title:
Onset of cavity deformation upon subsonic motion of a projectile in a
  fluid complex plasma

abstract:
  We study deformation of a cavity around a large projectile moving with
subsonic velocity in the cloud of small dust particles. To solve this problem,
we employ the Navier--Stokes equation for a compressible fluid with due regard
for friction between dust particles and atoms of neutral gas. The solutions
shows that due to friction, the pressure of dust cloud at the boundary of the
cavity behind the projectile can become negative, which entails formation of a
microscopic void free from dust particles -- the cavity deformation.
Corresponding threshold velocity is calculated, which is found to decrease with
increasing cavity size. Measurement of such velocity makes it possible to
estimate the static pressure inside the dust cloud.


title: Wronskians and linear independence

abstract:
  We give a new and simple proof of the fact that a finite family of analytic
functions has a zero Wronskian only if it is linearly dependent.


title: An Upper Bound on the Capacity of non-Binary Deletion Channels

abstract:
  We derive an upper bound on the capacity of non-binary deletion channels.
Although binary deletion channels have received significant attention over the
years, and many upper and lower bounds on their capacity have been derived,
such studies for the non-binary case are largely missing. The state of the art
is the following: as a trivial upper bound, capacity of an erasure channel with
the same input alphabet as the deletion channel can be used, and as a lower
bound the results by Diggavi and Grossglauser are available. In this paper, we
derive the first non-trivial non-binary deletion channel capacity upper bound
and reduce the gap with the existing achievable rates. To derive the results we
first prove an inequality between the capacity of a 2K-ary deletion channel
with deletion probability $d$, denoted by $C_{2K}(d)$, and the capacity of the
binary deletion channel with the same deletion probability, $C_2(d)$, that is,
$C_{2K}(d)\leq C_2(d)+(1-d)\log(K)$. Then by employing some existing upper
bounds on the capacity of the binary deletion channel, we obtain upper bounds
on the capacity of the 2K-ary deletion channel. We illustrate via examples the
use of the new bounds and discuss their asymptotic behavior as $d \rightarrow
0$.


title:
Weighted Sum Rate Maximization for Downlink OFDMA with Subcarrier-pair
  based Opportunistic DF Relaying

abstract:
  This paper addresses a weighted sum rate (WSR) maximization problem for
downlink OFDMA aided by a decode-and-forward (DF) relay under a total power
constraint. A novel subcarrier-pair based opportunistic DF relaying protocol is
proposed. Specifically, user message bits are transmitted in two time slots. A
subcarrier in the first slot can be paired with a subcarrier in the second slot
for the DF relay-aided transmission to a user. In particular, the source and
the relay can transmit simultaneously to implement beamforming at the
subcarrier in the second slot. Each unpaired subcarrier in either the first or
second slot is used for the source's direct transmission to a user. A benchmark
protocol, same as the proposed one except that the transmit beamforming is not
used for the relay-aided transmission, is also considered. For each protocol, a
polynomial-complexity algorithm is developed to find at least an approximately
optimum resource allocation (RA), by using continuous relaxation, the dual
method, and Hungarian algorithm. Instrumental to the algorithm design is an
elegant definition of optimization variables, motivated by the idea of
regarding the unpaired subcarriers as virtual subcarrier pairs in the direct
transmission mode. The effectiveness of the RA algorithm and the impact of
relay position and total power on the protocols' performance are illustrated by
numerical experiments. The proposed protocol always leads to a maximum WSR
equal to or greater than that for the benchmark one, and the performance gain
of using the proposed one is significant especially when the relay is in close
proximity to the source and the total power is low. Theoretical analysis is
presented to interpret these observations.


title:
Growth of High-Mobility Bi2Te2Se Nanoplatelets on hBN Sheets by van der
  Waals Epitaxy

abstract:
  The electrical detection of the surface states of topological insulators is
strongly impeded by the interference of bulk conduction, which commonly arises
due to pronounced doping associated with the formation of lattice defects. As
exemplified by the topological insulator Bi2Te2Se, we show that via van der
Waals epitaxial growth on thin hBN substrates the structural quality of such
nanoplatelets can be substantially improved. The surface state carrier mobility
of nanoplatelets on hBN is increased by a factor of about 3 compared to
platelets on conventional Si/SiOx substrates, which enables the observation of
well-developed Shubnikov-de Haas oscillations. We furthermore demonstrate the
possibility to effectively tune the Fermi level position in the films with the
aid of a back gate.


title: A Geometric Approach to Defining Multiplication

abstract:
  In this paper we will do the following: (1) show how to geometrically define
multiplication, using only basic plane geometry, independently of area and any
notion of similar triangles; (2) prove all the properties of multiplication
using only the axioms of plane geometry and the geometric definition of
multiplication; (3) explain how the geometric definition of multiplication
relates to the area of a right triangle (or rectangle); and (4) explain how by
using only the geometric definition of multiplication and the Pythagorean
Theorem one can prove that two triangles have the same angles if and only if
the lengths of their corresponding sides are proportional. The interesting and
surprising thing, from a pedagogical and/or mathematical point of view, is that
all of these results can be proven using only simple geometry (no limits
needed). As we shall see, parallel lines in our geometric approach will play a
role similar to limits in the standard algebraic approach. We believe that both
prospective K-12 mathematics teachers and STEM students could especially
benefit by being exposed to the material in this paper before graduating from
university.


title:
On conditions of negativity of friction resistance for non-stationary
  modes of blood flow and possible mechanism of affecting of environmental
  factors on energy effectiveness of cardio-vascular system functioning

abstract:
  It is shown that initiated by action of molecular viscosity impulse flow,
directed usually from the moving fluid to limiting it solid surface, can, under
certain conditions, turn to zero and get negative values in the case of
non-stationary flow caused by alternating in time longitudinal (along the pipe
axis) pressure gradient. It is noted that this non-equilibrium mechanism of
negative friction resistance in the similar case of pulsating blood flow in the
blood vessels, in addition to the stable to turbulent disturbances swirled
blood flow structure providing, can also constitute hydro-mechanical basis of
the observed but not explained yet paradoxically high energy effectiveness of
the normal functioning of the cardio-vascular system (CVS). We consider
respective mechanism of affecting on the stability of the normal work of CVS by
environmental variable factors using shifting of hydro-dynamic mode with
negative resistance realization range boundaries and variation of linear
hydro-dynamic instability leading to the structurally stable swirled blood flow
organization.


title:
Sum of squared logarithms - An inequality relating positive definite
  matrices and their matrix logarithm

abstract:
  Let y1, y2, y3, a1, a2, a3 > 0 be such that y1 y2 y3 = a1 a2 a3 and y1 + y2 +
y3 >= a1 + a2 + a3, y1 y2 + y2 y3 + y1 y3 >= a1 a2 + a2 a3 + a1 a3.
  Then the following inequality holds (log y1)^2 + (log y2)^2 + (log y3)^2 >=
(log a1)^2 + (log a2)^2 + (log a3)^2.
  This can also be stated in terms of real positive definite 3x3-matrices P1,
P2: If their determinants are equal det P1 = det P2, then tr P1 >= tr P2 and tr
Cof P1 >= tr Cof P2 implies norm(log P1) >= norm(log P2), where log is the
principal matrix logarithm and norm(P) denotes the Frobenius matrix norm.
Applications in matrix analysis and nonlinear elasticity are indicated.


title:
Explicit formulas for determinantal representations of the Drazin
  inverse solutions of some matrix and differential matrix equations

abstract:
  The Drazin inverse solutions of the matrix equations ${\rm {\bf A}}{\rm {\bf
X}} = {\rm {\bf B}}$, ${\rm {\bf X}}{\rm {\bf A}} = {\rm {\bf B}}$ and ${\rm
{\bf A}}{\rm {\bf X}}{\rm {\bf B}} ={\rm {\bf D}} $ are considered in this
paper. We use both the determinantal representations of the Drazin inverse
obtained earlier by the author and in the paper. We get analogs of the Cramer
rule for the Drazin inverse solutions of these matrix equations and using their
for determinantal representations of solutions of some differential matrix
equations, ${\bf X}'+ {\bf A}{\bf X}={\bf B}$ and ${\bf X}'+{\bf X}{\bf A}={\bf
B}$, where the matrix ${\bf A}$ is singular.


title: Fibonacci Numbers, Golden Section and Applications

abstract:
  In this thesis we examined mathematical properties of Fibonacci numbers and
applications of this numbers in the nature,geometry and economy.We obtained
Golden section and proved some mathematical identities using Golden section.
Infinity of the prime numbers proved by using properties of Fibonacci numbers.
Encounterings with Fibonacci numbers in the nature are examined with details.
Also examples are given for relation about Fibonacci numbers and stock exchange
and these are examined.


title: Estimating the covariance of random matrices

abstract:
  We extend to the matrix setting a recent result of Srivastava-Vershynin about
estimating the covariance matrix of a random vector. The result can be in-
terpreted as a quantified version of the law of large numbers for positive
semi-definite matrices which verify some regularity assumption. Beside giving
examples, we dis- cuss the notion of log-concave matrices and give estimates on
the smallest and largest eigenvalues of a sum of such matrices.


title: Searching for Charged Higgs Boson in Polarized Top Quark

abstract:
  The charged Higgs boson is quite common in many new physics models. In this
study we examine the potential of observing a heavy charged Higgs boson in its
decay mode of top-quark and bottom-quark in the Type-II
Two-Higgs-Doublet-Model. In this model, the chirality structure of the coupling
of charged Higgs boson to the top- and bottom-quark is very sensitive to the
value of $\tan\beta$. As the polarization of the top-quark can be measured
experimentally from the top-quark decay products, one could make use of the
top-quark polarization to determine the value of $\tan\beta$. We preform a
detailed analysis of measuring top-quark polarization in the production
channels $gb\to tH^-$ and $g\bar{b}\to \bar{t}H^+$. We calculate the helicity
amplitudes of the charged Higgs boson production and decay.Our calculation
shows that the top-quark from the charged Higgs boson decay provides a good
probe for measuring $\tan\beta$, especially for the intermediate $\tan\beta$
region. On the contrary, the top-quark produced in association with the charged
Higgs boson cannot be used to measure $\tan\beta$ because its polarization is
highly contaminated by the $t$-channel kinematics.


