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Search Results: 1 - 10 of 3514 matches for " Edson;Cortez "
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Cattle manure and N-urea in radish crop (Raphanus sativus)
Mendoza Cortez,Juan W; Cecílio Filho,Arthur B; Coutinho,Edson L; Alves,Anarlete;
Ciencia e investigación agraria , 2010, DOI: 10.4067/S0718-16202010000100004
Abstract: this work was carried out in jaboticabal (575 m altitude, 21°15? 22? s and 48° 15? 58? w), s?o paulo, brazil, aiming to investigate the effects of cattle manure and nitrogen (urea) doses on radish height and yield. randomized blocks were used with a 2x4x4 factorial scheme and 3 replications. the treatments were combinations of cultivars (25 and 19), cattle manure doses (0, 25, 50, and 75 t ha-1 dry basis) and n doses (0, 60, 120 and 180 kg ha-1). increased cattle manure and urea doses provided higher plant height and commercial yield in both cultivars, but the n produced more signifcant effects than the cattle manure. the maximum commercial yield of cultivar (cv) 19 (20.34 t ha-1) was obtained using 75 t ha-1 of cattle manure and 139 kg ha-1 of n, whereas that of cv 25 (11.90 t ha-1) occurred with 75 t ha-1 of cattle manure and 180 kg ha-1 of n. the maximum economic effciency doses for cv. 25 were 65.1 t ha-1 and 180 kg ha-1 of cattle manure and n, respectively, whereas those for cv 19 were 63.6 t ha-1 and 144.7 kg ha-1 of cattle manure and n, respectively.
Population Dynamics of Large Herbivores and the Framing of Wildlife Conservation in Zimbabwe  [PDF]
Edson Gandiwa
Open Journal of Ecology (OJE) , 2014, DOI: 10.4236/oje.2014.47036
Abstract:

This article reviews: 1) The role of natural and human-induced controls in influencing large herbivore populations; 2) how human controls (i.e., policy instruments, incentives and provisions) influence human activities and wildlife conservation; and 3) media framing of wildlife conservation using Zimbabwe as a case study, in particular Gonarezhou National Park and adjacent areas. The review shows that droughts are important in influencing large herbivore populations in semi-arid ecosystems; political instability and economic collapse does not necessarily lead to increased illegal hunting in situations where policy instruments, such as laws, are enforced. A higher perceived effectiveness of Communal Areas Management Programme for Indigenous Resources was partly associated with a decline in human-wildlife conflicts and there was a spill-over effect of frames from the political domain into wildlife conservation following Zimbabwe’s land reforms in 2000. It is concluded that natural bottom-up processes (e.g., droughts) influence large herbivore population dynamics whereas policy instruments, incentives, provisions and societal frames mainly have a top-down effect on wild large herbivore populations in savanna ecosystems.

