3,797 research outputs found

    Validação de modelos geoestatísticos usando teste de Filliben: aplicação em agroclimatologia.

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    O objetivo deste trabalho é validar modelos geoestatísticos aplicados a agroclimatologia através do teste de normalidade de Filliben em resíduos ortonormais com dados de precipitação média anual para o Estado de São Paulo.bitstream/CNPTIA/10388/1/comtec60.pdfAcesso em: 28 maio 2008

    Avaliação e comparação de estimadores de Krigagem para variáveis agronômicas - uma proposta.

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    Avaliar e comparar diferentes tipos de estimadores ótimos krigagem visando extrapolar seus potenciais na determinação da melhor distribuição espacial de variáveis agronômicas para a bacia hidrográfica do ribeirão São Domingos em Pindorama.bitstream/CNPTIA/9211/1/DOCUMENTO3int.pdfAcesso em: 29 maio 2009

    Reação de cultivares de cenoura a meloidogyne incognita raça 1 e Meloidogyne mayaguensis.

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    Studies on the behaviour of Pseudomonas fluorescens biofilms after ortho-phthalaldehyde treatment

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    A relatively novel biocide, ortho-phthalaldehyde (OPA), was tested to control biofilms formed by Pseudomonas fluorescens on stainless steel surfaces. The toxic action of OPA was assessed in terms of inactivation and removal of the biofilm by means of, respectively, the determination of the respiratory activity and the variation in the dry weight of the biofilms. For comparison, the activity of OPA against suspended bacteria was also evaluated. The results showed that higher concentrations of OPA and longer exposure times are needed to inactivate P. fluorescens biofilms than planktonic populations, thus denoting that sessile bacteria have a reduced susceptibility to OPA. This appears to be associated with the reaction with the proteins of the matrix, as demonstrated by the reduction of the antimicrobial action of OPA in the presence of a protein (bovine serum albumin). The application of OPA appeared to cause little effect in the removal of biofilms from the metal slides since the mass of biofilm that remained on the surfaces, after biocide treatment, was within the same range as those observed in the control tests. These results suggest that, with OPA application, biofilms can be inactivated but stay attached to the surfaces, decreasing thereby the success of the chemical treatment.Instituto de Biotecnologia e Química Fina (IBQF). Fundação para a Ciência e a Tecnologia (FCT) - POCTT/1999/BIO/35683

    Surveillance of the behaviour of pseudomonas fluorescens biofilms after ortho-phtalaldehyde disinfection

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    A relatively novel antimicrobial agent, ortho-phtalaldehyde (OPA), was tested in the control of biofilms formed by Pseudomonas fluorescens on stainless steel surfaces. The toxic action of OPA was assessed by means of activity tests and dry weight of the biofilms. For comparative purposes, the activity of OPA against bacterial suspended cultures was also evaluated. The results showed that concentrations of OPA higher than 15 mg L-1 inactivate the planktonic populations while having a lower effect against the P. fluorecens biofilms. The inactivation of the biofilm was only attained with the higher OPA concentrations (50 and 100 mg L-1) and for longer exposure times (3 h). The application of OPA appears to cause little effect in the removal of biofilms from the metal slides since the amount of biofilm mass that remained on the surfaces, after biocide treatment, stills to be very high and representative. These results suggest the fact that, with OPA application, biofilms can be inactivated but stay attached to the surfaces, decreasing, by this way, the success of the chemical treatment.Fundação para a Ciência e a Tecnologia (FCT), project POCTT/1999/BIO/35683

    Seleção para germinação de sementes de cenoura na região norte do Brasil.

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    As cultivares de cenoura do grupo Brasília apresentam boa adaptação às condições de cultivo durante o verão no Brasil. Entretanto, é necessário selecionar para aumentar o potencial de germinação sob temperaturas elevadas, propiciando economia de sementes e estandes mais uniformes, principalmente em regiões quentes do país. O objetivo deste trabalho foi verificar a efetividade da seleção para maximização da germinação de sementes de cenoura sob altas temperaturas, para uma população do grupo Brasília, em condições de campo no Norte do Brasil. Em setembro de 2008, em Porto Velho-RO, foram avaliadas quanto a germinação 57 progênies meioirmãs de cenoura da população de melhoramento 0712480, utilizando-se delineamento em blocos casualizados com quatro repetições de 100 sementes de cada progênie. Os dados obtidos foram submetidos a análises de variância e estimadas aherdabilidade e ganhos diretos com a seleção. Pôde-se verificar que a seleção para maior porcentagem de germinação em altas temperaturas possibilita ganho genético para esta característica. No entanto, não supera o ganho obtido com a seleção efetuada em laboratório, já que o mesmo possibilita obtertemperaturas médias diárias mais elevadas e constantes.Trabalho apresentado no Congresso Brasileiro de Olericultura, 50., 2010, Guarapari. Cinquenta anos contribuindo para a saúde da população brasileira. Trabalho A3097-T4592

    Arithmetic fuchsian groups and space time block codes

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    In the context of space time block codes (STBCs) the theory of arithmetic Fuchsian groups is presented. Additionally, in this work we present a new class of STBCs based on arithmetic Fuchsian groups. This new class of codes satisfies the property full-diversity, linear dispersion and full-rate. Mathematical subject classification: 18B35, 94A15, 20H10

    Gold's hedging and safe haven properties for European stock and bond markets

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    Most portfolio managers and risk managers strive to pick assets that lead to efficient financial risk mitigation; among them, gold stands out. This paper provides new insights into the role of gold as both a hedge and a safe haven towards European stock and sovereign bond markets. We base the analysis on evidence spanning the Euro's inception to the COVID-19 pandemic spread across Europe. To capture gold's hedge ability, we use the ADCC-GARCH and DCC-GARCH models, while for testing gold's safe haven property we use OLS regressions for different quantiles. Our results show that gold is a hedge for stocks, particularly after the Lehman Brothers collapse. Gold also shows strong safe haven properties for the most extreme negative returns (1% and 2.5% quantiles), and during specific events, such as the Lehman Brothers collapse, the Greek bailout and the Brexit Referendum. Still, for the COVID-19 pandemic outbreak, the results do not confirm this property. Conversely, for bonds, both hedge and safe haven effects are not strongly evident, with gold characterised, at best, as a weak hedge and safe haven. These findings have portfolio allocation implications for investors in European markets, namely fund and risk managers, by pointing out gold hedging and safe haven attributes.info:eu-repo/semantics/publishedVersio
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