title: Central limit theorem related to MDR-method

abstract:
  In many medical and biological investigations, including genetics, it is
typical to handle high dimensional data which can be viewed as a set of values
of some factors and a binary response variable. For instance, the response
variable can describe the state of a patient health and one often assumes that
it depends only on some part of factors. An important problem is to determine
collections of significant factors. In this regard we turn to the MDR-method
introduced by M.Ritchie and coauthors. Our recent paper provided the necessary
and sufficient conditions for strong consistency of estimates of the prediction
error employing the K-fold cross-validation and an arbitrary penalty function.
Here we introduce the regularized versions of the mentioned estimates and prove
for them the multidimensional CLT. Statistical variants of the CLT involving
self-normalization are discussed as well.
  Keywords and phrases: binary response variable, significant factors, penalty
function, cross-validation, MDR-method, SLLN for arrays, strong consistency,
regularized estimates, multidimensional CLT, self-normalization.


title:
Compressed correlation functions and fast aging dynamics in metallic
  glasses

abstract:
  We present x-ray photon correlation spectroscopy measurements of the atomic
dynamics in a Zr67Ni33 metallic glass, well below its glass transition
temperature. We find that the decay of the density fluctuations can be well
described by compressed, thus faster than exponential, correlation functions
which can be modeled by the well-known Kohlrausch-Williams-Watts function with
a shape exponent {\beta} larger than one. This parameter is furthermore found
to be independent of both waiting time and wave-vector, leading to the
possibility to rescale all the correlation functions to a single master curve.
The dynamics in the glassy state is additionally characterized by different
aging regimes which persist in the deep glassy state. These features seem to be
universal in metallic glasses and suggest a non diffusive nature of the
dynamics. This universality is supported by the possibility of describing the
fast increase of the structural relaxation time with waiting time using a
unique model function, independently of the microscopic details of the system.


title:
The radial distribution of water ice and chromophores across Saturn's
  system

abstract:
  Over the last eight years, the Visual and Infrared Mapping Spectrometer
(VIMS) aboard the Cassini orbiter has returned hyperspectral images in the
0.35-5.1 micron range of the icy satellites and rings of Saturn. These very
different objects show significant variations in surface composition, roughness
and regolith grain size as a result of their evolutionary histories, endogenic
processes and interactions with exogenic particles. The distributions of
surface water ice and chromophores, i.e. organic and non-icy materials, across
the saturnian system, are traced using specific spectral indicators (spectral
slopes and absorption band depths) obtained from rings mosaics and
disk-integrated satellites observations by VIMS.


title: Minimal and irreducible links in the Shannon game

abstract:
  We discuss weak and strong links (`virtual connections') in the Shannon game.
General properties of these links are discussed, leading to a method to find
all links of given size by a suitably pruned exhaustive search. This is applied
to links on graphs of up to 11 vertices. We discuss the concept of reducibility
of such links. Three simple reductions are considered, including one, the
`short-cut', not previously described. The complete sets of irreducible weak
links on up to 11 vertices and strong links on up to 10 vertices are presented.
Some applications to the analysis of Hex are noted.


title: Euclidean Relativistic Quantum Mechanics

abstract:
  We discuss a formulation of exactly Poincar\'e invariant quantum mechanics
where the input is model Euclidean Green functions or their generating
functional. We discuss the structure of the models, the construction of the
Hilbert space, the construction and transformation properties of
single-particle states, and the construction of GeV scale transition matrix
elements. A simple model is utilized to demonstrate the feasibility of this
approach.


title:
Bose-Einstein condensate dark matter model tested by galactic rotation
  curves

abstract:
  Rotation curves of spiral galaxies are fundamental tools in the study of dark
matter. Here we test the Bose-Einstein condensate (BEC) dark matter model
against rotation curve data of High and Low Surface Brightness (HSB and LSB)
galaxies, respectively. When the rotational velocities increase over the whole
observed range, the fit of the BEC model is similar to the one of the
Navarro-Frenk-White (NFW) dark matter model. When however the rotation curves
exhibit long flat regions, the NFW profiles provide a slightly better fit.


title: Six "beyond Collins and Sivers" transverse spin asymmetries at COMPASS

abstract:
  COMPASS is a fixed-target high energy physics experiment at the SPS at CERN
\cite{Abbon:2007pq}. One of the important objectives of the experiment is the
exploration of the transverse spin structure of the nucleon via spin dependent
azimuthal asymmetries in single-hadron production in deep inelastic scattering
of polarized leptons off transversely polarized target. For this purpose a
series of measurements were made in COMPASS, using 160 GeV/c longitudinally
polarized muon beam and transversely polarized $^6LiD$ (in 2002, 2003 and 2004)
and $NH_3$ (in 2007 and 2010) targets.
  Till now main attention was focused on Collins and Sivers asymmetries and
obtained results play an important role in the general understanding of the
three-dimensional nature of the nucleon in terms of Transverse Momentum
Dependent (TMD) Parton Distribution Functions (PDFs) and Fragmentation
Functions (FFs).
  In addition to these two measured leading-twist effects, the SIDIS
cross-section counts six more target transverse spin dependent azimuthal
effects, which have their own well defined leading or higher-twist
interpretation in terms of QCD parton model. So far COMPASS presented
preliminary results for these asymmetries from deuteron
\cite{Parsamyan:2007ju},\cite{Kotzinian:2007uv} and "proton-2007" data
\cite{Parsamyan:2010se}. In this contribution we review the results obtained
with the last "proton-2010" data sample.


title:
Positive Semidefinite Matrix Completion, Universal Rigidity and the
  Strong Arnold Property

abstract:
  This paper addresses the following three topics: positive semidefinite (psd)
matrix completions, universal rigidity of frameworks, and the Strong Arnold
Property (SAP). We show some strong connections among these topics, using
semidefinite programming as unifying theme. Our main contribution is a
sufficient condition for constructing partial psd matrices which admit a unique
completion to a full psd matrix. Such partial matrices are an essential tool in
the study of the Gram dimension $\gd(G)$ of a graph $G$, a recently studied
graph parameter related to the low psd matrix completion problem. Additionally,
we derive an elementary proof of Connelly's sufficient condition for universal
rigidity of tensegrity frameworks and we investigate the links between these
two sufficient conditions. We also give a geometric characterization of psd
matrices satisfying the Strong Arnold Property in terms of nondegeneracy of an
associated semidefinite program, which we use to establish some links between
the Gram dimension $\gd(\cdot)$ and the Colin de Verdi\`ere type graph
parameter $\nu^=(\cdot)$.


title:
A Concise Formula for Generalized Two-Qubit Hilbert-Schmidt Separability
  Probabilities

abstract:
  We report major advances in the research program initiated in "Moment-Based
Evidence for Simple Rational-Valued Hilbert-Schmidt Generic 2 x 2 Separability
Probabilities" (J. Phys. A, 45, 095305 [2012]). A highly succinct separability
probability function P(alpha) is put forth, yielding for generic
(9-dimensional) two-rebit systems, P(1/2) = 29/64, (15-dimensional) two-qubit
systems, P(1) = 8/33 and (27-dimensional) two-quater(nionic)bit systems,
P(2)=26/323. This particular form of P(alpha) was obtained by Qing-Hu Hou and
colleagues by applying Zeilberger's algorithm ("creative telescoping") to a
fully equivalent--but considerably more complicated--expression containing six
7F6 hypergeometric functions (all with argument 27/64 = (3/4)^3). That
hypergeometric form itself had been obtained using systematic, high-accuracy
probability-distribution-reconstruction computations. These employed 7,501
determinantal moments of partially transposed four-by-four density matrices,
parameterized by alpha = 1/2, 1, 3/2,...,32. From these computations, exact
rational-valued separability probabilities were discernible. The
(integral/half-integral) sequences of 32 rational values, then, served as input
to the Mathematica FindSequenceFunction command, from which the initially
obtained hypergeometric form of P(alpha) emerged.


title: H2O emission in high-z ultra-luminous infrared galaxies

abstract:
  Using IRAM PdBI we report the detection of H2O in six new lensed
ultra-luminous starburst galaxies at high redshift, discovered in the Herschel
H-ATLAS survey. The sources are detected either in the 2_{02}-1_{11} or
2_{11}-2_{02} H_2O emission lines with integrated line fluxes ranging from 1.8
to 14 Jy.km/s. The corresponding apparent luminosities are mu x L_H2O ~ 3-12 x
10^8 Lo, where mu is the lensing magnification factor (3 < mu < 12). These
results confirm that H2O lines are among the strongest molecular lines in such
galaxies, with intensities almost comparable to those of the high-J CO lines,
and same profiles and line widths (200-900 km/s) as the latter. With the
current sensitivity of PdBI, H2O can therefore easily be detected in high-z
lensed galaxies (with F(500um) > 100 mJy) discovered in the Herschel surveys.
Correcting the luminosities for lensing amplification, L_H2O is found to have a
strong dependence on the IR luminosity, varying as ~L_IR^{1.2}. This relation
which needs to be confirmed with better statistics, may indicate a role of
radiative (IR) excitation of the H2O lines, and implies that high-z galaxies
with L_IR >~ 10^13 Lo tend to be very strong emitters in H2O, that have no
equivalent in the local universe.


title: Measurements of the cosmic ray spectrum and average mass with IceCube

abstract:
  Located at the South Pole, IceCube is a particle-astrophysics observatory
composed of a square-kilometer surface air shower array (IceTop) and a 1.4 km
deep cubic-kilometer optical Cherenkov detector array. We review results of
measurements of the cosmic ray spectrum and average mass in the energy range 1
PeV to 1 EeV.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ph


title:
Limits on spin-dependent WIMP-nucleon cross sections from 225 live days
  of XENON100 data

abstract:
  We present new experimental constraints on the elastic, spin-dependent
WIMP-nucleon cross section using recent data from the XENON100 experiment,
operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of
224.6 live days x 34 kg of exposure acquired during 2011 and 2012 revealed no
excess signal due to axial-vector WIMP interactions with 129-Xe and 131-Xe
nuclei. This leads to the most stringent upper limits on WIMP-neutron cross
sections for WIMP masses above 6 GeV, with a minimum cross section of 3.5 x
10^{-40} cm^2 at a WIMP mass of 45 GeV, at 90% confidence level.


title:
Meromorphically integrable homogeneous potentials with multiple Darboux
  points

abstract:
  We prove that the only meromorphically integrable planar homogeneous
potential of degree k <> -2,0,2 having a multiple Darboux point is the
potential invariant by rotation. This case is a singular case of the
Maciejewski-Przybylska relation on eigenvalues at Darboux points of homogeneous
potentials, and needed before a case by case special analysis. The most
striking application of this Theorem is the complete classification of
integrable real analytic homogeneous potentials in the plane of negative
degree.


