Variables associated with children's physical activity levels during recess : the A-CLASS project

Background
School recess provides a daily opportunity for children to engage in physically active behaviours. However, few studies have investigated what factors may influence children's physical activity levels in this context. Such information may be important in the development and implementation of recess interventions. The aim of this study was to investigate the association between a range of recess variables and children's sedentary, moderate and vigorous physical activity in this context.

Methods
One hundred and twenty-eight children (39% boys) aged 9-10 years old from 8 elementary schools had their physical activity levels observed during school recess using the System for Observing Children's Activity and Relationships during Play (SOCARP). Playground variables data were also collected at this time. Multilevel prediction models identified variables that were significantly associated with children's sedentary, moderate and vigorous physical activity during recess.

Results
Girls engaged in 13.8% more sedentary activity and 8.2% less vigorous activity than boys during recess. Children with no equipment provision during recess engaged in more sedentary activity and less moderate activity than children provided with equipment. In addition, as play space per child increased, sedentary activity decreased and vigorous activity increased. Temperature was a significant negatively associated with vigorous activity.

Conclusions
Modifiable and unmodifiable factors were associated with children's sedentary, moderate and vigorous physical activity during recess. Providing portable equipment and specifying areas for activities that dominate the elementary school playground during recess may be two approaches to increase recess physical activity levels, though further research is needed to evaluate the short and long-term impact of such strategies.

Descriptive model of the offence process of women violent offenders : distal background variables

The literature indicates two areas of growing concern in regard to the perpetration of violence by women. One is that the incidence of violence perpetrated by women is increasing across jurisdictions. The other is that despite their growing numbers the knowledge and understanding of violent women has been greatly hindered by the general lack of empirical investigation of this population. The present study uses a grounded theory approach to develop a preliminary descriptive model of the offence process of women violent offenders. The women's violent offence model (WVOM) has four distinct levels or phases. The current article addresses the first of these in detail, consisting of the distal background variables. This phase of the model includes experiences of childhood and adolescence, providing preliminary insight into the more stable distal predispositional factors underlying women's violent offending.

It's the economy : the effect of macroeconomic variables of the rate of suicide

Background. There are a large number of factors mediating suicide. Many studies have searched for a direct causal relationship between economic hardship and suicide, however, findings have been varied.

Method. Suicide data was obtained from the Australian Bureau of Statistics for the period between January 1968 and August 2002. These were correlated with a suite of macroeconomic data including housing loan interest rates, unemployment rates, days lost to industrial disputes, Consumer Price Index, gross domestic product, and the Consumer Sentiment Index.

Results. A total of 51 845 males and 16 327 females committed suicide between these dates. There were significant associations between suicide rates and eleven macroeconomic indicators for both genders in at least one age range. Data was divided into male and female and five age ranges and pooled ages. Analyses were conducted on these 132 datasets resulting in 80 significant findings. The data was generally stronger for indices measuring economic performance than indices measuring consumers’ perceptions of the state of the economy. A striking difference between male and female trends was seen. Generally, male suicide rates increased with markers of economic adversity, while the opposite pattern was seen in females. There were significantly different patterns in age-stratified data, with for example higher housing loan interest rates having a positive association with suicide in younger people and a negative association in older age groups.

Conclusion. Macroeconomic trends are significantly associated with suicide. The patterns in males and females are very different, and there are further substantial age-related differences.

Forecasting construction demand : a vector error correction model with dummy variables

Modelling the level of demand for construction is vital in policy formulation and implementation as the construction industry plays an important role in a country’s economic development process. In construction economics, research efforts on construction demand modelling and forecasting are various, but few researchers have considered the impact of global economy events in construction demand modelling. An advanced multivariate modelling technique, namely the vector error correction (VEC) model with dummy variables, was adopted to predict demand in the Australian construction market. The results of prediction accuracy tests suggest that the general VEC model and the VEC model with dummy variables are both acceptable for forecasting construction economic indicators. However, the VEC model that considers external impacts achieves higher prediction accuracy than the general VEC model. The model estimates indicate that the growth in population, changes in national income, fluctuations in interest rates and changes in householder expenditure all play significant roles when explaining variations in construction demand. The VEC model with disturbances developed can serve as an experimentation using an advanced econometrical method which can be used to analyse the effect of specific events or factors on the construction market growth.

