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Highest Accuracy (highest + accuracy)
Selected AbstractsSupport vector machines-based modelling of seismic liquefaction potentialINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 10 2006Mahesh Pal Abstract This paper investigates the potential of support vector machines (SVM)-based classification approach to assess the liquefaction potential from actual standard penetration test (SPT) and cone penetration test (CPT) field data. SVMs are based on statistical learning theory and found to work well in comparison to neural networks in several other applications. Both CPT and SPT field data sets is used with SVMs for predicting the occurrence and non-occurrence of liquefaction based on different input parameter combination. With SPT and CPT test data sets, highest accuracy of 96 and 97%, respectively, was achieved with SVMs. This suggests that SVMs can effectively be used to model the complex relationship between different soil parameter and the liquefaction potential. Several other combinations of input variable were used to assess the influence of different input parameters on liquefaction potential. Proposed approach suggest that neither normalized cone resistance value with CPT data nor the calculation of standardized SPT value is required with SPT data. Further, SVMs required few user-defined parameters and provide better performance in comparison to neural network approach. Copyright © 2006 John Wiley & Sons, Ltd. [source] Tests of radial basis functions in the 3D DRM-MDINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 1 2006Bruno Natalini Abstract Several global as well as compactly supported radial basis functions were tested in the boundary element dual reciprocity method-multi domain approach (DRM-MD) applied to 3D potential problems. Compactly supported radial basis functions (CS-RBFs) showed the highest accuracy, while the augmented thin plate splines (ATPS) showed the highest consistency in terms of accuracy and convergence for the two examples considered, the Poisson and the advection,diffusion equations. A problem for implementation of the CS-RBFs is the lack of guidelines in choosing the size of the support, which showed to have large influence on the accuracy and convergence when these types of RBFs are used. The ATPS showed satisfactory accuracy and since its use does not involve any extra parameters, at the moment it is this function that is the choice of the authors for use in the DRM-MD. Copyright © 2005 John Wiley & Sons, Ltd. [source] Reliability and validity of the Norwegian version of the Severe Impairment Battery (SIB)INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 9 2008Sverre Bergh Abstract Objective The Severe Impairment Battery (SIB) is developed to test cognitive function in patients with dementia of moderate to severe degree. We have conducted a study to assess the inter-rater reliability and the validity of the Norwegian version of SIB. Methods The reliability study comprised 30 patients, and the validity study 59 patients in nursing homes. We assessed Cronbach's alpha coefficient of the scale and the inter-rater reliability for the total SIB score and its nine sub scores between two testers by means of the Spearman's correlation coefficients. In the validity study we compared the SIB scores with the scores on the Clinical Dementia Rating Scale. Results The mean SIB score was 72.10 (SD 25.37). The Cronbach's alpha was 0.97, and the inter-rater reliability of total SIB score was Spearman's rho 0.85, and ranged from 0.46 to 0.76 for the nine sub-scores. The mean SIB score for patients with a CDR score,<,2 was 84.2(13.4), whereas total scores for patients with CDR 2 and 3 were 74 (18.9) and 48.4 (33.3), respectively. A cut-off point of 80.5 points gave the highest accuracy in discriminating between patients with CDR 2 and CDR 3, while a cut-off point of 87.5 best discriminated between CDR,<,2 and CDR 3. Conclusion The study indicates that the Norwegian version of SIB is a reliable and valid test with which to evaluate the cognition in patients with dementia of moderate to severe degree. Copyright © 2008 John Wiley & Sons, Ltd. [source] Sensitivity and specificity of current diagnostic tests for gill-associated virus in Penaeus monodonJOURNAL OF FISH DISEASES, Issue 11 2006J Munro Abstract This study reports the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy between a reverse transcriptase-nested polymerase chain reaction (RT-nPCR) and an enzyme-linked immunosorbent assay (ELISA) for the detection of gill-associated virus (GAV) from a sample of 120 Penaeus monodon. Subsequently, the same comparisons were applied to the ELISA and haemagglutination (HA) assays for detection of GAV from a second 120 prawns. The optical density (OD) or dilution cut-off point had a direct influence on the tested parameters. The cut-off OD of 0.5,0.6 with the ELISA produced a sensitivity of 98% compared with RT-nPCR. However, these OD produced the lowest accuracy (85.8% and 86.7%, respectively). The OD cut off of 0.75 resulted in the highest accuracy (91.7%) and NPV (81.3%) while it had the second highest sensitivity (97%) and PPV (93.3%). However, the OD cut off of 0.9 had the highest specificity (80%). With regards to HA, the titre cut off at 8 resulted in the highest sensitivity, specificity and NPV (94%, 100% and 100%, respectively) compared with the ELISA, while the HA titre of 16 gave the highest accuracy (73%) and the second highest specificity (75%). A HA titre of 64 gave the highest PPV (81%). Using the RT-nPCR as the gold standard, the ELISA had an accuracy of 91.7% when using a cut off >0.75 as a positive result. When compared with the ELISA, the HA had an accuracy of 73% when using an HA titre cut off greater than 16 as a positive result. These results indicate that alternative tests for GAV (ELISA and HA) can be used to explore multiple questions about the disease status of P. monodon stocks in a cost-effective manner. [source] Detection of choline signal in human breast lesions with chemical-shift imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2008Hyeon-Man Baek PhD Abstract Purpose To investigate the application of MR spectroscopy using chemical-shift imaging (CSI) for characterizing human breast lesions at 1.5T, and to evaluate the diagnostic performance using ROC (receiver operating characteristics) analysis. Materials and Methods Thirty-six patients (35,73 years old, mean 52), with 27 malignant and 9 benign lesions, underwent anatomical imaging, dynamic contrast-enhanced MR imaging, and CSI. The ROC analysis was performed and the cutoff point yielding the highest accuracy was found to be a choline (Cho) signal-to-noise ratio (SNR) >3.2. Results The mean Cho SNR was 2.8 ± 0.8 (range, 1.8,4.3) for the benign group and 5.9 ± 3.4 (2.1,17.5) for the malignant group (P = 0.01). Based on the criterion of Cho SNR >3.2 as malignant, CSI correctly diagnosed 22 of 27 malignant lesions and 7 of 9 benign lesions, resulting in a sensitivity of 81%, specificity of 78%, and overall accuracy of 81%. If the criterion was set higher at Cho SNR >4.0 the specificity improved to 89% but sensitivity was lowered to 67%. Conclusion The ROC analysis presented in this work could be used to set an objective diagnostic criterion depending on preferred emphasis on sensitivity or specificity. J. Magn. Reson. Imaging 2008;27:1114,1121. © 2008 Wiley-Liss, Inc. [source] A comparison between the accuracy of voxel-based morphometry and hippocampal volumetry in Alzheimer's diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2004Cristina Testa PhD Abstract Purpose To compare the accuracy of voxel-based morphometry (VBM) and region of interest (ROI)-based hippocampal volumetry to detect medial temporal lobe atrophy in Alzheimer's disease (AD). Materials and Methods A total of 27 AD patients (age 74 ± 9 years; 22 women; Mini-Mental State Exam [MMSE] 21 ± 4) and 25 controls (age 70 ± 8; 16 women; MMSE 29 ± 1) were studied. Accuracy of VBM to detect gray matter loss in those seven AD patients and 11 controls with similar ROI-based hippocampal measures and of ROI-based volumetry to detect gray matter loss in those four AD patients and five controls with similar VBM-based hippocampal measures was assessed. VBM was performed with statistical parametric mapping (SPM99). Results The area under the curve was 0.96 (95% C.I., 0.92,1.00) for VBM, 0.89 (95% C.I., 0.80,0.98) for ROI-based hippocampal measures, and 0.99 (95% C.I., 0.96,1.00) for both. In subjects with similar ROI-based hippocampal measures, VBM detected atrophy in AD patients at P < 0.0001, while in subjects with similar VBM-based hippocampal measure, volumetry was not significant (P = 0.11). Both