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Sample records for accuracy studies quadas

  1. Does the Reporting Quality of Diagnostic Test Accuracy Studies, as Defined by STARD 2015, Affect Citation?

    PubMed Central

    Choi, Young Jun; Chung, Mi Sun; Koo, Hyun Jung; Park, Ji Eun; Yoon, Hee Mang

    2016-01-01

    Objective To determine the rate with which diagnostic test accuracy studies that are published in a general radiology journal adhere to the Standards for Reporting of Diagnostic Accuracy Studies (STARD) 2015, and to explore the relationship between adherence rate and citation rate while avoiding confounding by journal factors. Materials and Methods All eligible diagnostic test accuracy studies that were published in the Korean Journal of Radiology in 2011–2015 were identified. Five reviewers assessed each article for yes/no compliance with 27 of the 30 STARD 2015 checklist items (items 28, 29, and 30 were excluded). The total STARD score (number of fulfilled STARD items) was calculated. The score of the 15 STARD items that related directly to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 was also calculated. The number of times each article was cited (as indicated by the Web of Science) after publication until March 2016 and the article exposure time (time in months between publication and March 2016) were extracted. Results Sixty-three articles were analyzed. The mean (range) total and QUADAS-2-related STARD scores were 20.0 (14.5–25) and 11.4 (7–15), respectively. The mean citation number was 4 (0–21). Citation number did not associate significantly with either STARD score after accounting for exposure time (total score: correlation coefficient = 0.154, p = 0.232; QUADAS-2-related score: correlation coefficient = 0.143, p = 0.266). Conclusion The degree of adherence to STARD 2015 was moderate for this journal, indicating that there is room for improvement. When adjusted for exposure time, the degree of adherence did not affect the citation rate. PMID:27587959

  2. EOS mapping accuracy study

    NASA Technical Reports Server (NTRS)

    Forrest, R. B.; Eppes, T. A.; Ouellette, R. J.

    1973-01-01

    Studies were performed to evaluate various image positioning methods for possible use in the earth observatory satellite (EOS) program and other earth resource imaging satellite programs. The primary goal is the generation of geometrically corrected and registered images, positioned with respect to the earth's surface. The EOS sensors which were considered were the thematic mapper, the return beam vidicon camera, and the high resolution pointable imager. The image positioning methods evaluated consisted of various combinations of satellite data and ground control points. It was concluded that EOS attitude control system design must be considered as a part of the image positioning problem for EOS, along with image sensor design and ground image processing system design. Study results show that, with suitable efficiency for ground control point selection and matching activities during data processing, extensive reliance should be placed on use of ground control points for positioning the images obtained from EOS and similar programs.

  3. Data Accuracy in Citation Studies.

    ERIC Educational Resources Information Center

    Boyce, Bert R.; Banning, Carolyn Sue

    1979-01-01

    Four hundred eighty-seven citations of the 1976 issues of the Journal of the American Society for Information Science and the Personnel and Guidance Journal were checked for accuracy: total error was 13.6 percent and 10.7 percent, respectively. Error categories included incorrect author name, article/book title, journal title; wrong entry; and…

  4. In vivo confocal microscopy of basal cell carcinoma: a systematic review of diagnostic accuracy.

    PubMed

    Kadouch, D J; Schram, M E; Leeflang, M M; Limpens, J; Spuls, P I; de Rie, M A

    2015-10-01

    Basal cell carcinoma (BCC) is the most prevalent type of skin cancer. Histologic analysis of punch biopsy or direct excision specimen is used to confirm clinical diagnosis. In vivo reflectance confocal microscopy (RCM) is a non-invasive imaging modality that could facilitate early diagnosis and minimize unnecessary invasive procedures. We systematically reviewed diagnostic accuracy (sensitivity and specificity) of RCM in diagnosing primary BCCs to judge its usefulness. Eligible studies were reviewed for methodological quality using the QUADAS-2 tool. We used the bivariate random-effects model to calculate summary estimates of sensitivity and specificity. Six studies met the selection criteria and were included for analysis. The meta-analysis showed a summary estimate of sensitivity 0.97 (95% CI, 0.90-0.99) and specificity 0.93 (95% CI, 0.88-0.96). All but one of the QUADAS-2 items showed a high or unclear risk of bias with regards to patient selection. RCM may be a promising diagnostic tool, but the limited number of available studies and potential risk of bias of included studies do not allow us to draw firm conclusions. Future accuracy studies should take these limitations into account. PMID:26290493

  5. Systematic review of accuracy of prenatal diagnosis for abnormal chromosome diseases by microarray technology.

    PubMed

    Xu, H B; Yang, H; Liu, G; Chen, H

    2014-10-31

    The accuracy of prenatal diagnosis for abnormal chromosome diseases by chromosome microarray technology and karyotyping were compared. A literature search was carried out in the MEDLINE database with the keywords "chromosome" and "karyotype" and "genetic testing" and "prenatal diagnosis" and "oligonucleotide array sequence". The studies obtained were filtered by using the QUADAS tool, and studies conforming to the quality standard were fully analyzed. There was one paper conforming to the QUADAS standards including 4406 gravidas with adaptability syndromes of prenatal diagnosis including elderly parturient women, abnormal structure by type-B ultrasound, and other abnormalities. Microarray technology yielded successful diagnoses in 4340 cases (98.8%), and there was no need for tissue culture in 87.9% of the samples. All aneuploids and non-parallel translocations in 4282 cases of non-chimera identified by karyotyping could be detected using microarray analysis technology, whereas parallel translocations and fetal triploids could not be detected by microarray analysis technology. In the samples with normal karyotyping results, type-B ultrasound showed that 6% of chromosomal deficiencies or chromosome duplications could be detected by microarray technology, and the same abnormal chromosomes were detected in 1.7% of elderly parturient women and samples with positive serology screening results. In the prenatal diagnosis test, compared with karyotyping, microarray technology could identify the extra cell genetic information with clinical significance, aneuploids, and non-parallel translocations; however, its disadvantage is that it could not identify parallel translocations and triploids.

  6. Air traffic control surveillance accuracy and update rate study

    NASA Technical Reports Server (NTRS)

    Craigie, J. H.; Morrison, D. D.; Zipper, I.

    1973-01-01

    The results of an air traffic control surveillance accuracy and update rate study are presented. The objective of the study was to establish quantitative relationships between the surveillance accuracies, update rates, and the communication load associated with the tactical control of aircraft for conflict resolution. The relationships are established for typical types of aircraft, phases of flight, and types of airspace. Specific cases are analyzed to determine the surveillance accuracies and update rates required to prevent two aircraft from approaching each other too closely.

  7. A study of laseruler accuracy and precision (1986-1987)

    SciTech Connect

    Ramachandran, R.S.; Armstrong, K.P.

    1989-06-22

    A study was conducted to investigate Laserruler accuracy and precision. Tests were performed on 0.050 in., 0.100 in., and 0.120 in. gauge block standards. Results showed and accuracy of 3.7 {mu}in. for the 0.12 in. standard, with higher accuracies for the two thinner blocks. The Laserruler precision was 4.83 {mu}in. for the 0.120 in. standard, 3.83 {mu}in. for the 0.100 in. standard, and 4.2 {mu}in. for the 0.050 in. standard.

  8. Diagnostic accuracy of the clinical feeding evaluation in detecting aspiration in children: a systematic review.

    PubMed

    Calvo, Irene; Conway, Aifric; Henriques, Filipa; Walshe, Margaret

    2016-06-01

    The aim of this systematic review is to determine the diagnostic accuracy of clinical feeding evaluation (CFE) compared to instrumental assessments in detecting oropharyngeal aspiration (OPA) in children. This is important to support clinical decision-making and to provide safe, cost-effective, higher quality care. All published and unpublished studies in all languages assessing the diagnostic accuracy of CFE compared to videofluoroscopic swallowing study (VFSS) and/or fibre-optic endoscopic examination of swallowing (FEES) in detecting OPA in paediatric populations were sought. Databases were searched from inception to April 2015. Grey literature, citations, and references were also searched. Two independent reviewers extracted and analysed data. Accuracy estimates were calculated. Research reports were translated into English as required. Six studies examining the diagnostic accuracy of CFE using VFSS and/or FEES were eligible for inclusion. Sample sizes, populations studied, and CFE characteristics varied widely. The overall methodological quality of the studies, assessed with QUADAS-2, was considered 'low'. Results suggested that CFEs trialling liquid consistencies might provide better accuracy estimates than CFEs trialling solids exclusively. This systematic review highlights the critical lack of evidence on the accuracy of CFE in detecting OPA in children. Larger well-designed primary diagnostic test accuracy studies in this area are needed to inform dysphagia assessment in paediatrics. PMID:26862075

  9. The methodological quality of three foundational law enforcement drug influence evaluation validation studies

    PubMed Central

    2013-01-01

    Background A Drug Influence Evaluation (DIE) is a formal assessment of an impaired driving suspect, performed by a trained law enforcement officer who uses circumstantial facts, questioning, searching, and a physical exam to form an unstandardized opinion as to whether a suspect’s driving was impaired by drugs. This paper first identifies the scientific studies commonly cited in American criminal trials as evidence of DIE accuracy, and second, uses the QUADAS tool to investigate whether the methodologies used by these studies allow them to correctly quantify the diagnostic accuracy of the DIEs currently administered by US law enforcement. Results Three studies were selected for analysis. For each study, the QUADAS tool identified biases that distorted reported accuracies. The studies were subject to spectrum bias, selection bias, misclassification bias, verification bias, differential verification bias, incorporation bias, and review bias. The studies quantified DIE performance with prevalence-dependent accuracy statistics that are internally but not externally valid. Conclusion The accuracies reported by these studies do not quantify the accuracy of the DIE process now used by US law enforcement. These studies do not validate current DIE practice. PMID:24188398

  10. Accuracy study of the IDO scheme by Fourier analysis

    NASA Astrophysics Data System (ADS)

    Imai, Yohsuke; Aoki, Takayuki

    2006-09-01

    The numerical accuracy of the Interpolated Differential Operator (IDO) scheme is studied with Fourier analysis for the solutions of Partial Differential Equations (PDEs): advection, diffusion, and Poisson equations. The IDO scheme solves governing equations not only for physical variable but also for first-order spatial derivative. Spatial discretizations are based on Hermite interpolation functions with both of them. In the Fourier analysis for the IDO scheme, the Fourier coefficients of the physical variable and the first-order derivative are coupled by the equations derived from the governing equations. The analysis shows the IDO scheme resolves all the wavenumbers with higher accuracy than the fourth-order Finite Difference (FD) and Compact Difference (CD) schemes for advection equation. In particular, for high wavenumbers, the accuracy is superior to that of the sixth-order Combined Compact Difference (CCD) scheme. The diffusion and Poisson equations are also more accurately solved in comparison with the FD and CD schemes. These results show that the IDO scheme guarantees highly resolved solutions for all the terms of fluid flow equations.

  11. Bias due to composite reference standards in diagnostic accuracy studies.

    PubMed

    Schiller, Ian; van Smeden, Maarten; Hadgu, Alula; Libman, Michael; Reitsma, Johannes B; Dendukuri, Nandini

    2016-04-30

    Composite reference standards (CRSs) have been advocated in diagnostic accuracy studies in the absence of a perfect reference standard. The rationale is that combining results of multiple imperfect tests leads to a more accurate reference than any one test in isolation. Focusing on a CRS that classifies subjects as disease positive if at least one component test is positive, we derive algebraic expressions for sensitivity and specificity of this CRS, sensitivity and specificity of a new (index) test compared with this CRS, as well as the CRS-based prevalence. We use as a motivating example the problem of evaluating a new test for Chlamydia trachomatis, an asymptomatic disease for which no gold-standard test exists. As the number of component tests increases, sensitivity of this CRS increases at the expense specificity, unless all tests have perfect specificity. Therefore, such a CRS can lead to significantly biased accuracy estimates of the index test. The bias depends on disease prevalence and accuracy of the CRS. Further, conditional dependence between the CRS and index test can lead to over-estimation of index test accuracy estimates. This commonly-used CRS combines results from multiple imperfect tests in a way that ignores information and therefore is not guaranteed to improve over a single imperfect reference unless each component test has perfect specificity, and the CRS is conditionally independent of the index test. When these conditions are not met, as in the case of C. trachomatis testing, more realistic statistical models should be researched instead of relying on such CRSs.

  12. High-accuracy mass spectrometry for fundamental studies.

    PubMed

    Kluge, H-Jürgen

    2010-01-01

    Mass spectrometry for fundamental studies in metrology and atomic, nuclear and particle physics requires extreme sensitivity and efficiency as well as ultimate resolving power and accuracy. An overview will be given on the global status of high-accuracy mass spectrometry for fundamental physics and metrology. Three quite different examples of modern mass spectrometric experiments in physics are presented: (i) the retardation spectrometer KATRIN at the Forschungszentrum Karlsruhe, employing electrostatic filtering in combination with magnetic-adiabatic collimation-the biggest mass spectrometer for determining the smallest mass, i.e. the mass of the electron anti-neutrino, (ii) the Experimental Cooler-Storage Ring at GSI-a mass spectrometer of medium size, relative to other accelerators, for determining medium-heavy masses and (iii) the Penning trap facility, SHIPTRAP, at GSI-the smallest mass spectrometer for determining the heaviest masses, those of super-heavy elements. Finally, a short view into the future will address the GSI project HITRAP at GSI for fundamental studies with highly-charged ions.

  13. Cadastral Positioning Accuracy Improvement: a Case Study in Malaysia

    NASA Astrophysics Data System (ADS)

    Hashim, N. M.; Omar, A. H.; Omar, K. M.; Abdullah, N. M.; Yatim, M. H. M.

    2016-09-01

    Cadastral map is a parcel-based information which is specifically designed to define the limitation of boundaries. In Malaysia, the cadastral map is under authority of the Department of Surveying and Mapping Malaysia (DSMM). With the growth of spatial based technology especially Geographical Information System (GIS), DSMM decided to modernize and reform its cadastral legacy datasets by generating an accurate digital based representation of cadastral parcels. These legacy databases usually are derived from paper parcel maps known as certified plan. The cadastral modernization will result in the new cadastral database no longer being based on single and static parcel paper maps, but on a global digital map. Despite the strict process of the cadastral modernization, this reform has raised unexpected queries that remain essential to be addressed. The main focus of this study is to review the issues that have been generated by this transition. The transformed cadastral database should be additionally treated to minimize inherent errors and to fit them to the new satellite based coordinate system with high positional accuracy. This review result will be applied as a foundation for investigation to study the systematic and effectiveness method for Positional Accuracy Improvement (PAI) in cadastral database modernization.

