3,509 research outputs found

    Rota's basis conjecture for paving matroids

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    Rota conjectured that, given n disjoint bases of a rank-n matroid M, there are n disjoint transversals of these bases that are all bases of M. We prove a stronger statement for the class of paving matroids

    Irish Trainees Continuing to Emigrate.

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    The Medical Council’s spotlight report on ‘Trainee Career and Retention Intentions’, to be released later in October 2015, will report further findings from its 2014 Trainee National Experience Survey1, to which over 1,600 non consultant hospital doctors (NCHDs) in training posts responded. This latest report will show that close to half of trainees – the cornerstone of hospital care and the future cornerstone of our health services – intend to pursue their careers outside of Ireland. Most worrying is that those in Higher Specialist Training are more likely to leave, resulting in greater loss to the Irish health system in terms of investment of effort and money, and lost expertise. The findings are consistent with a growing body of evidence on the medical workforce crisis facing Ireland. In early 2015, 88% of Irish medical students reported their intentions to leave Ireland on graduation, though close to half said they would return. However, the assumption that most doctors will return was dispelled in our 2015 survey of 307 emigrant Irish trained doctors who had left Ireland between 2008 and 2013.Since leaving, there had been a three-fold rise in those intending to remain abroad permanently and only a quarter intended to return to practice in Ireland

    Is there an integrative center in the vertebrate brain-stem? A robotic evaluation of a model of the reticular formation viewed as an action selection device

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    Neurobehavioral data from intact, decerebrate, and neonatal rats, suggests that the reticular formation provides a brainstem substrate for action selection in the vertebrate central nervous system. In this article, Kilmer, McCulloch and Blum’s (1969, 1997) landmark reticular formation model is described and re-evaluated, both in simulation and, for the first time, as a mobile robot controller. Particular model configurations are found to provide effective action selection mechanisms in a robot survival task using either simulated or physical robots. The model’s competence is dependent on the organization of afferents from model sensory systems, and a genetic algorithm search identified a class of afferent configurations which have long survival times. The results support our proposal that the reticular formation evolved to provide effective arbitration between innate behaviors and, with the forebrain basal ganglia, may constitute the integrative, ’centrencephalic’ core of vertebrate brain architecture. Additionally, the results demonstrate that the Kilmer et al. model provides an alternative form of robot controller to those usually considered in the adaptive behavior literature

    Determining the feasibility of chemical vapor deposition process for the production of dispersoid strengthened chromium alloys Final report

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    Chemical vapor deposition process for production of high purity chromium metal containing thorium oxide dispersion materia

    A Preliminary Quantification of the Impacts of Aspen to Conifer Succession on Water Yield Within the Colorado River Basin (A Process Aggravating the Salt Pollution Problem)

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    Heat pulse velocity techniques were developed for effectively monitoring water movement in aspen (Populus ttremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (Picea engelmannii). Once the techniques were perfected, transpiration was monitored in replicated trees of each species for one year. This data was used to modify the plant activity index and the crop coefficient for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling indicate 18.5 cm(7.3 in) net loss of moisture available for stream flow when spruce replace aspen, and a loss of 7.1 cm (2.8 in) when fir forests cover the watershed. The aspen to conifer successional trend is therefore significantly reducing water yields within the Colorado River Basin, water that could be used to dilute salt downstream from the high water-yielding watersheds

    Assessment of the clinical utility of adding common single nucleotide polymorphism genetic scores to classical risk factor algorithms in coronary heart disease risk prediction in UK men

