title: Two-Fluid Description for Iron-Based Superconductors

abstract:
  We present a two-fluid description for iron-based superconductors, which
contains an itinerant electron Fermi-liquid and a local moment spin-liquid,
coupled together via an effective Hund's rule interaction. We examine the
low-energy collective behavior of such a system. We find that an
electron-spinon composite mode emerges in the intermediate coupling regime,
which may account for the hump-dip behavior observed in the resent scanning
tunneling spectroscopy experiments. The superconductivity and spin-density-wave
phases are consistently described within the same framework. Possible
experimental test is also proposed.


title: The Dust Tail of Asteroid (3200) Phaethon

abstract:
  We report the discovery of a comet-like tail on asteroid (3200) Phaethon when
imaged at optical wavelengths near perihelion. In both 2009 and 2012, the tail
appears >=350" (2.5x10^8 m) in length and extends approximately in the
projected anti-solar direction. We interpret the tail as being caused by dust
particles accelerated by solar radiation pressure. The sudden appearance and
the morphology of the tail indicate that the dust particles are small, with an
effective radius ~1 micrometer and a combined mass ~3x10^5 kg. These particles
are likely products of thermal fracture and/or desiccation cracking under the
very high surface temperatures (~1000 K) experienced by Phaethon at perihelion.
The existence of the tail confirms earlier inferences about activity in this
body based on the detection of anomalous brightening. Phaethon, the presumed
source of the Geminid meteoroids, is still active.


title: Radiative Transfer Simulations for Neutron Star Merger Ejecta

abstract:
  The merger of binary neutron stars (NSs) is among the most promising
gravitational wave (GW) sources. Next-generation GW detectors are expected to
detect signals from the NS merger within 200 Mpc. Detection of electromagnetic
wave (EM) counterpart is crucial to understand the nature of GW sources. Among
possible EM emission from the NS merger, emission powered by radioactive
r-process nuclei is one of the best targets for follow-up observations.
However, prediction so far does not take into account detailed r-process
element abundances in the ejecta. We perform radiative transfer simulations for
the NS merger ejecta including all the r-process elements from Ga to U for the
first time. We show that the opacity in the NS merger ejecta is about kappa =
10 cm^2 g^{-1}, which is higher than that of Fe-rich Type Ia supernova ejecta
by a factor of ~ 100. As a result, the emission is fainter and longer than
previously expected. The spectra are almost featureless due to the high
expansion velocity and bound-bound transitions of many different r-process
elements. We demonstrate that the emission is brighter for a higher mass ratio
of two NSs and a softer equation of states adopted in the merger simulations.
Because of the red color of the emission, follow-up observations in red optical
and near-infrared (NIR) wavelengths will be the most efficient. At 200 Mpc,
expected brightness of the emission is i = 22 - 25 AB mag, z = 21 - 23 AB mag,
and 21 - 24 AB mag in NIR JHK bands. Thus, observations with wide-field 4m- and
8m-class optical telescopes and wide-field NIR space telescopes are necessary.
We also argue that the emission powered by radioactive energy can be detected
in the afterglow of nearby short gamma-ray bursts.


title:
Detectability of High-Redshift Superluminous Supernovae with Upcoming
  Optical and Near-Infrared Surveys - II. Beyond z=6

abstract:
  Observational identification of the first stars is one of the great
challenges in the modern astronomy. Although a single first star is too faint
to be detected, supernova explosions of the first stars can be bright enough.
An important question is whether such supernovae can be detected in the limited
observational area with realistic observational resources. We perform detailed
simulations to study the detectability of superluminous supernovae (SLSNe) at
high redshifts, using the observationally-calibrated star formation rate
density and supernova occurrence rate. We show that a 100 deg^2 survey with the
limiting magnitude of 26 mag in near-infrared wavelengths will be able to
discover about 10 SLSNe at z > 10. If the survey is extended to 200 deg^2 with
27 mag depth, about 10 SLSNe can be discovered at z > 15. We emphasize that the
observations at > 3 um are crucial to detect and select SLSNe at z > 10. Our
simulations are also applied to the planned survey with Euclid, WFIRST, and
WISH. These surveys will be able to detect about 1000, 400, and 3000 SLSNe up
to z ~ 5, 7, and 12, respectively. We conclude that detection of SLSNe at z >
10 is in fact achievable in the near future.


title:
Gravitational Binary-lens Events with Prominent Effects of Lens Orbital
  Motion

abstract:
  Gravitational microlensing events produced by lenses composed of binary
masses are important because they provide a major channel to determine physical
parameters of lenses. In this work, we analyze the light curves of two
binary-lens events OGLE-2006-BLG-277 and OGLE-2012-BLG-0031 for which the light
curves exhibit strong deviations from standard models. From modeling
considering various second-order effects, we find that the deviations are
mostly explained by the effect of the lens orbital motion. We also find that
lens parallax effects can mimic orbital effects to some extent. This implies
that modeling light curves of binary-lens events not considering orbital
effects can result in lens parallaxes that are substantially different from
actual values and thus wrong determinations of physical lens parameters. This
demonstrates the importance of routine consideration of orbital effects in
interpreting light curves of binary-lens events. It is found that the lens of
OGLE-2006-BLG-277 is a binary composed of a low-mass star and a brown dwarf
companion.


title:
Characterization of GX 339-4 outburst of 2010-11: analysis by xspec
  using two component advective flow model

abstract:
  We study spectral properties of GX 339-4 during its 2010-11 outburst with Two
Component Advective Flow (TCAF) model after its inclusion in XSPEC as a table
model. We compare results fitted by TCAF model with combined disk black body
and power-law model. For a spectral fit, we use 2.5-25 keV spectral data of the
PCA instrument onboard RXTE satellite. From our fit, accretion flow parameters
such as Keplerian (disk) rate, sub-Keplerian (halo) rate, location and strength
of shock are extracted. We quantify how the disk and the halo rates vary during
the entire outburst. We study how the halo to disk accretion rate ratio (ARR),
quasi-periodic oscillations (QPOs), shock locations and its strength vary when
the system passes through hard, hard-intermediate, soft-intermediate, and soft
states. We find pieces of evidence of monotonically increasing and decreasing
nature of QPO frequencies depending on the variation of ARR during rising and
declining phases. Interestingly, on days of transition from hard state to
hard-intermediate spectral state (during the rising phase) or vice-versa
(during decline phase), ARR is observed to be locally maximum. Non-constancy of
ARR while obtaining reasonable fits points to the presence of two independent
components in the flow.


title: Single-atom polarizer

abstract:
  Traditional polarizer provides a way to convert an unknown polarization into
a specified polarization. According to Malus, the intensity of the transmission
is directly proportional to the square of the cosine of angle between the
transmission axes of the polarizer and the incident polarization. There, the
intensity refers to the collective behavior of many photons. Here we propose a
novel approach to realizing polarization-filtering at single-photon level. We
discuss how a single planepolarized photon transports through a polarized
analyzer generated by a single atom (the so-called "single-atom polarizer"),
and provide a single quantum version of Malus's law. We investigate the quantum
scattering of a single photon by a controllable four-level atom inside a
one-dimensional waveguide. By using real-space theoretical approach, we obtain
analytic expressions of the transmission spectrum of the photon. Then, our
numerical experiments show that the transmitted probability of the incident
photon can be controlled by selecting the polarized-dependent transition
configuration of the driven atom. The application of such a single-atom
polarizer to linear optical quantum information processing is also discussed.


title: Cayley graphs on abelian groups

abstract:
  Let $A$ be an abelian group and let $\iota$ be the automorphism of $A$
defined by $i:a\mapsto a^{-1}$. A Cayley graph $\Gamma=\mathrm{Cay}(A,S)$ is
said to have an automorphism group \emph{as small as possible} if
$\mathrm{Aut}(\Gamma)= A\rtimes\langle i\rangle$. In this paper, we show that
almost all Cayley graphs on abelian groups have automorphism group as small as
possible, proving a conjecture of Babai and Godsil.


title: Spontaneous Photoemission From Metamaterial Junction: A Conjecture

abstract:
  The possibility of spontaneous photon pair emission from a normal material -
metamaterial junction is investigated in a quantum field theory setting. We
consider a pair of photons arising from vacuum fluctuations of the
electromagnetic field close to the junction where one photon each comes from
the normal and metamaterial sectors. Mixing between the positive and negative
norm photon modes can give rise to spontaneous photoemission, the rate of which
is calculated.

categories: physics.optics cond-mat.mtrl-sci gr-qc hep-th quant-ph


title:
Investigations of afterpulsing and detection efficiency recovery in
  superconducting nanowire single-photon detectors

abstract:
  We report on the observation of a non-uniform dark count rate in
Superconducting Nanowire Single Photon Detectors (SNSPDs), specifically
focusing on an afterpulsing effect present when the SNSPD is operated at a high
bias current regime. The afterpulsing exists for real detection events
(triggered by input photons) as well as for dark counts (no laser input). In
our standard set-up, the afterpulsing is most likely to occur at around 180 ns
following a detection event, for both real counts and dark counts. We
characterize the afterpulsing behavior and speculate that it is not due to the
SNSPD itself but rather the amplifiers used to boost the electrical output
signal from the SNSPD. We show that the afterpulsing indeed disappears when we
use a different amplifier with a better low frequency response. We also examine
the short-lived enhancement of detection efficiency during the recovery of the
SNSPD due to temporary perturbation of the bias and grounding conditions.


title: The Borel-Cantelli Lemma for Markov Sequences of Events

abstract:
  In the present paper, we propose a new generalization of the Borel-Cantelli
lemma. This generalization can be further used to derive strong limit results
for Markov chains. Illustrative applications are provided.


title: A C*-algebra associated with dynamics on a graph of strings

abstract:
  A C*-algebra $\mathfrak E$ associated with a dynamical system on a metric
graph is introduced. The system is governed by the wave equation and controlled
from boundary vertices. Algebra $\mathfrak E$ is generated by the so-called
{\it eikonals}, which are self-adjoint operators related with reachable sets of
the system. Its structure is the main subject of the paper. We show that
$\mathfrak E$ is a direct sum of "elementary blocks". Each block is an algebra
of operators multiplying ${\mathbb R}^n$-valued functions by continuous
matrix-valued functions of special kind. The eikonal algebra is determined by
the boundary inverse data. This shows promise of its possible applications to
inverse problems.


