the evolution of
polarization tensors of various ranks in arbitrary multipole fields. The
derivation of these generalized Bloch equations can be considerably simplified
by using a particular bra-ket notation for irreducible tensors.


title: Quantum Entropic Ambiguities: Ethylene

abstract:
  In a quantum system, there may be many density matrices associated with a
state on an algebra of observables. For each density matrix, one can compute
its entropy. These are in general different. Therefore one reaches the
remarkable possibility that there may be many entropies for a given state
[Private communication from R. Sorkin]. This ambiguity in entropy can often be
traced to a gauge symmetry emergent from the non-trivial topological character
of the configuration space of the underlying system. It can also happen in
finite-dimensional matrix models. In the present work, we discuss this entropy
ambiguity and its consequences for an ethylene molecule. This is a very simple
and well-known system where these notions can be put to tests. Besides its
intrinsic conceptual interest, the simplicity of this model can serve as an
introduction to a similar discussion of systems such as coloured monopoles and
the breaking of colour symmetry.

categories: hep-th cond-mat.stat-mech math-ph math.MP physics.chem-ph quant-ph


title:
Doping Induced Spin State Transition in LaCoO3: Dynamical Mean-Field
  Study

abstract:
  Hole and electron doped LaCoO3 is studied using dynamical mean-field theory.
The one-particle spectra are analyzed and compared to the available
experimental data, in particular the x-ray absorption spectra. Analyzing the
temporal spin-spin correlation functions we find the atomic intermediate spin
state is not important for the observed Curie-Weiss susceptibility. Contrary to
the commonly held view about the roles played by the t2g and eg electrons we
find narrow quasiparticle bands of t2g character crossing the Fermi level
accompanied by strongly damped eg excitations.


title:
Recovery of fluctuation spectrum evolution from tomographic shear
  spectra

abstract:
  Forthcoming large angle surveys are planned to obtain high precision
tomographic shear data. In principle, they will allow us to recover the spectra
of matter density fluctuation, at various redshift, through the inversion of
the expressions yielding shear from fluctuation spectra. This was discussed in
previous work, where SVD techniques for matrix inversion were also shown to be
the optimal tool to this aim. Here we show the significant improvements
obtainable by using a 7 bin tomography, as allowed by future Euclid data, as
well as the question of error propagation from shear to fluctuation spectra. We
find that the technique is a promising tool, namely for the analysis of baryon
physics throug high-l shear spectra and to test the consistency between
expansion rate and fluctuation growth.


title:
Finite-temperature Gutzwiller approximation and the phase diagram of a
  toy-model for V2O3

abstract:
  We exploit exact inequalities that refer to the entropy of a distribution to
derive a simple variational principle at finite temperature for trial density
matrices of Gutzwiller and Jastrow type. We use the result to extend at finite
temperature the Gutzwiller approximation, which we apply to study a two-orbital
model that we believe captures some essential features of V$_2$O$_3$. We indeed
find that the phase diagram of the model bears many similarities to that of
real vanadium sesquioxide. In addition, we show that in a Bethe lattice, where
the finite temperature Gutzwiller approximation provides a rigorous upper bound
of the actual free energy, the results compare well with the exact phase
diagram obtained by the dynamical mean field theory.


title: Graphical Models for Preference and Utility

abstract:
  Probabilistic independence can dramatically simplify the task of eliciting,
representing, and computing with probabilities in large domains. A key
technique in achieving these benefits is the idea of graphical modeling. We
survey existing notions of independence for utility functions in a
multi-attribute space, and suggest that these can be used to achieve similar
advantages. Our new results concern conditional additive independence, which we
show always has a perfect representation as separation in an undirected graph
(a Markov network). Conditional additive independencies entail a particular
functional for the utility function that is analogous to a product
decomposition of a probability function, and confers analogous benefits. This
functional form has been utilized in the Bayesian network and influence diagram
literature, but generally without an explanation in terms of independence. The
functional form yields a decomposition of the utility function that can greatly
speed up expected utility calculations, particularly when the utility graph has
a similar topology to the probabilistic network being used.


title: Counterfactuals and Policy Analysis in Structural Models

abstract:
  Evaluation of counterfactual queries (e.g., "If A were true, would C have
been true?") is important to fault diagnosis, planning, determination of
liability, and policy analysis. We present a method of revaluating
counterfactuals when the underlying causal model is represented by structural
models - a nonlinear generalization of the simultaneous equations models
commonly used in econometrics and social sciences. This new method provides a
coherent means for evaluating policies involving the control of variables
which, prior to enacting the policy were influenced by other variables in the
system.


