896 resultados para Observer performance methods
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Double-observer line transect methods are becoming increasingly widespread, especially for the estimation of marine mammal abundance from aerial and shipboard surveys when detection of animals on the line is uncertain. The resulting data supplement conventional distance sampling data with two-sample mark–recapture data. Like conventional mark–recapture data, these have inherent problems for estimating abundance in the presence of heterogeneity. Unlike conventional mark–recapture methods, line transect methods use knowledge of the distribution of a covariate, which affects detection probability (namely, distance from the transect line) in inference. This knowledge can be used to diagnose unmodeled heterogeneity in the mark–recapture component of the data. By modeling the covariance in detection probabilities with distance, we show how the estimation problem can be formulated in terms of different levels of independence. At one extreme, full independence is assumed, as in the Petersen estimator (which does not use distance data); at the other extreme, independence only occurs in the limit as detection probability tends to one. Between the two extremes, there is a range of models, including those currently in common use, which have intermediate levels of independence. We show how this framework can be used to provide more reliable analysis of double-observer line transect data. We test the methods by simulation, and by analysis of a dataset for which true abundance is known. We illustrate the approach through analysis of minke whale sightings data from the North Sea and adjacent waters.
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International Journal of Paediatric Dentistry 2012; 22: 459466 Aim. This in vitro study aimed to test the performance of fluorescence-based methods in detecting occlusal caries lesions in primary molars compared to conventional methods. Design. Two examiners assessed 113 sites on 77 occlusal surfaces of primary molars using three fluorescence devices: DIAGNOdent (LF), DIAGNOdent pen (LFpen), and fluorescence camera (VistaProof-FC). Visual inspection (ICDAS) and radiographic methods were also evaluated. One examiner repeated the evaluations after one month. As reference standard method, the lesion depth was determined after sectioning and evaluation in stereomicroscope. The area under the ROC curve (Az), sensitivity, specificity, and accuracy of the methods were calculated at enamel (D1) and dentine caries (D3) lesions thresholds. The intra and interexaminer reproducibility were calculated using the intraclass correlation coefficient (ICC) and kappa statistics. Results. At D1, visual inspection presented higher sensitivities (0.970.99) but lower specificities (0.180.25). At D3, all the methods demonstrated similar performance (Az values around 0.90). Visual and radiographic methods showed a slightly higher specificity (values higher than 0.96) than the fluorescence based ones (values around 0.88). In general, all methods presented high reproducibility (ICC higher than 0.79). Conclusions. Although fluorescence-based and conventional methods present similar performance in detecting occlusal caries lesions in primary teeth, visual inspection alone seems to be sufficient to be used in clinical practice.
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This paper presents simple, rapid, precise and accurate stability-indicating HPLC and CE methods, which were developed and validated for the determination of nitrendipine, nimodipine and nisoldipine. These drugs are calcium channel antagonists of the 1,4-dihydropyridine type which are used in the treatment of cardiovascular diseases. Experimental results showed a good linear correlation between the area and the concentration of drugs covering a relatively large domain of concentration in all cases. The linearity of the analytical procedures was in the range of 2.0-120.0 mu g mL-1 for nitrendipine, 1.0-100.0 mu g mL(-1) for nimodipine and 100.0-600.0 mu g mL(-1) for nisoldipine, the regression determination coefficient being higher than 0.99 in all cases. The proposed methods were found to have good precision and accuracy. The chemical stability of these drugs was determined under various conditions and the methods have shown adequate separation for their enantiomers and degradation products. In addition, degradation products produced as a result of stress studies did not interfere with the detection of the drugs' enantiomers and the assays can thus be considered stability-indicating.
