title:
Collisionless shocks in partly ionized plasma with cosmic rays:
  microphysics of non-thermal components

abstract:
  In this review we discuss some observational aspects and theoretical models
of astrophysical collisionless shocks in partly ionized plasma with the
presence of non-thermal components. A specific feature of fast strong
collisionless shocks is their ability to accelerate energetic particles that
can modify the shock upstream flow and form the shock precursors. We discuss
the effects of energetic particle acceleration and associated magnetic field
amplification and decay in the extended shock precursors on the line and
continuum multi-wavelength emission spectra of the shocks. Both Balmer-type and
radiative astrophysical shocks are discussed in connection to supernova
remnants interacting with partially neutral clouds. Quantitative models
described in the review predict a number of observable line-like emission
features that can be used to reveal the physical state of the matter in the
shock precursors and the character of nonthermal processes in the shocks.
Implications of recent progress of gamma-ray observations of supernova remnants
in molecular clouds are highlighted.


title: On commutative weak BCK-algebras

abstract:
  The class of weak BCK-algebras is obtained by weakening one of standard BCK
axioms. It is known that every weak BCK-algebra is completely determined by the
structure of its initial segments. We review several natural classes of
commutative weak BCK-algebras, prove that they are equationally definable, and
show that the order duals of a multitude of algebras with implication known in
the literature in connection with various quantum logics are, in fact,
commutative weak BCK-algebras belonging to that or other of these classes. We
also characterize initial segments of algebras in each of the classes as
lattices equipped with a suitable kind of complementation. In particular,
commutative weak BCK-algebras are just those meet semilattices with the least
element in which all initial segments are non-distributive de Morgan lattices.


title: Passages in Graphs

abstract:
  Directed graphs can be partitioned in so-called passages. A passage P is a
set of edges such that any two edges sharing the same initial vertex or sharing
the same terminal vertex are both inside $P$ or are both outside of P. Passages
were first identified in the context of process mining where they are used to
successfully decompose process discovery and conformance checking problems. In
this article, we examine the properties of passages. We will show that passages
are closed under set operators such as union, intersection and difference.
Moreover, any passage is composed of so-called minimal passages. These
properties can be exploited when decomposing graph-based analysis and
computation problems.


title: Self-limiting excitation of MEMS devices with surface electrodes

abstract:
  An excitation method for MEMS devices with planar electrodes is described.
The stationary part of the device (the stator) consists of three electrode
arrays arranged in the 'ABCABC' order. 'A', 'B', and 'C' carry time-independent
potentials and together form a spatially-periodic electrostatic profile. The
moving part of the device (the translator) has two electrode arrays 'ababab',
with 'a' and 'b' carrying time-dependent out-of-phase voltages. When the
frequency of the time-dependent voltage is close to the natural frequency of
the spring-mass system, the translator is driven into resonance. By adjusting
the spatial phase of the stationary profile, the driving force on the
translator can be maximized for any equilibrium position. Physical misalignment
between the stator and translator resulting from imperfect fabrication can be
corrected electrically. A dynamical equation describing translator motion is
derived and analyzed for resonant and parametric driving. In both cases, the
driving force depends on the translator displacement in a periodic fashion.
Such nonlinearity of the driving force results in self-stabilization of forced
oscillations. This property has implications for the stability of vibratory
gyroscopes.


title: A Literature Survey on Empirical Evidence in Software Engineering

abstract:
  Context: Software Engineering research makes use of collections of software
artifacts (corpora) to derive empirical evidence from. Goal: To improve quality
and reproducibility of research, we need to understand the characteristics of
used corpora. Method: For that, we perform a literature survey using grounded
theory. We analyze the latest proceedings of seven relevant conferences.
Results: While almost all papers use corpora of some kind with the common case
of collections of source code of open-source Java projects, there are no
frequently used projects or corpora across all the papers. For some conferences
we can detect recurrences. We discover several forms of requirements and
applied tunings for corpora which indicate more specific needs of research
efforts. Conclusion: Our survey feeds into a quantitative basis for discussing
the current state of empirical research in software engineering, thereby
enabling ultimately improvement of research quality specifically in terms of
use (and reuse) of empirical evidence.


title: The strange (hi)story of particles and waves

abstract:
  This is a non-technical presentation (in historical context) of the quantum
theory that is strictly based on global unitarity. While the first part was
written for a general readership, Sect. 5 may appear a bit provocative. I argue
that the single-particle wave functions of quantum mechanics have to be
correctly interpreted as field modes that are "occupied once" (that is, first
excited states of the corresponding quantum oscillators in the case of a boson
field). Multiple excitations lead non-relativistically to apparent
many-particle wave functions, while the quantum states proper are defined by
wave function(al)s on the configuration space of fundamental fields, or on
another, as yet elusive, fundamental basis.


title: Chemical analysis of giant stars in the young open cluster NGC 3114

abstract:
  Context: Open clusters are very useful targets for examining possible trends
in galactocentric distance and age, especially when young and old open clusters
are compared. Aims: We carried out a detailed spectroscopic analysis to derive
the chemical composition of seven red giants in the young open cluster NGC
3114. Abundances of C, N, O, Li, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce,
and Nd were obtained, as well as the carbon isotopic ratio. Methods: The
atmospheric parameters of the studied stars and their chemical abundances were
determined using high-resolution optical spectroscopy. We employed the
local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral
analysis code MOOG. The abundances of the light elements were derived using the
spectral synthesis technique. Results: We found that NGC 3114 has a mean
metallicity of [Fe/H] = -0.01+/-0.03. The isochrone fit yielded a turn-off mass
of 4.2 Msun. The [N/C] ratio is in good agreement with the models predicted by
first dredge-up. We found that two stars, HD 87479 and HD 304864, have high
rotational velocities of 15.0 km/s and 11.0 km/s; HD 87526 is a halo star and
is not a member of NGC 3114. Conclusions: The carbon and nitrogen abundance in
NGC 3114 agree with the field and cluster giants. The oxygen abundance in NGC
3114 is lower compared to the field giants. The [O/Fe] ratio is similar to the
giants in young clusters. We detected sodium enrichment in the analyzed cluster
giants. As far as the other elements are concerned, their [X/Fe] ratios follow
the same trend seen in giants with the same metallicity.


title: On optimal language compression for sets in PSPACE/poly

abstract:
  We show that if DTIME[2^O(n)] is not included in DSPACE[2^o(n)], then, for
every set B in PSPACE/poly, all strings x in B of length n can be represented
by a string compressed(x) of length at most log(|B^{=n}|)+O(log n), such that a
polynomial-time algorithm, given compressed(x), can distinguish x from all the
other strings in B^{=n}. Modulo the O(log n) additive term, this achieves the
information-theoretic optimum for string compression. We also observe that
optimal compression is not possible for sets more complex than PSPACE/poly
because for any time-constructible superpolynomial function t, there is a set A
computable in space t(n) such that at least one string x of length n requires
compressed(x) to be of length 2 log(|A^=n|).


title: Extreme value theory for random walks on homogeneous spaces

abstract:
  In this paper we study extreme events for random walks on homogeneous spaces.
We consider the following three cases. On the torus we study closest returns of
a random walk to a fixed point in the space. For a random walk on the space of
unimod- ular lattices we study extreme values for lengths of the shortest
vector in a lattice. For a random walk on a homogeneous space we study the
maximal distance a random walk gets away from an arbitrary fixed point in the
space. We prove an exact limiting distribution on the torus and upper and lower
bounds for sparse subsequences of random walks in the two other cases. In all
three settings we obtain a logarithm law.


title: Linear-in-$\Delta$ Lower Bounds in the LOCAL Model

abstract:
  By prior work, there is a distributed algorithm that finds a maximal
fractional matching (maximal edge packing) in $O(\Delta)$ rounds, where
$\Delta$ is the maximum degree of the graph. We show that this is optimal:
there is no distributed algorithm that finds a maximal fractional matching in
$o(\Delta)$ rounds.
  Our work gives the first linear-in-$\Delta$ lower bound for a natural graph
problem in the standard model of distributed computing---prior lower bounds for
a wide range of graph problems have been at best logarithmic in $\Delta$.


title: Revisiting ZZ and \gamma Z production with effective field theories

abstract:
  A complete and systematic effective field theory analysis of new physics
effects in \bar{f}f -> ZZ and \bar{f}f -> \gamma Z is performed. Results are
presented for the different initial and final-state polarized differential
cross sections in terms of oblique, gauge-fermion and neutral triple gauge
corrections (nTGC). Phenomenological signatures for new physics detection at
the LHC and at future linear colliders are discussed. In comparison to WW
production, they follow a completely different pattern: nTGC only appear at
NNLO in the effective field theory expansion and, accordingly, are extremely
suppressed. However, in the high energy regime, v << \sqrt{s} << 3 TeV, nTGC
are shown to neatly dominate the longitudinal-transversal final-state
polarizations over the standard model background. Their tiny effects get hugely
amplified at energies \sqrt{s} (0.6-1) TeV and can easily generate up to 20%
deviations over the standard model predictions.


title:
Reply to arXiv:1211.3957 and arXiv:1211.4731 by Leader et al. and
  arXiv:1212.0761 by Harindranath et al

abstract:
  We reply to the recent comments on our published papers, Phys. Rev. Lett. 109
(2012) 152005 and Phys. Lett. B717 (2012) 214. We point out that the criticisms
about the transverse polarization parton sum rule we obtained are invalid.


title: Perturbations of Kantowski-Sachs models with a cosmological constant

abstract:
  We investigate perturbations of Kantowski-Sachs models with a positive
cosmological constant, using the gauge invariant 1+3 and 1+1+2 covariant splits
of spacetime together with a harmonic decomposition. The perturbations are
assumed to be vorticity-free and of perfect fluid type, but otherwise include
general scalar, vector and tensor modes. In this case the set of equations can
be reduced to six evolution equations for six harmonic coefficients.