title: Supersymmetric Completion of Gauss-Bonnet Combination in Five Dimensions

abstract:
  Based on superconformal tensor calculus in five dimensions, we construct the
supersymmetric completion of Gauss-Bonnet combination. We study the vacuum
solutions with AdS_2 x S^3 and AdS_3 x S^2 structures. We also analyze the
spectrum around a maximally supersymmetric Minkowski_5.


title: Correlations between SNe Ia Rates and Host Galaxy Properties

abstract:
  Studying the correlation of type Ia supernova rates (SNR) with host galaxy
properties is an important step in understanding the exact nature of type Ia
supernovae. We use SNe Ia from the SDSS-II sample, spectroscopically determined
masses and star formation rates, and a new maximum likelihood method, to fit
the Scannapieco and Bildsten rate model $SNR = A{\times}M + B{\times}SFR$,
where $M$ is galaxy mass and $SFR$ is star formation rate. We find $A =
3.5^{+0.9}_{-0.7}\times10^{-14}(\text{SNe/yr})(M_{\odot})^{-1}$ and $B
=1.3^{+0.4}_{-0.3}\times10^{-3}(\text{SNe/yr})(M_{\odot}$yr$^{-1})^{-1}$,
assuming overall efficiency of 0.5. This is in reasonable agreement with other
determinations. However we find strong evidence that this model is a poor fit
to other projections of the data: it fails to correctly predict the
distribution of supernovae with host mass or SFR. An additional model parameter
is required; most likely this parameter is related to host galaxy mass. Some
implications of this result are discussed.


title: Markovian acyclic directed mixed graphs for discrete data

abstract:
  Acyclic directed mixed graphs (ADMGs) are graphs that contain directed
($\rightarrow$) and bidirected ($\leftrightarrow$) edges, subject to the
constraint that there are no cycles of directed edges. Such graphs may be used
to represent the conditional independence structure induced by a DAG model
containing hidden variables on its observed margin. The Markovian model
associated with an ADMG is simply the set of distributions obeying the global
Markov property, given via a simple path criterion (m-separation). We first
present a factorization criterion characterizing the Markovian model that
generalizes the well-known recursive factorization for DAGs. For the case of
finite discrete random variables, we also provide a parameterization of the
model in terms of simple conditional probabilities, and characterize its
variation dependence. We show that the induced models are smooth. Consequently,
Markovian ADMG models for discrete variables are curved exponential families of
distributions.


title: Operator pencil passing through a given operator

abstract:
  Let $\Delta$ be a linear differential operator acting on the space of
densities of a given weight $\lo$ on a manifold $M$. One can consider a pencil
of operators $\hPi(\Delta)=\{\Delta_\l\}$ passing through the operator $\Delta$
such that any $\Delta_\l$ is a linear differential operator acting on densities
of weight $\l$. This pencil can be identified with a linear differential
operator $\hD$ acting on the algebra of densities of all weights. The existence
of an invariant scalar product in the algebra of densities implies a natural
decomposition of operators, i.e. pencils of self-adjoint and anti-self-adjoint
operators. We study lifting maps that are on one hand equivariant with respect
to divergenceless vector fields, and, on the other hand, with values in
self-adjoint or anti-self-adjoint operators. In particular we analyze the
relation between these two concepts, and apply it to the study of
$\diff(M)$-equivariant liftings. Finally we briefly consider the case of
liftings equivariant with respect to the algebra of projective transformations
and describe all regular self-adjoint and anti-self-adjoint liftings.


title: Discriminative Feature Selection for Uncertain Graph Classification

abstract:
  Mining discriminative features for graph data has attracted much attention in
recent years due to its important role in constructing graph classifiers,
generating graph indices, etc. Most measurement of interestingness of
discriminative subgraph features are defined on certain graphs, where the
structure of graph objects are certain, and the binary edges within each graph
represent the "presence" of linkages among the nodes. In many real-world
applications, however, the linkage structure of the graphs is inherently
uncertain. Therefore, existing measurements of interestingness based upon
certain graphs are unable to capture the structural uncertainty in these
applications effectively. In this paper, we study the problem of discriminative
subgraph feature selection from uncertain graphs. This problem is challenging
and different from conventional subgraph mining problems because both the
structure of the graph objects and the discrimination score of each subgraph
feature are uncertain. To address these challenges, we propose a novel
discriminative subgraph feature selection method, DUG, which can find
discriminative subgraph features in uncertain graphs based upon different
statistical measures including expectation, median, mode and phi-probability.
We first compute the probability distribution of the discrimination scores for
each subgraph feature based on dynamic programming. Then a branch-and-bound
algorithm is proposed to search for discriminative subgraphs efficiently.
Extensive experiments on various neuroimaging applications (i.e., Alzheimer's
Disease, ADHD and HIV) have been performed to analyze the gain in performance
by taking into account structural uncertainties in identifying discriminative
subgraph features for graph classification.


title:
Ground state structure of a bilayer Wigner crystal with repulsive
  dielectric images

abstract:
  We study the ground-state structures of identical classical point charges
with Coulomb interactions, confined between two symmetric parallel charged
walls. For the well understood homogeneous dielectric case with no
electrostatic images, the charges evenly condense on the opposite walls,
thereby forming a bilayer Wigner crystal; five structures compete upon changing
the inter-wall separation. Here, we consider a dielectric jump between the
walls and a solvent in which charges are immersed, implying repulsive images.
Using recently developed series representations of lattice sums for Coulomb
law, we derive the complete phase diagram. In contrast to the homogeneous
dielectric case, the particles remain in a hexagonal Wigner monolayer up to a
certain distance between the walls. Beyond this distance, a bifurcation occurs
to a sequence of Wigner bilayers, each layer having a nonzero spacing from the
nearest wall. Another new phenomenon is that the ground-state energy as a
function of the wall separation exhibits a global minimum.


title:
A Simple, Combinatorial Algorithm for Solving SDD Systems in
  Nearly-Linear Time

abstract:
  In this paper, we present a simple combinatorial algorithm that solves
symmetric diagonally dominant (SDD) linear systems in nearly-linear time. It
uses very little of the machinery that previously appeared to be necessary for
a such an algorithm. It does not require recursive preconditioning, spectral
sparsification, or even the Chebyshev Method or Conjugate Gradient. After
constructing a "nice" spanning tree of a graph associated with the linear
system, the entire algorithm consists of the repeated application of a simple
(non-recursive) update rule, which it implements using a lightweight data
structure. The algorithm is numerically stable and can be implemented without
the increased bit-precision required by previous solvers. As such, the
algorithm has the fastest known running time under the standard unit-cost RAM
model. We hope that the simplicity of the algorithm and the insights yielded by
its analysis will be useful in both theory and practice.


title:
Non-perturbative laser effects on the electrical properties of graphene
  nanoribbons

abstract:
  The use of Floquet theory combined with a realistic description of the
electronic structure of illuminated graphene and graphene nanoribbons is
developed to assess the emergence of non-adiabatic and non-perturbative effects
on the electronic properties. Here, we introduce an efficient computational
scheme and illustrate its use by applying it to graphene nanoribbons in the
presence of both linear and circular polarization. The interplay between
confinement due to the finite sample size and laser-induced transitions is
shown to lead to sharp features on the average conductance and density of
states. Particular emphasis is given to the emergence of the bulk limit
response.


title: Political Disaffection: a case study on the Italian Twitter community

abstract:
  In our work we analyse the political disaffection or "the subjective feeling
of powerlessness, cynicism, and lack of confidence in the political process,
politicians, and democratic institutions, but with no questioning of the
political regime" by exploiting Twitter data through machine learning
techniques. In order to validate the quality of the time-series generated by
the Twitter data, we highlight the relations of these data with political
disaffection as measured by means of public opinion surveys. Moreover, we show
that important political news of Italian newspapers are often correlated with
the highest peaks of the produced time-series.


title: Measuring the Casimir force gradient from graphene on a SiO_2 substrate

abstract:
  The gradient of the Casimir force between a Si-SiO${}_2$-graphene substrate
and an Au-coated sphere is measured by means of a dynamic atomic force
microscope operated in the frequency shift technique. It is shown that the
presence of graphene leads to up to 9% increase in the force gradient at the
shortest separation considered. This is in qualitative agreement with the
predictions of an additive theory using the Dirac model of graphene.


title: The Canada-France High-z Quasar Survey: 1.2mm Observations

abstract:
  We report 250 GHz (1.2 mm) observations of a sample of 20 QSOs at redshifts
5.8<z<6.5 from the the Canada-France High-z Quasar Survey (CFHQS), using the
Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-metre telescope. A
rms sensitivity <~ 0.6 mJy was achieved for 65% of the sample, and <~ 1.0 mJy
for 90%. Only one QSO, CFHQS J142952+544717, was robustly detected with
S_250GHz = 3.46 +/-0.52 mJy. This indicates that one of the most powerful known
starbursts at z~6 is associated with this radio loud QSO. On average, the other
CFHQS QSOs, which have a mean optical magnitude fainter than previously studied
SDSS samples of z~6 QSOs, have a mean 1.2 mm flux density <S_250GHz> = 0.41
+/-0.14 mJy; such a 2.9-sigma average detection is hardly meaningful. It would
correspond to <L_FIR> ~ 0.94+/-0.32 10^12 Lo, and an average star formation
rate of a few 100's Mo/yr, depending on the IMF and a possible AGN contribution
to <L_FIR>. This is consistent with previous findings of Wang et al. (2011) on
the far-infrared emission of z~6 QSOs and extends them toward optically fainter
sources.


title:
System size dependence of transverse momentum correlations at
  $\sqrt{s_{NN}}=$ 62.4 and 200 GeV at the BNL Relativistic Heavy Ion Collider

abstract:
  We present a study of the average transverse momentum ($p_t$) fluctuations
and $p_t$ correlations for charged particles produced in Cu+Cu collisions at
midrapidity for $\sqrt{s_{NN}} =$ 62.4 and 200 GeV. These results are compared
with those published for Au+Au collisions at the same energies, to explore the
system size dependence. In addition to the collision energy and system size
dependence, the $p_t$ correlation results have been studied as functions of the
collision centralities, the ranges in $p_t$, the pseudorapidity $\eta$, and the
azimuthal angle $\phi$. The square root of the measured $p_t$ correlations when
scaled by mean $p_t$ is found to be independent of both colliding beam energy
and system size studied. Transport-based model calculations are found to have a
better quantitative agreement with the measurements compared to models which
incorporate only jetlike correlations.


