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Bone-to-bone and implant-to-bone impingement : a novel graphical representation for hip replacement planning

Bone-to-bone impingement (BTBI) and implant-to-bone impingement (ITBI) risk assessment is generally performed intra-operatively by surgeons, which is entirely subjective and qualitative, and therefore, lead to sub-optimal results and recurrent dislocation in some cases. Therefore, a method was developed for identifying subject-specific BTBI and ITBI, and subsequently, visualising the impingement area on native bone anatomy to highlight where prominent bone should be resected. Activity definitions and subject-specific bone geometries, with planned implants were used as inputs for the method. The ITBI and BTBI boundary and area were automatically identified using ray intersection and region growing algorithm respectively to retain the same ‘conical clearance angle’ obtained to avoid prosthetic impingement (PI). The ITBI and BTBI area was then presented with different colours to highlight the risk of impingement, and importance of resection. A clinical study with five patients after 2 years of THA was performed to validate the method. The results supported the study hypothesis, in that the predicted highest risk area (red coloured zone) was completely/majorly resected during the surgery. Therefore, this method could potentially be used to examine the effect of different pre-operative plans and hip motions on BTBI, ITBI, and PI, and to guide bony resection during THA surgery

Temporal event-structure coding in developmental dyslexia: Evidence from explicit and implicit temporal processes

As an alternative to theories positing visual or phonological deficits it has been suggested that the aetiology of dyslexia takes the form of a temporal processing deficit that may refer to impairment in the functional connectivity of the processes involved in reading. Here we investigated this idea in an experimental task designed to measure simultaneity thresholds. Fifteen children diagnosed with developmental dyslexia, alongside a matched sample of 13 normal readers undertook a series of threshold determination procedures designed to locate visual simultaneity thresholds and to assess the influence of subthreshold synchrony or asynchrony upon these thresholds. While there were no significant differences in simultaneity thresholds between dyslexic and normal readers, indicating no evidence of an altered perception, or temporal quantization of events, the dyslexic readers reported simultaneity significantly less frequently than normal readers, with the reduction largely attributable presentation of a subthreshold asynchrony. The results are discussed in terms of a whole systems approach to maintaining information processing integrity

Decline in coral cover and flattening of the reefs around Mauritius (1998–2010)

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Elliott JA, Patterson MR, Staub CG, Koonjul M, Elliott SM. 2018. Decline in coral cover and flattening of the reefs around Mauritius (1998–2010) PeerJ 6:e6014, doi: 10.7717/peerj.6014 .Coral reefs are degrading through the impacts of multiple anthropogenic stressors. How are coral reef communities going to change and how to protect them for future generations are important conservation questions. Using coral reef data from Mauritius, we examined changes in cover in 23 benthic groups for a 13-yr period and at 15 sites. Moreover, we determined which land-based stressor out of four (human population, agriculture, tourism, rainfall) correlated the most with the observed changes in coral reef cover. Among the stony corals, Acropora corals appeared to be the most impacted, decreasing in cover at many sites. However, the non-Acropora encrusting group increased in cover at several sites. The increase in abundance of dead corals and rubble at some sites also supported the observations of stony coral decline during the study period. Additionally, the decline in stony corals appeared to be more pronounced in second half of the study period for all sites suggesting that a global factor rather than a local factor was responsible for this decline. There was little change in cover for the other benthic groups, some of which were quite rare. Human population was significantly correlated with changes in coral reef cover for 11 sites, followed by tourism and agriculture. Rainfall, a proxy for runoff, did not appear to affect coral reef cover. Overall, our results showed that there has been a decline of stony coral cover especially the ones with complex morphologies, which in turn suggest that coral reefs around Mauritius have experienced a decline in habitat complexity during the study period. Our study also suggests that humans are an important factor contributing to the demise of coral reefs around the island.We would like to thank the Albion Fisheries Research Centre, Ministry of Fisheries, Government of Mauritius for providing the long-term benthic community dataset without which this work would not have been possible. Jennifer Elliott expresses her deepest gratitude to the members of her advisory committee, Peter Edmunds, Tarik Gouhier, Brian Helmuth and Steve Vollmer for their thoughtful inputs during the execution of this work. This is contribution number 384 from the Marine Science Center at Northeastern University

Response normalization and blur adaptation:data and multi-scale model

Adapting to blurred or sharpened images alters perceived blur of a focused image (M. A. Webster, M. A. Georgeson, & S. M. Webster, 2002). We asked whether blur adaptation results in (a) renormalization of perceived focus or (b) a repulsion aftereffect. Images were checkerboards or 2-D Gaussian noise, whose amplitude spectra had (log-log) slopes from -2 (strongly blurred) to 0 (strongly sharpened). Observers adjusted the spectral slope of a comparison image to match different test slopes after adaptation to blurred or sharpened images. Results did not show repulsion effects but were consistent with some renormalization. Test blur levels at and near a blurred or sharpened adaptation level were matched by more focused slopes (closer to 1/f) but with little or no change in appearance after adaptation to focused (1/f) images. A model of contrast adaptation and blur coding by multiple-scale spatial filters predicts these blur aftereffects and those of Webster et al. (2002). A key proposal is that observers are pre-adapted to natural spectra, and blurred or sharpened spectra induce changes in the state of adaptation. The model illustrates how norms might be encoded and recalibrated in the visual system even when they are represented only implicitly by the distribution of responses across multiple channels

