1,115 research outputs found

    Influence of wear algorithm formulation on computational-experimental corroboration

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    Experimental wear testing is well-established as an important part of the TKR design process. Recently, in-silico models have proved their value to corroborate long-term in-vitro results on a much shorter timescale [1]. Both FE-based models & multi-body dynamics can be used to predict contact pressures, sliding distances and cross-shear (CS). The precise mechanisms of wear are not sufficiently understood to permit analytical calculations, and so empirical formulations are used to estimate wear depths & volumes.Most early simulations were based on a modified Archard/Lancaster formulation; more recently a number of alternative formulations for cross shear have been proposed; it is unclear which is the most robust or accurate for the widest range of activities. The aim of this study was to develop and corroborate a fast in-silico wear model, and use this to compare different wear formulations

    The Definition of Insurance: Implications for a Health Insurance Demand Model

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    This paper uses data from the 1977-78 National Medical Care Expenditures Survey to evaluate five different measures of insurance: a family\u27s expected out-of-pocket payment for medical care, the expected value of the indemnity (fee-for-service) benefits from an insurance policy for a family, the percentage of the expected loss that the insured pays, the policy premium, and the policy limit of coverage. The study provides information that can help us understand whose insurance coverage will change significantly as a result of health care reform. For example, it shows that those with low income (such as minorities, families headed by females, and unmarried individuals) on average purchase low amounts of health insurance. These groups would benefit considerably if health care reform institutes universal coverage. Conversely, whites, families headed by males, married individuals, and those with high incomes on average have considerable health insurance coverage

    ENVIRONMENTAL AND BIOLOGICAL CONSEQUENCES OF MICROPLASTIC WITHIN MARINE HABITATS

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    Merged with duplicate record 10026.1/1932 on 06.20.2017 by CS (TIS)Large pieces of plastic greater than a millimetre in diameter contaminate marine habitats worldwide and the associated environmental problems are well documented. In addition tiny fragments of plastic debris less than a millimetre in size have recently been reported. This thesis examines the distribution and environmental consequences of microscopic particles of plastic within marine habitats. To quantify the relative influence of wind and depositional environment on the accumulation of plastic debris, a mensurative experiment was conducted in a macrotidal Estuary. The overall trend was that material accumulated in down-wind sites. However, the relative importance of wind as a transport agent depended on the size and density of the plastic. Natural sediments are transported according to their size; but the extent to which models of sediment dynamics could be applied to the transport of plastic debris remains untested. I examined relationships between the abundance of microplastic debris and sediment particle size, latitude and human population density using samples from sandy shores worldwide. Microplastic was found at every location, showing the global extent of this contamination and there was a significant positive correlation between human population density and microplastic abundance. Sewage sludge disposal grounds were examined as potential sources of microplastic. Replicate sediment grab samples showed that disposal grounds near Plymouth and Newcastle (UK) had greater abundance of microplastic debris compared to reference sites. To investigate the biological consequences of ingesting clean microplastic particles the mussel, Mytilus edulis (L.) was used as a model organism. The fate of ingested plastic was tracked within the body tissues using a laboratory trial. Mussels were exposed to 3.0 and 9.61µm microplastic particles in seawater for 3 hours and then transferred to clean conditions. After 3 days ingested microplastic had accumulated in the circulatory fluid of M edulis. Smaller particles 3.0 µm were present in the haemolymph in consistently higher numbers than larger particles, and both sizes were still present after 48 days. There were no measurable changes in organismal health from ingestion of this material. However, it has been frequently suggested that plastics debris may transfer chemical contaminants to marine life. To test this, the sorption-affinity of candidate environmental hydrophobic contaminants from aqueous solution onto microscopic particles of polyvinylchloride and similar sized particles of sand was compared. Chemical analysis confirmed that polyvinylchloride absorbed more contaminants than sand. A second experiment examined the bioavailability of sorbed contaminants and chemical additives that are incorporated into plastic during manufacture. Laboratory trials using Arenicola marina (L.) showed that the sorbed contaminants and additives bioconcentrated in gut tissues leading to deleterious biological effects. In conclusion, microplastic debris is a ubiquitous form of contamination and when ingested, this material can translocate from the gut to the circulatory system and haemocytes, and can transfer chemicals into animal tissues, and reduce the health of animals near the base of the food chain. The implications of these findings are discussed in relation to potential measures to improve the management of plastics in society and to reduce the amount of plastic entering the environment

    Farm-gate nitrogen balances on intensive dairy farms in the south west of Ireland

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    peer-reviewedNitrogen management and farm-gate N balances were evaluated on 21 intensive dairy farms in the south west of Ireland for each of four years (2003 to 2006). The mean annual stocking density was equivalent to 202 kg/ha (s.d. 29.6) of N excreted by livestock on the farm. The mean annual farm-gate N surplus (imports – exports) declined between 2003 and 2006 (277 to 232 kg/ha, s.e. 6.8; P < 0.001) due to a decline in annual N imports (fertilizer, feed and imported manures; 335 to 288 kg/ha, s.e. 6.9; P < 0.001). Overall annual fertilizer N use on the farms decreased during the study period (266 to 223 kg/ha, s.e. 6.5; P < 0.001) mainly due to lower inputs for the first application in spring and for the production of first-cut silage. These decreases were partly offset by applying more slurry in spring for early grazing and for first-cut silage. The introduction of white clover resulted in lower N imports on four farms. Export of N from farms was unaffected by reductions in N imports. The mean efficiency of N use tended to increase over time (0.18 in 2003 to 0.20 in 2006). The large variation in quantities of fertilizer N applied on farms with similar stocking densities suggests potential for further improvements in the efficiency of N use. In terms of fertilizer N use, complying with S.I. No. 378 of 2006 did not require major changes in the N management practiceson 19 of the farms.This project was part-funded by the European Research and Development Fund under INTERREG IIIB: Green Dairy Project N° 100 and partly by the Dairy Levy. Financial support for post-graduate students involved in this study was provided by the Teagasc Walsh Fellowship Scheme

