Fluidic Momentum Controller

Large angular control moments and torques are developed by controllably circulating a relatively small mass of liquid through small diameter pipes describing a large diameter loop. The loop, by generating and storing angular momentum, can thereby provide efficient cancellation of periodic, non-accumulating, externally induced rotational disturbances. The loop is preferably located on or near the periphery of a structure which is to be stabilized

Perceptions of healthy eating and physical activity in an ethnically diverse sample of young children and their parents: the DEAL prevention of obesity study

Background: Ethnicity is a consistent correlate of obesity; however, little is known about the perceptions and beliefs that may influence engagement with obesity prevention programmes among ethnic minority children. Barriers to (and facilitators of) healthy lifestyles were examined in the qualitative arm of the London (UK) DiEt and Active Living (DEAL) study. Methods: Children aged 8–13 years and their parents, from diverse ethnic groups, were recruited through schools and through places of worship. Thirteen focus group sessions were held with 70 children (n = 39 girls) and eight focus groups and five interviews with 43 parents (n = 34 mothers). Results: Across ethnic groups, dislike of school meals, lack of knowledge of physical activity guidelines for children and negativity towards physical education at school among girls, potentially hindered healthy living. Issues relating to families' wider neighbourhoods (e.g. fast food outlets; lack of safety) illustrated child and parental concerns that environments could thwart intentions for healthy eating and activity. By contrast, there was general awareness of key dietary messages and an emphasis on dietary variety and balance. For ethnic minorities, places of worship were key focal points for social support. Discourse around the retention of traditional practices, family roles and responsibilities, and religion highlighted both potential facilitators (e.g. the importance of family meals) and barriers (reliance on convenience stores for traditional foods). Socio-economic circumstances intersected with key themes, within and between ethnic groups. Conclusions: Several barriers to (and facilitators of) healthy lifestyles were common across ethnic groups. Diversity of cultural frameworks not only were more nuanced, but also shaped lifestyles for minority children.</p

An investigation of two methods for assessing the vertical structure of forest stands

In this study we investigate the limitations of two methods for assessing forest structure: vertical point sampling with a camera and laser point quadrat sampling. Vertical point sampling with a camera is a method by which the height squared per unit area of a forest can be quickly estimated. First, we derive the bias incurred for failing to adjust for slope when implementing this sampling method, and we show that slope can generally be ignored as long as the majority of sample points occur on slopes less than 35 degrees. In the second part of this study we outline the equivalence between survival analysis methods and laser point quadrat analysis methods. We use a survival-based parametric regression model to analyze laser point quadrat data and estimate canopy structure and density. The results show that survival analysis techniques can yield improved results over traditional non-parametric point quadrat analysis methods

Student perceptions of the learning environment under a quarter system at two community colleges

This study was part of a longitudinal research project to determine the effects of a transition from a quarter academic calendar to a semester academic calendar on the learning environment. This project was also a companion study to similar research that was being conducted at Iowa State University. Specifically, the project examined student perception of the learning environment, student perception of grade point average, student organizational involvement and ease of articulation to four-year institutions as they related to the conversion from one academic delivery system to another;A major finding of this study was that students perceived a significant difference in the learning environment under the semester system as compared to the present quarter system. Students perceived under the semester system that they would have more time to assimilate classroom material which had been better prepared and that there would be a more leisurely learning pace;Students did not perceive that significant differences would occur in their grade point average under the semester system but rather their grade point average would remain approximately the same. The majority of the respondents were not planning to transfer to four-year institutions; consequently, no significant differences were perceived in transferring to four-year institutions under a semester system as compared to the present quarter system;No significant differences were found when comparing Des Moines Area Community College students with Southeastern Community College students on perceptions of the learning environment, grade point average, or transferring to four-year institutions under a semester system as compared to the present quarter system;Sixty-five percent of the respondents were freshmen; thirty-five percent were sophomores. Females comprised 57% of the sample. The students ranged in age from 18-50, working while attending classes, and they were not involved in student organizations;In summary, students perceived the learning environment would be significantly affected by the academic delivery system

Auroral vector electric field and particle comparisons. 1: Pre-midnight convection topology

Polar 3 was launched in northern Norway on January 27, 1974. Traversing nearly 3 deg latitude, the rocket crossed over a stable IBC II auroral arc in the positive bay region and continued north to a convection boundary which was identified as the Harang discontinuity. Measurement of the complete electric field vector, of energetic electrons and of the auroral N+2 and OI emissions were used to study the convection topology in the pre-magnetic-midnight region. A strong anticorrelation was observed between the electric field and the precipitating energetic electrons. The inverted V nature of the electron precipitations at the convection boundary, compared with the lack of such structure over the arc which was within the positive bay region, leads to the conclusion that auroral arcs are likely to be associated with inverted V type precipitation only at or poleward of convection boundaries and their eddy structures

