Changes in the Dynamics of Postural and Locomotor Control as a Result of Varying Task Demands

The aim of this study was to examine changes in postural and locomotor control under varying task demands. Three experiments were designed to address the impact that fast walking had on standing posture over time, slow walking had on gait dynamics over time, and the extent to which gait speed interacts with the ability to walk randomly. For experiment I, the aim was to identify the time course in which postural adaptation occurred while walking at faster than preferred speeds. Postural motion was assessed at specific intervals over a 35-min walking trial. Findings revealed that walking at a faster speed increased the amount, variability, and structure (Approximate Entropy-ApEn) of postural motion compared to baseline assessments. Subsequent trials following baseline assessments revealed a leveling-off for specific center of pressure (COP) variables and decline in path length, although heart rate (HR) and rate of perceived exertion (RPE) increased over the entire walking trial. In experiment II, the aim was to examine changes in stride-to-stride variability over time while walking at slower than preferred speeds. The results revealed an increased stride-to-stride variability and signal regularity (lower ApEn) during walking at 80% preferred walking speed (PWS) compared to PWS. After 10-15 mins a decrease stride-to-stride variability and increase in signal irregularity was seen. Changes leveled-off for the remainder of the session. Experiment III was designed to examine the effect that intentionally increasing variability (random) had on gait dynamics. Participants were asked to vary their gait while walking on a treadmill at three different speeds. The results revealed gait speed was a significant factor in the amount of variability (CV, range), with higher levels produced during the slower speed than at PWS and the faster speed. Higher levels of complexity (higher SampEn) were seen in stride time and knee joint motion during the random condition irrespective of gait speed. Overall, young adults are able to walk at speeds faster or slower than preferred as well as increase gait variability when instructed. These changes in postural and locomotor dynamics reveal that a healthy motor control system can quickly adapt to the task demands imposed upon it

Numerical analysis of cement panels reinforced with galvanized iron or polypropylene meshes

This paper deals with the numerical analysis of panels reinforced with galvanized iron (GI) or polypropylene (PP) meshes. It has been a common practice to use galvanized iron meshes as reinforcement in panels and is popularly called as ferrocement panels. Elevated humidity level and presence of salts can lead to corrosion of these galvanized iron meshes, leading to reduced service life. A rust-freepolypropylene mesh can be used as an alternate to the steel mesh. This paper presents numerical analysis in ANSYS Workbench based on an experimental study published in the literature” Comparative study of ferrocement panels reinforced with galvanized iron and polypropylene meshes”. A total of 16 rectangular panels tested in flexure was analyzed. Out of 16 panels, 8 were reinforced with GI mesh and 8 with PP mesh. The specimens were simply supported on two short edges and subjected to four-point bending. The parameters investigated include thickness of panels, volume fraction and the material of the mesh. All the GI mesh panels showed better strength than the corresponding PP mesh reinforcedcement panels. However, PP mesh panels exhibited better ductility as compared to GI mesh panels. An increase of 54% is noticed in 40mm thick panels reinforced with GI mesh, when compared to 20mm thick panels. Similarly, an increase of 83% is noticed in 40mm thick panels reinforced with PP mesh, when compared to 20mm thick panels. The results of numerical analysis were found to be comparable with the corresponding experimental results

FRENCH QUALITY AND ECO-LABELING SCHEMES: DO THEY ALSO BENEFIT THE ENVIRONMENT?

The environmental effects of various 'quality' and 'eco-labeling' programs in the Midi-Pyrenees region of the south of France are analyzed, using factor analysis, analysis of variance, and qualitative analysis. Implications for agri-environmental policies on both sides of the Atlantic are discussed.Environmental Economics and Policy,

‘Quality’ and ‘Eco-labeling’ of Food Products in France and the United States

In this paper, we explain the history of French and US quality and eco-Iabeling schemes, the current status and issues facing these schemes in agriculture, and the relevance ofthe French experience to the US

Assessing Population Trends of New-Hampshire Forest Birds: Local vs Regional Patterns

We examined the changes in abundance between 1969 and 1986 of 19 forest-dwelling, mostly migratory bird species breeding in New Hampshire at 2 different scales: one local (an intensively studied 10-ha plot in unfragmented forest) and the other regional (Breeding Bird Surveys statewide). Twelve of the 19 species exhibited similar trends at both scales. Eight neither increased nor decreased, and 4 (Least Flycatcher, Winter Wren, Wood Thrush, and Swainsoh\u27s Thrush) declined significantly. Others increased, decreased, or re-mained steady at one or the other scale. Overall, more species declined than increased both locally (8 vs. 1) and regionally (5 vs. 1). Comparisons of these patterns, combined with results of intensive studies at the local level, suggest that changes in food abundance and in vege-tation structure related to forest succession on the breeding grounds, along with other pro-cesses that influence bird reproductive success and survivorship, are the most plausible explanations for most of the observed trends. Winter mortality was also identified as affecting breeding abundances, but only in short-distance migrant and permanently resident species. We have no evidence to indicate that the numbers of long-distance migrants were affected by events in their Neotropical wintering areas, although this possibility is difficult to assess from breeding-ground data. We urge caution in attributing declines of breeding forest migrant birds to tropical deforestation or similar causes until we either can eliminate alternate explanations that involve breeding-season events or have available critically needed demo-graphic information on migrant populations in their wintering areas

Comparison of Prices for \u27Organic\u27 and \u27Conventional\u27 Grains and Soybeans in the Northern Great Plains and Upper MIdwest: 1995-2000

Price premiums for organic crops drew the attention of increasing numbers of farmers in the Northern Great Plains and Upper Midwest during the 1990s. Continuing low prices for crops grown with \u27conventional\u27 farming methods during the late 1990s caused a growing number of farmers to explore the possibilities of switching to organic methods and obtaining organic certification. As part of the sustainable agriculture research program in the Economics Department at South Dakota State University (SDSU), we have been comparing \u27organic\u27 and \u27conventional\u27 crop prices over the past six years. This pamphlet contains an update of the price comparisons through 2000. The information should be of use to farmers and others considering management changes and investments related to organic agriculture, as well as to policy makers

Generative Roles: Assessing Sustained Involvement in Generativity

Abstract Generative roles refer to observable, behavioral community positions that embody aspects of teaching and nurturing that are central to the concept of generativity. Two studies are presented that describe generative roles in a community sample and provide psychometric data for a short index of generative roles. The first study also provides reliability and validity data from a second informant. The second study examines generative roles at different stages of adolescence and adulthood. Participants were asked 8 yes/no questions about a variety of community roles. The validity of the GRI was supported by significant correlations with the Loyola Generativity Scale, a widely used measure of generative concern (r=.33), and measures of related constructs. The correlations were similar across age categories. The Generative Roles Index has good psychometric qualities and complements existing measures of generativity by providing behavioral, observable data on roles