pinecone/core-2020-05-10-deduplication huggingface dataset:
Towards a game theoretic authorisation model

Authorised users (insiders) are behind the majority of security incidents with high financial impacts. Because authorisation is the process of controlling users’ access to resources, improving authorisation techniques may mitigate the insider threat. Current approaches to authorisation suffer from the assumption that users will (can) not depart from the expected behaviour implicit in the authorisation policy. In reality however, users can and do depart from the canonical behaviour. This paper argues that the conflict of interest between insiders and authorisation mechanisms is analogous to the subset of problems formally studied in the field of game theory. It proposes a game theoretic authorisation model that can ensure users’ potential misuse of a resource is explicitly considered while making an authorisation decision. The resulting authorisation model is dynamic in the sense that its access decisions vary according to the changes in explicit factors that influence the cost of misuse for both the authorisation mechanism and the insider
AMP-activated protein kinase and metabolic control.

28 pagesInternational audienceAMP-activated protein kinase AMP-activated protein kinase (AMPK AMPK ), a phylogenetically conserved serine/threonine protein kinase, is a major regulator of cellular and whole-body energy homeostasis that coordinates metabolic pathways in order to balance nutrient supply with energy demand. It is now recognized that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profile, and blood pressure in insulin-resistant rodents. Indeed, AMPK activation mimics the beneficial effects of physical activity or those of calorie restriction calorie restriction by acting on multiple cellular targets. In addition, it is now demonstrated that AMPK is one of the probable (albeit indirect) targets of major antidiabetic drugs drugs including the biguanides (metformin metformin ) and thiazolidinedione thiazolidinedione s, as well as of insulin-sensitizing adipokines (e.g., adiponectin adiponectin ). Taken together, such findings highlight the logic underlying the concept of targeting the AMPK pathway for the treatment of metabolic syndrome and type 2 diabetes
Using the interaction rhythm as a natural reinforcement signal for social robots: a matter of belief

The original publication is available at www.springerlink.com Copyright Springer VerlagIn this paper, we present the results of a pilot study of a human robot interaction experiment where the rhythm of the interaction is used as a reinforcement signal to learn sensorimotor associations. The algorithm uses breaks and variations in the rhythm at which the human is producing actions. The concept is based on the hypothesis that a constant rhythm is an intrinsic property of a positive interaction whereas a break reflects a negative event. Subjects from various backgrounds interacted with a NAO robot where they had to teach the robot to mirror their actions by learning the correct sensorimotor associations. The results show that in order for the rhythm to be a useful reinforcement signal, the subjects have to be convinced that the robot is an agent with which they can act naturally, using their voice and facial expressions as cues to help it understand the correct behaviour to learn. When the subjects do behave naturally, the rhythm and its variations truly reflects how well the interaction is going and helps the robot learn efficiently. These results mean that non-expert users can interact naturally and fruitfully with an autonomous robot if the interaction is believed to be natural, without any technical knowledge of the cognitive capacities of the robot
A Tale of Two Current Sheets

I outline a new model of particle acceleration in the current sheet
separating the closed from the open field lines in the force-free model of
pulsar magnetospheres, based on reconnection at the light cylinder and
"auroral" acceleration occurring in the return current channel that connects
the light cylinder to the neutron star surface. I discuss recent studies of
Pulsar Wind Nebulae, which find that pair outflow rates in excess of those
predicted by existing theories of pair creation occur, and use those results to
point out that dissipation of the magnetic field in a pulsar's wind upstream of
the termination shock is restored to life as a viable model for the solution of
the "$\sigma$" problem as a consequence of the lower wind 4-velocity implied by
the larger mass loading.Comment: 17 pages, 6 figures, Invited Review, Proceedings of the "ICREA
  Workshop on The High-Energy Emission from Pulsars and their Systems", Sant
  Cugat, Spain, April 12-16, 201
Gamma-rays from millisecond pulsars in Globular Clusters

