7,744 research outputs found

    Contrasting Treatments of Recall Bias in Two Epidemiological Settings

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    The author contrasts the treatment of recall bias in the literature on induced abortions and breast cancer, and on environmental tobacco smoke and lung cancer

    Does size matter? Experiences and perspectives of BIM implementation from large and SME construction contractors

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    This paper presents the findings of a qualitative study into the experiences and perspectives of large and SME construction contractors towards the implementation of Building Information Modelling (BIM) within their organisations. Results of the survey were statistically analysed to test for similarity and significant variations between the two groups. The results confirmed that both groups were equally aware of the perceived benefits of BIM, but found that the largest barriers to implementation were the costs associated with the technology and training requirements. Significant differences between the groups included plans to implement BIM and concerns with legal and commercial barriers

    PRICE TRANSMISSION, THRESHOLD BEHAVIOR, AND ASYMMETRIC ADJUSTMENT IN THE U.S. PORK SECTOR

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    The US pork sector has experienced many significant structural changes in recent years. Such changes may have influenced price dynamics and transmission of shocks through marketing channels. We investigate linkages among farm, wholesale, and retail markets using weekly price data for the period covering 1987 through 1998. Our analysis uses a threshold cointegration model that permits asymmetric adjustment to positive and negative price shocks. Our results reveal important asymmetries. Our results are consistent with existing literature which has determined that price adjustment patterns are unidirectional and that information tends to flow from farm, to wholesale, to retail markets.asymmetric price transmission, vertical price transmission, error correction, thresholds, pork markets, Demand and Price Analysis, Livestock Production/Industries,

    Towards a Reference Terminology for Ontology Research and Development in the Biomedical Domain

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    Ontology is a burgeoning field, involving researchers from the computer science, philosophy, data and software engineering, logic, linguistics, and terminology domains. Many ontology-related terms with precise meanings in one of these domains have different meanings in others. Our purpose here is to initiate a path towards disambiguation of such terms. We draw primarily on the literature of biomedical informatics, not least because the problems caused by unclear or ambiguous use of terms have been there most thoroughly addressed. We advance a proposal resting on a distinction of three levels too often run together in biomedical ontology research: 1. the level of reality; 2. the level of cognitive representations of this reality; 3. the level of textual and graphical artifacts. We propose a reference terminology for ontology research and development that is designed to serve as common hub into which the several competing disciplinary terminologies can be mapped. We then justify our terminological choices through a critical treatment of the ‘concept orientation’ in biomedical terminology research

    MODELING CATASTROPHIC WEATHER EVENTS AND THE RISKS OF ANIMAL WASTE SPILLS IN THE COASTAL PLAIN OF NORTH CAROLINA

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    This paper considers probabilistic models of hurricane-induced animal waste lagoon failures in North Carolina. A substantial number of waste lagoons exist in areas prone to hurricane damages. We evaluate expected losses which represent actuarially-fair insurance premium rates for a plan that would indemnify producers against damages from lagoon failures. Our results imply annual premiums ranging from under 100peryeartoover100 per year to over 2,062 per year. An interesting result is that those areas with the highest levels of expected loss are also those areas with the greatest concentration of waste lagoons.Environmental Economics and Policy, Livestock Production/Industries,

    Improvements to context based self-supervised learning

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    We develop a set of methods to improve on the results of self-supervised learning using context. We start with a baseline of patch based arrangement context learning and go from there. Our methods address some overt problems such as chromatic aberration as well as other potential problems such as spatial skew and mid-level feature neglect. We prevent problems with testing generalization on common self-supervised benchmark tests by using different datasets during our development. The results of our methods combined yield top scores on all standard self-supervised benchmarks, including classification and detection on PASCAL VOC 2007, segmentation on PASCAL VOC 2012, and "linear tests" on the ImageNet and CSAIL Places datasets. We obtain an improvement over our baseline method of between 4.0 to 7.1 percentage points on transfer learning classification tests. We also show results on different standard network architectures to demonstrate generalization as well as portability. All data, models and programs are available at: https://gdo-datasci.llnl.gov/selfsupervised/.Comment: Accepted paper at CVPR 201

    A Multi-Region Analysis of the Acquisition, Consolidation and Retention of Spatial Memory in the Morris Water Maze using Immediate Early Gene Imaging

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    The Morris water maze has been extensively used in the study of spatial learning and memory, and a number of hippocampal, parahippocampal and neocortical brain regions have been identified as necessary for successful performance in this task. Immediate Early Genes (IEGs) have been implicated in learning and memory processes, and are used as markers of neural activity in a brain region in response to learning tasks. The use of adequate control conditions in these tasks has been identified as important, and we devised a novel control condition in an attempt to address these concerns. We examined the expression of IEGs over the course of spatial learning, finding that Zif268 expression was upregulated in a number of regions during early learning, and that c-Fos was upregulated during late learning. We investigated the role of IEGs in cellular consolidation at different time-points in the hours following learning, but we did not find support for multiple waves of IEG expression as previously reported in the literature. We also examined the course of systems consolidation by analysing IEG expression during recent and remote memory probe trials. The hippocampus was equivalently or increasingly activated over the course of time reflecting its continued involvement, while widespread increases in cortical activity were observed at remote time-points, consistent with systems consolidation theories. In addition, we showed that IEG expression was associated with error correction during learning and with superior performance during retention

    Applied constant gain amplification in circulating loop experiments

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    The reconfiguration of channel or wavelength routes in optically transparent mesh networks can lead to deviations in channel power that may impact transmission performance. A new experimental approach, applied constant gain, is used to maintain constant gain in a circulating loop enabling the study of gain error effects on long-haul transmission under reconfigured channel loading. Using this technique we examine a number of channel configurations and system tuning operations for both full-span dispersion-compensated and optimized dispersion-managed systems. For each system design, large power divergence was observed with a maximum of 15 dB at 2240 km, when switching was implemented without additional system tuning. For a bit error rate of 10-3, the maximum number of loop circulations was reduced by up to 33%
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