Navegando por Palavras-chave "Allometry"

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    Allometric scaling of 6-min walking distance by body mass as a standardized measure of exercise capacity in healthy adults
    (Springer, 2012-07-01) Dourado, Victor Zuniga [UNIFESP]; McBurnie, Mary Ann; Universidade Federal de São Paulo (UNIFESP); Kaiser Permanente Ctr Hlth Res
    Body mass (BM) is a confounding variable in human performance. We hypothesized that adjusting 6-min walk distance (6MWD) for BM differences using allometric scaling would allow meaningful individual and group comparisons. We aimed to use allometric scaling of 6MWD to BM to provide an index for comparing walking performance in middle-aged and older adults. One hundred and twenty subjects (40-87 years) participated. Anthropometry, spirometry, and two walk tests were evaluated. We adjusted 6MWD to BM, gender, and age using an allometric procedure. the allometric exponents were prospectively applied in a validation sample of 44 healthy subjects. Body mass presented significant negative correlation (p < 0.01) with 6MWD center dot A BM-1 in middle-aged and older adults (r = -0.70 and -0.46, respectively). the allometric exponent (b) for 6MWD was significantly higher for older than middle-aged adults (0.35 +/- A 0.20 vs. 0.11 +/- A 0.08, respectively). the resulting BM exponents were similar in male and female subjects (0.22 +/- A 0.13 and 0.17 +/- A 0.09, respectively). the correlation between 6MWD center dot A BM-b and BM using the exponents (0.11 or 0.35) was not statistically different from zero (r = 0.00) in the validation sample, suggesting that allometric analysis did not penalize the subjects based on BM. Allometric scaling of 6MWD in middle-aged and older adults may be useful for evaluating walking performance free of the confounding effect of BM, even in the absence of a table of norms.
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    Biomassa em vegetação de restauração florestal de dois anos na planície costeira em Caraguatatuba, SP
    (Universidade Federal de São Paulo, 2017-06-22) Horikawa, Natacia Ery [UNIFESP]; Montero, Leda Lorenzo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Biomass is a fundamental parameter of functional characterization of ecosystems. It constitutes one of the main carbon reservoirs of terrestrial ecosystems, thus being a relevant in the context of mitigation of climate change. The objective of this study is to describe the biomass in mixed species coastal plain restoration planting in Caraguatatuba, SP. More specifically (i) Evaluate mortality and growth of the most abundant planting species; (ii) Develop allometric models to estimate total and aboveground biomass; (iii) Quantify the accumulated biomass in the first two years as well as the contribution of roots to the biomass budget; (iv) Evaluate how fertility and growth rate affect the relative biomass allocation (above and below ground). The study area of approximately 7 ha was previously covered by pasture. In 2012 were planted 15.690 seedlings of 48 species. The diameter at soil height (DAS), height (H) and canopy (COB) of 3.020 seedlings of 25 species planted in a row, alternating pioneer and non– pioneer species in plots with and without nutrient were measured in a semester basis. The relative growth rate (RGR) of all selected seedlings was calculated. To obtain the dry weight, 67 seedlings of 21 species were collected. Allometric models were then built using linear regression between dry weight and measured dimensions (DAS, H and COB). The effect of fertility and individual RGR on the relative biomass allocation were tested using mixed linear models. The models were selected using the Akaike Information Criteria. Initial mortality was high (> 20%). It was significantly reduced in the second year to 9%. Lower mortality and higher RGRs were recorded in Citharexylum myrianthum, while Euterpe edulis presented mortality > 90% and low RGRs. The best allometric models selected were: Ln(biomass) = -0.25 + 0.82 Ln(DAS² * H) (R² = 0.94, p <0.001) for the total biomass; and Ln(biomass) = -0.78 + 0.85 Ln(DAS² * H) (R² = 0.92, p <0.001) for the abovegroung biomass. The total biomass accumulated at the whole area was calculated as 50 Mg.ha-1 and the aboveground biomass about 35 Mg.ha-1. Roots represented 30% of the total biomass. The models indicated that the effect of fertility on the relative biomass allocation was uncertain. However, the RGR affected the relative biomass allocation. The R: S ratio decreased as the RGR becomes higher. In general, pioneer species had lower mortality and higher growth rates than non-pioneers. The results suggest caution when planting shade tolerant species in the initial stages of the restoration, with an alternative approach of later introduction of this kind of species in plantations. Fast-growing seedlings presented a preferential allocation in aboveground biomass, whereas the slow-growing seedlings had preference to belowground biomass, which is a clear indication of different strategies in the capture and use of resources. The models described the planting satisfactorily, providing accurate estimates of biomass. The results reinforce the importance of considering roots in biomass estimates and indicate high potential of mixed species restoration plantations in subtropical regions to mitigate the greenhouse effect.