Computational analysis and preliminary redesign of the nozzle contour of the Langley hypersonic CF4 tunnel

A computational analysis, modification, and preliminary redesign study was performed on the nozzle contour of the Langley Hypersonic CF4 Tunnel. This study showed that the existing nozzle was contoured incorrectly for the design operating condition, and this error was shown to produce the measured disturbances in the exit flow field. A modified contour was designed for the current nozzle downstream of the maximum turning point that would provide a uniform exit flow. New nozzle contours were also designed for an exit Mach number and Reynolds number combination which matches that attainable in the Langley 20-Inch Mach 6 Tunnel. Two nozzle contours were designed: one having the same exit radius but a larger mass flow rate than that of the existing CF4 Tunnel, and the other having the same mass flow rate but a smaller exit radius than that of the existing CF4 Tunnel

Investigations And Management Of Epizootic Plague At Ice House Reservoir, Eldorado National Forest, California, 1994 And 1995

The occurrence of plague (Yersinia pestic) at Ice House Reservoir in 1994 and 1995 was characteristic of widespread epizootics in high use recreational areas of California. Staff of the Vector-Borne Disease Section investigated these epizootics and found dense populations of plague susceptible California ground squirrels (Spermophilus beecheyi) with high numbers of fleas, primarily Diamanus montanus, the most important plague vector. This combination indicated a high risk of plague exposure to campground users. A non-fatal human case of plague, contracted at Mountain Camp II, was reported after the initial epizootic investigation. The patient\u27s exposure occurred prior to the reporting of the epizootic die-off among the California ground squirrels. The plague investigation included direct observations, animal trapping, and laboratory testing of rodent carcasses, sera, and fleas. Plague management and prevention included flea control with 2% Diazinon dust and rodent population reduction using 1% zinc phosphide treated grain. Evaluation of the 1994 applications indicated a successful reduction of rodents and fleas. However, the need for an ongoing management program was emphasized in 1995 when the plague epizootic continued. Intrusion of plague infected rodents and their fleas necessitated a 1995 treatment in the four campgrounds involved

The Effects of MBO on Performance and Satisfaction in a Public Sector Organization

This field study examined the effects of MBO on measures of quantity and quality of performance and satisfaction with the work and supervision among employees in a human services agency. Although not all the quantity measures improved significantly, the combined measure for quantity of performance and one of two quality measures showed significant improvement following implementation of MBO. Satisfaction with supervision also significantly improved but not satisfaction with work. The study lends support to the use of MBO in public sector organizations

The Effects of MBO on Performance and Satisfaction in a Public Sector Organization

This field study examined the effects of MBO on measures of quantity and quality of performance and satisfaction with the work and supervision among employees in a human services agency. Although not all the quantity measures improved significantly, the combined measure for quantity of performance and one of two quality measures showed significant improvement following implementation of MBO. Satisfaction with supervision also significantly improved but not satisfaction with work. The study lends support to the use of MBO in public sector organizations

Corn and Soybean Potassium Uptake, Removal with Harvest, and Recycling to the Soil

Research has been conducted at the ISU Northeast Research Farm for many years to study potassium (K) fertilization rates and placement methods on corn and soybean grain yield, K uptake, and soil-test K values. However, no research has investigated K recycling to the soil from maturing plants and crop residue until the next crop is planted. Because all plant K is soluble in water, the amount and the timing of the K recycled to the soil should have a significant early impact on soil-test K values, and should explain a great deal of usually very high soil-test K temporal variability. Therefore, plots of several field K trials at this farm were used to investigate these issues

Sex Differences in Vascular Compliance in Normal-Weight but Not Obese Boys and Girls: The Effect of Body Composition

Objectives. To determine the effect of sex and obesity on vascular function in children and explore potential mechanisms that account for differences in vascular function. Methods. Participants were 61 (30 boys) normal-weight (BMI 25–75% ile for age and sex) and 62 (30 boys) obese (BMI ≥ 95% ile) children of ages 8–18 years. Measurements of large and small artery elastic index (LAEI and SAEI, resp.) and reactive hyperemia index (RHI) were obtained at rest, along with anthropometric and biochemical information. Results. In normal-weight children, LAEI was 16% higher in males than females (P = 0.04) with a similar trend for SAEI (13% higher in males, P = 0.067). In obese children, no sex-related differences in vascular measures were observed. In multivariable models, sex differences in arterial compliance were explained by higher lean mass in normal-weight boys. Fat mass predicted LAEI and SAEI in both normal-weight and obese females, but fat mass predicted arterial compliance in boys when fat mass exceeded 24 kg (37% of the sample). Conclusions. Normal-weight males have higher arterial compliance than normal-weight females due to increased lean mass, but sex-related differences were not observed among obese children due to a lack of sex-related differences in lean or fat mass

Development of scales to assess children's perceptions of friend and parental influences on physical activity

