title:
MAGIC gamma-ray and multifrequency observations of flat spectrum radio
  quasar PKS 1510-089 in early 2012

abstract:
  Among more than fifty blazars detected in very high energy (VHE, E>100GeV)
gamma-rays, only three belong to the subclass of Flat Spectrum Radio Quasars
(FSRQs). MAGIC observed FSRQ PKS 1510-089 in February-April 2012 during a high
activity state in the high energy (HE, E>100 MeV) gamma-ray band observed by
AGILE and Fermi. MAGIC observations result in the detection of a source with
significance of 6.0 sigma. In agreement with the previous VHE observations of
the source, we find no statistically significant variability during the MAGIC
observations in daily, weekly or monthly time scales. The other two known VHE
FSRQs have shown daily scale to sub-hour variability.
  We study the multifrequency behaviour of the source at the epoch of MAGIC
observation, collecting quasi-simultaneous data at radio and optical (GASP-WEBT
and F-Gamma collaborations, REM, Steward, Perkins, Liverpool, OVRO and VLBA
telescopes), X-ray (Swift satellite) and HE gamma-ray frequencies. The
gamma-ray SED combining AGILE, Fermi and MAGIC data joins smoothly and shows no
hint of a break. The multifrequency light curves suggest a common origin for
the millimeter radio and HE gamma-ray emission and the HE gamma-ray flaring
starts when the new component is ejected from the 43GHz VLBA core. The
quasi-simultaneous multifrequency SED is modelled with a one-zone inverse
Compton model. We study two different origins of the seed photons for the
inverse Compton scattering, namely the infra-red torus and a slow sheath
surrounding the jet around the VLBA core. Both models fit the data well.
However, the fast HE gamma-ray variability requires that within the modelled
large emitting region, there must exist more compact regions. We suggest that
these observed signatures would be most naturally explained by a turbulent
plasma flowing at a relativistic speed down the jet and crossing a standing
conical shock.


title:
Quasiconformal extendibility of integral transforms of
  Noshiro-Warschawski functions

abstract:
  Since the nonlinear integral transforms $J_{\alpha}[f](z) =
\int_{0}^{z}(f'(u))^{\alpha} du$ and $I_{\alpha}[f](z) =\int_0^z
(f(u)/u)^{\alpha} du$ with a complex number $\alpha$ have been introduced, a
great number of studies were dedicated to deriving sufficient conditions for
univalence on the unit disk. On the other hand, little is known about the
conditions that $J_{\alpha}[f]$ or $I_{\alpha}[f]$ produces a holomorphic
univalent function in the unit disk which extends to a quasiconformal map on
the complex plane. In this paper we discuss quasiconformal extendibility of the
integral transforms $J_{\alpha}[f]$ and $I_{\alpha}[f]$ for holomorphic
functions which satisfy the Noshiro-Warschawski criterion. Various approaches
using pre-Schwarzian derivatives, differential subordinations and Loewner
theory are taken to this problem.


title: Random walk centrality for temporal networks

abstract:
  Nodes can be ranked according to their relative importance within the
network. Ranking algorithms based on random walks are particularly useful
because they connect topological and diffusive properties of the network.
Previous methods based on random walks, as for example the PageRank, have
focused on static structures. However, several realistic networks are indeed
dynamic, meaning that their structure changes in time. In this paper, we
propose a centrality measure for temporal networks based on random walks which
we call TempoRank. While in a static network, the stationary density of the
random walk is proportional to the degree or the strength of a node, we find
that in temporal networks, the stationary density is proportional to the
in-strength of the so-called effective network. The stationary density also
depends on the sojourn probability q which regulates the tendency of the walker
to stay in the node. We apply our method to human interaction networks and show
that although it is important for a node to be connected to another node with
many random walkers at the right moment (one of the principles of the
PageRank), this effect is negligible in practice when the time order of link
activation is included.


title:
Nonlinear hyperspectral unmixing with robust nonnegative matrix
  factorization

abstract:
  This paper introduces a robust mixing model to describe hyperspectral data
resulting from the mixture of several pure spectral signatures. This new model
not only generalizes the commonly used linear mixing model, but also allows for
possible nonlinear effects to be easily handled, relying on mild assumptions
regarding these nonlinearities. The standard nonnegativity and sum-to-one
constraints inherent to spectral unmixing are coupled with a group-sparse
constraint imposed on the nonlinearity component. This results in a new form of
robust nonnegative matrix factorization. The data fidelity term is expressed as
a beta-divergence, a continuous family of dissimilarity measures that takes the
squared Euclidean distance and the generalized Kullback-Leibler divergence as
special cases. The penalized objective is minimized with a block-coordinate
descent that involves majorization-minimization updates. Simulation results
obtained on synthetic and real data show that the proposed strategy competes
with state-of-the-art linear and nonlinear unmixing methods.


title: Gas inflows towards the nucleus of the active galaxy NGC7213

abstract:
  We present two-dimensional stellar and gaseous kinematics of the inner
0.8x1.1kpc^2 of the LINER/Seyfert 1 galaxy NGC7213, from optical spectra
obtained with the GMOS integral field spectrograph on the Gemini South
telescope at a spatial resolution of 60pc. The stellar kinematics shows an
average velocity dispersion of 177km/s, circular rotation with a projected
velocity amplitude of 50km/s and a kinematic major axis at a position angle of
-4degrees (west of north). From the average velocity dispersion we estimate a
black hole mass of M_BH=8_{-6}^{+16}x10^7 M_sun. The gas kinematics is
dominated by non-circular motions, mainly along two spiral arms extending from
the nucleus out to 4arcsec (280pc) to the NW and SE, that are cospatial with a
nuclear dusty spiral seen in a structure map of the nuclear region of the
galaxy. The projected gas velocities along the spiral arms show blueshifts in
the far side and redshifts in the near side, with values of up to 200km/s. This
kinematics can be interpreted as gas inflows towards the nucleus along the
spiral arms if the gas is in the plane of the galaxy. We estimate the mass
inflow rate using two different methods. The first is based of the observed
velocities and geometry of the flow, and gives a mass inflow rate in the
ionised gas of 7x10^-2 M_sun/yr. In the second method, we calculate the net
ionised gas mass flow rate through concentric circles of decreasing radii
around the nucleus resulting in mass inflow rates ranging from 0.4 M_sun/yr at
300pc down to 0.2 M_sun/yr at 100pc from the nucleus. These rates are larger
than necessary to power the active nucleus.


title: Discrete Thickness

abstract:
  We investigate the relationship between a discrete version of thickness and
its smooth counterpart. These discrete energies are defined on equilateral
polygons with $n$ vertices. It will turn out that the smooth ropelength, which
is the scale invariant quotient of length divided by thickness, is the
$\Gamma$-limit of the discrete ropelength for $n\to\infty$, regarding the
topology induced by the Sobolev norm
$||\cdot||_{W^{1,\infty}(\mathbb{S}_{1},\mathbb{R}^{d})}$. This result directly
implies the convergence of almost minimizers of the discrete energies in a
fixed knot class to minimizers of the smooth energy. Moreover, we show that the
unique absolute minimizer of inverse discrete thickness is the regular $n$-gon.


title:
Strong and Mild Extrapolated $L^2$-Solutions to the Heat Equation with
  Constant Delay

abstract:
  We propose a Hilbert space solution theory for a nonhomogeneous heat equation
with delay in the highest order derivatives with nonhomogeneous Dirichlet
boundary conditions in a bounded domain. Under rather weak regularity
assumptions on the data, we prove a well-posedness result and give an explicit
representation of solutions. Further, we prove an exponential decay rate for
the energy in the dissipative case. We also show that lower order
regularizations lead to ill-posedness, also for higher-order equations.
Finally, an application with physically relevant constants is given.


title: The Double Eulerian Polynomial and Inversion Tables

abstract:
  We show that the pair (des, ides) of statistics on the set of permu- tations
has the same distribution as the pair (asc, row) of statistics on the set of
inversion tables, proving a conjecture of Visontai. The common generating
function of these pairs is the double Eulerian polynomial.


title: Weak positivity via mixed Hodge modules

abstract:
  We prove that the lowest nonzero piece in the Hodge filtration of a mixed
Hodge module is always weakly positive in the sense of Viehweg.


title: Harmonic Oscillator in Relativistic Minimal Length Quantum Mechanics

abstract:
  We consider the Dirac equation with a generalized uncertainty principle in
the presence of the Harmonic interaction and an external magnetic field. By
doing the study in the momentum space, the problem solved in an exact
analytical manner and the eigenfucntions reported in terms of the
hypergeometric functions.


title: Yoneda lemma for complete Segal spaces

abstract:
  In this note we formulate and give a self-contained proof of the Yoneda lemma
for infinity categories in the language of complete Segal spaces.


title:
Enhancing Mobile Object Classification Using Geo-referenced Maps and
  Evidential Grids

abstract:
  Evidential grids have recently shown interesting properties for mobile object
perception. Evidential grids are a generalisation of Bayesian occupancy grids
using Dempster- Shafer theory. In particular, these grids can handle
efficiently partial information. The novelty of this article is to propose a
perception scheme enhanced by geo-referenced maps used as an additional source
of information, which is fused with a sensor grid. The paper presents the key
stages of such a data fusion process. An adaptation of conjunctive combination
rule is presented to refine the analysis of the conflicting information. The
method uses temporal accumulation to make the distinction between stationary
and mobile objects, and applies contextual discounting for modelling
information obsolescence. As a result, the method is able to better
characterise the occupied cells by differentiating, for instance, moving
objects, parked cars, urban infrastructure and buildings. Experiments carried
out on real- world data illustrate the benefits of such an approach.


title:
Ultra-fast quantum randomness generation by accelerated phase diffusion
  in a pulsed laser diode

abstract:
  We demonstrate a high bit-rate quantum random number generator by
interferometric detection of phase diffusion in a gain-switched DFB laser
diode. Gain switching at few-GHz frequencies produces a train of bright pulses
with nearly equal amplitudes and random phases. An unbalanced Mach-Zehnder
interferometer is used to interfere subsequent pulses and thereby generate
strong random-amplitude pulses, which are detected and digitized to produce a
high-rate random bit string. Using established models of semiconductor laser
field dynamics, we predict a regime of high visibility interference and nearly
complete vacuum-fluctuation-induced phase diffusion between pulses. These are
confirmed by measurement of pulse power statistics at the output of the
interferometer. Using a 5.825 GHz excitation rate and 14-bit digitization, we
observe 43 Gbps quantum randomness generation.


