645,883 research outputs found

    The Changing Epidemiology of Malaria in Ifakara Town, Southern Tanzania.

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    Between 1995 and 2000 there were marked changes in the epidemiology of malaria in Ifakara, southern Tanzania. We documented these changes using parasitological and clinical data from a series of community- and hospital-based studies involving children up to the age of 5 years. There was a right shift and lowering in the age-specific parasite prevalence in the community-based cohort studies. The incidence of clinical malaria in placebo-receiving infants in additional study cohorts dropped from 0.8 in 1995 to 0.43 episodes per infant per year in 2000, an incidence rate ratio of 0.53 (95% confidence interval: 0.404, 0.70, P<0.0001). At the same time, there was an increase in the total number of malaria admissions and a marked right shift in the age pattern of these admissions (median age in 1995 1.55 years vs. 2.33 in 2000, P<0.0001). However, the burden of malaria deaths remained in infants. We discuss how these dramatic changes in the epidemiology of malaria may have arisen from the use of currently available malaria control tools. Caution is required in the interpretation of hospital-based data as it is likely to underestimate the impact of anaemia on mortality in the community, where most paediatric deaths occur. Even in low/moderate malaria transmission settings, where older children suffer most malaria episodes, targeting effective malaria control at infants may produce important reductions in infant mortality caused by malaria

    Two Taylor Algorithms for Computing the Action of the Matrix Exponential on a Vector

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    Ibáñez González, JJ.; Alonso Abalos, JM.; Alonso-Jordá, P.; Defez Candel, E.; Sastre, J. (2022). Two Taylor Algorithms for Computing the Action of the Matrix Exponential on a Vector. Algorithms. 15(2):1-48. https://doi.org/10.3390/a1502004814815

    What explains the invading success of the aquatic mud snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)?

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    The spread of non-native species is one of the most harmful and least reversible disturbances in ecosystems. Species have to overcome several filters to become a pest (transport, establishment, spread and impact). Few studies have checked the traits that confer ability to overcome these steps in the same species. The aim of the present study is to review the available information on the life-history and ecological traits of the mud snail, Potamopyrgus antipodarum Gray (Hydrobiidae, Mollusca), native from New Zealand, in order to explain its invasive success at different aquatic ecosystems around the world. A wide tolerance range to physico-chemical factors has been found to be a key trait for successful transport. A high competitive ability at early stages of succession can explains its establishment success in human-altered ecosystems. A high reproduction rate, high capacity for active and passive dispersal, and the escape from native predators and parasites explains its spread success. The high reproduction and the ability to monopolize invertebrate secondary production explain its high impact in the invaded ecosystems. However, further research is needed to understand how other factors, such as population density or the degree of human perturbation can modify the invasive success of this aquatic snai

    Cooperation between expert knowledge and data mining discovered knowledge: Lessons learned

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    Expert systems are built from knowledge traditionally elicited from the human expert. It is precisely knowledge elicitation from the expert that is the bottleneck in expert system construction. On the other hand, a data mining system, which automatically extracts knowledge, needs expert guidance on the successive decisions to be made in each of the system phases. In this context, expert knowledge and data mining discovered knowledge can cooperate, maximizing their individual capabilities: data mining discovered knowledge can be used as a complementary source of knowledge for the expert system, whereas expert knowledge can be used to guide the data mining process. This article summarizes different examples of systems where there is cooperation between expert knowledge and data mining discovered knowledge and reports our experience of such cooperation gathered from a medical diagnosis project called Intelligent Interpretation of Isokinetics Data, which we developed. From that experience, a series of lessons were learned throughout project development. Some of these lessons are generally applicable and others pertain exclusively to certain project types

    Meiotic behavior of two polyploid species of genus Pleurodema (Anura: Leiuperidae) from central Argentina

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    Polyploidy is an important evolutionary force but rare in vertebrates. However, in anurans, the genus Pleurodema has polyploid species, two of them tetraploid and one octoploid. The manner in which the chromosomes join in diakinesis can vary among species and, crucially, if they differ in their ploidy levels. In this work, we describe the meiotic configurations in two cryptic species from central Argentina, with different ploidy levels, Pleurodema kriegi (tetraploid) and P. cordobae (octoploid). A total of 306 diakineses from 19 individuals were analyzed. In meiosis, P. kriegi form 22 bivalents, whereas P. cordobae exhibits variation in meiotic figures. We discuss the possible allo- and autopolyploid origin of these species, and we consider that the autopolyploid origin of P. cordobae from P. kriegi might be the most feasible.Fil: Salas, Nancy Edith. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; ArgentinaFil: Valetti, Julian Alonso. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grenat, Pablo Raúl. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Otero, Manuel Alejandro. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martino, Adolfo Ludovico. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Generalized uncertainty principle impact onto the black holes information flux and the sparsity of Hawking radiation

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    We investigate the generalized uncertainty principle (GUP) corrections to the entropy content and the information flux of black holes, as well as the corrections to the sparsity of the Hawking radiation at the late stages of evaporation. We find that due to these quantum gravity motivated corrections, the entropy flow per particle reduces its value on the approach to the Planck scale due to a better accuracy in counting the number of microstates. We also show that the radiation flow is no longer sparse when the mass of a black hole approaches Planck mass which is not the case for non-GUP calculations.Comment: 6 pages, 2 figures, typos corrected, published in Phys. Rev.
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