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Accuracy
Kinds of Accuracy Terms modified by Accuracy Selected AbstractsON THE ADAPTIVE ACCURACY OF DIRECTIONAL ASYMMETRY IN INSECT WING SIZEEVOLUTION, Issue 11 2008Christophe Pélabon Subtle left,right biases are often observed in organisms with an overall bilateral symmetry. The evolutionary significance of these directional asymmetries remains uncertain, however, and scenarios of both developmental constraints and adaptation have been suggested. Reviewing the literature on asymmetry in insect wings, we analyze patterns of directional asymmetry in wing size to evaluate the possible adaptive significance of this character. We found that directional asymmetry in wing size is widespread among insects, with left- and right-biased asymmetries commonly observed. The direction of the asymmetry does not appear to be evolutionarily conserved above the species level. Overall, we argue that the very small magnitude of directional asymmetry, 0.7% of the wing size on average, associated with an extremely imprecise expression, precludes directional asymmetry from playing any major adaptive role. [source] IMPROVING FORECAST ACCURACY BY COMBINING RECURSIVE AND ROLLING FORECASTS,INTERNATIONAL ECONOMIC REVIEW, Issue 2 2009Todd E. Clark This article presents analytical, Monte Carlo, and empirical evidence on combining recursive and rolling forecasts when linear predictive models are subject to structural change. Using a characterization of the bias,variance trade-off faced when choosing between either the recursive and rolling schemes or a scalar convex combination of the two, we derive optimal observation windows and combining weights designed to minimize mean square forecast error. Monte Carlo experiments and several empirical examples indicate that combination can often provide improvements in forecast accuracy relative to forecasts made using the recursive scheme or the rolling scheme with a fixed window width. [source] SOIL EROSION AND SEDIMENT YIELD PREDICTION ACCURACY USING WEPP,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2004John M. Laflen ABSTRACT: The objectives of this paper are to discuss expectations for the Water Erosion Prediction Project (WEPP) accuracy, to review published studies related to WEPP goodness of fit, and to evaluate these in the context of expectations for WEPP's goodness of fit. WEPP model erosion predictions have been compared in numerous studies to observed values for soil loss and sediment delivery from cropland plots, forest roads, irrigated lands and small watersheds. A number of different techniques for evaluating WEPP have been used, including one recently developed where the ability of WEPP to accurately predict soil erosion can be compared to the accuracy of replicated plots to predict soil erosion. In one study involving 1,594 years of data from runoff plots, WEPP performed similarly to the Universal Soil Loss Erosion (USLE) technology, indicating that WEPP has met the criteria of results being "at least as good with respect to observed data and known relationships as those from the USLE," particularly when the USLE technology was developed using relationships derived from that data set, and using soil erodibility values measured on those plots using data sets from the same period of record. In many cases, WEPP performed as well as could be expected, based on comparisons with the variability in replicate data sets. One major finding has been that soil erodibility values calculated using the technology in WEPP for rainfall conditions may not be suitable for furrow irrigated conditions. WEPP was found to represent the major storms that account for high percentages of soil loss quite well,a single storm application that the USLE technology is unsuitable for,and WEPP has performed well for disturbed forests and forest roads. WEPP has been able to reflect the extremes of soil loss, being quite responsive to the wide differences in cropping, tillage, and other forms of management, one of the requirements for WEPP validation. WEPP was also found to perform well on a wide range of small watersheds, an area where USLE technology cannot be used. [source] DISCREPANCIES IN GLEASON SCORING OF PROSTATE BIOPSIES AND RADICAL PROSTATECTOMY SPECIMENS AND THE EFFECTS OF MULTIPLE NEEDLE BIOPSIES ON SCORING ACCURACY.ANZ JOURNAL OF SURGERY, Issue 5 2007A REGIONAL EXPERIENCE IN TAMWORTH, AUSTRALIA Background: The aim of this study was to review the discrepancies in Gleason scores (GS) of prostate biopsies and radical prostatectomy specimens and the effects of multiple-needle biopsies on scoring accuracy. Methods: One hundred patients who had undergone consecutive radical prostatectomies (RP) between January 2004 and May 2006 were reviewed retrospectively. Patient information including age, prebiopsy prostate-specific antigen levels, biopsy GS, RP GS and pathology details were recorded and compared. Results: The concordance rate of biopsy GS and RP GS was found to be at 43%, with 46% of biopsy specimens being undergraded. Eleven per cent of the specimens were overgraded. The accuracy was fairly similar when specimens were reported by the same or different pathologists, at 42 and 44%, respectively. The accuracy of biopsy GS improved with increasing number of biopsies taken. Conclusion: There are significant discrepancies in Gleason scoring of biopsy and RP specimens, with a concordance rate of 43% and undergrading rate of 46%. Increasing the number of biopsies helps improve scoring accuracy. Clinicians and patients need to be mindful when deciding cancer treatment options, in view of these discrepancies. [source] HP36P DOES NEO-ADJUVANT CHEMOTHERAPY AFFECT THE ACCURACY OF HELICAL CT AND CT PORTOGRAPHY FOR PRE-OPERATIVE PLANNING IN HEPATIC COLORECTAL METASTASES?ANZ JOURNAL OF SURGERY, Issue 2007S. Adie Purpose