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Sample records for roc receiver operating

  1. Receiver Operating Characteristics (ROCs) in Recognition Memory: A Review

    Science.gov (United States)

    Yonelinas, Andrew P.; Parks, Colleen M.

    2007-01-01

    Receiver operating characteristic (ROC) analysis is being used increasingly to examine the memory processes underlying recognition memory. The authors discuss the methodological issues involved in conducting and analyzing ROC results, describe the various models that have been developed to account for these results, review the behavioral empirical…

  2. Receiver operator characteristic (ROC) analysis without truth

    International Nuclear Information System (INIS)

    Henkelman, R.M.; Kay, I.; Bronskill, M.J.

    1990-01-01

    Receiver operator characteristic (ROC) analysis, the preferred method of evaluating diagnostic imaging tests, requires an independent assessment of the true state of disease, which can be difficult to obtain and is often of questionable accuracy. A new method of analysis is described which does not require independent truth data and which can be used when several accurate tests are being compared. This method uses correlative information to estimate the underlying model of multivariate normal distributions of disease-positive and disease-negative patients. The method is shown to give results equivalent to conventional ROC analysis in a comparison of computed tomography, radionuclide scintigraphy, and magnetic resonance imaging for liver metastasis. When independent truth is available, the method can be extended to incorporate truth data or to evaluate the consistency of the truth data with the imaging data

  3. Receiver operating characteristic (ROC) curves: review of methods with applications in diagnostic medicine

    Science.gov (United States)

    Obuchowski, Nancy A.; Bullen, Jennifer A.

    2018-04-01

    Receiver operating characteristic (ROC) analysis is a tool used to describe the discrimination accuracy of a diagnostic test or prediction model. While sensitivity and specificity are the basic metrics of accuracy, they have many limitations when characterizing test accuracy, particularly when comparing the accuracies of competing tests. In this article we review the basic study design features of ROC studies, illustrate sample size calculations, present statistical methods for measuring and comparing accuracy, and highlight commonly used ROC software. We include descriptions of multi-reader ROC study design and analysis, address frequently seen problems of verification and location bias, discuss clustered data, and provide strategies for testing endpoints in ROC studies. The methods are illustrated with a study of transmission ultrasound for diagnosing breast lesions.

  4. ROC-ing along: Evaluation and interpretation of receiver operating characteristic curves.

    Science.gov (United States)

    Carter, Jane V; Pan, Jianmin; Rai, Shesh N; Galandiuk, Susan

    2016-06-01

    It is vital for clinicians to understand and interpret correctly medical statistics as used in clinical studies. In this review, we address current issues and focus on delivering a simple, yet comprehensive, explanation of common research methodology involving receiver operating characteristic (ROC) curves. ROC curves are used most commonly in medicine as a means of evaluating diagnostic tests. Sample data from a plasma test for the diagnosis of colorectal cancer were used to generate a prediction model. These are actual, unpublished data that have been used to describe the calculation of sensitivity, specificity, positive predictive and negative predictive values, and accuracy. The ROC curves were generated to determine the accuracy of this plasma test. These curves are generated by plotting the sensitivity (true-positive rate) on the y axis and 1 - specificity (false-positive rate) on the x axis. Curves that approach closest to the coordinate (x = 0, y = 1) are more highly predictive, whereas ROC curves that lie close to the line of equality indicate that the result is no better than that obtained by chance. The optimum sensitivity and specificity can be determined from the graph as the point where the minimum distance line crosses the ROC curve. This point corresponds to the Youden index (J), a function of sensitivity and specificity used commonly to rate diagnostic tests. The area under the curve is used to quantify the overall ability of a test to discriminate between 2 outcomes. By following these simple guidelines, interpretation of ROC curves will be less difficult and they can then be interpreted more reliably when writing, reviewing, or analyzing scientific papers. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. The ROC Toolbox: A toolbox for analyzing receiver-operating characteristics derived from confidence ratings.

    Science.gov (United States)

    Koen, Joshua D; Barrett, Frederick S; Harlow, Iain M; Yonelinas, Andrew P

    2017-08-01

    Signal-detection theory, and the analysis of receiver-operating characteristics (ROCs), has played a critical role in the development of theories of episodic memory and perception. The purpose of the current paper is to present the ROC Toolbox. This toolbox is a set of functions written in the Matlab programming language that can be used to fit various common signal detection models to ROC data obtained from confidence rating experiments. The goals for developing the ROC Toolbox were to create a tool (1) that is easy to use and easy for researchers to implement with their own data, (2) that can flexibly define models based on varying study parameters, such as the number of response options (e.g., confidence ratings) and experimental conditions, and (3) that provides optimal routines (e.g., Maximum Likelihood estimation) to obtain parameter estimates and numerous goodness-of-fit measures.The ROC toolbox allows for various different confidence scales and currently includes the models commonly used in recognition memory and perception: (1) the unequal variance signal detection (UVSD) model, (2) the dual process signal detection (DPSD) model, and (3) the mixture signal detection (MSD) model. For each model fit to a given data set the ROC toolbox plots summary information about the best fitting model parameters and various goodness-of-fit measures. Here, we present an overview of the ROC Toolbox, illustrate how it can be used to input and analyse real data, and finish with a brief discussion on features that can be added to the toolbox.

  6. Design of a receiver operating characteristic (ROC) study of 10:1 lossy image compression

    Science.gov (United States)

    Collins, Cary A.; Lane, David; Frank, Mark S.; Hardy, Michael E.; Haynor, David R.; Smith, Donald V.; Parker, James E.; Bender, Gregory N.; Kim, Yongmin

    1994-04-01

    The digital archiving system at Madigan Army Medical Center (MAMC) uses a 10:1 lossy data compression algorithm for most forms of computed radiography. A systematic study on the potential effect of lossy image compression on patient care has been initiated with a series of studies focused on specific diagnostic tasks. The studies are based upon the receiver operating characteristic (ROC) method of analysis for diagnostic systems. The null hypothesis is that observer performance with approximately 10:1 compressed and decompressed images is not different from using original, uncompressed images for detecting subtle pathologic findings seen on computed radiographs of bone, chest, or abdomen, when viewed on a high-resolution monitor. Our design involves collecting cases from eight pathologic categories. Truth is determined by committee using confirmatory studies performed during routine clinical practice whenever possible. Software has been developed to aid in case collection and to allow reading of the cases for the study using stand-alone Siemens Litebox workstations. Data analysis uses two methods, ROC analysis and free-response ROC (FROC) methods. This study will be one of the largest ROC/FROC studies of its kind and could benefit clinical radiology practice using PACS technology. The study design and results from a pilot FROC study are presented.

  7. Correlation of free-response and receiver-operating-characteristic area-under-the-curve estimates: Results from independently conducted FROC/ROC studies in mammography

    International Nuclear Information System (INIS)

    Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde

    2012-01-01

    Purpose: From independently conducted free-response receiver operating characteristic (FROC) and receiver operating characteristic (ROC) experiments, to study fixed-reader associations between three estimators: the area under the alternative FROC (AFROC) curve computed from FROC data, the area under the ROC curve computed from FROC highest rating data, and the area under the ROC curve computed from confidence-of-disease ratings. Methods: Two hundred mammograms, 100 of which were abnormal, were processed by two image-processing algorithms and interpreted by four radiologists under the FROC paradigm. From the FROC data, inferred-ROC data were derived, using the highest rating assumption. Eighteen months afterwards, the images were interpreted by the same radiologists under the conventional ROC paradigm; conventional-ROC data (in contrast to inferred-ROC data) were obtained. FROC and ROC (inferred, conventional) data were analyzed using the nonparametric area-under-the-curve (AUC), (AFROC and ROC curve, respectively). Pearson correlation was used to quantify the degree of association between the modality-specific AUC indices and standard errors were computed using the bootstrap-after-bootstrap method. The magnitude of the correlations was assessed by comparison with computed Obuchowski-Rockette fixed reader correlations. Results: Average Pearson correlations (with 95% confidence intervals in square brackets) were: Corr(FROC, inferred ROC) = 0.76[0.64, 0.84] > Corr(inferred ROC, conventional ROC) = 0.40[0.18, 0.58] > Corr (FROC, conventional ROC) = 0.32[0.16, 0.46]. Conclusions: Correlation between FROC and inferred-ROC data AUC estimates was high. Correlation between inferred- and conventional-ROC AUC was similar to the correlation between two modalities for a single reader using one estimation method, suggesting that the highest rating assumption might be questionable.

  8. Verification of a model for the detection of intrauterine growth restriction (IUGR) by receiver operating characteristics (ROC)

    Science.gov (United States)

    Liu, Pengbo; Mongelli, Max; Mondry, Adrian

    2004-07-01

    The purpose of this study is to verify by Receiver Operating Characteristics (ROC) a mathematical model supporting the hypothesis that IUGR can be diagnosed by estimating growth velocity. The ROC compare computerized simulation results with clinical data from 325 pregnant British women. Each patient had 6 consecutive ultrasound examinations for fetal abdominal circumference (fac). Customized and un-customized fetal weights were calculated according to Hadlock"s formula. IUGR was diagnosed by the clinical standard, i.e. estimated weight below the tenth percentile. Growth velocity was estimated by calculating the changes of fac (Dzfac/dt) at various time intervals from 3 to 10 weeks. Finally, ROC was used to compare the methods. At 3~4 weeks scan interval, the area under the ROC curve is 0.68 for customized data and 0.66 for the uncustomized data with 95% confidence interval. Comparison between simulation data and real pregnancies verified that the model is clinically acceptable.

  9. A Primer on Receiver Operating Characteristic Analysis and Diagnostic Efficiency Statistics for Pediatric Psychology: We Are Ready to ROC

    Science.gov (United States)

    2014-01-01

    Objective To offer a practical demonstration of receiver operating characteristic (ROC) analyses, diagnostic efficiency statistics, and their application to clinical decision making using a popular parent checklist to assess for potential mood disorder. Method Secondary analyses of data from 589 families seeking outpatient mental health services, completing the Child Behavior Checklist and semi-structured diagnostic interviews. Results Internalizing Problems raw scores discriminated mood disorders significantly better than did age- and gender-normed T scores, or an Affective Problems score. Internalizing scores 30 had a diagnostic likelihood ratio of 7.4. Conclusions This study illustrates a series of steps in defining a clinical problem, operationalizing it, selecting a valid study design, and using ROC analyses to generate statistics that support clinical decisions. The ROC framework offers important advantages for clinical interpretation. Appendices include sample scripts using SPSS and R to check assumptions and conduct ROC analyses. PMID:23965298

  10. A comparison of ROC inferred from FROC and conventional ROC

    Science.gov (United States)

    McEntee, Mark F.; Littlefair, Stephen; Pietrzyk, Mariusz W.

    2014-03-01

    This study aims to determine whether receiver operating characteristic (ROC) scores inferred from free-response receiver operating characteristic (FROC) were equivalent to conventional ROC scores for the same readers and cases. Forty-five examining radiologists of the American Board of Radiology independently reviewed 47 PA chest radiographs under at least two conditions. Thirty-seven cases had abnormal findings and 10 cases had normal findings. Half the readers were asked to first locate any visualized lung nodules, mark them and assign a level of confidence [the FROC mark-rating pair] and second give an overall to the entire image on the same scale [the ROC score]. The second half of readers gave the ROC rating first followed by the FROC mark-rating pairs. A normal image was represented with number 1 and malignant lesions with numbers 2-5. A jackknife free-response receiver operating characteristic (JAFROC), and inferred ROC (infROC) was calculated from the mark-rating pairs using JAFROC V4.1 software. ROC based on the overall rating of the image calculated using DBM MRMC software, which was also used to compare infROC and ROC AUCs treating the methods as modalities. Pearson's correlations coefficient and linear regression were used to examine their relationship using SPSS, version 21.0; (SPSS, Chicago, IL). The results of this study showed no significant difference between the ROC and Inferred ROC AUCs (p≤0.25). While Pearson's correlation coefficient was 0.7 (p≤0.01). Inter-reader correlation calculated from Obuchowski- Rockette covariance's ranged from 0.43-0.86 while intra-reader agreement was greater than previously reported ranging from 0.68-0.82.

  11. Receiver Operating Characteristic (ROC to Determine Cut-Off Points of Biomarkers in Lung Cancer Patients

    Directory of Open Access Journals (Sweden)

    Heidi L. Weiss

    2004-01-01

    Full Text Available The role of biomarkers in disease prognosis continues to be an important investigation in many cancer studies. In order for these biomarkers to have practical application in clinical decision making regarding patient treatment and follow-up, it is common to dichotomize patients into those with low vs. high expression levels. In this study, receiver operating characteristic (ROC curves, area under the curve (AUC of the ROC, sensitivity, specificity, as well as likelihood ratios were calculated to determine levels of growth factor biomarkers that best differentiate lung cancer cases versus control subjects. Selected cut-off points for p185erbB-2 and EGFR membrane appear to have good discriminating power to differentiate control tissues versus uninvolved tissues from patients with lung cancer (AUC = 89% and 90%, respectively; while AUC increased to at least 90% for selected cut-off points for p185erbB-2 membrane, EGFR membrane, and FASE when comparing between control versus carcinoma tissues from lung cancer cases. Using data from control subjects compared to patients with lung cancer, we presented a simple and intuitive approach to determine dichotomized levels of biomarkers and validated the value of these biomarkers as surrogate endpoints for cancer outcome.

  12. Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part I: The use of ROC curves in diagnostic medicine and electrocardiographic markers of ischaemia.

    Science.gov (United States)

    Barnabei, Luca; Marazìa, Stefania; De Caterina, Raffaele

    2007-11-01

    A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic (ECG) stress testing. Part I will focus on theoretical description and analysis along with reviewing the common problems related to the diagnosis of myocardial ischaemia by means of exercise ECG stress testing. Part II will be devoted to applying ROC curves to available diagnostic criteria through the analysis of ECG stress test parameters.

  13. Measuring diagnostic and predictive accuracy in disease management: an introduction to receiver operating characteristic (ROC) analysis.

    Science.gov (United States)

    Linden, Ariel

    2006-04-01

    Diagnostic or predictive accuracy concerns are common in all phases of a disease management (DM) programme, and ultimately play an influential role in the assessment of programme effectiveness. Areas, such as the identification of diseased patients, predictive modelling of future health status and costs and risk stratification, are just a few of the domains in which assessment of accuracy is beneficial, if not critical. The most commonly used analytical model for this purpose is the standard 2 x 2 table method in which sensitivity and specificity are calculated. However, there are several limitations to this approach, including the reliance on a single defined criterion or cut-off for determining a true-positive result, use of non-standardized measurement instruments and sensitivity to outcome prevalence. This paper introduces the receiver operator characteristic (ROC) analysis as a more appropriate and useful technique for assessing diagnostic and predictive accuracy in DM. Its advantages include; testing accuracy across the entire range of scores and thereby not requiring a predetermined cut-off point, easily examined visual and statistical comparisons across tests or scores, and independence from outcome prevalence. Therefore the implementation of ROC as an evaluation tool should be strongly considered in the various phases of a DM programme.

  14. Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part II: the use of ROC curves in the choice of electrocardiographic stress test markers of ischaemia.

    Science.gov (United States)

    Marazìa, Stefania; Barnabei, Luca; De Caterina, Raffaele

    2008-01-01

    A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic stress testing. Part II will be devoted to the comparative analysis of various parameters derived from exercise stress testing for the diagnosis of underlying coronary artery disease.

  15. A Three-Dimensional Receiver Operator Characteristic Surface Diagnostic Metric

    Science.gov (United States)

    Simon, Donald L.

    2011-01-01

    Receiver Operator Characteristic (ROC) curves are commonly applied as metrics for quantifying the performance of binary fault detection systems. An ROC curve provides a visual representation of a detection system s True Positive Rate versus False Positive Rate sensitivity as the detection threshold is varied. The area under the curve provides a measure of fault detection performance independent of the applied detection threshold. While the standard ROC curve is well suited for quantifying binary fault detection performance, it is not suitable for quantifying the classification performance of multi-fault classification problems. Furthermore, it does not provide a measure of diagnostic latency. To address these shortcomings, a novel three-dimensional receiver operator characteristic (3D ROC) surface metric has been developed. This is done by generating and applying two separate curves: the standard ROC curve reflecting fault detection performance, and a second curve reflecting fault classification performance. A third dimension, diagnostic latency, is added giving rise to 3D ROC surfaces. Applying numerical integration techniques, the volumes under and between the surfaces are calculated to produce metrics of the diagnostic system s detection and classification performance. This paper will describe the 3D ROC surface metric in detail, and present an example of its application for quantifying the performance of aircraft engine gas path diagnostic methods. Metric limitations and potential enhancements are also discussed

  16. pROC: an open-source package for R and S+ to analyze and compare ROC curves.

    Science.gov (United States)

    Robin, Xavier; Turck, Natacha; Hainard, Alexandre; Tiberti, Natalia; Lisacek, Frédérique; Sanchez, Jean-Charles; Müller, Markus

    2011-03-17

    Receiver operating characteristic (ROC) curves are useful tools to evaluate classifiers in biomedical and bioinformatics applications. However, conclusions are often reached through inconsistent use or insufficient statistical analysis. To support researchers in their ROC curves analysis we developed pROC, a package for R and S+ that contains a set of tools displaying, analyzing, smoothing and comparing ROC curves in a user-friendly, object-oriented and flexible interface. With data previously imported into the R or S+ environment, the pROC package builds ROC curves and includes functions for computing confidence intervals, statistical tests for comparing total or partial area under the curve or the operating points of different classifiers, and methods for smoothing ROC curves. Intermediary and final results are visualised in user-friendly interfaces. A case study based on published clinical and biomarker data shows how to perform a typical ROC analysis with pROC. pROC is a package for R and S+ specifically dedicated to ROC analysis. It proposes multiple statistical tests to compare ROC curves, and in particular partial areas under the curve, allowing proper ROC interpretation. pROC is available in two versions: in the R programming language or with a graphical user interface in the S+ statistical software. It is accessible at http://expasy.org/tools/pROC/ under the GNU General Public License. It is also distributed through the CRAN and CSAN public repositories, facilitating its installation.

  17. Applications of ROC analysis in diagnostic image evaluation

    International Nuclear Information System (INIS)

    Metz, C.E.

    1979-01-01

    The need for Receiver Operating Characteristic (ROC) analysis is indicated by a discussion of the limitations of accuracy and of sensitivity and specificity as indices of diagnostic detection or discrmination performance. The concept of a variable decision threshold is shown to lead in a natural way to the ROC curve as a means for specifying diagnostic performance. Practical techniques for measuring ROC curves are described, and directions for possible generalizations of conventional ROC analysis are indicated

  18. Receiver Operator Characteristic Tools Graphic User Interface Extension for R Commander

    Directory of Open Access Journals (Sweden)

    Daniel Corneliu LEUCUŢA

    2015-12-01

    Full Text Available Background: Receiver Operator Characteristic (ROC curve, is a graphical plot which presents the performance of a binary classifier when the discrimination cutoff is varied. The aim of this work was to create an extension for R Commander that offers a graphical user interface for Receiver Operator Characteristic tools provided by several existing command line accessible packages like pROC and ROCR. Material and Methods: The extension was built and tested with R version 3.2.0 and R Commander 2.1-7. Results: We built an extension called RcmdrPlugin.ROC that we uploaded on the CRAN servers. The extension adds a new menu called ROC, along with two submenus pROC and ROCR that broadly corresponds to commands available to access the functions of these packages. The pROC menu offers several commands: to plot a ROC curve for a dataset or for a logistic regression model, to compare paired and unpaired ROC curves, each providing the following tabs: General (to select the variables for the analysis, and options for switching cases with controls; Smoothing (allowing the user to select different types of smoothing – binominal, density, distributions like normal, lognormal, ...; AUC (to specify the partial area under the curve (AUC options, CI (to select the options of confidence intervals (CI – the level, computing method: DeLong, bootstrap, ...; Plot (for the plotting options. The ROCR dialogue window offers more options in choosing the performance measures for the plot. Conclusion: The RcmdrPlugin.ROC extension helps less advanced users of R accessing ROC tools in a friendly graphical user interface.

  19. ROC [Receiver Operating Characteristics] study of maximum likelihood estimator human brain image reconstructions in PET [Positron Emission Tomography] clinical practice

    International Nuclear Information System (INIS)

    Llacer, J.; Veklerov, E.; Nolan, D.; Grafton, S.T.; Mazziotta, J.C.; Hawkins, R.A.; Hoh, C.K.; Hoffman, E.J.

    1990-10-01

    This paper will report on the progress to date in carrying out Receiver Operating Characteristics (ROC) studies comparing Maximum Likelihood Estimator (MLE) and Filtered Backprojection (FBP) reconstructions of normal and abnormal human brain PET data in a clinical setting. A previous statistical study of reconstructions of the Hoffman brain phantom with real data indicated that the pixel-to-pixel standard deviation in feasible MLE images is approximately proportional to the square root of the number of counts in a region, as opposed to a standard deviation which is high and largely independent of the number of counts in FBP. A preliminary ROC study carried out with 10 non-medical observers performing a relatively simple detectability task indicates that, for the majority of observers, lower standard deviation translates itself into a statistically significant detectability advantage in MLE reconstructions. The initial results of ongoing tests with four experienced neurologists/nuclear medicine physicians are presented. Normal cases of 18 F -- fluorodeoxyglucose (FDG) cerebral metabolism studies and abnormal cases in which a variety of lesions have been introduced into normal data sets have been evaluated. We report on the results of reading the reconstructions of 90 data sets, each corresponding to a single brain slice. It has become apparent that the design of the study based on reading single brain slices is too insensitive and we propose a variation based on reading three consecutive slices at a time, rating only the center slice. 9 refs., 2 figs., 1 tab

  20. Statistical evaluation of diagnostic performance topics in ROC analysis

    CERN Document Server

    Zou, Kelly H; Bandos, Andriy I; Ohno-Machado, Lucila; Rockette, Howard E

    2016-01-01

    Statistical evaluation of diagnostic performance in general and Receiver Operating Characteristic (ROC) analysis in particular are important for assessing the performance of medical tests and statistical classifiers, as well as for evaluating predictive models or algorithms. This book presents innovative approaches in ROC analysis, which are relevant to a wide variety of applications, including medical imaging, cancer research, epidemiology, and bioinformatics. Statistical Evaluation of Diagnostic Performance: Topics in ROC Analysis covers areas including monotone-transformation techniques in parametric ROC analysis, ROC methods for combined and pooled biomarkers, Bayesian hierarchical transformation models, sequential designs and inferences in the ROC setting, predictive modeling, multireader ROC analysis, and free-response ROC (FROC) methodology. The book is suitable for graduate-level students and researchers in statistics, biostatistics, epidemiology, public health, biomedical engineering, radiology, medi...

  1. The role of stenosis ratio as a predictor of surgical satisfaction in patients with lumbar spinal canal stenosis: a receiver-operator characteristic (ROC) curve analysis.

    Science.gov (United States)

    Mohammadi, Hassanreza R; Azimi, Parisa; Benzel, Edward C; Shahzadi, Sohrab; Azhari, Shirzad

    2016-09-01

    The aim of this study was to elucidate independent factors that predict surgical satisfaction in lumbar spinal canal stenosis (LSCS) patients. Patients who underwent surgery were grouped based on the age, gender, duration of symptoms, walking distance, Neurogenic Claudication Outcome Score (NCOS) and the stenosis ratio (SR) described by Lurencin. We recorded on 2-year patient satisfaction using standardized measure. The optimal cut-off points in SR, NCOS and walking distance for predicting surgical satisfaction were estimated from sensitivity and specificity calculations and receiver operator characteristic (ROC) curves. One hundred fifty consecutive patients (51 male, 99 female, mean age 62.4±10.9 years) were followed up for 34±13 months (range 24-49). One, two, three and four level stenosis was observed in 10.7%, 39.3%, 36.0 % and 14.0% of patients, respectively. Post-surgical satisfaction was 78.5% at the 2 years follow up. In ROC curve analysis, the asymptotic significance is less than 0.05 in SR and the optimal cut-off value of SR to predict worsening surgical satisfaction was measured as more than 0.52, with 85.4% sensitivity and 77.4% specificity (AUC 0.798, 95% CI 0.73-0.90; Ppatients with degenerative lumbar stenosis considered for surgical treatment. Using a ROC curve analysis, a radiological feature, the SR, demonstrated superiority in predicting patient satisfaction, compared to functional and clinical characteristics such as walking distance and NCOS.

  2. Wavelet and receiver operating characteristic analysis of heart rate variability

    Science.gov (United States)

    McCaffery, G.; Griffith, T. M.; Naka, K.; Frennaux, M. P.; Matthai, C. C.

    2002-02-01

    Multiresolution wavelet analysis has been used to study the heart rate variability in two classes of patients with different pathological conditions. The scale dependent measure of Thurner et al. was found to be statistically significant in discriminating patients suffering from hypercardiomyopathy from a control set of normal subjects. We have performed Receiver Operating Characteristc (ROC) analysis and found the ROC area to be a useful measure by which to label the significance of the discrimination, as well as to describe the severity of heart dysfunction.

  3. Robust Biometric Score Fusion by Naive Likelihood Ratio via Receiver Operating Characteristics

    NARCIS (Netherlands)

    Tao, Q.; Veldhuis, Raymond N.J.

    This paper presents a novel method of fusing multiple biometrics on the matching score level. We estimate the likelihood ratios of the fused biometric scores, via individual receiver operating characteristics (ROC) which construct the Naive Bayes classifier. Using a limited number of operation

  4. Comparison of Paired ROC Curves through a Two-Stage Test.

    Science.gov (United States)

    Yu, Wenbao; Park, Eunsik; Chang, Yuan-Chin Ivan

    2015-01-01

    The area under the receiver operating characteristic (ROC) curve (AUC) is a popularly used index when comparing two ROC curves. Statistical tests based on it for analyzing the difference have been well developed. However, this index is less informative when two ROC curves cross and have similar AUCs. In order to detect differences between ROC curves in such situations, a two-stage nonparametric test that uses a shifted area under the ROC curve (sAUC), along with AUCs, is proposed for paired designs. The new procedure is shown, numerically, to be effective in terms of power under a wide range of scenarios; additionally, it outperforms two conventional ROC-type tests, especially when two ROC curves cross each other and have similar AUCs. Larger sAUC implies larger partial AUC at the range of low false-positive rates in this case. Because high specificity is important in many classification tasks, such as medical diagnosis, this is an appealing characteristic. The test also implicitly analyzes the equality of two commonly used binormal ROC curves at every operating point. We also apply the proposed method to synthesized data and two real examples to illustrate its usefulness in practice.

  5. Consistency Results for the ROC Curves of Fused Classifiers

    National Research Council Canada - National Science Library

    Bjerkaas, Kristopher

    2004-01-01

    .... An established performance quantifier is the Receiver Operating Characteristic (ROC) curve, which allows one to view the probability of detection versus the probability of false alarm in one graph...

  6. Receiver operating characteristics of perceptrons : Influence of sample size and prevalence

    NARCIS (Netherlands)

    Freking, Ansgar; Biehl, Michael; Braun, Christian; Kinzel, Wolfgang; Meesmann, Malte

    1999-01-01

    In many practical classification problems it is important to distinguish false positive from false negative results when evaluating the performance of the classifier. This is of particular importance for medical diagnostic tests. In this context, receiver operating characteristic (ROC) curves have

  7. Basic principles of ROC analysis

    International Nuclear Information System (INIS)

    Metz, C.E.

    1978-01-01

    The limitations of diagnostic accuracy as a measure of decision performance require introduction of the concepts of the sensitivity and specificity of a diagnostic test. These measures and the related indices, true positive fraction and false positive fraction, are more meaningful than accuracy, yet do not provide a unique description of diagnostic performance because they depend on the arbitrary selection of a decision threshold. The receiver operating characteristic (ROC) curve is shown to be a simple yet complete empirical description of this decision threshold effect, indicating all possible combinations of the relative frequencies of the various kinds of correct and incorrect decisions. Practical experimental techniques for measuring ROC curves are described, and the issues of case selection and curve-fitting are discussed briefly. Possible generalizations of conventional ROC analysis to account for decision performance in complex diagnostic tasks are indicated. ROC analysis is shown to be related in a direct and natural way to cost/benefit analysis of diagnostic decision making. The concepts of average diagnostic cost and average net benefit are developed and used to identify the optimal compromise among various kinds of diagnostic error. Finally, the way in which ROC analysis can be employed to optimize diagnostic strategies is suggested

  8. Transformation-invariant and nonparametric monotone smooth estimation of ROC curves.

    Science.gov (United States)

    Du, Pang; Tang, Liansheng

    2009-01-30

    When a new diagnostic test is developed, it is of interest to evaluate its accuracy in distinguishing diseased subjects from non-diseased subjects. The accuracy of the test is often evaluated by receiver operating characteristic (ROC) curves. Smooth ROC estimates are often preferable for continuous test results when the underlying ROC curves are in fact continuous. Nonparametric and parametric methods have been proposed by various authors to obtain smooth ROC curve estimates. However, there are certain drawbacks with the existing methods. Parametric methods need specific model assumptions. Nonparametric methods do not always satisfy the inherent properties of the ROC curves, such as monotonicity and transformation invariance. In this paper we propose a monotone spline approach to obtain smooth monotone ROC curves. Our method ensures important inherent properties of the underlying ROC curves, which include monotonicity, transformation invariance, and boundary constraints. We compare the finite sample performance of the newly proposed ROC method with other ROC smoothing methods in large-scale simulation studies. We illustrate our method through a real life example. Copyright (c) 2008 John Wiley & Sons, Ltd.

  9. Recollection is a continuous process: Evidence from plurality memory receiver operating characteristics.

    Science.gov (United States)

    Slotnick, Scott D; Jeye, Brittany M; Dodson, Chad S

    2016-01-01

    Is recollection a continuous/graded process or a threshold/all-or-none process? Receiver operating characteristic (ROC) analysis can answer this question as the continuous model and the threshold model predict curved and linear recollection ROCs, respectively. As memory for plurality, an item's previous singular or plural form, is assumed to rely on recollection, the nature of recollection can be investigated by evaluating plurality memory ROCs. The present study consisted of four experiments. During encoding, words (singular or plural) or objects (single/singular or duplicate/plural) were presented. During retrieval, old items with the same plurality or different plurality were presented. For each item, participants made a confidence rating ranging from "very sure old", which was correct for same plurality items, to "very sure new", which was correct for different plurality items. Each plurality memory ROC was the proportion of same versus different plurality items classified as "old" (i.e., hits versus false alarms). Chi-squared analysis revealed that all of the plurality memory ROCs were adequately fit by the continuous unequal variance model, whereas none of the ROCs were adequately fit by the two-high threshold model. These plurality memory ROC results indicate recollection is a continuous process, which complements previous source memory and associative memory ROC findings.

  10. Optimal Joint Detection and Estimation That Maximizes ROC-Type Curves.

    Science.gov (United States)

    Wunderlich, Adam; Goossens, Bart; Abbey, Craig K

    2016-09-01

    Combined detection-estimation tasks are frequently encountered in medical imaging. Optimal methods for joint detection and estimation are of interest because they provide upper bounds on observer performance, and can potentially be utilized for imaging system optimization, evaluation of observer efficiency, and development of image formation algorithms. We present a unified Bayesian framework for decision rules that maximize receiver operating characteristic (ROC)-type summary curves, including ROC, localization ROC (LROC), estimation ROC (EROC), free-response ROC (FROC), alternative free-response ROC (AFROC), and exponentially-transformed FROC (EFROC) curves, succinctly summarizing previous results. The approach relies on an interpretation of ROC-type summary curves as plots of an expected utility versus an expected disutility (or penalty) for signal-present decisions. We propose a general utility structure that is flexible enough to encompass many ROC variants and yet sufficiently constrained to allow derivation of a linear expected utility equation that is similar to that for simple binary detection. We illustrate our theory with an example comparing decision strategies for joint detection-estimation of a known signal with unknown amplitude. In addition, building on insights from our utility framework, we propose new ROC-type summary curves and associated optimal decision rules for joint detection-estimation tasks with an unknown, potentially-multiple, number of signals in each observation.

  11. Impact of signal scattering and parametric uncertainties on receiver operating characteristics

    Science.gov (United States)

    Wilson, D. Keith; Breton, Daniel J.; Hart, Carl R.; Pettit, Chris L.

    2017-05-01

    The receiver operating characteristic (ROC curve), which is a plot of the probability of detection as a function of the probability of false alarm, plays a key role in the classical analysis of detector performance. However, meaningful characterization of the ROC curve is challenging when practically important complications such as variations in source emissions, environmental impacts on the signal propagation, uncertainties in the sensor response, and multiple sources of interference are considered. In this paper, a relatively simple but realistic model for scattered signals is employed to explore how parametric uncertainties impact the ROC curve. In particular, we show that parametric uncertainties in the mean signal and noise power substantially raise the tails of the distributions; since receiver operation with a very low probability of false alarm and a high probability of detection is normally desired, these tails lead to severely degraded performance. Because full a priori knowledge of such parametric uncertainties is rarely available in practice, analyses must typically be based on a finite sample of environmental states, which only partially characterize the range of parameter variations. We show how this effect can lead to misleading assessments of system performance. For the cases considered, approximately 64 or more statistically independent samples of the uncertain parameters are needed to accurately predict the probabilities of detection and false alarm. A connection is also described between selection of suitable distributions for the uncertain parameters, and Bayesian adaptive methods for inferring the parameters.

  12. Critical thresholds of liver function parameters for ketosis prediction in dairy cows using receiver operating characteristic (ROC) analysis.

    Science.gov (United States)

    Sun, Yuhang; Wang, Bo; Shu, Shi; Zhang, Hongyou; Xu, Chuang; Wu, Ling; Xia, Cheng

    2015-01-01

    Fatty liver syndrome and ketosis are important metabolic disorders in high-producing cows during early lactation with fatty liver usually preceding ketosis. To date, parameters for early prediction of the risk of ketosis have not been investigated in China. To determine the predictive value of some parameters on the risk of ketosis in China. In a descriptive study, 48 control and 32 ketotic Holstein Friesian cows were randomly selected from one farm with a serum β-hydroxybutyrate (BHBA) concentration of 1.20 mmol/L as cutoff point. The risk prediction thresholds for ketosis were determined by receiver operating characteristic (ROC) analysis. In line with a high BHBA concentration, blood glucose concentration was significantly lower in ketotic cows compared to control animals (2.77 ± 0.24 versus 3.34 ± 0.03 mmol/L; P = 0.02). Thresholds were more than 0.76 mmol/L for nonesterified fatty acids (NEFA, with 65% sensitivity and 92% specificity), more than 104 U/L for aspartate aminotransferase (AST, 74% and 85%, respectively), less than 140 U/L for cholinesterase (CHE, 75% and 59%, respectively), and more than 3.3 µmol/L for total bilirubin (TBIL, 58% and 83%, respectively). There were significant correlations between BHBA and glucose (R = -4.74), or CHE (R = -0.262), BHBA and NEFA (R = 0.520), or AST (R = 0.525), or TBIL (R = 0.278), or direct bilirubin (DBIL, R = 0.348). AST, CHE, TBIL and NEFA may be useful parameters for risk prediction of ketosis. This study might be of value in addressing novel directions for future research on the connection between ketosis and liver dysfunction.

  13. Receiver Operating Characteristic Analysis for Detecting Explosives-related Threats

    Energy Technology Data Exchange (ETDEWEB)

    Oxley, Mark E; Venzin, Alexander M

    2012-11-14

    The Department of Homeland Security (DHS) and the Transportation Security Administration (TSA) are interested in developing a standardized testing procedure for determining the performance of candidate detection systems. This document outlines a potential method for judging detection system performance as well as determining if combining the information from a legacy system with a new system can signicantly improve performance. In this document, performance corresponds to the Neyman-Pearson criterion applied to the Receiver Operating Characteristic (ROC) curves of the detection systems in question. A simulation was developed to investigate how the amount of data provided by the vendor in the form of the ROC curve eects the performance of the combined detection system. Furthermore, the simulation also takes into account the potential eects of correlation and how this information can also impact the performance of the combined system.

  14. Receiver operating characteristic analysis improves diagnosis by radionuclide ventriculography

    International Nuclear Information System (INIS)

    Dickinson, C.Z.; Forman, M.B.; Vaugh, W.K.; Sandler, M.P.; Kronenberg, M.W.

    1985-01-01

    Receiver operating characteristic analysis (ROC) evaluates continuous variables to define diagnostic criteria for the optimal sensitivity (SENS) and specificity (SPEC) of a test. The authors studied exercise-induced chest pain (CP), ST-changes on electrocardiography (ECG) and rest-exercise gated radionuclide ventriculography (RVG) using ROC to clarify the optimal criteria for detecting myocardial ischemia due to coronary artherosclerosis (CAD). The data of 95 consecutive patients studied with coronary angiography, rest-exercise RVG and ECG were reviewed. 77 patients had ''significant'' CAD (≥50% lesions). Exercise-induced CP, ECG abnormalities (ST-T shifts) and RVG abnormalities (change in ejection fraction, 2-view regional wall motion change and relative end-systolic volume) were evaluated to define optimal SENS/SPEC of each and for the combined data. ROC curves were constructed by multiple logistic regression (MLR). By MLR, RVG alone was superior to ECG and CP. The combination of all three produced the best ROC curve for the entire group and for clinical subsets based on the number of diseased vessels and the presence or absence of prior myocardial infarction. When CP, ECG and RVG were combined, the optimal SENS/SPEC for detection of single vessel disease was 88/86. The SENS/SPEC for 3 vessel disease was 93/95. Thus, the application of RVG for the diagnosis of myocardial ischemia is improved with the inclusion of ECG and CP data by the use of a multiple logistic regression model. ROC analysis allows clinical application of multiple data for diagnosing CAD at desired SENS/SPEC rather than by arbitrary single-standard criteria

  15. Compare diagnostic tests using transformation-invariant smoothed ROC curves⋆

    Science.gov (United States)

    Tang, Liansheng; Du, Pang; Wu, Chengqing

    2012-01-01

    Receiver operating characteristic (ROC) curve, plotting true positive rates against false positive rates as threshold varies, is an important tool for evaluating biomarkers in diagnostic medicine studies. By definition, ROC curve is monotone increasing from 0 to 1 and is invariant to any monotone transformation of test results. And it is often a curve with certain level of smoothness when test results from the diseased and non-diseased subjects follow continuous distributions. Most existing ROC curve estimation methods do not guarantee all of these properties. One of the exceptions is Du and Tang (2009) which applies certain monotone spline regression procedure to empirical ROC estimates. However, their method does not consider the inherent correlations between empirical ROC estimates. This makes the derivation of the asymptotic properties very difficult. In this paper we propose a penalized weighted least square estimation method, which incorporates the covariance between empirical ROC estimates as a weight matrix. The resulting estimator satisfies all the aforementioned properties, and we show that it is also consistent. Then a resampling approach is used to extend our method for comparisons of two or more diagnostic tests. Our simulations show a significantly improved performance over the existing method, especially for steep ROC curves. We then apply the proposed method to a cancer diagnostic study that compares several newly developed diagnostic biomarkers to a traditional one. PMID:22639484

  16. Receiver operating characteristic (ROC) curve for classification of {sup 18}F-NaF uptake on PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Valadares, Agnes Araujo, E-mail: agnesvaladares@me.com [Universidade de Sao Paulo (HC/FM/USP), SP (Brazil). Hospital das Clinicas. Fac. de Mediciana; Duarte, Paulo Schiavom; Ono, Carla Rachel; Coura-Filho, George Barberio; Sado, Heitor Naoki; Carvalho, Giovanna [Instituto do Cancer do Estado de Sao Paulo Octavio Frias de Oliveira (ICESP), Sao Paulo, SP (Brazil). Servico de Medicina Nuclear; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto [Universidade de Sao Paulo (FM/USP), Sao Paulo, SP (Brazil). Fac. de Medicina. Dept. de Radiologia e Oncologia

    2016-01-15

    Objective: To assess the cutoff values established by ROC curves to classify {sup 18}F-NaF uptake as normal or malignant. Materials and Methods: PET/CT images were acquired 1 hour after administration of 185 MBq of {sup 18}F-NaF. Volumes of interest (VOIs) were drawn on three regions of the skeleton as follows: proximal right humerus diaphysis (HD), proximal right femoral diaphysis (FD) and first vertebral body (VB1), in a total of 254 patients, totalling 762 VOIs. The uptake in the VOIs was classified as normal or malignant on the basis of the radiopharmaceutical distribution pattern and of the CT images. A total of 675 volumes were classified as normal and 52 were classified as malignant. Thirty-five VOIs classified as indeterminate or nonmalignant lesions were excluded from analysis. The standardized uptake value (SUV) measured on the VOIs were plotted on an ROC curve for each one of the three regions. The area under the ROC (AUC) as well as the best cutoff SUVs to classify the VOIs were calculated. The best cutoff values were established as the ones with higher result of the sum of sensitivity and specificity. Results: The AUCs were 0.933, 0.889 and 0.975 for UD, FD and VB1, respectively. The best SUV cutoffs were 9.0 (sensitivity: 73%; specificity: 99%), 8.4 (sensitivity: 79%; specificity: 94%) and 21.0 (sensitivity: 93%; specificity: 95%) for UD, FD and VB1, respectively. Conclusion: The best cutoff value varies according to bone region of analysis and it is not possible to establish one value for the whole body. (author)

  17. Predictive factors in patients with hepatocellular carcinoma receiving sorafenib therapy using time-dependent receiver operating characteristic analysis.

    Science.gov (United States)

    Nishikawa, Hiroki; Nishijima, Norihiro; Enomoto, Hirayuki; Sakamoto, Azusa; Nasu, Akihiro; Komekado, Hideyuki; Nishimura, Takashi; Kita, Ryuichi; Kimura, Toru; Iijima, Hiroko; Nishiguchi, Shuhei; Osaki, Yukio

    2017-01-01

    To investigate variables before sorafenib therapy on the clinical outcomes in hepatocellular carcinoma (HCC) patients receiving sorafenib and to further assess and compare the predictive performance of continuous parameters using time-dependent receiver operating characteristics (ROC) analysis. A total of 225 HCC patients were analyzed. We retrospectively examined factors related to overall survival (OS) and progression free survival (PFS) using univariate and multivariate analyses. Subsequently, we performed time-dependent ROC analysis of continuous parameters which were significant in the multivariate analysis in terms of OS and PFS. Total sum of area under the ROC in all time points (defined as TAAT score) in each case was calculated. Our cohort included 175 male and 50 female patients (median age, 72 years) and included 158 Child-Pugh A and 67 Child-Pugh B patients. The median OS time was 0.68 years, while the median PFS time was 0.24 years. On multivariate analysis, gender, body mass index (BMI), Child-Pugh classification, extrahepatic metastases, tumor burden, aspartate aminotransferase (AST) and alpha-fetoprotein (AFP) were identified as significant predictors of OS and ECOG-performance status, Child-Pugh classification and extrahepatic metastases were identified as significant predictors of PFS. Among three continuous variables (i.e., BMI, AST and AFP), AFP had the highest TAAT score for the entire cohort. In subgroup analyses, AFP had the highest TAAT score except for Child-Pugh B and female among three continuous variables. In continuous variables, AFP could have higher predictive accuracy for survival in HCC patients undergoing sorafenib therapy.

  18. On the form of ROCs constructed from confidence ratings.

    Science.gov (United States)

    Malmberg, Kenneth J

    2002-03-01

    A classical question for memory researchers is whether memories vary in an all-or-nothing, discrete manner (e.g., stored vs. not stored, recalled vs. not recalled), or whether they vary along a continuous dimension (e.g., strength, similarity, or familiarity). For yes-no classification tasks, continuous- and discrete-state models predict nonlinear and linear receiver operating characteristics (ROCs), respectively (D. M. Green & J. A. Swets, 1966; N. A. Macmillan & C. D. Creelman, 1991). Recently, several authors have assumed that these predictions are generalizable to confidence ratings tasks (J. Qin, C. L. Raye, M. K. Johnson, & K. J. Mitchell, 2001; S. D. Slotnick, S. A. Klein, C. S. Dodson, & A. P. Shimamura, 2000, and A. P. Yonelinas, 1999). This assumption is shown to be unwarranted by showing that discrete-state ratings models predict both linear and nonlinear ROCs. The critical factor determining the form of the discrete-state ROC is the response strategy adopted by the classifier.

  19. "Remember" source memory ROCs indicate recollection is a continuous process.

    Science.gov (United States)

    Slotnick, Scott D

    2010-01-01

    The dual process model assumes memory is based on recollection (retrieval with specific detail) or familiarity (retrieval without specific detail). A current debate is whether recollection is a threshold process or, like familiarity, is a continuous process. In the present study two continuous models and two threshold models of recollection were evaluated using receiver operating characteristic (ROC) analysis. These models included the continuous signal detection unequal variance model and the threshold dual process model. In the study phase of three experiments, objects were presented to the right or left of fixation. At test, participants made either remember-know responses or item confidence responses followed by source memory (spatial location) confidence ratings. Recollection-based ROCs were generated from source memory confidence ratings associated with "remember" responses (in Experiments 1-2) or the highest item confidence responses (in Experiment 3). Neither threshold model adequately fit any of the recollection-based ROCs. By contrast, one or both of the continuous models adequately fit all of the recollection-based ROCs. The present results indicate recollection and familiarity are both continuous processes.

  20. Test for the statistical significance of differences between ROC curves

    International Nuclear Information System (INIS)

    Metz, C.E.; Kronman, H.B.

    1979-01-01

    A test for the statistical significance of observed differences between two measured Receiver Operating Characteristic (ROC) curves has been designed and evaluated. The set of observer response data for each ROC curve is assumed to be independent and to arise from a ROC curve having a form which, in the absence of statistical fluctuations in the response data, graphs as a straight line on double normal-deviate axes. To test the significance of an apparent difference between two measured ROC curves, maximum likelihood estimates of the two parameters of each curve and the associated parameter variances and covariance are calculated from the corresponding set of observer response data. An approximate Chi-square statistic with two degrees of freedom is then constructed from the differences between the parameters estimated for each ROC curve and from the variances and covariances of these estimates. This statistic is known to be truly Chi-square distributed only in the limit of large numbers of trials in the observer performance experiments. Performance of the statistic for data arising from a limited number of experimental trials was evaluated. Independent sets of rating scale data arising from the same underlying ROC curve were paired, and the fraction of differences found (falsely) significant was compared to the significance level, α, used with the test. Although test performance was found to be somewhat dependent on both the number of trials in the data and the position of the underlying ROC curve in the ROC space, the results for various significance levels showed the test to be reliable under practical experimental conditions

  1. An extension of the receiver operating characteristic curve and AUC-optimal classification.

    Science.gov (United States)

    Takenouchi, Takashi; Komori, Osamu; Eguchi, Shinto

    2012-10-01

    While most proposed methods for solving classification problems focus on minimization of the classification error rate, we are interested in the receiver operating characteristic (ROC) curve, which provides more information about classification performance than the error rate does. The area under the ROC curve (AUC) is a natural measure for overall assessment of a classifier based on the ROC curve. We discuss a class of concave functions for AUC maximization in which a boosting-type algorithm including RankBoost is considered, and the Bayesian risk consistency and the lower bound of the optimum function are discussed. A procedure derived by maximizing a specific optimum function has high robustness, based on gross error sensitivity. Additionally, we focus on the partial AUC, which is the partial area under the ROC curve. For example, in medical screening, a high true-positive rate to the fixed lower false-positive rate is preferable and thus the partial AUC corresponding to lower false-positive rates is much more important than the remaining AUC. We extend the class of concave optimum functions for partial AUC optimality with the boosting algorithm. We investigated the validity of the proposed method through several experiments with data sets in the UCI repository.

  2. Large-field image intensifiers versus conventional chest radiography: ROC study with simulated interstitial disease

    International Nuclear Information System (INIS)

    Winter, L.H.L.; Chakraborty, D.P.; Waes, P.F.G.M.

    1988-01-01

    Two image intensifier tubes have recently been introduced whose large imaging area makes them suitable for chest imaging (Phillips Pulmodiagnost TLX slit II and Siemens TX 57 large entrance field II). Both modalities present a 10 x 10-cm hard copy image to the radiologist. A receiver operating characteristic (ROC) curve study with simulated interstitial disease was performed to compare the image quality of these image intensifiers with conventional chest images. The relative ranking in terms of decreasing ROC areas was Siemens, conventional, and Philips. Compared with conventional imaging, none of the differences in ROC curve area were statistically significant at the 5% level

  3. ROC Analysis for Evaluation of Radiation Biodosimetry Technologies

    International Nuclear Information System (INIS)

    Williams, Benjamin B.; Swartz, Harold M.; Flood, Ann Barry; Demidenko, Eugene

    2016-01-01

    Receiver operating characteristic (ROC) analysis is a fundamental tool used for the evaluation and comparison of diagnostic systems that provides estimates of the combinations of sensitivity and specificity that can be achieved with a given technique. Along with critical considerations of practical limitations, such as throughput and time to availability of results, ROC analyses can be applied to provide meaningful assessments and comparisons of available biodosimetry methods. Accordingly, guidance from the Food and Drug Administration to evaluate biodosimetry devices recommends using ROC analysis. However, the existing literature for the numerous biodosimetry methods that have been developed to address the needs for triage either do not contain ROC analyses or present ROC analyses where the dose distributions of the study samples are not representative of the populations to be screened. The use of non-representative sample populations can result in a significant spectrum bias, where estimated performance metrics do not accurately characterize the true performance under real-world conditions. Particularly, in scenarios where a large group of people is screened because they were potentially exposed in a large-scale radiation event, directly measured population data do not exist. However, a number of complex simulations have been performed and reported in the literature that provide estimates of the required dose distributions. Based on these simulations and reported data about the output and uncertainties of biodosimetry assays, we illustrate how ROC curves can be generated that incorporate a realistic representative sample. A technique to generate ROC curves for biodosimetry data is presented along with representative ROC curves, summary statistics and discussion based on published data for triage-ready electron paramagnetic resonance in vivo tooth dosimetry, the dicentric chromosome assay and quantitative polymerase chain reaction assay. We argue that this

  4. Experimental Design and Data Analysis in Receiver Operating Characteristic Studies: Lessons Learned from Reports in Radiology from 1997 to 20061

    Science.gov (United States)

    Shiraishi, Junji; Pesce, Lorenzo L.; Metz, Charles E.; Doi, Kunio

    2009-01-01

    Purpose: To provide a broad perspective concerning the recent use of receiver operating characteristic (ROC) analysis in medical imaging by reviewing ROC studies published in Radiology between 1997 and 2006 for experimental design, imaging modality, medical condition, and ROC paradigm. Materials and Methods: Two hundred ninety-five studies were obtained by conducting a literature search with PubMed with two criteria: publication in Radiology between 1997 and 2006 and occurrence of the phrase “receiver operating characteristic.” Studies returned by the query that were not diagnostic imaging procedure performance evaluations were excluded. Characteristics of the remaining studies were tabulated. Results: Two hundred thirty-three (79.0%) of the 295 studies reported findings based on observers' diagnostic judgments or objective measurements. Forty-three (14.6%) did not include human observers, with most of these reporting an evaluation of a computer-aided diagnosis system or functional data obtained with computed tomography (CT) or magnetic resonance (MR) imaging. The remaining 19 (6.4%) studies were classified as reviews or meta-analyses and were excluded from our subsequent analysis. Among the various imaging modalities, MR imaging (46.0%) and CT (25.7%) were investigated most frequently. Approximately 60% (144 of 233) of ROC studies with human observers published in Radiology included three or fewer observers. Conclusion: ROC analysis is widely used in radiologic research, confirming its fundamental role in assessing diagnostic performance. However, the ROC studies reported in Radiology were not always adequate to support clear and clinically relevant conclusions. © RSNA, 2009 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2533081632/-/DC1 PMID:19864510

  5. Separating Mnemonic Process From Participant and Item Effects in the Assessment of ROC Asymmetries

    NARCIS (Netherlands)

    Pratte, Michael S.; Rouder, Jeffrey N.; Morey, Richard D.

    One of the most influential findings in the study of recognition memory is that receiver operating characteristic (ROC) curves are asymmetric about the negative diagonal. This result has led to the rejection of the equal-variance signal detection model of recognition memory and has provided

  6. Three-class ROC analysis--the equal error utility assumption and the optimality of three-class ROC surface using the ideal observer.

    Science.gov (United States)

    He, Xin; Frey, Eric C

    2006-08-01

    Previously, we have developed a decision model for three-class receiver operating characteristic (ROC) analysis based on decision theory. The proposed decision model maximizes the expected decision utility under the assumption that incorrect decisions have equal utilities under the same hypothesis (equal error utility assumption). This assumption reduced the dimensionality of the "general" three-class ROC analysis and provided a practical figure-of-merit to evaluate the three-class task performance. However, it also limits the generality of the resulting model because the equal error utility assumption will not apply for all clinical three-class decision tasks. The goal of this study was to investigate the optimality of the proposed three-class decision model with respect to several other decision criteria. In particular, besides the maximum expected utility (MEU) criterion used in the previous study, we investigated the maximum-correctness (MC) (or minimum-error), maximum likelihood (ML), and Nyman-Pearson (N-P) criteria. We found that by making assumptions for both MEU and N-P criteria, all decision criteria lead to the previously-proposed three-class decision model. As a result, this model maximizes the expected utility under the equal error utility assumption, maximizes the probability of making correct decisions, satisfies the N-P criterion in the sense that it maximizes the sensitivity of one class given the sensitivities of the other two classes, and the resulting ROC surface contains the maximum likelihood decision operating point. While the proposed three-class ROC analysis model is not optimal in the general sense due to the use of the equal error utility assumption, the range of criteria for which it is optimal increases its applicability for evaluating and comparing a range of diagnostic systems.

  7. Rocker: Open source, easy-to-use tool for AUC and enrichment calculations and ROC visualization.

    Science.gov (United States)

    Lätti, Sakari; Niinivehmas, Sanna; Pentikäinen, Olli T

    2016-01-01

    Receiver operating characteristics (ROC) curve with the calculation of area under curve (AUC) is a useful tool to evaluate the performance of biomedical and chemoinformatics data. For example, in virtual drug screening ROC curves are very often used to visualize the efficiency of the used application to separate active ligands from inactive molecules. Unfortunately, most of the available tools for ROC analysis are implemented into commercially available software packages, or are plugins in statistical software, which are not always the easiest to use. Here, we present Rocker, a simple ROC curve visualization tool that can be used for the generation of publication quality images. Rocker also includes an automatic calculation of the AUC for the ROC curve and Boltzmann-enhanced discrimination of ROC (BEDROC). Furthermore, in virtual screening campaigns it is often important to understand the early enrichment of active ligand identification, for this Rocker offers automated calculation routine. To enable further development of Rocker, it is freely available (MIT-GPL license) for use and modifications from our web-site (http://www.jyu.fi/rocker).

  8. Receiver-operating characteristic curves for somatic cell scores and California mastitis test in Valle del Be lice dairy sheep

    NARCIS (Netherlands)

    Riggio, V.; Pesce, L.L.; Morreale, S.; Portolano, B.

    2013-01-01

    Using receiver-operating characteristic (ROC) curve methodology this study was designed to assess the diagnostic effectiveness of somatic cell count (SCC) and the California mastitis test (CMT) in Valle del Belice sheep, and to propose and evaluate threshold values for those tests that would

  9. Receiver operating characteristic analysis and its potential role in evaluating the effect of head movement in PET of the brain

    International Nuclear Information System (INIS)

    Patterson, H.; Clarke, G.H.; Lombardo, P.; McKay, W.J.; Austin and Repatriation Medical Centre, Heidelberg, VIC

    1999-01-01

    Full text: We outline an example of receiver operating characteristic (ROC) analysis in the assessment of image quality. ROC analysis is a measure of image quality that accounts for the consequences of the decision and the role of the observer. Kim and Haynie (Nuclear Diagnostic Imaging: Practical Clinical Applications. Melbourne: Macmillan, 1987) describe ROC analysis as an 'objective approach to the evaluation of diagnostic decision making'. ROC analysis is an ideal technique for evaluating images of a Hoffman brain phantom obtained using positron emission tomography. Images have been acquired with the phantom in different positions. The position of the phantom and the time the phantom remained in each position was based on the measurements of head movement during simulated brain imaging (Patterson et al., Technologists Symposium, ANZSNM, 1998). This study was undertaken to explore the potential of ROC analysis in determining the effect of movement on the ability to detect lesions of various sizes

  10. Receiver operating characteristic analysis of age-related changes in lineup performance.

    Science.gov (United States)

    Humphries, Joyce E; Flowe, Heather D

    2015-04-01

    In the basic face memory literature, support has been found for the late maturation hypothesis, which holds that face recognition ability is not fully developed until at least adolescence. Support for the late maturation hypothesis in the criminal lineup identification literature, however, has been equivocal because of the analytic approach that has been used to examine age-related changes in identification performance. Recently, receiver operator characteristic (ROC) analysis was applied for the first time in the adult eyewitness memory literature to examine whether memory sensitivity differs across different types of lineup tests. ROC analysis allows for the separation of memory sensitivity from response bias in the analysis of recognition data. Here, we have made the first ROC-based comparison of adults' and children's (5- and 6-year-olds and 9- and 10-year-olds) memory performance on lineups by reanalyzing data from Humphries, Holliday, and Flowe (2012). In line with the late maturation hypothesis, memory sensitivity was significantly greater for adults compared with young children. Memory sensitivity for older children was similar to that for adults. The results indicate that the late maturation hypothesis can be generalized to account for age-related performance differences on an eyewitness memory task. The implications for developmental eyewitness memory research are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Optimal algorithm for automatic detection of microaneurysms based on receiver operating characteristic curve

    Science.gov (United States)

    Xu, Lili; Luo, Shuqian

    2010-11-01

    Microaneurysms (MAs) are the first manifestations of the diabetic retinopathy (DR) as well as an indicator for its progression. Their automatic detection plays a key role for both mass screening and monitoring and is therefore in the core of any system for computer-assisted diagnosis of DR. The algorithm basically comprises the following stages: candidate detection aiming at extracting the patterns possibly corresponding to MAs based on mathematical morphological black top hat, feature extraction to characterize these candidates, and classification based on support vector machine (SVM), to validate MAs. Feature vector and kernel function of SVM selection is very important to the algorithm. We use the receiver operating characteristic (ROC) curve to evaluate the distinguishing performance of different feature vectors and different kernel functions of SVM. The ROC analysis indicates the quadratic polynomial SVM with a combination of features as the input shows the best discriminating performance.

  12. Separating Mnemonic Process from Participant and Item Effects in the Assessment of ROC Asymmetries

    Science.gov (United States)

    Pratte, Michael S.; Rouder, Jeffrey N.; Morey, Richard D.

    2010-01-01

    One of the most influential findings in the study of recognition memory is that receiver operating characteristic (ROC) curves are asymmetric about the negative diagonal. This result has led to the rejection of the equal-variance signal detection model of recognition memory and has provided motivation for more complex models, such as the…

  13. ROC curve analyses of eyewitness identification decisions: An analysis of the recent debate.

    Science.gov (United States)

    Rotello, Caren M; Chen, Tina

    2016-01-01

    How should the accuracy of eyewitness identification decisions be measured, so that best practices for identification can be determined? This fundamental question is under intense debate. One side advocates for continued use of a traditional measure of identification accuracy, known as the diagnosticity ratio , whereas the other side argues that receiver operating characteristic curves (ROCs) should be used instead because diagnosticity is confounded with response bias. Diagnosticity proponents have offered several criticisms of ROCs, which we show are either false or irrelevant to the assessment of eyewitness accuracy. We also show that, like diagnosticity, Bayesian measures of identification accuracy confound response bias with witnesses' ability to discriminate guilty from innocent suspects. ROCs are an essential tool for distinguishing memory-based processes from decisional aspects of a response; simulations of different possible identification tasks and response strategies show that they offer important constraints on theory development.

  14. Beyond ROC Curvature: Strength Effects and Response Time Data Support Continuous-Evidence Models of Recognition Memory

    Science.gov (United States)

    Dube, Chad; Starns, Jeffrey J.; Rotello, Caren M.; Ratcliff, Roger

    2012-01-01

    A classic question in the recognition memory literature is whether retrieval is best described as a continuous-evidence process consistent with signal detection theory (SDT), or a threshold process consistent with many multinomial processing tree (MPT) models. Because receiver operating characteristics (ROCs) based on confidence ratings are…

  15. A bivariate contaminated binormal model for robust fitting of proper ROC curves to a pair of correlated, possibly degenerate, ROC datasets.

    Science.gov (United States)

    Zhai, Xuetong; Chakraborty, Dev P

    2017-06-01

    The objective was to design and implement a bivariate extension to the contaminated binormal model (CBM) to fit paired receiver operating characteristic (ROC) datasets-possibly degenerate-with proper ROC curves. Paired datasets yield two correlated ratings per case. Degenerate datasets have no interior operating points and proper ROC curves do not inappropriately cross the chance diagonal. The existing method, developed more than three decades ago utilizes a bivariate extension to the binormal model, implemented in CORROC2 software, which yields improper ROC curves and cannot fit degenerate datasets. CBM can fit proper ROC curves to unpaired (i.e., yielding one rating per case) and degenerate datasets, and there is a clear scientific need to extend it to handle paired datasets. In CBM, nondiseased cases are modeled by a probability density function (pdf) consisting of a unit variance peak centered at zero. Diseased cases are modeled with a mixture distribution whose pdf consists of two unit variance peaks, one centered at positive μ with integrated probability α, the mixing fraction parameter, corresponding to the fraction of diseased cases where the disease was visible to the radiologist, and one centered at zero, with integrated probability (1-α), corresponding to disease that was not visible. It is shown that: (a) for nondiseased cases the bivariate extension is a unit variances bivariate normal distribution centered at (0,0) with a specified correlation ρ 1 ; (b) for diseased cases the bivariate extension is a mixture distribution with four peaks, corresponding to disease not visible in either condition, disease visible in only one condition, contributing two peaks, and disease visible in both conditions. An expression for the likelihood function is derived. A maximum likelihood estimation (MLE) algorithm, CORCBM, was implemented in the R programming language that yields parameter estimates and the covariance matrix of the parameters, and other statistics

  16. Summary receiver operating characteristic curves as a technique for meta-analysis of the diagnostic performance of duplex ultrasonography in peripheral arterial disease

    NARCIS (Netherlands)

    deVries, SO; Hunink, MGM; Polak, JF

    Rationale and Objectives. We summarized and compared the diagnostic performance of duplex and color-guided duplex ultrasonography in the evaluation of peripheral arterial disease. We present our research as an example of the use of summary receiver operating characteristic (ROC) curves in a

  17. Reader characteristics linked to detection of pulmonary nodules on radiographs: ROC vs. JAFROC analyses of performance

    Science.gov (United States)

    Kohli, Akshay; Robinson, John W.; Ryan, John; McEntee, Mark F.; Brennan, Patrick C.

    2011-03-01

    The purpose of this study is to explore whether reader characteristics are linked to heightened levels of diagnostic performance in chest radiology using receiver operating characteristic (ROC) and jackknife free response ROC (JAFROC) methodologies. A set of 40 postero-anterior chest radiographs was developed, of which 20 were abnormal containing one or more simulated nodules, of varying subtlety. Images were independently reviewed by 12 boardcertified radiologists including six chest specialists. The observer performance was measured in terms of ROC and JAFROC scores. For the ROC analysis, readers were asked to rate their degree of suspicion for the presence of nodules by using a confidence rating scale (1-6). JAFROC analysis required the readers to locate and rate as many suspicious areas as they wished using the same scale and resultant data were used to generate Az and FOM scores for ROC and JAFROC analyses respectively. Using Pearson methods, scores of performance were correlated with 7 reader characteristics recorded using a questionnaire. JAFROC analysis showed that improved reader performance was significantly (pchest specialty (pchest radiographs (pchest readings per year (pchest radiographs (pchest specialty, hours reading per week and number of radiographs read per year. Also, JAFROC is a more powerful predictor of performance as compared to ROC.

  18. Receiver operating characteristic analysis of regional cerebral blood flow in Alzheimer's disease

    International Nuclear Information System (INIS)

    Zemcov, A.; Barclay, L.L.; Sansone, J.; Metz, C.E.

    1985-01-01

    Receiver operating characteristic (ROC) curves were used to quantitatively assess the ability of individual detectors in a 32-detector 133 Xe inhalation system to discriminate between two populations over the range of regional cerebral blood flow (rCBF) values. These populations were clinically evaluated as normal (age 63.1 +/- 13.1, n = 23) and presumed Alzheimer's disease (age 72.7 +/- 7.0, n = 82). Summary statistics showed that for homologous detectors the average value of blood flow in the normal group was greater than the flow value in the group of subjects with Alzheimer's disease. Conclusions drawn from single values of flow or mean hemispheric flow can lead to erroneous conclusions about hemisphere asymmetries. However, the dynamic relationship between the correct identifications (true positives) compared with incorrect identifications (false positives) of Alzheimer's disease at each detector varies over the range of blood flow values, and quantitative characterization of this relationship in terms of an ROC curve provides more insight into the structure of the data. Detectors approximating the speech, auditory and association cortex were most effective in discriminating between groups. Frontal detectors were marginally useful diagnostically

  19. Optimizing area under the ROC curve using semi-supervised learning.

    Science.gov (United States)

    Wang, Shijun; Li, Diana; Petrick, Nicholas; Sahiner, Berkman; Linguraru, Marius George; Summers, Ronald M

    2015-01-01

    Receiver operating characteristic (ROC) analysis is a standard methodology to evaluate the performance of a binary classification system. The area under the ROC curve (AUC) is a performance metric that summarizes how well a classifier separates two classes. Traditional AUC optimization techniques are supervised learning methods that utilize only labeled data (i.e., the true class is known for all data) to train the classifiers. In this work, inspired by semi-supervised and transductive learning, we propose two new AUC optimization algorithms hereby referred to as semi-supervised learning receiver operating characteristic (SSLROC) algorithms, which utilize unlabeled test samples in classifier training to maximize AUC. Unlabeled samples are incorporated into the AUC optimization process, and their ranking relationships to labeled positive and negative training samples are considered as optimization constraints. The introduced test samples will cause the learned decision boundary in a multidimensional feature space to adapt not only to the distribution of labeled training data, but also to the distribution of unlabeled test data. We formulate the semi-supervised AUC optimization problem as a semi-definite programming problem based on the margin maximization theory. The proposed methods SSLROC1 (1-norm) and SSLROC2 (2-norm) were evaluated using 34 (determined by power analysis) randomly selected datasets from the University of California, Irvine machine learning repository. Wilcoxon signed rank tests showed that the proposed methods achieved significant improvement compared with state-of-the-art methods. The proposed methods were also applied to a CT colonography dataset for colonic polyp classification and showed promising results.

  20. Receiver operating characteristic curve evaluation on computed radiography: an experimental study

    International Nuclear Information System (INIS)

    Yu Zixi; Wang Changyuan; Xu Yue; Xie Jindong; Zhang Menglong; Wang Jian

    2003-01-01

    Objective: To get the maximum information from computed radiography (CR) output images by changing post-processing parameters. Methods: Six experimental photos of polypropylene balls of 2.0 mm in diameter were taken by means of one time X-ray exposing on an imaging plate (IP) with different post-processing parameters including rotation amount (GA), gray gradation type (GT), rotation center (GC), shifting amount (GS), frequency rank (RN), frequency type (RT), and degree of enhancement (RE). 6 photos were viewed by three students and one radiologist on a 6000 lx illuminance viewbox. Receiver operating characteristic (ROC) curves were made by means of 5-value-differentiation method. Results: The largest mean area value (Az) below ROC curves of a low contrast experimental photo with post-processing parameters GA=1.0, GT=A, GC=1.6, GS=0.3, RN=4.0, RT=R and RE=3.0 was 0.96, and the maximum information was obtained. The smallest mean area value (Az) was 0.78 with changed post-processing parameters GA=0.8, GS=-0.2 and RE=0.5 while other parameters were not changed. The minimum information was obtained from this photo. Conclusion: In order to get the maximum information from a CR output image, the post-processing parameters should be suitably selected

  1. Optimization of restricted ROC surfaces in three-class classification tasks.

    Science.gov (United States)

    Edwards, Darrin C; Metz, Charles E

    2007-10-01

    We have shown previously that an N-class ideal observer achieves the optimal receiver operating characteristic (ROC) hypersurface in a Neyman-Pearson sense. Due to the inherent complexity of evaluating observer performance even in a three-class classification task, some researchers have suggested a generally incomplete but more tractable evaluation in terms of a surface, plotting only the three "sensitivities." More generally, one can evaluate observer performance with a single sensitivity or misclassification probability as a function of two linear combinations of sensitivities or misclassification probabilities. We analyzed four such formulations including the "sensitivity" surface. In each case, we applied the Neyman-Pearson criterion to find the observer which achieves optimal performance with respect to each given set of "performance description variables" under consideration. In the unrestricted case, optimization with respect to the Neyman-Pearson criterion yields the ideal observer, as does maximization of the observer's expected utility. Moreover, during our consideration of the restricted cases, we found that the two optimization methods do not merely yield the same observer, but are in fact completely equivalent in a mathematical sense. Thus, for a wide variety of observers which maximize performance with respect to a restricted ROC surface in the Neyman-Pearson sense, that ROC surface can also be shown to provide a complete description of the observer's performance in an expected utility sense.

  2. From Humans to Rats and Back Again: Bridging the Divide between Human and Animal Studies of Recognition Memory with Receiver Operating Characteristics

    Science.gov (United States)

    Koen, Joshua D.; Yonelinas, Andrew P.

    2011-01-01

    Receiver operating characteristics (ROCs) have been used extensively to study the processes underlying human recognition memory, and this method has recently been applied in studies of rats. However, the extent to which the results from human and animal studies converge is neither entirely clear, nor is it known how the different methods used to…

  3. Software for illustrative presentation of basic clinical characteristics of laboratory tests--GraphROC for Windows.

    Science.gov (United States)

    Kairisto, V; Poola, A

    1995-01-01

    GraphROC for Windows is a program for clinical test evaluation. It was designed for the handling of large datasets obtained from clinical laboratory databases. In the user interface, graphical and numerical presentations are combined. For simplicity, numerical data is not shown unless requested. Relevant numbers can be "picked up" from the graph by simple mouse operations. Reference distributions can be displayed by using automatically optimized bin widths. Any percentile of the distribution with corresponding confidence limits can be chosen for display. In sensitivity-specificity analysis, both illness- and health-related distributions are shown in the same graph. The following data for any cutoff limit can be shown in a separate click window: clinical sensitivity and specificity with corresponding confidence limits, positive and negative likelihood ratios, positive and negative predictive values and efficiency. Predictive values and clinical efficiency of the cutoff limit can be updated for any prior probability of disease. Receiver Operating Characteristics (ROC) curves can be generated and combined into the same graph for comparison of several different tests. The area under the curve with corresponding confidence interval is calculated for each ROC curve. Numerical results of analyses and graphs can be printed or exported to other Microsoft Windows programs. GraphROC for Windows also employs a new method, developed by us, for the indirect estimation of health-related limits and change limits from mixed distributions of clinical laboratory data.