title:
Verification of cosine squared relation of electronic conductance in a
  biphenyl molecule

abstract:
  The experimentally obtained (Venkataraman {\em et al}. \cite{latha}) cosine
squared relation of electronic conductance in a biphenyl molecule is verified
theoretically within a tight-binding framework. Using Green's function
formalism we numerically calculate two-terminal conductance as a function of
relative twist angle among the molecular rings and find that the results are in
good agreement with the experimental observation.


title: Maximal extension of conformally flat globally hyperbolic space-times

abstract:
  The notion of maximal extension of a globally hyperbolic space-time arises
from the notion of maximal solutions of the Cauchy problem associated to the
Einstein's equations of general relativity. In 1969 Choquet-Bruhat and Geroch
proved that if the Cauchy problem has a local solution, this solution has a
unique maximal extension. Since the causal structure of a space-time is
invariant under conformal changes of metrics we may generalize this notion of
maximality to the conformal setting. In this article we focus on conformally
flat space-times of dimension greater or equal than 3. In this case, by a
Lorentzian version of Liouville theorem, these space-times are locally modeled
on the Einstein space-time. In the first part we use this fact to prove the
existence and uniqueness of the maximum extension for globally hyperbolic
conformally flat space-times. In the second part we find a causal
characterization of globally hyperbolic conformally flat maximal space-times
whose developing map is a global diffeomorphism.


title: Hydrogen lines in LAMOST low resolution spectra of RR Lyrae stars

abstract:
  The LAMOST spectroscopic survey for Galactic structure and evolution has been
in operation since October 2012, following a one-year pilot survey. The pilot
survey produced a data release containing over 600,000 stellar spectra. By
cross-checking with a large time series photometric database of RR Lyrae stars
in high Galactic latitude regions, we found a total number of 157 stars that
have been observed with LAMOST. In this sample, we successfully captured three
RR Lyrae stars in the fast expansion phase, all of them showing significant
hypersonic shock wave features in the spectra. By fitting the H{\alpha} line
shape, we determine that the emission features seen within the broader
H{\alpha} absorption line suggest hypersonic relative motions in the
atmospheres of these three objects. With a further LAMOST survey of millions of
stars, we will capture a large sample of RR Lyrae stars in their hypersonic
expansion phase, and therefore provide a large database for the study of the
internal structure and pulsation mechanism of RR Lyrae stars.


title:
Saharan mineral dust outbreaks observed over the North Atlantic island
  of La Palma in summertime between 1984 and 2012

abstract:
  We estimate the frequency of Saharan mineral dust outbreak events observed
over the North Atlantic island of La Palma based on in situ nightly atmospheric
extinction measurements recorded almost continuously since 1984 by the
Carlsberg Meridian Telescope at the Roque de los Muchachos observatory. The
outbreak frequency shows a well-defined seasonal peak in the months of July to
September, during which time the occurrence of Saharan dust events (SDEs) is
approximately 28\pm6%. We find considerable year-to-year variability in the
summertime SDEs frequency, observing a steady reduction between 1984 and 1997,
followed by a period of relative mean stability from 1999 to 2012. We
investigated changes in the atmospheric extinction of the SDEs as an indicator
of strength of the episodes and found that this parameter approximately follows
the SDE frequency, however, instrumental limitations prevented us from deriving
precise conclusions regarding their long-term changes. A lagged correlation
analysis between SDE properties and the El Ni\~{n}o Southern Oscillation
(ENSO), North Atlantic Oscillation (NAO), and Sahel rainfall index (SRI) was
performed. We found that 55\pm4% of the year-to-year variations in
July-September SDE frequency may be reproduced by a lagged relationship to the
NAO conditions during the preceding October-December period, and 45\pm4% may be
reproduced by a negative correlation to the SRI during the preceding
February-April period. Based on these relationships it may be possible to
obtain an approximate indication of the strength of the upcoming summertime
dust season over the North Atlantic around half a year in advance.


title:
On Irreversibility and Radiation in Classical Electrodynamics of Point
  Particles

abstract:
  The direct interaction theory of electromagnetism, also known as
Wheeler-Feynman electrodynamics, is often misinterpreted and found unappealing
because of its reference to the absorber and, more importantly, to the
so-called absorber condition. Here we remark that the absorber condition is
indeed questionable and presumably not relevant for the explanation of
irreversible radiation phenomena in our universe. What is relevant and deserves
further scrutiny is the emergent effective description of a test particle in an
environment. We therefore rephrase what we consider the relevant calculation by
Wheeler and Feynman and comment on the status of the theory.


title: On the genericity of pseudo-Anosov braids I: rigid braids

abstract:
  We prove that, in the $l$-ball of the Cayley graph of the braid group with $n
\geqslant 3$ strands, the proportion of rigid pseudo-Anosov braids is bounded
below independently of $l$ by a positive value.


title: Spin Sensitive Transmission Through Helical Potentials

abstract:
  We calculate the transmission coefficient for electrons passing through the
helically shaped potential barrier, which can be, for example, produced by DNA
molecules.


title: Dynamical Mass Generation of Vector Mesons from QCD Trace Anomaly

abstract:
  Mass formulas for the light-vector mesons written in terms of the gluon
condensate i.e., the trace anomaly in quantum chromodynamics (QCD), are derived
on the basis of finite energy QCD sum rules. We utilize sum rules with $s^n$
and $s^{n+1/2}$ weights, which relate the energy-weighted spectral sums to the
vacuum expectation values of certain commutation relations. After evaluating
the commutation relations, the sum rules with $s^n$ weights are reduced to the
familiar ones obtained from the operator product expansion (OPE). On the other
hand, the sum rules with $s^{n+1/2}$ weights cannot be derived from OPE. They
give new relations between the spectral sums and QCD vacuum fluctuations. To
derive simple mass formula, we adopt the pole + continuum Ansatz for the
spectral function, and solve coupled equations given by the sum rules with
$s^{0,1}$ weights and the new sum rule with $s^{1/2}$ weight. Application of
our approach to the axial-vector meson is also discussed.


title:
A Space-Efficient Design for Reversible Floating Point Adder in Quantum
  Computing

abstract:
  Reversible logic has applications in low-power computing and quantum
computing. However, there are few existing designs for reversible
floating-point adders and none suitable for quantum computation. In this paper
we propose a space-efficient reversible floating-point adder, suitable for
binary quantum computation, improving the design of Nachtigal et al. Our work
focuses on improving the reversible designs of the alignment unit and the
normalization unit, which are the most expensive parts. By changing a few
elements of the existing algorithm, including the circuit designs of the RLZC
(reversible leading zero counter) and converter, we have reduced the cost about
68%. We also propose fault-tolerant designs for the circuits. The KQ for our
fault-tolerant design is almost sixty times as expensive as for a 32-bit
fixed-point addition. We note that the floating-point representation makes
in-place, truly reversible arithmetic impossible, requiring us to retain both
inputs, which limits the sustainability of its use for quantum computation.


title:
Permeability through a perforated domain for the incompressible 2D Euler
  equations

abstract:
  We investigate the influence of a perforated domain on the 2D Euler
equations. Small inclusions of size $\varepsilon$ are uniformly distributed on
the unit segment or a rectangle, and the fluid fills the exterior. These
inclusions are at least separated by a distance $\varepsilon^\alpha$ and we
prove that for $\alpha$ small enough (namely, less than 2 in the case of the
segment, and less than 1 in the case of the square), the limit behavior of the
ideal fluid does not feel the effect of the perforated domain at leading order
when $\varepsilon\to 0$.


title: L\'{e}vy driven models and derivative pricing

abstract:
  We develop a general method for derivative pricing. This approach has its
roots in Shannon's Information Theory. The notion of $\lambda$-analyticity of
L\'{e}vy models is introduced on the basis of which new representations of the
pricing integral are obtained. It is shown that popular in applications
L\'{e}vy models are $\lambda$-analytic. We apply these results to derive a
general algorithm for pricing of European call options.


title: Perturbative QCD correlations in multi-parton collisions

abstract:
  We examine the role played in double parton interactions (DPI) by the
parton--parton correlations originating from perturbative QCD parton
splittings. Also presented are the results of the numerical analysis of the
integrated DPI cross sections at Tevatron and LHC energies. To obtain the
numerical results the knowledge of the single-parton GPDs gained by the HERA
experiments was used to construct the non-perturbative input for generalized
double parton distributions. The perturbative two-parton correlations induced
by three-parton interactions contribute significantly to resolution of the
longstanding puzzle of an excess of multi-jet production events in the
back-to-back kinematics observed at the Tevatron.


title: Bounding ground state energy of Hopfield models

abstract:
  In this paper we look at a class of random optimization problems that arise
in the forms typically known as Hopfield models. We view two scenarios which we
term as the positive Hopfield form and the negative Hopfield form. For both of
these scenarios we define the binary optimization problems that essentially
emulate what would typically be known as the ground state energy of these
models. We then present a simple mechanism that can be used to create a set of
theoretical rigorous bounds for these energies. In addition to purely
theoretical bounds, we also present a couple of fast optimization algorithms
that can also be used to provide solid (albeit a bit weaker) algorithmic bounds
for the ground state energies.


title:
Pattern formation in terms of semiclassically limited distribution on
  lower-dimensional manifolds for nonlocal
  Fisher--Kolmogorov--Petrovskii--Piskunov equation

abstract:
  We have investigated the pattern formation in systems described by the
nonlocal Fisher--Kolmogorov--Petrovskii--Piskunov equation for the cases where
the dimension of the pattern concentration area is less than that of
independent variables space. We have obtained a system of integro-differential
equations which describe the dynamics of the concentration area and the
semiclassically limited distribution of a pattern in the class of trajectory
concentrated functions. Also, asymptotic large-time solutions have been
obtained that describe the semiclassically limited distribution of a
quasi-steady-state pattern on the concentration manifold. The approach is
illustrated by an example for which the analytical solution is in good
agreement with the prediction of a numerical simulation.


