Modularity of food-sharing networks minimises the risk for individual and group starvation in hunter-gatherer societies.

It has been argued that hunter-gatherers' food-sharing may have provided the basis for a whole range of social interactions, and hence its study may provide important insight into the evolutionary origin of human sociality. Motivated by this observation, we propose a simple network optimization model inspired by a food-sharing dynamic that can recover some empirical patterns found in social networks. We focus on two of the main food-sharing drivers discussed by the anthropological literature: the reduction of individual starvation risk and the care for the group welfare or egalitarian access to food shares, and show that networks optimizing both criteria may exhibit a community structure of highly-cohesive groups around special agents that we call hunters, those who inject food into the system.

Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes.

The synthesis of geopolymer matrixes from coal (co-)combustion fly ashes as the sole source of silica and alumina has been studied in order to assess both their capacity to immobilise the potentially toxic elements contained in these coal (co-)combustion by-products and their suitability to be used as cement replacements. The geopolymerisation process has been performed using (5, 8 and 12 M) NaOH solutions as activation media and different curing time (6-48 h) and temperature (40-80 degrees C) conditions. Synthesised geopolymers have been characterised with regard to their leaching behaviour, following the DIN 38414-S4 [DIN 38414-S4, Determination of leachability by water (S4), group S: sludge and sediments.

Progressive supravenous granulomatous nodular eruption in a human immunodeficiency virus-positive intravenous drug user treated with highly active antiretroviral therapy.

We describe a 41-year-old human immunodeficiency virus-infected woman with a previous history of intravenous drug abuse, who developed multiple linear nodules following the superficial veins on both arms. Histopathological examination disclosed a dermal histiocytic inflammatory reaction with sarcoid-like granuloma formation occasionally showing an intracytoplasmic refractile material in the histiocytic cells. Nodular lesions developed progressively after starting on highly active antiretroviral therapy (HAART) which increased her CD4 cell count and suppressed her viral load.

Identification and chemical characterization of industrial particulate matter sources in southwest Spain.

A detailed physical and chemical characterization of coarse particulate matter (PM10) and fine particulate matter (PM2.5) in the city of Huelva (in Southwestern Spain) was carried out during 2001 and 2002. To identify the major emission sources with a significant influence on PM10 and PM2.

Physico-chemical characterization of atmospheric aerosols in a rural area affected by the Aznalcollar toxic spill, south-west Spain during the soil reclamation activities.

High levels of atmospheric contamination due to the re-suspension of pyrite particles from the mining waste slurry were recorded in the Guadiamar valley (the Guadiamar is a tributary of the Guadalquivir river) after the toxic spill of Aznalcóllar, north of the Doñana Natural Park (SW Spain). Major high-particulate events occurred during the extraction of the pyrite-rich mud layer, which covered an extensive area of the valley downstream of the confluence of the Agrio and Guadiamar rivers. This study deals with the monitoring of the ambient air quality at two stations near the village of Aznalcázar in the central part of the flooded area.

Fly ash content and distribution in lake sediments around a large power station: inferences from magnetic susceptibility analysis.

The bulk magnetic susceptibility of sediments from artificial and natural lakes around a large coal-fired power station in NE Spain has been measured. Higher magnetic susceptibility values are found in lake sediments located SE of the power station. This distribution of susceptibility values is compatible with environmental and meterological studies of emissions from the power station, which indicate a dominant SE plume direction.