Pre-operative scanning for hepatic colorectal metastases surgery remains a challenge, especially in the age of neo-adjuvant chemo, which has marked biochemical & physical effects on the liver. We investigated helical CT and CT portography as pre-op planning tools. Methodology All patients who had resection of hepatic colorectal metastases between Jan 2004 and June 2006 were included. Patients were divided into those who received neo-adjuvant chemo and those who did not. The number of malignant hepatic lesions found on each scan was compared with those found on histopathology & intra-op ultrasound/examination. Accurate scans (scan lesions = true lesions), over-estimations (scan lesions > true lesions) and under-estimations (scan lesions < true lesions) were recorded. Results 25 patients had pre-op CT portography with neo-adjuvant chemo and 63 without. Accurate scans on a per-patient basis were 2 (8%) for the chemo group vs. 27 (43%) for the non-chemo group, p < 0.002. Notably, there were 17 (68%) over-estimates in the chemo group vs. 25 (40%) in the non-chemo group. There were 6 (24%) vs. 11 (17%) under-estimates respectively. 23 patients had pre-op helical CT with neo-adjuvant chemo and 64 without. Accurate scans on a per-patient basis were 7 (30%) for the chemo group vs. 26 (41%) in the non-chemo group, p = 0.388. There were 8 (35%) over-estimates in the chemo group vs. 12 (19%) in the non-chemo group. There were 8 (35%) vs. 26 (41%) under-estimates respectively. Conclusion While CT portography is useful for detecting occult hepatic metastases, there is evidence that over-estimation of disease is a problem, particularly when neo-adjuvant chemo was used. Helical CT also shows this trend although to a lesser extent. [source] ROUTES TO HIGHER-ORDER ACCURACY IN PARAMETRIC INFERENCEAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 2 2009G. Alastair Young Summary Developments in the theory of frequentist parametric inference in recent decades have been driven largely by the desire to achieve higher-order accuracy, in particular distributional approximations that improve on first-order asymptotic theory by one or two orders of magnitude. At the same time, much methodology is specifically designed to respect key principles of parametric inference, in particular conditionality principles. Two main routes to higher-order accuracy have emerged: analytic methods based on ,small-sample asymptotics', and simulation, or ,bootstrap', approaches. It is argued here that, of these, the simulation methodology provides a simple and effective approach, which nevertheless retains finer inferential components of theory. The paper seeks to track likely developments of parametric inference, in an era dominated by the emergence of methodological problems involving complex dependences and/or high-dimensional parameters that typically exceed available data sample sizes. [source] Head and neck cancer patients with pulmonary nodules: Value and role of CT-guided transthoracic needle aspiration biopsiesHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 11 2003Benoît Mesurolle MD Abstract Background. To evaluate transthoracic needle aspiration biopsies of pulmonary lesions in patients with squamous cell cancer of head and neck. Methods. Retrospective series of 85 patients with squamous cell cancer of head and neck cancer and pulmonary nodules who underwent CT-guided needle aspiration biopsy. Results. Diagnostic samples were obtained in 85% of patients. There were 8 benign and 77 malignant lesions. Among the 73 proved cases, 4 were false-negative cases. CT-guided biopsy had an accuracy of 81%, a sensitivity of 94%, and a negative predictive value of 60%. Accuracies were 68% for lesions of 20 mm or smaller and 89% for lesions greater than 20 mm. In a subset of 45 solitary lesions, among 30 positive biopsies, 15 were categorized as primary malignancies, 3 as metastatic, and 12 as indeterminate malignancies. Conclusions. In head and neck cancer patients, the prevalence of thoracic malignancies is high when a pulmonary lesion is detected. CT-guided biopsy of pulmonary lesion is an accurate procedure. However, a third of positive biopsies were categorized as indeterminate malignancies. © 2003 Wiley Periodicals, Inc. Head Neck 25: 000,000, 2003 [source] Brain temperature and pH measured by 1H chemical shift imaging of a thulium agentNMR IN BIOMEDICINE, Issue 2 2009Daniel Coman Abstract Temperature and pH are two of the most important physiological parameters and are believed to be tightly regulated because they are intricately related to energy metabolism in living organisms. Temperature and/or pH data in mammalian brain are scarce, however, mainly because of lack of precise and non-invasive methods. At 11.7,T, we demonstrate that a thulium-based macrocyclic complex infused through the bloodstream can be used to obtain temperature and pH maps of rat brain in vivo by 1H chemical shift imaging (CSI) of the sensor itself in conjunction with a multi-parametric model that depends on several proton resonances of the sensor. Accuracies of temperature and pH determination with the thulium sensor , which has a predominantly extracellular presence , depend on stable signals during the course of the CSI experiment as well as redundancy for temperature and pH sensitivities contained within the observed signals. The thulium-based method compared well with other methods for temperature (1H MRS of N -acetylaspartate and water; copper,constantan thermocouple wire) and pH (31P MRS of inorganic phosphate and phosphocreatine) assessment, as established by in vitro and in vivo studies. In vitro studies in phantoms with two compartments of different pH value observed under different ambient temperature conditions generated precise temperature and pH distribution maps. In vivo studies in , -chloralose-anesthetized and renal-ligated rats revealed temperature (33,34°C) and pH (7.3,7.4) distributions in the cerebral cortex that are in agreement with observations by other methods. These results show that the thulium sensor can be used to measure temperature and pH distributions in rat brain in vivo simultaneously and accurately with using biosensor imaging of redundant. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nuchal translucency measurement at different crown-rump lengths along the 10- to 14-week period for Down syndrome screeningPRENATAL DIAGNOSIS, Issue 5 2005Maria A. Zoppi Abstract Objectives To evaluate the screening accuracy for Down syndrome of nuchal translucency (NT) measurement at different crown-rump length (CRL) subgroups along the 10- to 14-week period. Methods NT was classified ,enlarged' if greater than or equal to 1.5 and 2.0 multiples of the regressed median. Accuracies for Down syndrome (formula = [(TP + TN)/(TP + TN + FP + FN)] × 100, where TP: true positive, TN: true negative, FP: false positive, FN: false negative) were evaluated in four classes of CRL: 38,44 mm, 45,54 mm, 55,70 mm, and 71,84 mm, and compared. Results Of 20 743 fetuses, 20 611 were with no chromosomal abnormalities and 132 were with Down syndrome. Down syndrome fetuses with enlarged NT were 99 (greater than or equal to 1.5 MoM) and 86 (greater than or equal to 2.0 MoM). Sensitivity decreased with gestation, while specificity increased, resulting in increasing likelihood ratios with gestation for each of the CRL groups (8.1, 14.1, 16.3, 17.1 with the use of the 1.5 MoM cut-off, and 13.2, 27.1, 50.1, 84.1 for the 2.0 MoM cut-off). The accuracy increased with gestation (89%, 95%, 95%, 96% with the use of the 1.5 MoM cut-off, and 94%, 97%, 98%, 99% for the 2.0 MoM cut-off, for each of the CRL groups), differences being statistically significant between periods in half of the comparisons. Conclusions Although sensitivity of NT assessment for Down syndrome screening decreased as gestation advanced from the 10th to the 14th week, accuracy showed a remarkable increase. These changes should be taken into account in defining and improving the Down syndrome screening policies. Copyright © 2005 John Wiley & Sons, Ltd. [source] Simultaneous quantification of 2,,2,-difluorodeoxycytidine and 2,,2,-difluorodeoxyuridine nucleosides and nucleotides in white blood cells using porous graphitic carbon chromatography coupled with tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2009Robert S. Jansen A novel assay for the simultaneous quantification of the widely used anticancer agent 2,,2,-difluorodeoxycytidine (gemcitabine; dFdC), its deaminated metabolite 2,,2,-difluorodeoxyuridine (dFdU) and their mono-, di- and triphosphates (dFdCMP, dFdCDP, dFdCTP, dFdUMP, dFdUDP and dFdUTP) in peripheral blood mononuclear cells (PBMCs) is described. Separation of all eight compounds was achieved within 15,min using a porous graphitic carbon column (Hypercarb) with a gradient from 0 to 25,mM ammonium bicarbonate in acetonitrile/water (15:85, v/v). Calibration ranges in PBMC lysate from 4.29 to 429, 29.0 to 2900, 31.4 to 3140 and 36.9 to 3690,nM for dFdC, dFdCMP, dFdCDP and dFdCTP and from 42.1 to 4210, 25.4 to 2540, 43.2 to 4320 and 52.7 to 5270,nM for dFdU, dFdUMP, dFdUDP and dFdUTP, respectively, were validated. Accuracies were within 82.3,119% at the lower limit of quantification (LLOQ) and the precisions were less than 20.0%. At the other tested levels accuracies were within 91.4,114% and precisions less than 14.9%. Mixtures of 13C,15N2 -labeled dFdC and dFdU nucleotides were synthesized and used as internal standards. Whole blood samples showed extensive ongoing dFdC metabolism when stored at room temperature, but not on ice-water, which made the addition of enzyme inhibitors unnecessary. Stock solutions and samples were stable under all analytically relevant conditions. The method was successfully applied to clinical samples. Copyright © 2009 John Wiley & Sons, Ltd. [source] Direct determination of endogenous melatonin in human saliva by column-switching semi-microcolumn liquid chromatography/mass spectrometry with on-line analyte enrichmentRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2004Akira Motoyama An analytical method that enables direct and sensitive determination of endogenous melatonin (MLT) in human saliva was developed by means of column-switching semi-microcolumn liquid chromatography (i.d.: 1,2,mm)/mass spectrometry (LC/MS). The system allows direct injection analysis of a 400-,L aliquot of saliva with minimal sample pretreatment (internal standard (IS) addition and vortex mixing) and a relatively short run-time (10,min). The system consists of three columns to attain large volume injection and on-line analyte enrichment. A pre-column packed with a silica-based mixed-functional C8 (4.0,mm i.d.,×,20,mm) was used for on-line sample cleanup. MLT and an IS, the d7 isomer of MLT (d7-MLT), were heart-cut by valve switching and enriched at the top of the intermediate trapping column packed with a silica-based C18 (4.0,mm i.d.,×,10,mm). Subsequently, the analytes were backflushed into a semi-micro C18 silica column (2.0,mm i.d.,×,150 mm) for the final separation. MLT and IS were ascertained by positive electrospray ionization and selected ion monitoring (SIM). MLT was monitored based on its fragment ion at m/z 174.1 by in-source collision-induced dissociation (CID). The validation of this method revealed a detection limit of 2.5,pg,mL,1 at a signal-to-noise (S/N) ratio of 5. The linearity of the method was established in the ranges 5,250 and 100,2500,pg,mL,1 with a coefficient of determination of greater than 0.998. Accuracies, evaluated at five levels in the range 5,1000,pg,mL,1, were between 81 and 108% with a relative standard deviation (RSD) ranging from 1.3,20%. The method was successfully applied