title: Truth Table Minimization of Computational Models

abstract:
  Complexity theory offers a variety of concise computational models for
computing boolean functions - branching programs, circuits, decision trees and
ordered binary decision diagrams to name a few. A natural question that arises
in this context with respect to any such model is this:
  Given a function f:{0,1}^n \to {0,1}, can we compute the optimal complexity
of computing f in the computational model in question? (according to some
desirable measure).
  A critical issue regarding this question is how exactly is f given, since a
more elaborate description of f allows the algorithm to use more computational
resources. Among the possible representations are black-box access to f (such
as in computational learning theory), a representation of f in the desired
computational model or a representation of f in some other model. One might
conjecture that if f is given as its complete truth table (i.e., a list of f's
values on each of its 2^n possible inputs), the most elaborate description
conceivable, then any computational model can be efficiently computed, since
the algorithm computing it can run poly(2^n) time. Several recent studies show
that this is far from the truth - some models have efficient and simple
algorithms that yield the desired result, others are believed to be hard, and
for some models this problem remains open.
  In this thesis we will discuss the computational complexity of this question
regarding several common types of computational models. We shall present
several new hardness results and efficient algorithms, as well as new proofs
and extensions for known theorems, for variants of decision trees, formulas and
branching programs.


title: Controlled Experimentation in Naturalistic Mobile Settings

abstract:
  Performing controlled user experiments on small devices in naturalistic
mobile settings has always proved to be a difficult undertaking for many Human
Factors researchers. Difficulties exist, not least, because mimicking natural
small device usage suffers from a lack of unobtrusive data to guide
experimental design, and then validate that the experiment is proceeding
naturally.Here we use observational data to derive a set of protocols and a
simple checklist of validations which can be built into the design of any
controlled experiment focused on the user interface of a small device. These,
have been used within a series of experimental designs to measure the utility
and application of experimental software. The key-point is the validation
checks -- based on the observed behaviour of 400 mobile users -- to ratify that
a controlled experiment is being perceived as natural by the user. While the
design of the experimental route which the user follows is a major factor in
the experimental setup, without check validations based on unobtrusive observed
data there can be no certainty that an experiment designed to be natural is
actually progressing as the design implies.


title: Modeling Dependencies in Claims Reserving with GEE

abstract:
  A common approach to the claims reserving problem is based on generalized
linear models (GLM). Within this framework, the claims in different origin and
development years are assumed to be independent variables. If this assumption
is violated, the classical techniques may provide incorrect predictions of the
claims reserves or even misleading estimates of the prediction error.
  In this article, the application of generalized estimating equations (GEE)
for estimation of the claims reserves is shown. Claim triangles are handled as
panel data, where claim amounts within the same accident year are dependent.
Since the GEE allow to incorporate dependencies, various correlation structures
are introduced and some practical recommendations are given.
  Model selection criteria within the GEE reserving method are proposed.
Moreover, an estimate for the mean square error of prediction for the claims
reserves is derived in a nonstandard way and its advantages are discussed. Real
data examples are provided as an illustration of the potential benefits of the
presented approach.


title:
Multi-scale analysis of the European airspace using network community
  detection

abstract:
  We show that the European airspace can be represented as a multi-scale
traffic network whose nodes are airports, sectors, or navigation points and
links are defined and weighted according to the traffic of flights between the
nodes. By using a unique database of the air traffic in the European airspace,
we investigate the architecture of these networks with a special emphasis on
their community structure. We propose that unsupervised network community
detection algorithms can be used to monitor the current use of the airspaces
and improve it by guiding the design of new ones. Specifically, we compare the
performance of three community detection algorithms, also by using a null model
which takes into account the spatial distance between nodes, and we discuss
their ability to find communities that could be used to define new control
units of the airspace.


title: Lifting $\ell_1$-optimization strong and sectional thresholds

abstract:
  In this paper we revisit under-determined linear systems of equations with
sparse solutions. As is well known, these systems are among core mathematical
problems of a very popular compressed sensing field. The popularity of the
field as well as a substantial academic interest in linear systems with sparse
solutions are in a significant part due to seminal results
\cite{CRT,DonohoPol}. Namely, working in a statistical scenario,
\cite{CRT,DonohoPol} provided substantial mathematical progress in
characterizing relation between the dimensions of the systems and the sparsity
of unknown vectors recoverable through a particular polynomial technique called
$\ell_1$-minimization. In our own series of work
\cite{StojnicCSetam09,StojnicUpper10,StojnicEquiv10} we also provided a
collection of mathematical results related to these problems. While, Donoho's
work \cite{DonohoPol,DonohoUnsigned} established (and our own work
\cite{StojnicCSetam09,StojnicUpper10,StojnicEquiv10} reaffirmed) the typical or
the so-called \emph{weak threshold} behavior of $\ell_1$-minimization many
important questions remain unanswered. Among the most important ones are those
that relate to non-typical or the so-called \emph{strong threshold} behavior.
These questions are usually combinatorial in nature and known techniques come
up short of providing the exact answers. In this paper we provide a powerful
mechanism that that can be used to attack the "tough" scenario, i.e. the
\emph{strong threshold} (and its a similar form called \emph{sectional
threshold}) of $\ell_1$-minimization.


title: The revised SNIP indicator of Elsevier's Scopus

abstract:
  The modified SNIP indicator of Elsevier, as recently explained by Waltman et
al. (2013) in this journal, solves some of the problems which Leydesdorff &
Opthof (2010 and 2011) indicated in relation to the original SNIP indicator
(Moed, 2010 and 2011). The use of an arithmetic average, however, remains
unfortunate in the case of scientometric distributions because these can be
extremely skewed (Seglen, 1992 and 1997). The new indicator cannot (or hardly)
be reproduced independently when used for evaluation purposes, and remains in
this sense opaque from the perspective of evaluated units and scholars.


title: Minimal Indices for Successor Search

abstract:
  We give a new successor data structure which improves upon the index size of
the P\v{a}tra\c{s}cu-Thorup data structures, reducing the index size from $O(n
w^{4/5})$ bits to $O(n \log w)$ bits, with optimal probe complexity.
Alternatively, our new data structure can be viewed as matching the space
complexity of the (probe-suboptimal) $z$-fast trie of Belazzougui et al. Thus,
we get the best of both approaches with respect to both probe count and index
size. The penalty we pay is an extra $O(\log w)$ inter-register operations. Our
data structure can also be used to solve the weak prefix search problem, the
index size of $O(n \log w)$ bits is known to be optimal for any such data
structure.
  The technical contributions include highly efficient single word indices,
with out-degree $w/\log w$ (compared to the $w^{1/5}$ out-degree of fusion tree
based indices). To construct such high efficiency single word indices we device
highly efficient bit selectors which, we believe, are of independent interest.


title: A note on strong protomodularity, actions and quotients

abstract:
  In order to study the problems of extending an action along a quotient of the
acted object and along a quotient of the acting object, we investigate some
properties of the fibration of points. In fact, we obtain a characterization of
protomodular categories among quasi-pointed regular ones, and, in the
semi-abelian case, a characterization of strong protomodular categories.
Eventually, we return to the initial questions by stating the results in terms
of internal actions.


title: Under-determined linear systems and $\ell_q$-optimization thresholds

abstract:
  Recent studies of under-determined linear systems of equations with sparse
solutions showed a great practical and theoretical efficiency of a particular
technique called $\ell_1$-optimization. Seminal works \cite{CRT,DOnoho06CS}
rigorously confirmed it for the first time. Namely, \cite{CRT,DOnoho06CS}
showed, in a statistical context, that $\ell_1$ technique can recover sparse
solutions of under-determined systems even when the sparsity is linearly
proportional to the dimension of the system. A followup \cite{DonohoPol} then
precisely characterized such a linearity through a geometric approach and a
series of work\cite{StojnicCSetam09,StojnicUpper10,StojnicEquiv10} reaffirmed
statements of \cite{DonohoPol} through a purely probabilistic approach. A
theoretically interesting alternative to $\ell_1$ is a more general version
called $\ell_q$ (with an essentially arbitrary $q$). While $\ell_1$ is
typically considered as a first available convex relaxation of sparsity norm
$\ell_0$, $\ell_q,0\leq q\leq 1$, albeit non-convex, should technically be a
tighter relaxation of $\ell_0$. Even though developing polynomial (or close to
be polynomial) algorithms for non-convex problems is still in its initial
phases one may wonder what would be the limits of an $\ell_q,0\leq q\leq 1$,
relaxation even if at some point one can develop algorithms that could handle
its non-convexity. A collection of answers to this and a few realted questions
is precisely what we present in this paper.


title:
Towards the Identification of New Physics through Quark Flavour
  Violating Processes

abstract:
  We outline a systematic strategy which should help in this decade to identify
New Physics beyond the Standard Model by means of quark flavour violating
processes and thereby to extend the picture of short distance physics down to
the scales as short as 10^{-20} m and even shorter distance scales
corresponding to energies of 100 TeV. Rather then using all possible flavour
violating observables that will be measured in the coming years, we concentrate
on those observables that are theoretically clean and very sensitive to NP.
Assuming that the data on the selected observables by us will be very precise,
we stress the importance of correlations between these observables as well as
of future precise calculations of non-perturbative parameters by means of
lattice QCD. Our strategy consists of twelve steps which we will discuss in
detail illustrating possible outcomes with the help of the SM, models with
CMFV, MFV and models with tree-level FCNCs mediated by neutral gauge bosons and
scalars. We propose DNA-charts that exhibit correlations between flavour
observables in different NP scenarios. The models with new left-handed and/or
right-handed currents and non-MFV interactions can be distinguished
transparently in this manner. We emphasis the important role of the stringent
CMFV relations between various observables as standard candles of flavour
physics. The pattern of deviations from these relations may help in identifying
the correct NP scenario. The success of this program will be very much
facilitated through direct signals of NP at the LHC. We also emphasize the
importance of lepton flavour violation, electric dipole moments and
(g-2)_{e,mu} in these studies.


title: Ergodic Properties of Quantum Birth and Death Chains

abstract:
  We study a class of quantum Markov processes that, on the one hand, is
inspired by the micromaser experiment in quantum optics and, on the other hand,
by classical birth and death processes. We prove some general geometric
properties and irreducibility for non-degenerated parameters. Furthermore, we
analyze ergodic properties of the corresponding transition operators. For
homogeneous birth and death rates we show how these can be fully determined by
explicit calculation. As for classical birth and death chains we obtain a rich
yet simple class of quantum Markov chains on an infinite space, which allow
only local transitions while having divers ergodic properties.


