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Search Results: 1 - 10 of 126657 matches for " Jo?o Renato;Lombardi "
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Antiviral activities of plants occurring in the state of Minas Gerais, Brazil: Part 2. Screening Bignoniaceae species
Brand?o, Geraldo Célio;Kroon, Erna G.;Santos, Joo Rodrigues dos;Stehmann, Joo Renato;Lombardi, Júlio A.;Oliveira, Alaíde Braga de;
Revista Brasileira de Farmacognosia , 2010, DOI: 10.1590/S0102-695X2010005000035
Abstract: ethanol extracts of eighteen bignoniaceae species have been evaluated by the mtt assay for cytotoxicity in vero cells and for antiviral activity against human herpes virus type 1, vaccinia virus and murine encephalomyocarditis virus. among such species, seven are reported to be of traditional medicinal use no cytotoxicity was observed for most of the extracts up to the concentration of 500 μg/ml. fourteen (50%) of the 28 extracts assayed have disclosed antiviral activity with ec50 values in the range of 4.6+0.3 to 377.2+17.7 μg/ml. only two species, arrabidaea samydoides and callichlamys latifolia, have shown activity against all the three viruses. the extracts were chemically characterized by their tlc and hplc-dad profiles. mangiferin is the major constituent of a. samydoides but the isolated compound has been less active than the crude extract. this is the first report on the antiviral evaluation of the eighteen bignoniaceae species assayed.
2MASS wide field extinction maps: V. Corona Australis
Joo Alves,Marco Lombardi,Charles Lada
Physics , 2014, DOI: 10.1051/0004-6361/201322159
Abstract: We present a near-infrared extinction map of a large region ($\sim$870 deg$^2$) covering the isolated Corona Australis complex of molecular clouds. We reach a 1-$\sigma$ error of 0.02 mag in the K-band extinction with a resolution of 3 arcmin over the entire map. We find that the Corona Australis cloud is about three times as large as revealed by previous CO and dust emission surveys. The cloud consists of a 45 pc long complex of filamentary structure from the well known star forming Western-end (the head, $N \geq10^{23}$ cm$^{-2}$) to the diffuse Eastern-end the tail, ($N \leq10^{21}$ cm$^{-2}$). Remarkably, about two thirds of the complex both in size and mass lie beneath A$_V\sim1$ mag. We find that the PDF of the cloud cannot be described by a single log-normal function. Similar to prior studies, we found a significant excess at high column densities, but a log-normal + power-law tail fit does not work well at low column densities. We show that at low column densities near the peak of the observed PDF, both the amplitude and shape of the PDF are dominated by noise in the extinction measurements making it impractical to derive the intrinsic cloud PDF below A$_K <$ 0.15 mag. Above A$_K \sim 0.15$ mag, essentially the molecular component of the cloud, the PDF appears to be best described by a power-law with index $-3$, but could also described as the tail of a broad and relatively low amplitude, log-normal PDF that peaks at very low column densities.
Biologia reprodutiva de Calibrachoa elegans (Miers) Stehmann & Semir (Solanaceae)
Brazilian Journal of Botany , 2001, DOI: 10.1590/S0100-84042001000100005
Abstract: calibrachoa elegans is an endemic annual species from the "canga" region in the iron quadrangle, minas gerais, brazil. the study of its reproductive biology involved cross-pollination experiments, self-incompatibility tests and observations of the pollination process. results of manual pollination experiments showed that the studied population is allogamous. interruption of pollen tube growth in the style of self-pollinated flowers confirmed the occurrence of self-incompatibility reactions. pollination is effected only by females of hexantheda missionica (colletinae, apoideae), which show high fidelity to flowers of c. elegans; males use the flowers as a nectar source, as stops between flights when searching for females, and as shelter during the night. they prepare the shelter by cutting and removing anthers and style. the populations of hexantheda missionica found in minas gerais are the first records of this species for southeastern brazil and probably represent remnants that reached this region during the past, but are now disjunct and isolated from those in southern brazil.
