248 resultados para Componentes principais


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The present study was developed in two streams from the two different drainage basins located in the mid-southern region of Paraná state. In each stream were evaluated some physical and chemical parameters in open (without streamside vegetation) and shaded (with streamside vegetation) segments. Monthly samplings were carried out from January to December 2007. The following limnological parameters were measured: water temperature, specific conductance, oxygen saturation, pH, turbidity and current velocity. In the same stream were not observed differences among segments from the drainage basins, and nominal values and seasonal pattern have been very similar between open and shaded ambient. A Principal Component Analysis (PCA) showed small divergence between streams and segments, with separation of groups with base sampling dates. The results suggest that the region is homogeneous according to physical and chemical water conditions, therefore, stronger influenced for time factor, and diverging seasonal periods associated a climatic region condition.

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Two drainage basins located in the mid-southern region of Paraná state were comparatively studied for analysis of limnological characteristics in lotic ecosystems. Ten segments of rivers and streams were evaluated in each basin, from June 4th through to June, 29th , 2007. The following physical and chemical parameters were measured: water temperature, specific conductance, oxygen saturation, pH, turbidity, current velocity and depth. The two drainage basins presented similar nominal values for all parameters investigated. There were significant differences between the two environments in relation to temperature, pH, and oxygen saturation. Cluster analysis revealed five small groups of samplings, each one with particular limnological characteristics. The Principal Components Analysis (PCA) confirmed the difference among the drainage basins. These results suggest an influence of regional and local factors in limnological characteristics of rivers and streams in the studied drainage basins.

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In view of the diversity of environments found in the Brazilian territory, it is understandable that the use of native species can provide more relevant information for ecotoxicological studies. The purpose of this work was to evaluate the quality of water samples from the Atibaia River in an area that is under the influence of petroleum refinery using a native test-organism and submitting the data to PCA statistical analysis. Therefore, acute toxicity assays with Lecane bulla (Rotifera) were performed in four locations of the river, as well as physical-chemical analyses. Sampling was drawn in the dry and rainy seasons. The bioassays were static and lasted 48 hours; dead organisms were quantified at the end of the tests. Toxicological differences among the samples/per location and control were compared by means of the Analysis of Variance. Physical-chemical and mortality variables were simultaneously analyzed by multivariate analysis of the principal components and the Pearson correlation coefficient. Water samples from the exit of the refinery stabilization pond (location S.1) were toxic to L. bulla in both seasons, with significant differences in relation to the control and between the seasons. The statistical treatment of data showed that mortality was strong and positively correlated with total hardness, chlorides and EC, which together with pH presented higher values in location S.1, in the dry and in the rainy seasons. Due to its sensibility to the quality of the Atibaia river water samples, the potential use of L. bulla for ecotoxicological studies as an alternative test organism could be demonstrated.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Genética e Melhoramento Animal - FCAV

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Heavy metals are found naturally in soils at low concentrations, but their content may be increased by human activity, making them one of the barriers in management of tropical soils. These chemical elements can be found in the composition of organic and inorganic fertilizers, insecticides, fungicides, mine tailings, and urban waste, and may cause serious damage to the environment and human health. Thus, adsorption studies are essential in assessing the behavior of heavy metals in the soil. The objective of this study was to evaluate the influence of soil chemical, particle size, and mineralogical properties on adsorption of cadmium (Cd), evaluated by Langmuir and Freundlich models, in Latossolos (Oxisols) with or without human activity. Soil samples were collected from the surface layer, 0.00-0.20 m, and chemical, particle size, and mineralogical analyzes were performed. In the adsorption study, concentrations of 0, 5, 25, 50, 100, 200, 300, and 400 mu g L-1 of Cd were used in the form of Cd(NO3)(2). The empirical mathematical models of Langmuir and Freundlich were used for construction of adsorption isotherms. Data were analyzed by means of multivariate statistical techniques, Cluster Analysis and Principal Component Analysis. The data from the adsorption experiment showed a good fit to the Langmuir and Freundlich models. Soils with a lower goethite/hematite ratio and greater cation exchange capacity and pH, showed higher maximum adsorption capacity of Cd.

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The study was conducted in two different locations in South Brazil, in tillage in the 2009/2010 season on eight sunflower hybrids, aiming to determine the path correlations and coefficients between primary and secondary characters on the main variable of achene productivity. The correlations were similar between environments. The characters of the head diameter and mass of a thousand achenes had a significant influence on sunflower productivity. Based on the magnitude of the direct and indirect effects, we highlighted all primary components on the main variable, beside the good determination coefficient and low residual effect. The secondary component, the number of achenes, despite the significant direct effect on productivity, was indirectly influenced by the primary components, making it an undesirable character for selection.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Beef quality control, particularly its sensory characteristics, is an important factor for producers and retailers in order to satisfy consumer’s choices. Sensory analysis is an important tool to evaluate attributes that cannot be measured by easily available instrumental techniques, as well as texture – tenderness and juiciness – whose human perception is more complete, through trained panels. The aim of this study was evaluate the use of a beef sensory analysis protocol in three different laboratories. Six commercial samples of different brands of aged beef and 14 samples from crossbred animals (Bonsmara × Nelore - 7 and Canchim × Nelore - 7), aged during 14 days were analyzed. The samples were distributed to each participant laboratory, where 7 to 12 panelists were trained. A sheet containing a 9 cm non-structured scale with 14 attributes was used. The attributes were brown colour (CMAR); aponevrosis (PNAP); hydration degree (GH); characteristic beef aroma (SCCB); salty taste (SS); liver flavour (SF); fat flavour (SG); metallic flavour (SM); tenderness (MZ); juiciness (SL); fibrosity (FBS) and liver texture (SF). Obtained data was analyzed using analysis of variance and principal component analysis (PCA). The results showed that there was no interaction between samples and laboratories, indicating that all of them responded in a similar manner in relation to the samples, except PNAP attribute, which was expected as meat is very non-uniform normally. Samples were well differentiated in all laboratories as it could be observed in PCA graphs. With proper training it is possible to use a standard protocol for beef sensory analysis.