title: Block Maps between Primitive Uniform and Pisot Substitutions

abstract:
  In this article, we prove that for all pairs of primitive Pisot or uniform
substitutions with the same dominating eigenvalue, there exists a finite set of
block maps such that every block map between the corresponding subshifts is an
element of this set, up to a shift.


title: Upper-bounding $\ell_1$-optimization sectional thresholds

abstract:
  In this paper we look at a particular problem related to under-determined
linear systems of equations with sparse solutions. $\ell_1$-minimization is a
fairly successful polynomial technique that can in certain statistical
scenarios find sparse enough solutions of such systems. Barriers of $\ell_1$
performance are typically referred to as its thresholds. Depending if one is
interested in a typical or worst case behavior one then distinguishes between
the \emph{weak} thresholds that relate to a typical behavior on one side and
the \emph{sectional} and \emph{strong} thresholds that relate to the worst case
behavior on the other side. Starting with seminal works
\cite{CRT,DonohoPol,DOnoho06CS} a substantial progress has been achieved in
theoretical characterization of $\ell_1$-minimization statistical thresholds.
More precisely, \cite{CRT,DOnoho06CS} presented for the first time linear lower
bounds on all of these thresholds. Donoho's work \cite{DonohoPol} (and our own
\cite{StojnicCSetam09,StojnicUpper10}) went a bit further and essentially
settled the $\ell_1$'s \emph{weak} thresholds. At the same time they also
provided fairly good lower bounds on the values on the \emph{sectional} and
\emph{strong} thresholds. In this paper, we revisit the \emph{sectional}
thresholds and present a simple mechanism that can be used to create solid
upper bounds as well. The method we present relies on a seemingly simple but
substantial progress we made in studying Hopfield models in
\cite{StojnicHopBnds10}.


title: Bounds on restricted isometry constants of random matrices

abstract:
  In this paper we look at isometry properties of random matrices. During the
last decade these properties gained a lot attention in a field called
compressed sensing in first place due to their initial use in \cite{CRT,CT}.
Namely, in \cite{CRT,CT} these quantities were used as a critical tool in
providing a rigorous analysis of $\ell_1$ optimization's ability to solve an
under-determined system of linear equations with sparse solutions. In such a
framework a particular type of isometry, called restricted isometry, plays a
key role. One then typically introduces a couple of quantities, called upper
and lower restricted isometry constants to characterize the isometry properties
of random matrices. Those constants are then usually viewed as mathematical
objects of interest and their a precise characterization is desirable. The
first estimates of these quantities within compressed sensing were given in
\cite{CRT,CT}. As the need for precisely estimating them grew further a finer
improvements of these initial estimates were obtained in e.g.
\cite{BCTsharp09,BT10}. These are typically obtained through a combination of
union-bounding strategy and powerful tail estimates of extreme eigenvalues of
Wishart (Gaussian) matrices (see, e.g. \cite{Edelman88}). In this paper we
attempt to circumvent such an approach and provide an alternative way to obtain
similar estimates.


title:
All-solid-state continuous-wave laser systems for ionization, cooling
  and quantum state manipulation of beryllium ions

abstract:
  We describe laser systems for photoionization, Doppler cooling and quantum
state manipulation of beryllium ions. For photoionization of neutral beryllium,
we have developed a continuous-wave 235 nm source obtained by two stages of
frequency doubling from a diode laser at 940 nm. The system delivers up to 400
mW at 470 nm and 28 mW at 235 nm. For control of the beryllium ion, three laser
wavelengths at 313 nm are produced by sum-frequency generation and
second-harmonic generation from four infrared fiber lasers. Up to 7.2 W at 626
nm and 1.9 W at 313 nm are obtained using two pump beams at 1051 and 1551 nm.
Intensity fluctuations below 0.5 % per hour (during 8 hours of operation) have
been measured at a 313 nm power of 1 W. These systems are used to load
beryllium ions into a segmented ion trap.


title: Charge and spin density waves: Quasi one dimension to two dimension

abstract:
  Possibility of electronic charge and spin separation leading to charge
density wave and spin density wave is well established in one dimensional
systems in presence and absence of Coulomb interaction. We start from quasi one
dimension and show the possibility of such a transition in quasi one dimension
as well as in two dimension by going to a regime where it can be shown for free
electrons that just interact via Fermi statistics. Since Coulomb interaction
can only facilitate the phenomenon, the purpose of our work is to show the
phenomena unambiguously in the limit when Coulomb interaction can be ignored.
Finally we also comment on dimensions greater than two and inclusion of Coulomb
interactions.


title: Integrable Quantum Hydrodynamics in Two Dimensional Phase Space

abstract:
  Quantum liquids in two dimensions represent interesting dynamical quantum
systems for several reasons, among them the possibility of the existence of
infinite hidden symmetries, such as conformal symmetry or the symmetry
associated with area preserving diffeo-morphisms. It is known that when the
symmetry algebra is large enough, symmetry may fully prescribe the dynamics.
However, the way this is borne out in two dimensional hydrodynamics, both
classical and quantum, is not fully understood. Here we take a step in
clarifying this issue, by focusing on a particular example, namely that of a
two dimensional phase space liquid which emerges when one considers the
Calogero model, a many-body one-dimensional system interacting through an
inverse square law potential. We demonstrate how the symmetry algebra of
conserved quantities of the one dimensional system is expressed in terms of the
incompressible Euler hydrodynamics of point vortices in phase space. Due to a
formal relation between quantum hydrodynamics and classical stochastic
hydrodynamics, which is inherent in the method of stochastic quantization, the
ideas and methods developed here may also have application in the study of
stochastic classical hydrodynamics, after suitable modifications.

categories: math-ph cond-mat.stat-mech math.MP nlin.SI


title: UDC in Action

abstract:
  The UDC (Universal Decimal Classification) is not only a classification
language with a long history; it also presents a complex cognitive system
worthy of the attention of complexity theory. The elements of the UDC: classes,
auxiliaries, and operations are combined into symbolic strings, which in
essence represent a complex networks of concepts. This network forms a backbone
of ordering of knowledge and at the same time allows expression of different
perspectives on various products of human knowledge production. In this paper
we look at UDC strings derived from the holdings of libraries. In particular we
analyse the subject headings of holdings of the university library in Leuven,
and an extraction of UDC numbers from the OCLC WorldCat. Comparing those sets
with the Master Reference File, we look into the length of strings, the
occurrence of different auxiliary signs, and the resulting connections between
UDC classes. We apply methods and representations from complexity theory.
Mapping out basic statistics on UDC classes as used in libraries from a point
of view of complexity theory bears different benefits. Deploying its structure
could serve as an overview and basic information for users among the nature and
focus of specific collections. A closer view into combined UDC numbers reveals
the complex nature of the UDC as an example for a knowledge ordering system,
which deserves future exploration from a complexity theoretical perspective.


title:
Neutron response of the LAMBDA spectrometer and neutron interaction
  length in BaF2

abstract:
  We report on the neutron response of the LAMBDA spectrometer developed
earlier for high-energy gamma-ray measurement. The energy dependent neutron
detection efficiency of the spectrometer has been measured using the
time-of-flight (TOF) technique and compared with that of an organic liquid
scintillator based neutron detector (BC501A). The extracted efficiencies have
also been compared with those obtained from Monte Carlo GEANT4 simulation. We
have also measured the average interaction length of neutrons in the BaF2
crystal in a separate experiment, in order to determine the TOF energy
resolution. Finally, the LAMBDA spectrometer has been tested in an
in-beam-experiment by measuring neutron energy spectra in the 4He + 93Nb
reaction to extract nuclear level density parameters. Nuclear level density
parameters obtained by the LAMBDA spectrometer were found to be consistent with
those obtained by the BC501A neutron detector, indicating that the spectrometer
can be efficiently used as a neutron detector to measure the nuclear level
density parameter.


title: Moving-Frame Approach to Nonlinear Internal Waves in Oceans

abstract:
  In this article, we introduce a moving-frame approach to the geophysical
equation of two-dimensional uniformly stratified rotational fluid in oceans and
find a family of exact solutions containing ten arbitrary parameter functions.


title:
Analysis of Multi-Cell Downlink Cooperation with a Constrained Spatial
  Model

abstract:
  Multi-cell cooperation (MCC) mitigates intercell interference and improves
throughput at the cell edge. This paper considers a cooperative downlink,
whereby cell-edge mobiles are served by multiple cooperative base stations. The
cooperating base stations transmit identical signals over paths with
non-identical path losses, and the receiving mobile performs diversity
combining. The analysis in this paper is driven by a new expression for the
conditional outage probability when signals arriving over different paths are
combined in the presence of noise and interference, where the conditioning is
with respect to the network topology and shadowing. The channel model accounts
for path loss, shadowing, and Nakagami fading, and the Nakagami fading
parameters do not need to be identical for all paths. To study performance over
a wide class of network topologies, a random spatial model is adopted, and
performance is found by statistically characterizing the rates provided on the
downlinks. To model realistic networks, the model requires a minimum separation
among base stations. Having adopted a realistic model and an accurate analysis,
the paper proceeds to determine performance under several resource-allocation
policies and provides insight regarding how the cell edge should be defined.


title:
The optical companion to the intermediate mass millisecond pulsar
  J1439-5501 in the Galactic field

abstract:
  We present the identification of the companion star to the intermediate mass
binary pulsar J1439-5501 obtained by means of ground-based deep images in the
B, V and I bands, acquired with FORS2 mounted at the ESO-VLT. The companion is
a massive white dwarf (WD) with B=23.57+-0.02, V=23.21+-0.01 and I=22.96+-0.01,
located at only ~0.05" from the pulsar radio position. Comparing the WD
location in the (B, B-V) and (V, V-I) Color-Magnitude diagrams with theoretical
cooling sequences we derived a range of plausible combinations of companion
masses (1<~Mcom<~1.3 Msun), distances (d<~1200 pc), radii (<~7.8 10^3 Rsun) and
temperatures (T=31350^{+21500}_{-7400}). From the PSR mass function and the
estimated mass range we also constrained the inclination angle i >~ 55 degrees
and the pulsar mass (Mpsr <~2.2 Msun). The comparison between the WD cooling
age and the spin down age suggests that the latter is overestimated by a factor
of about ten.


title:
Algebraic Characterization of Rings of Continuous p-adic Valued
  Functions

abstract:
  The aim of this paper is to give an algebraic characterization of the rings
$C(X,\mathbb{Q}_p)$ of all continuous $\mathbb{Q}_p$-valued functions on a
compact space $X$. The characterization is similar to that of M. Stone from
1940 for the case of $\mathbb{R}$-valued functions.


