900 resultados para Variables from CGTMSE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Macroalgal species richness and diversity were analysed along a longitudinal profile in small and large scales during Spring, Fall and Winter, respectively in a small stream and a mid size river in the northwest region of São Paulo State, southeastern Brazil (20 degrees 23'-20 degrees 49'S, 49 degrees 26'-51 degrees 19'W). Longitudinal variation in species richness and diversity in small scale was strongly associated with incident light. Microhabitat distribution (from data taken by quadrat technique) revealed no significant correlations. Principal coordinates analysis (PCO) indicated no consistent groupings among sampling sites in distinct seasons (Spring, Fall and Winter). Longitudinal analysis in large scale revealed different patterns in the two seasons sampled (Spring and Winter), whereas species diversity presented a consistent tl end: high upstream, low in mid reaches and higher downstream. It was associated with type of substratum in Spring, rocky substrata presenting the highest values for species richness and diversity. Weak correlations were observed in Winter. Microhabitat distribution showed significant correlations between species abundance and the following variables: positive for rocky substrata and current velocity and negative for sandyclayish substratum and macrophyte-dominated substratum. PCO delineated only one consistent grouping formed by the two headwater sites. Small scale macroalgal distribution corroborated the longitudinal pattern predicted by the River Continuum Concept, whereas the large scale approach showed a distribution more associated with substratum type than to light availability. These results showed an opposite trend in relation to the expected distributional pattern. Longitudinal distribution in macroalgal community structure has yet to be better documented, particularly for tropical streams and no generalization is possible at this stage.
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The third primary production algorithm round robin (PPARR3) compares output from 24 models that estimate depth-integrated primary production from satellite measurements of ocean color, as well as seven general circulation models (GCMs) coupled with ecosystem or biogeochemical models. Here we compare the global primary production fields corresponding to eight months of 1998 and 1999 as estimated from common input fields of photosynthetically-available radiation (PAR), sea-surface temperature (SST), mixed-layer depth, and chlorophyll concentration. We also quantify the sensitivity of the ocean-color-based models to perturbations in their input variables. The pair-wise correlation between ocean-color models was used to cluster them into groups or related output, which reflect the regions and environmental conditions under which they respond differently. The groups do not follow model complexity with regards to wavelength or depth dependence, though they are related to the manner in which temperature is used to parameterize photosynthesis. Global average PP varies by a factor of two between models. The models diverged the most for the Southern Ocean, SST under 10 degrees C, and chlorophyll concentration exceeding 1 mg Chlm(-3). Based on the conditions under which the model results diverge most, we conclude that current ocean-color-based models are challenged by high-nutrient low-chlorophyll conditions, and extreme temperatures or chlorophyll concentrations. The GCM-based models predict comparable primary production to those based on ocean color: they estimate higher values in the Southern Ocean, at low SST, and in the equatorial band, while they estimate lower values in eutrophic regions (probably because the area of high chlorophyll concentrations is smaller in the GCMs). Further progress in primary production modeling requires improved understanding of the effect of temperature on photosynthesis and better parameterization of the maximum photosynthetic rate. (c) 2006 Elsevier Ltd. All rights reserved.
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This work describes an application of principal component analysis (PCA) on a database of secondary metabolites from the Asteraceae family. The numbers of occurrences of metabolites in 11 chemical classes for the different vibes of the family were used as variables, PCA allows the identification of chemical classes that contribute most to the subgroups classification within the family. Relationships between chemical composition and botanical classification were made. (C) 2001 Elsevier B.V. B.V. All rights reserved.
