QoS support in satellite and wireless networks : study under the network simulator (NS-2)

Aquest projecte es basa en l'estudi de l'oferiment de qualitat de servei en xarxes wireless i satel·litals. Per això l'estudi de les tècniques de cross-layer i del IEEE 802.11e ha sigut el punt clau per al desenvolupament teòric d'aquest estudi. Usant el simulador de xarxes network simulator, a la part de simulacions es plantegen tres situacions: l'estudi de la xarxa satel·lital, l'estudi del mètode d'accés HCCA i la interconnexió de la xarxa satel·lital amb la wireless. Encara que aquest últim punt, incomplet en aquest projecte, ha de ser la continuació per a futures investigacions.Este proyecto se basa en el estudio del ofrecimiento de calidad de servicio en redes wireless y satelitales. Por eso el estudio de las técnicas de cross-layer y del IEEE 802.11eha sido el punto clave para el desarrollo teórico de este estudio. Usando el simulador de redes network simulator, en la parte de simulaciones se plantean tres situaciones: el estudio de la red satelital, el estudio del método de acceso HCCA y la interconexión de la red satelital con la wireless. Aunque este último punto, incompleto en este proyecto, tiene que ser la continuación para futuras investigaciones.This project is based on the study of offering quality of service in satellite and wireless networks. For that reason the study of the techniques of cross-layer and the IEEE 802.11e has been the key point for the theoretical development of this study. Using the software network simulator, in the part of simulations three situations consider: the study of the satellite network, the study of the access method HCCA and the interconnection of the satellite network with the wireless. Although this last point, incomplete in this work, must be the continuation for future investigations

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.Peer reviewe

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats

In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Development’s (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security

QoS support in satellite and wireless networks: study under the network simulator (NS-2)

Aquest projecte es basa en l'estudi de l'oferiment de qualitat de servei en xarxes wireless i satel·litals. Per això l'estudi de les tècniques de cross-layer i del IEEE 802.11e ha sigut el punt clau per al desenvolupament teòric d’aquest estudi. Usant el simulador de xarxes network simulator, a la part de simulacions es plantegen tres situacions: l'estudi de la xarxa satel·lital, l'estudi del mètode d'accés HCCA i la interconnexió de la xarxa satel·lital amb la wireless. Encara que aquest últim punt, incomplet en aquest projecte, ha de ser la continuació per a futures investigacions.Este proyecto se basa en el estudio del ofrecimiento de calidad de servicio en redes wireless y satelitales. Por eso el estudio de las técnicas de cross-layer y del IEEE 802.11eha sido el punto clave para el desarrollo teórico de este estudio. Usando el simulador de redes network simulator, en la parte de simulaciones se plantean tres situaciones: el estudio de la red satelital, el estudio del método de acceso HCCA y la interconexión de la red satelital con la wireless. Aunque este último punto, incompleto en este proyecto, tiene que ser la continuación para futuras investigaciones.This project is based on the study of offering quality of service in satellite and wireless networks. For that reason the study of the techniques of cross-layer and the IEEE 802.11e has been the key point for the theoretical development of this study. Using the software network simulator, in the part of simulations three situations consider: the study of the satellite network, the study of the access method HCCA and the interconnection of the satellite network with the wireless. Although this last point, incomplete in this work, must be the continuation for future investigations

Localization Algorithm with On-line Path Loss Estimation and Node Selection

RSS-based localization is considered a low-complexity algorithm with respect to other range techniques such as TOA or AOA. The accuracy of RSS methods depends on the suitability of the propagation models used for the actual propagation conditions. In indoor environments, in particular, it is very difficult to obtain a good propagation model. For that reason, we present a cooperative localization algorithm that dynamically estimates the path loss exponent by using RSS measurements. Since the energy consumption is a key point in sensor networks, we propose a node selection mechanism to limit the number of neighbours of a given node that are used for positioning purposes. Moreover, the selection mechanism is also useful to discard bad links that could negatively affect the performance accuracy. As a result, we derive a practical solution tailored to the strict requirements of sensor networks in terms of complexity, size and cost. We present results based on both computer simulations and real experiments with the Crossbow MICA2 motes showing that the proposed scheme offers a good trade-off in terms of position accuracy and energy efficiency

A Pragmatic approach of localization and tracking algorithms in wireless sensor networks