Queen control of a key life-history event in a eusocial insect

In eusocial insects, inclusive fitness theory predicts potential queen–worker conflict over the timing of events in colony life history. Whether queens or workers control the timing of these events is poorly understood. In the bumble-bee Bombus terrestris, queens exhibit a ‘switch point’ in which they switch from laying diploid eggs yielding females (workers and new queens) to laying haploid eggs yielding males. By rearing foundress queens whose worker offspring were removed as pupae and sexing their eggs using microsatellite genotyping, we found that queens kept in the complete absence of adult workers still exhibit a switch point. Moreover, the timing of their switch points relative to the start of egg-laying did not differ significantly from that of queens allowed to produce normal colonies. The finding that bumble-bee queens can express the switch point in the absence of workers experimentally demonstrates queen control of a key life-history event in eusocial insects. In addition, we found no evidence that workers affect the timing of the switch point either directly or indirectly via providing cues to queens, suggesting that workers do not fully express their interests in queen–worker conflicts over colony life history

A solvable model of the evolutionary loop

A model for the evolution of a finite population in a rugged fitness landscape is introduced and solved. The population is trapped in an evolutionary loop, alternating periods of stasis to periods in which it performs adaptive walks. The dependence of the average rarity of the population (a quantity related to the fitness of the most adapted individual) and of the duration of stases on population size and mutation rate is calculated.Comment: 6 pages, EuroLaTeX, 1 figur

Quantitative X-ray microradiography for high-throughput phenotyping of osteoarthritis in mice

Objective To investigate and validate digital X-ray microradiography as a novel, high-throughput and cost-effective screening approach to identify abnormal joint phenotypes in mice. Method Digital X-ray microradiography was used to quantify the subchondral bone mineral content (BMC) in the medial tibial plateau. Accuracy and reproducibility of the method were determined in 22 samples from C57BL/6(B6Brd;B6Dnk;B6N-Tyrc-Brd) wild-type mice. The method was then validated in wild-type mice that had undergone surgical destabilisation of medial meniscus (DMM) and in a genetically modified mouse strain with an established increase in trabecular bone mass. Results The measurement of subchondral BMC by digital X-ray microradiography had a coefficient of variation of 3.6%. Digital X-ray microradiography was able to demonstrate significantly increased subchondral BMC in the medial tibial plateau of male mice 4 and 8 weeks after DMM surgery and in female mice 8 weeks after surgery. Furthermore, digital X-ray microradiography also detected the increase in subchondral BMC in a genetically modified mouse strain with high trabecular bone mass. Conclusion Quantitation of subchondral BMC by digital X-ray microradiography is a rapid, sensitive and cost-effective method to identify abnormal joint phenotypes in mice of both genders at several ages

Supersweet Sweet Corn Cultivar Evaluation for Northern Indiana, 2015

This paper reports on thirteen bicolor, two yellow, and three white supersweet sweet corn entries that were evaluated at the Pinney-Purdue Agricultural Center in Wanatah, Indiana

Perceived parenting and psychological well-being in UK ethnic minority adolescents

Background: Warm, caring parenting with appropriate supervision and control is considered to contribute to the best mental health outcomes for young people. The extent to which this view on ‘optimal’ parenting and health applies across ethnicities, warrants further attention. We examined associations between perceived parental care and parental control and psychological well-being among ethnically diverse UK adolescents.&lt;p&gt;&lt;/p&gt; Methods: In 2003 a sample of 4349 pupils aged 11–13 years completed eight self-reported parenting items. These items were used to derive the parental care and control scores. Higher score represents greater care and control, respectively. Psychological well-being was based on total psychological difficulties score from Goodman's Strengths and Difficulties Questionnaire, increasing score corresponding to increasing difficulties.&lt;p&gt;&lt;/p&gt; Results: All minority pupils had lower mean care and higher mean control scores compared with Whites. In models stratified by ethnicity, increasing parental care was associated with lower psychological difficulties score (better mental health) and increasing parental control with higher psychological difficulties score within each ethnic group, compared with reference categories. The difference in psychological difficulties between the highest and lowest tertiles of parental care, adjusted for age, sex, family type and socio-economic circumstances, was: White UK =−2.92 (95% confidence interval −3.72, −2.12); Black Caribbean =−2.08 (−2.94, −1.22); Nigerian/Ghanaian =−2.60 (−3.58, −1.62); Other African =−3.12 (−4.24, −2.01); Indian =−2.77 (−4.09, −1.45); Pakistani/ Bangladeshi =−3.15 (−4.27, −2.03). Between ethnic groups (i.e. in models including ethnicity), relatively better mental health of minority groups compared with Whites was apparent even in categories of low care and low autonomy. Adjusting for parenting scores, however, did not fully account for the protective effect of minority ethnicity.&lt;p&gt;&lt;/p&gt; Conclusions: Perceived quality of parenting is a correlate of psychological difficulties score for all ethnic groups despite differences in reporting. It is therefore likely that programmes supporting parenting will be effective regardless of ethnicity.&lt;p&gt;&lt;/p&gt