The relationship between motor performance and peer relations in 9- to 12-year-old children.

BACKGROUND: Poor motor skills have been associated with peer relationship difficulties, with lower peer preference and greater likelihood of suffering from withdrawal and low self-worth. Most research into these relationships has focused upon children with motor problems and on activities involving physical skills (play/sport). The current study examined the link between motor performance and peer relations in 9- to 12-year-old children in both physical and non-physical (schoolwork) settings using a community sample. METHODS: Participants were 192 school children whose motor performance was tested using the Movement Assessment Battery for Children. Peer acceptance was assessed using the Peer Rating Scale and teachers completed the Peer Exclusion subscale of the Child Behaviour Scale to indicate each child's peer status. Children were also asked to indicate their level of physical activity and their perceived freedom in leisure using self-report questionnaires. RESULTS: Children with poor motor performance had lower levels of physical activity, and freedom in leisure and were less preferred by their peers in both play and classroom settings. These effects were stronger for boys than for girls. Teacher indicated that children with poorer motor skills experienced higher levels of peer rejection in the classroom setting. When motor performance was separated into fine- and gross-motor performance it was found that only the latter was significantly correlated with peer acceptance in the play context but that fine-motor skills contributed significantly to variance in teacher ratings of peer exclusion in the classroom setting. CONCLUSIONS: The results support and extend earlier findings that children with poor motor performance are less accepted by their peers in play settings and provide some support for this extending to settings involving low levels of physical activity (classroom settings). The results similarly support previous findings that motor performance is associated with perceived freedom in leisure and with the likelihood of participating in active pursuits.

Reconstruction-of-difference (RoD) imaging for cone-beam CT neuro-angiography.

Timely evaluation of neurovasculature via CT angiography (CTA) is critical to the detection of pathology such as ischemic stroke. Cone-beam CTA (CBCT-A) systems provide potential advantages in the timely use at the point-of-care, although challenges of a relatively slow gantry rotation speed introduce tradeoffs among image quality, data consistency and data sparsity. This work describes and evaluates a new reconstruction-of-difference (RoD) approach that is robust to such challenges. A fast digital simulation framework was developed to test the performance of the RoD over standard reference reconstruction methods such as filtered back-projection (FBP) and penalized likelihood (PL) over a broad range of imaging conditions, grouped into three scenarios to test the trade-off between data consistency, data sparsity and peak contrast. Two experiments were also conducted using a CBCT prototype and an anthropomorphic neurovascular phantom to test the simulation findings in real data. Performance was evaluated primarily in terms of normalized root mean square error (NRMSE) in comparison to truth, with reconstruction parameters chosen to optimize performance in each case to ensure fair comparison. The RoD approach reduced NRMSE in reconstructed images by up to 50%-53% compared to FBP and up to 29%-31% compared to PL for each scenario. Scan protocols well suited to the RoD approach were identified that balance tradeoffs among data consistency, sparsity and peak contrast-for example, a CBCT-A scan with 128 projections acquired in 8.5 s over a 180° + fan angle half-scan for a time attenuation curve with ~8.5 s time-to-peak and 600 HU peak contrast. With imaging conditions such as the simulation scenarios of fixed data sparsity (i.e. varying levels of data consistency and peak contrast), the experiments confirmed the reduction of NRMSE by 34% and 17% compared to FBP and PL, respectively. The RoD approach demonstrated superior performance in 3D angiography compared to FBP and PL in all simulation and physical experiments, suggesting the possibility of CBCT-A on low-cost, mobile imaging platforms suitable to the point-of-care. The algorithm demonstrated accurate reconstruction with a high degree of robustness against data sparsity and inconsistency.

Decrease in hepatic blood flow during furosemide-induced diuresis.

The effect of furosemide on hepatic hemodynamics was investigated using electromagnetic flow probes positioned around the hepatic-portal vein and common hepatic artery of anesthetized dogs. Furosemide administration induced a vigorous diuresis and concomitantly decreased total hepatic blood flow. Hepatic arterial blood remained relatively stable. Thus, the decrease in total hepatic blood flow was due primarily to a decrease in portal blood flow. When furosemide was given to animals with ureters ligated to prevent extracellular volume contraction, the drug did not reduce total hepatic blood flow, portal blood flow or hepatic arterial blood flow. Thus, furosemide induces a decrease in total hepatic blood flow that appears to involve a mechanism dependent upon the volume contraction produced by the diuretic. The contraction causes a reduction in venous blood flow but not arterial blood flow to the liver.