21,477 research outputs found

    A new strategy for case-based reasoning retrieval using classification based on association

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    This paper proposes a novel strategy, Case-Based Reasoning Using Association Rules (CBRAR) to improve the performance of the Similarity base Retrieval SBR, classed frequent pattern trees FP-CAR algorithm, in order to disambiguate wrongly retrieved cases in Case-Based Reasoning (CBR). CBRAR use class as-sociation rules (CARs) to generate an optimum FP-tree which holds a value of each node. The possible advantage offered is that more efficient results can be gained when SBR returns uncertain answers. We compare the CBR Query as a pattern with FP-CAR patterns to identify the longest length of the voted class. If the patterns are matched, the proposed strategy can select not just the most similar case but the correct one. Our experimental evaluation on real data from the UCI repository indicates that the proposed CBRAR is a better approach when com-pared to the accuracy of the CBR systems used in our experiments

    Impacts of Unattended Train Operations (UTO) on Productivity and Efficiency in Metropolitan Railways

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    Urban metro subway systems (metros) around the world are choosing increasing levels of automation for new and existing lines: the global length of metro lines capable of unattended train operation (UTO) is predicted to triple in the next 10 years. Despite significant investment in this technology, empirical evidence for the financial and service quality impacts of UTO in metros remains scarce. This study used questionnaires and semistructured interviews with the Community of Metros and Nova Group benchmarking groups to assemble emerging evidence of how automation affected costs, staffing, service capacity, and reliability. The results from an analysis of data from 23 lines suggested that UTO could reduce staff numbers by 30% to 70%, with the amount of wage cost reduction depending on whether staff on UTO lines were paid more. On the basis of the experience of seven metros, the capital costs of lines capable of UTO were higher, but the internal rate of return had been estimated by two metros at 10% to 15%. Automated lines were capable of operating at the highest service frequencies of up to 42 trains per hour, and the limited available data suggested that automated lines were more reliable. The findings indicated that UTO was a means to a more flexible and reliable operating model that could increase metro productivity and efficiency. The study identified important work needed to understand the impacts of UTO and identify where statistical analyses would add value once sufficiently large data sets became available

    Evaluation of cystatin C for the detection of chronic kidney disease in cats

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    BackgroundSerum cystatin C (sCysC) and urinary cystatin C (uCysC) are potential biomarkers for early detection of chronic kidney disease (CKD) in cats. An in-depth clinical validation is required. ObjectivesTo evaluate CysC as a marker for CKD in cats and to compare assay performance of the turbidimetric assay (PETIA) with the previously validated nephelometric assay (PENIA). AnimalsNinety cats were included: 49 CKD and 41 healthy cats. MethodsSerum CysC and uCysC concentrations were prospectively evaluated in cats with CKD and healthy cats. Based on plasma exo-iohexol clearance test (PexICT), sCysC was evaluated to distinguish normal, borderline, and low GFR. Sensitivity and specificity to detect PexICT<1.7mL/min/kg were calculated. Serum CysC results of PENIA and PETIA were correlated with GFR. Statistical analysis was performed using general linear modeling. ResultsCats with CKD had significantly higher meanSD sCysC (1.4 +/- 0.5mg/L) (P<.001) and uCysC/urinary creatinine (uCr) (291 +/- 411mg/mol) (P<.001) compared to healthy cats (sCysC 1.0 +/- 0.3 and uCysC/uCr 0.32 +/- 0.97). UCysC was detected in 35/49 CKD cats. R-2 values between GFR and sCysC or sCr were 0.39 and 0.71, respectively (sCysC or sCr=+GFR+epsilon). Sensitivity and specificity were 22 and 100% for sCysC and 83 and 93% for sCr. Serum CysC could not distinguish healthy from CKD cats, nor normal from borderline or low GFR, in contrast with sCr. ConclusionSerum CysC is not a reliable marker of reduced GFR in cats and uCysC could not be detected in all CKD cats

    Ethnic Differences in Carotid Intima-Media Thickness Between UK Children of Black African-Caribbean and White European Origin.