  14. High-accuracy mass spectrometry for fundamental studies.

    PubMed

    Kluge, H-Jürgen

    2010-01-01

    Mass spectrometry for fundamental studies in metrology and atomic, nuclear and particle physics requires extreme sensitivity and efficiency as well as ultimate resolving power and accuracy. An overview will be given on the global status of high-accuracy mass spectrometry for fundamental physics and metrology. Three quite different examples of modern mass spectrometric experiments in physics are presented: (i) the retardation spectrometer KATRIN at the Forschungszentrum Karlsruhe, employing electrostatic filtering in combination with magnetic-adiabatic collimation-the biggest mass spectrometer for determining the smallest mass, i.e. the mass of the electron anti-neutrino, (ii) the Experimental Cooler-Storage Ring at GSI-a mass spectrometer of medium size, relative to other accelerators, for determining medium-heavy masses and (iii) the Penning trap facility, SHIPTRAP, at GSI-the smallest mass spectrometer for determining the heaviest masses, those of super-heavy elements. Finally, a short view into the future will address the GSI project HITRAP at GSI for fundamental studies with highly-charged ions. PMID:20530821

  15. Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review

    PubMed Central

    Green, Hefziba; Steinmetz, Tali; Leibovici, Leonard; Paul, Mical

    2015-01-01

    The diagnosis of Legionnaires' disease (LD) is based on the isolation of Legionella spp., a 4-fold rise in antibodies, a positive urinary antigen (UA), or direct immunofluorescence tests. PCR is not accepted as a diagnostic tool for LD. This systematic review assesses the diagnostic accuracy of PCR in various clinical samples with a direct comparison versus UA. We included prospective or retrospective cohort and case-control studies. Studies were included if they used the Centers for Disease Control and Prevention consensus definition criteria of LD or a similar one, assessed only patients with clinical pneumonia, and reported data for all true-positive, false-positive, true-negative, and false-negative results. Two reviewers abstracted data independently. Risk of bias was assessed using Quadas-2. Summary sensitivity and specificity values were estimated using a bivariate model and reported with a 95% confidence interval (CI). Thirty-eight studies were included. A total of 653 patients had confirmed LD, and 3,593 patients had pneumonia due to other pathogens. The methodological quality of the studies as assessed by the Quadas-2 tool was poor to fair. The summary sensitivity and specificity values for diagnosis of LD in respiratory samples were 97.4% (95% CI, 91.1% to 99.2%) and 98.6% (95% CI, 97.4% to 99.3%), respectively. These results were mainly unchanged by any covariates tested and subgroup analysis. The diagnostic performance of PCR in respiratory samples was much better than that of UA. Compared to UA, PCR in respiratory samples (especially in sputum samples or swabs) revealed a significant advantage in sensitivity and an additional diagnosis of 18% to 30% of LD cases. The diagnostic performance of PCR in respiratory samples was excellent and preferable to that of the UA. Results were independent on the covariate tested. PCR in respiratory samples should be regarded as a valid tool for the diagnosis of LD. PMID:26659202

  16. Nonparametric meta-analysis for diagnostic accuracy studies.

    PubMed

    Zapf, Antonia; Hoyer, Annika; Kramer, Katharina; Kuss, Oliver

    2015-12-20

    Summarizing the information of many studies using a meta-analysis becomes more and more important, also in the field of diagnostic studies. The special challenge in meta-analysis of diagnostic accuracy studies is that in general sensitivity and specificity are co-primary endpoints. Across the studies both endpoints are correlated, and this correlation has to be considered in the analysis. The standard approach for such a meta-analysis is the bivariate logistic random effects model. An alternative approach is to use marginal beta-binomial distributions for the true positives and the true negatives, linked by copula distributions. In this article, we propose a new, nonparametric approach of analysis, which has greater flexibility with respect to the correlation structure, and always converges. In a simulation study, it becomes apparent that the empirical coverage of all three approaches is in general below the nominal level. Regarding bias, empirical coverage, and mean squared error the nonparametric model is often superior to the standard model, and comparable with the copula model. The three approaches are also applied to two example meta-analyses. PMID:26174020

  17. Alaska national hydrography dataset positional accuracy assessment study

    USGS Publications Warehouse

    Arundel, Samantha; Yamamoto, Kristina H.; Constance, Eric; Mantey, Kim; Vinyard-Houx, Jeremy

    2013-01-01

    Initial visual assessments Wide range in the quality of fit between features in NHD and these new image sources. No statistical analysis has been performed to actually quantify accuracy Determining absolute accuracy is cost prohibitive (must collect independent, well defined test points) Quantitative analysis of relative positional error is feasible.

  18. Reporting standards for studies of diagnostic test accuracy in dementia

    PubMed Central

    Noel-Storr, Anna H.; McCleery, Jenny M.; Richard, Edo; Ritchie, Craig W.; Flicker, Leon; Cullum, Sarah J.; Davis, Daniel; Quinn, Terence J.; Hyde, Chris; Rutjes, Anne W.S.; Smailagic, Nadja; Marcus, Sue; Black, Sandra; Blennow, Kaj; Brayne, Carol; Fiorivanti, Mario; Johnson, Julene K.; Köpke, Sascha; Schneider, Lon S.; Simmons, Andrew; Mattsson, Niklas; Zetterberg, Henrik; Bossuyt, Patrick M.M.; Wilcock, Gordon

    2014-01-01

    Objective: To provide guidance on standards for reporting studies of diagnostic test accuracy for dementia disorders. Methods: An international consensus process on reporting standards in dementia and cognitive impairment (STARDdem) was established, focusing on studies presenting data from which sensitivity and specificity were reported or could be derived. A working group led the initiative through 4 rounds of consensus work, using a modified Delphi process and culminating in a face-to-face consensus meeting in October 2012. The aim of this process was to agree on how best to supplement the generic standards of the STARD statement to enhance their utility and encourage their use in dementia research. Results: More than 200 comments were received during the wider consultation rounds. The areas at most risk of inadequate reporting were identified and a set of dementia-specific recommendations to supplement the STARD guidance were developed, including better reporting of patient selection, the reference standard used, avoidance of circularity, and reporting of test-retest reliability. Conclusion: STARDdem is an implementation of the STARD statement in which the original checklist is elaborated and supplemented with guidance pertinent to studies of cognitive disorders. Its adoption is expected to increase transparency, enable more effective evaluation of diagnostic tests in Alzheimer disease and dementia, contribute to greater adherence to methodologic standards, and advance the development of Alzheimer biomarkers. PMID:24944261

  19. A hyperspectral imager for high radiometric accuracy Earth climate studies

    NASA Astrophysics Data System (ADS)

    Espejo, Joey; Drake, Ginger; Heuerman, Karl; Kopp, Greg; Lieber, Alex; Smith, Paul; Vermeer, Bill

    2011-10-01

    We demonstrate a visible and near-infrared prototype pushbroom hyperspectral imager for Earth climate studies that is capable of using direct solar viewing for on-orbit cross calibration and degradation tracking. Direct calibration to solar spectral irradiances allow the Earth-viewing instrument to achieve required climate-driven absolute radiometric accuracies of <0.2% (1σ). A solar calibration requires viewing scenes having radiances 105 higher than typical Earth scenes. To facilitate this calibration, the instrument features an attenuation system that uses an optimized combination of different precision aperture sizes, neutral density filters, and variable integration timing for Earth and solar viewing. The optical system consists of a three-mirror anastigmat telescope and an Offner spectrometer. The as-built system has a 12.2° cross track field of view with 3 arcmin spatial resolution and covers a 350-1050 nm spectral range with 10 nm resolution. A polarization compensated configuration using the Offner in an out of plane alignment is demonstrated as a viable approach to minimizing polarization sensitivity. The mechanical design takes advantage of relaxed tolerances in the optical design by using rigid, non-adjustable diamond-turned tabs for optical mount locating surfaces. We show that this approach achieves the required optical performance. A prototype spaceflight unit is also demonstrated to prove the applicability of these solar cross calibration methods to on-orbit environments. This unit is evaluated for optical performance prior to and after GEVS shake, thermal vacuum, and lifecycle tests.

  20. Diagnostic Accuracy of Molecular Amplification Tests for Human African Trypanosomiasis—Systematic Review

    PubMed Central

    Boer, Kimberly R.; Dyserinck, Heleen C.; Büscher, Philippe; Schallig, Henk D. H. F.; Leeflang, Mariska M. G.

    2012-01-01

    Background A range of molecular amplification techniques have been developed for the diagnosis of Human African Trypanosomiasis (HAT); however, careful evaluation of these tests must precede implementation to ensure their high clinical accuracy. Here, we investigated the diagnostic accuracy of molecular amplification tests for HAT, the quality of articles and reasons for variation in accuracy. Methodology Data from studies assessing diagnostic molecular amplification tests were extracted and pooled to calculate accuracy. Articles were included if they reported sensitivity and specificity or data whereby values could be calculated. Study quality was assessed using QUADAS and selected studies were analysed using the bivariate random effects model. Results 16 articles evaluating molecular amplification tests fulfilled the inclusion criteria: PCR (n = 12), NASBA (n = 2), LAMP (n = 1) and a study comparing PCR and NASBA (n = 1). Fourteen articles, including 19 different studies were included in the meta-analysis. Summary sensitivity for PCR on blood was 99.0% (95% CI 92.8 to 99.9) and the specificity was 97.7% (95% CI 93.0 to 99.3). Differences in study design and readout method did not significantly change estimates although use of satellite DNA as a target significantly lowers specificity. Sensitivity and specificity of PCR on CSF for staging varied from 87.6% to 100%, and 55.6% to 82.9% respectively. Conclusion Here, PCR seems to have sufficient accuracy to replace microscopy where facilities allow, although this conclusion is based on multiple reference standards and a patient population that was not always representative. Future studies should, therefore, include patients for which PCR may become the test of choice and consider well designed diagnostic accuracy studies to provide extra evidence on the value of PCR in practice. Another use of PCR for control of disease could be to screen samples collected from rural areas and test in reference

  1. Accuracy of optical dental digitizers: an in vitro study.

    PubMed

    Vandeweghe, Stefan; Vervack, Valentin; Vanhove, Christian; Dierens, Melissa; Jimbo, Ryo; De Bruyn, Hugo

    2015-01-01

    The aim of this study was to evaluate the accuracy, in terms of trueness and precision, of optical dental scanners. An experimental acrylic resin cast was created and digitized using a microcomputed tomography (microCT) scanner, which served as the reference model. Five polyether impressions were made of the acrylic resin cast to create five stone casts. Each dental digitizer (Imetric, Lava ST, Smart Optics, KaVo Everest) made five scans of the acrylic resin cast and one scan of every stone cast. The scans were superimposed and compared using metrology software. Deviations were calculated between the datasets obtained from the dental digitizers and the microCT scanner (= trueness) and between datasets from the same dental digitizer (= precision). With exception of the Smart Optics scanner, there were no significant differences in trueness for the acrylic resin cast. For the stone casts, however, the Lava ST performed better than Imetric, which did better than the KaVo scanner. The Smart Optics scanner demonstrated the highest deviation. All digitizers demonstrated a significantly higher trueness for the acrylic resin cast compared to the plaster cast, except the Lava ST. The Lava ST was significantly more precise compared to the other scanners. Imetric and Smart Optics also demonstrated a higher level of precision compared to the KaVo scanner. All digitizers demonstrated some degree of error. Stone cast copies are less accurate because of difficulties with scanning the rougher surface or dimensional deformations caused during the production process. For complex, large-span reconstructions, a highly accurate scanner should be selected. PMID:25734714

  2. Accuracy Study of a 2-Component Point Doppler Velocimeter (PDV)

    NASA Technical Reports Server (NTRS)

    Kuhlman, John; Naylor, Steve; James, Kelly; Ramanath, Senthil

    1997-01-01

    A two-component Point Doppler Velocimeter (PDV) which has recently been developed is described, and a series of velocity measurements which have been obtained to quantify the accuracy of the PDV system are summarized. This PDV system uses molecular iodine vapor cells as frequency discriminating filters to determine the Doppler shift of laser light which is scattered off of seed particles in a flow. The majority of results which have been obtained to date are for the mean velocity of a rotating wheel, although preliminary data are described for fully-developed turbulent pipe flow. Accuracy of the present wheel velocity data is approximately +/- 1 % of full scale, while linearity of a single channel is on the order of +/- 0.5 % (i.e., +/- 0.6 m/sec and +/- 0.3 m/sec, out of 57 m/sec, respectively). The observed linearity of these results is on the order of the accuracy to which the speed of the rotating wheel has been set for individual data readings. The absolute accuracy of the rotating wheel data is shown to be consistent with the level of repeatability of the cell calibrations. The preliminary turbulent pipe flow data show consistent turbulence intensity values, and mean axial velocity profiles generally agree with pitot probe data. However, there is at present an offset error in the radial velocity which is on the order of 5-10 % of the mean axial velocity.

  3. Study of accuracy of precipitation measurements using simulation method

    NASA Astrophysics Data System (ADS)

    Nagy, Zoltán; Lajos, Tamás; Morvai, Krisztián

    2013-04-01

    Hungarian Meteorological Service1 Budapest University of Technology and Economics2 Precipitation is one of the the most important meteorological parameters describing the state of the climate and to get correct information from trends, accurate measurements of precipitation is very important. The problem is that the precipitation measurements are affected by systematic errors leading to an underestimation of actual precipitation which errors vary by type of precipitaion and gauge type. It is well known that the wind speed is the most important enviromental factor that contributes to the underestimation of actual precipitation, especially for solid precipitation. To study and correct the errors of precipitation measurements there are two basic possibilities: · Use of results and conclusion of International Precipitation Measurements Intercomparisons; · To build standard reference gauges (DFIR, pit gauge) and make own investigation; In 1999 at the HMS we tried to achieve own investigation and built standard reference gauges But the cost-benefit ratio in case of snow (use of DFIR) was very bad (we had several winters without significant amount of snow, while the state of DFIR was continously falling) Due to the problem mentioned above there was need for new approximation that was the modelling made by Budapest University of Technology and Economics, Department of Fluid Mechanics using the FLUENT 6.2 model. The ANSYS Fluent package is featured fluid dynamics solution for modelling flow and other related physical phenomena. It provides the tools needed to describe atmospheric processes, design and optimize new equipment. The CFD package includes solvers that accurately simulate behaviour of the broad range of flows that from single-phase to multi-phase. The questions we wanted to get answer to are as follows: · How do the different types of gauges deform the airflow around themselves? · Try to give quantitative estimation of wind induced error. · How does the use

  4. Accuracy of urea breath test in Helicobacter pylori infection: Meta-analysis

    PubMed Central

    Ferwana, Mazen; Abdulmajeed, Imad; Alhajiahmed, Ali; Madani, Wedad; Firwana, Belal; Hasan, Rim; Altayar, Osama; Limburg, Paul J; Murad, Mohammad Hassan; Knawy, Bandar

    2015-01-01

    AIM: To quantitatively summarize and appraise the available evidence of urea breath test (UBT) use to diagnose Helicobacter pylori (H. pylori) infection in patients with dyspepsia and provide pooled diagnostic accuracy measures. METHODS: We searched MEDLINE, EMBASE, Cochrane library and other databases for studies addressing the value of UBT in the diagnosis of H. pylori infection. We included cross-sectional studies that evaluated the diagnostic accuracy of UBT in adult patients with dyspeptic symptoms. Risk of bias was assessed using QUADAS (Quality Assessment of Diagnostic Accuracy Studies)-2 tool. Diagnostic accuracy measures were pooled using the random-effects model. Subgroup analysis was conducted by UBT type (13C vs 14C) and by measurement technique (Infrared spectrometry vs Isotope Ratio Mass Spectrometry). RESULTS: Out of 1380 studies identified, only 23 met the eligibility criteria. Fourteen studies (61%) evaluated 13C UBT and 9 studies (39%) evaluated 14C UBT. There was significant variation in the type of reference standard tests used across studies.Pooled sensitivity was 0.96 (95%CI: 0.95-0.97) andpooled specificity was 0.93 (95%CI: 0.91-0.94). Likelihood ratio for a positive test was 12 and for a negative test was 0.05 with an area under thecurve of 0.985. Meta-analyses were associated with a significant statistical heterogeneity that remained unexplained after subgroup analysis. The included studies had a moderate risk of bias. CONCLUSION: UBT has high diagnostic accuracy for detecting H. pylori infection in patients with dyspepsia. The reliability of diagnostic meta-analytic estimates however is limited by significant heterogeneity. PMID:25632206

  5. Diagnostic accuracy of high resolution melting analysis for detection of KRAS mutations: a systematic review and meta-analysis.

    PubMed

    Liu, Yue-Ping; Wu, Hai-Yan; Yang, Xiang; Xu, Han-Qing; Chen, Dong; Huang, Qing; Fu, Wei-Ling

    2014-01-01

    Increasing evidence points to a negative correlation between KRAS mutations and patients' responses to anti-EGFR monoclonal antibody treatment. Therefore, patients must undergo KRAS mutation detection to be eligible for treatment. High resolution melting analysis (HRM) is gaining increasing attention in KRAS mutation detection. However, its accuracy has not been systematically evaluated. We conducted a meta-analysis of published articles, involving 13 articles with 1,520 samples, to assess its diagnostic accuracy compared with DNA sequencing. The quality of included articles was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tools. Random effects models were applied to analyze the performance of pooled characteristics. The overall sensitivity and specificity of HRM were 0.99 (95% confidence interval [CI]: 0.98-1.00) and 0.96 (95%CI: 0.94-0.97), respectively. The area under the summary receiver operating characteristic curve was 0.996. High sensitivity and specificity, less labor, rapid turn-around and the closed-tube format of HRM make it an attractive choice for rapid detection of KRAS mutations in clinical practice. The burden of DNA sequencing can be reduced dramatically by the implementation of HRM, but positive results still need to be sequenced for diagnostic confirmation. PMID:25515911

  6. Using Meta-Analysis to Inform the Design of Subsequent Studies of Diagnostic Test Accuracy

    ERIC Educational Resources Information Center

    Hinchliffe, Sally R.; Crowther, Michael J.; Phillips, Robert S.; Sutton, Alex J.