title: Mechanics of Adhered, Pressurized Graphene Blisters

abstract:
  We study the mechanics of pressurized graphene membranes using an
experimental configuration that allows the determination of the elasticity of
graphene and the adhesion energy between a substrate and a graphene (or other
two-dimensional solid) membrane. The test consists of a monolayer graphene
membrane adhered to a substrate by surface forces. The substrate is patterned
with etched microcavities of a prescribed volume and when they are covered with
the graphene monolayer it traps a fixed number (N) of gas molecules in the
microchamber. By lowering the ambient pressure, and thus changing the pressure
difference across the graphene membrane, the membrane can be made to bulge and
delaminate in a stable manner from the substrate. Here we describe the analysis
of the membrane/substrate as a thermodynamic system and explore the behavior of
the system over representative experimentally-accessible geometry and loading
parameters. We carry out companion experiments and compare them to the
theoretical predictions and then use the theory and experiments together to
determine the adhesion energy of graphene/SiO2 interfaces. We find an average
adhesion energy of 0.24 J/m2 which is lower, but in line with our previously
reported values. We assert that this test, which we call the constant N blister
test, is a valuable approach to determine the adhesion energy between
two-dimensional solid membranes and a substrate, which is an important, but not
well-understood aspect of behavior. The test also provides valuable information
that can serve as the basis for subsequent research to understand the
mechanisms contributing to the observed adhesion energy. Finally, we show how
in the limit of a large microcavity, the constant N test approaches the
behavior observed in a constant pressure blister test and we provide an
experimental observation that suggests this behavior.


title: Anderson localization of entangled photons in an integrated quantum walk

abstract:
  Waves fail to propagate in random media. First predicted for quantum
particles in the presence of a disordered potential, Anderson localization has
been observed also in classical acoustics, electromagnetism and optics. Here,
for the first time, we report the observation of Anderson localization of pairs
of entangled photons in a two-particle discrete quantum walk affected by
position dependent disorder. A quantum walk on a disordered lattice is realized
by an integrated array of interferometers fabricated in glass by femtosecond
laser writing. A novel technique is used to introduce a controlled phase shift
into each unit mesh of the network. Polarization entanglement is exploited to
simulate the different symmetries of the two-walker system. We are thus able to
experimentally investigate the genuine effect of (bosonic and fermionic)
statistics in the absence of interaction between the particles. We will show
how different types of randomness and the symmetry of the wave-function affect
the localization of the entangled walkers.


title:
Adhesion and size dependent friction anisotropy in boron nitride
  nanotubes

abstract:
  The frictional properties of individual multiwalled boron nitride nanotubes
(BN-NTs) synthesized by chemical vapor deposition (CVD) and deposited on a
silicon substrate are investigated using an atomic force microscope tip sliding
along (longitudinal sliding) and across (transverse sliding) the tube's
principal axis. Because of the tube transverse deformations during the tip
sliding, a larger friction coefficient is found for the transverse sliding as
compared to the longitudinal sliding. Here, we show that the friction
anisotropy in BN-NTs, defined as the ratio between transverse and longitudinal
friction forces per unit area, increases with the nanotube-substrate contact
area. Larger contact area denotes stronger surface adhesion, resulting in a
longitudinal friction coefficient closer to the value expected in absence of
transverse deformations. Compared to carbon nanotubes (C-NT), BN-NTs display a
friction coefficient in each sliding direction with intermediate values between
CVD and arc discharge C-NTs. CVD BN-NTs with improved tribological properties
and higher oxidation temperature might be a better candidate than CVD C-NTs for
applications in extreme environments.


title:
A Novel Frank-Wolfe Algorithm. Analysis and Applications to Large-Scale
  SVM Training

abstract:
  Recently, there has been a renewed interest in the machine learning community
for variants of a sparse greedy approximation procedure for concave
optimization known as {the Frank-Wolfe (FW) method}. In particular, this
procedure has been successfully applied to train large-scale instances of
non-linear Support Vector Machines (SVMs). Specializing FW to SVM training has
allowed to obtain efficient algorithms but also important theoretical results,
including convergence analysis of training algorithms and new characterizations
of model sparsity.
  In this paper, we present and analyze a novel variant of the FW method based
on a new way to perform away steps, a classic strategy used to accelerate the
convergence of the basic FW procedure. Our formulation and analysis is focused
on a general concave maximization problem on the simplex. However, the
specialization of our algorithm to quadratic forms is strongly related to some
classic methods in computational geometry, namely the Gilbert and MDM
algorithms.
  On the theoretical side, we demonstrate that the method matches the
guarantees in terms of convergence rate and number of iterations obtained by
using classic away steps. In particular, the method enjoys a linear rate of
convergence, a result that has been recently proved for MDM on quadratic forms.
  On the practical side, we provide experiments on several classification
datasets, and evaluate the results using statistical tests. Experiments show
that our method is faster than the FW method with classic away steps, and works
well even in the cases in which classic away steps slow down the algorithm.
Furthermore, these improvements are obtained without sacrificing the predictive
accuracy of the obtained SVM model.


title:
Tauberian conditions, Muckenhoupt weights, and differentiation
  properties of weighted bases

abstract:
  We give an alternative characterization of the class of Muckenhoupt weights
$A_{\infty, \mathfrak B}$ for homothecy invariant Muckenhoupt bases $\mathfrak
B$ consisting of convex sets. In particular we show that $w\in A_{\infty,
\mathfrak B}$ if and only if there exists a constant $c>0$ such that for all
measurable sets $E\subset \mathbb R^n$ we have $$ w({x\in \mathbb R^n:
M_{\mathfrak B} (\mathbf {1}_E)(x)>1/2}) < c w(E).$$ This applies for example
to the collection $\mathfrak R$ of rectangles with sides parallel to the
coordinate axes, giving a new characterization of strong (multiparameter)
Muckenhoupt weights. We also show versions of these results under the presence
of a doubling measure. Thus the strong maximal function $M_{\mathfrak R,\mu}$,
defined with respect to a product-doubling measure $\mu$, is bounded on
$L^p(\mu)$ for some $p>1$ if and only if $$\mu({x\in \mathbb R^n: M_{\mathfrak
R,\mu} (\mathbf{1}_E)(x)>1/2}) < c \mu(E)$$ for all measurable sets $E\subset
\mathbb R^n$. Finally we discuss applications in differentiation theory,
proving among other things that Tauberian conditions as above imply that the
corresponding bases differentiate $L^\infty(\mu)$, with respect to the measure
$\mu$.


title: 5D super Yang-Mills theory and the correspondence to AdS$_7$/CFT$_6$

abstract:
  We study the relation between 5D super Yang-Mills theory and the holographic
description of 6D (2,0) superconformal theory. We start by clarifying some
issues related to the localization of N=1 SYM with matter on $S^5$. We
concentrate on the case of a single adjoint hypermultiplet with a mass term and
argue that the theory has a symmetry enlargement at mass M=1/(2r), where r is
the $S^5$ radius. However, in order to have a well-defined localization locus
it is necessary to rotate M onto the imaginary axis, breaking the enlarged
symmetry. Based on our prescription, the imaginary mass values are physical and
we show how the localized path integral is consistent with earlier results for
5D SYM in flat space. We then compute the free energy and the expectation value
for a circular Wilson loop in the large N limit. The Wilson loop calculation
shows a mass dependent constant rescaling between weak and strong coupling. The
Wilson loop continued back to to the enlarged symmetry point is consistent with
a supergravity computation for an M2 brane using the standard identification of
the compactification radius and the 5D coupling. If we continue back to the
physical regime and use this value of the mass to determine the
compactification radius, then we find agreement between the SYM free energy and
the corresponding supergravity calculation. We also verify numerically some of
our analytic approximations.


title:
What is an Observatory? The Crucial Role of Such Organizations for
  Maximizing the Science Return from Astronomy Research Facilities

abstract:
  Observatories, Institutes and Centers that support major astronomical
facilities have, for decades, played a key role in maximizing the scientific
return from their facilities and telescopes. It is crucial to realize that an
"observatory" is more than simply a telescope or ensemble of telescopes that
provide observing opportunities for astronomers. Observatories are at the heart
of an institutional capability to do things beyond what is possible for
astronomers themselves to do as individuals. Observatories organize and
mobilize a range of multidisciplinary skills for achieving a coherent and
sustainable capability that is central to modern observational astrophysics.
Yet many of the activities and roles carried out by the "observatory"
organization in fulfillment of their mission are not fully recognized by
policymakers or senior managers, and often not fully understood even within the
astronomy community. As we assess the future opportunities for new facilities
in a challenging budget environment it is important to be cognizant of what
observatories do and the roles they play.


title:
Estimating Phoneme Class Conditional Probabilities from Raw Speech
  Signal using Convolutional Neural Networks

abstract:
  In hybrid hidden Markov model/artificial neural networks (HMM/ANN) automatic
speech recognition (ASR) system, the phoneme class conditional probabilities
are estimated by first extracting acoustic features from the speech signal
based on prior knowledge such as, speech perception or/and speech production
knowledge, and, then modeling the acoustic features with an ANN. Recent
advances in machine learning techniques, more specifically in the field of
image processing and text processing, have shown that such divide and conquer
strategy (i.e., separating feature extraction and modeling steps) may not be
necessary. Motivated from these studies, in the framework of convolutional
neural networks (CNNs), this paper investigates a novel approach, where the
input to the ANN is raw speech signal and the output is phoneme class
conditional probability estimates. On TIMIT phoneme recognition task, we study
different ANN architectures to show the benefit of CNNs and compare the
proposed approach against conventional approach where, spectral-based feature
MFCC is extracted and modeled by a multilayer perceptron. Our studies show that
the proposed approach can yield comparable or better phoneme recognition
performance when compared to the conventional approach. It indicates that CNNs
can learn features relevant for phoneme classification automatically from the
raw speech signal.


title:
Full-band electronic structure calculation of semiconductor
  nanostructures: a reduced-order approach

abstract:
  We propose an efficient reduced-order technique for electronic structure
calculations of semiconductor nanostructures, suited for inclusion in full-band
quantum transport simulators. The model is based on the linear combination of
bulk bands obtained by the empirical pseudopotential method, combined with the
use of problem-matched basis functions numerically generated from the singular
value decomposition. The efficiency and accuracy of the proposed approach are
demonstrated in the case of the dispersion relation of hole subbands in an
unstrained GaN layer.


title:
Spatial Resources Optimization in Distributed MIMO Networks with Limited
  Data Sharing

abstract:
  Wireless access through a large distributed network of low-complexity
infrastructure nodes empowered with cooperation and coordination capabilities,
is an emerging radio architecture, candidate to deal with the mobile data
capacity crunch. In the 3GPP evolutionary path, this is known as the Cloud-RAN
paradigm for future radio. In such a complex network, distributed MIMO
resources optimization is of paramount importance, in order to achieve capacity
scaling. In this paper, we investigate efficient strategies towards optimizing
the pairing of access nodes with users as well as linear precoding designs for
providing fair QoS experience across the whole network, when data sharing is
limited due to complexity and overhead constraints. We propose a method for
obtaining the exact optimal spatial resources allocation solution which can be
applied in networks of limited scale, as well as an approximation algorithm
with bounded polynomial complexity which can be used in larger networks. The
particular algorithm outperforms existing user-oriented clustering techniques
and achieves quite high quality-of-service levels with reasonable complexity.


