Challenges of Recruiting a Vulnerable Population in a Grounded Theory Study

Recruitment is a crucial and fundamental part of research and one that poses various degrees of difficulty. This is particularly so when the area of research is one that is either highly sensitive, or that involves participants who are deemed to be particularly vulnerable. This article explores the inherent tensions in matters of participant recruitment among meeting the demands of institutional ethics committees, satisfying the concerns of clinicians in the field and the need to maintain methodological rigor. A postgraduate research student’s experience of these tensions underpins the discussion. The article concludes with an outline of the student’s strategies and resolution of these issues.postprin

Are Scores on the PPT Useful in Determination of Risk of Future Falls in Individuals With Dementia?

Individuals with dementia or Alzheimer’s disease (AD), exhibit both a progressive decline in cognitive function and accumulating difficulty with physical function.1 As cognitive impairment begins, individuals will initially demonstrate difficulties with short-term memory and with instrumental activities of daily living. As the dementia progresses, individuals will increasingly demonstrate difficulties with long-term memory, communication, and basic activities of daily living

A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: Implications for H0H_0

Strong gravitational lensing provides an independent measurement of the Hubble parameter ($H_0$). One remaining systematic is a bias from the additional mass due to a galaxy group at the lens redshift or along the sightline. We quantify this bias for more than 20 strong lenses that have well-sampled sightline mass distributions, focusing on the convergence $\kappa$ and shear $\gamma$. In 23% of these fields, a lens group contributes a $\ge$1% convergence bias; in 57%, there is a similarly significant line-of-sight group. For the nine time delay lens systems, $H_0$ is overestimated by 11$^{+3}_{-2}$% on average when groups are ignored. In 67% of fields with total $\kappa \ge$ 0.01, line-of-sight groups contribute $\gtrsim 2\times$ more convergence than do lens groups, indicating that the lens group is not the only important mass. Lens environment affects the ratio of four (quad) to two (double) image systems; all seven quads have lens groups while only three of 10 doubles do, and the highest convergences due to lens groups are in quads. We calibrate the $\gamma$-$\kappa$ relation: $\log(\kappa_{\rm{tot}}) = (1.94 \pm 0.34) \log(\gamma_{\rm{tot}}) + (1.31 \pm 0.49)$ with a rms scatter of 0.34 dex. Shear, which, unlike convergence, can be measured directly from lensed images, can be a poor predictor of $\kappa$; for 19% of our fields, $\kappa$ is $\gtrsim 2\gamma$. Thus, accurate cosmology using strong gravitational lenses requires precise measurement and correction for all significant structures in each lens field.Comment: 34 pages, 11 figures, accepted for publication in Ap