Development and initial validation of the determinants of physical activity questionnaire

Background: Physical activity interventions are more likely to be effective if they target causal determinants of behaviour change. Targeting requires accurate identification of specific theoretical determinants of physical activity. Two studies were undertaken to develop and validate the Determinants of Physical Activity Questionnaire. Methods In Study 1, 832 male and female university staff and students were recruited from 49 universities across the UK and completed the 66-item measure, which is based on the Theoretical Domains Framework. Confirmatory factor analysis was undertaken on a calibration sample to generate the model, which resulted in a loss of 31 items. A validation sample was used to cross-validate the model. 20 new items were added and Study 2 tested the revised model in a sample of 466 male and female university students together with a physical activity measure. Results: The final model consisted of 11 factors and 34 items, and CFA produced a reasonable fit χ2 (472) = 852.3, p < .001, CFI = .933, SRMR = .105, RMSEA = .042 (CI = .037-.046), as well as generally acceptable levels of discriminant validity, internal consistency, and test-retest reliability. Eight subscales significantly differentiated between high and low exercisers, indicating that those who exercise less report more barriers for physical activity. Conclusions: A theoretically underpinned measure of determinants of physical activity has been developed with reasonable reliability and validity. Further work is required to test the measure amongst a more representative sample. This study provides an innovative approach to identifying potential barriers to physical activity. This approach illustrates a method for moving from diagnosing implementation difficulties to designing and evaluating interventions

Relationships Between Habitat and Snag Characteristics and the Reproductive Success of the Brown-headed Nuthatch (Sitta pusilla) in Eastern Texas.

Habitat use and reproductive success of the Brown-headed Nuthatch (Sitta pusilla Latham) were studied in East Texas during the 2001-2002 breeding seasons. We compared nest cavity selection at used and randomly selected non-used areas. Height of nest trees, midstory density, and percent leaf litter were negatively correlated with nest site selection. Brown-headed Nuthatches showed a strong preference for short snags; yet placed their nest cavity entrances near the top ofthe snags. While nuthatches may be selecting for habitats with little or no midstory density, percent of leaf litter in the nest sites is most likely the consequence of frequent burning. No significant differences among habitat variables and snag characteristics were found between successful and failed nest cavities. Additionally, no habitat variables were correlated with the number of chicks fledged per nest. Predation was the major cause of nest failure in this study

Shear bands and cracking of metallic glass plates in bending

The thickness dependence of yielding and fracture of metallic glass plates subjected to bending is considered in terms of the shear band processes responsible for these properties. We argue that the shear band spacing (and length) scales with the thickness of the plate because of strain relaxation in the vicinity of the shear band at the surface. This is consistent with recent measurements of shear band spacing versus sample size. We also argue that the shear displacements in the shear band scale with the shear band length and plate thickness, thus causing cracks to be initiated in thicker plates at smaller bending strains. This leads to fracture bending strains that decrease markedly with increasing plate thickness, consistent with recent experiments. These results suggest that amorphous metals in the form of foams might have superior ductility and toughness

Do Red-Cockaded Woodpeckers Select Cavity Trees Based on Chemical Composition of Pine Resin?

We examined resin chemistry of loblolly (Pinus taeda) and shortleaf (P. echinata) pines selected as cavity trees by Red-cockaded Woodpeckers (Picoides borealis) in eastern Texas. We sampled resin from (1) pines selected by Red-cockaded Woodpeckers that contained naturally excavated active cavities, (2) pines selected by forest biologists that contained artificially installed cavity inserts and were actively being used by Red-cockaded Woodpeckers, and (3) control pines of similar age and appearance to the active cavity trees. We hypothesized that if woodpeckers are inducing a change in resin chemistry by excavating resin wells, this change should appear in active cavity trees selected by woodpeckers and trees selected by biologists, but not in control pines. If woodpeckers are selecting pines that have specific resin chemistry, concentrations of some resin components in active cavity trees selected by the woodpeckers for natural cavity excavation should be different from both control pines and pines selected by biologists. A large diterpene acid peak containing an isopimariclevopimaric- palustric methyl-ester mix in active natural cavity trees was approximately 20% greater than controls and 22% greater than trees with artificial cavities. None of the other eight resin chemicals differed among treatments. The activity of Red-cockaded Woodpeckers at resin wells did not appear to affect the composition of cavity tree resin. Woodpeckers, however, may select pines with specific resin chemistries for cavity trees

Social influence processes on adolescents' food likes and consumption: the role of parental authoritativeness and individual self-monitoring

This cross-sectional study investigated how parents and friends influence adolescents’ food likes and consumption. 709 adolescent-parent and 638 adolescent-friend dyads completed a questionnaire, allowing us to compare target-parent and target-friend resemblances both on food likes and consumption, while distinguishing between cultural influence and dyadic unique influence. In addition, we identified two psychosocial predictors of resemblance, namely parenting style and adolescents' self-monitoring. As expected, results indicated that authoritative parenting style increased target-parent resemblance in food likes (directly) and consumption (indirectly), and self-monitoring orientation increased target-friend resemblance in food likes (directly) and consumption (indirectly). We also showed that target-friend resemblance was more culture-based than target-parent resemblance, suggesting that parental influence is more specific to the dyadic relation than is peer influence

Red-Cockaded Woodpeckers and Silvicultural Practice: is Uneven-Aged? Silviculture Preferable to Even-Aged

The endangered red-cockaded woodpecker (Picoides borealis) has become a high-profile management issue in the southeastern United States. Suitable habitat consists of mature to old pine, or mixed pine-hardwood forest, with minimal hardwood midstory vegetation. Loss of habitat, detrimental silvicultural practices, and changes in the fire regime have resulted in small fragmented populations, most of which have been declining precipitously in recent decades (Costa and Escano 1989, Conner and Rudolph 1989). The current population of l0-12 thousand birds occurs across much of the original range from Virginia and Florida west to Oklahoma and Texas (James 1995). However, populations are restricted to isolated tracts of suitable habitat, primarily on public lands. Consequently, the debate over the future of this once abundant species, characteristic of fire climax pine forests, has focused primarily on management strategies for the species by the U.S. Forest Service (USFS), the agency responsible for the majority of the public forest lands in the region

Red-cockaded Woodpecker Colony Status and Trends On the Angelina, Davy Crockett and Sabine National Forests

Abundant hardwood midstory, colony isolation, and habitat fragmentation are believed to be the causes for severe population declines of red-cockaded woodpeckers on three national forests in eastern Texas

Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) Infestation Rates Related to Site and Stand Characteristics in Nacogdoches County, Texas

Twenty-two pine stands with a variety of site and stand characteristics and management strategies were analyzed using discriminant analysis to determine factors which influence Nantucket pine tip moth infestations. A whole-tree sequential sampling scheme designed to estimate absolute infestation rates (±5%) was used. An 8% infestation rate was used as the dividing line between high and low tip moth infestations. A sequential sampling program was used in the field to estimate populations. Absolute infestation rates (P ± 5%), were obtained through random selection of pines for whole-tree sampling. Four equations were developed which gave 91% correct classification of initial data. The discriminating variables included site preparation intensity, pine height, pine age, site index, soil texture at 61 cm depth, depth of A horizon multiplied by soil texture code, and depth of clay