  4. StAR: a simple tool for the statistical comparison of ROC curves

    Directory of Open Access Journals (Sweden)

    Melo Francisco

    2008-06-01

    Full Text Available Abstract Background As in many different areas of science and technology, most important problems in bioinformatics rely on the proper development and assessment of binary classifiers. A generalized assessment of the performance of binary classifiers is typically carried out through the analysis of their receiver operating characteristic (ROC curves. The area under the ROC curve (AUC constitutes a popular indicator of the performance of a binary classifier. However, the assessment of the statistical significance of the difference between any two classifiers based on this measure is not a straightforward task, since not many freely available tools exist. Most existing software is either not free, difficult to use or not easy to automate when a comparative assessment of the performance of many binary classifiers is intended. This constitutes the typical scenario for the optimization of parameters when developing new classifiers and also for their performance validation through the comparison to previous art. Results In this work we describe and release new software to assess the statistical significance of the observed difference between the AUCs of any two classifiers for a common task estimated from paired data or unpaired balanced data. The software is able to perform a pairwise comparison of many classifiers in a single run, without requiring any expert or advanced knowledge to use it. The software relies on a non-parametric test for the difference of the AUCs that accounts for the correlation of the ROC curves. The results are displayed graphically and can be easily customized by the user. A human-readable report is generated and the complete data resulting from the analysis are also available for download, which can be used for further analysis with other software. The software is released as a web server that can be used in any client platform and also as a standalone application for the Linux operating system. Conclusion A new software for

  5. Roc curves for continuous data

    CERN Document Server

    Krzanowski, Wojtek J

    2009-01-01

    Since ROC curves have become ubiquitous in many application areas, the various advances have been scattered across disparate articles and texts. ROC Curves for Continuous Data is the first book solely devoted to the subject, bringing together all the relevant material to provide a clear understanding of how to analyze ROC curves.The fundamental theory of ROC curvesThe book first discusses the relationship between the ROC curve and numerous performance measures and then extends the theory into practice by describing how ROC curves are estimated. Further building on the theory, the authors prese

  6. Face recognition in schizophrenia: do individual and average ROCs tell the same story?

    Science.gov (United States)

    Tiberghien, Guy; Martin, Clara; Baudouin, Jean-Yves; Franck, Nicolas; Guillaume, Fabrice; Huron, Caroline

    2015-01-01

    Many studies have shown that recollection process is impaired in patients with schizophrenia, whereas familiarity is generally spared. However, in these studies, the Receiver Operating Characteristic (ROC) presented is average ROC likely to mask individual differences. In the present study using a face-recognition task, we computed the individual ROC of patients with schizophrenia and control participants. Each group was divided into two subgroups on the basis of the type of recognition processes implemented: recognition based on familiarity only and recognition based on familiarity and recollection. The recognition performance of the schizophrenia patients was below that of the control participants only when recognition was based solely on familiarity. For the familiarity-alone patients, the score obtained on the Scale for the Assessment of Positive Symptoms (SAPS) was correlated with the variance of the old-face familiarity. For the familiarity-recollection patients, the score obtained on the Scale for the Assessment of Negative Symptoms (SANS) was correlated with the decision criterion and with the old-face recollection probability. These results show that one cannot ascribe the impaired recognition observed in patients with schizophrenia to a recollection deficit alone. These results show that individual ROC can be used to distinguish between subtypes of schizophrenia and could serve as a basis for setting up specific cognitive remediation therapy for individuals with schizophrenia.

  7. Disadvantages of using the area under the receiver operating characteristic curve to assess imaging tests: A discussion and proposal for an alternative approach

    International Nuclear Information System (INIS)

    Halligan, Steve; Altman, Douglas G.; Mallett, Susan

    2015-01-01

    The objectives are to describe the disadvantages of the area under the receiver operating characteristic curve (ROC AUC) to measure diagnostic test performance and to propose an alternative based on net benefit. We use a narrative review supplemented by data from a study of computer-assisted detection for CT colonography. We identified problems with ROC AUC. Confidence scoring by readers was highly non-normal, and score distribution was bimodal. Consequently, ROC curves were highly extrapolated with AUC mostly dependent on areas without patient data. AUC depended on the method used for curve fitting. ROC AUC does not account for prevalence or different misclassification costs arising from false-negative and false-positive diagnoses. Change in ROC AUC has little direct clinical meaning for clinicians. An alternative analysis based on net benefit is proposed, based on the change in sensitivity and specificity at clinically relevant thresholds. Net benefit incorporates estimates of prevalence and misclassification costs, and it is clinically interpretable since it reflects changes in correct and incorrect diagnoses when a new diagnostic test is introduced. ROC AUC is most useful in the early stages of test assessment whereas methods based on net benefit are more useful to assess radiological tests where the clinical context is known. Net benefit is more useful for assessing clinical impact. (orig.)

  8. RocKeTeria restaurant

    Science.gov (United States)

    2000-01-01

    When StenniSphere at John C. Stennis Space Center in Hancock County, Miss., opened in May 2000, it introduced the RocKeTeria, a new 1960s-style, space-themed restaurant located in the newly expanded visitor center. The restaurant, operated by the owners of Mary's Drive Inn of Biloxi, features an extensive collection of space-related photos from that era, as well as a full menu of home-style cooking.

  9. Theoretical vs. empirical discriminability: the application of ROC methods to eyewitness identification.

    Science.gov (United States)

    Wixted, John T; Mickes, Laura

    2018-01-01

    Receiver operating characteristic (ROC) analysis was introduced to the field of eyewitness identification 5 years ago. Since that time, it has been both influential and controversial, and the debate has raised an issue about measuring discriminability that is rarely considered. The issue concerns the distinction between empirical discriminability (measured by area under the ROC curve) vs. underlying/theoretical discriminability (measured by d' or variants of it). Under most circumstances, the two measures will agree about a difference between two conditions in terms of discriminability. However, it is possible for them to disagree, and that fact can lead to confusion about which condition actually yields higher discriminability. For example, if the two conditions have implications for real-world practice (e.g., a comparison of competing lineup formats), should a policymaker rely on the area-under-the-curve measure or the theory-based measure? Here, we illustrate the fact that a given empirical ROC yields as many underlying discriminability measures as there are theories that one is willing to take seriously. No matter which theory is correct, for practical purposes, the singular area-under-the-curve measure best identifies the diagnostically superior procedure. For that reason, area under the ROC curve informs policy in a way that underlying theoretical discriminability never can. At the same time, theoretical measures of discriminability are equally important, but for a different reason. Without an adequate theoretical understanding of the relevant task, the field will be in no position to enhance empirical discriminability.

  10. Paired receiver operating characteristic curves and the effect of history on radiographic interpretation: CT of the head as a case study

    International Nuclear Information System (INIS)

    McNeil, B.J.; Hanley, J.A.; Funkenstein, H.H.; Wallman, J.

    1983-01-01

    The use of a statistical technique for paired comparisons using receiver operating characteristic (ROC) curves is illustrated by studying the extent to which clinical history altered the interpretation of computed tomographic (CT) examinations of the head. Eighty-nine CT examinations of the head were presented in random order to four readers, first with minimum history (age and sex) and then several weeks later with complete neutrological history as of the time the CT examination had been obtained. Using a paired ROC analysis, a small but significant (p < .05) improvement was detected for the interpretations in the presence of complete history; for readings without history the average area was 94.4% and for readings with history it was 97.7%

  11. Introduction to ROC analysis

    International Nuclear Information System (INIS)

    Kelsey, C.A.; Mettler, F.A.

    1988-01-01

    An elementary introduction to ROC analysis illustrates how ROC curves depend on observer threshold levels and discusses the relation between ROC curve parameters and other measures of observer performance including accuracy sensitivity specificity true positive fraction, true negative fraction, false positive fraction and false negative fraction

  12. Construction of joint confidence regions for the optimal true class fractions of Receiver Operating Characteristic (ROC) surfaces and manifolds.

    Science.gov (United States)

    Bantis, Leonidas E; Nakas, Christos T; Reiser, Benjamin; Myall, Daniel; Dalrymple-Alford, John C

    2017-06-01

    The three-class approach is used for progressive disorders when clinicians and researchers want to diagnose or classify subjects as members of one of three ordered categories based on a continuous diagnostic marker. The decision thresholds or optimal cut-off points required for this classification are often chosen to maximize the generalized Youden index (Nakas et al., Stat Med 2013; 32: 995-1003). The effectiveness of these chosen cut-off points can be evaluated by estimating their corresponding true class fractions and their associated confidence regions. Recently, in the two-class case, parametric and non-parametric methods were investigated for the construction of confidence regions for the pair of the Youden-index-based optimal sensitivity and specificity fractions that can take into account the correlation introduced between sensitivity and specificity when the optimal cut-off point is estimated from the data (Bantis et al., Biomet 2014; 70: 212-223). A parametric approach based on the Box-Cox transformation to normality often works well while for markers having more complex distributions a non-parametric procedure using logspline density estimation can be used instead. The true class fractions that correspond to the optimal cut-off points estimated by the generalized Youden index are correlated similarly to the two-class case. In this article, we generalize these methods to the three- and to the general k-class case which involves the classification of subjects into three or more ordered categories, where ROC surface or ROC manifold methodology, respectively, is typically employed for the evaluation of the discriminatory capacity of a diagnostic marker. We obtain three- and multi-dimensional joint confidence regions for the optimal true class fractions. We illustrate this with an application to the Trail Making Test Part A that has been used to characterize cognitive impairment in patients with Parkinson's disease.

  13. ROC analysis of benefit and limitation in radiotherapy for cancer of the oral cavity

    International Nuclear Information System (INIS)

    Maciejewski, B.; Zajusz, A.

    1993-01-01

    The ROC (receiver operating characteristic) analysis of optimization of radiation treatment of cancer of oral cavity was carried out. Material of 210 patients with squamous cell carcinoma of the oral cavity was included into the study. Based on dose-response curves for tumor and late mucosal reactions, iso-utility curves and optimal k values were estimated. Optimal k values decreased from 0.792 to 0.584 with extension of overall treatment time from 35 to 49 days. This may suggest that the planning of additional dose to compensate tumor clonogens repopulation during prolonged treatment does not improve the therapeutic gain in radiotherapy for cancer of the oral cavity. The ROC is a useful model to estimate the optimal radiation treatment for a given tumor because it is independent of any arbitrary consensus or theoretical assumption. (author) 1 tab., 3 figs., 5 refs

  14. MODELING URBAN DYNAMICS USING RANDOM FOREST: IMPLEMENTING ROC AND TOC FOR MODEL EVALUATION

    Directory of Open Access Journals (Sweden)

    M. Ahmadlou

    2016-06-01

    Full Text Available The importance of spatial accuracy of land use/cover change maps necessitates the use of high performance models. To reach this goal, calibrating machine learning (ML approaches to model land use/cover conversions have received increasing interest among the scholars. This originates from the strength of these techniques as they powerfully account for the complex relationships underlying urban dynamics. Compared to other ML techniques, random forest has rarely been used for modeling urban growth. This paper, drawing on information from the multi-temporal Landsat satellite images of 1985, 2000 and 2015, calibrates a random forest regression (RFR model to quantify the variable importance and simulation of urban change spatial patterns. The results and performance of RFR model were evaluated using two complementary tools, relative operating characteristics (ROC and total operating characteristics (TOC, by overlaying the map of observed change and the modeled suitability map for land use change (error map. The suitability map produced by RFR model showed 82.48% area under curve for the ROC model which indicates a very good performance and highlights its appropriateness for simulating urban growth.

  15. Ideal observer estimation and generalized ROC analysis for computer-aided diagnosis

    International Nuclear Information System (INIS)

    Edwards, Darrin C.

    2004-01-01

    The research presented in this dissertation represents an innovative application of computer-aided diagnosis and signal detection theory to the specific task of early detection of breast cancer in the context of screening mammography. A number of automated schemes have been developed in our laboratory to detect masses and clustered microcalcifications in digitized mammograms, on the one hand, and to classify known lesions as malignant or benign, on the other. The development of fully automated classification schemes is difficult, because the output of a detection scheme will contain false-positive detections in addition to detected malignant and benign lesions, resulting in a three-class classification task. Researchers have so far been unable to extend successful tools for analyzing two-class classification tasks, such as receiver operating characteristic (ROC) analysis, to three-class classification tasks. The goals of our research were to use Bayesian artificial neural networks to estimate ideal observer decision variables to both detect and classify clustered microcalcifications and mass lesions in mammograms, and to derive substantial theoretical results indicating potential avenues of approach toward the three-class classification task. Specifically, we have shown that an ideal observer in an N-class classification task achieves an optimal ROC hypersurface, just as the two-class ideal observer achieves an optimal ROC curve; and that an obvious generalization of a well-known two-class performance metric, the area under the ROC curve, is not useful as a performance metric in classification tasks with more than two classes. This work is significant for three reasons. First, it involves the explicit estimation of feature-based (as opposed to image-based) ideal observer decision variables in the tasks of detecting and classifying mammographic lesions. Second, it directly addresses the three-class classification task of distinguishing malignant lesions, benign

  16. Diagnostic accuracy of the MMPI-2 with the Mexican criminal personality: The ROC curve analysis

    OpenAIRE

    Ampudia Rueda, Amada; Sánchez Crespo, Guadalupe; Jiménez Gómez, Fernando 

    2016-01-01

    The objective of this study is to assess the diagnostic accuracy of the personality of the Mexican criminal with the Minnesota Multiphasic Personality Inventory-2 (MMPI-2). The inventory was administered to 1,740 Mexican participants of which 870 (728 male and 142 female) are prison inmates, processed and/or sentenced for various crimes from various prisons in Mexico City, and the other 870 participants (728 male and 142 female) are not prison inmates. The ROC (Receiver Operating Characterist...

  17. Exploration of analysis methods for diagnostic imaging tests: problems with ROC AUC and confidence scores in CT colonography.

    Science.gov (United States)

    Mallett, Susan; Halligan, Steve; Collins, Gary S; Altman, Doug G

    2014-01-01

    Different methods of evaluating diagnostic performance when comparing diagnostic tests may lead to different results. We compared two such approaches, sensitivity and specificity with area under the Receiver Operating Characteristic Curve (ROC AUC) for the evaluation of CT colonography for the detection of polyps, either with or without computer assisted detection. In a multireader multicase study of 10 readers and 107 cases we compared sensitivity and specificity, using radiological reporting of the presence or absence of polyps, to ROC AUC calculated from confidence scores concerning the presence of polyps. Both methods were assessed against a reference standard. Here we focus on five readers, selected to illustrate issues in design and analysis. We compared diagnostic measures within readers, showing that differences in results are due to statistical methods. Reader performance varied widely depending on whether sensitivity and specificity or ROC AUC was used. There were problems using confidence scores; in assigning scores to all cases; in use of zero scores when no polyps were identified; the bimodal non-normal distribution of scores; fitting ROC curves due to extrapolation beyond the study data; and the undue influence of a few false positive results. Variation due to use of different ROC methods exceeded differences between test results for ROC AUC. The confidence scores recorded in our study violated many assumptions of ROC AUC methods, rendering these methods inappropriate. The problems we identified will apply to other detection studies using confidence scores. We found sensitivity and specificity were a more reliable and clinically appropriate method to compare diagnostic tests.

  18. Part 5: Receiver Operating Characteristic Curve and Area under the Curve

    Directory of Open Access Journals (Sweden)

    Saeed Safari

    2016-04-01

    Full Text Available Multiple diagnostic tools are used by emergency physicians,every day. In addition, new tools are evaluated to obtainmore accurate methods and reduce time or cost of conventionalones. In the previous parts of this educationalseries, we described diagnostic performance characteristicsof diagnostic tests including sensitivity, specificity, positiveand negative predictive values, and likelihood ratios. Thereceiver operating characteristics (ROC curve is a graphicalpresentation of screening characteristics. ROC curve is usedto determine the best cutoff point and compare two or moretests or observers by measuring the area under the curve(AUC. In this part of our educational series, we explain ROCcurve and two methods to determine the best cutoff value.

  19. Diagnostic tests’ decision-making rules based upon analysis of ROC-curves

    Directory of Open Access Journals (Sweden)

    Л. В. Батюк

    2015-10-01

    Full Text Available In this paper we propose the model which substantiates diagnostics decision making based on the analysis of Receiver Operating Characteristic curves (ROC-curves and predicts optimal values of diagnostic indicators of biomedical information. To assess the quality of the test result prediction the standard criteria of the sensitivity and specificity of the model were used. Values of these criteria were calculated for the cases when the sensitivity of the test was greater than specificity by several times, when the number of correct diagnoses was maximal, when the sensitivity of the test was equal to its specificity and the sensitivity of the test was several times greater than the specificity of the test. To assess the significance of the factor characteristics and to compare the prognostic characteristics of models we used mathematical modeling and plotting the ROC-curves. The optimal value of the diagnostic indicator was found to be achieved when the sensitivity of the test is equal to its specificity. The model was adapted to solve the case when the sensitivity of the test is greater than specificity of the test.

  20. Receiver operating characteristics of diagnostic efficacy of resting left ventricular performance (evaluating with a non-imaging ECG gated scintillation detector - nuclear stethoscope)

    International Nuclear Information System (INIS)

    Kotlyarov, E.V.; Reba, R.C.; Lindsay, J.

    1983-01-01

    Receiver operating characteristic (ROC) analysis of left ventricular performance at rest was applied to evaluate diagnostic utility of non-imaging nuclear detector (''Nuclear Stethoscope''), for screening patients with coronary artery disease (CAD). Thirty-one patients without CAD and normal rest and stress radionuclide ventriculography (MUGA) were used as a control group. Another 62 patients with abnormal left ventricular reserve and segmental wall motion abnormalities at rest were also studied. All 93 patients were studied with the Nuclear Stethoscope (30 minutes after conventional MUGA testing) both in beat-to-beat and gated equilibrium modes. ROC analysis showed that along with ejection fraction, stroke and end-diastolic volumes, evaluation of the left ventricular filling phase has a great potential for the identification of patients with a segmental wall motion abnormality and, therefore, significant CAD

  1. Receiver-operating characteristic curves and likelihood ratios: improvements over traditional methods for the evaluation and application of veterinary clinical pathology tests

    DEFF Research Database (Denmark)

    Gardner, Ian A.; Greiner, Matthias

    2006-01-01

    Receiver-operating characteristic (ROC) curves provide a cutoff-independent method for the evaluation of continuous or ordinal tests used in clinical pathology laboratories. The area under the curve is a useful overall measure of test accuracy and can be used to compare different tests (or...... different equipment) used by the same tester, as well as the accuracy of different diagnosticians that use the same test material. To date, ROC analysis has not been widely used in veterinary clinical pathology studies, although it should be considered a useful complement to estimates of sensitivity...... and specificity in test evaluation studies. In addition, calculation of likelihood ratios can potentially improve the clinical utility of such studies because likelihood ratios provide an indication of how the post-test probability changes as a function of the magnitude of the test results. For ordinal test...

  2. Accrual of ROCs LECs and REGOs. Phase 3a: pre-determined entitlements to ROCs for small microgenerators

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report describes a proposed scheme to enable microgenerators in the UK to claim Renewable Obligation Certificates (ROCs) on the basis of predetermined estimates of output rather than data from meters. The aim of the scheme, which has been developed following discussions with representatives of the microgeneration community in the UK, is to make it easier for small generators to access to ROCs and thus encourage householders and smaller commercial/business users to install renewable microgeneration technologies. The work was commissioned as part of the review of the Renewables Obligation. The report considers: background information; the Australian scheme for small generating units; eligibility and entitlements; the operation of the scheme; new procedural and legislative requirements; measures to protect and improve the Renewables Obligation; alterative approaches; scheme benefits; and recommendations. An overview of the scheme's key features is given in the report's executive summary.

  3. Receiver operating characteristic analysis of eyewitness memory: comparing the diagnostic accuracy of simultaneous versus sequential lineups.

    Science.gov (United States)

    Mickes, Laura; Flowe, Heather D; Wixted, John T

    2012-12-01

    A police lineup presents a real-world signal-detection problem because there are two possible states of the world (the suspect is either innocent or guilty), some degree of information about the true state of the world is available (the eyewitness has some degree of memory for the perpetrator), and a decision is made (identifying the suspect or not). A similar state of affairs applies to diagnostic tests in medicine because, in a patient, the disease is either present or absent, a diagnostic test yields some degree of information about the true state of affairs, and a decision is made about the presence or absence of the disease. In medicine, receiver operating characteristic (ROC) analysis is the standard method for assessing diagnostic accuracy. By contrast, in the eyewitness memory literature, this powerful technique has never been used. Instead, researchers have attempted to assess the diagnostic performance of different lineup procedures using methods that cannot identify the better procedure (e.g., by computing a diagnosticity ratio). Here, we describe the basics of ROC analysis, explaining why it is needed and showing how to use it to measure the performance of different lineup procedures. To illustrate the unique advantages of this technique, we also report 3 ROC experiments that were designed to investigate the diagnostic accuracy of simultaneous versus sequential lineups. According to our findings, the sequential procedure appears to be inferior to the simultaneous procedure in discriminating between the presence versus absence of a guilty suspect in a lineup.

  4. Perspective Biological Markers for Autism Spectrum Disorders: Advantages of the Use of Receiver Operating Characteristic Curves in Evaluating Marker Sensitivity and Specificity

    Directory of Open Access Journals (Sweden)

    Provvidenza M. Abruzzo

    2015-01-01

    Full Text Available Autism Spectrum Disorders (ASD are a heterogeneous group of neurodevelopmental disorders. Recognized causes of ASD include genetic factors, metabolic diseases, toxic and environmental factors, and a combination of these. Available tests fail to recognize genetic abnormalities in about 70% of ASD children, where diagnosis is solely based on behavioral signs and symptoms, which are difficult to evaluate in very young children. Although it is advisable that specific psychotherapeutic and pedagogic interventions are initiated as early as possible, early diagnosis is hampered by the lack of nongenetic specific biological markers. In the past ten years, the scientific literature has reported dozens of neurophysiological and biochemical alterations in ASD children; however no real biomarker has emerged. Such literature is here reviewed in the light of Receiver Operating Characteristic (ROC analysis, a very valuable statistical tool, which evaluates the sensitivity and the specificity of biomarkers to be used in diagnostic decision making. We also apply ROC analysis to some of our previously published data and discuss the increased diagnostic value of combining more variables in one ROC curve analysis. We also discuss the use of biomarkers as a tool for advancing our understanding of nonsyndromic ASD.

  5. ROC generated thresholds for field-assessed aerobic fitness related to body size and cardiometabolic risk in schoolchildren.

    Directory of Open Access Journals (Sweden)

    Lynne M Boddy

    Full Text Available OBJECTIVES: 1. to investigate whether 20 m multi-stage shuttle run performance (20mSRT, an indirect measure of aerobic fitness, could discriminate between healthy and overweight status in 9-10.9 yr old schoolchildren using Receiver Operating Characteristic (ROC analysis; 2. Investigate if cardiometabolic risk differed by aerobic fitness group by applying the ROC cut point to a second, cross-sectional cohort. DESIGN: Analysis of cross-sectional data. PARTICIPANTS: 16,619 9-10.9 year old participants from SportsLinx project and 300 11-13.9 year old participants from the Welsh Schools Health and Fitness Study. OUTCOME MEASURES: SportsLinx; 20mSRT, body mass index (BMI, waist circumference, subscapular and superilliac skinfold thicknesses. Welsh Schools Health and Fitness Study; 20mSRT performance, waist circumference, and clustered cardiometabolic risk. ANALYSES: Three ROC curve analyses were completed, each using 20mSRT performance with ROC curve 1 related to BMI, curve 2 was related to waist circumference and 3 was related to skinfolds (estimated % body fat. These were repeated for both girls and boys. The mean of the three aerobic fitness thresholds was retained for analysis. The thresholds were subsequently applied to clustered cardiometabolic risk data from the Welsh Schools study to assess whether risk differed by aerobic fitness group. RESULTS: The diagnostic accuracy of the ROC generated thresholds was higher than would be expected by chance (all models AUC >0.7. The mean thresholds were 33 and 25 shuttles for boys and girls respectively. Participants classified as 'fit' had significantly lower cardiometabolic risk scores in comparison to those classed as unfit (p<0.001. CONCLUSION: The use of the ROC generated cut points by health professionals, teachers and coaches may provide the opportunity to apply population level 'risk identification and stratification' processes and plan for "at-risk" children to be referred onto intervention

  6. bcROCsurface: an R package for correcting verification bias in estimation of the ROC surface and its volume for continuous diagnostic tests.

    Science.gov (United States)

    To Duc, Khanh

    2017-11-18

    Receiver operating characteristic (ROC) surface analysis is usually employed to assess the accuracy of a medical diagnostic test when there are three ordered disease status (e.g. non-diseased, intermediate, diseased). In practice, verification bias can occur due to missingness of the true disease status and can lead to a distorted conclusion on diagnostic accuracy. In such situations, bias-corrected inference tools are required. This paper introduce an R package, named bcROCsurface, which provides utility functions for verification bias-corrected ROC surface analysis. The shiny web application of the correction for verification bias in estimation of the ROC surface analysis is also developed. bcROCsurface may become an important tool for the statistical evaluation of three-class diagnostic markers in presence of verification bias. The R package, readme and example data are available on CRAN. The web interface enables users less familiar with R to evaluate the accuracy of diagnostic tests, and can be found at http://khanhtoduc.shinyapps.io/bcROCsurface_shiny/ .

  7. DTI measures identify mild and moderate TBI cases among patients with complex health problems: A receiver operating characteristic analysis of U.S. veterans.

    Science.gov (United States)

    Main, Keith L; Soman, Salil; Pestilli, Franco; Furst, Ansgar; Noda, Art; Hernandez, Beatriz; Kong, Jennifer; Cheng, Jauhtai; Fairchild, Jennifer K; Taylor, Joy; Yesavage, Jerome; Wesson Ashford, J; Kraemer, Helena; Adamson, Maheen M

    2017-01-01

    Standard MRI methods are often inadequate for identifying mild traumatic brain injury (TBI). Advances in diffusion tensor imaging now provide potential biomarkers of TBI among white matter fascicles (tracts). However, it is still unclear which tracts are most pertinent to TBI diagnosis. This study ranked fiber tracts on their ability to discriminate patients with and without TBI. We acquired diffusion tensor imaging data from military veterans admitted to a polytrauma clinic (Overall n  = 109; Age: M  = 47.2, SD  = 11.3; Male: 88%; TBI: 67%). TBI diagnosis was based on self-report and neurological examination. Fiber tractography analysis produced 20 fiber tracts per patient. Each tract yielded four clinically relevant measures (fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity). We applied receiver operating characteristic (ROC) analyses to identify the most diagnostic tract for each measure. The analyses produced an optimal cutpoint for each tract. We then used kappa coefficients to rate the agreement of each cutpoint with the neurologist's diagnosis. The tract with the highest kappa was most diagnostic. As a check on the ROC results, we performed a stepwise logistic regression on each measure using all 20 tracts as predictors. We also bootstrapped the ROC analyses to compute the 95% confidence intervals for sensitivity, specificity, and the highest kappa coefficients. The ROC analyses identified two fiber tracts as most diagnostic of TBI: the left cingulum (LCG) and the left inferior fronto-occipital fasciculus (LIF). Like ROC, logistic regression identified LCG as most predictive for the FA measure but identified the right anterior thalamic tract (RAT) for the MD, RD, and AD measures. These findings are potentially relevant to the development of TBI biomarkers. Our methods also demonstrate how ROC analysis may be used to identify clinically relevant variables in the TBI population.

  8. Statistical properties of a utility measure of observer performance compared to area under the ROC curve

    Science.gov (United States)

    Abbey, Craig K.; Samuelson, Frank W.; Gallas, Brandon D.; Boone, John M.; Niklason, Loren T.

    2013-03-01

    The receiver operating characteristic (ROC) curve has become a common tool for evaluating diagnostic imaging technologies, and the primary endpoint of such evaluations is the area under the curve (AUC), which integrates sensitivity over the entire false positive range. An alternative figure of merit for ROC studies is expected utility (EU), which focuses on the relevant region of the ROC curve as defined by disease prevalence and the relative utility of the task. However if this measure is to be used, it must also have desirable statistical properties keep the burden of observer performance studies as low as possible. Here, we evaluate effect size and variability for EU and AUC. We use two observer performance studies recently submitted to the FDA to compare the EU and AUC endpoints. The studies were conducted using the multi-reader multi-case methodology in which all readers score all cases in all modalities. ROC curves from the study were used to generate both the AUC and EU values for each reader and modality. The EU measure was computed assuming an iso-utility slope of 1.03. We find mean effect sizes, the reader averaged difference between modalities, to be roughly 2.0 times as big for EU as AUC. The standard deviation across readers is roughly 1.4 times as large, suggesting better statistical properties for the EU endpoint. In a simple power analysis of paired comparison across readers, the utility measure required 36% fewer readers on average to achieve 80% statistical power compared to AUC.

  9. ROC analysis in gammagraphic diagnosis of hepatic cirrhosis

    International Nuclear Information System (INIS)

    Hdez-Armas, J.; Allende, A.; Alarco, R.; Panero, J.; Oton, C.

    1982-01-01

    An application of the ROC statistical method is described on a sample of 161 patients who underwent hepatic gammagraphy and biopsies obtained by laparsocopy, and of whom 90 were found to have hepatic cirrhosis according to pathological anatomy. Five decision thresholds have been established in the elaboration of the gammagraphic diagnosis of cirrhosis. The true positive fraction (TPF) and false positive fraction (FPF) of these five thresholds are shown on an ordinate axis and an ROC curve is obtained. By means of a simplified cost-benefit analysis the optimal point of operation for this type of diagnosis is determined on this curve, according to which the diagnosis of cirrhosis should be considered positive when alterations in the size of the liver and distribution of the isotope in the liver are found simultaneously with splenomegaly. (orig.)

  10. Clinical diagnostic accuracy of acute colonic diverticulitis in patients admitted with acute abdominal pain, a receiver operating characteristic curve analysis.

    Science.gov (United States)

    Jamal Talabani, A; Endreseth, B H; Lydersen, S; Edna, T-H

    2017-01-01

    The study investigated the capability of clinical findings, temperature, C-reactive protein (CRP), and white blood cell (WBC) count to discern patients with acute colonic diverticulitis from all other patients admitted with acute abdominal pain. The probability of acute diverticulitis was assessed by the examining doctor, using a scale from 0 (zero probability) to 10 (100 % probability). Receiver operating characteristic (ROC) curves were used to assess the clinical diagnostic accuracy of acute colonic diverticulitis in patients admitted with acute abdominal pain. Of 833 patients admitted with acute abdominal pain, 95 had acute colonic diverticulitis. ROC curve analysis gave an area under the ROC curve (AUC) of 0.95 (CI 0.92 to 0.97) for ages patients. Separate analysis showed an AUC = 0.83 (CI 0.80 to 0.86) of CRP alone. White blood cell count and temperature were almost useless to discriminate acute colonic diverticulitis from other types of acute abdominal pain, AUC = 0.59 (CI 0.53 to 0.65) for white blood cell count and AUC = 0.57 (0.50 to 0.63) for temperature, respectively. This prospective study demonstrates that standard clinical evaluation by non-specialist doctors based on history, physical examination, and initial blood tests on admission provides a high degree of diagnostic precision in patients with acute colonic diverticulitis.

  11. Diagnostic accuracy of quantitative 99mTc-MIBI scintimammography according to ROC curve analysis

    International Nuclear Information System (INIS)

    Kim, J. H.; Lee, H. K.; Seo, J. W.; Cho, N. S.; Cha, K. H.; Lee, T. H.

    1998-01-01

    99mTc-sestamibi scintimammography (SMM) has been shown to be a useful diagnostic test in the detection of breast cancer and the receiver operating characteristic (ROC) curve analysis provides detailed information of a diagnostic test. The purpose of this study was to evaluate the feasibility and efficacy of quantitative indices of SMM in the detection of malignant breast lesions according to ROC analysis. Prone anterior, lateral planar and supine SPECT imagings were performed on 75 female patients (mean age=43.4 yr) with breast mass (size≥0.8cm) after intravenous injection of 20-30 mCi 99mTc-sestamibi. 45 Malignant (Invasive ductal ca(36), Inv lobular ca(5), Inv duc + lob (1), Inv tubular ca (3)) and 30 benign (fibroadenoma (13), fib cyst(12), Fat necrosis(3), papilloma(1), paraffinoma (1)) lesions were histologically proven. Data were analyzed by creating three regions of interest (ROIs) over designated areas: lesion, normal breast and right chest wall. Lesion to normal (L/NL) and lesion to chest wall (L/CW) ratios were calculated for each patient both on the planar and SPECT. The area under the ROC curve (AUC) was calculated and compared among four semiquantitative indices and an average scintimammographic index (SMM(mean)) from arithmatic mean. ROC curve analysis revealed planar L/N, SPECT L/N and L/CW ratios provide comparable better diagnostic accuracies for detection of breast cancer than planar L/CW ratio (p<0.05), respectively. For quantitative SMM of 75 lesions, malignancy rate was 60%, and Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value and Accuracy were 0.78, 0.77, 0.84, 0.72 and 0.77, respectively. Quantitative SMM is an useful objective method for differentiating malignant from benign breast lesions

  12. Diagnostic accuracy of quantitative 99mTc-MIBI scintimammography according to ROC curve analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. H.; Lee, H. K.; Seo, J. W.; Cho, N. S.; Cha, K. H.; Lee, T. H. [Gachon Medical College, Gil Medical Center, Inchon (Korea, Republic of)

    1998-07-01

    99mTc-sestamibi scintimammography (SMM) has been shown to be a useful diagnostic test in the detection of breast cancer and the receiver operating characteristic (ROC) curve analysis provides detailed information of a diagnostic test. The purpose of this study was to evaluate the feasibility and efficacy of quantitative indices of SMM in the detection of malignant breast lesions according to ROC analysis. Prone anterior, lateral planar and supine SPECT imagings were performed on 75 female patients (mean age=43.4 yr) with breast mass (size{>=}0.8cm) after intravenous injection of 20-30 mCi 99mTc-sestamibi. 45 Malignant (Invasive ductal ca(36), Inv lobular ca(5), Inv duc + lob (1), Inv tubular ca (3)) and 30 benign (fibroadenoma (13), fib cyst(12), Fat necrosis(3), papilloma(1), paraffinoma (1)) lesions were histologically proven. Data were analyzed by creating three regions of interest (ROIs) over designated areas: lesion, normal breast and right chest wall. Lesion to normal (L/NL) and lesion to chest wall (L/CW) ratios were calculated for each patient both on the planar and SPECT. The area under the ROC curve (AUC) was calculated and compared among four semiquantitative indices and an average scintimammographic index (SMM(mean)) from arithmatic mean. ROC curve analysis revealed planar L/N, SPECT L/N and L/CW ratios provide comparable better diagnostic accuracies for detection of breast cancer than planar L/CW ratio (p<0.05), respectively. For quantitative SMM of 75 lesions, malignancy rate was 60%, and Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value and Accuracy were 0.78, 0.77, 0.84, 0.72 and 0.77, respectively. Quantitative SMM is an useful objective method for differentiating malignant from benign breast lesions.

  13. Evaluation of the optimal diagnostic criteria for regional lymph node metastases of lung cancer on MR imaging by receiver operating characteristic curve

    International Nuclear Information System (INIS)

    Iwai, Naomichi; Yamaguchi, Yutaka

    1991-01-01

    MRI was performed in 78 primary lung cancer cases to evaluate the optimal diagnostic criteria for regional lymph node metastases. Receiver operating characteristic (ROC) curve analysis for 262 lymph nodes of the hilar and mediastinal regions showed that the optimal size criterion is 10 mm in the mean axis of nodal diameter. Employing this criterion, the diagnostic rates for hilar and mediastinal lymph nodes had a sensitivity of 75%, a specificity of 82%, and an overall accuracy of 79%. However, the diagnostic rates for subaortic, paraaortic, and hilar lymph nodes using the same criterion showed lower specificities than those for other nodes. It was suggested that evaluation by coronal section made the diagnosis for subaortic lymph nodes more precise. In the ROC curve analysis for each histologic type, it was thought that the optimal criterion for adenocarcinoma was 10 mm in the mean axis, and that the criteria for squamous cell carcinoma were 11 mm in the mean axis and 10 mm in the sort axis. (author)

  14. Interrelationships Between Receiver/Relative Operating Characteristics Display, Binomial, Logit, and Bayes' Rule Probability of Detection Methodologies

    Science.gov (United States)

    Generazio, Edward R.

    2014-01-01

    Unknown risks are introduced into failure critical systems when probability of detection (POD) capabilities are accepted without a complete understanding of the statistical method applied and the interpretation of the statistical results. The presence of this risk in the nondestructive evaluation (NDE) community is revealed in common statements about POD. These statements are often interpreted in a variety of ways and therefore, the very existence of the statements identifies the need for a more comprehensive understanding of POD methodologies. Statistical methodologies have data requirements to be met, procedures to be followed, and requirements for validation or demonstration of adequacy of the POD estimates. Risks are further enhanced due to the wide range of statistical methodologies used for determining the POD capability. Receiver/Relative Operating Characteristics (ROC) Display, simple binomial, logistic regression, and Bayes' rule POD methodologies are widely used in determining POD capability. This work focuses on Hit-Miss data to reveal the framework of the interrelationships between Receiver/Relative Operating Characteristics Display, simple binomial, logistic regression, and Bayes' Rule methodologies as they are applied to POD. Knowledge of these interrelationships leads to an intuitive and global understanding of the statistical data, procedural and validation requirements for establishing credible POD estimates.

  15. Clinical relevance of the ROC and free-response paradigms for comparing imaging system efficacies

    International Nuclear Information System (INIS)

    Chakraborty, D. P.

    2010-01-01

    Observer performance studies are widely used to assess medical imaging systems. Unlike technical/engineering measurements observer performance include the entire imaging chain and the radiologist. However, the widely used receiver operating characteristic (ROC) method ignores lesion localisation information. The free-response ROC (FROC) method uses the location information to appropriately reward or penalise correct or incorrect localizations, respectively. This paper describes a method for improving the clinical relevance of FROC studies. The method consists of assigning appropriate risk values to the different lesions that may be present on a single image. A high-risk lesion is one that is critical to detect and act upon, and is assigned a higher risk value than a low-risk lesion, one that is relatively innocuous. Instead of simply counting the number of lesions that are detected, as is done in conventional FROC analysis, a risk-weighted count is used. This has the advantage of rewarding detections of high-risk lesions commensurately more than detections of lower risk lesions. Simulations were used to demonstrate that the new method, termed case-based analysis, results in a higher figure of merit for an expert who detects more high-risk lesions than a naive observer who detects more low-risk lesions, even though both detect the same total number of lesions. Conventional free-response analysis is unable to distinguish between the two types of observers. This paper also comments on the issue of clinical relevance of ROC analysis vs. FROC for tasks that involve lesion localisation. (authors)

  16. Accrual of ROCs LECs and REGOs

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the findings of a project to identify the technical and administrative difficulties experienced by microgenerators in accessing the benefits of Renewables Obligation Certificates (ROCs), Levy Exemption Certificates (LECs) and Renewable Electricity Guarantees of Origin (REGO). These include cost, administrative complexity and financial risk. Changes allowing bulk processing, meter data provision, sell and buyback contracts, and alignment of ROCs, LECs and REGOs are discussed as well as making the schemes more customer friendly. The background to the project is traced, and an overview of the processes associated with gaining ROCs, LECs and REGOs is presented.

  17. Multi-probe-based resonance-frequency electrical impedance spectroscopy for detection of suspicious breast lesions: improving performance using partial ROC optimization

    Science.gov (United States)

    Lederman, Dror; Zheng, Bin; Wang, Xingwei; Wang, Xiao Hui; Gur, David

    2011-03-01

    We have developed a multi-probe resonance-frequency electrical impedance spectroscope (REIS) system to detect breast abnormalities. Based on assessing asymmetry in REIS signals acquired between left and right breasts, we developed several machine learning classifiers to classify younger women (i.e., under 50YO) into two groups of having high and low risk for developing breast cancer. In this study, we investigated a new method to optimize performance based on the area under a selected partial receiver operating characteristic (ROC) curve when optimizing an artificial neural network (ANN), and tested whether it could improve classification performance. From an ongoing prospective study, we selected a dataset of 174 cases for whom we have both REIS signals and diagnostic status verification. The dataset includes 66 "positive" cases recommended for biopsy due to detection of highly suspicious breast lesions and 108 "negative" cases determined by imaging based examinations. A set of REIS-based feature differences, extracted from the two breasts using a mirror-matched approach, was computed and constituted an initial feature pool. Using a leave-one-case-out cross-validation method, we applied a genetic algorithm (GA) to train the ANN with an optimal subset of features. Two optimization criteria were separately used in GA optimization, namely the area under the entire ROC curve (AUC) and the partial area under the ROC curve, up to a predetermined threshold (i.e., 90% specificity). The results showed that although the ANN optimized using the entire AUC yielded higher overall performance (AUC = 0.83 versus 0.76), the ANN optimized using the partial ROC area criterion achieved substantially higher operational performance (i.e., increasing sensitivity level from 28% to 48% at 95% specificity and/ or from 48% to 58% at 90% specificity).

  18. Item Strength Influences Source Confidence and Alters Source Memory zROC Slopes

    Science.gov (United States)

    Starns, Jeffrey J.; Ksander, John C.

    2016-01-01

    Increasing the number of study trials creates a crossover pattern in source memory zROC slopes; that is, the slope is either below or above 1 depending on which source receives stronger learning. This pattern can be produced if additional learning affects memory processes such as the relative contribution of recollection and familiarity to source…

  19. ROC-king onwards: intraepithelial lymphocyte counts, distribution & role in coeliac disease mucosal interpretation.

    Science.gov (United States)

    Rostami, Kamran; Marsh, Michael N; Johnson, Matt W; Mohaghegh, Hamid; Heal, Calvin; Holmes, Geoffrey; Ensari, Arzu; Aldulaimi, David; Bancel, Brigitte; Bassotti, Gabrio; Bateman, Adrian; Becheanu, Gabriel; Bozzola, Anna; Carroccio, Antonio; Catassi, Carlo; Ciacci, Carolina; Ciobanu, Alexandra; Danciu, Mihai; Derakhshan, Mohammad H; Elli, Luca; Ferrero, Stefano; Fiorentino, Michelangelo; Fiorino, Marilena; Ganji, Azita; Ghaffarzadehgan, Kamran; Going, James J; Ishaq, Sauid; Mandolesi, Alessandra; Mathews, Sherly; Maxim, Roxana; Mulder, Chris J; Neefjes-Borst, Andra; Robert, Marie; Russo, Ilaria; Rostami-Nejad, Mohammad; Sidoni, Angelo; Sotoudeh, Masoud; Villanacci, Vincenzo; Volta, Umberto; Zali, Mohammad R; Srivastava, Amitabh

    2017-12-01

    Counting intraepithelial lymphocytes (IEL) is central to the histological diagnosis of coeliac disease (CD), but no definitive 'normal' IEL range has ever been published. In this multicentre study, receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off between normal and CD (Marsh III lesion) duodenal mucosa, based on IEL counts on >400 mucosal biopsy specimens. The study was designed at the International Meeting on Digestive Pathology, Bucharest 2015. Investigators from 19 centres, eight countries of three continents, recruited 198 patients with Marsh III histology and 203 controls and used one agreed protocol to count IEL/100 enterocytes in well-oriented duodenal biopsies. Demographic and serological data were also collected. The mean ages of CD and control groups were 45.5 (neonate to 82) and 38.3 (2-88) years. Mean IEL count was 54±18/100 enterocytes in CD and 13±8 in normal controls (p=0.0001). ROC analysis indicated an optimal cut-off point of 25 IEL/100 enterocytes, with 99% sensitivity, 92% specificity and 99.5% area under the curve. Other cut-offs between 20 and 40 IEL were less discriminatory. Additionally, there was a sufficiently high number of biopsies to explore IEL counts across the subclassification of the Marsh III lesion. Our ROC curve analyses demonstrate that for Marsh III lesions, a cut-off of 25 IEL/100 enterocytes optimises discrimination between normal control and CD biopsies. No differences in IEL counts were found between Marsh III a, b and c lesions. There was an indication of a continuously graded dose-response by IEL to environmental (gluten) antigenic influence. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  20. Plateletpheresis efficiency and mathematical correction of software-derived platelet yield prediction: A linear regression and ROC modeling approach.

    Science.gov (United States)

    Jaime-Pérez, José Carlos; Jiménez-Castillo, Raúl Alberto; Vázquez-Hernández, Karina Elizabeth; Salazar-Riojas, Rosario; Méndez-Ramírez, Nereida; Gómez-Almaguer, David

    2017-10-01

    Advances in automated cell separators have improved the efficiency of plateletpheresis and the possibility of obtaining double products (DP). We assessed cell processor accuracy of predicted platelet (PLT) yields with the goal of a better prediction of DP collections. This retrospective proof-of-concept study included 302 plateletpheresis procedures performed on a Trima Accel v6.0 at the apheresis unit of a hematology department. Donor variables, software predicted yield and actual PLT yield were statistically evaluated. Software prediction was optimized by linear regression analysis and its optimal cut-off to obtain a DP assessed by receiver operating characteristic curve (ROC) modeling. Three hundred and two plateletpheresis procedures were performed; in 271 (89.7%) occasions, donors were men and in 31 (10.3%) women. Pre-donation PLT count had the best direct correlation with actual PLT yield (r = 0.486. P Simple correction derived from linear regression analysis accurately corrected this underestimation and ROC analysis identified a precise cut-off to reliably predict a DP. © 2016 Wiley Periodicals, Inc.

  1. Smooth time-dependent receiver operating characteristic curve estimators.

    Science.gov (United States)

    Martínez-Camblor, Pablo; Pardo-Fernández, Juan Carlos

    2018-03-01

    The receiver operating characteristic curve is a popular graphical method often used to study the diagnostic capacity of continuous (bio)markers. When the considered outcome is a time-dependent variable, two main extensions have been proposed: the cumulative/dynamic receiver operating characteristic curve and the incident/dynamic receiver operating characteristic curve. In both cases, the main problem for developing appropriate estimators is the estimation of the joint distribution of the variables time-to-event and marker. As usual, different approximations lead to different estimators. In this article, the authors explore the use of a bivariate kernel density estimator which accounts for censored observations in the sample and produces smooth estimators of the time-dependent receiver operating characteristic curves. The performance of the resulting cumulative/dynamic and incident/dynamic receiver operating characteristic curves is studied by means of Monte Carlo simulations. Additionally, the influence of the choice of the required smoothing parameters is explored. Finally, two real-applications are considered. An R package is also provided as a complement to this article.

  2. Reliability in NDT: ROC study of radiographic weld inspections

    International Nuclear Information System (INIS)

    Nockemann, C.; Heidt, H.; Thomsen, N.

    1991-01-01

    The complexity of modern nondestructive testing (NDT) equipment as well as the demand for high reliability in many industries makes it necessary to have a tool to assess different NDT techniques and devices quickly. As for cost benefit considerations, a measure of accuracy has to include not only the number of correctly detected defects but also the corresponding number of false indications. In order to satisfy a variety of security demands this ratio of true and false indications must be known for a wide range of defect dimensions to be included in the defect count. This information will be provided by only one ROC (relative operating characteristic) study of inspection data using the rating confidence method. An expanded ROC version also yields an assessment of the accuracy of the defect classification and of the correctness of the indicated defect importance. All these measures of performance can also be called up for each individual inspector. For demonstrating the power of the method it is applied to ascertain the difference in detection performance of three distinct experimental modalities in the radiographic testing of welded joints. In order to be capable of drawing conclusions reliably, the study is completed by statistical significance tests. The paper shows the usefulness of ROC for performance assessment in NDT and gives an illustration of what can be done with which effort. (Author)

  3. Análise TG-ROC de testes de imunofluorescência no diagnóstico de leishmaniose visceral canina Análisis TG-ROC de pruebas de inmunofluorescencia en el diagnóstico de leishmaniasis visceral canina TG-ROC analysis of immunofluorescence assays in canine visceral leishmaniasis diagnosis

    Directory of Open Access Journals (Sweden)

    Rita Maria da Silva

    2009-12-01

    Full Text Available OBJETIVO: Analisar a acurácia do diagnóstico de dois protocolos de imunofluorescência indireta para leishmaniose visceral canina. MÉTODOS: Cães provenientes de inquérito soroepidemiológico realizado em área endêmica nos municípios de Araçatuba e de Andradina, na região noroeste do estado de São Paulo, em 2003, e área não endêmica da região metropolitana de São Paulo, foram utilizados para avaliar comparativamente dois protocolos da reação de imunofluorescência indireta (RIFI para leishmaniose: um utilizando antígeno heterólogo Leishmania major (RIFI-BM e outro utilizando antígeno homólogo Leishmania chagasi (RIFI-CH. Para estimar acurácia utilizou-se a análise two-graph receiver operating characteristic (TG-ROC. A análise TG-ROC comparou as leituras da diluição 1:20 do antígeno homólogo (RIFI-CH, consideradas como teste referência, com as diluições da RIFI-BM (antígeno heterólogo. RESULTADOS: A diluição 1:20 do teste RIFI-CH apresentou o melhor coeficiente de contingência (0,755 e a maior força de associação entre as duas variáveis estudadas (qui-quadrado=124,3, sendo considerada a diluição-referência do teste nas comparações com as diferentes diluições do teste RIFI-BM. Os melhores resultados do RIFI-BM foram obtidos na diluição 1:40, com melhor coeficiente de contingência (0,680 e maior força de associação (qui-quadrado=80,8. Com a mudança do ponto de corte sugerido nesta análise para a diluição 1:40 da RIFI-BM, o valor do parâmetro especificidade aumentou de 57,5% para 97,7%, embora a diluição 1:80 tivesse apresentado a melhor estimativa para sensibilidade (80,2% com o novo ponto de corte. CONCLUSÕES: A análise TG-ROC pode fornecer importantes informações sobre os testes de diagnósticos, além de apresentar sugestões sobre pontos de cortes que podem melhorar as estimativas de sensibilidade e especificidade do teste, e avaliá-los a luz do melhor custo

  4. Progress in evaluation of human observer visual detection performance using the ROC curve approach

    International Nuclear Information System (INIS)

    Metz, C.E.; Starr, S.J.; Lusted, L.B.; Rossmann, K.

    1976-01-01

    The ROC approach to analysis of human observer detection performance as playing a key role in elucidation the relationships among the physical parameters of an imaging operation, the ability of a human observer to use the image to make decisions regarding the state of health or disease in a medical diagnostic situation, and the medical and social utility of those decisions, was studied. The conventional ROC curve describing observer performance in simple detection tasks can be used to predict observer performance in complex detection tasks. The conventional ROC curve thus provides a description of observer detection performance which is useful in situations more relevant clinically than those for which it is measured. Similar predictions regarding observer performance in identification and recognition tasks are currently being sought. The ROC curve can be used to relate signal detectability to various measures of the diagnostic and social benefit derived from a medical imaging procedure. These relationships provide a means for assessing the relative desirability of alternative diagnostic techniques and can be used to evaluate combinations of diagnostic studies

  5. The diagnosis of small solitary pulmonary nodule: comparison of standard and inverse digital images on a high resolution monitor using ROC analysis

    International Nuclear Information System (INIS)

    Choi, Byeong Kyoo; Lee, In Sun; Seo, Joon Beom; Lee, Jin Seong; Song, Koun Sik; Lim, Tae Hwan

    2002-01-01

    To study the impact of inversion of soft-copy chest radiographs on the detection of small solitary pulmonary nodules using a high-resolution monitor. The study group consisted of 80 patients who had undergone posterior chest radiography; 40 had a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 were control subjects. Standard and inverse digital images using the inversion tool on a PACS system were displayed on high-resolution monitors (2048x2560x8 bit). Ten radiologists were requested to rank each image using a five-point scale (1=definitely negative, 3=equivocal or indeterminate, 5=definite nodule), and the data were interpreted using receiver operating characteristic (ROC) analysis. The area under the ROC curve for pooled data of standard image sets was significantly larger than that of inverse image sets (0.8893 and 0.8095, respectively; p 0.05). For detecting small solitary pulmonary nodules, inverse digital images were significantly inferior to standard digital images

  6. ROC evaluation of SPECT myocardial lesion detectability with and without single iteration non-uniform Chang attenuation compensation using an anthropomorphic female phantom

    International Nuclear Information System (INIS)

    Jang, S.; Jaszczak, R.J.; Duke Univ. Medical Center, Durham, NC; Gilland, D.R.; Turkington, T.G.; Coleman, R.E.; Tsui, B.M.W.; Metz, C.E.

    1998-01-01

    The purpose of this work was to evaluate lesion detectability with and without nonuniform attenuation compensation (AC) in myocardial perfusion SPECT imaging in women using an anthropomorphic phantom and receiver operating characteristics (ROC) methodology. Breast attenuation causes artifacts in reconstructed images and may increase the difficulty of diagnosis of myocardial perfusion imaging in women. The null hypothesis tested using the ROC study was that nonuniform AC does not change the lesion detectability in myocardial perfusion SPECT imaging in women. The authors used a filtered backprojection (FBP) reconstruction algorithm and Chang's single iteration method for AC. In conclusion, with the proposed myocardial defect model nuclear medicine physicians demonstrated no significant difference for the detection of the anterior wall defect; however, a greater accuracy for the detection of the inferior wall defect was observed without nonuniform AC than with it. Medical physicists did not demonstrate any statistically significant difference in defect detection accuracy with or without nonuniform AC in the female phantom

  7. Application of three-class ROC analysis to task-based image quality assessment of simultaneous dual-isotope myocardial perfusion SPECT (MPS).

    Science.gov (United States)

    He, Xin; Song, Xiyun; Frey, Eric C

    2008-11-01

    The diagnosis of cardiac disease using dual-isotope myocardial perfusion SPECT (MPS) is based on the defect status in both stress and rest images, and can be modeled as a three-class task of classifying patients as having no, reversible, or fixed perfusion defects. Simultaneous acquisition protocols for dual-isotope MPS imaging have gained much interest due to their advantages including perfect registration of the (201)Tl and (99m)Tc images in space and time, increased patient comfort, and higher clinical throughput. As a result of simultaneous acquisition, however, crosstalk contamination, where photons emitted by one isotope contribute to the image of the other isotope, degrades image quality. Minimizing the crosstalk is important in obtaining the best possible image quality. One way to minimize the crosstalk is to optimize the injected activity of the two isotopes by considering the three-class nature of the diagnostic problem. To effectively do so, we have previously developed a three-class receiver operating characteristic (ROC) analysis methodology that extends and unifies the decision theoretic, linear discriminant analysis, and psychophysical foundations of binary ROC analysis in a three-class paradigm. In this work, we applied the proposed three-class ROC methodology to the assessment of the image quality of simultaneous dual-isotope MPS imaging techniques and the determination of the optimal injected activity combination. In addition to this application, the rapid development of diagnostic imaging techniques has produced an increasing number of clinical diagnostic tasks that involve not only disease detection, but also disease characterization and are thus multiclass tasks. This paper provides a practical example of the application of the proposed three-class ROC analysis methodology to medical problems.

  8. THE ROLE AND PLACE OF LOGISTIC REGRESSION AND ROC ANALYSIS IN SOLVING MEDICAL DIAGNOSTIC TASK

    Directory of Open Access Journals (Sweden)

    S. G. Grigoryev

    2016-01-01

    Full Text Available Diagnostics, equally with  prevention and  treatment, is a basis of medical science and practice. For its history the medicine  has accumulated a great variety  of diagnostic methods for different diseases and  pathologic conditions. Nevertheless, new  tests,  methods and  tools are being  developed and recommended to application nowadays. Such  indicators as sensitivity and  specificity which  are defined on the basis  of fourfold contingency  tables   construction or  ROC-analysis method with  ROC  – curve  modelling (Receiver operating characteristic are used  as the  methods to estimate the  diagnostic capability. Fourfold  table  is used  with  the purpose to estimate the method which confirms or denies the diagnosis, i.e. a quality indicator. ROC-curve, being a graph, allows making the estimation of model  quality by subdivision of two classes  on the  basis  of identifying the  point  of cutting off a continuous or discrete quantitative attribute.The method of logistic regression technique is introduced as a tool to develop some  mathematical-statistical forecasting model  of probability of the event the researcher is interested in if there are two possible variants of the outcome. The method of ROC-analysis is chosen and described in detail as a tool to estimate the  model  quality. The capabilities of the named methods are demonstrated by a real example of creation  and  efficiency estimation (sensitivity and  specificity of a forecasting model  of probability of complication development in the form of pyodermatitis in children with  atopic dermatitis.

  9. ROC Analysis of Diagnostic Performance in Liver Scan

    International Nuclear Information System (INIS)

    Lee, Myung Chul; Moon, Dyuk Hyuk; Koh, Chang Soon; Matumoto, Toru; Tateno, Yukio

    1988-01-01

    To evaluate diagnostic accuracy of liver scintigraphy we analysed liver scans of 143 normal and 258 patients with various liver diseases. Three ROC curves for SOL, liver cirrhosis and diffuse liver disease were fitted using rating methods and areas under the ROC curves and their standard errors were calculated by the trapezoidal rule and the variance of the Wilcoxon statistic suggested by McNeil. We compared these results with that of National Institute of Radiological Science in Japan. 1) The sensitivity of liver scintigraphy was 74.2% in SOL, 71.8% in liver cirrhosis and 34.8% in diffuse liver disease. The specificity was 96.0% in SOL, 94.2% in liver cirrhosis and 87.6% in diffuse liver disease. 2) ROC curves of SOL and liver cirrhosis approached the upper left-hand corner closer than that of diffuse liver disease. Area (± standard error) under the ROC curve was 0.868±0.024 in SOL and 0.867±0.028 in liver cirrhosis. These were significantly higher than 0.658±0.043 in diffuse liver disease. 3) There was no interobserver difference in terms of ROC curves. But low sensitivity and high specificity of authors' SOL diagnosis suggested we used more strict decision threshold.

  10. The validity of using ROC software for analysing visual grading characteristics data: an investigation based on the novel software VGC analyzer

    International Nuclear Information System (INIS)

    Hansson, Jonny; Maansson, Lars Gunnar; Baath, Magnus

    2016-01-01

    The purpose of the present work was to investigate the validity of using single-reader-adapted receiver operating characteristics (ROC) software for analysis of visual grading characteristics (VGC) data. VGC data from four published VGC studies on optimisation of X-ray examinations, previously analysed using ROCFIT, were reanalysed using a recently developed software dedicated to VGC analysis (VGC Analyzer), and the outcomes [the mean and 95 % confidence interval (CI) of the area under the VGC curve (AUC VGC ) and the p-value] were compared. The studies included both paired and non-paired data and were reanalysed both for the fixed-reader and the random-reader situations. The results showed good agreement between the softwares for the mean AUC VGC . For non-paired data, wider CIs were obtained with VGC Analyzer than previously reported, whereas for paired data, the previously reported CIs were similar or even broader. Similar observations were made for the p-values. The results indicate that the use of single-reader-adapted ROC software such as ROCFIT for analysing non-paired VGC data may lead to an increased risk of committing Type I errors, especially in the random-reader situation. On the other hand, the use of ROC software for analysis of paired VGC data may lead to an increased risk of committing Type II errors, especially in the fixed-reader situation. (authors)

  11. Receiver operating characteristic analysis for the detection of simulated microcalcifications on mammograms using hardcopy images

    International Nuclear Information System (INIS)

    Lai, C J; Shaw, Chris C; Whitman, Gary J; Yang, Wei T; Dempsey, Peter J; Nguyen, Victoria; Ice, Mary F

    2006-01-01

    The aim of this study was to compare mammography systems based on three different detectors-a conventional screen-film (SF) combination, an a-Si/CsI flat-panel (FP)-based detector, and a charge-coupled device (CCD)-based x-ray phosphor-based detector-for their performance in detecting simulated microcalcifications (MCs). 112-150 μm calcium carbonate grains were used to simulate MCs and were overlapped with a slab phantom of simulated 50% adipose/50% glandular breast tissue-equivalent material referred to as the uniform background. For the tissue structure background, 200-250 μm calcium carbonate grains were used and overlapped with an anthropomorphic breast phantom. All MC phantom images were acquired with and without magnification (1.8X). The hardcopy images were reviewed by five mammographers. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed, and the areas under the ROC curves (A z s) were used to compare the performances of the three mammography systems under various conditions. The results showed that, with a uniform background and contact images, the FP-based system performed significantly better than the SF and the CCD-based systems. For magnified images with a uniform background, the SF and the FP-based systems performed equally well and significantly better than the CCD-based system. With tissue structure background and contact images, the SF system performed significantly better than the FP and the CCD-based systems. With magnified images and a tissue structure background, the SF and the CCD-based systems performed equally well and significantly better than the FP-based system. In the detection of MCs in the fibroglandular and the heterogeneously dense regions, no significant differences were found except that the SF system performed significantly better than the CCD-based system in the fibroglandular regions for the contact images

  12. Receiver-operating characteristic curves for somatic cell scores and California mastitis test in Valle del Belice dairy sheep.

    Science.gov (United States)

    Riggio, Valentina; Pesce, Lorenzo L; Morreale, Salvatore; Portolano, Baldassare

    2013-06-01

    Using receiver-operating characteristic (ROC) curve methodology this study was designed to assess the diagnostic effectiveness of somatic cell count (SCC) and the California mastitis test (CMT) in Valle del Belice sheep, and to propose and evaluate threshold values for those tests that would optimally discriminate between healthy and infected udders. Milk samples (n=1357) were collected from 684 sheep in four flocks. The prevalence of infection, as determined by positive bacterial culture was 0.36, 87.7% of which were minor and 12.3% major pathogens. Of the culture negative samples, 83.7% had an SCCculture negative vs. infected), minor pathogen status (culture negative vs. infected with minor pathogens), major pathogen status (culture negative vs. infected with major pathogens), and CMT results were evaluated, the estimated area under the ROC curve was greater for glands infected with major compared to minor pathogens (0.88 vs. 0.73), whereas the area under the curve considering all pathogens was similar to the one for minor pathogens (0.75). The estimated optimal thresholds were 3.00 (CMT), 2.81 (SCS for the whole sample), 2.81 (SCS for minor pathogens), and 3.33 (SCS for major pathogens). These correctly classified, respectively, 69.0%, 73.5%, 72.6% and 91.0% of infected udders in the samples. The CMT appeared only to discriminate udders infected with major pathogens. In this population, SCS appeared to be the best indirect test of the bacteriological status of the udder. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Cognitive Vulnerabilities and Depression in Young Adults: An ROC Curves Analysis.

    Science.gov (United States)

    Balsamo, Michela; Imperatori, Claudio; Sergi, Maria Rita; Belvederi Murri, Martino; Continisio, Massimo; Tamburello, Antonino; Innamorati, Marco; Saggino, Aristide

    2013-01-01

    Objectives and Methods. The aim of the present study was to evaluate, by means of receiver operating characteristic (ROC) curves, whether cognitive vulnerabilities (CV), as measured by three well-known instruments (the Beck Hopelessness Scale, BHS; the Life Orientation Test-Revised, LOT-R; and the Attitudes Toward Self-Revised, ATS-R), independently discriminate between subjects with different severities of depression. Participants were 467 young adults (336 females and 131 males), recruited from the general population. The subjects were also administered the Beck Depression Inventory-II (BDI-II). Results. Four first-order (BHS Optimism/Low Standard; BHS Pessimism; Generalized Self-Criticism; and LOT Optimism) and two higher-order factors (Pessimism/Negative Attitudes Toward Self, Optimism) were extracted using Principal Axis Factoring analysis. Although all first-order and second-order factors were able to discriminate individuals with different depression severities, the Pessimism factor had the best performance in discriminating individuals with moderate to severe depression from those with lower depression severity. Conclusion. In the screening of young adults at risk of depression, clinicians have to pay particular attention to the expression of pessimism about the future.

  14. Observer performance in detecting multiple radiographic signals: prediction and analysis using a generalized ROC approach

    International Nuclear Information System (INIS)

    Metz, C.E.; Starr, S.J.; Lusted, L.B.

    1975-01-01

    The theories of decision processes and signal detection provide a framework for the evaluation of observer performance. Some radiologic procedures involve a search for multiple similar lesions, as in gallstone or pneumoconiosis examinations. A model is presented which attempts to predict, from the conventional receiver operating characteristic (ROC) curve describing the detectability of a single visual signal in a radiograph, observer performance in an experiment requiring detection of more than one such signal. An experiment is described which tests the validity of this model for the case of detecting the presence of zero, one, or two low-contrast radiographic images of a two-mm.-diameter lucite bead embedded in radiographic mottle. Results from six observers, including three radiologists, confirm the validity of the model and suggest that human observer performance for relatively complex detection tasks can be predicted from the results of simpler experiments

  15. Additional diagnostic value of 99Tcm-MIBI imaging over 'cold' nodules in 99Tcm thyroid imaging proved by ROC analysis

    International Nuclear Information System (INIS)

    Mei Ping; Qin Yongde; Wang Saigang; Ruxianguli; Baya; Lv Jie; Xie Bing; Sun Xiaoyan

    2007-01-01

    Objective: More studies have found that 99 Tc m -MIBI thyroid imaging may provide more differential diagnostic value than traditional 99 Tc m O 4 - thyroid imaging. This study attempted to analyze the receiver operating characteristic (ROC) curves to verify the additional diagnostic value of 99 Tc m -MIBI over 99 Tc m O 4 - thyroid imaging in the differentiation of the 'cold' nodules. Methods: Sixty-eight patients initially diagnosed with 'cold' nodules in 99 Tc m O 4 - thyroid scintigraphy were selected for further 99 Tc m -MIBI thyroid imaging at early (15 min after 99 Tc m -MIBI intravenous injection, ER) and delayed phase (2 h after injection, DR). Semi-quantitative analysis was performed using tumor/normal tissue (T/N) ratio both at ER and DR, with 0.8 defined as the threshold for differential diagnoses. In ROC curves analyses, the ratios from tumor/submaxillary gland (T/S) and tumor/heart (T/H) were derived to obtain the most proper differential diagnostic thresholds. Results: Of all patients with the 'cold' nodules, only eight cases were finally diagnosed on pathology with thyroid malignancy, while other 60 were benign. For differential diagnoses, the sensitivity, specificity and accuracy of semi-quantitative 99 Tc m -MIBI thyroid imaging were 100.0%, 76.7% and 79.4% respectively. However, with thresholds of T/N=0.995, T/S=0.995, T/H=1.005 derived from ROC curves for DR 99 Tc m -MIBI imaging, the differential diagnostic sensitivities were 100.0%, 87.5%, 75.0% and the specificities were 90.0%, 85.0%, 83.3% respectively. The areas under the ROC curves were 0.949, 0.876 and 0. 867 respectively for DR, all significantly larger than those of ER. Statistical difference was also evident between threshold values of 0.8 and 0.995 (χ 2 =6.125, P 99 Tc m -MIBI thyroid imaging provide additional diagnostic value over 99 Tc m O 4 - thyroid imaging for the differentiation of the 'cold' nodules. For 99 Tc m -MIBI thyroid imaging, DR is more valuable than ER in the ROC

  16. Impact of FIB-4 index on hepatocellular carcinoma incidence during nucleos(t)ide analogue therapy in patients with chronic hepatitis B: An analysis using time-dependent receiver operating characteristic.

    Science.gov (United States)

    Tada, Toshifumi; Kumada, Takashi; Toyoda, Hidenori; Tsuji, Kunihiko; Hiraoka, Atsushi; Tanaka, Junko

    2017-02-01

    Nucleos(t)ide analogue (NA) therapy has been reported to reduce the risk of hepatocellular carcinoma (HCC) development in patients with chronic hepatitis B (CHB). However, even during NA therapy, development of HCC has been observed in patients with CHB. Therefore, we clarified the predictive power of clinical factors for HCC incidence using receiver operating characteristic (ROC) analysis that takes time dependence into account. A total of 539 patients with CHB treated with NAs were enrolled. Univariate, multivariate, and time-dependent ROC curves for clinical factors associated with the development of HCC were analyzed. Eighty-one patients developed HCC during the follow-up period (median duration, 5.9 years). α-fetoprotein (AFP) and FIB-4 index at 24 weeks from the initiation of treatment and sex were significantly associated with HCC incidence according to the log-rank test. Cox proportional hazards models including the covariates of sex, hepatitis B genotype, basal core promoter mutations, AFP at 24 weeks, and FIB-4 index at 24 weeks showed that FIB-4 index >2.65 (HR, 5.03; 95% CI, 3.06-8.26; P patients with CHB receiving NA therapy is a risk factor for developing HCC. The FIB-4 index is an excellent predictor of HCC development. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  17. The role of scintimammography and mammography in recurrent breast cancer. Evaluation of their accuracy using ROC curves

    International Nuclear Information System (INIS)

    Kolasinska, A.D.; Buscombe, J.R.; Cwikla, J.B.; Hilson, A.J.W.; Holloway, B.; Parbhoo, S.P.; Davidson, T.

    2001-01-01

    With the increasing demand for breast conservation surgery, the probability of recurrent tumour within the breast increases. Traditionally x-ray mammography (XMM) was used to assess the post-surgical breast, but post-surgery and radiotherapy changes have reduced the accuracy of this method. Scintimammography (SMM) has also been proposed and appears to be more accurate than XMM. A total of 101 women received Tc99m MIBI SMM and 88 had a subsequent XMM. There were 142 sites suspected of loco-regional recurrence breast cancer. During the study the patients did not receive any treatment other then hormonotherapy. SMM was performed by the standard Diggles-Khalkhali method and XMM was performed using standard 2 views. Analysis was performed and the results of each type of imaging compared with histology. In the ROC curve analysis 5 points of certainty were used: from 1 being definitely normal to 5 being definitely cancer; grades 4 and 5 were counted as positive. The overall sensitivity value of SMM was 84% and specificity was 85%, compared with a sensitivity of 52% for XMM and a specificity of 84%. Analysis of areas under ROC curves provides statistically significant difference between SMM and XMM (p < 0.05). Combining the two tests did not significantly improve the diagnostic accuracy of sequence imaging over SMM. ROC curve analysis demonstrates that scintimammography should be the primary investigation in suspected local recurrence following breast conservation surgery. (author)

  18. ROC analysis of acid demineralized artificial caries

    International Nuclear Information System (INIS)

    Kang, Byung Cheol

    1997-01-01

    This study is designed to determine the artificial incipient proximal caries lesion detectability by dentists on Ektaspeed Plus film using ROC analysis. Sixteen premolars and 30 molars, which have 52 proximal caries-like demineralized lesions using acid-gel technique were added to 20 sound premolars and 30 sound molars to make 24 plaster blocks. Each block with 4 teeth and 6 contacting proximal surfaces was placed in an optical bench to take 12 bitewing radiographs with Ektaspeed Plus film. Thirty-six dentists acted as observers to evaluated the proximal lesions using five rating scales for ROC analysis. They were also asked to determine the presence or absence of the proximal caries. The true status of the proximal caries was established by the consensus of three oral and maxillofacila radiologists. For evaluation of intra-observer agreement, 9 dentist reread the radiographs at an interval of 1 month. The Pearson correlation coefficient for the intra-observer agreement was 0.746 (good agreement). Ten observer's data set were degenerated. The mean area under ROC curve from 26 observers was 0.806 and standard deviation was 0.061. The sensitivity and the specificity of the binary response were 0.17 (SD=0.11) and 0.78 (SD=0.17) respectively. The binary response only reveal a single values of sensitivity and the specificity. The ROC analysis to assess the diagnostic accuracy in caries detection, which producing estimates of sensitivities for all specifities, yield more comprehensive measures of diagnostic performance than single values for sensitivity and specificity.

  19. El Rocío y el turismo de peregrinación

    OpenAIRE

    Villa Díaz, Águeda

    2006-01-01

    La palabra Rocío está llena de significados: una virgen, una romería y una aldea vecinas de la marisma del Guadalquivir bautizadas por un fenómeno microclimático, como es la diaria y fecunda presencia de agua en su mínima expresión las gotas de rocío. Pero este nombre evoca, sobre todo, a la devoción a Nuestra Señora del Rocío Patrona de Almonte y a su anual romería de Pentecostés el Rocío Grande. Esta romería ha conocido una gran expansión en los últimos cincuenta años, atrayendo peregrinos ...

  20. Delineating a Retesting Zone Using Receiver Operating Characteristic Analysis on Serial QuantiFERON Tuberculosis Test Results in US Healthcare Workers

    Directory of Open Access Journals (Sweden)

    Wendy Thanassi

    2012-01-01

    Full Text Available Objective. To find a statistically significant separation point for the QuantiFERON Gold In-Tube (QFT interferon gamma release assay that could define an optimal “retesting zone” for use in serially tested low-risk populations who have test “reversions” from initially positive to subsequently negative results. Method. Using receiver operating characteristic analysis (ROC to analyze retrospective data collected from 3 major hospitals, we searched for predictors of reversion until statistically significant separation points were revealed. A confirmatory regression analysis was performed on an additional sample. Results. In 575 initially positive US healthcare workers (HCWs, 300 (52.2% had reversions, while 275 (47.8% had two sequential positive tests. The most statistically significant (Kappa = 0.48, chi-square = 131.0, P<0.001 separation point identified by the ROC for predicting reversion was the tuberculosis antigen minus-nil (TBag-nil value at 1.11 International Units per milliliter (IU/mL. The second separation point was found at TBag-nil at 0.72 IU/mL (Kappa = 0.16, chi-square = 8.2, P<0.01. The model was validated by the regression analysis of 287 HCWs. Conclusion. Reversion likelihood increases as the TBag-nil approaches the manufacturer's cut-point of 0.35 IU/mL. The most statistically significant separation point between those who test repeatedly positive and those who revert is 1.11 IU/mL. Clinicians should retest low-risk individuals with initial QFT results < 1.11 IU/mL.

  1. ROC analysis of diagnostic performance in liver scintigraphy

    International Nuclear Information System (INIS)

    Fritz, S.L.; Preston, D.F.; Gallagher, J.H.

