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21.
In a set of laboratory experiments, we examined competition for phosphorus between algae and bacteria under various carbon:phosphorus (C:P) supply ratios in spatially homogeneous and heterogeneous microcosms. Experimental results were compared to those predicted by theoretical models of resource competition. In the spatially heterogeneous microcosm, algae that were inferior competitors for P persisted in vessels with high local C:P supply ratios that would cause exclusion in the spatially homogeneous microcosms. Resource competition theory, adapted to this system, provided a starting point for explaining these results. Spatial structure can enhance local diversity because locally inferior competitors are transported from source habitats into sink habitats where they would otherwise be excluded. Such local sources were determined by their resource supply ratios. These results verify the hypothesis that spatial processes enhance local diversity when a system of local habitats is divided into sources and sinks in such a way that each persisting species has at least one source within the system. However, existing theoretical models did not accurately predict distributions of competitor abundance within this experimental system. 相似文献
22.
Background
The construction of complex spatial simulation models such as those used in network epidemiology, is a daunting task due to the large amount of data involved in their parameterization. Such data, which frequently resides on large geo-referenced databases, has to be processed and assigned to the various components of the model. All this just to construct the model, then it still has to be simulated and analyzed under different epidemiological scenarios. This workflow can only be achieved efficiently by computational tools that can automate most, if not all, these time-consuming tasks. In this paper, we present a simulation software, Epigrass, aimed to help designing and simulating network-epidemic models with any kind of node behavior. 相似文献23.
Izabel Cristina dos Reis Nildimar Alves Honório Fábio Saito Monteiro de Barros Christovam Barcellos Uriel Kitron Daniel Cardoso Portela Camara Glaucio Rocha Pereira Erlei Cassiano Keppeler M?nica da Silva-Nunes Cláudia Torres Code?o 《PloS one》2015,10(9)
Fish farming in the Amazon has been stimulated as a solution to increase economic development. However, poorly managed fish ponds have been sometimes associated with the presence of Anopheles spp. and consequently, with malaria transmission. In this study, we analyzed the spatial and temporal dynamics of malaria in the state of Acre (and more closely within a single county) to investigate the potential links between aquaculture and malaria transmission in this region. At the state level, we classified the 22 counties into three malaria endemicity patterns, based on the correlation between notification time series. Furthermore, the study period (2003–2013) was divided into two phases (epidemic and post-epidemic). Higher fish pond construction coincided both spatially and temporally with increased rate of malaria notification. Within one malaria endemic county, we investigated the relationship between the geolocation of malaria cases (2011–2012) and their distance to fish ponds. Entomological surveys carried out in these ponds provided measurements of anopheline abundance that were significantly associated with the abundance of malaria cases within 100 m of the ponds (P < 0.005; r = 0.39). These results taken together suggest that fish farming contributes to the maintenance of high transmission levels of malaria in this region. 相似文献
24.
Maciel-De-Freitas R Codeço CT Lourenço-De-Oliveira R 《Medical and veterinary entomology》2007,21(3):284-292
The daily survival rate of Aedes aegypti (L) (Diptera: Culicidae) is one of the most important parameters in mathematical models of dengue transmission. In this report, we evaluate the effect of adult body size on the survival and dispersal rates of male and female Ae. aegypti, the primary dengue vector in Brazil. Independent of larval diet (i.e. size), the daily survival rate of females recaptured in the field was greater than that of males (smaller: t = 5.617; d.f. = 15; P < 0.05; larger: t = 4.241; d.f. = 16; P < 0.05). Larger males lived longer than smaller males (t = 2.2893; d.f. = 7; P < 0.05), but no size effect was observed for females (t =- 0.086; d.f. = 19; P= 0.932). The daily survival rate of smaller females was similar to that of larger females (0.712 and 0.730, respectively, as calculated by an exponential model, and 0.743 and 0.779, respectively, calculated by a non-linear model), and they dispersed further than larger females (mean distances travelled were 78.8 m and 40.9 m, respectively; t =- 10.22; d.f. = 323; P < 0.05). Adult body size did not influence male dispersal distances (t = 0.904; d.f. = 206; P= 0.367). Given our evidence that smaller females appear to have similar lifespans and evidence from other studies that they bite more frequently during a single gonotrophic cycle than larger females, our results suggest that smaller females have a higher vectorial capacity. 相似文献
25.