for the endogenous saliva MLT monitoring of two healthy subjects. Copyright © 2004 John Wiley & Sons, Ltd. [source] Viscosity models for New Zealand black liquor at low solids concentrationsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010S.B. Alabi Abstract Availability of accurate models for prediction of the viscosity of black liquor (BL) from the chemical pulping of pine will facilitate its online monitoring and control and subsequently the optimisation of combustion in a recovery boiler. New Zealand (NZ) BL viscosity data are limited, and no predictive model is available. The viscosities of the NZ BL samples at solids concentrations (SCs) < 50% were obtained at temperature of 25,85 °C and shear rate up to ,2000 s,1. The samples showed Newtonian behaviour. Existing models from the literature and a binomial model developed in this work were used to fit the viscosity data as a function of SC and temperature. Accuracies of these models were examined for both the log-transformed and the untransformed viscosity data using coefficient of correlation (R) and maximum absolute relative error (MARE) (between the actual and predicted viscosities), respectively, as indices. Although the existing models fit NZ BL viscosity data well when they were log-transformed, they performed poorly when not transformed. Conversely, the new binomial model gave accurate predictions with both the log-transformed and untransformed viscosity data (R = 0.9997; MARE = 5.7%). It is concluded that at low SCs, the viscosity of Newtonian BL can be accurately predicted using the new binomial model. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Simultaneous determination of peimine and peiminine in rat plasma by LC-ESI-MS employing solid-phase extractionBIOMEDICAL CHROMATOGRAPHY, Issue 8 2010Xiaodan Wu Abstract A simple and reliable LC-ESI-MS method for the determination of peimine and peiminine in rat plasma was developed for the first time. The method was proven to be specific and sensitive by carrying out validation. The analytes were extracted from rat plasma via solid-phase extraction on Waters Oasis MCX cartridges. Chromatography separation was achieved on a C18 column using 10,mM ammonium acetate (adjusted to pH 3.0 with glacial acetic acid),acetonitrile (85:15, v/v) as mobile phase. The linear range was 1,100,ng/mL for peimine and peiminine. Intra- and inter-day precisiond were less than 10%. Accuracies were within 85,115% of their nominal concentrations. The limit of quantification was 1,ng/mL for both analytes. The developed assay was successfully applied to pharmacokinetic study of peimine and peiminine in rats orally administered the alkaloids extracts from Bulbus Fritillariae, demonstrating a possible broader spectrum of applications of this method. Copyright © 2009 John Wiley & Sons, Ltd. [source] Time-Adaptive Lines for the Interactive Visualization of Unsteady Flow Data SetsCOMPUTER GRAPHICS FORUM, Issue 8 2009N. Cuntz I.3.3 [Computer Graphics]: Line and Curve Generation; I.3.1 [Computer Graphics]: Parallel Processing Abstract The quest for the ideal flow visualization reveals two major challenges: interactivity and accuracy. Interactivity stands for explorative capabilities and real-time control. Accuracy is a prerequisite for every professional visualization in order to provide a reliable base for analysis of a data set. Geometric flow visualization has a long tradition and comes in very different flavors. Among these, stream, path and streak lines are known to be very useful for both 2D and 3D flows. Despite their importance in practice, appropriate algorithms suited for contemporary hardware are rare. In particular, the adaptive construction of the different line types is not sufficiently studied. This study provides a profound representation and discussion of stream, path and streak lines. Two algorithms are proposed for efficiently and accurately generating these lines using modern graphics hardware. Each includes a scheme for adaptive time-stepping. The adaptivity for stream and path lines is achieved through a new processing idea we call ,selective transform feedback'. The adaptivity for streak lines combines adaptive time-stepping and a geometric refinement of the curve itself. Our visualization is applied, among others, to a data set representing a simulated typhoon. The storage as a set of 3D textures requires special attention. Both algorithms explicitly support this storage, as well as the use of precomputed adaptivity information. [source] Single-beat estimation of the left ventricular end-systolic pressure,volume relationship in patients with heart failureACTA PHYSIOLOGICA, Issue 1 2010E. A. Ten Brinke Abstract Aim:, The end-systolic pressure,volume relationship (ESPVR) constructed from multiple pressure,volume (PV) loops acquired during load intervention is an established method to asses left ventricular (LV) contractility. We tested the accuracy of simplified single-beat (SB) ESPVR estimation in patients with severe heart failure. Methods:, Nineteen heart failure patients (NYHA III-IV) scheduled for surgical ventricular restoration and/or restrictive mitral annuloplasty and 12 patients with normal LV function scheduled for coronary artery bypass grafting were included. PV signals were obtained before and after cardiac surgery by pressure-conductance catheters and gradual pre-load reductions by vena cava occlusion (VCO). The SB method was applied to the first beat of the VCO run. Accuracy was quantified by the root-mean-square-error (RMSE) between ESPVRSB and gold-standard ESPVRVCO. In addition, we compared slopes (EES) and intercepts (end-systolic volume at multiple pressure levels (70,100 mmHg: ESV70,ESV100) of ESPVRSB vs. ESPVRVCO by Bland,Altman analyses. Results:, RMSE was 1.7 ± 1.0 mmHg and was not significantly different between groups and not dependent