    Multiple-membership multiple-classification models for social network and group dependences

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    The social network literature on network dependences has largely ignored other sources of dependence, such as the school that a student attends, or the area in which an individual lives. The multilevel modelling literature on school and area dependences has, in turn, largely ignored social networks. To bridge this divide, a multiple-membership multiple-classification modelling approach for jointly investigating social network and group dependences is presented. This allows social network and group dependences on individual responses to be investigated and compared. The approach is used to analyse a subsample of the Adolescent Health Study data set from the USA, where the response variable of interest is individual level educational attainment, and the three individual level covariates are sex, ethnic group and age. Individual, network, school and area dependences are accounted for in the analysis. The network dependences can be accounted for by including the network as a classification in the model, using various network configurations, such as ego-nets and cliques. The results suggest that ignoring the network affects the estimates of variation for the classifications that are included in the random part of the model (school, area and individual), as well as having some influence on the point estimates and standard errors of the estimates of regression coefficients for covariates in the fixed part of the model. From a substantive perspective, this approach provides a flexible and practical way of investigating variation in an individual level response due to social network dependences, and estimating the share of variation of an individual response for network, school and area classifications

    Mucosal Immunity and Self-Reported Upper Respiratory Symptoms in a Cohort of Premier League Academy Soccer Players

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    Introduction The measurement of a number of salivary biomarkers has become common place in Premier League Soccer teams, in an attempt to monitor responses to training, competition, lifestyle factors and stress. The purpose of this paper was to analyse markers of mucosal immunity through the second half of a competitive season in a cohort of Premier League Academy players. Methods A total of 256 saliva samples were taken during routine monitoring of a cohort 16 players in the under-18 age group of an English Premier League club Academy. Morning saliva samples were collected weekly over a period of 17 weeks between the christmas break and the end of the competitive season. The IgA concentration of the samples was determined using an IPRO Point of Care device and the remaining sample was sent to a remote laboratory for the subsequent determination of IgG and alpha-amylase (sAA) by ELISA. On any occasion that players perceived upper respiratory symptoms (URS) a WURSS questionnaire was completed and extra saliva samples (115) taken each day until symptoms had ceased. Results IgA, IgG and sAA were highly variable between subjects (with CV 57.6, 81.4 and 59.5% respectively) and within subjects (48.5, 65.9, and 46.4%) through the 17 week period. Weekly group mean (±SD) IgA ranged from 114.1 (57.5) to 318.4 (176) μg/ml, IgG from 27.4 (23.7) to 61.7 ( 30.5) μg/ml and sAA from 191.9 (100.7) to 370.6 (203) μg/ml, but no significant differences were seen due to the high individual variability. During the 17 week study period 26 incidences of URS were reported by 15 of the players and were monitored using WURSS and subsequent saliva testing. A drop in IgA by more than 40% from individual healthy mean values, within two weeks of each URS episode, was seen in 14 of the 26 episodes. A drop in IgA/sAA ratio by more than 40% of individual healthy mean values, within two weeks of each URS episode, was seen in 19 of the 26 episodes. However, using the same individualised criteria for IgA and IgA/sAA ratio there were 28 and 38 samples, respectively, where such drops did not lead to URS, with several such occurences seen within the same individuals. In cases where URS were reported, subsequent IgA during perceived symptoms was seen to rise 40% above individual healthy mean levels in 15 of the 26 episodes. Conclusion Salivary markers of mucosal immunity, particularly IgA and sAA when expressed as percentages of healthy baseline norms have good potential for predicting self-reported URS in this cohort of elite under 18 soccer players. Rather than remain suppressed through symptoms, these markers were often then seen to rise by more than 40%. Creation of individual profiles of such salivary markers seems warranted for purposes of monitoring

    Ludii -- The Ludemic General Game System

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    While current General Game Playing (GGP) systems facilitate useful research in Artificial Intelligence (AI) for game-playing, they are often somewhat specialised and computationally inefficient. In this paper, we describe the "ludemic" general game system Ludii, which has the potential to provide an efficient tool for AI researchers as well as game designers, historians, educators and practitioners in related fields. Ludii defines games as structures of ludemes -- high-level, easily understandable game concepts -- which allows for concise and human-understandable game descriptions. We formally describe Ludii and outline its main benefits: generality, extensibility, understandability and efficiency. Experimentally, Ludii outperforms one of the most efficient Game Description Language (GDL) reasoners, based on a propositional network, in all games available in the Tiltyard GGP repository. Moreover, Ludii is also competitive in terms of performance with the more recently proposed Regular Boardgames (RBG) system, and has various advantages in qualitative aspects such as generality.Comment: Accepted at ECAI 202

    Construction of a laser combiner for dual fluorescent single molecule imaging of pRNA of phi29 DNA packaging motor

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    A customized laser combiner was designed and constructed for dual channel single molecule imaging. The feasibility of a combiner-incorporated imaging system was demonstrated in studies of single molecule FRET. Distance rulers made of dual-labeled dsDNA were used to evaluate the system by determining the distance between one FRET pair. The results showed that the system is sensitive enough to distinguish between distances differing by two base pair and the distances calculated from FRET efficiencies are close to those documented in the literature. The single molecule FRET with the dual-color imaging system was also applied to reconstructed phi29 motor pRNA monomers. Finally, techniques for dual laser alignment and tuning of laser power for dual-color excitation are discussed
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