    2013-01-01

    An individual diagnostic accuracy study rarely provides enough information to make conclusive recommendations about the accuracy of a diagnostic test; particularly when the study is small. Meta-analysis methods provide a way of combining information from multiple studies, reducing uncertainty in the result and hopefully providing substantial…

  7. STARD 2015: An Updated List of Essential Items for Reporting Diagnostic Accuracy Studies.

    PubMed

    Bossuyt, Patrick M; Reitsma, Johannes B; Bruns, David E; Gatsonis, Constantine A; Glasziou, Paul P; Irwig, Les; Lijmer, Jeroen G; Moher, David; Rennie, Drummond; de Vet, Henrica C W; Kressel, Herbert Y; Rifai, Nader; Golub, Robert M; Altman, Douglas G; Hooft, Lotty; Korevaar, Daniël A; Cohen, Jérémie F

    2015-12-01

    Incomplete reporting has been identified as a major source of avoidable waste in biomedical research. Essential information is often not provided in study reports, impeding the identification, critical appraisal, and replication of studies. To improve the quality of reporting of diagnostic accuracy studies, the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement was developed. Here we present STARD 2015, an updated list of 30 essential items that should be included in every report of a diagnostic accuracy study. This update incorporates recent evidence about sources of bias and variability in diagnostic accuracy and is intended to facilitate the use of STARD. As such, STARD 2015 may help to improve completeness and transparency in reporting of diagnostic accuracy studies.

  8. STARD 2015: An Updated List of Essential Items for Reporting Diagnostic Accuracy Studies.

    PubMed

    Bossuyt, Patrick M; Reitsma, Johannes B; Bruns, David E; Gatsonis, Constantine A; Glasziou, Paul P; Irwig, Les; Lijmer, Jeroen G; Moher, David; Rennie, Drummond; de Vet, Henrica C W; Kressel, Herbert Y; Rifai, Nader; Golub, Robert M; Altman, Douglas G; Hooft, Lotty; Korevaar, Daniël A; Cohen, Jérémie F

    2015-12-01

    Incomplete reporting has been identified as a major source of avoidable waste in biomedical research. Essential information is often not provided in study reports, impeding the identification, critical appraisal, and replication of studies. To improve the quality of reporting of diagnostic accuracy studies, the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement was developed. Here we present STARD 2015, an updated list of 30 essential items that should be included in every report of a diagnostic accuracy study. This update incorporates recent evidence about sources of bias and variability in diagnostic accuracy and is intended to facilitate the use of STARD. As such, STARD 2015 may help to improve completeness and transparency in reporting of diagnostic accuracy studies. PMID:26510957

  9. STARD 2015: An Updated List of Essential Items for Reporting Diagnostic Accuracy Studies.

    PubMed

    Bossuyt, Patrick M; Reitsma, Johannes B; Bruns, David E; Gatsonis, Constantine A; Glasziou, Paul P; Irwig, Les; Lijmer, Jeroen G; Moher, David; Rennie, Drummond; de Vet, Henrica C W; Kressel, Herbert Y; Rifai, Nader; Golub, Robert M; Altman, Douglas G; Hooft, Lotty; Korevaar, Daniël A; Cohen, Jérémie F

    2015-12-01

    Incomplete reporting has been identified as a major source of avoidable waste in biomedical research. Essential information is often not provided in study reports, impeding the identification, critical appraisal, and replication of studies. To improve the quality of reporting of diagnostic accuracy studies, the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement was developed. Here we present STARD 2015, an updated list of 30 essential items that should be included in every report of a diagnostic accuracy study. This update incorporates recent evidence about sources of bias and variability in diagnostic accuracy and is intended to facilitate the use of STARD. As such, STARD 2015 may help to improve completeness and transparency in reporting of diagnostic accuracy studies. PMID:26509226

  10. Effects of Varying Feedback Accuracy on Task Acquisition: A Computerized Translational Study

    ERIC Educational Resources Information Center

    Hirst, Jason M.; DiGennaro Reed, Florence D.; Reed, Derek D.

    2013-01-01

    Research has shown that the accuracy of instructions influences responding immediately and under later conditions. The purpose of the present study was to extend this literature and use a translational approach to assess the short- and long-term effects of feedback accuracy on the acquisition of a task. Three levels of inaccurate feedback were…

  11. Dynamic Development of Complexity and Accuracy: A Case Study in Second Language Academic Writing

    ERIC Educational Resources Information Center

    Rosmawati

    2014-01-01

    This paper reports on the development of complexity and accuracy in English as a Second Language (ESL) academic writing. Although research into complexity and accuracy development in second language (L2) writing has been well established, few studies have assumed the multidimensionality of these two constructs (Norris & Ortega, 2009) or…

  12. Accuracy of clinical diagnosis in parkinsonism--a prospective study.

    PubMed

    Rajput, A H; Rozdilsky, B; Rajput, A

    1991-08-01

    Clinical diagnosis of Parkinson's syndrome (PS) is reasonably easy in most cases but the distinction between different variants of PS may be difficult in early cases. The correct diagnosis is not only important for counselling and management of patients but also in conducting pharmacological and epidemiological studies. There is very little critical literature on the pathological verification of the clinical diagnosis in PS. We report our 22 years experience to address that issue. Between 1968 and 1990, 65 PS patients came to autopsy. Complete data are available in 59 (M-50, F-19) cases. The initial diagnosis made by a qualified neurologist was idiopathic Parkinson's disease (IPD) in 43 cases. Of those 28 (65%) had Lewy body pathology. After a mean duration of 12 years the final diagnosis was IPD in 41 cases which was confirmed in 31 (76%). The IPD could not be clinically distinguished from cases with severe substantia nigra neuronal loss without inclusions or from those with neurofibrillary tangle inclusions and neuronal loss at the anatomical sites typically involved in IPD. All progressive supra-nuclear palsy, olivopontocerebellar atrophy, Jakob-Creutzfeldt's disease and the majority of the multiple system atrophy cases were diagnosed correctly during life. The correct clinical diagnosis in most non-IPD variants of PS was possible within 5 years of onset (range: 2 months to 18 years). We recommend that studies aimed at including only the IPD cases restrict the enrollment to those cases that have had PS motor manifestations for five years or longer duration. PMID:1913360

  13. Study on the accuracy factors of large-scale photogrammetry system

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Dong, Mingli; Lu, Naiguang

    2011-05-01

    In photogrammetry system, the Base-Distance Ratio, the Image Scale, and the Image Standard Error, which construct the network strength of the system, are the main accuracy factors. In this paper, the normal and convergent network configurations of the photogrammetry are studied and the Network Strength, which presents the strength and accuracy of the camera station network, is expressed with the accuracy factors mentioned above. In order to verify the validation of this expression, the large-scale 3D reference field is designed and used to test the effects of these accuracy factors. The experimental results show that the relationship between the accuracy and the factors is consistent with the expression. These conclusions will guide the photogrammetric work to reduce the system errors.

  14. Study on the accuracy factors of large-scale photogrammetry system

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Dong, Mingli; Lu, Naiguang

    2010-12-01

    In photogrammetry system, the Base-Distance Ratio, the Image Scale, and the Image Standard Error, which construct the network strength of the system, are the main accuracy factors. In this paper, the normal and convergent network configurations of the photogrammetry are studied and the Network Strength, which presents the strength and accuracy of the camera station network, is expressed with the accuracy factors mentioned above. In order to verify the validation of this expression, the large-scale 3D reference field is designed and used to test the effects of these accuracy factors. The experimental results show that the relationship between the accuracy and the factors is consistent with the expression. These conclusions will guide the photogrammetric work to reduce the system errors.

  15. Do knowledge, knowledge sources and reasoning skills affect the accuracy of nursing diagnoses? a randomised study

    PubMed Central

    2012-01-01

    Background This paper reports a study about the effect of knowledge sources, such as handbooks, an assessment format and a predefined record structure for diagnostic documentation, as well as the influence of knowledge, disposition toward critical thinking and reasoning skills, on the accuracy of nursing diagnoses. Knowledge sources can support nurses in deriving diagnoses. A nurse’s disposition toward critical thinking and reasoning skills is also thought to influence the accuracy of his or her nursing diagnoses. Method A randomised factorial design was used in 2008–2009 to determine the effect of knowledge sources. We used the following instruments to assess the influence of ready knowledge, disposition, and reasoning skills on the accuracy of diagnoses: (1) a knowledge inventory, (2) the California Critical Thinking Disposition Inventory, and (3) the Health Science Reasoning Test. Nurses (n = 249) were randomly assigned to one of four factorial groups, and were instructed to derive diagnoses based on an assessment interview with a simulated patient/actor. Results The use of a predefined record structure resulted in a significantly higher accuracy of nursing diagnoses. A regression analysis reveals that almost half of the variance in the accuracy of diagnoses is explained by the use of a predefined record structure, a nurse’s age and the reasoning skills of `deduction’ and `analysis’. Conclusions Improving nurses’ dispositions toward critical thinking and reasoning skills, and the use of a predefined record structure, improves accuracy of nursing diagnoses. PMID:22852577

  16. Non-parametric Evaluation of Biomarker Accuracy under Nested Case-control Studies

    PubMed Central

    Cai, Tianxi; Zheng, Yingye

    2012-01-01

    Summary To evaluate the clinical utility of new risk markers, a crucial step is to measure their predictive accuracy with prospective studies. However, it is often infeasible to obtain marker values for all study participants. The nested case-control (NCC) design is a useful cost-effective strategy for such settings. Under the NCC design, markers are only ascertained for cases and a fraction of controls sampled randomly from the risk sets. The outcome dependent sampling generates a complex data structure and therefore a challenge for analysis. Existing methods for analyzing NCC studies focus primarily on association measures. Here, we propose a class of non-parametric estimators for commonly used accuracy measures. We derived asymptotic expansions for accuracy estimators based on both finite population and Bernoulli sampling and established asymptotic equivalence between the two. Simulation results suggest that the proposed procedures perform well in finite samples. The new procedures were illustrated with data from the Framingham Offspring study. PMID:22844169

  17. Study the effect of gray component replacement level on reflectance spectra and color reproduction accuracy

    NASA Astrophysics Data System (ADS)

    Spiridonov, I.; Shopova, M.; Boeva, R.

    2013-03-01

    The aim of this study is investigation of gray component replacement (GCR) levels on reflectance spectrum for different overprints of the inks and color reproduction accuracy. The most commonly implemented method in practice for generation of achromatic composition is gray component replacement (GCR). The experiments in this study, have been performed in real production conditions with special test form generated by specialized software. The measuring of reflection spectrum of printed colors, gives a complete conception for the effect of different gray component replacement levels on color reproduction accuracy. For better data analyses and modeling of processes, we have calculated (converted) the CIEL*a*b* color coordinates from the reflection spectra data. The assessment of color accuracy by using different GCR amount has been made by calculation of color difference ΔE* ab. In addition for the specific printing conditions we have created ICC profiles with different GCR amounts. A comparison of the color gamuts has been performed. For a first time a methodology is implemented for examination and estimation of effect of GCR levels on color reproduction accuracy by studying a big number of colors in entire visible spectrum. Implementation in practice of the results achieved in this experiment, will lead to improved gray balance and better color accuracy. Another important effect of this research is reduction of financial costs of printing production by decreasing of ink consumption, indirect reduction of emissions during the manufacture of inks and facilitates the process of deinking during the recycling paper.

  18. Dynamics of Complexity and Accuracy: A Longitudinal Case Study of Advanced Untutored Development

    ERIC Educational Resources Information Center

    Polat, Brittany; Kim, Youjin

    2014-01-01

    This longitudinal case study follows a dynamic systems approach to investigate an under-studied research area in second language acquisition, the development of complexity and accuracy for an advanced untutored learner of English. Using the analytical tools of dynamic systems theory (Verspoor et al. 2011) within the framework of complexity,…

  19. Experimental studies of high-accuracy RFID localization with channel impairments

    NASA Astrophysics Data System (ADS)

    Pauls, Eric; Zhang, Yimin D.

    2015-05-01

    Radio frequency identification (RFID) systems present an incredibly cost-effective and easy-to-implement solution to close-range localization. One of the important applications of a passive RFID system is to determine the reader position through multilateration based on the estimated distances between the reader and multiple distributed reference tags obtained from, e.g., the received signal strength indicator (RSSI) readings. In practice, the achievable accuracy of passive RFID reader localization suffers from many factors, such as the distorted RSSI reading due to channel impairments in terms of the susceptibility to reader antenna patterns and multipath propagation. Previous studies have shown that the accuracy of passive RFID localization can be significantly improved by properly modeling and compensating for such channel impairments. The objective of this paper is to report experimental study results that validate the effectiveness of such approaches for high-accuracy RFID localization. We also examine a number of practical issues arising in the underlying problem that limit the accuracy of reader-tag distance measurements and, therefore, the estimated reader localization. These issues include the variations in tag radiation characteristics for similar tags, effects of tag orientations, and reader RSS quantization and measurement errors. As such, this paper reveals valuable insights of the issues and solutions toward achieving high-accuracy passive RFID localization.

  20. A study of neural network parameters for improvement in classification accuracy

    NASA Astrophysics Data System (ADS)

    Pathak, Avijit; Tiwari, K. C.

    2016-05-01

    Hyperspectral data due to large number of spectral bands facilitates discrimination between large numbers of classes in a data; however, the advantage afforded by the hyperspectral data often tends to get lost in the limitations of convection al classifier techniques. Artificial Neural Networks (ANN) in several studies has shown to outperform convection al classifiers, however; there are several issues with regard to selection of parameters for achieving best possible classification accuracy. Objectives of this study have been accordingly formulated to include an investigation of t he effect of various Neural Network parameters on the accuracy of hyperspectral image classification. AVIRIS Hyperspectral Indian Pine Test site 3 dataset acquiredin220 Bands on June 12, 1992 has been used in the stud y. Thereafter, maximal feature extraction technique of Principle component analysis (PCA) is used to reduce the dataset t o 10 bands preserving of 99.96% variance. The data contains 16 major classes of which 4 have been considered for ANN based classification. The parameters selected for the study are - number of hidden layers, hidden Nodes, training sample size, learning rate and learning momentum. Backpropagation method of learning is adopted. The overall accuracy of the network trained has been assessed using test sample size of 300 pixels. Although, the study throws up certain distinct ranges within which higher classification accuracies can be expected, however, no definite relationship could be identified between various ANN parameters under study.

  1. Effects of implant angulation, material selection, and impression technique on impression accuracy: a preliminary laboratory study.

    PubMed

    Rutkunas, Vygandas; Sveikata, Kestutis; Savickas, Raimondas

    2012-01-01

    The aim of this preliminary laboratory study was to evaluate the effects of 5- and 25-degree implant angulations in simulated clinical casts on an impression's accuracy when using different impression materials and tray selections. A convenience sample of each implant angulation group was selected for both open and closed trays in combination with one polyether and two polyvinyl siloxane impression materials. The influence of material and technique appeared to be significant for both 5- and 25-degree angulations (P < .05), and increased angulation tended to decrease impression accuracy. The open-tray technique was more accurate with highly nonaxially oriented implants for the small sample size investigated.

  2. A Study on the Effect of Input Parameters on Springback Prediction Accuracy

    NASA Astrophysics Data System (ADS)

    Han, Y. S.; Yang, W. H.; Choi, K. Y.; Kim, B. H.