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Microhabitat distribution was investigated in five populations of Characeae (two of Chara guairensis, two of Nitella subglomerata and one of Nitella sp.) to determine the distributional patterns, the morphometric and reproductive adaptations to varying environmental conditions and niche width on a scale of few centimeters. Variations in physical variables revealed some general trends of microhabitat distribution for the Characeae populations studied, with occurrence under the following conditions: slow and narrow current velocities; substrata predominantly composed of small particle size (sand-clay); variable and generally low depths. In terms of morphological adaptations, we found some general patterns: plants with longer whorl branchlets also had longer internodes in all populations studied, whereas longer plants had also thicker axis. The former were generally associated with higher biomass (percent cover). Few correlations of morphological characters were observed with environmental variables (e.g. plant length with irradiance: negative in two populations and positive in one population). Despite the general patterns of occurrence mentioned above, our results also indicated that each population differed in its responses to environmental variables and had particular morphological and reproductive adaptations. The Characean populations occurred under a narrower range of microhabitat conditions than other macroalgae from lotic habitats, particularly lower current velocity (6.7-9.8 cm s(-1)) and a more specific substratum type (sand-clay). Niche width values (0.60-0.99) of the Characeae populations studied indicate a high degree of habitat specialization and are among the highest yet found in lotic macroalgae. The relatively narrow variations in microhabitat conditions and high niche widths here reported for Characean populations, suggest a lower tolerance to variations in current velocity, depth, irradiance and substratum type. These characteristics probably explain the relatively restricted distribution of Characeae species in streams of S (a) over tildeo Paulo State with low frequency of records in most regions.
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Tin dioxide nanoparticle suspensions were synthesized at room temperature by the hydrolysis reaction of tin chloride (II) dissolved in ethanol. The effect of the initial tin (II) ion concentration, in the ethanolic solution, on the mean particle size of the nanoparticles was studied. The Sn2+ concentration was varied from 0.0025 to 0.1 M, and all other synthesis parameters were kept fixed. Moreover, an investigation of the effect of agglomeration on the nanoparticle characteristics (i.e., size and morphology) was also done by modifying the pH of the SnO2 suspensions. The different samples were characterized by transmission electron microscopy, optical absorption spectroscopy in the ultraviolet range, and photoluminescence measurements. The results show that higher initial ion concentrations and agglomeration lead to larger nanoparticles. The concentration effect is explained by enhanced growth due to a higher supersaturation of the liquid medium. However, it was observed that the agglomeration of the nanoparticles in suspension induce coarsening by the oriented-attachment mechanism.
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Optimal conditions for the extraction of casearins from Casearia sylvestris were determined using response surface methodology. The maceration and sonication extraction techniques were performed using a 3 x 3 x 3 full factorial design including three acidity conditions, three solvents of different polarities and three extraction times. The yields and selectivities of the extraction of casearins were significantly influenced by acidity conditions. Taking into account all variables tested, the optimal conditions for maceration extraction were estimated to involve treatment with dichloromethane saturated with ammonium hydroxide for 26 h. Similar yields and selectivities for casearins were determined for sonication extraction using the same solvent but for the much shorter time of I h. The best results for stabilisation of the fresh plant material were obtained using leaves that had been oven dried at 40 degrees C for 48 h. Copyright (c) 2006 John Wiley & Sons, Ltd.
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Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Parana River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/ 10 m(3)) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m(3)) of Bryconamericus stramineus throughout almost the whole study period, the majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species. shows favourable conditions for fish reproduction and development.
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The objective of the present study was to characterize the fecundity of Callinectes ornatus from the northern coast of São Paulo, Brazil. To study the fecundity and its relationships to size, brood weight, and egg size, the ovigerous females were collected at 2-month intervals for two consecutive years (January, 1991 to November, 1992) in the Ubatuba region using a fishing boat equipped with an otter-trawl type of net. After collecting, the animals were screened, bagged, labeled, and stored frozen. Only data from 38 females carrying early stage eggs were considered. In the laboratory, the specimens were thawed at room temperature, the pleopod structure with the egg mass was removed and the eggs were carefully removed from the pleopods. The samples were then fixed in 10% formalin and stored in 70% ethanol, until the time for processing. Processing followed the method of Hines (1982, 1988). Following the frequency determination of carapace width and fecundity, mean egg number, mean volume and mean dry weight of brooded egg mass were determined for each class obtained. Data were analyzed by regressions of log-log transformations for allometric plots (Y = aX(b)) of reproductive variables versus carapace width. Carapace width was one of the main factors for the determination of fecundity, which ranged 171 570 +/- 94 634 eggs, with females of the same size class presenting a wide amplitude of variation. This supports the hypothesis that portunid females present staggered spawning, possibly presenting more than one period of reproduction within one year. The present species showed lower fecundity than the remaining portunids studied, but they did show a rapid and efficient embryonic development, presumably capable of assuring reproductive success.
