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Search Results: 1 - 10 of 23814 matches for " Ricardo;Monteiro "
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Classical and thermodynamic stability of black holes
Ricardo Monteiro
Physics , 2010,
Abstract: We consider the stability of black holes within both classical general relativity and the semiclassical thermodynamic description. In particular, we study linearised perturbations and their contribution to the gravitational partition function, addressing technical issues for charged (Reissner-Nordstrom) and rotating (Kerr-AdS) black holes. Exploring the connection between classical and thermodynamic stability, we find classical instabilities of Myers-Perry black holes and bifurcations to new black hole families.
Tratamento n?o-operatório do trauma hepático
Rasslan, Samir;Monteiro, Ricardo Portieri;
Revista do Colégio Brasileiro de Cirurgi?es , 1999, DOI: 10.1590/S0100-69911999000600011
Abstract: the liver is the most common organ damaged in abdominal trauma. frequently, the cellotomy reveals a minor hepatic lesion with no signs of active bleeding. and the surgeon quite often finish the procedure with simply cleaning and drainage of the abdominal cavity. due to the above mentioned aspects, the nonoperative management appears to be a reasonable option. actually, such initial approach represents the treatment of choice in victims of blunt trauma with hepatic injuries that reach the hospital with normal levell of conscience and hemodynamic stability. authors in this article, make a review and discuss the pattern selection's criteria, morbidity and mortality of the nonoperative management of blunt hepatic trauma.
Sample design in marine meiofauna Desenho amostral em meiofauna marinha
Luciana Monteiro Lage,Ricardo Coutinho
Vértices , 2010,
Abstract: Human activities on coastal marine biota have led to discussions of appropriate sampling protocols, so that the various studies can be compared. Most sampling methods produced for meiofauna, contemplates the sedimentary environment. However, it is known that meiofauna can inhabit any substrate in the marine environment. Meiofauna is recognized as a good tool for studies of environmental quality and marine ecological processes. The use of experimental studies can increase understanding of the mechanisms of dispersal and colonization of meiofauna and their ecological processes. As atividades humanas litoraneas sobre a biota marinha têm levado a discuss es sobre protocolos de amostragem adequados, de forma que os vários estudos possam ser comparados. A maior parte dos métodos de amostragem produzidos para a meiofauna, comtempla o ambiente sedimentar. Porém, é conhecido que a meiofauna pode habitar qualquer substrato no meio marinho, sendo reconhecida como boa ferramenta para estudos de qualidade ambiental e processos ecológicos marinhos. A utiliza o de estudos experimentais pode elevar a compreens o dos mecanismos de dispers o e coloniza o da meiofauna, bem como seus processos ecológicos.
Negative modes and the thermodynamics of Reissner-Nordstr?m black holes
Ricardo Monteiro,Jorge E. Santos
Physics , 2008, DOI: 10.1103/PhysRevD.79.064006
Abstract: We analyse the problem of negative modes of the Euclidean section of the Reissner-Nordstr\"om black hole in four dimensions. We find analytically that a negative mode disappears when the specific heat at constant charge becomes positive. The sector of perturbations analysed here is included in the canonical partition function of the magnetically charged black hole. The result obeys the usual rule that the partition function is only well-defined when there is local thermodynamical equilibrium. We point out the difficulty in quantising Einstein-Maxwell theory, where the so-called conformal factor problem is considerably more intricate. Our method, inspired by hep-th/0608001, allows us to decouple the divergent gauge volume and treat the metric perturbations sector in a gauge-invariant way.
Microstructural and Mechanical Characterization after Thermomechanical Treatments in 6063 Aluminum Alloy  [PDF]
Waldemar A. Monteiro, Iara M. Espósito, Ricardo B. Ferrari, Sidnei J. Buso
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.211206
Abstract: The aim of this work is the mechanical and microstructural characterization by optical and electron microscopy as well as microhardness of Al 6063 alloy after mechanical and thermal treatment. Al-Mg based alloys have special attention due to the lightness of the material and certain mechanical properties and recyclability. Such alloys produce good mechanical properties in moderate mechanical efforts (up to 700 MPa) and good resistance to the corrosion. Cold rolling steps (30%, 60% and 90% in area reduction) in Al 6063 alloy were employed for the recrystallization studies, followed by thermal treatment using four isothermal heating (423K, 523K, 623K and 723K) during 1800, 3600, 5400 and 7200s. The direct observation and chemical microanalysis were made in a JEOL200C and JEOL2010 transmission electron microscopes combined with mechanical characterization utilizing Vickers microhardness measurements. Normally classified as non-heat-treatable these alloys obtain higher strength either by strain-hardening or by solid solution. The nucleation of new grains is a non stability of the deformed microstructure, depending on subgrain size heterogeneities present as potential embryos in the deformed state adjacent to high local misorientation. The results indicate a significant effect of second-phase particles on recrystallization and how to control the resulting microstructure and texture by the use of particles. It may be a preferential growth in the early stage due to their local environment or a selection of certain orientations from among those produced by particles stimulated nucleation or a preferential nucleation at particles in favored sites such as grain boundaries.