    2011-08-01

    In this study, it is considered the input parameters in springback simulation affect factors to use member part by Taguchi's method into six-sigma tool on the basis of experiment for acquiring much more accurate springback prediction in Pamstamp2G. The best combination of input parameters for higher springback prediction accuracy is determined to the fender part as the one is applied for member part. The cracks and wrinkles in drawing and flanging operation must be removed for predicting the higher springback in accuracy. The compensation of springback on the basis of simulation is carried out. It is concluded that 95% of accuracy for springback prediction in dimension is secured as comparing with tryout panel.

  3. Early-Onset Neonatal Sepsis: Still Room for Improvement in Procalcitonin Diagnostic Accuracy Studies.

    PubMed

    Chiesa, Claudio; Pacifico, Lucia; Osborn, John F; Bonci, Enea; Hofer, Nora; Resch, Bernhard

    2015-07-01

    To perform a systematic review assessing accuracy and completeness of diagnostic studies of procalcitonin (PCT) for early-onset neonatal sepsis (EONS) using the Standards for Reporting of Diagnostic Accuracy (STARD) initiative.EONS, diagnosed during the first 3 days of life, remains a common and serious problem. Increased PCT is a potentially useful diagnostic marker of EONS, but reports in the literature are contradictory. There are several possible explanations for the divergent results including the quality of studies reporting the clinical usefulness of PCT in ruling in or ruling out EONS.We systematically reviewed PubMed, Scopus, and the Cochrane Library databases up to October 1, 2014. Studies were eligible for inclusion in our review if they provided measures of PCT accuracy for diagnosing EONS. A data extraction form based on the STARD checklist and adapted for neonates with EONS was used to appraise the quality of the reporting of included studies.We found 18 articles (1998-2014) fulfilling our eligibility criteria which were included in the final analysis. Overall, the results of our analysis showed that the quality of studies reporting diagnostic accuracy of PCT for EONS was suboptimal leaving ample room for improvement. Information on key elements of design, analysis, and interpretation of test accuracy were frequently missing.Authors should be aware of the STARD criteria before starting a study in this field. We welcome stricter adherence to this guideline. Well-reported studies with appropriate designs will provide more reliable information to guide decisions on the use and interpretations of PCT test results in the management of neonates with EONS.

  4. Who Should Mark What? A Study of Factors Affecting Marking Accuracy in a Biology Examination

    ERIC Educational Resources Information Center

    Suto, Irenka; Nadas, Rita; Bell, John

    2011-01-01

    Accurate marking is crucial to the reliability and validity of public examinations, in England and internationally. Factors contributing to accuracy have been conceptualised as affecting either marking task demands or markers' personal expertise. The aim of this empirical study was to develop this conceptualisation through investigating the…

  5. Breaking the Code of Silence: A Study of Teachers' Nonverbal Decoding Accuracy of Foreign Language Anxiety

    ERIC Educational Resources Information Center

    Gregersen, Tammy

    2007-01-01

    This study examined teachers' accuracy in decoding nonverbal behaviour indicative of foreign language anxiety. Teachers and teacher trainees twice observed a videotape without sound of seven beginning French foreign language students as they participated in an oral exam; four of these students were defined as anxious language learners by the…

  6. Evaluating radiographers' diagnostic accuracy in screen-reading mammograms: what constitutes a quality study?

    SciTech Connect

    Debono, Josephine C; Poulos, Ann E

    2015-03-15

    The aim of this study was to first evaluate the quality of studies investigating the diagnostic accuracy of radiographers as mammogram screen-readers and then to develop an adapted tool for determining the quality of screen-reading studies. A literature search was used to identify relevant studies and a quality evaluation tool constructed by combining the criteria for quality of Whiting, Rutjes, Dinnes et al. and Brealey and Westwood. This constructed tool was then applied to the studies and subsequently adapted specifically for use in evaluating quality in studies investigating diagnostic accuracy of screen-readers. Eleven studies were identified and the constructed tool applied to evaluate quality. This evaluation resulted in the identification of quality issues with the studies such as potential for bias, applicability of results, study conduct, reporting of the study and observer characteristics. An assessment of the applicability and relevance of the tool for this area of research resulted in adaptations to the criteria and the development of a tool specifically for evaluating diagnostic accuracy in screen-reading. This tool, with further refinement and rigorous validation can make a significant contribution to promoting well-designed studies in this important area of research and practice.

  7. Comparative study of application accuracy of two frameless neuronavigation systems: experimental error assessment quantifying registration methods and clinically influencing factors.

    PubMed

    Paraskevopoulos, Dimitrios; Unterberg, Andreas; Metzner, Roland; Dreyhaupt, Jens; Eggers, Georg; Wirtz, Christian Rainer

    2010-04-01

    This study aimed at comparing the accuracy of two commercial neuronavigation systems. Error assessment and quantification of clinical factors and surface registration, often resulting in decreased accuracy, were intended. Active (Stryker Navigation) and passive (VectorVision Sky, BrainLAB) neuronavigation systems were tested with an anthropomorphic phantom with a deformable layer, simulating skin and soft tissue. True coordinates measured by computer numerical control were compared with coordinates on image data and during navigation, to calculate software and system accuracy respectively. Comparison of image and navigation coordinates was used to evaluate navigation accuracy. Both systems achieved an overall accuracy of <1.5 mm. Stryker achieved better software accuracy, whereas BrainLAB better system and navigation accuracy. Factors with conspicuous influence (P<0.01) were imaging, instrument replacement, sterile cover drape and geometry of instruments. Precision data indicated by the systems did not reflect measured accuracy in general. Surface matching resulted in no improvement of accuracy, confirming former studies. Laser registration showed no differences compared to conventional pointers. Differences between the two systems were limited. Surface registration may improve inaccurate point-based registrations but does not in general affect overall accuracy. Accuracy feedback by the systems does not always match with true target accuracy and requires critical evaluation from the surgeon.

  8. Studies of the accuracy of time integration methods for reaction-diffusion equations

    NASA Astrophysics Data System (ADS)

    Ropp, David L.; Shadid, John N.; Ober, Curtis C.

    2004-03-01

    In this study we present numerical experiments of time integration methods applied to systems of reaction-diffusion equations. Our main interest is in evaluating the relative accuracy and asymptotic order of accuracy of the methods on problems which exhibit an approximate balance between the competing component time scales. Nearly balanced systems can produce a significant coupling of the physical mechanisms and introduce a slow dynamical time scale of interest. These problems provide a challenging test for this evaluation and tend to reveal subtle differences between the various methods. The methods we consider include first- and second-order semi-implicit, fully implicit, and operator-splitting techniques. The test problems include a prototype propagating nonlinear reaction-diffusion wave, a non-equilibrium radiation-diffusion system, a Brusselator chemical dynamics system and a blow-up example. In this evaluation we demonstrate a "split personality" for the operator-splitting methods that we consider. While operator-splitting methods often obtain very good accuracy, they can also manifest a serious degradation in accuracy due to stability problems.

  9. Accuracy of bite mark analysis from food substances: A comparative study

    PubMed Central

    Daniel, M. Jonathan; Pazhani, Ambiga

    2015-01-01

    Aims and Objectives: The aims and objectives of the study were to compare the accuracy of bite mark analysis from three different food substances-apple, cheese and chocolate using two techniques-the manual docking procedure and computer assisted overlay generation technique and to compare the accuracy of the two techniques for bite mark analysis on food substances. Materials and Methods: The individuals who participated in the study were made to bite on three food substances-apple, cheese, and chocolate. Dentate individuals were included in the study. Edentulous individuals and individuals having a missing anterior tooth were excluded from the study. The dental casts of the individual were applied to the positive cast of the bitten food substance to determine docking or matching. Then, computer generated overlays were compared with bite mark pattern on the foodstuff. Results: The results were tabulated and the comparison of bite mark analysis on the three different food substances was analyzed by Kruskall-Wallis ANOVA test and the comparison of the two techniques was analyzed by Spearman's Rho correlation coefficient. Conclusion: On comparing the bite marks analysis from the three food substances-apple, cheese and chocolate, the accuracy was found to be greater for chocolate and cheese than apple. PMID:26816463

  10. Diagnostic accuracy of cytokeratin-19 fragment (CYFRA 21-1) for bladder cancer: a systematic review and meta-analysis.

    PubMed

    Huang, Yuan-Lan; Chen, Jie; Yan, Wei; Zang, Ding; Qin, Qin; Deng, An-Mei

    2015-05-01

    Previous studies have evaluated the accuracy of serum and urinary measurements of cytokeratin-19 fragment (CYFRA 21-1) for the diagnosis of bladder cancer; however, the results have been inconsistent. The aim of this study was to evaluate the overall accuracy of CYFRA 21-1 for the diagnosis of bladder cancer. We performed a search for English-language publications reporting on the detection of CYFRA21-1 levels for the diagnosis of bladder cancer through November 2, 2014, using public medical databases, including EMBASE, Web of Science, and Medline. The quality of the studies was assessed by revised QUADAS tools. The performance characteristics were pooled and analyzed using a bivariate model. Publication bias was explored with the Deek's test. Sixteen studies, with a total 1,262 bladder-cancer patients and 1,233 non-bladder-cancer patients, were included in the study. The pooled sensitivities for serum and urine CYFRA 21-1 were 0.42 (95 % confidence interval (CI), 0.33-0.51) and 0.82 (95 % CI, 0.70-0.90), respectively. The corresponding specificities were 0.94 (95 % CI, 0.90-0.96) and 0.80 (95 % CI, 0.73-0.86), respectively. The areas under the summary receiver-operating-characteristic curves for serum and urine CYFRA 21-1 were 0.88 (95 % CI, 0.85-0.91) and 0.87 (95 % CI, 0.84-0.90), respectively. The major design deficiencies of the included studies were participant-selection bias, potential review, and verification bias. Therefore, we concluded that both serum and urine CYFRA 21-1 served as efficient indexes for bladder-cancer diagnosis. Additional, well-designed studies should be performed to rigorously evaluate the diagnostic value of CYFRA 21-1 for bladder cancer. PMID:25854170

  11. Assessing the quality of studies on the diagnostic accuracy of tumor markers

    PubMed Central

    Goebell, Peter J.; Kamat, Ashish M.; Sylvester, Richard J.; Black, Peter; Droller, Michael; Godoy, Guilherme; Hudson, M’Liss A.; Junker, Kerstin; Kassouf, Wassim; Knowles, Margaret A.; Schulz, Wolfgang A.; Seiler, Roland; Schmitz-Dräger, Bernd J.

    2015-01-01

    Objectives With rapidly increasing numbers of publications, assessments of study quality, reporting quality, and classification of studies according to their level of evidence or developmental stage have become key issues in weighing the relevance of new information reported. Diagnostic marker studies are often criticized for yielding highly discrepant and even controversial results. Much of this discrepancy has been attributed to differences in study quality. So far, numerous tools for measuring study quality have been developed, but few of them have been used for systematic reviews and meta-analysis. This is owing to the fact that most tools are complicated and time consuming, suffer from poor reproducibility, and do not permit quantitative scoring. Methods The International Bladder Cancer Network (IBCN) has adopted this problem and has systematically identified the more commonly used tools developed since 2000. Results In this review, those tools addressing study quality (Quality Assessment of Studies of Diagnostic Accuracy and Newcastle-Ottawa Scale), reporting quality (Standards for Reporting of Diagnostic Accuracy), and developmental stage (IBCN phases) of studies on diagnostic markers in bladder cancer are introduced and critically analyzed. Based upon this, the IBCN has launched an initiative to assess and validate existing tools with emphasis on diagnostic bladder cancer studies. Conclusions The development of simple and reproducible tools for quality assessment of diagnostic marker studies permitting quantitative scoring is suggested. PMID:25159014

  12. Comparative study of dimensional accuracy of different impression techniques using addition silicone impression material.

    PubMed

    Penaflor, C F; Semacio, R C; De Las Alas, L T; Uy, H G

    1998-01-01

    This study compared dimensional accuracy of the single, double with spacer, double with cut-out and double mix impression technique using addition silicone impression material. A typhodont containing Ivorine teeth model with six (6) full-crown tooth preparations were used as the positive control. Two stone replication models for each impression technique were made as test materials. Accuracy of the techniques were assessed by measuring four dimensions on the stone dies poured from the impression of the Ivorine teeth model. Results indicated that most of the measurements for the height, width and diameter slightly decreased and a few increased compared with the Ivorine teeth model. The double with cut-out and double mix technique presents the least difference from the master model as compared to the two latter impression techniques. PMID:10202524

  13. Spectroscopic Accuracy in Quantum Chemistry: a Benchmark Study on Na_3

    NASA Astrophysics Data System (ADS)

    Hauser, Andreas W.; Pototschnig, Johann V.; Ernst, Wolfgang E.

    2015-06-01

    Modern techniques of quantum chemistry allow the prediction of molecular properties to good accuracy, provided the systems are small and their electronic structure is not too complex. For most users of common program packages, `chemical' accuracy in the order of a few kJ/mol for relative energies between different geometries is sufficient. The demands of molecular spectroscopists are typically much more stringent, and often include a detailed topographical survey of multi-dimensional potential energy surfaces with an accuracy in the range of wavenumbers. In a benchmark study of current predictive capabilities we pick the slightly sophisticated, but conceptually simple and well studied case of the Na_3 ground state, and present a thorough investigation of the interplay between Jahn-Teller-, spin-orbit-, rovibrational- and hyperfine-interactions based only on ab initio calculations. The necessary parameters for the effective Hamiltonian are derived from the potential energy surface of the 12E'{} ground state and from spin density evaluations at selected geometries, without any fitting adjustments to experimental data. We compare our results to highly resolved microwave spectra. L. H. Coudert, W. E. Ernst and O. Golonzka, J. Chem. Phys. 117, 7102-7116 (2002)

  14. High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

    PubMed

    Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2015-09-18

    High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%.

  15. High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

    PubMed

    Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

    2015-09-18

    High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%. PMID:26087881

  16. Simulation approach for the evaluation of tracking accuracy in radiotherapy: a preliminary study.

    PubMed

    Tanaka, Rie; Ichikawa, Katsuhiro; Mori, Shinichiro; Sanada, Sigeru

    2013-01-01

    Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). It is important to keep the patient dose as low as possible while maintaining tracking accuracy. A simulation approach would be helpful to optimize the imaging conditions. This study was performed to develop a computer simulation platform based on a noise property of the imaging system for the evaluation of tracking accuracy at any noise level. Flat-field images were obtained using a direct-type dynamic FPD, and noise power spectrum (NPS) analysis was performed. The relationship between incident quantum number and pixel value was addressed, and a conversion function was created. The pixel values were converted into a map of quantum number using the conversion function, and the map was then input into the random number generator to simulate image noise. Simulation images were provided at different noise levels by changing the incident quantum numbers. Subsequently, an implanted marker was tracked automatically and the maximum tracking errors were calculated at different noise levels. The results indicated that the maximum tracking error increased with decreasing incident quantum number in flat-field images with an implanted marker. In addition, the range of errors increased with decreasing incident quantum number. The present method could be used to determine the relationship between image noise and tracking accuracy. The results indicated that the simulation approach would aid in determining exposure dose conditions according to the necessary tracking accuracy. PMID:22843379

  17. Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.

    PubMed

    Sanders, Geoff; Sinclair, Kamila

    2011-12-01

    We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering.

  18. Results of a remote multiplexer/digitizer unit accuracy and environmental study

    NASA Technical Reports Server (NTRS)

    Wilner, D. O.

    1977-01-01

    A remote multiplexer/digitizer unit (RMDU), a part of the airborne integrated flight test data system, was subjected to an accuracy study. The study was designed to show the effects of temperature, altitude, and vibration on the RMDU. The RMDU was subjected to tests at temperatures from -54 C (-65 F) to 71 C (160 F), and the resulting data are presented here, along with a complete analysis of the effects. The methods and means used for obtaining correctable data and correcting the data are also discussed.

  19. The neglected tool in the Bayesian ecologist's shed: a case study testing informative priors' effect on model accuracy.