title:
Low-lying even parity meson resonances and spin-flavor symmetry
  revisited

abstract:
  We review and extend the model derived in Phys. Rev. D83 016007 (2011) to
address the dynamics of the low-lying even parity meson resonances. This model
is based on a coupled channels spin-flavor extension of the chiral
Weinberg-Tomozawa Lagrangian. This interaction is then used to study the S-wave
meson-meson scattering involving members not only of the \pi-octet, but also of
the \rho-nonet. In this work, we study in detail the structure of the SU(6)
symmetry breaking contact terms that respect (or softly break) chiral symmetry.
We derive the most general local (without involving derivatives) terms
consistent with the chiral symmetry breaking pattern of QCD. After introducing
sensible simplifications to reduce the large number of possible operators, we
carry out a phenomenological discussion of the effects of these terms. We show
how the inclusion of these pieces leads to an improvement of the description of
J^P = 2^+ sector, without spoiling the main features of the predictions
obtained in the original model in the J^P = 0^+ and J^P = 1^+ sectors. In
particular, we find a significantly better description of the
I^G(J^{PC})=0^+(2^{++}), 1^-(2^{++}) and the I(J^{P})=\frac{1}{2}(2^{+})
sectors, which correspond to the f_2(1270), a_2(1320) and K^*_2(1430) quantum
numbers, respectively.


title: A software for aging faces applied to ancient marble busts

abstract:
  The study and development of software able to show the effect of aging of
faces is one of the tasks of face recognition technologies. Some software
solutions are used for investigations, some others to show the effects of drugs
on healthy appearance, however some other applications can be proposed for the
analysis of visual arts. Here we use a freely available software, which is
providing interesting results, for the comparison of ancient marble busts. An
analysis of Augustus busts is proposed.


title: On the Orbits of not Expansive Mappings in Metric Spaces

abstract:
  Let $\MSpace$ be a locally compact metric space and let
$\pMap:\MSpace\to\MSpace$ be a not expansive map. We prove that for each
$\ppa_0\in\MSpace$ the sequence $\ppa_0,\pMap(\ppa_0),\pMap^2(\ppa_0),\ldots$
is either relatively compact in $\MSpace$ or compactly divergent in $\MSpace$.
As applications we study the structure of the functions which are limits of the
iterates of the map $\pMap$ and we prove the analyticity of the set of
$\pMap$-recurrent points when $\pMap:\MSpace\to\MSpace$ is a holomorphic and
$\MSpace$ is a complex hyperbolic spaces in the sense of Kobayashi.


title: Silicon spin chains at finite temperature: dynamics of Si(553)-Au

abstract:
  When gold is deposited on Si(553), the surface self-assembles to form a
periodic array of steps with nearly perfect structural order. In scanning
tunneling microscopy these steps resemble quasi-one-dimensional atomic chains.
At temperatures below ~50 K the chains develop tripled periodicity. We recently
predicted, on the basis of density-functional theory calculations at T=0, that
this tripled periodicity arises from the complete polarization of the electron
spin on every third silicon atom along the step; in the ground state these
linear chains of silicon spins are antiferromagnetically ordered. Here we
explore, using ab-initio molecular dynamics and kinetic Monte Carlo
simulations, the behavior of silicon spin chains on Si(553)-Au at finite
temperature. Thermodynamic phase transitions at T>0 in one-dimensional systems
are prohibited by the Mermin-Wagner theorem. Nevertheless we find that a
surprisingly sharp onset occurs upon cooling---at about 30 K for perfect
surfaces and at higher temperature for surfaces with defects---to a
well-ordered phase with tripled periodicity, in good agreement with experiment.


title:
Sequential recombination algorithm for jet clustering and background
  subtraction

abstract:
  We investigate a new sequential recombination algorithm which effectively
subtracts background as it reconstructs the jet. We examine the new algorithm's
behavior in light of existing algorithms, and we find that in Monte Carlo
comparisons, the new algorithm's robustness against collision backgrounds is
comparable to that of other jet algorithms when the latter have been augmented
by further background subtraction techniques.


title: Electron motion in a Holstein molecular chain in an electric field

abstract:
  A charge motion in an electric field in a Holstein molecular chain is modeled
in the absence of dissipation. It is shown that in a weak electric field a
Holstein polaron moves uniformly experiencing small oscillations of its shape.
These oscillations are associated with the chain's discreteness and caused by
the presence of Peierls-Nabarro potential there. The critical value of the
electric field intensity at which the moving polaron starts oscillating at
Bloch frequency is found. It is shown that the polaron can demonstrate Bloch
oscillations retaining its shape. It is also shown that a breathing mode of
Bloch oscillations can arise. In all cases the polaron motion along the chain
is infinite.


title: Infinitesimals as an issue in neo-Kantian philosophy of science

abstract:
  We seek to elucidate the philosophical context in which one of the most
important conceptual transformations of modern mathematics took place, namely
the so-called revolution in rigor in infinitesimal calculus and mathematical
analysis. Some of the protagonists of the said revolution were Cauchy, Cantor,
Dedekind, and Weierstrass. The dominant current of philosophy in Germany at the
time was neo-Kantianism. Among its various currents, the Marburg school (Cohen,
Natorp, Cassirer, and others) was the one most interested in matters scientific
and mathematical. Our main thesis is that Marburg neo-Kantian philosophy
formulated a sophisticated position towards the problems raised by the concepts
of limits and infinitesimals. The Marburg school neither clung to the
traditional approach of logically and metaphysically dubious infinitesimals,
nor whiggishly subscribed to the new orthodoxy of the "great triumvirate" of
Cantor, Dedekind, and Weierstrass that declared infinitesimals conceptus
nongrati in mathematical discourse. Rather, following Cohen's lead, the Marburg
philosophers sought to clarify Leibniz's principle of continuity, and to
exploit it in making sense of infinitesimals and related concepts.


title:
On multi soliton solutions of the Sine-Gordon equation in more than one
  space dimension

abstract:
  The (1+1)-dimensional Sine-Gordon equation passes integrability tests
commonly applied to nonlinear evolution equations. Its soliton solutions are
obtained by a Hirota algorithm. In higher space-dimensions, the equation does
not pass these tests. In this paper, using no more than the relativistic
kinematics of the tachyonic momentum vectors, from which the soliton solutions
are constructed through the Hirota algorithm, the existence and classification
of N-soliton solutions of the (1+2)- and (1+3)-dimensional equations for all N
greater than or equal to 1 are presented. In (1+2) dimensions, each
multisoliton solution propagates rigidly at one velocity. The solutions are
divided into two subsets: Solutions whose velocities are lower than the speed
of light (c = 1), or are greater than or equal to c.
  In (1+3)-dimensions, multisoliton solutions are characterized by spatial
structure and velocity composition. The spatial structure is either planar
(rotated (1+2)-dimensional solutions), or genuinely three-dimensional - branes.
Some solutions, planar or branes, propagate rigidly at one velocity, which is
lower than, equal to, or higher than c. A subset of the branes contains
hybrids, in which different clusters of solitons propagate at different
velocities. Some velocities may be lower than c but some must be equal to, or
greater than c. Finally, the speed of light cannot be approached from within
the subset of slower-than-light solutions in both (1+2) and (1+3) dimensions.


title:
Magnetic topology and current channels in plasmas with toroidal current
  density inversions

abstract:
  The equilibrium magnetic field inside axisymmetric plasmas with inversions on
the toroidal current density is studied. Structurally stable non-nested
magnetic surfaces are considered. For any inversion in the internal current
density the magnetic families define several positive current channels about a
central negative one. A general expression relating the positive and negative
currents is derived in terms of a topological anisotropy parameter. Next, an
analytical local solution for the poloidal magnetic flux is derived and shown
compatible with current hollow magnetic pitch measurements shown in the
literature. Finally, the analytical solution exhibits non-nested magnetic
families with positive anisotropy, indicating that the current inside the
positive channels have at least twice the magnitude of the central one.


title:
A note on a Bayesian nonparametric estimator of the discovery
  probability

abstract:
  Favaro, Lijoi, and Pruenster (2012, Biometrics, 68, 1188--1196) derive a
novel Bayesian nonparametric estimator of the probability of detecting at the
$(n+m+1)$th observation a species already observed with any given frequency in
an enlarged sample of size $n+m$, conditionally on a basic sample of size $n$.
Unfortunately the general result under Gibbs priors (Theorem 2), and
consequently the explicit result under $(\alpha, \theta)$ Poisson-Dirichlet
priors (Proposition 3), appear to be wrong. Here we provide the correct
formulas for both the results, obtained by means of a new technique devised in
Cerquetti (2013). We verify the correctness of our derivation by an explicit
counterproof for the two-parameter Poisson-Dirichlet case.


title: Time delayed laser networks: phase versus chaos synchronization

abstract:
  The synchronization of chaotic lasers and the optical phase synchronization
of light originating in multiple coupled lasers have both been extensively
studied, however, the interplay between these two phenomena, especially at the
network level is unexplored. Here we experimentally compare chaos
synchronization of laser networks with heterogeneous coupling delay times to
phase synchronization of similar networks. While chaotic lasers exhibit
deterioration in synchronization as the network time delay heterogeneity
increases, phase synchronization is found to be independent of heterogeneity.
The experimental results are found to be in agreement with numerical
simulations for semiconductor lasers.


title: CCQE, 2p2h excitations and \nu-energy reconstruction

abstract:
  We analyze the MiniBooNE muon neutrino CCQE-like
d\sigma/dT_\mu/dcos\theta_\mu data using a theoretical model that, among other
nuclear effects, includes RPA correlations and 2p2h (multinucleon) mechanisms.
These corrections turn out to be essential for the description of the data. We
find that MiniBooNE CCQE-like data are fully compatible with former
determinations of the nucleon axial mass M_A ~ 1.05 GeV. This is in sharp
contrast with several previous analysis where anomalously large values of M_A ~
1.4 GeV have been suggested. We also show that because of the the multinucleon
mechanism effects, the algorithm used to reconstruct the neutrino energy is not
adequate when dealing with quasielastic-like events. Finally, we analyze the
MiniBooNE unfolded cross section, and show that it exhibits an excess (deficit)
of low (high) energy neutrinos, which is an artifact of the unfolding process
that ignores 2p2h mechanisms.