title: Signatures of long-lived spiral patterns

abstract:
  Azimuthal age/color gradients across spiral arms are a signature of
long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where
we have previously found azimuthal age/color gradient candidates, 13 objects
were further selected if a two-armed grand-design pattern survived in a surface
density stellar mass map. Mass maps were obtained from optical and
near-infrared imaging, by comparing with a Monte Carlo library of stellar
population synthesis models that allowed us to obtain the mass-to-light ratio
in the J band, (M/L)_J, as a function of (g-i) versus (i-J) color. The selected
spirals were analyzed with Fourier methods in search for other signatures of
long-lived modes related to the gradients, such as the gradient divergence
toward corotation, and the behavior of the phase angle of the two-armed spiral
in different wavebands, as expected from theory. The results show additional
signatures of long-lived spirals in at least 50% of the objects.


title: Exact sampling and counting for fixed-margin matrices

abstract:
  The uniform distribution on matrices with specified row and column sums is
often a natural choice of null model when testing for structure in two-way
tables (binary or nonnegative integer). Due to the difficulty of sampling from
this distribution, many approximate methods have been developed. We will show
that by exploiting certain symmetries, exact sampling and counting is in fact
possible in many nontrivial real-world cases. We illustrate with real datasets
including ecological co-occurrence matrices and contingency tables.


title:
Studies of NGC 6720 with Calibrated HST WFC3 Emission-Line Filter
  Images--I: Structure and Evolution

abstract:
  We have performed a detailed analysis of the Ring Nebula (NGC 6720) using HST
WFC3 images and derived a new 3-D model. Existing high spectral resolution
spectra played an important supplementary role in our modeling. It is shown
that the Main Ring of the nebula is an ionization-bounded irregular
non-symmetric disk with a central cavity and perpendicular extended lobes
pointed almost towards the observer. The faint outer halos are determined to be
fossil radiation, i.e. radiation from gas ionized in an earlier stage of the
nebula when it was not ionization bounded.
  The narrow-band WFC3 filters that isolate some of the emission-lines are
affected by broadening on their short wavelength side and all the filters were
calibrated using ground-based spectra. The filter calibration results are
presented in an appendix.


title:
Interpretation of the Depths of Maximum of Extensive Air Showers
  Measured by the Pierre Auger Observatory

abstract:
  To interpret the mean depth of cosmic ray air shower maximum and its
dispersion, we parametrize those two observables as functions of the first two
moments of the $\ln A$ distribution. We examine the goodness of this simple
method through simulations of test mass distributions. The application of the
parameterization to Pierre Auger Observatory data allows one to study the
energy dependence of the mean $\ln A$ and of its variance under the assumption
of selected hadronic interaction models. We discuss possible implications of
these dependences in term of interaction models and astrophysical cosmic ray
sources.


title:
On the relation between forecast precision and trading profitability of
  financial analysts

abstract:
  We analyze the relation between earning forecast accuracy and expected
profitability of financial analysts. Modeling forecast errors with a
multivariate Gaussian distribution, a complete characterization of the payoff
of each analyst is provided. In particular, closed-form expressions for the
probability density function, for the expectation, and, more generally, for
moments of all orders are obtained. Our analysis shows that the relationship
between forecast precision and trading profitability need not to be monotonic,
and that, for any analyst, the impact on his expected payoff of the correlation
between his forecasts and those of the other market participants depends on the
accuracy of his signals. Furthermore, our model accommodates a unique
full-communication equilibrium in the sense of Radner (1979): if all
information is reflected in the market price, then the expected payoff of all
market participants is equal to zero.


title: Defects, Super-Poincar\'{e} line bundle and Fermionic T-duality

abstract:
  Topological defects are interfaces joining two conformal field theories, for
which the energy momentum tensor is continuous across the interface. A class of
the topological defects is provided by the interfaces separating two bulk
systems each described by its own Lagrangian, where the two descriptions are
related by a discrete symmetry.
  In this paper we elaborate on the cases in which the discrete symmetry is a
bosonic or a fermionic T- duality. We review how the equations of motion
imposed by the defect encode the general bosonic T- duality transformations for
toroidal compactifications. We generalize this analysis in some detail to the
case of topological defects allowed in coset CFTs, in particular to those
cosets where the gauged group is either an axial or vector U(1). This is
discussed in both the operator and Lagrangian approaches. We proceed to
construct a defect encoding a fermionic T-duality. We show that the fermionic
T-duality is implemented by the Super-Poincar\'{e} line bundle. The observation
that the exponent of the gauge invariant flux on a defect is a kernel of the
Fourier-Mukai transform of the Ramond-Ramond fields, is generalized to a
fermionic T-duality. This is done via a fiberwise integration on
supermanifolds.


title:
Sterile neutrino fits to dark matter mass profiles in the Milky Way and
  in galaxy clusters

abstract:
  In several recent papers it was claimed that SN 1987A data supports the
existence of 4.0 eV and 21.4 eV active neutrino mass eigenstates, and it was
shown that such large masses could be made consistent with existing constraints
including neutrino oscillation data and upper limits on the neutrino flavor
state masses, provided that there also exist a pair of sterile neutrino mass
states whose masses are nearly degenerate with the active ones, plus a third
active-sterile doublet that is tachyonic ($m^2 <0$). Here, independent evidence
is presented for the existence of sterile neutrinos with the previously claimed
masses based on fits to the dark matter distributions in the Milky Way galaxy
and four clusters of galaxies. The fits are in excellent agreement with
observations. In addition, sterile neutrinos having the suggested masses
address the "cusp" problem and the missing satellites problem, as well as that
of the "top down" scenario of structure formation -- previously a chief
drawback of HDM particles. Nevertheless, the highly controversial nature of the
claim, and the need for two free parameters in the dark matter fits, additional
confirming evidence will be required before it can be considered proven.


title: Normal forms of convex lattice polytopes

abstract:
  We describe an algorithm for determining whether two convex polytopes P and
Q, embedded in a lattice, are isomorphic with respect to a lattice
automorphism. We extend this to a method for determining if P and Q are
equivalent, i.e. whether there exists an affine lattice automorphism that sends
P to Q. Methods for calculating the automorphism group and affine automorphism
group of P are also described.
  An alternative strategy is to determine a normal form such that P and Q are
isomorphic if and only if their normal forms are equal. This is the approach
adopted by Kreuzer and Skarke in their PALP software. We describe the
Kreuzer-Skarke method in detail, and give an improved algorithm when P has many
symmetries. Numerous examples, plus two appendices containing detailed
pseudo-code, should help with any future reimplementations of these techniques.
We conclude by explaining how to define and calculate the normal form of a
Laurent polynomial.


title:
Studies of NGC 6720 with Calibrated HST WFC3 Emission-Line Filter
  Images--II:Physical Conditions

abstract:
  We have performed a detailed analysis of the electron temperature and density
in the the Ring Nebula using the calibrated HST WFC3 images described in the
preceding paper. The electron temperature (Te) determined from [N II] and [O
III] rises slightly and monotonically towards the central star. The observed
equivalent width (EW) in the central region indicates that Te rises as high as
13000 K. In contrast, the low EW's in the outer regions are largely due to
scattered diffuse Galactic radiation by dust. The images allowed determination
of unprecedented small scale variations in Te. These variations indicate that
the mean square area temperature fluctuations are significantly higher than
expected from simple photoionization. The power producing these fluctuations
occurs at scales of less than 3.5E15 cm. This scale length provides a strong
restriction on the mechanism causing the large t^2 values observed.


title:
On the Performance of Low Density Parity Check Codes for Gaussian
  Interference Channels

abstract:
  In this paper, two-user Gaussian interference channel(GIC) is revisited with
the objective of developing implementable (explicit) channel codes.
Specifically, low density parity check (LDPC) codes are adopted for use over
these channels, and their benefits are studied. Different scenarios on the
level of interference are considered. In particular, for strong interference
channel examples with binary phase shift keying (BPSK), it is demonstrated that
rates better than those offered by single user codes with time sharing are
achievable. Promising results are also observed with quadrature-shift-keying
(QPSK). Under general interference a Han-Kobayashi coding based scheme is
employed splitting the information into public and private parts, and utilizing
appropriate iterative decoders at the receivers. Using QPSK modulation at the
two transmitters, it is shown that rate points higher than those achievable by
time sharing are obtained.


title:
Simplifying the Configuration of 802.11 Wireless Networks with Effective
  SNR

abstract:
  Advances in the price, performance, and power consumption of Wi-Fi (IEEE
802.11) technology have led to the adoption of wireless functionality in
diverse consumer electronics. These trends have enabled an exciting vision of
rich wireless applications that combine the unique features of different
devices for a better user experience. To meet the needs of these applications,
a wireless network must be configured well to provide good performance at the
physical layer. But because of wireless technology and usage trends, finding
these configurations is an increasingly challenging problem.
  Wireless configuration objectives range from simply choosing the fastest way
to encode data on a single wireless link to the global optimization of many
interacting parameters over multiple sets of communicating devices. As more
links are involved, as technology advances (e.g., the adoption of OFDM and MIMO
techniques in Wi-Fi), and as devices are used in changing wireless channels,
the size of the configuration space grows. Thus algorithms must find good
operating points among a growing number of options.
  ... continued inside thesis.


title: Ideal Whitehead Graphs in Out(F_r) II: The Complete Graph in Each Rank

abstract:
  We show how to construct, for each $r \geq 3$, an ageometric, fully
irreducible $\phi\in Out(F_r)$ whose ideal Whitehead graph is the complete
graph on $2r-1$ vertices.
  This paper is the second in a series of three where we show that precisely
eighteen of the twenty-one connected, simplicial, five-vertex graphs are ideal
Whitehead graphs of fully irreducible $\phi \in Out(F_3)$. The result is a
first step to an $Out(F_r)$ version of the Masur-Smillie theorem proving
precisely which index lists arise from singular measured foliations for
pseudo-Anosov mapping classes.
  In this paper we additionally give a method for finding periodic Nielsen
paths and prove a criterion for identifying representatives of ageometric,
fully irreducible $\phi\in Out(F_r)$


title: Image registration with sparse approximations in parametric dictionaries

abstract:
  We examine in this paper the problem of image registration from the new
perspective where images are given by sparse approximations in parametric
dictionaries of geometric functions. We propose a registration algorithm that
looks for an estimate of the global transformation between sparse images by
examining the set of relative geometrical transformations between the
respective features. We propose a theoretical analysis of our registration
algorithm and we derive performance guarantees based on two novel important
properties of redundant dictionaries, namely the robust linear independence and
the transformation inconsistency. We propose several illustrations and insights
about the importance of these dictionary properties and show that common
properties such as coherence or restricted isometry property fail to provide
sufficient information in registration problems. We finally show with
illustrative experiments on simple visual objects and handwritten digits images
that our algorithm outperforms baseline competitor methods in terms of
transformation-invariant distance computation and classification.