title:
Constraints on black hole spins with a general relativistic accretion
  disk corona model

abstract:
  The peaks of the spectra of the accretion disks surrounding massive black
holes in quasars are in the far-UV or soft X-ray band, which are usually not
observed. However, in the disk corona model, the soft photons from the disk are
Comptonized to high energy in the hot corona, and the hard X-ray spectra
(luminosity and spectral shape) contain the information of the incident spectra
from the disk. The values of black hole spin parameter $a_{\ast}$ are inferred
from the spectral fitting, which spread over a large range, $\sim -0.94$ to
$0.998$. We find that the inclination angles and mass accretion rates are well
determined by the spectral fitting, while the results are sensitive to the
accuracy of black hole mass estimates. No tight constraints on the black hole
spins are achieved, if the uncertainties of black hole mass measurements are a
factor of four, which are typical for the single-epoch reverberation mapping
method. Recently, the accuracy of black hole mass measurement has been
significantly improved to $0.2-0.4$~dex with velocity resolved reverberation
mapping method (Pancoast et al., 2014). The black hole spin can be well
constrained if the mass measurement accuracy is $\la 50$\%. In the accretion
disk corona scenario, a fraction of power dissipated in the disk is transported
into the corona, and therefore the accretion disk is thinner than a bare disk
for the same mass accretion rate, because the radiation pressure in the disk is
reduced. We find that the thin disk approximation, $H/R\la 0.1$, is still valid
if $0.3<\dot{m}<0.5$, provided a half of the dissipated power is radiated in
the corona above the disk.


title:
Numerical study of Anderson localization of terahertz waves in
  disordered waveguides

abstract:
  We present a numerical study of electromagnetic wave transport in disordered
quasi-one-dimensional waveguides at terahertz frequencies. Finite element
method calculations of terahertz wave propagation within LiNbO$_{3}$ waveguides
with randomly arranged air-filled circular scatterers exhibit an onset of
Anderson localization at experimentally accessible length scales. Results for
the average transmission as a function of waveguide length and scatterer
density demonstrate a clear crossover from diffusive to localized transport
regime. In addition, we find that transmission fluctuations grow dramatically
when crossing into the localized regime. Our numerical results are in good
quantitative agreement with theory over a wide range of experimentally
accessible parameters both in the diffusive and localized regime opening the
path towards experimental observation of terahertz wave localization.


title: Number-conserving approaches to $n$-component Bose-Einstein condensates

abstract:
  We develop the number-conserving approach that has previously been used in a
single component Bose-Einstein condensed dilute atomic gas, to describe
consistent coupled condensate and noncondensate number dynamics, to an
$n$-component condensate. The resulting system of equations comprises, for each
component, of a generalised Gross-Pitaevskii equation coupled to modified
Bogoliubov-de Gennes equations. Lower-order approximations yield general
formulations for multi-component Gross-Pitaevskii equations, and systems of
multi-component Gross-Pitaevskii equations coupled to multi-component modified
number-conserving Bogoliubov-de Gennes equations. The analysis is left general,
such that, in the $n$-component condensate, there may or may not be mutually
coherent components. An expansion in powers of the ratio of noncondensate to
condensate particle numbers for each coherent set is used to derive the
self-consistent, second-order, dynamical equations of motion. The advantage of
the analysis developed in this article is in its applications to dynamical
instabilities that appear when two (or more) components are in conflict and
where a significant noncondensed fraction of atoms is expected to appear.


title:
On Classical Solvability for a Linear 1D Heat Equation with Constant
  Delay

abstract:
  In this paper, we consider a linear heat equation with constant coefficients
and a single constant delay. Such equations are commonly used to model and
study various problems arising in ecology and population biology when
describing the temporal evolution of human or animal populations accounting for
migration, interaction with the environment and certain aftereffects caused by
diseases or enviromental polution, etc. Whereas dynamical systems with lumped
parameters have been addressed in numerous investigations, there still remain a
lot of open questions for the case of systems with distributed parameters,
especially when the delay effects are incorporated. Here, we consider a general
non-homogeneous one-dimensional heat equation with delay in both higher and
lower order terms subject to non-homogeneous initial and boundary conditions.
For this, we prove the unique existence of a classical solution as well as its
continuous dependence on the data.


title: Laser damage in silicon: energy absorption, relaxation and transport

abstract:
  Silicon irradiated with an ultrashort 800 nm-laser pulse is studied
theoretically using a two temperature description that considers the transient
free carrier density during and after irradiation. A Drude model is implemented
to account for the highly transient optical parameters. We analyze the
importance of considering these density-dependent parameters as well as the
choice of the Drude collision frequency. In addition, degeneracy and transport
effects are investigated. The importance of each of these processes for
resulting calculated damage thresholds is studied.We report damage thresholds
calculations that are in very good agreement with experimental results over a
wide range of pulse durations.


title:
Construction of Exact Control for a One-Dimensional Heat Equation with
  Delay

abstract:
  We prove an exact controllability result for a one-dimensional heat equation
with delay in both lower and highest order terms and nonhomogeneous Dirichlet
boundary conditions. Moreover, we give an explicit representation of the
control function steering the system into a given final state. Under certain
decay properties for corresponding Fourier coefficients which can be
interpreted as a sufficiently high Sobolev regularity of the data, both control
function and the solution are proved to be regular in the classical sense both
with respect to time and space variables.


title: Dichotomy on intervals of strong partial Boolean clones

abstract:
  The following result has been shown recently in the form of a dichotomy: For
every total clone $C$ on $\mathbf{2} := \{0,1\}$, the set $\mathcal{I}(C)$ of
all partial clones on $\mathbf{2}$ whose total component is $C$, is either
finite or of continuum cardinality. In this paper we show that the dichotomy
holds, even if only strong partial clones are considered, i.e., partial clones
which are closed under taking subfunctions: For every total clone $C$ on
$\mathbf{2}$, the set $\mathcal{I}_{\mathrm{Str}}(C)$ of all strong partial
clones on $\mathbf{2}$ whose total component is $C$, is either finite or of
continuum cardinality.


title: Estimate nothing

abstract:
  In the econometrics of financial time series, it is customary to take some
parametric model for the data, and then estimate the parameters from historical
data. This approach suffers from several problems. Firstly, how is estimation
error to be quantified, and then taken into account when making statements
about the future behaviour of the observed time series? Secondly, decisions may
be taken today committing to future actions over some quite long horizon, as in
the trading of derivatives; if the model is re-estimated at some intermediate
time, our earlier decisions would need to be revised - but the derivative has
already been traded at the earlier price. Thirdly, the exact form of the
parametric model to be used is generally taken as given at the outset; other
competitor models might possibly work better in some circumstances, but the
methodology does not allow them to be factored into the inference. What we
propose here is a very simple (Bayesian) alternative approach to inference and
action in financial econometrics which deals decisively with all these issues.
The key feature is that nothing is being estimated.


title:
Representation of Classical Solutions to a Linear Wave Equation with
  Pure Delay

abstract:
  For a wave equation with pure delay, we study an inhomogeneous
initial-boundary value problem in a bounded 1D domain. Under smoothness
assumptions, we prove unique existence of classical solutions for any given
finite time horizon and give their explicit representation. Continuous
dependence on the data in a weak extrapolated norm is also shown.


title:
Percolation induced effects in 2D coined quantum walks: analytic
  asymptotic solutions

abstract:
  Quantum walks on graphs can model physical processes and serve as efficient
tools in quantum information theory. Once we admit random variations in the
connectivity of the underlying graph, we arrive at the problem of percolation,
where the long-time behaviour appears untreatable with direct numerical
methods. We develop novel analytic methods based on the theory of random
unitary operations which help us to determine explicitly the asymptotic
dynamics of quantum walks on 2D finite integer lattices with percolation. Based
on this theory we find new unexpected features of percolated walks like
asymptotic position inhomogeneity or special directional symmetry breaking.


title:
On Stability of Hyperbolic Thermoelastic Reissner-Mindlin-Timoshenko
  Plates

abstract:
  In the present article, we consider a thermoelastic plate of
Reissner-Mindlin-Timoshenko type with the hyperbolic heat conduction arising
from Cattaneo's law. In the absense of any additional mechanical dissipations,
the system is often not even strongly stable unless restricted to the
rotationally symmetric case, etc. We present a well-posedness result for the
linear problem under general mixed boundary conditions for the elastic and
thermal parts. For the case of a clamped, thermally isolated plate, we show an
exponential energy decay rate under a full damping for all elastic variables.
Restricting the problem to the rotationally symmetric case, we further prove
that a single frictional damping merely for the bending compoment is sufficient
for exponential stability. To this end, we construct a Lyapunov functional
incorporating the Bogovski\u{i} operator for irrotational vector fields which
we discuss in the appendix.


title: Entanglement Purification with the Exchange Interaction

abstract:
  Entanglement purification allows the creation of qubit pairs of arbitrarily
high fidelity with respect to a maximally entangled state, starting from a
larger number of low-fidelity pairs. Purification requires quantum memory, a
role for which electron spins are well suited. However, using existing
recurrence protocols involving symmetric local two-qubit operations for spin
qubits turns out to be rather unpractical. We present an efficient purification
protocol requiring only a single pulsed Heisenberg- or XY-type exchange
interaction between two qubit pairs. In contrast to known protocols, we allow
for asymmetric bilateral two-qubit operations where the two communication
parties operate differently on their qubits. In the optimal version of our
protocol, the local two-qubit interactions in the case of Heisenberg exchange
correspond to the $\sqrt{\mathrm{SWAP}}$ gate and its inverse.


title:
Order-Parameter Symmetries of Domain Walls in Ferroelectrics and
  Ferroelastics

abstract:
  The symmetry of boundaries between ferroelectric, ferroelastic and antiphase
domains is a key element for a theoretical understanding of their properties.
Here, we derive this symmetry from their organic relation to the symmetry of
the primary transition order parameters. The domain wall symmetries are shown
to coincide with directions of the order-parameter n-dimensional vector space,
corresponding to sum of the vectors associated with adjacent domain states.
This property is illustrated by the determination of the domain wall maximal
symmetries in BaTiO3, LaAlO3, SrTiO3 and Gd2(MoO4)3. Besides, the domain
pattern in YMnO3 is interpreted as resulting from an annihilation-creation
process, the annihilation of the antiphase domain walls creating six
ferroelectric domain walls merging at a single point.