Amyloid-type fiber formation in control of enzyme action: interfacial activation of phospholipase A2
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The lag-burst behavior in the action of phospholipase A2 (PLA2) on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine was investigated at temperatures slightly offset from the main phase transition temperature Tm of this lipid, thus slowing down the kinetics of the activation process. Distinct stages leading to maximal activity were resolved using a combination of fluorescence parameters, including Förster resonance energy transfer between donor- and acceptor-labeled enzyme, fluorescence anisotropy, and lifetime, as well as thioflavin T fluorescence enhancement. We showed that the interfacial activation of PLA2, evident after the preceding lag phase, coincides with the formation of oligomers staining with thioflavin T and subsequently with Congo red. Based on previous studies and our findings here, we propose a novel mechanism for the control of PLA2, involving amyloid protofibrils with highly augmented enzymatic activity. Subsequently, these protofibrils form “mature” fibrils, devoid of activity. Accordingly, the process of amyloid formation is used as an on-off switch to obtain a transient burst in enzymatic catalysis. 相似文献
26.
Delphine Pessoa Caetano Souto-Maior Erida Gjini Joao S. Lopes Bruno Ce?a Cláudia T. Code?o M. Gabriela M. Gomes 《PLoS computational biology》2014,10(8)
The biological effects of interventions to control infectious diseases typically depend on the intensity of pathogen challenge. As much as the levels of natural pathogen circulation vary over time and geographical location, the development of invariant efficacy measures is of major importance, even if only indirectly inferrable. Here a method is introduced to assess host susceptibility to pathogens, and applied to a detailed dataset generated by challenging groups of insect hosts (Drosophila melanogaster) with a range of pathogen (Drosophila C Virus) doses and recording survival over time. The experiment was replicated for flies carrying the Wolbachia symbiont, which is known to reduce host susceptibility to viral infections. The entire dataset is fitted by a novel quantitative framework that significantly extends classical methods for microbial risk assessment and provides accurate distributions of symbiont-induced protection. More generally, our data-driven modeling procedure provides novel insights for study design and analyses to assess interventions. 相似文献
27.
T N Docile N A Honório D F Baptista G Pereira J A A dos Santos C T Codeço 《Neotropical Entomology》2017,46(6):613-621
Little is known about the relationship between the presence of Aedes, abiotic factors and the entomofauna existing in phytotelmatas. The aim of this study was to identify biotic and abiotic factors associated with the presence of Aedes in bromeliads sites located in a forest fragment in Rio de Janeiro, Brazil. In the study area, eight bromeliads from the Aechmea genus were chosen and kept in landscape form. Physical and chemical variables were measured. Collected aquatic insects were identified according to the literature. A total of 3102 immature insects were collected. The presence of Aedes aegypti (Linnaeus) (2.29%) was rare. Few specimens were found concentrated in urban-adjacent areas during summer. On the other hand, Aedes albopictus (Skuse) (17.57%) was found throughout the year in 0%–80% of the sites, averaging 1.0 mosq/bromelia. Aedes albopictus was found predominantly in central sites of the forest fragment. The Canonical Correspondence Analysis indicates that most taxa had a moderate association with temperature, dissolved oxygen, and pH. The abiotic variables, such as temperature and dissolved oxygen, affect the distribution of the genus Aedes vectors, while most of the other variables did not. 相似文献
28.
Carolin Marlen Degener Tatiana Mingote Ferreira de ázara Rosemary Aparecida Roque Susanne R?sner Eliseu Soares Oliveira Rocha Erna Geessien Kroon Cláudia Torres Code?o Aline Araújo Nobre J?rg Johannes Ohly Martin Geier álvaro Eduardo Eiras 《Memórias do Instituto Oswaldo Cruz》2015,110(4):517-527
The objective of this study was to evaluate the effectiveness of Aedes
aegypti mass trapping using the sticky trap MosquiTRAP (MQT) by
performing a cluster randomised controlled trial in Manaus, state of Amazonas,
Brazil. After an initial questionnaire and baseline monitoring of adult Ae.
aegypti abundance with BG-Sentinel (BGS) traps in six clusters, three
clusters were randomly assigned to the intervention arm where each participating
household received three MQTs for mass trapping during 17 months. The remaining three
clusters (control arm) did not receive traps. The effect of mass trapping on adult
Ae. aegypti abundance was monitored fortnightly with BGS traps.
During the last two months of the study, a serological survey was conducted. After
the study, a second questionnaire was applied in the intervention arm. Entomological
monitoring indicated that MQT mass trapping did not reduce adult Ae.
aegypti abundance. The serological survey indicated that recent dengue
infections were equally frequent in the intervention and the control arm. Most
participants responded positively to questions concerning user satisfaction.
According to the results, there is no evidence that mass trapping with MQTs can be
used as a part of dengue control programs. The use of this sticky trap is only
recommendable for dengue vector monitoring. 相似文献
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30.
Danielle N. C. C. Costa Cláudia T. Code?o Moacyr A. Silva Guilherme L. Werneck 《PLoS neglected tropical diseases》2013,7(8)