    1981-01-01

    Studies on the accuracy of liver scintigraphy for the detection of metastases were assembled from 38 sources in the medical literature. An ROC curve was fitted to the observed values of sensitivity and specificity using an algorithm developed by Ogilvie and Creelman. This ROC curve fitted the data better than average sensitivity and specificity values in each of four subsets of the data. For the subset dealing with Tc-99m sulfur colloid scintigraphy, performed for detection of suspected metastases and containing data on 2800 scans from 17 independent series, it was not possible to reject the hypothesis that interobserver variation was entirely due to the use of different decision thresholds by the reporting clinicians. Thus the ROC curve obtained is a reasonable baseline estimate of the performance potentially achievable in today's clinical setting. Comparison of new reports with these data is impossible, but is limited by the small sample sizes in most reported series

  2. ROC analysis of diagnostic performance in liver scintigraphy.

    Science.gov (United States)

    Fritz, S L; Preston, D F; Gallagher, J H

    1981-02-01

    Studies on the accuracy of liver scintigraphy for the detection of metastases were assembled from 38 sources in the medical literature. An ROC curve was fitted to the observed values of sensitivity and specificity using an algorithm developed by Ogilvie and Creelman. This ROC curve fitted the data better than average sensitivity and specificity values in each of four subsets of the data. For the subset dealing with Tc-99m sulfur colloid scintigraphy, performed for detection of suspected metastases and containing data on 2800 scans from 17 independent series, it was not possible to reject the hypothesis that interobserver variation was entirely due to the use of different decision thresholds by the reporting clinicians. Thus the ROC curve obtained is a reasonable baseline estimate of the performance potentially achievable in today's clinical setting. Comparison of new reports with these data is possible, but is limited by the small sample sizes in most reported series.

  3. A semiparametric separation curve approach for comparing correlated ROC data from multiple markers

    Science.gov (United States)

    Tang, Liansheng Larry; Zhou, Xiao-Hua

    2012-01-01

    In this article we propose a separation curve method to identify the range of false positive rates for which two ROC curves differ or one ROC curve is superior to the other. Our method is based on a general multivariate ROC curve model, including interaction terms between discrete covariates and false positive rates. It is applicable with most existing ROC curve models. Furthermore, we introduce a semiparametric least squares ROC estimator and apply the estimator to the separation curve method. We derive a sandwich estimator for the covariance matrix of the semiparametric estimator. We illustrate the application of our separation curve method through two real life examples. PMID:23074360

  4. Discriminatory power of MRI for differentiation of adrenal non-adenomas vs adenomas evaluated by means of ROC analysis: Can biopsy be obviated?

    Energy Technology Data Exchange (ETDEWEB)

    Slapa, R.Z.; Jakubowski, W.; Krolicki, L. [Department of Imaging, Warsaw Medical School (Poland); Januszewicz, A. [Department of Hypertension, National Institute of Cardiology, Warsaw (Poland); Kasperlik-Zaluska, A.A. [Department of Endocrinology, Center for Postgraduate Medical Education, Warsaw (Poland); Dabrowska, E.; Feltynowski, T. [Department of Hypertension, Warsaw Medical School, Warsaw (Poland); Fijuth, J. [Department of Teleradiotherapy, Institute of Oncology, Warsaw (Poland); Tarnawski, R. [Department of Radiotherapy, Institute of Oncology, Gliwice Branch, Gliwice (Poland)

    2000-01-01

    The purpose of our study was to evaluate the discriminatory power of MRI in high-field magnet (1.5 T) for differentiation of adrenal non-adenomas vs adenomas assessing the following parameters separately and in combination: mean diameter of adrenal mass; previously described and new ratios as well as index calculated from signal intensity (SI) on SE T2-weighted images, chemical shift imaging (CSI), and Gd-DTPA-enhanced dynamic studies. One hundred eight adrenal masses (36 non-hyperfunctioning adenomas, 27 pheochromocytomas, 23 aldosterone-secreting adenomas, 20 malignant masses and 2 cortisol-secreting adenomas) in 95 patients were evaluated with SE sequences, CSI and Gd-DTPA dynamic studies. Indices and ratios of SI for all examined MRI methods were calculated and examined retrospectively for significance of differences between the groups with calculation of sensitivity and specificity. Receiver operating characteristics (ROC) analysis of calculated parameters in combination was performed. The multifactorial analysis of all four parameters, including size of the tumor, T2{sub liver} index, CSI ratio reflecting lipid content in the tumor and Wo{sub max/last} ratio reflecting maximal washout of contrast agent from the tumor had 100 % sensitivity and 100 % specificity in characterization of adrenal non-adenoma. The best performance of combination of mean tumor diameter with single MRI SI parameter was achieved in combination with T2{sub liver} index for all adrenal masses (area under ROC 0.987) and CSI ratio for non-hyperfunctioning adrenal masses (area under ROC 0.991). Magnetic resonance imaging enables sensitive and specific diagnosis of adrenal non-adenoma. (orig.)

  5. Non-localization and localization ROC analyses using clinically based scoring

    Science.gov (United States)

    Paquerault, Sophie; Samuelson, Frank W.; Myers, Kyle J.; Smith, Robert C.

    2009-02-01

    We are investigating the potential for differences in study conclusions when assessing the estimated impact of a computer-aided detection (CAD) system on readers' performance. The data utilized in this investigation were derived from a multi-reader multi-case observer study involving one hundred mammographic background images to which fixed-size and fixed-intensity Gaussian signals were added, generating a low- and high-intensity signal sets. The study setting allowed CAD assessment in two situations: when CAD sensitivity was 1) superior or 2) lower than the average reader. Seven readers were asked to review each set in the unaided and CAD-aided reading modes, mark and rate their findings. Using this data, we studied the effect on study conclusion of three clinically-based receiver operating characteristic (ROC) scoring definitions. These scoring definitions included both location-specific and non-location-specific rules. The results showed agreement in the estimated impact of CAD on the overall reader performance. In the study setting where CAD sensitivity is superior to the average reader, the mean difference in AUC between the CAD-aided read and unaided read was 0.049 (95%CIs: -0.027; 0.130) for the image scoring definition that is based on non-location-specific rules, and 0.104 (95%CIs: 0.036; 0.174) and 0.090 (95%CIs: 0.031; 0.155) for image scoring definitions that are based on location-specific rules. The increases in AUC were statistically significant for the location-specific scoring definitions. It was further observed that the variance on these estimates was reduced when using the location-specific scoring definitions compared to that using a non-location-specific scoring definition. In the study setting where CAD sensitivity is equivalent or lower than the average reader, the mean differences in AUC are slightly above 0.01 for all image scoring definitions. These increases in AUC were not statistical significant for any of the image scoring definitions

  6. Scene perception and memory revealed by eye movements and receiver-operating characteristic analyses: does a cultural difference truly exist?

    Science.gov (United States)

    Evans, Kris; Rotello, Caren M; Li, Xingshan; Rayner, Keith

    2009-02-01

    Cultural differences have been observed in scene perception and memory: Chinese participants purportedly attend to the background information more than did American participants. We investigated the influence of culture by recording eye movements during scene perception and while participants made recognition memory judgements. Real-world pictures with a focal object on a background were shown to both American and Chinese participants while their eye movements were recorded. Later, memory for the focal object in each scene was tested, and the relationship between the focal object (studied, new) and the background context (studied, new) was manipulated. Receiver-operating characteristic (ROC) curves show that both sensitivity and response bias were changed when objects were tested in new contexts. However, neither the decrease in accuracy nor the response bias shift differed with culture. The eye movement patterns were also similar across cultural groups. Both groups made longer and more fixations on the focal objects than on the contexts. The similarity of eye movement patterns and recognition memory behaviour suggests that both Americans and Chinese use the same strategies in scene perception and memory.

  7. El rocío y el turismo de peregrinación

    Directory of Open Access Journals (Sweden)

    Águeda Villa Díaz

    2006-01-01

    Full Text Available La palabra Rocío está llena de significados: una virgen, una romería y una aldea —vecinas de la marisma del Guadalquivir— bautizadas por un fenómeno microclimático, como es la diaria y fecunda presencia de agua en su mínima expresión —las gotas de rocío—. Pero este nombre evoca, sobre todo, a la devoción a Nuestra Señora del Rocío —Patrona de Almonte— y a su anual romería de Pentecostés —el Rocío Grande—. Esta romería ha conocido una gran expansión en los últimos cincuenta años, atrayendo peregrinos de puntos cada vez más lejanos, pero su origen es muy antiguo y siempre se ha desarrollado asociada a la aldea. En su imparable proceso de crecimiento, aquella aldea y sus rituales festivos muestran una rápida evolución —adaptable a las nuevas circunstancias— que no desdeña la incorporación de nuevos y dispares elementos, que las modifican sensible y profundamente. De manera que, el Rocío conforma, actualmente, una realidad espacial, social, económica, cultural y simbólica en ebullición. La estrecha vinculación de la aldea y las rutas de peregrinación con los espacios protegidos de Doñana relacionan El Rocío con las políticas de conservación de la naturaleza.

  8. Evaluation of computer tomograms using a black-and-white monitor and a colour monitor: A ROC comparison

    International Nuclear Information System (INIS)

    Rockstroh, G.; Rotte, K.H.; Kriedemann, E.

    1987-01-01

    Different views about the value of a colour monitor for the evaluation of computer tomograms have prompted us to carry out this ROC (Receiver Operation Characteristic) examination. The latter was based on patient computer tomograms in which lesions of the liver were simulated by image manipulation. 5 radiologists analysed the image material (a) on a black-and-white monitor, (b) on a colour monitor, and (c) simultaneously on a black-and-white and a colour monitor. The study shows that the use of a colour monitor gives no essentially different result than evaluation with a black-and-white monitor. The slightly better result of 2% more true positive findings with simultaneous representation of black-and-white and colour image relative to the sole use of black-and-white display is within error limits. The colour representation gives no advantages for the evaluation of usual computer tomograms because the window technique enables a contrasty representation in black-and-white too. (orig.) [de

  9. Geisinger high-risk osteoporosis clinic (HiROC): 2013-2015 FLS performance analysis.

    Science.gov (United States)

    Dunn, P; Webb, D; Olenginski, T P

    2018-02-01

    Geisinger Health System (GHS) high-risk osteoporosis clinic (HiROC), which treats patients with low-trauma, fragility fractures, reports their 2013-2015 performance measures in secondary fracture prevention. This fracture liaison service (FLS) pathway treats 75% of high-risk, drug eligible patients, compared to 13.8% in GHS primary care. This performance points to the need for more FLS programs throughout the world. The purpose of this study is to analyze and report ongoing performance measures in outpatient and inpatient high-risk osteoporosis clinic (HiROC) program designed for patients with low-trauma, fragility fractures. Retrospective chart review of outpatient HiROC (511 patients) and inpatient HiROC (1279 patients) performance from 2013 to 2015 is reported within Geisinger Health System (GHS). Similar to a prior report, we document that Geisinger's branded outpatient and inpatient HiROC pathways continue to function as an all-fracture FLS. Importantly, this analysis emphasizes the importance of FLS care that HiROC's treatment rate of 75% was markedly superior to GHS-PCP care of 13.8%. However, a large percentage of patients (37.8%) were lost to follow-up care. This led to the identification of multiple care gaps/barriers to ideal best practice. FLS programs use case finding strategies and address secondary fracture prevention. GHS HiROC's performance and initiation of drug therapy in this fracture patient population contrasts with GHS-PCP care's much lower rate of treatment, documenting the need for ongoing FLS care. Importantly, the results of this analysis have prompted the beginnings of GHS programmatic changes, designed to narrow the reported care gaps in this mature FLS.

  10. 3D CT versus axial helical CT versus conventional tomography in the classification of acetabular fractures: A ROC analysis

    International Nuclear Information System (INIS)

    Kickuth, Ralph; Laufer, Ulf; Hartung, Guido; Gruening, Christian; Stueckle, Christoph; Kirchner, Johannes

    2002-01-01

    AIM: To assess the diagnostic power of three-dimensional computed tomography (3D CT), axial helical computed tomography (CT) and conventional tomography in the classification of acetabular fractures by interdisciplinary review. MATERIALS AND METHODS: Receiver operating characteristics (ROCs) were assessed for two radiologists and two surgeons blinded to the presence of acetabular fractures in an animal model (a total of 62 porcine hips, 40 of them with artificial acetabular fractures). Main target parameter was the diagnostic accuracy in the classification of the artificial fractures following Judet et al. RESULTS: ROC analysis for radiologists showed A z values of 0·83 for 3D CT, 0·81 for axial helical CT, and 0·78 for conventional tomography; differences between the three techniques were not significant (P = 0·46-0·73). A z values for the surgeons were 0·87 for 3D CT, 0·68 for axial helical CT, and 0·60 for conventional tomography; 3D CT was significantly better than axial helical CT (P = 0·01) and conventional tomography (P = 0·001). The differences between axial helical CT and conventional tomography were not significant (P = 0·37). CONCLUSION: Acetabular fractures are best classified by 3D CT, followed by axial helical CT and conventional tomography when assessed by surgeons. 3D CT did not provide any additional significant benefit in the classification performed by radiologists. Kickuth, R. et al. (2002)

  11. ROC analysis for evaluating the detectability of image unsharpness due to the patient's movement. Phantom study comparing preview and diagnostic LCDs

    International Nuclear Information System (INIS)

    Tanaka, Rie; Shiraishi, Junji; Takamori, Miho; Watari, Chihiro

    2011-01-01

    The purpose of this study was to evaluate the detectability of image unsharpness due to a patient's movement, a receiver operating characteristic (ROC) analysis was conducted to compare the diagnostic and preview liquid-crystal displays (LCDs). Phantom images that simulated a patient's movement were obtained by using a moving metronome and acrylic plates with a computed radiography (CR) system. A total of 104 images were classified into five groups according to the degrees of image unsharpness determined based on the metronome velocity and exposure time. In an ROC observer study (n=6), a 2-megapixel diagnostic monochrome LCD (2M-LCD) and a 1.3-megapixel general color LCD for preview (1.3M-LCD) were compared in terms of the detection of image unsharpness due to the movement. A statistical test was performed using the multi-reader multi-case (MRMC) method. In the results, the average areas under the ROC curve values for the detection of image unsharpness using the 2M-LCD and 1.3M-LCD were 0.952 and 0.850, respectively. The detection of image unsharpness using the 2M-LCD was significantly better than that using the 1.3M-LCD (p<0.05). In addition, some images with slight unsharpness were identified correctly only using the 2M-LCD. The results suggest that the low-resolution LCD (id est (i.e.), the 1.3M-LCD for preview) had a limitation in identifying image unsharpness due to the patient's movement. Slight unsharpness could be missed in primary image checks performed on a preview monitor equipped with an imaging system. Therefore, the high-resolution LCD (i.e., a 2M-LCD) is necessary when using radiography for diagnostics. (author)

  12. Comparison of rat epidermal keratinocyte organotypic culture (ROC) with intact human skin

    DEFF Research Database (Denmark)

    Pappinen, Sari; Hermansson, Martin; Kuntsche, Judith

    2008-01-01

    study was to compare the stratum corneum lipid content of ROC with the corresponding material from human skin. The lipid composition was determined by thin-layer chromatography (TLC) and mass-spectrometry, and the thermal phase transitions of stratum corneum were studied by differential scanning...... calorimetry (DSC). All major lipid classes of the stratum corneum were present in ROC in a similar ratio as found in human stratum corneum. Compared to human skin, the level of non-hydroxyacid-sphingosine ceramide (NS) was increased in ROC, while alpha-hydroxyacid-phytosphingosine ceramide (AP) and non...... compared to human skin, in agreement with the results from DSC. ROC underwent a lipid lamellar order to disorder transition (T2) at a slightly lower temperature (68 degrees C) than human skin (74 degrees C). These differences in stratum corneum lipid composition and the thermal phase transitions may...

  13. Diagnostic accuracy of atypical p-ANCA in autoimmune hepatitis using ROC- and multivariate regression analysis.

    Science.gov (United States)

    Terjung, B; Bogsch, F; Klein, R; Söhne, J; Reichel, C; Wasmuth, J-C; Beuers, U; Sauerbruch, T; Spengler, U

    2004-09-29

    Antineutrophil cytoplasmic antibodies (atypical p-ANCA) are detected at high prevalence in sera from patients with autoimmune hepatitis (AIH), but their diagnostic relevance for AIH has not been systematically evaluated so far. Here, we studied sera from 357 patients with autoimmune (autoimmune hepatitis n=175, primary sclerosing cholangitis (PSC) n=35, primary biliary cirrhosis n=45), non-autoimmune chronic liver disease (alcoholic liver cirrhosis n=62; chronic hepatitis C virus infection (HCV) n=21) or healthy controls (n=19) for the presence of various non-organ specific autoantibodies. Atypical p-ANCA, antinuclear antibodies (ANA), antibodies against smooth muscles (SMA), antibodies against liver/kidney microsomes (anti-Lkm1) and antimitochondrial antibodies (AMA) were detected by indirect immunofluorescence microscopy, antibodies against the M2 antigen (anti-M2), antibodies against soluble liver antigen (anti-SLA/LP) and anti-Lkm1 by using enzyme linked immunosorbent assays. To define the diagnostic precision of the autoantibodies, results of autoantibody testing were analyzed by receiver operating characteristics (ROC) and forward conditional logistic regression analysis. Atypical p-ANCA were detected at high prevalence in sera from patients with AIH (81%) and PSC (94%). ROC- and logistic regression analysis revealed atypical p-ANCA and SMA, but not ANA as significant diagnostic seromarkers for AIH (atypical p-ANCA: AUC 0.754+/-0.026, odds ratio [OR] 3.4; SMA: 0.652+/-0.028, OR 4.1). Atypical p-ANCA also emerged as the only diagnostically relevant seromarker for PSC (AUC 0.690+/-0.04, OR 3.4). None of the tested antibodies yielded a significant diagnostic accuracy for patients with alcoholic liver cirrhosis, HCV or healthy controls. Atypical p-ANCA along with SMA represent a seromarker with high diagnostic accuracy for AIH and should be explicitly considered in a revised version of the diagnostic score for AIH.

  14. Repository operational criteria comparative analysis

    International Nuclear Information System (INIS)

    Hageman, J.P.; Chowdhury, A.H.

    1994-06-01

    The objective of the ''Repository Operational Criteria (ROC) Feasibility Studies'' (or ROC task) was to conduct comprehensive and integrated analyses of repository design, construction, and operations criteria in 10 CFR Part 60 regulations considering the interfaces among the components of the regulations and impacts of any potential changes to those regulations. The ROC task addresses regulatory criteria and uncertainties related to the preclosure aspects of the geologic repository. Those parts of 10 CFR Part 60 that require routine guidance or minor changes to the rule were addressed in Hageman and Chowdhury, 1992. The ROC task shows a possible need for further regulatory clarity, by major changes to the rule, related to the design bases and siting of a geologic repository operations area and radiological emergency planning in order to assure defense-in-depth. The analyses, presented in this report, resulted in the development and refinement of regulatory concepts and their supporting rationale for recommendations for potential major changes to 10 CFR Pan 0 regulations

  15. Overestimation of test performance by ROC analysis: Effect of small sample size

    International Nuclear Information System (INIS)

    Seeley, G.W.; Borgstrom, M.C.; Patton, D.D.; Myers, K.J.; Barrett, H.H.

    1984-01-01

    New imaging systems are often observer-rated by ROC techniques. For practical reasons the number of different images, or sample size (SS), is kept small. Any systematic bias due to small SS would bias system evaluation. The authors set about to determine whether the area under the ROC curve (AUC) would be systematically biased by small SS. Monte Carlo techniques were used to simulate observer performance in distinguishing signal (SN) from noise (N) on a 6-point scale; P(SN) = P(N) = .5. Four sample sizes (15, 25, 50 and 100 each of SN and N), three ROC slopes (0.8, 1.0 and 1.25), and three intercepts (0.8, 1.0 and 1.25) were considered. In each of the 36 combinations of SS, slope and intercept, 2000 runs were simulated. Results showed a systematic bias: the observed AUC exceeded the expected AUC in every one of the 36 combinations for all sample sizes, with the smallest sample sizes having the largest bias. This suggests that evaluations of imaging systems using ROC curves based on small sample size systematically overestimate system performance. The effect is consistent but subtle (maximum 10% of AUC standard deviation), and is probably masked by the s.d. in most practical settings. Although there is a statistically significant effect (F = 33.34, P<0.0001) due to sample size, none was found for either the ROC curve slope or intercept. Overestimation of test performance by small SS seems to be an inherent characteristic of the ROC technique that has not previously been described

  16. Identifying indicators of harmful and problem gambling in a Canadian sample through receiver operating characteristic analysis.

    Science.gov (United States)

    Quilty, Lena C; Avila Murati, Daniela; Bagby, R Michael

    2014-03-01

    Many gamblers would prefer to reduce gambling on their own rather than to adopt an abstinence approach within the context of a gambling treatment program. Yet responsible gambling guidelines lack quantifiable markers to guide gamblers in wagering safely. To address these issues, the current investigation implemented receiver operating characteristic (ROC) analysis to identify behavioral indicators of harmful and problem gambling. Gambling involvement was assessed in 503 participants (275 psychiatric outpatients and 228 community gamblers) with the Canadian Problem Gambling Index. Overall gambling frequency, duration, and expenditure were able to distinguish harmful and problematic gambling at a moderate level. Indicators of harmful gambling were generated for engagement in specific gambling activities: frequency of tickets and casino; duration of bingo, casino, and investments; and expenditures on bingo, casino, sports betting, games of skill, and investments. Indicators of problem gambling were similarly produced for frequency of tickets and casino, and expenditures on bingo, casino, games of skill, and investments. Logistic regression analyses revealed that overall gambling frequency uniquely predicted the presence of harmful and problem gambling. Furthermore, frequency indicators for tickets and casino uniquely predicted the presence of both harmful and problem gambling. Together, these findings contribute to the development of an empirically based method enabling the minimization of harmful or problem gambling through self-control rather than abstinence.

  17. A statistical approach to evaluate the performance of cardiac biomarkers in predicting death due to acute myocardial infarction: time-dependent ROC curve

    Science.gov (United States)

    Karaismailoğlu, Eda; Dikmen, Zeliha Günnur; Akbıyık, Filiz; Karaağaoğlu, Ahmet Ergun

    2018-04-30

    Background/aim: Myoglobin, cardiac troponin T, B-type natriuretic peptide (BNP), and creatine kinase isoenzyme MB (CK-MB) are frequently used biomarkers for evaluating risk of patients admitted to an emergency department with chest pain. Recently, time- dependent receiver operating characteristic (ROC) analysis has been used to evaluate the predictive power of biomarkers where disease status can change over time. We aimed to determine the best set of biomarkers that estimate cardiac death during follow-up time. We also obtained optimal cut-off values of these biomarkers, which differentiates between patients with and without risk of death. A web tool was developed to estimate time intervals in risk. Materials and methods: A total of 410 patients admitted to the emergency department with chest pain and shortness of breath were included. Cox regression analysis was used to determine an optimal set of biomarkers that can be used for estimating cardiac death and to combine the significant biomarkers. Time-dependent ROC analysis was performed for evaluating performances of significant biomarkers and a combined biomarker during 240 h. The bootstrap method was used to compare statistical significance and the Youden index was used to determine optimal cut-off values. Results : Myoglobin and BNP were significant by multivariate Cox regression analysis. Areas under the time-dependent ROC curves of myoglobin and BNP were about 0.80 during 240 h, and that of the combined biomarker (myoglobin + BNP) increased to 0.90 during the first 180 h. Conclusion: Although myoglobin is not clinically specific to a cardiac event, in our study both myoglobin and BNP were found to be statistically significant for estimating cardiac death. Using this combined biomarker may increase the power of prediction. Our web tool can be useful for evaluating the risk status of new patients and helping clinicians in making decisions.

  18. A comparison of confidence/credible interval methods for the area under the ROC curve for continuous diagnostic tests with small sample size.

    Science.gov (United States)

    Feng, Dai; Cortese, Giuliana; Baumgartner, Richard

    2017-12-01

    The receiver operating characteristic (ROC) curve is frequently used as a measure of accuracy of continuous markers in diagnostic tests. The area under the ROC curve (AUC) is arguably the most widely used summary index for the ROC curve. Although the small sample size scenario is common in medical tests, a comprehensive study of small sample size properties of various methods for the construction of the confidence/credible interval (CI) for the AUC has been by and large missing in the literature. In this paper, we describe and compare 29 non-parametric and parametric methods for the construction of the CI for the AUC when the number of available observations is small. The methods considered include not only those that have been widely adopted, but also those that have been less frequently mentioned or, to our knowledge, never applied to the AUC context. To compare different methods, we carried out a simulation study with data generated from binormal models with equal and unequal variances and from exponential models with various parameters and with equal and unequal small sample sizes. We found that the larger the true AUC value and the smaller the sample size, the larger the discrepancy among the results of different approaches. When the model is correctly specified, the parametric approaches tend to outperform the non-parametric ones. Moreover, in the non-parametric domain, we found that a method based on the Mann-Whitney statistic is in general superior to the others. We further elucidate potential issues and provide possible solutions to along with general guidance on the CI construction for the AUC when the sample size is small. Finally, we illustrate the utility of different methods through real life examples.

  19. Comparing risk of failure models in water supply networks using ROC curves

    International Nuclear Information System (INIS)

    Debon, A.; Carrion, A.; Cabrera, E.; Solano, H.

    2010-01-01

    The problem of predicting the failure of water mains has been considered from different perspectives and using several methodologies in engineering literature. Nowadays, it is important to be able to accurately calculate the failure probabilities of pipes over time, since water company profits and service quality for citizens depend on pipe survival; forecasting pipe failures could have important economic and social implications. Quantitative tools (such as managerial or statistical indicators and reliable databases) are required in order to assess the current and future state of networks. Companies managing these networks are trying to establish models for evaluating the risk of failure in order to develop a proactive approach to the renewal process, instead of using traditional reactive pipe substitution schemes. The main objective of this paper is to compare models for evaluating the risk of failure in water supply networks. Using real data from a water supply company, this study has identified which network characteristics affect the risk of failure and which models better fit data to predict service breakdown. The comparison using the receiver operating characteristics (ROC) graph leads us to the conclusion that the best model is a generalized linear model. Also, we propose a procedure that can be applied to a pipe failure database, allowing the most appropriate decision rule to be chosen.

  20. Comparing risk of failure models in water supply networks using ROC curves

    Energy Technology Data Exchange (ETDEWEB)

    Debon, A., E-mail: andeau@eio.upv.e [Centro de Gestion de la Calidad y del Cambio, Dpt. Estadistica e Investigacion Operativa Aplicadas y Calidad, Universidad Politecnica de Valencia, E-46022 Valencia (Spain); Carrion, A. [Centro de Gestion de la Calidad y del Cambio, Dpt. Estadistica e Investigacion Operativa Aplicadas y Calidad, Universidad Politecnica de Valencia, E-46022 Valencia (Spain); Cabrera, E. [Dpto. De Ingenieria Hidraulica Y Medio Ambiente, Instituto Tecnologico del Agua, Universidad Politecnica de Valencia, E-46022 Valencia (Spain); Solano, H. [Universidad Diego Portales, Santiago (Chile)

    2010-01-15

    The problem of predicting the failure of water mains has been considered from different perspectives and using several methodologies in engineering literature. Nowadays, it is important to be able to accurately calculate the failure probabilities of pipes over time, since water company profits and service quality for citizens depend on pipe survival; forecasting pipe failures could have important economic and social implications. Quantitative tools (such as managerial or statistical indicators and reliable databases) are required in order to assess the current and future state of networks. Companies managing these networks are trying to establish models for evaluating the risk of failure in order to develop a proactive approach to the renewal process, instead of using traditional reactive pipe substitution schemes. The main objective of this paper is to compare models for evaluating the risk of failure in water supply networks. Using real data from a water supply company, this study has identified which network characteristics affect the risk of failure and which models better fit data to predict service breakdown. The comparison using the receiver operating characteristics (ROC) graph leads us to the conclusion that the best model is a generalized linear model. Also, we propose a procedure that can be applied to a pipe failure database, allowing the most appropriate decision rule to be chosen.

  1. A transfer of technology from engineering: use of ROC curves from signal detection theory to investigate information processing in the brain during sensory difference testing.

    Science.gov (United States)

    Wichchukit, Sukanya; O'Mahony, Michael

    2010-01-01

    This article reviews a beneficial effect of technology transfer from Electrical Engineering to Food Sensory Science. Specifically, it reviews the recent adoption in Food Sensory Science of the receiver operating characteristic (ROC) curve, a tool that is incorporated in the theory of signal detection. Its use allows the information processing that takes place in the brain during sensory difference testing to be studied and understood. The review deals with how Signal Detection Theory, also called Thurstonian modeling, led to the adoption of a more sophisticated way of analyzing the data from sensory difference tests, by introducing the signal-to-noise ratio, d', as a fundamental measure of perceived small sensory differences. Generally, the method of computation of d' is a simple matter for some of the better known difference tests like the triangle, duo-trio and 2-AFC. However, there are occasions when these tests are not appropriate and other tests like the same-different and the A Not-A test are more suitable. Yet, for these, it is necessary to understand how the brain processes information during the test before d' can be computed. It is for this task that the ROC curve has a particular use. © 2010 Institute of Food Technologists®

  2. 47 CFR 25.220 - Non-conforming transmit/receive earth station operations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Non-conforming transmit/receive earth station operations. 25.220 Section 25.220 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25.220 Non-conforming transmit/receive...

  3. Repository operational criteria analysis

    International Nuclear Information System (INIS)

    Hageman, J.P.; Chowdhury, A.H.

    1992-08-01

    The objective of the ''Repository Operational Criteria (ROC) Feasibility Studies'' (or ROC task) was to conduct comprehensive and integrated analyses of repository design, construction, and operations criteria in 10 CFR Part 60 regulations, considering the interfaces and impacts of any potential changes to those regulations. The study addresses regulatory criteria related to the preclosure aspects of the geologic repository. The study task developed regulatory concepts or potential repository operational criteria (PROC) based on analysis of a repository's safety functions and other regulations for similar facilities. These regulatory concepts or PROC were used as a basis to assess the sufficiency and adequacy of the current criteria in 10 CFR Part 60. Where the regulatory concepts were same as current operational criteria, these criteria were referenced. The operations criteria referenced or the PROC developed are given in this report. Detailed analyses used to develop the regulatory concepts and any necessary PROC for those regulations that may require a minor change are also presented. The results of the ROC task showed a need for further analysis and possible major rule change related to the design bases of a geologic repository operations area, siting, and radiological emergency planning

  4. Quantitative contrast-enhanced ultrasound evaluation of pathological complete response in patients with locally advanced breast cancer receiving neoadjuvant chemotherapy.

    Science.gov (United States)

    Wan, Cai-Feng; Liu, Xue-Song; Wang, Lin; Zhang, Jie; Lu, Jin-Song; Li, Feng-Hua

    2018-06-01

    To clarify whether the quantitative parameters of contrast-enhanced ultrasound (CEUS) can be used to predict pathological complete response (pCR) in patients with locally advanced breast cancer receiving neoadjuvant chemotherapy (NAC). Fifty-one patients with histologically proved locally advanced breast cancer scheduled for NAC were enrolled. The quantitative data for CEUS and the tumor diameter were collected at baseline and before surgery, and compared with the pathological response. Multiple logistic regression analysis was performed to examine quantitative parameters at CEUS and the tumor diameter to predict the pCR, and receiver operating characteristic (ROC) curve analysis was used as a summary statistic. Multiple logistic regression analysis revealed that PEAK (the maximum intensity of the time-intensity curve during bolus transit), PEAK%, TTP% (time to peak), and diameter% were significant independent predictors of pCR, and the area under the ROC curve was 0.932(Az 1 ), and the sensitivity and specificity to predict pCR were 93.7% and 80.0%. The area under the ROC curve for the quantitative parameters was 0.927(Az 2 ), and the sensitivity and specificity to predict pCR were 81.2% and 94.3%. For diameter%, the area under the ROC curve was 0.786 (Az 3 ), and the sensitivity and specificity to predict pCR were 93.8% and 54.3%. The values of Az 1 and Az 2 were significantly higher than that of Az 3 (P = 0.027 and P = 0.034, respectively). However, there was no significant difference between the values of Az 1 and Az 2 (P = 0.825). Quantitative analysis of tumor blood perfusion with CEUS is superior to diameter% to predict pCR, and can be used as a functional technique to evaluate tumor response to NAC. Copyright © 2018. Published by Elsevier B.V.

  5. Corrected ROC analysis for misclassified binary outcomes.

    Science.gov (United States)

    Zawistowski, Matthew; Sussman, Jeremy B; Hofer, Timothy P; Bentley, Douglas; Hayward, Rodney A; Wiitala, Wyndy L

    2017-06-15

    Creating accurate risk prediction models from Big Data resources such as Electronic Health Records (EHRs) is a critical step toward achieving precision medicine. A major challenge in developing these tools is accounting for imperfect aspects of EHR data, particularly the potential for misclassified outcomes. Misclassification, the swapping of case and control outcome labels, is well known to bias effect size estimates for regression prediction models. In this paper, we study the effect of misclassification on accuracy assessment for risk prediction models and find that it leads to bias in the area under the curve (AUC) metric from standard ROC analysis. The extent of the bias is determined by the false positive and false negative misclassification rates as well as disease prevalence. Notably, we show that simply correcting for misclassification while building the prediction model is not sufficient to remove the bias in AUC. We therefore introduce an intuitive misclassification-adjusted ROC procedure that accounts for uncertainty in observed outcomes and produces bias-corrected estimates of the true AUC. The method requires that misclassification rates are either known or can be estimated, quantities typically required for the modeling step. The computational simplicity of our method is a key advantage, making it ideal for efficiently comparing multiple prediction models on very large datasets. Finally, we apply the correction method to a hospitalization prediction model from a cohort of over 1 million patients from the Veterans Health Administrations EHR. Implementations of the ROC correction are provided for Stata and R. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  6. Bootstrap-based procedures for inference in nonparametric receiver-operating characteristic curve regression analysis.

    Science.gov (United States)

    Rodríguez-Álvarez, María Xosé; Roca-Pardiñas, Javier; Cadarso-Suárez, Carmen; Tahoces, Pablo G

    2018-03-01

    Prior to using a diagnostic test in a routine clinical setting, the rigorous evaluation of its diagnostic accuracy is essential. The receiver-operating characteristic curve is the measure of accuracy most widely used for continuous diagnostic tests. However, the possible impact of extra information about the patient (or even the environment) on diagnostic accuracy also needs to be assessed. In this paper, we focus on an estimator for the covariate-specific receiver-operating characteristic curve based on direct regression modelling and nonparametric smoothing techniques. This approach defines the class of generalised additive models for the receiver-operating characteristic curve. The main aim of the paper is to offer new inferential procedures for testing the effect of covariates on the conditional receiver-operating characteristic curve within the above-mentioned class. Specifically, two different bootstrap-based tests are suggested to check (a) the possible effect of continuous covariates on the receiver-operating characteristic curve and (b) the presence of factor-by-curve interaction terms. The validity of the proposed bootstrap-based procedures is supported by simulations. To facilitate the application of these new procedures in practice, an R-package, known as npROCRegression, is provided and briefly described. Finally, data derived from a computer-aided diagnostic system for the automatic detection of tumour masses in breast cancer is analysed.

  7. Recent developments in the ROCS/MC code for retrieving local power information in coarse-mesh reactor analysis

    International Nuclear Information System (INIS)

    Grill, S.F.; Jonsson, A.; Crump, M.W.

    1983-01-01

    The inclusion of 3-D effects in PWR analysis is necessary for accurate predictions of reactivity, power distributions, and reactivity coefficients. The ROCS/MC code system has been developed by Combustion Engineering to provide 3-D coarse mesh analysis (ROCS) with the capability to retrieve local information on flux, power and burnup (MC). A review of the finite difference representation of the MC diffusion equation, along with recent improvements to the ROCS/MC system are presented. These improvements include the implementation if fine mesh radial boundary conditions and internal calculation of coarse mesh boundary conditions, generalization of the imbedded calculation to account for the local neighboring environment, and the automation of ROCS/MC links to C-E's code system for in-core power distribution monitoring and core-follow analysis. The results of the ROCS/MC verification program are described and show good agreement with C-E's ROCS/PDQ based methodologies

  8. Preliminary analysis of the operating characteristics of a generic repository receiving facility: Status report

    International Nuclear Information System (INIS)

    1985-10-01

    The operating characteristics of a repository receiving facility structured around current technology and practices have been reviewed. Cask turnaround times and operator doses were estimated. Large throughout and long-term receiving operations at a nuclear waste repository result in an unprecedented number of casks being handled. While the current generation of material-handling equipment is adequate to process the casks, personnel radiation exposures for the generic facility analyzed are unacceptably high. This emphasizes the need for development of occupational radiation exposure control concepts for application in repository receiving facilities. 3 refs., 22 figs., 6 tabs

  9. Differentiation between microcystin contaminated and uncontaminated fish by determination of unconjugated MCs using an ELISA anti-Adda test based on receiver-operating characteristic curves threshold values: application to Tinca tinca from natural ponds.

    Science.gov (United States)

    Moreno, Isabel María; Herrador, M Ángeles; Atencio, Loyda; Puerto, María; González, A Gustavo; Cameán, Ana María

    2011-02-01

    The aim of this study was to evaluate whether the enzyme-linked immunosorbent assay (ELISA) anti-Adda technique could be used to monitor free microcystins (MCs) in biological samples from fish naturally exposed to toxic cyanobacteria by using receiver operating characteristic (ROC) curve software to establish an optimal cut-off value for MCs. The cut-off value determined by ROC curve analysis in tench (Tinca tinca) exposed to MCs under laboratory conditions by ROC curve analysis was 5.90-μg MCs/kg tissue dry weight (d.w.) with a sensitivity of 93.3%. This value was applied in fish samples from natural ponds (Extremadura, Spain) in order to asses its potential MCs bioaccumulation by classifying samples as either true positive (TP), false positive (FP), true negative (TN), or false negative (FN). In this work, it has been demonstrated that toxic cyanobacteria, mainly Microcystis aeruginosa, Aphanizomenon issatchenkoi, and Anabaena spiroides, were present in two of these ponds, Barruecos de Abajo (BDown) and Barruecos de Arriba (BUp). The MCs levels were detected in waters from both ponds with an anti-MC-LR ELISA immunoassay and were of similar values (between 3.8-6.5-μg MC-LR equivalent/L in BDown pond and 4.8-6.0-μg MC-LR equivalent/L in BUp). The MCs cut-off values were applied in livers from fish collected from these two ponds using the ELISA anti-Adda technique. A total of 83% of samples from BDown pond and only 42% from BUp were TP with values of free MCs higher than 8.8-μg MCs/kg tissue (d.w.). Copyright © 2009 Wiley Periodicals, Inc.

  10. Diagnostic yield of ink-jet prints from digital radiographs for the assessment of approximal carious lesions: ROC-analysis

    International Nuclear Information System (INIS)

    Schulze, Ralf K.W.; Grimm, Stefanie; Schulze, Dirk; Voss, Kai; Keller, Hans-Peter; Wedel, Matthias

    2011-01-01

    Aims: To investigate the diagnostic quality of different quality, individually calibrated ink-jet printers for the very challenging dental radiographic task of approximal carious lesion detection. Materials and methods: A test-pattern evaluating resolution, contrast and homogeneity of the ink-jet prints was developed. 50 standardized dental radiographs each showing two neighbouring teeth in natural contact were printed on glossy paper with calibrated, randomly selected ink-jet printers (Canon S520 and iP4500, Epson Stylus Photo R2400). Printing size equalled the viewing size on a 17'' cathode-ray-tube monitor daily quality-tested according to German regulations. The true caries status was determined from serial sectioning and microscopic evaluation. 16 experienced observers evaluated the radiographs on a five-point confidence scale on all prints plus the viewing monitor with respect to the visibility of a carious lesion. A non-parametric Receiver-Operating Characteristics (ROC-) analysis was performed explicitly designed for the evaluation of readings stemming from identical samples but different modality. Significant differences are expressed by a critical ratio z exceeding ±2. Diagnostic accuracy was determined by the area (Az) underneath the ROC-curves. Results: Average Az-values ranged between 0.62 (S520 and R2400) and 0.64 (monitor, iP4500), with no significant difference between modalities (P = 0.172). Neither significant (range mean z: -0.40 (S520) and -0.11 (iP4500)) nor clinically relevant differences were found between printers and viewing monitor. Conclusions: Our results for a challenging task in dental radiography indicate that calibrated, off-the-shelf ink-jet printers are able to reproduce (dental) radiographs at quality levels sufficient for radiographic diagnosis in a typical dental working environment.

  11. Diagnostic yield of ink-jet prints from digital radiographs for the assessment of approximal carious lesions: ROC-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Ralf K.W., E-mail: rschulze@mail.uni-mainz.de [Poliklinik fuer Zahnaerztliche Chirurgie, University Medical Center of the Johannes Gutenberg-University, Augustusplatz 2, D-55131 Mainz (Germany); Grimm, Stefanie, E-mail: StefanieGrimm@gmx.de [Poliklinik fuer Zahnaerztliche Chirurgie, University Medical Center of the Johannes Gutenberg-University, Augustusplatz 2, D-55131 Mainz (Germany); Schulze, Dirk, E-mail: dirk.schulze@uniklinik-freiburg.de [Klinik fuer Mund,- Kiefer- und Gesichtschirurgie, Sektion Roentgen, Universitaetsklinikum Freiburg, Hugstetterstr. 55, D-79106 Freiburg (Germany); Voss, Kai, E-mail: zahnarzt@drvoss.eu [Zahnaerztekammer Schleswig-Holstein, Vorstand fuer Praxisfuehrung, Westring 496, D- 24106 Kiel (Germany); Keller, Hans-Peter, E-mail: hans-peter.keller@din.de [NA Dental (NADENT) im DIN, Alexander-Wellendorff-Str. 2, D-75172 Pforzheim (Germany); Wedel, Matthias, E-mail: matthias.wedel@siemens.com [Siemens AG, Medical Solutions, Postfach 32 60, D-91050 Erlangen (Germany)

    2011-08-15

    Aims: To investigate the diagnostic quality of different quality, individually calibrated ink-jet printers for the very challenging dental radiographic task of approximal carious lesion detection. Materials and methods: A test-pattern evaluating resolution, contrast and homogeneity of the ink-jet prints was developed. 50 standardized dental radiographs each showing two neighbouring teeth in natural contact were printed on glossy paper with calibrated, randomly selected ink-jet printers (Canon S520 and iP4500, Epson Stylus Photo R2400). Printing size equalled the viewing size on a 17'' cathode-ray-tube monitor daily quality-tested according to German regulations. The true caries status was determined from serial sectioning and microscopic evaluation. 16 experienced observers evaluated the radiographs on a five-point confidence scale on all prints plus the viewing monitor with respect to the visibility of a carious lesion. A non-parametric Receiver-Operating Characteristics (ROC-) analysis was performed explicitly designed for the evaluation of readings stemming from identical samples but different modality. Significant differences are expressed by a critical ratio z exceeding {+-}2. Diagnostic accuracy was determined by the area (Az) underneath the ROC-curves. Results: Average Az-values ranged between 0.62 (S520 and R2400) and 0.64 (monitor, iP4500), with no significant difference between modalities (P = 0.172). Neither significant (range mean z: -0.40 (S520) and -0.11 (iP4500)) nor clinically relevant differences were found between printers and viewing monitor. Conclusions: Our results for a challenging task in dental radiography indicate that calibrated, off-the-shelf ink-jet printers are able to reproduce (dental) radiographs at quality levels sufficient for radiographic diagnosis in a typical dental working environment.

  12. Role of high-resolution CT in the diagnosis of small pulmonary nodules coexisting with potentially operable lung cancer

    International Nuclear Information System (INIS)

    Yuan, Yue; Matsumoto, Tsuneo; Hiyama, Atsuto; Miura, Goji; Tanaka, Nobuyuki; Matsunaga, Naofumi

    2002-01-01

    The purpose of this study was to evaluate whether high-resolution CT (HRCT) could facilitate the preoperative diagnosis of one or two small nodules of 1 cm or less coexisting with a lung cancer, i.e., coexisting small nodule. This study included 27 coexisting small nodules in 24 potentially operable lung cancer patients. An observer study was performed by five radiologists. The observer performances in differentiating malignant from benign coexisting small nodules were evaluated on conventional CT and HRCT using receiver operating characteristic (ROC) analysis. The area under the ROC curve of five observers was 0.731 on HRCT and 0.578 on conventional CT in the differential diagnosis of coexisting small nodules. A significant diagnostic improvement was found on HRCT (p=0.031). This was especially evident for nodules of ground-glass attenuation (p=0.005). HRCT plays an important role in determining the treatment of potentially operable lung cancer patients with coexisting small nodules. (author)

  13. Subject-centered free-response ROC (FROC) analysis

    OpenAIRE

    Bandos, Andriy I.; Rockette, Howard E.; Gur, David

    2013-01-01

    Purpose: To develop an approach of estimating subject-centered free-response receiver operating characteristic (FROC) curve for providing patient-centered inferences regarding detection-localization characteristics of a diagnostic system.

  14. Quantitative evaluation of visual detection performance in medicine: ROC analysis and determination of diagnostic benefit

    International Nuclear Information System (INIS)

    Metz, C.E.; Starr, S.J.; Lusted, L.B.

    1976-01-01

    An ROC curve provides an empirical description of the trade-offs which are possible among the various types of correct and incorrect decisions as the human decision-maker varies one or more confidence thresholds. Conventional ROC curves measured in simple decision-making situations can, in some cases, be used to predict human decision performance in more complex situations. By considering both the consequences of the various types of diagnostic decisions and the overhead cost of a diagnostic study, one can use the ROC curve to evaluate the diagnostic usefulness of a study in any particular clinical context. Since the ROC curve describes the possible relationships among the probabilities of the various types of correct and incorrect decisions, it plays a central role in optimizing diagnostic strategies using the general techniques of decision analysis. Applications in radiographic image evaluation are described

  15. An ROC-type measure of diagnostic accuracy when the gold standard is continuous-scale.

    Science.gov (United States)

    Obuchowski, Nancy A

    2006-02-15

    ROC curves and summary measures of accuracy derived from them, such as the area under the ROC curve, have become the standard for describing and comparing the accuracy of diagnostic tests. Methods for estimating ROC curves rely on the existence of a gold standard which dichotomizes patients into disease present or absent. There are, however, many examples of diagnostic tests whose gold standards are not binary-scale, but rather continuous-scale. Unnatural dichotomization of these gold standards leads to bias and inconsistency in estimates of diagnostic accuracy. In this paper, we propose a non-parametric estimator of diagnostic test accuracy which does not require dichotomization of the gold standard. This estimator has an interpretation analogous to the area under the ROC curve. We propose a confidence interval for test accuracy and a statistical test for comparing accuracies of tests from paired designs. We compare the performance (i.e. CI coverage, type I error rate, power) of the proposed methods with several alternatives. An example is presented where the accuracies of two quick blood tests for measuring serum iron concentrations are estimated and compared.

  16. Use of the ROC anchor in foot and ankle surgery. A retrospective study.

    Science.gov (United States)

    Kuwada, G T

    1999-05-01

    A retrospective study was conducted on the use of the ROC (Radial Osteo Compression) soft-tissue anchor in foot and ankle surgery. This article describes how the anchor is deployed, problematic aspects of using the anchor, and complications and success rates associated with the anchor in ankle stabilizations, posterior tibial tendon reconstruction, peroneus brevis tendon reconstruction after fracture of the base of the fifth metatarsal, and detachment and reattachment of the Achilles tendon. The ROC anchor consists of the anchor with nonabsorbable suture attached to the shaft, the deployment handle, and drill bits. The anchor and shaft are snapped into the deployment handle and inserted into the drill hole. Compression of the trigger deploys the anchor into the hole. The ROC anchor was found to be reliable, useful, and relatively easy to deploy, with outcomes similar to those of other soft-tissue anchors.

  17. Can the pre-operative Western Ontario and McMaster score predict patient satisfaction following total hip arthroplasty?

    Science.gov (United States)

    Rogers, B A; Alolabi, B; Carrothers, A D; Kreder, H J; Jenkinson, R J

    2015-02-01

    In this study we evaluated whether pre-operative Western Ontario and McMaster Universities (WOMAC) osteoarthritis scores can predict satisfaction following total hip arthroplasty (THA). Prospective data for a cohort of patients undergoing THA from two large academic centres were collected, and pre-operative and one-year post-operative WOMAC scores and a 25-point satisfaction questionnaire were obtained for 446 patients. Satisfaction scores were dichotomised into either improvement or deterioration. Scatter plots and Spearman's rank correlation coefficient were used to describe the association between pre-operative WOMAC and one-year post-operative WOMAC scores and patient satisfaction. Satisfaction was compared using receiver operating characteristic (ROC) analysis against pre-operative, post-operative and δ WOMAC scores. We found no relationship between pre-operative WOMAC scores and one-year post-operative WOMAC or satisfaction scores, with Spearman's rank correlation coefficients of 0.16 and -0.05, respectively. The ROC analysis showed areas under the curve (AUC) of 0.54 (pre-operative WOMAC), 0.67 (post-operative WOMAC) and 0.43 (δ WOMAC), respectively, for an improvement in satisfaction. We conclude that the pre-operative WOMAC score does not predict the post-operative WOMAC score or patient satisfaction after THA, and that WOMAC scores can therefore not be used to prioritise patient care. ©2015 The British Editorial Society of Bone & Joint Surgery.

  18. Lesion type and reader experience affect the diagnostic accuracy of breast MRI: A multiple reader ROC study

    Energy Technology Data Exchange (ETDEWEB)

    Baltzer, Pascal A.T., E-mail: patbaltzer@gmail.com [Department of Biomedical Imaging and Imge-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna (Austria); Kaiser, Werner Alois [Department of Diagnostic and Interventional Radiology, University Hospital Jena, Erlanger Allee 101, 07740 Jena (Germany); Dietzel, Matthias, E-mail: dietzelmatthias2@hotmail.com [Department of Neuroradiology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen (Germany)

    2015-01-15

    Highlights: • The main findings of our study are, that reader experience and lesion type (i.e., mass versus non-mass enhancement) are independent predictors of the diagnostic accuracy of breast MRI. • Specifically, benign and malignant non-mass lesions cannot be differentiated with sufficient accuracy, especially if readers are not experienced. • We conclude that future research in breast MRI should focus on non-mass lesions, as these are the problem makers in modern breast MRI. - Abstract: Purpose: To evaluate the influence of lesion type (mass versus non-mass) and reader experience on the diagnostic performance of breast MRI (BMRI) in a non-screening setting. Materials and methods: Consecutive patients (mean age, 55 ± 12 years) with breast lesions that were verified by biopsy or surgery, and who had had BMRI as part of their diagnostic workup, were eligible for this retrospective single-center study. Cancers diagnosed by biopsy before BMRI were excluded to eliminate biological and interpretation bias due to biopsy or chemotherapy effects (n = 103). Six blinded readers (experience level, high (HE, n = 2); intermediate (IE, n = 2); and low (LE, n = 2)) evaluated all examinations and assigned independent MRI BI-RADS ratings. Lesion type (mass, non-mass, focal) was noted. Receiver operating characteristics (ROC) and logistic regression analysis was performed to compare diagnostic accuracies. Results: There were 259 histologically verified lesions (123 malignant, 136 benign) investigated. There were 169 mass (103 malignant, 66 benign) and 48 non-mass lesions (19 malignant, 29 benign). Another 42 lesions that met the inclusion criteria were biopsied due to conventional findings (i.e., microcalcifications, architectural distortions), but did not enhance on MRI (41 benign, one DCIS). ROC analysis revealed a total area under the curve (AUC) between 0.834 (LE) and 0.935 (HI). Logistic regression identified a significant effect of non-mass lesions (P < 0.0001) and

  19. Correlator receiver architecture with PnpN optical thyristor operating as optical hard-limiter

    Science.gov (United States)

    Kang, Tae-Gu; Ho Lee, Su; Park, Soonchul

    2011-07-01

    We propose novel correlator receiver architecture with a PnpN optical thyristor operating as optical hard-limiter, and demonstrate a multiple-access interference rejection of the proposed correlator receiver. The proposed correlator receiver is composed of the 1×2 splitter, optical delay line, 2×1 combiner, and fabricated PnpN optical thyristor. The proposed correlator receiver enhances the system performance because it excludes some combinations of multiple-access interference patterns from causing errors as in optical code-division multiple access systems with conventional optical receiver shown in all previous works. It is found that the proposed correlator receiver can fully reject the interference signals generated by decoding processing and multiple access for two simultaneous users.

  20. The Weiss Functional Impairment Rating Scale-Parent Form for assessing ADHD: evaluating diagnostic accuracy and determining optimal thresholds using ROC analysis.

    Science.gov (United States)

    Thompson, Trevor; Lloyd, Andrew; Joseph, Alain; Weiss, Margaret

    2017-07-01

    The Weiss Functional Impairment Rating Scale-Parent Form (WFIRS-P) is a 50-item scale that assesses functional impairment on six clinically relevant domains typically affected in attention-deficit/hyperactivity disorder (ADHD). As functional impairment is central to ADHD, the WFIRS-P offers potential as a tool for assessing functional impairment in ADHD. These analyses were designed to examine the overall performance of WFIRS-P in differentiating ADHD and non-ADHD cases using receiver operating characteristics (ROC) analysis. This is the first attempt to empirically determine the level of functional impairment that differentiates ADHD children from normal controls. This observational study comprised 5-19-year-olds with physician-diagnosed ADHD (n = 476) and non-ADHD controls (n = 202). ROC analysis evaluated the ability of WFIRS-P to discriminate between ADHD and non-ADHD, and identified a WFIRS-P cut-off score that optimises correct classification. Data were analysed for the complete sample, for males versus females and for participants in two age groups (5-12 versus 13-19 years). Area under the curve (AUC) was 0.91 (95% confidence interval 0.88-0.93) for the overall WFIRS-P score, suggesting highly accurate classification of ADHD distinct from non-ADHD. Sensitivity (0.83) and specificity (0.85) were maximal for a mean overall WFIRS-P score of 0.65, suggesting that this is an appropriate threshold for differentiation. DeLong's test found no significant differences in AUCs for males versus females or 5-12 versus 13-19 years, suggesting that WFIRS-P is an accurate classifier of ADHD across gender and age. When assessing function, WFIRS-P appears to provide a simple and effective basis for differentiating between individuals with/without ADHD in terms of functional impairment. Disease-specific applications of QOL research.

  1. Dynamic thresholds and a summary ROC curve: Assessing prognostic accuracy of longitudinal markers.

    Science.gov (United States)

    Saha-Chaudhuri, P; Heagerty, P J

    2018-04-19

    Cancer patients, chronic kidney disease patients, and subjects infected with HIV are routinely monitored over time using biomarkers that represent key health status indicators. Furthermore, biomarkers are frequently used to guide initiation of new treatments or to inform changes in intervention strategies. Since key medical decisions can be made on the basis of a longitudinal biomarker, it is important to evaluate the potential accuracy associated with longitudinal monitoring. To characterize the overall accuracy of a time-dependent marker, we introduce a summary ROC curve that displays the overall sensitivity associated with a time-dependent threshold that controls time-varying specificity. The proposed statistical methods are similar to concepts considered in disease screening, yet our methods are novel in choosing a potentially time-dependent threshold to define a positive test, and our methods allow time-specific control of the false-positive rate. The proposed summary ROC curve is a natural averaging of time-dependent incident/dynamic ROC curves and therefore provides a single summary of net error rates that can be achieved in the longitudinal setting. Copyright © 2018 John Wiley & Sons, Ltd.

  2. Spatial resolution requirements in digital radiography of scaphoid fractures. An ROC analysis

    International Nuclear Information System (INIS)

    Jonsson, A.; Laurin, S.; Karner, G.; Herrlin, K.; Hochbergs, P.; Jonsson, K.; Rudling, O.; Sandstroem, S.; Sloth, M.; Svahn, G.; Pettersson, H.

    1996-01-01

    Purpose: To investigate the spatial resolution requirements in digital radiography of scaphoid fractures. Material and Methods: Included in the study were 60 scaphoid radiographs with and 60 without fractures of the scaphoid bone. The film-screen images were digitized using pixel sizes of 115, 170, and 340 μm along with 170 μm with a 10:1 wavelet compression. The digital images were displayed on a 1280 x 1024 x 8 bits monitor, and 5 observers evaluated the images in 5 randomized sessions. The results for each pixel size were then compared to the film-screen images by ROC analysis. Results: The mean area under the ROC curves was larger for the film-screen images than for the digital images at all resolutions. However, this difference was not significant when the areas under the ROC curves for the film-screen images were compared to the digital images of 115, 170, and 170 μm with 10:1 compression. There was a significant difference for the 340-μm pixel size in favour of the film-screen images. The mean ROC curves for the digital images were very similar for the 115 and 170 μm pixel sizes, although slightly better for 115 μm. At 170 μm, the compression seemed to have a relatively small negative effect on the diagnostic performance; the deterioration was greater when the pixel size was increased to 340 μm. There was no obvious correlation between diagnostic performance and the experience of the observers in using workstations. Conclusions: The pixel size of 170 μm is adequate for the detection of subtle fractures, even after wavelet compression by a ratio of 10:1. (orig.)

  3. Bayesian receiver operating characteristic estimation of multiple tests for diagnosis of bovine tuberculosis in Chadian cattle.

    Directory of Open Access Journals (Sweden)

    Borna Müller

    Full Text Available BACKGROUND: Bovine tuberculosis (BTB today primarily affects developing countries. In Africa, the disease is present essentially on the whole continent; however, little accurate information on its distribution and prevalence is available. Also, attempts to evaluate diagnostic tests for BTB in naturally infected cattle are scarce and mostly complicated by the absence of knowledge of the true disease status of the tested animals. However, diagnostic test evaluation in a given setting is a prerequisite for the implementation of local surveillance schemes and control measures. METHODOLOGY/PRINCIPAL FINDINGS: We subjected a slaughterhouse population of 954 Chadian cattle to single intra-dermal comparative cervical tuberculin (SICCT testing and two recently developed fluorescence polarization assays (FPA. Using a Bayesian modeling approach we computed the receiver operating characteristic (ROC curve of each diagnostic test, the true disease prevalence in the sampled population and the disease status of all sampled animals in the absence of knowledge of the true disease status of the sampled animals. In our Chadian setting, SICCT performed better if the cut-off for positive test interpretation was lowered from >4 mm (OIE standard cut-off to >2 mm. Using this cut-off, SICCT showed a sensitivity and specificity of 66% and 89%, respectively. Both FPA tests showed sensitivities below 50% but specificities above 90%. The true disease prevalence was estimated at 8%. Altogether, 11% of the sampled animals showed gross visible tuberculous lesions. However, modeling of the BTB disease status of the sampled animals indicated that 72% of the suspected tuberculosis lesions detected during standard meat inspections were due to other pathogens than Mycobacterium bovis. CONCLUSIONS/SIGNIFICANCE: Our results have important implications for BTB diagnosis in a high incidence sub-Saharan African setting and demonstrate the practicability of our Bayesian approach for

  4. fraud detection in mobile communications networks using user

    African Journals Online (AJOL)

    DEPT OF AGRICULTURAL ENGINEERING

    testing the methods with data from real mobile communications networks. Keywords: Call .... System. Monitoring. Database. Database. Fig. 3: Mobile communication detection tools ..... receiver operating characteristic curve (ROC). ROC is a ...

  5. Association of pre-operative medication use with post-operative delirium in surgical oncology patients receiving comprehensive geriatric assessment.

    Science.gov (United States)

    Jeong, Young Mi; Lee, Eunsook; Kim, Kwang-Il; Chung, Jee Eun; In Park, Hae; Lee, Byung Koo; Gwak, Hye Sun

    2016-07-07

    Older patients undergoing surgery tend to have a higher frequency of delirium. Delirium is strongly associated with poor surgical outcomes. This study evaluated the association between pre-operative medication use and post-operative delirium (POD) in surgical oncology patients receiving comprehensive geriatric assessment (CGA). A total of 475 patients who were scheduled for cancer surgery and received CGA from January 2014 to June 2015 were included. Pre-operative medication review through CGA was conducted on polypharmacy (≥5 medications), delirium-inducing medications (DIMs), fall-inducing medications (FIMs), and potentially inappropriate medications (PIMs). POD was confirmed by psychiatric consultation, and DSM-V criteria were used for diagnosing delirium. The model fit of the prediction model was assessed by computing the Hosmer-Lemeshow goodness-of-fit test. Effect size was measured using the Nagelkerke R(2). Discrimination of the model was assessed by an analysis of the area under receiver operating curve (AUROC). Two models were constructed for multivariate analysis based on univariate analysis; model I included dementia and DIM in addition to age and sex, and model II included PIM instead of DIM of model I. Every one year increase of age increased the risk of POD by about 1.1-fold. DIM was a significant factor for POD after adjusting for confounders (AOR 12.78, 95 % CI 2.83-57.74). PIM was also a significant factor for POD (AOR 5.53, 95 % CI 2.03-15.05). The Hosmer-Lemeshow test results revealed good fits for both models (χ(2) = 3.842, p = 0.871 for model I and χ(2) = 8.130, p = 0.421 for model II). The Nagelkerke R(2) effect size and AUROC for model I was 0.215 and 0.833, respectively. Model II had the Nagelkerke R(2)effect size of 0.174 and AUROC of 0.819. These results suggest that pharmacists' comprehensive review for pre-operative medication use is critical for the post-operative outcomes like delirium in older patients.

  6. Long Length Contaminated Equipment Retrieval System Receiver Trailer and Transport Trailer Operations and Maintenance Manual

    International Nuclear Information System (INIS)

    DALE, R.N.

    2000-01-01

    A system to accommodate the removal of long-length contaminated equipment (LLCE) from Hanford underground radioactive waste storage tanks was designed, procured, and demonstrated, via a project activity during the 1990s. The system is the Long Length Contaminated Equipment Removal System (LLCERS). LLCERS will be maintained and operated by Tank Farms Engineering and Operations organizations and other varied projects having a need for the system. The responsibility for the operation and maintenance of the LLCERS Receiver Trailer (RT) and Transport Trailer (TT) resides with the RPP Characterization Project Operations organization. The purpose of this document is to provide vendor supplied operating and maintenance (O and M) information for the RT and TT in a readily retrievable form. This information is provided this way instead of in a vendor information (VI) file to maintain configuration control of the operations baseline as described in RPP-6085, ''Configuration Management Plan for Long Length Contaminated Equipment Receiver and Transport Trailers''. Additional Operations Baseline documents are identified in RPP-6085

  7. Intra-Operative Amylase Concentration in Peri-Pancreatic Fluid Predicts Pancreatic Fistula After Distal Pancreatectomy.

    Science.gov (United States)

    Nahm, Christopher B; de Reuver, Philip R; Hugh, Thomas J; Pearson, Andrew; Gill, Anthony J; Samra, Jaswinder S; Mittal, Anubhav

    2017-06-01

    Post-operative pancreatic fistula (POPF) is a potentially severe complication following distal pancreatectomy. The aim of this study was to assess the predictive value of intra-operative amylase concentration (IOAC) in peri-pancreatic fluid after distal pancreatectomy for the diagnosis of POPF. Consecutive patients who underwent a distal pancreatectomy between November 2014 and September 2016 were included in the analysis. IOAC was measured, followed by drain fluid analysis for amylase on post-operative days (PODs) 1, 3, and 5. Receiver operator characteristic (ROC) analysis was performed to evaluate the discriminative capacity of IOAC as a predictor of POPF. IOAC was measured after distal pancreatectomy in 26 patients. The IOAC correlated significantly with (i) PODs 1, 3, and 5 drain amylase (p  1000 experienced a post-operative complication (OR 18.3, 95% CI 2.51-103, p pancreatectomy.

  8. Long Length Contaminated Equipment Retrieval System Receiver Trailer and Transport Trailer Operations and Maintenance Manual

    Energy Technology Data Exchange (ETDEWEB)

    DALE, R.N.

    2000-05-01

    A system to accommodate the removal of long-length contaminated equipment (LLCE) from Hanford underground radioactive waste storage tanks was designed, procured, and demonstrated, via a project activity during the 1990s. The system is the Long Length Contaminated Equipment Removal System (LLCERS). LLCERS will be maintained and operated by Tank Farms Engineering and Operations organizations and other varied projects having a need for the system. The responsibility for the operation and maintenance of the LLCERS Receiver Trailer (RT) and Transport Trailer (TT) resides with the RPP Characterization Project Operations organization. The purpose of this document is to provide vendor supplied operating and maintenance (O & M) information for the RT and TT in a readily retrievable form. This information is provided this way instead of in a vendor information (VI) file to maintain configuration control of the operations baseline as described in RPP-6085, ''Configuration Management Plan for Long Length Contaminated Equipment Receiver and Transport Trailers''. Additional Operations Baseline documents are identified in RPP-6085.

  9. The Belief Bias Effect Is Aptly Named: A Reply to Klauer and Kellen (2011)

    Science.gov (United States)

    Dube, Chad; Rotello, Caren M.; Heit, Evan

    2011-01-01

    In "Assessing the Belief Bias Effect With ROCs: It's a Response Bias Effect," Dube, Rotello, and Heit (2010) examined the form of receiver operating characteristic (ROC) curves for reasoning and the effects of belief bias on measurement indices that differ in whether they imply a curved or linear ROC function. We concluded that the ROC…

  10. Mutations in the LRRK2 Roc-COR tandem domain link Parkinson's disease to Wnt signalling pathways.

    Science.gov (United States)

    Sancho, Rosa M; Law, Bernard M H; Harvey, Kirsten

    2009-10-15

    Mutations in PARK8, encoding LRRK2, are the most common known cause of Parkinson's disease. The LRRK2 Roc-COR tandem domain exhibits GTPase activity controlling LRRK2 kinase activity via an intramolecular process. We report the interaction of LRRK2 with the dishevelled family of phosphoproteins (DVL1-3), key regulators of Wnt (Wingless/Int) signalling pathways important for axon guidance, synapse formation and neuronal maintenance. Interestingly, DVLs can interact with and mediate the activation of small GTPases with structural similarity to the LRRK2 Roc domain. The LRRK2 Roc-COR domain and the DVL1 DEP domain were necessary and sufficient for LRRK2-DVL1 interaction. Co-expression of DVL1 increased LRRK2 steady-state protein levels, an effect that was dependent on the DEP domain. Strikingly, LRRK2-DVL1-3 interactions were disrupted by the familial PARK8 mutation Y1699C, whereas pathogenic mutations at residues R1441 and R1728 strengthened LRRK2-DVL1 interactions. Co-expression of DVL1 with LRRK2 in mammalian cells resulted in the redistribution of LRRK2 to typical cytoplasmic DVL1 aggregates in HEK293 and SH-SY5Y cells and co-localization in neurites and growth cones of differentiated dopaminergic SH-SY5Y cells. This is the first report of the modulation of a key LRRK2-accessory protein interaction by PARK8 Roc-COR domain mutations segregating with Parkinson's disease. Since the DVL1 DEP domain is known to be involved in the regulation of small GTPases, we propose that: (i) DVLs may influence LRRK2 GTPase activity, and (ii) Roc-COR domain mutations modulating LRRK2-DVL interactions indirectly influence kinase activity. Our findings also link LRRK2 to Wnt signalling pathways, suggesting novel pathogenic mechanisms and new targets for genetic analysis in Parkinson's disease.

  11. Methodology for quantitative evaluation of diagnostic medical imaging

    International Nuclear Information System (INIS)

    Metz, C.

    1980-01-01

    This report deals with the evaluation of the performance of diagnostic medical imaging procedures using the Receiver Operating Characteristic or ROC analysis. The development of new tests for the statistical significance of apparent differences between ROC curves is discussed

  12. Comparative SAXS and DSC study on stratum corneum structural organization in an epidermal cell culture model (ROC)

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Herre, Angela; Fahr, Alfred

    2013-01-01

    barrier similar to that of human stratum corneum is, however, a prerequisite. In this study, the stratum corneum lipid organization in an epidermal cell culture model based on rat epidermal keratinocytes (REK organotypic culture, ROC) was investigated by small-angle X-ray scattering (SAXS) in dependence......Cell cultured skin equivalents present an alternative for dermatological in vitro evaluations of drugs and excipients as they provide the advantage of availability, lower variability and higher assay robustness compared to native skin. For penetration/permeation studies, an adequate stratum corneum...... and SC lipid organization. Cultivation for 21days resulted in further minor changes in the structural organization of ROC SC. The SAXS patterns of ROC SC had overall large similarities with that of human SC and point to the presence of a long periodicity phase with a repeat distance of about 122Å, e...

  13. ROCS: a Reproducibility Index and Confidence Score for Interaction Proteomics Studies

    Directory of Open Access Journals (Sweden)

    Dazard Jean-Eudes

    2012-06-01

    Full Text Available Abstract Background Affinity-Purification Mass-Spectrometry (AP-MS provides a powerful means of identifying protein complexes and interactions. Several important challenges exist in interpreting the results of AP-MS experiments. First, the reproducibility of AP-MS experimental replicates can be low, due both to technical variability and the dynamic nature of protein interactions in the cell. Second, the identification of true protein-protein interactions in AP-MS experiments is subject to inaccuracy due to high false negative and false positive rates. Several experimental approaches can be used to mitigate these drawbacks, including the use of replicated and control experiments and relative quantification to sensitively distinguish true interacting proteins from false ones. Methods To address the issues of reproducibility and accuracy of protein-protein interactions, we introduce a two-step method, called ROCS, which makes use of Indicator Prey Proteins to select reproducible AP-MS experiments, and of Confidence Scores to select specific protein-protein interactions. The Indicator Prey Proteins account for measures of protein identifiability as well as protein reproducibility, effectively allowing removal of outlier experiments that contribute noise and affect downstream inferences. The filtered set of experiments is then used in the Protein-Protein Interaction (PPI scoring step. Prey protein scoring is done by computing a Confidence Score, which accounts for the probability of occurrence of prey proteins in the bait experiments relative to the control experiment, where the significance cutoff parameter is estimated by simultaneously controlling false positives and false negatives against metrics of false discovery rate and biological coherence respectively. In summary, the ROCS method relies on automatic objective criterions for parameter estimation and error-controlled procedures. Results We illustrate the performance of our method by applying

  14. Pre-Operative Prediction of Advanced Prostatic Cancer Using Clinical Decision Support Systems: Accuracy Comparison between Support Vector Machine and Artificial Neural Network

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Youn; Moon, Sung Kyoung; Hwang, Sung Il; Sung, Chang Kyu; Cho, Jeong Yeon; Kim, Seung Hyup; Lee, Hak Jong [Seoul National University College of Medicine, Seoul (Korea, Republic of); Jung, Dae Chul [National Cancer Center, Ilsan (Korea, Republic of); Lee, Ji Won [Kangwon National University College of Medicine, Chuncheon (Korea, Republic of)

    2011-10-15

    The purpose of the current study was to develop support vector machine (SVM) and artificial neural network (ANN) models for the pre-operative prediction of advanced prostate cancer by using the parameters acquired from transrectal ultrasound (TRUS)-guided prostate biopsies, and to compare the accuracies between the two models. Five hundred thirty-two consecutive patients who underwent prostate biopsies and prostatectomies for prostate cancer were divided into the training and test groups (n = 300 versus n 232). From the data in the training group, two clinical decision support systems (CDSSs-[SVM and ANN]) were constructed with input (age, prostate specific antigen level, digital rectal examination, and five biopsy parameters) and output data (the probability for advanced prostate cancer [> pT3a]). From the data of the test group, the accuracy of output data was evaluated. The areas under the receiver operating characteristic (ROC) curve (AUC) were calculated to summarize the overall performances, and a comparison of the ROC curves was performed (p < 0.05). The AUC of SVM and ANN is 0.805 and 0.719, respectively (p = 0.020), in the pre-operative prediction of advanced prostate cancer. Te performance of SVM is superior to ANN in the pre-operative prediction of advanced prostate cancer.

  15. Describing three-class task performance: three-class linear discriminant analysis and three-class ROC analysis

    Science.gov (United States)

    He, Xin; Frey, Eric C.

