Fretting wear and fatigue in taper junctions of modular orthopaedic implants

Multi-component, or modular, implants have a number of advantages over monoblock implants, but also a number of disadvantages related to micromotion and fretting at the taper interface. Depending on the fretting regime, either fatigue or wear damage may occur, resulting in greatly reduced fatigue lives and the production of metallic wear debris. Current revision rates of hip implants with replaceable necks are double those with fixed necks. To improve the understanding of taper performance and identify factors that can reduce wear and fatigue damage, 3-D finite element modelling of a taper connection representing the neck-stem junction of a dual modular hip prosthesis was performed. This included evaluations of short- and long-term taper strength, wear simulations and fatigue life predictions. Wear simulations included material removal due to wear. Fatigue damage calculations were performed using the critical plane Smith-Watson-Topper and Fatemi-Socie parameters together with an isotropic, linear damage accumulation model. To facilitate fatigue calculations, a unique method of tracking a consistent set of material points was presented. Taper geometry, assembly force and the magnitude of the cyclic load were all found to affect taper performance. Increasing the assembly load reduced micromotion, but reductions in wear were offset by an increase in contact pressure. Increased loads resulted in significant increases in fatigue damage. Clinically relevant wear rates were predicted, suggesting that wear volumes produced by neck-stem tapers are similar to rates of head-neck and bearing surfaces of large head metal-on-metal total hips. Fatigue crack initiation sites were predicted to be within the taper junction, located at the edges of the wear patches in regions of partial slip. Due to the evolution of the contact and sub-surface stress/strains, the inclusion of material removal was found to be critical in the prediction of both crack initiation site and fatigue damage

The New Zealand Kauri (Agathis Australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications for IntCal13

We describe here the New Zealand kauri (Agathis australis) Younger Dryas (YD) research project, which aims to undertake Δ14C analysis of ~140 decadal floating wood samples spanning the time interval ~13.1–11.7 kyr cal BP. We report 14C intercomparison measurements being undertaken by the carbon dating laboratories at University of Waikato (Wk), University of California at Irvine (UCI), and University of Oxford (OxA). The Wk, UCI, and OxA laboratories show very good agreement with an interlaboratory comparison of 12 successive decadal kauri samples (average offsets from consensus values of –7 to +4 14C yr). A University of Waikato/University of Heidelberg (HD) intercomparison involving measurement of the YD-age Swiss larch tree Ollon505, shows a HD/Wk offset of ~10–20 14C yr (HD younger), and strong evidence that the positioning of the Ollon505 series is incorrect, with a recommendation that the 14C analyses be removed from the IntCal calibration database

Digital Bridges Across Disciplinary, Practical and Pedagogical Divides: An Online Professional Master’s Program in Heritage Resource Management

Growth and diversification in heritage resource management (HRM) archaeology since the 1960s have created new demands for training the next generations of HRM leaders and for addressing persistent and counterproductive divisions between academic and applied archaeologies. The Simon Fraser University Department of Archaeology (SFU) has responded to these demands with an all-new, cohort-based, thesis-focused graduate program created by and for HRM professionals. The program’s target audience is HRM practitioners who hold Bachelor’s credentials, have initiated promising careers in HRM, and desire advanced, research-focused degrees to enable their professional capacity and upward mobility. The SFU program is structured and focused to provide intensive, predominantly online training in the four essential dimensions of HRM: law and policy, ethics and practice, business management, and research design and methods. The program has been successful through initial cohort cycles and in attracting HRM industry interest in collaboration. Industry-academic partnerships in cognate disciplines have proved effective in comparable circumstances but remain underdeveloped as bases for planning and delivering state-of-the-art training in applied archaeology and the broader field of HRM. Critical next steps in program development entail the identification of attributes of HRM futures desired by all or most HRM stakeholders and the collaborative pursuit of those desired futures

Life-Expectancy Disparities Among Adults With HIV in the United States and Canada: The Impact of a Reduction in Drug- and Alcohol-Related Deaths Using the Lives Saved Simulation Model.

