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Search Results: 1 - 10 of 469161 matches for " Leonardo S. G.;Brasileiro "
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Determina??o espectrofotométrica simultanea de cobre e ferro em álcool etílico combustível com reagentes derivados da ferroína
Teixeira, Leonardo S. G.;Brasileiro, Jo?o F.;Borges Jr., Mário M.;Cordeiro, Paulo W. L.;Rocha, Sarah A. N.;Costa, Antonio C. Spínola;
Química Nova , 2006, DOI: 10.1590/S0100-40422006000400020
Abstract: in the present work three ferroin reagents were studied for the simultaneous spectrophotometric determination of iron and copper: 1,10-phenanthroline, 2,2'-bipyridine and 2,4,6-tri(2-pyridyl)-1,3,5-triazine. effect of ph, conditions, order reagent addition, interferences, amount of reagents, lineal range, sensitivity and stability of each system were compared. the 2,4,6-tri(2-pyridyl)-1,3,5-triazine can be used for determination of iron in the presence of copper with a detection limit of 5 μg l-1 and coefficient of variation of 2.0%; however it was not possible to determine directly copper in the presence of iron with this reagent. 1,10-phenanthroline can be used for simultaneous determination of the metallic ions with detection limits of 7 and 8 mg l-1 and coefficients of variation of 1.8 and 2.3% in the determination of iron and copper, respectively. the results showed also that 2,2'-bipyridine can be used for simultaneous determination of the metallic ions with detection limits of 11 and 32 μg l-1 and coefficients of variation of 1.9 and 2.5% in the determination of iron and copper, respectively. the reagents were used for spectrophotometric determination of iron and copper in ethanol fuel.
Rhodolith Beds Are Major CaCO3 Bio-Factories in the Tropical South West Atlantic
Gilberto M. Amado-Filho, Rodrigo L. Moura, Alex C. Bastos, Leonardo T. Salgado, Paulo Y. Sumida, Arthur Z. Guth, Ronaldo B. Francini-Filho, Guilherme H. Pereira-Filho, Douglas P. Abrantes, Poliana S. Brasileiro, Ricardo G. Bahia, Rachel N. Leal, Les Kaufman, Joanie A. Kleypas, Marcos Farina, Fabiano L. Thompson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035171
Abstract: Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (<150 m depth) subjected to episodic disturbance. Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N - 27°S). To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50′ - 19°45′S) off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km2. Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO3 production was estimated from in situ growth assays at 1.07 kg m?2 yr?1, with a total production rate of 0.025 Gt yr?1, comparable to those of the world's largest biogenic CaCO3 deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades.
Amphibia, Anura, Hylidae, Bokermannohyla izecksohni: Distribution extension
Toledo, L. F.,Brasileiro, C. A.,Araújo, O. G. S.,Haddad, C. F. B.
Check List , 2008,
Abstract:
Rhodolith bed structure along a depth gradient on the northern coast of bahia state, brazil
Bahia, Ricardo G.;Abrantes, Douglas P.;Brasileiro, Poliana S.;Pereira Filho, Guilherme H.;Amado Filho, Gilberto M.;
Brazilian Journal of Oceanography , 2010, DOI: 10.1590/S1679-87592010000400007
Abstract: the aim of this study was to determine the structure of a rhodolith bed along a depth gradient of 5 to 25 m in the shelf in front of salvador city, a region of northeastern brazil. the dimensions, morphology and coralline algae composition of the rhodoliths were analyzed, as well as the vitality, density, and associated flora of the bed at three depths: 5, 15 and 25 m. samples were obtained by scuba divers in summer 2007. five rhodolith-forming taxa were identified: sporolithon episporum, lithothamnion brasiliense, lithothamnion superpositum, mesophyllum erubescens, and lithophyllum sp. the encrusting growth form and the spherical shape were predominant at all depths. rhodolith dimensions and vitality decreased and the density increased from the shallow to the deepest zones. fifty-six macroalgal species were found as rhodolith-associated flora. the shallower depth presented higher values for macroalgal biomass and number of species. these results associated with other recent rhodolith bed descriptions indicate that the pattern of brazilian rhodolith bed structure along depth gradients may be related to a combination of the extent and slope of the continental shelf.
La di-gestión de energías en los Call Centers: entre cuerpos des-hechos y perfomances del liderazgo
Landa,María Inés; Marengo,Leonardo G.;
Trabajo y sociedad , 2012,
Abstract: in this article we propose the study, from a "social body perspective", of the socio-productive universe of call centers, focusing on the dynamics of human energy metabolism that is produced in this emerging field. consequently, we have organized the argumentation strategy in two moments: firstly, we present the conceptual framework chosen for the analysis of a particular case: the telephone company movistar in argentina. secondly, we describe the diferential energy dispositions, physical and social, that reveal the agents' framework of the call center object of study: telephone operator, client, company and leaders. we conclude that the energy management model in call centers implements an original and specific model of selection and use of working bodies. paradoxically, in the analyzed business scenes the main technological innovation is not a machine but a human technology, a body performance.