title: Time-like reductions of five-dimensional supergravity

abstract:
  In this paper we study the scalar geometries occurring in the dimensional
reduction of minimal five-dimensional supergravity to three Euclidean
dimensions, and find that these depend on whether one first reduces over space
or over time. In both cases the scalar manifold of the reduced theory is
described as an eight-dimensional Lie group $L$ (the Iwasawa subgroup of
$G_{2(2)}$) with a left-invariant para-quaternionic-K\"ahler structure. We show
that depending on whether one reduces first over space or over time, the group
$L$ is mapped to two different open $L$-orbits on the pseudo-Riemannian
symmetric space $G_{2(2)}/(SL(2) \cdot SL(2))$. These two orbits are
inequivalent in the sense that they are distinguished by the existence of
integrable $L$-invariant complex or para-complex structures.


title:
A spectral approach to a constrained optimization problem for the
  Helmholtz equation in unbounded domains

abstract:
  We study some convergence issues for a recent approach to the problem of
transparent boundary conditions for the Helmholtz equation in unbounded
domains. The approach is based on the minimization on an integral functional
which arises from an integral formulation of the radiation condition at
infinity. In this Letter, we implement a Fourier-Chebyschev collocation method
and show that this approach reduce the computational cost significantly. As a
consequence, we give numerical evidence of some convergence estimates available
in literature and we study the robustness of the algorithm at low and mid-high
frequencies.


title: Generalized Biwords for Bitext Compression and Translation Spotting

abstract:
  Large bilingual parallel texts (also known as bitexts) are usually stored in
a compressed form, and previous work has shown that they can be more
efficiently compressed if the fact that the two texts are mutual translations
is exploited. For example, a bitext can be seen as a sequence of biwords
---pairs of parallel words with a high probability of co-occurrence--- that can
be used as an intermediate representation in the compression process. However,
the simple biword approach described in the literature can only exploit
one-to-one word alignments and cannot tackle the reordering of words. We
therefore introduce a generalization of biwords which can describe multi-word
expressions and reorderings. We also describe some methods for the binary
compression of generalized biword sequences, and compare their performance when
different schemes are applied to the extraction of the biword sequence. In
addition, we show that this generalization of biwords allows for the
implementation of an efficient algorithm to look on the compressed bitext for
words or text segments in one of the texts and retrieve their counterpart
translations in the other text ---an application usually referred to as
translation spotting--- with only some minor modifications in the compression
algorithm.


title:
How science maps reveal knowledge transfer: new measurement for a
  historical case

abstract:
  Modelling actors of science via science (overlay) maps has recently become a
popular practice in Interdisciplinarity Research (IDR). The benefits of this
toolkit have also been recognized for other areas of scientometrics, such as
the study of science dynamics. In this paper we propose novel methods of
measuring knowledge diffusion/integration based on previous applications of the
overlay methodology. New indices called Mean Overlay Distance and Overlay
Diversity Ratio, respectively, are being drawn from previous uses of the
Stirling index as the main proxy for knowledge diversification. We demonstrate
the added value of this proposal via a case study addressing the development of
a rather complex discourse in biology, usually referred to as the Species
Problem. The selected topic is known for a history connecting various research
fields and traditions, being, therefore, both an ideal and challenging case for
the study of knowledge diffusion.


title:
A Novel Proof for the DoF Region of the MIMO Broadcast Channel with No
  CSIT

abstract:
  In this paper, a new proof for the degrees of freedom (DoF) region of the
K-user multiple-input multiple-output (MIMO) broadcast channel (BC) with no
channel state information at the transmitter (CSIT) and perfect channel state
information at the receivers (CSIR) is provided. Based on this proof, the
capacity region of a certain class of MIMO BC with channel distribution
information at the transmitter (CDIT) and perfect CSIR is derived. Finally, an
outer bound for the DoF region of the MIMO interference channel (IC) with no
CSIT is provided.


title: Fast LTL Satisfiability Checking by SAT Solvers

abstract:
  Satisfiability checking for Linear Temporal Logic (LTL) is a fundamental step
in checking for possible errors in LTL assertions. Extant LTL satisfiability
checkers use a variety of different search procedures. With the sole exception
of LTL satisfiability checking based on bounded model checking, which does not
provide a complete decision procedure, LTL satisfiability checkers have not
taken advantage of the remarkable progress over the past 20 years in Boolean
satisfiability solving. In this paper, we propose a new LTL
satisfiability-checking framework that is accelerated using a Boolean SAT
solver. Our approach is based on the variant of the \emph{obligation-set
method}, which we proposed in earlier work. We describe here heuristics that
allow the use of a Boolean SAT solver to analyze the obligations for a given
LTL formula. The experimental evaluation indicates that the new approach
provides a a significant performance advantage.


title: On the hyperbolicity of random graphs

abstract:
  Let $G=(V,E)$ be a connected graph with the usual (graph) distance metric
$d:V \times V \to N \cup \{0 \}$. Introduced by Gromov, $G$ is
$\delta$-hyperbolic if for every four vertices $u,v,x,y \in V$, the two largest
values of the three sums $d(u,v)+d(x,y), d(u,x)+d(v,y), d(u,y)+d(v,x)$ differ
by at most $2\delta$. In this paper, we determinate the value of this
hyperbolicity for most binomial random graphs.


title: Patterns in random permutations avoiding the pattern 132

abstract:
  We consider a random permutation drawn from the set of 132-avoiding
permutations of length $n$ and show that the number of occurrences of another
pattern $\sigma$ has a limit distribution, after scaling by
$n^{\lambda(\sigma)/2}$ where $\lambda(\sigma)$ is the length of $\sigma$ plus
the number of descents. The limit is not normal, and can be expressed as a
functional of a Brownian excursion. Moments can be found by recursion.


title:
Interaction-induced anomalous quantum Hall state on the honeycomb
  lattice

abstract:
  We examine the existence of the interaction-generated quantum anomalous Hall
phase on the honeycomb lattice. For the spinless model at half filling, the
existence of a quantum anomalous Hall phase (Chern insulator phase) has been
predicted using mean-field methods. However, recent exact diagonalization
studies for small clusters with periodic boundary condition have not found a
clear sign of an interaction-driven Chern insulator phase. We use exact
diagonalization method to study properties of small clusters with open boundary
condition and, contrary to previous studies, we find clear signatures of the
topological phase transition for finite size clusters. We also examine
applicability of the entangled-plaquette state (correlator-product state)
ansatz to describe the ground states of the system. Within this approach the
lattice is covered with plaquettes and the ground state wave-function is
written in terms of the plaquette coefficients. Configurational weights can
then be optimized using a variational Monte Carlo algorithm. Using the
entangled-plaquette state ansatz we study the ground state properties of the
system for larger system sizes and show that the results agree with the exact
diagonalization results for small clusters. This confirms validity of the
entangled-plaquette state ansatz to describe the ground states of the system
and provides further confirmation of the existence of the quantum anomalous
Hall phase in the thermodynamic limit, as predicted by the mean-field theory
calculations.


title:
Becoming the Change: A Critical Evaluation of the Changing Face of Life
  Science, as Reflected in the NGSS

abstract:
  Tennessee is one of the 26 lead state partners that volunteered to provide
leadership and guidance to states for the purpose of adoption of Next
Generation Science Standards (NGSS. As stated in the Tennessee Vision for STEM
Education (2009), "Tennessee recognizes the importance of science and aims to
commit to this understanding by becoming involved in the development, and
eventual adoption and implementation of NGSS." The present study correlates the
Tennessee State Science Standards to the NGSS for High School Biology/ Life
Sciences and examines the need for a dynamic set of standards that teach the
technical skills and critical thinking needed in these scientific fields. The
NGSS addresses a move from dated scientific quandaries and proposes standards
supported by cutting edge scientific research and literature. Partnerships
between scientists and educators allow for the information exchange necessary
to implement the changes in scientific research in K-12 instruction.
Professional development opportunities that include direct partnerships with
scientists foster the continued understanding and skills required to teach
science.


title:
The Role of Quantum Fluctuations in the Hexatic Phase of Cold Polar
  Molecules

abstract:
  Two dimensional crystals melt via an intermediate \textit{hexatic} phase
which is characterized by an anomalous scaling of spatial and orientational
correlation functions and the absence of an attraction between dislocations. We
propose a protocol to study the role of quantum fluctuations on the nature of
this phase with a system of strongly correlated polar molecules in a parameter
regime where thermal and quantum fluctuations are of the same order of
magnitude. The dislocations can be located in experiment from local energy
differences which induce internal stark shifts in dislocation molecules. We
present a criterium to identify the hexatic phase from the statistics of the
end points of topological defect strings and find a hexatic phase, which is
dominated by quantum fluctuations, between crystal and superfluid phase.


title: Hydrodynamics of compressible superfluids in confined geometries

abstract:
  We present a study of the hydrodynamics of compressible superfluids in
confined geometries. We use a perturbative procedure in terms of the
dimensionless expansion parameter $(v/v_s)^2$ where $v$ is the typical speed of
the flow and $v_s$ the speed of sound. A zero value of this parameter
corresponds to the incompressible limit. We apply the procedure to two specific
problems: the case of a trapped superfluid with a gaussian profile of the local
density, and that of a superfluid confined in a rotating obstructed cylinder.
We find that the corrections due to finite compressibility which are, as
expected, negligible for liquid He, are important but amenable to the
perturbative treatment for typical ultracold atomic systems.


title: Model-based clustering for conditionally correlated categorical data

abstract:
  An extension of the latent class model is presented for clustering
categorical data by relaxing the classical "class conditional independence
assumption" of variables. This model consists in grouping the variables into
inter-independent and intra-dependent blocks, in order to consider the main
intra-class correlations. The dependency between variables grouped inside the
same block of a class is taken into account by mixing two extreme
distributions, which are respectively the independence and the maximum
dependency. When the variables are dependent given the class, this approach is
expected to reduce the biases of the latent class model. Indeed, it produces a
meaningful dependency model with only a few additional parameters. The
parameters are estimated, by maximum likelihood, by means of an EM algorithm.
Moreover, a Gibbs sampler is used for model selection in order to overcome the
computational intractability of the combinatorial problems involved by the
block structure search. Two applications on medical and biological data sets
show the relevance of this new model. The results strengthen the view that this
model is meaningful and that it reduces the biases induced by the conditional
independence assumption of the latent class model.