    PubMed

    Morris, William K; Vesk, Peter A; McCarthy, Michael A; Bunyavejchewin, Sarayudh; Baker, Patrick J

    2015-01-01

    Despite benefits for precision, ecologists rarely use informative priors. One reason that ecologists may prefer vague priors is the perception that informative priors reduce accuracy. To date, no ecological study has empirically evaluated data-derived informative priors' effects on precision and accuracy. To determine the impacts of priors, we evaluated mortality models for tree species using data from a forest dynamics plot in Thailand. Half the models used vague priors, and the remaining half had informative priors. We found precision was greater when using informative priors, but effects on accuracy were more variable. In some cases, prior information improved accuracy, while in others, it was reduced. On average, models with informative priors were no more or less accurate than models without. Our analyses provide a detailed case study on the simultaneous effect of prior information on precision and accuracy and demonstrate that when priors are specified appropriately, they lead to greater precision without systematically reducing model accuracy.

  20. Dimensional Accuracy of Hydrophilic and Hydrophobic VPS Impression Materials Using Different Impression Techniques - An Invitro Study

    PubMed Central

    Pilla, Ajai; Pathipaka, Suman

    2016-01-01

    Introduction The dimensional stability of the impression material could have an influence on the accuracy of the final restoration. Vinyl Polysiloxane Impression materials (VPS) are most frequently used as the impression material in fixed prosthodontics. As VPS is hydrophobic when it is poured with gypsum products, manufacturers added intrinsic surfactants and marketed as hydrophilic VPS. These hydrophilic VPS have shown increased wettability with gypsum slurries. VPS are available in different viscosities ranging from very low to very high for usage under different impression techniques. Aim To compare the dimensional accuracy of hydrophilic VPS and hydrophobic VPS using monophase, one step and two step putty wash impression techniques. Materials and Methods To test the dimensional accuracy of the impression materials a stainless steel die was fabricated as prescribed by ADA specification no. 19 for elastomeric impression materials. A total of 60 impressions were made. The materials were divided into two groups, Group1 hydrophilic VPS (Aquasil) and Group 2 hydrophobic VPS (Variotime). These were further divided into three subgroups A, B, C for monophase, one-step and two-step putty wash technique with 10 samples in each subgroup. The dimensional accuracy of the impressions was evaluated after 24 hours using vertical profile projector with lens magnification range of 20X-125X illumination. The study was analyzed through one-way ANOVA, post-hoc Tukey HSD test and unpaired t-test for mean comparison between groups. Results Results showed that the three different impression techniques (monophase, 1-step, 2-step putty wash techniques) did cause significant change in dimensional accuracy between hydrophilic VPS and hydrophobic VPS impression materials. One-way ANOVA disclosed, mean dimensional change and SD for hydrophilic VPS varied between 0.56% and 0.16%, which were low, suggesting hydrophilic VPS was satisfactory with all three impression techniques. However, mean

  1. Study on Increasing the Accuracy of Classification Based on Ant Colony algorithm

    NASA Astrophysics Data System (ADS)

    Yu, M.; Chen, D.-W.; Dai, C.-Y.; Li, Z.-L.

    2013-05-01

    The application for GIS advances the ability of data analysis on remote sensing image. The classification and distill of remote sensing image is the primary information source for GIS in LUCC application. How to increase the accuracy of classification is an important content of remote sensing research. Adding features and researching new classification methods are the ways to improve accuracy of classification. Ant colony algorithm based on mode framework defined, agents of the algorithms in nature-inspired computation field can show a kind of uniform intelligent computation mode. It is applied in remote sensing image classification is a new method of preliminary swarm intelligence. Studying the applicability of ant colony algorithm based on more features and exploring the advantages and performance of ant colony algorithm are provided with very important significance. The study takes the outskirts of Fuzhou with complicated land use in Fujian Province as study area. The multi-source database which contains the integration of spectral information (TM1-5, TM7, NDVI, NDBI) and topography characters (DEM, Slope, Aspect) and textural information (Mean, Variance, Homogeneity, Contrast, Dissimilarity, Entropy, Second Moment, Correlation) were built. Classification rules based different characters are discovered from the samples through ant colony algorithm and the classification test is performed based on these rules. At the same time, we compare with traditional maximum likelihood method, C4.5 algorithm and rough sets classifications for checking over the accuracies. The study showed that the accuracy of classification based on the ant colony algorithm is higher than other methods. In addition, the land use and cover changes in Fuzhou for the near term is studied and display the figures by using remote sensing technology based on ant colony algorithm. In addition, the land use and cover changes in Fuzhou for the near term is studied and display the figures by using

  2. The Eye Phone Study: reliability and accuracy of assessing Snellen visual acuity using smartphone technology

    PubMed Central

    Perera, C; Chakrabarti, R; Islam, F M A; Crowston, J

    2015-01-01

    Purpose Smartphone-based Snellen visual acuity charts has become popularized; however, their accuracy has not been established. This study aimed to evaluate the equivalence of a smartphone-based visual acuity chart with a standard 6-m Snellen visual acuity (6SVA) chart. Methods First, a review of available Snellen chart applications on iPhone was performed to determine the most accurate application based on optotype size. Subsequently, a prospective comparative study was performed by measuring conventional 6SVA and then iPhone visual acuity using the ‘Snellen' application on an Apple iPhone 4. Results Eleven applications were identified, with accuracy of optotype size ranging from 4.4–39.9%. Eighty-eight patients from general medical and surgical wards in a tertiary hospital took part in the second part of the study. The mean difference in logMAR visual acuity between the two charts was 0.02 logMAR (95% limit of agreement −0.332, 0.372 logMAR). The largest mean difference in logMAR acuity was noted in the subgroup of patients with 6SVA worse than 6/18 (n=5), who had a mean difference of two Snellen visual acuity lines between the charts (0.276 logMAR). Conclusion We did not identify a Snellen visual acuity app at the time of study, which could predict a patients standard Snellen visual acuity within one line. There was considerable variability in the optotype accuracy of apps. Further validation is required for assessment of acuity in patients with severe vision impairment. PMID:25931170

  3. Accuracy of Nurse-Performed Lung Ultrasound in Patients With Acute Dyspnea: A Prospective Observational Study.

    PubMed

    Mumoli, Nicola; Vitale, Josè; Giorgi-Pierfranceschi, Matteo; Cresci, Alessandra; Cei, Marco; Basile, Valentina; Brondi, Barbara; Russo, Elisa; Giuntini, Lucia; Masi, Lorenzo; Cocciolo, Massimo; Dentali, Francesco

    2016-03-01

    In clinical practice lung ultrasound (LUS) is becoming an easy and reliable noninvasive tool for the evaluation of dyspnea. The aim of this study was to assess the accuracy of nurse-performed LUS, in particular, in the diagnosis of acute cardiogenic pulmonary congestion. We prospectively evaluated all the consecutive patients admitted for dyspnea in our Medicine Department between April and July 2014. At admission, serum brain natriuretic peptide (BNP) levels and LUS was performed by trained nurses blinded to clinical and laboratory data. The accuracy of nurse-performed LUS alone and combined with BNP for the diagnosis of acute cardiogenic dyspnea was calculated. Two hundred twenty-six patients (41.6% men, mean age 78.7 ± 12.7 years) were included in the study. Nurse-performed LUS alone had a sensitivity of 95.3% (95% CI: 92.6-98.1%), a specificity of 88.2% (95% CI: 84.0-92.4%), a positive predictive value of 87.9% (95% CI: 83.7-92.2%) and a negative predictive value of 95.5% (95% CI: 92.7-98.2%). The combination of nurse-performed LUS with BNP level (cut-off 400 pg/mL) resulted in a higher sensitivity (98.9%, 95% CI: 97.4-100%), negative predictive value (98.8%, 95% CI: 97.2-100%), and corresponding negative likelihood ratio (0.01, 95% CI: 0.0, 0.07). Nurse-performed LUS had a good accuracy in the diagnosis of acute cardiogenic dyspnea. Use of this technique in combination with BNP seems to be useful in ruling out cardiogenic dyspnea. Other studies are warranted to confirm our preliminary findings and to establish the role of this tool in other settings. PMID:26945396

  4. [Comparative study on hyperspectral inversion accuracy of soil salt content and electrical conductivity].

    PubMed

    Peng, Jie; Wang, Jia-Qiang; Xiang, Hong-Ying; Teng, Hong-Fen; Liu, Wei-Yang; Chi, Chun-Ming; Niu, Jian-Long; Guo, Yan; Shi, Zhou

    2014-02-01

    The objective of the present article is to ascertain the mechanism of hyperspectral remote sensing monitoring for soil salinization, which is of great importance for improving the accuracy of hyperspectral remote sensing monitoring. Paddy soils in Wensu, Hetian and Baicheng counties of the southern Xinjiang were selected. Hyperspectral data of soils were obtained. Soil salt content (S(t)) an electrical conductivity of 1:5 soil-to-water extracts (EC(1:5)) were determined. Relationships between S(t) and EC(1:5) were studied. Correlations between hyperspectral indices and S(t), and EC(1:5) were analyzed. The inversion accuracy of S(t) using hyperspectral technique was compared with that of EC(1:5). Results showed that: significant (p<0.01) relationships were found between S(t) and EC(1:5) for soils in Wensu and Hetian counties, and correlation coefficients were 0.86 and 0.45, respectively; there was no significant relationship between S(t) and EC(1:5) for soils in Baicheng county. Therefore, the correlations between S(t) and EC(1:5) varied with studied sites. S(t) and EC(1:5) were significantly related with spectral reflectance, first derivative reflectance and continuum-removed reflectance, respectively; but correlation coefficients between S(t) and spectral indices were higher than those between EC(1:5) and spectral indices, which was obvious in some sensitive bands for soil salinization such as 660, 35, 1229, 1414, 1721, 1738, 1772, 2309 nm, and so on. Prediction equations of St and EC(1:5) were established using multivariate linear regression, principal component regression and partial least-squares regression methods, respectively. Coefficients of determination, determination coefficients of prediction, and relative analytical errors of these equations were analyzed. Coefficients of determination and relative analytical errors of equations between S(t) and spectral indices were higher than those of equations between EC(1:5) and spectral indices. Therefore, the

  5. Astra: Interdisciplinary study on enhancement of the end-to-end accuracy for spacecraft tracking techniques

    NASA Astrophysics Data System (ADS)

    Iess, Luciano; Di Benedetto, Mauro; James, Nick; Mercolino, Mattia; Simone, Lorenzo; Tortora, Paolo

    2014-02-01

    Navigation of deep-space probes is accomplished through a variety of different radio observables, namely Doppler, ranging and Delta-Differential One-Way Ranging (Delta-DOR). The particular mix of observations used for navigation mainly depends on the available on-board radio system, the mission phase and orbit determination requirements. The accuracy of current ESA and NASA tracking systems is at level of 0.1 mm/s at 60 s integration time for Doppler, 1-5 m for ranging and 6-15 nrad for Delta-DOR measurements in a wide range of operational conditions. The ASTRA study, funded under ESA's General Studies Programme (GSP), addresses the ways to improve the end-to-end accuracy of Doppler, ranging and Delta-DOR systems by roughly a factor of 10. The target accuracies were set to 0.01 mm/s at 60 s integration time for Doppler, 20 cm for ranging and 1 nrad for Delta-DOR. The companies and universities that took part in the study were the University of Rome Sapienza, ALMASpace, BAE Systems and Thales Alenia Space Italy. The analysis of an extensive data set of radio-metric observables and dedicated tests of the ground station allowed consolidating the error budget for each measurement technique. The radio-metric data set comprises X/X, X/Ka and Ka/Ka range and Doppler observables from the Cassini and Rosetta missions. It includes also measurements from the Advanced Media Calibration System (AMCS) developed by JPL for the radio science experiments of the Cassini mission. The error budget for the three radio-metric observables was consolidated by comparing the statistical properties of the data set with the expected error models. The analysis confirmed the contribution from some error sources, but revealed also some discrepancies and ultimately led to improved error models. The error budget reassessment provides adequate information for building guidelines and strategies to effectively improve the navigation accuracies of future deep space missions. We report both on updated

  6. Diagnostic Accuracy of Frozen Section of Central Nervous System Lesions: A 10-Year Study

    PubMed Central

    KHODDAMI, Maliheh; AKBARZADEH, Ali; MORDAI, Afshin; BIDARI - ZEREHPOUSH, Farahnaz; ALIPOUR, Hamid; SAMADZADEH, Sara; ALIPOUR, Bijan

    2015-01-01

    Objective Definitive diagnosis of the central nervous system (CNS) lesions is unknown prior to histopathological examination. To determine the method and the endpoint for surgery, intraoperative evaluation of the lesion helps the surgeon. In this study, the diagnostic accuracy and pitfalls of using frozen section (FS) of CNS lesions is determined. Materials & Methods In this retrospective study, we analyzed the results of FS and permanent diagnoses of all CNS lesions by reviewing reports from 3 general hospitals between March 2001 and March 2011. Results 273 cases were reviewed and patients with an age range from 3 to 77 years of age were considered. 166 (60.4%) had complete concordance between FS and permanent section diagnosis, 83 (30.2%) had partial concordance, and 24 cases (9.5%) were discordant. Considering the concordant and partially concordant cases, the accuracy rate was 99.5%, sensitivity was 91.4%, specificity was 99.7%, and positive and negative predictive values were 88.4% and 99.8%, respectively. Conclusion Our results show high sensitivity and specificity of FS diagnosis in the evaluation of CNS lesions. A Kappa agreement score of 0.88 shows high concordance for FS results with permanent section. Pathologist’s misinterpretation, small biopsy samples (not representative of the entire tumor), suboptimal slides, and inadequate information about tumor location and radiologic findings appear to be the major causes for these discrepancies indicated from our study. PMID:25767535

  7. [An experimental study on human bitemarks digital analysis and its accuracy].

    PubMed

    Wu, Yan; Chen, Xinmin; Sun, Dahong

    2005-10-01

    This experiment was designed to study the method of human bitemarks digital analysis and its accuracy. The human bitemarks were made on the dog skin by human dentition. The related parameters of human bitemarks and suspects criminal dentitions were digitally recorded and managed. The digital picture of human bitemark was obtained, and the dental study model, bite in wax and bitemark on pig skin of suspected criminal were scanned. The overlay was prepared with Adobe Photoshop 5. 5 and the parameters were measured with AutoCAD R14, then their matches were compared. The result shows that the human bitemarks digital analysis is a more accurate approach to human bitemarks identification. Three methods for collecting evidence dental study model, bite in wax and bitemark on pig skin all can be used as aids in forensic sciences. Dental study model is the most accurate one of all the three methods mentioned above. PMID:16294721

  8. [An experimental study on human bitemarks digital analysis and its accuracy].

    PubMed

    Wu, Yan; Chen, Xinmin; Sun, Dahong

    2005-10-01

    This experiment was designed to study the method of human bitemarks digital analysis and its accuracy. The human bitemarks were made on the dog skin by human dentition. The related parameters of human bitemarks and suspects criminal dentitions were digitally recorded and managed. The digital picture of human bitemark was obtained, and the dental study model, bite in wax and bitemark on pig skin of suspected criminal were scanned. The overlay was prepared with Adobe Photoshop 5. 5 and the parameters were measured with AutoCAD R14, then their matches were compared. The result shows that the human bitemarks digital analysis is a more accurate approach to human bitemarks identification. Three methods for collecting evidence dental study model, bite in wax and bitemark on pig skin all can be used as aids in forensic sciences. Dental study model is the most accurate one of all the three methods mentioned above.

  9. A PILOT STUDY OF THE ACCURACY OF CO2 SENSORS IN COMMERCIAL BUILDINGS

    SciTech Connect

    Fisk, William; Fisk, William J.; Faulkner, David; Sullivan, Douglas P.