title:
A Fixed Point Theorem and Equilibria of Abstract Economies with w-Upper
  Semicontinuous Set-Valued Maps

abstract:
  We introduce the notion of w-upper semicontinuous set valued maps and give a
new fixed-point theorem. We also introduce the notion of set valued maps with
e-USS-property. These results can be applied to obtain some new equilibrium
theorems for abstract economies.


title: Study on a Phase Space Representation of Quantum Theory

abstract:
  A study on a method for the establishment of a phase space representation of
quantum theory is presented. The approach utilizes the properties of Gaussian
distribution, the properties of Hermite polynomials, Fourier analysis and the
current formulation of quantum mechanics which is based on the use of Hilbert
space and linear operators theory. Phase space representation of quantum states
and wave functions in phase space are introduced using properties of a set of
functions called harmonic Gaussian functions. Then, new operators called
dispersion operators are defined and identified as the operators which admit as
eigenstates the basis states of the phase space representation. Generalization
of the approach for multidimensional cases is shown. Examples of applications
are given.


title: On Carnot algebra with the growth vector (2,3,5,8)

abstract:
  We compute two vector field models of the Carnot algebra with the growth
vector (2,3,5,8), and an infinitesimal symmetry of the corresponding
sub-Riemannian structure.


title: Phase transitions in the Ramsey-Tur\'an theory

abstract:
  Let $f(n)$ be a function and $L$ be a graph. Denote by $RT(n,L,f(n))$ the
maximum number of edges of an $L$-free graph on $n$ vertices with independence
number less than $f(n)$. Erd\H os and S\'os asked if $RT\left(n, K_5,
c\sqrt{n}\right) = o(n^2)$ for some constant $c$. We answer this question by
proving the stronger $RT\left(n, K_5, o\left(\sqrt{n\log n}\right)\right) =
o(n^2)$. It is known that $RT \left(n, K_5, c \sqrt{n\log n} \right) =
n^2/4+o(n^2)$ for $c>1$, so one can say that $K_5$ has a Ramsey-Tur\'an phase
transition at $c\sqrt{n\log n}$. We extend this result to several other $K_s$'s
and functions $f(n)$, determining many more phase transitions. We shall
formulate several open problems, in particular, whether variants of the
Bollob\'as-Erd\H os graph exist to give good lower bounds on $RT\left(n, K_s,
f(n)\right)$ for various pairs of $s$ and $f(n)$. Among others, we use
Szemer\'edi's Regularity Lemma and the Hypergraph Dependent Random Choice
Lemma. We also present a short proof of the fact that $K_s$-free graphs with
small independence number are sparse.


title:
Correlation functions in liquids and crystals : Free energy functional
  and liquid - crystal transition

abstract:
  A free energy functional for a crystal that contains both the symmetry
conserved and symmetry broken parts of the direct pair correlation function has
been used to investigate the crystallization of fluids in three-dimensions. The
symmetry broken part of the direct pair correlation function has been
calculated using a series in ascending powers of the order parameters and which
contains three- and higher-bodies direct correlation functions of the isotropic
phase. It is shown that a very accurate description of freezing transitions for
a wide class of potentials is found by considering the first two terms of this
series. The results found for freezing parameters including structure of the
frozen phase for fluids interacting via the inverse power potential u(r) =
\epsilon (\sigma/r)^{n} for n ranging from 4 to \infty are in very good
agreement with simulation results. It is found that for n > 6.5 the fluid
freezes into a face centred cubic (fcc) structure while for n \leq 6 the body
centred cubic (bcc) structure is preferred. The fluid-bcc-fcc triple point is
found to be at 1/n = 0.158 which is in good agreement with simulation result.


title: Asymmetric Diamond Ising--Hubbard Chain with Attraction

abstract:
  The ground state and thermodynamic properties of an asymmetric diamond
Ising--Hubbard chain with the on-site electron-electron attraction has been
considered. The problem can be solved exactly using the decoration-iteration
transformation. In the case of the antiferromagnetic Ising interaction, the
influence of this attraction on the ground state and the temperature
dependences of the magnetization, magnetic susceptibility, and specific heat
has been studied.


title:
Environmental structure and competitive scoring advantages in team
  competitions

abstract:
  In most professional sports, the structure of the environment is kept neutral
so that scoring imbalances may be attributed to differences in team skill. It
thus remains unknown what impact structural heterogeneities can have on scoring
dynamics and producing competitive advantages. Applying a generative model of
scoring dynamics to roughly 10 million team competitions drawn from an online
game, we quantify the relationship between a competition's structure and its
scoring dynamics. Despite wide structural variations, we find the same
three-phase pattern in the tempo of events observed in many sports. Tempo and
balance are highly predictable from a competition's structural features alone
and teams exploit environmental heterogeneities for sustained competitive
advantage. The most balanced competitions are associated with specific
environmental heterogeneities, not from equally skilled teams. These results
shed new light on the principles of balanced competition, and illustrate the
potential of online game data for investigating social dynamics and
competition.

categories: physics.soc-ph cs.SI physics.data-an stat.AP


title: Theory of Fast Electron Transport for Fast Ignition

abstract:
  Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in
which DT fuel is first compressed to high density and then ignited by a
relativistic electron beam generated by a fast (< 20 ps) ultra-intense laser
pulse, which is usually brought in to the dense plasma via the inclusion of a
re-entrant cone. The transport of this beam from the cone apex into the dense
fuel is a critical part of this scheme, as it can strongly influence the
overall energetics. Here we review progress in the theory and numerical
simulation of fast electron transport in the context of Fast Ignition.
Important aspects of the basic plasma physics, descriptions of the numerical
methods used, a review of ignition-scale simulations, and a survey of schemes
for controlling the propagation of fast electrons are included. Considerable
progress has taken place in this area, but the development of a robust,
high-gain FI `point design' is still an ongoing challenge.


title: On the size, shape, and density of dwarf planet Makemake

abstract:
  A recent stellar occultation by dwarf planet Makemake provided an excellent
opportunity to measure the size and shape of one of the largest objects in the
Kuiper belt. The analysis of these results provided what were reported to be
precise measurements of the lengths of the projected axes, the albedo, and even
the density of Makemake, but these results were, in part, derived from
qualitative arguments. We reanalyzed the occultation timing data using a
quantitative statistical description, and, in general, find the previously
reported results on the shape of Makemake to be unjustified. In our solution,
in which we use our inference from photometric data that Makemake is being
viewed nearly pole-on, we find a 1 sigma upper limit to the projected
elongation of Makemake of 1.02, with measured equatorial diameter of 1434 +/-
14 km and a projected polar diameter of 1422 +/- 14 km, yielding an albedo of
0.81+0.01/-0.02$. If we remove the external constraint on the pole position of
Makemake, we find instead a 1 sigma upper limit to the elongation of 1.06, with
a measured equatorial diameter of 1434+48/-18 km and a projected polar diameter
of 1420+18/-24 km, yielding an albedo of 0.81+0.03/-0.05. Critically, we find
that the reported measurement of the density of Makemake was based on the
misapplication of the volatile retention models. A corrected analysis shows
that the occultation measurements provide no meaningful constraint on the
density of Makemake.


title: Probing Non-Standard Interaction of Neutrinos with IceCube and DeepCore

abstract:
  We consider effects of the Non-Standard Interactions (NSI) on oscillations of
the high energy atmospheric neutrinos. The \nu_\mu-oscillograms are constructed
and their dependence on the NSI strength parameters \epsilon_{\alpha \beta}
studied. We computed zenith angle distributions of the \nu_\mu-events in the
presence of NSI in different energy regions. The distributions are confronted
with the IceCube-79 (high energy sample) and the DeepCore (low energy sample)
data and constraints on the strength parameters |\epsilon_{\mu \tau}| < 6x10^-3
and |\epsilon_{\mu\mu}-\epsilon_{\tau\tau}| < 3x10^-2 (90% C.L.) have been
obtained. Future measurements of the zenith angle distributions by DeepCore in
smaller energy bins will allow to improve the bounds by factor 2 - 3. We
discuss the signatures of NSI in zenith angle and energy distributions of
events which allow to discriminate them from the effects of sterile neutrinos.


title:
Solutions of the Pell equations x^2-(a^2+2a)y^2=N via generalized
  Fibonacci and Lucas numbers

abstract:
  In this study, we find continued fraction expansion of sqrt(d) when d=a^2+2a
where a is positive integer. We consider the integer solutions of the Pell
equation x^2-(a^2+2a)y^2=N when N={-1,+1,-4,+4}. We formulate the n-th solution
(x_{n},y_{n}) by using the continued fraction expansion. We also formulate the
n-th solution (x_{n},y_{n}) via the generalized Fibonacci and Lucas sequences.


title: Random stable looptrees

abstract:
  We introduce a class of random compact metric spaces L(\alpha) indexed by
\alpha \in (1,2) and which we call stable looptrees. They are made of a
collection of random loops glued together along a tree structure, and can be
informally be viewed as dual graphs of \alpha-stable L\'evy trees. We study
their properties and prove in particular that the Hausdorff dimension of
L(\alpha) is almost surely equal to \alpha. We also show that stable looptrees
are universal scaling limits, for the Gromov-Hausdorff topology, of various
combinatorial models. In a companion paper, we prove that the stable looptree
of parameter 3/2 is the scaling limit of cluster boundaries in critical
site-percolation on large random triangulations.


title:
A Seamless Flow Mobility Management Architecture for Vehicular
  Communication Networks

abstract:
  Vehicular Ad Hoc Networks (VANETs) are self-organizing, self-healing networks
which provide wireless communication among vehicular and roadside devices.
Applications in such networks can take advantage of the use of simultaneous
connections, thereby maximizing the throughput and lowering latency. In order
to take advantage of all radio interfaces of the vehicle and to provide good
quality of service for vehicular applications, we de- veloped a seamless flow
mobility management architecture based on vehicular network application classes
with network-based mobility management. Our goal is to minimize the time of
flow connection exchange in order to comply with the minimum requirements of
vehicular application classes, as well as to maximize their throughput. NS3
simulations were performed to analyse the behaviour of our architecture by
comparing it with other three scenarios. As a result of this work, we observed
that the proposed architecture presented a low handover time, with lower packet
loss and lower delay.