title:
Remembering Manfred Bonitz (7.3.1931 -- 14.8.2012) on the first
  anniversary of his death

abstract:
  Biographical essay at the occasion of the first death anniversary of Manfred
Bonitz


title:
Excited State Properties of Organic Semiconductors: Breakdown of the
  Tamm-Dancoff Approximation

abstract:
  The solution of the Bethe-Salpeter equation within the framework of many-body
perturbation theory has turned out to be a benchmark for ab-initio calculations
of optical properties of semiconductors and insulators. Commonly, however, the
coupling between the resonant and anti-resonant excitations is neglected which
is referred to as the Tamm-Dancoff approximation (TDA). This is well justified
in cases where the exciton binding energy is much smaller than the band gap.
Here, we report on the optical properties of a representative series of organic
semiconductors where we find the TDA to no longer hold. We observe an increase
of the exciton binding energy of up to 44% thereby improving the agreement with
experiment.


title:
A gambling interpretation of some quantum information-theoretic
  quantities

abstract:
  It is known that repeated gambling over the outcomes of independent and
identically distributed (i.i.d.) random variables gives rise to alternate
operational meaning of entropies in the classical case in terms of the doubling
rates. We give a quantum extension of this approach for gambling over the
measurement outcomes of tensor product states. Under certain parameters of the
gambling setup, one can give operational meaning of von Neumann entropies. We
discuss two variants of gambling when a helper is available and it is shown
that the difference in their doubling rates is the quantum discord. Lastly, a
quantum extension of Kelly's gambling setup in the classical case gives a
doubling rate that is upper bounded by the Holevo information.


title:
Improved determination of the 1(0)-0(0) rotational frequency of NH3D+
  from the high resolution spectrum of the v4 infrared band

abstract:
  The high resolution spectrum of the v4 band of NH3D+ has been measured by
difference frequency IR laser spectroscopy in a multipass hollow cathode
discharge cell. From the set of molecular constants obtained from the analysis
of the spectrum, a value of 262817(6) MHz (3sigma) has been derived for the
frequency of the 1(0)-0(0) rotational transition. This value supports the
assignment to NH3D+ of lines at 262816.7 MHz recorded in radio astronomy
observations in Orion-IRc2 and the cold prestellar core B1-bS.


title: The Quantum Theory of the Lorentzian Fermionic Differential Forms

abstract:
  We consider the quantum theory of the Lorentzian fermionic differential forms
and the corresponding bi-spinor quantum fields, which are the expansion
coefficients of the forms in the bi-spinor basis of Becher and Joos [7]. The
canonical quantization procedure for the bi-spinor gauge theory in terms of its
Dirac spinor constituents is described in detail and the corresponding Feynman
rules are derived. We also derive all possible mass terms for massive fermions
in the bi-spinor gauge theory. The solutions are classified by a scalar spin
quantum number, a number that has no analog in the standard gauge theory and in
the SM. The possible mass terms correspond to combinations of scalar spin zero
singlets and scalar spin one-half doublets in the generation space. A
description of the connection between Lorentz spin of bi-spinors and scalar
spin of bi-spinor constituents is given.


title:
Advanced Mass Calibration and Visualization for FT-ICR Mass Spectrometry
  Imaging

abstract:
  Mass spectrometry imaging by Fourier transform ion cyclotron resonance yields
hundreds of unique peaks, many of which cannot be resolved by lower performance
mass spectrometers. The high mass accuracy and high mass resolving power allow
confident identification of small molecules and lipids directly from biological
tissue sections. Here, calibration strategies for Fourier transform ion
cyclotron resonance mass spectrometry imaging were investigated. Sub
parts-per-million mass accuracy is demonstrated over an entire tissue section.
Ion abundance fluctuations are corrected for by addition of total and relative
ion abundances for a root-mean-square error of 0.158 ppm on 16,764 peaks. A new
approach for visualization of Fourier transform ion cyclotron resonance mass
spectrometry imaging data at high resolution is presented. The Mosaic Data-cube
provides a flexible means to visualize the entire mass range at a mass spectral
bin width of 0.001 Dalton. The high resolution Mosaic Data-cube resolves
spectral features not visible at lower bin widths, while retaining the high
mass accuracy from the calibration methods discussed.


title: Noncommutative Motives II: K-Theory and Noncommutative Motives

abstract:
  We continue the work initiated in arXiv:1206.3645, where we introduced a new
stable symmetric monoidal $(\infty,1)$-category $SH_{nc}$ encoding a motivic
stable homotopy theory for the noncommutative spaces of Kontsevich and obtained
a canonical monoidal colimit-preserving functor $SH\to SH_{nc}$ relating this
new theory to the $(\infty,1)$-category encoding the stable motivic
$\mathbb{A}^1$ theory of Morel-Voevodsky. For a scheme $X$ this map recovers
the dg-derived category of perfect complexes $L_{pe}(X)$.
  In this sequel we address the study of the different flavours of algebraic
$K$-theory of dg-categories. As in the commutative case, these can be
understood as spectral valued $\infty$-presheaves over the category of
noncommutative smooth spaces and therefore provide objects in $SH_{nc}$ once
properly localized. Our first main result is the description of non-connective
$K$-theory of dg-categories introduced by Schlichting as the noncommutative
Nisnevich sheafification of connective $K$-theory. In particular it follows
that its further $\mathbb{A}^1$-localization is an object in $SH_{nc}$. As a
corollary of the recent result in A. Blanc Phd thesis, we prove that this
object is a unit for the monoidal structure.
  Using this, we obtain a precise proof for a conjecture of Kontsevich claiming
that $K$-theory gives the correct mapping spaces in noncommutative motives. As
a second corollary we obtain a factorization of our comparison map $SH\to
SH_{nc}$ through $Mod_{KH}(SH)$ - the $(\infty,1)$-category of modules over the
commutative algebra object $KH$ representing homotopy invariant algebraic
$K$-theory of schemes in $SH$. If $k$ is a field admitting resolutions of
singularities, this factorization is fully faithful, so that, at the motivic
level, no information (below $K$-theory) is lost by passing to the
noncommutative world.


title:
Quantum black hole entropy and the holomorphic prepotential of N=2
  supergravity

abstract:
  Supersymmetric terms in the effective action of N=2 supergravity in four
dimensions are generically classified into chiral-superspace integrals and
full-superspace integrals. For a theory of N=2 vector multiplets coupled to
supergravity, a special class of couplings is given by chiral-superspace
integrals that are governed by a holomorphic prepotential function. The quantum
entropy of BPS black holes in such theories depends on the prepotential
according to a known integral formula. We show, using techniques of
localization, that a large class of full-superspace integrals in the effective
action of N=2 supergravity do not contribute to the quantum entropy of BPS
black holes at any level in the derivative expansion. Our work extends similar
results for semi-classical supersymmetric black hole entropy, and goes towards
providing an explanation of why the prepotential terms capture the exact
microscopic quantum black hole entropy.


title: Greedy algorithms and poset matroids

abstract:
  We generalize the matroid-theoretic approach to greedy algorithms to the
setting of poset matroids, in the sense of Barnabei, Nicoletti and Pezzoli
(1998) [BNP]. We illustrate our result by providing a generalization of Kruskal
algorithm (which finds a minimum spanning subtree of a weighted graph) to
abstract simplicial complexes.


title:
Uniformly exponentially stable approximations for a class of damped
  systems with unbounded feedbacks

abstract:
  In this paper we study time semi-discrete approximations of a class of
exponentially stable infinite dimensional systems with unbounded feedbacks. It
has recently been proved that for time semi-discrete systems, due to high
frequency spurious components, the exponential decay property may be lost as
the time step tends to zero. We prove that adding a suitable numerical
viscosity term in the numerical scheme, one obtains approximations that are
uniformly exponentially stable with respect to the discretization parameter


title: Photo-active collagen systems with controlled triple helix architecture

abstract:
  The design of photo-active collagen systems is presented as a basis for
establishing biomimetic materials with varied network architecture and
programmable macroscopic properties. Following in-house isolation of type I
collagen, reaction with vinyl-bearing compounds of varied backbone rigidity,
i.e. 4-vinylbenzyl chloride (4VBC) and glycidyl methacrylate (GMA), was carried
out. TNBS colorimetric assay, 1H-NMR and ATR-FTIR confirmed covalent and
tunable functionalization of collagen lysines. Depending on the type and extent
of functionalization, controlled stability and thermal denaturation of triple
helices were observed via circular dichroism (CD), whereby the hydrogen-bonding
capability of introduced moieties was shown to play a major role. Full gel
formation was observed following photo-activation of functionalized collagen
solutions. The presence of a covalent network only slightly affected collagen
triple helix conformation (as observed by WAXS and ATR-FTIR), confirming the
structural organization of functionalized collagen precursors. Photo-activated
hydrogels demonstrated an increased denaturation temperature (DSC) with respect
to native collagen, suggesting that the formation of the covalent network
successfully stabilized collagen triple helices. Moreover, biocompatibility and
mechanical competence of obtained hydrogels were successfully demonstrated
under physiologically-relevant conditions. These results demonstrate that this
novel synthetic approach enabled the formation of biocompatible collagen
systems with defined network architecture and programmable macroscopic
properties, which can only partially be obtained with current synthetic
methods.


title:
Probability density adjoint for sensitivity analysis of the Mean of
  Chaos

abstract:
  Sensitivity analysis, especially adjoint based sensitivity analysis, is a
powerful tool for engineering design which allows for the efficient computation
of sensitivities with respect to many parameters. However, these methods break
down when used to compute sensitivities of long-time averaged quantities in
chaotic dynamical systems.
  The following paper presents a new method for sensitivity analysis of {\em
ergodic} chaotic dynamical systems, the density adjoint method. The method
involves solving the governing equations for the system's invariant measure and
its adjoint on the system's attractor manifold rather than in phase-space. This
new approach is derived for and demonstrated on one-dimensional chaotic maps
and the three-dimensional Lorenz system. It is found that the density adjoint
computes very finely detailed adjoint distributions and accurate sensitivities,
but suffers from large computational costs.


