7,724 research outputs found
Solid state sandwich concept: Designs, considerations and issues
Progress in analysis and design of solid state approaches to the solar power satellite microwave power transmission system is reviewed with special emphasis on the Sandwich concept and the issues of maintenance of low junction temperatures for amplifiers to assure acceptable lifetime. Ten specific issues or considerations are discussed and their resolution or status is presented
Initial MPTS study results: Design considerations and issues
One of the key issues identified during investigations of microwave power transmission systems from 1965 to 1976 was the need to assure that the billions of diodes on ground-based rectennas are sufficiently reliable to support long life times of approximately 30 years. Major systems studies conducted focused on waveguides; radio frequency interference and biological considerations; the relationship between performance, weight, and cost; risk assessment; crossed field directional amplifier noise; a 48 kW klystron; effects of the environment on propagation and phase control; rectenna technology; a rationale for the ground power density region; alternate technologies for orbital assembly; ionospheric effects and phase control; and reception conversion (rf to dc collector/converter)
A study of the quantitative formation of furfural from d-lyxose
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1939.MIT copy bound with: Reactions of β-ionone / by Ida Rovno [1939]Includes bibliographical references (leaf [28]).by Maynard E. Smith.B.S
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
Evolutionary Markovian Strategies in 2 x 2 Spatial Games
Evolutionary spatial 2 x 2 games between heterogeneous agents are analyzed
using different variants of cellular automata (CA). Agents play repeatedly
against their nearest neighbors 2 x 2 games specified by a rescaled payoff
matrix with two parameteres. Each agent is governed by a binary Markovian
strategy (BMS) specified by 4 conditional probabilities [p_R, p_S, p_T, p_P]
that take values 0 or 1. The initial configuration consists in a random
assignment of "strategists" among the 2^4= 16 possible BMS. The system then
evolves within strategy space according to the simple standard rule: each agent
copies the strategy of the neighbor who got the highest payoff. Besides on the
payoff matrix, the dominant strategy -and the degree of cooperation- depend on
i) the type of the neighborhood (von Neumann or Moore); ii) the way the
cooperation state is actualized (deterministically or stochastichally); and
iii) the amount of noise measured by a parameter epsilon. However a robust
winner strategy is [1,0,1,1].Comment: 18 pages, 8 figures (7 of these figures contain 4 encapsulapted
poscript files each
Enforcement of Labor Arbitration Agreements: Is Refusal to Arbitrate an Unfair Labor Practice?
Review of \u3ci\u3eCases and Materials on the Legal Profession\u3c/i\u3e by Elliott E. Cheatham
- …