The influence of visual flow and perceptual load on locomotion speed

Visual flow is used to perceive and regulate movement speed during locomotion. We assessed the extent to which variation in flow from the ground plane, arising from static visual textures, influences locomotion speed under conditions of concurrent perceptual load. In two experiments, participants walked over a 12-m projected walkway that consisted of stripes that were oriented orthogonal to the walking direction. In the critical conditions, the frequency of the stripes increased or decreased. We observed small, but consistent effects on walking speed, so that participants were walking slower when the frequency increased compared to when the frequency decreased. This basic effect suggests that participants interpreted the change in visual flow in these conditions as at least partly due to a change in their own movement speed, and counteracted such a change by speeding up or slowing down. Critically, these effects were magnified under conditions of low perceptual load and a locus of attention near the ground plane. Our findings suggest that the contribution of vision in the control of ongoing locomotion is relatively fluid and dependent on ongoing perceptual (and perhaps more generally cognitive) task demands

Extended optical treatment versus early patching with an intensive patching regimen in children with amblyopia in Europe (EuPatch): a multicentre, randomised controlled trial

Background Amblyopia, the most common visual impairment of childhood, is a public health concern. An extended period of optical treatment before patching is recommended by the clinical guidelines of several countries. The aim of this study was to compare an intensive patching regimen, with and without extended optical treatment (EOT), in a randomised controlled trial. Methods EuPatch was a randomised controlled trial conducted in 30 hospitals in the UK, Greece, Austria, Germany, and Switzerland. Children aged 3–8 years with newly detected, untreated amblyopia (defined as an interocular difference ≥0·30 logarithm of the minimum angle of resolution [logMAR] best corrected visual acuity [BCVA]) due to anisometropia, strabismus, or both were eligible. Participants were randomly assigned (1:1) via a computer-generated sequence to either the EOT group (18 weeks of glasses use before patching) or to the early patching group (3 weeks of glasses use before patching), stratified for type and severity of amblyopia. All participants were initially prescribed an intensive patching regimen (10 h/day, 6 days per week), supplemented with motivational materials. The patching period was up to 24 weeks. Participants, parents or guardians, assessors, and the trial statistician were not masked to treatment allocation. The primary outcome was successful treatment (ie, ≤0·20 logMAR interocular difference in BCVA) after 12 weeks of patching. Two primary analyses were conducted: the main analysis included all participants, including those who dropped out, but excluded those who did not provide outcome data at week 12 and remained on the study; the other analysis imputed this missing data. All eligible and randomly assigned participants were assessed for adverse events. This study is registered with the International Standard Randomised Controlled Trial Number registry (ISRCTN51712593) and is no longer recruiting. Findings Between June 20, 2013, and March 12, 2020, after exclusion of eight participants found ineligible after detailed screening, we randomly assigned 334 participants (170 to the EOT group and 164 to the early patching group), including 188 (56%) boys, 146 (44%) girls, and two (1%) participants whose sex was not recorded. 317 participants (158 in the EOT group and 159 in the early patching group) were analysed for the primary outcome without imputation of missing data (median follow-up time 42 weeks [IQR 42] in the EOT group vs 27 weeks [27] in the early patching group). 24 (14%) of 170 participants in the EOT group and ten (6%) of 164 in the early patching group were excluded or dropped out of the study, mostly due to loss to follow-up and withdrawal of consent; ten (6%) in the EOT group and three (2%) in the early patching group missed the 12 week visit but remained on the study. A higher proportion of participants in the early patching group had successful treatment (107 [67%] of 159) than those in the EOT group (86 [54%] of 158; 13% difference; p=0·019) after 12 weeks of patching. No serious adverse events related to the interventions occurred. Interpretation The results from this trial indicate that early patching is more effective than EOT for the treatment of most children with amblyopia. Our findings also provide data for the personalisation of amblyopia treatments. Funding Action Medical Research, NIHR Clinical Research Network, and Ulverscroft Foundation

Effective security requirements analysis: HAZOP and use cases

Abstract. Use cases are widely used for functional requirements elicitation. However, security non-functional requirements are often neglected in this requirements analysis process. As systems become increasingly complex current means of analysis will probably prove ineffective. In the safety domain a variety of effective analysis techniques have emerged over many years. Since the safety and security domains share many similarities, various authors have suggested that safety techniques might usefully find application in security. This paper takes one such technique, HAZOP, and applies it to one widely used functional requirement elicitation component, UML use cases, in order to provide systematic analysis of potential security issues at the start of system development

Discrete-time sliding mode control on a flexible truss structure

Implementation of discrete-time sliding mode control on a sampled-data system leads to sliding motion in an O(T-2) boundary layer of the discontinuity surface, where T is the sampling period. A truss panel structure vibration control experiment is conducted to demonstrate the effectiveness of the proposed method. This paper utilizes a truncated model to characterize the models of interest and treats all the high frequency modes as disturbances. The experiment includes system identification, state observer design, and discrete-time sliding mode control