Improvements in life expectancy among people living with human immunodeficiency virus (PLWH) receiving antiretroviral treatment in the United States and Canada might differ among key populations. Given the difference in substance use among key populations and the current opioid epidemic, drug- and alcohol-related deaths might be contributing to the disparities in life expectancy. We sought to estimate life expectancy at age 20 years in key populations (and their comparison groups) in 3 time periods (2004-2007, 2008-2011, and 2012-2015) and the potential increase in expected life expectancy with a simulated 20% reduction in drug- and alcohol-related deaths using the novel Lives Saved Simulation model. Among 92,289 PLWH, life expectancy increased in all key populations and comparison groups from 2004-2007 to 2012-2015. Disparities in survival of approximately a decade persisted among black versus white men who have sex with men and people with (vs. without) a history of injection drug use. A 20% reduction in drug- and alcohol-related mortality would have the greatest life-expectancy benefit for black men who have sex with men, white women, and people with a history of injection drug use. Our findings suggest that preventing drug- and alcohol-related deaths among PLWH could narrow disparities in life expectancy among some key populations, but other causes of death must be addressed to further narrow the disparities

Virulence phenotypes of low-passage clinical isolates of Nontypeable Haemophilus influenzae assessed using the chinchilla laniger model of otitis media

<p>Abstract</p> <p>Background</p> <p>The nontypeable Haemophilus influenzae (NTHi) are associated with a spectrum of respiratory mucosal infections including: acute otitis media (AOM); chronic otitis media with effusion (COME); otorrhea; locally invasive diseases such as mastoiditis; as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. These diverse clinical and genotypic findings suggest that each NTHi strain possesses a unique set of virulence factors that contributes to the course of the disease.</p> <p>Results</p> <p>The local and systemic virulence patterns of ten genomically characterized low-passage clinical NTHi strains (PittAA – PittJJ) obtained from children with COME or otorrhea were stratified using the chinchilla model of otitis media (OM). Each isolate was used to bilaterally inoculate six animals and thereafter clinical assessments were carried out daily for 8 days by blinded observers. There was no statistical difference in the time it took for any of the 10 NTHi strains to induce otologic (local) disease with respect to any or all of the other strains, however the differences in time to maximal local disease and the severity of local disease were both significant between the strains. Parameters of systemic disease indicated that the strains were not all equivalent: time to development of the systemic disease, maximal systemic scores and mortality were all statistically different among the strains. PittGG induced 100% mortality while PittBB, PittCC, and PittEE produced no mortality. Overall Pitt GG, PittII, and Pitt FF produced the most rapid and most severe local and systemic disease. A post hoc determination of the clinical origins of the 10 NTHi strains revealed that these three strains were of otorrheic origin, whereas the other 7 were from patients with COME.</p> <p>Conclusion</p> <p>Collectively these data suggest that the chinchilla OM model is useful for discriminating between otorrheic and COME NTHi strains as to their disease-producing potential in humans, and combined with whole genome analyses, point the way towards identifying classes of virulence genes.</p

Absence of Evidence Is Not Evidence of Absence: The Color-Density Relation at Fixed Stellar Mass Persists to z ~ 1

We use data drawn from the DEEP2 Galaxy Redshift Survey to investigate the relationship between local galaxy density, stellar mass, and rest-frame galaxy color. At z ~ 0.9, we find that the shape of the stellar mass function at the high-mass (log (M*/Msun) > 10.1) end depends on the local environment, with high-density regions favoring more massive systems. Accounting for this stellar mass-environment relation (i.e., working at fixed stellar mass), we find a significant color-density relation for galaxies with 10.6 < log(M*/Msun) < 11.1 and 0.75 < z < 0.95. This result is shown to be robust to variations in the sample selection and to extend to even lower masses (down to log(M*/Msun) ~ 10.4). We conclude by discussing our results in comparison to recent works in the literature, which report no significant correlation between galaxy properties and environment at fixed stellar mass for the same redshift and stellar mass domain. The non-detection of environmental dependence found in other data sets is largely attributable to their smaller samples size and lower sampling density, as well as systematic effects such as inaccurate redshifts and biased analysis techniques. Ultimately, our results based on DEEP2 data illustrate that the evolutionary state of a galaxy at z ~ 1 is not exclusively determined by the stellar mass of the galaxy. Instead, we show that local environment appears to play a distinct role in the transformation of galaxy properties at z > 1.Comment: 10 pages, 5 Figures; Accepted for publication in MNRA

Clinical features and management of children with primary ciliary dyskinesia in England