title: Sparre-Andersen theorem with spatiotemporal correlations

abstract:
  The Sparre-Andersen theorem is a remarkable result in one-dimensional random
walk theory concerning the universality of the ubiquitous first-passage-time
distribution. It states that the probability distribution $\rho_n$ of the
number of steps needed for a walker starting at the origin to land on the
positive semi-axes does not depend on the details of the distribution for the
jumps of the walker, provided this distribution is symmetric and continuous,
where in particular $\rho_n \sim n^{-3/2}$ for large number of steps $n$. On
the other hand, there are many physical situations in which the time spent by
the walker in doing one step depends on the length of the step and the interest
concentrates on the time needed for a return, not on the number of steps. Here
we modify the Sparre-Andersen proof to deal with such cases, in rather general
situations in which the time variable correlates with the step variable. As an
example we present a natural process in 2D that shows deviations from normal
scaling are present for the first-passage-time distribution on a semi plane.


title:
Increasing Server Availability for Overall System Security: A Preventive
  Maintenance Approach Based on Failure Prediction

abstract:
  Server Availability (SA) is an important measure of overall systems security.
Important security systems rely on the availability of their hosting servers to
deliver critical security services. Many of these servers offer management
interface through web mainly using an Apache server. This paper investigates
the increase of Server Availability by the use of Artificial Neural Networks
(ANN) to predict software aging phenomenon. Several resource usage data is
collected and analyzed on a typical long-running software system (a web
server). A Multi-Layer Perceptron feed forward Artificial Neural Network was
trained on an Apache web server data-set to predict future server resource
exhaustion through uni-variate time series forecasting. The results were
benchmarked against those obtained from non-parametric statistical techniques,
parametric time series models and empirical modeling techniques reported in the
literature.


title: X-Ray Luminous Binaries, Metallicity, and the Early Universe

abstract:
  High mass X-ray binaries (HMXBs) may have had a significant impact on the
heating of the intergalactic medium in the early universe. Study of HMXBs in
nearby, low metallicity galaxies that are local analogues to early galaxies can
help us understand early HMXBs. The total luminosity of HMXB populations is
dominated by sources at high luminosities. These sources exhibit X-ray spectra
that show curvature above 2 keV and the same is likely true of HMXB populations
at high redshifts. The spectral curvature changes the K-correction for X-rays
from HMXBs in a manner that weakens the constraints on X-ray emission of early
HMXBs obtained from the soft X-ray background. Applied to deep X-ray surveys of
star forming galaxies, the modified K-correction suggests a moderate increase
in the ratio of X-ray luminosity to star formation rate at intermediate
redshifts, z=3-5, and is consistent with a large enhancement at high redshifts,
z=6-7.


title:
Capacities and Capacity-Achieving Decoders for Various Fingerprinting
  Games

abstract:
  Combining an information-theoretic approach to fingerprinting with a more
constructive, statistical approach, we derive new results on the fingerprinting
capacities for various informed settings, as well as new log-likelihood
decoders with provable code lengths that asymptotically match these capacities.
The simple decoder built against the interleaving attack is further shown to
achieve the simple capacity for unknown attacks, and is argued to be an
improved version of the recently proposed decoder of Oosterwijk et al. With
this new universal decoder, cut-offs on the bias distribution function can
finally be dismissed.
  Besides the application of these results to fingerprinting, a direct
consequence of our results to group testing is that (i) a simple decoder
asymptotically requires a factor 1.44 more tests to find defectives than a
joint decoder, and (ii) the simple decoder presented in this paper provably
achieves this bound.


title: Homogenization of lateral diffusion on a random surface

abstract:
  We study the problem of lateral diffusion on a static, quasi-planar surface
generated by a stationary, ergodic random field possessing rapid small-scale
spatial fluctuations. The aim is to study the effective behaviour of a particle
undergoing Brownian motion on the surface viewed as a projection on the
underlying plane. By formulating the problem as a diffusion in a random medium,
we are able to use known results from the theory of stochastic homogenization
of SDEs to show that, in the limit of small scale fluctuations, the diffusion
process behaves quantitatively like a Brownian motion with constant diffusion
tensor $D$. While $D$ will not have a closed-form expression in general, we are
able to derive variational bounds for the effective diffusion tensor, and using
a duality transformation argument, obtain a closed form expression for $D$ in
the special case where $D$ is isotropic. We also describe a numerical scheme
for approximating the effective diffusion tensor and illustrate this scheme
with two examples.


title: On the Complexity of Computing with Planar Algebraic Curves

abstract:
  In this paper, we give improved bounds for the computational complexity of
computing with planar algebraic curves. More specifically, for arbitrary
coprime polynomials $f$, $g \in \mathbb{Z}[x,y]$ and an arbitrary polynomial $h
\in \mathbb{Z}[x,y]$, each of total degree less than $n$ and with integer
coefficients of absolute value less than $2^\tau$, we show that each of the
following problems can be solved in a deterministic way with a number of bit
operations bounded by $\tilde{O}(n^6+n^5\tau)$, where we ignore polylogarithmic
factors in $n$ and $\tau$:
  (1) The computation of isolating regions in $\mathbb{C}^2$ for all complex
solutions of the system $f = g = 0$,
  (2) the computation of a separating form for the solutions of $f = g = 0$,
  (3) the computation of the sign of $h$ at all real valued solutions of $f = g
= 0$, and
  (4) the computation of the topology of the planar algebraic curve
$\mathcal{C}$ defined as the real valued vanishing set of the polynomial $f$.
  Our bound improves upon the best currently known bounds for the first three
problems by a factor of $n^2$ or more and closes the gap to the
state-of-the-art randomized complexity for the last problem.


title:
On the integrability of a new lattice equation found by multiple scale
  analysis

abstract:
  In this paper we discuss the integrability properties of a nonlinear partial
difference equation on the square obtained by the multiple scale integrability
test from a class of multilinear dispersive equations defined on a four points
lattice.


title:
Magnetic susceptibility of frustrated spin-s J1-J2 quantum Heisenberg
  magnets: High-temperature expansion and exact diagonalization data

abstract:
  Motivated by recent experiments on low-dimensional frustrated quantum magnets
with competing nearest-neighbor exchange coupling J1 and next nearest-neighbor
exchange coupling J2 we investigate the magnetic susceptibility of
two-dimensional J1-J2 Heisenberg models with arbitrary spin quantum number s.
We use exact diagonalization and high-temperature expansion up to order 10 to
analyze the influence of the frustration strength J2/J1 and the spin quantum
number s on the position and the height of the maximum of the susceptibility.
The derived theoretical data can be used to get information on the ratio J2/J1
by comparing with susceptibility measurements on corresponding magnetic
compounds.


title: Sentence Compression as Tree Transduction

abstract:
  This paper presents a tree-to-tree transduction method for sentence
compression. Our model is based on synchronous tree substitution grammar, a
formalism that allows local distortion of the tree topology and can thus
naturally capture structural mismatches. We describe an algorithm for decoding
in this framework and show how the model can be trained discriminatively within
a large margin framework. Experimental results on sentence compression bring
significant improvements over a state-of-the-art model.


title: Cross-lingual Annotation Projection for Semantic Roles

abstract:
  This article considers the task of automatically inducing role-semantic
annotations in the FrameNet paradigm for new languages. We propose a general
framework that is based on annotation projection, phrased as a graph
optimization problem. It is relatively inexpensive and has the potential to
reduce the human effort involved in creating role-semantic resources. Within
this framework, we present projection models that exploit lexical and syntactic
information. We provide an experimental evaluation on an English-German
parallel corpus which demonstrates the feasibility of inducing high-precision
German semantic role annotation both for manually and automatically annotated
English data.


title: Multilingual Part-of-Speech Tagging: Two Unsupervised Approaches

abstract:
  We demonstrate the effectiveness of multilingual learning for unsupervised
part-of-speech tagging. The central assumption of our work is that by combining
cues from multiple languages, the structure of each becomes more apparent. We
consider two ways of applying this intuition to the problem of unsupervised
part-of-speech tagging: a model that directly merges tag structures for a pair
of languages into a single sequence and a second model which instead
incorporates multilingual context using latent variables. Both approaches are
formulated as hierarchical Bayesian models, using Markov Chain Monte Carlo
sampling techniques for inference. Our results demonstrate that by
incorporating multilingual evidence we can achieve impressive performance gains
across a range of scenarios. We also found that performance improves steadily
as the number of available languages increases.


title:
Unsupervised Methods for Determining Object and Relation Synonyms on the
  Web

abstract:
  The task of identifying synonymous relations and objects, or synonym
resolution, is critical for high-quality information extraction. This paper
investigates synonym resolution in the context of unsupervised information
extraction, where neither hand-tagged training examples nor domain knowledge is
available. The paper presents a scalable, fully-implemented system that runs in
O(KN log N) time in the number of extractions, N, and the maximum number of
synonyms per word, K. The system, called Resolver, introduces a probabilistic
relational model for predicting whether two strings are co-referential based on
the similarity of the assertions containing them. On a set of two million
assertions extracted from the Web, Resolver resolves objects with 78% precision
and 68% recall, and resolves relations with 90% precision and 35% recall.
Several variations of resolvers probabilistic model are explored, and
experiments demonstrate that under appropriate conditions these variations can
improve F1 by 5%. An extension to the basic Resolver system allows it to handle
polysemous names with 97% precision and 95% recall on a data set from the TREC
corpus.


title: Wikipedia-based Semantic Interpretation for Natural Language Processing

abstract:
  Adequate representation of natural language semantics requires access to vast
amounts of common sense and domain-specific world knowledge. Prior work in the
field was based on purely statistical techniques that did not make use of
background knowledge, on limited lexicographic knowledge bases such as WordNet,
or on huge manual efforts such as the CYC project. Here we propose a novel
method, called Explicit Semantic Analysis (ESA), for fine-grained semantic
interpretation of unrestricted natural language texts. Our method represents
meaning in a high-dimensional space of concepts derived from Wikipedia, the
largest encyclopedia in existence. We explicitly represent the meaning of any
text in terms of Wikipedia-based concepts. We evaluate the effectiveness of our
method on text categorization and on computing the degree of semantic
relatedness between fragments of natural language text. Using ESA results in
significant improvements over the previous state of the art in both tasks.
Importantly, due to the use of natural concepts, the ESA model is easy to
explain to human users.


title: Identification of Pleonastic It Using the Web

abstract:
  In a significant minority of cases, certain pronouns, especially the pronoun
it, can be used without referring to any specific entity. This phenomenon of
pleonastic pronoun usage poses serious problems for systems aiming at even a
shallow understanding of natural language texts. In this paper, a novel
approach is proposed to identify such uses of it: the extrapositional cases are
identified using a series of queries against the web, and the cleft cases are
identified using a simple set of syntactic rules. The system is evaluated with
four sets of news articles containing 679 extrapositional cases as well as 78
cleft constructs. The identification results are comparable to those obtained
by human efforts.