on end-diastolic volume, indicating equal, high accuracy over a wide volume range. SB-predicted EES had a bias of ,0.39 mmHg mL,1 and limits of agreement (LoA) ,2.0 to +1.2 mmHg mL,1. SB-predicted ESVs at each pressure level showed small bias (range: ,10.8 to +9.4 mL) and narrow LoA. Two-way anova indicated that differences between groups were not dependent on the method. Conclusion:, Our findings, obtained in hearts spanning a wide range of sizes and conditions, support the use of the SB method. This method ultimately facilitates less invasive ESPVR estimation, particularly when coupled with emerging noninvasive techniques to measure LV pressures and volumes. [source] Accuracy of Relative Weights on Multiple Leading Performance Measures: Effects on Managerial Performance and Knowledge,CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2010KHIM KELLY First page of article [source] Auditor Quality and the Accuracy of Management Earnings Forecasts,CONTEMPORARY ACCOUNTING RESEARCH, Issue 4 2000PETER M. CLARKSON Abstract In this study, we appeal to insights and results from Davidson and Neu 1993 and McConomy 1998 to motivate empirical analyses designed to gain a better understanding of the relationship between auditor quality and forecast accuracy. We extend and refine Davidson and Neu's analysis of this relationship by introducing additional controls for business risk and by considering data from two distinct time periods: one in which the audit firm's responsibility respecting the earnings forecast was to provide review-level assurance, and one in which its responsibility was to provide audit-level assurance. Our sample data consist of Toronto Stock Exchange (TSE) initial public offerings (IPOs). The earnings forecast we consider is the one-year-ahead management earnings forecast included in the IPO offering prospectus. The results suggest that after the additional controls for business risk are introduced, the relationship between forecast accuracy and auditor quality for the review-level assurance period is no longer significant. The results also indicate that the shift in regimes alters the fundamental nature of the relationship. Using data from the audit-level assurance regime, we find a negative and significant relationship between forecast accuracy and auditor quality (i.e., we find Big 6 auditors to be associated with smaller absolute forecast errors than non-Big 6 auditors), and further, that the difference in the relationship between the two regimes is statistically significant. [source] Diagnosis of Nonmelanoma Skin Cancer/Keratinocyte Carcinoma: A Review of Diagnostic Accuracy of Nonmelanoma Skin Cancer Diagnostic Tests and TechnologiesDERMATOLOGIC SURGERY, Issue 10 2007METTE MOGENSEN MD BACKGROUND Nonmelanoma skin cancer (NMSC) is the most prevalent cancer in the light-skinned population. Noninvasive treatment is increasingly used for NMSC patients with superficial lesions, making the development of noninvasive diagnostic technologies highly relevant. OBJECTIVE The scope of this review is to present data on the current state-of-the-art diagnostic methods for keratinocyte carcinoma: basal cell carcinoma, squamous cell carcinoma, and actinic keratosis. METHODS AND MATERIALS MEDLINE, BIOSIS, and EMBASE searches on NMSC and physical and clinical examination, biopsy, molecular marker, ultrasonography, Doppler, optical coherence tomography, dermoscopy, spectroscopy, fluorescence imaging, confocal microscopy, positron emission tomography, computed tomography, magnetic resonance imaging, terahertz imaging, electrical impedance and sensitivity, specificity, and diagnostic accuracy. RESULTS State-of-the-art diagnostic research has been limited in this field, but encouraging results from the reviewed diagnostic trials have suggested a high diagnostic accuracy for many of the technologies. Most of the studies, however, were pilot or small studies and the results would need to be validated in larger trials. CONCLUSIONS Some of these new imaging technologies have the capability of providing new, three-dimensional in vivo, in situ understanding of NMSC development over time. Some of the new technologies described here have the potential to make it from the bench to the clinic. [source] Detecting language problems: accuracy of five language screening instruments in preschool childrenDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2007H M E Van Agt MA To identify a simple and effective screening instrument for language delays in 3-year-old children the reliability, validity, and accuracy of five screening instruments were examined. A postal questionnaire sent to parents of 11423 children included the Dutch version of the General Language Screen (GLS), the Van Wiechen (VW) items, the Language Screening Instrument for 3- to 4-year-olds, consisting of a parent form (LSI-PF) and a child test (LSI-CT), and parents' own judgement of their child's language development on a visual analogue scale (VAS). The response rate was 78% or 8877 children. Reliability (internal consistency) was found to be acceptable (,=0.67,0.72) for all instruments. Significant correlations between the screening instruments (r=0.29,0.55, p<0.01) indicated good concurrent validity. Accuracy was estimated by the sensitivity, specificity, and receiver operating characteristic (ROC) curves against two reference tests based on parent report and specialists' judgement. If the test would classify approximately 5% of the population as screen-positive, the mean sensitivity was 50%; assigning between 20% and 30% of the population as screen-positive, the mean sensitivity was 77%. The sensitivity was lowest for the LSI-CT (range 43,62%), whereas short instruments like the LSI-PF, VW, and the one-item VAS exhibited high levels of sensitivity (range 50,86%). The area under the ROC curves, ranged from 0.75 to 0.87. Apparently, short and simple parent report instruments like the LSI-PF and the one-item VAS perform remarkably well in detecting language delays in preschool children. [source] Accuracy of lymph nodes cell block preparation according to ultrasound features in preoperative staging of breast cancerDIAGNOSTIC CYTOPATHOLOGY, Issue 1 2010Corinne Engohan-Aloghe M.D. Abstract To analyse the correlation between axillary ultrasonography (US), cell block (CBs) preparation, and histological diagnosis of lymph nodes from patients with primary breast cancer with the intention to assess the accuracy of cell block (CB) technique in preoperative staging. We tested a series of 26 patients who underwent axillary cell blocks from ultrasound guided fine-needle aspiration with histologic follow-up (axillary lymph nodes dissection). The specificity of axillary cell block was 100% vs. 14% for axillary ultrasound and the sensitivity was 73% for axillary cell block and 87% for axillary ultrasound. The positive and negative predictive values of cell block were respectively, 100 and 78%. Based on these results, we concluded that CB preparation was a feasible and specific technique to evaluate axillary lymph nodes status of patients with primary invasive breast cancer. Diagn. Cytopathol. 2010. © 2009 Wiley-Liss, Inc. [source] Immunocytochemical typing of primary tumors on fine-needle aspiration cytologies of lymph nodesDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2008Alexandre Sherlley Casimiro Onofre M.Sc. Abstract The aim of this study was to analyze the role of immunocytochemistry as an ancillary method on routine FNACs of enlarged lymph nodes, using different markers. In a validating cohort study all patients had confirmatory histological and/or clinical follow-up. 10 FNACs were analyzed for the differentiation of Non-Hodgkin Lymphoma (NHL) from metastatic carcinoma (MC), 30 cases to identify the sites of metastatic unknown primary tumors and 16 cases were checked to confirm clinical suspicion of a specific MC. Accuracy to differentiate NHL from MC was 100%, 92.3% to identify a primary tumor site of MC, and 100% to confirm a clinical suspicion of a specific MC. In 7 cases, the site of the primary tumor remained clinically unknown. Application of immunocytochemical markers on the same slide used for microscopic diagnosis is a useful tool in the routine assessment of FNACs of lymph nodes. Diagn. Cytopathol. 2008;36:207,215. © 2008 Wiley-Liss, Inc. [source] Solid renal masses in adults: Image-guided fine-needle aspiration cytology and imaging techniques,"Two Heads Better Than One?"DIAGNOSTIC CYTOPATHOLOGY, Issue 1 2008José García-Solano M.D. Abstract We have compared the diagnostic accuracy of image-guided 25G-FNA (fine-needle aspiration) and imaging modalities in a group of 31 patients with solid space-occupying renal lesions. All patients had undergone total nephrectomy and histologic sections were available for review. By FNA there were 24 malignant diagnoses, I benign diagnosis, and 6 cases with yield inadequate for diagnosis. The FNA accuracy for malignancy was 100% with no false positive cases; cancer typing by FNA matched the final histologic diagnoses in 91.6% of cases. Sensitivity, specificity, positive predictive value, and negative predictive value were 80%, 14%, 80%, and 14%, respectively. Radiologically there were 26 diagnoses of malignancy, I of benignity, and 4 indeterminate lesions (IL). Accuracy for malignancy was 100%, with one false positive case; cancer typing matched the final histologic diagnoses in 84%. Sensitivity of imaging modalities was 86%, specificity 17%, positive predictive value 83%, and negative predictive value 20%. Four IL corresponded to renal cell carcinoma in the final histologic report: two IL had a previous diagnosis of malignancy by FNA, and the yield of two was inadequate for cytologic diagnosis. Both techniques have 100% accuracy for the diagnosis of malignancy. The sensitivity, specificity, positive predictive value, and negative predictive value of imaging techniques are slightly higher than those obtained by FNA. Imaging techniques and FNA of solid renal masses complement each other in IL and in nondiagnostic FNAs. Diagn. Cytopathol. 2008;36:8,12. © 2007 Wiley-Liss, Inc. [source] Diagnostic Accuracy of Handheld Echocardiography for Evaluation of Aortic StenosisECHOCARDIOGRAPHY, Issue 5 2010Arnd Schaefer M.D. Background: Symptomatic severe aortic stenosis is associated with increased mortality and morbidity. Early identification of these patients by echocardiography is crucial. We conducted this study to evaluate a handheld ultrasound device (HCU) in patients with suspected severe aortic stenosis (AS) in comparison to a standard echocardiography device (SE). Methods: A HCU (Vivid I; GE Healthcare) and a SE device (Philips iE 33) were used to evaluate 50 consecutive patients with suspected severe AS. Two consecutive echocardiographic studies were performed by two experienced and blinded examiners using HCU and SE device. AS was graded by mean transaortic pressure, aortic valve area (AVA), and indexed AVA (AVA adjusted for body surface area). Results: Mean difference for mean transaortic gradient, AVA and indexed AVA for the SE and HCU device were 1.28 mmHg (,0.70 to 3.26 mmHg), ,0.02 cm2 (,0.06 to 0.01 cm2), and ,0.01 cm2/m2 (,0.03 to 0.01 cm2/m2), respectively. Discrepancies between both devices were not associated with misinterpretation of the degree of AS. Conclusion: Our study demonstrates that HCU can be used to evaluate patients with suspected AS. (ECHOCARDIOGRAPHY 2010;27:481-486) [source] Impact of Valvular Calcification on the Diagnostic Accuracy of Transesophageal Echocardiography for the Detection of Congenital Aortic Valve MalformationECHOCARDIOGRAPHY, Issue 7 2007Akash Makkar M.D. Background: Degeneration of congenital bicuspid or