Biologia reprodutiva de Calibrachoa elegans (Miers) Stehmann & Semir (Solanaceae)
Brazilian Journal of Botany , 2001,
Abstract: Calibrachoa elegans é uma espécie anual, endêmica da regi o da canga do quadrilátero ferrífero de Minas Gerais, Brasil. O estudo da sua biologia reprodutiva envolveu experimentos de cruzamentos, teste do sistema de auto-incompatibilidade e observa o do processo de poliniza o. Os experimentos realizados através de poliniza es manuais indicam que a popula o estudada é preferencialmente alógama. A interrup o do crescimento do tubo polínico no estilete das flores autopolinizadas, verificada através da microscopia de fluorescência, confirmou a ocorrência de rea o de auto-incompatibilidade. A poliniza o é realizada apenas pelas fêmeas de Hexantheda missionica (Colletinae, Apoideae), uma abelha com alta fidelidade de visita às flores de C. elegans. Os machos desta espécie utilizam as flores como fonte de néctar, como local para pouso entre os v os de patrulhamento a procura de fêmeas para acasalamento e como abrigo noturno. Para se acomodarem na flor, geralmente cortam e removem os estames e o estilete. As popula es de Hexantheda missionica encontradas em Minas Gerais s o o primeiro registro da espécie para a regi o sudeste do Brasil e, provavelmente, representam remanescentes que chegaram a esta regi o no passado e que agora se encontram disjuntas e isoladas das popula es da regi o sul do Brasil.
Current diagnosis of occult or cryptic hepatitis B
Joo Renato Rebello Pinho
Einstein (S?o Paulo) , 2005,
Abstract: The present article presents a kind of hepatitis B in patients whodo not have the surface antigen (HbsAg) detectable in sera. It hasbeen described in different parts of the world and is known todayas “occult or criptic hepatitis B” and its importance has beenextensively discussed in the edical literature. Biological aspectsof the disease, its natural history, etiology and pathogenesis aredescribed. Occult hepatitis B virus infection has been found amongpatients with hepatitis C, HIV infection, hepatitis non A-E andhepatocellular carcinoma. The persistence of replication of thehepatitis B virus after acute hepatitis reinforces the need forscreening blood donators with anti-HBc and emphasizes theimportance of adoption of tests to detect nucleic acids in order toavoid the transmission of hepatitis B from seronegative blooddonors.
Hydrologic Monitoring Plan of the Brazilian Water Producer/PCJ Project  [PDF]
Denise Taffarello, Joo Guimar?es, Regiane Kock de Sousa Lombardi, Maria do Carmo Calijuri, Eduardo Mario Mendiondo
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.712152
Abstract: Both Ecosystem-based Adaptation (EbA) and Payment for Ecosystem Services (PES) have a wide range of strategies that include different economic instruments for nature conservation. Although the generation and maintenance of payment for hydrologic ecosystem services (Water-PES) is expanding in Brazil, there are difficulties in the implementation of projects. Due to the complexity and non-linearity of the hydrological processes, also affecting both EbA and Water-PES goals, monitoring quali-quantitative aspects of streams have been here addressed as a useful management tool. This study presents the Hydrological Monitoring Plan (HMP) of the Water Producer/PCJ project, operating between 2009-2014, in order to: 1) evaluate the impact of project actions under water quali-quantitative aspects; and 2) promote the incorporation of HMP’s elements in water resources management. HMP of the Water Producer/PCJ project has been implemented following the conditions for efficiency (baseline, long-term scale compatible with the actions of the project, in the experimental and reference watersheds). In addition, HMP is being implemented from upstream to downstream in catchments with areas ranging from 17 to 130 km2. This proposal favors the quantification and valuation of hydrologic services that could be assessed by ecohydrologic monitoring and modeling. Thus, we look forward to the consolidation of the Brazilian information system of water resources, the reduction of modeling uncertainties and integrated assessment of the consequences of land-use/land-cover change that strongly impact goals of EbA and Water-PES initiatives.
