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Search Results: 1 - 10 of 474073 matches for " Felipe A. Dias "
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Shifts in composition of avian communities related to temperate-grassland afforestation in southeastern South America Altera es na composi o de comunidades de aves relacionadas ao florestamento de campos temperados no sudeste da América do Sul
Rafael A. Dias,Vinicius A. G. Bastazini,Maycon S. S. Gon?alves,Felipe C. Bonow
Iheringia. Série Zoologia , 2013,
Abstract: Afforestation of temperate grasslands with fast-growing trees for industrial pulpwood production is spreading in South America. Despite high afforestation rates resulting from governmental policies that stimulate pulpwood production in grasslands of southern Brazil and Uruguay, the impact of this activity on biodiversity remains to be properly assessed. We used an Impact-Reference study design to evaluate how grassland afforestation affects the composition of grassland bird assemblages. We sampled eucalyptus plantations and neighboring natural grasslands in southern Brazil from 2006-2009, and relied on nested sampling and analysis to separate the effects of afforestation from the natural variability of grasslands. We recorded a significant difference in composition between assemblages from grasslands and tree plantations. Species adapted to open, treeless areas tended to be negatively affected in relation to edge or forest birds in eucalyptus plantations. Afforestation is systematically replacing the bird assemblage of hilltop grasslands by a collection of common edge and forest species that occur in nearby riverine and hillside forests. Although most grassland birds negatively affected by tree plantations are common and widespread, observed and predicted afforestation rates in southeastern South America may result in regional population reductions in the near future. O florestamento de campos temperados com árvores de crescimento rápido para a produ o industrial de celulose está aumentando na América do Sul. Apesar das elevadas taxas de florestamento resultantes de políticas governamentais que estimulam o plantio de árvores para celulose em campos do sul do Brasil e Uruguai, o impacto dessa atividade sobre a biodiversidade ainda carece de avalia o adequada. Utilizamos um delineamento experimental do tipo impacto-referência para avaliar como o florestamento dos campos afeta a composi o da assembleia de aves campestres. Amostramos planta es de eucalipto e campos nativos no sul do Brasil entre 2006-2009 e nos valemos de amostragem e análise aninhada para separar os efeitos do florestamento da variabilidade natural dos campos. Registramos uma diferen a significativa na composi o entre as assembleias de aves do campo e de planta es de eucalipto. Espécies adaptadas a áreas abertas destituídas de árvores foram afetadas negativamente pelo florestamento, ao passo que aves florestais ou de borda de floresta foram favorecidas pela planta o de eucalipto. O florestamento está sistematicamente substituindo a assembleia de aves de campos de topos de morros por
Single factor financial asset pricing models: an empirical test of the Capital Asset Pricing Model CAPM and the Downside Capital Asset Pricing Model D-CAPM Modelos de precifica o de ativos financeiros de fator único: um teste empírico dos modelos CAPM e D-CAPM
Felipe Dias Paiva
Rege : Revista de Gest?o , 2005,
Abstract: This study analyzed the Capital Asset Pricing Model CAPM as well as the Downside Capital Asset Pricing Model D-CAPM and evaluated the latter as an efficient alternative asset pricing model. The returns of 40 companies on the S o Paulo Stock Exchange BOVESPA were studied between December 1996 and August 2002. To test the models the study used as variables the Interbank Deposit Certificate CDI as a risk free asset and the Index of S o Paulo Stock Exchange IBOVESPA as a proxy of the market portfolio. The D-CAPM was shown to be more useful in explaining the return of the stock market than the CAPM. O objetivo deste estudo é analisar o capital asset pricing model (CAPM) e o downside capital asset pricing model (D-CAPM), bem como avaliar se este último modelo é uma eficiente alternativa de modelo de precifica o de ativos. Os dados da pesquisa referem-se a 40 retornos de companhias listadas na Bolsa de Valores de S o Paulo, de dezembro de 1996 a agosto de 2002. O artigo utilizou, para testar os modelos, as variáveis Certificado de Depósito Interbancário (CDI), como um ativo livre de risco, e o índice da Bolsa de Valores de Sao Paulo (Ibovespa), como proxy do portfólio de mercado. Conclui-se, ent o, que o D-CAPM possui uma maior capacidade explicativa dos retornos dos ativos se comparado ao CAPM.
