The effect of anxiety on anticipation, allocation of attentional resources, and visual search behaviours.

Successful sports performance requires athletes to be able to mediate any detrimental effects of anxiety whilst being able to complete tasks simultaneously. In this study, we examine how skill level influences the ability to mediate the effects of anxiety on anticipation performance and the capacity to allocate attentional resources to concurrent tasks. We use a counterbalanced, repeated measures design that required expert and novice badminton players to complete a film-based anticipation test in which they predicted serve direction under high- and low-anxiety conditions. On selected trials, participants completed an auditory secondary task. Visual search data were recorded and the Mental Readiness Form v-3 was used to measure cognitive anxiety, somatic anxiety and self-confidence. The Rating Scale of Mental Effort was used to measure mental effort. The expert players outperformed their novice counterparts on the anticipation task across both anxiety conditions, with both groups anticipation performance deteriorating under high- compared to low-anxiety. This decrease across anxiety conditions was significantly greater in the novice compared to the expert group. High-anxiety resulted in a shorter final visual fixation duration for both groups when compared to low-anxiety. Anxiety had a negative impact on secondary task performance for the novice, but not the expert group. Our findings suggest that expert athletes more effectively allocated attentional resources during performance under high-anxiety conditions. In contrast, novice athletes used more attentional resources when completing the primary task and, therefore, were unable to maintain secondary task performance under high-anxiety.

Identifying the causal mechanisms of the quiet eye.

Scientists who have examined the gaze strategies employed by athletes have determined that longer quiet eye (QE) durations (QED) are characteristic of skilled compared to less-skilled performers. However, the cognitive mechanisms of the QE and, specifically, how the QED affects performance are not yet fully understood. We review research that has examined the functional mechanism underlying QE and discuss the neural networks that may be involved. We also highlight the limitations surrounding QE measurement and its definition and propose future research directions to address these shortcomings. Investigations into the behavioural and neural mechanisms of QE will aid the understanding of the perceptual and cognitive processes underlying expert performance and the factors that change as expertise develops.

The effect of stimulus intensity on response time and accuracy in dynamic, temporally constrained environments.

The ability to make accurate judgments and execute effective skilled movements under severe temporal constraints are fundamental to elite performance in a number of domains including sport, military combat, law enforcement, and medicine. In two experiments, we examine the effect of stimulus strength on response time and accuracy in a temporally constrained, real-world, decision-making task. Specifically, we examine the effect of low stimulus intensity (black) and high stimulus intensity (sequin) uniform designs, worn by teammates, to determine the effect of stimulus strength on the ability of soccer players to make rapid and accurate responses. In both field- and laboratory-based scenarios, professional soccer players viewed developing patterns of play and were required to make a penetrative pass to an attacking player. Significant differences in response accuracy between uniform designs were reported in laboratory- and field-based experiments. Response accuracy was significantly higher in the sequin compared with the black uniform condition. Response times only differed between uniform designs in the laboratory-based experiment. These findings extend the literature into a real-world environment and have significant implications for the design of clothing wear in a number of domains.

Effect of completeness of revascularization on clinical outcome in patients with multivessel disease presenting with unstable angina who undergo percutaneous coronary intervention.

We evaluated the current short- and medium-term outcomes of complete revascularization, compared to culprit lesion percutaneous coronary intervention (PCI), in patients with multivessel coronary disease presenting with unstable angina. One hundred fifty-one patients with multivessel coronary disease presented to a tertiary cardiothoracic center with unstable angina/non-ST elevation myocardial infarction (UA/NSTEMI) between January 2000 and September 2001. In group A (n=71), the intended strategy was complete revascularization by multivessel PCI. In group B (n=80), culprit lesion PCI was intended despite the presence of other lesions amenable to PCI (B1) or due to confounding anatomical factors (B2). Clinical variables and endpoints were collected from patient notes, a dedicated database and telephone follow-up, and included recurrent stable and unstable angina, need for repeat PCI or elective coronary artery bypass graft, incidence of non-fatal myocardial infarction (MI) and death. Baseline characteristics were similar in each group. Procedural success was achieved in over 95% of cases in both groups with high stent implantation rates (>96%). There was no observed difference in mortality or incidence of MI between the groups. Compared to group A, more patients in group B1 had residual angina [22.8% (13/57) versus 9.9% (7/71); p=0.041] and required further PCI [17.5% (10/57) versus 7.0% (5/71); p=0.045]. There was a non-significant trend toward fewer readmissions for UA and less long-term antianginal medication in group A [38.0% (27/71) versus 52.6% (30/57); p=0.043]. Complete and culprit lesion revascularization by PCI are safe methods of treating patients with multivessel coronary disease presenting with UA/NSTEMI. Reductions in residual angina, repeat PCI and need for antianginal therapies suggest that complete revascularization should be the strategy of choice when possible.