Antioxidant Capacity of the Leaf Extract Obtained from Arrabidaea chica Cultivated in Southern Brazil
Jackeline Tiemy Guinoza Siraichi, Daniele Fernanda Felipe, Lara Zampar Serra Brambilla, Melissa Junqueira Gatto, Vania Aparecida Terra, Alessandra Lourenco Cecchini, Lucia Elaine Ranieri Cortez, Edson Rodrigues-Filho, Diógenes Aparício Garcia Cortez
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072733
Abstract: Arrabidaea chica leaf extract has been used by people as an anti-inflammatory and astringent agent as well as a remedy for intestinal colic, diarrhea, leucorrhea, anemia, and leukemia. A. chica is known to be a good producer of phenolics. Therefore, in the present study, we investigated its antioxidant activity. The phenolic composition of A. chica leaves was studied by liquid chromatography coupled to diode array detection (LC–DAD) and liquid chromatography coupled to electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS), and isoscutellarein, 6-hydroxyluteolin, hispidulin, scutellarein, luteolin, and apigenin were identified. The extract from leaves of A. chica was tested for antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, β-carotene bleaching test, and total reactive antioxidant potential (TRAP) method. The crude extract quenched DPPH free radicals in a dose-dependent manner, and the IC50 of the extract was 13.51 μg/mL. The β-carotene bleaching test showed that the addition of the A. chica extract in different concentrations (200 and 500 μg/mL) prevented the bleaching of β-carotene at different degrees (51.2% ±3.38% and 94% ±4.61%, respectively). The TRAP test showed dose-dependent correlation between the increasing concentrations of A. chica extract (0.1, 0.5, and 1.0 μg/mL) and the TRAP values obtained by trolox (hydro-soluble vitamin E) 0.4738±0.0466, 1.981±0.1603, and 6.877±1.445 μM, respectively. The 2 main flavonoids, scutellarein and apigenin, were separated, and their antioxidant activity was found to be the same as that of the plant extract. These 2 flavonoids were quantified in the plant extract by using a validated HPLC-UV method. The results of these tests showed that the extract of A. chica had a significant antioxidant activity, which could be attributed to the presence of the mixture of flavonoids in the plant extract, with the main contribution of scutellarein and apigenin.
Lanostane triterpenes from the fungus Pisolithus tinctorius
Zamuner, M. Lucília M.;Cortez, Diógenes A. G.;Dias Filho, Benedito P.;Lima, M. Inês S.;Rodrigues-Filho, Edson;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000500028
Abstract: a new triterpene, 3b,22x,23x-trihydroxy-24-methyllanosta-8,24(28)-diene-31-al 22-acetate, named pisosteral, and four known lanostane triterpenes derivatives, 3b,22x,23x-trihydroxy-24-methyllanosta-8,24(28)-diene 22-acetate (pisosterol), 3a,22x,23x-trihydroxy-24-methyllanosta-8,24(28)-diene 22-acetate (3-epi-pisosterol), 3b,22x,23x-trihydroxy-24-methyllanosta-8,24(28)-diene 23-acetate and 3b,22x,23x-trihydroxy-24-ethyllanosta-8,24(28)-diene 22-acetate, were isolated from fruiting bodies of pisolithus tinctorius, collected in an eucalyptus plantation. from cultivation of a strain of p. tinctorius isolated from pinus taeda, four known triterpenes lanostane derivatives, 3b,22x-dihydroxy-24-methyllanosta-8,24(28)-diene, 3b,22x-dihydroxy-24-ethyllanosta-8,24(28)-diene, 3b-hydroxylanosta-8,24-diene (lanosterol) and 3b-hydroxylanosta-7(8),9,24-triene (agnosterol), were isolated. these compounds were identified on the basis of chemical and physical methods, mainly mass spectrometry and 1d and 2d nuclear magnetic resonance.
Estudo fitoquímico e avalia??o da atividade moluscicida do Calophyllum brasiliense Camb (Clusiaceae)
Gasparotto Jr., Arquimedes;Brenzan, Mislaine Adriana;Piloto, Izabel Cristina;Cortez, Diógenes Aparício Garcia;Nakamura, Celso Vataru;Dias Filho, Benedito Prado;Rodrigues Filho, Edson;Ferreira, Antonio Gilberto;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000400003
Abstract: the bioassay-guided fractionation against biomphalaria glabrata of hydroalcoholic extracts of calophyllum brasiliense aerial parts led to the isolation of the coumarin, named (-) mammea a/bb. the compound had its structure determined by both spectroscopic techniques (nmr 1h, nmr 13c, ghsqc, ghmbc and ms) and some literature comparison data. the probit analysis of (-) mammea a/bb showed ld50 = 0.67 ppm and ld90 = 1.47 ppm. in addition, the dichloromethane extract obtained from c. brasiliense leaves with significant molluscicidal activity against biomphalaria glabrata was analyzed by hplc-uv.
El Acceso a los Servicios de Atenci 3n de la Salud en el Per o y la Equidad en su Financiamiento El Acceso a los Servicios de Atenci 3n de la Salud en el Per o y la Equidad en su Financiamiento
Rafael Cortez
Revista de Análisis Económico (RAE) , 1996,
Abstract: This study develops a methodology to analize the demand for health services. It is based on dichotomic regressions aimed at determining why consumers prefer certain services and do not demand other. It discusses the possible impact on the number of medical vis its of changes in health costs and households income, and focuses on highlighting some criteria regarding the efficiency and fairness of current policies of coverage and finance. The empirical analysis uses information from the National Survey on Health Expenditures (Endesa, 1995), which obtained data on health and demographic variables from a sample of 1,290 households and 6,366 individuals. This study develops a methodology to analize the demand for health services. It is based on dichotomic regressions aimed at determining why consumers prefer certain services and do not demand other. It discusses the possible impact on the number of medical vis its of changes in health costs and households income, and focuses on highlighting some criteria regarding the efficiency and fairness of current policies of coverage and finance. The empirical analysis uses information from the National Survey on Health Expenditures (Endesa, 1995), which obtained data on health and demographic variables from a sample of 1,290 households and 6,366 individuals.
Singularites generiques et quasi-resolutions des varietes de Schubert pour le groupe lineaire
Aurelie Cortez
Mathematics , 2001,
Abstract: We determine explicitly the irreducible components of the singular locus of any Schubert variety for GL_n(K), K being an algebraically closed field of arbitrary characteristic. We also describe the generic singularities along these components. The case of covexillary Schubert varieties was solved in an earlier work of the author [Ann. Inst. Fourier vol. 51 fasc. 2 (2001), 375-393]. Here, we first exhibit some irreducible components of the singular locus of X_w, by describing the generic singularity along each of them. Let S_w be the union of these components. As mentioned above, the equality S_w = Sing X_w is known for covexillary varieties, and we base our proof of the general case on this result. More precisely, we study the exceptional locus of certain quasi-resolutions of a non-covexillary Schubert variety X_w, and we relate the intersection of these loci to S_w. Then, by induction on the dimension, we can establish the equality.
Slowly Oscillating Solution of the Cubic Heat Equation
Fernando Cortez
Mathematics , 2015,
Abstract: In this paper, we are considering the Cauchy problem of the nonlinear heat equation $u\_t -\Delta u= u^{3 },\ u(0,x)=u\_0$. After extending Y. Meyer's result establishing the existence of global solutions, under a smallness condition of the initial data in the homogeneous Besov spaces $\dot{B}\_{p}^{-\sigma, \infty}(\mathbb{R}^{3})$, where $3 \textless{} p \textless{} 9$ and $\sigma=1-3/p$, we prove that initial data $u\_0\in \mathcal{S}(\mathbb{R}^{3})$, arbitrarily small in ${\dot B^{-2/3,\infty}\_{9}}(\mathbb{R}^{3})$, can produce solutions that explode in finite time. In addition, the blowup may occur after an arbitrarily short time.
Discrete Singular Convolution Method for Numerical Solutions of Fifth Order Korteweg-De Vries Equations  [PDF]
Edson Pindza, Eben Maré
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.17002
Abstract:

