968 resultados para 270203 Population and Ecological Genetics
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Among the determinant factors in the resistance and susceptibility of Biomphalaria to Schistosoma mansoni, hemocytes play an important role. Aiming at studying S. mansoni/Biomphalaria interactions related to hemocytes, the first step is certainly connected with the standardization of this cell population in uninfected Biomphalaria. In this way, quantification of this cell population in hemolymph, as well as its phagocitary capacity, have been determined for the first time. Furthermore, using susceptible and resistant strains of B. glabrata and B. tenagophila, the hemocytegram and phagocytary capacity of hemocytes after infection with S. mansoni were determined too. Resistant and susceptible strains of B.glabrata (BA and BH, respectively), as well as resistant and susceptible strains of B. tenagophila (Taim and CF, respectively) were infected with 10 miracidia of the LE and SJ strains of S. mansoni, respectively. These infected snails and respective uninfected controls were assessed in relation to the number of circulating hemocytes and alteration in the phagocytary capacity, by using Zymozan and MTT. Reading was taken by means of a spectrophotometer at 5 hours and 1,2,5,10,20 and 30 days after infection. The results showed a decrease in population of the circulating phagocytary cells, 5 hours after infection. One day post-infection, the circulating cells of the susceptible snails showed an increased metabolic activity, but the same event could not be observed in the resistant strains. In the subsequent observation periods, significant differences among the strains studied could not be observed until the end of the experiment
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Portuguese historiography has mostly adopted a pessimistic view regarding the contribution of the railways to the development of country. Yet, railway access helped to increase population concentration and economic development, favoring migration into towns, the growth of pre-existing urban centers, and the emergence of new centers. But railways tended to be more beneficial to regions that were already prosperous and to aggravate the conditions unfavorable to development in areas with greater structural weaknesses.
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AbstractLatent tuberculosis infection (LTBI) and human immunodeficiency virus (HIV)-coinfection are challenges in the control of tuberculosis transmission. We aimed to assess and summarize evidence available in the literature regarding the treatment of LTBI in both the general and HIV-positive population, in order to support decision making by the Brazilian Tuberculosis Control Program for LTBI chemoprophylaxis. We searched MEDLINE, Cochrane Library, Centre for Reviews and Dissemination, Embase, LILACS, SciELO, Trip database, National Guideline Clearinghouse, and the Brazilian Theses Repository to identify systematic reviews, randomized clinical trials, clinical guidelines, evidence-based synopses, reports of health technology assessment agencies, and theses that investigated rifapentine and isoniazid combination compared to isoniazid monotherapy. We assessed the quality of evidence from randomized clinical trials using the Jadad Scale and recommendations from other evidence sources using the Grading of Recommendations, Assessment, Development, and Evaluations approach. The available evidence suggests that there are no differences between rifapentine + isoniazid short-course treatment and the standard 6-month isoniazid therapy in reducing active tuberculosis incidence or death. Adherence was better with directly observed rifapentine therapy compared to self-administered isoniazid. The quality of evidence obtained was moderate, and on the basis of this evidence, rifapentine is recommended by one guideline. Available evidence assessment considering the perspective of higher adherence rates, lower costs, and local peculiarity context might support rifapentine use for LTBI in the general or HIV-positive populations. Since novel trials are ongoing, further studies should include patients on antiretroviral therapy.
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Polygonanthus amazonicus Ducke já foi incorporada em oito famílias diferentes, mas era conhecida de apenas uma árvore desde a primeira coletada em 1929. Uma excursão do projeto Flora Amazônica comprovou sua área de ocorrência, que é de pelo menos 17.500 km2 na região compreendida entre Maués e Borba no Estado do Amazonas. Seu habitat e provável meio de dispersão são descritos. o caso desta e de muitas outras espécies com escassa representação nos herbários demonstra a necessidade de se manter um intenso programa de coleta botânica para se manter uma base mais realista da distribuição de muitas espécies.
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This paper draws upon a detailed longitudinal survey of households living on agricultural plots in the northern three provinces of the Ecuadorian Amazon, the principal region of colonization by migrants in Ecuador since the 1970s. Following the discovery of petroleum in 1967 near what has subsequently come to be the provincial capital and largest Amazonian city of Lago Agrio, oil companies built roads to lay pipelines to extract and pump oil across the Andes for export. As a result, for the past 30 years over half of both Ecuador's export earnings and government revenues have come from petroleum extracted from this region. But the roads also facilitated massive spontaneous in-migration of families from origin areas in the Ecuadorian Sierra, characterized by minifundia and rural poverty. This paper is about those migrants and their effects on the Amazonian landscape. We discuss the data collection methodology and summarize key results on settler characteristics and changes in population, land use, land ownership, technology, labor allocation, and living conditions, as well as the relationships between changes in population and changes in land use over time. The population in the study region has been growing rapidly due to both natural population growth (high fertility) and in-migration. This has led to a dramatic process of subdivision and fragmentation of plots in the 1990's, which contrasts with the consolidation of plots that has occurred in most of the mature frontier areas of the Brazilian Amazon. This fragmentation has led to important changes in land tenure and land use, deforestation, cattle raising, labor allocation, and settler welfare.