Objective In England, the National Health Service commissioned a National Management Service for children with primary ciliary dyskinesia (PCD). The aims of this study were to describe the health of children seen in this Service and compare lung function to children with cystic fibrosis (CF). Design Multi-centre service evaluation of the English National Management PCD Service. Setting Four nationally commissioned PCD centres in England. Patients 333 children with PCD reviewed in the Service in 2015; lung function data were also compared to 2970 children with CF. Results Median age at diagnosis for PCD was 2.6 years, significantly lower in children with situs inversus (1.0 vs 6.0 years, p&lt;0.0001). Compared with national data from the CF Registry, mean (SD) %predicted FEV1 76.8% in PCD (n=240) and 85.0% in CF, and FEV1 was lower in children with PCD up to the age of 15 years. Approximately half of children had some hearing impairment, with 26% requiring hearing aids. Children with a lower BMI had lower FEV1 (p&lt;0.001). One third of children had positive respiratory cultures at review, 54% of these grew Haemophilus influenzae. Conclusions We provide evidence that children with PCD in England have worse lung function than those with CF. Nutritional status should be considered in PCD management, as those with a lower BMI have significantly lower FEV1. Hearing impairment is common but seems to improve with age. Well designed and powered randomised controlled trials on management of PCD are needed to inform best clinical practice

The Origin of the 24-micron Excess in Red Galaxies

Observations with the Spitzer Space Telescope have revealed a population of red-sequence galaxies with a significant excess in their 24-micron emission compared to what is expected from an old stellar population. We identify 900 red galaxies with 0.15<z<0.3 from the AGN and Galaxy Evolution Survey (AGES) selected from the NOAO Deep Wide-Field Survey Bootes field. Using Spitzer/MIPS, we classify 89 (~10%) with 24-micron infrared excess (f24>0.3 mJy). We determine the prevalence of AGN and star-formation activity in all the AGES galaxies using optical line diagnostics and mid-IR color-color criteria. Using the IRAC color-color diagram from the IRAC Shallow Survey, we find that 64% of the 24-micron excess red galaxies are likely to have strong PAH emission features in the 8-micron IRAC band. This fraction is significantly larger than the 5% of red galaxies with f24<0.3 mJy that are estimated to have strong PAH emission, suggesting that the infrared emission is largely due to star-formation processes. Only 15% of the 24-micron excess red galaxies have optical line diagnostics characteristic of star-formation (64% are classified as AGN and 21% are unclassifiable). The difference between the optical and infrared results suggest that both AGN and star-formation activity is occurring simultaneously in many of the 24-micron excess red galaxies. These results should serve as a warning to studies that exclusively use optical line diagnostics to determine the dominant emission mechanism in the infrared and other bands. We find that ~40% of the 24-micron excess red galaxies are edge-on spiral galaxies with high optical extinctions. The remaining sources are likely to be red galaxies whose 24-micron emission comes from a combination of obscured AGN and star-formation activity.Comment: ApJ, accepted; 11 pages, 7 figures; corrected reference to IRAC Shallow Survey in abstrac

IntCal09 and Marine09 radiocarbon age calibration curves, 0-50,000yeats cal BP

The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org

Decadally resolved lateglacial radiocarbon evidence from New Zealand kauri

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Arizona Board of Regents on behalf of the University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 58 (2016): 709-733, doi: 10.1017/RDC.2016.86.The Last Glacial-Interglacial Transition (LGIT; 15,000-11,000 cal BP) was characterized by complex spatiotemporal patterns of climate change, with numerous studies requiring accurate chronological control to decipher leads from lags in global paleoclimatic, -environmental and archaeological records. However, close scrutiny of the few available tree-ring chronologies and 14C-dated sequences composing the IntCal13 radiocarbon calibration curve, indicates significant weakness in 14C calibration across key periods of the LGIT. Here, we present a decadally-resolved atmospheric 14C record derived from New Zealand kauri spanning the Lateglacial from ~13,100 - 11,365 cal BP. Two floating kauri 14C time series, curve-matched to IntCal13, serve as a radiocarbon backbone through the Younger Dryas. The floating Northern Hemisphere (NH) 14C datasets derived from the YD-B and Central European Lateglacial Master tree-ring series are matched against the new kauri data, forming a robust NH 14C time series to ~14,200 cal BP. Our results show that IntCal13 is questionable from ~12,200 - 11,900 cal BP and the ~10,400 BP 14C plateau is approximately five decades too short. The new kauri record and re-positioned NH pine 14C series offer a refinement of the international 14C calibration curves IntCal13 and SHCal13, providing increased confidence in the correlation of global paleorecords.This work was part funded by the Foundation for Research, Science and Technology (FRST)—now Ministry for Business, Innovation & Employment (MBIE)-PROP-20224-SFK-UOA), a Royal Society of New Zealand grant, the Australian Research Council (FL100100195 and DP0664898) and the Natural Environment Research Council (NE/H009922/1, NE/I007660/1, NER/A/S/2001/01037 and NE/H007865/1)