Software timing analysis for complex hardware with survivability and risk analysis

The increasing automation of safety-critical real-time systems, such as those in cars and planes, leads, to more complex and performance-demanding on-board software and the subsequent adoption of multicores and accelerators. This causes software's execution time dispersion to increase due to variable-latency resources such as caches, NoCs, advanced memory controllers and the like. Statistical analysis has been proposed to model the Worst-Case Execution Time (WCET) of software running such complex systems by providing reliable probabilistic WCET (pWCET) estimates. However, statistical models used so far, which are based on risk analysis, are overly pessimistic by construction. In this paper we prove that statistical survivability and risk analyses are equivalent in terms of tail analysis and, building upon survivability analysis theory, we show that Weibull tail models can be used to estimate pWCET distributions reliably and tightly. In particular, our methodology proves the correctness-by-construction of the approach, and our evaluation provides evidence about the tightness of the pWCET estimates obtained, which allow decreasing them reliably by 40% for a railway case study w.r.t. state-of-the-art exponential tails.This work is a collaboration between Argonne National Laboratory and the Barcelona Supercomputing Center within the Joint Laboratory for Extreme-Scale Computing. This research is supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, under contract number DE-AC02- 06CH11357, program manager Laura Biven, and by the Spanish Government (SEV2015-0493), by the Spanish Ministry of Science and Innovation (contract TIN2015-65316-P), by Generalitat de Catalunya (contract 2014-SGR-1051).Peer ReviewedPostprint (author's final draft

Topological Vulnerability of the European Power Grid Under Errors and Attacks

Electronic version of an article published as "International journal of bifurcation and chaos", vol. 17, no. 7, July 2007, p. 2465-2475. DOI No: 10.1142/S0218127407018531. © Copyright World Scientific Publishing Company We present an analysis of the topological structure and static tolerance to errors and attacks of the September 2003 actualization of the Union for the Coordination of Transport of Electricity (UCTE) power grid, involving thirty-three different networks. Though every power grid studied has exponential degree distribution and most of them lack typical small-world topology, they display patterns of reaction to node loss similar to those observed in scale-free networks. We have found that the node removal behaviour can be logarithmically related to the power grid size. This logarithmic behaviour would suggest that, though size favours fragility, growth can reduce it. We conclude that, with the ever-growing demand for power and reliability, actual planning strategies to increase transmission systems would have to take into account this relative increase in vulnerability with size, in order facilitate and improve the power grid design and functioningPeer ReviewedPostprint (author’s final draft

Componentes generacionales y socioeconómicos de la discapacidad entre los mayores españoles

Este artículo analiza dos posibles condicionantes de la discapacidad entre los mayores españoles (edades 65-89) residentes en hogares: su adscripción generacional y su estatus socioeconómico. Se utilizan microdatos de la Encuesta Nacional de Salud de España con los que se construye un indicador de discapacidad en escala continua a partir de la autonomía declarada para la realización de actividades cotidianas. Se aplican modelos de regresión lineal para hombres y mujeres con las siguientes variables de control: edad, cohorte de nacimiento, nivel educativo y estatura autodeclarada. Los resultados indican estabilidad en los niveles de discapacidad entre grupos sucesivos de generaciones y la existencia de un gradiente socioeconómico de discapacidad, especialmente entre las mujeres y en las edades centrales de la vejez (70 a 79 años).This paper analyzes two possible determinants of disability, birth cohort and socioeconomic status, among Spanish elderly aged 65-89 living independently. We use microdata from the Spanish Health Interview Survey, particularly the self-reported ability to perform daily activities, to construct a continuous measure of disability. Multivariate linear regression models are applied separately for men and women controlling for the following variables: age, birth cohort, educational attainment and self-reported height. Results indicate stability in disability levels across successive generations as well as the existence of a socioeconomic dimension of disability especially among women and within ages 70-79