Globular clusters (GCs) with their ages of the order of several billion years
contain many final products of evolution of stars such as: neutron stars, white
dwarfs and probably also black holes. These compact objects can be at present
responsible for the acceleration of particles to relativistic energies.
Therefore, gamma-ray emission is expected from GCs as a result of radiation
processes occurring either in the inner magnetosperes of millisecond pulsars or
in the vicinity of accreting neutron stars and white dwarfs or as a result of
interaction of particles leaving the compact objects with the strong radiation
field within the GC. Recently, GeV gamma-ray emission has been detected from
several GCs by the new satellite observatory Fermi. Also Cherenkov telescopes
reported interesting upper limits at the TeV energies which start to constrain
the content of GCs. We review the results of these gamma-ray observations in
the context of recent scenarios for their origin.Comment: 20 pages, 9 figures, will be published in Astrophysics and Space
  Science Series (Springer), eds. N. Rea and D.F. Torre
Radio pulsar populations

The goal of this article is to summarize the current state of play in the
field of radio pulsar statistics. Simply put, from the observed sample of
objects from a variety of surveys with different telescopes, we wish to infer
the properties of the underlying sample and to connect these with other
astrophysical populations (for example supernova remnants or X-ray binaries).
The main problem we need to tackle is the fact that, like many areas of
science, the observed populations are often heavily biased by a variety of
selection effects. After a review of the main effects relevant to radio
pulsars, I discuss techniques to correct for them and summarize some of the
most recent results. Perhaps the main point I would like to make in this
article is that current models to describe the population are far from complete
and often suffer from strong covariances between input parameters. That said,
there are a number of very interesting conclusions that can be made concerning
the evolution of neutron stars based on current data. While the focus of this
review will be on the population of isolated Galactic pulsars, I will also
briefly comment on millisecond and binary pulsars as well as the pulsar content
of globular clusters and the Magellanic Clouds.Comment: 16 pages, 6 figures, to appear in Proceedings of ICREA Workshop on
  The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain,
  2010 April 12-16 (Springer
Pulsars as gravitational wave detectors

Pulsar timing array projects are carrying out high precision observations of
millisecond pulsars with the aim of detecting ultra-low frequency (~ 10^{-9} to
10^{-8} Hz) gravitational waves. We show how unambiguous detections of such
waves can be obtained by identifying a signal that is correlated between the
timing of different pulsars. Here we describe the ongoing observing projects,
the expected sources of gravitational waves, the processing of the data and the
implications of current results.Comment: Review of "pulsars as gravitational wave detectors" for the ICREA
  Workshop on The High-Energy Emission from Pulsars and their System
Activated Magnetospheres of Magnetars

Like the solar corona, the external magnetic field of magnetars is twisted by
surface motions of the star. The twist energy is dissipated over time. We
discuss the theory of this activity and its observational status. (1) Theory
predicts that the magnetosphere tends to untwist in a peculiar way: a bundle of
electric currents (the "j-bundle") is formed with a sharp boundary, which
shrinks toward the magnetic dipole axis. Recent observations of shrinking hot
spots on magnetars are consistent with this behavior. (2) Continual discharge
fills the j-bundle with electron-positron plasma, maintaining a nonthermal
corona around the neutron star. The corona outside a few stellar radii strongly
interacts with the stellar radiation and forms a "radiatively locked" outflow
with a high e+- multiplicity. The locked plasma annihilates near the apexes of
the closed magnetic field lines. (3) New radiative-transfer simulations suggest
a simple mechanism that shapes the observed X-ray spectrum from 0.1 keV to 1
MeV: part of the thermal X-rays emitted by the neutron star are reflected from
the outer corona and then upscattered by the inner relativistic outflow in the
j-bundle, producing a beam of hard X-rays.Comment: 23 pages, 7 figures; review chapter in the proceedings of ICREA
  Workshop on the High-Energy Emission from Pulsars and Their Systems, Sant
  Cugat, Spain, April 201
The magnetar emission in the IR band: the role of magnetospheric
  currents