unicuspid aortic valves can progress more rapidly than that of tricuspid valves, and an early diagnosis significantly impacts decision making and outcome. We hypothesized that the extent of valvular calcification would negatively influence the diagnostic accuracy of multiplane transesophageal echocardiography (TEE) for the diagnosis of congenital aortic valve disease. Methods: TEE was performed in 57 patients undergoing aortic valve replacement surgery for aortic stenosis (n = 46), pure regurgitation (n = 9), or significant regurgitation with less than severe aortic stenosis (n = 2). The degree of aortic valve calcification and the number of valve cusps were determined at surgery. Results: Surgical inspection confirmed 14 bicuspid and 43 tricuspid aortic valves. Sensitivity and specificity of TEE for the diagnosis of congenital aortic valve malformation was 93% (13/14) and 91% (39/43) (P = 0.0001), respectively. In patients with no or mild aortic valve calcification (n = 13), sensitivity and specificity of TEE for the diagnosis of congenitally malformed aortic valve was 100% (5/5) and 100% (8/8) (P = 0.001), respectively. In patients with moderate or marked aortic valve calcification (n = 44), sensitivity and specificity of TEE for the diagnosis of congenitally malformed aortic valve was 89% (8/9) and 89% (31/35) (P<0.0001), respectively. In this subgroup of 44 patients, there were four false-positive and one false-negative diagnoses due to valvular calcification. Conclusions: Although TEE is highly sensitive and specific for the detection of congenital aortic valve malformations, presence of moderate or marked calcification of the aortic valve may result in false positive and false negative diagnoses. [source] Echocardiographic Assessment of Left Ventricular Mass in Neonatal and Adult Mice: Accuracy of Different Echocardiographic MethodsECHOCARDIOGRAPHY, Issue 10 2006Alexander Ghanem M.D. Echocardiography is an established method to estimate left-ventricular mass (LVM) in mice. Accuracy is determined by cardiac size and morphology and influenced by mathematical models. We investigated accuracy of three common algorithms in three early developmental stages. High-resolution echocardiography was performed in 35 C57/BL6-mice. Therefore, two-dimensional-guided M-mode echocardiography and parasternal short- and long-axis views in B-mode were obtained. LVM was assessed in vivo applying Penn (P), Area Length (AL), and Truncated Ellipsoid (TE) algorithms and validated with histomorphometry. Regression analysis of all mice showed fair estimation of LVM assessed with M-mode-based Penn algorithm (y = 0.6*x , 0.12, r: 0.71). In contrast two-dimensional assessment of LVM revealed close linear relationship with histomorphometry (yAL= 1.21*x , 12.1, r: 0.88, yTE= 1.38*x , 2.88, r: 0.86). Bias was lowest for LVM-AL at diastole underestimating 3.2%. In concordance with the summarized data, LVM-P revealed lower regression coefficients and significant underestimation in all three subgroups. Small hearts (<50 mg, n = 12) correlated best with LVM-AL at systole. Hearts of adolescent (50,75 mg, n = 13) and adult (75,100 mg, n = 10) mice revealed close linear relationship with LVM-AL and LVM-TE at diastole. Echocardiographic assessment of LVM is feasible in hearts weighting less than 50 mg and can be estimated best in systole. Hearts weighting more than 50 mg are estimated most accurately by means of LVM-AL at diastole. [source] Accuracy of Tissue Doppler Echocardiography in the Diagnosis of New-Onset Congestive Heart Failure in Patients with Levels of B-Type Natriuretic Peptide in the Midrange and Normal Left Ventricular Ejection FractionECHOCARDIOGRAPHY, Issue 8 2006Stephane Arques M.D. Background: Based on the hypothesis that it reflects left ventricular (LV) diastolic pressures, B-type natriuretic peptide (BNP) is largely utilized as first-line diagnostic complement in the emergency diagnosis of congestive heart failure (HF). The incremental diagnostic value of tissue Doppler echocardiography, a reliable noninvasive estimate of LV filling pressures, has been reported in patients with preserved LV ejection fraction and discrepancy between BNP levels and the clinical judgment, however, its clinical validity in such patients in the presence of BNP concentrations in the midrange, which may reflect intermediate, nondiagnostic levels of LV filling pressures, is unknown. Methods: 34 patients without history of HF, presenting with acute dyspnea at rest, BNP levels of 100,400 pg/ml and normal LV ejection fraction were prospectively enrolled (17 with congestive HF and 17 with noncardiac cause). Tissue Doppler echocardiography was performed within 3 hours after admission. Results: unlike BNP (P = 0.78), Boston criteria (P = 0.0129), radiographic pulmonary edema (P = 0.0036) and average E/Ea ratio (P = 0.0032) were predictive of congestive HF by logistic regression analysis. In this clinical setting, radiographic pulmonary edema had a positive predictive value of 80% in the diagnosis of congestive HF. In patients without evidence of radiographic pulmonary edema, average E/Ea > 10 was a powerful predictor of congestive HF (area under the ROC curve of 0.886, P < 0.001, sensitivity 100% and specificity 78.6%). Conclusion: by better reflecting LV filling pressures, bedside tissue Doppler echocardiography accurately differentiates congestive HF from noncardiac cause in dyspneic patients with intermediate, nondiagnostic BNP levels and normal LV ejection fraction. [source] The significance of overlapping plant range to a putative adaptive trade-off in the black bean aphid Aphis fabae ScopECOLOGICAL ENTOMOLOGY, Issue 4 2004C. R. Tosh Abstract., 1. This study continues to explore the analysis of a putative adaptive trade-off in the utilisation of host plants Vicia faba and Tropaeolum majus by the aphid, Aphis fabae. These plants are utilised exclusively by the subspecies Aphis fabae fabae and A. f. mordwilkoi respectively, and this plant-use system has been studied previously as a potential source of disruptive selection. 