title: Feature allocations, probability functions, and paintboxes

abstract:
  The problem of inferring a clustering of a data set has been the subject of
much research in Bayesian analysis, and there currently exists a solid
mathematical foundation for Bayesian approaches to clustering. In particular,
the class of probability distributions over partitions of a data set has been
characterized in a number of ways, including via exchangeable partition
probability functions (EPPFs) and the Kingman paintbox. Here, we develop a
generalization of the clustering problem, called feature allocation, where we
allow each data point to belong to an arbitrary, non-negative integer number of
groups, now called features or topics. We define and study an "exchangeable
feature probability function" (EFPF)---analogous to the EPPF in the clustering
setting---for certain types of feature models. Moreover, we introduce a
"feature paintbox" characterization---analogous to the Kingman paintbox for
clustering---of the class of exchangeable feature models. We provide a further
characterization of the subclass of feature allocations that have EFPF
representations.


title:
Generalized Bregman Divergence and Gradient of Mutual Information for
  Vector Poisson Channels

abstract:
  We investigate connections between information-theoretic and
estimation-theoretic quantities in vector Poisson channel models. In
particular, we generalize the gradient of mutual information with respect to
key system parameters from the scalar to the vector Poisson channel model. We
also propose, as another contribution, a generalization of the classical
Bregman divergence that offers a means to encapsulate under a unifying
framework the gradient of mutual information results for scalar and vector
Poisson and Gaussian channel models. The so-called generalized Bregman
divergence is also shown to exhibit various properties akin to the properties
of the classical version. The vector Poisson channel model is drawing
considerable attention in view of its application in various domains: as an
example, the availability of the gradient of mutual information can be used in
conjunction with gradient descent methods to effect compressive-sensing
projection designs in emerging X-ray and document classification applications.


title:
X-ray interference effects on the determination of structural data in
  ultrathin La2/3Sr1/3MnO3 epitaxial thin films

abstract:
  We analyze X-ray diffraction data used to extract cell parameters of
ultrathin films on closely matching substrates. We focus on epitaxial
La2/3Sr1/3MnO3 films grown on (001) SrTiO3 single crystalline substrates. It
will be shown that, due to extremely high structural similarity of film and
substrate, data analysis must explicitly consider the distinct phase of the
diffracted waves by substrate and films to extract reliable unit cell
parameters. The implications of this finding for the understanding of strain
effects in ultrathin films and interfaces will be underlined


title: How to kill the Unruh effect

abstract:
  How to kill the Unruh effect? Very simple, by requiring the Rindler
transformation to behave continuously for vanishing acceleration. Then the
Unruh effect disappears as we show in the case of the massive scalar quantum
field. The main point is that the continuity condition restricts the integral
of the mode expansion to the positive energy spectrum, suppressing thus the
$\beta$ - terms of the Bogoliubov transformation.


title: Surfactant mediated growth of ferromagnetic Mn {\delta}-doped Si

abstract:
  We present an investigation of Mn {\delta}-doped layers in Si(001) grown by
molecular beam epitaxy. We discovered that a Pb surfactant has significant
effect on the structural and magnetic properties of the submonolayer of Mn,
which depends on the Si capping layer growth temperature, T_Si, and the Mn
coverage, {\theta}_Mn. The results presented in this paper identify three
regions in the growth-phase-diagram characterized by distinct magnetic
behaviors and crystal structures. In one region, X-ray absorption fine
structure (XAFS) and transmission electron microscopy (TEM) experiments
indicate that MnSi nanocrystallites form with B2-like crystal type structures.
At the optimal growth conditions, T_Si = 200 C and {\theta}_Mn = 0.26
monolayer, a ferromagnetic phase develops with a Curie temperature T_C > 400 K
and a saturation moment m_sat = 1.56 {\mu}_B/Mn, whereas T_C drops to zero for
a control sample prepared without Pb. For T_Si > 200 C, MnSi-B20 type
precipitates form with a T_C ~ 170 K. Rutherford backscattering spectroscopy
shows that the increase in the remanent magnetization in these two phases is
possibly correlated with an increase in the Mn substitutional fraction, which
suggests that a Si_{1-x}Mn_x dilute magnetic semiconductor may be forming in
the matrix between the precipitates. Density functional calculations show that
Pb changes the pathway by which the Mn atoms access the Si substitutional
sites, Mn_Si. While the Pb increases the formation energy of Mn_Si at the Si
surface, it enables substitutional incorporation by lowering the formation
energy of Si vacancies by 0.92 eV.


title: Kirchberg X-algebras with real rank zero and intermediate cancellation

abstract:
  A universal coefficient theorem is proved for C*-algebras over an arbitrary
finite T_0-space X which have vanishing boundary maps. Under bootstrap
assumptions, this leads to a complete classification of unital/stable
real-rank-zero Kirchberg X-algebras with intermediate cancellation. Range
results are obtained for (unital) purely infinite graph C*-algebras with
intermediate cancellation and Cuntz-Krieger algebras with intermediate
cancellation. Permanence results for extensions of these classes follow.


title: Gravity duals of cyclic RG flows, with strings attached

abstract:
  In this note, we propose gravity duals for 3+1 dimensional Lorentz invariant
theories exhibiting discrete scale invariance. We construct non-singular
solutions of a six dimensional gravitational theory that are warped products of
$AdS_{5}$ and a circle. The presence of non-trivial warp factor explicitly
breaks the symmetries of $AdS_{5}$ to discrete scale invariance and also breaks
translation symmetry along the circle. The matter content of the 6D
gravitational theory does not violate the null energy condition. In addition,
we show that the linearized fluctuations around these 6D backgrounds are stable
i.e., the fluctuations do not violate the Breitenlohner-Freedman stability
criterion. The dual theories display periodic RG trajectories, but these RG
flows do not violate the $a$-theorem. In particular, the dual field theory is
not a soft deformation (deformation by marginal or relevant operators) of a 3+1
dimensional conformal field theory and hence the $a$-theorem and similar
monotonicity constraints on RG flows do not apply to these examples. The
holographic $c$-theorem also does not apply to these solutions. Finally, we
present solutions of type II supergravity that exhibit discrete scale
invariance to demonstrate that such solutions can be embedded in string theory.


title: Hanbury Brown and Twiss interferometry at a free-electron laser

abstract:
  We present measurements of second- and higher-order intensity correlation
functions (so-called Hanbury Brown and Twiss experiment) performed at the
free-electron laser (FEL) FLASH in the non-linear regime of its operation. We
demonstrate the high transverse coherence properties of the FEL beam with a
degree of transverse coherence of about 80% and degeneracy parameter of the
order 10^9 that makes it similar to laser sources. Intensity correlation
measurements in spatial and frequency domain gave an estimate of the FEL
average pulse duration of 50 fs. Our measurements of the higher-order
correlation functions indicate that FEL radiation obeys Gaussian statistics,
which is characteristic to chaotic sources.


title:
Radar Imaging and Physical Characterization of Near-Earth Asteroid
  (162421) 2000 ET70

abstract:
  We observed near-Earth asteroid (162421) 2000 ET70 using the Arecibo and
Goldstone radar systems over a period of 12 days during its close approach to
the Earth in February 2012. We obtained continuous wave spectra and
range-Doppler images with range resolutions as fine as 15 m. Inversion of the
radar images yields a detailed shape model with an effective spatial resolution
of 100 m. The asteroid has overall dimensions of 2.6 km X 2.2 km X 2.1 km (5%
uncertainties) and a surface rich with kilometer-scale ridges and concavities.
This size, combined with absolute magnitude measurements, implies an extremely
low albedo (~2%). It is a principal axis rotator and spins in a retrograde
manner with a sidereal spin period of 8.96 +/- 0.01 hours. In terms of
gravitational slopes evaluated at scales of 100 m, the surface seems mostly
relaxed with over 99% of the surface having slopes less than 30 degrees, but
there are some outcrops at the north pole that may have steeper slopes. Our
precise measurements of the range and velocity of the asteroid, combined with
optical astrometry, enables reliable trajectory predictions for this
potentially hazardous asteroid in the interval 460-2813.


title: Device-Independent Test for Genuine Multipartite Entanglement

abstract:
  We investigate a-priori detection probabilities of genuine multipartite
entanglement (GME). Even if one does not have knowledge about the basis in
which a state is produced by a source, how a channel decoheres it or about the
very working of the detectors used, we find that it is possible to detect GME
with reasonably high probability in a feasible fashion. We show that by means
of certain separability criteria, GME can be detected in a
measurement-device-independent way. Our method provides several applications
whenever e.g. state tomography is not possible or too demanding, and is a tool
to investigate security issues in multi-particle quantum cryptographical
protocols.


title: Karhunen-Loeve Analysis for Weak Gravitational Lensing

abstract:
  In the past decade, weak gravitational lensing has become an important tool
in the study of the universe at the largest scale, giving insights into the
distribution of dark matter, the expansion of the universe, and the nature of
dark energy. This thesis research explores several applications of
Karhunen-Loeve (KL) analysis to speed and improve the comparison of weak
lensing shear catalogs to theory in order to constrain cosmological parameters
in current and future lensing surveys. After providing a brief introduction to
cosmology and to KL analysis, this work addresses three related aspects of weak
lensing analysis: (1) Three-dimensional tomographic mapping (based on work
published in Vanderplas et al. 2011); (2) Shear peak statistics with
incomplete/gappy data (based on work published in Vanderplas et al. 2012); and
(3) two-point parameter estimation from gappy data using KL modes (previously
unpublished)... [this abstract has been abbreviated; please see the thesis for
the full abstract].


title:
Minimum Relative Entropy for Quantum Estimation: Feasibility and General
  Solution

abstract:
  We propose a general framework for solving quantum state estimation problems
using the minimum relative entropy criterion. A convex optimization approach
allows us to decide the feasibility of the problem given the data and, whenever
necessary, to relax the constraints in order to allow for a physically
admissible solution. Building on these results, the variational analysis can be
completed ensuring existence and uniqueness of the optimum. The latter can then
be computed by standard, efficient standard algorithms for convex optimization,
without resorting to approximate methods or restrictive assumptions on its
rank.


