Structural Changes in Data Communication in Wireless Sensor Networks

Wireless sensor networks are an important technology for making distributed autonomous measures in hostile or inaccessible environments. Among the challenges they pose, the way data travel among them is a relevant issue since their structure is quite dynamic. The operational topology of such devices can often be described by complex networks. In this work, we assess the variation of measures commonly employed in the complex networks literature applied to wireless sensor networks. Four data communication strategies were considered: geometric, random, small-world, and scale-free models, along with the shortest path length measure. The sensitivity of this measure was analyzed with respect to the following perturbations: insertion and removal of nodes in the geometric strategy; and insertion, removal and rewiring of links in the other models. The assessment was performed using the normalized Kullback-Leibler divergence and Hellinger distance quantifiers, both deriving from the Information Theory framework. The results reveal that the shortest path length is sensitive to perturbations.Comment: 12 pages, 4 figures, Central European Journal of Physic

A RUBÉN DRI “La Universidad es una especie de iglesia”

 Rubén Dri visitó Viedma para dictar un curso denominado “Sujeto y Poder”. Su trayectoria de vida es muy vasta, al igual que sus producciones. Dri es filósofo y teólogo y perteneció al movimiento de Sacerdotes para el Tercer Mundo. Fue profesor de filosofía en la Universidad Nacional del Nordeste en Resistencia, Chaco. Perseguido por la dictadura militar genocida (1976-1983), se exilió en México donde ejerció la docencia y la investigación en la Universidad Nacional de México, en la Universidad Autónoma Metropolitana, en las áreas de epistemología y filosofía política, y en el Instituto Teológico de Estudios Superiores de la misma ciudad. Actualmente, como profesor consulto, es profesor-investigador en la Facultad de Ciencias Sociales de la Universidad de Buenos Aires, aunque prefiere presentarse como “asambleísta” de una asamblea vecinal en la Ciudad de Buenos Aires

Daytime turbulent exchange between the Amazon forest and the atmosphere

Detailed observations of turbulence just above and below the crown of the Amazon rain forest during the wet season are presented. The forest canopy is shown to remove high frequency turbulent fluctuations while passing lower frequencies. Filter characteristics of turbulent transfer into the Amazon rain forest canopy are quantified. Simple empirical relations that relate observed turbulent heat fluxes to horizontal wind variance are presented. Changes in the amount of turbulent coupling between the forest and the boundary layer associated with deep convective clouds are presented both as statistical averages and as a series of case studies. These convective processes during the rainy season are shown to alter the diurnal course of turbulent fluxes. In wake of giant coastal systems, no significant heat or moisture fluxes occur for up to a day after the event. Radar data is used to demonstrate that even small raining clouds are capable of evacuating the canopy of substances normally trapped by persistent static stability near the forest floor. Recovery from these events can take more than an hour, even during mid-day. In spite of the ubiquitous presence of clouds and frequent rain during this season, the average horizontal wind speed spectrum is well described by dry CBL similarity hypotheses originally found to apply in flat terrain

Guillain-Barré syndrome: advances and future perspectives

The first case of Guillain-Barré syndrome was described in 1916. Since then, knowledge about the pathophysiology and immunogenesis of this acquired inflammatory polyradiculoneuropathy has been growing steadily, especially after the advent of nerve conduction studies and the discovery of pathogenic autoantibodies. In the present study, we conducted a review of the main information available in the literature to date about the syndrome, including its diagnosis and management

Water and energy fluxes from a woodland savanna (cerrado) in southeast Brazil

Study region: The area of woodland savanna (cerrado) is located in southeast Brazil (21°36′ to 44′ S, 47°34′ to 41′ W). Study focus: The cerrado sensu-stricto savanna evapotranspiration was observed using the eddy-covariance method over three years. New hydrological insights for the region: The first year total rainfall (R = 1664 mm) was 11% above the long-term rainfall (1498 mm) and the total evapotranspiration (ET = 1242 mm) and water equivalent of available energy (Av = 1835 mm) were approximately 4% and 2% greater, respectively, than in the second year when the rainfall total was 5% lower than the long-term average. In the third year despite the total rainfall (1259 mm) being 24% lower than the first year and 16% lower than the average, the totals of ET (1242 mm) and Av (1815 mm) were approximately the same. The small variation in the observed annual ET totals shows that in this cerrado vegetation the deep soil moisture content supports the ET in a dry year and the water available for recharging the soil profile and groundwater (∼R − ET) was dominated by the rainfall amount being significantly greater in the wet year (422 mm) than in the dry year (13 mm)

Profile of retail market and consumers of papaya from 'Solo' and 'Formosa' group in Federal District – DF

Este estudo analisou os principais fatores envolvidos na comercialização do mamão em 27 supermercados e 27 varejões do Distrito Federal (Brasília e cidades satélites), no período de janeiro a dezembro de 2001. Entrevistaram-se 162 consumidores. Na tabulação e análise dos questionários, obteve-se: o principal fornecedor de mamão para o varejo foi a Ceasa-DF; a presença de danos físicos foi o principal aspecto observado pelos responsáveis pela compra; os frutos são expostos em prateleiras sem refrigeração, e o responsável pelo prejuízo ocasionado pelas perdas foi o próprio estabelecimento varejista. Os estabelecimentos varejistas diferenciaram-se em alguns tópicos, tais como: responsável pela compra, existência de contrato; forma de exposição dos frutos; grau de maturação dos frutos adquiridos, e acompanhamento das perdas. Os consumidores preferem frutos nos estádios 3 a 5 (acima de 25% da superfície amarela); escolhem o estabelecimento para compra de mamão orientados pela qualidade e preço; não pagariam mais por um mamão embalado e classificado, preferindo mamão a granel pela possibilidade de escolher-se o fruto que mais lhe agrade no momento da compra, e elegeram, como principal problema, a presença de frutos com danos físicos.The main factors involved in the commercialization of papaya in 27 supermarkets and 27 retail shops of Federal District (Brasília and satellite cities) was studied from January to December of 2001. The data was colleted using questionnaire answered by the manager of the establishment and by 162 consumers. It was observed that the wholesalers of Federal District Wholesale Market (CEASA-DF) was the main supplier of papaya to the retail market; physical damage was the main aspect to be observed by those responsible for the purchase; papaya fruits for selling were displayed in unrefrigerated racks; the retail markets themselves bore the financial losses. The retail market differed in relation of: who purchase the papaya fruits; contracts with the wholesaler; how to expose the fruit; maturation of purchased fruits; and follow-up of losses. It was found that consumers preferred: fruits in the 3rd to 5th stage of maturation; to choose papaya retail market they based on quality and price; not to pay more for wrapping and classification, opting for unwrapped fruit in order to choose the preferred fruit. Consumers reported physical damage to be the primary inhibitor to purchase