3,722 research outputs found

    Classificação de perfis com horizonte A antrópico (Terra Preta de Índio) em áreas de várzea do rio Solimões, AM.

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    Com o intuito de desenvolver um maior conhecimento pedológico a cerca dos solos antrópicos na Amazônia, o presente estudo teve como objetivo caracterizar e classificar perfis de TPI em áreas de várzea do rio Solimões

    High Titers ofChlamydia trachomatis Antibodies in Brazilian Women with Tubal Occlusion or Previous Ectopic Pregnancy

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    Objective. To evaluate serum chlamydia antibody titers (CATs) in tubal occlusion or previous ectopic pregnancy and the associated risk factors.Methods. The study population consisted of 55 women wih tubal damage and 55 parous women. CAT was measured using the whole-cell inclusion immunofluorescence test and cervical chlamydial DNA detected by PCR. Odds ratios were calculated to assess variables associated withC. trachomatis infection.Results. The prevalence of chlamydial antibodies and antibody titers in women with tubal occlusion or previous ectopic pregnancy was significantly higher (P < .01) than in parous women. Stepwise logistic regression analysis showed that chlamydia IgG antibodies were associated with tubal damage and with a larger number of lifetime sexual partners.Conclusions. Chlamydia antibody titers were associated with tubal occlusion, prior ectopic pregnancy, and with sexual behavior, suggesting that a chlamydia infection was the major contributor to the tubal damage in these women

    Distribuição diametrica do número de árvores e da área basal de uma floresta primaria de terra firme no Amapá.

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    As florestas tropicais estão entre os ecossistemas mais complexos conhecidos. Apesar da aparente desordem de seus componentes, encontram-se padrões mensuraveis de dinamica, composicao e estruturas. enquanto estes, entre outros aspectos, detalham riqueza e diversidade floristica, indicadores físicos da massa arborea e ocupação horizontal e vertical do espaço, em termos de dinamica, destacam-se, mortalidade e o crescimento da massa arborea.bitstream/item/97850/1/CPAF-AP-1998-Distribuicao-diametrica.pd

    Antioxidant defenses of irrigated forage sorghum with saline aquaculture effluent.

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    The objective of this work was to evaluate the biomass production and antioxidant enzymatic system activity of irrigated forage sorghum with saline aquaculture effluent under different leaching fractions. The experiment was conducted in the Caatinga Experimental Field of the Embrapa Semiarido, in Petrolina, State of Pernambuco, Brazil. The experimental design was a complete randomized block in a split-plot arrangement with four replications, consisting of three forage sorghum varieties (Volumax, F305 and Sudan) and four leaching fractions (0, 5, 10 and 15%). The vegetal materials were collected when the plants were at the soft-dough stage. The biomass production and activity of the enzymes superoxide dismutase, catalase and ascorbate peroxidase were evaluated. Irrigation with saline aquaculture effluent with leaching fraction of 15% results in low salinity level in the root zone and higher biomass production of forage sorghum Sudan and F305, in semiarid conditions. The antioxidant system was activated in the three sorghum varieties to prevent accumulation of reactive oxygen species, with the synchrony between the enzymes superoxide dismutase and catalase resulting in a better productive response of the varieties Sudan and F30

    Currency Unions and Trade: A PPML Re-Assessment with High-Dimensional Fixed Effects

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    Recent work on the effects of currency unions (CUs) on trade stresses the importance of using many countries and years in order to obtain reliable estimates. However, for large samples, computational issues associated with the three-way (exporter-time, importer-time, and country-pair) fixed effects currently recommended in the gravity literature have heretofore limited the choice of estimator, leaving an important methodological gap. To address this gap, we introduce an iterative Poisson Pseudo-Maximum Likelihood (PPML) estimation procedure that facilitates the inclusion of these fixed effects for large data sets and also allows for correlated errors across countries and time. When applied to a comprehensive sample with more than 200 countries trading over 65 years, these innovations flip the conclusions of an otherwise rigorously-specified linear model. Most importantly, our estimates for both the overall CU effect and the Euro effect specifically are economically small and statistically insignificant. We also document that linear and PPML estimates of the Euro effect increasingly diverge as the sample size grows
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