    2007-03-01

    Binary ROC analysis has solid decision-theoretic foundations and a close relationship to linear discriminant analysis (LDA). In particular, for the case of Gaussian equal covariance input data, the area under the ROC curve (AUC) value has a direct relationship to the Hotelling trace. Many attempts have been made to extend binary classification methods to multi-class. For example, Fukunaga extended binary LDA to obtain multi-class LDA, which uses the multi-class Hotelling trace as a figure-of-merit, and we have previously developed a three-class ROC analysis method. This work explores the relationship between conventional multi-class LDA and three-class ROC analysis. First, we developed a linear observer, the three-class Hotelling observer (3-HO). For Gaussian equal covariance data, the 3- HO provides equivalent performance to the three-class ideal observer and, under less strict conditions, maximizes the signal to noise ratio for classification of all pairs of the three classes simultaneously. The 3-HO templates are not the eigenvectors obtained from multi-class LDA. Second, we show that the three-class Hotelling trace, which is the figureof- merit in the conventional three-class extension of LDA, has significant limitations. Third, we demonstrate that, under certain conditions, there is a linear relationship between the eigenvectors obtained from multi-class LDA and 3-HO templates. We conclude that the 3-HO based on decision theory has advantages both in its decision theoretic background and in the usefulness of its figure-of-merit. Additionally, there exists the possibility of interpreting the two linear features extracted by the conventional extension of LDA from a decision theoretic point of view.

  16. Improvement of diagnostic efficiency in distinguishing the benign and malignant thyroid nodules via conventional ultrasound combined with ultrasound contrast and elastography.

    Science.gov (United States)

    Liu, Mei-Juan; Men, Yan-Ming; Zhang, Yong-Lin; Zhang, Yu-Xi; Liu, Hao

    2017-07-01

    We aimed to evaluate the diagnostic values of conventional ultrasound (US), ultrasound contrast (UC) and ultrasound elastography (UE) in distinguishing the benign and malignant thyroid nodules. A total of 100 patients with thyroid nodules receiving operative treatment were selected; they underwent the conventional US, UE and UC examinations before operation, respectively. The nodules received pathological examination after operation to distinguish benign from malignant lesions. The sensitivity, specificity and diagnostic accordance rate of each diagnostic method was evaluated by receiver operating characteristic (ROC) curve, and the area under the curve (AUC) of ROC was calculated. The manifestations of malignant thyroid nodules in conventional US examination were mostly the hypoecho, heterogeneous echo, irregular shape, unclear boundary, aspect ratio benign and malignant nodules in 2, 3 and 4 points were statistically significant (Pbenign and malignant thyroid nodules.

  17. A modified Wald interval for the area under the ROC curve (AUC) in diagnostic case-control studies.

    Science.gov (United States)

    Kottas, Martina; Kuss, Oliver; Zapf, Antonia

    2014-02-19

    The area under the receiver operating characteristic (ROC) curve, referred to as the AUC, is an appropriate measure for describing the overall accuracy of a diagnostic test or a biomarker in early phase trials without having to choose a threshold. There are many approaches for estimating the confidence interval for the AUC. However, all are relatively complicated to implement. Furthermore, many approaches perform poorly for large AUC values or small sample sizes. The AUC is actually a probability. So we propose a modified Wald interval for a single proportion, which can be calculated on a pocket calculator. We performed a simulation study to compare this modified Wald interval (without and with continuity correction) with other intervals regarding coverage probability and statistical power. The main result is that the proposed modified Wald intervals maintain and exploit the type I error much better than the intervals of Agresti-Coull, Wilson, and Clopper-Pearson. The interval suggested by Bamber, the Mann-Whitney interval without transformation and also the interval of the binormal AUC are very liberal. For small sample sizes the Wald interval with continuity has a comparable coverage probability as the LT interval and higher power. For large sample sizes the results of the LT interval and of the Wald interval without continuity correction are comparable. If individual patient data is not available, but only the estimated AUC and the total sample size, the modified Wald intervals can be recommended as confidence intervals for the AUC. For small sample sizes the continuity correction should be used.

  18. Eyewitness identification in simultaneous and sequential lineups: an investigation of position effects using receiver operating characteristics.

    Science.gov (United States)

    Meisters, Julia; Diedenhofen, Birk; Musch, Jochen

    2018-04-20

    For decades, sequential lineups have been considered superior to simultaneous lineups in the context of eyewitness identification. However, most of the research leading to this conclusion was based on the analysis of diagnosticity ratios that do not control for the respondent's response criterion. Recent research based on the analysis of ROC curves has found either equal discriminability for sequential and simultaneous lineups, or higher discriminability for simultaneous lineups. Some evidence for potential position effects and for criterion shifts in sequential lineups has also been reported. Using ROC curve analysis, we investigated the effects of the suspect's position on discriminability and response criteria in both simultaneous and sequential lineups. We found that sequential lineups suffered from an unwanted position effect. Respondents employed a strict criterion for the earliest lineup positions, and shifted to a more liberal criterion for later positions. No position effects and no criterion shifts were observed in simultaneous lineups. This result suggests that sequential lineups are not superior to simultaneous lineups, and may give rise to unwanted position effects that have to be considered when conducting police lineups.

  19. Medical decision making tools: Bayesian analysis and ROC analysis

    International Nuclear Information System (INIS)

    Lee, Byung Do

    2006-01-01

    During the diagnostic process of the various oral and maxillofacial lesions, we should consider the following: 'When should we order diagnostic tests? What tests should be ordered? How should we interpret the results clinically? And how should we use this frequently imperfect information to make optimal medical decision?' For the clinicians to make proper judgement, several decision making tools are suggested. This article discusses the concept of the diagnostic accuracy (sensitivity and specificity values) with several decision making tools such as decision matrix, ROC analysis and Bayesian analysis. The article also explain the introductory concept of ORAD program

  20. SAG/ROC-SCFβ-TrCP E3 Ubiquitin Ligase Promotes Pro-Caspase-3 Degradation as a Mechanism of Apoptosis Protection

    Directory of Open Access Journals (Sweden)

    Mingjia Tan

    2006-12-01

    Full Text Available Skp1-cullin-F-box protein (SCF is a multicomponent E3 ubiquitin (Ub ligase that ubiquitinates a number of important biologic molecules such as p27, β-catenin, and lκB for proteasomal degradation, thus regulating cell proliferation and survival. One SCF component, SAG/ROC2/Rbx2/Hrt2, a RING finger protein, was first identified as a redox-inducible protein, which, when overexpressed, inhibited apoptosis both in vitro and in vivo. We report here that sensitive to apoptosis gene (SAG, as well as its family member ROC1/Rbxi, bound to the proinactive form of caspase-3 (pro-caspase-3. Binding was likely mediated through F-box protein, β-transducin repeat-containing protein (β-TrCP, which binds to the first 38 amino acids of pro-caspase-3. Importantly, β-TrCP1 expression significantly shortened the protein half-life of pro-caspase-3, whereas expression of a dominant-negative β-TrCP1 mutant with the F-box domain deleted extended it. An in vitro ubiquitination assay showed that SAG/ROC-SCF -Trcp promoted ubiquitination of pro-caspase-3. Furthermore, endogenous levels of pro-caspase-3 were decreased by overexpression of SAG/ROC-SCFβ-TrCP E3 Ub ligases, but increased on siRNA silencing of SAG, regulator of cullin-1 (ROC1, or β-TrCPs, leading to increased apoptosis by etoposide and TNF-related apoptosis-inducing ligand through increased activation of caspase-3. Thus, pro-caspase-3 appears to be a substrate of SAG/ROC-SCFβ-TrCP E3 Ub ligase, which protects cells from apoptosis through increased apoptosis threshold by reducing the basal level of pro-caspase-3.

  1. Operating conditions of an open and direct solar thermal Brayton cycle with optimised cavity receiver and recuperator

    International Nuclear Information System (INIS)

    Le Roux, W.G.; Bello-Ochende, T.; Meyer, J.P.

    2011-01-01

    The small-scale open and direct solar thermal Brayton cycle with recuperator has several advantages, including low cost, low operation and maintenance costs and it is highly recommended. The main disadvantages of this cycle are the pressure losses in the recuperator and receiver, turbomachine efficiencies and recuperator effectiveness, which limit the net power output of such a system. The irreversibilities of the solar thermal Brayton cycle are mainly due to heat transfer across a finite temperature difference and fluid friction. In this paper, thermodynamic optimisation is applied to concentrate on these disadvantages in order to optimise the receiver and recuperator and to maximise the net power output of the system at various steady-state conditions, limited to various constraints. The effects of wind, receiver inclination, rim angle, atmospheric temperature and pressure, recuperator height, solar irradiance and concentration ratio on the optimum geometries and performance were investigated. The dynamic trajectory optimisation method was applied. Operating points of a standard micro-turbine operating at its highest compressor efficiency and a parabolic dish concentrator diameter of 16 m were considered. The optimum geometries, minimum irreversibility rates and maximum receiver surface temperatures of the optimised systems are shown. For an environment with specific conditions and constraints, there exists an optimum receiver and recuperator geometry so that the system produces maximum net power output. -- Highlights: → Optimum geometries exist such that the system produces maximum net power output. → Optimum operating conditions are shown. → Minimum irreversibility rates and minimum entropy generation rates are shown. → Net power output was described in terms of total entropy generation rate. → Effects such as wind, recuperator height and irradiance were investigated.

  2. Physiologic Waveform Analysis for Early Detection of Hemorrhage during Transport and Higher Echelon Medical Care of Combat Casualties

    Science.gov (United States)

    2014-03-01

    area under the curve (ROC AUC ) values. (ROC AUC values range from 0 and 1 and indicate the probability of correct detection/discrimination...training set of the human LBNP data. Values are receiver operating characteristic area under the curves (ROC AUCs ) comparing the relative SV change...detection of hemorrhage is crucial for managing combat casualties. However, mean arterial blood pressure (ABP) and other vital signs are late indicators of

  3. Acurácia de critérios para vagotonia no eletrocardiograma de repouso de 12 derivações: uma análise com curvas ROC Accuracy of vagotonia criteria in the 12-lead resting electrocardiogram: analysis with ROC curves

    Directory of Open Access Journals (Sweden)

    José Kawazoe Lazzoli

    2002-04-01

    Full Text Available OBJETIVO: Determinar a sensibilidade, a especificidade, os valores preditivos positivo e negativo e a acurácia de diferentes critérios eletrocardiográficos para vagotonia. MÉTODOS: Foram avaliados 74 atletas olímpicos brasileiros (51 homens e 23 mulheres com idade entre 16 e 42 anos (24 ± 5 anos, tendo sido realizados, entre outros exames, um ECG de repouso de 12 derivações e uma avaliação do tônus vagal cardíaco (TVC pelo teste de exercício sem carga de quatro segundos (T4s, cujo índice B/C (indicativo da magnitude do TVC foi utilizado como padrão-ouro. O T4s é um teste que se baseia no mecanismo da taquicardia inicial do exercício e foi anteriormente padronizado e validado como capaz de avaliar o TVC sem influência do componente simpático. Dados de 10 atletas foram excluídos devido à presença de critérios ecocardiográficos para hipertrofia ventricular esquerda, ainda que provavelmente fisiológica. Com o auxílio de curvas ROC (receiver operating characteristic, selecionou-se o ponto de corte com a melhor combinação entre sensibilidade (Sens e especificidade (Esp para cada variável do ECG, calculando-se os valores preditivos positivo (VPP e negativo (VPN e a acurácia (AC. Foram ainda correlacionados o índice B/C e as variáveis do ECG. RESULTADOS: Há fraca associação entre o índice B/C e as variáveis do ECG, à exceção da duração do intervalo R-R (r = 0,353; P = 0,004, que também apresentou curva ROC significativa (chi2= 0,863; P = 0,002, sendo que o critério intervalo R-R > ou = 990ms apresentou os seguintes resultados: Sens - 100%; Esp - 73%; VPP 20%; VPN 100%; AC 75%. As variáveis do ECG que apresentaram pontos de corte com acurácia > 80% foram: amplitude da onda T em V5 > ou = 8,0mm; amplitude da onda T em V6 > ou = 7,0mm; amplitude da onda Q em V5 > ou = 7,0mm; amplitude da onda R em V4 > ou = 50,0mm; presença de supradesnível de ponto J em duas ou mais derivações; presença de supradesn

  4. Sex differences in the prediction of the effectiveness of paroxetine for patients with major depressive disorder identified using a receiver operating characteristic curve analysis for early response.

    Science.gov (United States)

    Tomita, Tetsu; Yasui-Furukori, Norio; Norio, Yasui-Furukori; Sato, Yasushi; Nakagami, Taku; Tsuchimine, Shoko; Kaneda, Ayako; Kaneko, Sunao

    2014-01-01

    We investigated cutoff values for the early response of patients with major depressive disorder to paroxetine and their sex differences by using a receiver operating characteristic (ROC) curve analysis to predict the effectiveness of paroxetine. In total, 120 patients with major depressive disorder were enrolled and treated with 10-40 mg/day paroxetine for 6 weeks; 89 patients completed the protocol. A clinical evaluation using the Montgomery-Asberg Depression Rating Scale (MADRS) was performed at weeks 0, 1, 2, 4, and 6. In male subjects, the cutoff values for MADRS improvement rating in week 1, week 2, and week 4 were 20.9%, 34.9%, and 33.3%, respectively. The sensitivities and the specificities were 83.3% and 80.0%, 83.3% and 80.0%, and 100% and 90%, respectively. The areas under the curve (AUC) were 0.908, 0.821, and 0.979, respectively. In female subjects, the cutoff values for the MADRS improvement rating in week 1, week 2, and week 4 were 21.4%, 35.7%, and 32.3%, respectively. The sensitivities and the specificities were 71.4% and 84.6%, 73.8% and 76.9%, and 90.5% and 76.9%, respectively. The AUCs were 0.781, 0.735, and 0.904, respectively. Early improvement with paroxetine may predict the long-term response. The accuracy of the prediction for the response is higher in male subjects.

  5. Recognition Errors Suggest Fast Familiarity and Slow Recollection in Rhesus Monkeys

    Science.gov (United States)

    Basile, Benjamin M.; Hampton, Robert R.

    2013-01-01

    One influential model of recognition posits two underlying memory processes: recollection, which is detailed but relatively slow, and familiarity, which is quick but lacks detail. Most of the evidence for this dual-process model in nonhumans has come from analyses of receiver operating characteristic (ROC) curves in rats, but whether ROC analyses…

  6. iROCS: Integrated accident management framework for coping with beyond-design-basis external events

    International Nuclear Information System (INIS)

    Kim, Jaewhan; Park, Soo-Yong; Ahn, Kwang-Il; Yang, Joon-Eon

    2016-01-01

    Highlights: • An integrated mitigating strategy to cope with extreme external events, iROCS, is proposed. • The strategy aims to preserve the integrity of the reactor vessel as well as core cooling. • A case study for an extreme damage state is performed to assess the effectiveness and feasibility of candidate mitigation strategies under an extreme event. - Abstract: The Fukushima Daiichi accident induced by the Great East Japan earthquake and tsunami on March 11, 2011, poses a new challenge to the nuclear society, especially from an accident management viewpoint. This paper presents a new accident management framework called an integrated, RObust Coping Strategy (iROCS) to cope with beyond-design-basis external events (BDBEEs). The iROCS approach is characterized by classification of various plant damage conditions (PDCs) that might be impacted by BDBEEs and corresponding integrated coping strategies for each of PDCs, aiming to maintain and restore core cooling (i.e., to prevent core damage) and to maintain the integrity of the reactor pressure vessel if it is judged that core damage may not be preventable in view of plant conditions. From a case study for an extreme damage condition, it showed that candidate accident management strategies should be evaluated from the viewpoint of effectiveness and feasibility against accident scenarios and extreme damage conditions of the site, especially when employing mobile or portable equipment under BDBEEs within the limited time available to achieve desired goals such as prevention of core damage as well as a reactor vessel failure.

  7. Glutamate dehydrogenase (RocG) in Bacillus licheniformis WX-02: Enzymatic properties and specific functions in glutamic acid synthesis for poly-γ-glutamic acid production.

    Science.gov (United States)

    Tian, Guangming; Wang, Qin; Wei, Xuetuan; Ma, Xin; Chen, Shouwen

    2017-04-01

    Poly-γ-glutamic acid (γ-PGA), a natural biopolymer, is widely used in cosmetics, medicine, food, water treatment, and agriculture owing to its features of moisture sequestration, cation chelation, non-toxicity and biodegradability. Intracellular glutamic acid, the substrate of γ-PGA, is a limiting factor for high yield in γ-PGA production. Bacillus subtilis and Bacillus licheniformis are both important γ-PGA producing strains, and B. subtilis synthesizes glutamic acid in vivo using the unique GOGAT/GS pathway. However, little is known about the glutamate synthesis pathway in B. licheniformis. The aim of this work was to characterize the glutamate dehydrogenase (RocG) in glutamic acid synthesis from B. licheniformis with both in vivo and in vitro experiments. By re-directing the carbon flux distribution, the rocG gene deletion mutant WX-02ΔrocG produced intracellular glutamic acid with a concentration of 90ng/log(CFU), which was only 23.7% that of the wild-type WX-02 (380ng/log(CFU)). Furthermore, the γ-PGA yield of mutant WX-02ΔrocG was 5.37g/L, a decrease of 45.3% compared to the wild type (9.82g/L). In vitro enzymatic assays of RocG showed that RocG has higher affinity for 2-oxoglutarate than glutamate, and the glutamate synthesis rate was far above degradation. This is probably the first study to reveal the glutamic acid synthesis pathway and the specific functions of RocG in B. licheniformis. The results indicate that γ-PGA production can be enhanced through improving intracellular glutamic acid synthesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Operating characteristics of depression and anxiety disorder phenotype dimensions and trait neuroticism: a theoretical examination of the fear and distress disorders from the Netherlands study of depression and anxiety.

    Science.gov (United States)

    Tully, Phillip J; Wardenaar, Klaas J; Penninx, Brenda W J H

    2015-03-15

    The receiver operating characteristics (ROC) of anhedonic depression and anxious arousal to detect the distress- (major depression, dysthymia, generalized anxiety disorder) and fear-disorder clusters (i.e. panic disorder, agoraphobia, social phobia) have not been reported in a large sample. A sample of 2981 persons underwent structured psychiatric interview; n=652 were without lifetime depression and anxiety disorder history. Participants also completed a neuroticism scale (Revised NEO Five Factor Inventory [NEO-FFI]), and the 30-item short adaptation of the Mood and Anxiety Symptoms Questionnaire (MASQ-D30) measuring anhedonic depression, anxious arousal and general distress. Maximal sensitivity and specificity was determined by the Youden Index and the area-under-the-curve (AUC) in ROC analysis. A total of 2624 completed all measures (age M=42.4 years±13.1, 1760 females [67.1%]), including 1060 (40.4%) persons who met criteria for a distress-disorder, and 973 (37.1%) who met criteria for a fear-disorder. The general distress dimension provided the highest ROC values in the detection of the distress-disorders (AUC=.814, sensitivity=71.95%, specificity=76.34%, positive predictive value=67.33, negative predictive value=80.07). None of the measures provided suitable operating characteristics in the detection of the fear-disorders with specificity values depression and anxiety disorders may lead to inflated positive- and negative predictive values. The MASQ-D30 general distress dimension showed clinically suitable operating characteristics in the detection of distress-disorders. Neither neuroticism nor the MASQ-D30 dimensions provided suitable operating characteristics in the detection of the fear-disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Life-Long Cyberlearning System: A Pilot Project for the "Learning Society" in the ROC.

    Science.gov (United States)

    Han, Huei-Wen; Wang, Yen-Chao

    1999-01-01

    Provides an overview of the implementation of lifelong learning in Taiwan, Republic of China (ROC) as part of its educational reform policy and describes a pilot project, the Lifelong Cyberlearning System. Highlights include planning architecture, Web-based learning technology, professional education, industrial and corporate assistance, and…

  10. 25 CFR 47.3 - How does a Bureau-operated school find out how much funding it will receive?

    Science.gov (United States)

    2010-04-01

    ... EDUCATION UNIFORM DIRECT FUNDING AND SUPPORT FOR BUREAU-OPERATED SCHOOLS § 47.3 How does a Bureau-operated school find out how much funding it will receive? The Office of Indian Education Programs (OIEP) will... 25 Indians 1 2010-04-01 2010-04-01 false How does a Bureau-operated school find out how much...

  11. Correlation of Serum Cystatin C with Glomerular Filtration Rate in Patients Receiving Platinum-Based Chemotherapy

    Directory of Open Access Journals (Sweden)

    Ernesta Cavalcanti

    2016-01-01

    Full Text Available Objectives. Serum cystatin C seems to be an accurate marker of glomerular filtration rate (GFR compared to serum creatinine. The aim of this work was to explore the possibility of using serum cystatin C instead of serum creatinine to early predict renal failure in cancer patients who received platinum based chemotherapy. Design and Methods. Serum creatinine, serum cystatin C concentrations, and GFR were determined simultaneously in 52 cancer patients received carboplatin-based or cisplatin-based chemotherapy. Serum creatinine was assayed on Cobas C6000-Roche, serum cystatin C assay was performed on AIA 360-Tosoh, and GFR was determined in all patients, before the first cycle of chemotherapy and before the subsequent administrations. Results. In the overall series, for the prediction of a fall of GFR < 80 mL/min/1.73 m2, the AUC of the ROC curve for cystatin C was 0,667 and the best threshold was 1.135 mg/L (sensitivity 90.5%, specificity 61.1%. For a GFR fall < 60 mL/min/1.73 m2, the AUC of ROC curve for cystatin C was 74.3% and the best threshold was 1.415 mg/L (sensitivity 66.7%, specificity 73.2%. Conclusions. Baseline cystatin C values were not able to predict renal failure during subsequent treatment. In conclusion, serum cystatin C is not a reliable early marker to efficiently predict renal failure in patients receiving chemotherapy.

  12. Dual-time point scanning of integrated FDG PET/CT for the evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT

    International Nuclear Information System (INIS)

    Kasai, Takami; Motoori, Ken; Horikoshi, Takuro; Uchiyama, Katsuhiro; Yasufuku, Kazuhiro; Takiguchi, Yuichi; Takahashi, Fumiaki; Kuniyasu, Yoshio; Ito, Hisao

    2010-01-01

    Purpose: To evaluate whether dual-time point scanning with integrated fluorine-18 fluorodeoxyglucose ( 18 F-FDG) positron emission tomography and computed tomography (PET/CT) is useful for evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT. Materials and methods: PET/CT data and pathological findings of 560 nodal stations in 129 patients with pathologically proven non-small cell lung cancer diagnosed as operable by contrast-enhanced CT were reviewed retrospectively. Standardized uptake values (SUVs) on early scans (SUVe) 1 h, and on delayed scans (SUVd) 2 h after FDG injection of each nodal station were measured. Retention index (RI) (%) was calculated by subtracting SUVe from SUVd and dividing by SUVe. Logistic regression analysis was performed with seven kinds of models, consisting of (1) SUVe, (2) SUVd, (3) RI, (4) SUVe and SUVd, (5) SUVe and RI, (6) SUVd and RI, and (7) SUVe, SUVd and RI. The seven derived models were compared by receiver-operating characteristic (ROC) analysis. k-Fold cross-validation was performed with k values of 5 and 10. p < 0.05 was considered statistically significant. Results: Model (1) including the term of SUVe showed the largest area under the ROC curve among the seven models. The cut-off probability of metastasis of 3.5% with SUVe of 2.5 revealed a sensitivity of 78% and a specificity of 81% on ROC analysis, and approximately 60% and 80% on k-fold cross-validation. Conclusion: Single scanning of PET/CT is sufficiently useful for evaluating mediastinal and hilar nodes for metastasis.

  13. Receiver Operating Characteristic Analysis for Classification Based on Various Prior Probabilities of Groups with an Application to Breath Analysis

    Science.gov (United States)

    Cimermanová, K.

    2009-01-01

    In this paper we illustrate the influence of prior probabilities of diseases on diagnostic reasoning. For various prior probabilities of classified groups characterized by volatile organic compounds of breath profile, smokers and non-smokers, we constructed the ROC curve and the Youden index with related asymptotic pointwise confidence intervals.

  14. Optimal Threshold Determination for Discriminating Driving Anger Intensity Based on EEG Wavelet Features and ROC Curve Analysis

    Directory of Open Access Journals (Sweden)

    Ping Wan

    2016-08-01

    Full Text Available Driving anger, called “road rage”, has become increasingly common nowadays, affecting road safety. A few researches focused on how to identify driving anger, however, there is still a gap in driving anger grading, especially in real traffic environment, which is beneficial to take corresponding intervening measures according to different anger intensity. This study proposes a method for discriminating driving anger states with different intensity based on Electroencephalogram (EEG spectral features. First, thirty drivers were recruited to conduct on-road experiments on a busy route in Wuhan, China where anger could be inducted by various road events, e.g., vehicles weaving/cutting in line, jaywalking/cyclist crossing, traffic congestion and waiting red light if they want to complete the experiments ahead of basic time for extra paid. Subsequently, significance analysis was used to select relative energy spectrum of β band (β% and relative energy spectrum of θ band (θ% for discriminating the different driving anger states. Finally, according to receiver operating characteristic (ROC curve analysis, the optimal thresholds (best cut-off points of β% and θ% for identifying none anger state (i.e., neutral were determined to be 0.2183 ≤ θ% < 1, 0 < β% < 0.2586; low anger state is 0.1539 ≤ θ% < 0.2183, 0.2586 ≤ β% < 0.3269; moderate anger state is 0.1216 ≤ θ% < 0.1539, 0.3269 ≤ β% < 0.3674; high anger state is 0 < θ% < 0.1216, 0.3674 ≤ β% < 1. Moreover, the discrimination performances of verification indicate that, the overall accuracy (Acc of the optimal thresholds of β% for discriminating the four driving anger states is 80.21%, while 75.20% for that of θ%. The results can provide theoretical foundation for developing driving anger detection or warning devices based on the relevant optimal thresholds.

  15. Autonomous Operation of Super-Regenerative Receiver in BAN

    NARCIS (Netherlands)

    Kalyanasundaram, P.; Huang, L.; Dolmans, G.; Imamura, K.

    2012-01-01

    Super-regenerative receiver is one of the potential candidates to achieve ultra low power wireless communication in body area network (BAN). The main limitations of the super-regenerative receiver include the difficulty in choosing a good quench waveform to optimize its sensitivity and selectivity,

  16. A Study on the Deriving Requirements of ARGO Operation System

    Directory of Open Access Journals (Sweden)

    Yoon-Kyung Seo

    2009-12-01

    Full Text Available Korea Astronomy and Space Science Institute (KASI has been developing one mobile and one stationary SLR system since 2008 named as ARGO-M and ARGO-F, respectively. KASI finished the step of deriving the system requirements of ARGO. The requirements include definitions and scopes of various software and hardware components which are necessary for developing the ARGO-M operation system. And the requirements define function, performance, and interface requirements. The operation system consisting of ARGO-M site, ARGO-F site, and Remote Operation Center (ROC inside KASI is designed for remote access and the automatic tracking and control system which are the main operation concept of ARGO system. To accomplish remote operation, we are considering remote access to ARGO-F and ARGO-M from ROC. The mobile-phone service allows us to access the ARGO-F remotely and to control the system in an emergency. To implement fully automatic tracking and control function in ARGO-F, we have investigated and described the requirements about the automatic aircraft detection system and the various meteorological sensors. This paper addresses the requirements of ARGO Operation System.

  17. Receiver-exciter controller design

    Science.gov (United States)

    Jansma, P. A.

    1982-01-01

    A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

  18. An Optical Receiver Post Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

    Science.gov (United States)

    Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

    2016-01-01

    The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administrations (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

  19. An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

    Science.gov (United States)

    Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

    2016-01-01

    The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

  20. Dual-time point scanning of integrated FDG PET/CT for the evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Takami, E-mail: takaby@hotmail.co [Department of Radiology, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8677 (Japan); Motoori, Ken, E-mail: motoorik@faculty.chiba-u.j [Department of Radiology, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8677 (Japan); Horikoshi, Takuro, E-mail: taku_steelfish@yahoo.co.j [Department of Radiology, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8677 (Japan); Uchiyama, Katsuhiro, E-mail: ka-uchiyama@nifty.co [Diagnostic PET Imaging Center, Department of Radiology, Sannoh Medical Center, 166-2 Sannohcho, Inage-ku, Chiba City, Chiba-ken 263-0002 (Japan); Yasufuku, Kazuhiro, E-mail: kyasufuku@faculty.chiba-u.j [Department of Thoracic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8670 (Japan); Takiguchi, Yuichi, E-mail: takiguchi@faculty.chiba-u.j [Department of Respirology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8670 (Japan); Takahashi, Fumiaki, E-mail: takahashifu@pharm.kitasato-u.ac.j [Division of Biostatistics, Graduate School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641 (Japan); Kuniyasu, Yoshio, E-mail: kuniyasu@ace.ocn.ne.j [Diagnostic PET Imaging Center, Department of Radiology, Sannoh Medical Center, 166-2 Sannohcho, Inage-ku, Chiba City, Chiba-ken 263-0002 (Japan); Ito, Hisao, E-mail: hisao@faculty.chiba-u.j [Department of Radiology, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba-ken 260-8677 (Japan)

    2010-08-15

    Purpose: To evaluate whether dual-time point scanning with integrated fluorine-18 fluorodeoxyglucose ({sup 18}F-FDG) positron emission tomography and computed tomography (PET/CT) is useful for evaluation of mediastinal and hilar lymph nodes in non-small cell lung cancer diagnosed as operable by contrast-enhanced CT. Materials and methods: PET/CT data and pathological findings of 560 nodal stations in 129 patients with pathologically proven non-small cell lung cancer diagnosed as operable by contrast-enhanced CT were reviewed retrospectively. Standardized uptake values (SUVs) on early scans (SUVe) 1 h, and on delayed scans (SUVd) 2 h after FDG injection of each nodal station were measured. Retention index (RI) (%) was calculated by subtracting SUVe from SUVd and dividing by SUVe. Logistic regression analysis was performed with seven kinds of models, consisting of (1) SUVe, (2) SUVd, (3) RI, (4) SUVe and SUVd, (5) SUVe and RI, (6) SUVd and RI, and (7) SUVe, SUVd and RI. The seven derived models were compared by receiver-operating characteristic (ROC) analysis. k-Fold cross-validation was performed with k values of 5 and 10. p < 0.05 was considered statistically significant. Results: Model (1) including the term of SUVe showed the largest area under the ROC curve among the seven models. The cut-off probability of metastasis of 3.5% with SUVe of 2.5 revealed a sensitivity of 78% and a specificity of 81% on ROC analysis, and approximately 60% and 80% on k-fold cross-validation. Conclusion: Single scanning of PET/CT is sufficiently useful for evaluating mediastinal and hilar nodes for metastasis.

  1. How should we screen for depression following a natural disaster? An ROC approach to post-disaster screening in adolescents and adults.

    Science.gov (United States)

    Cohen, Joseph R; Adams, Zachary W; Menon, Suvarna V; Youngstrom, Eric A; Bunnell, Brian E; Acierno, Ron; Ruggiero, Kenneth J; Danielson, Carla Kmett

    2016-09-15

    The present study's aim was to provide the foundation for an efficient, empirically based protocol for depression screening following a natural disaster. Utilizing a Receiver Operating Characteristic (ROC) analytic approach, the study tested a) what specific disaster-related stressors (i.e., property damage, loss of basic services) and individual-related constructs (i.e., PTSD symptoms, trauma history, social support) conveyed the greatest risk for post-natural disaster depression, b) specific cutoff scores across these measures, and c) whether the significance or cutoff scores for each construct varied between adolescents and adults. Structured phone-based clinical interviews were conducted with 2000 adolescents who lived through a tornado and 1543 adults who survived a hurricane. Findings suggested that in both adolescents and adults, individual-related constructs forecasted greater risk for depressive symptoms following a natural disaster compared to disaster-related stressors. Furthermore, trauma history and PTSD symptoms were particularly strong indicators for adolescent depressive symptoms compared to adult depressive symptoms. Adolescents and adults who reported vulnerable scores for social support, trauma history, and lifetime PTSD symptoms were approximately twice as likely to present as depressed following the natural disaster. Findings from the present study were limited to post-disaster assessments and based on self-reported functioning 6-12 months following the natural disaster. The present study synthesizes the extensive body of research on post-disaster functioning by providing a clear framework for which questions may be most important to ask when screening for depression following a natural disaster. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Wideband CMOS receivers

    CERN Document Server

    Oliveira, Luis

    2015-01-01

    This book demonstrates how to design a wideband receiver operating in current mode, in which the noise and non-linearity are reduced, implemented in a low cost single chip, using standard CMOS technology.  The authors present a solution to remove the transimpedance amplifier (TIA) block and connect directly the mixer’s output to a passive second-order continuous-time Σ∆ analog to digital converter (ADC), which operates in current-mode. These techniques enable the reduction of area, power consumption, and cost in modern CMOS receivers.

  3. Customizable Digital Receivers for Radar

    Science.gov (United States)

    Moller, Delwyn; Heavey, Brandon; Sadowy, Gregory

    2008-01-01

    Compact, highly customizable digital receivers are being developed for the system described in 'Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets' (NPO-43962), NASA Tech Briefs, Vol. 31, No. 7 (August 2007), page 72. The receivers are required to operate in unison, sampling radar returns received by the antenna elements in a digital beam-forming (DBF) mode. The design of these receivers could also be adapted to commercial radar systems. At the time of reporting the information for this article, there were no commercially available digital receivers capable of satisfying all of the operational requirements and compact enough to be mounted directly on the antenna elements. A provided figure depicts the overall system of which the digital receivers are parts. Each digital receiver includes an analog-to-digital converter (ADC), a demultiplexer (DMUX), and a field-programmable gate array (FPGA). The ADC effects 10-bit band-pass sampling of input signals having frequencies up to 3.5 GHz. The input samples are demultiplexed at a user-selectable rate of 1:2 or 1:4, then buffered in part of the FPGA that functions as a first-in/first-out (FIFO) memory. Another part of the FPGA serves as a controller for the ADC, DMUX, and FIFO memory and as an interface between (1) the rest of the receiver and (2) a front-panel data port (FPDP) bus, which is an industry-standard parallel data bus that has a high data-rate capability and multichannel configuration suitable for DBF. Still other parts of the FPGA in each receiver perform signal-processing functions. The digital receivers can be configured to operate in a stand-alone mode, or in a multichannel mode as needed for DBF. The customizability of the receiver makes it applicable to a broad range of system architectures. The capability for operation of receivers in either a stand-alone or a DBF mode enables the use of the receivers in an unprecedentedly wide variety of radar systems.

  4. Evaluating the Performance of Multiple Classifier Systems: A Matrix Algebra Representation of Boolean Fusion Rules

    National Research Council Canada - National Science Library

    Hill, Justin

    2003-01-01

    ...., a logical OR, AND, or a majority vote of the classifiers in the system). An established method for evaluating a classifier is measuring some aspect of its Receiver Operating Characteristic (ROC...

  5. STUDY ON THE ACCOUNTING OF ADJUSTMENTS FOR RECEIVABLES DEPRECIATION IN OPERATIONS WITH CLIENTS

    Directory of Open Access Journals (Sweden)

    ILIE RĂSCOLEAN

    2015-12-01

    Full Text Available The present work approaches an important topic for credit institutions: limiting the credit risk and determining the prudential value adjustments for the depreciation of client credits, and their reflection in the accounting statements. The Chart of Accounts applicable to credit institutions includes class-two accounts Operations with clients and expenses and revenues accounts, which help record the adjustments for receivables depreciation in operations with clients. To constitute, diminish or annul depreciations, credit institutions have the obligation to assure the classification of their credits based on classification categories according to three criteria: financial performance, debt service and initiation of juridical procedures. By the present study, we present the way the credit portfolio is structured according to the criteria mentioned and the reflection in accounting of the prudential adjustments of value. The article ends with the authors’ conclusions regarding the specificity of the way of classification of the credits according to risk categories in agreement to the evolution of the class determination criteria.

  6. Análisis de puntos de rocío y contenidos de humedad de mezclas gaseosas N2-H2O y CH4-H2O

    OpenAIRE

    D. Bogoya M.; C. Müller, I. Q.; L. R. Oellrich

    1995-01-01

    EI conocimiento actual del contenido de humedad de mezclas gaseosas saturadas es aún incompleto, especialmente en la región de altas presiones y bajas temperaturas. Por tanto se realizaron medidas experimentales de punta de rocío con los sistemas nitrógeno-agua y metano-agua, a presiones de 3 y 6 MPa y a temperaturas de 258 K a 288 K. Los puntos de rocío se determinaron con el método del espejo de punta de rocío y los contenidos de humedad por medio de la titulación de Karl-Fischer. Los valor...

  7. Not proper ROC curves as new tool for the analysis of differentially expressed genes in microarray experiments

    Directory of Open Access Journals (Sweden)

    Pistoia Vito

    2008-10-01

    Full Text Available Abstract Background Most microarray experiments are carried out with the purpose of identifying genes whose expression varies in relation with specific conditions or in response to environmental stimuli. In such studies, genes showing similar mean expression values between two or more groups are considered as not differentially expressed, even if hidden subclasses with different expression values may exist. In this paper we propose a new method for identifying differentially expressed genes, based on the area between the ROC curve and the rising diagonal (ABCR. ABCR represents a more general approach than the standard area under the ROC curve (AUC, because it can identify both proper (i.e., concave and not proper ROC curves (NPRC. In particular, NPRC may correspond to those genes that tend to escape standard selection methods. Results We assessed the performance of our method using data from a publicly available database of 4026 genes, including 14 normal B cell samples (NBC and 20 heterogeneous lymphomas (namely: 9 follicular lymphomas and 11 chronic lymphocytic leukemias. Moreover, NBC also included two sub-classes, i.e., 6 heavily stimulated and 8 slightly or not stimulated samples. We identified 1607 differentially expressed genes with an estimated False Discovery Rate of 15%. Among them, 16 corresponded to NPRC and all escaped standard selection procedures based on AUC and t statistics. Moreover, a simple inspection to the shape of such plots allowed to identify the two subclasses in either one class in 13 cases (81%. Conclusion NPRC represent a new useful tool for the analysis of microarray data.

  8. Compartment modeling of coal gasification in an entrained flow gasifier: A study on the influence of operating conditions

    International Nuclear Information System (INIS)

    Kong, Xiangdong; Zhong, Weimin; Du, Wenli; Qian, Feng

    2014-01-01

    Highlights: • Gasification of Shenfu coal in an industrial Texaco gasifier for syngas production. • An equivalent compartment model is developed using Aspen Plus. • Effects of operating parameters on gasification performance indices are studied. • Choosing a reasonable ROC to enhance the gasification efficiency can be flexible. - Abstract: Coal gasifiers are core components of coal-based polygeneration systems for power and chemical production. To study the effects of operational parameters on the performance of entrained flow coal gasifiers, this paper presents an equivalent compartment model (CM) using the Aspen Plus process simulator. The CM blocking is established based on gasifier flow field analysis, using a number of compartments. A simple configuration of these compartments involving material recirculation should be able to simulate the main flow and provide the temperature and gas component distributions. The model predictions exhibit good agreement with industrial data in the model validation. The influences of the oxygen-to-carbon ratio (ROC) and the coal slurry concentration on the gasification performance are discussed. Within the calculation range, the increase in the coal slurry concentration enhances the yield of the effective compositions in product gas. For a given slurry concentration of 62%, the efficient gas yield is a maximum for ROC of 1.43 kg/kg, whereas the oxygen consumption is a minimum for ROC of 1.37 kg/kg. According to the intended final use, however, choosing a reasonable ROC to obtain a higher efficient syngas yield and lower oxygen consumption can be flexible

  9. A 10-MWe solar-thermal central-receiver pilot plant: Solar facilities design integration. Plant operating/training manual (RADL-Item 2-36)

    Science.gov (United States)

    1982-07-01

    Plant and system level operating instructions are provided for the Barstow Solar Pilot Plant. Individual status instructions are given that identify plant conditions, process controller responsibilities, process conditions and control accuracies, operating envelopes, and operator cautions appropriate to the operating condition. Transition operating instructions identify the sequence of activities to be carried out to accomplish the indicated transition. Most transitions involve the startup or shutdown of an individual flowpath. Background information is provided on collector field operations, and the heliostat groupings and specific commands used in support receiver startup are defined.

  10. Role of Combined Post-Operative Venous Lactate and 48 Hours C-Reactive Protein Values on the Etiology and Predictive Capacity of Organ-Space Surgical Site Infection after Elective Colorectal Operation.

    Science.gov (United States)

    Juvany, Montserrat; Guirao, Xavier; Oliva, Joan Carles; Badía Pérez, Jose M

    2017-04-01

    C-reactive protein (CRP) has been assessed to detect organ-space surgical site infection (OSI). Nevertheless, data about peri-operative oxygen debt and surgical stress-elicited biologic markers to explain and allow for the early detection of OSI are lacking. We analyzed immediate post-operative venous lactate, early CRP levels, and intra-operative hemodynamic values on the capacity to predict OSI after elective colorectal operation. Patients undergoing an elective colorectal surgical procedure with anastomosis between March 2013 and August 2014 were included and assessed prospectively. Post-operative lactate values at L-0, L-6, and L-24 hours, CRP (basal and 48 h), and the percentage of operative time (POT) with systolic blood pressure below 100 mm Hg and heart rate above 90 beats per minute in patients with and without OSI were compared. Binary logistic regression was constructed for L-0 and CRP-48, and receiver-operating characteristic (ROC) was analyzed for sensitivity (S), specificity (Sp), positive (PPV) and negative (NPV) predictive values. Patients with OSI (11 of 100) showed higher L-0 and L-24 (3.2 ± 2.5 vs. 1.6 ± 0.8; p = 0.025 and 1.9 ± 1.2 vs. 1.2 ± 0.4 mmol/L; p = 0.025) and CRP-48 (188 ± 80 vs. 74 ± 52 mg/L; p = 0.001). The ROC from logistic regression showed area under the curve of 0.899 (95% confidence interval [CI] 0.805-0.992), S of 72% (95% CI 43.2%-90.5%), Sp of 95% (95% CI 88.6%-98.4%), PPV of 66% (95% CI 38.9%-86.4%) and NPV of 0.96 (95% CI 90%-99%). L-0 was higher in those patients with hypotension during more than 60% of the POT (2.4 ± 2.1 vs. 1.6 ± 0.8; p = 0.038). Patients with OSI had a higher POT with hypotension (50 ± 28% vs. 30 ± 28%; p = 0.032) and tachycardia (18 ± 27% vs. 5 ± 16%; p = 0,024). The combination of immediate post-operative lactate and CRP at 48 hours proved to be useful in predicting OSI after elective colorectal operation

  11. Final environmental statement related to the operation of the Barnwell Fuel Receiving and Storage Station (Docket No. 70-1729)

    International Nuclear Information System (INIS)

    1976-01-01

    The proposed action is to issue a materials license, pursuant to 10 CFR Parts 30, 40 and 70 of the Commission's regulations, authorizing Allied-General Nuclear Services to receive and handle fuel casks containing spent reactor fuel elements and to store spent reactor fuel at the Barnwell Nuclear Fuel Plant (BNFP), in the Barnwell Fuel Receiving and Storage Station (BFRSS). The BFRSS is a part of, and contiguous to, the BNFP-Separations Facility which is being constructed on a small portion of a 1700 acre site about six miles west of the city of Barnwell in Barnwell County, South Carolina. Construction of the BFRSS facility has been completed and the BNFP Separations Facility is more than 90% complete. A uranium Hexafluoride Facility is being constructed on the same site, and a Plutonium Product Facility is proposed to be constructed adjacent to the Separations Facility. The license that is the subject of this action will, if issued, allow lthe use of the BFRSS separate4 from the operation of the Separations Facility. Impacts resulting from the construction of the BFRSS have already occurred and mitigating measures have been and are being implemented to offset any adverse impacts. Operation of the BFRSS will not interfere with water sources, and should cause no noticeable damage to the terrestrial or aquatic environments. Operating experience at other fuel receiving and storage facilities has shown that radioactive concentrations discharged to the environs (the more significant process effluents) have been well below applicabhle state and federal limits. The small quantities to be released during operation of the BFRSS will result in negligible environmental impact. 20 figs

  12. Preferential access to emotion under attentional blink: evidence for threshold phenomenon

    Directory of Open Access Journals (Sweden)

    Szczepanowski Remigiusz

    2015-03-01

    Full Text Available The present study provides evidence that the activation strength produced by emotional stimuli must pass a threshold level in order to be consciously perceived, contrary to the assumption of continuous quality of representation. An analysis of receiver operating characteristics (ROC for attentional blink performance was used to distinguish between two (continuous vs. threshold models of emotion perception by inspecting two different ROC’s shapes. Across all conditions, the results showed that performance in the attentional blink task was better described by the two-limbs ROC predicted by the Krantz threshold model than by the curvilinear ROC implied by the signal-detection theory.

  13. Detection of moving objects: The first stage of an autonomous surveillance system

    CSIR Research Space (South Africa)

    Keaikitse, M

    2012-10-01

    Full Text Available using video footage of the real world. The Receiver Operating Characteristic (ROC) curves are used to quantify the performance of the algorithms. In our experiments, the adaptive Gaussian mixture model outperforms the Wallflower method....

  14. Methodology for quantitative evalution of diagnostic performance. Project III

    International Nuclear Information System (INIS)

    Metz, C.E.

    1985-01-01

    Receiver Operation Characteristic (ROC) methodology is now widely recognized as the most satisfactory approach to the problem of measuring and specifying the performance of a diagnostic procedure. The primary advantage of ROC analysis over alternative methodologies is that it seperates differences in diagnostic accuracy that are due to actual differences in discrimination capacity from those that are due to decision threshold effects. Our effort during the past year has been devoted to developing digital computer programs for fitting ROC curves to diagnostic data by maximum likelihood estimation and to developing meaningful and valid statistical tests for assessing the significance of apparent differences between measured ROC curves. FORTRAN programs previously written here for ROC curve fitting and statistical testing have been refined to make them easier to use and to allow them to be run in a large variety of computer systems. We have attempted also to develop two new curve-fitting programs: one for conventional ROC data that assumes a different functional form for the ROC curve, and one that can be used for ''free-response'' ROC data. Finally, we have cooperated with other investigators to apply our techniques to analyze ROC data generated in clinical studies, and we have sought to familiarize the medical community with the advantages of ROC methodology. 36 ref

  15. A Data-Driven Method for Selecting Optimal Models Based on Graphical Visualisation of Differences in Sequentially Fitted ROC Model Parameters

    Directory of Open Access Journals (Sweden)

    K S Mwitondi

    2013-05-01

    Full Text Available Differences in modelling techniques and model performance assessments typically impinge on the quality of knowledge extraction from data. We propose an algorithm for determining optimal patterns in data by separately training and testing three decision tree models in the Pima Indians Diabetes and the Bupa Liver Disorders datasets. Model performance is assessed using ROC curves and the Youden Index. Moving differences between sequential fitted parameters are then extracted, and their respective probability density estimations are used to track their variability using an iterative graphical data visualisation technique developed for this purpose. Our results show that the proposed strategy separates the groups more robustly than the plain ROC/Youden approach, eliminates obscurity, and minimizes over-fitting. Further, the algorithm can easily be understood by non-specialists and demonstrates multi-disciplinary compliance.

  16. Sensitivity and specificity of machine learning classifiers for glaucoma diagnosis using Spectral Domain OCT and standard automated perimetry

    Directory of Open Access Journals (Sweden)

    Fabrício R. Silva

    2013-06-01

    Full Text Available PURPOSE: To evaluate the sensitivity and specificity of machine learning classifiers (MLCs for glaucoma diagnosis using Spectral Domain OCT (SD-OCT and standard automated perimetry (SAP. METHODS: Observational cross-sectional study. Sixty two glaucoma patients and 48 healthy individuals were included. All patients underwent a complete ophthalmologic examination, achromatic standard automated perimetry (SAP and retinal nerve fiber layer (RNFL imaging with SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec Inc., Dublin, California. Receiver operating characteristic (ROC curves were obtained for all SD-OCT parameters and global indices of SAP. Subsequently, the following MLCs were tested using parameters from the SD-OCT and SAP: Bagging (BAG, Naive-Bayes (NB, Multilayer Perceptron (MLP, Radial Basis Function (RBF, Random Forest (RAN, Ensemble Selection (ENS, Classification Tree (CTREE, Ada Boost M1(ADA,Support Vector Machine Linear (SVML and Support Vector Machine Gaussian (SVMG. Areas under the receiver operating characteristic curves (aROC obtained for isolated SAP and OCT parameters were compared with MLCs using OCT+SAP data. RESULTS: Combining OCT and SAP data, MLCs' aROCs varied from 0.777(CTREE to 0.946 (RAN.The best OCT+SAP aROC obtained with RAN (0.946 was significantly larger the best single OCT parameter (p<0.05, but was not significantly different from the aROC obtained with the best single SAP parameter (p=0.19. CONCLUSION: Machine learning classifiers trained on OCT and SAP data can successfully discriminate between healthy and glaucomatous eyes. The combination of OCT and SAP measurements improved the diagnostic accuracy compared with OCT data alone.

  17. Dynamics of receptor-operated Ca2+ Currents Through TRPC Channels Controlled via the PI(4,5P2-PLC Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Masayuki X Mori

    2015-02-01

    Full Text Available Transient receptor potential canonical (TRPC channels are Ca2+-permeable, nonselective cation channels that carry receptor-operated Ca2+ currents (ROCs triggered by receptor-induced, phospholipase C (PLC-catalyzed hydrolysis of phosphatidylinositol 4,5-bisphosphate (PI(4,5P2. Within the vasculature, TRPC channel ROCs contribute to smooth muscle cell depolarization, vasoconstriction and vascular remodeling. However, TRPC channel ROCs exhibit a variable response to receptor-stimulation, and the regulatory mechanisms governing TRPC channel activity remain obscure. The variability of ROCs may be explained by their complex regulation by PI(4,5P2 and its metabolites, which differentially affect TRPC channel activity. To resolve the complex regulation of ROCs, the use of voltage-sensing phosphoinositide phosphatases and model simulation have helped to reveal the time-dependent contribution of PI(4,5P2 and the possible role of PI(4,5P2 in the regulation of ROCs. These approaches may provide unprecedented insight into the dynamics of PI(4,5P2 regulation of TRPC channels and the fundamental mechanisms underlying transmembrane ion flow. Within that context, we summarize the regulation of TRPC channels and their coupling to receptor-mediated signaling, as well as the application of voltage-sensing phosphoinositide phosphatases to this research. We also discuss the controversial bidirectional effects of PI(4,5P2 using a model simulation that could explain the complicated effects of PI(4,5P2 on different ROCs.

  18. Dynamics of receptor-operated Ca(2+) currents through TRPC channels controlled via the PI(4,5)P2-PLC signaling pathway.

    Science.gov (United States)

    Mori, Masayuki X; Itsuki, Kyohei; Hase, Hideharu; Sawamura, Seishiro; Kurokawa, Tatsuki; Mori, Yasuo; Inoue, Ryuji

    2015-01-01

    Transient receptor potential canonical (TRPC) channels are Ca(2+)-permeable, nonselective cation channels that carry receptor-operated Ca(2+) currents (ROCs) triggered by receptor-induced, phospholipase C (PLC)-catalyzed hydrolysis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Within the vasculature, TRPC channel ROCs contribute to smooth muscle cell depolarization, vasoconstriction, and vascular remodeling. However, TRPC channel ROCs exhibit a variable response to receptor-stimulation, and the regulatory mechanisms governing TRPC channel activity remain obscure. The variability of ROCs may be explained by their complex regulation by PI(4,5)P2 and its metabolites, which differentially affect TRPC channel activity. To resolve the complex regulation of ROCs, the use of voltage-sensing phosphoinositide phosphatases and model simulation have helped to reveal the time-dependent contribution of PI(4,5)P2 and the possible role of PI(4,5)P2 in the regulation of ROCs. These approaches may provide unprecedented insight into the dynamics of PI(4,5)P2 regulation of TRPC channels and the fundamental mechanisms underlying transmembrane ion flow. Within that context, we summarize the regulation of TRPC channels and their coupling to receptor-mediated signaling, as well as the application of voltage-sensing phosphoinositide phosphatases to this research. We also discuss the controversial bidirectional effects of PI(4,5)P2 using a model simulation that could explain the complicated effects of PI(4,5)P2 on different ROCs.

  19. Receiver operating characteristic analysis of chest radiographs with computed radiography and conventional analog films

    International Nuclear Information System (INIS)

    Morioka, C.; Brown, K.; Dalter, S.; Milos, M.J.; Huang, H.K.; Kangarloo, H.; Boechat, I.M.; Batra, P.

    1988-01-01

    Receiver operating characteristic is used to compare the image quality of films obtained digitally using computed radiography (CR) and conventionally using analog film following fluoroscopic examination. Twenty-four cases, some with a solitary noncalcified nodule and/or pneumothorax, were collected. Ten radiologists have been tested viewing analog and CR digital films separately. Preliminary results indicate that there is no significant difference in the ability to detect either a pneumothorax or a solitary noncalcified nodule when comparing CR digital film with conventional analog film. A comparison of the CR digital image displayed on a 2,048-line monitor against analog and CR digital film is in progress

  20. Psychometric properties of the Dutch version of the Eating Disorder Inventory-3

    NARCIS (Netherlands)

    Lehmann, V.; Ouwens, M.A.; Braeken, J.; Danner, U.N.; van Elburg, A.A.; Bekker, M.H.J.; Breurkens, A.; van Strien, T.

    2013-01-01

    The psychometric properties of the Dutch version of the Eating Disorder Inventory–3 (EDI-3) were tested in eating disordered patients (N = 514) using confirmatory factor analyses, variance decomposition, reliabilities, and receiver operating characteristic (ROC) curve analyses. Factorial validity

  1. Multiobjective optimization of classifiers by means of 3D convex-hull-based evolutionary algorithms

    NARCIS (Netherlands)

    Zhao, J.; Basto, Fernandes V.; Jiao, L.; Yevseyeva, I.; Asep, Maulana A.; Li, R.; Bäck, T.H.W.; Tang, T.; Michael, Emmerich T. M.

    2016-01-01

    The receiver operating characteristic (ROC) and detection error tradeoff(DET) curves are frequently used in the machine learning community to analyze the performance of binary classifiers. Recently, the convex-hull-based multiobjective genetic programming algorithm was proposed and successfully

  2. Usefulness of ECT in liver diseases

    International Nuclear Information System (INIS)

    Nishikawa, Jun-ichi

    1981-01-01

    The clinical usefulness of single photon emission tomography using rotating chair (ECT), comparing with liver scintigrams was examined with ROC (receiver operating characteristic) curve analysis. The ROC curve of ECT drew higher curved line than that of liver scintigram, i.e. true positive ratio of ECT was slightly inferior to that of liver scintigram, but false positive ratio of ECT was superior to that of liver scintigram. ECT adds useful clinical information to liver scintigram which shows questionable or suspected uptake defects. (author)

  3. Post-operative neuromuscular function of patients receiving non ...

    African Journals Online (AJOL)

    Objectives: To determine the number of patients whose non-depolarising muscle relaxation is adequately reversed. To define factors that contribute to reversal. Design: A cross sectional study. Setting: Universitas Hospital recovery room over a 2 month period. Subjects: Patients that received non-depolarising muscle ...

  4. 49 CFR 393.88 - Television receivers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Television receivers. 393.88 Section 393.88... NECESSARY FOR SAFE OPERATION Miscellaneous Parts and Accessories § 393.88 Television receivers. Any motor vehicle equipped with a television viewer, screen or other means of visually receiving a television...

  5. Stuck between a ROC and a hard place? Barriers to the take up of green energy in the UK

    International Nuclear Information System (INIS)

    Diaz-Rainey, Ivan; Ashton, John K.

    2008-01-01

    This paper examines the UK mechanisms for ensuring future investment in renewable energy through consumer adoption of green energy tariffs and the Renewable Obligation Certificate (ROC) system. Using a national survey and focus groups the stated willingness by UK customers to pay a premium for renewable or green energy and actual take up of such tariffs is assessed. Substantial differences between willingness to pay for and the adoption of green energy tariffs are reported. This disparity is linked to a range of factors including consumer confusion, lack of supply, complexities of constructing 'green source' tariffs under the ROC system and a lack of customer trust. It is concluded that the re-definition of the green energy market in favour of 'green source' tariffs, greater direct compliance with the Renewable Obligation by addressing supply constraints, and efforts in providing clearer information and choices for consumers via a compulsory green energy accreditation scheme are required if willing consumers' are to contribute to investment in renewable energy

  6. Atropine use may lead to post-operative respiratory acidosis in neonates receiving ductal ligation: A retrospective cohort study.

    Science.gov (United States)

    Chang, Szu-Ling; Lin, Wen-Li; Weng, Chien-Hsiang; Wu, Shye-Jao; Tsai, Hsin-Jung; Wang, Shwu-Meei; Peng, Chun-Chih; Chang, Jui-Hsing

    2018-04-01

    Patent ductus arteriosus (PDA) is one of the most common cardiac conditions in preterm infants. Closure of the PDA in symptomatic patients can be achieved medically or surgically. Atropine is commonly administered in general anesthesia as a premedication in this age group but with limited evidence addressing the effect of its use. Our study examined the association of the use of atropine as a premedication in PDA ligation and the risk of post-operative respiratory complications. This retrospective cohort study included 150 newborns who have failed medical treatment for PDA and received PDA ligation during 2008-2012 in a single tertiary medical center. Ninety-two of them (61.3%) received atropine as premedication for general anesthesia while 58 (38.7%) did not. Post-operative respiratory condition, the need of cardiopulmonary resuscitation and the presence of bradycardia were measured. Patients with atropine use were associated with increased odds of respiratory acidosis in both univariate analysis (22.9% vs 7.3%; OR = 3.785, 95% CI = 1.211-11.826, p = 0.022) and multivariate analysis (OR = 4.030, 95% CI = 1.230-13.202, p = 0.021), with an even higher odds of respiratory acidosis in patients receiving both atropine and ketamine. The use of atropine as premedication in general anesthesia for neonatal PDA ligation is associated with higher risk of respiratory acidosis, which worsens with the combined use of ketamine. Copyright © 2017. Published by Elsevier B.V.

  7. Analysing data from observer studies in medical imaging research: An introductory guide to free-response techniques

    International Nuclear Information System (INIS)

    Thompson, J.D.; Manning, D.J.; Hogg, P.

    2014-01-01

    Observer performance methods maintain their place in radiology research, particularly in the assessment of the diagnostic accuracy of new and existing techniques, despite not being fully embraced by the wider audience in medical imaging. The receiver operating characteristic (ROC) paradigm has been widely used in research and the latest location sensitive methods allow an analysis that is closer to the clinical scenario. This paper discusses the underpinning theories behind observer performance assessment, exploring the potential sources of error and the development of the ROC method. The paper progresses by explaining the clinical relevance and statistical suitability of the free-response ROC (FROC) paradigm, and the methodological considerations for those wishing to perform an observer performance study

  8. 29 CFR 1917.155 - Air receivers.

    Science.gov (United States)

    2010-07-01

    .... This section applies to compressed air receivers and equipment used for operations such as cleaning... transportation applications as railways, vehicles or cranes. (b) Gauges and valves. (1) Air receivers shall be... 29 Labor 7 2010-07-01 2010-07-01 false Air receivers. 1917.155 Section 1917.155 Labor Regulations...

  9. 77 FR 1707 - National Toxicology Program (NTP) Final Process for Preparation of the Report on Carcinogens (RoC)

    Science.gov (United States)

    2012-01-11

    ... the RoC. The process is available on the NTP Web site ( http://ntp.niehs.nih.gov/go/rocprocess ) or by... Counselors public meeting (76 FR 68461) on December 15, 2011 ( http://ntp.niehs.nih.gov/go/9741 ). The NTP... Web site ( http://ntp.niehs.nih.gov/go/rocprocess ) or by contacting Dr. Lunn (see ADDRESSES...

  10. Design and analysis of compressed sensing radar detectors

    NARCIS (Netherlands)

    Anitori, L.; Maleki, A.; Otten, M.P.G.; Baraniuk, R.G.; Hoogeboom, P.

    2013-01-01

    We consider the problem of target detection from a set of Compressed Sensing (CS) radar measurements corrupted by additive white Gaussian noise. We propose two novel architectures and compare their performance by means of Receiver Operating Characteristic (ROC) curves. Using asymptotic arguments and

  11. Pre-operative Spermatic Cord Ultrasonography Helps to Reduce the Incidence of Metachronous Inguinal Hernia in Boys

    Directory of Open Access Journals (Sweden)

    Shoujiang Huang

    2018-06-01

    Full Text Available Background/purpose: Thickening of the spermatic cord is a clinical sign of an inguinal hernia. We therefore tested whether pre-operative spermatic cord ultrasonography could reduce the incidence of metachronous inguinal hernia (MIH.Methods: Boys under 2 years old with an initial unilateral inguinal hernia were enrolled in this study. In whom the width of the asymptomatic-sided spermatic cord was ≥0.5 cm, these patients underwent contralateral groin exploration. Age at initial operation, weight, initial operation side, the sonographic width of the spermatic cord, the operative findings and presence of MIH were recorded, and the relationship among them was studied. Boys in the US group underwent an open herniorrhaphy with pre-operative ultrasound examination; the non-US group included boys who did not undergo a pre-operative ultrasound examination. A receiver operator curve (ROC analysis was performed to evaluated predictive value of the sonographic width of the spermatic cord for contralateral hernia.Results: A total of 24 months' follow-up data were obtained from 1,793 boys (US group 1,162, non-US group 631. In the US group, the width of the hernia-sided spermatic cord (0.75 ± 0.18 cm was larger than the normal side (0.37 ± 0.05 cm, P < 0.001. And the width of normal side spermatic cord had no significant difference between the groups regarding other factors such as age and weight. In whom the width of the asymptomatic-sided spermatic cord was ≥0.5 cm, the corresponding incidence of CIH was 86.4% (57/66. The width of the spermatic cord predicted the presence of contralateral hernia with ROC area under the curve = 0.943 (95% CI = 0.919–0.966. The total incidence of MIH was 4.1% (74/1793. The incidence of MIH in the US group was 2.2% (25/1162 much lower than 7.8% (49/631 in the non-US group (P < 0.001. If the width of the asymptomatic-sided spermatic cord was 0.5 cm and 0.54 cm, the corresponding sensitivity was 0.682 and 0

  12. Operator decision support system for integrated wastewater management including wastewater treatment plants and receiving water bodies.

    Science.gov (United States)

    Kim, Minsoo; Kim, Yejin; Kim, Hyosoo; Piao, Wenhua; Kim, Changwon

    2016-06-01

    An operator decision support system (ODSS) is proposed to support operators of wastewater treatment plants (WWTPs) in making appropriate decisions. This system accounts for water quality (WQ) variations in WWTP influent and effluent and in the receiving water body (RWB). The proposed system is comprised of two diagnosis modules, three prediction modules, and a scenario-based supporting module (SSM). In the diagnosis modules, the WQs of the influent and effluent WWTP and of the RWB are assessed via multivariate analysis. Three prediction modules based on the k-nearest neighbors (k-NN) method, activated sludge model no. 2d (ASM2d) model, and QUAL2E model are used to forecast WQs for 3 days in advance. To compare various operating alternatives, SSM is applied to test various predetermined operating conditions in terms of overall oxygen transfer coefficient (Kla), waste sludge flow rate (Qw), return sludge flow rate (Qr), and internal recycle flow rate (Qir). In the case of unacceptable total phosphorus (TP), SSM provides appropriate information for the chemical treatment. The constructed ODSS was tested using data collected from Geumho River, which was the RWB, and S WWTP in Daegu City, South Korea. The results demonstrate the capability of the proposed ODSS to provide WWTP operators with more objective qualitative and quantitative assessments of WWTP and RWB WQs. Moreover, the current study shows that ODSS, using data collected from the study area, can be used to identify operational alternatives through SSM at an integrated urban wastewater management level.

  13. Optimal cutoff values of WHO-HPQ presenteeism scores by ROC analysis for preventing mental sickness absence in Japanese prospective cohort.

    Directory of Open Access Journals (Sweden)

    Tomoko Suzuki

    Full Text Available Sickness absence due to mental disease in the workplace has become a global public health problem. Previous studies report that sickness presenteeism is associated with sickness absence. We aimed to determine optimal cutoff scores for presenteeism in the screening of the future absences due to mental disease.A prospective study of 2195 Japanese employees from all areas of Japan was conducted. Presenteeism and depression were measured by the validated Japanese version of the World Health Organization Health and Work Performance Questionnaire (WHO-HPQ and K6 scale, respectively. Absence due to mental disease across a 2-year follow-up was surveyed using medical certificates obtained for work absence. Socioeconomic status was measured via a self-administered questionnaire. Receiver operating curve (ROC analysis was used to determine optimal cutoff scores for absolute and relative presenteeism in relation to the area under the curve (AUC, sensitivity, and specificity.The AUC values for absolute and relative presenteeism were 0.708 (95% CI, 0.618-0.797 and 0.646 (95% CI, 0.546-0.746, respectively. Optimal cutoff scores of absolute and relative presenteeism were 40 and 0.8, respectively. With multivariate adjustment, cohort participants with our proposal cutoff scores for absolute and relative presenteeism were significantly more likely to be absent due to mental disease (OR = 4.85, 95% CI: 2.20-10.73 and OR = 5.37, 95% CI: 2.42-11.93, respectively. The inclusion or exclusion of depressive symptoms (K6≥13 at baseline in the multivariate adjustment did not influence the results.Our proposed optimal cutoff scores of absolute and relative presenteeism are 40 and 0.8, respectively. Participants who scored worse than the cutoff scores for presenteeism were significantly more likely to be absent in future because of mental disease. Our findings suggest that the utility of presenteeism in the screening of sickness absence due to mental disease would

  14. Approaches to the detection of ovarian cancer

    DEFF Research Database (Denmark)

    Høgdall, Estrid

    2016-01-01

    (ROCA), or Copenhagen Index (CPH-I).  Aim: To describe biomarkers that potentially improve the detection/risk estimation of OC.  Results: The ability to differentiate OC from benign and borderline ovarian tumors was analyzed using Receiver Operating Characteristics (ROC) curves resulting in Area Under...

  15. Universal School Readiness Screening at Kindergarten Entry

    Science.gov (United States)

    Quirk, Matthew; Dowdy, Erin; Dever, Bridget; Carnazzo, Katherine; Bolton, Courtney

    2018-01-01

    Researchers examined the concurrent and predictive validity of a brief (12-item) teacher-rated school readiness screener, the Kindergarten Student Entrance Profile (KSEP), using receiver operating characteristic (ROC) curve analysis to examine associations between (N = 78) children's social-emotional (SE) and cognitive (COG) readiness with…

  16. Diagnostic Utility of the Social Skills Improvement System Performance Screening Guide

    Science.gov (United States)

    Krach, S. Kathleen; McCreery, Michael P.; Wang, Ye; Mohammadiamin, Houra; Cirks, Christen K.

    2017-01-01

    Researchers investigated the diagnostic utility of the Social Skills Improvement System: Performance Screening Guide (SSIS-PSG). Correlational, regression, receiver operating characteristic (ROC), and conditional probability analyses were run to compare ratings on the SSIS-PSG subscales of Prosocial Behavior, Reading Skills, and Math Skills, to…

  17. Post-Operative Infection Is an Independent Risk Factor for Worse Long-Term Survival after Colorectal Cancer Surgery.

    Science.gov (United States)

    Kerin Povšič, Milena; Ihan, Alojz; Beovič, Bojana

    2016-12-01

    Colorectal cancer surgery is associated with a high incidence of post-operative infections, the outcome of which may be improved if diagnosed and treated early enough. We compared white blood cell (WBC) count, C-reactive protein (CRP), and procalcitonin (PCT) as predictors of post-operative infections and analyzed their impact on long-term survival. This retrospective study included 186 patients undergoing colorectal surgery. Post-operative values of WBC, CRP, and PCT were analyzed by the receiver operating characteristic (ROC) analysis. We followed infections 30 d after the surgery. A five-year survival was analyzed by Kaplan-Meier method and prognostic factors by Cox regression model. Fifty-five patients (29.5%) developed post-operative infection, the most frequent of which was surgical site infection (SSI). C-reactive protein on post-operative day three and PCT on post-operative day two demonstrated the highest diagnostic accuracy for infection (area under the curve [AUC] 0.739 and 0.735). C-reactive protein on post-operative day three was an independent predictor of infection. Five-year survival was higher in the non-infected group (70.8%), compared with the infected group (52.1%). The worst survival (40.9%) was identified in patients with organ/space SSI. Post-operative infection and tumor stage III-IV were independent predictors of a worse five-year survival. C-reactive protein on post-operative day three and PCT on post-operative day two may be early predictors of infection after colorectal cancer surgery. Post-operative infections in particular organ/space SSI have a negative impact on long-term survival.

  18. Screening for Depressive Disorders Using the Mood and Anxiety Symptoms Questionnaire Anhedonic Depression Scale: A Receiver-Operating Characteristic Analysis

    Science.gov (United States)

    Bredemeier, Keith; Spielberg, Jeffery M.; Silton, Rebecca Levin; Berenbaum, Howard; Heller, Wendy; Miller, Gregory A.

    2010-01-01

    The present study examined the utility of the anhedonic depression scale from the Mood and Anxiety Symptoms Questionnaire (MASQ-AD scale) as a way to screen for depressive disorders. Using receiver-operating characteristic analysis, we examined the sensitivity and specificity of the full 22-item MASQ-AD scale, as well as the 8- and 14-item…

  19. Local dynamic stability during treadmill walking can detect children with developmental coordination disorder

    DEFF Research Database (Denmark)

    Speedtsberg, Merete Brink; Christensen, Sofie Bouschinger; Stenum, Jan

    2018-01-01

    -posterior directions were recorded with a sternum mounted accelerometer at 256Hz. Short term local dynamic stability (λs), root mean square (RMS) and relative root mean square (RMSR) were calculated from measures of orthogonal trunk accelerations. Receiver operating characteristic curve (ROC) analysis was performed...... between children with DCD and TD children in any direction. The ROC analysis of λs in separate directions and in two dimensions showed an excellent accuracy of discriminating between children with DCD and TD children. Anterior-posterior direction in combination with medio-lateral or vertical showed best...

  20. Diagnostic utility of the glucagon stimulation test in comparison to the insulin tolerance test in patients following pituitary surgery

    DEFF Research Database (Denmark)

    Berg, Christian; Meinel, Timo; Lahner, Harald

    2009-01-01

    OBJECTIVE: The glucagon stimulation test (GST) like the insulin tolerance test (ITT) stimulates both ACTH and GH secretion. However, there are limited data with modern assays on sensitivity and specificity for GST in comparison to ITT. The aim of this study was to evaluate the diagnostic utility......). Receiver-operating characteristic (ROC) analysis was performed to identify the thresholds for GST. RESULTS: In ITT, 18/49 cases were classified as AI. ROC analysis revealed a peak cortisol value >599 nmol/l in GST for adrenal sufficiency with 100% specificity and 32% sensitivity, and a peak cortisol

  1. Methodology for evaluation of diagnostic performance

    International Nuclear Information System (INIS)

    Metz, C.E.

    1992-01-01

    Effort in this project during the past year has focused on the development, refinement, and distribution of computer software that will allow current Receiver Operating Characteristic (ROC) methodology to be used conveniently and reliably by investigators in a variety of evaluation tasks in diagnostic medicine; and on the development of new ROC methodology that will broaden the spectrum of evaluation tasks and/or experimental settings to which the fundamental approach can be applied. Progress has been limited by the amount of financial support made available to the project

  2. Mammography in Norway: Image quality and total performance

    International Nuclear Information System (INIS)

    Olsen, J.B.; Skretting, A.; Widmark, A.

    1997-04-01

    This report describes a method for assessing the total performance in mammography based on Receiver Operating Characteristic (ROC) analysis. In the time period from December 1993 to March 1994 the method was applied to assess the total performance of all the 45 Norwegian mammography laboratories operative at that time. Image quality characteristics in each laboratory was established by use of well-known phantoms

  3. Mammography in Norway: Image quality and total performance; Mammografivirksomhet i Norge: Bildekvalitet og totalytelse

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, J.B.; Skretting, A. [Norske Radiumhospital, Oslo (Norway); Widmark, A. [Statens Straalevern, Oesteraas (Norway)

    1997-04-01

    This report describes a method for assessing the total performance in mammography based on Receiver Operating Characteristic (ROC) analysis. In the time period from December 1993 to March 1994 the method was applied to assess the total performance of all the 45 Norwegian mammography laboratories operative at that time. Image quality characteristics in each laboratory was established by use of well-known phantoms.

  4. Textural features in pre-treatment [F18]-FDG-PET/CT are correlated with risk of local recurrence and disease-specific survival in early stage NSCLC patients receiving primary stereotactic radiation therapy.