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Las áreas montanas brindan numerosos bienes y servicios a la humanidad cómo la provisión de agua. Asimismo, albergan una biota muy diversa y existe en ellas una actividad económica de considerable importancia centrada en la ganadería. En algunos casos las actividades asociadas a la ganadería pueden modificar los ecosistemas montanos y los bienes y servicios que brindan de forma drástica. Esto se debe a los cambios en la vegetación, y la pérdida y compactación de los suelos, que tiene repercusiones en la cantidad de agua captada, evapotranspirada y almacenada. También tiene repercusiones sobre la biodiversidad, tanto positivas como negativas. Aquí nos propusimos investigar cómo los cambios en la cobertura vegetal producidos por cuatro siglos de uso ganadero en el piso superior de las Sierras de Córdoba (Centro Argentino) han afectado a atributos del ecosistema como la diversidad vegetal, la integridad de los suelos y la capacidad de proveer agua a la población humana. A su vez, nos propusimos estudiar en detalle cómo las distintas opciones actuales de manejo pueden afectar a la cobertura vegetal y por ende a los atributos del ecosistema. De este modo, esperamos: (1) poder desarrollar un modelo espacialmente explícito que permita predecir la evolución del ecosistema ante distintos escenarios de manejo. (2) Más a largo plazo determinar los costos y los beneficios de los distintos manejos, en términos de la conservación de la biodiversidad, los suelos y la provisión de agua. El área de estudio cuenta un Sistema de Información Geográfica muy completo que incluye numerosas capas de información (vegetación, topografía, casas y caminos y otras). Además, existe en el área un Parque Nacional, con potreros bajo distintos manejos ganaderos (exclusión, cargas ganaderas moderadas continuas y estacionales), y una zona con herbivoría nativa de guanacos, que fueron reintroducidos recientemente en el Parque. Fuera del Parque, hay establecimientos con ganadería tradicional, con cargas ganaderas altas; así como un área donde se ha realizado una restauración modelo mediante reforestación y revegetación de zonas erosionadas. Estos escenarios representan una oportunidad muy especial para realizar estudios comparativos de la evolución de la fisonomía, composición florística, diversidad vegetal, integridad del suelo (erosión, tasa de infiltración, contenido de agua a lo largo del año) y el caudal de los arroyos en la estación seca. En este proyecto proponemos seguir con mediciones de la evolución de la vegetación bajo los distintos escenarios y seguir averiguando métodos de restauración de la vegetación. Además, proponemos empezar a realizar mediciones relacionadas al valor de los distintos tipos de cobertura vegetal, resultado de cuatro siglos de historia de disturbio, sobre la diversidad y los recursos hídricos. Por otro lado, realizaremos mediciones ecofisiológicas en las especies dominantes, para comprender sus efectos sobre el ciclo del agua.
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The vast network of hedges in Ireland provide habitats of great importance to the wildlife of the country, yet surprisingly enough, only very limited survey work has been carried out on our hedgerows in the past. Now with the implementation of the new Rural Environmental Protection Scheme, farmers will be paid to manage their hedgerows in such a way as to make them into increasingly attractive wildlife habitats. However, hedgerow management expertise seems to be somewhat lacking in Ireland and we must draw upon the knowledge of our neighbours in the E.U. where quite an amount of research has been carried out on this subject. The aim of this study is to present the relevant aspects of the research for the benefit of the people who will be involved in the administration of the Rural Environmental Protection Scheme and to anyone else involved in hedgerow management.
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v.34:no.6(1952)
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n.s. no.18(1983)
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A new species, Isoctenus malabaris, is described from southern Brazil. This spider was abundantly collected with pitfall traps at Araucaria Forests (Mixed Ombrophilous Forest) domain. The activity of this species was studied in three distinct habitats (primary and secondary forests and silvicultures) during 20 months. A bimodal seasonal activity pattern, of males, was observed. Abundance differences of this species between habitats were not significant.
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The population of the hermit crab Pagurus criniticornis (Dana, 1852) was studied based on seasonal abundance, size frequency distribution, sex ratio, reproductive period, fecundity and shell relationship. Specimens were collected monthly by SCUBA diving in the infralittoral area of Anchieta Island, Ubatuba. A total of 1,017 individuals was analyzed. Animal size (minimum and maximum shield length, respectively) was 0.7 and 2.9 mm for males, 0.6 and 2.8 mm for non-ovigerous females, and 1.0 and 2.5 mm for ovigerous females. The sex ratio was 1:1.29. Sexual dimorphism was recorded by the presence of males in the largest size classes. Ovigerous females were captured during all months along the year, with percentages varying from 8% (July) to 84.3% (February) in relation to the total females collected. Mean ± SD fecundity was 168 ± 125 eggs and tended to increase with increasing hermit size. Shells of four gastropod species [Cerithium atratum (Born, 1778), Morula nodulosa (Adams, 1845), Anachis lyrata (Sowerby, 1832) and Modulus modulus (Linnaeus, 1758)] were occupied by ovigerous females of P. criniticornis but fecundity was not significantly different in relation to the different shell types. The profile showed continuous and intense reproduction of P. criniticornis probably related to strategies developed to compensate for interspecific competition in the studied insular area.
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ABSTRACT The present study encompasses the species composition and ecological characteristics of the snake community in a Cerrado-Amazon transition zone in Midwest of Brazil (state of Mato Grosso). The data were collected during six excursions to the "Tanguro" (study area) by visual encounter survey, pitfall traps with drift fences and non-systematic sampling. We collected 194 specimens, distributed in 34 species, 26 genera, and eight families. The most abundant species were Crotalus durissus Linnaeus, 1758 (n = 50), Philodryas olfersii (Lichtenstein, 1823) (n = 15), Philodryas nattereri Steindachner, 1870 (n = 13), Xenodon rabdocephalus (Wied, 1824) (n = 12), Lachesis muta (Linnaeus, 1766) (n = 10) and Erythrolamprus almadensis (Wagler, 1824) (n = 10). The composition of species found here represents a combination of Cerrado and Amazonian savanna fauna.