Complex interactions envolving a gall midge Myrciamyia maricaensis Maia (Diptera, Cecidomyiidae), phytophagous modifiers and parasitoids
Ferraz, Fernando Fortunato Faria;Monteiro, Ricardo Ferreira;
Revista Brasileira de Zoologia , 2003, DOI: 10.1590/S0101-81752003000300011
Abstract: myrciamyia maricaensis maia, 1995 (diptera, cecidomyiidae) induces a gall in lateral and apical shoots in the plant myrcia lundiana kiaersk (myrtaceae) which is used and modified by two eulophid wasps species. in both cases the gall former species suffer high rate of attack exceeding the importance of parasitoid species as mortality factors. in this study these interactions are described and their effects as mortality of gall former. the intensity of occurrence of the two eulophid species as modifiers and of microhymenopteran parasitoids, and the relative importance of these species as mortality agents of the m. maricaensis larvae is compared. this comparison reveals that two modifiers species found in the gall tissue modification causing the death of the m. maricaensis larva and it is a more important factor of mortality than the cecidomyiid larva parasitism. the fluctuation of the number of each type of gall along the year was monitored in the research field and confirmed in numerical and in synchronic terms of occurrence of the galls; the importance of the species of the gall modifier eulophids, particularly one of these species, as factors of mortality of the m. maricaensis larvae and justified our comparing the relationship between these species and m. maricaensis as similar to the parasitoid-host relationship. the gall shape modification by one of the eulophids allows the occurrence of other inquiline insect species, what means that this gall modification becomes it more heterogeneous and allows the increase of the species richness to the system.
A new Sigelgaita Heinrich (Lepidoptera, Pyralidae, Phycitinae) feeding on cacti in Brazil
Monteiro, Ricardo F.;Becker, Vitor O.;
Revista Brasileira de Zoologia , 2002, DOI: 10.1590/S0101-81752002000500023
Abstract: description and biological aspects of a new species of sigelgaita heinrich, 1939, the first known to occur east of the andes, s. cerei becker, are presented. s. cerei larvae were collected on "restinga" ecosystems feeding on pilosocereus arrabidae (lem.) byles & rowl. (parque nacional da restinga de jurubatiba-macaé and área de prote??o ambiental de barra de marica, rio de janeiro) and rarely on cereus obtusus haw. (pnrj). life cycle and behavior of larvae are presented. larvae are found singly on flower buds, on fruit or more frequently on stem of the plants. they build chambers in the cladodium where they complete their larval development, then droping to the ground in order to pupate. trichogramma sp. was parasitizing 72% of eggs and a species of braconid was parasitizing half out of ten larvae collected from fruits of cereus obtusus. s. cerei larvae develop a special role in the colonization and establishment of a diverse fauna associates with the hosts such as insects, spiders and yeasts. ants, such as camponotus crassus mayr, 1862 and c. cingulatus mayr, 1862 are among the insects which most frequently nest in the chambers abandoned by the larvae of this moth species.
Espécies cecidógenas (Diptera, Cecidomyiidae) e parasitóides (Hymenoptera) associadas a Guapira opposita (Vell.) Reitz: (Nyctaginaceae) na Restinga da Barra de Maricá, Rio de Janeiro
Maia, Valéria Cid;Monteiro, Ricardo F;
Revista Brasileira de Zoologia , 1999, DOI: 10.1590/S0101-81751999000200013
Abstract: three different galls of bruggmannia spp. (diptera, cecidomyiidae) on guapira opposita (vell.) reitz. (nyctaginaceae) were studied at restinga of barra de maricá, state of rio de janeiro. thirty parasitoid species are associated to these galls. most of them is generalist and solitary. hyperparasitoidism is common. the trophic relations among gall makers and parasitoids are presented.