title: Text Relatedness Based on a Word Thesaurus

abstract:
  The computation of relatedness between two fragments of text in an automated
manner requires taking into account a wide range of factors pertaining to the
meaning the two fragments convey, and the pairwise relations between their
words. Without doubt, a measure of relatedness between text segments must take
into account both the lexical and the semantic relatedness between words. Such
a measure that captures well both aspects of text relatedness may help in many
tasks, such as text retrieval, classification and clustering. In this paper we
present a new approach for measuring the semantic relatedness between words
based on their implicit semantic links. The approach exploits only a word
thesaurus in order to devise implicit semantic links between words. Based on
this approach, we introduce Omiotis, a new measure of semantic relatedness
between texts which capitalizes on the word-to-word semantic relatedness
measure (SR) and extends it to measure the relatedness between texts. We
gradually validate our method: we first evaluate the performance of the
semantic relatedness measure between individual words, covering word-to-word
similarity and relatedness, synonym identification and word analogy; then, we
proceed with evaluating the performance of our method in measuring text-to-text
semantic relatedness in two tasks, namely sentence-to-sentence similarity and
paraphrase recognition. Experimental evaluation shows that the proposed method
outperforms every lexicon-based method of semantic relatedness in the selected
tasks and the used data sets, and competes well against corpus-based and hybrid
approaches.


title:
Inferring Shallow-Transfer Machine Translation Rules from Small Parallel
  Corpora

abstract:
  This paper describes a method for the automatic inference of structural
transfer rules to be used in a shallow-transfer machine translation (MT) system
from small parallel corpora. The structural transfer rules are based on
alignment templates, like those used in statistical MT. Alignment templates are
extracted from sentence-aligned parallel corpora and extended with a set of
restrictions which are derived from the bilingual dictionary of the MT system
and control their application as transfer rules. The experiments conducted
using three different language pairs in the free/open-source MT platform
Apertium show that translation quality is improved as compared to word-for-word
translation (when no transfer rules are used), and that the resulting
translation quality is close to that obtained using hand-coded transfer rules.
The method we present is entirely unsupervised and benefits from information in
the rest of modules of the MT system in which the inferred rules are applied.


title: Mesoscopic and continuum modelling of angiogenesis

abstract:
  Angiogenesis is the formation of new blood vessels from pre-existing ones in
response to chemical signals secreted by, for example, a wound or a tumour. In
this paper, we propose a mesoscopic lattice-based model of angiogenesis, in
which processes that include proliferation and cell movement are considered as
stochastic events. By studying the dependence of the model on the lattice
spacing and the number of cells involved, we are able to derive the
deterministic continuum limit of our equations and compare it to similar
existing models of angiogenesis. We further identify conditions under which the
use of continuum models is justified, and others for which stochastic or
discrete effects dominate. We also compare different stochastic models for the
movement of endothelial tip cells which have the same macroscopic,
deterministic behaviour, but lead to markedly different behaviour in terms of
production of new vessel cells.


title: On a generalization of affinoid varieties

abstract:
  In this thesis we develop the foundations for a theory of analytic geometry
over a valued field, uniformly encompassing the case when the base field is
equipped with a non-archimedean valuation and the case when it has an
archimedean one. Our building blocks are dagger affinoid algebras, i.e.
algebras of germs of analytic functions, equipped with their canonical
bornology. We obtain results akin to the ones of affinoid algebras and affinoid
spaces theory in our context. In particular, we give a generalization of the
celebrated Gerritzen-Grauert theorem. Finally, we construct the category of
dagger analytic spaces and compare its objects with classical objects from
Berkovich geometry, dagger spaces of Grosse-Klonne and complex analytic spaces.


title:
Low-Complexity Polynomial Channel Estimation in Large-Scale MIMO with
  Arbitrary Statistics

abstract:
  This paper considers pilot-based channel estimation in large-scale
multiple-input multiple-output (MIMO) communication systems, also known as
massive MIMO, where there are hundreds of antennas at one side of the link.
Motivated by the fact that computational complexity is one of the main
challenges in such systems, a set of low-complexity Bayesian channel
estimators, coined Polynomial ExpAnsion CHannel (PEACH) estimators, are
introduced for arbitrary channel and interference statistics. While the
conventional minimum mean square error (MMSE) estimator has cubic complexity in
the dimension of the covariance matrices, due to an inversion operation, our
proposed estimators significantly reduce this to square complexity by
approximating the inverse by a L-degree matrix polynomial. The coefficients of
the polynomial are optimized to minimize the mean square error (MSE) of the
estimate.
  We show numerically that near-optimal MSEs are achieved with low polynomial
degrees. We also derive the exact computational complexity of the proposed
estimators, in terms of the floating-point operations (FLOPs), by which we
prove that the proposed estimators outperform the conventional estimators in
large-scale MIMO systems of practical dimensions while providing a reasonable
MSEs. Moreover, we show that L needs not scale with the system dimensions to
maintain a certain normalized MSE. By analyzing different interference
scenarios, we observe that the relative MSE loss of using the low-complexity
PEACH estimators is smaller in realistic scenarios with pilot contamination. On
the other hand, PEACH estimators are not well suited for noise-limited
scenarios with high pilot power; therefore, we also introduce the
low-complexity diagonalized estimator that performs well in this regime.
Finally, we ...


title:
Coherence effects in scattering order expansion of light by atomic
  clouds

abstract:
  We interpret cooperative scattering by a collection of cold atoms as a
multiple scattering process. Starting from microscopic equations describing the
response of $N$ atoms to a probe light beam, we represent the total scattered
field as an infinite series of multiple scattering events. As an application of
the method, we obtain analytical expressions of the coherent intensity in the
double scattering approximation for Gaussian density profiles. In particular,
we quantify the contributions of coherent backward and forward scattering.


title:
Long-Term Timing and Glitch Characteristics of Anomalous X-ray Pulsar
  1RXS J170849.0-400910

abstract:
  We present the results of our detailed timing studies of an anomalous X-ray
pulsar, 1RXS J170849.0-400910, using Rossi X-ray Timing Explorer (RXTE)
observations spanning over ~6 yr from 2005 until the end of RXTE mission. We
constructed the long-term spin characteristics of the source and investigated
time and energy dependence of pulse profile and pulsed count rates. We find
that pulse profile and pulsed count rates in the 2-10 keV band do not show any
significant variations in ~6 yr. 1RXS J170849.0-400910 has been the most
frequently glitching anomalous X-ray pulsar: three spin-up glitches and three
candidate glitches were observed prior to 2005. Our extensive search for
glitches later in the timeline resulted in no unambiguous glitches though we
identified two glitch candidates (with Delta(nu)/nu ~10^{-6}) in two data gaps:
a strong candidate around MJD 55532 and another one around MJD 54819, which is
slightly less robust. We discuss our results in the context of pulsar glitch
models and expectancy of glitches within the vortex unpinning model.


title: Riemannian Holonomy Groups of Statistical Manifolds

abstract:
  Normal distribution manifolds play essential roles in the theory of
information geometry, so do holonomy groups in classification of Riemannian
manifolds. After some necessary preliminaries on information geometry and
holonomy groups, it is presented that the corresponding Riemannian holonomy
group of the $d$-dimensional normal distribution is
$SO\left(\frac{d\left(d+3\right)}{2}\right)$, for all $d\in\mathbb{N}$. As a
generalization on exponential family, a list of holonomy groups follows.


title: Relations between automata and the simple k-path problem

abstract:
  Let $G$ be a directed graph on $n$ vertices. Given an integer $k<=n$, the
SIMPLE $k$-PATH problem asks whether there exists a simple $k$-path in $G$. In
case $G$ is weighted, the MIN-WT SIMPLE $k$-PATH problem asks for a simple
$k$-path in $G$ of minimal weight. The fastest currently known deterministic
algorithm for MIN-WT SIMPLE $k$-PATH by Fomin, Lokshtanov and Saurabh runs in
time $O(2.851^k\cdot n^{O(1)}\cdot \log W)$ for graphs with integer weights in
the range $[-W,W]$. This is also the best currently known deterministic
algorithm for SIMPLE k-PATH- where the running time is the same without the
$\log W$ factor. We define $L_k(n)\subseteq [n]^k$ to be the set of words of
length $k$ whose symbols are all distinct. We show that an explicit
construction of a non-deterministic automaton (NFA) of size $f(k)\cdot
n^{O(1)}$ for $L_k(n)$ implies an algorithm of running time $O(f(k)\cdot
n^{O(1)}\cdot \log W)$ for MIN-WT SIMPLE $k$-PATH when the weights are
non-negative or the constructed NFA is acyclic as a directed graph. We show
that the algorithm of Kneis et al. and its derandomization by Chen et al. for
SIMPLE $k$-PATH can be used to construct an acylic NFA for $L_k(n)$ of size
$O^*(4^{k+o(k)})$.
  We show, on the other hand, that any NFA for $L_k(n)$ must be size at least
$2^k$. We thus propose closing this gap and determining the smallest NFA for
$L_k(n)$ as an interesting open problem that might lead to faster algorithms
for MIN-WT SIMPLE $k$-PATH.
  We use a relation between SIMPLE $k$-PATH and non-deterministic xor automata
(NXA) to give another direction for a deterministic algorithm with running time
$O^*(2^k)$ for SIMPLE $k$-PATH.


title: Quantum Electrodynamics of Atomic Resonances

abstract:
  A simple model of an atom interacting with the quantized electromagnetic
field is studied. The atom has a finite mass $m$, finitely many excited states
and an electric dipole moment, $\vec{d}_0 = -\lambda_{0} \vec{d}$, where $\|
d^{i}\| = 1,$ $ i=1,2,3,$ and $\lambda_0$ is proportional to the elementary
electric charge. The interaction of the atom with the radiation field is
described with the help of the Ritz Hamiltonian, $-\vec{d}_0\cdot \vec{E}$,
where $\vec{E}$ is the electric field, cut off at large frequencies. A
mathematical study of the Lamb shift, the decay channels and the life times of
the excited states of the atom is presented. It is rigorously proven that these
quantities are analytic functions of the momentum $\vec{p}$ of the atom and of
the coupling constant $\lambda_0$, provided $|\vec{p}| < mc$ and $| \Im\vec{p}
|$ and $| \lambda_{0} |$ are sufficiently small. The proof relies on a somewhat
novel inductive construction involving a sequence of `smooth Feshbach-Schur
maps' applied to a complex dilatation of the original Hamiltonian, which yields
an algorithm for the calculation of resonance energies that converges
super-exponentially fast.