2. Here the potential of these two host plants to generate disruptive selection is considered given common utilisation of the abundant host plant, Rumex obtusifolius, by both subspecies. 3. The life history of subspecific clones is quantified in the laboratory on V. faba, T. majus, and R. obtusifolius at various temperatures and used to parameterise a temperature-driven simulation model of aphid population development. 4. Accuracy of the model is tested using a field experiment, and fitness of clones on specific and common host is simulated using temperature data from a number of English sites. 5. The model gives a close quantitative fit to field data and makes the following predictions: performance of A. f. fabae is higher on the specific host than the common host under all tested thermal regimes; and performance of A. f. mordwilkoi is superior on the specific host in warm years but inferior in cold years. 6. Given the great abundance of R. obtusifolius relative to T. majus, the model predicts that the plant utilisation system has little potential to consistently promote hybrid dysfunction. This adds further weight to the assertion that the plant utilisation system studied can offer little insight into the evolutionary processes involved in subspecific differentiation and probably contains a host plant/host plants acquired after the evolution of reproductive barriers. [source] A Three-step Method for Choosing the Number of Bootstrap RepetitionsECONOMETRICA, Issue 1 2000Donald W. K. Andrews This paper considers the problem of choosing the number of bootstrap repetitions B for bootstrap standard errors, confidence intervals, confidence regions, hypothesis tests, p -values, and bias correction. For each of these problems, the paper provides a three-step method for choosing B to achieve a desired level of accuracy. Accuracy is measured by the percentage deviation of the bootstrap standard error estimate, confidence interval length, test's critical value, test's p -value, or bias-corrected estimate based on B bootstrap simulations from the corresponding ideal bootstrap quantities for which B=,. The results apply quite generally to parametric, semiparametric, and nonparametric models with independent and dependent data. The results apply to the standard nonparametric iid bootstrap, moving block bootstraps for time series data, parametric and semiparametric bootstraps, and bootstraps for regression models based on bootstrapping residuals. Monte Carlo simulations show that the proposed methods work very well. [source] Is Teaching Experience Necessary for Reliable Scoring of Extended English Questions?EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 2 2009Lucy Royal-Dawson Hundreds of thousands of raters are recruited internationally to score examinations, but little research has been conducted on the selection criteria for these raters. Many countries insist upon teaching experience as a selection criterion and this has frequently become embedded in the cultural expectations surrounding the tests. Shortages in raters for some of England's national examinations has led to non-teachers being hired to score a small minority of items and changes in technology have fostered this approach. For a National Curriculum test in English taken at age 14, this study investigated whether teaching experience was a necessary selection criterion for all aspects of the examination. Fifty-seven raters with different backgrounds were trained in the normal manner and scored the same 97 students' work. Accuracy was investigated using a cross-classified multilevel model of absolute score differences with accuracy measures at level 1 and raters crossed with candidates at level 2. By comparing the scoring accuracy of graduates with a degree in English, teacher trainees, experienced teachers and experienced raters, this study found that teaching experience was not a necessary selection criterion. A rudimentary model for allocation of raters to different question types is proposed and further research to investigate the limits of necessary qualifications for scoring is suggested. [source] Voltammetric Determination of ,-Tocopheryl Acetate in Pharmaceutical Dosage FormsELECTROANALYSIS, Issue 11 2004Slawomir Michalkiewicz Abstract A simple and rapid voltammetric method has been developed for the quantitative determination of ,-tocopheryl acetate (,-TOAc) in pharmaceutical preparations. Studies with linear scan (LSV), square-wave (SQWV) and differential pulse voltammetry (DPV) were carried out using platinum microelectrodes. A well-defined, irreversible oxidation wave/peak was obtained at 1.30,V (vs. Ag/AgCl reference electrode.) The use of SQWV or DPV technique provides a precise determination of ,-tocopheryl acetate using the multiple standard addition method. The statistical parameters and the recovery study data clearly indicate good reproducibility and accuracy of the method. Accuracy of the results assessed by recovery trials was found within the 99.3% to 103.5%, and 99.1% to 101.4%, for SQWV and DPV, respectively. The quantification limits for the both voltammetric techniques were found to be 6×10,5,M (SQWV) and 7×10,5,M (DPV). Analysis of the authentic samples containing ,-TOAc showed no interference with common additives and excipients, such as unsaturated fatty acids (co-formulated as glycerine esters) and vitamin A (as retinol or ,-carotene). The method proposed does not require any pretreatment of the pharmaceutical dosage forms. A gas chromatography determination of ,-TOAc in real samples was also performed for comparison. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||