    Science.gov (United States)

    Pyka, Thomas; Bundschuh, Ralph A; Andratschke, Nicolaus; Mayer, Benedikt; Specht, Hanno M; Papp, Laszló; Zsótér, Norbert; Essler, Markus

    2015-04-22

    Textural features in FDG-PET have been shown to provide prognostic information in a variety of tumor entities. Here we evaluate their predictive value for recurrence and prognosis in NSCLC patients receiving primary stereotactic radiation therapy (SBRT). 45 patients with early stage NSCLC (T1 or T2 tumor, no lymph node or distant metastases) were included in this retrospective study and followed over a median of 21.4 months (range 3.1-71.1). All patients were considered non-operable due to concomitant disease and referred to SBRT as the primary treatment modality. Pre-treatment FDG-PET/CT scans were obtained from all patients. SUV and volume-based analysis as well as extraction of textural features based on neighborhood gray-tone difference matrices (NGTDM) and gray-level co-occurence matrices (GLCM) were performed using InterView Fusion™ (Mediso Inc., Budapest). The ability to predict local recurrence (LR), lymph node (LN) and distant metastases (DM) was measured using the receiver operating characteristic (ROC). Univariate and multivariate analysis of overall and disease-specific survival were executed. 7 out of 45 patients (16%) experienced LR, 11 (24%) LN and 11 (24%) DM. ROC revealed a significant correlation of several textural parameters with LR with an AUC value for entropy of 0.872. While there was also a significant correlation of LR with tumor size in the overall cohort, only texture was predictive when examining T1 (tumor diameter 3 cm) subgroups. No correlation of the examined PET parameters with LN or DM was shown. In univariate survival analysis, both heterogeneity and tumor size were predictive for disease-specific survival, but only texture determined by entropy was determined as an independent factor in multivariate analysis (hazard ratio 7.48, p = .016). Overall survival was not significantly correlated to any examined parameter, most likely due to the high comorbidity in our cohort. Our study adds to the growing evidence that tumor

  5. Textural features in pre-treatment [F18]-FDG-PET/CT are correlated with risk of local recurrence and disease-specific survival in early stage NSCLC patients receiving primary stereotactic radiation therapy

    International Nuclear Information System (INIS)

    Pyka, Thomas; Bundschuh, Ralph A; Andratschke, Nicolaus; Mayer, Benedikt; Specht, Hanno M; Papp, Laszló; Zsótér, Norbert; Essler, Markus

    2015-01-01

    Textural features in FDG-PET have been shown to provide prognostic information in a variety of tumor entities. Here we evaluate their predictive value for recurrence and prognosis in NSCLC patients receiving primary stereotactic radiation therapy (SBRT). 45 patients with early stage NSCLC (T1 or T2 tumor, no lymph node or distant metastases) were included in this retrospective study and followed over a median of 21.4 months (range 3.1–71.1). All patients were considered non-operable due to concomitant disease and referred to SBRT as the primary treatment modality. Pre-treatment FDG-PET/CT scans were obtained from all patients. SUV and volume-based analysis as well as extraction of textural features based on neighborhood gray-tone difference matrices (NGTDM) and gray-level co-occurence matrices (GLCM) were performed using InterView Fusion™ (Mediso Inc., Budapest). The ability to predict local recurrence (LR), lymph node (LN) and distant metastases (DM) was measured using the receiver operating characteristic (ROC). Univariate and multivariate analysis of overall and disease-specific survival were executed. 7 out of 45 patients (16%) experienced LR, 11 (24%) LN and 11 (24%) DM. ROC revealed a significant correlation of several textural parameters with LR with an AUC value for entropy of 0.872. While there was also a significant correlation of LR with tumor size in the overall cohort, only texture was predictive when examining T1 (tumor diameter < = 3 cm) and T2 (>3 cm) subgroups. No correlation of the examined PET parameters with LN or DM was shown. In univariate survival analysis, both heterogeneity and tumor size were predictive for disease-specific survival, but only texture determined by entropy was determined as an independent factor in multivariate analysis (hazard ratio 7.48, p = .016). Overall survival was not significantly correlated to any examined parameter, most likely due to the high comorbidity in our cohort. Our study adds to the growing evidence

  6. Optimal threshold estimation for binary classifiers using game theory.

    Science.gov (United States)

    Sanchez, Ignacio Enrique

    2016-01-01

    Many bioinformatics algorithms can be understood as binary classifiers. They are usually compared using the area under the receiver operating characteristic ( ROC ) curve. On the other hand, choosing the best threshold for practical use is a complex task, due to uncertain and context-dependent skews in the abundance of positives in nature and in the yields/costs for correct/incorrect classification. We argue that considering a classifier as a player in a zero-sum game allows us to use the minimax principle from game theory to determine the optimal operating point. The proposed classifier threshold corresponds to the intersection between the ROC curve and the descending diagonal in ROC space and yields a minimax accuracy of 1-FPR. Our proposal can be readily implemented in practice, and reveals that the empirical condition for threshold estimation of "specificity equals sensitivity" maximizes robustness against uncertainties in the abundance of positives in nature and classification costs.

  7. A Study for Parametric Morphogeometric Operators to Assist the Detection of Keratoconus

    Directory of Open Access Journals (Sweden)

    Laurent Bataille

    2017-12-01

    Full Text Available The aim of this study is to describe a new keratoconus detection method based on the analysis of certain parametric morphogeometric operators extracted from a custom patient-specific three-dimensional (3D model of the human cornea. A corneal geometric reconstruction is firstly performed using zonal functions and retrospective Scheimpflug tomography data from 107 eyes of 107 patients. The posterior corneal surface is later analysed using an optimised computational geometry technique and the morphology of healthy and keratoconic corneas is characterized by means of geometric variables. The performance of these variables as predictors of a new geometric marker is assessed through a receiver operating characteristic (ROC curve analysis and their correlations are analysed through Pearson or Spearman coefficients. The posterior apex deviation variable shows the best keratoconus diagnosis capability. However, the strongest correlations in both healthy and pathological corneas are provided by the metrics directly related to the thickness as the sagittal plane area at the apex and the sagittal plane area at the minimum thickness point. A comparison of the screening of keratoconus provided by the Sirius topographer and the detection of corneal ectasia using the posterior apex deviation parameter is also performed, demonstrating the accuracy of this characterization as an effective marker of the diagnosis and ectatic disease progression.

  8. Investigating Strength and Frequency Effects in Recognition Memory Using Type-2 Signal Detection Theory

    Science.gov (United States)

    Higham, Philip A.; Perfect, Timothy J.; Bruno, Davide

    2009-01-01

    Criterion- versus distribution-shift accounts of frequency and strength effects in recognition memory were investigated with Type-2 signal detection receiver operating characteristic (ROC) analysis, which provides a measure of metacognitive monitoring. Experiment 1 demonstrated a frequency-based mirror effect, with a higher hit rate and lower…

  9. AUK: a simple alternative to the AUC

    NARCIS (Netherlands)

    Kaymak, U.; Ben-David, A.; Potharst, R.

    2010-01-01

    The area under Receiver Operating Characteristic (ROC) curve, also known as the AUC-index, is commonly used for ranking the performance of data mining models. The AUC has many merits, such as objectivity and ease of interpretation. However, since it is class indifferent, its usefulness while dealing

  10. The AUK : a simple alternative to the AUC

    NARCIS (Netherlands)

    Kaymak, U.; Ben-David, A.; Potharst, R.

    2012-01-01

    The area under the receiver operating characteristic (ROC) curve, also known as the AUC-index, is commonly used for ranking the performance of data mining models. The AUC has various merits, such as ease of interpretation. However, since it is class indifferent, its usefulness while dealing with

  11. AUK: a simple alternative to the AUC

    NARCIS (Netherlands)

    U. Kaymak (Uzay); A. Ben-David (Arie); R. Potharst (Rob)

    2010-01-01

    textabstractThe area under Receiver Operating Characteristic (ROC) curve, also known as the AUC-index, is commonly used for ranking the performance of data mining models. The AUC has many merits, such as objectivity and ease of interpretation. However, since it is class indifferent, its usefulness

  12. International ring trial to detect anti-Trichinella IgG by ELISA on pig sera.

    Science.gov (United States)

    In the present study, the sensitivity and specificity of the ELISA assay determined by the CRLP validation was 100% and 98.29%, respectively. The assay was reproducible, moreover, based on the receiver-operator characteristic (ROC) curve, the sensitivity and specificity of the assay reached 97.5% an...

  13. Comparison of proteomic biomarker panels in urine and serum for ovarian cancer diagnosis

    DEFF Research Database (Denmark)

    Petri, Anette Lykke; Simonsen, Anja Hviid; Høgdall, Estrid

    2010-01-01

    The purposes of this study were to confirm previously found candidate epithelial ovarian cancer biomarkers in urine and to compare a paired serum biomarker panel and a urine biomarker panel from the same study cohort with regard to the receiver operating characteristic curve (ROC) area under the ...

  14. An efficient visual saliency detection model based on Ripplet transform

    Indian Academy of Sciences (India)

    A Diana Andrushia

    human visual attention models is still not well investigated. ... Ripplet transform; visual saliency model; Receiver Operating Characteristics (ROC); .... proposed method has the same resolution as that of an input ... regions are obtained, which are independent of their sizes. ..... impact than those far away from the attention.

  15. Fair lineups are better than biased lineups and showups, but not because they increase underlying discriminability.

    Science.gov (United States)

    Smith, Andrew M; Wells, Gary L; Lindsay, R C L; Penrod, Steven D

    2017-04-01

    Receiver Operating Characteristic (ROC) analysis has recently come in vogue for assessing the underlying discriminability and the applied utility of lineup procedures. Two primary assumptions underlie recommendations that ROC analysis be used to assess the applied utility of lineup procedures: (a) ROC analysis of lineups measures underlying discriminability, and (b) the procedure that produces superior underlying discriminability produces superior applied utility. These same assumptions underlie a recently derived diagnostic-feature detection theory, a theory of discriminability, intended to explain recent patterns observed in ROC comparisons of lineups. We demonstrate, however, that these assumptions are incorrect when ROC analysis is applied to lineups. We also demonstrate that a structural phenomenon of lineups, differential filler siphoning, and not the psychological phenomenon of diagnostic-feature detection, explains why lineups are superior to showups and why fair lineups are superior to biased lineups. In the process of our proofs, we show that computational simulations have assumed, unrealistically, that all witnesses share exactly the same decision criteria. When criterial variance is included in computational models, differential filler siphoning emerges. The result proves dissociation between ROC curves and underlying discriminability: Higher ROC curves for lineups than for showups and for fair than for biased lineups despite no increase in underlying discriminability. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  16. Transthyretin levels: Potential biomarker for monitoring nutritional support efficacy and clinical complications risk in patients receiving parenteral nutrition.

    Science.gov (United States)

    Borges de Oliveira Nascimento Freitas, Renata Germano; Hessel, Gabriel; Junqueira Vasques, Ana Carolina; Negrão Nogueira, Roberto José

    2018-04-01

    Nutritional support is an effective strategy to restore or maintain nutritional status, to reduce clinical complications, hospitalization period and the morbidity/mortality risk of hospitalized patients. So, a good marker is important to evaluate the nutritional support. This study aims to evaluate the evolution of transthyretin levels in patients receiving parenteral nutrition (PN) during 14 days. Longitudinal study of 88 hospitalized patients. The assessments and samples were taken during the first 72 h (T0), on the 7th day (T7) and 14th day (T14) of PN. This study was approved by the Ethics Committee of the School of Medical Sciences at UNICAMP (No 538/2011). The C-reactive protein (CRP) levels were high and albumin and transthyretin levels were low at baseline. From T0 to T14, only transthyretin increased (p = 0.03). According to the receiver operation characteristic (ROC) curve, we found that the transthyretin had some improvement when the CRP levels were less than 10.4 mg/dl (T7). According to the CRP/albumin ratio, all patients classified as without risk for complications were discharged from the hospital. In addition, we observed that patients with transthyretin reduction had a concomitant higher risk for complications according to their ratio CRP/albumin (p = 0.03). CRP/albumin ratio was associated with the evolution of transthyretin levels. Transthyretin values showed significant improvement in the 14 days of PN. Especially, less inflamed patients (ie CRP less than 10.4 mg/dl) improved their transthyretin levels. So, CRP value at day 7 that predicts the transthyretin and transthyretin is a good biomarker for classification of nutritional support and clinical complications risk in patients receiving PN. Copyright © 2017 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

  17. Salivary oxytocin concentrations in response to running, sexual self-stimulation, breastfeeding and the TSST: The Regensburg Oxytocin Challenge (ROC) study.

    Science.gov (United States)

    Jong, Trynke R de; Menon, Rohit; Bludau, Anna; Grund, Thomas; Biermeier, Verena; Klampfl, Stefanie M; Jurek, Benjamin; Bosch, Oliver J; Hellhammer, Juliane; Neumann, Inga D

    2015-12-01

    Intranasal oxytocin (OXT) application is emerging as a potential treatment for socio-emotional disorders associated with abnormalities in OXT system (re-) activity. The crucial identification of patients with such abnormalities could be streamlined by the assessment of basal and stimulus-induced OXT concentrations in saliva, using a simple, stress-free sampling procedure (i.e. an OXT challenge test). We therefore established the Regensburg Oxytocin Challenge (ROC) test to further validate salivary OXT concentrations as a practical, reliable and sensitive biomarker. OXT concentrations were quantified by radioimmunoassay in samples collected at home by healthy adult male and female volunteers before and after running ("Run") or sexual self-stimulation ("Sex"). In lactating women, salivary OXT concentrations were quantified before, during and after breastfeeding. Salivary OXT along with salivary cortisol and heart rate were monitored in healthy adult participants undergoing the Trier Social Stress Test (TSST). The home-based "Run" and "Sex" challenges as well as the laboratory-based TSST caused quantifiable, rapid, and consistent increases in salivary OXT (approximately 2.5-fold after 10-15min), which were similar for men and women. Breastfeeding did not result in measurably increased salivary OXT levels, probably because the short pulses of OXT release characteristic for lactation were missed. Taken together, ROC tests reliably assess the responsiveness of the OXT system (i.e., the increase in salivary OXT concentrations as compared to basal levels) to challenges such as "Run" and "Sex" at home or psychosocial stress (TSST) in the laboratory. Further studies with larger sample numbers are essentially needed in order to reveal individual differences in ROC test outcomes depending on, for example, genetic or environmental factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Hearing Instrument using receivers with different performance characteristics

    DEFF Research Database (Denmark)

    2009-01-01

    The invention regards a signal processing device in a hearing aid, wherein the signal processing device is electrically coupled to a connection socket operable to detachably connect a receiver to the socket and whereby the signal processing device further comprise a detector operable to detect...... a characteristics of the receiver which is connected to the signal processing device through the connection socket....

  19. Sources of expertise in transportation planning, management, and operations: Information received as of September 25, 1987

    International Nuclear Information System (INIS)

    1987-01-01

    The DOE Office of Storage and Transportation Systems is responsible for the development and management of a transportation system to provide all the necessary services for the transportation of the spent fuel and wastes from reactor sites to repositories. DOE/ORO has requested Oak Ridge Associated Universities (ORAU) to assist DOE in developing rosters of sources of transportation expertise in: (1) carrier operations; (2) transportation management, planning, and logistics; (3) transportation equipment; (4) transportation facilities design and operation; (5) vehicle safety; and (6) transportation operations quality assurance; as related to truck, rail, barge, and intermodal transportation. Persons or organizations with experience in shipping of non-hazardous materials, spent nuclear fuel, other radioactive materials, and/or other hazardous materials were included in the information system. A mailed inquiry was sent to over 2300 potential sources of transportation expertise. Responses were received from 207 persons and 254 organizations. Section 1 contains the identification numbers of the individuals and organizations that responded. Section 2 contains identification codes, names, addresses, and phone numbers of each of the individual and organization respondents. The reader can refer to Section 2 for the name and address of the respondents for the identification codes listed for each technical area/experience base in Section 1

  20. Increased signal intensity within glioblastoma resection cavities on fluid-attenuated inversion recovery imaging to detect early progressive disease in patients receiving radiotherapy with concomitant temozolomide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Luke A. [Monash University, Melbourne (Australia); Korfiatis, Panagiotis; Erickson, Bradley J. [Mayo Clinic Rochester, Department of Radiology, Rochester, MN (United States); Agrawal, Jay P. [University of Massachusetts Medical School, Department of Radiology, Worcester, MA (United States)

    2018-01-15

    Our study tested the diagnostic accuracy of increased signal intensity (SI) within FLAIR MR images of resection cavities in differentiating early progressive disease (ePD) from pseudoprogression (PsP) in patients with glioblastoma treated with radiotherapy with concomitant temozolomide therapy. In this retrospective study approved by our Institutional Review Board, we evaluated the records of 122 consecutive patients with partially or totally resected glioblastoma. Region of interest (ROI) analysis assessed 33 MR examinations from 11 subjects with histologically confirmed ePD and 37 MR examinations from 14 subjects with PsP (5 histologically confirmed, 9 clinically diagnosed). After applying an N4 bias correction algorithm to remove B0 field distortion and to standardize image intensities and then normalizing the intensities based on an ROI of uninvolved white matter from the contralateral hemisphere, the mean intensities of the ROI from within the resection cavities were calculated. Measures of diagnostic performance were calculated from the receiver operating characteristic (ROC) curve using the threshold intensity that maximized differentiation. Subgroup analysis explored differences between the patients with biopsy-confirmed disease. At an optimal threshold intensity of 2.9, the area under the ROC curve (AUROC) for FLAIR to differentiate ePD from PsP was 0.79 (95% confidence interval 0.686-0.873) with a sensitivity of 0.818 and specificity of 0.694. The AUROC increased to 0.86 when only the patients with biopsy-confirmed PsP were considered. Increased SI within the resection cavity of FLAIR images is not a highly specific sign of ePD in glioblastoma patients treated with the Stupp protocol. (orig.)

  1. The status of hazardous waste management in Taiwan, R.O.C

    International Nuclear Information System (INIS)

    Chen, L.L.G.

    1989-01-01

    A large quantity of industrial waste (such as waste oils FCB's, cadmium, etc.) is produced daily in Taiwan, R.O.C.. A 1985 survey found that the amount of waste generated equalled approximately 30 million tons per year. Hazardous waste represents 9.7% of this total. Based on statistics from this same 1985 survey, 72% of the factories disposed of their waste without intermediate treatment. This paper reports that since most methods used for treatment of hazardous wastes were implemented incorrectly, the proper treatment of such waste has become the focal point of environmental protection in Taiwan. From July, 1987 the short-term program for industrial waste control has had as its first priority the control of toxic, infectious and corrosive hazardous waste. At the same time, a registration system for permission, reporting and results inspection for hazardous wastes is being developed. An industrial waste exchange and reclamation system is also being developed. It is predicted that a complete hazardous waste management program can be developed within the next four years

  2. Binary and multi-category ratings in a laboratory observer performance study: a comparison.

    Science.gov (United States)

    Gur, David; Bandos, Andriy I; King, Jill L; Klym, Amy H; Cohen, Cathy S; Hakim, Christiane M; Hardesty, Lara A; Ganott, Marie A; Perrin, Ronald L; Poller, William R; Shah, Ratan; Sumkin, Jules H; Wallace, Luisa P; Rockette, Howard E

    2008-10-01

    The authors investigated radiologists, performances during retrospective interpretation of screening mammograms when using a binary decision whether to recall a woman for additional procedures or not and compared it with their receiver operating characteristic (ROC) type performance curves using a semi-continuous rating scale. Under an Institutional Review Board approved protocol nine experienced radiologists independently rated an enriched set of 155 examinations that they had not personally read in the clinic, mixed with other enriched sets of examinations that they had individually read in the clinic, using both a screening BI-RADS rating scale (recall/not recall) and a semi-continuous ROC type rating scale (0 to 100). The vertical distance, namely the difference in sensitivity levels at the same specificity levels, between the empirical ROC curve and the binary operating point were computed for each reader. The vertical distance averaged over all readers was used to assess the proximity of the performance levels under the binary and ROC-type rating scale. There does not appear to be any systematic tendency of the readers towards a better performance when using either of the two rating approaches, namely four readers performed better using the semi-continuous rating scale, four readers performed better with the binary scale, and one reader had the point exactly on the empirical ROC curve. Only one of the nine readers had a binary "operating point" that was statistically distant from the same reader's empirical ROC curve. Reader-specific differences ranged from -0.046 to 0.128 with an average width of the corresponding 95% confidence intervals of 0.2 and p-values ranging for individual readers from 0.050 to 0.966. On average, radiologists performed similarly when using the two rating scales in that the average distance between the run in individual reader's binary operating point and their ROC curve was close to zero. The 95% confidence interval for the fixed

  3. Sodium reflux pool-boiler solar receiver on-sun test results

    Energy Technology Data Exchange (ETDEWEB)

    Andraka, C E; Moreno, J B; Diver, R B; Moss, T A [Oak Ridge National Lab., TN (United States)

    1992-06-01

    The efficient operation of a Stirling engine requires the application of a high heat flux to the relatively small area occupied by the heater head tubes. Previous attempts to couple solar energy to Stirling engines generally involved directly illuminating the heater head tubes with concentrated sunlight. In this study, operation of a 75-kW{sub t} sodium reflux pool-boiler solar receiver has been demonstrated and its performance characterized on Sandia's nominal 75-kW{sub t} parabolic-dish concentrator, using a cold-water gas-gap calorimeter to simulate Stirling engine operation. The pool boiler (and more generally liquid-metal reflux receivers) supplies heat to the engine in the form of latent heat released from condensation of the metal vapor on the heater head tubes. The advantages of the pool boiler include uniform tube temperature, leading to longer life and higher temperature available to the engine, and decoupling of the design of the solar absorber from the engine heater head. The two-phase system allows high input thermal flux, reducing the receiver size and losses, therefore improving system efficiency. The receiver thermal efficiency was about 90% when operated at full power and 800{degree}C. Stable sodium boiling was promoted by the addition of 35 equally spaced artificial cavities in the wetted absorber surface. High incipient boiling superheats following cloud transients were suppressed passively by the addition of small amounts of xenon gas to the receiver volume. Stable boiling without excessive incipient boiling superheats was observed under all operating conditions. The receiver developed a leak during performance evaluation, terminating the testing after accumulating about 50 hours on sun. The receiver design is reported here along with test results including transient operations, steady-state performance evaluation, operation at various temperatures, infrared thermography, x-ray studies of the boiling behavior, and a postmortem analysis.

  4. Recent developments in imaging system assessment methodology, FROC analysis and the search model.

    Science.gov (United States)

    Chakraborty, Dev P

    2011-08-21

    A frequent problem in imaging is assessing whether a new imaging system is an improvement over an existing standard. Observer performance methods, in particular the receiver operating characteristic (ROC) paradigm, are widely used in this context. In ROC analysis lesion location information is not used and consequently scoring ambiguities can arise in tasks, such as nodule detection, involving finding localized lesions. This paper reviews progress in the free-response ROC (FROC) paradigm in which the observer marks and rates suspicious regions and the location information is used to determine whether lesions were correctly localized. Reviewed are FROC data analysis, a search-model for simulating FROC data, predictions of the model and a method for estimating the parameters. The search model parameters are physically meaningful quantities that can guide system optimization.

  5. Recent developments in imaging system assessment methodology, FROC analysis and the search model

    International Nuclear Information System (INIS)

    Chakraborty, Dev P.

    2011-01-01

    A frequent problem in imaging is assessing whether a new imaging system is an improvement over an existing standard. Observer performance methods, in particular the receiver operating characteristic (ROC) paradigm, are widely used in this context. In ROC analysis lesion location information is not used and consequently scoring ambiguities can arise in tasks, such as nodule detection, involving finding localized lesions. This paper reviews progress in the free-response ROC (FROC) paradigm in which the observer marks and rates suspicious regions and the location information is used to determine whether lesions were correctly localized. Reviewed are FROC data analysis, a search model for simulating FROC data, predictions of the model and a method for estimating the parameters. The search model parameters are physically meaningful quantities that can guide system optimization.

  6. AFJU OFC 18(4).indd

    African Journals Online (AJOL)

    imac-1

    at −20 ◦C till the time of the assay of urinary survivin concentrations by ELISA technique ... Data were fed to the computer using the Predictive Analytics Soft- ware (PASW ... expression was evaluated using Receiver Operating Characteristic. (ROC) curve ..... from urine sediments using RT-PCR and real time quantitative RT-.

  7. Validation of a Brief PTSD Scale for Clients with Severe Mental Illnesses

    Science.gov (United States)

    O'Hare, Thomas; Shen, Ce; Sherrer, Margaret

    2012-01-01

    Trauma and Posttraumatic Stress Disorder (PTSD) are more common in severe mental illnesses (SMI) clients than in the general population, yet brief screens for detecting probable PTSD in SMI clients are nonexistent. In a two-part study, the authors used correlation analysis and receiver operating characteristics (ROC) analysis to develop and…

  8. Validation of a self-administered modified CAGE test (CAGE-C) in a somatic hospital ward: comparison with biochemical markers

    DEFF Research Database (Denmark)

    Zierau, F; Hardt, F; Henriksen, Jens Henrik Sahl

    2005-01-01

    . The result of a diagnostic interview with a trained staff member from the local alcohol treatment unit was used as the gold standard. Data were analyzed by means of receiver operating characteristic (ROC) curves. Results. In this population 25 % had an alcohol problem and the questionnaire proved to be valid...

  9. Safety analysis, 200 Area, Savannah River Plant: Separations area operations. Receiving Basin for Offsite Fuel (Supplement 3)

    Energy Technology Data Exchange (ETDEWEB)

    Allen, P M

    1983-09-01

    Analysis of the Savannah River Plant RBOF and RRF included an evaluation of the reliability of process equipment and controls, administrative controls, and engineered safety features. The evaluation also identified potential scenarios and radiological consequences. Risks were calculated in terms of 50-year population dose commitment per year (man-rem/year) to the onsite and offsite population within an 80 Km radius of RBOF and RRF, and to an individual at the plant boundary. The total 50-year onsite and offsite population radiological risks of operating the RBOF and RRF were estimated to be 1.0 man-rem/year. These risks are significantly less than the population dose of 54,000 man/rem/yr for natural background radiation in a 50-mile radius. The 50-year maximum offsite individual risk from operating the facility was estimated to be 2.1 {times} 10{sup 5} rem/yr. These risks are significantly lower than 93 mrem/yr an individual is expected to receive from natural background radiation in this area. The analysis shows. that the RBOF and RRF can be operated without undue risk to onsite personnel or to the general public.

  10. Proximal caries detection: Sirona Sidexis versus Kodak Ektaspeed Plus.

    Science.gov (United States)

    Khan, Emad A; Tyndall, Donald A; Ludlow, John B; Caplan, Daniel

    2005-01-01

    This study compared the accuracy of intraoral film and a charge-coupled device (CCD) receptor for proximal caries detection. Four observers evaluated images of the proximal surfaces of 40 extracted posterior teeth. The presence or absence of caries was scored using a five-point confidence scale. The actual status of each surface was determined from ground section histology. Responses were evaluated by means of receiver operating characteristic (ROC) analysis. Areas under ROC curves (Az) were assessed through a paired t-test. The performance of the CCD-based intraoral sensor was not different statistically from Ektaspeed Plus film in detecting proximal caries.

  11. PROMETHEE-ROC Model for Assessing the Readiness of Technology for Generating Energy

    Directory of Open Access Journals (Sweden)

    Danielle Costa Morais

    2015-01-01

    Full Text Available This paper puts forward a proposal for a multicriteria decision model for prioritizing technologies that are critical for power generation in the energy sector. It deals with the context of imprecise information regarding importance of criteria; then an integration of surrogate weights with the PROMETHEE method is undertaken in order to approach this context. In this type of strategic decision problem, how to deal with imprecise information is always a challenge. The use of surrogate weights presents a significant contribution and it can facilitate the assignment of weights in a decision ranking problem, which requires the decision-maker (DM to order the criteria by their importance for the decision problem. Thus for this situation of assessing the readiness of technology for generating energy where the DM is able and feels comfortable to order all criteria by their relative importance, the proposed approach of surrogate weights in the PROMETHEE II method, the PROMETHEE-ROC model, is shown to be an adequate approach.

  12. Flexible Receiver Radiation Detection System (FRRDS) Users Manual

    International Nuclear Information System (INIS)

    Troyer, G.L.

    1996-01-01

    The Flexible Receiver Radiation Detection System (FRRDS) comprises a control computer, a remote data acquisition subsystem, and three hyperpure germanium gamma radiation detectors. The scope of this document is the description of various steps for the orderly start-up, use, and shutdown of the FRRDS. Only those items necessary for these oprations are included. This document is a companion to WHC-SD-W151-UM-002, 'Operating Instructions for the 42 Inch Flexible Receiver,' WHC-SD-W151-UM-003, 'Operating Instructions for the 4-6 Inch Flexible Receiver,' and the vendor supplied system users guide (Ref. 6)

  13. Combination of Mean Platelet Volume/Platelet Count Ratio and the APACHE II Score Better Predicts the Short-Term Outcome in Patients with Acute Kidney Injury Receiving Continuous Renal Replacement Therapy.

    Science.gov (United States)

    Li, Junhui; Li, Yingchuan; Sheng, Xiaohua; Wang, Feng; Cheng, Dongsheng; Jian, Guihua; Li, Yongguang; Feng, Liang; Wang, Niansong

    2018-03-29

    Both the Acute physiology and Chronic Health Evaluation (APACHE II) score and mean platelet volume/platelet count Ratio (MPR) can independently predict adverse outcomes in critically ill patients. This study was aimed to investigate whether the combination of them could have a better performance in predicting prognosis of patients with acute kidney injury (AKI) who received continuous renal replacement therapy (CRRT). Two hundred twenty-three patients with AKI who underwent CRRT between January 2009 and December 2014 in a Chinese university hospital were enrolled. They were divided into survivals group and non-survivals group based on the situation at discharge. Receiver Operating Characteristic (ROC) curve was used for MPR and APACHE II score, and to determine the optimal cut-off value of MPR for in-hospital mortality. Factors associated with mortality were identified by univariate and multivariate logistic regression analysis. The mean age of the patients was 61.4 years, and the overall in-hospital mortality was 48.4%. Acute cardiorenal syndrome (ACRS) was the most common cause of AKI. The optimal cut-off value of MPR for mortality was 0.099 with an area under the ROC curve (AUC) of 0.636. The AUC increased to 0.851 with the addition of the APACHE II score. The mortality of patients with of MPR > 0.099 was 56.4%, which was significantly higher than that of the control group with of ≤ 0.099 (39.6%, P= 0.012). Logistic regression analysis showed that average number of organ failure (OR = 2.372), APACHE II score (OR = 1.187), age (OR = 1.028) and vasopressors administration (OR = 38.130) were significantly associated with poor prognosis. Severity of illness was significantly associated with prognosis of patients with AKI. The combination of MPR and APACHE II score may be helpful in predicting the short-term outcome of AKI. © 2018 The Author(s). Published by S. Karger AG, Basel.

  14. Combination of Mean Platelet Volume/Platelet Count Ratio and the APACHE II Score Better Predicts the Short-Term Outcome in Patients with Acute Kidney Injury Receiving Continuous Renal Replacement Therapy

    Directory of Open Access Journals (Sweden)

    Junhui Li

    2018-03-01

    Full Text Available Background/Aims: Both the Acute physiology and Chronic Health Evaluation (APACHE II score and mean platelet volume/platelet count Ratio (MPR can independently predict adverse outcomes in critically ill patients. This study was aimed to investigate whether the combination of them could have a better performance in predicting prognosis of patients with acute kidney injury (AKI who received continuous renal replacement therapy (CRRT. Methods: Two hundred twenty-three patients with AKI who underwent CRRT between January 2009 and December 2014 in a Chinese university hospital were enrolled. They were divided into survivals group and non-survivals group based on the situation at discharge. Receiver Operating Characteristic (ROC curve was used for MPR and APACHE II score, and to determine the optimal cut-off value of MPR for in-hospital mortality. Factors associated with mortality were identified by univariate and multivariate logistic regression analysis. Results: The mean age of the patients was 61.4 years, and the overall in-hospital mortality was 48.4%. Acute cardiorenal syndrome (ACRS was the most common cause of AKI. The optimal cut-off value of MPR for mortality was 0.099 with an area under the ROC curve (AUC of 0.636. The AUC increased to 0.851 with the addition of the APACHE II score. The mortality of patients with of MPR > 0.099 was 56.4%, which was significantly higher than that of the control group with of ≤ 0.099 (39.6%, P= 0.012. Logistic regression analysis showed that average number of organ failure (OR = 2.372, APACHE II score (OR = 1.187, age (OR = 1.028 and vasopressors administration (OR = 38.130 were significantly associated with poor prognosis. Conclusion: Severity of illness was significantly associated with prognosis of patients with AKI. The combination of MPR and APACHE II score may be helpful in predicting the short-term outcome of AKI.

  15. Análisis de puntos de rocío y contenidos de humedad de mezclas gaseosas N2-H2O y CH4-H2O

    Directory of Open Access Journals (Sweden)

    D. Bogoya M.

    1995-01-01

    Full Text Available EI conocimiento actual del contenido de humedad de mezclas gaseosas saturadas es aún incompleto, especialmente en la región de altas presiones y bajas temperaturas. Por tanto se realizaron medidas experimentales de punta de rocío con los sistemas nitrógeno-agua y metano-agua, a presiones de 3 y 6 MPa y a temperaturas de 258 K a 288 K. Los puntos de rocío se determinaron con el método del espejo de punta de rocío y los contenidos de humedad por medio de la titulación de Karl-Fischer. Los valores experimentales se compararon con correlaciones de la literatura. El método de Sharma-Campbell resultó ser la mejor descripción del sistema nitrógeno-agua. Para temperaturas inferiores a 273 K la suposición de comportamiento de gas ideal mostro ser suficiente para el sistema metano-agua, mientras que para temperaturas superiores a 273 K los cálculos mediante el principio de estados correspondientes con dos parámetros, en combinación con una corrección de fugacidad, manifestó ser la mejor.

  16. [Value of PUSSOM and P-POSSUM for the prediction of surgical operative risk in patients undergoing pancreaticoduodenectomy for periampullary tumors].

    Science.gov (United States)

    Chen, Yingtai; Chu, Yunmian; Che, Xu; Lan, Zhongmin; Zhang, Jianwei; Wang, Chengfeng

    2015-06-01

    To investigate the value of Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and a modification of the POSSUM system (P-P0SSUM) scoring system in predicting the surgical operative risk of pancreaticoduodenectomy for periampullary tumors. POSSUM and P-POSSUM scoring systems were used to retrospectively evaluate the clinical data of 432 patients with periampullar tumors who underwent pancreaticoduodenectomy in the Department of Abdominal Surgery, Cancer Hospital, Chinese Academy of Medical Sciences from January 1985 to December 2010. The predictive occurrence of postoperative complications and mortality rate were calculated according to the formula. ROC curve analysis and different group of risk factors were used to determine the discrimination ability of the two score systems, and to determine their predictive efficacy by comparing the actual and predictive complications and mortality rates, using Hosmer-Lemeshow test to determine the goodness of fit of the two scoring systems. The average physiological score of the 432 patients was 16.1 ± 3.5, and the average surgical severity score was 19.6 ± 2.7. ROC curve analysis showed that the area under ROC curve for mortality predicted by POSSUM and P-POSSUM were 0.893 and 0.888, showing a non-significant difference (P > 0.05) between them. The area under ROC curve for operative complications predicted by POSSUM scoring system was 0.575. The POSSUM score system was most accurate for the prediction of complication rates of 20%-40%, showing the O/E value of 0.81. Compared with the POSSUM score system, P-POSSUM had better ability in the prediction of postoperative mortality, when the predicted value of mortality was greater than 15%, the predictive result was more accurate, and the O/E value was 1.00. POSSUM and P-POSSUM scoring system have good value in predicting the mortality of patients with periampullary tumors undergoing pancreaticoduodenectomy, but a poorer value of

  17. A final report on the Phase 1 testing of a molten-salt cavity receiver

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, J M [ed.; Smith, D C [Babcock and Wilcox Co., Barberton, OH (United States). Nuclear Equipment Div.

    1992-05-01

    This report describes the design, construction, and testing of a solar central receiver using molten nitrate salt as a heat exchange fluid. Design studies for large commercial plants (30--100 MWe) have shown molten salt to be an excellent fluid for solar thermal plants as it allows for efficient thermal storage. Plant design studies concluded that an advanced receiver test was required to address uncertainties not covered in prior receiver tests. This recommendation led to the current test program managed by Sandia National Laboratories for the US Department of Energy. The 4.5 MWt receiver is installed at Sandia National Laboratories' Central Receiver Test Facility in Albuquerque, New Mexico. The receiver incorporates features of large commercial receiver designs. This report describes the receiver's configuration, heat absorption surface (design and sizing), the structure and supporting systems, and the methods for control. The receiver was solar tested during a six-month period at the Central Receiver Test Facility in Albuquerque, NM. The purpose of the testing was to characterize the operational capabilities of the receiver under a number of solar operating and stand-by conditions. This testing consisted of initial check-out of the systems, followed by steady-state performance, transient receiver operation, receiver operation in clouds, receiver thermal loss testing, receiver start-up operation, and overnight thermal conditioning tests. This report describes the design, fabrication, and results of testing of the receiver.

  18. Spatiotemporal correlation of optical coherence tomography in-vivo images of rabbit airway for the diagnosis of edema

    Science.gov (United States)

    Kang, DongYel; Wang, Alex; Volgger, Veronika; Chen, Zhongping; Wong, Brian J. F.

    2015-07-01

    Detection of an early stage of subglottic edema is vital for airway management and prevention of stenosis, a life-threatening condition in critically ill neonates. As an observer for the task of diagnosing edema in vivo, we investigated spatiotemporal correlation (STC) of full-range optical coherence tomography (OCT) images acquired in the rabbit airway with experimentally simulated edema. Operating the STC observer on OCT images generates STC coefficients as test statistics for the statistical decision task. Resulting from this, the receiver operating characteristic (ROC) curves for the diagnosis of airway edema with full-range OCT in-vivo images were extracted and areas under ROC curves were calculated. These statistically quantified results demonstrated the potential clinical feasibility of the STC method as a means to identify early airway edema.

  19. Colonoscopy can miss diverticula of the left colon identified by barium enema.

    Science.gov (United States)

    Niikura, Ryota; Nagata, Naoyoshi; Shimbo, Takuro; Akiyama, Junichi; Uemura, Naomi

    2013-04-21

    To identify the diagnostic value of colonoscopy for diverticulosis as determined by barium enema. A total of 65 patients with hematochezia who underwent colonoscopy and barium enema were analyzed, and the diagnostic value of colonoscopy for diverticula was assessed. The receiver operating characteristic area under the curve was compared in relation to age (barium enema. Colonoscopy had a sensitivity of 91% and specificity of 90%. No significant differences were found in the receiver operating characteristic area under the curve (ROC-AUC) for age group or sex. The ROC-AUC of the left colon was significantly lower than that of the right colon (0.81 vs 0.96, P = 0.02). Colonoscopy identified 486 colonic diverticula, while barium enema identified 1186. The detection ratio for the entire colon was therefore 0.41 (486/1186). The detection ratio in the left colon (0.32, 189/588) was significantly lower than that of the right colon (0.50, 297/598) (P barium enema, only half the number of colonic diverticula can be detected by colonoscopy in the entire colon and even less in the left colon.

  20. An ROC study detecting ability of idiopathic pulmonary fibrosis using digital radiography

    International Nuclear Information System (INIS)

    Chung, Eun Chul; Im, Jung Gi; Han, Man Chung; Kim, Jong Hyo

    1991-01-01

    One potential advantage of the digital radiography system is its ability to enhance image quality by various types of processing. Digital unsharp masking is one of the simplest and most useful forms of enhancing processes. The efficacy of unsharp masking in radiological diagnosis has not been investigated thoroughly. To evaluate the effects of unsharp masking in film-digital chest images, 3 observers were shown 150 test radiographs. These test radiographs consisted of 50 unprocessed images (25 normals and 25 patients with idiopathic pulmonary fibrosis with honey combing) and their 100 processed images by using 450 and 15-sized masks respectively. An ROC analysis of these data suggests that unsharp masking is more effective in detecting idiopathic pulmonary fibrosis than unprocessed image (ρ < 0.05), and so it may improve diagnostic accuracy for interstitial fibrosis. In addition, the smaller mask size (15) is more effective than the larger one (mask size 45) (ρ < 0.05). By using this analytic approach, an optimal parameter in digital chest radiography may be investigated in many other forms of pulmonary disease such as pulmonary nodule or mediastinal mass

  1. An ROC study detecting ability of idiopathic pulmonary fibrosis using digital radiography

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eun Chul; Im, Jung Gi; Han, Man Chung; Kim, Jong Hyo [College of Medicine, Ewha Womens University, Seoul (Korea, Republic of)

    1991-03-15

    One potential advantage of the digital radiography system is its ability to enhance image quality by various types of processing. Digital unsharp masking is one of the simplest and most useful forms of enhancing processes. The efficacy of unsharp masking in radiological diagnosis has not been investigated thoroughly. To evaluate the effects of unsharp masking in film-digital chest images, 3 observers were shown 150 test radiographs. These test radiographs consisted of 50 unprocessed images (25 normals and 25 patients with idiopathic pulmonary fibrosis with honey combing) and their 100 processed images by using 450 and 15-sized masks respectively. An ROC analysis of these data suggests that unsharp masking is more effective in detecting idiopathic pulmonary fibrosis than unprocessed image ({rho} < 0.05), and so it may improve diagnostic accuracy for interstitial fibrosis. In addition, the smaller mask size (15) is more effective than the larger one (mask size 45) ({rho} < 0.05). By using this analytic approach, an optimal parameter in digital chest radiography may be investigated in many other forms of pulmonary disease such as pulmonary nodule or mediastinal mass.

  2. Determination of a cutoff value for pelvic floor distensibility using the Epi-no balloon to predict perineal integrity in vaginal delivery: ROC curve analysis. Prospective observational single cohort study

    Directory of Open Access Journals (Sweden)

    Miriam Raquel Diniz Zanetti

    Full Text Available CONTEXT AND OBJECTIVE: Several risk factors are involved in perineal lacerations during vaginal delivery. However, little is known about the influence of perineal distensibility as a protective factor. The aim here was to determine a cutoff value for pelvic floor distensibility measured using the Epi-no balloon, which could be used as a predictive factor for perineal integrity in vaginal delivery. DESIGN AND SETTING: Prospective observational single cohort study conducted in a maternity hospital. METHODS: A convenience sample of 227 consecutive at-term parturients was used. All women had a single fetus in the vertex presentation, with up to 9.0 cm of dilation. The maximum dilation of the Epi-no balloon was measured using a tape measure after it had been inflated inside the vagina up to the parturients' maximum tolerance. The receiver operating characteristic (ROC curve was used to obtain the Epi-no circumference measurement with best sensitivity and specificity. RESULTS: Among the 161 patients who were included in the study, 50.9% underwent episiotomy, 21.8% presented lacerations and 27.3% retained an intact perineum. Age > 25.9 years; number of pregnancies > 3.4; number of deliveries > 2.2 and circumference measured by Epi-no > 21.4 cm were all directly correlated with an intact perineum. Circumference measurements using the Epi-no balloon that were greater than 20.8 cm showed sensitivity and specificity of 70.5% and 66.7% (area under curve = 0.713, respectively, as a predictive factor for an intact perineum in vaginal delivery. CONCLUSION: Circumferences greater than 20.8 cm achieved using the Epi-no balloon are a predictive factor for perineal integrity in parturients.

  3. Store-operate-coherence-on-value

    Science.gov (United States)

    Chen, Dong; Heidelberger, Philip; Kumar, Sameer; Ohmacht, Martin; Steinmacher-Burow, Burkhard

    2014-11-18

    A system, method and computer program product for performing various store-operate instructions in a parallel computing environment that includes a plurality of processors and at least one cache memory device. A queue in the system receives, from a processor, a store-operate instruction that specifies under which condition a cache coherence operation is to be invoked. A hardware unit in the system runs the received store-operate instruction. The hardware unit evaluates whether a result of the running the received store-operate instruction satisfies the condition. The hardware unit invokes a cache coherence operation on a cache memory address associated with the received store-operate instruction if the result satisfies the condition. Otherwise, the hardware unit does not invoke the cache coherence operation on the cache memory device.

  4. Detection of pulmonary nodules

    International Nuclear Information System (INIS)

    Vanzulli, A.; Zanello, A.; DelMaschio, M.; Paesano, P.; Panizza, P.; DelMaschio, A.

    1989-01-01

    The authors have prospectively studied 203 pulmonary nodules in 91 patients, selected by CT (gold standard), with both subtraction digital radiography (SDR) and conventional plain film. Subtracted images were obtained by using copper filter inserted between two photostimulable imaging plates. Five radiologists randomly analyzed all conventional and subtracted images. The authors calculated sensitivity, specificity, and positive and negative predictive values for both conventional radiography and SDR. Receiver operating characteristics (ROC) curves were calculated by plotting the number of nodules detected with different degrees of confidence. SDR detected 12% more nodules than conventional radiography. ROC curves demonstrated that the level of confidence was better for SDR (P <.05)

  5. 12 CFR 614.4700 - Financing foreign trade receivables.

    Science.gov (United States)

    2010-01-01

    ... OPERATIONS Banks for Cooperatives and Agricultural Credit Banks Financing International Trade § 614.4700 Financing foreign trade receivables. (a) Banks for cooperatives and agricultural credit banks, under policies adopted by their boards of directors, are authorized to finance foreign trade receivables on...

  6. Methodology for quantitative evaluation of diagnostic performance

    International Nuclear Information System (INIS)

    Metz, C.

    1981-01-01

    Of various approaches that might be taken to the diagnostic performance evaluation problem, Receiver Operating Characteristic (ROC) analysis holds great promise. Further development of the methodology for a unified, objective, and meaningful approach to evaluating the usefulness of medical imaging procedures is done by consideration of statistical significance testing, optimal sequencing of correlated studies, and analysis of observer performance

  7. Analysis of Regional Effects on Market Segment Production

    Science.gov (United States)

    2016-06-01

    Standard Errors (SE). ................................................................................................23  Table 8.  Confusion Matrix ...decision tree models: the number of trees to grow, the shrinkage or learning rate ( lambda ), and the number of splits for each tree. A large number of...mean accession rate. 26 Table 8. Confusion Matrix for Gradient Boosted Decision Tree Model. The receiver operating characteristics (ROC

  8. Receiver subsystem analysis report (RADL Item 4-1). The 10-MWe solar thermal central-receiver pilot plant: Solar-facilities design integration

    Science.gov (United States)

    1982-04-01

    The results of thermal hydraulic, design for the stress analyses which are required to demonstrate that the receiver design for the Barstow Solar Pilot Plant satisfies the general design and performance requirements during the plant's design life are presented. Recommendations are made for receiver operation. The analyses are limited to receiver subsystem major structural parts (primary tower, receiver unit core support structure), pressure parts (absorber panels, feedwater, condensate and steam piping/components, flash tank, and steam mainfold) and shielding.

  9. Rocking at 81 and Rolling at 34: ROC Cut-Off Scores for the Negative Acts Questionnaire–Revised in Serbia

    Science.gov (United States)

    Petrović, Ivana B.; Vukelić, Milica; Čizmić, Svetlana

    2017-01-01

    Researchers are still searching for the ways to identify different categories of employees according to their exposure to negative acts and psychological experience of workplace bullying. We followed Notelaers and Einarsen’s application of the ROC analysis to determine the NAQ-R cut-off scores applying a “lower” and “higher” threshold. The main goal of this research was to develop and test different gold standards of personal and organizational relevance in determining the NAQ-R cut-off scores in a specific cultural and economic context of Serbia. Apart from combining self-labeling as a victim with self-perceived health, the objectives were to test the gold standards developed as a combination of self-labeling with life satisfaction, self-labeling with intention to leave and a complex gold standard based on self-labeling, self-perceived health, life satisfaction and intention to leave taken together. The ROC analysis on Serbian workforce data supports applying of different gold standards. For identifying employees in a preliminary stage of bullying, the most applicable was the gold standard based on self-labeling and intention to leave (score 34 and higher). The most accurate identification of victims could be based on the most complex gold standard (score 81 and higher). This research encourages further investigation of gold standards in different cultures. PMID:28119652

  10. Recognition Memory zROC Slopes for Items with Correct versus Incorrect Source Decisions Discriminate the Dual Process and Unequal Variance Signal Detection Models

    Science.gov (United States)

    Starns, Jeffrey J.; Rotello, Caren M.; Hautus, Michael J.

    2014-01-01

    We tested the dual process and unequal variance signal detection models by jointly modeling recognition and source confidence ratings. The 2 approaches make unique predictions for the slope of the recognition memory zROC function for items with correct versus incorrect source decisions. The standard bivariate Gaussian version of the unequal…

  11. Change in end-tidal carbon dioxide outperforms other surrogates for change in cardiac output during fluid challenge.

    Science.gov (United States)

    Lakhal, K; Nay, M A; Kamel, T; Lortat-Jacob, B; Ehrmann, S; Rozec, B; Boulain, T

    2017-03-01

    During fluid challenge, volume expansion (VE)-induced increase in cardiac output (Δ VE CO) is seldom measured. In patients with shock undergoing strictly controlled mechanical ventilation and receiving VE, we assessed minimally invasive surrogates for Δ VE CO (by transthoracic echocardiography): fluid-induced increases in end-tidal carbon dioxide (Δ VE E'CO2 ); pulse (Δ VE PP), systolic (Δ VE SBP), and mean systemic blood pressure (Δ VE MBP); and femoral artery Doppler flow (Δ VE FemFlow). In the absence of arrhythmia, fluid-induced decrease in heart rate (Δ VE HR) and in pulse pressure respiratory variation (Δ VE PPV) were also evaluated. Areas under the receiver operating characteristic curves (AUC ROC s) reflect the ability to identify a response to VE (Δ VE CO ≥15%). In 86 patients, Δ VE E'CO2 had an AUC ROC =0.82 [interquartile range 0.73-0.90], significantly higher than the AUC ROC for Δ VE PP, Δ VE SBP, Δ VE MBP, and Δ VE FemFlow (AUC ROC =0.61-0.65, all P  1 mm Hg (>0.13 kPa) had good positive (5.0 [2.6-9.8]) and fair negative (0.29 [0.2-0.5]) likelihood ratios. The 16 patients with arrhythmia had similar relationships between Δ VE E'CO2 and Δ VE CO to patients with regular rhythm ( r 2 =0.23 in both subgroups). In 60 patients with no arrhythmia, Δ VE E'CO2 (AUC ROC =0.84 [0.72-0.92]) outperformed Δ VE HR (AUC ROC =0.52 [0.39-0.66], P AUC ROC =0.73 [0.60-0.84], P =0.21). In the 45 patients with no arrhythmia and receiving ventilation with tidal volume AUC ROC =0.86 [0.72-0.95] vs 0.66 [0.49-0.80], P =0.02. Δ VE E'CO2 outperformed Δ VE PP, Δ VE SBP, Δ VE MBP, Δ VE FemFlow, and Δ VE HR and, during protective ventilation, arrhythmia, or both, it also outperformed Δ VE PPV. A value of Δ VE E'CO2 >1 mm Hg (>0.13 kPa) indicated a likely response to VE. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  12. Diagnostic ability of the periapical radiographs and digital image in the detection of the artificial proximal caries

    International Nuclear Information System (INIS)

    Heo, Min Suk; You, Dong Soo

    1994-01-01

    Recently, the digital image was introduced into radiological image. The digital image has the power of contrast enhancement, histogram control, and other digitally enhancement. At the point of the resolution, periapical radiograph is superior to the digital image, but enhanced digital procedure improves the diagnostic ability of the digital image. The purpose of this study was to evaluate the diagnostic ability of artificial proximal caries in conventional radiographs, digital radiographs and enhanced digital radiographs (histogram specification). ROC (Receiver Operating Characteristic) analysis and paired t-test were used for the evaluation of detectability, and following results were acquired: 1. The mean ROC area of conventional radiographs was 0.9274. 2. The mean ROC area of unenhanced digital image was 0.9168. 3. The mean ROC area of enhanced digital image was 0.9339. 4. The diagnostic ability of three imaging methods was not significant difference (p>0.05). So, the digital images had similar diagnostic ability of artificial proximal caries to conventional radiographs. If properly enhanced digital image, it may be superior to conventional radiographs.

  13. Echocardiographic right ventricle longitudinal contraction indices cannot predict ejection fraction in post-operative Fallot children.

    Science.gov (United States)

    Bonnemains, Laurent; Stos, Bertrand; Vaugrenard, Thibaud; Marie, Pierre-Yves; Odille, Freddy; Boudjemline, Younes

    2012-03-01

    To examine in a population of post-operative tetralogy of Fallot patients, the correlation between right ventricle (RV) ejection fractions (EF) computed from magnetic resonance imaging (MRI) and three echocardiographic indices of RV function: TAPSE, longitudinal strain and strain rate. Indeed, these patients present a pulmonary regurgitation which is responsible for progressive dilatation of the RV. An echocardiographic assessment of the RV function would be very useful in determining the timing of pulmonary revalvulation for Fallot patients. However, these indices are generally based on the ventricle contraction in the long axis direction which is impaired in this population and does not seem to correlate with the EF. Thirty-five post-operative tetralogy of Fallot patients and 20 patients with normal RVs were included. In both groups, RVEF, assessed by MRI, was compared with the three echocardiographic indices. Longitudinal strain and strain rates were computed both on the free wall and on the whole RV. No correlation was found between the echocardiographic indices and the MRI EF in our Fallot population. The accuracy of those indices as a diagnostic test of an altered RV was low with Younden's indices varying from -0.18 to 0.5 and areas under the Receiver Operating Characterictic (ROC) curves equal to 0.54 for tricuspid annulus plane systolic excursion, 0.59-0.62 for strain and 0.57-0.63 for strain rate. Three conventional echocardiographic indices based on RV longitudinal contraction failed to assess the EF in our population of post-operative tetralogy of Fallot patients.

  14. Tools to identify linear combination of prognostic factors which maximizes area under receiver operator curve.

    Science.gov (United States)

    Todor, Nicolae; Todor, Irina; Săplăcan, Gavril

    2014-01-01

    The linear combination of variables is an attractive method in many medical analyses targeting a score to classify patients. In the case of ROC curves the most popular problem is to identify the linear combination which maximizes area under curve (AUC). This problem is complete closed when normality assumptions are met. With no assumption of normality search algorithm are avoided because it is accepted that we have to evaluate AUC n(d) times where n is the number of distinct observation and d is the number of variables. For d = 2, using particularities of AUC formula, we described an algorithm which lowered the number of evaluations of AUC from n(2) to n(n-1) + 1. For d > 2 our proposed solution is an approximate method by considering equidistant points on the unit sphere in R(d) where we evaluate AUC. The algorithms were applied to data from our lab to predict response of treatment by a set of molecular markers in cervical cancers patients. In order to evaluate the strength of our algorithms a simulation was added. In the case of no normality presented algorithms are feasible. For many variables computation time could be increased but acceptable.

  15. Conformational and spectroscopic study of xanthogen ethyl formates, ROC(S)SC(O)OCH₂CH₃. Isolation of CH₃CH₂OC(O)SH.

    Science.gov (United States)

    Juncal, Luciana C; Cozzarín, Melina V; Romano, Rosana M

    2015-03-15

    ROC(S)SC(O)OCH2CH3, with R=CH3-, (CH3)2CH- and CH3(CH2)2-, were obtained through the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. The liquid compounds were identified and characterized by (1)H and (13)C NMR and mass spectrometry. The conformations adopted by the molecules were studied by DFT methods. 6 conformers were theoretically predicted for R=CH3- and (CH3)2CH-, while the conformational flexibility of the n-propyl substituent increases the total number of feasible rotamers to 21. For the three molecules, the conformers can be associated in 3 groups, being the most stable the AS forms - the C=S double bond anti (A) with respect to the C-S single bond and the S-C single bond syn (S) with respect to the C=O double bond - followed by AA and SS conformers. The vibrational spectra were interpreted in terms of the predicted conformational equilibrium, presenting the ν(C=O) spectral region signals corresponding to the three groups of conformers. A moderated pre-resonance Raman enhancement of the ν(C=S) vibrational mode of CH3(CH2)2OC(S)SC(O)OCH2CH3 was detected, when the excitation radiation approaches the energy of a n→π∗ electronic transition associated with the C=S chromophore. UV-visible spectra in different solvents were measured and interpreted in terms of TD-DFT calculations. The unknown molecule CH3CH2OC(O)SH was isolated by the UV-visible photolysis of CH3OC(S)SC(O)OCH2CH3 isolated in Ar matrix, and also obtained as a side-product of the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. [Management of patients with bronchial asthma received general anesthesia and surgical intervention].

    Science.gov (United States)

    To, Masako; Tajima, Makoto; Ogawa, Cyuhei; Otomo, Mamoru; Suzuki, Naohito; Sano, Yasuyuki

    2002-01-01

    Stimulation to bronchial mucosa is one of the major risk factor of asthma attack. When patients receive surgical intervention and general anesthesia, they are always exposed to stimulation to bronchial mucosa. Prevention method of bronchial asthma attack during surgical intervention is not established yet. We investigated that clinical course of patients with bronchial asthma who received general anesthesia and surgical intervention. Seventy-six patients with bronchial asthma were received general anesthesia and surgical intervention from 1993 to 1998. Twenty-four patients were mild asthmatic patients, 39 were moderate asthmatic patients and 13 were severe asthmatic patients. Preoperative treatment for preventing asthma attack was as follows; Eight patients were given intravenous infusion of aminophylline before operation. Fifty-two patients were given intravenous infusion of aminophylline and hydrocortisone before operation. Three patients were given intravenous infusion of hydrocortisone for consecutive 3 days before operation. Thirteen patients were given no treatment for preventing asthma attack. One patient was suffered from asthma attack during operation. She was given no preventing treatment for asthma attack before operation. Three patients were suffered from asthma attack after operation. No wound dehiscence was observed in all patients. To prevent asthma attack during operation, intravenous infusion of steroid before operation is recommended, when patients with asthma receive general anesthesia and surgical intervention.

  17. Estimation of doses received by operators in the 1958 RB reactor accident using the MCNP5 computer code simulation

    Directory of Open Access Journals (Sweden)

    Pešić Milan P.

    2012-01-01

    Full Text Available A numerical simulation of the radiological consequences of the RB reactor reactivity excursion accident, which occurred on October 15, 1958, and an estimation of the total doses received by the operators were run by the MCNP5 computer code. The simulation was carried out under the same assumptions as those used in the 1960 IAEA-organized experimental simulation of the accident: total fission energy of 80 MJ released in the accident and the frozen positions of the operators. The time interval of exposure to high doses received by the operators has been estimated. Data on the RB1/1958 reactor core relevant to the accident are given. A short summary of the accident scenario has been updated. A 3-D model of the reactor room and the RB reactor tank, with all the details of the core, created. For dose determination, 3-D simplified, homogenised, sexless and faceless phantoms, placed inside the reactor room, have been developed. The code was run for a number of neutron histories which have given a dose rate uncertainty of less than 2%. For the determination of radiation spectra escaping the reactor core and radiation interaction in the tissue of the phantoms, the MCNP5 code was run (in the KCODE option and “mode n p e”, with a 55-group neutron spectra, 35-group gamma ray spectra and a 10-group electron spectra. The doses were determined by using the conversion of flux density (obtained by the F4 tally in the phantoms to doses using factors taken from ICRP-74 and from the deposited energy of neutrons and gamma rays (obtained by the F6 tally in the phantoms’ tissue. A rough estimation of the time moment when the odour of ozone was sensed by the operators is estimated for the first time and given in Appendix A.1. Calculated total absorbed and equivalent doses are compared to the previously reported ones and an attempt to understand and explain the reasons for the obtained differences has been made. A Root Cause Analysis of the accident was done and

  18. Flurbiprofen improves dysfunction of T-lymphocyte subsets and natural killer cells in cancer patients receiving post-operative morphine analgesia.

    Science.gov (United States)

    Shen, Jin-Chun; Sun, He-Liang; Zhang, Ming-Qiang; Liu, Xiao-Yu; Wang, Zhong- Yun; Yang, Jian-Jun

    2014-08-01

    Acute pain can lead to immune dysfunction, which can be partly ameliorated by successful pain management. Opioids, which are widely used for analgesia, can result in the deterioration of immune function. This study aimed to investigate the influence of morphine with or without flurbiprofen as post-operative analgesics on the immune systems of patients undergoing gastric cancer surgery. 60 patients undergoing gastric cancer surgery were equally randomized into two groups. They received post-operative patient-controlled intravenous (IV) analgesia using morphine either with or without flurbiprofen. Visual analogue scale (VAS) scores, Bruggemann comfort scale (BCS) scores, morphine consumption, time of first flatus, incidence of nausea/vomiting, and T-lymphocyte subsets (CD3⁺, CD4⁺, and CD8⁺) and natural killer cells (CD3⁻CD16⁺CD56⁺) were evaluated. No significant difference was observed in the VAS scores, BCS scores, and nausea/vomiting incidence between groups. Less morphine was consumed and the time of first flatus was earlier in patients receiving morphine with flurbiprofen than morphine alone. The expression of CD3⁺, CD4⁺, CD4⁺/CD8⁺, and CD3⁻CD16⁺CD56⁺ decreased at 2 hours after incision and, except for CD3⁻CD16⁺CD56⁺, returned to baseline at 120 hours after surgery. Moreover, the expression of CD3⁻CD16⁺CD56⁺ at 2 hours after incision and the expression of CD3⁺, CD4⁺, CD4⁺/CD8⁺, and CD3⁻CD16⁺CD56⁺ at 24 hours after surgery were higher in patients receiving morphine with flurbiprofen than morphine alone. The combination of morphine and flurbiprofen ameliorates the immune depression in Tlymphocyte subsets and natural killer cells and provides a similar analgesic efficacy to morphine alone in patients undergoing gastric cancer surgery.

  19. Choice reaction time in patients with post-operative cognitive dysfunction

    DEFF Research Database (Denmark)

    Steinmetz, J.; Rasmussen, L.S.

    2008-01-01

    BACKGROUND: Post-operative cognitive dysfunction (POCD) is detected by administration of a neuropsychological test battery. Reaction time testing is at present not included as a standard test. Choice reaction time (CRT) data from the first International Study of Post-operative Cognitive Dysfunction...... in nine countries. CRT was measured 52 times using the four boxes test. Patients performed the test before surgery (n=1083), at 1 week (n=926) and at 3 months (n=852) post-operatively. CRT for the individual patient was determined as the median time of correct responses. The usefulness of the CRT...... had a significantly longer CRT. ROC curves revealed that a reaction time of 813 ms was the most appropriate cut-off at 1 week and 762 ms at 3 months but the positive predictive value for POCD was low: 34.4% and 14.7%, respectively. CONCLUSIONS: Post-operative cognitive dysfunction is associated...

  20. Lung nodule detection performance in five observers on computed tomography (CT) with adaptive iterative dose reduction using three-dimensional processing (AIDR 3D) in a Japanese multicenter study: Comparison between ultra-low-dose CT and low-dose CT by receiver-operating characteristic analysis.

    Science.gov (United States)

    Nagatani, Yukihiro; Takahashi, Masashi; Murata, Kiyoshi; Ikeda, Mitsuru; Yamashiro, Tsuneo; Miyara, Tetsuhiro; Koyama, Hisanobu; Koyama, Mitsuhiro; Sato, Yukihisa; Moriya, Hiroshi; Noma, Satoshi; Tomiyama, Noriyuki; Ohno, Yoshiharu; Murayama, Sadayuki

    2015-07-01

    To compare lung nodule detection performance (LNDP) in computed tomography (CT) with adaptive iterative dose reduction using three dimensional processing (AIDR3D) between ultra-low dose CT (ULDCT) and low dose CT (LDCT). This was part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIve) Study, a multicenter research project being conducted in Japan. Institutional Review Board approved this study and informed consent was obtained. Eighty-three subjects (body mass index, 23.3 ± 3.2) underwent chest CT at 6 institutions using identical scanners and protocols. In a single visit, each subject was scanned using different tube currents: 240, 120 and 20 mA (3.52, 1.74 and 0.29 mSv, respectively). Axial CT images with 2-mm thickness/increment were reconstructed using AIDR3D. Standard of reference (SOR) was determined based on CT images at 240 mA by consensus reading of 2 board-certificated radiologists as to the presence of lung nodules with the longest diameter (LD) of more than 3mm. Another 5 radiologists independently assessed and recorded presence/absence of lung nodules and their locations by continuously-distributed rating in CT images at 20 mA (ULDCT) and 120 mA (LDCT). Receiver-operating characteristic (ROC) analysis was used to evaluate LNDP of both methods in total and also in subgroups classified by LD (>4, 6 and 8 mm) and nodular characteristics (solid and ground glass nodules). For SOR, 161 solid and 60 ground glass nodules were identified. No significant difference in LNDP for entire solid nodules was demonstrated between both methods, as area under ROC curve (AUC) was 0.844 ± 0.017 in ULDCT and 0.876 ± 0.026 in LDCT (p=0.057). For ground glass nodules with LD 8mm or more, LNDP was similar between both methods, as AUC 0.899 ± 0.038 in ULDCT and 0.941 ± 0.030 in LDCT. (p=0.144). ULDCT using AIDR3D with an equivalent radiation dose to chest x-ray could have comparable LNDP to LDCT with AIDR3D except for smaller ground

  1. Joint confidence region estimation for area under ROC curve and Youden index.

    Science.gov (United States)

    Yin, Jingjing; Tian, Lili

    2014-03-15

    In the field of diagnostic studies, the area under the ROC curve (AUC) serves as an overall measure of a biomarker/diagnostic test's accuracy. Youden index, defined as the overall correct classification rate minus one at the optimal cut-off point, is another popular index. For continuous biomarkers of binary disease status, although researchers mainly evaluate the diagnostic accuracy using AUC, for the purpose of making diagnosis, Youden index provides an important and direct measure of the diagnostic accuracy at the optimal threshold and hence should be taken into consideration in addition to AUC. Furthermore, AUC and Youden index are generally correlated. In this paper, we initiate the idea of evaluating diagnostic accuracy based on AUC and Youden index simultaneously. As the first step toward this direction, this paper only focuses on the confidence region estimation of AUC and Youden index for a single marker. We present both parametric and non-parametric approaches for estimating joint confidence region of AUC and Youden index. We carry out extensive simulation study to evaluate the performance of the proposed methods. In the end, we apply the proposed methods to a real data set. Copyright © 2013 John Wiley & Sons, Ltd.

  2. A ROC-based feature selection method for computer-aided detection and diagnosis

    Science.gov (United States)

    Wang, Songyuan; Zhang, Guopeng; Liao, Qimei; Zhang, Junying; Jiao, Chun; Lu, Hongbing

    2014-03-01

    Image-based computer-aided detection and diagnosis (CAD) has been a very active research topic aiming to assist physicians to detect lesions and distinguish them from benign to malignant. However, the datasets fed into a classifier usually suffer from small number of samples, as well as significantly less samples available in one class (have a disease) than the other, resulting in the classifier's suboptimal performance. How to identifying the most characterizing features of the observed data for lesion detection is critical to improve the sensitivity and minimize false positives of a CAD system. In this study, we propose a novel feature selection method mR-FAST that combines the minimal-redundancymaximal relevance (mRMR) framework with a selection metric FAST (feature assessment by sliding thresholds) based on the area under a ROC curve (AUC) generated on optimal simple linear discriminants. With three feature datasets extracted from CAD systems for colon polyps and bladder cancer, we show that the space of candidate features selected by mR-FAST is more characterizing for lesion detection with higher AUC, enabling to find a compact subset of superior features at low cost.

  3. Plasma metabolic changes in Chinese HIV-infected patients receiving lopinavir/ritonavir based treatment: Implications for HIV precision therapy.

    Science.gov (United States)

    Li, Xiaolin; Wu, Tong; Jiang, Yongjun; Zhang, Zining; Han, Xiaoxu; Geng, Wenqing; Ding, Haibo; Kang, Jing; Wang, Qi; Shang, Hong

    2018-05-16

    The goal of this study is to profile the metabolic changes in the plasma of HIV patients receiving lopinavir/ritonavir (LPV/r)-based highly active antiretroviral therapy (HAART) relative to their treatment-naïve phase, aimed to identify precision therapy for HIV for improving prognosis and predicting dyslipidemia caused by LPV/r. 38 longitudinal plasma samples were collected from 19 HIV-infected patients both before and after antiretroviral therapy, and 18 samples from healthy individuals were used as controls. Untargeted metabolomics profiling of these plasma samples was performed using liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). A total of 331 compounds of known identity were detected among these metabolites, a 67-metabolite signature mainly mapping to tryptophan, histidine, acyl carnitine, ketone bodies and fatty acid metabolism distinguished HIV patients from healthy controls. The levels of 19 out of the 67 altered metabolites including histidine, kynurenine, and 3-hydroxybutyrate (BHBA), recovered after LPV/r-based antiretroviral therapy, and histidine was positively correlated with the presence of CD4 + T lymphocytes. Furthermore, using receiver operating characteristic (ROC) analyses, we discovered that butyrylcarnitine in combination with myristic acid from plasma in treatment-naïve patients could predict dyslipidemia caused by LPV/r with 87% accuracy. Metabolites alterations in treatment-naïve HIV patients may indicate an inflammatory, oxidative state and mitochondrial dysfunction that is permissive for disease progression. Histidine may provide a specific protective function for HIV patients. Besides, elevated fatty acids levels including butyrylcarnitine and myristic acid after infection may indicate patients at risk of suffering from dyslipidemia after LPV/r-based HAART. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. 10-MWe pilot-plant-receiver panel test requirements document solar thermal test facility

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-25

    Testing plans for a full-scale test receiver panel and supporting hardware which essentially duplicate both physically and functionally, the design planned for the Barstow Solar Pilot Plant are presented. Testing is to include operation during normal start and shutdown, intermittent cloud conditions, and emergencies to determine the panel's transient and steady state operating characteristics and performance under conditions equal to or exceeding those expected in the pilot plant. The effects of variations of input and output conditions on receiver operation are also to be investigated. Test hardware are described, including the pilot plant receiver, the test receiver assembly, receiver panel, flow control, electrical control and instrumentation, and structural assembly. Requirements for the Solar Thermal Test Facility for the tests are given. The safety of the system is briefly discussed, and procedures are described for assembly, installation, checkout, normal and abnormal operations, maintenance, removal and disposition. Also briefly discussed are quality assurance, contract responsibilities, and test documentation. (LEW)

  5. Significance of MPEG-7 textural features for improved mass detection in mammography.

    Science.gov (United States)

    Eltonsy, Nevine H; Tourassi, Georgia D; Fadeev, Aleksey; Elmaghraby, Adel S

    2006-01-01

    The purpose of the study is to investigate the significance of MPEG-7 textural features for improving the detection of masses in screening mammograms. The detection scheme was originally based on morphological directional neighborhood features extracted from mammographic regions of interest (ROIs). Receiver Operating Characteristics (ROC) was performed to evaluate the performance of each set of features independently and merged into a back-propagation artificial neural network (BPANN) using the leave-one-out sampling scheme (LOOSS). The study was based on a database of 668 mammographic ROIs (340 depicting cancer regions and 328 depicting normal parenchyma). Overall, the ROC area index of the BPANN using the directional morphological features was Az=0.85+/-0.01. The MPEG-7 edge histogram descriptor-based BPNN showed an ROC area index of Az=0.71+/-0.01 while homogeneous textural descriptors using 30 and 120 channels helped the BPNN achieve similar ROC area indexes of Az=0.882+/-0.02 and Az=0.877+/-0.01 respectively. After merging the MPEG-7 homogeneous textural features with the directional neighborhood features the performance of the BPANN increased providing an ROC area index of Az=0.91+/-0.01. MPEG-7 homogeneous textural descriptor significantly improved the morphology-based detection scheme.

  6. Complex analysis of the ionospheric response to operation of ``Progress'' cargo spacecraft according to the data of GNSS receivers in Baikal region

    Science.gov (United States)

    Ishin, Artem; Voeykov, Sergey; Perevalova, Natalia; Khakhinov, Vitaliy

    2017-12-01

    As a part of the Plasma-Progress and Radar-Progress space experiments conducted from 2006 to 2014, effects of the Progress spacecraft engines on the ionosphere have been studied using data from Global Navigation Satellite System (GNSS) receivers. 72 experiments have been carried out. All these experiments were based on data from the International GNSS Service (IGS) to record ionospheric plasma irregularities caused by engine operation. 35 experiments used data from the ISTP SB RAS network SibNet. The analysis of the spatio-temporal structure of total electron content (TEC) variations has shown that the problem of identifying the TEC response to engine operation is complicated by a number of factors: 1) the engine effect on ionospheric plasma is strongly localized in space and has a relatively low intensity; 2) a small number of satellite-receiver radio rays due to the limited number of GNSS stations, particularly before 2013; 3) a potential TEC response is masked with background ionospheric disturbances of various intensities. However, TEC responses are identified with certainty when a satellite-receiver radio ray crosses a disturbed region within minutes after the impact. TEC responses have been registered in 7 experiments (10 % of cases). The amplitude of ionospheric response (0.3-0.16 TECU) exceeded the background TEC variations (~0.25 TECU) several times. The TEC data indicate that the ionospheric irregularity lifetime is from 4 to 10 minutes. According to the estimates we made, the transverse size of irregularities is from 12 to 30 km.