title: Three Generalizations of Davenport-Schinzel Sequences

abstract:
  We present new, and mostly sharp, bounds on the maximum length of certain
generalizations of Davenport-Schinzel sequences. Among the results are sharp
bounds on order-$s$ {\em double DS} sequences, for all $s$, sharp bounds on
sequences avoiding {\em catenated permutations} (aka formation free sequences),
and new lower bounds on sequences avoiding {\em zig-zagging} patterns.


title:
Who is Dating Whom: Characterizing User Behaviors of a Large Online
  Dating Site

abstract:
  Online dating sites have become popular platforms for people to look for
potential romantic partners. It is important to understand users' dating
preferences in order to make better recommendations on potential dates. The
message sending and replying actions of a user are strong indicators for what
he/she is looking for in a potential date and reflect the user's actual dating
preferences. We study how users' online dating behaviors correlate with various
user attributes using a large real-world dateset from a major online dating
site in China. Many of our results on user messaging behavior align with
notions in social and evolutionary psychology: males tend to look for younger
females while females put more emphasis on the socioeconomic status (e.g.,
income, education level) of a potential date. In addition, we observe that the
geographic distance between two users and the photo count of users play an
important role in their dating behaviors. Our results show that it is important
to differentiate between users' true preferences and random selection. Some
user behaviors in choosing attributes in a potential date may largely be a
result of random selection. We also find that both males and females are more
likely to reply to users whose attributes come closest to the stated
preferences of the receivers, and there is significant discrepancy between a
user's stated dating preference and his/her actual online dating behavior.
These results can provide valuable guidelines to the design of a recommendation
engine for potential dates.


title: A report on Tarski's decidability problem

abstract:
  This paper contains a list of crucial mistakes and counterexamples to some of
the main statements in the paper "Elementary theory of free nonabelian groups"
by O. Kharlampovich and A. Myasnikov, which was published in the Journal of
Algebra in June 2006.


title: A quantum magnetic RC circuit

abstract:
  We propose a setup that is the spin analog of the charge-based quantum RC
circuit. We define and compute the spin capacitance and the spin resistance of
the circuit for both ferromagnetic (FM) and antiferromagnetic (AF) systems. We
find that the antiferromagnetic setup has universal properties, but the
ferromagnetic setup does not. We discuss how to use the proposed setup as a
quantum source of spin excitations, and put forward a possible experimental
realization using ultracold atoms in optical lattices.


title:
Dispersive wave emission and supercontinuum generation in a silicon wire
  waveguide pumped around the 1550 nm telecommunication wavelength

abstract:
  We experimentally and numerically study dispersive wave emission, soliton
fission and supercontinuum generation in a silicon wire at telecommunication
wavelengths. Through dispersion engineering, we experimentally confirm a
previously reported numerical study [1] and show that the emission of resonant
radiation from the solitons can lead to the generation of a supercontinuum
spanning over 500 nm. An excellent agreement with numerical simulations is
observed.


title: Reconfiguration of Dominating Sets

abstract:
  We explore a reconfiguration version of the dominating set problem, where a
dominating set in a graph $G$ is a set $S$ of vertices such that each vertex is
either in $S$ or has a neighbour in $S$. In a reconfiguration problem, the goal
is to determine whether there exists a sequence of feasible solutions
connecting given feasible solutions $s$ and $t$ such that each pair of
consecutive solutions is adjacent according to a specified adjacency relation.
Two dominating sets are adjacent if one can be formed from the other by the
addition or deletion of a single vertex.
  For various values of $k$, we consider properties of $D_k(G)$, the graph
consisting of a vertex for each dominating set of size at most $k$ and edges
specified by the adjacency relation. Addressing an open question posed by Haas
and Seyffarth, we demonstrate that $D_{\Gamma(G)+1}(G)$ is not necessarily
connected, for $\Gamma(G)$ the maximum cardinality of a minimal dominating set
in $G$. The result holds even when graphs are constrained to be planar, of
bounded tree-width, or $b$-partite for $b \ge 3$. Moreover, we construct an
infinite family of graphs such that $D_{\gamma(G)+1}(G)$ has exponential
diameter, for $\gamma(G)$ the minimum size of a dominating set. On the positive
side, we show that $D_{n-m}(G)$ is connected and of linear diameter for any
graph $G$ on $n$ vertices having at least $m+1$ independent edges.


title:
Degree of Chemical Non-equilibrium in Central Au-Au Collisions at RHIC
  energies

abstract:
  We investigate the difference between hadron resonance gas (HRG) calculations
for chemical freeze-out parameters at fully and partly chemical equilibria. To
this end, the results are compared with the particle ratios measured in central
Au-Au collisions at a wide range of nucleon-nucleon center-of-mass energies,
\hbox{$\sqrt{s_{NN}}=7.7-200 $GeV} as offered by the STAR experiment. We
restrict the discussion to STAR, because of large statistics and overall
homogeneity of STAR measurements (one detector) against previous experiments.
We find that the matter produced at these energies is likely in fully chemical
equilibrium, which is consistent with recent lattice QCD results. The possible
improvements by partial chemical equilibrium ($\gamma_S\neq 1$) are very
limited. We also discuss these results with the ones deduced from $\phi/\pi^-$
and $\Omega^-/\pi^-$ ratios. These hadron ratios are sensitive to the degree of
chemical equilibrium. Accordingly, the conclusion that the matter produced
reaches fully chemical equilibrium in central Au-Au at RHIC energies is
confirmed.


title: On the New Intersection Theorem for totally reflexive modules

abstract:
  Let (R,m,k) be a local ring. We establish a totally reflexive analogue of the
New Intersection Theorem, provided for every totally reflexive R-module M,
there is a big Cohen-Macaulay R-module B_M such that the socle of B_M\otimes_RM
is zero. When R is a quasi-specialization of a G-regular local ring or when M
has complete intersection dimension zero, we show the existence of such a big
Cohen-Macaulay R-module. It is conjectured that if R admits a non-zero
Cohen-Macaulay module of finite Gorenstein dimension, then it is
Cohen-Macaulay. We prove this conjecture if either R is a quasi-specialization
of a G-regular local ring or a quasi-Buchsbaum local ring.


title:
Relaxation and integral representation for functionals of linear growth
  on metric measure spaces

abstract:
  This article studies an integral representation of functionals of linear
growth on metric measure spaces with a doubling measure and a Poincar\'e
inequality. Such a functional is defined through relaxation, and it defines a
Radon measure on the space. For the singular part of the functional, we get the
expected integral representation with respect to the variation measure. A new
feature is that in the representation for the absolutely continuous part, a
constant appears already in the weighted Euclidean case. As an application we
show that in a variational minimization problem related to the functional,
boundary values can be presented as a penalty term.


title:
Dzyaloshinskii-Moriya nature of ferroelectric ordering in
  magnetoelectric Gd$_{1-x}$Y$_{x}$MnO$_{3}$ system

abstract:
  This work reports on magnetic, dielectric, thermodynamic and magnetoelectric
properties of Gd$_{1-x}$Y$_{x}$MnO$_{3}$, with 0 \leq x \leq 0.4, with emphasis
on the (x, T) phase diagram, towards unraveling the role of the driving
mechanisms in stabilizing both magnetic and ferroelectric orderings. The (x, T)
phase diagram reflects the effect of lattice distortions induced by the
substitution of $Gd^{3+}$ ion by smaller $Y^{3+}$ ion, which gradually
unbalances the antiferromagnetic against the ferromagnetic exchange
interactions, enabling the emergence of ferroelectricity for higher
concentrations of yttrium. For $x \leq 0.1$, the paramagnetic phase is followed
by a presumably incommensurate collinear antiferromagnetic phase, then a weak
ferromagnetic canted A-type antiferromagnetic ordering is established at lower
temperatures.For $0.2 \leq x \leq 0.4$, a different phase sequence is obtained.
The canted A-type antiferromagnetic arrangement is no more stable, and instead
a pure antiferromagnetic ordering is stabilized below T$_{lock}$ $\approx$ 14 -
17 K, with an improper ferroelectric character. From these results, a cycloid
modulated spin arrangement at low temperatures is proposed, accordingly to the
inverse Dzyaloshinskii Moriya model. Anomalous temperature dependence of the
dipolar relaxation energy and magnetization evidence for structural and
magnetic changes occurring at $T* \approx 22 - 28 K$, for $0.1 \leq x \leq
0.4$.


title:
Current-induced magnetization dynamics at the edge of a two-dimensional
  electron system with strong spin-orbit coupling

abstract:
  We experimentally investigate electron transport through the interface
between a permalloy ferromagnet and the edge of a two-dimensional electron
system with strong Rashba-type spin-orbit coupling. We observe strongly
non-linear transport around zero bias at millikelvin temperatures. The observed
nonlinearity is fully suppressed above some critical values of temperature,
magnetic field, and current through the interface. We interpret this behavior
as the result of spin accumulation at the interface and its current-induced
absorption as a magnetization torque.


title:
Entanglement Entropy as a Probe of the Proximity Effect in Holographic
  Superconductors

abstract:
  We study the entanglement entropy as a probe of the proximity effect of a
superconducting system by using the gauge/gravity duality in a fully
back-reacted gravity system. While the entanglement entropy in the
superconducting phase is less than the entanglement entropy in the normal
phase, we find that near the contact interface of the superconducting to normal
phase the entanglement entropy has a different behavior due to the leakage of
Cooper pairs to the normal phase. We verify this behavior by calculating the
conductivity near the boundary interface.


title:
Electromagnetic fields and potentials generated by massless charged
  particles

abstract:
  We provide for the first time the exact solution of Maxwell's equations for a
massless charged particle moving on a generic trajectory at the speed of light.
In particular we furnish explicit expressions for the vector potential and the
electromagnetic field, which were both previously unknown, finding that they
entail different physical features for bounded and unbounded trajectories. With
respect to the standard Lienard-Wiechert field the electromagnetic field
acquires singular delta-like contributions whose support and dimensionality
depend crucially on whether the motion is a) linear, b) accelerated unbounded,
c) accelerated bounded. In the first two cases the particle generates a planar
shock-wave-like electromagnetic field traveling along a straight line. In the
second and third cases the field acquires, in addition, a delta-like
contribution supported on a physical singularity-string attached to the
particle. For generic accelerated motions a genuine radiation field is also
present, represented by a regular principal-part type distribution diverging on
the same singularity-string.