There is a general consensus about the fact that the magnetar scenario
provides a convincing explanation for several of the observed properties of the
Anomalous X-ray Pulsars and the Soft Gamma Repeaters. However, the origin of
the emission observed at low energies is still an open issue. We present a
quantitative model for the emission in the optical/infrared band produced by
curvature radiation from magnetospheric charges, and compare results with
current magnetars observations.Comment: 6 Pages, 2 Figures. Astrophysics and Space Science, in press.
  Proceedings of the ICREA Workshop on The High-Energy Emission from Pulsars
  and their Systems, Sant Cugat, April 12-16 201
X-ray emission from isolated neutron stars

X-ray emission is a common feature of all varieties of isolated neutron stars
(INS) and, thanks to the advent of sensitive instruments with good
spectroscopic, timing, and imaging capabilities, X-ray observations have become
an essential tool in the study of these objects. Non-thermal X-rays from young,
energetic radio pulsars have been detected since the beginning of X-ray
astronomy, and the long-sought thermal emission from cooling neutron star's
surfaces can now be studied in detail in many pulsars spanning different ages,
magnetic fields, and, possibly, surface compositions. In addition, other
different manifestations of INS have been discovered with X-ray observations.
These new classes of high-energy sources, comprising the nearby X-ray Dim
Isolated Neutron Stars, the Central Compact Objects in supernova remnants, the
Anomalous X-ray Pulsars, and the Soft Gamma-ray Repeaters, now add up to
several tens of confirmed members, plus many candidates, and allow us to study
a variety of phenomena unobservable in "standard'' radio pulsars.Comment: Chapter to be published in the book of proceedings of the 1st Sant
  Cugat Forum on Astrophysics, "ICREA Workshop on the high-energy emission from
  pulsars and their systems", held in April, 201
Pulsar Results with the Fermi Large Area Telescope

The launch of the Fermi Gamma-ray Space Telescope has heralded a new era in
the study of gamma-ray pulsars. The population of confirmed gamma-ray pulsars
has gone from 6-7 to more than 60, and the superb sensitivity of the Large Area
Telescope (LAT) on Fermi has allowed the detailed study of their spectra and
light curves. Twenty-four of these pulsars were discovered in blind searches of
the gamma-ray data, and twenty-one of these are, at present, radio quiet,
despite deep radio follow-up observations. In addition, millisecond pulsars
have been confirmed as a class of gamma-ray emitters, both individually and
collectively in globular clusters. Recently, radio searches in the direction of
LAT sources with no likely counterparts have been highly productive, leading to
the discovery of a large number of new millisecond pulsars. Taken together,
these discoveries promise a great improvement in the understanding of the
gamma-ray emission properties and Galactic population of pulsars. We summarize
some of the results stemming from these newly-detected pulsars and their timing
and multi-wavelength follow-up observations.Comment: 21 pages, 9 figures, to appear in Proceedings of ICREA Workshop on
  The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain,
  2010 April 12-16 (Springer
Multiwavelength Observations of Pulsar Wind Nebulae

The extended nebulae formed as pulsar winds expand into their surroundings
provide information about the composition of the winds, the injection history
from the host pulsar, and the material into which the nebulae are expanding.
Observations from across the electromagnetic spectrum provide constraints on
the evolution of the nebulae, the density and composition of the surrounding
ejecta, the geometry of the central engines, and the long-term fate of the
energetic particles produced in these systems. Such observations reveal the
presence of jets and wind termination shocks, time-varying compact emission
structures, shocked supernova ejecta, and newly formed dust. Here I provide a
broad overview of the structure of pulsar wind nebulae, with specific examples
from observations extending from the radio band to very-high-energy gamma-rays
that demonstrate our ability to constrain the history and ultimate fate of the
energy released in the spin-down of young pulsars.Comment: 20 pages, 11 figures. Invited review to appear in Proc. of the
  inaugural ICREA Workshop on "The High-Energy Emission from Pulsars and their
  Systems" (2010), eds. N. Rea and D. Torres, (Springer Astrophysics and Space
  Science series
Lepton Acceleration in Pulsar Wind Nebulae

