Modeling the leadership – project performance relation: radial basis function,Gaussian and Kriging methods as alternatives to linear regression

The purpose of this paper is to analyze alternative forecasting methods that produce results at least similar to or better than linear regression (MLR) that can be used in the modeling of social systems. While organizations may be considered as typically non-linear systems, the common feature of most models found in literature continues to be the use of linear regression techniques. From a case study, advanced statistical methods of Gaussian and Kriging are evaluated, as well as an artificial intelligence (AI) tool, the radial basis function (RBF). The results show the best performance of the suggested methods compared to MLR, especially RBF, because of its uniform prediction behavior throughout all ranges of evaluation. These techniques, although somewhat unconventional in social systems modeling, present a potential contribution in increasing the accuracy and precision of the predictions allowing a more accurate assessment of the impact of certain strategies on the project performance to be made before the allocation of material, human and financial resources.     

Characterizing landscape changes in central Rondonia using Landsat TM imagery

An analysis of landscape changes in a region of pioneer settlements in central Rondonia, western Brazilian Amazon, was derived from Landsat TM data. Total deforested area increased from 206 x 103 ha in 1977, to 565 x 103 ha in 1985 and to 1210 x 103 ha, or 35.5% of the region, in 1995. Eighty-one per cent of the total 1995 deforestation had occurred in regions within 12.5km from areas of pioneer colonization deforested by 1977. Deforested area exceeded 79% in regions within 12.5km from the region's first road.     

Short‐term effects in a reduced flow stretch: The case of the Antas River in South Brazil

The building of adduction channels (penstocks) that conduct water from reservoirs to turbines, which are located kilometres from the dam, is becoming common, optimizing the electricity generation in small dams. This design creates a river stretch with reduced discharge between the dam and the powerhouse. This study evaluates the short‐term impacts of the below‐dam decrease in river flow on fish assemblages. Samples were collected in the reduced flow stretch of the Castro Alves Hydropower Plant (Antas River, Rio Grande do Sul, Brazil) before the reservoir started operating (January 2008; mean discharge of 103.7 m³/s) and immediately after operation began (March 2008; mean discharge of 12.4 m³/s). Sampling was conducted in distinct habitats of the reduced flow stretch (slow waters—gillnets, sand beaches—seining nets, structured littoral—electrofishing, and fast waters—cast nets) with a strongly standardized effort. The attributes of the fish assemblages were not negatively affected by the flow reduction in any habitat sampled. However, distinct changes in the spatial structure were observed considering the different types of habitat predominantly used by the species, which represents an entire reorganization of the fish assemblages in the short term. It is fundamental that these short‐term aspects be considered in the licensing of hydropower plants in addition to the long‐term changes.     

Polyunsaturated Fatty Acid Concentrates of Carp Oil: Chemical Hydrolysis and Urea Complexation

The aims of this study were to compare three treatments in the chemical hydrolysis reaction of bleached oil from carp (Cyprinus carpio) heads and to obtain polyunsaturated fatty acid concentrates by urea complexation. The three treatments were carried out with different oil:ethanol molar ratios. In the treatment with a 1:39 molar ratio, a higher yield of free fatty acids was found. These fatty acids were submitted to urea complexation (−10 °C for 20 h, and urea–fatty acid ratio of 4.5–1). There was a 31.4% increase in monounsaturated and polyunsaturated fatty acids (MUFA and PUFA) content and a 75% decrease in saturated fatty acids (SAF) content. An increase of 85.4% in the EPA + DHA content was found. The non-urea complexing fraction can be considered a rich source of MUFA and PUFA with a total amount of 88.9%.     

Extensional rheology of raw natural rubber from new clones of Hevea brasiliensis

Natural rubber (NR) is a biopolymer whose properties depend on the molecular structure of the 1,4‐cis polyisoprene chains, nonrubber constituents, environmental conditions, etc. NR has been characterized by Mooney viscosity, Wallace plasticity, nitrogen content (%N). However, these cannot effectively account for clone's differences. The aim of this work is to use extensional rheology to characterize and differentiate NR samples as for clone type and the season of the year in comparison to the traditional characterizations. Three IAC 300 series and RRIM 600 clones of Hevea brasiliensis tapped between October 2006 (Oct_06) and August 2008 (Aug_08) were investigated. IAC 329 clones showed the least susceptibility to seasonal changes, whereas RRIM 600 was the most influenced. An opposite trend between extensional viscosity (η_E) and %N was established. The former was very sensitive to changes in the molecular structure of NR, being fundamental for monitoring purposes and strategic development of new rubber tree clones. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers