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Model Set (model + set)
Selected AbstractsThe US Dollar and the Trade Deficit: What Accounts for the Late 1990s?,INTERNATIONAL FINANCE, Issue 3 2005Benjamin Hunt Based on a version of the IMF's global economy model set up to analyse macroeconomic interdependence between the United States and the rest of the world, this paper asks to what extent accelerating productivity growth in the United States may have contributed to the US real exchange rate appreciation and the trade balance deterioration witnessed in the second half of the 1990s. The paper concludes that productivity is only part of this story. A portfolio preference shift in favour of US assets, possibly triggered by faster productivity growth, and some uncertainty and learning about the persistence of both shocks are needed to match the data more satisfactorily. [source] Model consisting of ultrasonographic and simple blood indexes accurately identify compensated hepatitis B cirrhosisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8pt1 2008Yong-Peng Chen Abstract Background and Aim:, Several models for significant fibrosis or cirrhosis have been introduced for hepatitis C, but are seldom for hepatitis B. The present study retrospectively evaluates the relationship between ultrasonography, blood tests, and fibrosis stage, and constructs a model for predicting compensated cirrhosis. Methods:, A total of 653 patients with chronic hepatitis B who underwent liver biopsies, ultrasonographic scanning, and routine blood tests were retrospectively analyzed. The patients were divided into the model set and validation set. Blood tests and ultrasonographic indexes were analyzed statistically. An ultrasonographic scoring system consisting of liver parenchyma, gallbladder, hepatic vessel, and splenomegaly was introduced. Results:, There were significant differences between cirrhosis and other fibrosis stages in ultrasonographic indexes of liver parenchyma, gallbladder, hepatic vessel, and splenomegaly. Ultrasonographic scores were significantly different between F4 and other fibrosis, and significantly correlated with fibrosis stage. Apart from alanine aminotransferase and alkaline phosphatase, blood tests and patients' age were correlated with fibrosis, and were significantly different between patients with and without cirrhosis. The model for cirrhosis indexes consisting of ultrasonographic score, patient's age, and variables, including platelet, albumin, and bilirubin predicted cirrhosis with area under receiver,operator curve of 0.907 in the model set and 0.849 in the validation set. Using proper cut-off values, nearly 81% patients could be accurately assessed for the absence or presence of cirrhosis. Conclusion:, The model consisting of ultrasonographic score, patients' age, blood variables of platelet, albumin, and bilirubin can identify hepatitis B cirrhosis with a high degree of accuracy. The application of this model would greatly reduce the number of biopsies. [source] Cost-Effectiveness of Screening for Unhealthy Alcohol Use with %Carbohydrate Deficient Transferrin: Results From a Literature-Based Decision Analytic Computer ModelALCOHOLISM, Issue 8 2009Alok Kapoor Background:, The %carbohydrate deficient transferrin (%CDT) test offers objective evidence of unhealthy alcohol use but its cost-effectiveness in primary care conditions is unknown. Methods:, Using a decision tree and Markov model, we performed a literature-based cost-effectiveness analysis of 4 strategies for detecting unhealthy alcohol use in adult primary care patients: (i) Questionnaire Only, using a validated 3-item alcohol questionnaire; (ii) %CDT Only; (iii) Questionnaire followed by %CDT (Questionnaire-%CDT) if the questionnaire is negative; and (iv) No Screening. For those patients screening positive, clinicians performed more detailed assessment to characterize unhealthy use and determine therapy. We estimated costs using Medicare reimbursement and the Medical Expenditure Panel Survey. We determined sensitivity, specificity, prevalence of disease, and mortality from the medical literature. In the base case, we calculated the incremental cost-effectiveness ratio (ICER) in 2006 dollars per quality-adjusted life year ($/QALY) for a 50-year-old cohort. Results:, In the base case, the ICER for the Questionnaire-%CDT strategy was $15,500/QALY compared with the Questionnaire Only strategy. Other strategies were dominated. When the prevalence of unhealthy alcohol use exceeded 15% and screening age was <60 years, the Questionnaire-%CDT strategy costs less than $50,000/QALY compared to the Questionnaire Only strategy. Conclusions:, Adding %CDT to questionnaire-based