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Search Results: 1 - 10 of 435643 matches for " Efrem J. G.; "
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Two new species of Apistogramma Regan (Teleostei: Cichlidae) from the rio Trombetas, Pará State, Brazil
Kullander, Sven O;Ferreira, Efrem J. G.;
Neotropical Ichthyology , 2005, DOI: 10.1590/S1679-62252005000300003
Abstract: apistogramma angayuara is described from the rio trombetas close to the cachoeira vira mundo where it is found in association with rapids. it is assigned to the a. pertensis species group, distinguished by the following characters in combination: three prominent stripes composed of dark spots along the sides of the abdomen, 2 vs. 3 postlachrymal infraorbital pores, 5 vs. 4 dentary pores, low dorsal fin in adult males, and presence of a caudal spot. it is the smallest species of apistogramma reported so far, with the largest male 24.7 mm sl and the largest female 22.7 mm sl, and the first cichlid species found with a significant proportion of rhizopods in the stomach content. apistogramma salpinction is described from lentic habitats at the margin of road br-163, circa 70 km from cachoeira porteira village, in a swamp most probably connected to the igarapé caxipacoré. it is compared to members of the apistogramma cacatuoides group with which it shares prolonged anterior dorsal fin lappets and marginal caudal fin streamers in adult males. it is distinguished from all other species of apistogramma by the color pattern which includes a lateral band and abdominal stripes that become darker and have much lighter interspaces on the caudal peduncle, and a caudal spot that is divided into elongated blotches continuing the lateral band and upper two abdominal stripes, respectively.
Spawning areas, dispersion and microhabitats of fish larvae in the Anavilhanas Ecological Station, rio Negro, Amazonas State, Brazil
Oliveira, Edinbergh C. de;Ferreira, Efrem J. G.;
Neotropical Ichthyology , 2008, DOI: 10.1590/S1679-62252008000400003
Abstract: the abundance and distribution of ichthyoplankton and their relationships to current velocity, temperature, dissolved oxygen, ph and electrical conductivity of the water in the anavilhanas ecological station, negro river, amazonas state, brazil, were analyzed. preferred microhabitats for spawning, dispersion and nursery were also verified. sampling was undertaken during the falling water period of 2001 and the rising water period of 2002, in a section of 100 km subdivided into 5 subsections, with a total of 20 stations (5 beaches, 5 ravines, 5 channels, and 5 lake channels) at night and during the day at the surface and at the bottom. 647 eggs and 4,187 larvae were captured, belonging to 10 families and four orders: characiformes (6), siluriformes (2), perciformes (1), and clupeiformes (1). engraulidae (55.39%), pimelodidae (30.45%), auchenipteridae (5.23%) and sciaenidae (5.13%) were the dominant families. the hierarchical statistical model (anova) with three factors (microhabitat, depth and period) was applied to the environmental variables and the larval abundance, showing greater abundances of sciaenids in the ravines and lower abundances of engraulids in the channels. the highest captures were obtained at lower temperature values, at the bottom during the day and at the surface at night, suggesting an active larval behavior. the presence of the four larval development stages in all subsection for pimelodids and sciaenids, and in three subsections for engraulids, indicates that the anavilhanas ecological station is an important spawning and nursery area for species of these groups in the negro river. larvae abundance of all characiform families was extremely low (from 0.1 to 1.17%), suggesting that they do not spawn in this system.
Patterns of energy allocation to reproduction in three Amazonian fish species
Santos, Rodrigo N. dos;Amadio, Sidinéia;Ferreira, Efrem J. G.;
Neotropical Ichthyology , 2010, DOI: 10.1590/S1679-62252010005000001
Abstract: the study considered the influence of the hydrological cycle and gonadal development on the accumulation and use of energy in three fish species from an amazonian flooded area. fishes were sampled over a 24 hour period at monthly intervals between july 2004 and june 2005 using gillnets of different mesh sizes. body cavity fat and gonadosomatic indices were determined, as well as energy content of gonads and muscles. amongst the studied species, different means of energy allocation for reproduction were found: acestrorhynchus falcirostris allocate energy from body cavity fat to its gonads; pygocentrus nattereri uses mainly energy accumulated in the muscles for the process of gonadal maturation; and hoplosternum littorale uses energy accumulated in their muscles and body cavity fat for reproductive processes. it is quite clear that the flood pulse regulates the gain and use of the energy reserves in fishes from the amazonian floodplain.