Chemical migration during soil water retention curve evaluation
Pires, Luiz F.;Villanueva, Felipe C.A.;Dias, Nivea M.P.;Bacchi, Osny O. Santos;Reichardt, Klaus;
Anais da Academia Brasileira de Ciências , 2011, DOI: 10.1590/S0001-37652011005000032
Abstract: wetting and drying (w-d) cycles can induce important elemental migrations in soils. the main purpose of this work was to study the possible existence of soil chemical elemental migrations in samples submitted to repeated w-d cycles during evaluations of soil water retention curve (swrc). the experimental measurements were carried out by atomic absorption spectrometry (aas) for ca2+, mg2+ and k+ on samples of three different brazilian tropical soils (geric ferralsol, eutric nitosol and rhodic ferralsol). results demonstrate an increase in the electrical conductivity of the water extracted from the samples and significant losses of ca2+, mg2+ and k+ during the applications of up to nine w-d cycles. it was also observed differences in swrc for all soils when samples submitted to the application of several w-d cycles were compared with samples not submitted to it. these differences occurred at the region of both structural and textural pores. a possible explanation for these results could be the soil chemical migration during the sequences of w-d cycles, which can affect the soil structure development.
Bioinformatics of the sugarcane EST project
Telles, Guilherme P.;Braga, Marília D.V.;Dias, Zanoni;Tzy-Li, Lin;Quitzau, José A.A.;Silva, Felipe R. da;Meidanis, Jo?o;
Genetics and Molecular Biology , 2001, DOI: 10.1590/S1415-47572001000100003
Abstract: the sugarcane est project (sucest) produced 291,904 expressed sequence tags (ests) in a consortium that involved 74 sequencing and data mining laboratories. we created a web site for this project that served as a ?meeting point? for receiving, processing, analyzing, and providing services to help explore the sequence data. in this paper we describe the information pathway that we implemented to support this project and a brief explanation of the clustering procedure, which resulted in 43,141 clusters.
Impactos ambientais do manejo agroecológico da caatinga no Rio Grande do Norte
Barreto, Hilton Felipe Marinho;Soares, Jo?o Paulo Guimar?es;Morais, Débora Andréa Evangelista Fa?anha;Silva, Andréa Cristina Capriatta;Salman, Ana Karina Dias;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010001000004
Abstract: the objective of this work was to evaluate the environmental impacts of caatinga agroecological handling, in production unities of family farms, in rio grande do norte, using the method ambitec of animal production - environmental dimension, developed by embrapa meio ambiente. seven family farm production units were evaluated within four projects of agrarian reform in the county of apodi, rn, brazil. the data for surveying were obtained through applying queries to the responsibles for the production units, who attributed - to each studied variable - a value which represented the alteration resulted from the technology implementation. after insertion of the alteration coeficients of each indicator by production unit, the impact coeficients was automatically calculated using ambitec sheet. the caatinga agroecological handling had a positive environmental impact, and its major contributions were related to the positive effects of the following indicators: soil production capacity, use of material input, product quality, and decrease of pollution emission to atmosphere. two indicators had negative impact scores: energy use and use of natural resources. by the superiority of the benefits, caatinga agroecological handling is a technology innovation which generates positive environmental impacts.
Prevalência e fatores de risco de leptospirose bovina no Estado do Maranh?o
Silva, Felipe J.;Concei??o, Washington L.F.;Fagliari, José J.;Girio, Raul J.S.;Dias, Ricardo A.;Borba, Mauro R.;Mathias, Luis A.;
Pesquisa Veterinária Brasileira , 2012, DOI: 10.1590/S0100-736X2012000400006
Abstract: prevalence and risk factors of bovine leptospirosis in the state of maranh?o were investigated. based on production parameters that vary across different production systems, management practices, the purpose of exploitation, the average size of herds and market systems, the state was divided in four sampling circuits. the study aimed to investigate the epidemiological features of bovine leptospirosis in the state of maranh?o, in order to determine the prevalence of the infection in cattle and herds, to determine the occurrence of serovars of leptospira spp., to identify risk factors associated with leptospirosis in cattle and to differentiate the livestock circuits itself regarding the prevalence of leptospirosis. the survey was conducted in 136 herds in the circuit i, in which 841 > 24 months old females were analyzed; 238 in the circuit ii and 2,582 females were analyzed; 122 in the circuit iii and 869 females were analyzed; 77 in the circuit iv and 540 females were analyzed; a total of 573 herds and 4,832 females were analyzed. the presence of antibodies against leptospira spp. was verified by microscopic agglutination test (mat). of the 4,832 cows examined, 1,904 (35.94%, ci 95% = 33.01% - 38.98%) were positive. of the 573 herds, 380 (64.81%, ci 95% = 61.10% - 68.35%) were positive. serovars hardjo and wolffi were the most frequent in the state. the circuit iii showed the lowest prevalence of leptospirosis in all comparisons. the variables presence of horses (p = 0.000), presence of capybaras (p = 0.034) and herds with up to 32 adult females (p = 0.002) were identified as risk factors for leptospirosis.