title: Polarization conversion loss in birefringent crystalline resonators

abstract:
  Whispering gallery modes in birefringent crystalline resonators are
investigated. We experimentally investigate the XY--cut resonators made with
LiNbO$_3$, LiTaO$_3$ and BBO and observe strong influence of the resonator's
shape and birefringence on the quality factor of the extraordinary polarized
modes. We show that extraordinary modes can have lower Q and even be suppressed
due to polarization conversion loss. The ordinary ray modes retain the high Q
due to inhibited reflection phenomenon.


title: Analyzing Medium Access Techniques in Wireless Body Area Networks

abstract:
  This paper presents comparison of Access Techniques used in Medium Access
Control (MAC) protocol for Wireless Body Area Networks (WBANs). Comparison is
performed between Time Division Multiple Access (TDMA), Frequency Division
Multiple Access (FDMA), Carrier Sense Multiple Access with Collision Avoidance
(CSMA/CA), Pure ALOHA and Slotted ALOHA (S-ALOHA). Performance metrics used for
comparison are Throughput (T), Delay (D) and Offered Load (G). The main goal
for comparison is to show which technique gives highest Throughput and lowest
Delay with increase in Load. Energy efficiency is major issue in WBAN that is
why there is need to know which technique performs best for energy conservation
and also gives minimum delay. Simulations are performed for different scenarios
and results are compared for all techniques. We suggest TDMA as best technique
to be used in MAC protocol for WBANs due to its high throughput and minimum
delay with increase in load. MATLAB is the tool that is used for simulation.


title: On the co-orbital motion of two planets in quasi-circular orbits

abstract:
  We develop an analytical Hamiltonian formalism adapted to the study of the
motion of two planets in co-orbital resonance. The Hamiltonian, averaged over
one of the planetary mean longitude, is expanded in power series of
eccentricities and inclinations. The model, which is valid in the entire
co-orbital region, possesses an integrable approximation modeling the planar
and quasi-circular motions. First, focusing on the fixed points of this
approximation, we highlight relations linking the eigenvectors of the
associated linearized differential system and the existence of certain
remarkable orbits like the elliptic Eulerian Lagrangian configurations, the
Anti-Lagrange (Giuppone et al., 2010) orbits and some second sort orbits
discovered by Poincar\'e. Then, the variational equation is studied in the
vicinity of any quasi-circular periodic solution. The fundamental frequencies
of the trajectory are deduced and possible occurrence of low order resonances
are discussed. Finally, with the help of the construction of a Birkhoff normal
form, we prove that the elliptic Lagrangian equilateral configurations and the
Anti-Lagrange orbits bifurcate from the same fixed point L4.


title: Onsager's conjecture almost everywhere in time

abstract:
  In recent work by Isett (arXiv:1211.4065), and later by Buckmaster, De
Lellis, Isett and Sz\'ekelyhidi Jr. (arXiv:1302.2815), iterative schemes where
presented for constructing solutions belonging to the H\"older class
$C^{1/5-\epsilon}$ of the 3D incompressible Euler equations which do not
conserve energy. The cited work is partially motivated by a conjecture of Lars
Onsager in 1949 relating to the existence of $C^{1/3-\epsilon}$ solutions to
the Euler equations which dissipate energy. In this note we show how the later
scheme can be adapted in order to prove the existence of non-trivial H\"older
continuous solutions which for almost every time belong to the critical Onsager
H\"older regularity $C^{1/3-\epsilon}$ and have compact temporal support.


title:
Molybdenum, Ruthenium, and the Heavy r-process Elements in Moderately
  Metal-Poor Main-Sequence Turnoff Stars

abstract:
  The ratios of elemental abundances observed in metal-poor stars of the
Galactic halo provide a unique present-day record of the nucleosynthesis
products of its earliest stars. While the heaviest elements were synthesized by
the r- and s-processes, dominant production mechanisms of light trans-ironic
elements were obscure until recently. This work investigates further our 2011
conclusion that the low-entropy regime of a high-entropy wind (HEW) produced
molybdenum and ruthenium in two moderately metal-poor turnoff stars that showed
extreme overabundances of those elements with respect to iron. Only a few, rare
nucleosynthesis events may have been involved.
  Here we determine abundances for Mo, Ru, and other trans-Fe elements for 28
similar stars by matching spectral calculations to well-exposed near-UV Keck
HIRES spectra obtained for beryllium abundances. In each of the 26 turnoff
stars with Mo or Ru line detections and no evidence for s-process production
(therefore old), we find Mo and Ru to be three to six times overabundant. In
contrast, the maximum overabundance is reduced to factors of three and two for
the neighboring elements zirconium and palladium. Since the overproduction
peaks sharply at Mo and Ru, a low-entropy HEW is confirmed as its origin.
  The overabundance level of the heavy r-process elements varies significantly,
from none to a factor of four, but is uncorrelated with Mo and Ru
overabundances. Despite their moderate metallicity, stars in this group trace
the products of different nucleosynthetic events: possibly very few events,
possibly events whose output depended on environment, metallicity, or time.


title:
Reply to the Comment on "Optimal working conditions for thermoelectric
  generators with realistic thermal coupling" by S. Su et al

abstract:
  We reply to the comment made by Su et al. on "Optimal working conditions for
thermoelectric generators with realistic thermal coupling". In particular we
justify the efficiency definition used in the main paper.


title: The decay of the Walsh coefficients of smooth functions

abstract:
  We give upper bounds on the Walsh coefficients of functions for which the
derivative of order at least one has bounded variation of fractional order.
Further, we also consider the Walsh coefficients of functions in periodic and
non-periodic reproducing kernel Hilbert spaces. A lower bound which shows that
our results are best possible is also shown.


title: Integral Brauer-Manin obstructions for sums of two squares and a power

abstract:
  We use Brauer-Manin obstructions to explain failures of the integral Hasse
principle and strong approximation away from infinity for the equation
x^2+y^2+z^k=m with fixed integers k>=3 and m. Under Schinzel's hypothesis (H),
we prove that Brauer-Manin obstructions corresponding to specific Azumaya
algebras explain all failures of strong approximation away from infinity at the
variable z. Finally, we present an algorithm that, again under Schinzel's
hypothesis (H), finds out whether the equation has any integral solutions.


title: Senescent fibroblasts can drive melanoma initiation and progression

abstract:
  Skin is one of the largest human organ systems whose primary purpose is the
protection of deeper tissues. As such, the skin must maintain a homeostatic
balance in the face of many microenvironmental and genetic perturbations. At
its simplest, skin homeostasis is maintained by the balance between skin cell
growth and death such that skin architecture is preserved. This study presents
a hybrid multiscale mathematical model of normal skin (vSkin). The model
focuses on key cellular and microenvironmental variables that regulate
homeostatic interactions among keratinocytes, melanocytes and fibroblasts, key
components of the skin. The model recapitulates normal skin structure, and is
robust enough to withstand physical as well as biochemical perturbations.
Furthermore, the vSkin model revealed the important role of the skin
microenvironment in melanoma initiation and progression. Our experiments showed
that dermal fibroblasts, which are an important source of growth factors in the
skin, adopt a phenotype that facilitates cancer cell growth and invasion when
they become senescent. Based on these experimental results, we incorporated
senescent fibroblasts into vSkin model and showed that senescent fibroblasts
transform the skin microenvironment and enhance the growth and invasion of
normal melanocytes as well as early stage melanoma cells. These predictions are
consistent with our experimental results as well as clinical observations. Our
co-culture experiments show that the senescent fibroblasts promote the growth
and invasion of non-tumorigenic melanoma cells. We also observed increased
proteolytic activity in stromal fields adjacent to melanoma lesions in human
histology. Collectively, senescent fibroblasts create a pro-oncogenic
environment that synergizes with mutations to drive melanoma initiation and
progression and should therefore be considered as a potential future
therapeutic target.


title:
Coupled systems of fractional equations related to sound propagation:
  analysis and discussion

abstract:
  In this note we analyse the propagation of a small density perturbation in a
one-dimensional compressible fluid by means of fractional calculus modelling,
replacing thus the ordinary time derivative with the Caputo fractional
derivative in the constitutive equations. By doing so, we embrace a vast
phenomenology, including subdiffusive, superdiffusive and also memoryless
processes like classical diffusions. From a mathematical point of view, we
study systems of coupled fractional equations, leading to fractional diffusion
equations or to equations with sequential fractional derivatives. In this
framework we also propose a method to solve partial differential equations with
sequential fractional derivatives by analysing the corresponding coupled system
of equations.


title:
Analytic solutions of fractional differential equations by operational
  methods

abstract:
  We describe a general operational method that can be used in the analysis of
fractional initial and boundary value problems with additional analytic
conditions. As an example, we derive analytic solutions of some fractional
generalisation of differential equations of mathematical physics. Fractionality
is obtained by substituting the ordinary integer-order derivative with the
Caputo fractional derivative. Furthermore, operational relations between
ordinary and fractional differentiation are shown and discussed in detail.
Finally, a last example concerns the application of the method to the study of
a fractional Poisson process.


title:
Fractional calculus modelling for unsteady unidirectional flow of
  incompressible fluids with time-dependent viscosity

abstract:
  In this note we analyze a model for a unidirectional unsteady flow of a
viscous incompressible fluid with time dependent viscosity. A possible way to
take into account such behaviour is to introduce a memory formalism, including
thus the time dependent viscosity by using an integro-differential term and
therefore generalizing the classical equation of a Newtonian viscous fluid. A
possible useful choice, in this framework, is to use a rheology based on
stress/strain relation generalized by fractional calculus modelling. This is a
model that can be used in applied problems, taking into account a power law
time variability of the viscosity coefficient. We find analytic solutions of
initial value problems in an unbounded and bounded domain. Furthermore, we
discuss the explicit solution in a meaningful particular case.


title: On Some Operators Involving Hadamard Derivatives

abstract:
  In this paper we introduce a novel Mittag--Leffler-type function and study
its properties in relation to some integro-differential operators involving
Hadamard fractional derivatives or Hyper-Bessel-type operators. We discuss then
the utility of these results to solve some integro-differential equations
involving these operators by means of operational methods. We show the
advantage of our approach through some examples. Among these, an application to
a modified Lamb--Bateman integral equation is presented.