screening for unhealthy alcohol use was cost-effective in our literature-based decision analytic model set in typical primary care conditions. Screening with %CDT should be considered for adults up to the age of 60 when the prevalence of unhealthy alcohol use is 15% or more and screening questionnaires are negative. [source] Water Resources Modeling of the Ganges-Brahmaputra-Meghna River Basins Using Satellite Remote Sensing Data,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2009Bushra Nishat Nishat, Bushra and S.M. Mahbubur Rahman, 2009. Water Resources Modeling of the Ganges-Brahmaputra-Meghna River Basins Using Satellite Remote Sensing Data. Journal of the American Water Resources Association (JAWRA) 45(6):1313-1327. Abstract:, Large-scale water resources modeling can provide useful insights on future water availability scenarios for downstream nations in anticipation of proposed upstream water resources projects in large international river basins (IRBs). However, model set up can be challenging due to the large amounts of data requirement on both static states (soils, vegetation, topography, drainage network, etc.) and dynamic variables (rainfall, streamflow, soil moisture, evapotranspiration, etc.) over the basin from multiple nations and data collection agencies. Under such circumstances, satellite remote sensing provides a more pragmatic and convenient alternative because of the vantage of space and easy availability from a single data platform. In this paper, we demonstrate a modeling effort to set up a water resources management model, MIKE BASIN, over the Ganges, Brahmaputra, and Meghna (GBM) river basins. The model is set up with the objective of providing Bangladesh, the lowermost riparian nation in the GBM basins, a framework for assessing proposed water diversion scenarios in the upstream transboundary regions of India and deriving quantitative impacts on water availability. Using an array of satellite remote sensing data on topography, vegetation, and rainfall from the transboundary regions, we demonstrate that it is possible to calibrate MIKE BASIN to a satisfactory level and predict streamflow in the Ganges and Brahmaputra rivers at the entry points of Bangladesh at relevant scales of water resources management. Simulated runoff for the Ganges and Brahmaputra rivers follow the trends in the rated discharge for the calibration period. However, monthly flow volume differs from the actual rated flow by (,) 8% to (+) 20% in the Ganges basin, by (,) 15 to (+) 12% in the Brahmaputra basin, and by (,) 15 to (+) 19% in the Meghna basin. Our large-scale modeling initiative is generic enough for other downstream nations in IRBs to adopt for their own modeling needs. [source] A Learning-Theoretic Approach To Model-Set IdentificationASIAN JOURNAL OF CONTROL, Issue 1 2001Yasuaki Oishi ABSTRACT A new approach to model-set identification is proposed based on an agnostic learning theory. The squared prediction error is estimated together with its uncertainty uniformly in some parameter region. Based on this estimation, a model set is constructed so as to include the best model. The proposed approach does not require assumptions on the true dynamics or the noise, neither does it need infinite number of input-output data in order to justify its result. But it guarantees that the size of the identified model set converges to zero as the number of input-output data increases. Improvement of the precision is considered on the proposed identification method. Generalization of the approach is discussed and a numerical example is presented. [source] Discrete tomography of icosahedral model setsACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2009Christian Huck The discrete tomography of mathematical quasicrystals with icosahedral symmetry is investigated, placing emphasis on reconstruction and uniqueness problems. The work is motivated by the requirement in materials science for the unique reconstruction of the structures of icosahedral quasicrystals from a small number of images produced by quantitative high-resolution transmission electron microscopy. [source] Discrete tomography of planar model setsACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2006Michael Baake Discrete tomography is a well-established method to investigate finite point sets, in particular finite subsets of periodic systems. Here, we start to develop an efficient approach for the treatment of finite subsets of mathematical quasicrystals. To this end, the class of cyclotomic model sets is introduced, and the corresponding consistency, reconstruction and uniqueness problems of the discrete tomography of these sets are discussed. [source] | |||||||||||||