Confirmatory factorial analysis of the children´s attraction to physical activity scale (capa).

AIM: Attraction to physical activity (PA) is an important contributor to children´s intrinsic motivation to engage in games, and sports. Previous studies have supported the utility of the children´s attraction to PA scale (CAPA) (Brustad, 1996) but the validity of this measure for use in Portugal has not been established. The purpose of this study was to cross-validate the shorter version of the CAPA scale in the Portuguese cultural context. METHODS: A sample of 342 children (8--10 years of age) was used. Confirmatory factor analyses using EQS software ( version 6.1) tested t hree competing measurement models: a single--factor model, a five factor model, and a second order factor model. RESULTS: The single--factor model and the second order model showed a poor fit to the data. It was found that a five-factor model similar to the original one revealed good fit to the data (S--B χ 2 (67) =94.27,p=0.02; NNFI=0.93; CFI=0.95; RMSEA=0.04; 90%CI=0.02;0.05). CONCLUSIONS: The results indicated that the CAPA scale is valid and appropriate for use in the Portuguese cultural context. The availability of a valid scale to evaluate attraction to PA at schools should provide improved opportunities for better assessment and understanding of children´s involvement in PA.

Effects of a 5-month football program on perceived psychological status and body composition of overweight boys.

The effects of a 5-month intervention of football instruction and practice on the perceived psychological status and body composition of overweight boys were examined. Twelve boys (8-12 years; body mass index ≥ 85th percentile) participated in a structured 5-month football program, consisting of four weekly 60-90 min sessions with mean heart rate > 80%HRmax [football group (FG)]. A control group (CG) included eight boys of equivalent age from an obesity clinic located in the same area as the school. Both groups participated in two sessions of 45-90-min physical education per week at school. Indicators of perceived psychological status included body image, self-esteem, attraction to participation in physical activity, and perceived physical competence measured with standardized questionnaires. Body composition was evaluated using dual-energy X-ray absorptiometry. From baseline through 5 months, FG improved (P < 0.05) in all indicators of psychological status (%Δ = +11.7 to +29.2%) compared with CG (%Δ = -32.1 to +0.5%). Changes in percentage body fat and lean body mass, however, did not differ between FG and CG. The findings suggest that a 5-month football intervention program was effective in improving the psychological status of overweight boys but did not significantly alter body composition.

Probing individual quantum dots: noise in self-assembled systems.

In this work we explore the noise characteristics in lithographically-defined two terminal devices containing self-assembled InAs/InP quantum dots. The experimental ensemble of InAs dots show random telegraph noise (RTN) with tuneable relative amplitude-up to 150%-in well defined temperature and source-drain applied voltage ranges. Our numerical simulation indicates that the RTN signature correlates with a very low number of quantum dots acting as effective charge storage centres in the structure for a given applied voltage. The modulation in relative amplitude variation can thus be associated to the altered electrostatic potential profile around such centres and enhanced carrier scattering provided by a charged dot.

Vortex configuration flow cell based on low-temperature cofired ceramics as a compact chemiluminescence microsystem.

The integration of optical detection methods in continuous flow microsystems can highly extend their range of application, as long as some negative effects derived from their scaling down can be minimized. Downsizing affects to a greater extent the sensitivity of systems based on absorbance measurements than the sensitivity of those based on emission ones. However, a careful design of the instrumental setup is needed to maintain the analytical features in both cases. In this work, we present the construction and evaluation of a simple miniaturized optical system, which integrates a novel flow cell configuration to carry out chemiluminescence (CL) measurements using a simple photodiode. It consists of a micromixer based on a vortex structure, which has been constructed by means of the low-temperature cofired ceramics (LTCC) technology. This mixer not only efficiently promotes the CL reaction due to the generated high turbulence but also allows the detection to be carried out in the same area, avoiding intensity signal losses. As a demonstration, a flow injection system has been designed and optimized for the detection of cobalt(II) in water samples. It shows a linear response between 2 and 20 microM with a correlation of r > 0.993, a limit of detection of 1.1 microM, a repeatability of RSD = 12.4%, and an analysis time of 17 s. These results demonstrate the suitability of the proposal to the determination of compounds involved in CL reactions by means of an easily constructed versatile device based on low-cost instrumentation.

Magnetic characterization of microscopic particles by MO-SNOM.

This paper reports on the development of a magneto-optical scanning near-field optical microscope and the experimental near-field study of the domain structure for a model magnetic particle of 16 x 16 micro m(2) of a Co(70.4)Fe(4.6)Si(15)B(10) amorphous thin film, deposited on a silicon substrate. We present the topographic, optical and magneto-optical differential susceptibility (MODS) images of the particle. Imaging by using the local MODS reveals the domain structure. These images are also used for positioning the tip in order to acquire local hysteresis loops, with submicrometre spatial resolution.