title: Analyzing Delay in Wireless Multi-hop Heterogeneous Body Area Networks

abstract:
  With increase in ageing population, health care market keeps growing. There
is a need for monitoring of health issues. Wireless Body Area Network (WBAN)
consists of wireless sensors attached on or inside human body for monitoring
vital health related problems e.g, Electro Cardiogram (ECG), Electro
Encephalogram (EEG), ElectronyStagmography (ENG) etc. Due to life threatening
situations, timely sending of data is essential. For data to reach health care
center, there must be a proper way of sending data through reliable connection
and with minimum delay. In this paper transmission delay of different paths,
through which data is sent from sensor to health care center over heterogeneous
multi-hop wireless channel is analyzed. Data of medical related diseases is
sent through three different paths. In all three paths, data from sensors first
reaches ZigBee, which is the common link in all three paths. Wireless Local
Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX),
Universal Mobile Telecommunication System (UMTS) are connected with ZigBee.
Each network (WLAN, WiMAX, UMTS) is setup according to environmental
conditions, suitability of device and availability of structure for that
device. Data from these networks is sent to IP-Cloud, which is further
connected to health care center. Delay of data reaching each device is
calculated and represented graphically. Main aim of this paper is to calculate
delay of each link in each path over multi-hop wireless channel.


title: Catalytic Coherence

abstract:
  Due to conservation of energy we cannot directly turn a quantum system with a
definite energy into a superposition of different energies. However, if we have
access to an additional resource in terms of a system with a high degree of
coherence, as for standard models of laser light, we can overcome this
limitation. The question is to what extent coherence gets degraded when
utilized. Here it is shown that coherence can be turned into a catalyst,
meaning that we can use it repeatedly without ever diminishing its power to
enable coherent operations. This finding stands in contrast to the degradation
of other quantum resources, and has direct consequences for quantum
thermodynamics, as it shows that latent energy that may be locked into
superpositions of energy eigenstates can be released catalytically.


title:
Model for the resistance force acting on circular bodies in the
  imminence of rolling

abstract:
  The laws of friction are reasonably well understood for the case of blocks in
contact with rough plane surfaces. However, as far as bodies with circular
sections are concerned, the physics of friction becomes more involving and it
is not possible to adopt a simple conceptual framework to explain all
phenomena. In particular, there is no approach so far to the problem of the
resistance force that opposes to circular bodies that remain at rest while
acted upon by small forces. Here we fill this gap by introducing a mechanical
model based on both the elasticity theory and Hertz contact mechanics. Our
approach furnishes a quantitative expression for the critical force beyond
which rest can no longer be maintained. Besides confirming the expected
proportionality of the resistance force with the load, our result contains no
free parameters and is expressed solely in terms of physical properties of the
problem, such as the pressure of the body per unit of superficial area, a
relation between the Young modulus of the surface and its Poisson ratio, and
the symmetry of the contact.


title: Heegaard Floer homology and rational cuspidal curves

abstract:
  We apply the methods of Heegaard Floer homology to identify topological
properties of complex curves in the complex projective plane. As one
application, we resolve an open conjecture that constrains the Alexander
polynomial of the link of the singular point of the curve in the case that
there is exactly one singular point, having connected link, and the curve is of
genus 0. Generalizations apply in the case of multiple singular points.


title: Chasing the k-colorability threshold

abstract:
  Over the past decade, physicists have developed deep but non-rigorous
techniques for studying phase transitions in discrete structures. Recently,
their ideas have been harnessed to obtain improved rigorous results on the
phase transitions in binary problems such as random $k$-SAT or $k$-NAESAT
(e.g., Coja-Oghlan and Panagiotou: STOC 2013). However, these rigorous
arguments, typically centered around the second moment method, do not extend
easily to problems where there are more than two possible values per variable.
The single most intensely studied example of such a problem is random graph
$k$-coloring. Here we develop a novel approach to the second moment method in
this problem. This new method, inspired by physics conjectures on the geometry
of the set of $k$-colorings, allows us to establish a substantially improved
lower bound on the $k$-colorability threshold. The new lower bound is within an
additive $2\ln 2+o_k(1)\approx 1.39$ of a simple first-moment upper bound and
within $2\ln 2-1+o_k(1)\approx 0.39$ of the physics conjecture. By comparison,
the best previous lower bound left a gap of about $2+\ln k$, unbounded in terms
of the number of colors [Achlioptas, Naor: STOC 2004].


title:
Increased mode instability thresholds of fiber amplifiers by gain
  saturation

abstract:
  We show by numerical modeling that saturation of the population inversion
reduces the stimulated thermal Rayleigh gain relative to the laser gain in
large mode area fiber amplifiers. We show how to exploit this effect to raise
mode instability thresholds by a substantial factor. We also demonstrate that
when suppression of stimulated Brillouin scattering and the population
saturation effect are both taken into account, counter-pumped amplifiers have
higher mode instability thresholds than co-pumped amplifiers for fully
Yb$^{3+}$ doped cores, and confined doping can further raise the thresholds.


title: Lepton flavor mixing in the Wolfenstein scheme

abstract:
  We mimic the Wolfenstein scheme of quark flavor mixing to describe neutrino
oscillations in the standard model. We identify the parameter $\lambda$ with
the experimentally measured value of the mixing element responsible for
atmospheric neutrino oscillations. The matrix elements responsible for solar
neutrino oscillations and the Chooz angle are taken to be proportional to
$\lambda^2$ and $\lambda^3$, respectively. Using present world average data on
neutrinos, we derive bounds on the other parameters $A$, $\rho$, and $\eta$, of
the new scheme.


title: An Improved LR-aided K-Best Algorithm for MIMO Detection

abstract:
  Recently, lattice reduction (LR) technique has caught great attention for
multi-input multi-output (MIMO) receiver because of its low complexity and high
performance. However, when the number of antennas is large, LR-aided linear
detectors and successive interference cancellation (SIC) detectors still
exhibit considerable performance gap to the optimal maximum likelihood detector
(MLD). To enhance the performance of the LR-aided detectors, the LR-aided
K-best algorithm was developed at the cost of the extra complexity on the order
$\mathcal{O}(N_t^2 K + N_t K^2)$, where $N_t$ is the number of transmit
antennas and $K$ is the number of candidates. In this paper, we develop an
LR-aided K-best algorithm with lower complexity by exploiting a priority queue.
With the aid of the priority queue, our analysis shows that the complexity of
the LR-aided K-best algorithm can be further reduced to $\mathcal{O}(N_t^2 K +
N_t K {\rm log}_2(K))$. The low complexity of the proposed LR-aided K-best
algorithm allows us to perform the algorithm for large MIMO systems (e.g.,
50x50 MIMO systems) with large candidate sizes. Simulations show that as the
number of antennas increases, the error performance approaches that of AWGN
channel.


title:
Collective allocation of science funding: from funding agencies to
  scientific agency

abstract:
  Public agencies like the U.S. National Science Foundation (NSF) and the
National Institutes of Health (NIH) award tens of billions of dollars in annual
science funding. How can this money be distributed as efficiently as possible
to best promote scientific innovation and productivity? The present system
relies primarily on peer review of project proposals. In 2010 alone, NSF
convened more than 15,000 scientists to review 55,542 proposals. Although
considered the scientific gold standard, peer review requires significant
overhead costs, and may be subject to biases, inconsistencies, and oversights.
We investigate a class of funding models in which all participants receive an
equal portion of yearly funding, but are then required to anonymously donate a
fraction of their funding to peers. The funding thus flows from one participant
to the next, each acting as if he or she were a funding agency themselves. Here
we show through a simulation conducted over large-scale citation data (37M
articles, 770M citations) that such a distributed system for science may yield
funding patterns similar to existing NIH and NSF distributions, but may do so
at much lower overhead while exhibiting a range of other desirable features.
Self-correcting mechanisms in scientific peer evaluation can yield an efficient
and fair distribution of funding. The proposed model can be applied in many
situations in which top-down or bottom-up allocation of public resources is
either impractical or undesirable, e.g. public investments, distribution
chains, and shared resource management.


title: Nanometer scale quantum thermometry in a living cell

abstract:
  Sensitive probing of temperature variations on nanometer scales represents an
outstanding challenge in many areas of modern science and technology. In
particular, a thermometer capable of sub-degree temperature resolution as well
as integration within a living system could provide a powerful new tool for
many areas of biological research, including temperature-induced control of
gene expression and cell-selective treatment of disease. Here, we demonstrate a
new approach to nanoscale thermometry that utilizes coherent manipulation of
the electronic spin associated with nitrogen-vacancy (NV) color centers in
diamond. We show the ability to detect temperature variations down to 1.8 mK
(sensitivity of 9 mK/sqrt(Hz)) in an ultra-pure bulk diamond sample. Using NV
centers in diamond nanocrystals (nanodiamonds), we directly measure the local
thermal environment at length scales down to 200 nm. Finally, by introducing
both nanodiamonds and gold nanoparticles into a single human embryonic
fibroblast, we demonstrate temperature-gradient control and mapping at the
sub-cellular level, enabling unique potential applications in life sciences.


title: The C0 general density theorem for geodesic flows

abstract:
  Given a closed Riemannian manifold, we prove the C0-general density theorem
for continuous geodesic flows. More precisely, that there exists a residual (in
the C0-sense) subset of the continuous geodesic flows such that, in that
residual subset, the geodesic flow exhibits dense closed orbits.


title: Differential operators on non-commutative algebras

abstract:
  There is a relatively well-known description of the algebra of (higher order)
left differential operators on commutative algebras. This note gives a
construction of similar flavor for algebras of differential operators on not
necessarily commutative algebras.


title: Alternating knots, planar graphs and q-series

abstract:
  Recent advances in Quantum Topology assign $q$-series to knots in at least
three different ways. The $q$-series are given by generalized Nahm sums (i.e.,
special $q$-hypergeometric sums) and have unknown modular and asymptotic
properties. We give an efficient method to compute those $q$-series that come
from planar graphs (i.e., reduced Tait graphs of alternating links) and compute
several terms of those series for all graphs with at most 8 edges drawing
several conclusions. In addition, we give a graph-theory proof of a theorem of
Dasbach-Lin which identifies the coefficient of $q^k$ in those series for
$k=0,1,2$ in terms of polynomials on the number of vertices, edges and
triangles of the graph. Updated tables of data.