measures independently contributed to discrimination (P = 0.004 and P = 0.032) in a logistic regression model. Conclusion These results indicate that VBM is more accurate, but the combination of both methods provides the highest accuracy for detection of hippocampal atrophy in AD. J. Magn. Reson. Imaging 2004;19:274,282. © 2004 Wiley-Liss, Inc. [source] Quantitative analysis of MRI signal abnormalities of brain white matter with high reproducibility and accuracyJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2002Xingchang Wei MD Abstract Purpose To assess the reproducibility and accuracy compared to radiologists of three automated segmentation pipelines for quantitative magnetic resonance imaging (MRI) measurement of brain white matter signal abnormalities (WMSA). Materials and Methods WMSA segmentation was performed on pairs of whole brain scans from 20 patients with multiple sclerosis (MS) and 10 older subjects who were positioned and imaged twice within 30 minutes. Radiologist outlines of WMSA on 20 sections from 16 patients were compared with the corresponding results of each segmentation method. Results The segmentation method combining expectation-maximization (EM) tissue segmentation, template-driven segmentation (TDS), and partial volume effect correction (PVEC) demonstrated the highest accuracy (the absolute value of the Z-score was 0.99 for both groups of subjects), as well as high interscan reproducibility (repeatability coefficient was 0.68 mL in MS patients and 1.49 mL in aging subjects). Conclusion The addition of TDS to the EM segmentation and PVEC algorithms significantly improved the accuracy of WMSA volume measurements, while also improving measurement reproducibility. J. Magn. Reson. Imaging 2002;15:203,209. © 2002 Wiley-Liss, Inc. [source] Citation rates and perceptions of scientific contributionJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 2 2006Dag W. Aksnes In this study scientists were asked about their own publication history and their citation counts. The study shows that the citation counts of the publications correspond reasonably well with the authors' own assessments of scientific contribution. Generally, citations proved to have the highest accuracy in identifying either major or minor contributions. Nevertheless, according to these judgments, citations are not a reliable indicator of scientific contribution at the level of the individual article. In the construction of relative citation indicators, the average citation rate of the subfield appears to be slightly more appropriate as a reference standard than the journal citation rate. The study confirms that review articles are cited more frequently than other publication types. Compared to the significance authors attach to these articles they appear to be considerably "overcited." However, there were only marginal differences in the citation rates between empirical, methods, and theoretical contributions. [source] Asymptotic rate of quantum ergodicity in chaotic Euclidean billiardsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 10 2006Alexander Barnett The quantum unique ergodicity (QUE) conjecture of Rudnick and Sarnak is that every eigenfunction ,n of the Laplacian on a manifold with uniformly hyperbolic geodesic flow becomes equidistributed in the semiclassical limit (eigenvalue En , ,); that is, "strong scars" are absent. We study numerically the rate of equidistribution for a uniformly hyperbolic, Sinai-type, planar Euclidean billiard with Dirichlet boundary condition (the "drum problem") at unprecedented high E and statistical accuracy, via the matrix elements ,,n, Â,m, of a piecewise-constant test function A. By collecting 30,000 diagonal elements (up to level n , 7 × 105) we find that their variance decays with eigenvalue as a power 0.48 ± 0.01, close to the semiclassical estimate ½ of Feingold and Peres. This contrasts with the results of existing studies, which have been limited to En a factor 102 smaller. We find strong evidence for QUE in this system. We also compare off-diagonal variance as a function of distance from the diagonal, against Feingold-Peres (or spectral measure) at the highest accuracy (0.7%) thus far in any chaotic system. We outline the efficient scaling method and boundary integral formulae used to calculate eigenfunctions. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||