The use of cues to convergence and accommodation in naive, uninstructed participants

A remote haploscopic video refractor was used to assess vergence and accommodation responses in a group of 32 emmetropic, orthophoric, symptom free, young adults naïve to vision experiments in a minimally instructed setting. Picture targets were presented at four positions between 2 m and 33 cm. Blur, disparity and looming cues were presented in combination or separately to asses their contributions to the total near response in a within-subjects design. Response gain for both vergence and accommodation reduced markedly whenever disparity was excluded, with much smaller effects when blur and proximity were excluded. Despite the clinical homogeneity of the participant group there were also some individual differences

Receding and disparity cues aid relaxation of accommodation

Purpose. Accommodation can mask hyperopia and reduce the accuracy of non-cycloplegic refraction. It is, therefore, important to minimize accommodation to obtain a measure of hyperopia as accurate as possible. To characterize the parameters required to measure the maximally hyperopic error using photorefraction, we used different target types and distances to determine which target was most likely to maximally relax accommodation and thus more accurately detect hyperopia in an individual. Methods. A PlusoptiX SO4 infra-red photorefractor was mounted in a remote haploscope which presented the targets. All participants were tested with targets at four fixation distances between 0.3 and 2 m containing all combinations of blur, disparity, and proximity/looming cues. Thirty-eight infants (6 to 44 weeks) were studied longitudinally, and 104 children [4 to 15 years (mean 6.4)] and 85 adults, with a range of refractive errors and binocular vision status, were tested once. Cycloplegic refraction data were available for a sub-set of 59 participants spread across the age range. Results. The maximally hyperopic refraction (MHR) found at any time in the session was most frequently found when fixating the most distant targets and those containing disparity and dynamic proximity/looming cues. Presence or absence of blur was less significant, and targets in which only single cues to depth were present were also less likely to produce MHR. MHR correlated closely with cycloplegic refraction (r = 0.93, mean difference 0.07 D, p = n.s., 95% confidence interval +/-<0.25 D) after correction by a calibration factor. Conclusions. Maximum relaxation of accommodation occurred for binocular targets receding into the distance. Proximal and disparity cues aid relaxation of accommodation to a greater extent than blur, and thus non-cycloplegic refraction targets should incorporate these cues. This is especially important in screening contexts with a brief opportunity to test for significant hyperopia. MHR in our laboratory was found to be a reliable estimation of cycloplegic refraction. (Optom Vis Sci 2009;86:1276-1286

Preparedness for use of the rapid result HIV self-test by gay men and other men who have sex with men (MSM): a mixed methods exploratory study among MSM and those involved in HIV prevention and care

Objectives: The aim of the study was to explore preparedness for the HIV self-test among men who have sex with men (MSM) and those involved in HIV prevention and care. Methods: A mixed methods exploratory research design was employed, detailing awareness and willingness to use the self-test and the perceived barriers and facilitators to implementation. Quantitative and qualitative data collection and analysis were completed in parallel. Descriptive and inferential analysis of cross-sectional bar-based survey data collected from MSM through a self-completed questionnaire and oral fluid specimen collection (n = 999) was combined with qualitative, thematic, analysis of data collected through 12 expert focus groups (n = 55) consisting of gay men, National Health Service (NHS) staff, community organizations, entrepreneurs and activists. Findings were subsequently combined and assessed for synergies. Results: Among MSM, self-test awareness was moderate (55%). Greater awareness was associated with increased educational attainment [adjusted odds ratio 1.51; 95% confidence interval (CI) 1.00–2.30; P = 0.05] and previous history of sexually transmitted infection (STI) testing (adjusted odds ratio 1.63; 95% CI 1.11–2.39; P = 0.01). Willingness to use the test was high (89%) and associated with meeting sexual partners online (unadjusted odds ratio 1.96; 95% CI 1.31–2.94; P &lt; 0.001). Experts highlighted the overall acceptability of self-testing; it was understood as convenient, discreet, accessible, and with a low burden to services. However, some ambivalence towards self-testing was reported; it could reduce opportunities to engage with wider services, wider health issues and the determinants of risk. Conclusions: Self-testing represents an opportunity to reduce barriers to HIV testing and enhance prevention and access to care. Levels of awareness are moderate but willingness to use is high. Self-testing may amplify health inequalities

Detection of avascular necrosis on routine diffusion-weighted whole body MRI in patients with multiple myeloma.

