839 resultados para Semi-arid region


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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O objetivo deste trabalho foi o de determinar a concentração hidrogeniônica (pH), acidez total titulável e tempo de redução do azul de metileno no fluido ruminal de caprinos com ou sem raça definida, mantidos em pastagens artificiais, exclusivas de gramíneas, ou em caatinga, durante as épocas chuvosa e seca do ano. O delineamento experimental foi inteiramente casualizado, sendo analisado em esquema fatorial 2³ (animais com e sem raça definida, pastagens artificiais e em caatinga, épocas chuvosa e seca do ano). O tipo de pastagem influenciou significativamente (p < 0,05) os valores encontrados para acidez total titulável. em relação ao pH, o tipo de pastagem e época do ano foram significativamente (p < 0,05) os fatores mais incisivos. A atividade microbiana, avaliada através dos parâmetros estudados, foi mais intensa na época das águas e na caatinga em relação à da seca e pastagens artificiais, respectivamente. Na avaliação dos resultados desses testes, deve-se sempre levar em consideração principalmente a época do ano e o tipo de pastagem, sem, no entanto, desprezar o fator raça.

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Rock cavies are rodents found in the semi-arid caatinga of Brazil. We studied the structure of the rock cavy placenta by light and transmission electron microscopy. The exchange area of the labyrinth was organized in lobes separated by interlobular areas. The interhaemal barrier was syncytial haemomonochorial. The syncytiotrophoblast had recesses in the basal membrane and some invaginations of the apical membrane, but transtrophoblastic channels could not be found. The interlobular regions comprised syncytiotrophoblast, enclosing maternal venous blood channels, and cytotrophoblast. There was a prominent subplacenta composed of cytotrophoblast and syncytiotrophoblast. Microvilli projected into spaces between the cytotrophoblasts and into lacunae within the syncytiotrophoblast. The yolk sac epithelium exhibited coated pits, endocytotic vesicles and larger vacuoles, consistent with a role in protein uptake from the uterine lumen. Tight junctions between these cells provided a barrier to diffusion by the intercellular route. The reproductive biology of the rock cavy differs from other members of the family, including the guinea pig, but the architecture of the placenta remains remarkably constant. (c) 2004 Elsevier Ltd. All rights reserved.

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The frog species Ceratophrys joazeirensis Mercadal, 1986 is only known from the Caatinga (semi-arid savanna) and, until recently, from the type locality of Juazeiro, State of Bahia, Brazil. It has now also been found in the States of Paraíba and Rio Grande do Norte, in environments of hypoxerophylic Caatinga. Cytogenetic and comparative analysis of the cranial morphology of C. joazeirensis and C. aurita (Raddi, 1823) were undertaken. The karyotype of the species is also shown for the first time. The results show important differences in the cranial morphology between C. joazeirensis (8n) and C. aurita (8n), species whose areas of distribution (Caatinga and Northeast Atlantic forest, respectively) are contiguous. The chromosomes of C. joazeirensis show similar size and morphology to the ones of C. aurita (C. dorsata), C. ornata Bell, 1843 (8n) and C. cranwelli Barrio, 1980 (2n). Such data would be in agreement with the opinion of some authors who consider these species to constitute a monophyletic group. Copyright © 2006 Magnolia Press.

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The Triassic fish faunas of the Southern Hemisphere are only known from a few sedimentary basins and the most productive sites are those from the Karoo Supergroup, in South Africa and the Sydney Basin of Australia. A single lungfish tooth plate ascribed to Ptychoceratodus cf. philippsi was recovered from Late Triassic (Carnian) red beds of southern Brazil and is described herein. This find extends to South America the palaeogeographic distribution of the genus, which occurs in the Early Triassic of Australia and South Africa and the Middle/Late Triassic of Europe and Late Triassic of Madagascar and India. The presence of this dipnoan solely in the uppermost part of the Santa Maria Formation suggests that the migration of Ptychoceratodus towards the Paraná Basin began not before the late Induan/early Olenekian (late Early Triassic). At that time, more humid (monsoonal) conditions prevailed in what is now southern Brazil, compared to semi-arid/desert conditions that dominated the Late Permian and possibly the earliest Early Triassic (the latter presumably not represented in the Paraná Basin). © The Geological Society of London 2008.

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The present study aimed to assess the sediment quality in a tropical estuary located in the northeast of Brazil under semi-arid conditions and multiple sources of contamination, using both toxicity bioassays and metal distribution. The metal distribution followed a concentration gradient decreasing one order of magnitude from the inner station toward the outer estuary, with amounts in the following order: Fe > Al > Zn > Cr > Pb > Cu. The index of geoaccumulation indicated a metal enrichment in the Ceará river sediment, mainly at inner sites, considered from moderately to strongly contaminated by Al, Cu, Cr and Zn. Sediment samples were considered toxic by means of whole sediment tests with copepods (reproduction) and amphipods (survival), and also elutriate fraction and sediment-water interface with sea urchin embryos (development). Acute and chronic toxicity did not exhibit a significant correlation with metals, emphasizing the influence of other contaminants mainly related to the pollution sources installed in the mid-estuary. © 2013 Elsevier Ltd. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

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Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