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The new Brazilian ABNT NBR 15575 Standard (the ―Standard‖) recommends two methods for analyzing housing thermal performance: a simplified and a computational simulation method. The aim of this paper is to evaluate both methods and the coherence between each. For this, the thermal performance of a low-cost single-family house was evaluated through the application of the procedures prescribed by the Standard. To accomplish this study, the EnergyPlus software was selected. Comparative analyses of the house with varying envelope U-values and solar absorptance of external walls were performed in order to evaluate the influence of these parameters on the results. The results have shown limitations in the current Standard computational simulation method, due to different aspects: weather files, lack of consideration of passive strategies, and inconsistency with the simplified method. Therefore, this research indicates that there are some aspects to be improved in this Standard, so it could better represent the real thermal performance of social housing in Brazil.
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Introduction Toxoplasmosis may be life-threatening in fetuses and in immune-deficient patients. Conventional laboratory diagnosis of toxoplasmosis is based on the presence of IgM and IgG anti-Toxoplasma gondii antibodies; however, molecular techniques have emerged as alternative tools due to their increased sensitivity. The aim of this study was to compare the performance of 4 PCR-based methods for the laboratory diagnosis of toxoplasmosis. One hundred pregnant women who seroconverted during pregnancy were included in the study. The definition of cases was based on a 12-month follow-up of the infants. Methods Amniotic fluid samples were submitted to DNA extraction and amplification by the following 4 Toxoplasma techniques performed with parasite B1 gene primers: conventional PCR, nested-PCR, multiplex-nested-PCR, and real-time PCR. Seven parameters were analyzed, sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and efficiency (Ef). Results Fifty-nine of the 100 infants had toxoplasmosis; 42 (71.2%) had IgM antibodies at birth but were asymptomatic, and the remaining 17 cases had non-detectable IgM antibodies but high IgG antibody titers that were associated with retinochoroiditis in 8 (13.5%) cases, abnormal cranial ultrasound in 5 (8.5%) cases, and signs/symptoms suggestive of infection in 4 (6.8%) cases. The conventional PCR assay detected 50 cases (9 false-negatives), nested-PCR detected 58 cases (1 false-negative and 4 false-positives), multiplex-nested-PCR detected 57 cases (2 false-negatives), and real-time-PCR detected 58 cases (1 false-negative). Conclusions The real-time PCR assay was the best-performing technique based on the parameters of Se (98.3%), Sp (100%), PPV (100%), NPV (97.6%), PLR (â^ž), NLR (0.017), and Ef (99%).
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Purpose – The purpose of the present analysis is to show that HR systems are not always designed in ways that consider the well-being of employees. In particular, performance metric methods seem to be designed with organizational goals in mind while focusing less on what employees need and desire. Design/methodology/approach – A literature review and multiple case-study method was utilized. Findings – The analysis showed that performance metrics should be revaluated by executives and HR professionals if they seek to develop socially responsible organizational cultures which care about the well-being of employees. Originality/value – The paper exposes the fact that performance appraisal techniques can be rooted in methodologies that ignore or deemphasize the value of employee well-being. The analysis provides a context in which all HR practices can be questioned in relation to meeting the standards of a social justice agenda in the area of corporate social responsibility.
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The authors conducted an in vivo study to determine clinical cutoffs for a laser fluorescence (LF) device, an LF pen and a fluorescence camera (FC), as well as to evaluate the clinical performance of these methods and conventional methods in detecting occlusal caries in permanent teeth by using the histologic gold standard for total validation of the sample.
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This in vitro study aimed to assess the speed and caries removal effectiveness of four different new and conventional dentine excavation methods. Eighty deciduous molars were assigned to four groups. Teeth were sectioned longitudinally through the lesion centre. Images of one half per tooth were captured by light microscope and confocal laser scanning microscopy (CLSM) to assess the caries extension. The halves were then reassembled and caries removed using round carbide bur (group 1), Er:YAG laser (group 2), hand excavator (group 3) and a polymer bur (group 4). The time needed for the whole excavation in each tooth was registered. After excavation, the halves were photographed by light microscope. Caries extension obtained from CLSM images were superimposed on the post-excavation images, allowing comparison between caries extension and removal. The regions where caries and preparation limits coincided, as well as the areas of over- and underpreparation, were measured. Steel bur was the fastest method, followed by the polymer bur, hand excavator and laser. Steel bur exhibited also the largest overpreparation area, followed by laser, hand excavator and polymer bur. The largest underpreparation area was found using polymer bur, followed by laser, hand excavator and steel bur. Hand excavator presented the longest coincidence line, followed by polymer and steel burs and laser. Overall, hand excavator seemed to be the most suitable method for carious dentine excavation in deciduous teeth, combining good excavation time with effective caries removal.