A Herbivorous Mite Down-Regulates Plant Defence and Produces Web to Exclude Competitors
Renato A. Sarmento, Felipe Lemos, Cleide R. Dias, Wagner T. Kikuchi, Jean C. P. Rodrigues, Angelo Pallini, Maurice W. Sabelis, Arne Janssen
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023757
Abstract: Herbivores may interact with each other through resource competition, but also through their impact on plant defence. We recently found that the spider mite Tetranychus evansi down-regulates plant defences in tomato plants, resulting in higher rates of oviposition and population growth on previously attacked than on unattacked leaves. The danger of such down-regulation is that attacked plants could become a more profitable resource for heterospecific competitors, such as the two-spotted spider mite Tetranychus urticae. Indeed, T. urticae had an almost 2-fold higher rate of oviposition on leaf discs on which T. evansi had fed previously. In contrast, induction of direct plant defences by T. urticae resulted in decreased oviposition by T. evansi. Hence, both herbivores affect each other through induced plant responses. However, when populations of T. evansi and T. urticae competed on the same plants, populations of the latter invariably went extinct, whereas T. evansi was not significantly affected by the presence of its competitor. This suggests that T. evansi can somehow prevent its competitor from benefiting from the down-regulated plant defence, perhaps by covering it with a profuse web. Indeed, we found that T. urticae had difficulties reaching the leaf surface to feed when the leaf was covered with web produced by T. evansi. Furthermore, T. evansi produced more web when exposed to damage or other cues associated with T. urticae. We suggest that the silken web produced by T. evansi serves to prevent competitors from profiting from down-regulated plant defences.
Seletividade de herbicidas pré-emergentes ao pinh?o-manso (Jatropha curcas)
Rocha, P.R.R;Silva, A.F;Faria, A.T;Galon, L;Ferreira, E.A;Felipe, R.S;Silva, A.A;Dias, L.A.S;
Planta Daninha , 2010, DOI: 10.1590/S0100-83582010000400013
Abstract: in recent years, the areas cultivated with physic nut (jatropha curcas) have expanded in brazil, aiming at its use in biofuel production. however, one of the problems faced by the producers is the lack of studies on its tolerance to the herbicides registered in brazil. the objective of this work was to evaluate the tolerance of physic nut genotypes to herbicides applied at pre-emergence. the experiment was arranged in a randomized block design, with four replications, in a factorial design, 3 x 6. factor a was composed by the genotypes (filomena, gon?alo and paragua?u), and factor b by the herbicides (isoxaflutole, oxyfluorfen, sulfentrazone, pendimethalin and tebuthiuron), plus one non-treated control. intoxication by the herbicides was evaluated at 19, 32, 40, 48, 56 and 64 days after treatments (dat). height, leaf area, and plant dry matter were evaluated at 64 dat. it was verified that the jatropha genotypes have different tolerance to the herbicides studied. isoxaflutole and tebuthiuron caused severe injuries to all genotypes and negatively affected all the variables evaluated. on the other hand, oxyfluorfen and pendimethalin proved to be selective to the crop and should be evaluated in further studies to be recommended to the crop.
Crustal thickness beneath Rio de Janeiro, Brazil, from spectra of SH waves at station RDJ
Cario, Felipe Dias;Souza, Jorge Luis de;
Geofísica internacional , 2006,
Abstract: amplitude and phase spectra of long period analog s wave records were used to estimate crustal thickness under rio de janeiro seismic station. earthquakes with shallow focal depths (10-33 km) and epicentral distances varying from 83 to 88 degrees provided the best estimates of crustal thickness. epicentral distance seems to be the most important parameter in getting adequate amplitude and phase spectra. the estimated crustal thickness under rdj station is 32.9 ± 2.6 km. this value is compatible with an intraplate continent-ocean transition zone and with recent surface wave studies and crustal thickness determinations from receiver functions.
Crustal thickness beneath Rio de Janeiro, Brazil, from spectra of SH waves at station RDJ
Felipe Dias Cario,Jorge Luis de Souza
Geofísica internacional , 2006,
Abstract: Amplitude and phase spectra of long period analog S wave records were used to estimate crustal thickness under Rio de Janeiro seismic station. Earthquakes with shallow focal depths (10-33 km) and epicentral distances varying from 83 to 88 degrees provided the best estimates of crustal thickness. Epicentral distance seems to be the most important parameter in getting adequate amplitude and phase spectra. The estimated crustal thickness under RDJ station is 32.9 ± 2.6 km. This value is compatible with an intraplate continent-ocean transition zone and with recent surface wave studies and crustal thickness determinations from receiver functions.
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