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

What Happens in a Moment

International audienc

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

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

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

Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene.

The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well-known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ13C analysis and δ15N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ15N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue-specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ15N values than modern populations. Amino acid δ15N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts

Conditional or unconditional? The effects of implementation intentions on driver behavior

Implementation intentions (IF-THEN plans) exert conditional effects on behavior, meaning that their ability to change behavior is conditional upon encountering the critical situation specified in the IF component of the plan. In the present study, we tested whether implementation intentions can exert unconditional effects on behavior. Consistent with the process of operant generalization, we hypothesized that implementation intentions would change behavior, not only in situations that are contextually identical to those specified in the IF component but also in contextually similar situations. Implementation intentions were not expected to generate behavior-change in contextually different situations to those specified. Participants (N = 139) completed questionnaires measuring speeding behavior and motivation to speed. Experimental participants then specified implementation intentions to avoid speeding in critical situations that were either contextually identical, similar or different to those subsequently encountered on a driving simulator. Control participants received educational information about the risks of speeding. All participants then drove on a driving simulator. Consistent with the hypotheses, participants in both the contextually identical and similar conditions exceeded the speed limit less frequently than did controls. There was no difference in speeding behavior between the contextually different and control conditions. Implications of the findings for behavior-change are discussed

Assessing the Effect of Stellar Companions from High-Resolution Imaging of Kepler Objects of Interest

We report on 176 close (<2") stellar companions detected with high-resolution imaging near 170 hosts of Kepler Objects of Interest. These Kepler targets were prioritized for imaging follow-up based on the presence of small planets, so most of the KOIs in these systems (176 out of 204) have nominal radii <6 R_E . Each KOI in our sample was observed in at least 2 filters with adaptive optics, speckle imaging, lucky imaging, or HST. Multi-filter photometry provides color information on the companions, allowing us to constrain their stellar properties and assess the probability that the companions are physically bound. We find that 60 -- 80% of companions within 1" are bound, and the bound fraction is >90% for companions within 0.5"; the bound fraction decreases with increasing angular separation. This picture is consistent with simulations of the binary and background stellar populations in the Kepler field. We also reassess the planet radii in these systems, converting the observed differential magnitudes to a contamination in the Kepler bandpass and calculating the planet radius correction factor, $X_R = R_p (true) / R_p (single)$. Under the assumption that planets in bound binaries are equally likely to orbit the primary or secondary, we find a mean radius correction factor for planets in stellar multiples of $X_R = 1.65$. If stellar multiplicity in the Kepler field is similar to the solar neighborhood, then nearly half of all Kepler planets may have radii underestimated by an average of 65%, unless vetted using high resolution imaging or spectroscopy.Comment: 23 pages, 12 figures. Accepted for publication in The Astronomical Journa

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

Mucin binding reduces colistin antimicrobial activity

Colistin has found increasing use in treating drug-resistant bacterial lung infections, but potential interactions with pulmonary biomolecules have not been investigated. We postulated that colistin, like aminoglycoside antibiotics, may bind to secretory mucin in sputum or epithelial mucin that lines airways, reducing free drug levels. To test this hypothesis, we measured binding of colistin and other antibiotics to porcine mucin, a family of densely glycosylated proteins used as a surrogate for human sputum and airway mucin. Antibiotics were incubated in dialysis tubing with or without mucin, and concentrations of unbound antibiotics able to penetrate the dialysis tubing were measured over time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The percentage of antibiotic measured in the dialysate after 4 h in the presence of mucin, relative to the amount without mucin, was 15% for colistin, 16% for polymyxin B, 19% for tobramycin, 52% for ciprofloxacin, and 78% for daptomycin. Antibiotics with the strongest mucin binding had an overall polybasic positive charge, whereas those with comparatively little binding were less basic. When comparing MICs measured with or without added mucin, colistin and polymyxin B showed >100-fold increases in MICs for multiple Gram-negative bacteria. Preclinical evaluation of mucin binding should become a standard procedure when considering the potential pulmonary use of new or existing antibiotics, particularly those with a polybasic overall charge. In the airways, mucin binding may reduce the antibacterial efficacy of inhaled or intravenously administered colistin, and the presence of sub-MIC effective antibiotic concentrations could result in the development of antibiotic resistance