title: Towards a better compressed sensing

abstract:
  In this paper we look at a well known linear inverse problem that is one of
the mathematical cornerstones of the compressed sensing field. In seminal works
\cite{CRT,DOnoho06CS} $\ell_1$ optimization and its success when used for
recovering sparse solutions of linear inverse problems was considered.
Moreover, \cite{CRT,DOnoho06CS} established for the first time in a statistical
context that an unknown vector of linear sparsity can be recovered as a known
existing solution of an under-determined linear system through $\ell_1$
optimization. In \cite{DonohoPol,DonohoUnsigned} (and later in
\cite{StojnicCSetam09,StojnicUpper10}) the precise values of the linear
proportionality were established as well. While the typical $\ell_1$
optimization behavior has been essentially settled through the work of
\cite{DonohoPol,DonohoUnsigned,StojnicCSetam09,StojnicUpper10}, we in this
paper look at possible upgrades of $\ell_1$ optimization. Namely, we look at a
couple of algorithms that turn out to be capable of recovering a substantially
higher sparsity than the $\ell_1$. However, these algorithms assume a bit of
"feedback" to be able to work at full strength. This in turn then translates
the original problem of improving upon $\ell_1$ to designing algorithms that
would be able to provide output needed to feed the $\ell_1$ upgrades considered
in this papers.


title: Derived dualities induced by a 1-cotilting bimodule

abstract:
  In this paper we characterize the modules and the complexes involved in the
dualities induced by a 1-cotilting bimodule in terms of a linear compactness
condition. Our result generalizes the classical characterization of reflexive
modules with respect to Morita dualities. The linear compactness notion
considered, permits us to obtain finiteness properties of the rings and modules
involved.


title: Robust synchronization of spin-torque oscillators with an LCR load

abstract:
  We study dynamics of a serial array of spin-torque-oscillators with a
parallel inductor-capacitor-resistor (LCR) load. In a large range of parameters
the fully synchronous regime, where all the oscillators have the same state and
the output field is maximal, is shown to be stable. However, not always such a
robust complete synchronization develops from the random initial state, in many
cases nontrivial clustering is observed, with a partial synchronization
resulting in a quasiperiodic or chaotic mean field dynamics.


title: Local strain engineering in atomically thin MoS2

abstract:
  Tuning the electronic properties of a material by subjecting it to strain
constitutes an important strategy to enhance the performance of semiconducting
electronic devices. Using local strain, confinement potentials for excitons can
be engineered, with exciting possibilities for trapping excitons for quantum
optics and for efficient collection of solar energy. Two-dimensional materials
are able to withstand large strains before rupture, offering a unique
opportunity to introduce large local strains. Here, we study atomically thin
MoS2 layers with large local strains of up to 2.5% induced by controlled
delamination from a substrate. Using simultaneous scanning Raman and
photoluminescence imaging, we spatially resolve a direct bandgap reduction of
up to 90 meV induced by local strain. We observe a funnel effect in which
excitons drift hundreds of nanometers to lower bandgap regions before
recombining, demonstrating exciton confinement by local strain. The
observations are supported by an atomistic tight-binding model developed to
predict the effect of inhomogeneous strain on the local electronic states in
MoS2. The possibility of generating large strain-induced variations in exciton
trapping potentials opens the door for a variety of applications in atomically
thin materials including photovoltaics, quantum optics and two-dimensional
optoelectronic devices.


title: Designing Bell inequalities from a Tsirelson bound

abstract:
  We present a simple analytic bound on the quantum value of general
correlation type Bell inequalities, similar to Tsirelson's bound. It is based
on the maximal singular value of the coefficient matrix associated with the
inequality. We provide a criterion for tightness of the bound and show that the
class of inequalities where our bound is tight covers many famous examples from
the literature. We describe how this bound helps to construct Bell
inequalities, in particular inequalities that witness the dimension of the
measured observables.


abstract:
  Subdiffusion in a system in which mobile particles $A$ can chemically react
with static particles $B$ according to the rule $A+B\rightarrow B$ is
considered within a persistent random walk model. This model, which assumes a
correlation between successive steps of particles, provides hyperbolic Cattaneo
normal diffusion or fractional subdiffusion equations for a system without
chemical reactions. Starting with the difference equation, which describes a
persistent random walk in a system with chemical reactions, using the
generating function method and the continuous time random walk formalism, we
will derive the Cattaneo--type subdiffusion differential equation with
fractional time derivatives in which the chemical reactions mentioned above are
taken into account. We will also find its solution over a long time limit.
Based on the obtained results, we will find the Cattaneo--type
subdiffusion--reaction equation in the case in which mobile particles of
species $A$ and $B$ can chemically react according to a more complicated rule.


title:
Uniformly polynomially stable approximations for a class of second order
  evolution equations

abstract:
  In this paper we study time semi-discrete approximations of a class of
polynomially stable infinite dimensional systems modeling the damped
vibrations. We prove that adding a suitable numerical viscosity term in the
numerical scheme, one obtains approximations that are uniformly polynomially
stable with respect to the discretization parameter.


title: Characteristic exponents of complex networks

abstract:
  We present a novel way to characterize the structure of complex networks by
studying the statistical properties of the trajectories of random walks over
them. We consider time series corresponding to different properties of the
nodes visited by the walkers. We show that the analysis of the fluctuations of
these time series allows to define a set of characteristic exponents which
capture the local and global organization of a network. This approach provides
a way of solving two classical problems in network science, namely the
systematic classification of networks, and the identification of the salient
properties of growing networks. The results contribute to the construction of a
unifying framework for the investigation of the structure and dynamics of
complex systems.


title: Spherical perceptron as a storage memory with limited errors

abstract:
  It has been known for a long time that the classical spherical perceptrons
can be used as storage memories. Seminal work of Gardner, \cite{Gar88}, started
an analytical study of perceptrons storage abilities. Many of the Gardner's
predictions obtained through statistical mechanics tools have been rigorously
justified. Among the most important ones are of course the storage capacities.
The first rigorous confirmations were obtained in \cite{SchTir02,SchTir03} for
the storage capacity of the so-called positive spherical perceptron. These were
later reestablished in \cite{TalBook} and a bit more recently in
\cite{StojnicGardGen13}. In this paper we consider a variant of the spherical
perceptron that operates as a storage memory but allows for a certain fraction
of errors. In Gardner's original work the statistical mechanics predictions in
this directions were presented sa well. Here, through a mathematically rigorous
analysis, we confirm that the Gardner's predictions in this direction are in
fact provable upper bounds on the true values of the storage capacity.
Moreover, we then present a mechanism that can be used to lower these bounds.
Numerical results that we present indicate that the Garnder's storage capacity
predictions may, in a fairly wide range of parameters, be not that far away
from the true values.


title: Measurement of muonium emission from silica aerogel

abstract:
  Emission of muonium ($\mu^{+}e^{-}$) atoms from silica aerogel into vacuum
was observed. Characteristics of muonium emission were established from silica
aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg
cm$^{-3}$. Spectra of muonium decay times correlated with distances from the
aerogel surfaces, which are sensitive to the speed distributions, follow
general features expected from a diffusion process, while small deviations from
a simple room-temperature thermal diffusion model are identified. The
parameters of the diffusion process are deduced from the observed yields.


title:
Suppression of the Rayleigh-Plateau instability on a vertical fibre
  coated with wormlike micelle solutions

abstract:
  We report on the Rayleigh-Plateau instability in films of giant micelles
solutions coating a vertical fibre. We observe that the dynamics of thin films
coating the fibre could be very different from the Newtonian or standard
Non-Newtonian cases. By varying the concentration of the components of the
solutions and depending on the film thickness, we show for the first time that
the Rayleigh-Plateau instability can be stabilized using surfactant solutions.
Using global rheology and optical visualisations, we show that the development
of shear-induced structures is required to stabilize the micellar film along
the fibre. Assuming that the viscoelastic properties of the shear-induced state
can be described by a simple model, we suggest that, in addition to the
presence of shear-induced structures, the latter must have an elastic modulus
greater than a critical value evaluated from a linear stability analysis.
Finally, our analysis provides a way of estimating the bulk elasticity of the
shear-induced state.


title: Direction Dependent Background Fitting for the Fermi GBM Data

abstract:
  We present a method for determining the background of Fermi GBM GRBs using
the satellite positional information and a physical model. Since the polynomial
fitting method typically used for GRBs is generally only indicative of the
background over relatively short timescales, this method is particularly useful
in the cases of long GRBs or those which have Autonomous Repoint Request (ARR)
and a background with much variability on short timescales. We give a Direction
Dependent Background Fitting (DDBF) method for separating the motion effects
from the real data and calculate the duration (T90 and T50, as well as
confidence intervals) of the nine example bursts, from which two resulted an
ARR. We also summarize the features of our method and compare it qualitatively
with the official GBM Catalogue. Our background filtering method uses a model
based on the physical information of the satellite position. Therefore, it has
many advantages compared to previous methods. It can fit long background
intervals, remove all the features caused by the rocking behaviour of the
satellite, and search for long emissions or not-triggered events. Furthermore,
many part of the fitting have now been automatised, and the method have been
shown to work for both Sky Survey mode and ARR mode data. Future work will
provide a burst catalogue with DDBF.


title:
Time-of-flight secondary ion mass spectrometry-based molecular
  distribution distinguishing healthy and osteoarthritic human cartilage

abstract:
  Osteoarthritis (OA) is a pathology that ultimately causes joint destruction.
The cartilage is one of the principal affected tissues. Alterations in the
lipid mediators and an imbalance in the metabolism of cells that form the
cartilage (chondrocytes) have been described as contributors to the OA
development. In this study, we have studied the distribution of lipids and
chemical elements in healthy and OA human cartilage. Time of flight-secondary
ion mass spectrometry (TOF-SIMS) allows us to study the spatial distribution of
molecules at a high resolution on a tissue section. TOF-SIMS revealed a
specific peak profile that distinguishes healthy from OA cartilages. The
spatial distribution of cholesterol-related peaks exhibited a remarkable
difference between healthy and OA cartilages. A distinctive colocalization of
cholesterol and other lipids in the superficial area of the cartilage was
found. A higher intensity of oleic acid and other fatty acids in the OA
cartilages exhibited a similar localization. On the other hand, CN(-) was
observed with a higher intensity in the healthy samples. Finally, we observed
an accumulation of calcium and phosphate ions exclusively in areas surrounding
the chondrocyte in OA tissues. To our knowledge, this is the first time that
TOF-SIMS revealed combined changes in the molecular distribution in the OA
human cartilage.