Serological survey of measles and rubella immunity in Sydney preschool children.

OBJECTIVES: To estimate the prevalence of serological evidence of immunity to measles and rubella in preschool children in central and southern Sydney (NSW, Australia) and the prevalence of immunity in children with either documented or parentally reported immunization. METHODS: Geographical cluster random sampling was used to select children aged between 18 and 60 months to participate in the present study. Standardized interviews obtained information on each child's reported (by parents) immunization status and documentary evidence of immunization was recorded from the Personal Health Record. Venous blood was collected, serum was separated and stored frozen until tested. Measles and rubella antibodies were measured using ELISA, with either immunofluorescence or haemagglutination inhibition being used to clarify equivocal results. The study was conducted from 1992 to 1994 in conjunction with surveys of blood lead concentrations, iron status and micronutrient status. RESULTS: Parents of 726 of 953 children identified between 9 and 60 months of age agreed to participate in the lead, immunization, iron status and micronutrient studies. Sufficient blood for antibody testing was obtained from 580 children, aged 18 to 62 months at the time of collection. Parents reported that 94.7% (95% confidence interval (CI) 92.7-96.5%) of children had received a measles-mumps or measles-mumps-rubella (MMR) immunization. General practitioners administered 72.8% of these immunizations. The prevalence of serological evidence of immunity to measles and rubella was 88.8% (95% CI 86.2-91.4%) and 91.9% (95% CI 89.6-94.2%). respectively. There was documented evidence of measles and rubella immunization for 88.4% (95% CI 85.7-91.2%) and 86.4% (95% CI 83.4-89.3%) of children, respectively. Of children with documented measles immunization, 91.6% (95% CI 89.2-94.0%) had detectable measles antibody. Of children with documented rubella immunization 97.2% (95% CI 95.8-98.6%) had detectable rubella antibody. CONCLUSIONS: Measles and rubella immunization rates in central and southern Sydney are relatively high and most of these immunizations are provided by the private sector. Immunity to rubella in children with documented rubella immunization is at the level that would be expected from seroconversion studies. Immunity to measles in children with documented measles immunization is slightly lower than expected from seroconversion studies, highlighting the need for the second MMR immunization in preschool children, as well as making near universal immunization imperative if this disease is to be eradicated.

Opportunistic sampling from early childhood centres: a substitute for random sampling to determine lead and iron status of pre-school children?

This report compares the results from two sampling strategies used to determine the prevalence of elevated blood lead concentrations and iron status in 12-36 month old children in Central Sydney. The two methods were stratified random sampling using census collector districts and an opportunistic sampling strategy using client registers at Early Childhood Centres (ECCs). The response rates were 75.3% (n = 718 of whom 198 were aged 12-36 months) and 24.1% (n = 304) respectively. The geometric mean blood lead concentrations were 0.40 and 0.34 mumol/L respectively (p = 0.001). The traditional random sampling prevalence survey identified a significantly higher proportion of children with blood lead concentrations greater than 0.48 (OR = 0.61, 95% CI 0.40-0.93) and 0.72 mumol/L (OR = 0.44, 95% CI 0.21-0.92) compared to the simpler opportunistic survey. The median plasma ferritin concentration for both studies was 19 micrograms/L (p = 0.4). The prevalence of iron depletion, iron deficiency and iron deficiency anaemia was not significantly different between the two studies. In conclusion, opportunistic sampling through ECCs does not appear to be a substitute for the traditional random sampling prevalence surveys of determine the prevalence of elevated blood lead concentrations in pre-school children in Central Sydney. However, opportunistic sampling through ECCs may be an appropriate method for monitoring iron status, in particular iron depletion, in pre-school children in Central Sydney.

Intracoronary ultrasound.

Although contrast angiography is important in the diagnosis and treatment of atherosclerotic disease, it does have limitations. Intracoronary ultrasound more accurately assesses the amount of atherosclerosis and has given us new insights into the pathophysiology of coronary plaque accumulation and remodelling. It also allows the monitoring of therapeutic intervention. Intracoronary ultrasound is a new gold standard. It does not obviate the need for angiography but provides complementary information that enables us to perform optimal interventional procedures.