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A Bacia Bauru (Cretáceo Superior), acumulou uma seqüência sedimentar continental essencialmente arenosa. Numa fase inicial desértica, o seu substrato basáltico foi soterrado por extensa e monótona cobertura de areias eólicas com intercalações subordinadas de depósitos de loesse. O relevo original do substrato favoreceu a formação de uma drenagem regional endorrêica, sob clima semi-árido, propiciando assim condições de formação do Paleopantanal Araçatuba. Os depósitos paludiais (Formação Araçatuba) constituem estratos tabulares de siltitos e arenitos de cor cinza claro esverdeado típica, eventualmente cimentados por carbonato de cálcio. Moldes e pseudomorfos de cristais de gipsita e dolomita foram identificados na unidade. Aparentemente, estão associados com gretas de ressecação, marcas de raízes e intervalos com laminação tipo climbing ripple, que indicam ambiente de águas salinas rasas e relativamente calmas, submetidas a fases de exposição subaérea e ressecação. Nos limites da área de ocorrência da Formação Araçatuba, as unidades arenosas podem exibir feições sigmóides e estratificação contorcida, comuns em depósitos deltaicos marginais. A Formação Araçatuba é contornada e posteriormente encoberta por depósitos eólicos da Formação Vale do Rio do Peixe.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Electromagnetic methods have been extensively applied in the prospecting of sulphide bodies and other conducting materials. The interpretation of e. m. data is based on the results obtained either with reduced scale or analytical modelling. In most models, the host rocks, the overburden as well as the halo of disseminated sulphides are considered highly resistive although in nature they are often weakly conductive. Presence of a well-developed conducting overburden in tropical and sub-tropical regions and a saline rich crustal layer in semi-arid regions have been found to modify significantly the e. m. anomalies in practice. Therefore, the parameters of the target, determined on the basis of simple models where the presence of the conducting environment is neglected, are found to be in considerable error. The effects of the overburden on the e. m. anomalies of a dipping tabular ore body were studied with reduced scale models for varying response parameters of both the overburden and the orebody, and also for different depths and dips of the target. The overburden and the orebody were represented by metallic sheets of varying thickness in the scale model developed in accordance with the law of electromagnetic similitude. The results of these investigations show that the overburden affects the anomaly by causing: a) phase rotation; b) amplitude reduction; c) base level displacement; d) reversion of the quadrature; and e) appearance of an extra peak in the quadrature in the case of low dipping models. The last two effects complicate the quantification of the anomalies but, on the other hand, provide a qualitative indication of the response parameters of both the ore body and the overburden. The results were assembled in the form of Argand diagrams and, finally, an interpretation scheme is suggested for the e. m. field data on the basis of these diagrams.

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This work aimed to evaluate the carcass yields, commercial cuts and non-carcass components of Santa Inês lambs fed with 30, 40, 50 or 60% of oldman saltbush hay with concentrated. Were used 32 castrated lambs at 8 months old and initial body weight of 22 + 1.97kg, housed individually and slaughtered after 60 days of feedlot. The weights of hot and cold carcass decreased linearly with the inclusion of saltbush hay in the diet, however, there was no effect for true carcass yield and commercial cuts: shoulder (19.26%), neck (8.52%) ribs (26.57%) and leg (33.88%). There was a linear decrease for ribeye area and fat thickness when the level of hay in the diet increased. The weights and yields of skin, liver, heart, kidneys with perirenal fat, omental and mesenteric fats decreased linearly with the inclusion of hay in the diet, while the content (%) of gastrointestinal tract increased. The increased proportion of saltbush hay in the diet of lambs provided adequate true carcass yield and commercial cuts, however, reduces the ribeye area and fat thickness, important measurements in the qualitative evaluation of the lamb's carcass.

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The almost complete absence or misdistribution of water as a natural resource frequently constitute a limiting factor for plant growth and development in the semi-arid northeastern Brazil. In this context, the use of appropriate irrigation techniques is an essential and indispensable factor for proper functioning of the primary and secondary metabolisms in plants. This study aimed to assess the metabolism of the Syrah grapevine in the semi-arid northeastern Brazil, by using three irrigation strategies (controlled deficit irrigation [CDI], deficit irrigation [DI], and full irrigation [FI]). The research was conducted at Embrapa Semiarid (Embrapa-Brazilian Agricultural Research Corporation), Experimental Field of Bebedouro, municipality of Petrolina, state of Pernambuco, Brazil. The statistical design was randomized blocks, with a 3 x 6 factorial scheme. Six samplings were performed throughout the experiment cycle at 54, 60, 73, 87, 101, and 115 days after pruning (DAP). We analyzed the total soluble sugars, reducing sugars, total soluble protein, and invertase activity. Analysis of variance and the F test were performed for all analyzed variables. The means were compared using the Tukey test at 5% significance. At the end of the experiment cycle, DI was found to increase the average acid invertase activity in the plant cell wall. Further, by the end of the experiment cycle, the total soluble sugars and reducing sugars increased in all plants in the three irrigation strategies. Thus, we conclude that it is possible to reduce water consumption in vineyards of the semi-arid northeastern Brazil, without significantly affecting the protein and sugar metabolisms in the plants.