title: Extremal norms for positive linear inclusions

abstract:
  For finite-dimensional linear semigroups which leave a proper cone invariant
it is shown that irreducibility with respect to the cone implies the existence
of an extremal norm. In case the cone is simplicial a similar statement applies
to absolute norms. The semigroups under consideration may be generated by
discrete-time systems, continuous-time systems or continuous-time systems with
jumps. The existence of extremal norms is used to extend results on the
Lipschitz continuity of the joint spectral radius beyond the known case of
semigroups that are irreducible in the representation theory interpretation of
the word.


title:
Are Quasi-Monte Carlo algorithms efficient for two-stage stochastic
  programs?

abstract:
  Quasi-Monte Carlo algorithms are studied for designing discrete
approximations of two-stage linear stochastic programs. Their integrands are
piecewise linear, but neither smooth nor lie in the function spaces considered
for QMC error analysis. We show that under some weak geometric condition on the
two-stage model all terms of their ANOVA decomposition, except the one of
highest order, are smooth. Hence, Quasi-Monte Carlo algorithms may achieve the
optimal rate of convergence $O(n^{-1+\delta})$ with $\delta \in(0,\frac{1}{2}]$
and a constant not depending on the dimension. The geometric condition is shown
to be generically satisfied if the underlying distribution is normal. We
discuss sensitivity indices, effective dimensions and dimension reduction
techniques for two-stage integrands. Numerical experiments show that indeed
convergence rates close to the optimal rate are achieved when using randomly
scrambled Sobol' point sets and randomly shifted lattice rules accompanied with
suitable dimension reduction techniques.


title: Probing holographic semi-local quantum liquids with D-branes

abstract:
  We study dynamics of probe D-branes in $(d+2)$-dimensional background with
general semi-locality. The background is characterized by a parameter $\eta$
and is conformal to $AdS_{2}\times\mathbb{R}^{d}$. We discuss thermodynamics of
the probe D-branes and find that the entropy density is vanishing in the
extremal limit, which indicates that the background may correspond to the true
ground state of the system. We also clarify the conditions under which the
specific heat matches to the behavior of a Fermi liquid or a Bose liquid. We
calculate the current-current and density-density retarded Green's functions,
from which we can obtain the AC conductivity and the zero sound mode. The AC
conductivity scales as $\omega^{-1}$ when $d/\eta<2$ and $\omega^{-2\eta/d}$
when $d/\eta>2$, while it contains a logarithmic term in $\omega$ when
$d/\eta=2$. We also observe that there is no quasi-particle excitation when
$d/\eta\geq2$ and classify the conditions under which the quasi-particle
description is valid when $d/\eta<2$.


title: Classification of Conic Sections in $PE_2(\mathbb{R})$

abstract:
  This paper gives a complete classification of conics in $PE_2(\mathbb{R})$.
The classification has been made earlier (Reveruk [5]), but it showed to be
incomplete and not possible to cite and use in further studies of properties of
conics, pencil of conics, and of quadratic forms in pseudo-Euclidean spaces.
This paper provides that. A pseudo-orthogonal matrix, pseudo-Euclidean values
of a matrix, diagonalization of a matrix in a pseudo-Euclidean way are
introduced. Conics are divided in families and by types, giving both of them
geometrical meaning. The invariants of a conic with respect to the group of
motions in $PE_2(\mathbb{R})$ are determined, making it possible to determine a
conic without reducing its equation to canonical form. An overview table is
given.


title:
A Set of Formulae on Fractal Dimension Relations and Its Application to
  Urban Form

abstract:
  The area-perimeter scaling can be employed to evaluate the fractal dimension
of urban boundaries. However, the formula in common use seems to be not
correct. By means of mathematical method, a new formula of calculating the
boundary dimension of cities is derived from the idea of box-counting
measurement and the principle of dimensional consistency in this paper. Thus,
several practical results are obtained as follows. First, I derive the
hyperbolic relation between the boundary dimension and form dimension of
cities. Using the relation, we can estimate the form dimension through the
boundary dimension and vice versa. Second, I derive the proper scales of
fractal dimension: the form dimension comes between 1.5 and 2, and the boundary
dimension comes between 1 and 1.5. Third, I derive three form dimension values
with special geometric meanings. The first is 4/3, the second is 3/2, and the
third is about 1.7071. The fractal dimension relation formulae are applied to
China's cities and the cities of the United Kingdom, and the computations are
consistent with the theoretical expectation. The formulae are useful in the
fractal dimension estimation of urban form, and the findings about the fractal
parameters are revealing for future city planning and the spatial optimization
of cities.


title: Analysis of Quickselect under Yaroslavskiy's Dual-Pivoting Algorithm

abstract:
  There is excitement within the algorithms community about a new partitioning
method introduced by Yaroslavskiy. This algorithm renders Quicksort slightly
faster than the case when it runs under classic partitioning methods. We show
that this improved performance in Quicksort is not sustained in Quickselect; a
variant of Quicksort for finding order statistics. We investigate the number of
comparisons made by Quickselect to find a key with a randomly selected rank
under Yaroslavskiy's algorithm. This grand averaging is a smoothing operator
over all individual distributions for specific fixed order statistics. We give
the exact grand average. The grand distribution of the number of comparison
(when suitably scaled) is given as the fixed-point solution of a distributional
equation of a contraction in the Zolotarev metric space. Our investigation
shows that Quickselect under older partitioning methods slightly outperforms
Quickselect under Yaroslavskiy's algorithm, for an order statistic of a random
rank. Similar results are obtained for extremal order statistics, where again
we find the exact average, and the distribution for the number of comparisons
(when suitably scaled). Both limiting distributions are of perpetuities (a sum
of products of independent mixed continuous random variables).


title:
Fourier Analysis of an Expanded Gravity Model for Spatio-Temporal
  Interactions

abstract:
  Fourier analysis and cross-correlation function are successfully applied to
improving the conventional gravity model of interaction between cities by
introducing a time variable to the attraction measures (e.g., city sizes). The
traditional model assumes spatial interaction as instantaneous, while the new
model considers the interaction as a temporal process and measures it as an
aggregation over a period of time. By doing so, the new model not only is more
theoretically sound, but also enables us to integrate the analysis of temporal
process into spatial interaction modeling. Based on cross-correlation function,
the developed model is calibrated by Fourier analysis techniques, and the
computation process is demonstrated in four steps. The paper uses a simple case
study to illustrate the approach to modeling the interurban interaction, and
highlight the relationship between the new model and the conventional gravity
model.


title: Galois bimodules and integrality of PI comodule algebras over invariants

abstract:
  Let A be a comodule algebra for a finite dimensional Hopf algebra K over an
algebraically closed field k, and let A^K be the subalgebra of invariants. Let
Z be a central subalgebra in A, which is a domain with quotient field Q. Assume
that Q\otimes_Z A is a central simple algebra over Q, and either A is a
finitely generated torsion-free Z-module and Z is integrally closed in Q, or A
is a finite projective Z-module. Then we show that A and Z are integral over
the subring of central invariants Z\cap A^K. More generally, we show that this
statement is valid under the same assumptions if Z is a reduced algebra with
quotient ring Q, and Q\otimes_Z A is a semisimple algebra with center Q. In
particular, the statement holds for a coaction of K on a prime PI algebra A
whose center Z is an integrally closed finitely generated domain over k. This
generalizes the results of S. Skryabin in the case when A is commutative. For
the proof, we develop a theory of Galois bimodules over semisimple algebras
finite over the center.


title:
Redefining the Attraction Measure, Scaling Exponent and Impedance
  Function of the Gravity Model

abstract:
  The attraction measure, scaling exponent, and impedance function of the
gravity model are redefined using the concepts from fractals and spatial
complexity. Firstly, the attraction measure of spatial interaction in human
systems is defined by the product of traffic inflow and outflow. Based on the
new definition, the gravity model originating from the Newtonian analogy is
differentiated from Wilson's spatial interaction model deriving from
entropy-maximizing principle. Secondly, the scaling exponent of the gravity
model based on the inverse distance relationship is revealed to be the ratio of
the fractal dimension of networks of cities to that of hierarchies of cities.
The value of the scaling exponent is then shown to approach to 2, which
corresponds to the value of the power exponent of the law of gravity in
classical physics. Thirdly, the inverse power function is demonstrated to be
more acceptable than the negative exponential function as an impedance function
of the gravity model. The limits of application of different gravity models
based on different impedance functions are brought to light. Applying the
expanded theory and models to China's interregional flows yields satisfying
results, which in turn lend further support to the expanded theory and models.


title:
An exact analytic treatment of propagating mass accretion rate
  fluctuations in X-ray binaries

abstract:
  Many statistical properties of the aperiodic variability observed in X-ray
radiation from accreting compact objects can be naturally explained by the
propagating fluctuations model. This considers variations in mass accretion
rate to be stirred up throughout the accretion flow. Variations from the outer
regions of the accretion flow will propagate towards the central object,
modulating the variations from the inner regions and eventually modulating the
radiation, giving rise to the observed linear RMS-flux relation and also
Fourier frequency dependent time lags. Previous treatments of this model have
relied on computationally intensive Monte Carlo simulations which can only
yield an estimate of statistical properties such as the power spectrum. Here,
we find exact and analytic expressions for the power spectrum and lag spectrum
predicted by the same model. We use our calculation to fit the model of Ingram
& Done (2012) to a power spectrum of XTE J1550-564. The result we present here
will apply to any treatment of the propagating fluctuations model and thus
provides a very powerful tool for future theoretical modelling.


title:
High energy collision cascades in tungsten: dislocation loops structure
  and clustering scaling laws

abstract:
  Recent experiments on in-situ high-energy self-ion irradiation of tungsten
(W) show the occurrence of unusual cascade damage effects resulting from single
ion impacts, shedding light on the nature of radiation damage expected in the
tungsten components of a fusion reactor. In this paper, we investigate the
dynamics of defect production in 150 keV collision cascades in W at atomic
resolution, using molecular dynamics simulations and comparing predictions with
experimental observations. We show that cascades in W exhibit no subcascade
break-up even at high energies, producing a massive, unbroken molten area,
which facilitates the formation of large defect clusters. Simulations show
evidence of the formation of both 1/2<111> and <100> interstitial-type
dislocation loops, as well as the occurrence of cascade collapse resulting in
<100> vacancy-type dislocation loops, in excellent agreement with experimental
observations. The fractal nature of the cascades gives rise to a scale-less
power law type size distribution of defect clusters.