title:
Massively Parallel RNA Chemical Mapping with a Reduced Bias MAP-seq
  Protocol

abstract:
  Chemical mapping methods probe RNA structure by revealing and leveraging
correlations of a nucleotide's structural accessibility or flexibility with its
reactivity to various chemical probes. Pioneering work by Lucks and colleagues
has expanded this method to probe hundreds of molecules at once on an Illumina
sequencing platform, obviating the use of slab gels or capillary
electrophoresis on one molecule at a time. Here, we describe optimizations to
this method from our lab, resulting in the MAP-seq protocol (Multiplexed
Accessibility Probing read out through sequencing), version 1.0. The protocol
permits the quantitative probing of thousands of RNAs at once, by several
chemical modification reagents, on the time scale of a day using a table-top
Illumina machine. This method and a software package MAPseeker
(http://simtk.org/home/map_seeker) address several potential sources of bias,
by eliminating PCR steps, improving ligation efficiencies of ssDNA adapters,
and avoiding problematic heuristics in prior algorithms. We hope that the
step-by-step description of MAP-seq 1.0 will help other RNA mapping
laboratories to transition from electrophoretic to next-generation sequencing
methods and to further reduce the turnaround time and any remaining biases of
the protocol.


title: A New Theorem on N-th Order Differential Equation with Retarded Argument

abstract:
  In this work, using the well-known mean-value theorem (Lagrange's theorem) we
obtain an inequality for n-th order differential equations with retarded
argument. If the retarded argument vanishes then the inequality turns to an
inequality for n-th order ordinary differential equations which plays a vital
role in the proof of existence theorem for n-th order ordinary differential
equations.


title:
Kolmogorov's strong law of large numbers in game-theoretic probability:
  Reality's side

abstract:
  The game-theoretic version of Kolmogorov's strong law of large numbers says
that Skeptic has a strategy forcing the statement of the law in a game of
prediction involving Reality, Forecaster, and Skeptic. This note describes a
simple matching strategy for Reality.


title: The core of games on ordered structures and graphs

abstract:
  In cooperative games, the core is the most popular solution concept, and its
properties are well known. In the classical setting of cooperative games, it is
generally assumed that all coalitions can form, i.e., they are all feasible. In
many situations, this assumption is too strong and one has to deal with some
unfeasible coalitions. Defining a game on a subcollection of the power set of
the set of players has many implications on the mathematical structure of the
core, depending on the precise structure of the subcollection of feasible
coalitions. Many authors have contributed to this topic, and we give a unified
view of these different results.


title: Pure spinors, intrinsic torsion and curvature in odd dimensions

abstract:
  We study the geometric properties of a $(2m+1)$-dimensional complex manifold
$\mathcal{M}$ admitting a holomorphic reduction of the frame bundle to the
structure group $P \subset \mathrm{Spin}(2m+1,\mathbb{C})$, the stabiliser of
the line spanned by a pure spinor at a point. Geometrically, $\mathcal{M}$ is
endowed with a holomorphic metric $g$, a holomorphic volume form, a spin
structure compatible with $g$, and a holomorphic pure spinor field $\xi$ up to
scale. The defining property of $\xi$ is that it determines an almost null
structure, i.e.\ an $m$-plane distribution $\mathcal{N}_\xi$ along which $g$ is
totally degenerate.
  We develop a spinor calculus, by means of which we encode the geometric
properties of $\mathcal{N}_\xi$ and of its rank-$(m+1)$ orthogonal complement
$\mathcal{N}_\xi^\perp$ corresponding to the algebraic properties of the
intrinsic torsion of the $P$-structure. This is the failure of the Levi-Civita
connection $\nabla$ of $g$ to be compatible with the $P$-structure. In a
similar way, we examine the algebraic properties of the curvature of $\nabla$.
  Applications to spinorial differential equations are given. Notably, we
relate the integrability properties of $\mathcal{N}_\xi$ and
$\mathcal{N}_\xi^\perp$ to the existence of solutions of odd-dimensional
versions of the zero-rest-mass field equation. We give necessary and sufficient
conditions for the almost null structure associated to a pure conformal Killing
spinor to be integrable. Finally, we conjecture a Goldberg--Sachs-type theorem
on the existence of a certain class of almost null structures when
$(\mathcal{M},g)$ has prescribed curvature.
  We discuss applications of this work to the study of real pseudo-Riemannian
manifolds.


title: Softly Constrained Films

abstract:
  The shape of materials is often subject to a number of geometric constraints
that limit the size of the system or fix the structure of its boundary. In soft
and biological materials, however, these constraints are not always hard, but
are due to other physical mechanisms that affect the overall force balance. A
capillary film spanning a flexible piece of wire or a cell anchored to a
compliant substrate by mean of adhesive contacts are examples of these softly
constrained systems in the macroscopic and microscopic world. In this article I
review some of the important mathematical and physical developments that
contributed to our understanding of shape formation in softly constrained films
and their recent application to the mechanics of adherent cells.


title:
Loops and spurs: The angular power spectrum of the Galactic synchrotron
  background

abstract:
  We present a new model of the diffuse Galactic synchrotron radiation,
concentrating on its angular anisotropies. While previous studies have focussed
on either the variation of the emissivity on large (kpc) scales, or on
fluctuations due to MHD turbulence in the interstellar medium, we unify these
approaches to match the angular power spectrum. We note that the usual
turbulence cascade calculation ignores spatial correlations at the injection
scale due to compression of the interstellar medium by old supernova remnants
-- the 'radio loops', only four of which are visible by eye in radio maps. This
new component naturally provides the otherwise missing power on intermediate
and small scales in the all-sky map at 408 MHz. Our model can enable more
reliable subtraction of the synchrotron foreground for studies of CMB
anisotropies (both in temperature and polarisation) or searches for dark matter
annihilation. We conclude with some remarks on the relevance to modelling of
the polarised foreground.


title:
Covariant Renormalizable Modified and Massive Gravity Theories on (Non)
  Commutative Tangent Lorentz Bundles

abstract:
  The fundamental field equations in modified gravity (including general
relativity; massive and bimetric theories; Ho\vrava-Lifshits, HL;
Einstein--Finsler gravity extensions etc) posses an important decoupling
property with respect to nonholonomic frames with 2 (or 3) +2+2+... spacetime
decompositions. This allows us to construct exact solutions with generic
off--diagonal metrics depending on all spacetime coordinates via generating and
integration functions containing (un-) broken symmetry parameters. Such
nonholonomic configurations/ models have a nice ultraviolet behavior and seem
to be ghost free and (super) renormalizable in a sense of covariant and/or
massive modifications of HL gravity. The apparent noncommutativity and breaking
of Lorentz invariance by quantum effects can be encoded into fibers of
noncommutative tangent Lorentz bundles for corresponding "partner"
anisotropically induced theories. We show how the constructions can be extended
to include conjectured covariant reonormalizable models with massive graviton
fields and effective Einstein fields with (non)commutative variables.


title:
Off-Diagonal Ekpyrotic Scenarios and Equivalence of Modified, Massive
  and/or Einstein Gravity

abstract:
  Using our anholonomic frame deformation method, we show how generic
off-diagonal cosmological solutions depending, in general, on all spacetime
coordinates and undergoing a phase of ultra-slow contraction can be constructed
in massive gravity. In this paper, there are found and studied new classes of
locally anisotropic and (in) homogeneous cosmological metrics with open and
closed spatial geometries. The late time acceleration is present due to
effective cosmological terms induced by nonlinear off-diagonal interactions and
graviton mass. The off-diagonal cosmological metrics and related St\" uckelberg
fields are constructed in explicit form up to nonholonomic frame transforms of
the Friedmann-Lama\^itre-Robertson-Walker (FLRW) coordinates. We show that the
solutions include matter, graviton mass and other effective sources modelling
nonlinear gravitational and matter fields interactions in modified and/or
massive gravity, with polarization of physical constants and deformations of
metrics, which may explain certain dark energy and dark matter effects. There
are stated and analyzed the conditions when such configurations mimic
interesting solutions in general relativity and modifications and recast the
general Painlev\'e--ullstrand and FLRW metrics. Finally, we elaborate on a
reconstruction procedure for a subclass of off-diagonal cosmological solutions
which describe cyclic and ekpyrotic universes, with an emphasis on open issues
and observable signatures.


title:
Exploiting Functional Dependencies in Qualitative Probabilistic
  Reasoning

abstract:
  Functional dependencies restrict the potential interactions among variables
connected in a probabilistic network. This restriction can be exploited in
qualitative probabilistic reasoning by introducing deterministic variables and
modifying the inference rules to produce stronger conclusions in the presence
of functional relations. I describe how to accomplish these modifications in
qualitative probabilistic networks by exhibiting the update procedures for
graphical transformations involving probabilistic and deterministic variables
and combinations. A simple example demonstrates that the augmented scheme can
reduce qualitative ambiguity that would arise without the special treatment of
functional dependency. Analysis of qualitative synergy reveals that new
higher-order relations are required to reason effectively about synergistic
interactions among deterministic variables.


title:
Qualitative Propagation and Scenario-based Explanation of Probabilistic
  Reasoning

abstract:
  Comprehensible explanations of probabilistic reasoning are a prerequisite for
wider acceptance of Bayesian methods in expert systems and decision support
systems. A study of human reasoning under uncertainty suggests two different
strategies for explaining probabilistic reasoning: The first, qualitative
belief propagation, traces the qualitative effect of evidence through a belief
network from one variable to the next. This propagation algorithm is an
alternative to the graph reduction algorithms of Wellman (1988) for inference
in qualitative probabilistic networks. It is based on a qualitative analysis of
intercausal reasoning, which is a generalization of Pearl's "explaining away",
and an alternative to Wellman's definition of qualitative synergy. The other,
Scenario-based reasoning, involves the generation of alternative causal
"stories" accounting for the evidence. Comparing a few of the most probable
scenarios provides an approximate way to explain the results of probabilistic
reasoning. Both schemes employ causal as well as probabilistic knowledge.
Probabilities may be presented as phrases and/or numbers. Users can control the
style, abstraction and completeness of explanations.


title: Managing Uncertainty in Rule Based Cognitive Models

abstract:
  An experiment replicated and extended recent findings on psychologically
realistic ways of modeling propagation of uncertainty in rule based reasoning.
Within a single production rule, the antecedent evidence can be summarized by
taking the maximum of disjunctively connected antecedents and the minimum of
conjunctively connected antecedents. The maximum certainty factor attached to
each of the rule's conclusions can be sealed down by multiplication with this
summarized antecedent certainty. Heckerman's modified certainty factor
technique can be used to combine certainties for common conclusions across
production rules.