title: Controlling Several Atoms in a Cavity

abstract:
  We treat control of several two-level atoms interacting with one mode of the
electromagnetic field in a cavity. This provides a useful model to study
pertinent aspects of quantum control in infinite dimensions via the emergence
of infinite-dimensional system algebras. Hence we address problems arising with
infinite-dimensional Lie algebras and those of unbounded operators. For the
models considered, these problems can be solved by splitting the set of control
Hamiltonians into two subsets: The first obeys an abelian symmetry and can be
treated in terms of infinite-dimensional Lie algebras and strongly closed
subgroups of the unitary group of the system Hilbert space. The second breaks
this symmetry, and its discussion introduces new arguments. Yet, full
controllability can be achieved in a strong sense: e.g., in a time dependent
Jaynes-Cummings model we show that, by tuning coupling constants appropriately,
every unitary of the coupled system (atoms and cavity) can be approximated with
arbitrarily small error.


title: Waiting time distribution for trains of quantized electron pulses

abstract:
  We consider a sequence of quantized Lorentzian pulses of non-interacting
electrons impinging on a quantum point contact (QPC) and study the waiting time
distribution (WTD), for any transmission and any number of pulses. As the
degree of overlap between the electronic wave functions is tuned, the WTD
reveals how the correlations between particles are modified. In the weak
overlap regime, the WTD is made of several equidistant peaks, separated by the
same period as the incoming pulses, contained in an almost exponentially
decaying envelope. In the other limit, the WTD of a single quantum channel
subjected to a constant voltage is recovered. In both cases, the WTD stresses
the difference between the fluctuations induced by the scatterer and the ones
encoded in the incoming quantum state. A clear cross-over between these two
situations is studied with numerical and analytical calculations based on
scattering theory.


title: Cooling a magnetic nanoisland by spin-polarized currents

abstract:
  We investigate cooling of a vibrational mode of a magnetic quantum dot by a
spin-polarized tunneling charge current, exploiting the interaction between the
magnetization and the vibration. The spin-polarized charge current polarizes
the magnetic nanoisland, lowering its energy. Inevitable Ohmic energy losses
due to the charge current flow will heat up the vibration. A small but finite
coupling between the vibration and the local magnetic moment then permits an
energy exchange, resulting in a lower energy, i.e., cooling, of the vibrational
mode. We determine parameter regimes for the cooling of the vibration below
$50\%$ of its initial value. Lowest final phonon temperature is observed for
weak electron-phonon-coupling but similar magnetization-phonon coupling
strength. The cooling rate, thereby, increases at first with the
magnetization-phonon coupling and then saturates.


title: Rational reductions of the 2D-Toda hierarchy and mirror symmetry

abstract:
  We introduce and study a two-parameter family of symmetry reductions of the
two-dimensional Toda lattice hierarchy, which are characterized by a rational
factorization of the Lax operator into a product of an upper diagonal and the
inverse of a lower diagonal formal difference operator. They subsume and
generalize several classical 1 + 1 integrable hierarchies, such as the bigraded
Toda hierarchy, the Ablowitz-Ladik hierarchy and E. Frenkel's q-deformed
Gelfand-Dickey hierarchy. We establish their characterization in terms of block
Toeplitz matrices for the associated factorization problem, and study their
Hamiltonian structure. At the dispersionless level, we show how the
Takasaki-Takebe classical limit gives rise to a family of non-conformal
Frobenius manifolds with flat identity. We use this to generalize the relation
of the Ablowitz-Ladik hierarchy to Gromov-Witten theory by proving an analogous
mirror theorem for rational reductions: in particular, we show that the
dual-type Frobenius manifolds we obtain are isomorphic to the equivariant
quantum cohomology of a family of toric Calabi-Yau threefolds obtained from
minimal resolutions of the local orbifold line.


title: Data Mining Cultural Aspects of Social Media Marketing

abstract:
  For marketing to function in a globalized world it must respect a diverse set
of local cultures. With marketing efforts extending to social media platforms,
the crossing of cultural boundaries can happen in an instant. In this paper we
examine how culture influences the popularity of marketing messages in social
media platforms. Text mining, automated translation and sentiment analysis
contribute largely to our research. From our analysis of 400 posts on the
localized Google+ pages of German car brands in Germany and the US, we conclude
that posting time and emotions are important predictors for reshare counts.


title:
Comparing Finesse simulations, analytical solutions and OSCAR
  simulations of Fabry-Perot alignment signals

abstract:
  This document records the results of a comparison of the interferometer
simulation Finesse against an analytic (MATLAB based) calculation of the
alignment sensing signals of a Fabry Perot cavity. This task was started during
the commissioning workshop at the LIGO Livingston site between the 28.1. and
1.02 2013 with the aim of creating a reference example for validating numerical
simulation tools. The FFT based simulation OSCAR joined the battle later.


title: B(G) for all local and global fields

abstract:
  Generalizing earlier results concerning p-adic fields, this paper develops a
theory of B(G) for all local and global fields.


title:
Reconfigurable p-n Junction Diodes and the Photovoltaic Effect in
  Exfoliated MoS2 Films

abstract:
  Realizing basic semiconductor devices such as p-n junctions are necessary for
developing thin-film and optoelectronic technologies in emerging planar
materials such as MoS2. In this work, electrostatic doping by buried gates is
used to study the electronic and optoelectronic properties of p-n junctions in
exfoliated MoS2 flakes. Creating a controllable doping gradient across the
device leads to the observation of the photovoltaic effect in monolayer and
bilayer MoS2 flakes. For thicker flakes, strong ambipolar conduction enables
realization of fully reconfigurable p-n junction diodes with rectifying
current-voltage characteristics, and diode ideality factors as low as 1.6. The
spectral response of the photovoltaic effect shows signatures of the predicted
band gap transitions. For the first excitonic transition, a shift of >4kBT is
observed between monolayer and bulk devices, indicating a thickness-dependence
of the excitonic coulomb interaction.


title: Algebraic and combinatorial rank of divisors on finite graphs

abstract:
  We study the algebraic rank of a divisor on a graph, an invariant defined
using divisors on algebraic curves dual to the graph. We prove it satisfies the
Riemann-Roch formula, a specialization property, and the Clifford inequality.
We prove that it is at most equal to the (usual) combinatorial rank, and that
equality holds in many cases, though not in general.


title:
Smart Deferral of Messages for Privacy Protection in Online Social
  Networks

abstract:
  Despite the several advantages commonly attributed to social networks such as
easiness and immediacy to communicate with acquaintances and friends,
significant privacy threats provoked by unexperienced or even irresponsible
users recklessly publishing sensitive material are also noticeable. Yet, a
different, but equally hazardous privacy risk might arise from social networks
profiling the online activity of their users based on the timestamp of the
interactions between the former and the latter. In order to thwart this last
type of commonly neglected attacks, this paper presents a novel, smart deferral
mechanism for messages in online social networks. Such solution suggests
intelligently delaying certain messages posted by end users in social networks
in a way that the observed online-activity profile generated by the attacker
does not reveal any time-based sensitive information. Conducted experiments as
well as a proposed architecture implementing this approach demonstrate the
suitability and feasibility of our mechanism.


title: Temperature Renormalization of Optical Spectra of Monolayer MoS2

abstract:
  Newly measured optical absorption and photoluminescence spectra reveal
substantial frequency shifts of both exciton and trion peaks as monolayer MoS2
is cooled from 363 K to 4 K. First-principles simulations using the
GW-Bethe-Salpeter Equation approach satisfactorily reproduce these frequency
shifts by incorporating many-electron interactions and the thermal expansion of
the in-plane lattice constant. Studying these temperature effects in monolayer
MoS2 is crucial for rectifying the results of room-temperature experiments with
the previous predictions of zero-temperature-limit simulations. Moreover, we
estimate that the thermal expansion coefficient of monolayer MoS2 is around 25%
less than that of bulk counterpart by tracking the frequency shifts of the
exciton or trion peaks in optical spectra. This may serve as a convenient way
to estimate thermal expansion coefficients of general two-dimensional
chalcogenides.


title:
Note on a Cohomological Theory of Contact-Instanton and Invariants of
  Contact Structures

abstract:
  In the localization of 5-dimensional N = 1 super-Yang-Mills,
contact-instantons arise as non-perturbative contributions. In this note, we
revisit such configurations and discuss their generalizations. We propose for
contact-instantons a cohomological theory whose BRST observables are invariants
of the background contact geometry. To make the formalism more concrete, we
study the moduli problem of contact- instanton, and we find that it is closely
related to the eqiuivariant index of a canonical Dirac-Kohn operator associated
to the geometry. An integral formula is given when the geometry is K-contact.
We also discuss the relation to 5d N = 1 super-Yang- Mills, and by studying a
contact-instanton solution canonical to the background geometry, we discuss a
possible connection between N = 1 theory and contact homology. We also uplift
the 5d theory a 6d cohomological theory which localizes to
Donaldson-Uhlenbeck-Yau instantons when placed on special geometry.


title: Supersymmetric mode converters

abstract:
  Originally developed in the context of quantum field theory, the concept of
supersymmetry (SUSY) can be used to systematically design a new class of
optical structures. In this work, we demonstrate how key features arising from
optical supersymmetry can be exploited to control the flow of light for mode
division multiplexing applications. Superpartner configurations are
experimentally realized in coupled optical networks, and the corresponding
light dynamics in such systems are directly observed. We show that SUSY can be
judiciously utilized to remove the fundamental mode of a multimode optical
structure, while establishing global phase matching conditions for the
remaining set of modes. Along these lines, supersymmetry may serve as a
promising platform for a new generation of versatile optical components with
novel properties and functionalities.


title: Universality of graphs with few triangles and anti-triangles

abstract:
  We study 3-random-like graphs, that is, sequences of graphs in which the
densities of triangles and anti-triangles converge to 1/8. Since the random
graph ${\mathcal G}_{n,1/2}$ is, in particular, 3-random-like, this can be
viewed as a weak version of quasirandomness. We first show that 3-random-like
graphs are 4-universal, that is, they contain induced copies of all 4-vertex
graphs. This settles a question of Linial and Morgenstern. We then show that
for larger subgraphs, 3-random-like sequences demonstrate a completely
different behaviour. We prove that for every graph $H$ on $n\geq R(10,10)$
vertices there exist 3-random-like graphs without an induced copy of $H$.
Moreover, we prove that for every $\ell$ there are 3-random-like graphs which
are $\ell$-universal but not $m$-universal when $m$ is sufficiently large
compared to $\ell$.