Desigualdad social y niveles de discapacidad entre los mayores españoles

Se analizan factores socioeconómicos relacionados con desigualdad social en el nivel de discapacidad de la población española de 65 a 89 años nacida entre 1910 y 1944. Para ello se utilizan microdatos de cuatro ediciones de la Encuesta Nacional de Salud de España (ENSE): 1997, 2001, 2006 y 2011/12. Se presenta un indicador de discapacidad en escala continua basado en actividades de la vida diaria que se analiza en función de la edad, la cohorte de nacimiento, el nivel educativo (estatus socioeconómico), la estatura (estado nutricional neto) y la incidencia de condiciones crónicas cardiovasculares. Los resultados revelan diferencias de género y un gradiente socioeconómico de la discapacidad durante el proceso de envejecimiento. La brecha de género a favor de los hombres es mayor en los niveles educativos más bajos y desaparece entre los estratos socioeducativos más altos. Las diferencias socioeconómicas son mayores entre las mujeres antes de los 80 años y entre los hombres en edades comprendidas entre los 85 y los 89 años. La asociación positiva entre las condiciones crónicas cardiovasculares y la discapacidad se da tanto en hombres como en mujeres y deja de ser significativa entre los más mayores.This paper examines socioeconomic determinants of disability for the Spanish population aged 65 to 89 years, born between 1910 and 1944. To do this, we use microdata from four waves of the National Health Survey of Spain (ENSE): 1997, 2001, 2006 and 2011/12. A continuous indicator of disability based on activities of daily life is constructed which is analyzed by age, birth cohort, educational attainment (socioeconomic status), height (net nutritional status), and incidence of cardiovascular chronic conditions. Results reveal gender differences and a socioeconomic gradient of disability throughout the aging process. The gender gap in favor of men is greater with lower socioeconomic status and disappears within high socioeconomic status. Socioeconomic differences, approximated by level of education, are greater among women under 80 and among men aged 85 to 89 years. A positive association between cardiovascular chronic conditions and disability exists for both men and women and becomes insignificant among the more elderly

Sistema de gestió domòtica per a optimitzar el consum enegètic d'un habitatge

El present projecte mostra una complerta definició de la domòtica, juntament amb el disseny, construcció i simulació d’un prototip de proves basat en una casa domotitzada. Per una banda, la casa domòtica s’ha dissenyat seguint uns paràmetres d’estalvi d’energia per fer-la el més eficient possible. Més enllà s'han instal·lat plaques fotovoltaiques i un sistema geotèrmic per fer la casa totalment autosuficient i renovable, disminuint així l'impacte mediambiental. Pel que fa al prototip de proves (centralitzat des d’un microprocessador), representa a petita escala el funcionament dels components electrònics que hi hauria en la casa. El prototip comercial, seria la placa base que aniria a la instal·lació domòtica de l’habitatge. A més a més, s’han realitzat càlculs dels consums en ambdós casos i l’estalvi energètic i econòmic que suposaria l’aplicació d’aquesta tecnologia i energies renovables en un habitatge. Per acabar, en aquest treball, s’han intentat cobrir tots els aspectes possibles per fer de la casa, la millor per a viure-hi: consumint sols d’energia renovable (plaques fotovoltaiques) i reduint el consum a partir de l’energia geotèrmica (calefacció i refrigeració). Per part de la domòtica, s’aconsegueix una reducció en consum gràcies a l’automatització de la casa a partir de sensors i actuadors, millorant així tant la comoditat com la seguretat

Three Millennia of Climatic, Ecological, and Cultural Change on Easter Island: An Integrative Overview

Eastern Island (Rapa Nui) is famous for the legacy of an extinct civilization symbolized by the megalithic statues called moai. Several enigmas regarding the colonization of the island its deforestation and a presumed cultural collapse of the ancient civilization still remain elusive. According to the prevailing view, the first settlers arrived between AD 800 and AD 1200 from east Polynesia and overexploited the island's natural resources causing an ecological catastrophe leading to a cultural collapse (Flenley and Bahn, 2003 ). The main evidence for this theory was the abrupt replacement of palm pollen by grass pollen in the sediments of the island's lakes and mires (Raraku, Kao, and Aroi), which was interpreted in terms of a thorough deforestation between approximately AD 1200 and AD 1400/1600 (Flenley and King, 1984; Flenley et al., 1991; Mann et al., 2008). This ecocidal view is widely accepted not only by the scientific community but also by society, thanks to its popularization by the mass media

Late Holocene vegetation dynamics and deforestation in Rano Aroi: implications for Easter Island's ecological and cultural history