OBJECTIVE:Current therapies for multiple myeloma, which include corticosteroids, increase risk of avascular necrosis. The aim of this study was to assess incidental detection of femoral head avascular necrosis on routine whole body MRI including diffusion weighted MRI. METHODS:All whole body MRI studies, performed on patients with known multiple myeloma between 1 January 2010 to 1 May 2017 were assessed for features of avascular necrosis. RESULTS:650 whole body MR scans were analysed. 15 patients (6.6%) had typical MR features of avascular necrosis: 2/15 (13.3%) had femoral head collapse, 4/15 (26.7%) had bilateral avascular necrosis and 9/15 (60%) were asymptomatic. CONCLUSION:This is the first report of avascular necrosis detected on routine whole body MRI in patients with multiple myeloma. Targeted review of femoral heads in multiple myeloma patients undergoing whole body MR is recommended, including in patients without symptoms. ADVANCES IN KNOWLEDGE:Whole body MR which includes diffusion-weighted MRI is extremely sensitive for evaluation of bone marrow. Although whole body MRI is primarily used for evaluation of multiple myeloma disease burden, it also presents an unique opportunity to evaluate the femoral heads for signs of avascular necrosis which can predate symptoms

Billiard Systems in Three Dimensions: The Boundary Integral Equation and the Trace Formula

We derive semiclassical contributions of periodic orbits from a boundary integral equation for three-dimensional billiard systems. We use an iterative method that keeps track of the composition of the stability matrix and the Maslov index as an orbit is traversed. Results are given for isolated periodic orbits and rotationally invariant families of periodic orbits in axially symmetric billiard systems. A practical method for determining the stability matrix and the Maslov index is described.Comment: LaTeX, 19 page

Using a runway paradigm to assess the relative strength of rats' motivations for enrichment objects

Laboratory animals should be provided with enrichment objects in their cages; however, it is first necessary to test whether the proposed enrichment objects provide benefits that increase the animals’ welfare. The two main paradigms currently used to assess proposed enrichment objects are the choice test, which is limited to determining relative frequency of choice, and consumer demand studies, which can indicate the strength of a preference but are complex to design. Here, we propose a third methodology: a runway paradigm, which can be used to assess the strength of an animal’s motivation for enrichment objects, is simpler to use than consumer demand studies, and is faster to complete than typical choice tests. Time spent with objects in a standard choice test was used to rank several enrichment objects in order to compare with the ranking found in our runway paradigm. The rats ran significantly more times, ran faster, and interacted longer with objects with which they had previously spent the most time. It was concluded that this simple methodology is suitable for measuring rats’ motivation to reach enrichment objects. This can be used to assess the preference for different types of enrichment objects or to measure reward system processes

Properties of highly clustered networks

We propose and solve exactly a model of a network that has both a tunable degree distribution and a tunable clustering coefficient. Among other things, our results indicate that increased clustering leads to a decrease in the size of the giant component of the network. We also study SIR-type epidemic processes within the model and find that clustering decreases the size of epidemics, but also decreases the epidemic threshold, making it easier for diseases to spread. In addition, clustering causes epidemics to saturate sooner, meaning that they infect a near-maximal fraction of the network for quite low transmission rates.Comment: 7 pages, 2 figures, 1 tabl

What voters want: reactions to candidate characteristics in a survey experiment

There has been extensive research into the extent to which voters utilise short cuts based on gender and race stereotypes when evaluating candidates, but relatively little is known about how they respond to other background characteristics. We compare the impact of candidates' sex, religion, age, education, occupation and location/residence through a survey experiment in which respondents rate two candidates based on short biographies. We find small differences in the ratings of candidates in response to sex, religion, age and education cues but more sizeable effects are apparent for the candidate's occupation and place of residence. Even once we introduce a control for political party into our experimental scenarios the effect of candidate's place of residence continues to have a sizeable impact on candidate evaluations. Our research suggests that students of electoral behaviour should pay attention to a wider range of candidate cues