title: Context-Dependent Similarity

abstract:
  Attribute weighting and differential weighting, two major mechanisms for
computing context-dependent similarity or dissimilarity measures are studied
and compared. A dissimilarity measure based on subset size in the context is
proposed and its metrization and application are given. It is also shown that
while all attribute weighting dissimilarity measures are metrics differential
weighting dissimilarity measures are usually non-metric.


title:
Similarity Networks for the Construction of Multiple-Faults Belief
  Networks

abstract:
  A similarity network is a tool for constructing belief networks for the
diagnosis of a single fault. In this paper, we examine modifications to the
similarity-network representation that facilitate the construction of belief
networks for the diagnosis of multiple coexisting faults.


title:
Integrating Probabilistic, Taxonomic and Causal Knowledge in Abductive
  Diagnosis

abstract:
  We propose an abductive diagnosis theory that integrates probabilistic,
causal and taxonomic knowledge. Probabilistic knowledge allows us to select the
most likely explanation; causal knowledge allows us to make reasonable
independence assumptions; taxonomic knowledge allows causation to be modeled at
different levels of detail, and allows observations be described in different
levels of precision. Unlike most other approaches where a causal explanation is
a hypothesis that one or more causative events occurred, we define an
explanation of a set of observations to be an occurrence of a chain of
causation events. These causation events constitute a scenario where all the
observations are true. We show that the probabilities of the scenarios can be
computed from the conditional probabilities of the causation events. Abductive
reasoning is inherently complex even if only modest expressive power is
allowed. However, our abduction algorithm is exponential only in the number of
observations to be explained, and is polynomial in the size of the knowledge
base. This contrasts with many other abduction procedures that are exponential
in the size of the knowledge base.


title: What is an Optimal Diagnosis?

abstract:
  Within diagnostic reasoning there have been a number of proposed definitions
of a diagnosis, and thus of the most likely diagnosis, including most probable
posterior hypothesis, most probable interpretation, most probable covering
hypothesis, etc. Most of these approaches assume that the most likely diagnosis
must be computed, and that a definition of what should be computed can be made
a priori, independent of what the diagnosis is used for. We argue that the
diagnostic problem, as currently posed, is incomplete: it does not consider how
the diagnosis is to be used, or the utility associated with the treatment of
the abnormalities. In this paper we analyze several well-known definitions of
diagnosis, showing that the different definitions of the most likely diagnosis
have different qualitative meanings, even given the same input data. We argue
that the most appropriate definition of (optimal) diagnosis needs to take into
account the utility of outcomes and what the diagnosis is used for.


title:
Kutato: An Entropy-Driven System for Construction of Probabilistic
  Expert Systems from Databases

abstract:
  Kutato is a system that takes as input a database of cases and produces a
belief network that captures many of the dependence relations represented by
those data. This system incorporates a module for determining the entropy of a
belief network and a module for constructing belief networks based on entropy
calculations. Kutato constructs an initial belief network in which all
variables in the database are assumed to be marginally independent. The entropy
of this belief network is calculated, and that arc is added that minimizes the
entropy of the resulting belief network. Conditional probabilities for an arc
are obtained directly from the database. This process continues until an
entropy-based threshold is reached. We have tested the system by generating
databases from networks using the probabilistic logic-sampling method, and then
using those databases as input to Kutato. The system consistently reproduces
the original belief networks with high fidelity.


title: Ideal Reformulation of Belief Networks

abstract:
  The intelligent reformulation or restructuring of a belief network can
greatly increase the efficiency of inference. However, time expended for
reformulation is not available for performing inference. Thus, under time
pressure, there is a tradeoff between the time dedicated to reformulating the
network and the time applied to the implementation of a solution. We
investigate this partition of resources into time applied to reformulation and
time used for inference. We shall describe first general principles for
computing the ideal partition of resources under uncertainty. These principles
have applicability to a wide variety of problems that can be divided into
interdependent phases of problem solving. After, we shall present results of
our empirical study of the problem of determining the ideal amount of time to
devote to searching for clusters in belief networks. In this work, we acquired
and made use of probability distributions that characterize (1) the performance
of alternative heuristic search methods for reformulating a network instance
into a set of cliques, and (2) the time for executing inference procedures on
various belief networks. Given a preference model describing the value of a
solution as a function of the delay required for its computation, the system
selects an ideal time to devote to reformulation.


title: Computationally-Optimal Real-Resource Strategies

abstract:
  This paper focuses on managing the cost of deliberation before action. In
many problems, the overall quality of the solution reflects costs incurred and
resources consumed in deliberation as well as the cost and benefit of
execution, when both the resource consumption in deliberation phase, and the
costs in deliberation and execution are uncertain and may be described by
probability distribution functions. A feasible (in terms of resource
consumption) strategy that minimizes the expected total cost is termed
computationally-optimal. For a situation with several independent,
uninterruptible methods to solve the problem, we develop a
pseudopolynomial-time algorithm to construct generate-and-test computationally
optimal strategy. We show this strategy-construction problem to be NP-complete,
and apply Bellman's Optimality Principle to solve it efficiently.


title: Problem Formulation as the Reduction of a Decision Model

abstract:
  In this paper, we extend the QMRDT probabilistic model for the domain of
internal medicine to include decisions about treatments. In addition, we
describe how we can use the comprehensive decision model to construct a simpler
decision model for a specific patient. In so doing, we transform the task of
problem formulation to that of narrowing of a larger problem.


title: Dynamic Construction of Belief Networks

abstract:
  We describe a method for incrementally constructing belief networks. We have
developed a network-construction language similar to a forward-chaining
language using data dependencies, but with additional features for specifying
distributions. Using this language, we can define parameterized classes of
probabilistic models. These parameterized models make it possible to apply
probabilistic reasoning to problems for which it is impractical to have a
single large static model.


title: A New Algorithm for Finding MAP Assignments to Belief Networks

abstract:
  We present a new algorithm for finding maximum a-posterior) (MAP) assignments
of values to belief networks. The belief network is compiled into a network
consisting only of nodes with boolean (i.e. only 0 or 1) conditional
probabilities. The MAP assignment is then found using a best-first search on
the resulting network. We argue that, as one would anticipate, the algorithm is
exponential for the general case, but only linear in the size of the network
for poly trees.


title: Reducing Uncertainty in Navigation and Exploration

abstract:
  A significant problem in designing mobile robot control systems involves
coping with the uncertainty that arises in moving about in an unknown or
partially unknown environment and relying on noisy or ambiguous sensor data to
acquire knowledge about that environment. We describe a control system that
chooses what activity to engage in next on the basis of expectations about how
the information re- turned as a result of a given activity will improve 2 its
knowledge about the spatial layout of its environment. Certain of the
higher-level components of the control system are specified in terms of
probabilistic decision models whose output is used to mediate the behavior of
lower-level control components responsible for movement and sensing.


title: Ergo: A Graphical Environment for Constructing Bayesian

abstract:
  We describe an environment that considerably simplifies the process of
generating Bayesian belief networks. The system has been implemented on readily
available, inexpensive hardware, and provides clarity and high performance. We
present an introduction to Bayesian belief networks, discuss algorithms for
inference with these networks, and delineate the classes of problems that can
be solved with this paradigm. We then describe the hardware and software that
constitute the system, and illustrate Ergo's use with several example


title: Decision Making with Interval Influence Diagrams

abstract:
  In previous work (Fertig and Breese, 1989; Fertig and Breese, 1990) we
defined a mechanism for performing probabilistic reasoning in influence
diagrams using interval rather than point-valued probabilities. In this paper
we extend these procedures to incorporate decision nodes and interval-valued
value functions in the diagram. We derive the procedures for chance node
removal (calculating expected value) and decision node removal (optimization)
in influence diagrams where lower bounds on probabilities are stored at each
chance node and interval bounds are stored on the value function associated
with the diagram's value node. The output of the algorithm are a set of
admissible alternatives for each decision variable and a set of bounds on
expected value based on the imprecision in the input. The procedure can be
viewed as an approximation to a full e-dimensional sensitivity analysis where n
are the number of imprecise probability distributions in the input. We show the
transformations are optimal and sound. The performance of the algorithm on an
influence diagrams is investigated and compared to an exact algorithm.


title: A Randomized Approximation Algorithm of Logic Sampling

abstract:
  In recent years, researchers in decision analysis and artificial intelligence
(AI) have used Bayesian belief networks to build models of expert opinion.
Using standard methods drawn from the theory of computational complexity,
workers in the field have shown that the problem of exact probabilistic
inference on belief networks almost certainly requires exponential computation
in the worst ease [3]. We have previously described a randomized approximation
scheme, called BN-RAS, for computation on belief networks [ 1, 2, 4]. We gave
precise analytic bounds on the convergence of BN-RAS and showed how to trade
running time for accuracy in the evaluation of posterior marginal
probabilities. We now extend our previous results and demonstrate the
generality of our framework by applying similar mathematical techniques to the
analysis of convergence for logic sampling [7], an alternative simulation
algorithm for probabilistic inference.


title:
Occupancy Grids: A Stochastic Spatial Representation for Active Robot
  Perception

abstract:
  In this paper we provide an overview of a new framework for robot perception,
real-world modelling, and navigation that uses a stochastic tesselated
representation of spatial information called the Occupancy Grid. The Occupancy
Grid is a multi-dimensional random field model that maintains probabilistic
estimates of the occupancy state of each cell in a spatial lattice. Bayesian
estimation mechanisms employing stochastic sensor models allow incremental
updating of the Occupancy Grid using multi-view, multi-sensor data, composition
of multiple maps, decision-making, and incorporation of robot and sensor
position uncertainty. We present the underlying stochastic formulation of the
Occupancy Grid framework, and discuss its application to a variety of robotic
tusks. These include range-based mapping, multi-sensor integration,
path-planning and obstacle avoidance, handling of robot position uncertainty,
incorporation of pre-compiled maps, recovery of geometric representations, and
other related problems. The experimental results show that the Occupancy Grid
approach generates dense world models, is robust under sensor uncertainty and
errors, and allows explicit handling of uncertainty. It supports the
development of robust and agile sensor interpretation methods, incremental
discovery procedures, and composition of information from multiple sources.
Furthermore, the results illustrate that robotic tasks can be addressed through
operations performed di- rectly on the Occupancy Grid, and that these
operations have strong parallels to operations performed in the image
processing domain.