Bystander intervention among secondary school pupils: testing an augmented Prototype Willingness Model

This study augmented the Prototype Willingness Model (PWM) to assess reactive and deliberative decision-making underpinning bystander intervention in gender-based violence contexts. There were 2079 participants (50% male, 49% female, 1% unreported), aged 11-15-years-old (M = 12.32, SD = 0.91), attending 19 secondary schools across Scotland. Participants self-reported the augmented PWM variables, then their intervention behaviour approximately one month later. Path analyses mostly supported the predicted relationships between positive and negative bidimensional attitudes, subjective norms, prototype perceptions, perceived behavioural control, and self-efficacy on intentions and willingness. Willingness predicted positive (speaking with a teacher) and negative (doing nothing) intervention in less serious violence. Self-efficacy predicted negative intervention in more serious violence. Subjective norms positively moderated the attitudes-intentions relationship. Overall, the results suggested that reactive (willingness) more so than deliberative (intention) decision-making account for intervention when young people witness gender-based violence. Additionally, the findings highlight the complexity of bystander intervention decision-making, where adding control perceptions, bidimensional attitudes, and moderators have independent contributions. Furthermore, self-comparison to the typical bystander who positively intervenes (prototype perceptions) was the strongest predictor of intentions and willingness, highlighting in a novel way the importance of image, and group membership on decision-making

Use of the ICF to investigate impairment, activity limitation and participation restriction in people using ankle-foot orthoses to manage mobility disabilities

This study investigated differences in impairment, activity limitation, participation restrictions and psychological distress between participants using ankle-foot orthoses (AFOs) as recommended, participants who did not use AFOs as recommended and participants who did not know recommendations for use.  Adults (n = 157) fitted with an AFO by an NHS Orthotic Service in Scotland completed a postal questionnaire that measured impairment, activity limitations participation restrictions and psychological distress using scales from the RAND 36-Item Health Survey 1.0 and the Hospital Anxiety and Depression Scale (HADS).  41% of participants used their AFOs as recommended, 32% did not use their AFOs as recommended and 27% did not know the recommendations for use. Participants using AFOs as recommended reported lower levels of impairment and activity limitations, indicated by higher energy levels (p = 0.005), higher physical functioning (p = 0.005), lower role-limitations due to emotional problems (p = 0.001) and lower levels of anxiety (p = 0.003) compared to people not using AFOs as recommended.  Health professionals need to ensure whether patients understand the recommendations for use of their AFO. Additionally, the results of the study support the value of evaluating patients' psychological well-being to gain a better understanding of AFO use. Implications for Rehabilitation Participants who reported using AFOs as recommended had significantly lower levels of impairment, activity limitations and anxiety compared to those who did not use their AFO as recommended. In this study, 27% of participants did not know recommendations for use of AFOs. Health professionals should give consideration as to how information, regarding wearing instructions and use of AFOs, is provided to people who are prescribed AFOs. Psychological outcomes in orthotics are rarely assessed. However, this study demonstrates there is a value in measuring psychological outcomes in orthotic management

Using a motorcycle rider behaviour questionnaire (MRBQ) to investigate the predictors of motorcyclists' crash risk

In 2005, there were over 23,000 motorcyclists (including moped riders) involved in injury road traffic crashes in Great Britain and 6,142 of these riders were killed or seriously injured (Department for Transport, 2006). In order to reduce the casualty rates it is necessary to understand why motorcycle crashes happen. The present study approached this issue by investigating the role of aberrant rider behaviour, using a Motorcycle Rider Behaviour Questionnaire (MRBQ) as a framework. The aims of the study were to test the reliability and discriminant validity of the MRBQ and to examine which MRBQ behaviours relate to crash risk. Following the Driver Behaviour Questionnaire (e.g., Reason et al., 1990), which classifies driver behaviour into a system of errors ('the failure of planned actions to achieve their intended consequences') and violations ('deliberate deviations from those practices necessary to maintain the safe operation of a potentially hazardous system'), the MRBQ measured errors and violations, but with regard to motorcycling rather than car driving (see Elliott, Baughan & Sexton, 2007). The questionnaire consisted of 43 items to measure the self-reported frequency of specific riding behaviours. The questionnaire was administered to a sample of motorcyclists via a postal survey (N = 8,666). Principal components analysis revealed a 5-factor solution (TRAFFIC ERRORS, CONTROL ERRORS, SPEED VIOLATIONS, performance of STUNTS, and use of SAFETY EQUIPMENT). Generalised linear modelling showed that, while controlling for the effects of age, experience and annual mileage, TRAFFIC ERRORS were the main predictors of crash risk. For crashes in which respondents accepted some degree of blame, CONTROL ERRORS and SPEED VIOLATIONS were also significant predictors of crash risk. Implications of the findings will be discussed in relation to deciding on which countermeasures may be most effective at reducing motorcycle casualty rates