    2007-09-01

    Carbon dioxide (CO2) sensors are often deployed in commercial buildings to obtain CO2 data that are used to automatically modulate rates of outdoor air supply. The goal is to keep ventilation rates at or above design requirements and to save energy by avoiding ventilation rates exceeding design requirements. However, there have been many anecdotal reports of poor CO2 sensor performance in actual commercial building applications. This study evaluated the accuracy of 44 CO2 sensors located in nine commercial buildings to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. CO2 measurement errors varied widely and were sometimes hundreds of parts per million. Despite its small size, this study provides a strong indication that the accuracy of CO2 sensors, as they are applied and maintained in commercial buildings, is frequently less than needed to measure typical values of maximum one-hour-average indoor-outdoor CO2 concentration differences with less than a 20percent error. Thus, we conclude that there is a need for more accurate CO2 sensors and/or better sensor maintenance or calibration procedures.

  10. Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.

    PubMed

    Sanders, Geoff; Sinclair, Kamila

    2011-12-01

    We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering. PMID:21125324

  11. Pose estimation with a Kinect for ergonomic studies: evaluation of the accuracy using a virtual mannequin.

    PubMed

    Plantard, Pierre; Auvinet, Edouard; Pierres, Anne-Sophie Le; Multon, Franck

    2015-01-01

    Analyzing human poses with a Kinect is a promising method to evaluate potentials risks of musculoskeletal disorders at workstations. In ecological situations, complex 3D poses and constraints imposed by the environment make it difficult to obtain reliable kinematic information. Thus, being able to predict the potential accuracy of the measurement for such complex 3D poses and sensor placements is challenging in classical experimental setups. To tackle this problem, we propose a new evaluation method based on a virtual mannequin. In this study, we apply this method to the evaluation of joint positions (shoulder, elbow, and wrist), joint angles (shoulder and elbow), and the corresponding RULA (a popular ergonomics assessment grid) upper-limb score for a large set of poses and sensor placements. Thanks to this evaluation method, more than 500,000 configurations have been automatically tested, which would be almost impossible to evaluate with classical protocols. The results show that the kinematic information obtained by the Kinect software is generally accurate enough to fill in ergonomic assessment grids. However inaccuracy strongly increases for some specific poses and sensor positions. Using this evaluation method enabled us to report configurations that could lead to these high inaccuracies. As a supplementary material, we provide a software tool to help designers to evaluate the expected accuracy of this sensor for a set of upper-limb configurations. Results obtained with the virtual mannequin are in accordance with those obtained from a real subject for a limited set of poses and sensor placements. PMID:25599426

  12. Pose Estimation with a Kinect for Ergonomic Studies: Evaluation of the Accuracy Using a Virtual Mannequin

    PubMed Central

    Plantard, Pierre; Auvinet, Edouard; Le Pierres, Anne-Sophie; Multon, Franck

    2015-01-01

    Analyzing human poses with a Kinect is a promising method to evaluate potentials risks of musculoskeletal disorders at workstations. In ecological situations, complex 3D poses and constraints imposed by the environment make it difficult to obtain reliable kinematic information. Thus, being able to predict the potential accuracy of the measurement for such complex 3D poses and sensor placements is challenging in classical experimental setups. To tackle this problem, we propose a new evaluation method based on a virtual mannequin. In this study, we apply this method to the evaluation of joint positions (shoulder, elbow, and wrist), joint angles (shoulder and elbow), and the corresponding RULA (a popular ergonomics assessment grid) upper-limb score for a large set of poses and sensor placements. Thanks to this evaluation method, more than 500,000 configurations have been automatically tested, which would be almost impossible to evaluate with classical protocols. The results show that the kinematic information obtained by the Kinect software is generally accurate enough to fill in ergonomic assessment grids. However inaccuracy strongly increases for some specific poses and sensor positions. Using this evaluation method enabled us to report configurations that could lead to these high inaccuracies. As a supplementary material, we provide a software tool to help designers to evaluate the expected accuracy of this sensor for a set of upper-limb configurations. Results obtained with the virtual mannequin are in accordance with those obtained from a real subject for a limited set of poses and sensor placements. PMID:25599426

  13. The effect of morphology on spelling and reading accuracy: a study on Italian children

    PubMed Central

    Angelelli, Paola; Marinelli, Chiara Valeria; Burani, Cristina

    2014-01-01

    In opaque orthographies knowledge of morphological information helps in achieving reading and spelling accuracy. In transparent orthographies with regular print-to-sound correspondences, such as Italian, the mappings of orthography onto phonology and phonology onto orthography are in principle sufficient to read and spell most words. The present study aimed to investigate the role of morphology in the reading and spelling accuracy of Italian children as a function of school experience to determine whether morphological facilitation was present in children learning a transparent orthography. The reading and spelling performances of 15 third-grade and 15 fifth-grade typically developing children were analyzed. Children read aloud and spelled both low-frequency words and pseudowords. Low-frequency words were manipulated for the presence of morphological structure (morphemic words vs. non-derived words). Morphemic words could also vary for the frequency (high vs. low) of roots and suffixes. Pseudo-words were made up of either a real root and a real derivational suffix in a combination that does not exist in the Italian language or had no morphological constituents. Results showed that, in Italian, morphological information is a useful resource for both reading and spelling. Typically developing children benefitted from the presence of morphological structure when they read and spelled pseudowords; however, in processing low-frequency words, morphology facilitated reading but not spelling. These findings are discussed in terms of morpho-lexical access and successful cooperation between lexical and sublexical processes in reading and spelling. PMID:25477855

  14. Impact of contacting study authors to obtain additional data for systematic reviews: diagnostic accuracy studies for hepatic fibrosis

    PubMed Central

    2014-01-01

    Background Seventeen of 172 included studies in a recent systematic review of blood tests for hepatic fibrosis or cirrhosis reported diagnostic accuracy results discordant from 2 × 2 tables, and 60 studies reported inadequate data to construct 2 × 2 tables. This study explores the yield of contacting authors of diagnostic accuracy studies and impact on the systematic review findings. Methods Sixty-six corresponding authors were sent letters requesting additional information or clarification of data from 77 studies. Data received from the authors were synthesized with data included in the previous review, and diagnostic accuracy sensitivities, specificities, and positive and likelihood ratios were recalculated. Results Of the 66 authors, 68% were successfully contacted and 42% provided additional data for 29 out of 77 studies (38%). All authors who provided data at all did so by the third emailed request (ten authors provided data after one request). Authors of more recent studies were more likely to be located and provide data compared to authors of older studies. The effects of requests for additional data on the conclusions regarding the utility of blood tests to identify patients with clinically significant fibrosis or cirrhosis were generally small for ten out of 12 tests. Additional data resulted in reclassification (using median likelihood ratio estimates) from less useful to moderately useful or vice versa for the remaining two blood tests and enabled the calculation of an estimate for a third blood test for which previously the data had been insufficient to do so. We did not identify a clear pattern for the directional impact of additional data on estimates of diagnostic accuracy. Conclusions We successfully contacted and received results from 42% of authors who provided data for 38% of included studies. Contacting authors of studies evaluating the diagnostic accuracy of serum biomarkers for hepatic fibrosis and cirrhosis in hepatitis C patients

  15. Accuracy in Rietveld quantitative phase analysis: a comparative study of strictly monochromatic Mo and Cu radiations

    PubMed Central

    León-Reina, L.; García-Maté, M.; Álvarez-Pinazo, G.; Santacruz, I.; Vallcorba, O.; De la Torre, A. G.; Aranda, M. A. G.

    2016-01-01

    This study reports 78 Rietveld quantitative phase analyses using Cu Kα1, Mo Kα1 and synchrotron radiations. Synchrotron powder diffraction has been used to validate the most challenging analyses. From the results for three series with increasing contents of an analyte (an inorganic crystalline phase, an organic crystalline phase and a glass), it is inferred that Rietveld analyses from high-energy Mo Kα1 radiation have slightly better accuracies than those obtained from Cu Kα1 radiation. This behaviour has been established from the results of the calibration graphics obtained through the spiking method and also from Kullback–Leibler distance statistic studies. This outcome is explained, in spite of the lower diffraction power for Mo radiation when compared to Cu radiation, as arising because of the larger volume tested with Mo and also because higher energy allows one to record patterns with fewer systematic errors. The limit of detection (LoD) and limit of quantification (LoQ) have also been established for the studied series. For similar recording times, the LoDs in Cu patterns, ∼0.2 wt%, are slightly lower than those derived from Mo patterns, ∼0.3 wt%. The LoQ for a well crystallized inorganic phase using laboratory powder diffraction was established to be close to 0.10 wt% in stable fits with good precision. However, the accuracy of these analyses was poor with relative errors near to 100%. Only contents higher than 1.0 wt% yielded analyses with relative errors lower than 20%. PMID:27275132

  16. Compensation of kinematic geometric parameters error and comparative study of accuracy testing for robot

    NASA Astrophysics Data System (ADS)

    Du, Liang; Shi, Guangming; Guan, Weibin; Zhong, Yuansheng; Li, Jin

    2014-12-01

    Geometric error is the main error of the industrial robot, and it plays a more significantly important fact than other error facts for robot. The compensation model of kinematic error is proposed in this article. Many methods can be used to test the robot accuracy, therefore, how to compare which method is better one. In this article, a method is used to compare two methods for robot accuracy testing. It used Laser Tracker System (LTS) and Three Coordinate Measuring instrument (TCM) to test the robot accuracy according to standard. According to the compensation result, it gets the better method which can improve the robot accuracy apparently.

  17. Speed and accuracy of facial expression classification in avoidant personality disorder: a preliminary study.

    PubMed

    Rosenthal, M Zachary; Kim, Kwanguk; Herr, Nathaniel R; Smoski, Moria J; Cheavens, Jennifer S; Lynch, Thomas R; Kosson, David S

    2011-10-01

    The aim of this preliminary study was to examine whether individuals with avoidant personality disorder (APD) could be characterized by deficits in the classification of dynamically presented facial emotional expressions. Using a community sample of adults with APD (n = 17) and non-APD controls (n = 16), speed and accuracy of facial emotional expression recognition was investigated in a task that morphs facial expressions from neutral to prototypical expressions (Multi-Morph Facial Affect Recognition Task; Blair, Colledge, Murray, & Mitchell, 2001). Results indicated that individuals with APD were significantly more likely than controls to make errors when classifying fully expressed fear. However, no differences were found between groups in the speed to correctly classify facial emotional expressions. The findings are some of the first to investigate facial emotional processing in a sample of individuals with APD and point to an underlying deficit in processing social cues that may be involved in the maintenance of APD. PMID:22448805

  18. EM-navigated catheter placement for gynecologic brachytherapy: an accuracy study

    NASA Astrophysics Data System (ADS)

    Mehrtash, Alireza; Damato, Antonio; Pernelle, Guillaume; Barber, Lauren; Farhat, Nabgha; Viswanathan, Akila; Cormack, Robert; Kapur, Tina

    2014-03-01

    Gynecologic malignancies, including cervical, endometrial, ovarian, vaginal and vulvar cancers, cause significant mortality in women worldwide. The standard care for many primary and recurrent gynecologic cancers consists of chemoradiation followed by brachytherapy. In high dose rate (HDR) brachytherapy, intracavitary applicators and /or interstitial needles are placed directly inside the cancerous tissue so as to provide catheters to deliver high doses of radiation. Although technology for the navigation of catheters and needles is well developed for procedures such as prostate biopsy, brain biopsy, and cardiac ablation, it is notably lacking for gynecologic HDR brachytherapy. Using a benchtop study that closely mimics the clinical interstitial gynecologic brachytherapy procedure, we developed a method for evaluating the accuracy of image-guided catheter placement. Future bedside translation of this technology offers the potential benefit of maximizing tumor coverage during catheter placement while avoiding damage to the adjacent organs, for example bladder, rectum and bowel. In the study, two independent experiments were performed on a phantom model to evaluate the targeting accuracy of an electromagnetic (EM) tracking system. The procedure was carried out using a laptop computer (2.1GHz Intel Core i7 computer, 8GB RAM, Windows 7 64-bit), an EM Aurora tracking system with a 1.3mm diameter 6 DOF sensor, and 6F (2 mm) brachytherapy catheters inserted through a Syed-Neblett applicator. The 3D Slicer and PLUS open source software were used to develop the system. The mean of the targeting error was less than 2.9mm, which is comparable to the targeting errors in commercial clinical navigation systems.

  19. EM-Navigated Catheter Placement for Gynecologic Brachytherapy: An Accuracy Study

    PubMed Central

    Mehrtash, Alireza; Damato, Antonio; Pernelle, Guillaume; Barber, Lauren; Farhat, Nabgha; Viswanathan, Akila; Cormack, Robert; Kapur, Tina

    2014-01-01

    Gynecologic malignancies, including cervical, endometrial, ovarian, vaginal and vulvar cancers, cause significant mortality in women worldwide. The standard care for many primary and recurrent gynecologic cancers consists of chemoradiation followed by brachytherapy. In high dose rate (HDR) brachytherapy, intracavitary applicators and/or interstitial needles are placed directly inside the cancerous tissue so as to provide catheters to deliver high doses of radiation. Although technology for the navigation of catheters and needles is well developed for procedures such as prostate biopsy, brain biopsy, and cardiac ablation, it is notably lacking for gynecologic HDR brachytherapy. Using a benchtop study that closely mimics the clinical interstitial gynecologic brachytherapy procedure, we developed a method for evaluating the accuracy of image-guided catheter placement. Future bedside translation of this technology offers the potential benefit of maximizing tumor coverage during catheter placement while avoiding damage to the adjacent organs, for example bladder, rectum and bowel. In the study, two independent experiments were performed on a phantom model to evaluate the targeting accuracy of an electromagnetic (EM) tracking system. The procedure was carried out using a laptop computer (2.1GHz Intel Core i7 computer, 8GB RAM, Windows 7 64-bit), an EM Aurora tracking system with a 1.3mm diameter 6 DOF sensor, and 6F (2 mm) brachytherapy catheters inserted through a Syed-Neblett applicator. The 3D Slicer and PLUS open source software were used to develop the system. The mean of the targeting error was less than 2.9mm, which is comparable to the targeting errors in commercial clinical navigation systems. PMID:25076828

  20. Summarising and validating test accuracy results across multiple studies for use in clinical practice.

    PubMed

    Riley, Richard D; Ahmed, Ikhlaaq; Debray, Thomas P A; Willis, Brian H; Noordzij, J Pieter; Higgins, Julian P T; Deeks, Jonathan J

    2015-06-15

    Following a meta-analysis of test accuracy studies, the translation of summary results into clinical practice is potentially problematic. The sensitivity, specificity and positive (PPV) and negative (NPV) predictive values of a test may differ substantially from the average meta-analysis findings, because of heterogeneity. Clinicians thus need more guidance: given the meta-analysis, is a test likely to be useful in new populations, and if so, how should test results inform the probability of existing disease (for a diagnostic test) or future adverse outcome (for a prognostic test)? We propose ways to address this. Firstly, following a meta-analysis, we suggest deriving prediction intervals and probability statements about the potential accuracy of a test in a new population. Secondly, we suggest strategies on how clinicians should derive post-test probabilities (PPV and NPV) in a new population based on existing meta-analysis results and propose a cross-validation approach for examining and comparing their calibration performance. Application is made to two clinical examples. In the first example, the joint probability that both sensitivity and specificity will be >80% in a new population is just 0.19, because of a low sensitivity. However, the summary PPV of 0.97 is high and calibrates well in new populations, with a probability of 0.78 that the true PPV will be at least 0.95. In the second example, post-test probabilities calibrate better when tailored to the prevalence in the new population, with cross-validation revealing a probability of 0.97 that the observed NPV will be within 10% of the predicted NPV.