<p>Abstract</p> <p>Background</p> <p>Many children do not meet physical activity guidelines. Parents and friends are likely to influence children's physical activity but there is a shortage of measures that are able to capture these influences.</p> <p>Methods</p> <p>A new questionnaire with the following three scales was developed: 1) <it>Parental influence on physical activity</it>; 2) <it>Motives for activity with friends </it>scale; and 3) <it>Physical activity and sedentary group normative values</it>. Content for each scale was informed by qualitative work. One hundred and seventy three, 10-11 year old children completed the new questionnaire twice, one week apart. Participants also wore an accelerometer for 5 days and mean minutes of moderate to vigorous physical activity, light physical activity and sedentary time per day were obtained. Test-retest reliability of the items was calculated and Principal Component analysis of the scales performed and sub-scales produced. Alphas were calculated for main scales and sub-scales. Correlations were calculated among sub-scales. Correlations between each sub-scale and accelerometer physical activity variables were calculated for all participants and stratified by sex.</p> <p>Results</p> <p>The Parental influence scale yielded four factors which accounted for 67.5% of the variance in the items and had good (α > 0.7) internal consistency. The Motives for physical activity scale yielded four factors that accounted for 66.1% and had good internal consistency. The Physical activity norms scale yielded 4 factors that accounted for 67.4% of the variance, with good internal consistency for the sub-scales and alpha of .642 for the overall scale. Associations between the sub-scales and physical activity differed by sex. Although only 6 of the 11 sub-scales were significantly correlated with physical activity there were a number of associations that were positively correlated >0.15 indicating that these factors may contribute to the explanation of children's physical activity.</p> <p>Conclusion</p> <p>Three scales that assess how parents, friends and group normative values may be associated with children's physical activity have been shown to be reliable and internally consistent. Examination of the extent to which these new scales improve our understanding of children's physical activity in datasets with a range of participant and family characteristics is needed.</p

Physical activity and sedentary behaviour typologies of 10-11 year olds

<p>Abstract</p> <p>Background</p> <p>Targeted interventions may be more effective at increasing children's physical activity. The aim of this study was to identify clusters of children based on physical activity and sedentary patterns across the week.</p> <p>Methods</p> <p>Participants were 761, 10-11 year old children. Participant's self-reported time spent in eight physical activity and sedentary contexts and wore an accelerometer. Cluster analysis was conducted on the time spent in the self-reported physical activity and sedentary contexts. Mean minutes of accelerometer derived of moderate to vigorous physical activity (MVPA) and sedentary time were derived for the entire week, weekdays only, weekend days and four different time periods across each type (weekend or weekday) of days. Differences in the physical activity patterns of the groups derived from the cluster analysis were assessed for overall physical activity as well as for the four time periods on weekdays and weekend days.</p> <p>Results</p> <p>Three clusters emerged: 1) High active/Low sedentary; 2) Low active/Moderate sedentary; and 3) High Active/High sedentary. Patterns of activity differed across the week for each group and the High Active/High sedentary obtained the most minutes of MVPA.</p> <p>Conclusions</p> <p>Patterns of physical activity and sedentary time differed across the week for each cluster. Interventions could be targeted to the key periods when each group is inactive.</p

Friendship groups and physical activity: qualitative findings on how physical activity is initiated and maintained among 10–11 year old children

<p>Abstract</p> <p>Background</p> <p>Many youth physical activity interventions have minimal effect. To design better interventions we need to understand more about the factors that influence youth activity. Application of self-determination theory to youth physical activity, particularly the relatedness and competence, might suggest that friends and friendship groups influence the initiation and maintenance of youth physical activity. In this study we examined this issue.</p> <p>Methods</p> <p>Seventeen focus groups were conducted with 113, 10–11 year old children, from 11 primary schools in Bristol, UK. Focus groups examined: 1) the nature of children's friendship groups; 2) associations between physical activity and social group status; and 3) how friendship groups affect the initiation and maintenance of physical activity. All focus groups were audio-taped and transcribed verbatim. Data were analyzed using content analysis.</p> <p>Results</p> <p>Participants reported that there were three different types of friendship groups; School friends; Neighborhood friends; and Other Friends who were friends from organized activities or children of their parents' friends. Participants had multiple groups of friends and engaged in different activities with the different groups. Possessing several groups of friends was desirable as it kept the friendships fresh and interesting. Physical activity was perceived as a positive attribute and linked to social status among boys. Among girls the association between physical activity ability and social status was more complex, appearing to differ by the norms of the group to which participants belonged. Some participants reported that low activity ability could be perceived as desirable in some social groups. Participants reported that friends provide support to initiate physical activity via co-participation (i.e. engaging in activity together); modeling of being active; and providing verbal support to engage in activity. Enjoyment was the most important factor in maintaining activity participation with participating in activity with friends a key factor influencing enjoyment.</p> <p>Conclusion</p> <p>Friendship groups affect both the initiation and maintenance of youth physical activity. Children belong to several groups and engage in different activities with different groups. Simple strategies that aim to promote physical activity via the different friendship groups could be an effective means of promoting increased physical activity in young people.</p