Easter Island (Rapa Nui) has been considered an example of how societies can cause their own destruction through the overexploitation of natural resources. The flagship of this ecocidal paradigm is the supposed abrupt, island-wide deforestation that occurred about one millennium ago, a few centuries after the arrival of Polynesian settlers to the island. Other hypotheses attribute the forest demise to different causes such as fruit consumption by rats or aridity but the occurrence of an abrupt, island-wide deforestation during the last millennium has become paradigmatic in Rapa Nui. We argue that such a view can be questioned, as it is based on the palynological study of incomplete records, owing to the existence of major sedimentary gaps. Here, we present a multiproxy (pollen, charcoal and geochemistry) study of the Aroi core, the first gap-free sedimentary sequence of the last millennia obtained to date in the island. Our results show changing vegetation patterns under the action of either climatic or anthropogenic drivers, or both, depending on the time interval considered. Palm forests were present in Aroi until the 16th century, when deforestation started, coinciding with fire exacerbation elikely of human origine and a dry climate. This is the latest deforestation event recorded so far in the island and took place roughly a century before European contact. In comparison to other Easter Island records, this record shows that deforestation was neither simultaneous nor proceeded at the same pace over the whole island. These findings suggest that Easter Island's deforestation was a heterogeneous process in space and time, and highlights the relevance of local catchment traits in the island's environmental and land management history

Climate changes and cultural shifts on Easter Island during the last three millennia

Easter Island's cultural shifts have been explained mostly by anthropogenic forcing and climate changes have been dismissed as relevant drivers of societal change. Recent findings demand a more complex scenario in which climatic, ecological and cultural factors interact

Using Markov’s inequality with power-of-k function for probabilistic WCET estimation

Deriving WCET estimates for software programs with probabilistic means (a.k.a. pWCET estimation) has received significant attention during last years as a way to deal with the increased complexity of the processors used in real-time systems. Many works build on Extreme Value Theory (EVT) that is fed with a sample of the collected data (execution times). In its application, EVT carries two sources of uncertainty: the first one that is intrinsic to the EVT model and relates to determining the subset of the sample that belongs to the (upper) tail, and hence, is actually used by EVT for prediction; and the second one that is induced by the sampling process and hence is inherent to all sample-based methods. In this work, we show that Markov’s inequality can be used to obtain provable trustworthy probabilistic bounds to the tail of a distribution without incurring any model-intrinsic uncertainty. Yet, it produces pessimistic estimates that we shave substantially by proposing the use of a power-of-k function instead of the default identity function used by Markov’s inequality. Lastly, we propose a method to deal with sampling uncertainty for Markov’s inequality that consistently improves EVT estimates on synthetic and real data obtained from a railway application.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under grant PID2019-110854RB-I00 / AEI / 10.13039/501100011033 and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 772773).Peer ReviewedPostprint (published version

Chicken liver is a potential reservoir of bacteriophages and phage-derived particles containing antibiotic resistance genes

Poultry meat production is one of the most important agri-food industries in the world. The selective pressure exerted by widespread prophylactic or therapeutic use of antibiotics in intensive chicken farming favours the development of drug resistance in bacterial populations. Chicken liver, closely connected with the intestinal tract, has been directly involved in food-borne infections and found to be contaminated with pathogenic bacteria, including Campylobacter and Salmonella. In this study, 74 chicken livers, divided into sterile and non-sterile groups, were analysed, not only for microbial indicators but also for the presence of phages and phage particles containing antibiotic resistance genes (ARGs). Both bacteria and phages were detected in liver tissues, including those dissected under sterile conditions. The phages were able to infect Escherichia coli and showed a Siphovirus morphology. The chicken livers contained from 10 3 to 10 6 phage particles per g, which carried a range of ARGs (bla , bla , sul1, qnrA, armA and tetW) detected by qPCR. The presence of phages in chicken liver, mostly infecting E. coli, was confirmed by metagenomic analysis, although this technique was not sufficiently sensitive to identify ARGs. In addition, ARG-carrying phages were detected in chicken faeces by qPCR in a previous study of the group. Comparison of the viromes of faeces and liver showed a strong coincidence of species, which suggests that the phages found in the liver originate in faeces. These findings suggests that phages, like bacteria, can translocate from the gut to the liver, which may therefore constitute a potential reservoir of antibiotic resistance genes. Phage particles carrying antibiotic resistant genes have been found in chicken livers. Metagenomic analysis of chicken liver viromes (PL) and chicken faeces viromes (HP) suggests that these phage particles could translocate from chicken gut to the liver