title: Clustering-Based Matrix Factorization

abstract:
  Recommender systems are emerging technologies that nowadays can be found in
many applications such as Amazon, Netflix, and so on. These systems help users
to find relevant information, recommendations, and their preferred items.
Slightly improvement of the accuracy of these recommenders can highly affect
the quality of recommendations. Matrix Factorization is a popular method in
Recommendation Systems showing promising results in accuracy and complexity. In
this paper we propose an extension of matrix factorization which adds general
neighborhood information on the recommendation model. Users and items are
clustered into different categories to see how these categories share
preferences. We then employ these shared interests of categories in a fusion by
Biased Matrix Factorization to achieve more accurate recommendations. This is a
complement for the current neighborhood aware matrix factorization models which
rely on using direct neighborhood information of users and items. The proposed
model is tested on two well-known recommendation system datasets: Movielens100k
and Netflix. Our experiment shows applying the general latent features of
categories into factorized recommender models improves the accuracy of
recommendations. The current neighborhood-aware models need a great number of
neighbors to acheive good accuracies. To the best of our knowledge, the
proposed model is better than or comparable with the current neighborhood-aware
models when they consider fewer number of neighbors.


title: Curvature of the space of positive Lagrangians

abstract:
  A Lagrangian submanifold in an almost Calabi-Yau manifold is called positive
if the real part of the holomorphic volume form restricted to it is positive.
An exact isotopy class of positive Lagrangian submanifolds admits a natural
Riemannian metric. We compute the Riemann curvature of this metric and show all
sectional curvatures are non-positive. The motivation for our calculation comes
from mirror symmetry. Roughly speaking, an exact isotopy class of positive
Lagrangians corresponds under mirror symmetry to the space of Hermitian metrics
on a holomorphic vector bundle. The latter space is an infinite-dimensional
analog of the non-compact symmetric space dual to the unitary group, and thus
has non-positive curvature.


title:
Structural disorder, magnetism, and electrical and thermoelectric
  properties of pyrochlore Nd2Ru2O7

abstract:
  Polycrystalline Nd2Ru2O7 samples have been prepared and examined using a
combination of structural, magnetic, and electrical and thermal transport
studies. Analysis of synchrotron X-ray and neutron diffraction patterns
suggests some site disorder on the A-site in the pyrochlore sublattice: Ru
substitutes on the Nd-site up to 7.0(3)%, regardless of the different
preparative conditions explored. Intrinsic magnetic and electrical transport
properties have been measured. Ru 4d spins order antiferromagnetically at 143 K
as seen both in susceptibility and specific heat, and there is a corresponding
change in the electrical resistivity behaviour. A second antiferromagnetic
ordering transition seen below 10 K is attributed to ordering of Nd 4f spins.
Nd2Ru2O7 is an electrical insulator, and this behaviour is believed to be
independent of the Ru-antisite disorder on the Nd site. The electrical
properties of Nd2Ru2O7 are presented in the light of data published on all
A2Ru2O7 pyrochlores, and we emphasize the special structural role that Bi3+
ions on the A-site play in driving metallic behaviour. High-temperature
thermoelectric properties have also been measured. When considered in the
context of known thermoelectric materials with useful figures-of-merit, it is
clear that Nd2Ru2O7 has excessively high electrical resistivity which prevents
it from being an effective thermoelectric. A method for screening candidate
thermoelectrics is suggested.


title: On Time-optimal Trajectories for a Car-like Robot with One Trailer

abstract:
  In addition to the theoretical value of challenging optimal control problmes,
recent progress in autonomous vehicles mandates further research in optimal
motion planning for wheeled vehicles. Since current numerical optimal control
techniques suffer from either the curse of dimens ionality, e.g. the
Hamilton-Jacobi-Bellman equation, or the curse of complexity, e.g.
pseudospectral optimal control and max-plus methods, analytical
characterization of geodesics for wheeled vehicles becomes important not only
from a theoretical point of view but also from a prac tical one. Such an
analytical characterization provides a fast motion planning algorithm that can
be used in robust feedback loops. In this work, we use the Pontryagin Maximum
Principle to characterize extremal trajectories, i.e. candidate geodesics, for
a car-like robot with one trailer. We use time as the distance function. In
spite of partial progress, this problem has remained open in the past two
decades. Besides straight motion and turn with maximum allowed curvature, we
identify planar elastica as the third piece of motion that occurs along our
extr emals. We give a detailed characterization of such curves, a special case
of which, called \emph{merging curve}, connects maximum curvature turns to
straight line segments. The structure of extremals in our case is revealed
through analytical integration of the system and adjoint equations.


title: Using Quantum Coherence to Enhance Gain in Atomic Physics

abstract:
  Quantum coherence and interference effects in atomic and molecular physics
has been extensively studied due to intriguing counterintuitive physics and
potential important applications. Here we present one such application of using
quantum coherence to generate and enhance gain in extreme
ultra-violet(XUV)(@58.4nm in Helium) and infra-red(@794.76nm in Rubidium)
regime of electromagnetic radiation. We show that using moderate external
coherent drive, a substantial enhancement in the energy of the lasing pulse can
be achieved under optimal conditions. We also discuss the role of coherence.
The present paper is intended to be pedagogical on this subject of
coherence-enhanced lasing.


title:
Stroboscopic wave packet description of time-dependent currents through
  ring-shaped nanostructures

abstract:
  We present an implementation of a new method for explicit simulations of
time-dependent electric currents through nanojunctions. The method is based on
unitary propagation of stroboscopic wave packet states and is designed to treat
open systems with fluctuating number of electrons while preserving full quantum
coherence throughout the whole infinite system. We demonstrate the performance
of the method on a model system consisting of a ring-shaped nanojunction with
two semi-infinite tight-binding leads. Time-dependent electron current
responses to abrupt bias turn-on or gate potential switching are computed for
several ring configurations and ring-leads coupling parameters. The found
current-carrying stationary states agree well with the predictions of the
Landauer formula. As examples of genuinely time-dependent process we explore
the presence of circulating currents in the rings in transient regimes and the
effect of a time-dependent gate potential.


title: Abelian length categories of strongly unbounded type

abstract:
  We discuss the notion of strongly unbounded type for abelian length
categories; this is closely related to the Second Brauer-Thrall Conjecture for
artin algebras. A new ingredient is the space of characters in the sense of
Crawley-Boevey.


title: Recycler Chromaticities and End Shims for NOvA at Fermilab

abstract:
  In era of NOvA operation, it is planned to slip-stack six on six Booster
proton batches in the Recycler ring for a total intensity of 5 1013
protons/cycle. During the slip-stacking, the chromaticities are required to be
jumped from (-2,-2) to (-20,-20). However, they can only be adjusted to
(-12,-12) from (-2,-2) using existing 2 families of powered sextupoles. On the
other hand, the presently designed Recycler lattice for Nova replaces the 30
straight section with 8 D-D half FODO cells . We use 3 quads in a half-cell to
obtain the working point under the limit of the feasible quad strength, and the
maximum beta-function in this section cannot be less than 80 m. In this paper,
we re-designed the end shims of the permanent magnets in the ring lattice with
appropriate quadrupole and sextupole components to meet both chromaticity and
tune requirements. We are able to use 2 quads in a half cell in RR30 straight
section within feasible quad strength. The maximum beta-functions are also
lowered to around 55 m. The dynamic aperture tracking has been done using MAD
to simulate the scenario of beam injection into the Recycler ring for Nova.


title: Extremal antipodal polygons and polytopes

abstract:
  Let $S$ be a set of $2n$ points on a circle such that for each point $p \in
S$ also its antipodal (mirrored with respect to the circle center) point $p'$
belongs to $S$. A polygon $P$ of size $n$ is called \emph{antipodal} if it
consists of precisely one point of each antipodal pair $(p,p')$ of $S$.
  We provide a complete characterization of antipodal polygons which maximize
(minimize, respectively) the area among all antipodal polygons of $S$. Based on
this characterization, a simple linear time algorithm is presented for
computing extremal antipodal polygons. Moreover, for the generalization of
antipodal polygons to higher dimensions we show that a similar characterization
does not exist.


title: Combination of searches for the Higgs boson using the full CDF data set

abstract:
  We present a combination of searches for the standard model Higgs boson using
the full CDF Run II data set, which corresponds to an integrated luminosity of
9.45--10.0 fb$^{-1}$ collected from $\sqrt{s}=1.96$ TeV $p{\bar{p}}$ collisions
at the Fermilab Tevatron. The searches consider Higgs boson production from
gluon-gluon fusion, vector-boson fusion, and associated production with either
a $W$ or $Z$ boson or a $t{\bar{t}}$ pair. Depending on the production mode,
Higgs boson decays to $W^+W^-$, $ZZ$, $b{\bar{b}}$, $\tau^+\tau^-$, and
$\gamma\gamma$ are examined. We search for a Higgs boson with masses ($m_H$) in
the range 90--200 GeV/$c^2$. In the absence of a signal, we expect based on
combined search sensitivity to exclude at the 95% credibility level the mass
regions $90<m_H<94$ GeV/$c^2$, $96<m_H<106$ GeV/$c^2$, and $153<m_H<175$
GeV/$c^2$. The observed exclusion regions are $90<m_H<102$ GeV/$c^2$ and
$149<m_H<172$ GeV/$c^2$. A moderate excess of signal-like events relative to
the background expectation at the level of 2.0 standard deviations is present
in the data for the $m_H=125$ GeV/$c^2$ search hypothesis. We also present
interpretations of the data within the context of a fermiophobic model and an
alternative standard model incorporating a fourth generation of fermions.
Finally, for the hypothesis of a new particle with mass 125 GeV/$c^2$, we
constrain the coupling strengths of the new particle to $W^\pm$ bosons, $Z$
bosons, and fermions.


title:
Convergence in law of the maximum of the two-dimensional discrete
  Gaussian free field

abstract:
  We consider the two-dimensional Gaussian Free Field on a box of side length
$N$, with Dirichlet boundary data, and prove the convergence of the law of the
recentered maximum of the field.