Plasma and serum micronutrient concentrations in preschool children.

The plasma concentrations of vitamin A, vitamin E, beta-carotene and serum concentrations of zinc, retinol-binding protein and prealbumin were examined for a random cluster sample, stratified by socioeconomic status, of 467 healthy preschool children. Children were aged 9-62 months; 44% were females. The mean plasma values were: vitamin A, 1.29 micromol l(-1); vitamin E, 18.9 micromol l(-1); and beta-carotene, 0.30 micromol l(-1). The mean serum values were: zinc, 13.9 micromol l(-1); retinol-binding protein, 25.5 mg l(-1); and prealbumin, 186.2 mg l(-1). The mean molar ratio of vitamin A to retinol-binding protein for the study group was 1.10. There were no differences in the mean values of any of the measured micronutrients between the genders. The results of this survey do not indicate that the prevalence of micronutrient deficiency in this preschool population is of public health significance.

Age-specific reference intervals for plasma vitamins A, E and beta-carotene and for serum zinc, retinol-binding protein and prealbumin for Sydney children aged 9-62 months.

Paediatric reference intervals for blood concentrations of certain nutrients are often based on either adult data or are derived from small samples of young children. Biochemical data were obtained from 467 randomly selected, healthy preschool children aged 9-62 months in Sydney, Australia. Data were obtained for plasma vitamins A, E and beta-carotene and for serum zinc, retinol-binding protein and prealbumin. Reference intervals based on the 2.5 and 97.5 centiles for age groups 9-23, 24-35, 36-47, 48-62 months and for the total group (9-62 months) were calculated. The 2.5-97.5 centiles for the whole group were: vitamin A, 0.7-1.8 mumol/l (20.05-51.56 micrograms/dl); vitamin E, 8-30 mumol/l (0.34-1.29 mg/dl); beta-carotene, 0.1-1.1 mumol/l (5.4-59.0 micrograms/dl); zinc, 9-19 mumol/l (58.8-124.2 micrograms/dl); retinol-binding protein, 14-36 mg/l; prealbumin, 104-264 mg/l. The reference intervals reported are consistent with the findings of a number of smaller studies and are likely to be an accurate reflection of the true intervals for healthy preschool children in western developed countries.

Iron status and anaemia in preschool children in Sydney.

The purpose of this study was to determine the iron status of preschool children in Sydney. We assessed 678 children aged 9 to 62 months living in 32 randomly selected census collection districts in central and southern Sydney for iron status using plasma ferritin; of these 678 children, 542 had zinc protoporphyrin tests, red cell indices and haemoglobin tests. Risk factors for iron deficiency were assessed by an administered questionnaire. Overall, the prevalence of iron depletion was 10.5 per cent, iron deficiency 2.8 per cent and iron deficiency anaemia 1.1 per cent. The 24-to-35-month age group (176 children) had the highest prevalence of iron deficiency anaemia of 3.0 per cent although iron depletion (18.7 per cent) and iron deficiency (5.4 per cent) were highest among the 9-to-23-month age group (182 children). Low iron status was related to age of under 24 months (odds ratio (OR) 2.86,95 per cent confidence interval (CI) 1.72 to 4.76). After adjustment for this age effect, the consumption of red meat fewer than four times a week was significantly associated with iron depletion (OR 2.27, CI 1.25 to 4.17) and there was a tendency for children who were being given a vitamin supplement to be less likely to be iron depleted (OR 4.00, CI 0.95 to 16.67). Iron deficiency and iron deficiency anaemia do not represent a major public health problem in preschool children in Sydney. However, for children in the age range of 12 to 36 months there is scope for interventions to further reduce the prevalence of iron deficiency anaemia.

Haem iron intake in 12-36 month old children depleted in iron: case-control study.

