Repeatability and validity of a food frequency questionnaire in free-living older people in relation to cognitive function

Objectives: To determine the repeatability and validity of a self-administered, 175-item food frequency questionnaire (FFQ) in free-living older people and to assess whether these are influenced by cognitive function. Participants and setting: 189 free-living people aged 64-80y were recruited from participants in a previous study. Design: To assess repeatability, 102 (52M, 50F) participants completed the FFQ on two occasions three months apart. To assess validity, another 87 participants (44 M, 43 F) completed the FFQ and a four-day weighed diet record three months later. 25 nutrients were studied. Results: For repeatability, Spearman rank correlation coefficients were above 0.35 (p<0.05) for all nutrients. Cohen’s weighted Kappa was above 0.4 for all nutrients except starch, riboflavin, retinol, β-carotene, and calcium. There were no substantial differences in correlation coefficients between sub-groups divided by short-term memory test score. There was no clear pattern for correlation coefficients in sub-groups divided by executive function test score. For validity, the Spearman rank correlation coefficients were above 0.2 (p<0.05) for all nutrients except fat, mono-unsaturated fatty acids, niacin equivalents and vitamin D, and Cohen’s weighted kappa was above 0.4 for alcohol and was above 0.2 for 13 other nutrients. Participants in the lowest-score groups of short-term memory and executive function had the lowest median Spearman correlation coefficient. Conclusions: The FFQ had reasonable repeatability and validity in ranking nutrient intakes in this population though the results varied between nutrients. Poor short-term memory or executive function may affect FFQ validity in ranking nutrient intakes

Testing stochastic software using Pseudo-oracles

Stochastic models can be difficult to test due to their complexity and randomness, yet their predictions are often used to make important decisions, so they need to be correct. We introduce a new search-based technique for testing implementations of stochastic models by maximising the differences between the implementation and a pseudo-oracle. Our technique reduces testing effort and enables discrepancies to be found that might otherwise be overlooked. We show the technique can identify differences challenging for humans to observe, and use it to help a new user understand implementation differences in a real model of a citrus disease (Huanglongbing) used to inform policy and research.Wellcome TrustThis is the author accepted manuscript. The final version is available from the Association for Computing Machinery via http://dx.doi.org/10.1145/2931037.293106

Formulas and Asymptotics for the Asymmetric Simple Exclusion Process

This is an expanded version of a series of lectures delivered by the second author in June, 2009. It describes the results of three of the authors' papers on ASEP, from the derivation of exact formulas for configuration probabilities, through Fredholm determinant representation, to asymptotics for ASEP with step initial condition establishing KPZ universality. Although complete proofs are in general not given, at least the main elements of them are.Comment: 25 pages. Version 2 corrects an error in Section II.

Assessing the relative validity of the Scottish Collaborative Group FFQ for measuring dietary intake in adults

Acknowledgements: The authors would like to thank Jacqueline Burr and Lindsey Shaw for collecting the data for this study. Data coding and entry for the food diaries was completed by Dr Lindsey Masson. The authors would also like to acknowledge the Scottish Health Survey Team, the Scottish Government and the National Centre for Social Research for their support in conducting this research. Financial support: This work was supported by funding from the Rural and Environment Science and Analytical Services Division (RESAS) programme of the Scottish Government (J.L.H., L.C.A.C., S.W. and G.Mc.N.). The RESAS programme had no role in the design, analysis or writing of this article. Conflict of interest: None. Authorship: J.L.H., L.C.A.C., S.W. and G.Mc.N. were responsible for the design of the study and formulated the research question. L.C.A.C. and S.W. carried out the study. J.L.H. completed the literature review, conducted the statistical analysis and drafted the initial paper. All authors were responsible for drafting and revising the manuscript and have approved the final version. Ethics of human subject participation: This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human subjects were approved by the Rowett Human Studies Ethical Review Panel. Written informed consent was obtained from all participants.Peer reviewedPostprintPostprintPostprintPostprintPostprintPostprintPostprintPostprin

Directional emission of light from a nano-optical Yagi-Uda antenna

The plasmon resonance of metal nanoparticles can enhance and direct light from optical emitters in much the same way that radio frequency (RF) antennas enhance and direct the emission from electrical circuits. In the RF regime, a typical antenna design for high directivity is the Yagi-Uda antenna, which basically consists of a one-dimensional array of antenna elements driven by a single feed element. Here, we present the experimental demonstration of directional light emission from a nano-optical Yagi-Uda antenna composed of an array of appropriately tuned gold nanorods. Our results indicate that nano-optical antenna arrays are a simple but efficient tool for the spatial control of light emission.Comment: 4 pages, including 4 figure

Driving in stroke survivors aged 18–65 years: The Psychosocial Outcomes In StrokE (POISE) Cohort Study

Background: There is limited information regarding return to driving after stroke. Aims: To determine the frequency and predictors of return to driving within 1 month of acute stroke in younger (age 18–65 years) adults. Methods: POISE (Psychosocial Outcomes In StrokE) was a cohort study conducted in Australia between October 2008 and June 2010. Consecutive patients (age 18–65 years) with a recent (≤28 days) acute stroke were recruited. Validated demographic, clinical, mental health, cognitive, and disability measures including return to driving were obtained. Multivariable logistic regression was used to determine factors associated with return to driving within 1 month of stroke. Results: Among 359 participants who were legally able to drive before stroke, 96 (26.7%) returned to driving within 1 month. Compared to those without an early return to driving (n = 263), drivers were more often male, the main income earner, in paid work before stroke and without symptoms of depression or fatigue. Independence in activities of daily living (odds ratio (OR) 30.05, 95% confidence interval (CI) 3.85–234.45), not recalling receiving advice on driving cessation (OR 5.55, 95% CI 2.86–11.11), and having returned to paid work (OR 3.93, 95% CI 1.94–7.96) were associated with early return to driving. Conclusions: One in four young adults resumed driving within a month, contrary to guideline recommendations. These data reinforce the importance of deciding who is responsible for determining fitness to drive after stroke, when, and whether it is reasonable to enforce driving restrictions on those with minimal disability who are fit to return to work. Registration: Australian New Zealand Clinical Trials Registry ANZCTRN 12608000459325

Non-response bias in physical activity trend estimates

© 2009 Craig et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Do female association preferences predict the likelihood of reproduction?

Sexual selection acting on male traits through female mate choice is commonly inferred from female association preferences in dichotomous mate choice experiments. However, there are surprisingly few empirical demonstrations that such association preferences predict the likelihood of females reproducing with a particular male. This information is essential to confirm association preferences as good predictors of mate choice. We used green swordtails (&lt;i&gt;Xiphophorus helleri&lt;/i&gt;) to test whether association preferences predict the likelihood of a female reproducing with a male. Females were tested for a preference for long- or short-sworded males in a standard dichotomous choice experiment and then allowed free access to either their preferred or non-preferred male. If females subsequently failed to produce fry, they were provided a second unfamiliar male with similar sword length to the first male. Females were more likely to reproduce with preferred than non-preferred males, but for those that reproduced, neither the status (preferred/non-preferred) nor the sword length (long/short) of the male had an effect on brood size or relative investment in growth by the female. There was no overall preference based on sword length in this study, but male sword length did affect likelihood of reproduction, with females more likely to reproduce with long- than short-sworded males (independent of preference for such males in earlier choice tests). These results suggest that female association preferences are good indicators of female mate choice but that ornament characteristics of the male are also important