Probing liquid surface waves, liquid properties and liquid films with light diffraction

Surface waves on liquids act as a dynamical phase grating for incident light. In this article, we revisit the classical method of probing such waves (wavelengths of the order of mm) as well as inherent properties of liquids and liquid films on liquids, using optical diffraction. A combination of simulation and experiment is proposed to trace out the surface wave profiles in various situations (\emph{eg.} for one or more vertical, slightly immersed, electrically driven exciters). Subsequently, the surface tension and the spatial damping coefficient (related to viscosity) of a variety of liquids are measured carefully in order to gauge the efficiency of measuring liquid properties using this optical probe. The final set of results deal with liquid films where dispersion relations, surface and interface modes, interfacial tension and related issues are investigated in some detail, both theoretically and experimentally. On the whole, our observations and analyses seem to support the claim that this simple, low--cost apparatus is capable of providing a wealth of information on liquids and liquid surface waves in a non--destructive way.Comment: 25 pages, 12 figures, to appear in Measurement Science and Technology (IOP

An adaptogenic role for omega-3 fatty acids in stress; a randomised placebo controlled double blind intervention study (pilot) [ISRCTN22569553]

BACKGROUND: There is evidence for an adaptive role of the omega -3 fatty acid, docosahexaenoic acid (DHA) during stress. Mechanisms of action may involve regulation of stress mediators, such as the catecholamines and proinflammatory cytokines. Prevention of stress-induced aggression and hostility were demonstrated in a series of clinical trials. This study investigates whether perceived stress is ameliorated by DHA in stressed university staff. METHODS: Subjects that scored ≥ 17 on the Perceived Stress Scale were randomised into a 6-week pilot intervention study. The diet reactive group was supplemented with 6 g of fish oil containing 1.5 g per day DHA, while the placebo group was supplemented with 6 g a day of olive oil. The groups were compared with each other and a wider cross sectional study population that did not receive either active or placebo intervention. RESULTS: There was a significant reduction in perceived stress in both the fish oil and the placebo group from baseline. There was also a significant between-group difference between the fish oil group and the no-treatment controls in the rate of stress reduction (p < 0.05). However, there was not a significant between-group difference between the fish oil and the placebo group, nor the placebo group and the control group. These results are discussed in the context of several methodological limitations. The significant stress reductions in both the fish oil and the placebo group are considered in view of statistical regression, an effect likely to have been exaggerated by the time course of the study, a large placebo effect and the possibility of an active effect from the placebo. CONCLUSION: There were significant differences (p < 0.05) in the fish oil group compared with no-treatment controls. This effect was not demonstrated in the placebo group. As a pilot study, it was not sufficiently powered to find the difference between the fish oil group and the placebo group significant. Further work needs to be undertaken to conclusively demonstrate these data trends. However, the findings from this research support the literature in finding a protective or 'adaptogenic' role for omega-3 fatty acids in stress

Instrumentation issues in implementation science

Background Like many new fields, implementation science has become vulnerable to instrumentation issues that potentially threaten the strength of the developing knowledge base. For instance, many implementation studies report findings based on instruments that do not have established psychometric properties. This article aims to review six pressing instrumentation issues, discuss the impact of these issues on the field, and provide practical recommendations. Discussion This debate centers on the impact of the following instrumentation issues: use of frameworks, theories, and models; role of psychometric properties; use of ‘home-grown’ and adapted instruments; choosing the most appropriate evaluation method and approach; practicality; and need for decision-making tools. Practical recommendations include: use of consensus definitions for key implementation constructs; reporting standards (e.g., regarding psychometrics, instrument adaptation); when to use multiple forms of observation and mixed methods; and accessing instrument repositories and decision aid tools. Summary This debate provides an overview of six key instrumentation issues and offers several courses of action to limit the impact of these issues on the field. With careful attention to these issues, the field of implementation science can potentially move forward at the rapid pace that is respectfully demanded by community stakeholders

Factors that influence career decision-making among elite athletes

A common belief about elite athletes is that they invest so much effort into the pursuit of their athletic careers that they fail to develop good career decision-making skills. Recent findings challenge that belief. The present study investigated career decision-making difficulties among 117 elite Australian athletes. Participants completed adapted versions of the Career Decision-Making Difficulties Questionnaire, the Athlete Identity Measurement Scale, the Career Decision-making Self-efficacy Short Form, and the Work Locus of Control Scale. These elite athletes showed no evidence of career decision-making difficulties. Combinations of this set of variables accounted for 35% of the variance in decision status and 20% of the variance in career decision-making difficulties. Career decision-making self-efficacy was a major contributor in both instances. Internal locus of control was also identified as a desirable characteristic in the context of career decision-making. The implications of these findings are discussed

The Relationship Between Career Variables and Occupational Aspirations and Expectations for Australian High School Adolescents

This study surveyed 925 Australian high school students enrolled in grades 8-12 on measures of occupational aspirations, occupational expectations, career status aspirations and career status expectations, and tested the association between these variables and career maturity, career indecision, career decision-making self-efficacy, and career barriers. Adolescents generally aspired to/expected to work within a small range of RIASEC occupational categories. One third of students reported occupational aspiration/expectation discrepancies. These differed across gender, and across age for females, but not for males. Students who demonstrated both occupational and status aspiration and expectation discrepancies reported more career indecision, were less confident about making a career-related decision, and were less career mature. Students generally held higher occupational status aspirations than expectations, and males were more likely to choose professional occupations than females. Age differences were found for status expectations, but not for status aspirations

Predicting Two Components of Career Maturity in School Based Adolescents

Three hundred and sixty-seven secondary school students across five year levels (8–12) were assessed for levels of career maturity (attitude and knowledge), work commitment, work value, career decidedness (indecision and certainty), career decision-making self-efficacy and self-esteem, and indicated their age, gender, socioeconomic status, school achievement and work experience. Using two multiple regression analyses, the predictor variables were able to account for 52% of the variance of career maturity attitude, and account for 41% of the variance of career maturity knowledge. Self-efficacy, age, career decidedness (certainty) and work commitment were the main predictors of career maturity attitude. Age, gender, career decidedness (certainty), work commitment and career decidedness (indecision) were the main predictors of career maturity knowledge. Results demonstrated the importance of examining two aspects of career maturity (attitude and knowledge), and were discussed in the context of Super’s (1957, 1990) theory of career development