African tropical rainforest net carbon dioxide fluxes in the twentieth century

The African humid tropical biome constitutes the second largest rainforest region, significantly impacts global carbon cycling and climate, and has undergone major changes in functioning owing to climate and land-use change over the past century. We assess changes and trends in CO2 fluxes from 1901 to 2010 using nine land surface models forced with common driving data, and depict the inter-model variability as the uncertainty in fluxes. The biome is estimated to be a natural (no disturbance) net carbon sink (−0.02 kg C m−2 yr−1 or −0.04 Pg C yr−1, p < 0.05) with increasing strength fourfold in the second half of the century. The models were in close agreement on net CO2 flux at the beginning of the century (σ1901 = 0.02 kg C m−2 yr−1), but diverged exponentially throughout the century (σ2010 = 0.03 kg C m−2 yr−1). The increasing uncertainty is due to differences in sensitivity to increasing atmospheric CO2, but not increasing water stress, despite a decrease in precipitation and increase in air temperature. However, the largest uncertainties were associated with the most extreme drought events of the century. These results highlight the need to constrain modelled CO2 fluxes with increasing atmospheric CO2 concentrations and extreme climatic events, as the uncertainties will only amplify in the next century

Rhipicephalus sanguineus (Acari: Ixodidae), the brown dog tick, parasitizing humans in Brazil Rhipicephalus sanguineus (Acari: Ixodidae), o carrapato vermelho do cão, parasitando humanos no Brasil

The objective of this paper is to describe four cases of human parasitism by Rhipicephalus sanguineus (Latrielle) in Brazil. During an investigation regarding the species of ectoparasites of domestic dogs from the metropolitan region of Recife, Pernambuco state, four dog owners were found to be parasitized by ticks. The ticks were collected from these individuals and their dogs. All the ticks were identified as Rhipicephalus sanguineus . These are, to our knowledge, the first four cases of human parasitism by this tick species in Brazil. The possible implications of this finding are discussed here.<br>O objetivo deste artigo é descrever quatro casos de parasitismo humano por Rhipicephalus sanguineus (Latrielle) no Brasil. Durante uma investigação sobre as espécies de ectoparasitas de cães domésticos provenientes da Região Metropolitana de Recife, Pernambuco, quatro proprietários de cães foram encontrados parasitados por carrapatos. Foram coletados carrapatos dos indivíduos e de seus cães. Todos os carrapatos foram identificados como Rhipicephalus sanguineus, sendo, portanto, descritos os primeiros quatro casos de parasitismo humano por esta espécie de carrapato, no Brasil. Neste trabalho, são discutidas as possíveis implicações epidemiológicas deste achado