  7. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Directory of Open Access Journals (Sweden)

    Cheng Chuantong

    2017-07-01

    Full Text Available Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  8. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Science.gov (United States)

    Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

    2017-07-01

    Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs) in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  9. Monitor quality and its importance in a picture archiving and communications system display workstation

    International Nuclear Information System (INIS)

    Dawood, R.M.; Todd-Prokropek, A.; Craig, J.O.M.C.; Highman, J.H.; Glass, H.D.

    1988-01-01

    Trials have compared image quality using receiver operating characteristic (ROC) curves for different digitization resolution, particularly on hard copy. Resolution required for such systems is critical. Monitor quality significantly affects results of such studies. Several ''high-quality'' monitors were tested for gray level uniformity, flicker, resolution, stationarity (including distortion), jitter, and stability with time. An ROC study has demonstrated that such errors, on one commercially available system, were large enough to degrade image display at both 1k x 1k and 2k x 2k matrix sizes. Flicker was very disturbing with difficult images. Greater attention to these factors is required in designing (and evaluating) picture archiving and communication system work stations

  10. Evaluation of CT in hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Norio; Miura, Yukio; Ohnishi, Mitsunori; Kamikon-ya, Norihiko; Sakamoto, Yoshisato; Miura, Takashi; Sakamoto, Kiyoshi; Takayasu, Yoshio

    1985-06-01

    In order to evaluate the diagnostic ability of CT in hepatocellular carcinoma, four kinds of CT images were comparatively studied by the accuracy and ROC (receiver operating characteristic) curve analysis. As a result, it was clarified that CT images were evaluated more objectively by ROC curve analysis than by accuracy. The diagnostic ability of existence and differentiation of tumor in the liver were higher in order of plain CT, contrast enhanced CT (CECT), bolus CT and CT arteriography (CTA). Therefore, in an usual CT examination intended to make differential diagnosis in space occupying liver disease, bolus CT seems to be indispensable, and also CTA is essential where diagnosis is difficult even by bolus CT.

  11. Cryogen-free dilution refrigerator for ACTPOL polarization- sensitive receiver

    Science.gov (United States)

    Shvarts, V.; Zhao, Z.; Devlin, M. J.; Klein, J.; Lungu, M.; Schmitt, B.; Thornton, R.

    2014-12-01

    We present a new cryogenic receiver for the Atacama Cosmology Telescope (ACT), a six-meter diameter off-axis Gregorian telescope located at an altitude of 5,200 meters (17,000 ft.) on Cerro Toco, in Northern Chile. The focal plane contains 3000 polarization-sensitive transition edge sensor (TES) bolometers, and is cooled to below 100 mK with a removable pulse-tube based customised JDry-100 dilution refrigerator insert. The optical tubes and the rest of the receiver are cooled with a dedicated pulse tube to below 3 K. Details of the receiver- to-telescope integration and first season on-site operation are described, including detector base temperature stability in vertical and tilted position as well as remote operation via Ethernet link.

  12. Cryogen-free dilution refrigerator for ACTPOL polarization- sensitive receiver

    International Nuclear Information System (INIS)

    Shvarts, V; Zhao, Z; Devlin, M J; Klein, J; Lungu, M; Schmitt, B; Thornton, R

    2014-01-01

    We present a new cryogenic receiver for the Atacama Cosmology Telescope (ACT), a six-meter diameter off-axis Gregorian telescope located at an altitude of 5,200 meters (17,000 ft.) on Cerro Toco, in Northern Chile. The focal plane contains 3000 polarization-sensitive transition edge sensor (TES) bolometers, and is cooled to below 100 mK with a removable pulse-tube based customised JDry-100 dilution refrigerator insert. The optical tubes and the rest of the receiver are cooled with a dedicated pulse tube to below 3 K. Details of the receiver- to-telescope integration and first season on-site operation are described, including detector base temperature stability in vertical and tilted position as well as remote operation via Ethernet link

  13. Application of Data Mining Algorithm to Recipient of Motorcycle Installment

    Directory of Open Access Journals (Sweden)

    Harry Dhika

    2015-12-01

    Full Text Available The study was conducted in the subsidiaries that provide services of finance related to the purchase of a motorcycle on credit. At the time of applying, consumers enter their personal data. Based on the personal data, it will be known whether the consumer credit data is approved or rejected. From 224 consumer data obtained, it is known that the number of consumers whose applications are approved is 87% or about 217 consumers and consumers whose application is rejected is 16% or as much as 6 consumers. Acceptance of motorcycle financing on credit by using the method of applying the algorithm through CRIS-P DM is the industry standard in the processing of data mining. The algorithm used in the decision making is the algorithm C4.5. The results obtained previously, the level of accuracy is measured with the Confusion Matrix and Receiver Operating characteristic (ROC. Evaluation of the Confusion Matrix is intended to seek the value of accuracy, precision value, and the value of recall data. While the Receiver Operating Characteristic (ROC is used to find data tables and comparison Area Under Curve (AUC.

  14. Development of the KIPPOD-IN-DIAPR solar thermal receiver

    International Nuclear Information System (INIS)

    Karni, J.; Rubin, R.; Kribus, A.

    1992-12-01

    Initial tests of the 50 kw DIAPR solar receiver have been conducted in the WIS Solar Furnace, at a power level of 11 kw. These tests show that the receiver components, and especially the novel window, are capable of stable operation at extreme conditions. A total of about 50 hours under solar load, including about 20 on-off cycles, were completed. all experiments were at high pressure, in the range of 15-25 bars. Asymmetric temperature distribution and accidental contamination of the window during the first run created thermal stresses on the window which exceeded those expected in normal operation at full load, but neither failure nor deterioration of the window were detected. Internal modifications of the receiver are planned that will reduce the temperature gradients and allow more efficient operation. Work is now in progress to modify and install the receiver in the WIS solar tower and test it at full 50 kw load in the summer of 93. The two-dimensional numerical simulation code is nearly completed, and produces energy balance and temperature range consistent with the experimental results. When extended to three dimensions it will serve to analyze the experimental results, to perform parametric studies and to assist in up scaling design. (authors). 2 refs., 7 figs., 1 tab

  15. Full-size solar dynamic heat receiver thermal-vacuum tests

    Science.gov (United States)

    Sedgwick, L. M.; Kaufmann, K. J.; Mclallin, K. L.; Kerslake, T. W.

    1991-01-01

    The testing of a full-size, 102 kW, solar dynamic heat receiver utilizing high-temperature thermal energy storage is described. The purpose of the test program was to quantify receiver thermodynamic performance, operating temperatures, and thermal response to changes in environmental and power module interface boundary conditions. The heat receiver was tested in a vacuum chamber with liquid nitrogen cold shrouds and an aperture cold plate to partly simulate a low-Earth-orbit environment. The cavity of the receiver was heated by an infrared quartz lamp heater with 30 independently controllable zones to allow axially and circumferentially varied flux distributions. A closed-Brayton cycle engine simulator conditioned a helium-xenon gas mixture to specific interface conditions to simulate the various operational modes of the solar dynamic power module on the Space Station Freedom. Inlet gas temperature, pressure, and flow rate were independently varied. A total of 58 simulated orbital cycles, each 94 minutes in duration, was completed during the test period.

  16. Receiving more than data - a signal model, theory and implementation of a cognitive IEEE 802.15.4 receiver

    Directory of Open Access Journals (Sweden)

    Tim Esemann

    2016-09-01

    Full Text Available Standard medium access schemes sense the channel immediately prior transmission, but are blind during the transmission. Therefore, standard transceivers have limited cognitive capabilities which are important for operation in heterogeneous radio environments. Specifically, mobile interferers move gradually into the reception range before actually causing collisions. These gradual interferences cannot yet be detected, and upcoming collisions cannot be predicted. We present a theoretical analysis of the received and demodulated signal. This analysis and the derived signal model verifies that the received signal contains more than transmitted data exclusively. Enhanced signal processing extracts signal components of an interference at the receiver and enables advanced interference detection to provide information about approaching mobile interferers. Our theoretical analysis is evaluated by simulations and experiments with an IEEE 802.15.4 transmitter and an extended cognitive receiver.

  17. Dish/stirling hybrid-receiver

    Science.gov (United States)

    Mehos, Mark S.; Anselmo, Kenneth M.; Moreno, James B.; Andraka, Charles E.; Rawlinson, K. Scott; Corey, John; Bohn, Mark S.

    2002-01-01

    A hybrid high-temperature solar receiver is provided which comprises a solar heat-pipe-receiver including a front dome having a solar absorber surface for receiving concentrated solar energy, a heat pipe wick, a rear dome, a sidewall joining the front and the rear dome, and a vapor and a return liquid tube connecting to an engine, and a fossil fuel fired combustion system in radial integration with the sidewall for simultaneous operation with the solar heat pipe receiver, the combustion system comprising an air and fuel pre-mixer, an outer cooling jacket for tangentially introducing and cooling the mixture, a recuperator for preheating the mixture, a burner plenum having an inner and an outer wall, a porous cylindrical metal matrix burner firing radially inward facing a sodium vapor sink, the mixture ignited downstream of the matrix forming combustion products, an exhaust plenum, a fossil-fuel heat-input surface having an outer surface covered with a pin-fin array, the combustion products flowing through the array to give up additional heat to the receiver, and an inner surface covered with an extension of the heat-pipe wick, a pin-fin shroud sealed to the burner and exhaust plenums, an end seal, a flue-gas diversion tube and a flue-gas valve for use at off-design conditions to limit the temperature of the pre-heated air and fuel mixture, preventing pre-ignition.

  18. The first Latin-American risk stratification system for cardiac surgery: can be used as a graphic pocket-card score.

    Science.gov (United States)

    Carosella, Victorio C; Navia, Jose L; Al-Ruzzeh, Sharif; Grancelli, Hugo; Rodriguez, Walter; Cardenas, Cesar; Bilbao, Jorge; Nojek, Carlos

    2009-08-01

    This study aims to develop the first Latin-American risk model that can be used as a simple, pocket-card graphic score at bedside. The risk model was developed on 2903 patients who underwent cardiac surgery at the Spanish Hospital of Buenos Aires, Argentina, between June 1994 and December 1999. Internal validation was performed on 708 patients between January 2000 and June 2001 at the same center. External validation was performed on 1087 patients between February 2000 and January 2007 at three other centers in Argentina. In the development dataset the area under receiver operating characteristics (ROC) curve was 0.73 and the Hosmer-Lemeshow (HL) test was P=0.88. In the internal validation ROC curve was 0.77. In the external validation ROC curve was 0.81, but imperfect calibration was detected because the observed in-hospital mortality (3.96%) was significantly lower than the development dataset (8.20%) (Pgraphic pocket-card score allows an easy bedside application with acceptable statistic precision.

  19. Screening for depressive disorders using the MASQ anhedonic depression scale: A receiver-operator characteristic analysis

    Science.gov (United States)

    Bredemeier, Keith; Spielberg, Jeffrey M.; Silton, Rebecca Levin; Berenbaum, Howard; Heller, Wendy; Miller, Gregory A.

    2010-01-01

    The present study examined the utility of the anhedonic depression scale from the Mood and Anxiety Symptoms Questionnaire (MASQ-AD) as a way to screen for depressive disorders. Using receiver-operator characteristic analysis, the sensitivity and specificity of the full 22-item MASQ-AD scale, as well as the 8 and 14-item subscales, were examined in relation to both current and lifetime DSM-IV depressive disorder diagnoses in two nonpatient samples. As a means of comparison, the sensitivity and specificity of a measure of a relevant personality dimension, neuroticism, was also examined. Results from both samples support the clinical utility of the MASQ-AD scale as a means of screening for depressive disorders. Findings were strongest for the MASQ-AD 8-item subscale and when predicting current depression status. Furthermore, the MASQ-AD 8-item subscale outperformed the neuroticism measure under certain conditions. The overall usefulness of the MASQ-AD scale as a screening device is discussed, as well as possible cutoff scores for use in research. PMID:20822283

  20. Is there an additional benefit of serial NT-proBNP measurements in patients with stable chronic heart failure receiving individually optimized therapy?

    Science.gov (United States)

    Franke, Jennifer; Frankenstein, Lutz; Schellberg, Dieter; Bajrovic, Amer; Wolter, Jan Sebastian; Ehlermann, Philipp; Doesch, Andreas O; Nelles, Manfred; Katus, Hugo A; Zugck, Christian

    2011-12-01

    The role of serial NT-proBNP measurements in patients suffering from chronic systolic heart failure (CHF) who already receive individually optimized pharmacotherapy is still unresolved. NT-proBNP was assessed at baseline and at 6 months follow-up in 504 stable CHF patients treated with individually optimized pharmacotherapy. After assessment of clinical stability at 6 months, patients were followed up for at least 1 year. The combined primary endpoint was defined as death, hospitalization due to cardiac reasons or heart transplantation in 1-year follow-up. We stratified our patients according to two principles: first, a percent change of value (CV) between the first and second measurement of NT-proBNP and secondly, the transformed logarithm of NT-proBNP measured at 6 months. During the follow-up period of 1 year, 50 patients (9.9%) reached the combined primary endpoint. Stratification according to percentage CV was less accurate in predicting endpoint-free survival compared to a classification in categories of lnNT-proBNP measured at 6 months (ROC AUC = 0.615; 95% CI 0.525-0.70 vs. ROC AUC = 0.790; 95% CI 0.721-0.856, respectively). When entered into proportional hazard regression analysis, lnNT-proBNP measured at 6 months remained an independent predictor of the combined primary endpoint with an associated HR of 2.53 (95% CI 1.385-4.280). To date, this is the largest analysis of serial NT-proBNP measurements in patients with CHF receiving individually optimized medical therapy. These data suggest that a single NT-proBNP measurement after 6 months in stable clinical conditions may have higher predictive value than stratification of change in serial measurements.

  1. Space charge calibration of the ALICE TPC operated with an open gating grid

    Energy Technology Data Exchange (ETDEWEB)

    Hellbaer, Ernst [Institut fuer Kernphysik, Goethe-Universitaet Frankfurt (Germany); Ivanov, Marian [GSI (Germany); Wiechula, Jens [Universitaet Tuebingen (Germany); Collaboration: ALICE-Collaboration

    2015-07-01

    The Time Projection Chamber (TPC) is the main particle identification detector of the ALICE experiment at the CERN LHC. High interaction rates of 50 kHz in Pb-Pb during the Run 3 period after 2020 require a major upgrade of the TPC readout. The currently used Multiwire Proportional Chambers (MWPCs) will be replaced by readout chambers (ROCs) based on Gas Electron Multiplier (GEM) technology which will be operated in a continuous mode. While the gating grid of the MWPCs prevents the positive ions of the amplification region from entering the drift volume, the GEM-based ROCs will introduce an ion backflow (IBF) of about 1%. In combination with the high-luminosity environment, this amount of back-drifting ions results in a considerable space charge density which distorts the drift path of the primary ionisation electrons significantly. In order to still provide a high tracking efficiency and cluster-to-track association, an efficient calibration scheme will be implemented. As a test ground for the new calibration scheme, pp collision data was taken during Run 1 with the gating grid operated in a transparent mode allowing the ions to enter the drift volume. The measured space point distortions due to the space charge are presented together with the corrected data and compared to simulations for Run 3.

  2. Electronic warfare receivers and receiving systems

    CERN Document Server

    Poisel, Richard A

    2014-01-01

    Receivers systems are considered the core of electronic warfare (EW) intercept systems. Without them, the fundamental purpose of such systems is null and void. This book considers the major elements that make up receiver systems and the receivers that go in them.This resource provides system design engineers with techniques for design and development of EW receivers for modern modulations (spread spectrum) in addition to receivers for older, common modulation formats. Each major module in these receivers is considered in detail. Design information is included as well as performance tradeoffs o

  3. VGC analyzer: a software for statistical analysis of fully crossed multiple-reader multiple-case visual grading characteristics studies

    International Nuclear Information System (INIS)

    Baath, Magnus; Hansson, Jonny

    2016-01-01

    Visual grading characteristics (VGC) analysis is a non-parametric rank-invariant method for analysis of visual grading data. In VGC analysis, image quality ratings for two different conditions are compared by producing a VGC curve, similar to how the ratings for normal and abnormal cases in receiver operating characteristic (ROC) analysis are used to create an ROC curve. The use of established ROC software for the analysis of VGC data has therefore previously been proposed. However, the ROC analysis is based on the assumption of independence between normal and abnormal cases. In VGC analysis, this independence cannot always be assumed, e.g. if the ratings are based on the same patients imaged under both conditions. A dedicated software intended for analysis of VGC studies, which takes possible dependencies between ratings into account in the statistical analysis of a VGC study, has therefore been developed. The software-VGC Analyzer-determines the area under the VGC curve and its uncertainty using non-parametric re-sampling techniques. This article gives an introduction to VGC Analyzer, describes the types of analyses that can be performed and instructs the user about the input and output data. (authors)

  4. Accuracy of an automated system for tuberculosis detection on chest radiographs in high-risk screening.

    Science.gov (United States)

    Melendez, J; Hogeweg, L; Sánchez, C I; Philipsen, R H H M; Aldridge, R W; Hayward, A C; Abubakar, I; van Ginneken, B; Story, A

    2018-05-01

    Tuberculosis (TB) screening programmes can be optimised by reducing the number of chest radiographs (CXRs) requiring interpretation by human experts. To evaluate the performance of computerised detection software in triaging CXRs in a high-throughput digital mobile TB screening programme. A retrospective evaluation of the software was performed on a database of 38 961 postero-anterior CXRs from unique individuals seen between 2005 and 2010, 87 of whom were diagnosed with TB. The software generated a TB likelihood score for each CXR. This score was compared with a reference standard for notified active pulmonary TB using receiver operating characteristic (ROC) curve and localisation ROC (LROC) curve analyses. On ROC curve analysis, software specificity was 55.71% (95%CI 55.21-56.20) and negative predictive value was 99.98% (95%CI 99.95-99.99), at a sensitivity of 95%. The area under the ROC curve was 0.90 (95%CI 0.86-0.93). Results of the LROC curve analysis were similar. The software could identify more than half of the normal images in a TB screening setting while maintaining high sensitivity, and may therefore be used for triage.

  5. Binary and multi-category ratings in a laboratory observer performance study: A comparison

    OpenAIRE

    Gur, David; Bandos, Andriy I.; King, Jill L.; Klym, Amy H.; Cohen, Cathy S.; Hakim, Christiane M.; Hardesty, Lara A.; Ganott, Marie A.; Perrin, Ronald L.; Poller, William R.; Shah, Ratan; Sumkin, Jules H.; Wallace, Luisa P.; Rockette, Howard E.

    2008-01-01

    The authors investigated radiologists, performances during retrospective interpretation of screening mammograms when using a binary decision whether to recall a woman for additional procedures or not and compared it with their receiver operating characteristic (ROC) type performance curves using a semi-continuous rating scale. Under an Institutional Review Board approved protocol nine experienced radiologists independently rated an enriched set of 155 examinations that they had not personally...

  6. Assessing antiquity and turnover of terrestrial ecosystems in eastern North America using fossil pollen data: A preliminary study

    International Nuclear Information System (INIS)

    Liu Yao; Jackson, Stephen T; Brewer, Simon; Williams, John W

    2010-01-01

    We explored formal approaches to identifying and interpreting the antiquity and turnover of terrestrial ecosystems in eastern North America using pollen records. Preliminary results of cluster analyses, receiver-operating characteristic (ROC) analyses, and likelihood estimation of ecosystem analog in a simple Bayesian model allow assessment of modern ecosystem antiquities and past ecosystem turnovers. Approaches discussed in this study thus provide a vehicle for further studies.

  7. Bayesian modeling and inference for diagnostic accuracy and probability of disease based on multiple diagnostic biomarkers with and without a perfect reference standard.

    Science.gov (United States)

    Jafarzadeh, S Reza; Johnson, Wesley O; Gardner, Ian A

    2016-03-15

    The area under the receiver operating characteristic (ROC) curve (AUC) is used as a performance metric for quantitative tests. Although multiple biomarkers may be available for diagnostic or screening purposes, diagnostic accuracy is often assessed individually rather than in combination. In this paper, we consider the interesting problem of combining multiple biomarkers for use in a single diagnostic criterion with the goal of improving the diagnostic accuracy above that of an individual biomarker. The diagnostic criterion created from multiple biomarkers is based on the predictive probability of disease, conditional on given multiple biomarker outcomes. If the computed predictive probability exceeds a specified cutoff, the corresponding subject is allocated as 'diseased'. This defines a standard diagnostic criterion that has its own ROC curve, namely, the combined ROC (cROC). The AUC metric for cROC, namely, the combined AUC (cAUC), is used to compare the predictive criterion based on multiple biomarkers to one based on fewer biomarkers. A multivariate random-effects model is proposed for modeling multiple normally distributed dependent scores. Bayesian methods for estimating ROC curves and corresponding (marginal) AUCs are developed when a perfect reference standard is not available. In addition, cAUCs are computed to compare the accuracy of different combinations of biomarkers for diagnosis. The methods are evaluated using simulations and are applied to data for Johne's disease (paratuberculosis) in cattle. Copyright © 2015 John Wiley & Sons, Ltd.

  8. Using TV Receiver Information to Increase Cognitive White Space Spectrum

    OpenAIRE

    Ellingsæter, Brage; Bezabih, Hemdan; Noll, Josef; Maseng, Torleiv

    2012-01-01

    In this paper we investigate the usage of cognitive radio devices within the service area of TV broadcast stations. Until now the main approach for a cognitive radio to operate in the TV bands has been to register TV broadcast stations locations and thus protecting the broadcast stations service area. Through information about TV receivers location, we show that a cognitive radio should be able to operate within this service area without causing harmful interference to the TV receivers as def...

  9. Solar central receiver reformer system for ammonia plants

    Science.gov (United States)

    1980-07-01

    An overview of a study to retrofit the Valley Nitrogen Producers, Inc., El Centro, California 600 ST/SD Ammonia Plant with Solar Central Receiver Technology is presented. The retrofit system consists of a solar central receiver reformer (SCRR) operating in parallel with the existing fossil fired reformer. Steam and hydrocarbon react in the catalyst filled tubes of the inner cavity receiver to form a hydrogen rich mixture which is the syngas feed for the ammonia production. The SCRR system will displace natural gas presently used in the fossil reformer combustion chamber.

  10. Communication received from the Resident Representative of the Russian Federation to the IAEA on the establishment, structure and operation of the International Uranium Enrichment Centre

    International Nuclear Information System (INIS)

    2007-01-01

    The Director General has received a communication dated 7 June 2007 from the Resident Representative of the Russian Federation, with an attachment entitled 'Establishment, Structure and Operation of the International Uranium Enrichment Centre'. As requested in that communication, the letter and its attachment are circulated for the information of Member States

  11. Initial results for compressive sensing in electronic support receiver systems

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2011-04-01

    Full Text Available determined by the antenna and microwave system comprising the transmitter and receiver, while the instantaneous bandwidth is mainly determined by the Analog-to-Digital Converter (ADC) in the receiver. A radar can thus operate at any frequency within its... Electronic/Electromagnetic Support Measures (ESM) was used historically [1], [2]. Modern ES receiver systems are based on digital receivers allowing powerful signal processing techniques to be used [3], [4]. Recent developments in sampling technology...

  12. Review and future perspective of central receiver design and performance

    Science.gov (United States)

    Zhu, Guangdong; Libby, Cara

    2017-06-01

    Concentrating solar power (CSP) technology provides a commercial solar option to the utility-scale electricity market. CSP is unique in its ability to include low-cost thermal storage; thus, it can generate electricity when the sun is not available and dispatch electricity to meet varying load requirements. Within the suite of CSP technologies, the central receiver design represents the state-of-the-art technology, promising low cost, high performance, and dispatchable energy production. Current total capacity of central receiver plants worldwide is about 1.0 gigawatt (electric) with operating plants in Spain and the United States, as well as projects under construction in Asia, the Middle East, and North Africa. Central receiver technology has been under development since the 1950s, and a variety of central receiver designs have been explored. A distinguishing feature is the heat transfer medium. Central receiver designs exist that use dense fluids, gases, and solid particles in this role. Water/steam and molten salt receivers have been adopted in current commercial plants and are often coupled with a steam-Rankine power cycle with an operating temperature of less than 600°C. Many new central receiver concepts, such as the volumetric air, supercritical carbon dioxide (sCO2), solid particle, and liquid-metal receiver designs, are under active research and development (R&D). New designs target operating temperatures generally higher than 700°C-800°C—and even above 1000°C—so that higher-performance power cycles such as the sCO2-Brayton cycle or air-Brayton/steam-Rankine combined cycle can be used to promote greater overall system efficiency. Central receiver thermal storage provides dispatchability unavailable from variable-output renewables such as solar photovoltaic and wind power. Case study analysis of the California grid shows that there is a limit on the amount of non-dispatchable renewable generation that the grid can accommodate, beyond which

  13. Review and Future Perspective of Central Receiver Design and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Guangdong; Libby, Cara

    2017-06-27

    Concentrating solar power (CSP) technology provides a commercial solar option to the utility-scale electricity market. CSP is unique in its ability to include low-cost thermal storage; thus, it can generate electricity when the sun is not available and dispatch electricity to meet varying load requirements. Within the suite of CSP technologies, the central receiver design represents the state-of-the-art technology, promising low cost, high performance, and dispatchable energy production. Current total capacity of central receiver plants worldwide is about 1.0 gigawatt (electric) with operating plants in Spain and the United States, as well as projects under construction in Asia, the Middle East, and North Africa. Central receiver technology has been under development since the 1950s, and a variety of central receiver designs have been explored. A distinguishing feature is the heat transfer medium. Central receiver designs exist that use dense fluids, gases, and solid particles in this role. Water/steam and molten salt receivers have been adopted in current commercial plants and are often coupled with a steam-Rankine power cycle with an operating temperature of less than 600 degrees C. Many new central receiver concepts, such as the volumetric air, supercritical carbon dioxide (sCO2), solid particle, and liquid-metal receiver designs, are under active research and development (R&D). New designs target operating temperatures generally higher than 700 degrees C-800 degrees C -- and even above 1000 degrees C -- so that higher-performance power cycles such as the sCO2-Brayton cycle or air-Brayton/steam-Rankine combined cycle can be used to promote greater overall system efficiency. Central receiver thermal storage provides dispatchability unavailable from variable-output renewables such as solar photovoltaic and wind power. Case study analysis of the California grid shows that there is a limit on the amount of non-dispatchable renewable generation that the grid can

  14. In the digital era, architectural distortion remains a challenging radiological task

    International Nuclear Information System (INIS)

    Suleiman, W.I.; McEntee, M.F.; Lewis, S.J.; Rawashdeh, M.A.; Georgian-Smith, D.; Heard, R.; Tapia, K.; Brennan, P.C.

    2016-01-01

    Aim: To compare readers' performance in detecting architectural distortion (AD) compared with other breast cancer types using digital mammography. Materials and methods: Forty-one experienced breast screen readers (20 US and 21 Australian) were asked to read a single test set of 30 digitally acquired mammographic cases. Twenty cases had abnormal findings (10 with AD, 10 non-AD) and 10 cases were normal. Each reader was asked to locate and rate any abnormalities. Lesion and case-based performance was assessed. For each collection of readers (US; Australian; combined), jackknife free-response receiver operating characteristic (JAFROC), figure of merit (FOM), and inferred receiver operating characteristic (ROC), area under curve (Az) were calculated using JAFROC v.4.1 software. Readers' sensitivity, location sensitivity, JAFROC, FOM, ROC, Az scores were compared between cases groups using Wilcoxon's signed ranked test statistics. Results: For lesion-based analysis, significantly lower location sensitivity (p=0.001) was shown on AD cases compared with non-AD cases for all reader collections. The case-based analysis demonstrated significantly lower ROC Az values (p=0.02) for the first collection of readers, and lower sensitivity for the second collection of readers (p=0.04) and all-readers collection (p=0.008), for AD compared with non-AD cases. Conclusions: The current work demonstrates that AD remains a challenging task for readers, even in the digital era. - Highlights: • Architectural Distortion interpretation remains challenging for readers even with digital acquisition. • Significantly lower location sensitivity and sensitivity values for the AD were shown.

  15. Billing and accounts receivable: fundamentals for improvement.

    Science.gov (United States)

    Bizon, M M

    1993-07-01

    If a healthcare facility's accounts receivable operation is experiencing problems, the patient accounts manager should survey all areas of his or her responsibility to determine the best method of resolving the difficulties. One effective technique to reduce billing problems is to take a proactive--not reactive--approach. If mistakes can be corrected before they get out of control, and if the patient accounts manager can ensure that claims will not be denied, a healthcare facility's accounts receivable should remain in good condition.

  16. Histogram analysis of diffusion kurtosis imaging derived maps may distinguish between low and high grade gliomas before surgery.

    Science.gov (United States)

    Qi, Xi-Xun; Shi, Da-Fa; Ren, Si-Xie; Zhang, Su-Ya; Li, Long; Li, Qing-Chang; Guan, Li-Ming

    2018-04-01

    To investigate the value of histogram analysis of diffusion kurtosis imaging (DKI) maps in the evaluation of glioma grading. A total of 39 glioma patients who underwent preoperative magnetic resonance imaging (MRI) were classified into low-grade (13 cases) and high-grade (26 cases) glioma groups. Parametric DKI maps were derived, and histogram metrics between low- and high-grade gliomas were analysed. The optimum diagnostic thresholds of the parameters, area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were achieved using a receiver operating characteristic (ROC). Significant differences were observed not only in 12 metrics of histogram DKI parameters (PHistogram analysis of DKI may be more effective in glioma grading.

  17. Structural analysis of a reflux pool-boiler solar receiver

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, E.L.; Stone, C.M.

    1991-06-01

    Coupled thermal-structural finite element calculations of a reflux pool-boiler solar receiver were performed to characterize the operating stresses and to address issues affecting the service life of the receiver. Analyses performed using shell elements provided information for receiver material selection and design optimization. Calculations based on linear elastic fracture mechanics principles were performed using continuum elements to assess the vulnerability of a seam-weld to fatigue crack growth. All calculations were performed using ABAQUS, a general purpose finite element code, and elements specifically formulated for coupled thermal-structural analysis. Two materials were evaluated: 316L SS and Haynes 230 alloys. The receiver response was simulated for a combination of structural and thermal loads that represent the startup and operating conditions of the receiver. For both materials, maximum stresses in the receiver developed shortly after startup due to uneven temperature distribution across the receiver surface. The largest effective stress was near yield in the 316L SS receiver and below 39 percent of yield in the Haynes 230 receiver. The calculations demonstrated that stress reductions of over 25 percent could be obtained by reducing the aft dome thickness to one closer to the absorber. The fatigue calculations demonstrated that the stress distribution near the seam-weld notch depends primarily on the structural load created by internal pressurization of the receiver rather than the thermal, indicating that the thermal loads can be neglected when assessing the stress intensity near the seam-weld notch. The stress intensity factor, computed using the J-integral method and crack opening-displacement field equations, was significantly below the fatigue threshold for most steels. The calculations indicated that the weld notch was always loaded in compression, a condition which is not conducive to fatigue crack growth. 15 refs., 30 figs., 3 tabs.

  18. Phantom gastric mucosa for evaluating computed radiography in double-contrast upper gastrointestinal examinations

    International Nuclear Information System (INIS)

    Murakami, M.; Watanabe, H.; Nakata, H.

    1996-01-01

    To test the clinical usefulness of computed radiography (CR) with a storage phosphor plate in upper gastrointestinal radiographic examinations, a newly devised phantom gastric mucosa was used. Simulated small elevated and depressed lesions were created on a phantom gastric mucosa made from a styrofoam 'plate'. Twenty-four sets of each CR and screen-film radiographs (SR) were obtained using phototimed exposures. Receiver operating characteristic (ROC) study and visual ranking using these images were performed. There was no significant difference between the ROC curves of CR and SR. By visual ranking, CR was equal to or better than SR in most cases. In no case was SR definitely superior to CR. CR can be safely applied in upper gastrointestinal roentgenologic examinations. (orig.)

  19. Differentiating pheochromocytoma from lipid-poor adrenocortical adenoma by CT texture analysis: feasibility study.

    Science.gov (United States)

    Zhang, Gu-Mu-Yang; Shi, Bing; Sun, Hao; Jin, Zheng-Yu; Xue, Hua-Dan

    2017-09-01

    To investigate the feasibility of using CT texture analysis (CTTA) to differentiate pheochromocytoma from lipid-poor adrenocortical adenoma (lp-ACA). Ninety-eight pheochromocytomas and 66 lp-ACAs were included in this retrospective study. CTTA was performed on unenhanced and enhanced images. Receiver operating characteristic (ROC) analysis was performed, and the area under the ROC curve (AUC) was calculated for texture parameters that were significantly different for the objective. Diagnostic accuracies were evaluated using the cutoff values of texture parameters with the highest AUCs. Compared to lp-ACAs, pheochromocytomas had significantly higher mean gray-level intensity (Mean), entropy, and mean of positive pixels (MPP), but lower skewness and kurtosis on unenhanced images (P feasible to use CTTA to differentiate pheochromocytoma from lp-ACA.

  20. Determination of dose received by bladder and rectum in external cervical irradiation

    International Nuclear Information System (INIS)

    Omer, Mohamed Ahmed Ali

    2001-12-01

    The cervical carcinoma is the common type of malignant tumor among sudanese females during the last years. The conventional external irradiation therapy is the common model of treatment for cervical carcinoma in (RICK). The irradiation of such cases implemented via four fields (box technique), two anterior and posterior and two lateral opposed fields, as central dose calculation, giving a dose of 5000 c Gy fractionated into 25 to 30 fractions. The parameter of the fields lie at the promontory of the sacral cephalic and at the obturators foramen caudally and laterally at the bony pelvic by one centimeter. The aim of the research is to determine the dose received by the rectum and bladder (critical organs), out of central dose calculation versus off axis dose calculation to (Day's method). The data obtained by using simulator and radiation oncological computerized system (Rocs). The results are analyzed by using statistical processing for social science program (SPSS) that shows the mean dose received by the bladder is 3821 cGy, due to central dose calculation that accompanied by an un-optimum encompassment of treatment line and 4210.6 c Gy. due to Off Axis Dose calculation dose 3324.4 c Gy and 3712.1 c Gy due to central dose calculation. The increment of dose received by the rectum and the bladder is due to utilizing of wider width of the filed size for lateral irradiation. To score the aim of International Atomic Energy Agency (IAEA) and (ALARA) principle A s Low As As Reasonable Available , we have to use the simulator to obtain the anatomical structures on the contour, or will be better to use CT. Scan for calculation of dose at the side of interest. (Author)

  1. HIGH-EFFICIENCY INFRARED RECEIVER

    Directory of Open Access Journals (Sweden)

    A. K. Esman

    2016-01-01

    Full Text Available Recent research and development show promising use of high-performance solid-state receivers of the electromagnetic radiation. These receivers are based on the low-barrier Schottky diodes. The approach to the design of the receivers on the basis of delta-doped low-barrier Schottky diodes with beam leads without bias is especially actively developing because for uncooled receivers of the microwave radiation these diodes have virtually no competition. The purpose of this work is to improve the main parameters and characteristics that determine the practical relevance of the receivers of mid-infrared electromagnetic radiation at the operating room temperature by modifying the electrodes configuration of the diode and optimizing the distance between them. Proposed original design solution of the integrated receiver of mid-infrared radiation on the basis of the low-barrier Schottky diodes with beam leads allows to effectively adjust its main parameters and characteristics. Simulation of the electromagnetic characteristics of the proposed receiver by using the software package HFSS with the basic algorithm of a finite element method which implemented to calculate the behavior of electromagnetic fields on an arbitrary geometry with a predetermined material properties have shown that when the inner parts of the electrodes of the low-barrier Schottky diode is performed in the concentric elliptical convex-concave shape, it can be reduce the reflection losses to -57.75 dB and the standing wave ratio to 1.003 while increasing the directivity up to 23 at a wavelength of 6.09 μm. At this time, the rounded radii of the inner parts of the anode and cathode electrodes are equal 212 nm and 318 nm respectively and the gap setting between them is 106 nm. These parameters will improve the efficiency of the developed infrared optical-promising and electronic equipment for various purposes intended for work in the mid-infrared wavelength range. 

  2. Analyzing ROC curves using the effective set-size model

    Science.gov (United States)

    Samuelson, Frank W.; Abbey, Craig K.; He, Xin

    2018-03-01

    The Effective Set-Size model has been used to describe uncertainty in various signal detection experiments. The model regards images as if they were an effective number (M*) of searchable locations, where the observer treats each location as a location-known-exactly detection task with signals having average detectability d'. The model assumes a rational observer behaves as if he searches an effective number of independent locations and follows signal detection theory at each location. Thus the location-known-exactly detectability (d') and the effective number of independent locations M* fully characterize search performance. In this model the image rating in a single-response task is assumed to be the maximum response that the observer would assign to these many locations. The model has been used by a number of other researchers, and is well corroborated. We examine this model as a way of differentiating imaging tasks that radiologists perform. Tasks involving more searching or location uncertainty may have higher estimated M* values. In this work we applied the Effective Set-Size model to a number of medical imaging data sets. The data sets include radiologists reading screening and diagnostic mammography with and without computer-aided diagnosis (CAD), and breast tomosynthesis. We developed an algorithm to fit the model parameters using two-sample maximum-likelihood ordinal regression, similar to the classic bi-normal model. The resulting model ROC curves are rational and fit the observed data well. We find that the distributions of M* and d' differ significantly among these data sets, and differ between pairs of imaging systems within studies. For example, on average tomosynthesis increased readers' d' values, while CAD reduced the M* parameters. We demonstrate that the model parameters M* and d' are correlated. We conclude that the Effective Set-Size model may be a useful way of differentiating location uncertainty from the diagnostic uncertainty in medical

  3. Front end power dissipation minimization and optimal transmission rate for wireless receivers

    NARCIS (Netherlands)

    Heuvel, van den J.H.C.; Wu, Y.; Baltus, P.G.M.; Linnartz, J.P.M.G.; Roermund, van A.H.M.

    2014-01-01

    Most wireless battery-operated devices spend more energy receiving than transmitting. Hence, minimizing the power dissipation in the receiver front end, which, in many cases, is the prominent power consuming part of the receiver, is an important challenge. This paper addresses this challenge by

  4. ROCView: prototype software for data collection in jackknife alternative free-response receiver operating characteristic analysis

    Science.gov (United States)

    Thompson, J; Hogg, P; Thompson, S; Manning, D; Szczepura, K

    2012-01-01

    ROCView has been developed as an image display and response capture (IDRC) solution to image display and consistent recording of reader responses in relation to the free-response receiver operating characteristic paradigm. A web-based solution to IDRC for observer response studies allows observations to be completed from any location, assuming that display performance and viewing conditions are consistent with the study being completed. The simplistic functionality of the software allows observations to be completed without supervision. ROCView can display images from multiple modalities, in a randomised order if required. Following registration, observers are prompted to begin their image evaluation. All data are recorded via mouse clicks, one to localise (mark) and one to score confidence (rate) using either an ordinal or continuous rating scale. Up to nine “mark-rating” pairs can be made per image. Unmarked images are given a default score of zero. Upon completion of the study, both true-positive and false-positive reports can be downloaded and adapted for analysis. ROCView has the potential to be a useful tool in the assessment of modality performance difference for a range of imaging methods. PMID:22573294

  5. Predicting glucose intolerance with normal fasting plasma glucose by the components of the metabolic syndrome

    International Nuclear Information System (INIS)

    Pei, D.; Lin, J.; Kuo, S.; Wu, D.; Li, J.; Hsieh, C.; Wu, C.; Hung, Y.; Kuo, K.

    2007-01-01

    Surprisingly it is estimated that about half of type 2 diabetics remain undetected. The possible causes may be partly attributable to people with normal fasting plasma glucose (FPG) but abnormal postprandial hyperglycemia. We attempted to develop an effective predictive model by using the metabolic syndrome (MeS) components as parameters to identify such persons. All participants received a standard 75 gm oral glucose tolerance test which showed that 106 had normal glucose tolerance, 61 had impaired glucose tolerance and 6 had diabetes on isolated postchallenge hyperglycemia. We tested five models which included various MeS components. Model 0: FPG; Model 1 (Clinical history model): family history (FH), FPG, age and sex; Model 2 (MeS model): Model 1 plus triglycerides, high-density lipoprotein cholesterol, body mass index, systolic blood pressure and diastolic blood pressure; Model 3: Model 2 plus fasting plasma insulin (FPI); Model 4: Model 3 plus homeostasis model assessment of insulin resistance. A receiver-operating characteristic (ROC) curve was used to determine the predictive discrimination of these models. The area under the ROC curve of the Model 0 was significantly larger than the area under the diagonal reference line. All the other 4 models had a larger area under the ROC curve than Model 0. Considering the simplicity and lower cost of Model 2, it would be the best model to use. Nevertheless, Model 3 had the largest area under the ROC curve. We demonstrated that Model 2 and 3 have a significantly better predictive discrimination to identify persons with normal FPG at high risk for glucose intolerance. (author)

  6. Lung nodule detection performance in five observers on computed tomography (CT) with adaptive iterative dose reduction using three-dimensional processing (AIDR 3D) in a Japanese multicenter study: Comparison between ultra-low-dose CT and low-dose CT by receiver-operating characteristic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nagatani, Yukihiro, E-mail: yatsushi@belle.shiga-med.ac.jp [Department of Radiology, Shiga University of Medical Science, Otsu 520-2192, Shiga (Japan); Takahashi, Masashi; Murata, Kiyoshi [Department of Radiology, Shiga University of Medical Science, Otsu 520-2192, Shiga (Japan); Ikeda, Mitsuru [Department of Radiological and Medical Laboratory Science, Nagoya University Graduate School of Medicine, Nagoya 461-8673, Aichi (Japan); Yamashiro, Tsuneo [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan); Miyara, Tetsuhiro [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan); Department of Radiology, Okinawa Prefectural Yaeyama Hospital, Ishigaki 907-0022, Okinawa (Japan); Koyama, Hisanobu [Department of Radiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Hyogo (Japan); Koyama, Mitsuhiro [Department of Radiology, Osaka Medical College, Takatsuki 569-8686, Osaka (Japan); Sato, Yukihisa [Department of Radiology, Osaka University Graduate School of Medicine, Suita 565-0871, Osaka (Japan); Department of Radiology, Osaka Medical Center of Cancer and Cardiovascular Diseases, Osaka 537-8511, Osaka (Japan); Moriya, Hiroshi [Department of Radiology, Ohara General Hospital, Fukushima 960-8611 (Japan); Noma, Satoshi [Department of Radiology, Tenri Hospital, Tenri 632-8552, Nara (Japan); Tomiyama, Noriyuki [Department of Radiology, Osaka University Graduate School of Medicine, Suita 565-0871, Osaka (Japan); Ohno, Yoshiharu [Department of Radiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Hyogo (Japan); Murayama, Sadayuki [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan)

    2015-07-15

    Highlights: • Using AIDR 3D, ULDCT showed comparable LND of solid nodules to LDCT. • Using AIDR 3D, LND of smaller GGN in ULDCT was inferior to that in LDCT. • Effective dose in ULDCT was about only twice of that in chest X-ray. • BMI values in study population were mostly in the normal range body habitus. - Abstract: Purpose: To compare lung nodule detection performance (LNDP) in computed tomography (CT) with adaptive iterative dose reduction using three dimensional processing (AIDR3D) between ultra-low dose CT (ULDCT) and low dose CT (LDCT). Materials and methods: This was part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIve) Study, a multicenter research project being conducted in Japan. Institutional Review Board approved this study and informed consent was obtained. Eighty-three subjects (body mass index, 23.3 ± 3.2) underwent chest CT at 6 institutions using identical scanners and protocols. In a single visit, each subject was scanned using different tube currents: 240, 120 and 20 mA (3.52, 1.74 and 0.29 mSv, respectively). Axial CT images with 2-mm thickness/increment were reconstructed using AIDR3D. Standard of reference (SOR) was determined based on CT images at 240 mA by consensus reading of 2 board-certificated radiologists as to the presence of lung nodules with the longest diameter (LD) of more than 3 mm. Another 5 radiologists independently assessed and recorded presence/absence of lung nodules and their locations by continuously-distributed rating in CT images at 20 mA (ULDCT) and 120 mA (LDCT). Receiver-operating characteristic (ROC) analysis was used to evaluate LNDP of both methods in total and also in subgroups classified by LD (>4, 6 and 8 mm) and nodular characteristics (solid and ground glass nodules). Results: For SOR, 161 solid and 60 ground glass nodules were identified. No significant difference in LNDP for entire solid nodules was demonstrated between both methods, as area under ROC

  7. The Issues of the Management of Receivables: Lithuanian Case

    Directory of Open Access Journals (Sweden)

    Remeikiene Rita

    2016-06-01

    Full Text Available Constant changes in business environment determine the significance of receivables to business. The analysis of the current situation in Lithuania has revealed that a substantial part of business enterprises are facing the problem of overdue receivables. This issue emerged as extremely topical after the beginning of the economic crisis in 2008. A number of scientific studies confirmed that the level of receivables has a significant impact not only on smooth business operation but also on operational results and serves as the cause of numerous economic and social problems, faced by both business enterprises and the state. Rising level of receivables determines slower recovery of total economics because it has a negative impact on the sustainability of the public sector of the country. In addition, the scientists highlight economic problems such as production capacity losses, general decrease in competitiveness and failure to satisfy the debt claims. The social problems include the increase in unemployment rate, fall of living standards, dissatisfaction with poor economics of the country and uncertainty about the future. The aim of this article is to analyse the impact of receivables on business in Lithuania. The methods of the research include scientific literature analysis and statistical data analysis.

  8. Operational performance of the development of a 15 kW parabolic trough mid-temperature solar receiver/reactor for hydrogen production

    International Nuclear Information System (INIS)

    Hong, Hui; Liu, Qibin; Jin, Hongguang

    2012-01-01

    Highlights: ► A 15 kW solar chemical receiver/reactor for hydrogen production was developed. ► The solar thermochemical efficiency of the receiver/reactor was in the range of 20–28%. ► Hydrogen production exceeding 80% was achieved. ► The research results extend the application of mid-temperature solar thermal energy. -- Abstract: In this paper, we report the operational performance and energy conversion efficiency of a developed 15 kW solar chemical receiver/reactor for hydrogen production. A concentrated solar heat of around 200–300 °C was utilized to provide process heat to drive methanol steam reforming. A modified 15 kW direct-irradiation solar reactor coupled with a linear receiver positioned along the focal line of a one-axis parabolic trough concentrator was used. The experiments were conducted from 200 to 300 °C under a mean solar flux of 300–800 W/m 2 and a reactant feeding rate of 6 kg/h. Reactants were continuously fed, and the attained conversion rate of methanol was more than 70% at 700 W/m 2 . The typical solar thermochemical efficiency of solar thermal energy converted into chemical energy was in the 20–28% range. The overall energy efficiency of input solar power conversion into chemical energy reached up to 17% and may be further increased by improving solar field efficiency. Hydrogen production exceeding 80% was achieved. In addition, preliminary economic evaluation was performed, and methods for further improvement were proposed. This paper proves that solar hydrogen production is feasible by combining solar thermal energy with alternative fuel at around 200–300 °C, which is much lower than the temperature of other solar thermochemical processes. This may offer an economic approach to solar fuel production and extend the application of mid-temperature solar thermal energy.

  9. Comparison of Peristat Online Perimetry with the Humphrey Perimetry in a Clinic-Based Setting

    OpenAIRE

    Lowry, Eugene A.; Hou, Jing; Hennein, Lauren; Chang, Robert T.; Lin, Shan; Keenan, Jeremy; Wang, Sean K.; Ianchulev, Sean; Pasquale, Louis R.; Han, Ying

    2016-01-01

    Purpose We determined the receiver operating characteristic (ROC) curves for Peristat online perimetry at detecting varying degrees of glaucoma and the correlation between Peristat online perimetry and Humphrey visual field. Methods: A prospective, comparative study of Peristat online perimetry (an achromatic static computer threshold testing program) and Humphrey visual field (HVF) 24-2 SITA standard testing was performed by 63 glaucoma patients and 30 healthy controls in random order. The n...

  10. Use of commercial robotics in radioactive waste shipping and receiving

    International Nuclear Information System (INIS)

    Berger, J.D.

    1985-01-01

    Radioactive waste shipping and receiving facilities presently planned for commercial and defense nuclear waste will handle waste packages at frequencies far in excess of those in common practice today. Unacceptable personnel exposure to ionizing radiation is projected to occur if current limits for radiation levels at the cask surface and current handling methods are used. To reduce these exposure levels, alternate handling methods are being developed and demonstrated. The production nature of cask receiving operations suggests commercial robotics be incorporated into a remote handling system to reduce predicted worker exposure to acceptable levels, while maintaining or increasing throughput. The first phase of cask handling system development culminated in a proof-of-principle test demonstrating the feasibility of performing cask receiving and unloading operations in a remote and partially automated manner. 6 refs., 12 figs

  11. [Law for the protection of returned overseas Chinese 7 September 1990].

    Science.gov (United States)

    1990-09-10

    The full text of the Beijing, China law on protection of returned overseas Chinese (ROC) (gui giao 2981 0294) and overseas Chinese families (OCF) (gui giao 0294 4187) is reported as effective on January 1, 1991 and adopted by the 7th National People's Congress Standing Committee on September 7, 1990. There are 22 articles. The 1st 2 articles define the population referred to: ROC are those Chinese who have returned and settled in China. OCF are those who have settled abroad. Family includes parents, children, spouses, brothers, sisters, grandparents, and grandchildren, and other relative receiving longterm support form overseas Chinese (OC). ROC and OCF have the same citizen rights and obligations prescribed in the constitution and other laws. ROC shall be resettled by the state. Concentrations of ROC in an area assures representation in the National People's Congress and people's congresses. ROC and OC have the right to organize social groups; the property of social groups is protected by law. In article 7, the state assures support for ranches and tree farms and school and medical care. Article 8 provides for local government support for investments of ROC, OC and OCF in industry and land commerce. Article 9 indicates government support at all levels for public services; tariffs will be reduced or exempted on donated materials and equipment brought from abroad. Private ownership of houses of ROC and OC is secured in article 10, and compensation is provided if the state appropriates the housing. ROC students and children of ROC and OC children in China are assured of support for education and employment assistance in article 11. Remittances of ROC and OCF received from abroad are protected in article 12. Article 13 secures the right of ROC and OCF to inheritance and gifts from relatives living abroad. ROC and OCF may dispose of overseas property. Article 15 requires examination of departure applications by relevant authorities. Emergency situations are accounted

  12. Use of the ROC model for optimalization in radiotherapy for head and neck cancers. Pt. 2. Cancer of the oral cavity

    International Nuclear Information System (INIS)

    Maciejewski, B.; Zajusz, A.; Rota, L.

    1993-01-01

    The ROC model is used to estimate optimal radiation treatment for cancer of the oral cavity. For 210 patients with cancer of the oral cavity iso-utility curves and k values were determined for various tumors stages and overall treatment times. Optimal k value decreases from 0.792 to 0.584 when overall treatment time is prolonged from 35 to 49 days. It may suggest that the planning of extra dose to balance the effect of extension of overall treatment time does not really improve therapeutic gain. (author)

  13. Personal monitoring and assessment of doses received by radiation workers

    International Nuclear Information System (INIS)

    Swindon, T.N.; Morris, N.D.

    1981-12-01

    The Personal Radiation Monitoring Service operated by the Australian Radiation Laboratory is outlined and the types of monitors used for assessment of doses received by radiation workers are described. The distribution of doses received by radiation workers in different occupational categories is determined. From these distributions, the average doses received have been assessed and the maximum likely additional increase in cancer deaths in Australia as a result of occupational exposure estimated. This increase is shown to be very small. There is, however, a considerable spread of doses received by individuals within occupational groups

  14. Lateral epicondylitis. Associations of MR imaging and clinical assessments with treatment options in patients receiving conservative and arthroscopic managements

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Ji Young [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Gachon University, Department of Radiology, Incheon (Korea, Republic of); Lee, Min Hee; Chung, Hye Won; Lee, Sang Hoon; Shin, Myung Jin [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Jeon, In-Ho [University of Ulsan College of Medicine, Department of Orthopedic Surgery, Seoul (Korea, Republic of)

    2018-03-15

    We assessed the implications of MR imaging with clinical history in lateral epicondylitis management by evaluating imaging and clinical features in patients with lateral epicondylitis treated conservatively or operatively. Sixty patients with lateral epicondylitis treated conservatively (n = 38) or operatively (n = 22) from 2011-2015 were included. MR imaging findings of common extensor tendon (CET), lateral collateral ligament (LCL) complex, muscle oedema, ulnar nerve and elbow joint were reviewed. Clinical data recorded were frequency, duration and intensity of pain, history of trauma and injection therapy, range of motion. MRI-assessed CET and LCL complex abnormalities, muscle oedema, radiocapitellar joint widening, joint effusion/synovitis, pain frequency and intensity differed significantly between the two groups (p <.05) with increased severity in operative group. Persistent pain (OR 12.2, p <.01), CET abnormality on longitudinal plane (OR 7.5, p =.03 for grade 2; OR 22.4, p <.01 for grade 3) and muscle oedema (OR 6.7, p =.03) were major factors associated with operative treatment. Area under the ROC curve of predicted probabilities for combination of these factors was 0.83. MR imaging, combined with clinical assessment, could facilitate appropriate management planning for patients with lateral epicondylitis. (orig.)

  15. Lateral epicondylitis. Associations of MR imaging and clinical assessments with treatment options in patients receiving conservative and arthroscopic managements

    International Nuclear Information System (INIS)

    Jeon, Ji Young; Lee, Min Hee; Chung, Hye Won; Lee, Sang Hoon; Shin, Myung Jin; Jeon, In-Ho

    2018-01-01

    We assessed the implications of MR imaging with clinical history in lateral epicondylitis management by evaluating imaging and clinical features in patients with lateral epicondylitis treated conservatively or operatively. Sixty patients with lateral epicondylitis treated conservatively (n = 38) or operatively (n = 22) from 2011-2015 were included. MR imaging findings of common extensor tendon (CET), lateral collateral ligament (LCL) complex, muscle oedema, ulnar nerve and elbow joint were reviewed. Clinical data recorded were frequency, duration and intensity of pain, history of trauma and injection therapy, range of motion. MRI-assessed CET and LCL complex abnormalities, muscle oedema, radiocapitellar joint widening, joint effusion/synovitis, pain frequency and intensity differed significantly between the two groups (p <.05) with increased severity in operative group. Persistent pain (OR 12.2, p <.01), CET abnormality on longitudinal plane (OR 7.5, p =.03 for grade 2; OR 22.4, p <.01 for grade 3) and muscle oedema (OR 6.7, p =.03) were major factors associated with operative treatment. Area under the ROC curve of predicted probabilities for combination of these factors was 0.83. MR imaging, combined with clinical assessment, could facilitate appropriate management planning for patients with lateral epicondylitis. (orig.)

  16. Receiver gain function: the actual NMR receiver gain

    OpenAIRE

    Mo, Huaping; Harwood, John S.; Raftery, Daniel

    2010-01-01

    The observed NMR signal size depends on the receiver gain parameter. We propose a receiver gain function to characterize how much the raw FID is amplified by the receiver as a function of the receiver gain setting. Although the receiver is linear for a fixed gain setting, the actual gain of the receiver may differ from what the gain setting suggests. Nevertheless, for a given receiver, we demonstrate that the receiver gain function can be calibrated. Such a calibration enables accurate compar...

  17. Financial reserve. Hospitals leery of credit lines, factoring receivables.

    Science.gov (United States)

    Edwards, D E; Hamilton, W C; Hauser, R

    1991-10-01

    Opening lines of credit and factoring (selling) accounts receivable are two ways to generate operating cash that non-healthcare industries have long used successfully. A recent survey of hospital officials across the nation, however, showed these techniques are used infrequently in health care. Among the 281 hospitals responding: Only 45 percent use lines of credit; Less than 5 percent pursue accounts receivable factoring; and Only 12 percent plan to begin factoring receivables in the future. As hospitals look for ways to offset depleted cash reserves, these percentages may increase.

  18. The functional improvement and reduction of operators' work at LNG receiving terminal

    International Nuclear Information System (INIS)

    Tomiyama, H.

    1997-01-01

    The Tokyo Gas Negishi Terminal has undergone a series of major changes since starting operation in 1966, including a change in the main feedstock from oil to LNG, and expansion of processing volume and scale. Control of the terminal has been in the form of centralized control and monitoring from a central control room. High technical levels have been maintained, this being one of the first terminals to adopt direct digital control (DDC) as the technology became available. In 1995, a distributed control system (DCS) was introduced as part of a large-scale redevelopment project at the Negishi Terminal, extending the scope of operations and monitoring by operators by full automation of controls, and improvement of functions including integration and upgrading of monitoring. The result has been a significant reduction in the workload on operators. The installation of these functions required further investment of around 1 billion yen, in addition to the cost of renewal of the facility. In spite of the major expansion of the range of facilities under control, the number of operators working 24-hours shifts has been reduced, and over 15 years cost reductions equivalent to around twice the investment cost are expected to be made. (au)

  19. Quantifying diagnostic performance: The log odds method as a practical option

    International Nuclear Information System (INIS)

    Haslam, Maxine; Manning, David

    2006-01-01

    Purpose: To investigate the most practical option available when statistically analysing small sample size studies. Method: The log odds ratio was applied to a study which took a retrospective approach and involved 50 patients who had undergone a ventilation and perfusion scan in the period between 01 January 2002 and 31 December 2002. Radiology reports and the patients' medical records were obtained, so that the clinical indications for the examination and the patients' medical history could be transferred onto the report form. Four radiographers who are routinely rotated into the Nuclear Medicine Department independently reported the same 50 ventilations and perfusion scans under identical conditions to the reporting radiologist. Results: Taking the radiologist reports as the gold standard the radiographers had an accuracy rate of 78%. The radiographers recorded an average sensitivity value of 94% and specificity value of 63%, with an A z reading of 0.71. Conclusion: As the sample size was too small for a receiver operating characteristic (ROC) curve to be drawn, the log odds ratio provided a value, which represents an area under the receiver operating characteristic (ROC) curve, which in turn ensured the results were statistically reliable. The log odds ratio enables researchers to carry out small-scale research without harbouring the data collected by unreliable analysis

  20. Turbo Decision Aided Receivers for Clipping Noise Mitigation in Coded OFDM

    Directory of Open Access Journals (Sweden)

    Declercq David

    2008-01-01

    Full Text Available Abstract Orthogonal frequency division multiplexing (OFDM is the modulation technique used in most of the high-rate communication standards. However, OFDM signals exhibit high peak average to power ratio (PAPR that makes them particularly sensitive to nonlinear distortions caused by high-power amplifiers. Hence, the amplifier needs to operate at large output backoff, thereby decreasing the average efficiency of the transmitter. One way to reduce PAPR consists in clipping the amplitude of the OFDM signal introducing an additional noise that degrades the overall system performance. In that case, the receiver needs to set up an algorithm that compensates this clipping noise. In this paper, we propose three new iterative receivers with growing complexity and performance that operate at severe clipping: the first and simplest receiver uses a Viterbi algorithm as channel decoder whereas the other two implement a soft-input soft-output (SISO decoder. Each soft receiver is analyzed through EXIT charts for different mappings. Finally, the performances of the receivers are simulated on both short time-varying channel and AWGN channel.

  1. Turbo Decision Aided Receivers for Clipping Noise Mitigation in Coded OFDM

    Directory of Open Access Journals (Sweden)

    Maxime Colas

    2008-02-01

    Full Text Available Orthogonal frequency division multiplexing (OFDM is the modulation technique used in most of the high-rate communication standards. However, OFDM signals exhibit high peak average to power ratio (PAPR that makes them particularly sensitive to nonlinear distortions caused by high-power amplifiers. Hence, the amplifier needs to operate at large output backoff, thereby decreasing the average efficiency of the transmitter. One way to reduce PAPR consists in clipping the amplitude of the OFDM signal introducing an additional noise that degrades the overall system performance. In that case, the receiver needs to set up an algorithm that compensates this clipping noise. In this paper, we propose three new iterative receivers with growing complexity and performance that operate at severe clipping: the first and simplest receiver uses a Viterbi algorithm as channel decoder whereas the other two implement a soft-input soft-output (SISO decoder. Each soft receiver is analyzed through EXIT charts for different mappings. Finally, the performances of the receivers are simulated on both short time-varying channel and AWGN channel.

  2. Conformational and spectroscopic study of xanthogen ethyl formates, ROC(S)SC(O)OCH2CH3. Isolation of CH3CH2OC(O)SH

    Science.gov (United States)

    Juncal, Luciana C.; Cozzarín, Melina V.; Romano, Rosana M.

    2015-03-01

    ROC(S)SC(O)OCH2CH3, with R = CH3sbnd , (CH3)2CHsbnd and CH3(CH2)2sbnd , were obtained through the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. The liquid compounds were identified and characterized by 1H and 13C NMR and mass spectrometry. The conformations adopted by the molecules were studied by DFT methods. 6 conformers were theoretically predicted for R = CH3sbnd and (CH3)2CHsbnd , while the conformational flexibility of the n-propyl substituent increases the total number of feasible rotamers to 21. For the three molecules, the conformers can be associated in 3 groups, being the most stable the AS forms - the Cdbnd S double bond anti (A) with respect to the Csbnd S single bond and the Ssbnd C single bond syn (S) with respect to the Cdbnd O double bond - followed by AA and SS conformers. The vibrational spectra were interpreted in terms of the predicted conformational equilibrium, presenting the ν(Cdbnd O) spectral region signals corresponding to the three groups of conformers. A moderated pre-resonance Raman enhancement of the ν(Cdbnd S) vibrational mode of CH3(CH2)2OC(S)SC(O)OCH2CH3 was detected, when the excitation radiation approaches the energy of a n → π∗ electronic transition associated with the Cdbnd S chromophore. UV-visible spectra in different solvents were measured and interpreted in terms of TD-DFT calculations. The unknown molecule CH3CH2OC(O)SH was isolated by the UV-visible photolysis of CH3OC(S)SC(O)OCH2CH3 isolated in Ar matrix, and also obtained as a side-product of the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3.

  3. Differences in the associations of anthropometric measures with insulin resistance and type 2 diabetes mellitus between Korean and US populations: Comparisons of representative nationwide sample data.

    Science.gov (United States)

    Yoon, Yeong Sook; Choi, Han Seok; Kim, Jin Kuk; Kim, Yu Il; Oh, Sang Woo

    Variation among ethnic groups in the association between obesity and insulin resistance (IR)/diabetes has been suggested, but studies reported inconsistent results. We evaluated ethnic differences in the association between obesity and insulin resistance (IR)/diabetes. We conducted a cross-sectional analysis using Korea (n=18,845) and the USA (n=4657) National Health and Nutrition Examination Survey(NHANES) 2007-2010. We performed statistical comparisons of AUC-ROC (area under the curve in a receiver operating characteristic curve) values for body mass index (BMI), waist circumference (WC) and homeostasis model assessment of insulin resistance (HOMA-IR) to predict IR or diabetes among different ethnic groups. AUC-ROC values for BMI and WC for predicting IR were highest in Whites (0.8324 and 0.8468) and lowest in Koreans (0.7422 and 0.7367). Whites showed the highest AUC-ROC values for BMI (0.6869) and WC (0.7421) for predicting diabetes, while the AUC-ROC for HOMA-IR was highest in Koreans (0.8861). Linear regression showed significant interactions between ethnicity and the main effects (all Pdiabetes was highest in Whites, while the ability of HOMA-IR to predict diabetes was highest in Koreans. Copyright © 2015 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

  4. The Q* Index: A Useful Global Measure of Dementia Screening Test Accuracy

    Directory of Open Access Journals (Sweden)

    A.J. Larner

    2015-06-01

    Full Text Available Background/Aims: Single, global or unitary, indicators of test diagnostic performance have intuitive appeal for clinicians. The Q* index, the point in receiver operating characteristic (ROC curve space closest to the ideal top left-hand corner and where test sensitivity and specificity are equal, is one such measure. Methods: Datasets from four pragmatic accuracy studies which examined the Mini-Mental State Examination, Addenbrooke's Cognitive Examination-Revised, Montreal Cognitive Assessment, Test Your Memory test, and Mini-Addenbrooke's Cognitive Examination were examined to calculate and compare the Q* index, the maximal correct classification accuracy, and the maximal Youden index, as well as the sensitivity and specificity at these cutoffs. Results: Tests ranked similarly for the Q* index and the area under the ROC curve (AUC ROC. The Q* index cutoff was more sensitive (and less specific than the maximal correct classification accuracy cutoff, and less sensitive (and more specific than the maximal Youden index cutoff. Conclusion: The Q* index may be a useful global parameter summarising the test accuracy of cognitive screening instruments, facilitating comparison between tests, and defining a possible test cutoff value. As the point of equal sensitivity and specificity, its use may be more intuitive and appealing for clinicians than AUC ROC.

  5. Violencia laboral externa en el ámbito de urgencias generales del Hospital Universitario Virgen del Rocío de Sevilla

    Directory of Open Access Journals (Sweden)

    Tatiana Chagoyen Barroso

    Full Text Available Introducción: En los últimos años se ha incrementado la violencia laboral, y un sector de los más afectados es el sanitario. En la actualidad, está cobrando importancia la violencia laboral en el personal de urgencias. Las agresiones suelen ser por parte de los usuarios y, en ocasiones de sus familiares, a los profesionales de la Salud. Objetivos: Conocer si los trabajadores de Urgencias Generales del Hospital Universitario Virgen del Rocío (HUVR saben de la existencia de un plan de prevención y atención de agresiones para los profesionales del sistema público de Andalucía. Conocer agresiones no registradas hacia el personal de urgencias en HUVR. Material y métodos: Se trata de un estudio observacional, descriptivo con 221 trabajadores (68 varones y 153 mujeres, a los que se les entrega un cuestionario sobre la Violencia Laboral Externa (VLE percibida durante los 2 últimos años; se realiza un estudio descriptivo con análisis de frecuencias. Y posteriormente, se realizará test de Chi Cuadrado o prueba exacta de Fisher para ver si existe relación entre variables categóricas. Resultados: De 221 trabajadores que realizaron la encuesta, solo 26 conocen el plan de agresiones de HUVR. De 127 agresiones en los 2 últimos años, solo se registraron 13 (no existe significación estadística con sexo, edad o categoría profesional. Conclusiones: Existe infradeclaración de agresiones y un claro desconocimiento del plan de agresiones en el Hospital Universitario Virgen del Rocío.

  6. Film-screen vs. digital radiography in rheumatoid arthritis of the hand. An ROC analysis

    International Nuclear Information System (INIS)

    Jonsson, A.; Borg, A.; Hannesson, P.; Herrlin, K.; Jonsson, K.; Sloth, M.; Pettersson, H.

    1994-01-01

    In a prospective investigation the diagnostic accuracy of filmscreen and digital radiography in rheumatoid arthritis of hands was compared. Seventy hands of 36 patients with established rheumatoid arthritis were included in the study. Each of 11 joints in every hand was evaluated regarding the following radiologic parameters: soft tissue swelling, joint space narrowing, erosions and periarticular osteopenia. The digital images were obtained with storage phosphor image plates and evaluated in 2 forms; as digital hard-copy on film and on a monitor of an interactive workstation. The digital images had a resolution of either 3.33 or 5.0 lp/mm. ROC curves were constructed and comparing the area under the curves no significant difference was found between the 3 different imaging forms in either resolution group for soft tissue swelling, joint space narrowing and erosions. The film-screen image evaluation of periarticular osteopenia was significantly better than the digital hard-copy one in the 3.33 lp/mm resolution group, but no significant difference was found in the 5.0 lp/mm group. These results support the view that currently available digital systems are capable of adequate diagnostic performance. (orig.)

  7. Image compression of bone images

    International Nuclear Information System (INIS)

    Hayrapetian, A.; Kangarloo, H.; Chan, K.K.; Ho, B.; Huang, H.K.

    1989-01-01

    This paper reports a receiver operating characteristic (ROC) experiment conducted to compare the diagnostic performance of a compressed bone image with the original. The compression was done on custom hardware that implements an algorithm based on full-frame cosine transform. The compression ratio in this study is approximately 10:1, which was decided after a pilot experiment. The image set consisted of 45 hand images, including normal images and images containing osteomalacia and osteitis fibrosa. Each image was digitized with a laser film scanner to 2,048 x 2,048 x 8 bits. Six observers, all board-certified radiologists, participated in the experiment. For each ROC session, an independent ROC curve was constructed and the area under that curve calculated. The image set was randomized for each session, as was the order for viewing the original and reconstructed images. Analysis of variance was used to analyze the data and derive statistically significant results. The preliminary results indicate that the diagnostic quality of the reconstructed image is comparable to that of the original image

  8. Assessment of diagnostic value of various tumors markers (CEA, CA199, CA50) for colorectal neoplasm with logistic regression and ROC curve

    International Nuclear Information System (INIS)

    Gu Ping; Huang Gang; Han Yuan

    2007-01-01

    Objective: To assess the diagnostic value of CEA, CA199 and CA50 for colorectal neoplasm by logistic regression and ROC curve. Methods: Serum CEA (with CLIA), CA199 (with ECLIA) and CA50 (with IRMA) levels were measured in 75 patients with colorectal cancer, 35 patients with benign colorectal disorders and 49 controls. The area under the ROC curve (AUC)s of CEA, CA199, CA50 from logistic regression results were compared. Results: In the cancer-benign disorder group, the AUC of CA50 was larger than the AUC of CA199. AUC of combined CEA, CA50 was largest: not only larger than any AUC of CEA, CA50, CA199 alone but also larger than the AUC of the combined three markers (0.875 vs 0.604). In cancer-control group, the AUC of combination of CEA, CA199 and CA50 was larger than any AUC of CEA, CA199 or CA50 alone. Both in the cancer-benign disorder group or cancer-control group, the AUC of CEA was larger than the AUC of CA199 or CA50. Conclusion: CEA is of definite value in the diagnosis of colorectal cancer. For differential diagnosis, the combination of CEA and CA50 can give more information, while the combination of three tumor markers is less helpful. As an advanced statistical method, logistic regression can improve the diagnostic sensitivity and specificity. (authors)

  9. Overexpression of EMMPRIN is associated with lymph node metastasis and advanced stage of non-small cell lung cancer: a retrospective study

    OpenAIRE

    Liu, Bing; Wan, Zhaohui; Sheng, Baowei; Lin, Yong; Fu, Tian; Zeng, Qingdi; Qi, Congcong

    2017-01-01

    Background Previous studies show that overexpression of EMMPRIN involved in the malignant biological behavior of tumors. This investigation was to disclose the expression status of EMMPRIN in non-small cell lung cancer (NSCLC) and its clinical value for the diagnosis of NSCLC. Methods The expression of EMMPRIN was examined using immunohistochemistry and enzyme-linked immunosorbent assay. The clinical value of EMMPRIN was evaluated by drawing a receiver operating characteristic (ROC) curve. Re...

  10. Precision-Recall-Gain Curves:PR Analysis Done Right

    OpenAIRE

    Flach, Peter; Kull, Meelis

    2015-01-01

    Precision-Recall analysis abounds in applications of binary classification where true negatives do not add value and hence should not affect assessment of the classifier's performance. Perhaps inspired by the many advantages of receiver operating characteristic (ROC) curves and the area under such curves for accuracy-based performance assessment, many researchers have taken to report Precision-Recall (PR) curves and associated areas as performance metric. We demonstrate in this paper that thi...

  11. Screening Avoidant/Restrictive Food Intake Disorder (ARFID) in children: Outcomes from utilitarian versus specialist psychometrics

    OpenAIRE

    Dovey, T. M.; Aldridge, V. K.; Martin, C. I.; Wilken, M.; Meyer, C.

    2016-01-01

    This study assessed the specificity and sensitivity of two commonly used psychometric methods to assess ARFID in children. To achieve this, a sample of 329 mothers and one father completed the Behavioral Pediatrics Feeding Assessment Scale (BPFAS) and the Child Food Neophobia Scale (CFNS). A Receiver Operating Characteristic (ROC) analysis indicated that both measures were able to successfully differentiate a known clinical sample from those of typically developing population. Although the BP...