Endogenous parathyroid hormone is associated with reduced cartilage volume in vivo in a population-based sample of adult women

Objectives Animal and in vitro studies suggest that parathyroid hormone (PTH) may affect articular cartilage. However, little is known of the relationship between PTH and human joints in vivo.

Design Longitudinal.

Setting Barwon Statistical Division, Victoria, Australia.

Participants 101 asymptomatic women aged 35–49 years (2007–2009) and without clinical knee osteoarthritis, selected from the population-based Geelong Osteoporosis Study.

Risk factors Blood samples obtained 10 years before (1994–1997) and stored at −80°C for random batch analyses. Serum intact PTH was quantified by chemiluminescent enzyme assay. Serum 25-hydroxyvitamin D (25(OH)D) was assayed using equilibrium radioimmunoassay. Models were adjusted for age, bone area and body mass index; further adjustment was made for 25(OH)D and calcium supplementation.

Outcome Knee cartilage volume, measured by MRI.

Results A higher lnPTH was associated with reduced medial—but not lateral—cartilage volume (regression coefficient±SD, p value: −72.2±33.6 mm3, p=0.03) after adjustment for age, body mass index and bone area. Further sinusoidal adjustment (−80.8±34.4 mm3, p=0.02) and 25(OH)D with seasonal adjustment (−72.7±35.1 mm3, p=0.04), calcium supplementation and prevalent osteophytes did not affect the results.

Conclusions A higher lnPTH might be detrimental to knee cartilage in vivo. Animal studies suggest that higher PTH concentrations reduce the healing ability of cartilage following minor injury. This may be apparent in the presence of increased loading, which occurs in the medial compartment, placing the medial cartilage at higher risk for injury.

Direct methods for distinction between endogenous and exogenous erythropoietin

Since the commercialization of the first recombinant human erythropoietin (rhEPO) product (epoetin-a) in 1989 as a treatment for acute anemia, rhEPO detection has represented a continuous challenge for the anti-doping fight. Indeed, it appeared rapidly that this ergogenic hormone would be abused by athletes looking for an artificial performance enhancer. Hemoglobin is one of the principal modulators of aerobic power [1, 2] and, consequently, of performance in endurance sports [3]. By stimulating the red blood cells production, EPO is known to raise hemoglobin concentration in a dose-dependant and predictable way. Therefore, this hormone soon became one of the athletes most popular doping agent. Since 1984, all forms of blood doping in sport have been officially banned. In 1990, the IOC medical commission, which was in charge of the anti-doping regulations, added rhEPO to the list of the prohibited drugs in sports, even if a direct test allowing to detect the molecule became available a decade after only.

Mobility of people with retinitis pigmentosa as a function of vision and psychological variables

We investigated the mobility performance of subjects with retinitis pigmentosa (RP) as a function of clinical measures of residual vision and psychological variables. We found a highly significant correlation between clinical measures of residual vision and mobility. Pelli-Robson contrast sensitivity and residual visual field together explained 64% of the variance in mobility performance in an indoor shopping mall. We suggest a simple new clinical method of scoring the visual field for predicting mobility performance, the RP Concentric Field Rating. The RP Concentric Field Rating alone explained 60% of the variance in mobility performance. In spite of expectations derived from reading the recent literature, we did not find a significant correlation between psychological variables and mobility performance in a group of subjects with RP.

A critical evaluation and comparison of two formative measures of system quality using criterion variables

Evaluating the validity of formative variables has presented ongoing challenges for researchers. In this paper we use global criterion measures to compare and critically evaluate two alternative formative measures of System Quality. One model is based on the ISO-9126 software quality standard, and the other is based on a leading information systems research model. We find that despite both models having a strong provenance, many of the items appear to be non-significant in our study. We examine the implications of this by evaluating the quality of the criterion variables we used, and the performance of PLS when evaluating formative models with a large number of items. We find that our respondents had difficulty distinguishing between global criterion variables measuring different aspects of overall System Quality. Also, because formative indicators “compete with one another” in PLS, it may be difficult to develop a set of measures which are all significant for a complex formative construct with a broad scope and a large number of items. Overall, we suggest that there is cautious evidence that both sets of measures are valid and largely equivalent, although questions still remain about the measures, the use of criterion variables, and the use of PLS for this type of model evaluation.