Pulsar Wind Nebulae (PWNe) act as calorimeters for the relativistic pair
winds emanating from within the pulsar light cylinder. Their radiative
dissipation in various wavebands is significantly different from that of their
pulsar central engines: the broadband spectra of PWNe possess characteristics
distinct from those of pulsars, thereby demanding a site of lepton acceleration
remote from the pulsar magnetosphere. A principal candidate for this locale is
the pulsar wind termination shock, a putatively highly-oblique,
ultra-relativistic MHD discontinuity. This paper summarizes key characteristics
of relativistic shock acceleration germane to PWNe, using predominantly Monte
Carlo simulation techniques that compare well with semi-analytic solutions of
the diffusion-convection equation. The array of potential spectral indices for
the pair distribution function is explored, defining how these depend
critically on the parameters of the turbulent plasma in the shock environs.
Injection efficiencies into the acceleration process are also addressed.
Informative constraints on the frequency of particle scattering and the level
of field turbulence are identified using the multiwavelength observations of
selected PWNe. These suggest that the termination shock can be comfortably
invoked as a principal injector of energetic leptons into PWNe without
resorting to unrealistic properties for the shock layer turbulence or MHD
structure.Comment: 19 pages, 5 figures, invited review to appear in Proc. of the
  inaugural ICREA Workshop on "The High-Energy Emission from Pulsars and their
  Systems" (2010), eds. N. Rea and D. Torres, (Springer Astrophysics and Space
  Science series
MHD models of Pulsar Wind Nebulae

Pulsar Wind Nebulae (PWNe) are bubbles or relativistic plasma that form when
the pulsar wind is confined by the SNR or the ISM. Recent observations have
shown a richness of emission features that has driven a renewed interest in the
theoretical modeling of these objects. In recent years a MHD paradigm has been
developed, capable of reproducing almost all of the observed properties of
PWNe, shedding new light on many old issues. Given that PWNe are perhaps the
nearest systems where processes related to relativistic dynamics can be
investigated with high accuracy, a reliable model of their behavior is
paramount for a correct understanding of high energy astrophysics in general. I
will review the present status of MHD models: what are the key ingredients,
their successes, and open questions that still need further investigation.Comment: 18 pages, 5 figures, Invited Review, Proceedings of the "ICREA
  Workshop on The High-Energy Emission from Pulsars and their Systems", Sant
  Cugat, Spain, April 12-16, 201
Multiple-object tracking in cluttered and crowded public spaces

This paper addresses the problem of tracking moving objects of variable
appearance in challenging scenes rich with features and texture. Reliable
tracking is of pivotal importance in surveillance applications. It is made
particularly difficult by the nature of objects encountered in such scenes:
these too change in appearance and scale, and are often articulated (e.g.
humans). We propose a method which uses fast motion detection and segmentation
as a constraint for both building appearance models and their robust
propagation (matching) in time. The appearance model is based on sets of local
appearances automatically clustered using spatio-kinetic similarity, and is
updated with each new appearance seen. This integration of all seen appearances
of a tracked object makes it extremely resilient to errors caused by occlusion
and the lack of permanence of due to low data quality, appearance change or
background clutter. These theoretical strengths of our algorithm are
empirically demonstrated on two hour long video footage of a busy city
marketplace
Acquisition scenario analysis for face recognition at a distance