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    Background: Risk prediction algorithms for coronary heart disease (CHD) are recommended for clinical use. However, their predictive ability remains modest and the inclusion of genetic risk may improve their performance. Methods: QRISK2 was used to assess CHD risk using conventional risk factors (CRFs). The performance of a 19 single nucleotide polymorphism (SNP) gene score (GS) for CHD including variants identified by genome-wide association study and candidate gene studies (weighted using the results from the CARDIoGRAMplusC4D meta-analysis) was assessed using the second Northwick Park Heart Study (NPHSII) of 2775 healthy UK men (284 cases). To improve the GS, five SNPs with weak evidence of an association with CHD were removed and replaced with seven robustly associated SNPs – giving a 21-SNP GS. Results: The weighted 19 SNP GS was associated with lipid traits (p<0.05) and CHD after adjustment for CRFs, (OR=1.31 per standard deviation, p=0.03). Addition of the 19 SNP GS to QRISK2 showed improved discrimination (area under the receiver operator characteristic curve 0.68 vs. 0.70 p=0.02), a positive net reclassification index (0.07, p=0.04) compared to QRISK2 alone and maintained good calibration (p=0.17). The 21-SNP GS was also associated with CHD after adjustment for CRFs (OR=1.39 per standard deviation, 1.42×10−3), but the combined QRISK2 plus GS score was poorly calibrated (p=0.03) and showed no improvement in discrimination (p=0.55) or reclassification (p=0.10) compared to QRISK2 alone. Conclusions: The 19-SNP GS is robustly associated with CHD and showed potential clinical utility in the UK population

    Different conformations of the German shepherd dog breed affect its posture and movement

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    Funder: The Kennel Club Charitable TrustAbstract: The conformation of the German shepherd dog (GSD) varies considerably within the breed. These differences may result in large variation in the movement and limb loading and undesirable consequences to their musculoskeletal health. This study aimed to investigate the relationship between conformation and biomechanical measures in 60 GSDs. Full body kinematic and kinetic measures were computed from 3D motion capture and pressure data. The dogs were divided into groups based on their back slope and curvature. Correlation analysis and statistical differences between groups showed that GSDs with a greater back slope have a greater contact area in their forelimbs and place them closer together when standing (n = 60). During trot, the dogs with sloped back showed a greater vertical force in the forelimbs and a greater mid-thoracic flexion (n = 60). Unilateral differences were found in the stifle flexion, hock flexion and hock adduction, suggesting greater movement asymmetry with an increase in the back slope (n = 30). In conclusion, several biomechanical parameters are affected by the GSD’s slope of the back and not by its curvature. Further studies are required to determine whether the variation in movement, posture and conformation within the breed relates to an increased susceptibility to musculoskeletal disorders

    Biomechanical comparison of standing posture and during trot between German shepherd and Labrador retriever dogs.

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    Funder: The Kennel Club Charitable Trust; Grant(s): Project ID: 4093 Project Code: 9653It is widely accepted that canine breeds stand and move differently. The prevalence of various musculoskeletal disorders such as hip and elbow dysplasia is also different between breeds. German shepherd dog (GSD) and Labrador retriever dog (LRD) are two large breeds with different conformations that have high prevalence of these disorders. This study quantifies the movement and standing posture of twelve healthy GSDs and twelve healthy LRDs to identify biomechanical similarities and differences that may be linked to sub-optimal hip and elbow mechanics. A pressure walkway and a motion capture system obtained measures of kinetics, kinematics and conformation during standing and trot. During standing, LRDs carry a greater percentage of the weight on the forelimbs (69%±5% vs. GSDs: 62%±2%, p<0.001) and their body Centre of Pressure (CoP) is located more cranially (p<0.001). GSDs had a greater pelvic tilt (79°±8 vs. 66°±9°, p = 0.004), more flexed stifles (44°±9° vs. LRDs: 34°±10°, p<0.05) and hocks (58°±11° vs. 26°±9°, p<0.01) and more extended hips (-10°±11° vs. 30°±12°, p<0.001). During trot, the GSDs' CoP had a longer anterior-posterior trajectory (151%±22% vs. LRDs: 93%±25% of the withers height, p<0.001). Stride parameters and loading of limbs were similar when normalised to the size and weight of the dog, respectively. The LRDs had a more extended thoracolumbar angle (p<0.001) and a less flexed lumbosacral angle (p<0.05). The LRDs' hip remained flexed during trot whereas the GSDs' hip joint was less flexed during swing (p<0.001) and more extended in late stance and early swing (p<0.001). In conclusion, the LRDs and GSDs differ in the way they stand and move and this would result in different loading pattern of the joints. Further investigation is required to determine the extent to which biomechanical differences are linked to musculoskeletal problems presented clinically
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