La di-gestión de energías en los Call Centers: entre cuerpos des-hechos y perfomances del liderazgo The Energy Absorption in Call Centers: Between Wrecked Bodies and Leadership Performance
María Inés Landa,Leonardo G. Marengo
Trabajo y sociedad , 2012,
Abstract: El artículo propone un estudio "en clave corporal" del universo socioproductivo de los Call Centers, centrando la mirada en la dinámica de metabolización de energías humanas que en dicho campo emergente se produce. En función de ello, se ha organizado la estrategia argumentativa en dos momentos: En primer lugar, se presenta el marco conceptual escogido para el análisis de un caso concreto: la empresa Movistar en Argentina. En segundo lugar, se describen las disposiciones energéticas diferenciales, corporales y sociales, que revela el cuadro de agentes del Call Center estudiado: teleoperador, cliente, empresa y líderes. Se concluye que el modelo de gestión de energías en los Call Centers implementa un esquema de selección y uso de los cuerpos-trabajadores original y específico. Paradójicamente, en los escenarios empresariales analizados la principal innovación tecnológica no es una máquina, sino una tecnología humana, una perfomance corporal. In this article we propose the study, from a "social body perspective", of the socio-productive universe of Call Centers, focusing on the dynamics of human energy metabolism that is produced in this emerging field. Consequently, we have organized the argumentation strategy in two moments: Firstly, we present the conceptual framework chosen for the analysis of a particular case: the telephone company Movistar in Argentina. Secondly, we describe the diferential energy dispositions, physical and social, that reveal the agents' framework of the Call Center object of study: telephone operator, client, company and leaders. We conclude that the energy management model in Call Centers implements an original and specific model of selection and use of working bodies. Paradoxically, in the analyzed business scenes the main technological innovation is not a machine but a human technology, a body performance.
Relaciones de potencia en condiciones no sinusoidales
Torres S. Horacio,Barreto G. Leonardo
Ingeniería e Investigación , 1996,
Abstract: Este artículo presenta algunas consideraciones con respecto al flujo de potencia cuando existen armónicos de tensión y/o corriente en el sistema de distribución. Se enfatiza el hecho de que las relaciones de potencia reactiva clásica definidas para el caso sinusoidal dejan de ser válidas y que la descomposición espectral de la potencia instantánea puede contribuir a establecer, comprender e interpretar las componentes de la potencia.
Utilization of microsatellites for the analysis of genomic alterations in colorectal cancers in Brazil
Fuzikawa, A.K.;Haddad, L.A.;da-Cunha-Melo, J.R.;Brasileiro-Filho, G.;Pena, S.D.J.;
Brazilian Journal of Medical and Biological Research , 1997, DOI: 10.1590/S0100-879X1997000800001
Abstract: two different pathogenetic mechanisms are proposed for colorectal cancers. one, the so-called "classic pathway", is the most common and depends on multiple additive mutational events (germline and/or somatic) in tumor suppressor genes and oncogenes, frequently involving chromosomal deletions in key genomic regions. methodologically this pathway is recognizable by the phenomenon of loss of heterozygosity. on the other hand, the "mutator pathway" depends on early mutational loss of the mismatch repair system (germline and/or somatic) leading to accelerated accumulation of gene mutations in critical target genes and progression to malignancy. methodologically this second pathway is recognizable by the phenomenon of microsatellite instability. the distinction between these pathways seems to be more than academic since there is evidence that the tumors emerging from the mutator pathway have a better prognosis. we report here a very simple methodology based on a set of tri-, tetra- and pentanucleotide repeat microsatellites allowing the simultaneous study of microsatellite instability and loss of heterozygosity which could allocate 70% of the colorectal tumors to the classic or the mutator pathway. the ease of execution of the methodology makes it suitable for routine clinical typing
Estratégias para aumento de sensibilidade em espectrofotometria UV-VIS
Rocha, Fábio R. P.;Teixeira, Leonardo S. G.;
Química Nova , 2004, DOI: 10.1590/S0100-40422004000500021
Abstract: spectrophotometry is one of the most widespread analytical techniques due to its simplicity, reliability, and low-cost instrumentation for both direct measurements and coupled to other techniques or processes such as chromatography, electrophoresis and flow analysis. however, the application is often limited by sensitivity. this article describes some advances that greatly improve the performance of spectrophotometric measurements, especially in order to increase sensitivity, including the employment of liquid-core waveguides and solid-phase spectrophotometry.
DESIGNING A RADIO-INTERFEROMETRIC ARRAY OF YAGI-UDA ANTENNAS WITH SPECTRAL WINDOW CENTRE AT 400 MHZ
Mu?oz S.,ángel G.; Hernández V.,Leonardo;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2003,
Abstract: abstract it is well known that the observation of celestial bodies through the use of radioastronomic devices has, generally speaking, important advantages in comparison to traditional studies concerning the visual spectrum. moreover, radio-interferometry gives additional advantages to the device, such as the enhancement of the signal receptor effective area, higher gaining and better array directivity. despite the number of experimental details, the design of a radio-telescope made up of an array of antennas whose radiation fields interfere among themselves does not involve excessive theoretical complications, in particular if yagi-uda antennas are used. the authors describe in this paper the designing and characteristics of a radio-interferometric array with mills cross symmetry, 4x4 twelve elements yagi-uda antennas, set to 400 mhz. finally, the potential of the array is briefly analysed in order to be used for radio-heliographics studies.
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