Complex interactions envolving a gall midge Myrciamyia maricaensis Maia (Diptera, Cecidomyiidae), phytophagous modifiers and parasitoids
Ferraz Fernando Fortunato Faria,Monteiro Ricardo Ferreira
Revista Brasileira de Zoologia , 2003,
Abstract: Myrciamyia maricaensis Maia, 1995 (Diptera, Cecidomyiidae) induces a gall in lateral and apical shoots in the plant Myrcia lundiana Kiaersk (Myrtaceae) which is used and modified by two eulophid wasps species. In both cases the gall former species suffer high rate of attack exceeding the importance of parasitoid species as mortality factors. In this study these interactions are described and their effects as mortality of gall former. The intensity of occurrence of the two eulophid species as modifiers and of microhymenopteran parasitoids, and the relative importance of these species as mortality agents of the M. maricaensis larvae is compared. This comparison reveals that two modifiers species found in the gall tissue modification causing the death of the M. maricaensis larva and it is a more important factor of mortality than the cecidomyiid larva parasitism. The fluctuation of the number of each type of gall along the year was monitored in the research field and confirmed in numerical and in synchronic terms of occurrence of the galls; the importance of the species of the gall modifier eulophids, particularly one of these species, as factors of mortality of the M. maricaensis larvae and justified our comparing the relationship between these species and M. maricaensis as similar to the parasitoid-host relationship. The gall shape modification by one of the eulophids allows the occurrence of other inquiline insect species, what means that this gall modification becomes it more heterogeneous and allows the increase of the species richness to the system.
ATIVIDADE ECOTURíSTICA E DINAMIZA O DA ECONOMIA EM CACHOEIRA GRANDE
Bruno Ricardo Monteiro Alcantara,Karla Sousa Pereira
Revista Brasileira de Ecoturismo , 2011,
Abstract: O município de Cachoeira Grande está localizado na Mesorregi o Norte Maranhense, possuindo uma popula o predominantemente rural. Estando assentado na Forma o geológica Itapecuru, o município de Cachoeira Grande apresenta solos com limita es para o desenvolvimento de práticas agrícolas, o que implica em reflexos sociais e econ micos para a popula o, já que a dinamica econ mica da regi o ocorre em fun o dessas atividades. A agricultura se desenvolveu historicamente na regi o porque esteve associada ao cultivo de espécies altamente eficiente no aproveitamento dos nutrientes (mandioca, feij o e melancia) por meio da associa o com microorganismos (fungos VAM e bactérias diazotróficas) e porque foi mantida basicamente pela matéria organica produzida pela própria vegeta o a partir da ciclagem de nutrientes. Essas práticas que antes se mostravam eficientes do ponto de vista ambiental e de sustenta o de produtividade vem se mostrando problemática diante de um aumento na densidade populacional e de uma redu o das áreas cultiváveis. Neste sentido, a dinamica econ mica do município de Cachoeira Grande, evidenciando diversos problemas ambientais especialmente nas áreas de matas ciliares, demanda diversas atividades mitigadoras que v o desde a educa o ambiental até a oferta de atividades que sejam mais racionais no uso dos recursos, unindo a gera o de renda com a manuten o dos frágeis ecossistemas que est o assentados sobre a base física do território de Cachoeira Grande. Apesar dos solos de Cachoeira Grande serem quimicamente pobres e altamente susceptíveis aos processos erosivos e da vegeta o estar imensamente degradada em fun o da agricultura, o município apresenta paisagens naturais exuberantes que podem ser utilizadas racionalmente pelo turismo, especialmente pelo ecoturismo. Os LATOSSOLOS formados por sedimentos oriundos de arenitos abrigam diversas paleodunas entremeadas de corpos de riachos e rios (a exemplo do Pirangi) de águas límpidas e extremamente frias. Características similares têm atraído em outros municípios visinhos enorme fluxo de turistas, dinamizando suas economias. Apesar da proximidade, Cachoeira Grande é pouco conhecida entre os habitantes de S o Luís. Tal situa o pode ser exemplificada pela presen a constante de visitantes no município de Morros, apesar da pequena distancia entre um município e outro e de possuir lugares com uma maior qualidade ambiental. Mas a aplica o do Ecoturismo está condicionado a diversos fatores, principalmente na implanta o de uma gest o voltada para o ecoturismo, que priorizasse o preparo dos morador
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