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Microhabitat distribution was investigated in three populations of C. coeruleus to determine the distributional patterns and their controlling factors, as well as morphometric adaptations to varying conditions on a scale of a few centimetres. Morphometric variations and their relations with physical variables (current velocity, irradiance, depth and type of substratum) revealed some particular characteristics for each population and indicate particular adaptations. However, some trends were clear: 1) larger plants (length and/or diameter) produced a higher quantity of monosporangia in the three populations; 2) plant length and diameter were positively correlated in two populations; 3) plant diameter was positively correlated with current velocity in two populations; 4) higher percent cover was associated with substrata composed of macrophytes in two populations. C. coeruleus occurred under relatively wide microhabitat conditions and had high niche width values, suggesting a tolerance to considerable variation in physical variables. These characteristics contribute to the species' wide distribution in Brazilian streams, both spatial (at distinct scales) and seasonal. (C) ADAC / Elsevier, Paris.
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The main objective of this research was to evaluate chemical and physical changes in 'Aurora-1' peach harvested at two maturity stages, packed in different types of packaging and kept under refrigeration. Fruit were harvested at the mature green and ripe stages, packed in four different types of packaging (control, PD-900 (TM), PVC and PET) and stored at 6 degrees C. The following variables were evaluated every eight days: coloration, accumulated fresh mass loss, firmness, appearance, acidity, total soluble solids contents, soluble sugars, and percentage of pectin solubilization. We observed that the postharvest life was influenced by packaging and the mature green fruits showed lower disease occurrence. Fresh mass loss was lower in packed fruits. The peel of mature green fruits developed a characteristic ripe peach color at the end of storage, but PD-900 (TM) provided a delay in color change. Packaging also influenced the firmness, allowing for more firmness retention than for the control fruits at both harvest stages. The organic acid content decreased in the packaged fruits and increased in the control fruits. In the packaged fruit, the amount of sugar increased until the eighth day and then decreased until the end of the storage period. The 'Aurora-1' peaches did not show compromised quality by packaging use and exhibited an increase in harvest life to 24 days (compared to 16 days for the control).
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Abundance and ecological distribution of the rock shrimp Sicyonia dorsalis from the northern coast of São Paulo State (Brazil) was investigated during a two-year period (July 2001 to June 2003). Monthly collections were conducted in the Ubatuba (UBA) and Caraguatatuba (CA) regions, using a commercial shrimp boat equipped with double-rig nets. In each region, seven depths were delimited (5 m to 35 m). A total of 1,752 and 1,894 shrimp were obtained at UBA and CA, respectively. The distribution of S. dorsalis differed among depths, years, and seasons. Highest abundance values were recorded in depths where silt and clay comprised more than 70% of the sediment. The majority (89%) of captured specimens were caught in the first year, in periods of lower mean temperature, mainly in the spring of 2001, when the intrusion of cold South Atlantic Central Waters (SACW) was more intense. In such period, the differences in the abundance of shrimps in each region (UBA = 1,118 and CA = 493) suggested that S. dorsalis migrated to the north (UBA), during the SACW intrusion. Thus, sediment type and water temperature are among the most important variables affecting the bathymetric distribution of S. dorsalis in these regions.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)