  1. Study on Improvement of Accuracy in Inertial Photogrammetry by Combining Images with Inertial Measurement Unit

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hideaki; Anzai, Shojiro; Koizumi, Toshio

    2016-06-01

    Inertial photogrammetry is defined as photogrammetry that involves using a camera on which an inertial measurement unit (IMU) is mounted. In inertial photogrammetry, the position and inclination of a shooting camera are calculated using the IMU. An IMU is characterized by error growth caused by time accumulation because acceleration is integrated with respect to time. This study examines the procedure to estimate the position of the camera accurately while shooting using the IMU and the structure from motion (SfM) technology, which is applied in many fields, such as computer vision. When neither the coordinates of the position of the camera nor those of feature points are known, SfM provides a similar positional relationship between the position of the camera and feature points. Therefore, the actual length of positional coordinates is not determined. If the actual length of the position of the camera is unknown, the camera acceleration is obtained by calculating the second order differential of the position of the camera, with respect to the shooting time. The authors had determined the actual length by assigning the position of IMU to the SfM-calculated position. Hence, accuracy decreased because of the error growth, which was the characteristic feature of IMU. In order to solve this problem, a new calculation method was proposed. Using this method, the difference between the IMU-calculated acceleration and the camera-calculated acceleration can be obtained using the method of least squares, and the magnification required for calculating the actual dimension from the position of the camera can be obtained. The actual length can be calculated by multiplying all the SfM point groups by the obtained magnification factor. This calculation method suppresses the error growth, which is due to the time accumulation in IMU, and improves the accuracy of inertial photogrammetry.

  2. Model accuracy impact through rescaled observations in hydrological data assimilation studies

    NASA Astrophysics Data System (ADS)

    Tugrul Yilmaz, M.; Crow, Wade T.; Ryu, Dongryeol

    2015-04-01

    Relative magnitudes of signal and noise in soil moisture datasets (e.g. satellite-, model-, station-based) feature significant variability. Optimality of the analysis when assimilating observations into the model depends on the degree that the differences between the signal variances of model and observations are minimized. Rescaling techniques that aim to reduce such differences in general only focus on matching certain statistics of the model and the observations while the impact of their relative accuracy over the optimality of the analysis remains unexplored. In this study the impacts of the relative accuracies of seasonality and anomaly components of modeled and observation-based soil moisture time series on optimality of assimilation analysis is investigated. Experiments using well-controlled synthetic and real datasets are performed. Experiments are performed by rescaling observations to model with varying aggressiveness: i) rescaling the entire observation time-series as one-piece or each month separately; ii) rescaling observation seasonality and anomaly components separately; iii) inserting model seasonality directly into observations while anomaly components are only rescaled. A simple Antecedent Precipitation Index (API) model is selected in both synthetic and real dataset experiments. Observations are assimilated into the API model using Kalman filter. Real dataset experiments use the Land Parameter Retrieval Model (LPRM) product based on the Advanced Microwave Scanning Radiometer on the Aqua platform (AMSR-E) observations over four USDA-ARS watersheds, while ground-based observations collected over these watersheds are used for validation. Results show that it is favorable to rescale observations more aggressively to a model when the model is more accurate (higher signal to noise ratio than the observations), while rescaling the observations strongly to the model degrades the analysis if the observations are more skillful.

  3. Screw Placement Accuracy and Outcomes Following O-Arm-Navigated Atlantoaxial Fusion: A Feasibility Study.

    PubMed

    Smith, Jacob D; Jack, Megan M; Harn, Nicholas R; Bertsch, Judson R; Arnold, Paul M

    2016-06-01

    Study Design Case series of seven patients. Objective C2 stabilization can be challenging due to the complex anatomy of the upper cervical vertebrae. We describe seven cases of C1-C2 fusion using intraoperative navigation to aid in the screw placement at the atlantoaxial (C1-C2) junction. Methods Between 2011 and 2014, seven patients underwent posterior atlantoaxial fusion using intraoperative frameless stereotactic O-arm Surgical Imaging and StealthStation Surgical Navigation System (Medtronic, Inc., Minneapolis, Minnesota, United States). Outcome measures included screw accuracy, neurologic status, radiation dosing, and surgical complications. Results Four patients had fusion at C1-C2 only, and in the remaining three, fixation extended down to C3 due to anatomical considerations for screw placement recognized on intraoperative imaging. Out of 30 screws placed, all demonstrated minimal divergence from desired placement in either C1 lateral mass, C2 pedicle, or C3 lateral mass. No neurovascular compromise was seen following the use of intraoperative guided screw placement. The average radiation dosing due to intraoperative imaging was 39.0 mGy. All patients were followed for a minimum of 12 months. All patients went on to solid fusion. Conclusion C1-C2 fusion using computed tomography-guided navigation is a safe and effective way to treat atlantoaxial instability. Intraoperative neuronavigation allows for high accuracy of screw placement, limits complications by sparing injury to the critical structures in the upper cervical spine, and can help surgeons make intraoperative decisions regarding complex pathology. PMID:27190736

  4. Accuracy evaluation of the optical surface monitoring system on EDGE linear accelerator in a phantom study.

    PubMed

    Mancosu, Pietro; Fogliata, Antonella; Stravato, Antonella; Tomatis, Stefano; Cozzi, Luca; Scorsetti, Marta

    2016-01-01

    Frameless stereotactic radiosurgery (SRS) requires dedicated systems to monitor the patient position during the treatment to avoid target underdosage due to involuntary shift. The optical surface monitoring system (OSMS) is here evaluated in a phantom-based study. The new EDGE linear accelerator from Varian (Varian, Palo Alto, CA) integrates, for cranial lesions, the common cone beam computed tomography (CBCT) and kV-MV portal images to the optical surface monitoring system (OSMS), a device able to detect real-time patient׳s face movements in all 6 couch axes (vertical, longitudinal, lateral, rotation along the vertical axis, pitch, and roll). We have evaluated the OSMS imaging capability in checking the phantoms׳ position and monitoring its motion. With this aim, a home-made cranial phantom was developed to evaluate the OSMS accuracy in 4 different experiments: (1) comparison with CBCT in isocenter location, (2) capability to recognize predefined shifts up to 2° or 3cm, (3) evaluation at different couch angles, (4) ability to properly reconstruct the surface when the linac gantry visually block one of the cameras. The OSMS system showed, with a phantom, to be accurate for positioning in respect to the CBCT imaging system with differences of 0.6 ± 0.3mm for linear vector displacement, with a maximum rotational inaccuracy of 0.3°. OSMS presented an accuracy of 0.3mm for displacement up to 1cm and 1°, and 0.5mm for larger displacements. Different couch angles (45° and 90°) induced a mean vector uncertainty < 0.4mm. Coverage of 1 camera produced an uncertainty < 0.5mm. Translations and rotations of a phantom can be accurately detect with the optical surface detector system.

  5. Determining immunisation status of children from history: a diagnostic accuracy study

    PubMed Central

    Nohavicka, Laura; Ashdown, Helen F; Kelly, Dominic F

    2013-01-01

    Objectives Children presenting unplanned to healthcare services are routinely asked about previous immunisations as part of their assessment. We aimed to assess the accuracy of screening children for immunisation status by history. Design Diagnostic accuracy study. We compared information from patient history by a retrospective review of notes and used a central database of child immunisation records as the reference standard. Setting Paediatric emergency department in a tertiary hospital in Oxford, UK. Participants Consecutive children aged 6 months to 6 years presenting over a 2-month period. Outcome measures Proportion of children with documented immunisation history; sensitivity and specificity of detecting overdue immunisations by history compared to central records. Results 1166 notes were surveyed. 76.3% children were asked about immunisations. The proportion of children who were fully immunised on central records was 93.1%. History had a sensitivity of 41.3% (95% CI 27% to 56.8%) and a specificity of 98.7% (95% CI 97.5% to 99.4%) for detecting those who were overdue. Negative predictive value was 95.8% (95% CI 93.9% to 97.2%). Only around a third of children with overdue immunisations are detected by the current screening methods, and approximately 1 in 20 children stated as being up to date are in fact overdue. Conclusions History had poor sensitivity for identifying overdue immunisation. Strategies to improve detection of children overdue with immunisation should focus on alternative strategies for alerting clinicians, such as linkage of community and hospital electronic records. PMID:23633421

  6. Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study

    PubMed Central

    Bongartz, Tim; Glazebrook, Katrina N; Kavros, Steven J; Murthy, Naveen S; Merry, Stephen P; Franz, Walter B; Michet, Clement J; Veetil, Barath M Akkara; Davis, John M; Mason, Thomas G; Warrington, Kenneth J; Ytterberg, Steven R; Matteson, Eric L; Crowson, Cynthia S; Leng, Shuai; McCollough, Cynthia H

    2015-01-01

    Objectives To assess the accuracy of dual-energy CT (DECT) for diagnosing gout, and to explore whether it can have any impact on clinical decision making beyond the established diagnostic approach using polarising microscopy of synovial fluid (diagnostic yield). Methods Diagnostic single-centre study of 40 patients with active gout, and 41 individuals with other types of joint disease. Sensitivity and specificity of DECT for diagnosing gout was calculated against a combined reference standard (polarising and electron microscopy of synovial fluid). To explore the diagnostic yield of DECT scanning, a third cohort was assembled consisting of patients with inflammatory arthritis and risk factors for gout who had negative synovial fluid polarising microscopy results. Among these patients, the proportion of subjects with DECT findings indicating a diagnosis of gout was assessed. Results The sensitivity and specificity of DECT for diagnosing gout was 0.90 (95% CI 0.76 to 0.97) and 0.83 (95% CI 0.68 to 0.93), respectively. All false negative patients were observed among patients with acute, recent-onset gout. All false positive patients had advanced knee osteoarthritis. DECT in the diagnostic yield cohort revealed evidence of uric acid deposition in 14 out of 30 patients (46.7%). Conclusions DECT provides good diagnostic accuracy for detection of monosodium urate (MSU) deposits in patients with gout. However, sensitivity is lower in patients with recent-onset disease. DECT has a significant impact on clinical decision making when gout is suspected, but polarising microscopy of synovial fluid fails to demonstrate the presence of MSU crystals. PMID:24671771

  7. Cocontraction of Pairs of Muscles around Joints May Improve an Accuracy of a Reaching Movement: a Numerical Simulation Study

    NASA Astrophysics Data System (ADS)

    Ueyama, Yuki; Miyashita, Eizo

    2011-06-01

    We have pair muscle groups on a joint; agonist and antagonist muscles. Simultaneous activation of agonist and antagonist muscles around a joint, which is called cocontraction, is suggested to take a role of increasing the joint stiffness in order to decelerate hand speed and improve movement accuracy. However, it has not been clear how cocontraction and the joint stiffness are varied during movements. In this study, muscle activation and the joint stiffness in reaching movements were studied under several requirements of end-point accuracy using a 2-joint 6-muscle model and an approximately optimal control. The time-varying cocontraction and the joint stiffness were showed by the numerically simulation study. It indicated that the strength of cocontraction and the joint stiffness increased synchronously as the required accuracy level increased. We conclude that cocontraction may get the joint stiffness increased to achieve higher requirement of the movement accuracy.

  8. Spontaneous Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis Describing the Diagnostic Accuracy of History, Physical Exam, Imaging, and Lumbar Puncture with an Exploration of Test Thresholds

    PubMed Central

    Carpenter, Christopher R.; Hussain, Adnan M.; Ward, Michael J.; Zipfel, Gregory J.; Fowler, Susan; Pines, Jesse M.; Sivilotti, Marco L.A.

    2016-01-01

    Background Spontaneous subarachnoid hemorrhage (SAH) is a rare, but serious etiology of headache. The diagnosis of SAH is especially challenging in alert, neurologically intact patients, as missed or delayed diagnosis can be catastrophic. Objectives To perform a diagnostic accuracy systematic review and meta-analysis of history, physical examination, cerebrospinal fluid (CSF) tests, computed tomography (CT), and clinical decision rules for spontaneous SAH. A secondary objective was to delineate probability of disease thresholds for imaging and lumbar puncture (LP). Methods PUBMED, EMBASE, SCOPUS, and research meeting abstracts were searched up to June 2015 for studies of emergency department (ED) patients with acute headache clinically concerning for spontaneous SAH. QUADAS-2 was used to assess study quality and, when appropriate, meta-analysis was conducted using random effects models. Outcomes were sensitivity, specificity, positive (LR+) and negative (LR−) likelihood ratios. To identify test- and treatment-thresholds, we employed the Pauker-Kassirer method with Bernstein test-indication curves using the summary estimates of diagnostic accuracy. Results A total of 5,022 publications were identified, of which 122 underwent full text-review; 22 studies were included (average SAH prevalence 7.5%). Diagnostic studies differed in assessment of history and physical exam findings, CT technology, analytical techniques used to identify xanthochromia, and criterion standards for SAH. Study quality by QUADAS-2 was variable; however, most had a relatively low-risk of biases. A history of neck pain (LR+ 4.1 [95% CI 2.2-7.6]) and neck stiffness on physical exam (LR+ 6.6 [4.0-11.0]) were the individual findings most strongly associated with SAH. Combinations of findings may rule out SAH, yet promising clinical decision rules await external validation. Non-contrast cranial CT within 6 hours of headache onset accurately ruled-in (LR+ 230 [6-8700]) and ruled-out SAH (LR− 0

  9. Effects of sampling and mineral separation on accuracy of detrital zircon studies

    NASA Astrophysics Data System (ADS)

    SláMa, JiřÃ.­; KošLer, Jan

    2012-05-01

    We investigated some of the sampling and mineral separation biases that affect the accuracy of detrital zircon provenance studies. The study has been carried on a natural catchment in the Scottish Highlands that represents a simple two-component source system and on samples of synthetic sediment prepared for this study to test the effects of heavy mineral separation on the resulting zircon age spectra. The results suggest that zircon fertility of the source rocks and physical properties of zircon represent the most important factors affecting the distribution of zircon age populations in the stream sediments. The sample preparation and selection of zircons for analysis may result in preferential loss of information from small zircon grains. Together with the preference for larger crystals during handpicking, it can result in several-fold difference compared to the real age distribution in the sediment sample. These factors appear to be more important for the reproducibility of zircon age spectra than is the number of zircon grains analyzed per sample.

  10. Clinical relevance of studies on the accuracy of visual inspection for detecting caries lesions: a systematic review.

    PubMed

    Gimenez, Thais; Piovesan, Chaiana; Braga, Mariana M; Raggio, Daniela P; Deery, Chris; Ricketts, David N; Ekstrand, Kim R; Mendes, Fausto Medeiros

    2015-01-01

    Although visual inspection is the most commonly used method for caries detection, and consequently the most investigated, studies have not been concerned about the clinical relevance of this procedure. Therefore, we conducted a systematic review in order to perform a critical evaluation considering the clinical relevance and methodological quality of studies on the accuracy of visual inspection for assessing caries lesions. Two independent reviewers searched several databases through July 2013 to identify papers/articles published in English. Other sources were checked to identify unpublished literature. The eligible studies were those which (1) assessed the accuracy of the visual method for detecting caries lesions on occlusal, approximal or smooth surfaces, in primary or permanent teeth, (2) used a reference standard, and (3) reported data about sample size and accuracy of the methods. Aspects related to clinical relevance and the methodological quality of the studies were evaluated. 96 of the 5,578 articles initially identified met the inclusion criteria. In general, most studies failed in considering some clinically relevant aspects: only 1 included study validated activity status of lesions, no study considered its prognosis, 79 studies did not consider a clinically relevant outcome, and only 1 evaluated a patient-centred outcome. Concerning methodological quality, the majority of the studies presented a high risk of bias in sample selection. In conclusion, studies on the accuracy of the visual method for caries detection should consider clinically relevant outcomes besides accuracy; moreover, they should be conducted with higher methodological quality, mainly regarding sample selection.