title: Statistics of Random 3-Manifolds occasionally fibering over the circle

abstract:
  We study random elements of subgroups (and cosets) of the mapping class group
of a closed hyperbolic surface, in part through the properties of their mapping
tori. In particular, we study the distribution of the homology of the mapping
torus (with rational, integer, and finite field coefficients, the hyperbolic
volume (whenever the manifold is hyperbolic), the dilatation of the monodromy,
the injectivity radius, and the bottom eigenvalue of the Laplacian on these
mapping tori. We also study mapping tori of punctured surface bundles, and
various invariants of their Dehn fillings. We also study corresponding
questions in the Dunfield-Thurston model of random Heegard splittings of fixed
genus, and give a number of new and improved results in that setting.


title:
Formulating Weak Lensing from the Boltzmann Equation and Application to
  Lens-lens Couplings

abstract:
  The Planck mission has conclusively detected lensing of the Cosmic Microwave
Background (CMB) radiation from foreground sources to an overall significance
of greater than $25\sigma$. The high precision of this measurement motivates
the development of a more complete formulation of the calculation of this
effect. While most effects on the CMB anisotropies are widely studied through
direct solutions of the Boltzmann equation, the non-linear effect of CMB
lensing is formulated through the solutions of the geodesic equation. In this
paper, we present a new formalism to the calculation of the lensing effect by
\emph{directly solving the Boltzmann equation}, as we did in the calculation of
the CMB anisotropies at recombination. In particular, we developed a
diagrammatic approach to efficiently keep track of all the interaction terms
and calculate all possible non-trivial correlations to arbitrary high orders.
Using this formalism, we explicitly articulate the approximations required to
recover the usual remapping approach used in current studies of the weak
lensing. In addition, we point out additional unexplored corrections that are
manifest in our formalism to which experiments may be sensitive. As an example,
we calculate the correction to the CMB temperature power spectrum for the
\emph{lens-lens} coupling effects which are neglected in standard calculations.
We find that the correction is $\lesssim 0.1\%$ of the CMB temperature power
spectrum for $\ell$ up to 3000 and thus is comparable to the cosmic variance.


title:
Serre Duality, Abel's Theorem, and Jacobi Inversion for Supercurves Over
  a Thick Superpoint

abstract:
  The principal aim of this paper is to extend Abel's theorem to the setting of
complex supermanifolds of dimension 1|q over a finite-dimensional local
supercommutative C-algebra. The theorem is proved by establishing a
compatibility of Serre duality for the supercurve with Poincare duality on the
reduced curve. We include an elementary algebraic proof of the requisite form
of Serre duality, closely based on the account of the reduced case given by
Serre in Algebraic Groups and Class Fields, combined with an invariance result
for the topology on the dual of the space of repartitions. Our Abel map, taking
Cartier divisors of degree zero to the dual of the space of sections of the
Berezinian sheaf, modulo periods, is defined via Penkov's characterization of
the Berezinian sheaf as the cohomology of the de Rham complex of the sheaf D of
differential operators, as a right module over itself. We discuss the Jacobi
inversion problem for the Abel map and give an example demonstrating that if n
is an integer sufficiently large that the generic divisor of degree n is
linearly equivalent to an effective divisor, this need not be the case for all
divisors of degree n.


title:
LSZ reduction formula in many-dimensional theory with space-space
  noncommutativity

abstract:
  An analogue of the Lehmann-Symanzik-Zimmermann reduction formula is obtained
for the case of noncommutative space-space theory. Some consequences of the
reduction formula and Haag's theorem are discussed.


title: Continued activity in P/2013 P5 PANSTARRS - The comet that should not be

abstract:
  P/2013 P5 PANSTARRS was discovered in Aug. 2013, displaying a cometary tail,
but with orbital elements typical for a member of the inner asteroid Main Belt.
  We monitored the object from 2013 Aug. 30 until Oct. 05 using the CFHT, NTT,
CA 1.23m, Perkins 1.8m (Lowell), and the 0.6m TRAPPIST telescopes. We measured
its nuclear radius to be r < 0.25-0.29km, and its colours g-r = 0.58+/-0.05 and
r-i = 0.23+/-0.06, typical for an S-class asteroid. We failed to detect any
rotational light curve, with an amplitude < 0.05mag and a double-peaked
rotation period < 20h. A detailed Finson-Probstein analysis of deep NTT and
CFHT images indicated that the object was active since at least late January
2013 until the time of the latest observations in 2013 September, with at least
two peaks of activity around 2013 June 14+/-10d and 2013 July 22+/-3d. The
changes of activity level and the activity peaks were extremely sharp and
short, shorter than the temporal resolution of our observations (about 1d). The
dust distribution was similar during these two events, with dust grains
covering at least the 1-1000{\mu}m range. The total mass ejected in grains <1mm
was estimated to be 3.0 10$^6$kg and 2.6 10$^7$kg around the two activity
peaks.
  Rotational disruption cannot be ruled out as the cause of the dust ejection.
We also propose that the components of a contact binary might gently rub and
produce the observed emission. Volatile sublimation might also explain what
appears as cometary activity over a period of 8 months. However, while Main
Belt comets best explained by ice sublimation are found in the outskirts of the
Main Belt, where water ice is believed to be able to survive buried in
moderately large objects for the age of the solar system deeply, the presence
of volatiles in an object smaller than 300m in radius would be very surprising
in the inner asteroid belt.


title: Extracting tag hierarchies

abstract:
  Tagging items with descriptive annotations or keywords is a very natural way
to compress and highlight information about the properties of the given entity.
Over the years several methods have been proposed for extracting a hierarchy
between the tags for systems with a "flat", egalitarian organization of the
tags, which is very common when the tags correspond to free words given by
numerous independent people. Here we present a complete framework for automated
tag hierarchy extraction based on tag occurrence statistics. Along with
proposing new algorithms, we are also introducing different quality measures
enabling the detailed comparison of competing approaches from different
aspects. Furthermore, we set up a synthetic, computer generated benchmark
providing a versatile tool for testing, with a couple of tunable parameters
capable of generating a wide range of test beds. Beside the computer generated
input we also use real data in our studies, including a biological example with
a pre-defined hierarchy between the tags. The encouraging similarity between
the pre-defined and reconstructed hierarchy, as well as the seemingly
meaningful hierarchies obtained for other real systems indicate that tag
hierarchy extraction is a very promising direction for further research with a
great potential for practical applications.


title:
Diffusion-Based Adaptive Distributed Detection: Steady-State Performance
  in the Slow Adaptation Regime

abstract:
  This work examines the close interplay between cooperation and adaptation for
distributed detection schemes over fully decentralized networks. The combined
attributes of cooperation and adaptation are necessary to enable networks of
detectors to continually learn from streaming data and to continually track
drifts in the state of nature when deciding in favor of one hypothesis or
another. The results in the paper establish a fundamental scaling law for the
steady-state probabilities of miss-detection and false-alarm in the slow
adaptation regime, when the agents interact with each other according to
distributed strategies that employ small constant step-sizes. The latter are
critical to enable continuous adaptation and learning. The work establishes
three key results. First, it is shown that the output of the collaborative
process at each agent has a steady-state distribution. Second, it is shown that
this distribution is asymptotically Gaussian in the slow adaptation regime of
small step-sizes. And third, by carrying out a detailed large deviations
analysis, closed-form expressions are derived for the decaying rates of the
false-alarm and miss-detection probabilities. Interesting insights are gained.
In particular, it is verified that as the step-size $\mu$ decreases, the error
probabilities are driven to zero exponentially fast as functions of $1/\mu$,
and that the error exponents increase linearly in the number of agents. It is
also verified that the scaling laws governing errors of detection and errors of
estimation over networks behave very differently, with the former having an
exponential decay proportional to $1/\mu$, while the latter scales linearly
with decay proportional to $\mu$. It is shown that the cooperative strategy
allows each agent to reach the same detection performance, in terms of
detection error exponents, of a centralized stochastic-gradient solution.


title:
The Impact of Social Segregation on Human Mobility in Developing and
  Urbanized Regions

abstract:
  This study leverages mobile phone data to analyze human mobility patterns in
developing countries, especially in comparison to more industrialized
countries. Developing regions, such as the Ivory Coast, are marked by a number
of factors that may influence mobility, such as less infrastructural coverage
and maturity, less economic resources and stability, and in some cases, more
cultural and language-based diversity. By comparing mobile phone data collected
from the Ivory Coast to similar data collected in Portugal, we are able to
highlight both qualitative and quantitative differences in mobility patterns -
such as differences in likelihood to travel, as well as in the time required to
travel - that are relevant to consideration on policy, infrastructure, and
economic development. Our study illustrates how cultural and linguistic
diversity in developing regions (such as Ivory Coast) can present challenges to
mobility models that perform well and were conceptualized in less culturally
diverse regions. Finally, we address these challenges by proposing novel
techniques to assess the strength of borders in a regional partitioning scheme
and to quantify the impact of border strength on mobility model accuracy.


title: Adaptive Mesh Refinement for Storm Surge

abstract:
  An approach to utilizing adaptive mesh refinement algorithms for storm surge
modeling is proposed. Currently numerical models exist that can resolve the
details of coastal regions but are often too costly to be run in an ensemble
forecasting framework without significant computing resources. The application
of adaptive mesh refinement algorithms substantially lowers the computational
cost of a storm surge model run while retaining much of the desired coastal
resolution. The approach presented is implemented in the \geoclaw framework and
compared to \adcirc for Hurricane Ike along with observed tide gauge data and
the computational cost of each model run.


title: CLT for the zeros of Classical Random Trigonometric Polynomials

abstract:
  We prove a Central Limit Theorem for the number of zeros of random
trigonometric polynomials of the form $K^{-1/2}\sum_{n=1}^{K} a_n\cos(nt)$,
being $(a_n)_n$ independent standard Gaussian random variables. In particular,
we prove the conjecture by Farahmand, Granville & Wigman that the variance is
equivalent to $V^2K$, $0<V^2<\infty$, as $K\to\infty$. % The case of stationary
trigonometric polynomials was studied by Granville & Wigman and by Aza\"\is &
Le\'on. Our approach is based on the Hermite/Wiener-Chaos decomposition for
square-integrable functionals of a Gaussian process and on Rice Formula for
zero counting.


title:
Engineering the unitary charge-conjugation operator of quantum field
  theory for particle-antiparticle using trapped ions and light fields in
  cavity QED

abstract:
  We present a method to engineer the unitary charge conjugation operator, as
given by quantum field theory, in the highly controlled context of quantum
optics, thus allowing one to simulate the creation of charged particles with
well-defined momenta simultaneously with their respective antiparticles. Our
method relies on trapped ions driven by a laser field and interacting with a
single mode of a light field in a high Q cavity.