Diet of Bryconops alburnoides and B. caudomaculatus (Osteichthyes: Characiformes) in the region affected by Balbina Hydroelectric Dam (Amazon drainage, Brazil)
Silva, Cylene C. da;Ferreira, Efrem J. G.;Deus, Cláudia P. de;
Neotropical Ichthyology , 2008, DOI: 10.1590/S1679-62252008000200011
Abstract: the study of fish diet and its interaction with the environment provides important data on ecology and behavior, as fish face varying environmental and food availability conditions. the aim of the present study was to determine the diet of bryconops caudomaculatus and bryconops alburnoides, as well as to assess its seasonal variation, within the area influenced by balbina hydroelectric dam (bhd), in the uatum? river (amazon basin, brazil). collections were carried out every two months from april 2005 to february 2007, using gill nets with mesh sizes ranging from 12 to 60 mm between opposite knots. two methods were used for determining diet: frequency of occurrence and relative volume, which were used to calculate the alimentary index (iai). diet similarity between species was analyzed by applying the morisita index. bryconops alburnoides ingested 12 items and b. caudomaculatus 10, with a 59% similarity between ingested items. terrestrial insects for b. alburnoides and immature insects for b. caudomaculatus were the main items in their diets, and therefore, they were considered insectivorous. the seasonal composition of the diet of b. alburnoides was influenced by environmental factors, and in spite of the dominance of immature insects, it had a significant number of terrestrial insects during the heavy rainfall periods.
Dieta de cinco espécies de Hemiodontidae (Teleostei, Characiformes) na área de influência do reservatório de Balbina, rio Uatum?, Amazonas, Brasil
Silva, Cylene C. da;Ferreira, Efrem J. G.;Deus, Cláudia P. de;
Iheringia. Série Zoologia , 2008, DOI: 10.1590/S0073-47212008000400008
Abstract: the diet of five species of hemiodontidae (hemiodus argenteus (pellegrin, 1908), h. atranalis (fowler, 1940), h. immaculatus (kner, 1858), h. microlepis (kner, 1858) e h. unimaculatus (bloch, 1794)) from the area of influence of the balbina reservoir, uatum? river, northern brazil, was investigated. fish were collected bimonthly from april 2005 to february 2007 in four places, two in the reservoir (upstream the dam) and two in the river (downstream the dam). a total of 318 stomachs were analyzed. the diet was evaluated using two methods: frequency of occurrence and relative volume, both combined in the alimentary index (iai). the breadth of the alimentary niche was low among the five analyzed species. hemiodus unimaculatus presented the largest niche breadth, while h. argenteus showed the smallest. detritus was an important item in the diet of all species, being predominant in hemiodus argenteus, h. microlepis and h. unimaculatus. hemiodus atranalis ingested mainly microcrustaceans and h. immaculatus consumed a larger proportion of vegetables. despite the consumption of certain preferential items the ingestion of a wide variety of items occurs for all the species showing a broad trophic diversity in the diet of this family, which could explain its relative success in reservoirs in the amazon.
Divergência genética em acessos de quiabeiro com base em marcadores morfológicos
Martinello Gilmar Efrem,Leal Nilton R.,Amaral Júnior Ant?nio T.,Pereira Messias G.
Horticultura Brasileira , 2002,
Abstract: Vinte e sete caracteres morfoagron micos, 13 quantitativos e 14 qualitativos, foram utilizados para a avalia o da diversidade genética em 39 acessos do gênero Abelmoschus, por meio das análises de agrupamento hierárquico do vizinho mais próximo e de componentes principais, utilizando-se a distancia Euclidiana média padronizada como medida de dissimilaridade. As plantas foram cultivadas em condi es de campo na Universidade Estadual do Norte Fluminense, em Campos dos Goytacazes, utilizando-se o delineamento experimental em blocos ao acaso com quatro repeti es. A forma o dos grupos de acessos, com base no método hierárquico do vizinho mais próximo, revelou resultados semelhantes aos obtidos pela análise em componentes principais, já que ambos os métodos reuniram os acessos de A. esculentus e A. caillei. O método hierárquico agrupou os genótipos de forma idêntica tanto para os 27 descritores quantitativos e qualitativos quanto para os 13 descritores quantitativos separadamente, demonstrando que os descritores qualitativos tiveram pouca influência na discrimina o genotípica. Por outro lado, os descritores qualitativos foram capazes de classificar corretamente as espécies, porém mascararam a variabilidade genética no germoplasma, n o possibilitando um rastreamento mais abrangente dos genomas. Os descritores que menos contribuíram para a discrimina o dos acessos foram, largura do epicálice, peso de 100 sementes, número de segmentos do estigma, altura da planta, comprimento da folha, largura da folha, nó do primeiro florescimento e comprimento do fruto.
