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61.
62.
Incubation period of AIDS in patients infected via blood transfusion 总被引:14,自引:0,他引:14
Temporal trends in the prevalence of HIV (human immunodeficiency virus) infection are uncertain because of the reluctance of most governments to embark on large-scale programmes of serological surveillance. In the absence of such data, attempts have been made to relate the number of reported cases of AIDS (acquired immune deficiency syndrome) in a defined population to the proportion of that population infected with the virus as a specified time point. One crucial determinant of this relationship is the probability distribution of the incubation period of the disease, with the period defined as the time interval from infection to diagnosis. Recent statistical analysis suggests a mean incubation period of 4.5 years with wide confidence limits, whereas a more heuristic study reports a mean of 15 years. Here we report on a new analysis which reveals age-related differences in the mean (and median) incubation period: 1.97 (1.90) years for children (0-4 yrs old at infection), 8.23 (7.97) years for adults (5-59 yrs old), 5.50 (5.44) years for elderly patients (60 yrs and older). 相似文献
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Cox PM Harris PP Huntingford C Betts RA Collins M Jones CD Jupp TE Marengo JA Nobre CA 《Nature》2008,453(7192):212-215
The Amazon rainforest plays a crucial role in the climate system, helping to drive atmospheric circulations in the tropics by absorbing energy and recycling about half of the rainfall that falls on it. This region (Amazonia) is also estimated to contain about one-tenth of the total carbon stored in land ecosystems, and to account for one-tenth of global, net primary productivity. The resilience of the forest to the combined pressures of deforestation and global warming is therefore of great concern, especially as some general circulation models (GCMs) predict a severe drying of Amazonia in the twenty-first century. Here we analyse these climate projections with reference to the 2005 drought in western Amazonia, which was associated with unusually warm North Atlantic sea surface temperatures (SSTs). We show that reduction of dry-season (July-October) rainfall in western Amazonia correlates well with an index of the north-south SST gradient across the equatorial Atlantic (the 'Atlantic N-S gradient'). Our climate model is unusual among current GCMs in that it is able to reproduce this relationship and also the observed twentieth-century multidecadal variability in the Atlantic N-S gradient, provided that the effects of aerosols are included in the model. Simulations for the twenty-first century using the same model show a strong tendency for the SST conditions associated with the 2005 drought to become much more common, owing to continuing reductions in reflective aerosol pollution in the Northern Hemisphere. 相似文献
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67.
Three-dimensional Fourier synthesis of horse oxyhaemoglobin at 2.8 A resolution: (1) x-ray analysis 总被引:6,自引:0,他引:6
M F Perutz H Miurhead J M Cox L C Goaman F S Mathews E L McGandy L E Webb 《Nature》1968,219(5149):29-32
68.
Many bacteria are capable of interacting with platelets and inducing platelet aggregation. This interaction may be a direct
interaction between a bacterial surface protein and a platelet receptor or may be an indirect interaction where plasma proteins
bind to the bacterial surface and subsequently bind to a platelet receptor. However, these interactions usually do not trigger
platelet activation as a secondary co-signal is also required. This is usually due to specific antibody bound to the bacteria
interacting with FcγRIIa on the platelet surface. Secreted bacterial products such as gingipains and lipopolysaccharide may
also be capable of triggering platelet activation. 相似文献
69.
A General Weighted Two-Way Dissimilarity Coefficient 总被引:1,自引:1,他引:0
70.
Malaria is a major cause of morbidity and mortality in the developing world and cerebral malaria is responsible for the majority
of malaria-associated deaths. There is a strong association between thrombocytopenia and outcome in malaria, suggesting a
role for platelets in the pathogenesis of malaria. This thrombocytopenia is likely due to platelet activation possibly through
an interaction between PfEMP1 on plasmodium and CD36 on platelets. Platelet activation by plasmodium has two potential consequences.
It can lead to the formation of micro-aggregates of infected red blood cells and platelets which can occlude blood vessels
and it also leads to binding to and activation of the endothelium. 相似文献