Fitting density models to observational data - The local Schmidt law in molecular clouds
Marco Lombardi,Charles J. Lada,Joo Alves
Physics , 2013, DOI: 10.1051/0004-6361/201321827
Abstract: We consider the general problem of fitting a parametric density model to discrete observations, taken to follow a non-homogeneous Poisson point process. This class of models is very common, and can be used to describe many astrophysical processes, including the distribution of protostars in molecular clouds. We give the expression for the likelihood of a given spatial density distribution of protostars and apply it to infer the most probable dependence of the protostellar surface density on the gas surface density. Finally, we apply this general technique to model the distribution of protostars in the Orion molecular cloud and robustly derive the local star formation scaling (Schmidt) law for a molecular cloud. We find that in this cloud the protostellar surface density, $\Sigma_\mathrm{YSO}$, is directly proportional to the square gas column density, here expressed as infrared extinction in the $K$-band, $A_K$: more precisely, $\Sigma_\mathrm{YSO} = (1.65 \pm 0.19) A_K^{(2.03 \pm 0.15)}$ stars pc$^{-2}$.
The extinction law from photometric data: linear regression methods
Joana Ascenso,Marco Lombardi,Charles J. Lada,Joo Alves
Physics , 2012, DOI: 10.1051/0004-6361/201118355
Abstract: Context. The properties of dust grains, in particular their size distribution, are expected to differ from the interstellar medium to the high-density regions within molecular clouds. Since the extinction at near-infrared wavelengths is caused by dust, the extinction law in cores should depart from that found in low-density environments if the dust grains have different properties. Aims. We explore methods to measure the near-infrared extinction law produced by dense material in molecular cloud cores from photometric data. Methods. Using controlled sets of synthetic and semi-synthetic data, we test several methods for linear regression applied to the specific problem of deriving the extinction law from photometric data. We cover the parameter space appropriate to this type of observations. Results. We find that many of the common linear-regression methods produce biased results when applied to the extinction law from photometric colors. We propose and validate a new method, LinES, as the most reliable for this effect. We explore the use of this method to detect whether or not the extinction law of a given reddened population has a break at some value of extinction.
On the Star Formation Rates in Molecular Clouds
Charles J. Lada,Marco Lombardi,Joo F. Alves
Physics , 2010, DOI: 10.1088/0004-637X/724/1/687
Abstract: In this paper we investigate the level of star formation activity within nearby molecular clouds. We employ a uniform set of infrared extinction maps to provide accurate assessments of cloud mass and structure and compare these with inventories of young stellar objects within the clouds. We present evidence indicating that both the yield and rate of star formation can vary considerably in local clouds, independent of their mass and size. We find that the surface density structure of such clouds appears to be important in controlling both these factors. In particular, we find that the star formation rate (SFR) in molecular clouds is linearly proportional to the cloud mass (M_{0.8}) above an extinction threshold of A_K approximately equal to 0.8 magnitudes, corresponding to a gas surface density threshold of approximaely 116 solar masses per square pc. We argue that this surface density threshold corresponds to a gas volume density threshold which we estimate to be n(H_2) approximately equal to 10^4\cc. Specifically we find SFR (solar masses per yr) = 4.6 +/- 2.6 x 10^{-8} M_{0.8} (solar masses) for the clouds in our sample. This relation between the rate of star formation and the amount of dense gas in molecular clouds appears to be in excellent agreement with previous observations of both galactic and extragalactic star forming activity. It is likely the underlying physical relationship or empirical law that most directly connects star formation activity with interstellar gas over many spatial scales within and between individual galaxies. These results suggest that the key to obtaining a predictive understanding of the star formation rates in molecular clouds and galaxies is to understand those physical factors which give rise to the dense components of these clouds.
Molecular clouds have power-law probability distribution functions
Marco Lombardi,Joo Alves,Charles J. Lada
Physics , 2015, DOI: 10.1051/0004-6361/201525650
Abstract: In this Letter we investigate the shape of the probability distribution of column densities (PDF) in molecular clouds. Through the use of low-noise, extinction-calibrated \textit{Herschel}/\textit{Planck} emission data for eight molecular clouds, we demonstrate that, contrary to common belief, the PDFs of molecular clouds are not described well by log-normal functions, but are instead power laws with exponents close to two and with breaks between $A_K \simeq 0.1$ and $0.2\,\mathrm{mag}$, so close to the CO self-shielding limit and not far from the transition between molecular and atomic gas. Additionally, we argue that the intrinsic functional form of the PDF cannot be securely determined below $A_K \simeq 0.1\,\mathrm{mag}$, limiting our ability to investigate more complex models for the shape of the cloud PDF.
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