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-17289-2_44Proceedings of 6th International Symposium, ISVC 2010, Las Vegas, NV, (USA)An experimental analysis of three acquisition scenarios for face recognition at a distance is reported, namely: close, medium, and far distance between camera and query face, the three of them considering templates enrolled in controlled conditions. These three representative scenarios are studied using data from the NIST Multiple Biometric Grand Challenge, as the first step in order to understand the main variability factors that affect face recognition at a distance based on realistic yet workable and widely available data. The scenario analysis is conducted quantitatively in two ways. First, we analyze the information content in segmented faces in the different scenarios. Second, we analyze the performance across scenarios of three matchers, one commercial, and two other standard approaches using popular features (PCA and DCT) and matchers (SVM and GMM). The results show to what extent the acquisition setup impacts on the verification performance of face recognition at a distance.This work has been partially supported by projects Bio-Challenge (TEC2009-11186), Contexts (S2009/TIC-1485), TeraSense (CSD2008-00068) and "Cátedra UAM-Telefónica"
Analysis of time domain information for footstep recognition

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-17289-2_47Proceedings of 6th International Symposium, ISVC 2010, Las Vegas, NV, (USA)This paper reports an experimental analysis of footsteps as a biometric. The focus here is on information extracted from the time domain of signals collected from an array of piezoelectric sensors. Results are related to the largest footstep database collected to date, with almost 20,000 valid footstep signals and more than 120 persons, which is well beyond previous related databases. Three feature approaches have been extracted, the popular ground reaction force (GRF), the spatial average and the upper and lower contours of the pressure signals. Experimental work is based on a verification mode with a holistic approach based on PCA and SVM, achieving results in the range of 5 to 15% EER depending on the experimental conditions of quantity of data used in the reference models.R.V.-R., J.F. and J.O.-G. are supported by projects Contexts (S2009/TIC-1485), Bio-Challenge (TEC2009-11186), TeraSense (CSD2008-00068) and "Cátedra UAM-Telefónica"
Intensification Strategies for Extremal Optimisation

It is only relatively recently that extremal optimisation (EO) has been applied to combinatorial optimisation problems. As such, there have been only a few attempts to extend the paradigm to include standard search mechanisms that are routinely used by other techniques such as genetic algorithms, tabu search and ant colony optimisation. The key way to begin this process is to augment EO with attributes that it naturally lacks. While EO does not get confounded by local optima and is able to move through search space unencumbered, one of the major issues is to provide it with better search intensification strategies. In this paper, two strategies that compliment EO's mechanics are introduced and are used to augment an existing solver framework. Results, for single and population versions of the algorithm, demonstrate that intensification aids the performance of EO.Full Tex
Multi-objective evolutionary algorithms for feature selection : application in bankruptcy prediction

A Multi-Objective Evolutionary Algorithm (MOEA) was
adapted in order to deal with problems of feature selection in datamining.
The aim is to maximize the accuracy of the classifier and/or to
minimize the errors produced while minimizing the number of features
necessary. A Support Vector Machines (SVM) classifier was adopted.
Simultaneously, the parameters required by the classifier were also optimized.
The validity of the methodology proposed was tested in the
problem of bankruptcy prediction using a database containing financial
statements of 1200 medium sized private French companies. The results
produced shown that MOEA is an efficient feature selection approach
and the best results were obtained when the accuracy, the errors and the
classifiers parameters are optimized.The financial support of the Portuguese science foundation (FCT) under grant PTDC/GES/70168/2006 is acknowledged
Multi-objective optimisation of web business processes

This paper proposes an approach for the optimisation of web business processes
using multi-objective evolutionary computing. Business process optimisation is
considered as the problem of constructing feasible business process designs with
optimum attribute values such as duration and cost. This optimisation framework
involves the application of a series of Evolutionary Multi-objective
Optimisation Algorithms (EMOAs) in an attempt to generate a series of diverse
optimised business process designs for given requirements. The optimisation
framework is tested to validate the framework's capability in capturing,
composing and optimising business process designs constituted of web services.
The results from the web business process optimisation scenario, featured in
this paper, demonstrate that the framework can identify business process designs
with optimised attribute values