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This study compared the performance of fluorescence-based methods, radiographic examination, and International Caries Detection and Assessment System (ICDAS) II on occlusal surfaces. One hundred and nineteen permanent human molars were assessed twice by 2 experienced dentists using the laser fluorescence (LF and LFpen) and fluorescence camera (FC) devices, ICDAS II and bitewing radiographs (BW). After measuring, the teeth were histologically prepared and assessed for caries extension. The sensitivities for dentine caries detection were 0.86 (FC), 0.78 (LFpen), 0.73 (ICDAS II), 0.51 (LF) and 0.34 (BW). The specificities were 0.97 (BW), 0.89 (LF), 0.65 (ICDAS II), 0.63 (FC) and 0.56 (LFpen). BW presented the highest values of likelihood ratio (LR)+ (12.47) and LR- (0.68). Rank correlations with histology were 0.53 (LF), 0.52 (LFpen), 0.41 (FC), 0.59 (ICDAS II) and 0.57 (BW). The area under the ROC curve varied from 0.72 to 0.83. Inter- and intraexaminer intraclass correlation values were respectively 0.90 and 0.85 (LF), 0.93 and 0.87 (LFpen) and 0.85 and 0.76 (FC). The ICDAS II kappa values were 0.51 (interexaminer) and 0.61 (intraexaminer). The BW kappa values were 0.50 (interexaminer) and 0.62 (intraexaminer). The Bland and Altman limits of agreement were 46.0 and 38.2 (LF), 55.6 and 40.0 (LFpen) and 1.12 and 0.80 (FC), for intra- and interexaminer reproducibilities. The posttest probability for dentine caries detection was high for BW and LF. In conclusion, LFpen, FC and ICDAS II presented better sensitivity and LF and BW better specificity. ICDAS II combined with BW showed the best performance and is the best combination for detecting caries on occlusal surfaces.
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BACKGROUND: Over the last 4 years ADAMTS-13 measurement underwent dramatic progress with newer and simpler methods. AIMS: Blind evaluation of newer methods for their performance characteristics. DESIGN: The literature was searched for new methods and the authors invited to join the evaluation. Participants were provided with a set of 60 coded frozen plasmas that were prepared centrally by dilutions of one ADAMTS-13-deficient plasma (arbitrarily set at 0%) into one normal-pooled plasma (set at 100%). There were six different test plasmas ranging from 100% to 0%. Each plasma was tested 'blind' 10 times by each method and results expressed as percentage vs. the local and the common standard provided by the organizer. RESULTS: There were eight functional and three antigen assays. Linearity of observed-vs.-expected ADAMTS-13 levels assessed as r2 ranged from 0.931 to 0.998. Between-run reproducibility expressed as the (mean) CV for repeated measurements was below 10% for three methods, 10-15% for five methods and up to 20% for the remaining three. F-values (analysis of variance) calculated to assess the capacity to distinguish between ADAMTS-13 levels (the higher the F-value, the better the capacity) ranged from 3965 to 137. Between-method variability (CV) amounted to 24.8% when calculated vs. the local and to 20.5% when calculated vs. the common standard. Comparative analysis showed that functional assays employing modified von Willebrand factor peptides as substrate for ADAMTS-13 offer the best performance characteristics. CONCLUSIONS: New assays for ADAMTS-13 have the potential to make the investigation/management of patients with thrombotic microangiopathies much easier than in the past.