OBJECTIVE: To compare the intakes of haem and non-haem iron in iron depleted and iron replete children. DESIGN: Case-control study. SETTING: Early Childhood Centres and a long day care centre in Sydney, Australia. SUBJECTS: Children aged 12-36 months depleted in iron and controls matched for age and sex. MEAN OUTCOME MEASURES: Iron status by using plasma ferritin concentration. A three day weighed dietary intake record completed by the parents. Risk factors for iron deficiency assessed by questionnaire. RESULTS: Fifty six iron depleted and 68 iron replete children participated. The average daily intake of haem iron was significantly lower in the iron depleted group (t = 2.392, P = 0.018); there was a tendency towards a lower average daily intake of non-haem iron (t = 1.724, P = 0.086) and vitamin C (t = 1.921, P = 0.057) for iron depleted children. Low intake of haem iron (< 0.71 mg/day) was significantly associated with iron depletion with an odds ratio fo 3.0 (P = 0.005). The proportion of iron depleted children who were given whole cows' milk before 12 months of age was almost double that of iron replete children; multivariate analysis showed that both haem iron intake and age of introduction of cows' milk were independently associated with iron depletion. CONCLUSIONS: The results of this study show that, in young children in developed countries, a lower haem iron intake is a major risk factor for iron depletion; the introduction of whole cows' milk before 12 months is further confirmed as a risk factor. Parental education on nutrition should now focus on these two aspects of nutrition for infants and young children.

Blood lead concentrations of preschool children in central and southern Sydney.

OBJECTIVES: To determine the prevalence of elevated blood lead concentrations in preschool children in central and southern Sydney. PARTICIPANTS AND SETTING: Children aged from 9 months to 5 years living in 32 randomly selected geographical areas in Central and southern Sydney. METHODS: Venous blood lead concentrations were estimated by atomic absorption spectrometry. RESULTS: 953 children were identified and 726 had parental consent to participate. A blood sample for lead estimation was obtained from 718 children. The geometric mean blood level concentration was 0.34 mu mol/L (7.0 mu/dL). The proportion of children with elevated blood lead concentrations was: 16.1% (>0.48 mu mol/L [10mu/dL]), 3.9% (>0.72 mu mol/L[15mu/dL]) and 0.3% (>1.21mu mol/L [25 mu/dL], respectively. The blood lead levels for children living with a 10-km radius of the Sydney Central Business district were: 25% (>0.48 mu mol/L [10mu/dL]) and 7% (>0.72 mu mol/L [15mu/dL]), respectively. Corresponding findings for children living 10 km outside this radius were: 9% (>0.48 mu mol/L [10mu/dL]) and 1.5% (0.72 mu mol/L [15mu/dL]), respectively. CONCLUSIONS: The proportion of children with elevated blood lead concentrations in Central and Southern Sydney as a whole does not exceed current National Health and Medical Research Council (NHMRC) recommendations. However, in those areas within a 10-km radius of the Central Business District, NHMRC interventional guidelines for communities where more that 5% of children have blood lead concentrations higher than 0.72 mu mol/L (15 mu/dL) should be applied.

Community prevalence survey of children's blood lead levels and environmental lead contamination in inner Sydney.

OBJECTIVE: To determine the distribution of blood lead levels in preschool children in inner Sydney and identify possible sources of environmental lead. DESIGN: Cross sectional community based prevalence survey of children and the houses in which they live, and a survey of volunteer children. SETTING: Mort Bay and Summer Hill, residential localities in inner Sydney. PARTICIPANTS: Ninety-five children aged 9-48 months able to be identified in a defined geographic area and 63 children aged 9-48 months volunteered by their parents. OUTCOME MEASURES: Concentrations of lead in venous blood of all children and in samples from the home environment of Mort Bay children. RESULTS: Four of the children (2.5%) had blood lead levels > or = 1.21 mumol/L (25 micrograms/dL, the current Australian threshold of concern), 27 (17.1%) had levels > or = 0.72 mumol/L (15 micrograms/dL, the new US threshold for individual intervention) and 80 (50.6%) had levels > or = 0.48 mumol/L (10 micrograms/dL, the new US threshold for community intervention). Blood lead concentrations were significantly correlated with concentrations of lead in "sink" soil (r = 0.555, P = 0.026), play area soil (r = 0.492, P = 0.016) and dust from vacuum cleaners (r = 0.428, P = 0.05), and with age of child (r = -0.182, P = 0.023). The presence of the child during house renovation was a strong predictor of having a blood lead level above 0.72 mumol/L (15 micrograms/dL) (odds ratio, 4.6; 95% confidence interval, 1.8-11.7, P = 0.001). CONCLUSIONS: Lead in soil and in household dust in older areas of Sydney is likely to represent a significant health hazard to young children. Many thousands of children may be affected in Sydney and other Australian cities. There is an urgent need for expanded prevalence surveys, public education and the development of strategies for the abatement of lead in urban environments.