  12. Prehospital Heart Rate and Blood Pressure Increase the Positive Predictive Value of the Glasgow Coma Scale for High-Mortality Traumatic Brain Injury

    Science.gov (United States)

    2014-05-15

    States, J.D., and Mango , N.K. (1999). Abbreviated injury scale unification: the case for a unified injury system for global use . J. Trauma 47, 309...Andrew Reisner,1,2 Xiaoxiao Chen,1 Kamal Kumar,1 and Jaques Reifman1 Abstract We hypothesized that vital signs could be used to improve the...logistic regression models and, using DeLong’s test, compared their area under receiver operating characteristic curves (ROC AUCs) for three outcomes

  13. Mobile health technology transforms injury severity scoring in South Africa.

    Science.gov (United States)

    Spence, Richard Trafford; Zargaran, Eiman; Hameed, S Morad; Navsaria, Pradeep; Nicol, Andrew

    2016-08-01

    The burden of data collection associated with injury severity scoring has limited its application in areas of the world with the highest incidence of trauma. Since January 2014, electronic records (electronic Trauma Health Records [eTHRs]) replaced all handwritten records at the Groote Schuur Hospital Trauma Unit in South Africa. Data fields required for Glasgow Coma Scale, Revised Trauma Score, Kampala Trauma Score, Injury Severity Score (ISS), and Trauma Score-Injury Severity Score calculations are now prospectively collected. Fifteen months after implementation of eTHR, the injury severity scores were compared as predictors of mortality on three accounts: (1) ability to discriminate (area under receiver operating curve, ROC); (2) ability to calibrate (observed versus expected ratio, O/E); and (3) feasibility of data collection (rate of missing data). A total of 7460 admissions were recorded by eTHR from April 1, 2014 to July 7, 2015, including 770 severely injured patients (ISS > 15) and 950 operations. The mean age was 33.3 y (range 13-94), 77.6% were male, and the mechanism of injury was penetrating in 39.3% of cases. The cohort experienced a mortality rate of 2.5%. Patient reserve predictors required by the scores were 98.7% complete, physiological injury predictors were 95.1% complete, and anatomic injury predictors were 86.9% complete. The discrimination and calibration of Trauma Score-Injury Severity Score was superior for all admissions (ROC 0.9591 and O/E 1.01) and operatively managed patients (ROC 0.8427 and O/E 0.79). In the severely injured cohort, the discriminatory ability of Revised Trauma Score was superior (ROC 0.8315), but no score provided adequate calibration. Emerging mobile health technology enables reliable and sustainable injury severity scoring in a high-volume trauma center in South Africa. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. The Operations Process

    Science.gov (United States)

    2010-03-26

    important events receive the most attention. Ensures that absentees and flank units receive changes to the operation order. Transmits changes to them...York: Vintage Books, 1991. Fuller, J. F. C. Generalship: Its Diseases and Their Cure . Harrisburg, PA: Military Service Publishing Co., 1936

  15. Activity optimization method in nuclear medicine: a comparison with roc analysis

    International Nuclear Information System (INIS)

    Perez Diaz, M.; Diaz Rizo, O.; Lopez, A.; Estevez Aparicio, E.; Roque Diaz, R.

    2006-01-01

    Full text of publication follows: A discriminant method for optimizing the administered activity is validated by comparison with R.O.C. curves. The method is tested in 21 SPECT studies, performed with a Cardiac phantom. Three different cold lesions (L1, L2 and L3) are placed in the myocardium-wall by pairs for each SPECT. Three activities (84 MBq, 37 MBq or 18.5 MBq) of Tc 99 m diluted in water are used as background. The discriminant analysis is used to select the parameters that characterize image quality among the measured variables in the obtained tomographic images. They are a group of Lesion-to-Background (L/B) and Signal-to-Noise (S/N) ratios. Two clusters with different image quality (p=0.021) are obtained following the measured variables. The first one contains the studies performed with 37 MBq and 84 MBq and the second one the studies made with 18.5 MBq. Cluster classifications constitute the dependent variable in the discriminant function. The ratios B/L1, B/L2 and B/L3 are the parameters able to construct the function with 100 % of cases correctly classified into the clusters. The value of 37 MBq is the lowest tested activity that permits good results for the L/B variables, without significant differences respect to 84 MBq (p>0.05). The result is coincident with the applied R.O.C.-analysis, in which 37 MBq permits the highest area under the curve and low false-positive and false-negative rates with significant differences respect to 18.5 MBq (p=0.008)

  16. Bibliographic study of doses received by operators with non-protected organs

    International Nuclear Information System (INIS)

    Aubert, B.; Rehel, J.L.

    2009-01-01

    Based on a literature survey, the authors present and discuss the various levels of doses received by different organs during interventional radiology. These doses depend on the procedures (close or remote), on the part of the body, on the protocols, and on the apparatus. They raise the issue of the use of a single dosimeter (born under protection as it is already required in France) or two dosimeters (a second one on a non protected area as it is the case in some other countries)

  17. AVC: Selecting discriminative features on basis of AUC by maximizing variable complementarity.

    Science.gov (United States)

    Sun, Lei; Wang, Jun; Wei, Jinmao

    2017-03-14

    The Receiver Operator Characteristic (ROC) curve is well-known in evaluating classification performance in biomedical field. Owing to its superiority in dealing with imbalanced and cost-sensitive data, the ROC curve has been exploited as a popular metric to evaluate and find out disease-related genes (features). The existing ROC-based feature selection approaches are simple and effective in evaluating individual features. However, these approaches may fail to find real target feature subset due to their lack of effective means to reduce the redundancy between features, which is essential in machine learning. In this paper, we propose to assess feature complementarity by a trick of measuring the distances between the misclassified instances and their nearest misses on the dimensions of pairwise features. If a misclassified instance and its nearest miss on one feature dimension are far apart on another feature dimension, the two features are regarded as complementary to each other. Subsequently, we propose a novel filter feature selection approach on the basis of the ROC analysis. The new approach employs an efficient heuristic search strategy to select optimal features with highest complementarities. The experimental results on a broad range of microarray data sets validate that the classifiers built on the feature subset selected by our approach can get the minimal balanced error rate with a small amount of significant features. Compared with other ROC-based feature selection approaches, our new approach can select fewer features and effectively improve the classification performance.

  18. ATLAS computing operations within the GridKa Cloud

    International Nuclear Information System (INIS)

    Kennedy, J; Walker, R; Olszewski, A; Nderitu, S; Serfon, C; Duckeck, G

    2010-01-01

    The organisation and operations model of the ATLAS T1-T2 federation/Cloud associated to the GridKa T1 in Karlsruhe is described. Attention is paid to Cloud level services and the experience gained during the last years of operation. The ATLAS GridKa Cloud is large and divers spanning 5 countries, 2 ROC's and is currently comprised of 13 core sites. A well defined and tested operations model in such a Cloud is of the utmost importance. We have defined the core Cloud services required by the ATLAS experiment and ensured that they are performed in a managed and sustainable manner. Services such as Distributed Data Management involving data replication,deletion and consistency checks, Monte Carlo Production, software installation and data reprocessing are described in greater detail. In addition to providing these central services we have undertaken several Cloud level stress tests and developed monitoring tools to aid with Cloud diagnostics. Furthermore we have defined good channels of communication between ATLAS, the T1 and the T2's and have pro-active contributions from the T2 manpower. A brief introduction to the GridKa Cloud is provided followed by a more detailed discussion of the operations model and ATLAS services within the Cloud.

  19. Evaluation and Error Analysis for a Solar thermal Receiver

    Energy Technology Data Exchange (ETDEWEB)

    Pfander, M.

    2001-07-01

    In the following study a complete balance over the REFOS receiver module, mounted on the tower power plant CESA-1 at the Plataforma Solar de Almeria (PSA), is carried out. Additionally an error inspection of the various measurement techniques used in the REFOS project is made. Especially the flux measurement system Prohermes that is used to determine the total entry power of the receiver module and known as a major error source is analysed in detail. Simulations and experiments on the particular instruments are used to determine and quantify possible error sources. After discovering the origin of the errors they are reduced and included in the error calculation. the ultimate result is presented as an overall efficiency of the receiver module in dependence on the flux density at the receiver module's entry plane and the receiver operating temperature. (Author) 26 refs.

  20. Evaluation and Error Analysis for a Solar Thermal Receiver

    International Nuclear Information System (INIS)

    Pfander, M.

    2001-01-01

    In the following study a complete balance over the REFOS receiver module, mounted on the tower power plant CESA-1 at the Plataforma Solar de Almeria (PSA), is carried out. Additionally an error inspection of the various measurement techniques used in the REFOS project is made. Especially the flux measurement system Pro hermes that is used to determine the total entry power of the receiver module and known as a major error source is analysed in detail. Simulations and experiments on the particular instruments are used to determine and quantify possible error sources. After discovering the origin of the errors they are reduced and included in the error calculation. The ultimate result is presented as an overall efficiency of the receiver module in dependence on the flux density at the receiver modules entry plane and the receiver operating temperature. (Author) 26 refs

  1. Development and testing of Band 10 receivers for the ALMA project

    International Nuclear Information System (INIS)

    Uzawa, Y.; Fujii, Y.; Gonzalez, A.; Kaneko, K.; Kroug, M.; Kojima, T.; Kuroiwa, K.; Miyachi, A.; Saito, S.; Makise, K.; Wang, Z.; Asayama, S.

    2013-01-01

    Highlights: •The ALMA Band 10 (787–950 GHz) SIS receivers have been developed. •The complex conductivity of NbTiN was measured by a THz-TDS for the mixer design. •Tens of Band 10 receivers have been produced and their performance was quite well. •The best achieved receiver noise temperature was 125 K corresponding to 3hf/k B . •Band 10 receiver installed in the ALMA antenna captured astronomical signals. -- Abstract: The production model of a dual polarization heterodyne receiver for the Atacama Large Millimeter/submillimteter Array (ALMA) telescope has been developed to operate in the 787–950 GHz frequency band. The receiver uses two double sideband (DSB) waveguide mixers with Nb/AlOx/Nb tunnel junctions and NbTiN/SiO 2 /Al microstrip tuning circuits on quartz substrate. A terahertz time domain spectrometer was used to characterize our NbTiN film for the tuning circuit design, which revealed that the complex conductivity of the film is described by the Mattis-Bardeen theory including a finite scattering time of 15 fs and a superconducting gap with a gap ratio 2Δ/k B T C ∼ 4.0. Tens of these receivers (out of the total production number of 73) have been successfully produced, and their performance is well within the stringent ALMA requirements. The best achieved DSB receiver noise temperature is 125 K, corresponding to about 3hf/k B for 4 K operation. One of Band 10 receivers has successfully been installed in the ALMA antenna for a test observation

  2. Photonic integrated transmitter and receiver for NG-PON2

    Science.gov (United States)

    Tavares, Ana; Lopes, Ana; Rodrigues, Cláudio; Mãocheia, Paulo; Mendes, Tiago; Brandão, Simão.; Rodrigues, Francisco; Ferreira, Ricardo; Teixeira, António

    2014-08-01

    In this paper the authors present a monolithic Photonic Integrated Circuit which includes a transmitter and a receiver for NG-PON2. With this layout it is possible to build an OLT and, by redesigning some filters, also an ONU. This technology allows reducing the losses in the transmitter and in the receiver, increasing power budget, and also reducing the OEO conversions, which has been a major problem that operators want to surpass.

  3. Fuel Receiving and Storage Station. License application, amendment 7

    International Nuclear Information System (INIS)

    1976-02-01

    Amendment No. 7 to Allied-General Nuclear Services application for licensing of the Fuel Receiving and Storage Station consists of revised pages for: Amendment No. 7 to AG-L 105, ''Technical Description in Support of Application for FRSS Operation''; Amendment No. 1 to AG-L 105A, ''Early Operation of the Service Concentrator''; and Amendment No. 2 to AG-L 110, ''FRSS Summary Preoperational Report.''

  4. On the analysis of glycomics mass spectrometry data via the regularized area under the ROC curve

    Directory of Open Access Journals (Sweden)

    Lebrilla Carlito B

    2007-12-01

    Full Text Available Abstract Background Novel molecular and statistical methods are in rising demand for disease diagnosis and prognosis with the help of recent advanced biotechnology. High-resolution mass spectrometry (MS is one of those biotechnologies that are highly promising to improve health outcome. Previous literatures have identified some proteomics biomarkers that can distinguish healthy patients from cancer patients using MS data. In this paper, an MS study is demonstrated which uses glycomics to identify ovarian cancer. Glycomics is the study of glycans and glycoproteins. The glycans on the proteins may deviate between a cancer cell and a normal cell and may be visible in the blood. High-resolution MS has been applied to measure relative abundances of potential glycan biomarkers in human serum. Multiple potential glycan biomarkers are measured in MS spectra. With the objection of maximizing the empirical area under the ROC curve (AUC, an analysis method was considered which combines potential glycan biomarkers for the diagnosis of cancer. Results Maximizing the empirical AUC of glycomics MS data is a large-dimensional optimization problem. The technical difficulty is that the empirical AUC function is not continuous. Instead, it is in fact an empirical 0–1 loss function with a large number of linear predictors. An approach was investigated that regularizes the area under the ROC curve while replacing the 0–1 loss function with a smooth surrogate function. The constrained threshold gradient descent regularization algorithm was applied, where the regularization parameters were chosen by the cross-validation method, and the confidence intervals of the regression parameters were estimated by the bootstrap method. The method is called TGDR-AUC algorithm. The properties of the approach were studied through a numerical simulation study, which incorporates the positive values of mass spectrometry data with the correlations between measurements within person

  5. Concentrating Solar Power Central Receiver Panel Component Fabrication and Testing FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Michael W [Pratt & Whitney Rocketdyne; Miner, Kris [Pratt & Whitney Rocketdyne

    2013-03-30

    The objective of this project is to complete a design of an advanced concentrated solar panel and demonstrate the manufacturability of key components. Then confirm the operation of the key components under prototypic solar flux conditions. This work is an important step in reducing the levelized cost of energy (LCOE) from a central receiver solar power plant. The key technical risk to building larger power towers is building the larger receiver systems. Therefore, this proposed technology project includes the design of an advanced molten salt prototypic sub-scale receiver panel that can be utilized into a large receiver system. Then complete the fabrication and testing of key components of the receive design that will be used to validate the design. This project shall have a significant impact on solar thermal power plant design. Receiver panels of suitable size for utility scale plants are a key element to a solar power tower plant. Many subtle and complex manufacturing processes are involved in producing a reliable, robust receiver panel. Given the substantial size difference between receiver panels manufactured in the past and those needed for large plant designs, the manufacture and demonstration on prototype receiver panel components with representative features of a full-sized panel will be important to improving the build process for commercial success. Given the thermal flux limitations of the test facility, the panel components cannot be rendered full size. Significance changes occurred in the projects technical strategies from project initiation to the accomplishments described herein. The initial strategy was to define cost improvements for the receiver, design and build a scale prototype receiver and test, on sun, with a molten salt heat transport system. DOE had committed to constructing a molten salt heat transport loop to support receiver testing at the top of the NSTTF tower. Because of funding constraints this did not happen. A subsequent plan to

  6. Books Received

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Books Received. Articles in Resonance – Journal of Science Education. Volume 1 Issue 1 January 1996 pp 118-118 Books Received. Books Received · More Details Fulltext PDF. Volume 1 Issue 2 February 1996 pp 120-120 Books Received. Books Received.

  7. Design of a cavity heat pipe receiver experiment

    Science.gov (United States)

    Schneider, Michael G.; Brege, Mark H.; Greenlee, William J.

    1992-01-01

    A cavity heat pipe experiment has been designed to test the critical issues involved with incorporating thermal energy storage canisters into a heat pipe. The experiment is a replication of the operation of a heat receiver for a Brayton solar dynamic power cycle. The heat receiver is composed of a cylindrical receptor surface and an annular heat pipe with thermal energy storage canisters and gaseous working fluid heat exchanger tubes surrounding it. Hardware for the cavity heat pipe experiment will consist of a sector of the heat pipe, complete with gas tube and thermal energy storage canisters. Thermal cycling tests will be performed on the heat pipe sector to simulate the normal energy charge/discharge cycle of the receiver in a spacecraft application.

  8. Sensitivity and specificity of machine learning classifiers and spectral domain OCT for the diagnosis of glaucoma.

    Science.gov (United States)

    Vidotti, Vanessa G; Costa, Vital P; Silva, Fabrício R; Resende, Graziela M; Cremasco, Fernanda; Dias, Marcelo; Gomi, Edson S

    2012-06-15

    Purpose. To investigate the sensitivity and specificity of machine learning classifiers (MLC) and spectral domain optical coherence tomography (SD-OCT) for the diagnosis of glaucoma. Methods. Sixty-two patients with early to moderate glaucomatous visual field damage and 48 healthy individuals were included. All subjects underwent a complete ophthalmologic examination, achromatic standard automated perimetry, and RNFL imaging with SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec, Inc., Dublin, California, USA). Receiver operating characteristic (ROC) curves were obtained for all SD-OCT parameters. Subsequently, the following MLCs were tested: Classification Tree (CTREE), Random Forest (RAN), Bagging (BAG), AdaBoost M1 (ADA), Ensemble Selection (ENS), Multilayer Perceptron (MLP), Radial Basis Function (RBF), Naive-Bayes (NB), and Support Vector Machine (SVM). Areas under the ROC curves (aROCs) obtained for each parameter and each MLC were compared. Results. The mean age was 57.0±9.2 years for healthy individuals and 59.9±9.0 years for glaucoma patients (p=0.103). Mean deviation values were -4.1±2.4 dB for glaucoma patients and -1.5±1.6 dB for healthy individuals (pposition (0.765), and 6 o'clock position (0.754). The aROCs from classifiers varied from 0.785 (ADA) to 0.818 (BAG). The aROC obtained with BAG was not significantly different from the aROC obtained with the best single SD-OCT parameter (p=0.93). Conclusions. The SD-OCT showed good diagnostic accuracy in a group of patients with early glaucoma. In this series, MLCs did not improve the sensitivity and specificity of SD-OCT for the diagnosis of glaucoma.

  9. Climate-mediated shifts in Neandertal subsistence behaviors at Pech de l'Azé IV and Roc de Marsal (Dordogne Valley, France).

    Science.gov (United States)

    Hodgkins, Jamie; Marean, Curtis W; Turq, Alain; Sandgathe, Dennis; McPherron, Shannon J P; Dibble, Harold

    2016-07-01

    Neandertals disappeared from Europe just after 40,000 years ago. Some hypotheses ascribe this to numerous population crashes associated with glacial cycles in the late Pleistocene. The goal of this paper is to test the hypothesis that glacial periods stressed Neandertal populations. If cold climates stressed Neandertals, their subsistence behaviors may have changed-requiring intensified use of prey through more extensive nutrient extraction from faunal carcasses. To test this, an analysis of Neandertal butchering was conducted on medium sized bovid/cervid remains composed of predominately red deer (Cervus elaphus), reindeer (Rangifer tarandus), and roe deer (Capreolus caprelous) deposited during global warm and cold phases from two French sites: Pech de l'Azé IV (Pech IV, Bordes' excavation) and Roc de Marsal (RDM). Analysis of surface modification on high survival long bones and proximal and middle phalanges demonstrates that skeletal elements excavated from the cold levels (RDM Level 4, Pech IV Level I2) at each cave have more cut marks and percussion marks than elements from the warm levels (RDM Level 9, Pech IV Level Y-Z) after controlling for fragment size. At both sites, epiphyseal fragments are rare, and although this pattern can result from carnivore consumption, carnivore tooth marks are almost nonexistent (climate, but may have been a general Neandertal behavioral characteristic, suggesting that these hominids were regularly on the edge of sufficient nutrient availability even during interglacials. Overall, the faunal assemblages from Roc de Marsal and Pech IV provide some support for the hypothesis that Neandertals were processing faunal remains more heavily during glacial periods, suggesting a response to increased nutritional stress during colder time periods. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. ROC Analysis of Visual Assessments Made in Gated Blood Pool Scans of Patients with Coronary Artery Disease

    International Nuclear Information System (INIS)

    Lee, Kyung Han; Choi, Yoon Ho; Lee, Bum Woo; Moon, Dae Hyuk; Chung, June Key; Lee, Myung Chul; Koh, Chang Soon; Koong, Sung Soo

    1989-01-01

    Visual assessment of regional wall motion abnormality (RWMA) by gated blood pol scan (GBPS) serves as an useful parameter in thc diagnosis, functional evaluation, and follow up in various clinical settings, but are still subject to some inherent limitations. On important problem may be the interobserver as well as intraobsever variation that may well be present due to the subjective nature of the interpretations. This study was carried out to determine the reliability and reproducibility of visual assessments made in GBPSs, and to observe the degree to which the results would be influenced by observer variation. Fifty two patients with coronary heart disease had resting GBPS and contrast ventriculography within 4 days apart. Contrast ventriculography showed normal wall motion in 6 patients and the remaining 46 had RWMA in one or more segments. The anterior and left anterolateral views of all 52 GBPSs were analyzed by three independent observers, who selected from 5 scales, their level of confidence that there was RWMA in that segment. Receiver operating characteristic (ROC) curves for each analysis was plotted and the area under the curve (θ) was used as a parameter representing each observer's performance in his interpretations. The findings of contract ventriculographies were used as the standard for RWMA. The apical and inferoapical segments showed the best correlation with contrast ventriculography (θ=0.90-.094, 0.81-0.94, respectively), and the inferior wall showed the poorest correlation (θ=0.70-0.74). The interpretations of the inferior, septal, apical and posteroinferior, segments showed no difference between the observers, but there was significantly better performance in assessment by observer A compared to that by B or C for the anterolateral segments (θ=0.87, 0.78, 0.76, respectively, p<0.01 for A vs B, p<0,05 for A vs C), as well as when all segments were considered altogether (θ=0,88, 0.83, 0.82, respectively, both p<0 05). This was also true for

  11. Reliability of cone beam computed tomography as a biopsy-independent tool in differential diagnosis of periapical cysts and granulomas: An In vivo Study.

    Science.gov (United States)

    Chanani, Ankit; Adhikari, Haridas Das

    2017-01-01

    Differential diagnosis of periapical cysts and granulomas is required as their treatment modalities are different. The aim of this study was to evaluate the efficacy of cone beam computed tomography (CBCT) in the differential diagnosis of periapical cysts from granulomas. A single-centered observational study was carried out in the Department of Conservative Dentistry and Endodontics, Dr. R. Ahmed Dental College and Hospital, using CBCT and dental operating microscope. Forty-five lesions were analyzed using CBCT scans. One evaluator analyzed each CBCT scan for the presence of the following six characteristic radiological features: cyst like-location, shape, periphery, internal structure, effect on the surrounding structures, and cortical plate perforation. Another independent evaluator analyzed the CBCT scans. This process was repeated after 6 months, and inter- and intrarater reliability of CBCT diagnoses was evaluated. Periapical surgeries were performed and tissue samples were obtained for histopathological analysis. To evaluate the efficacy, CBCT diagnoses were compared with histopathological diagnoses, and six receiver operating characteristic (ROC) curve analyses were conducted. ROC curve, Cronbach's alpha (α) test, and Cohen Kappa (κ) test were used for statistical analysis. Both inter- and intrarater reliability were excellent (α = 0.94, κ = 0.75 and 0.77, respectively). ROC curve with regard to ≥4 positive findings revealed the highest area under curve (0.66). CBCT is moderately accurate in the differential diagnosis of periapical cysts and granulomas.

  12. The recent development of isotope and radiation application in Taiwan, ROC

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Gann; Tsai, Zei-Tsan; Huang, Henton [Institute of Nuclear Energy Research, Lung-Tan, TW (China)

    1996-10-01

    The Institute of Nuclear Energy Research (INER) plays a vital role in both isotope and radiation application in Taiwan, ROC. For research and development of reactor-produced radioisotopes, both Sr-90/Y-90 and W-188/Re-188 generators for therapeutic application were emphasized. For production of cyclotron-produced radioisotopes, I-123, Tl-201, Ga-67, In-111, Co-67 and F-18 were generated using a TR-30/15 cyclotron with H{sup -}/D{sup -} 30MeV/15MeV and maximum beam current of 400{mu}A/150{mu}A. For preparation of radiopharmaceuticals, a number of organic ligands have been synthesized such as d,1-hexamethylpropyleneamine oxime (HMPAO), N- (S-benzoylmercaptoacetyl) triglycine (S-Bz-MAG{sub 3}), 2-alkoxyisobutylisonitrile and metaiodobenzylguanidine (MIBG) and octreotide. R/D and production of radiopharmaceuticals have been carried out in cooperation with domestic hospitals. Some research work related to target radiotherapeutic and radiopharmaceuticals has also been carried out with cooperation of domestic hospitals. The C-13 urea breath test (C-13-UBT) has been extensively studied clinically to investigate the prevalence of Helicobacter pylori infection. The detection of this bacteria in the stomach ulcer becomes very important in both diagnosis and therapy monitoring. There are three large Co-60 irradiation plant in Taiwan. The radiosterilization of medical devices has been used in Taiwan for more than 14 years. Besides INER conducted R/D on (1) radiosterilization study of porcine serum, (2) insect sterilization, (3) treatment of condensate microphone with gamma ray, and (4) radiation polymerization for industry and medical applications. In conclusion, the prospects of isotope and radiation applications in Taiwan are very promising and encouraging. The R/D and development of the applications will contribute technical, economic and social benefits to the society. (J.P.N.)

  13. Development and testing of Band 10 receivers for the ALMA project

    Energy Technology Data Exchange (ETDEWEB)

    Uzawa, Y., E-mail: y.uzawa@nao.ac.jp [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Fujii, Y.; Gonzalez, A.; Kaneko, K.; Kroug, M.; Kojima, T.; Kuroiwa, K.; Miyachi, A. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Saito, S.; Makise, K.; Wang, Z. [National Institute of Information and Telecommunications Technology, 588-2 Iwaoka, Iwaoka-cho, Kobe, Hyogo 651-2492 (Japan); Asayama, S. [Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago (Chile)

    2013-11-15

    Highlights: •The ALMA Band 10 (787–950 GHz) SIS receivers have been developed. •The complex conductivity of NbTiN was measured by a THz-TDS for the mixer design. •Tens of Band 10 receivers have been produced and their performance was quite well. •The best achieved receiver noise temperature was 125 K corresponding to 3hf/k{sub B}. •Band 10 receiver installed in the ALMA antenna captured astronomical signals. -- Abstract: The production model of a dual polarization heterodyne receiver for the Atacama Large Millimeter/submillimteter Array (ALMA) telescope has been developed to operate in the 787–950 GHz frequency band. The receiver uses two double sideband (DSB) waveguide mixers with Nb/AlOx/Nb tunnel junctions and NbTiN/SiO{sub 2}/Al microstrip tuning circuits on quartz substrate. A terahertz time domain spectrometer was used to characterize our NbTiN film for the tuning circuit design, which revealed that the complex conductivity of the film is described by the Mattis-Bardeen theory including a finite scattering time of 15 fs and a superconducting gap with a gap ratio 2Δ/k{sub B}T{sub C} ∼ 4.0. Tens of these receivers (out of the total production number of 73) have been successfully produced, and their performance is well within the stringent ALMA requirements. The best achieved DSB receiver noise temperature is 125 K, corresponding to about 3hf/k{sub B} for 4 K operation. One of Band 10 receivers has successfully been installed in the ALMA antenna for a test observation.

  14. Accelerated aging tests on ENEA-ASE solar coating for receiver tube suitable to operate up to 550 °C

    Science.gov (United States)

    Antonaia, A.; D'Angelo, A.; Esposito, S.; Addonizio, M. L.; Castaldo, A.; Ferrara, M.; Guglielmo, A.; Maccari, A.

    2016-05-01

    A patented solar coating for evacuated receiver, based on innovative graded WN-AlN cermet layer, has been optically designed and optimized to operate at high temperature with high performance and high thermal stability. This solar coating, being designed to operate in solar field with molten salt as heat transfer fluid, has to be thermally stable up to the maximum temperature of 550 °C. With the aim of determining degradation behaviour and lifetime prediction of the solar coating, we chose to monitor the variation of the solar absorptance αs after each thermal annealing cycle carried out at accelerated temperatures under vacuum. This prediction method was coupled with a preliminary Differential Thermal Analysis (DTA) in order to give evidence for any chemical-physical coating modification in the temperature range of interest before performing accelerated aging tests. In the accelerated aging tests we assumed that the temperature dependence of the degradation processes could be described by Arrhenius behaviour and we hypothesized that a linear correlation occurs between optical parameter variation rate (specifically, Δαs/Δt) and degradation process rate. Starting from Δαs/Δt values evaluated at 650 and 690 °C, Arrhenius plot gave an activation energy of 325 kJ mol-1 for the degradation phenomenon, where the prediction on the coating degradation gave a solar absorptance decrease of only 1.65 % after 25 years at 550 °C. This very low αs decrease gave evidence for an excellent stability of our solar coating, also when employed at the maximum temperature (550 °C) of a solar field operating with molten salt as heat transfer fluid.

  15. Screening avoidant/ restrictive food intake disorder (ARFID) in children : outcomes in utilitarian versus specialist psychometrics

    OpenAIRE

    Dovey, T. M.; Aldridge, V. K; Martin, C. I.; Wilken, M.; Meyer, Caroline

    2016-01-01

    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. This study assessed the specificity and sensitivity of two commonly used psychometric methods to assess ARFID in children. To achieve this, a sample of 329 mothers and one father completed the Behavioral Pediatrics Feeding Assessment Scale (BPFAS) and the Child Food Neophobia Scale (CFNS). A Receiver Operating Characteristic (ROC) analysis indi...

  16. Parameters for screening music performance anxiety

    OpenAIRE

    Barbar, Ana E.; Crippa, José A.; Osório, Flávia L.

    2014-01-01

    Objective: To assess the discriminative capacity of the Kenny Music Performance Anxiety Inventory (K-MPAI), in its version adapted for Brazil, in a sample of 230 Brazilian adult musicians. Method: The Social Phobia Inventory (SPIN) was used to assess the presence of social anxiety indicators, adopting it as the gold standard. The Mann-Whitney U test and the receiver operating characteristic (ROC) curve were used for statistical analysis, with p ≤ 0.05 set as the significance level. ...

  17. PRAME overexpression predicted good outcome in pediatric B-cell acute lymphoblastic leukemia patients receiving chemotherapy.

    Science.gov (United States)

    Zhang, Yan-Huan; Lu, Ai-Dong; Yang, Lu; Li, Ling-Di; Chen, Wen-Min; Long, Ling-Yu; Zhang, Le-Ping; Qin, Ya-Zhen

    2017-01-01

    To investigate the prognostic value of PRAME expression in pediatric acute lymphoblastic leukemia(ALL), we measured PRAME transcript levels at diagnosis in 191 patients(146 B-ALL; 45T-ALL)receiving chemotherapy only. PRAME overexpression was defined as transcript levels higher than 0.30%, which is the upper limit of normal bone marrow and the optimal cutoff value derived from ROC curve analysis. PRAME overexpression was identified in 45.5% of patients. In B-ALL, PRAME overexpression was significantly associated with lower CIR(cumulative incidence of relapse), higher DFS (disease-freesurvival), and OS(overall survival) rates at 3 years, respectively (5.8% vs. 14.9%, P=0.014; 94.2% vs. 85.1%, P=0.014; 96.0% vs. 87.4%, P=0.039). PRAME overexpression had no impact on outcome in T-ALL patients. Among B-ALL patients with non-poor cytogenetic risk, those with PRAME overexpression showed significantly lower CIR, higher DFS and OS rates at 3 years, respectively (8.47% vs. 14.5%, P=0.009; 96.5% vs. 85.5%, P=0.009; 98.4% vs. 88.0%, P=0.023). Furthermore, PRAME overexpression was an independent good prognostic factor for relapse in all B-ALL patients and B-ALL patients with non-poor cytogenetic risk. Therefore, the prognostic significance of PRAME overexpression differed by ALL subtype; It predicted good outcome in pediatric B-ALL receiving chemotherapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. HANDBOOK FOR CONSTRUCTED WETLANDS RECEIVING ACID MINE DRAINAGE

    Science.gov (United States)

    In the summer of 1987, a pilot constructed wetland was built at the Big Five Tunnel in Idaho Springs, Colorado. This report details the theory, design and construction of wetlands receiving acid mine drainages, based on the second and third year of operation of this wetland, whic...

  19. Monitoring of operating processes

    International Nuclear Information System (INIS)

    Barry, R.F.

    1981-01-01

    Apparatus is described for monitoring the processes of a nuclear reactor to detect off-normal operation of any process and for testing the monitoring apparatus. The processes are evaluated by response to their paramters, such as temperature, pressure, etc. The apparatus includes a pair of monitoring paths or signal processing units. Each unit includes facilities for receiving on a time-sharing basis, a status binary word made up of digits each indicating the status of a process, whether normal or off-normal, and test-signal binary words simulating the status binary words. The status words and test words are processed in succession during successive cycles. During each cycle, the two units receive the same status word and the same test word. The test words simulate the status words both when they indicate normal operation and when they indicate off-normal operation. Each signal-processing unit includes a pair of memories. Each memory receives a status word or a test word, as the case may be, and converts the received word into a converted status word or a converted test word. The memories of each monitoring unit operate into a non-coincidence which signals non-coincidence of the converted word out of one memory of a signal-processing unit not identical to the converted word of the other memory of the same unit

  20. Quad channel software defined receiver for passive radar application

    Directory of Open Access Journals (Sweden)

    Pető Tamás

    2017-03-01

    Full Text Available In recent times the growing utilization of the electromagnetic environment brings the passive radar researches more and more to the fore. For the utilization of the wide range of illuminators of opportunity the application of wideband radio receivers is required. At the same time the multichannel receiver structure has also critical importance in target direction finding and interference suppression. This paper presents the development of a multichannel software defined receiver specifically for passive radar applications. One of the relevant feature of the developed receiver platform is its up-to-date SoC (System on hip based structure, which greatly enhance the integration and signal processing capacity of the system, all while keeping the costs low. The software defined operation of the discussed receiver system is demonstrated with using DVB-T (Digital Video Broadcast – Terrestrial signal as illuminator of opportunity. During this demonstration the multichannel capabilities of the realized system are also tested with real data using direction finding and beamforming algorithms.

  1. Development and optimization of SPECT gated blood pool cluster analysis for the prediction of CRT outcome

    Energy Technology Data Exchange (ETDEWEB)

    Lalonde, Michel, E-mail: mlalonde15@rogers.com; Wassenaar, Richard [Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Wells, R. Glenn; Birnie, David; Ruddy, Terrence D. [Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario K1Y 4W7 (Canada)

    2014-07-15

    Purpose: Phase analysis of single photon emission computed tomography (SPECT) radionuclide angiography (RNA) has been investigated for its potential to predict the outcome of cardiac resynchronization therapy (CRT). However, phase analysis may be limited in its potential at predicting CRT outcome as valuable information may be lost by assuming that time-activity curves (TAC) follow a simple sinusoidal shape. A new method, cluster analysis, is proposed which directly evaluates the TACs and may lead to a better understanding of dyssynchrony patterns and CRT outcome. Cluster analysis algorithms were developed and optimized to maximize their ability to predict CRT response. Methods: About 49 patients (N = 27 ischemic etiology) received a SPECT RNA scan as well as positron emission tomography (PET) perfusion and viability scans prior to undergoing CRT. A semiautomated algorithm sampled the left ventricle wall to produce 568 TACs from SPECT RNA data. The TACs were then subjected to two different cluster analysis techniques, K-means, and normal average, where several input metrics were also varied to determine the optimal settings for the prediction of CRT outcome. Each TAC was assigned to a cluster group based on the comparison criteria and global and segmental cluster size and scores were used as measures of dyssynchrony and used to predict response to CRT. A repeated random twofold cross-validation technique was used to train and validate the cluster algorithm. Receiver operating characteristic (ROC) analysis was used to calculate the area under the curve (AUC) and compare results to those obtained for SPECT RNA phase analysis and PET scar size analysis methods. Results: Using the normal average cluster analysis approach, the septal wall produced statistically significant results for predicting CRT results in the ischemic population (ROC AUC = 0.73;p < 0.05 vs. equal chance ROC AUC = 0.50) with an optimal operating point of 71% sensitivity and 60% specificity. Cluster

  2. Development and optimization of SPECT gated blood pool cluster analysis for the prediction of CRT outcome

    International Nuclear Information System (INIS)

    Lalonde, Michel; Wassenaar, Richard; Wells, R. Glenn; Birnie, David; Ruddy, Terrence D.

    2014-01-01

    Purpose: Phase analysis of single photon emission computed tomography (SPECT) radionuclide angiography (RNA) has been investigated for its potential to predict the outcome of cardiac resynchronization therapy (CRT). However, phase analysis may be limited in its potential at predicting CRT outcome as valuable information may be lost by assuming that time-activity curves (TAC) follow a simple sinusoidal shape. A new method, cluster analysis, is proposed which directly evaluates the TACs and may lead to a better understanding of dyssynchrony patterns and CRT outcome. Cluster analysis algorithms were developed and optimized to maximize their ability to predict CRT response. Methods: About 49 patients (N = 27 ischemic etiology) received a SPECT RNA scan as well as positron emission tomography (PET) perfusion and viability scans prior to undergoing CRT. A semiautomated algorithm sampled the left ventricle wall to produce 568 TACs from SPECT RNA data. The TACs were then subjected to two different cluster analysis techniques, K-means, and normal average, where several input metrics were also varied to determine the optimal settings for the prediction of CRT outcome. Each TAC was assigned to a cluster group based on the comparison criteria and global and segmental cluster size and scores were used as measures of dyssynchrony and used to predict response to CRT. A repeated random twofold cross-validation technique was used to train and validate the cluster algorithm. Receiver operating characteristic (ROC) analysis was used to calculate the area under the curve (AUC) and compare results to those obtained for SPECT RNA phase analysis and PET scar size analysis methods. Results: Using the normal average cluster analysis approach, the septal wall produced statistically significant results for predicting CRT results in the ischemic population (ROC AUC = 0.73;p < 0.05 vs. equal chance ROC AUC = 0.50) with an optimal operating point of 71% sensitivity and 60% specificity. Cluster

  3. Detector evaluation for improved situational awareness: Receiver operator characteristic curve based

    NARCIS (Netherlands)

    Wuijckhuijse, A.L. van; Nieuwenhuizen, M.S.

    2016-01-01

    In military and civilian operations good situational awareness is a prerequisite to make proper decisions. The situational awareness is among others based upon intelligence, threat analysis and detection, altogether element of the so-called DIM (detection, identification, monitoring) system. In case

  4. [Programme review of somatropin deficit in pediatrics at the Hospital Universitario Virgen del Rocío].

    Science.gov (United States)

    Lavaredas, A; de la Puerta, R; Álvarez del Vayo, C

    2013-01-01

    To develop a program review of somatropin deficit, applied in pediatrics at the Hospital Universitario Virgen del Rocío, using two groups of patients: the ones diagnosed with deficiency of this hormone, and those born small for gestational age, with the intention of evaluating its effectiveness in the first year of treatment. Attaining a retrospective study of the cohort of patients treated with growth hormone under the above diagnoses, with cross-sectional and observational methodology, to which we applied a statistical analysis with the Statistical Package for Social Sciences®. After the beginning of the treatment, the growth rate had increased and the bone age approximated to the chronologic age. In the two treated groups in the first year of treatment were the female patients aged between 0 to 12 years with a deficit of growth hormone who responded better to therapy. We observed that the treatment instituted appeared highly effective in both groups of patients, allowing a favorable increase in height. Copyright © 2013 SEFH. Published by AULA MEDICA. All rights reserved.

  5. Enhanced heat transfer performances of molten salt receiver with spirally grooved pipe

    International Nuclear Information System (INIS)

    Lu, Jianfeng; Ding, Jing; Yu, Tao; Shen, Xiangyang

    2015-01-01

    The enhanced heat transfer performances of solar receiver with spirally grooved pipe were theoretically investigated. The physical model of heat absorption process was proposed using the general heat transfer correlation of molten salt in smooth and spirally grooved pipe. According to the calculation results, the convective heat transfer inside the receiver can remarkably enhance the heat absorption process, and the absorption efficiency increased with the flow velocity and groove height, while the wall temperature dropped. As the groove height increased, the heat losses of convection and radiation dropped with the decrease of wall temperature, and the average absorption efficiency of the heat receiver can be increased. Compared with the heat receiver with smooth pipe, the heat absorption efficiency of heat receiver with spirally grooved pipe e/d = 0.0475 can rise for 0.7%, and the maximum bulk fluid temperature can be increased for 31.1 °C. As a conclusion, spirally grooved pipe can be a very effective way for heat absorption enhancement of solar receiver, and it can also increase the operating temperature of molten salt. - Highlights: • Spirally grooved tube is a very effective way for solar receiver enhancement. • Heat absorption model of receiver is proposed with general heat transfer correlation. • Spirally groove tube increases absorption efficiency and reduces wall temperature. • Operating temperature of molten salt remarkably increases with groove height. • Heat absorption performance is promoted for first and second thermodynamics laws

  6. Diagnostic capability of 100-mm roll film digitizer system

    International Nuclear Information System (INIS)

    Kono, M.; Yamasaki, K.; Ikeda, M.

    1988-01-01

    The authors recently developed a roll film digitizer system. The sampling pitch is 100 μm. a scientific image study (Barger phantom, Hawlet chart, and modulation transfer function), receiver operating characteristic (ROC) study, and clinical evaluation were performed. For the ROC study, a chest phantom with simulated nodule and hairline was used. Differences in accuracy between readings of cathode ray tube (CRT) images and roll film images were not statistically significant for hairline and coin lesions, P<.05). As a clinical evaluation, eight radiologists evaluated predetermined radiologic findings on a five-point rating scale compared with original roll film images. Scores for CRT images were equal to those for the original roll film images. In conclusion, CRT images (1,000 x 1,000) were found to be sufficient for diagnostic accuracy of chest images compared with roll film images (100 x 100 mm)

  7. A novel teaching tool using dynamic cues improves visualisation of chest lesions by naive observers

    Science.gov (United States)

    Mohamed Ali, M. A.; Toomey, R. J.; Ryan, J. T.; Cuffe, F. C.; Brennan, P. C.

    2009-02-01

    Introduction Dynamic cueing is an effective way of stimulating perception of regions of interest within radiological images. This study explores the impact of a novel teaching tool using dynamic cueing for lesion detection on plain chest radiographs. Materials and methods Observer performance studies were carried out where 36 novices examined 30 chest images in random order. Half of these contained between one and three simulated pulmonary nodules. Three groups were investigated: A (control: no teaching tool), B (retested immediately after undergoing the teaching tool) and C (retested a week after undergoing the teaching tool). The teaching tool involved dynamically displaying the same images with and without lesions. Results were compared using Receiver Operating Characteristics (ROC), sensitivity and specificity analyses. Results The second reading showed significantly greater area under the ROC curve (Az value) (pchest radiographs in the short term.

  8. Establishing the cut-off score for remission and severity-ranges on the Psychotic Depression Assessment Scale (PDAS)

    DEFF Research Database (Denmark)

    Østergaard, Søren D; Rothschild, Anthony J; Flint, Alastair J

    2016-01-01

    BACKGROUND: The Psychotic Depression Assessment Scale (PDAS) is a rating scale dedicated to the measurement of severity in psychotic depression (PD). The aim of this study was to establish the PDAS cut-off for remission of PD as well as PDAS score-ranges for mild, moderate, and severe PD...... on the PDAS and the severity-ranges for mild, moderate, and severe PD were defined using the Clinical Global Impression - Severity scale (CGI-S) as reference by means of pair-wise receiver operating characteristic (ROC) analyses. Subsequently, it was tested whether remission on the PDAS could separate...... the effects of Olanzapine+Sertraline vs. Olanzapine+Placebo through an intention-to-treat, mixed-effects logistic regression of the data from STOP-PD. RESULTS: According to the ROC analyses, the ideal cut-off for remission of PD was a PDAS total score moderate...

  9. Use of prior mammograms in the classification of benign and malignant masses

    International Nuclear Information System (INIS)

    Varela, Celia; Karssemeijer, Nico; Hendriks, Jan H.C.L.; Holland, Roland

    2005-01-01

    The purpose of this study was to determine the importance of using prior mammograms for classification of benign and malignant masses. Five radiologists and one resident classified mass lesions in 198 mammograms obtained from a population-based screening program. Cases were interpreted twice, once without and once with comparison of previous mammograms, in a sequential reading order using soft copy image display. The radiologists' performances in classifying benign and malignant masses without and with previous mammograms were evaluated with receiver operating characteristic (ROC) analysis. The statistical significance of the difference in performances was calculated using analysis of variance. The use of prior mammograms improved the classification performance of all participants in the study. The mean area under the ROC curve of the readers increased from 0.763 to 0.796. This difference in performance was statistically significant (P = 0.008)

  10. Methodology of diagnostic tests in hepatology

    DEFF Research Database (Denmark)

    Christensen, Erik

    2009-01-01

    The performance of diagnostic tests can be assessed by a number of methods. These include sensitivity, specificity,positive and negative predictive values, likelihood ratios and receiver operating characteristic (ROC) curves. This paper describes the methods and explains which information...... they provide. Sensitivity and specificity provides measures of the diagnostic accuracy of a test in diagnosing the condition. The positive and negative predictive values estimate the probability of the condition from the test-outcome and the condition's prevalence. The likelihood ratios bring together......' and plotting sensitivity as a function of 1-specificity. The ROC-curve can be used to define optimal cut-off values for a test, to assess the diagnostic accuracy of the test, and to compare the usefulness of different tests in the same patients. Under certain conditions it may be possible to utilize a test...

  11. Diagnoses accuracy in the detection of abnormalities in the thorax x-ray: Teleradiology vs. conventional radiology

    International Nuclear Information System (INIS)

    Moron, Fanny Emilia; Melendez, Patricia; Martinez, Carlos Eli

    1998-01-01

    Background: introduction of teleradiology in Colombia is very recent and its operative characteristics and reliability are unknown. Objective: to evaluate intra and interobserver concordance in the interpretation of digitized chest x-ray films and to compare diagnostic Accuracy of teleradiology and film screen interpretation. Design: cross-sectional study for evaluation or concordance and operative characteristics of a diagnostic test. Patients and methods: convenience sample of 40 chest films. Independent lecture of digitized images for each radiologist to evaluate interobserver concordance: second lecture of digitized images for evaluation of intraobserver concordance. Generation of a gold standard diagnosis with a consensus interpretation of film screens, comparison of operative characteristics of teleradiology and conventional interpretation, using as a reference the gold standard (consensus lectures) and comparison of diagnostic precision using receiver operating characteristics curves (ROC curves). Results: agreements and concordance were significant higher than expected in both evaluations (inter and intraobserver). Sensitivity of teleradiology was similar to sensitivity of film screen interpretation and areas under ROC curves were not statistically different. Conclusions: concordance in the interpretation of chest radiological studies are significant in a teleradiology system and diagnostic utility of teleradiology is the same as conventional film screen interpretation. Accuracy and reliability of teleradiology are optimal

  12. A neural network approach to breast cancer diagnosis as a constraint satisfaction problem

    International Nuclear Information System (INIS)

    Tourassi, Georgia D.; Markey, Mia K.; Lo, Joseph Y.; Floyd, Carey E. Jr.

    2001-01-01

    A constraint satisfaction neural network (CSNN) approach is proposed for breast cancer diagnosis using mammographic and patient history findings. Initially, the diagnostic decision to biopsy was formulated as a constraint satisfaction problem. Then, an associative memory type neural network was applied to solve the problem. The proposed network has a flexible, nonhierarchical architecture that allows it to operate not only as a predictive tool but also as an analysis tool for knowledge discovery of association rules. The CSNN was developed and evaluated using a database of 500 nonpalpable breast lesions with definitive histopathological diagnosis. The CSNN diagnostic performance was evaluated using receiver operating characteristic analysis (ROC). The results of the study showed that the CSNN ROC area index was 0.84±0.02. The CSNN predictive performance is competitive with that achieved by experienced radiologists and backpropagation artificial neural networks (BP-ANNs) presented before. Furthermore, the study illustrates how CSNN can be used as a knowledge discovery tool overcoming some of the well-known limitations of BP-ANNs

  13. Large-scale use of solar energy with central receivers

    Science.gov (United States)

    Kreith, F.; Meyer, R. T.

    1983-12-01

    The working principles of solar central receiver power plants are outlined and applications are discussed. Heliostat arrays direct sunlight into a receiver cavity mounted on a tower, heating the working fluid in the tower to temperatures exceeding 500 C. The formulation for the image plane and the geometric concentration ratio for a heliostat field are provided, noting that commercial electric power plants will require concentration ratios of 200-1000. Automated controls consider imperfections in the mirrors, tracking errors, and seasonal insolation intensity and angular variations. Membranes may be used instead of rigid heliostat mirrors to reduce costs, while trade-offs exist between the efficiencies of cavity and exterior receivers on the tower. Sensible heat storage has proved most effective for cloudy or nighttime operations. Details of the DOE Solar One 10 MW plant, which began operation in 1982, are provided, with mention given to the 33.6 continuous hours of power generation that have been achieved. Projected costs of commercial installations are $700/kWt, and possible applications include recovering and refining oil, processing natural gas, uranium ore, and sugar cane, drying gypsum board, and manufacturing ammonia.

  14. Diagnostic accuracy of routine blood examinations and CSF lactate level for post-neurosurgical bacterial meningitis.

    Science.gov (United States)

    Zhang, Yang; Xiao, Xiong; Zhang, Junting; Gao, Zhixian; Ji, Nan; Zhang, Liwei

    2017-06-01

    To evaluate the diagnostic accuracy of routine blood examinations and Cerebrospinal Fluid (CSF) lactate level for Post-neurosurgical Bacterial Meningitis (PBM) at a large sample-size of post-neurosurgical patients. The diagnostic accuracies of routine blood examinations and CSF lactate level to distinguish between PAM and PBM were evaluated with the values of the Area Under the Curve of the Receiver Operating Characteristic (AUC -ROC ) by retrospectively analyzing the datasets of post-neurosurgical patients in the clinical information databases. The diagnostic accuracy of routine blood examinations was relatively low (AUC -ROC CSF lactate level achieved rather high diagnostic accuracy (AUC -ROC =0.891; CI 95%, 0.852-0.922). The variables of patient age, operation duration, surgical diagnosis and postoperative days (the interval days between the neurosurgery and examinations) were shown to affect the diagnostic accuracy of these examinations. The variables were integrated with routine blood examinations and CSF lactate level by Fisher discriminant analysis to improve their diagnostic accuracy. As a result, the diagnostic accuracy of blood examinations and CSF lactate level was significantly improved with an AUC -ROC value=0.760 (CI 95%, 0.737-0.782) and 0.921 (CI 95%, 0.887-0.948) respectively. The PBM diagnostic accuracy of routine blood examinations was relatively low, whereas the accuracy of CSF lactate level was high. Some variables that are involved in the incidence of PBM can also affect the diagnostic accuracy for PBM. Taking into account the effects of these variables significantly improves the diagnostic accuracies of routine blood examinations and CSF lactate level. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Electrodynamic Wireless Power Transmission to Rotating Magnet Receivers

    International Nuclear Information System (INIS)

    Garraud, A; Jimenez, J D; Garraud, N; Arnold, D P

    2014-01-01

    This paper presents an approach for electrodynamic wireless power transmission (EWPT) using a synchronously rotating magnet located in a 3.2 cm 3 receiver. We demonstrate wireless power transmission up to 99 mW (power density equal to 31 mW/cm 3 ) over a 5-cm distance and 5 mW over a 20-cm distance. The maximum operational frequency, and hence maximal output power, is constrained by the magnetic field amplitude. A quadratic relationship is found between the maximal output power and the magnetic field. We also demonstrate simultaneous, power transmission to multiple receivers positioned at different locations

  16. Distributed Arithmetic for Efficient Base-Band Processing in Real-Time GNSS Software Receivers

    Directory of Open Access Journals (Sweden)

    Grégoire Waelchli

    2010-01-01

    Full Text Available The growing market of GNSS capable mobile devices is driving the interest of GNSS software solutions, as they can share many system resources (processor, memory, reducing both the size and the cost of their integration. Indeed, with the increasing performance of modern processors, it becomes now feasible to implement in software a multichannel GNSS receiver operating in real time. However, a major issue with this approach is the large computing resources required for the base-band processing, in particular for the correlation operations. Therefore, new algorithms need to be developed in order to reduce the overall complexity of the receiver architecture. Towards that aim, this paper first introduces the challenges of the software implementation of a GPS receiver, with a main focus given to the base-band processing and correlation operations. It then describes the already existing solutions and, from this, introduces a new algorithm based on distributed arithmetic.

  17. FACSIM/MRS-1: Cask receiving and consolidation model documentation and user's guide

    International Nuclear Information System (INIS)

    Lotz, T.L.; Shay, M.R.

    1987-06-01

    The Pacific Northwest Laboratory (PNL) has developed a stochastic computer model, FACSIM/MRS, to assist in assessing the operational performance of the Monitored Retrievable Storage (MRS) waste-handling facility. This report provides the documentation and user's guide for the component FACSIM/MRS-1, which is also referred to as the front-end model. The FACSIM/MRS-1 model simulates the MRS cask-receiving and spent-fuel consolidation activities. The results of the assessment of the operational performance of these activities are contained in a second report, FACSIM/MRS-1: Cask Receiving and Consolidation Performance Assessment (Lotz and Shay 1987). The model of MRS canister storage and shipping operations is presented in FACSIM/MRS-2: Storage and Shipping Model Documentation and User's Guide (Huber et al. 1987). The FACSIM/MRS model uses the commercially available FORTRAN-based SIMAN (SIMulation ANalysis language) simulation package (Pegden 1982). SIMAN provides a set of FORTRAN-coded commands, called block operations, which are used to build detailed models of continuous or discrete events that make up the operations of any process, such as the operation of an MRS facility. The FACSIM models were designed to run on either an IBM-PC or a VAX minicomputer. The FACSIM/MRS-1 model is flexible enough to collect statistics concerning almost any aspect of the cask receiving and consolidation operations of an MRS facility. The MRS model presently collects statistics on 51 quantities of interest during the simulation. SIMAN reports the statistics with two forms of output: a SIMAN simulation summary and an optional set of SIMAN output files containing data for use by more detailed post processors and report generators

  18. Quality study of portal images acquired by computed radiography and screen-film system under megavoltage ray

    International Nuclear Information System (INIS)

    Cao Guoquan; Jin Xiance; Wu Shixiu; Xie Congying; Zhang Li; Yu Jianyi; Li Yueqing

    2007-01-01

    Objective: To evaluate the quality of the portal images acquired by computed radiography (CR) system and conventional screen-film system, respectively. Methods: Imaging plates (IP) and X-ray films ora home-devised lead phantom with a leakage of 6.45% were acquired, and modulation transfer function (MTF) curves of the both images were measured using edge method. Portal images of 40 nasopharyngeal cancer patients were acquired by IP and screen-film system respectively. Two doctors with similar experience evaluated the damage degree of petrosal bone, the receiver operating characteristic (ROC) curve of CR images and general images were drawn according to two doctors evaluation results. Results: The identification frequency of CR system and screen-film system were 1.159 and 0.806 Lp/mm respectively. For doctor one, the area under ROC curve of CR images and general images were 0.802 and 0.742 respectively. For doctor two, the area under ROC curve of CR images and general images were 0.751 and 0.600 respectively. The MTF curve and ROC curve of CR are both better than those of screen-film system. Conclusion: The image quality of CR portal imaging is much better than that of screen-film system. The utility of CR in linear accelerator for portal imaging is promising in clinic. (authors)

  19. Diagnostic accuracy of presepsin (sCD14-ST) as a biomarker of infection and sepsis in the emergency department.

    Science.gov (United States)

    de Guadiana Romualdo, Luis García; Torrella, Patricia Esteban; Acebes, Sergio Rebollo; Otón, María Dolores Albaladejo; Sánchez, Roberto Jiménez; Holgado, Ana Hernando; Santos, Enrique Jiménez; Freire, Alejandro Ortín

    2017-01-01

    Presepsin is a promising biomarker for the diagnosis and prognosis of sepsis. However, results reported about its value to diagnose sepsis in an emergency department (ED) are controversial, probably due to differences in the design of the studies. We have evaluated the diagnostic accuracy of presepsin for infection and sepsis, compared with procalcitonin (PCT) and C-reactive protein (CRP), in patients presenting to the emergency department (ED) with suspected infection. 223 patients with suspected infection were enrolled for the study. Blood samples were collected on admission for measurement of biomarkers. Definitive diagnosis was obtained afterwards by analysis of digital medical records. Receiver operating characteristic (ROC) curve analysis was conducted to determine the diagnostic accuracy. Infection was confirmed in 200 patients, including 130 with non-complicated infection and 70 with sepsis. Median CRP, PCT and presepsin levels were significantly higher in patients with infection and sepsis. PCT was the biomarker with the highest performance for infection (ROC AUC: 0.910); for sepsis, PCT (ROC AUC: 0.815) and presepsin (ROC AUC: 0.775) shown a similar performance. Although presepsin is a valuable biomarker for diagnosis of infection and sepsis, its diagnostic accuracy in our study does not improve that of PCT. Its introduction in clinical practice is not justified. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. PERBEDAAN TAKSIRAN BERAT BADAN JANIN MENURUT PERHITUNGAN FORMULA BERAT BADAN LAHIR BAYI

    Directory of Open Access Journals (Sweden)

    Ricvan Dana Nindrea

    2017-03-01

    Full Text Available Prediksi dari berat badan lahir adalah faktor yang penting dalam perawatan ibu hamil termasuk rencana perawatan, pencegahan komplikasi dan perawatan yang tepat, namun saat ini tidak banyak bidan yang mengetahui mengenai perhitungan taksiran berat badan lahir bayi tersebut. Penelitian ini bertujuan mengetahui perbedaan rerata taksiran berat badan janin antara formula Dare dan Risanto. Penelitian ini merupakan penelitian diagnostik dengan pendekatan yang digunakan adalah cross sectional study di kamar bersalin Rumah Sakit Satelit Bagian Obstetri dan Ginekologi Fakultas Kedokteran Universitas Andalas sejak bulan Maret-September 2016. Didapatkan sampel penelitian sebanyak 100 orang yang memenuhi kriteria inklusi dan eksklusi. Perhitungan dilakukan dengan melakukan pengukuran taksiran berat badan janin dengan formula Dare dan Risanto serta berat badan lahir bayi. Analisis data dilakukan secara univariat dan bivariat dengan menggunakan uji T dependent serta analisis Receiver Operating Curve (ROC. Diperoleh hasil tidak ada perbedaan rerata taksiran berat badan janin formula Dare dengan berat badan lahir bayi (p value > 0,05 dan ada perbedaan rerata taksiran berat badan janin formula Risanto dengan berat badan lahir bayi (p value < 0,05. Hasil analisis Receiver Operating Curve (ROC didapatkan bahwa Formula Dare lebih akurat untuk memprediksi taksiran berat badan janin dengan luas area dibawah kurva adalah 76,4%, sedangkan Formula Risanto 66,8%. Formula Dare lebih akurat dalam menentukan taksiran berat badan janin dibandingkan Formula Risanto.

  1. A low noise 665 GHz SIS quasi-particle waveguide receiver

    Science.gov (United States)

    Kooi, J. W.; Walker, C. K.; Leduc, H. G.; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

    1993-01-01

    Recent results on a 565-690 GHz SIS heterodyne receiver employing a 0.36 micron(sup 2) Nb/AlOx/Nb SIS tunnel junction with high quality circular non-contacting back short and E-plane tuners in a full height wave guide mount are reported. No resonant tuning structures were incorporated in the junction design at this time, even though such structures are expected to help the performance of the receiver. The receiver operates to at least the gap frequency of Niobium, approximately 680 GHz. Typical receiver noise temperatures from 565-690 GHz range from 160K to 230K with a best value of 185K DSB at 648 GHz. With the mixer cooled from 4.3K to 2K the measured receiver noise temperatures decreased by approximately 15 percent, giving roughly 180K DSB from 660 to 680 GHz. The receiver has a full 1 GHz IF pass band and was successfully installed at the Caltech Submillimeter Observatory in Hawaii.

  2. Predictive Value of Whole Blood and Plasma Coagulation Tests for Intra- and Postoperative Bleeding Risk: A Systematic Review

    DEFF Research Database (Denmark)

    Larsen, Julie Brogaard; Hvas, Anne-Mette

    2017-01-01

    review of the existing literature assessing the ability of whole blood coagulation (thromboelastography [TEG]/thromboelastometry [ROTEM]/Sonoclot), platelet function tests, and standard plasma-based coagulation tests to predict bleeding in the perioperative setting. We searched PubMed and Embase...... value of testing in patients receiving antithrombotic medication. In general, studies reported low positive predictive values for perioperative testing, whereas negative predictive values were high. The studies yielded moderate areas under receiver operator characteristics (ROC) curve (for the majority...... recommend that both whole blood and plasma-based coagulation tests are primarily used in case of bleeding and not for screening in unselected patients prior to surgery....

  3. 25-Gbit/s burst-mode optical receiver using high-speed avalanche photodiode for 100-Gbit/s optical packet switching.

    Science.gov (United States)

    Nada, Masahiro; Nakamura, Makoto; Matsuzaki, Hideaki

    2014-01-13

    25-Gbit/s error-free operation of an optical receiver is successfully demonstrated against burst-mode optical input signals without preambles. The receiver, with a high-sensitivity avalanche photodiode and burst-mode transimpedance amplifier, exhibits sufficient receiver sensitivity and an extremely quick response suitable for burst-mode operation in 100-Gbit/s optical packet switching.

  4. Ground test program for a full-size solar dynamic heat receiver

    Science.gov (United States)

    Sedgwick, L. M.; Kaufmann, K. J.; Mclallin, K. L.; Kerslake, T. W.

    1991-01-01

    Test hardware, facilities, and procedures were developed to conduct ground testing of a full-size, solar dynamic heat receiver in a partially simulated, low earth orbit environment. The heat receiver was designed to supply 102 kW of thermal energy to a helium and xenon gas mixture continuously over a 94 minute orbit, including up to 36 minutes of eclipse. The purpose of the test program was to quantify the receiver thermodynamic performance, its operating temperatures, and thermal response to changes in environmental and power module interface boundary conditions. The heat receiver was tested in a vacuum chamber using liquid nitrogen cold shrouds and an aperture cold plate. Special test equipment was designed to provide the required ranges in interface boundary conditions that typify those expected or required for operation as part of the solar dynamic power module on the Space Station Freedom. The support hardware includes an infrared quartz lamp heater with 30 independently controllable zones and a closed-Brayton cycle engine simulator to circulate and condition the helium-xenon gas mixture. The test article, test support hardware, facilities, and instrumentation developed to conduct the ground test program are all described.

  5. 47 CFR 73.6027 - Class A TV notifications concerning interference to radio astronomy, research and receiving...

    Science.gov (United States)

    2010-10-01

    ... interference to radio astronomy, research and receiving installations. 73.6027 Section 73.6027... radio astronomy, research and receiving installations. An applicant for digital operation of an existing... astronomy, research and receiving installations. [69 FR 69331, Nov. 29, 2004] ...

  6. Forward-biased nanophotonic detector for ultralow-energy dissipation receiver

    Science.gov (United States)

    Nozaki, Kengo; Matsuo, Shinji; Fujii, Takuro; Takeda, Koji; Shinya, Akihiko; Kuramochi, Eiichi; Notomi, Masaya

    2018-04-01

    Generally, reverse-biased photodetectors (PDs) are used for high-speed optical receivers. The forward voltage region is only utilized in solar-cells, and this photovoltaic operation would not be concurrently obtained with high efficiency and high speed operation. Here we report that photonic-crystal waveguide PDs enable forward-biased high-speed operation at 40 Gbit/s with keeping high responsivity (0.88 A/W). Within our knowledge, this is the first demonstration of the forward-biased PDs with high responsivity. This achievement is attributed to the ultracompactness of our PD and the strong light confinement within the absorber and depleted regions, thereby enabling efficient photo-carrier generation and fast extraction. This result indicates that it is possible to construct a high-speed and ultracompact photo-receiver without an electrical amplifier nor an external bias circuit. Since there is no electrical energy required, our estimation shows that the consumption energy is just the optical energy of the injected signal pulse which is about 1 fJ/bit. Hence, it will lead to an ultimately efficient and highly integrable optical-to-electrical converter in a chip, which will be a key ingredient for dense nanophotonic communication and processors.

  7. Forward-biased nanophotonic detector for ultralow-energy dissipation receiver

    Directory of Open Access Journals (Sweden)

    Kengo Nozaki

    2018-04-01

    Full Text Available Generally, reverse-biased photodetectors (PDs are used for high-speed optical receivers. The forward voltage region is only utilized in solar-cells, and this photovoltaic operation would not be concurrently obtained with high efficiency and high speed operation. Here we report that photonic-crystal waveguide PDs enable forward-biased high-speed operation at 40 Gbit/s with keeping high responsivity (0.88 A/W. Within our knowledge, this is the first demonstration of the forward-biased PDs with high responsivity. This achievement is attributed to the ultracompactness of our PD and the strong light confinement within the absorber and depleted regions, thereby enabling efficient photo-carrier generation and fast extraction. This result indicates that it is possible to construct a high-speed and ultracompact photo-receiver without an electrical amplifier nor an external bias circuit. Since there is no electrical energy required, our estimation shows that the consumption energy is just the optical energy of the injected signal pulse which is about 1 fJ/bit. Hence, it will lead to an ultimately efficient and highly integrable optical-to-electrical converter in a chip, which will be a key ingredient for dense nanophotonic communication and processors.

  8. Revisión del programa de déficit de somatropina en pediatría en el Hospital Universitario Virgen del Rocío

    OpenAIRE

    Lavaredas, A.; Puerta, R. de la; Álvarez del Vayo, C.

    2013-01-01

    Objetivo: Elaborar una revisión del programa de déficit de somatropina aplicado en pediatría en el Hospital Universitario Virgen del Rocío, utilizando dos grupos de pacientes, los diagnosticados con déficit de esta hormona y los nacidos pequeños para edad gestacional, con la intención de evaluar su efectividad en el primer año de tratamiento. Método: Realización de un estudio retrospectivo de la cohorte de pacientes en tratamiento con la hormona del crecimiento bajo los diagnósticos mencionad...

  9. Translating 'distress' and screening for emotional distress in multicultural cancer patients in Israel.

    Science.gov (United States)

    Cohen, Miri; Gagin, Roni; Cinamon, Tali; Stein, Tamar; Moscovitz, Marian; Kuten, Abraham

    2012-05-01

    The adaptability of the distress thermometer (DT) to multicultural groups has rarely been assessed. To assess DT adaptability to the Israeli population as a multicultural society. Participants were 496 cancer patients. They were recruited for 3 days a week in 2009-2010 (97% response rate). Participants completed the DT, a problem list, Hospital Anxiety and Depression Scale (HADS), and the Brief Symptom Inventory (BSI-18). Receiver-operating characteristic (ROC) curve analyses of DT scores yielded area under the curve (AUC) of 0.63 as against HADS and of 0.78 as against BSI-18. ROC analysis revealed that the optimal cutoff score was ≥ 3. It yielded sensitivity and specificity of 0.74 and 0.65, as against the HADS, and 0.64 and 0.64, as against the BSI-18. The Jewish participants reported higher distress than the Arab participants, and the ROC properties were markedly higher for the Jewish subgroup alone. The adapted DT was moderately efficient for detecting emotional distress in cancer patients in Israel. Cultural aspects related to distress should be taken into account for administration of the DT in multicultural societies.

  10. Auditory detection of an increment in the rate of a random process

    International Nuclear Information System (INIS)

    Brown, W.S.; Emmerich, D.S.

    1994-01-01

    Recent experiments have presented listeners with complex tonal stimuli consisting of components with values (i.e., intensities or frequencies) randomly sampled from probability distributions [e.g., R. A. Lutfi, J. Acoust. Soc. Am. 86, 934--944 (1989)]. In the present experiment, brief tones were presented at intervals corresponding to the intensity of a random process. Specifically, the intervals between tones were randomly selected from exponential probability functions. Listeners were asked to decide whether tones presented during a defined observation interval represented a ''noise'' process alone or the ''noise'' with a ''signal'' process added to it. The number of tones occurring in any observation interval is a Poisson variable; receiver operating characteristics (ROCs) arising from Poisson processes have been considered by Egan [Signal Detection Theory and ROC Analysis (Academic, New York, 1975)]. Several sets of noise and signal intensities and observation interval durations were selected which were expected to yield equivalent performance. Rating ROCs were generated based on subjects' responses in a single-interval, yes--no task. The performance levels achieved by listeners and the effects of intensity and duration are compared to those predicted for an ideal observer

  11. A proposal for a new Brazilian six-item version of the Edinburgh Postnatal Depression Scale

    Directory of Open Access Journals (Sweden)

    Maicon Rodrigues Albuquerque

    Full Text Available Abstract Introduction: Factor analysis of the Edinburgh Postnatal Depression Scale (EPDS could result in a shorter and easier to handle screening tool. Therefore, the aim of this study was to check and compare the metrics of two different 6-item EPDS subscales. Methods: We administered the EPDS to a total of 3,891 women who had given birth between 1 and 3 months previously. We conducted confirmatory and exploratory factor analyses and plotted receiver-operating characteristics (ROC curves to, respectively, determine construct validity, scale items' fit to the data, and ideal cutoff scores for the short versions. Results: A previously defined 6-item scale did not exhibit construct validity for our sample. Nevertheless, we used exploratory factor analysis to derive a new 6-item scale with very good construct validity. The area under the ROC curve of the new 6-item scale was 0.986 and the ideal cutoff score was ≥ 6. Conclusions: The new 6-item scale has adequate psychometric properties and similar ROC curve values to the10-item version and offers a means of reducing the cost and time taken to administer the instrument.

  12. Predictive inference for best linear combination of biomarkers subject to limits of detection.

    Science.gov (United States)

    Coolen-Maturi, Tahani

    2017-08-15

    Measuring the accuracy of diagnostic tests is crucial in many application areas including medicine, machine learning and credit scoring. The receiver operating characteristic (ROC) curve is a useful tool to assess the ability of a diagnostic test to discriminate between two classes or groups. In practice, multiple diagnostic tests or biomarkers are combined to improve diagnostic accuracy. Often, biomarker measurements are undetectable either below or above the so-called limits of detection (LoD). In this paper, nonparametric predictive inference (NPI) for best linear combination of two or more biomarkers subject to limits of detection is presented. NPI is a frequentist statistical method that is explicitly aimed at using few modelling assumptions, enabled through the use of lower and upper probabilities to quantify uncertainty. The NPI lower and upper bounds for the ROC curve subject to limits of detection are derived, where the objective function to maximize is the area under the ROC curve. In addition, the paper discusses the effect of restriction on the linear combination's coefficients on the analysis. Examples are provided to illustrate the proposed method. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Yfiler® Plus population samples and dilution series

    DEFF Research Database (Denmark)

    Andersen, Mikkel Meyer; Mogensen, Helle Smidt; Eriksen, Poul Svante

    2017-01-01

    DNA complicated the analysis by causing drop-ins of characteristic female DNA artefacts. Even though the customised analytical threshold in combination with the custom-made artefact filters gave more alleles, crime scene samples still needed special attention from the forensic geneticist....... dynamics and performance. We determined dye-dependent analytical thresholds by receiver operating characteristics (ROC) and made a customised artefact filter that includes theoretical known artefacts by use of previously analysed population samples. Dilution series of known male DNA and a selection...

  14. Fusion of multiscale wavelet-based fractal analysis on retina image for stroke prediction.

    Science.gov (United States)

    Che Azemin, M Z; Kumar, Dinesh K; Wong, T Y; Wang, J J; Kawasaki, R; Mitchell, P; Arjunan, Sridhar P

    2010-01-01

    In this paper, we present a novel method of analyzing retinal vasculature using Fourier Fractal Dimension to extract the complexity of the retinal vasculature enhanced at different wavelet scales. Logistic regression was used as a fusion method to model the classifier for 5-year stroke prediction. The efficacy of this technique has been tested using standard pattern recognition performance evaluation, Receivers Operating Characteristics (ROC) analysis and medical prediction statistics, odds ratio. Stroke prediction model was developed using the proposed system.

  15. Eumetcast receiving station integration withinthe satellite image database interface (SAIDIN) system.

    OpenAIRE

    Chic, Òscar

    2010-01-01

    Within the tasks devoted to operational oceanography, Coastal Ocean Observatory at Institut de Ciències del Mar (CSIC) has acquired an European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Broadcast System for Environmental Data (EUMETCast reception system) to replace a satellite direct broadcast system that receives data via High Resolution Picture Transmission (HRPT). EUMETCast system can receive data based on standard Digital Video Broadcastin...