title:
Analytical formulas, general properties and calculation of transport
  coefficients in the hadron gas: shear and bulk viscosities

abstract:
  Elaborated calculations of the shear and the bulk viscosities in the hadron
gas, using the ultrarelativistic quantum molecular dynamics (UrQMD) model cross
sections, are made. These cross sections are analyzed and improved. A special
treatment of the resonances is implemented additionally. All this allows for
better hydrodynamical description of the experimental data. The previously
considered approximation of one constant cross section for all hadrons is
justified. It's found that the bulk viscosity of the hadron gas is much larger
than the bulk viscosity of the pion gas while the shear viscosity is found to
be less sensitive to the hadronic mass spectrum. The maximum of the bulk
viscosity of the hadron gas is expected to be approximately in the temperature
range ${T=150 190 MeV}$ with zero chemical potentials. This range covers the
critical temperature values found from lattice calculations. We comment on some
important aspects of calculations of the bulk viscosity, which were not taken
into account or were not analyzed well previously. Doing this, a generalized
Chapman-Enskog procedure, taking into account deviations from the chemical
equilibrium, is outlined. Some general properties, features, the physical
meaning of the bulk viscosity and some other comments on the deviations from
the chemical equilibrium supplement this discussion. Analytical closed-form
expressions for the transport coefficients and some related quantities within a
quite large class of cross sections can be obtained. Some examples are
explicitly considered. Comparisons with some previous calculations of the
viscosities in the hadron gas and the pion gas are done.


title: Beam Physics of Integrable Optics Test Accelerator at Fermilab

abstract:
  Fermilab's Integrable Optics Test Accelerator is an electron storage ring
designed for testing advanced accelerator physics concepts, including
implementation of nonlinear integrable beam optics and experiments on optical
stochastic cooling. The machine is currently under construction at the Advanced
Superconducting Test Accelerator facility. In this report we present the goals
and the current status of the project, and describe the details of machine
design. In particular, we concentrate on numerical simulations setting the
requirements on the design and supporting the choice of machine parameters.


title: Ordering of two small parameters in the shallow water wave problem

abstract:
  The classical problem of irrotational long waves on the surface of a shallow
layer of an ideal fluid moving under the influence of gravity as well as
surface tension is considered. A systematic procedure for deriving an equation
for surface elevation for a prescribed relation between the orders of the two
expansion parameters, the amplitude parameter $\alpha$ and the long wavelength
(or shallowness) parameter $\beta$, is developed. Unlike the heuristic
approaches found in the literature, when modifications are made in the equation
for surface elevation itself, the procedure starts from the consistently
truncated asymptotic expansions for unidirectional waves, a counterpart of the
Boussinesq system of equations for the surface elevation and the bottom
velocity, from which the leading order and higher order equations for the
surface elevation can be obtained by iterations. The relations between the
orders of the two small parameters are taken in the form $\beta=O(\alpha^n)$
and $\alpha=O(\beta^m)$ with $n$ and $m$ specified to some important particular
cases. The analysis shows, in particular, that some evolution equations,
proposed before as model equations in other physical contexts (like the Gardner
equation, the modified KdV equation, and the so-called 5th-order KdV equation),
can emerge as the leading order equations in the asymptotic expansion for the
unidirectional water waves, on equal footing with the KdV equation. The results
related to the higher orders of approximation provide a set of consistent
higher order model equations for unidirectional water waves which replace the
KdV equation with higher-order corrections in the case of non-standard ordering
when the parameters $\alpha$ and $\beta$ are not of the same order of
magnitude. (See the paper for the complete abstract.)


title:
Analysis of the first IPTA Mock Data Challenge by the EPTA timing data
  analysis working group

abstract:
  This is a summary of the methods we used to analyse the first IPTA Mock Data
Challenge (MDC), and the obtained results. We have used a Bayesian analysis in
the time domain, accelerated using the recently developed ABC-method which
consists of a form of lossy linear data compression. The TOAs were first
processed with Tempo2, where the design matrix was extracted for use in a
subsequent Bayesian analysis. We used different noise models to analyse the
datasets: no red noise, red noise the same for all pulsars, and individual red
noise per pulsar. We sampled from the likelihood with four different samplers:
"emcee", "t-walk", "Metropolis-Hastings", and "pyMultiNest". All but emcee
agreed on the final result, with emcee failing due to artefacts of the
high-dimensionality of the problem. An interesting issue we ran into was that
the prior of all the 36 (red) noise amplitudes strongly affects the results. A
flat prior in the noise amplitude biases the inferred GWB amplitude, whereas a
flat prior in log-amplitude seems to work well. This issue is only apparent
when using a noise model with individually modelled red noise for all pulsars.
Our results for the blind challenges are in good agreement with the injected
values. For the GWB amplitudes we found h_c = 1.03 +/- 0.11 [10^{-14}], h_c =
5.70 +/- 0.35 [10^{-14}], and h_c = 6.91 +/- 1.72 [10^{-15}], and for the GWB
spectral index we found gamma = 4.28 +/- 0.20, gamma = 4.35 +/- 0.09, and gamma
= 3.75 +/- 0.40. We note that for closed challenge 3 there was quite some
covariance between the signal and the red noise: if we constrain the GWB
spectral index to the usual choice of gamma = 13/3, we obtain the estimates:
h_c = 10.0 +/- 0.64 [10^{-15}], h_c = 56.3 +/- 2.42 [10^{-15}], and h_c = 4.83
+/- 0.50 [10^{-15}], with one-sided 2 sigma upper-limits of: h_c <= 10.98
[10^{-15}], h_c <= 60.29 [10^{-15}], and h_c <= 5.65 [10^{-15}].


title: Habitable Zones Around Main-Sequence Stars: New Estimates

abstract:
  Identifying terrestrial planets in the habitable zones (HZs) of other stars
is one of the primary goals of ongoing radial velocity and transit exoplanet
surveys and proposed future space missions. Most current estimates of the
boundaries of the HZ are based on 1-D, cloud-free, climate model calculations
by Kasting et al.(1993). The inner edge of the HZ in Kasting et al.(1993) model
was determined by loss of water, and the outer edge was determined by the
maximum greenhouse provided by a CO2 atmosphere. A conservative estimate for
the width of the HZ from this model in our Solar system is 0.95-1.67 AU.
  Here, an updated 1-D radiative-convective, cloud-free climate model is used
to obtain new estimates for HZ widths around F, G, K and M stars. New H2O and
CO2 absorption coefficients, derived from the HITRAN 2008 and HITEMP 2010
line-by-line databases, are important improvements to the climate model.
According to the new model, the water loss (inner HZ) and maximum greenhouse
(outer HZ) limits for our Solar System are at 0.99 AU and 1.70 AU,
respectively, suggesting that the present Earth lies near the inner edge.
Additional calculations are performed for stars with effective temperatures
between 2600 K and 7200 K, and the results are presented in parametric form,
making them easy to apply to actual stars. The new model indicates that, near
the inner edge of the HZ, there is no clear distinction between runaway
greenhouse and water loss limits for stars with T_{eff} ~< 5000 K which has
implications for ongoing planet searches around K and M stars. To assess the
potential habitability of extrasolar terrestrial planets, we propose using
stellar flux incident on a planet rather than equilibrium temperature. Our
model does not include the radiative effects of clouds; thus, the actual HZ
boundaries may extend further in both directions than the estimates just given.


title: A Temporal Bayesian Network for Diagnosis and Prediction

abstract:
  Diagnosis and prediction in some domains, like medical and industrial
diagnosis, require a representation that combines uncertainty management and
temporal reasoning. Based on the fact that in many cases there are few state
changes in the temporal range of interest, we propose a novel representation
called Temporal Nodes Bayesian Networks (TNBN). In a TNBN each node represents
an event or state change of a variable, and an arc corresponds to a
causal-temporal relationship. The temporal intervals can differ in number and
size for each temporal node, so this allows multiple granularity. Our approach
is contrasted with a dynamic Bayesian network for a simple medical example. An
empirical evaluation is presented for a more complex problem, a subsystem of a
fossil power plant, in which this approach is used for fault diagnosis and
prediction with good results.


title:
Inferring Parameters and Structure of Latent Variable Models by
  Variational Bayes

abstract:
  Current methods for learning graphical models with latent variables and a
fixed structure estimate optimal values for the model parameters. Whereas this
approach usually produces overfitting and suboptimal generalization
performance, carrying out the Bayesian program of computing the full posterior
distributions over the parameters remains a difficult problem. Moreover,
learning the structure of models with latent variables, for which the Bayesian
approach is crucial, is yet a harder problem. In this paper I present the
Variational Bayes framework, which provides a solution to these problems. This
approach approximates full posterior distributions over model parameters and
structures, as well as latent variables, in an analytical manner without
resorting to sampling methods. Unlike in the Laplace approximation, these
posteriors are generally non-Gaussian and no Hessian needs to be computed. The
resulting algorithm generalizes the standard Expectation Maximization
algorithm, and its convergence is guaranteed. I demonstrate that this algorithm
can be applied to a large class of models in several domains, including
unsupervised clustering and blind source separation.


title:
Relative Loss Bounds for On-line Density Estimation with the Exponential
  Family of Distributions

abstract:
  We consider on-line density estimation with a parameterized density from the
exponential family. The on-line algorithm receives one example at a time and
maintains a parameter that is essentially an average of the past examples.
After receiving an example the algorithm incurs a loss which is the negative
log-likelihood of the example w.r.t. the past parameter of the algorithm. An
off-line algorithm can choose the best parameter based on all the examples. We
prove bounds on the additional total loss of the on-line algorithm over the
total loss of the off-line algorithm. These relative loss bounds hold for an
arbitrary sequence of examples. The goal is to design algorithms with the best
possible relative loss bounds. We use a certain divergence to derive and
analyze the algorithms. This divergence is a relative entropy between two
exponential distributions.


title: An Application of Uncertain Reasoning to Requirements Engineering

abstract:
  This paper examines the use of Bayesian Networks to tackle one of the tougher
problems in requirements engineering, translating user requirements into system
requirements. The approach taken is to model domain knowledge as Bayesian
Network fragments that are glued together to form a complete view of the domain
specific system requirements. User requirements are introduced as evidence and
the propagation of belief is used to determine what are the appropriate system
requirements as indicated by user requirements. This concept has been
demonstrated in the development of a system specification and the results are
presented here.


abstract:
  Possibilistic logic bases and possibilistic graphs are two different
frameworks of interest for representing knowledge. The former stratifies the
pieces of knowledge (expressed by logical formulas) according to their level of
certainty, while the latter exhibits relationships between variables. The two
types of representations are semantically equivalent when they lead to the same
possibility distribution (which rank-orders the possible interpretations). A
possibility distribution can be decomposed using a chain rule which may be
based on two different kinds of conditioning which exist in possibility theory
(one based on product in a numerical setting, one based on minimum operation in
a qualitative setting). These two types of conditioning induce two kinds of
possibilistic graphs. In both cases, a translation of these graphs into
possibilistic bases is provided. The converse translation from a possibilistic
knowledge base into a min-based graph is also described.