A new computational method for solving the fifth order Korteweg-de Vries (fKdV) equation is proposed. The nonlinear partial differential equation is discretized in space using the discrete singular convolution (DSC) scheme and an exponential time integration scheme combined with the best rational approximations based on the Carathéodory-Fejér procedure for time discretization. We check several numerical results of our approach against available analytical solutions. In addition, we computed the conservation laws of the fKdV equation. We find that the DSC approach is a very accurate, efficient and reliable method for solving nonlinear partial differential equations.

Carbon Doped Nano-Crystalline TiO2 Photo-Active Thin Film for Solid State Photochemical Solar Cells  [PDF]
Raymond Taziwa, Edson Meyer
Advances in Nanoparticles (ANP) , 2014, DOI: 10.4236/anp.2014.32008
Abstract:

Carbon doped titanium dioxide (C-TiO2) is considered as a promising photocatalytic material due to its optical absorption extended in the visible region compared to pure TiO2. However, in the field of photovoltaic’s, use of C-doped nano-crystalline titanium dioxide (C-TiO2) electrodes for light absorption has been considered to be unnecessary so far. In this context, we report here on the use of C-TiO2 nano-crystalline electrodes in photochemical solar cells devices (PCSC). Carbon doping has reduced the band gap of TiO2 to 2.41 eV and 2.25 eV with increase in the doping extent for the 9 mM C-TiO2 and 45 mM C-TiO2 respectively. The C-TiO2 electrodes were first used as photo electrodes for solar cells, exhibiting JSC of 1.34651 mA/cm2, VOC 0.683 V, FF 50.23% and η 0.46%. for the 9 mM C-TiO2

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