Els últims avenços en comunicacions sense fils i electrònica ha motivat l'aparició de les xarxes de sensors sense fils. Aquestes xarxes estan formades per un nou tipus de sensors de baixa potència i de baix cost que s\'on capa\c cos d'operar en rangs propers. La seva senzillesa i autonomia ha motivat el desenvolupament de moltes aplicacions en una gran varietat de camps. No obstant això, els nodes estan equipats amb uns recursos de processament de dades i capacitats de comunicació\'o limitats. Per tant, el desenvolupament de qualsevol aplicació planteja diversos problemes de disseny. Aquestes restriccions imposen un disseny d'aplicacions amb un caràcter distribuït i energèticament eficients. Els algoritmes de localització i seguiment són una d'aquestes aplicacions emergents que s'ha convertit en un camp d'interès per als investigadors. La informació d'enrutament de les xarxes de sensors est\̀a sovint suportada en la localització dels nodes. A més, el coneixement de la posició permet donar, a les dades detectades, un sentit geogràfic. En lloc d'utilitzar els mètodes existents de localització globals, com el GPS, que són més complexos i costosos, els recents avenços demostren la viabilitat de mètodes locals. En aquesta tesi, hem centrat el nostre estudi dels algoritmes de localització i seguiment, en xarxes de sensors sense fils, en solucions distribuïdes basades en mesures de potència. Una de la qüestions més importants és l'obtenció d'un mètode el més senzill possible, i les mesures de potència s'han convertit en les més simples. A més, també volem obtenir el millor compromís entre obtenir la major fiabilitat de l'algorisme i maximitzar l'eficiència energètica. En primer lloc, hem considerat el desenvolupament d'algoritmes de localització cooperatius basats en mesures de potència rebuda en xarxes interiors estàtiques. Les mesures de potencia imposen el coneixement d'un model de propagació per tal d'obtenir una estimació de la distància entre nodes. Nosaltres proposem la introducció d'un mètode que estima l'exponent de pèrdua de potència per propagació mitjançant les mesures de potència fetes, en comparació a les normalment utilitzades campanyes de mesures fetes a priori. A més a més, els mètodes cooperatius en els quals basem la nostra proposta augmenten el nombre de nodes que cooperen durant el procediment d'estimació de la posició d'un node no localitzat . Dos s\'on els problemes principals que no s'han de menystenir quan s'utilitza un major nombre de nodes. D'una banda, a major nombre de nodes cooperants, major intercanvi de missatges, i, per tant, major consum d'energia. D'altra banda, la probabilitat d'utilitzar nodes llunyans s'incrementa, i, com m\'es gran sigui la distància entre nodes, l'error de la distància estimada ser\̀a major, puix que utilitzem mesures de potència. Aquesta característica ens ha motivat a proposar tres criteris de selecció de nodes diferents per tal de reduir el nombre de nodes cooperants i així reduir el consum d'energia sempre intentant mantenir l'exactitud. Finalment, hem considerat la mobilitat dels nodes dins d'una xarxa fixa. L'interès és localitzar i seguir un node mòbil en una xarxa de sensor sense fils. En aquesta ocasió hem considerat dos escenaris diferents: una a l'aire lliure, on la velocitat és mitjana-alta, i un interior, on la velocitat és menor. En ambdós casos, també utilitzem un algorisme cooperatiu basat en mesures de potència. A més, el filtre de Kalman i els seus derivats s'introdueixen a la solució proposada, ja que s'han convertit en un solució d'ús comú als algoritmes de seguiment. En ambdós casos, la mobilitat del node produeix una alta variabilitat de les mesures de potència. Aquests errors poden causar una precisi\'o inferior. En aquest sentit, es proposa un mètode de correcció de les potències rebudes basat en un enfinestrat, per tal de disminuir aquests efectes negatius.The last advances in wireless communications and electronics have motivated the appearance of Wireless Sensor Networks. These networks are formed by a new kind of low-power and low-cost sensors able to operate across short ranges. Their simplicity and autonomy have motivated the development of many final applications in a large variety of fields. Nevertheless, sensor nodes are equipped with limited data processing and communication capabilities. Hence, several design challenges appear when an application has to be developed. These restrictions justify the design of highly distributed and energy-efficient applications. Localization and tracking algorithms are one of those emerging applications that have become an interesting field to the researchers. The information routing is often supported by their localization. Besides, the location knowledge gives to the data sensed a geographic sense. Instead of using the existing global localization methods, such as GPS, that are more complex and costly, recent advances have demonstrated the viability of local methods. In this PhD dissertation, we have focused our study of the localization and tracking algorithms for WSN on the RSS-based distributed approaches. One of the major issues is to obtain the simplest possible method, and RSS range measurements have become the simplest existing measurements. Besides, we have also presented methods that are able to optimize the trade-of between accuracy versus energy-efficiency. First, RSS-based cooperative localization algorithms in static indoor networks are considered. The use of RSS measurements requires the knowledge of a propagation model in order to obtain inter-node distance estimates. We introduce an on-line path loss estimation method that obtains the model by means of RSS measurements. Hence, we avoid the need of an a priori estimation of the propagation model. Moreover, the cooperative approaches used increase the number of nodes that cooperate with a non-located node in the location estimation procedure. Two major issues have to be taken into account when a large number of nodes are used. On the one hand, the larger the number of cooperating nodes, the larger the number of messages exchanged, and, hence, the higher the energy consumption. On the other hand, the probability of using further nodes is increased, hence, the higher the distance, the higher the error distance estimates, when RSS measurements are used. These features have motivated us to propose three different node selection criteria in order to reduce the energy consumption maintaining the accuracy. Finally, we have considered the mobility of the non-located nodes inside a fixed network. The interest is to locate and track a node moving across a WSN. We have considered two different scenarios: an outdoor one, in which the velocity is medium-high, and, an indoor one, where the velocity is lower. In both cases, we have still used an RSS-based cooperative algorithm. Besides, we introduce the Kalman Filter and its derivatives, because, they have become a common approach used for tracking purposes. In both scenarios, the mobility of the node causes a high variability of the RSS measurements. These errors reduce the accuracy. In that sense, we propose a window-based RSS correction method in order to counteract these negative effects

Método y sistema de localización y seguimiento de un dispositivo móvil en una red de nodos inalámbrica

Método y sistema de localización y seguimiento de un dispositivo móvil en una red de nodos inalámbrica El método comprende: - recibir, el dispositivo móvil (D), una serie de señales inalámbricas desde unos nodos estacionarios (n1-n8); - extraer y analizar información de potencia de las señales inalámbricas; - generar información de potencia estimada asociada a un nodo del cual el dispositivo móvil (D) no ha recibido una señal inalámbrica, en un periodo determinado, o la ha recibido pero su potencia es muy débil, aplicando un factor de corrección a información de potencia previa obtenida para dicho nodo en un periodo anterior a dicho periodo determinado; y - determinar la posición del dispositivo móvil (D) utilizando la información de potencia extraída, utilizando también dicha información de potencia estimada. El sistema está adaptado para implementar el método de la invención