Patterns of energy allocation to reproduction in three Amazonian fish species
Rodrigo N. dos Santos,Sidinéia Amadio,Efrem J. G. Ferreira
Neotropical Ichthyology , 2010,
Abstract: The study considered the influence of the hydrological cycle and gonadal development on the accumulation and use of energy in three fish species from an Amazonian flooded area. Fishes were sampled over a 24 hour period at monthly intervals between July 2004 and June 2005 using gillnets of different mesh sizes. Body cavity fat and gonadosomatic indices were determined, as well as energy content of gonads and muscles. Amongst the studied species, different means of energy allocation for reproduction were found: Acestrorhynchus falcirostris allocate energy from body cavity fat to its gonads; Pygocentrus nattereri uses mainly energy accumulated in the muscles for the process of gonadal maturation; and Hoplosternum littorale uses energy accumulated in their muscles and body cavity fat for reproductive processes. It is quite clear that the flood pulse regulates the gain and use of the energy reserves in fishes from the Amazonian floodplain. O presente estudo considerou a influência do ciclo hidrológico e matura o gonadal no acúmulo e utiliza o da energia em três espécies de peixes, numa área de planície de inunda o amaz nica. As amostras foram obtidas mensalmente durante o período de julho de 2004 a junho de 2005, utilizando redes de emalhar com vários tamanhos de malhas, durante 24 horas. O índice de gordura cavitária, índice gonadossomático, e teor energético dos músculos e g nadas foram analisados. Dentre as espécies analisadas, foram detectados diferentes padr es de aloca o de energia: Acestrorhynchus falcirostris aloca energia das reservas de gordura cavitária para as g nadas; Pygocentrus nattereri utiliza energia dos músculos para este fim e Hoplosternum littorale, além da gordura cavitária, utiliza também energia acumulada nos músculos para realiza o dos processos reprodutivos. Ficou evidente que o pulso de inunda o exerce forte influência no acúmulo e utiliza o das reservas energéticas dos peixes da planície de inunda o amaz nica.
Divergência genética em acessos de quiabeiro com base em marcadores morfológicos
Martinello, Gilmar Efrem;Leal, Nilton R.;Amaral Júnior, Ant?nio T.;Pereira, Messias G.;Daher, Rogério F.;
Horticultura Brasileira , 2002, DOI: 10.1590/S0102-05362002000100010
Abstract: twenty-seven morphological characteristics (13 quantitative and 14 qualitative) were used to evaluate the genetic diversity of 39 abelmoschus accessions by hierarchic method of single linkage and principal component analysis for the grouping of the genotypes. standardized average euclidean distance was used as dissimilarity measure. plants were grown in field conditions at the universidade estadual do norte fluminense, in campos dos goytacazes, brazil, using randomized complete blocks design with four replications. the accessions groups formation based on the hierarchic method of single linkage showed similar results to those obtained by principal components analysis since both methods grouped a. esculentus and a. caillei accessions. the hierarchic method has grouped the genotypes in the same way as for the 27 descriptors (quantitative and qualitative) as for the 13 quantitative descriptors, demonstrating that qualitative descriptors had a little influence on the genotypic discrimination. qualitative descriptors were able to correctly classify species, although they masked the genetic variability at the germplasm, not allowing a comprehensive survey of the genomes. the characters that less contributed for the genotypes discriminations were the epicalyx length, 100 seeds weight, number of stigma segments, plant height, leaf width, first flowering node and fruit length.
Case 3
Efrem Mandelcorn
University of Toronto Medical Journal , 2002, DOI: 10.5015/utmj.v79i3.873
Abstract:
Structural and Magnetic Phase Transitions in MnTe-MnSe solid solutions
Kapil E. Ingle,J. B. C. Efrem D'Sa,A. Das,K. R. Priolkar
Physics , 2014, DOI: 10.1016/j.jmmm.2013.07.052
Abstract: Neutron diffraction studies as a function of temperature on solid solutions of MnSe and MnTe in the Se rich region are presented. Interestingly as Te is doped in MnSe, the structural transformation to NiAs phase diminishes, both in terms of \% fraction of compound as well as in terms of transition temperature. In MnTe$_{0.3}$Se$_{0.7}$, the NaCl to NiAs phase transformation occurs at about 40K and although it is present at room temperature in MnTe$_{0.5}$Se$_{0.5}$, its volume fraction is only about 10\% of the total volume of sample. The magnetic ordering temperature of the cubic phase decreases with increasing Te content while the hexagonal phase orders at the same temperature as in MnSe. Anomalies in thermal evolution of lattice parameters at magnetic ordering as well as structural transition temperatures indicate presence of magnetostructural coupling in these compounds.
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