title: Artificial Decision Making Under Uncertainty in Intelligent Buildings

abstract:
  Our hypothesis is that by equipping certain agents in a multi-agent system
controlling an intelligent building with automated decision support, two
important factors will be increased. The first is energy saving in the
building. The second is customer value---how the people in the building
experience the effects of the actions of the agents. We give evidence for the
truth of this hypothesis through experimental findings related to tools for
artificial decision making. A number of assumptions related to agent control,
through monitoring and delegation of tasks to other kinds of agents, of rooms
at a test site are relaxed. Each assumption controls at least one uncertainty
that complicates considerably the procedures for selecting actions part of each
such agent. We show that in realistic decision situations, room-controlling
agents can make bounded rational decisions even under dynamic real-time
constraints. This result can be, and has been, generalized to other domains
with even harsher time constraints.


title: Reasoning With Conditional Ceteris Paribus Preference Statem

abstract:
  In many domains it is desirable to assess the preferences of users in a
qualitative rather than quantitative way. Such representations of qualitative
preference orderings form an importnat component of automated decision tools.
We propose a graphical representation of preferences that reflects conditional
dependence and independence of preference statements under a ceteris paribus
(all else being equal) interpretation. Such a representation is ofetn compact
and arguably natural. We describe several search algorithms for dominance
testing based on this representation; these algorithms are quite effective,
especially in specific network topologies, such as chain-and tree- structured
networks, as well as polytrees.


title: Continuous Value Function Approximation for Sequential Bidding Policies

abstract:
  Market-based mechanisms such as auctions are being studied as an appropriate
means for resource allocation in distributed and mulitagent decision problems.
When agents value resources in combination rather than in isolation, they must
often deliberate about appropriate bidding strategies for a sequence of
auctions offering resources of interest. We briefly describe a discrete dynamic
programming model for constructing appropriate bidding policies for resources
exhibiting both complementarities and substitutability. We then introduce a
continuous approximation of this model, assuming that money (or the numeraire
good) is infinitely divisible. Though this has the potential to reduce the
computational cost of computing policies, value functions in the transformed
problem do not have a convenient closed form representation. We develop {em
grid-based} approximation for such value functions, representing value
functions using piecewise linear approximations. We show that these methods can
offer significant computational savings with relatively small cost in solution
quality.


title: Discovering the Hidden Structure of Complex Dynamic Systems

abstract:
  Dynamic Bayesian networks provide a compact and natural representation for
complex dynamic systems. However, in many cases, there is no expert available
from whom a model can be elicited. Learning provides an alternative approach
for constructing models of dynamic systems. In this paper, we address some of
the crucial computational aspects of learning the structure of dynamic systems,
particularly those where some relevant variables are partially observed or even
entirely unknown. Our approach is based on the Structural Expectation
Maximization (SEM) algorithm. The main computational cost of the SEM algorithm
is the gathering of expected sufficient statistics. We propose a novel
approximation scheme that allows these sufficient statistics to be computed
efficiently. We also investigate the fundamental problem of discovering the
existence of hidden variables without exhaustive and expensive search. Our
approach is based on the observation that, in dynamic systems, ignoring a
hidden variable typically results in a violation of the Markov property. Thus,
our algorithm searches for such violations in the data, and introduces hidden
variables to explain them. We provide empirical results showing that the
algorithm is able to learn the dynamics of complex systems in a computationally
tractable way.


title: Comparing Bayesian Network Classifiers

abstract:
  In this paper, we empirically evaluate algorithms for learning four types of
Bayesian network (BN) classifiers - Naive-Bayes, tree augmented Naive-Bayes, BN
augmented Naive-Bayes and general BNs, where the latter two are learned using
two variants of a conditional-independence (CI) based BN-learning algorithm.
Experimental results show the obtained classifiers, learned using the CI based
algorithms, are competitive with (or superior to) the best known classifiers,
based on both Bayesian networks and other formalisms; and that the
computational time for learning and using these classifiers is relatively
small. Moreover, these results also suggest a way to learn yet more effective
classifiers; we demonstrate empirically that this new algorithm does work as
expected. Collectively, these results argue that BN classifiers deserve more
attention in machine learning and data mining communities.


title: Fast Learning from Sparse Data

abstract:
  We describe two techniques that significantly improve the running time of
several standard machine-learning algorithms when data is sparse. The first
technique is an algorithm that effeciently extracts one-way and two-way
counts--either real or expected-- from discrete data. Extracting such counts is
a fundamental step in learning algorithms for constructing a variety of models
including decision trees, decision graphs, Bayesian networks, and naive-Bayes
clustering models. The second technique is an algorithm that efficiently
performs the E-step of the EM algorithm (i.e. inference) when applied to a
naive-Bayes clustering model. Using real-world data sets, we demonstrate a
dramatic decrease in running time for algorithms that incorporate these
techniques.


title: Causal Discovery from a Mixture of Experimental and Observational Data

abstract:
  This paper describes a Bayesian method for combining an arbitrary mixture of
observational and experimental data in order to learn causal Bayesian networks.
Observational data are passively observed. Experimental data, such as that
produced by randomized controlled trials, result from the experimenter
manipulating one or more variables (typically randomly) and observing the
states of other variables. The paper presents a Bayesian method for learning
the causal structure and parameters of the underlying causal process that is
generating the data, given that (1) the data contains a mixture of
observational and experimental case records, and (2) the causal process is
modeled as a causal Bayesian network. This learning method was applied using as
input various mixtures of experimental and observational data that were
generated from the ALARM causal Bayesian network. In these experiments, the
absolute and relative quantities of experimental and observational data were
varied systematically. For each of these training datasets, the learning method
was applied to predict the causal structure and to estimate the causal
parameters that exist among randomly selected pairs of nodes in ALARM that are
not confounded. The paper reports how these structure predictions and parameter
estimates compare with the true causal structures and parameters as given by
the ALARM network.


title: Loglinear models for first-order probabilistic reasoning

abstract:
  Recent work on loglinear models in probabilistic constraint logic programming
is applied to first-order probabilistic reasoning. Probabilities are defined
directly on the proofs of atomic formulae, and by marginalisation on the atomic
formulae themselves. We use Stochastic Logic Programs (SLPs) composed of
labelled and unlabelled definite clauses to define the proof probabilities. We
have a conservative extension of first-order reasoning, so that, for example,
there is a one-one mapping between logical and random variables. We show how,
in this framework, Inductive Logic Programming (ILP) can be used to induce the
features of a loglinear model from data. We also compare the presented
framework with other approaches to first-order probabilistic reasoning.


title: Learning Polytrees

abstract:
  We consider the task of learning the maximum-likelihood polytree from data.
Our first result is a performance guarantee establishing that the optimal
branching (or Chow-Liu tree), which can be computed very easily, constitutes a
good approximation to the best polytree. We then show that it is not possible
to do very much better, since the learning problem is NP-hard even to
approximately solve within some constant factor.


title:
A Hybrid Anytime Algorithm for the Constructiion of Causal Models From
  Sparse Data

abstract:
  We present a hybrid constraint-based/Bayesian algorithm for learning causal
networks in the presence of sparse data. The algorithm searches the space of
equivalence classes of models (essential graphs) using a heuristic based on
conventional constraint-based techniques. Each essential graph is then
converted into a directed acyclic graph and scored using a Bayesian scoring
metric. Two variants of the algorithm are developed and tested using data from
randomly generated networks of sizes from 15 to 45 nodes with data sizes
ranging from 250 to 2000 records. Both variations are compared to, and found to
consistently outperform two variations of greedy search with restarts.


title: Model-Based Bayesian Exploration

abstract:
  Reinforcement learning systems are often concerned with balancing exploration
of untested actions against exploitation of actions that are known to be good.
The benefit of exploration can be estimated using the classical notion of Value
of Information - the expected improvement in future decision quality arising
from the information acquired by exploration. Estimating this quantity requires
an assessment of the agent's uncertainty about its current value estimates for
states. In this paper we investigate ways of representing and reasoning about
this uncertainty in algorithms where the system attempts to learn a model of
its environment. We explicitly represent uncertainty about the parameters of
the model and build probability distributions over Q-values based on these.
These distributions are used to compute a myopic approximation to the value of
information for each action and hence to select the action that best balances
exploration and exploitation.


title: Hybrid Probabilistic Programs: Algorithms and Complexity

abstract:
  Hybrid Probabilistic Programs (HPPs) are logic programs that allow the
programmer to explicitly encode his knowledge of the dependencies between
events being described in the program. In this paper, we classify HPPs into
three classes called HPP_1,HPP_2 and HPP_r,r>= 3. For these classes, we provide
three types of results for HPPs. First, we develop algorithms to compute the
set of all ground consequences of an HPP. Then we provide algorithms and
complexity results for the problems of entailment ("Given an HPP P and a query
Q as input, is Q a logical consequence of P?") and consistency ("Given an HPP P
as input, is P consistent?"). Our results provide a fine characterization of
when polynomial algorithms exist for the above problems, and when these
problems become intractable.


title:
Assessing the value of a candidate. Comparing belief function and
  possibility theories

abstract:
  The problem of assessing the value of a candidate is viewed here as a
multiple combination problem. On the one hand a candidate can be evaluated
according to different criteria, and on the other hand several experts are
supposed to assess the value of candidates according to each criterion.
Criteria are not equally important, experts are not equally competent or
reliable. Moreover levels of satisfaction of criteria, or levels of confidence
are only assumed to take their values in qualitative scales which are just
linearly ordered. The problem is discussed within two frameworks, the
transferable belief model and the qualitative possibility theory. They
respectively offer a quantitative and a qualitative setting for handling the
problem, providing thus a way to compare the nature of the underlying
assumptions.


title: Evaluation of Distributed Intelligence on the Smart Card

abstract:
  We describe challenges in the risk management of smart card based electronic
cash industry and describe a method to evaluate the effectiveness of
distributed intelligence on the smart card. More specifically, we discuss the
evaluation of distributed intelligence function called "on-chip risk
management" of the smart card for the global electronic cash payment
application using micro dynamic simulation. Handling of uncertainty related to
future economic environment, various potential counterfeit attack scenarios,
requires simulation of such environment to evaluate on-chip performance.
Creation of realistic simulation of electronic cash economy, transaction
environment, consumers, merchants, banks are challenge themselves. In addition,
we shows examples of detection capability of off-chip, host based counterfeit
detection systems based on the micro dynamic simulation model generated data
set.