  16. Gunshot Wounds in Military Working Dogs in Operation Enduring Freedom and Operation Iraqi Freedom: 29 cases (2003-2009)

    Science.gov (United States)

    2013-01-01

    oxygenmask held in proximity to the dog’s face or taped to a basket-style muzzle ) during evacuation to the VTF. None of the WIA dogs received IV crystalloid...military working dogs in Operation Enduring Freedom and Operation Iraqi Freedom: 29 cases (2003–2009) Janice L. Baker, DVM; Karyn A. Havas, DVM; Laura A...received on the battlefield, and ultimate outcome of U.S. military working dogs that incurred gunshot wound (GSW) injury in Operation Enduring Freedom

  17. Solar central receiver reformer system for ammonia plants

    Science.gov (United States)

    1980-07-01

    Details of the conceptual design, economic analysis, and development plan for a solar central receiver system for retrofitting the Valley Nitrogen Producers, Inc., El Centro, California 600 ST/SD Ammonia Plant are presented. The retrofit system consists of a solar central receiver reformer (SCRR) operating in parallel with the existing fossil fired reformer. Steam and hydrocarbon react in the catalyst filled tubes of the inner cavity receiver to form a hydrogen rich mixture which is the syngas feed for the ammonia production. The SCRR system displaces natural gas presently used in the fossil reformer combustion chamber. The solar reformer retrofit system characteristics and its interface with the existing plant are simple, incorporating state of the art components with proven technology. A northfield composed of one thousand forty second generation heliostats provides solar energy to the receiver which is positioned on top of a 90 meter high steel tower. The overall economics of this system can provide over 20% discount cash flow rate of return with proper investment and market conditions.

  18. Spread Spectrum Receiver Electromagnetic Interference (EMI) Test Guide

    Science.gov (United States)

    Wheeler, M. L.

    1998-01-01

    The objective of this test guide is to document appropriate unit level test methods and techniques for the performance of EMI testing of Direct Sequence (DS) spread spectrum receivers. Consideration of EMI test methods tailored for spread spectrum receivers utilizing frequency spreading, techniques other than direct sequence (such as frequency hopping, frequency chirping, and various hybrid methods) is beyond the scope of this test guide development program and is not addressed as part of this document EMI test requirements for NASA programs are primarily developed based on the requirements contained in MIL-STD-46 1 D (or earlier revisions of MIL-STD-46 1). The corresponding test method guidelines for the MIL-STD-461 D tests are provided in MIL-STD-462D. These test methods are well documented with the exception of the receiver antenna port susceptibility tests (intermodulation, cross modulation, and rejection of undesired signals) which must be tailored to the specific type of receiver that is being tested. Thus, test methods addressed in this guide consist only of antenna port tests designed to evaluate receiver susceptibility characteristics. MIL-STD-462D should be referred for guidance pertaining to test methods for EMI tests other than the antenna port tests. The scope of this test guide includes: (1) a discussion of generic DS receiver performance characteristics; (2) a summary of S-band TDRSS receiver operation; (3) a discussion of DS receiver EMI susceptibility mechanisms and characteristics; (4) a summary of military standard test guidelines; (5) recommended test approach and methods; and (6) general conclusions and recommendations for future studies in the area of spread spectrum receiver testing.

  19. Circulating basal anti-Müllerian hormone levels as predictor of ovarian response in women undergoing ovarian stimulation for in vitro fertilization.

    Science.gov (United States)

    Nardo, Luciano G; Gelbaya, Tarek A; Wilkinson, Hannah; Roberts, Stephen A; Yates, Allen; Pemberton, Phil; Laing, Ian

    2009-11-01

    To evaluate the clinical value of basal anti-Müllerian hormone (AMH) measurements compared with other available determinants, apart from chronologic age, in the prediction of ovarian response to gonadotrophin stimulation. Prospective cohort study. Tertiary referral center for reproductive medicine and an IVF unit. Women undergoing their first cycle of controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF). Basal levels of FSH and AMH as well as antral follicle count (AFC) were measured in 165 subjects. All patients were followed prospectively and their cycle outcomes recorded. Predictive value of FSH, AMH, and AFC for extremes of ovarian response to stimulation. Out of the 165 women, 134 were defined as normal responders, 15 as poor responders, and 16 as high responders. Subjects in the poor response group were significantly older then those in the other two groups. Anti-Müllerian hormone levels and AFC were markedly raised in the high responders and decreased in the poor responders. Compared with FSH and AFC, AMH performed better in the prediction of excessive response to ovarian stimulation-AMH area under receiver operating characteristic curve (ROC(AUC)) 0.81, FSH ROC(AUC) 0.66, AFC ROC(AUC) 0.69. For poor response, AMH (ROC(AUC) 0.88) was a significantly better predictor than FSH (ROC(AUC) 0.63) but not AFC (ROC(AUC) 0.81). AMH prediction of ovarian response was independent of age and PCOS. Anti-Müllerian hormone cutoffs of >3.75 ng/mL and stimulation with exogenous gonadotrophins. Overall, this biomarker is superior to basal FSH and AFC, and has the potential to be incorporated in to work-up protocols to predict patient's ovarian response to treatment and to individualize strategies aiming at reducing the cancellation rate and the iatrogenic complications of COH.

  20. A new comparison of hyperspectral anomaly detection algorithms for real-time applications

    Science.gov (United States)

    Díaz, María.; López, Sebastián.; Sarmiento, Roberto

    2016-10-01

    Due to the high spectral resolution that remotely sensed hyperspectral images provide, there has been an increasing interest in anomaly detection. The aim of anomaly detection is to stand over pixels whose spectral signature differs significantly from the background spectra. Basically, anomaly detectors mark pixels with a certain score, considering as anomalies those whose scores are higher than a threshold. Receiver Operating Characteristic (ROC) curves have been widely used as an assessment measure in order to compare the performance of different algorithms. ROC curves are graphical plots which illustrate the trade- off between false positive and true positive rates. However, they are limited in order to make deep comparisons due to the fact that they discard relevant factors required in real-time applications such as run times, costs of misclassification and the competence to mark anomalies with high scores. This last fact is fundamental in anomaly detection in order to distinguish them easily from the background without any posterior processing. An extensive set of simulations have been made using different anomaly detection algorithms, comparing their performances and efficiencies using several extra metrics in order to complement ROC curves analysis. Results support our proposal and demonstrate that ROC curves do not provide a good visualization of detection performances for themselves. Moreover, a figure of merit has been proposed in this paper which encompasses in a single global metric all the measures yielded for the proposed additional metrics. Therefore, this figure, named Detection Efficiency (DE), takes into account several crucial types of performance assessment that ROC curves do not consider. Results demonstrate that algorithms with the best detection performances according to ROC curves do not have the highest DE values. Consequently, the recommendation of using extra measures to properly evaluate performances have been supported and justified by

  1. The comparison of free androgen index and serum free testosterone levels in women with hirsutism or polycystic ovary syndrome

    Directory of Open Access Journals (Sweden)

    M. Metin Yıldırımkaya

    2011-06-01

    Full Text Available In many laboratories free testosterone can not be measured, so that free androgen index is suggested instead. The aim of this study was to compare free androgen index and serum free testosterone levels measured by radioimmunoassay in women with hirsutism or polycystic ovary syndrome.Materials and methods: Totally 94 women referred to the polyclinics of Ankara Numune Hospital were retrospectively included. Three patient groups were composed; 55 of hirsutism, 20 of polycystic ovary syndrome and 19 of both hirsutism and polycystic ovary syndrome. Total testosterone and sex hormone binding globuline levels were measured by chemiluminescence method and free testosterone levels were measured by radioimmunoassay. Free androgen index was calculated from total testosterone and sex hormone binding globuline.Results: There was a significant positive correlation between free testosterone and free androgen index in patients with hirsutism, in patients with polycystic ovary syndrome, in patients with hirsutism and polycystic ovary syndrome, and in total patient group [r(hirsutism=0,597, r(PCOS=0,617, r(hirsutism and PCOS=0,779, r(total patient group=0,649, P<0,01].Receiver operating characteristics curves were drawn to assess the diagnostic power of parameters for all patient groups [For hirsutism (n=55 auROC (FT=0,431 auROC (FAI=0,485] [For PCOS (n=20 auROC (FT=0,431 auROC (FAI=0,359] [For hirsutism and PCOS (n=19 auROC (FT=0,676 auROC (FAI=0,669]. In our study, free testosterone and free androgen index were found useful to diagnose ‘hirsutism and polycystic ovary syndrome’ but not others.Conclusion: Free androgen index can be used instead of free testosterone in hirsutism and polycystic ovary syndrome for diagnosis. J Clin Exp Invest 2011;2(2:152-6

  2. Download this PDF file

    African Journals Online (AJOL)

    2000-08-11

    Department of Chemistry, University of Ilorin, Ilorin, Nigeria;. 'Institute of Chemistry, Academia Sinica. Taipei, Taiwan, ROC. Department of Chemistry. National Taiwan University, Taipei, Taiwan. ROC. (Received August 11, 2000; revised January 17, 2001). ABSTRACT. A trace amount of n-BuLi at -78 C initiates a chemical ...

  3. A heat receiver design for solar dynamic space power systems

    Science.gov (United States)

    Baker, Karl W.; Dustin, Miles O.; Crane, Roger

    1990-01-01

    An advanced heat pipe receiver designed for a solar dynamic space power system is described. The power system consists of a solar concentrator, solar heat receiver, Stirling heat engine, linear alternator and waste heat radiator. The solar concentrator focuses the sun's energy into a heat receiver. The engine and alternator convert a portion of this energy to electric power and the remaining heat is rejected by a waste heat radiator. Primary liquid metal heat pipes transport heat energy to the Stirling engine. Thermal energy storage allows this power system to operate during the shade portion of an orbit. Lithium fluoride/calcium fluoride eutectic is the thermal energy storage material. Thermal energy storage canisters are attached to the midsection of each heat pipe. The primary heat pipes pass through a secondary vapor cavity heat pipe near the engine and receiver interface. The secondary vapor cavity heat pipe serves three important functions. First, it smooths out hot spots in the solar cavity and provides even distribution of heat to the engine. Second, the event of a heat pipe failure, the secondary heat pipe cavity can efficiently transfer heat from other operating primary heat pipes to the engine heat exchanger of the defunct heat pipe. Third, the secondary heat pipe vapor cavity reduces temperature drops caused by heat flow into the engine. This unique design provides a high level of reliability and performance.

  4. Análise de um modelo de risco pré-operatório específico para cirurgia valvar e a relação com o tempo de internação em unidade de terapia intensiva Analysis of specific pre-operative model to valve surgery and relationship with the length of stay in intensive care unit

    Directory of Open Access Journals (Sweden)

    Felipe Montes Pena

    2010-12-01

    Full Text Available OBJETIVOS: O tempo de internação prolongado após cirurgia cardíaca é associado a resultados imediatos ruins e aumento dos custos. O objetivo deste estudo foi analisar o poder preditor do escore de Ambler na previsão do tempo de internação em unidade de terapia intensiva. MÉTODOS: Estudo de coorte retrospectiva com dados coletados de 110 pacientes submetidos à cirurgia de troca valvar isolada ou associada. Os valores do escore aditivo e logístico do escore de Ambler e as performances preditivas do escore de Ambler foram obtidos por meio da curva ROC. A estadia em unidade de terapia intensiva definiu-se como normal 3 dias. A área sobre as curvas dos modelos aditivo e logístico foram comparadas por meio do teste de Hanley-MacNeil. RESULTADOS: A média de permanência em unidade de terapia intensiva foi de 4,2 dias. Sessenta e três pacientes pertenciam ao sexo masculino. O modelo logístico apresentou área sob a curva ROC de 0,73 e 0,79 para internação >3 dias e 3 dias e OBJECTIVES: The length of stay after prolonged cardiac surgery has been associated with poor immediate outcomes and increased costs. This study aimed to evaluate the predictive power of the Ambler Score to anticipate the length of stay in the intensive care unit. METHODS: This was a retrospective cohort study based on data collected from 110 patients undergoing valve replacement surgery alone or in combination with other procedures. Additive and logistic Ambler Scores were obtained and their predictive performances calculated using the Receiver Operating Characteristic curve. The normal length stay in the intensive care unit was assumed to be 3 days. The areas under the receiver operating curves for both the additive and logistic models were compared using the Hanley-MacNeil test. RESULTS: The mean intensive care unit length of stay was 4.2 days. Sixty-three patients were male. The logistic model showed areas under the receiver operating characteristic curve of 0

  5. Conceptual design of advanced central receiver power systems sodium-cooled receiver concept. Volume 2, Book 1. Commercial plant conceptual design. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-03-01

    The conceptual design of the 100-MW solar tower focus commercial power plant is described in detail. Sodium is pumped up to the top of a tall tower where the receiver is located. The sodium is heated in the receiver and then flows down the tower, through a pressure reducing device, and thence into a large, hot storage tank which is located at ground level and whose size is made to meet a specific thermal energy storage capacity requirement. From this tank, the sodium is pumped by a separate pump, through a system of sodium-to-water steam generators. The steam generator system consists of a separate superheater and reheater operating in parallel and an evaporator unit operating in series with the other two units. The sodium flowing from the evaporator unit is piped to a cold storage tank. From the cold storage tank, sodium is then pumped up to the tip of the tower to complete the cycle. The steam generated in the steam generators is fed to a conventional off-the-shelf, high-efficiency turbine. The steam loop operates in a conventional rankine cycle with the steam generators serving the same purpose as a conventional boiler and water being fed to the evaporator with conventional feedwater pumps. The pressure reducing device (a standard drag valve, for example) serves to mitigate the pressure caused by the static head of sodium and thus allows the large tanks to operate at ambient pressure conditions. (WHK)

  6. Graphene radio frequency receiver integrated circuit.

    Science.gov (United States)

    Han, Shu-Jen; Garcia, Alberto Valdes; Oida, Satoshi; Jenkins, Keith A; Haensch, Wilfried

    2014-01-01

    Graphene has attracted much interest as a future channel material in radio frequency electronics because of its superior electrical properties. Fabrication of a graphene integrated circuit without significantly degrading transistor performance has proven to be challenging, posing one of the major bottlenecks to compete with existing technologies. Here we present a fabrication method fully preserving graphene transistor quality, demonstrated with the implementation of a high-performance three-stage graphene integrated circuit. The circuit operates as a radio frequency receiver performing signal amplification, filtering and downconversion mixing. All circuit components are integrated into 0.6 mm(2) area and fabricated on 200 mm silicon wafers, showing the unprecedented graphene circuit complexity and silicon complementary metal-oxide-semiconductor process compatibility. The demonstrated circuit performance allow us to use graphene integrated circuit to perform practical wireless communication functions, receiving and restoring digital text transmitted on a 4.3-GHz carrier signal.

  7. The use of the AOA TTR-4P GPS receiver in operation at the BIPM for real-time restitution of GPS time

    Science.gov (United States)

    Thomas, Claudine

    1994-01-01

    The Global Positioning System is an outstanding tool for the dissemination of time. Using mono-channel C/A-code GPS time receivers, the restitution of GPS time through the satellite constellation presents a peak-to-peak discrepancy of several tens of nanoseconds without SA but may be as high as several hundreds of nanoseconds with SA. As a consequence, civil users are more and more interested in implementing hardware and software methods for efficient restitution of GPS time, especially in the framework of the project of a real-time prediction of UTC (UTCp) which could be available in the form of time differences (UTCp - GPS time). Previous work, for improving the real-time restitution of GPS time with SA, to the level obtained without SA, focused on the implementation of a Kalman filter based on past data and updated at each new observation. An alternative solution relies upon the statistical features of the noise brought about by SA; it has already been shown that the SA noise is efficiently reduced by averaging data from numerous satellites observed simultaneously over a sufficiently long time. This method was successfully applied to data from a GPS time receiver, model AOA TTR-4P, connected to the cesium clock kept at the BIPM. This device, a multi-channel, dual frequency, P-code GPS time receiver, is one of the first TTR-4P units in operation in a civil laboratory. Preliminary comparative studies of this new equipment with conventional GPS time receivers are described in this paper. The results of an experimental restitution of GPS time, obtained in June 1993, are also detailed: 3 to 6 satellites were observed simultaneously with a sample interval of 15 s, an efficient smoothing of SA noise was realized by averaging data on all observed satellites over more than 1 hour. When the GPS system is complete in 1994, 8 satellites will be observable continuously from anywhere in the world and the same level of uncertainty will be obtained using a shorter averaging

  8. Observer Variability and the Performance between Faculties and Residents: US Criteria for Benign and Malignant Thyroid Nodules

    International Nuclear Information System (INIS)

    Kim, Sung Hun; Park, Chang Suk; Jung, So Lyung

    2010-01-01

    To evaluate the interobserver variability and performance in the interpretation of ultrasonographic (US) findings of thyroid nodules. 72 malignant nodules and 61 benign nodules were enrolled as part of this study. Five faculty radiologists and four residents independently performed a retrospective analysis of the US images. The observers received one training session after the first interpretation and then performed a secondary interpretation. Agreement was analyzed by Cohen's kappa statistic. Degree of performance was analyzed using receiver operating characteristic (ROC) curves. Agreement between the faculties was fair-to-good for all criteria; however, between residents, agreement was poor-to-fair. The area under the ROC curves was 0.72, 0.62, and 0.60 for the faculties, senior residents, and junior residents, respectively. There was a significant difference in performance between the faculties and the residents (p < 0.05). There was a significant increase in the agreement for some criteria in the faculties and the senior residents after the training session, but no significant increase in the junior residents. Independent reporting of thyroid US performed by residents is undesirable. A continuous and specialized resident training is essential to enhance the degree of agreement and performance

  9. An air-based corrugated cavity-receiver for solar parabolic trough concentrators

    International Nuclear Information System (INIS)

    Bader, Roman; Pedretti, Andrea; Barbato, Maurizio; Steinfeld, Aldo

    2015-01-01

    Highlights: • We analyze a novel tubular cavity-receiver for solar parabolic trough collectors. • Four-fold solar concentration ratio is reached compared to conventional receivers. • Efficient operation at up to 500 °C is possible. • The pumping power requirement is found to be acceptably low. - Abstract: A tubular cavity-receiver that uses air as the heat transfer fluid is evaluated numerically using a validated heat transfer model. The receiver is designed for use on a large-span (9 m net concentrator aperture width) solar parabolic trough concentrator. Through the combination of a parabolic primary concentrator with a nonimaging secondary concentrator, the collector reaches a solar concentration ratio of 97.5. Four different receiver configurations are considered, with smooth or V-corrugated absorber tube and single- or double-glazed aperture window. The collector’s performance is characterized by its optical efficiency and heat loss. The optical efficiency is determined with the Monte Carlo ray-tracing method. Radiative heat exchange inside the receiver is calculated with the net radiation method. The 2D steady-state energy equation, which couples conductive, convective, and radiative heat transfer, is solved for the solid domains of the receiver cross-section, using finite-volume techniques. Simulations for Sevilla/Spain at the summer solstice at solar noon (direct normal solar irradiance: 847 W m −2 , solar incidence angle: 13.9°) yield collector efficiencies between 60% and 65% at a heat transfer fluid temperature of 125 °C and between 37% and 42% at 500 °C, depending on the receiver configuration. The optical losses amount to more than 30% of the incident solar radiation and constitute the largest source of energy loss. For a 200 m long collector module operated between 300 and 500 °C, the isentropic pumping power required to pump the HTF through the receiver is between 11 and 17 kW

  10. Salt Repository Project transportation system interface requirements: Transportation system/repository receiving facility interface requirements

    International Nuclear Information System (INIS)

    Smith, L.A.; Insalaco, J.W.; Trainer, T.A.

    1988-01-01

    This report is a preliminary review of the interface between the transportation system and the repository receiving facility for a nuclear waste mined geologic disposal system in salt. Criteria for generic cask and facility designs are developed. These criteria are derived by examining the interfaces that occur as a result of the operations needed to receive nuclear waste at a repository. These criteria provide the basis for design of a safe, operable, practical nuclear waste receiving facility. The processing functions required to move the shipping unit from the gate into the unloading area and back to the gate for dispatch are described. Criteria for a generic receiving facility are discussed but no specific facility design is presented or evaluated. The criteria are stated in general terms to allow application to a wide variety of cask and facility designs. 9 refs., 6 figs., 4 tabs

  11. Prediction of acute renal allograft rejection in early post-transplantation period by soluble CD30.

    Science.gov (United States)

    Dong, Wang; Shunliang, Yang; Weizhen, Wu; Qinghua, Wang; Zhangxin, Zeng; Jianming, Tan; He, Wang

    2006-06-01

    To evaluate the feasibility of serum sCD30 for prediction of acute graft rejection, we analyzed clinical data of 231 patients, whose serum levels of sCD30 were detected by ELISA before and after transplantation. They were divided into three groups: acute rejection group (AR, n = 49), uncomplicated course group (UC, n = 171) and delayed graft function group (DGF, n = 11). Preoperative sCD30 levels of three groups were 183 +/- 74, 177 +/- 82 and 168 +/- 53 U/ml, respectively (P = 0.82). Significant decrease of sCD30 was detected in three groups on day 5 and 10 post-transplantation respectively (52 +/- 30 and 9 +/- 5 U/ml respectively, P sCD30 values on day 5 post-transplantation (92 +/- 27 U/ml vs. 41 +/- 20 U/ml and 48 +/- 18 U/ml, P sCD30 levels on day 10 post-transplantation were virtually similar in patients of three groups (P = 0.43). Receiver operating characteristic (ROC) curve demonstrated that sCD30 level on day 5 post-transplantation could differentiate patients who subsequently suffered acute allograft rejection from others (area under ROC curve 0.95). According to ROC curve, 65 U/ml may be the optimal operational cut-off level to predict impending graft rejection (specificity 91.8%, sensitivity 87.1%). Measurement of soluble CD30 on day 5 post-transplantation might offer a noninvasive means to recognize patients at risk of impending acute graft rejection during early post-transplantation period.

  12. Artificial neural network study on organ-targeting peptides

    Science.gov (United States)

    Jung, Eunkyoung; Kim, Junhyoung; Choi, Seung-Hoon; Kim, Minkyoung; Rhee, Hokyoung; Shin, Jae-Min; Choi, Kihang; Kang, Sang-Kee; Lee, Nam Kyung; Choi, Yun-Jaie; Jung, Dong Hyun

    2010-01-01

    We report a new approach to studying organ targeting of peptides on the basis of peptide sequence information. The positive control data sets consist of organ-targeting peptide sequences identified by the peroral phage-display technique for four organs, and the negative control data are prepared from random sequences. The capacity of our models to make appropriate predictions is validated by statistical indicators including sensitivity, specificity, enrichment curve, and the area under the receiver operating characteristic (ROC) curve (the ROC score). VHSE descriptor produces statistically significant training models and the models with simple neural network architectures show slightly greater predictive power than those with complex ones. The training and test set statistics indicate that our models could discriminate between organ-targeting and random sequences. We anticipate that our models will be applicable to the selection of organ-targeting peptides for generating peptide drugs or peptidomimetics.

  13. SPECT versus planar bone radionuclide imaging in the detection of spondylolysis

    International Nuclear Information System (INIS)

    Whitten, C.G.; El-Khoury, G.Y.; Chang, P.J.; Seabold, J.E.; Found, E.M.; Renfrew, D.L.

    1991-01-01

    This paper evaluates the relative performance and ease of interpretation of SPECT versus planar radionuclide bone imaging in the detection of spondylolysis. The authors studied all patients presenting with back pain suggestive of spondylolysis from November 1989 to January 1991 who underwent bone scanning; patients underwent both planar and SPECT imaging. The planar and SPECT images were randomly mixed and independently interpreted by four observers for presence or absence of spondylolysis and ease of interpretation for each scan. Receiver operating characteristic (ROC) and analysis of variance (ANOVA) were used. Of 72 patients, 19 had confirmed spondylolysis, and 53 did not. While ROC analysis showed that SPECT performed slightly better than planar imaging for all four observers, the difference was not statistically significant. ANOVA results suggest that planar imaging was significantly easier to use than SPECT and that ease of use was strongly correlated with the observer's confidence in the diagnosis

  14. Assessment of biopsy-proven liver fibrosis by two-dimensional shear wave elastography

    DEFF Research Database (Denmark)

    Herrmann, Eva; de Lédinghen, Victor; Cassinotto, Christophe

    2018-01-01

    sites, as well as on successful transient elastography (TE) in 665 patients. Most patients had chronic hepatitis C (HCV, n = 379), hepatitis B (HBV, n = 400) or non-alcoholic fatty liver disease (NAFLD, n = 156). AUROCs of 2D-SWE in patients with HCV, HBV and NAFLD were 86.3%, 90.6% and 85...... equipment were contacted to share their data. Retrospective statistical analysis used direct and paired receiver operating characteristic (ROC) and area under the ROC curve (AUROC) analysis accounting for random effects. RESULTS: Data on both 2D-SWE and liver biopsy was available in 1134 patients from 13......BACKGROUND AND AIMS: 2D shear wave elastography (2D-SWE) has proven to be efficient for the evaluation of liver fibrosis in small to moderate size clinical trials. We aimed at running a larger scale meta-analysis of individual data. METHODS: Centers which have worked with Aixplorer ultrasound...

  15. Tomosynthesis for the early detection of pulmonary emphysema: diagnostic performance compared with chest radiography, using multidetector computed tomography as reference

    International Nuclear Information System (INIS)

    Yamada, Yoshitake; Jinzaki, Masahiro; Hashimoto, Masahiro; Shiomi, Eisuke; Kuribayashi, Sachio; Abe, Takayuki; Ogawa, Kenji

    2013-01-01

    To compare the diagnostic performance of tomosynthesis with that of chest radiography for the detection of pulmonary emphysema, using multidetector computed tomography (MDCT) as reference. Forty-eight patients with and 63 without pulmonary emphysema underwent chest MDCT, tomosynthesis and radiography on the same day. Two blinded radiologists independently evaluated the tomosynthesis images and radiographs for the presence of pulmonary emphysema. Axial and coronal MDCT images served as the reference standard and the percentage lung volume with attenuation values of -950 HU or lower (LAA -950 ) was evaluated to determine the extent of emphysema. Receiver-operating characteristic (ROC) analysis and generalised estimating equations model were used. ROC analysis revealed significantly better performance (P -950 . The diagnostic performance of tomosynthesis was significantly superior to that of radiography for the detection of pulmonary emphysema. In both tomosynthesis and radiography, the sensitivity was affected by the LAA -950 . (orig.)

  16. Glaucoma detection with damato multifixation campimetry online

    DEFF Research Database (Denmark)

    Olsen, Ane Sophie; Alberti, M.; Serup, L.

    2016-01-01

    to define abnormality, and these were evaluated using the Glaucoma Staging System as gold standard. Receiver operating characteristic (ROC) curves and area under the ROC (AUC) were calculated. Results AUCs from 15 algorithms ranged from 0.79 to 0.90. The most promising algorithm combined results from two...... successive DMCO STANDARD tests. The sensitivity was highly dependent on the severity of glaucoma. Hence, for eyes with mild, moderate, advanced, and severe glaucoma, the DMCO test demonstrated a sensitivity of 11.8, 71.4, 100, and 100%, respectively. The specificity was as high as 98.1%. Median duration per...... eye to complete the DMCO STANDARD test was 86 s for the control group and 125 s in participants with glaucoma. Conclusions DMCO shows promise as a free-of-charge online tool to identify glaucomatous visual field defects in a preselected population. Ongoing studies are evaluating the use of DMCO...

  17. Turbidity of mouthrinsed water as a screening index for oral malodor.

    Science.gov (United States)

    Ueno, Masayuki; Takeuchi, Susumu; Samnieng, Patcharaphol; Morishima, Seiji; Shinada, Kayoko; Kawaguchi, Yoko

    2013-08-01

    The objectives of this research were to examine the relationship between turbidity of mouthrinsed water and oral malodor, and to evaluate whether the turbidity could be used to screen oral malodor. The subjects were 165 oral malodor patients. Gas chromatography and organoleptic test (OT) were used for oral malodor measurement. Oral examination along with collection of saliva and quantification of bacteria was conducted. Turbidity of mouthrinsed water was measured with turbidimeter. Logistic regression with oral malodor status by OT as the dependent variable and receiver operating characteristic (ROC) analysis were performed. Turbidity had a significant association with oral malodor status. In addition, ROC analysis showed that the turbidity had an ability to screen for presence or absence of oral malodor. Turbidity could reflect or represent other influential variables of oral malodor and may be useful as a screening method for oral malodor. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Expecting excellence is key to receivable success in small and rural hospitals.

    Science.gov (United States)

    Boucher, D

    1990-06-01

    Although small and rural hospitals may have trouble hiring experienced billing and collection personnel, they can succeed in keeping down receivable levels and receivable days by adopting two principles for the business office: expect excellence and inspect for excellence. These principles include setting goals for business office staff as well as listening to and implementing their ideas for more effective operations.

  19. Better to receive than to give? Interorganizational service arrangements and hospital performance.

    Science.gov (United States)

    Trinh, Hanh Q; Begun, James W; Luke, Roice D

    2010-01-01

    The literature points to possible efficiencies in local-hospital-system performance, but little is known about the internal dynamics that might contribute to this. Study of the service arrangements that nearby same-system hospitals have with one another should provide clues into how system efficiencies might be attained. The purpose of this research was to better understand the financial and operational effects of service sharing and receiving arrangements among nearby hospitals belonging to the same systems. Data are compiled for the 1,227 U.S. urban acute care hospitals that belong to multihospital systems. A longitudinal structural equation model is employed-environmental pressures and organizational characteristics in 1997 are associated with service sharing and receiving arrangements in 2000; service sharing and receiving arrangements are then associated with performance in 2003. Service sharing and receiving are measured by counts of services focal hospitals report that are not duplicated by other-system hospitals within the same county. Linear Structural Relations (LISREL) is used to estimate the model. In general, market competition from managed care and hospitals influences hospitals to exchange services. For individual hospitals, service sharing has no effects on operational efficiency and financial performance. Service receiving, however, is related to greater efficiencies and higher profits. The findings underscore the asymmetrical relationships that exist among local-system hospitals. Individual hospitals benefit from service receiving arrangements but not from sharing arrangements-it is better to receive than to give. To the extent that individual hospitals independently determine service capacities, systems may not be able to effectively rationalize service offerings.

  20. A 380pW Dual Mode Optical Wake-up Receiver with Ambient Noise Cancellation.

    Science.gov (United States)

    Lim, Wootaek; Jang, Taekwang; Lee, Inhee; Kim, Hun-Seok; Sylvester, Dennis; Blaauw, David

    2016-06-01

    We present a sub-nW optical wake-up receiver for wireless sensor nodes. The wake-up receiver supports dual mode operation for both ultra-low standby power and high data rates, while canceling ambient in-band noise. In 0.18µm CMOS the receiver consumes 380pW in always-on wake-up mode and 28.1µW in fast RX mode at 250kbps.

  1. United States Department of Energy solar receiver technology development

    Science.gov (United States)

    Klimas, P. C.; Diver, R. B.; Chavez, J. M.

    The United States Department of Energy (DOE), through Sandia National Laboratories, has been conducting a Solar Thermal Receiver Technology Development Program, which maintains a balance between analytical modeling, bench and small scale testing, and experimentation conducted at scales representative of commercially-sized equipment. Central receiver activities emphasize molten salt-based systems on large scales and volumetric devices in the modeling and small scale testing. These receivers are expected to be utilized in solar power plants rated between 100 and 200 MW. Distributed receiver research focuses on liquid metal refluxing devices. These are intended to mate parabolic dish concentrators with Stirling cycle engines in the 5 to 25 kW(sub e) power range. The effort in the area of volumetric receivers is less intensive and highly cooperative in nature. A ceramic foam absorber of Sandia design was successfully tested on the 200 kW(sub t) test bed at Plataforma Solar during 1989. Material integrity during the approximately 90-test series was excellent. Significant progress has been made with parabolic dish concentrator-mounted receivers using liquid metals (sodium or a potassium/sodium mixture) as heat transport media. Sandia has successfully solar-tested a pool boiling reflux receiver sized to power a 25 kW Stirling engine. Boiling stability and transient operation were both excellent. This document describes these activities in detail and will outline plans for future development.

  2. Interference-Aware OFDM Receiver for Channels with Sparse Common Supports

    DEFF Research Database (Denmark)

    Barbu, Oana-Elena; Manchón, Carles Navarro; Badiu, Mihai Alin

    2017-01-01

    We design an algorithm for OFDM receivers operating in co-channel interference conditions, where the serving and interfering transmitters are synchronized in time. The channel estimation problem is formulated as one of sparse signal reconstruction using multiple measurement vectors. The proposed...

  3. Optimized molten salt receivers for ultimate trough solar fields

    Science.gov (United States)

    Riffelmann, Klaus-J.; Richert, Timo; Kuckelkorn, Thomas

    2016-05-01

    Today parabolic trough collectors are the most successful concentrating solar power (CSP) technology. For the next development step new systems with increased operation temperature and new heat transfer fluids (HTF) are currently developed. Although the first power tower projects have successfully been realized, up to now there is no evidence of an all-dominant economic or technical advantage of power tower or parabolic trough. The development of parabolic trough technology towards higher performance and significant cost reduction have led to significant improvements in competitiveness. The use of molten salt instead of synthetic oil as heat transfer fluid will bring down the levelized costs of electricity (LCOE) even further while providing dispatchable energy with high capacity factors. FLABEG has developed the Ultimate TroughTM (UT) collector, jointly with sbp Sonne GmbH and supported by public funds. Due to its validated high optical accuracy, the collector is very suitable to operate efficiently at elevated temperatures up to 550 °C. SCHOTT will drive the key-innovations by introducing the 4th generation solar receiver that addresses the most significant performance and cost improvement measures. The new receivers have been completely redesigned to provide a product platform that is ready for high temperature operation up to 550 °C. Moreover distinct product features have been introduced to reduce costs and risks in solar field assembly and installation. The increased material and design challenges incurred with the high temperature operation have been reflected in sophisticated qualification and validation procedures.

  4. The differential diagnostic value of serum homocysteine for white coat hypertension

    OpenAIRE

    Guo, Shitian; Lin, Hui; Pan, Sunlei; Zhai, Xiaoya; Meng, Liping

    2017-01-01

    Objective To assess the value of serum homocysteine (Hcy) in differential diagnosis of white coat hypertension (WCH). Results In this retrospective study, serum Hcy levels were elevated in hypertensive patients (P < 0.001) compared to WCH patients. Serum Hcy levels were positively correlated with 24-h mean systolic blood pressure, r = 0.1378, P < 0.001. The results of the receiving operating characteristic (ROC) curve showed that the AUC value of Hcy was 0.80 (95% CI, 0.77–0.83), the cut-off ...

  5. Run-time adaptation of a reconfigurable mobile UMTS receiver

    NARCIS (Netherlands)

    Smit, L.T.; Smit, Gerardus Johannes Maria; Hurink, Johann L.

    UMTS receivers are mobile devices, which should have a low energy consumption and operates in a frequently changing environment. The idea of this paper is to adapt the amount of signal processing for the reception within an UMTS mobile to this changing environment. In this way the amount of signal

  6. CT and MR assessment of tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space using ROC methodology

    International Nuclear Information System (INIS)

    Hunink, M.G.M.; Slegte, R.G.M. de; Speelman, H.; Gerritsen, G.J.

    1990-01-01

    Neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space requires thorough assessment of location and extension in order to plan appropriate treatment. This study evaluates computer tomography and magnetic resonance imaging in the workup of malignant and non-malignant tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space in 76 patients. An attempt is made to characterize histopathology on magnetic resonance images by analyzing the signal intensities on T1- and T2-weighted images relative to muscle and brain tissue. The test performance of computer tomography and magnetic resonance imaging in the assessment of tumor extension compared with receiver operating characteristic methodology. Although no definitive conclusions can be made as to the histopathology on the basis of the signal intensities on magnetic resonance imaging, some tumors show characteristic images. Receiver operating characteristic analysis of the performance of computer tomography and magnetic resonance imaging in the assessment of extension of neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space, demonstrates no statistically significant difference in overall test performance. However, in evaluating regions involving predominantly soft tissue structures and comparatively large bony structures magnetic resonance imaging is superior to computer tomography, whereas in evaluating regions involving thin bony structures, computer tomography performs better than magnetic resonance imaging. (orig.)

  7. Easy-to-Build Satellite Beacon Receiver for Propagation Experimentation at Millimeter Bands

    Directory of Open Access Journals (Sweden)

    F. Machado

    2014-04-01

    Full Text Available This paper describes the design and development of a digital satellite beacon receiver for propagation experimentation. Satellite beacons are frequently available for pointing large antennas, but such signals can be used for measuring rain attenuation and other phenomena as, for example, tropospheric scintillation. A fairly inexpensive beacon receiver has been built using off-the-shelf parts. This instrument is not at all bulky making it suitable for easy transportation. This article analyzes the receiver specifications, describes in detail its structure and presents some operational test results.

  8. Suicidal Ideation and Behaviours Among Adolescents Receiving Bariatric Surgery: A Case-Control Study.

    Science.gov (United States)

    McPhee, Jeanne; Khlyavich Freidl, Eve; Eicher, Julia; Zitsman, Jeffrey L; Devlin, Michael J; Hildebrandt, Tom; Sysko, Robyn

    2015-11-01

    This study examined the prevalence and correlates of suicidal ideation and behaviour (SI/B) among adolescents receiving bariatric surgery. Charts of 206 adolescents receiving bariatric surgery were reviewed. Cases with SI/B (current/lifetime reported at baseline or event occurring in the programme n = 31, 15%) were case matched on gender, age and surgery type to 31 adolescents reporting current or past psychiatric treatment and 31 adolescents denying lifetime SI/B or psychiatric treatment. Before surgery, adolescents with SI/B reported significantly lower total levels of health-related quality of life (p = 0.01) and greater depressive symptoms (p = 0.004) in comparison with candidates who never received psychiatric treatment. No significant differences were found between groups for the change in depressive symptoms or body mass index following surgery. As in studies of adults, a notable subset of adolescents receiving bariatric surgery indicated pre-operative or post-operative SI/B. It is critical that clinicians evaluate and monitor adolescent patients undergoing bariatric surgery for risk of SI/B. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

  9. Estimating the relative utility of screening mammography.

    Science.gov (United States)

    Abbey, Craig K; Eckstein, Miguel P; Boone, John M

    2013-05-01

    The concept of diagnostic utility is a fundamental component of signal detection theory, going back to some of its earliest works. Attaching utility values to the various possible outcomes of a diagnostic test should, in principle, lead to meaningful approaches to evaluating and comparing such systems. However, in many areas of medical imaging, utility is not used because it is presumed to be unknown. In this work, we estimate relative utility (the utility benefit of a detection relative to that of a correct rejection) for screening mammography using its known relation to the slope of a receiver operating characteristic (ROC) curve at the optimal operating point. The approach assumes that the clinical operating point is optimal for the goal of maximizing expected utility and therefore the slope at this point implies a value of relative utility for the diagnostic task, for known disease prevalence. We examine utility estimation in the context of screening mammography using the Digital Mammographic Imaging Screening Trials (DMIST) data. We show how various conditions can influence the estimated relative utility, including characteristics of the rating scale, verification time, probability model, and scope of the ROC curve fit. Relative utility estimates range from 66 to 227. We argue for one particular set of conditions that results in a relative utility estimate of 162 (±14%). This is broadly consistent with values in screening mammography determined previously by other means. At the disease prevalence found in the DMIST study (0.59% at 365-day verification), optimal ROC slopes are near unity, suggesting that utility-based assessments of screening mammography will be similar to those found using Youden's index.

  10. Multidetector CT Assessment of Lymph Node Size for Nodal Staging in Patients with Potentially Operable Squamous Esophageal Cancer and the 18F-FDG Positron Emission Tomography CT Correlation

    International Nuclear Information System (INIS)

    Yoom, Soo Kyung; Jung, Jung Im; Ahn, Myeong Im; Park, Jae Gil; Yoo, Ie Ryung; Park, Seog Hee; Park, Mi Jung; Park, Hyun Jin

    2010-01-01

    To investigate the size criteria of multidetector computed tomography (MDCT) for the evaluation metastatic lymph nodes (LNs) for potentially operable squamous esophageal cancer, and to compare this information with the results of positron emission tomography-CT (PET-CT). Twenty-four patients who underwent radical esophagectomy for esophageal cancer were studied. All patients had preoperative MDCT and PET-CT. The MDCT findings were compared with those of PET-CT and were correlated with the surgical records. The receiver operating characteristic (ROC) curve method was used to determine the appropriate cut-off value to distinguish benign from metastatic LNs. The size of metastatic LNs (9.35 ± 3.41 mm) was significantly larger than that of benign LNs (5.74 ± 1.64 mm) (p<0.001). The best cut-off value was 7 mm (81.8% sensitivity, 80.8% specificity). PET-CT detected all metastatic LNs except for four in the peritumoral region. The sensitivity and specificity of metastatic LN evaluation on PET-CT were 82.6% and 99.4%, respectively. Only one LN without metastasis showed increased fluoro-2-deoxy-D-glucose uptake on PET-CT. Size of metastatic LNs can typically be < 10 mm. For MDCT, the short diameter of 7 mm may be the optimal criterion. PET-CT is very accurate for the assessment of metastatic LNs except for those in the peritumoral region

  11. Utility as a rationale for choosing observer performance assessment paradigms for detection tasks in medical imaging.

    Science.gov (United States)

    Wunderlich, Adam; Abbey, Craig K

    2013-11-01

    Studies of lesion detectability are often carried out to evaluate medical imaging technology. For such studies, several approaches have been proposed to measure observer performance, such as the receiver operating characteristic (ROC), the localization ROC (LROC), the free-response ROC (FROC), the alternative free-response ROC (AFROC), and the exponentially transformed FROC (EFROC) paradigms. Therefore, an experimenter seeking to carry out such a study is confronted with an array of choices. Traditionally, arguments for different approaches have been made on the basis of practical considerations (statistical power, etc.) or the gross level of analysis (case-level or lesion-level). This article contends that a careful consideration of utility should form the rationale for matching the assessment paradigm to the clinical task of interest. In utility theory, task performance is commonly evaluated with total expected utility, which integrates the various event utilities against the probability of each event. To formalize the relationship between expected utility and the summary curve associated with each assessment paradigm, the concept of a "natural" utility structure is proposed. A natural utility structure is defined for a summary curve when the variables associated with the summary curve axes are sufficient for computing total expected utility, assuming that the disease prevalence is known. Natural utility structures for ROC, LROC, FROC, AFROC, and EFROC curves are introduced, clarifying how the utilities of correct and incorrect decisions are aggregated by summary curves. Further, conditions are given under which general utility structures for localization-based methodologies reduce to case-based assessment. Overall, the findings reveal how summary curves correspond to natural utility structures of diagnostic tasks, suggesting utility as a motivating principle for choosing an assessment paradigm.

  12. Clinical evaluation of JPEG2000 compression for digital mammography

    Science.gov (United States)

    Sung, Min-Mo; Kim, Hee-Joung; Kim, Eun-Kyung; Kwak, Jin-Young; Yoo, Jae-Kyung; Yoo, Hyung-Sik

    2002-06-01

    Medical images, such as computed radiography (CR), and digital mammographic images will require large storage facilities and long transmission times for picture archiving and communications system (PACS) implementation. American College of Radiology and National Equipment Manufacturers Association (ACR/NEMA) group is planning to adopt a JPEG2000 compression algorithm in digital imaging and communications in medicine (DICOM) standard to better utilize medical images. The purpose of the study was to evaluate the compression ratios of JPEG2000 for digital mammographic images using peak signal-to-noise ratio (PSNR), receiver operating characteristic (ROC) analysis, and the t-test. The traditional statistical quality measures such as PSNR, which is a commonly used measure for the evaluation of reconstructed images, measures how the reconstructed image differs from the original by making pixel-by-pixel comparisons. The ability to accurately discriminate diseased cases from normal cases is evaluated using ROC curve analysis. ROC curves can be used to compare the diagnostic performance of two or more reconstructed images. The t test can be also used to evaluate the subjective image quality of reconstructed images. The results of the t test suggested that the possible compression ratios using JPEG2000 for digital mammographic images may be as much as 15:1 without visual loss or with preserving significant medical information at a confidence level of 99%, although both PSNR and ROC analyses suggest as much as 80:1 compression ratio can be achieved without affecting clinical diagnostic performance.

  13. Developing a new diagnostic algorithm for human papilloma virus associated oropharyngeal carcinoma: an investigation of HPV DNA assays.

    Science.gov (United States)

    Cohen, Natasha; Gupta, Michael; Doerwald-Munoz, Lilian; Jang, Dan; Young, James Edward Massey; Archibald, Stuart; Jackson, Bernard; Lee, Jenny; Chernesky, Max

    2017-02-13

    Human papilloma virus (HPV) has been implicated in the development of a large proportion of oropharyngeal squamous cell carcinoma (OPSCC). Current techniques used to diagnose HPV etiology require histopathologic analysis. We aim to investigate the diagnostic accuracy of a new application non-histopathologic diagnostic tests to help assist diagnosis of HPV-related oropharyngeal tumors. Patients with OPSCC with nodal metastasis were consecutively recruited from a multidisciplinary cancer clinic. Appropriate samples were collected and analyzed. The various tests examined included COBAS® 4800, Cervista® HR and Genotyping. These tests were compared to p16 staining, which was used as the diagnostic standard. StataIC 14.2 was used to perform analysis, including sensitivity, specificity and receiver operator characteristic [ROC] curves. The COBAS® FNA (area under ROC 0.863) and saliva (area under ROC 0.847) samples performed well in diagnosing HPV positive and negative tumors. Samples tested with Cervista® did not corroborate p16 status reliably. We were able to increase the diagnostic yield of the COBAS® FNA samples by applying the results of the saliva test to negative FNA samples which correctly identified 11 additional p16 positive tumors (area under ROC 0.915). Surrogate testing for HPV using alternate methods is feasible and closely predicts the results of standard diagnostic methods. In the future, these could minimize invasive procedures for diagnosing HPV-related oropharyngeal cancer, but also help to diagnose and treat patients with unknown primaries.

  14. GO JUPITER PWS EDITED EDR 10KHZ WAVEFORM RECEIVER V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...

  15. GO JUPITER PWS EDITED EDR 1KHZ WAVEFORM RECEIVER V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...

  16. Evaluation of stroke volume variation obtained by arterial pulse contour analysis to predict fluid responsiveness intraoperatively.

    Science.gov (United States)

    Lahner, D; Kabon, B; Marschalek, C; Chiari, A; Pestel, G; Kaider, A; Fleischmann, E; Hetz, H

    2009-09-01

    Fluid management guided by oesophageal Doppler monitor has been reported to improve perioperative outcome. Stroke volume variation (SVV) is considered a reliable clinical predictor of fluid responsiveness. Consequently, the aim of the present trial was to evaluate the accuracy of SVV determined by arterial pulse contour (APCO) analysis, using the FloTrac/Vigileo system, to predict fluid responsiveness as measured by the oesophageal Doppler. Patients undergoing major abdominal surgery received intraoperative fluid management guided by oesophageal Doppler monitoring. Fluid boluses of 250 ml each were administered in case of a decrease in corrected flow time (FTc) to 10%. The ability of SVV to predict fluid responsiveness was assessed by calculation of the area under the receiver operating characteristic (ROC) curve. Twenty patients received 67 fluid boluses. Fifty-two of the 67 fluid boluses administered resulted in fluid responsiveness. SVV achieved an area under the ROC curve of 0.512 [confidence interval (CI) 0.32-0.70]. A cut-off point for fluid responsiveness was found for SVV > or =8.5% (sensitivity: 77%; specificity: 43%; positive predictive value: 84%; and negative predictive value: 33%). This prospective, interventional observer-blinded study demonstrates that SVV obtained by APCO, using the FloTrac/Vigileo system, is not a reliable predictor of fluid responsiveness in the setting of major abdominal surgery.

  17. Thermal State-of-Charge in Solar Heat Receivers

    Science.gov (United States)

    Hall, Carsie, A., III; Glakpe, Emmanuel K.; Cannon, Joseph N.; Kerslake, Thomas W.

    1998-01-01

    A theoretical framework is developed to determine the so-called thermal state-of-charge (SOC) in solar heat receivers employing encapsulated phase change materials (PCMS) that undergo cyclic melting and freezing. The present problem is relevant to space solar dynamic power systems that would typically operate in low-Earth-orbit (LEO). The solar heat receiver is integrated into a closed-cycle Brayton engine that produces electric power during sunlight and eclipse periods of the orbit cycle. The concepts of available power and virtual source temperature, both on a finite-time basis, are used as the basis for determining the SOC. Analytic expressions for the available power crossing the aperture plane of the receiver, available power stored in the receiver, and available power delivered to the working fluid are derived, all of which are related to the SOC through measurable parameters. Lower and upper bounds on the SOC are proposed in order to delineate absolute limiting cases for a range of input parameters (orbital, geometric, etc.). SOC characterization is also performed in the subcooled, two-phase, and superheat regimes. Finally, a previously-developed physical and numerical model of the solar heat receiver component of NASA Lewis Research Center's Ground Test Demonstration (GTD) system is used in order to predict the SOC as a function of measurable parameters.

  18. Integrated synchronous receiver channel for optical instrumentation applications

    Science.gov (United States)

    Benten, Harold G. P. H.; Ruotsalainen, Tarmo; Maekynen, Anssi J.; Rahkonen, Timo E.; Kopola, Harri K.

    1997-09-01

    A two-channel synchronous receiver circuit for optical instrumentation applications has been designed and implemented. Each receiver channel comprises a.o. transimpedance preamplifier, voltage amplifiers, programmable feedback networks, and a synchronous detector. The function of the channel is to extract the slowly varying information carrying signal from a modulated carrier which is accompanied by relatively high levels of noise. As a whole, the channel can be characterized as a narrow band filter around the frequency of interest. Medical applications include arterial oxygen saturation (SaO2) measurement and dental pulp vitality measurement. In both cases, two optical signals with different frequencies are received by a single photodiode. The measured performance of the optical receiver shows its suitability for the above mentioned applications. Therefore the circuit will be used in a small sized, battery-operated sensor prototype to test the sensing method in a clinical environment. Other applications include the signal processing of optical position-sensitive detectors. A summary of measured receiver channel performance: input reduced noise current spectral density between 0.20 and 0.30 pA/(root)Hz at all relevant frequencies, total programmable channel transimpedance between 7 M(Omega) and 500 M(Omega) , lower -3 dB frequency of at least 50 Hz, upper -3 dB frequency of 40 kHz, maximum voltage swing at the demodulator output of 2.4 V.

  19. Precise Receiver Clock Offset Estimations According to Each Global Navigation Satellite Systems (GNSS) Timescales

    Science.gov (United States)

    Thongtan, Thayathip; Tirawanichakul, Pawit; Satirapod, Chalermchon

    2017-12-01

    Each GNSS constellation operates its own system times; namely, GPS system time (GPST), GLONASS system time (GLONASST), BeiDou system time (BDT) and Galileo system time (GST). They could be traced back to Coordinated Universal Time (UTC) scale and are aligned to GPST. This paper estimates the receiver clock offsets to three timescales: GPST, GLONASST and BDT. The two measurement scenarios use two identical multi-GNSS geodetic receivers connected to the same geodetic antenna through a splitter. One receiver is driven by its internal oscillators and another receiver is connected to the external frequency oscillators, caesium frequency standard, kept as the Thailand standard time scale at the National Institute of Metrology (Thailand) called UTC(NIMT). The three weeks data are observed at 30 seconds sample rate. The receiver clock offsets with respected to the three system time are estimated and analysed through the geodetic technique of static Precise Point Positioning (PPP) using a data processing software developed by Wuhan University - Positioning And Navigation Data Analyst (PANDA) software. The estimated receiver clock offsets are around 32, 33 and 18 nanoseconds from GPST, GLONASST and BDT respectively. This experiment is initially stated that each timescale is inter-operated with GPST and further measurements on receiver internal delay has to be determined for clock comparisons especially the high accuracy clock at timing laboratories.

  20. Low-sampling-rate ultra-wideband digital receiver using equivalent-time sampling

    KAUST Repository

    Ballal, Tarig

    2014-09-01

    In this paper, we propose an all-digital scheme for ultra-wideband symbol detection. In the proposed scheme, the received symbols are sampled many times below the Nyquist rate. It is shown that when the number of symbol repetitions, P, is co-prime with the symbol duration given in Nyquist samples, the receiver can sample the received data P times below the Nyquist rate, without loss of fidelity. The proposed scheme is applied to perform channel estimation and binary pulse position modulation (BPPM) detection. Results are presented for two receivers operating at two different sampling rates that are 10 and 20 times below the Nyquist rate. The feasibility of the proposed scheme is demonstrated in different scenarios, with reasonable bit error rates obtained in most of the cases.

  1. Low-sampling-rate ultra-wideband digital receiver using equivalent-time sampling

    KAUST Repository

    Ballal, Tarig; Al-Naffouri, Tareq Y.

    2014-01-01

    In this paper, we propose an all-digital scheme for ultra-wideband symbol detection. In the proposed scheme, the received symbols are sampled many times below the Nyquist rate. It is shown that when the number of symbol repetitions, P, is co-prime with the symbol duration given in Nyquist samples, the receiver can sample the received data P times below the Nyquist rate, without loss of fidelity. The proposed scheme is applied to perform channel estimation and binary pulse position modulation (BPPM) detection. Results are presented for two receivers operating at two different sampling rates that are 10 and 20 times below the Nyquist rate. The feasibility of the proposed scheme is demonstrated in different scenarios, with reasonable bit error rates obtained in most of the cases.

  2. C-reactive protein-to-albumin ratio is a predictor of hepatitis B virus related decompensated cirrhosis: time-dependent receiver operating characteristics and decision curve analysis.

    Science.gov (United States)

    Huang, Si-Si; Xie, Dong-Mei; Cai, Yi-Jing; Wu, Jian-Min; Chen, Rui-Chong; Wang, Xiao-Dong; Song, Mei; Zheng, Ming-Hua; Wang, Yu-Qun; Lin, Zhuo; Shi, Ke-Qing

    2017-04-01

    Hepatitis B virus (HBV) infection remains a major health problem and HBV-related-decompensated cirrhosis (HBV-DC) usually leads to a poor prognosis. Our aim was to determine the utility of inflammatory biomarkers in predicting mortality of HBV-DC. A total of 329 HBV-DC patients were enrolled. Survival estimates for the entire study population were generated using the Kaplan-Meier method. The prognostic values for model for end-stage liver disease (MELD) score, Child-Pugh score, and inflammatory biomarkers neutrophil/lymphocyte ratio, C-reactive protein-to-albumin ratio (CAR), and lymphocyte-to-monocyte ratio (LMR) for HBV-DC were compared using time-dependent receiver operating characteristic curves and time-dependent decision curves. The survival time was 23.1±15.8 months. Multivariate analysis identified age, CAR, LMR, and platelet count as prognostic independent risk factors. Kaplan-Meier analysis indicated that CAR of at least 1.0 (hazard ratio, 7.19; 95% confidence interval, 4.69-11.03), and LMR less than 1.9 (hazard ratio, 2.40; 95% confidence interval, 1.69-3.41) were independently associated with mortality of HBV-DC. The time-dependent receiver operating characteristic indicated that CAR showed the best performance in predicting mortality of HBV-DC compared with LMR, MELD score, and Child-Pugh score. The results were also confirmed by time-dependent decision curves. CAR and LMR were associated with the prognosis of HBV-DC. CAR was superior to LMR, MELD score, and Child-Pugh score in HBV-DC mortality prediction.

  3. Carcinoembryonic antigen (CEA) level, CEA ratio, and treatment outcome of rectal cancer patients receiving pre-operative chemoradiation and surgery

    International Nuclear Information System (INIS)

    Yang, Kai-Lin; Chang, Shih-Ching; Chu, Lee-Shing; Wang, Ling-Wei; Yang, Shung-Haur; Liang, Wen-Yih; Kuo, Ying-Ju; Lin, Jen-Kou; Lin, Tzu-Chen; Chen, Wei-Shone; Jiang, Jeng-Kae; Wang, Huann-Sheng

    2013-01-01

    To investigate serum carcinoembryonic antigen (CEA) as a prognostic factor for rectal cancer patients receiving pre-operative chemoradiotherapy (CRT). Between 2000 and 2009, 138 patients with advanced rectal cancer receiving CRT before surgery at our hospital were retrospectively classified into 3 groups: pre-CRT CEA <6 ng/ml (group L; n = 87); pre-CRT CEA ≥ 6 ng/ml and post-CRT CEA <6 ng/ml (group H-L; n = 32); and both pre- and post-CRT CEA ≥ 6 ng/ml (group H-H; n = 19). CEA ratio (defined as post-CRT CEA divided by pre-CRT CEA), post-CRT CEA level and other factors were reviewed for prediction of pathologic complete response (pCR). Five-year disease-free survival (DFS) was better in groups L (69.0%) and H-L (74.5%) than in group H-H (44.9%) (p = 0.024). Pathologic complete response was observed in 19.5%, 21.9% and 5.3% of groups L, H-L and H-H respectively (p = 0.281). Multivariate analysis showed that ypN stage and pCR were independent prognostic factors for DFS and that post-CRT CEA level was independently predictive of pCR. As a whole, post-CRT CEA <2.61 ng/ml predicted pCR (sensitivity 76.0%; specificity 58.4%). For those with pre-CRT CEA ≥6 ng/ml, post-CRT CEA and CEA ratio both predicted pCR (sensitivity 87.5%, specificity 76.7%). In patients with pre-CRT serum CEA ≥6 ng/ml, those with “normalized” CEA levels after CRT may have similar DFS to those with “normal” (<6 ng/ml) pre-CRT values. Post-CRT CEA level is a predictor for pCR, especially in those with pre-CRT CEA ≥6 ng/ml

  4. Waste Receiving and Processing (WRAP) facility engineering study

    International Nuclear Information System (INIS)

    Christie, M.A.; Cammann, J.W.; McBeath, R.S.; Rode, H.H.

    1985-01-01

    A new Hanford waste management facility, the Waste Receiving and Processing (WRAP) facility (planned to be operational by FY 1994) will receive, inspect, process, and repackage contact-handled transuranic (CH-TRU) contaminated solid wastes. The wastes will be certified according to the waste acceptance criteria for disposal at the Waste Isolation Pilot Plant (WIPP) geologic repository in southeast New Mexico. Three alternatives which could cost effectively be applied to certify Hanford CH-TRU waste to the WIPP Waste Acceptance Criteria (WIPP-WAC) have been examined in this updated engineering study. The alternatives differed primarily in the reference processing systems used to transform nonconforming waste into an acceptable, certified waste form. It is recommended to include the alternative of shredding and immobilizing nonconforming wastes in cement (shred/grout processing) in the WRAP facility. Preliminary capital costs for WRAP in mid-point-of-construction (FY 1991) dollars were estimated at $45 million for new construction and $37 million for modification and installation in an existing Hanford surplus facility (231-Z Building). Operating, shipping, and decommissioning costs in FY 1986 dollars were estimated at $126 million, based on a 23-y WRAP life cycle (1994 to 2017). During this period, the WRAP facility will receive an estimated 38,000 m 3 (1.3 million ft 3 ) of solid CH-TRU waste. The study recommends pilot-scale testing and evaluation of the processing systems planned for WRAP and advises further investigation of the 231-Z Building as an alternative to new facility construction

  5. A terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer.

    Energy Technology Data Exchange (ETDEWEB)

    Klaassen, T. O. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Hajenius, M. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Adam, A. J. L. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Klapwijk, T. M. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Baryshev, A. (SRON National Institute for Space Research, Sorbonnelaan, Utrecht, The Netherlands); Kumar, Sushil (Massachusetts Institute of Technology, Cambridge, MA); Baselmans, J. J. A. (SRON National Institute for Space Research, Sorbonnelaan, Utrecht, The Netherlands); Hu, Qing (Massachusetts Institute of Technology, Cambridge, MA); Yang, Z. Q. (SRON National Institute for Space Research, Sorbonnelaan, Utrecht, The Netherlands); Hovenier, J. N. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Williams, Benjamin S. (Massachusetts Institute of Technology, Cambridge, MA); Gao, J. R. (Delft University of Technology, Lorentzweg, Delft, The Netherlands); Reno, John Louis

    2005-03-01

    We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2 THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8 THz as local oscillator. We measure a double sideband receiver noise temperature of 1400 K at 2.8 THz and 4.2 K, and find that the free-running QCL has sufficient power stability for a practical receiver, demonstrating an unprecedented combination of sensitivity and stability.

  6. Digital Receiver Phase Meter

    Science.gov (United States)

    Marcin, Martin; Abramovici, Alexander

    2008-01-01

    The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density measurements in laser metrology of moving bodies. To illustrate part of the principle of operation of the phase meter, the figure includes a simplified block diagram of a basic singlechannel digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.

  7. Synchronous OEIC Integrating Receiver for Optically Reconfigurable Gate Arrays

    Directory of Open Access Journals (Sweden)

    Carlos Sánchez-Azqueta

    2016-05-01

    Full Text Available A monolithically integrated optoelectronic receiver with a low-capacitance on-chip pin photodiode is presented. The receiver is fabricated in a 0.35 μm opto-CMOS process fed at 3.3 V and due to the highly effective integrated pin photodiode it operates at μW. A regenerative latch acting as a sense amplifier leads in addition to a low electrical power consumption. At 400 Mbit/s, sensitivities of −26.0 dBm and −25.5 dBm are achieved, respectively, for λ = 635 nm and λ = 675 nm (BER = 10−9 with an energy efficiency of 2 pJ/bit.

  8. Objective assessment of image quality VI: imaging in radiation therapy

    International Nuclear Information System (INIS)

    Barrett, Harrison H; Kupinski, Matthew A; Müeller, Stefan; Halpern, Howard J; Morris, John C III; Dwyer, Roisin

    2013-01-01

    Earlier work on objective assessment of image quality (OAIQ) focused largely on estimation or classification tasks in which the desired outcome of imaging is accurate diagnosis. This paper develops a general framework for assessing imaging quality on the basis of therapeutic outcomes rather than diagnostic performance. By analogy to receiver operating characteristic (ROC) curves and their variants as used in diagnostic OAIQ, the method proposed here utilizes the therapy operating characteristic or TOC curves, which are plots of the probability of tumor control versus the probability of normal-tissue complications as the overall dose level of a radiotherapy treatment is varied. The proposed figure of merit is the area under the TOC curve, denoted AUTOC. This paper reviews an earlier exposition of the theory of TOC and AUTOC, which was specific to the assessment of image-segmentation algorithms, and extends it to other applications of imaging in external-beam radiation treatment as well as in treatment with internal radioactive sources. For each application, a methodology for computing the TOC is presented. A key difference between ROC and TOC is that the latter can be defined for a single patient rather than a population of patients. (paper)

  9. Fuel Receiving and Storage Station. License application, amendment 5, addendum

    International Nuclear Information System (INIS)

    1975-06-01

    This Addendum to AG-L105 addresses the utilization of the Service Concentrator for evaporation of low level wastes generated during fuel receiving and storage operations. The Service Concentrator is described from various viewpoints and necessary relevant data are included for adequate assessment of safety. (U.S.)

  10. Heterodyne Receiver for Laboratory Spectrosocpy of Molecules of Astrophysical Importance

    Science.gov (United States)

    Wehres, Nadine; Lewen, Frank; Endres, Christian; Hermanns, Marius; Schlemmer, Stephan

    2016-06-01

    We present first results of a heterodyne receiver built for high-resolution emission laboratory spectroscopy of molecules of astrophysical interest. The room-temperature receiver operates at frequencies between 80 and 110 GHz, consistent with ALMA band 3. Many molecules have been identified in the interstellar and circumstellar medium at exactly these frequencies by comparing emission spectra obtained from telescopes to high-resolution laboratory absorption spectra. Taking advantage of the recent progresses in the field of mm/submm technology in the astronomy community, we have built a room-temperature emission spectrometer making use of heterodyne receiver technology at an instantaneous bandwidth of currently 2.5 GHz. The system performance, in particular the noise temperature and systematic errors, is presented. The proof-of-concept is demonstrated by comparing the emission spectrum of methyl cyanide to respective absorption spectra and to the literature. Future prospects as well as limitations of the new laboratory receiver for the spectroscopy of complex organic molecules or transient species in discharges will be discussed.

  11. Influence of Temperature Variation on Optical Receiver Sensitivity and its Compensation

    Directory of Open Access Journals (Sweden)

    A. Prokes

    2007-09-01

    Full Text Available In the paper, the influence of temperature variation on the sensitivity of an avalanche-photodiode-based optical receiver applied in the free space optical communication link is discussed. Communication systems of this type are exposed to a wide range of operating temperatures, which markedly affect many photodiode and preamplifier parameters. The paper presents a receiver sensitivity calculation, taking into consideration the temperature dependence of avalanche photodiode gain, excess noise factor, dark current and thermal noise of preamplifier resistances, and describes the compensation of temperature effects on photodiode gain based on a corresponding change in the reverse voltage applied to the diode. The calculations are demonstrated on the connection of a small-area silicon APD operating in the wavelength range from 820 to 1150 nm with a transimpedance preamplifier using a bipolar junction transistor.

  12. Maxent modelling for predicting the potential distribution of Thai Palms

    DEFF Research Database (Denmark)

    Tovaranonte, Jantrararuk; Barfod, Anders S.; Overgaard, Anne Blach

    2011-01-01

    on presence data. The aim was to identify potential hot spot areas, assess the determinants of palm distribution ranges, and provide a firmer knowledge base for future conservation actions. We focused on a relatively small number of climatic, environmental and spatial variables in order to avoid...... overprediction of species distribution ranges. The models with the best predictive power were found by calculating the area under the curve (AUC) of receiver-operating characteristic (ROC). Here, we provide examples of contrasting predicted species distribution ranges as well as a map of modeled palm diversity...

  13. Financial and Real Sector Leading Indicators of Recessions in Brazil Using Probabilistic Models

    Directory of Open Access Journals (Sweden)

    Fernando Nascimento de Oliveira

    Full Text Available We examine the usefulness of various financial and real sector variables to forecast recessions in Brazil between one and eight quarters ahead. We estimate probabilistic models of recession and select models based on their outof-sample forecasts, using the Receiver Operating Characteristic (ROC function. We find that the predictive out-of-sample ability of several models vary depending on the numbers of quarters ahead to forecast and on the number of regressors used in the model specification. The models selected seem to be relevant to give early warnings of recessions in Brazil.

  14. Are 1-K display systems suitable for primary diagnosis from radiographic images in picture archiving and communications systems

    International Nuclear Information System (INIS)

    Dawood, R.M.; Todd-Pokropek, A.; Highman, J.H.; Porter, A.; Craig, J.O.M.C.

    1990-01-01

    The authors of this paper performed a formal clinical evaluation of a commercially available high-resolution (1,280-line) picture archiving and communications system workstation. Diagnostic accuracy with plain radiographs was compared with that with laser-digitized images, with the use of receiver operating characteristic (ROC) curve methods. Four major clinical groups were studied: hand films of patients with renal osteodystrophy, chest films of patients with pneumocystis pneumonia, mammograms of patients with breast carcinoma, and skull films of patients with fractures. More than 13,000 observations were recorded

  15. Non-invasive detection of the freezing of gait in Parkinson's disease using spectral and wavelet features.

    Science.gov (United States)

    Nazarzadeh, Kimia; Arjunan, Sridhar P; Kumar, Dinesh K; Das, Debi Prasad

    2016-08-01

    In this study, we have analyzed the accelerometer data recorded during gait analysis of Parkinson disease patients for detecting freezing of gait (FOG) episodes. The proposed method filters the recordings for noise reduction of the leg movement changes and computes the wavelet coefficients to detect FOG events. Publicly available FOG database was used and the technique was evaluated using receiver operating characteristic (ROC) analysis. Results show a higher performance of the wavelet feature in discrimination of the FOG events from the background activity when compared with the existing technique.

  16. Design of the Acoustic Signal Receiving Unit of Acoustic Telemetry While Drilling

    Directory of Open Access Journals (Sweden)

    Li Zhigang

    2016-01-01

    Full Text Available Signal receiving unit is one of the core units of the acoustic telemetry system. A new type of acoustic signal receiving unit is designed to solve problems of the existing devices. The unit is a short joint in whole. It not only can receive all the acoustic signals transmitted along the drill string, without losing any signal, but will not bring additional vibration and interference. In addition, the structure of the amplitude transformer is designed, which can amplify the signal amplitude and improve the receiving efficiency. The design of the wireless communication module makes the whole device can be used in normal drilling process when the drill string is rotating. So, it does not interfere with the normal drilling operation.

  17. Configuration Management Plan for Long Length Contaminated Equipment Receiver and Transport Trailers

    International Nuclear Information System (INIS)

    DALE, R.N.

    2000-01-01

    Long Length Contaminated Equipment Removal System Receiver Trailer and Transport Trailer require a configuration management plan for design, requirements and operations baseline documents. This report serves as the plan for the Trailers

  18. Psychometric Properties of the Dutch Version of the Eating Disorder Inventory–3

    Directory of Open Access Journals (Sweden)

    Vicky Lehmann

    2013-10-01

    Full Text Available The psychometric properties of the Dutch version of the Eating Disorder Inventory–3 (EDI-3 were tested in eating disordered patients (N = 514 using confirmatory factor analyses, variance decomposition, reliabilities, and receiver operating characteristic (ROC curve analyses. Factorial validity results supported the 12 subscales, but model fit was impaired by correlated item errors, misallocated items, and redundant subscales. At the composite level, the Bulimia subscale was identified as a largely specific source of information that did not contribute much to its overarching composite. Reliabilities for subscales and composites ranged from .6 to .9. ROC curve analysis indicated good to excellent discriminative ability of the EDI-3 identifying clinical subjects against a reference group. In conclusion, further revisions of the EDI-3 might target the item allocation and (over-differentiation of subscales and composites to further clarify its structure. For the clinical practice, we advise the careful use of the EDI-3, although it might serve as a good screening tool.

  19. Postoperative three-dimensional CT angiography after cerebral aneurysm clipping with titanium clips: detection with single detector CT. Comparison with intra-arterial digital subtraction angiography

    International Nuclear Information System (INIS)

    Sakuma, I.; Tomura, N.; Kinouchi, H.; Takahashi, S.; Otani, T.; Watarai, J.; Mizoi, K.

    2006-01-01

    AIM: To assess the significance of three-dimensional computed tomography angiography (3D-CTA) in detecting remnant necks after cerebral aneurysm clipping. MATERIALS AND METHODS: A total of 59 patients (77 aneurysms) underwent surgery using titanium clips. Two blinded observers independently evaluated the presence of neck remnants on shaded-surface display (SSD) imaging, volume rendered (VR) imaging, and intra-arterial digital subtraction angiography (IADSA). RESULTS: Mean sensitivity and specificity for detecting neck remnants were 50.0 and 74.2% for SSD imaging, 61.5 and 82.8% for VR imaging, and 92.3 and 92.2% for IADSA, respectively. Receiver operating characteristic (ROC) analysis revealed excellent diagnostic performance for IADSA [mean area under ROC curve (Az)=0.97], and good diagnostic performance for 3D-CTA (Az=0.70 and 0.76 for SSD and VR, respectively). Specificity of VR was better than that SSD (p=0.082), however, there was no significant difference between them. CONCLUSION: Use of 3D-CTA techniques can facilitate postoperative evaluation

  20. Digital mammographic tumor classification using transfer learning from deep convolutional neural networks.

    Science.gov (United States)

    Huynh, Benjamin Q; Li, Hui; Giger, Maryellen L

    2016-07-01

    Convolutional neural networks (CNNs) show potential for computer-aided diagnosis (CADx) by learning features directly from the image data instead of using analytically extracted features. However, CNNs are difficult to train from scratch for medical images due to small sample sizes and variations in tumor presentations. Instead, transfer learning can be used to extract tumor information from medical images via CNNs originally pretrained for nonmedical tasks, alleviating the need for large datasets. Our database includes 219 breast lesions (607 full-field digital mammographic images). We compared support vector machine classifiers based on the CNN-extracted image features and our prior computer-extracted tumor features in the task of distinguishing between benign and malignant breast lesions. Five-fold cross validation (by lesion) was conducted with the area under the receiver operating characteristic (ROC) curve as the performance metric. Results show that classifiers based on CNN-extracted features (with transfer learning) perform comparably to those using analytically extracted features [area under the ROC curve [Formula: see text