title: Belief Functions and Default Reasoning

abstract:
  We present a new approach to dealing with default information based on the
theory of belief functions. Our semantic structures, inspired by Adams'
epsilon-semantics, are epsilon-belief assignments, where values committed to
focal elements are either close to 0 or close to 1. We define two systems based
on these structures, and relate them to other non-monotonic systems presented
in the literature. We show that our second system correctly addresses the
well-known problems of specificity, irrelevance, blocking of inheritance,
ambiguity, and redundancy.


title: An Algebraic Semantics for Possibilistic Logic

abstract:
  The first contribution of this paper is the presentation of a Pavelka - like
formulation of possibilistic logic in which the language is naturally enriched
by two connectives which represent negation (eg) and a new type of conjunction
(otimes). The space of truth values for this logic is the lattice of
possibility functions, that, from an algebraic point of view, forms a quantal.
A second contribution comes from the understanding of the new conjunction as
the combination of tokens of information coming from different sources, which
makes our language "dynamic". A Gentzen calculus is presented, which is proved
sound and complete with respect to the given semantics. The problem of truth
functionality is discussed in this context.


title: Automating Computer Bottleneck Detection with Belief Nets

abstract:
  We describe an application of belief networks to the diagnosis of bottlenecks
in computer systems. The technique relies on a high-level functional model of
the interaction between application workloads, the Windows NT operating system,
and system hardware. Given a workload description, the model predicts the
values of observable system counters available from the Windows NT performance
monitoring tool. Uncertainty in workloads, predictions, and counter values are
characterized with Gaussian distributions. During diagnostic inference, we use
observed performance monitor values to find the most probable assignment to the
workload parameters. In this paper we provide some background on automated
bottleneck detection, describe the structure of the system model, and discuss
empirical procedures for model calibration and verification. Part of the
calibration process includes generating a dataset to estimate a multivariate
Gaussian error model. Initial results in diagnosing bottlenecks are presented.


title: Chain Graphs for Learning

abstract:
  Chain graphs combine directed and undirected graphs and their underlying
mathematics combines properties of the two. This paper gives a simplified
definition of chain graphs based on a hierarchical combination of Bayesian
(directed) and Markov (undirected) networks. Examples of a chain graph are
multivariate feed-forward networks, clustering with conditional interaction
between variables, and forms of Bayes classifiers. Chain graphs are then
extended using the notation of plates so that samples and data analysis
problems can be represented in a graphical model as well. Implications for
learning are discussed in the conclusion.


title: Error Estimation in Approximate Bayesian Belief Network Inference

abstract:
  We can perform inference in Bayesian belief networks by enumerating
instantiations with high probability thus approximating the marginals. In this
paper, we present a method for determining the fraction of instantiations that
has to be considered such that the absolute error in the marginals does not
exceed a predefined value. The method is based on extreme value theory.
Essentially, the proposed method uses the reversed generalized Pareto
distribution to model probabilities of instantiations below a given threshold.
Based on this distribution, an estimate of the maximal absolute error if
instantiations with probability smaller than u are disregarded can be made.


title: Generating the Structure of a Fuzzy Rule under Uncertainty

abstract:
  The aim of this paper is to present a method for identifying the structure of
a rule in a fuzzy model. For this purpose, an ATMS shall be used (Zurita 1994).
An algorithm obtaining the identification of the structure will be suggested
(Castro 1995). The minimal structure of the rule (with respect to the number of
variables that must appear in the rule) will be found by this algorithm.
Furthermore, the identification parameters shall be obtained simultaneously.
The proposed method shall be applied for classification to an example. The {em
Iris Plant Database} shall be learnt for all three kinds of plants.


title:
Practical Model-Based Diagnosis with Qualitative Possibilistic
  Uncertainty

abstract:
  An approach to fault isolation that exploits vastly incomplete models is
presented. It relies on separate descriptions of each component behavior,
together with the links between them, which enables focusing of the reasoning
to the relevant part of the system. As normal observations do not need
explanation, the behavior of the components is limited to anomaly propagation.
Diagnostic solutions are disorders (fault modes or abnormal signatures) that
are consistent with the observations, as well as abductive explanations. An
ordinal representation of uncertainty based on possibility theory provides a
simple exception-tolerant description of the component behaviors. We can for
instance distinguish between effects that are more or less certainly present
(or absent) and effects that are more or less certainly present (or absent)
when a given anomaly is present. A realistic example illustrates the benefits
of this approach.