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    BACKGROUND AND PURPOSE: UK black African-Caribbean adults have higher risks of stroke than white Europeans and have been shown to have increased carotid intima-media thickness (cIMT). We examined whether corresponding ethnic differences in cIMT were apparent in childhood and, if so, whether these could be explained by ethnic differences in cardiovascular risk markers. METHODS: We conducted a 2-stage survey of 939 children (208 white European, 240 black African-Caribbean, 258 South Asian, 63 other Asian, 170 other ethnicity), who had a cardiovascular risk assessment and measurements of cIMT at mean ages of 9.8 and 10.8 years, respectively. RESULTS: Black African-Caribbean children had a higher cIMT than white Europeans (mean difference, 0.014 mm; 95% CI, 0.008-0.021 mm; P<0.0001). cIMT levels in South Asian and other Asian children were however similar to those of white Europeans. Among all children, cIMT was positively associated with age, systolic and diastolic blood pressure and inversely with combined skinfold thickness and serum triglyceride. Mean triglyceride was lower among black African-Caribbeans than white Europeans; blood pressure and skinfold thickness did not differ appreciably. However, adjustment for these risk factors had little effect on the cIMT difference between black African-Caribbeans and white Europeans. CONCLUSIONS: UK black African-Caribbean children have higher cIMT levels in childhood; the difference is not explained by conventional cardiovascular risk markers. There may be important opportunities for early cardiovascular prevention, particularly in black African-Caribbean children

    A boundary layer scaling technique for estimating near-surface wind energy using numerical weather prediction and wind map data

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    A boundary layer scaling (BLS) method for predicting long-term average near-surface wind speeds and power densities was developed in this work. The method was based on the scaling of reference climatological data either from long-term average wind maps or from hourly wind speeds obtained from high-resolution Numerical Weather Prediction (NWP) models, with case study applications from Great Britain. It incorporated a more detailed parameterisation of surface aerodynamics than previous studies and the predicted wind speeds and power densities were validated against observational wind speeds from 124 sites across Great Britain. The BLS model could offer long-term average wind speed predictions using wind map data derived from long-term observational data, with a mean percentage error of 1.5 % which provided an improvement on the commonly used NOABL (Numerical Objective Analysis of Boundary Layer) wind map. The boundary layer scaling of NWP data was not, however, able to improve upon the use of raw NWP data for near surface wind speed predictions. However, the use of NWP data scaled by the BLS model could offer improved power density predictions compared to the use of the reference data sets. Using a vertical scaling of the shape factor of a Weibull distribution fitted to the BLS NWP data, power density predictions with a 1 % mean percentage error were achieved. This provided a significant improvement on the use of a fixed shape factor which must be utilised when only long-term average wind speeds are available from reference wind maps. The work therefore highlights the advantages that use of a BLS model for wind speed and NWP data for power density predictions can offer for small to medium scale wind energy resource assessments, potentially facilitating more robust annual energy production and financial assessments of prospective small and medium scale wind turbine installations

    A mixed reality telepresence system for collaborative space operation

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    This paper presents a Mixed Reality system that results from the integration of a telepresence system and an application to improve collaborative space exploration. The system combines free viewpoint video with immersive projection technology to support non-verbal communication, including eye gaze, inter-personal distance and facial expression. Importantly, these can be interpreted together as people move around the simulation, maintaining natural social distance. The application is a simulation of Mars, within which the collaborators must come to agreement over, for example, where the Rover should land and go. The first contribution is the creation of a Mixed Reality system supporting contextualization of non-verbal communication. Tw technological contributions are prototyping a technique to subtract a person from a background that may contain physical objects and/or moving images, and a light weight texturing method for multi-view rendering which provides balance in terms of visual and temporal quality. A practical contribution is the demonstration of pragmatic approaches to sharing space between display systems of distinct levels of immersion. A research tool contribution is a system that allows comparison of conventional authored and video based reconstructed avatars, within an environment that encourages exploration and social interaction. Aspects of system quality, including the communication of facial expression and end-to-end latency are reported

    Achieving Low Carbon Thinking Everywhere in Infrastructure Delivery

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    Low Carbon Thinking (LCT) refers to achieving an overall carbon emission reduction through embedding such thinking in the lifecycle of infrastructure. It spans the effective use of technology and policy drivers geared to support the utilisation of low carbon resources, energy efficiency measures, efficient process and appliances, and the empowerment of consumers. Such an approach will ensure meeting our climate goals in more timely and efficient manner, while bringing greater opportunities and economic growth for society. Due to the ever-present competing factors affecting energy and its infrastructure and their link to emissions and climate change, this work aims to highlight approaches that convey the interplay between these issues and provide a synthesis of the current status of thinking in the field. In addition, this work also aims to identify areas where additional evidence and further research are needed to support decisions that can propel the UK into a low carbon pathway in its energy mix

    Open Problems on Central Simple Algebras

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    We provide a survey of past research and a list of open problems regarding central simple algebras and the Brauer group over a field, intended both for experts and for beginners.Comment: v2 has some small revisions to the text. Some items are re-numbered, compared to v
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