title: Collective Correlations of Brodmann Areas fMRI Study with RMT-Denoising

abstract:
  We study collective behavior of Brodmann regions of human cerebral cortex
using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory
(RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the
Brodmann areas with the aid of the Talairach coordinates. Principal Component
Analysis (PCA) of the Pearson correlation matrix for 41 different Brodmann
regions is carried out to determine their collective activity in the idle state
and in the active state stimulated by tapping. The collective brain activity is
identified through the statistical analysis of the eigenvectors to the largest
eigenvalues of the Pearson correlation matrix. The leading eigenvectors have a
large participation ratio. This indicates that several Broadmann regions
collectively give rise to the brain activity associated with these
eigenvectors. We apply random matrix theory to interpret the underlying
multivariate data.


title:
Logarithmic Bloch spaces in the polydisc, endpoint results for Hankel
  operators and pointwise multipliers

abstract:
  We define two notions of Logarithmic Bloch space in the polydisc for which we
provide equivalent definitions in terms of symbols of bounded Hankel operators.
We also provide a full characterization of the pointwise multipliers between
two different Bloch spaces of the unit polydisc.


title:
Ergodic theorems for $L_1$--$L_\infty$ contractions in
  Banach--Kantorovich $L_p$-lattices

abstract:
  We present versions of ergodic theorems for $L_1$--$L_\infty$ contractions in
Banach--Kantorovich $L_p$-lattices associated with the Maharam measure taking
values in the algebra of measurable functions.


title: Non-Uniform Blind Deblurring with a Spatially-Adaptive Sparse Prior

abstract:
  Typical blur from camera shake often deviates from the standard uniform
convolutional script, in part because of problematic rotations which create
greater blurring away from some unknown center point. Consequently, successful
blind deconvolution requires the estimation of a spatially-varying or
non-uniform blur operator. Using ideas from Bayesian inference and convex
analysis, this paper derives a non-uniform blind deblurring algorithm with
several desirable, yet previously-unexplored attributes. The underlying
objective function includes a spatially adaptive penalty which couples the
latent sharp image, non-uniform blur operator, and noise level together. This
coupling allows the penalty to automatically adjust its shape based on the
estimated degree of local blur and image structure such that regions with large
blur or few prominent edges are discounted. Remaining regions with modest blur
and revealing edges therefore dominate the overall estimation process without
explicitly incorporating structure-selection heuristics. The algorithm can be
implemented using a majorization-minimization strategy that is virtually
parameter free. Detailed theoretical analysis and empirical validation on real
images serve to validate the proposed method.


title: Nuclear medium effects in Drell-Yan process

abstract:
  We study nuclear medium effects in Drell-Yan processes at small target x
using quark parton distribution functions and nucleon structure functions for a
bound nucleon calculated in a microscopic nuclear model which takes into
account the effect of Fermi motion, nuclear binding and nucleon correlations
through a relativistic spectral function. The contributions of $\pi$ and $\rho$
mesons, target mass corrections and nuclear shadowing are also included. The
results are compared with the theoretical and experimental results. The model
is able to successfully explain the low target x results of E772 and E866
Drell-Yan experiments and is applicable to the forthcoming experimental
analysis of E906 Sea Quest experiment at Fermi Lab.


title: What do leaders know?

abstract:
  The ability of a society to make the right decisions on relevant matters
relies on its capability to properly aggregate the noisy information spread
across the individuals it is made of. In this paper we study the information
aggregation performance of a stylized model of a society whose most influential
individuals - the leaders - are highly connected among themselves and
uninformed. Agents update their state of knowledge in a Bayesian manner by
listening to their neighbors. We find analytical and numerical evidence of a
transition, as a function of the noise level in the information initially
available to agents, from a regime where information is correctly aggregated to
one where the population reaches consensus on the wrong outcome with finite
probability. Furthermore, information aggregation depends in a non-trivial
manner on the relative size of the clique of leaders, with the limit of a
vanishingly small clique being singular.


title: Propagation of chaos for a sub-critical Keller-Segel model

abstract:
  This paper deals with a sub-critical Keller-Segel equation. Starting from the
stochastic particle system associated with it, we show well-posedness results
and the propagation of chaos property. More precisely, we show that the
empirical measure of the system tends towards the unique solution of the limit
equation as the number of particles goes to infinity.


title:
Modal approach for tailoring the absorption in a photonic crystal
  membrane

abstract:
  In this paper, we propose a method for tailoring the absorption in a photonic
crystal membrane. For that purpose, we first applied Time Domain Coupled Mode
Theory to such a subwavelength membrane and demonstrated that 100% resonant
absorption can be reached even for a symmetric membrane, if degenerate modes
are involved. Design rules were then derived from this model in order to tune
the absorption. Subsequently, Finite Difference Time Domain simulations were
used as a proof of concept and carried out on a low absorbing material
(extinction coefficient=10-2) with a high refractive index corresponding to the
optical indices of amorphous silicon at around 720 nm. In doing so, 85%
resonant absorption was obtained, which is significantly higher than the
commonly reported 50% maximum value. Those results were finally analyzed and
confronted to theory so as to extend our method to other materials,
configurations and applications.


title: The Size-Change Termination Principle for Constructor Based Languages

abstract:
  This paper describes an automatic termination checker for a generic
first-order call-by-value language in ML style. We use the fact that value are
built from variants and tuples to keep some information about how arguments of
recursive call evolve during evaluation. The result is a criterion for
termination extending the size-change termination principle of Lee, Jones and
Ben-Amram that can detect size changes inside subvalues of arguments. Moreover
the corresponding algorithm is easy to implement, making it a good candidate
for experimentation.


title:
Revisiting literature observations on photodarkening in Yb3+doped fiber
  considering the possible presence of Tm impurities

abstract:
  Ytterbium (Yb) doped fiber lasers are known to be affected by the creation of
color centers during lasing (socalled photodarkening (PD)). In a previous work,
this defect creation was investigated from a spectroscopic point of view,
showing the presence of traces (ppb) of thulium (Tm) in the Yb doped fiber. It
was shown that Tm has a strong impact on the defect creation process involved
in PD. In this paper, we compare the results from the literature with our Tm
hypothesis, without finding any contradiction. Moreover, this hypothesis can be
an explanation for the discrepancies in the literature.


title:
Multiple orthogonal polynomials associated with an exponential cubic
  weight

abstract:
  We consider multiple orthogonal polynomials associated with the exponential
cubic weight e^{-x^3} over two contours in the complex plane. We study the
basic properties of these polynomials, including the Rodrigues formula and
nearest-neighbor recurrence relations. It turns out that the recurrence
coefficients are related to a discrete Painlev\'e equation. The asymptotics of
the recurrence coefficients, the ratio of the diagonal multiple orthogonal
polynomials and the (scaled) zeros of these polynomials are also investigated.


title: Grushin problems and control theory: Formulation and examples

abstract:
  In this paper we give a new formulation of an abstract control problem in
terms of a Grushin problem, so that we will reformulate all notions of
controllability, observability and stability in a new form that gives readers
an easy interpretation of these notions.


title:
Dynamics on flag manifolds: domains of proper discontinuity and
  cocompactness

abstract:
  For noncompact semisimple Lie groups $G$ we study the dynamics of the actions
of their discrete subgroups $\Gamma<G$ on the associated partial flag manifolds
$G/P$. Our study is based on the observation that they exhibit also in higher
rank a certain form of convergence type dynamics. We identify geometrically
domains of proper discontinuity in all partial flag manifolds. Under certain
dynamical assumptions equivalent to the Anosov subgroup condition, we establish
the cocompactness of the $\Gamma$-action on various domains of proper
discontinuity, in particular on domains in the full flag manifold $G/B$. We
show in the regular case (of $B$-Anosov subgroups) that the latter domains are
always nonempty if if $G$ has (locally) at least one noncompact simple factor
not of the type $A_1, B_2$ or $G_2$.


title: Simplicity of partial skew group rings of abelian groups

abstract:
  Let $\A$ be a ring with local units, $\E$ a set of local units for $\A$, $\G$
an abelian group and $\alpha$ a partial action of $\G$ by ideals of $\A$ that
contain local units and such that the partial skew group ring $\A\star_{\alpha}
\G$ is associative. We show that $\A\star_{\alpha} \G$ is simple if and only if
$\A$ is $\G$-simple and the center of the corner $e\delta_0 (\A\star_{\alpha}
\G) e \delta_0$ is a field for all $e\in \E$. We apply the result to
characterize simplicity of partial skew group rings in two cases, namely for
partial skew group rings arising from partial actions by clopen subsets of a
compact set and partial actions on the set level.


title:
TwitterCrowds: Techniques for Exploring Topic and Sentiment in
  Microblogging Data

abstract:
  Analysts and social scientists in the humanities and industry require
techniques to help visualize large quantities of microblogging data. Methods
for the automated analysis of large scale social media data (on the order of
tens of millions of tweets) are widely available, but few visualization
techniques exist to support interactive exploration of the results. In this
paper, we present extended descriptions of ThemeCrowds and SentireCrowds, two
tag-based visualization techniques for this data. We subsequently introduce a
new list equivalent for both of these techniques and present a number of case
studies showing them in operation. Finally, we present a formal user study to
evaluate the effectiveness of these list interface equivalents when comparing
them to ThemeCrowds and SentireCrowds. We find that discovering topics
associated with areas of strong positive or negative sentiment is faster when
using a list interface. In terms of user preference, multilevel tag clouds were
found to be more enjoyable to use. Despite both interfaces being usable for all
tested tasks, we have evidence to support that list interfaces can be more
efficient for tasks when an appropriate ordering is known beforehand.


title: Partial crossed products as equivalence relation algebras

abstract:
  For a free partial action of a group in a set we realize the associated
partial skew group ring as an algebra of functions with finite support over an
equivalence relation and we use this result to characterize the ideals in the
partial skew group ring. This generalizes, to the purely algebraic setting, the
known characterization of partial C*-crossed products as groupoid C*-algebras.
For completeness we include a new proof of the C* result for free partial
actions.