title: Decision Flexibility

abstract:
  The development of new methods and representations for temporal
decision-making requires a principled basis for characterizing and measuring
the flexibility of decision strategies in the face of uncertainty. Our goal in
this paper is to provide a framework - not a theory - for observing how
decision policies behave in the face of informational perturbations, to gain
clues as to how they might behave in the face of unanticipated, possibly
unarticulated uncertainties. To this end, we find it beneficial to distinguish
between two types of uncertainty: "Small World" and "Large World" uncertainty.
The first type can be resolved by posing an unambiguous question to a
"clairvoyant," and is anchored on some well-defined aspect of a decision frame.
The second type is more troublesome, yet it is often of greater interest when
we address the issue of flexibility; this type of uncertainty can be resolved
only by consulting a "psychic." We next observe that one approach to
flexibility used in the economics literature is already implicitly accounted
for in the Maximum Expected Utility (MEU) principle from decision theory.
Though simple, the observation establishes the context for a more illuminating
notion of flexibility, what we term flexibility with respect to information
revelation. We show how to perform flexibility analysis of a static (i.e.,
single period) decision problem using a simple example, and we observe that the
most flexible alternative thus identified is not necessarily the MEU
alternative. We extend our analysis for a dynamic (i.e., multi-period) model,
and we demonstrate how to calculate the value of flexibility for decision
strategies that allow downstream revision of an upstream commitment decision.


title:
A Transformational Characterization of Equivalent Bayesian Network
  Structures

abstract:
  We present a simple characterization of equivalent Bayesian network
structures based on local transformations. The significance of the
characterization is twofold. First, we are able to easily prove several new
invariant properties of theoretical interest for equivalent structures. Second,
we use the characterization to derive an efficient algorithm that identifies
all of the compelled edges in a structure. Compelled edge identification is of
particular importance for learning Bayesian network structures from data
because these edges indicate causal relationships when certain assumptions
hold.


title:
Conditioning Methods for Exact and Approximate Inference in Causal
  Networks

abstract:
  We present two algorithms for exact and approximate inference in causal
networks. The first algorithm, dynamic conditioning, is a refinement of cutset
conditioning that has linear complexity on some networks for which cutset
conditioning is exponential. The second algorithm, B-conditioning, is an
algorithm for approximate inference that allows one to trade-off the quality of
approximations with the computation time. We also present some experimental
results illustrating the properties of the proposed algorithms.


title: Independence Concepts for Convex Sets of Probabilities

abstract:
  In this paper we study different concepts of independence for convex sets of
probabilities. There will be two basic ideas for independence. The first is
irrelevance. Two variables are independent when a change on the knowledge about
one variable does not affect the other. The second one is factorization. Two
variables are independent when the joint convex set of probabilities can be
decomposed on the product of marginal convex sets. In the case of the Theory of
Probability, these two starting points give rise to the same definition. In the
case of convex sets of probabilities, the resulting concepts will be strongly
related, but they will not be equivalent. As application of the concept of
independence, we shall consider the problem of building a global convex set
from marginal convex sets of probabilities.


title: Clustering Without (Thinking About) Triangulation

abstract:
  The undirected technique for evaluating belief networks [Jensen, et.al.,
1990, Lauritzen and Spiegelhalter, 1988] requires clustering the nodes in the
network into a junction tree. In the traditional view, the junction tree is
constructed from the cliques of the moralized and triangulated belief network:
triangulation is taken to be the primitive concept, the goal towards which any
clustering algorithm (e.g. node elimination) is directed. In this paper, we
present an alternative conception of clustering, in which clusters and the
junction tree property play the role of primitives: given a graph (not a tree)
of clusters which obey (a modified version of) the junction tree property, we
transform this graph until we have obtained a tree. There are several
advantages to this approach: it is much clearer and easier to understand, which
is important for humans who are constructing belief networks; it admits a wider
range of heuristics which may enable more efficient or superior clustering
algorithms; and it serves as the natural basis for an incremental clustering
scheme, which we describe.


title:
Implementation of Continuous Bayesian Networks Using Sums of Weighted
  Gaussians

abstract:
  Bayesian networks provide a method of representing conditional independence
between random variables and computing the probability distributions associated
with these random variables. In this paper, we extend Bayesian network
structures to compute probability density functions for continuous random
variables. We make this extension by approximating prior and conditional
densities using sums of weighted Gaussian distributions and then finding the
propagation rules for updating the densities in terms of these weights. We
present a simple example that illustrates the Bayesian network for continuous
variables; this example shows the effect of the network structure and
approximation errors on the computation of densities for variables in the
network.