  11. What level of accuracy is achievable for preclinical dose painting studies on a clinical irradiation platform?

    PubMed

    Trani, Daniela; Reniers, Brigitte; Persoon, Lucas; Podesta, Mark; Nalbantov, Georgi; Leijenaar, Ralph T H; Granzier, Marlies; Yaromina, Ala; Dubois, Ludwig; Verhaegen, Frank; Lambin, Philippe

    2015-05-01

    Advancements made over the past decades in both molecular imaging and radiotherapy planning and delivery have enabled studies that explore the efficacy of heterogeneous radiation treatment ("dose painting") of solid cancers based on biological information provided by different imaging modalities. In addition to clinical trials, preclinical studies may help contribute to identifying promising dose painting strategies. The goal of this current study was twofold: to develop a reproducible positioning and set-up verification protocol for a rat tumor model to be imaged and treated on a clinical platform, and to assess the dosimetric accuracy of dose planning and delivery for both uniform and positron emission tomography-computed tomography (PET-CT) based heterogeneous dose distributions. We employed a syngeneic rat rhabdomyosarcoma model, which was irradiated by volumetric modulated arc therapy (VMAT) with uniform or heterogeneous 6 MV photon dose distributions. Mean dose to the gross tumor volume (GTV) as a whole was kept at 12 Gy for all treatment arms. For the nonuniform plans, the dose was redistributed to treat the 30% of the GTV representing the biological target volume (BTV) with a dose 40% higher than the rest of the GTV (GTV - BTV) (~15 Gy was delivered to the BTV vs. ~10.7 Gy was delivered to the GTV - BTV). Cone beam computed tomography (CBCT) images acquired for each rat prior to irradiation were used to correctly reposition the tumor and calculate the delivered 3D dose. Film quality assurance was performed using a water-equivalent rat phantom. A comparison between CT or CBCT doses and film measurements resulted in passing rates >98% with a gamma criterion of 3%/2 mm using 2D dose images. Moreover, between the CT and CBCT calculated doses for both uniform and heterogeneous plans, we observed maximum differences of <2% for mean dose to the tumor and mean dose to the biological target volumes. In conclusion, we have developed a robust method for dose painting

  12. Accuracy of computer-aided template-guided oral implant placement: a prospective clinical study

    PubMed Central

    2014-01-01

    Purpose The aim of the present study was to evaluate the in vivo accuracy of flapless, computer-aided implant placement by comparing the three-dimensional (3D) position of planned and placed implants through an analysis of linear and angular deviations. Methods Implant position was virtually planned using 3D planning software based on the functional and aesthetic requirements of the final restorations. Computer-aided design/computer-assisted manufacture technology was used to transfer the virtual plan to the surgical environment. The 3D position of the planned and placed implants, in terms of the linear deviations of the implant head and apex and the angular deviations of the implant axis, was compared by overlapping the pre- and postoperative computed tomography scans using dedicated software. Results The comparison of 14 implants showed a mean linear deviation of the implant head of 0.56 mm (standard deviation [SD], 0.23), a mean linear deviation of the implant apex of 0.64 mm (SD, 0.29), and a mean angular deviation of the long axis of 2.42° (SD, 1.02). Conclusions In the present study, computer-aided flapless implant surgery seemed to provide several advantages to the clinicians as compared to the standard procedure; however, linear and angular deviations are to be expected. Therefore, accurate presurgical planning taking into account anatomical limitations and prosthetic demands is mandatory to ensure a predictable treatment, without incurring possible intra- and postoperative complications. Graphical Abstract PMID:25177520

  13. Evaluation of accuracy of cone beam computed tomography for measurement of periodontal defects: A clinical study

    PubMed Central

    Banodkar, Akshaya Bhupesh; Gaikwad, Rajesh Prabhakar; Gunjikar, Tanay Udayrao; Lobo, Tanya Arthur

    2015-01-01

    Aims: The aim of the present study was to evaluate the accuracy of Cone Beam Computed Tomography (CBCT) measurements of alveolar bone defects caused due to periodontal disease, by comparing it with actual surgical measurements which is the gold standard. Materials and Methods: Hundred periodontal bone defects in fifteen patients suffering from periodontitis and scheduled for flap surgery were included in the study. On the day of surgery prior to anesthesia, CBCT of the quadrant to be operated was taken. After reflection of the flap, clinical measurements of periodontal defect were made using a reamer and digital vernier caliper. The measurements taken during surgery were then compared to the measurements done with CBCT and subjected to statistical analysis using the Pearson's correlation test. Results: Overall there was a very high correlation of 0.988 between the surgical and CBCT measurements. In case of type of defects the correlation was higher in horizontal defects as compared to vertical defects. Conclusions: CBCT is highly accurate in measurement of periodontal defects and proves to be a very useful tool in periodontal diagnosis and treatment assessment. PMID:26229268

  14. Camino® intracranial pressure monitor: prospective study of accuracy and complications

    PubMed Central

    Martinez-Manas, R.; Santamarta, D.; de Campos, J. M; Ferrer, E.

    2000-01-01

    OBJECTIVES—The fibreoptic device is a type of intracranial pressure monitor which seems to offer certain advantages over conventional monitoring systems. This study was undertaken to analyse the accuracy, drift characteristics, and complications of the Camino® fibreoptic device.
METHODS—One hundred and eight Camino® intracranial pressure (ICP) devices, in their three modalities, were implanted during 1997.The most frequent indication for monitoring was severe head injury due to road traffic accidents.
RESULTS—Sixty eight probe tips were cultured; 13.2% of the cases had a positive culture without clinical signs of infection, and 2.9% had a positive culture with clinical signs of ventriculitis. The most common isolated pathogen was Staphylococcus epidermidis. All patients were under cephalosporin prophylaxis during monitoring. Haemorrhage rate in patients without coagulation disorders was 2.1% and 15.3% in patients with coagulation abnormalities. Drift characteristics were studied in 56 cases; there was no drifting from the values expected according to the manufacturer's specifications in 34 probes. There was no relation between direction of the drift and duration of placement, nor between drift and time.
CONCLUSIONS—Although the complication and drift rates were similar to those reported elsewhere, there was no correlation between the direction of the drift and long term monitoring despite the fact that some published papers refer to overestimation of values with time with this type of device.

 PMID:10864608

  15. Is early detection of abused children possible?: a systematic review of the diagnostic accuracy of the identification of abused children

    PubMed Central

    2013-01-01

    Background Early detection of abused children could help decrease mortality and morbidity related to this major public health problem. Several authors have proposed tools to screen for child maltreatment. The aim of this systematic review was to examine the evidence on accuracy of tools proposed to identify abused children before their death and assess if any were adapted to screening. Methods We searched in PUBMED, PsycINFO, SCOPUS, FRANCIS and PASCAL for studies estimating diagnostic accuracy of tools identifying neglect, or physical, psychological or sexual abuse of children, published in English or French from 1961 to April 2012. We extracted selected information about study design, patient populations, assessment methods, and the accuracy parameters. Study quality was assessed using QUADAS criteria. Results A total of 2 280 articles were identified. Thirteen studies were selected, of which seven dealt with physical abuse, four with sexual abuse, one with emotional abuse, and one with any abuse and physical neglect. Study quality was low, even when not considering the lack of gold standard for detection of abused children. In 11 studies, instruments identified abused children only when they had clinical symptoms. Sensitivity of tests varied between 0.26 (95% confidence interval [0.17-0.36]) and 0.97 [0.84-1], and specificity between 0.51 [0.39-0.63] and 1 [0.95-1]. The sensitivity was greater than 90% only for three tests: the absence of scalp swelling to identify children victims of inflicted head injury; a decision tool to identify physically-abused children among those hospitalized in a Pediatric Intensive Care Unit; and a parental interview integrating twelve child symptoms to identify sexually-abused children. When the sensitivity was high, the specificity was always smaller than 90%. Conclusions In 2012, there is low-quality evidence on the accuracy of instruments for identifying abused children. Identified tools were not adapted to screening because of

  16. Accuracy of positioning and irradiation targeting for multiple targets in intracranial image-guided radiation therapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Tominaga, Hirofumi; Araki, Fujio; Shimohigashi, Yoshinobu; Ishihara, Terunobu; Kawasaki, Keiichi; Kanetake, Nagisa; Sakata, Junichi; Iwashita, Yuki

    2014-12-01

    This study investigated the accuracy of positioning and irradiation targeting for multiple off-isocenter targets in intracranial image-guided radiation therapy (IGRT). A phantom with nine circular targets was created to evaluate both accuracies. First, the central point of the isocenter target was positioned with a combination of an ExacTrac x-ray (ETX) and a 6D couch. The positioning accuracy was determined from the deviations of coordinates of the central point in each target obtained from the kV-cone beam computed tomography (kV-CBCT) for IGRT and the planning CT. Similarly, the irradiation targeting accuracy was evaluated from the deviations of the coordinates between the central point of each target and the central point of each multi-leaf collimator (MLC) field for multiple targets. Secondly, the 6D couch was intentionally rotated together with both roll and pitch angles of 0.5° and 1° at the isocenter and similarly the deviations were evaluated. The positioning accuracy for all targets was less than 1 mm after 6D positioning corrections. The irradiation targeting accuracy was up to 1.3 mm in the anteroposterior (AP) direction for a target 87 mm away from isocenter. For the 6D couch rotations with both roll and pitch angles of 0.5° and 1°, the positioning accuracy was up to 1.0 mm and 2.3 mm in the AP direction for the target 87 mm away from the isocenter, respectively. The irradiation targeting accuracy was up to 2.1 mm and 2.6 mm in the AP direction for the target 87 mm away from the isocenter, respectively. The off-isocenter irradiation targeting accuracy became worse than the positioning accuracy. Both off-isocenter accuracies worsened in proportion to rotation angles and the distance from the isocenter to the targets. It is necessary to examine the set-up margin for off-isocenter multiple targets at each institution because irradiation targeting accuracy is peculiar to the linac machine.

  17. An experimental study of the accuracy in measurement of modulation transfer function using an edge method

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hoon; Kim, Ye-seul; Park, Hye-Suk; Lee, Young-Jin; Kim, Hee-Joung

    2015-03-01

    Image evaluation is necessary in digital radiography (DR) which is widely used in medical imaging. Among parameters of image evaluation, modulation transfer function (MTF) is the important factor in the field of medical imaging and necessary to obtain detective quantum efficiency (DQE) which represents overall performance of the detector signal-to-noise ratio. However, the accurate measurement of MTF is still not easy because of geometric effect, electric noise, quantum noise, and truncation error. Therefore, in order to improve accuracy of MTF, four experimental methods were tested in this study such as changing the tube current, applying smoothing method in edge spread function (ESF), adjusting line spread function (LSF) range, and changing tube angle. Our results showed that MTF's fluctuation was decreased by high tube current and smoothing method. However, tube current should not exceed detector saturation and smoothing in ESF causes a distortion in ESF and MTF. In addition, decreasing LSF range diminished fluctuation and the number of sampling in MTF and high tube angle generates degradation in MTF. Based on these results, excessively low tube current and the smoothing method should be avoided. Also, optimal range of LSF considering reduction of fluctuation and the number of sampling in MTF was necessary and precise tube angle is essential to obtain an accurate MTF. In conclusion, our results demonstrated that accurate MTF can be acquired.

  18. Surgical accuracy under virtual reality-enhanced ultrasound guidance: an in vitro epicardial dynamic study.

    PubMed

    Linte, Cristian A; Wiles, Andrew D; Moore, John; Wedlake, Chris; Peters, Terry M

    2008-01-01

    In the context of our ongoing objective to reduce morbidity associated with cardiac interventions, minimizing invasiveness has inevitably led to more limited visual access to the target tissues. To ameliorate these challenges, we provide the surgeons with a complex visualization environment that integrates interventional ultrasound imaging augmented with pre-operative anatomical models and virtual surgical instruments within a virtual reality environment. In this paper we present an in vitro study on a cardiac phantom aimed at assessing the feasibility and targeting accuracy of our surgical system in comparison to traditional ultrasound imaging for intra-operative surgical guidance. The 'therapy delivery' was modeled in the context of a blinded procedure, mimicking a closed-chest intervention. Four users navigated a tracked pointer to a target, under guidance provide by either US imaging or virtual reality-enhanced ultrasound. A 2.8 mm RMS targeting error was achieved using our novel surgical system, which is adequate from both a clinical and engineering perspective, under the inherent procedure requirements and limitations of the system. PMID:19162594

  19. Accuracy, Effectiveness and Improvement of Vibration-Based Maintenance in Paper Mills: Case Studies

    NASA Astrophysics Data System (ADS)

    AL-NAJJAR, B.

    2000-01-01

    Many current vibration-based maintenance (VBM) policies for rolling element bearings do not use as much as possible of their useful lives. Evidence and indications to prolong the bearings' mean effective lives by using more accurate diagnosis and prognosis are confirmed when faulty bearing installation, faulty machinery design, harsh environmental condition and when a bearing is replaced as soon as its vibration level exceeds the normal. Analysis of data from roller bearings at two paper mills suggests that longer bearing lives can be safely achieved by increasing the accuracy of the vibration data. This paper relates bearing failure modes to the observed vibration spectra and their development patterns over the bearings' lives. A systematic approach, which describes the objectives and performance of studies in two Swedish paper mills, is presented. Explanations of the mechanisms behind some frequent modes of early failure and ways to avoid them are suggested. It is shown theoretically, and partly confirmed by the analysis of (unfortunately incomplete) data from two paper mills over many years, that accurate prediction of remaining bearing life requires: (a) enough vibration measurements, (b) numerate records of operating conditions, (c) better discrimination between frequencies in the spectrum and (d) correlation of (b) and (c). This is because life prediction depends on precise knowledge of primary, harmonic and side-band frequency amplitudes and their development over time. Further, the available data, which are collected from relevant plant activities, can be utilized to perform cyclic improvements in diagnosis, prognosis, experience and economy.

  20. Diagnostic accuracy of loop-mediated isothermal amplification in detection of Clostridium difficile in stool samples: a meta-analysis

    PubMed Central

    Wei, Chen; Yang-Ming, Li; Shan, Luo; Yi-Ming, Zhong

    2015-01-01

    Introduction Clostridium difficile infection (CDI) remains a diagnostic challenge for clinicians. More recently, loop-mediated isothermal amplification (LAMP) has become readily available for the diagnosis of CDI, and many studies have investigated the usefulness of LAMP for rapid and accurate diagnosis of CDI. However, the overall diagnostic accuracy of LAMP for CDI remains unclear. In this meta-analysis, our aim was to establish the overall diagnostic accuracy of LAMP in detection of Clostridium difficile (CD) in stool samples. Material and methods A search was done in PubMed, MEDLINE, EMBASE and Cochrane Library databases up to February 2014 to identify published studies that evaluated the diagnostic role of LAMP for CD. Methodological quality was assessed according to the quality assessment for studies of diagnostic accuracy (QUADAS) instrument. The sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) were pooled statistically using random effects models. Statistical analysis was performed by employing Meta-Disc 1.4 software. Summary receiver operating characteristic (SROC) curves were used to summarize overall test performance. Funnel plots were used to test the potential publication bias. Result A total of 9 studies met inclusion criteria for the present meta-analysis. The pooled SEN and SPE for diagnosing CD were 0.93 (95% CI: 0.91–0.95) and 0.98 (95% CI: 0.98–0.99), respectively. The PLR was 47.72 (95% CI: 15.10–150.82), NLR was 0.07 (95% CI: 0.04–0.14) and DOR was 745.19 (95% CI: 229.30−2421.72). The area under the ROC was 0.98. Meta-regression indicated that the total number of samples was a source of heterogeneity for LAMP in detection of CD. The funnel plots suggested no publication bias. Conclusions The LAMP meets the minimum desirable characteristics of a diagnostic test of SEN, SPE and other measures of accuracy in the diagnosis of CD, and it is suitable

  1. Functional Knowledge Transfer for High-accuracy Prediction of Under-studied Biological Processes

    PubMed Central

    Rowland, Jessica; Guan, Yuanfang; Bongo, Lars A.; Burdine, Rebecca D.; Troyanskaya, Olga G.

    2013-01-01

    A key challenge in genetics is identifying the functional roles of genes in pathways. Numerous functional genomics techniques (e.g. machine learning) that predict protein function have been developed to address this question. These methods generally build from existing annotations of genes to pathways and thus are often unable to identify additional genes participating in processes that are not already well studied. Many of these processes are well studied in some organism, but not necessarily in an investigator's organism of interest. Sequence-based search methods (e.g. BLAST) have been used to transfer such annotation information between organisms. We demonstrate that functional genomics can complement traditional sequence similarity to improve the transfer of gene annotations between organisms. Our method transfers annotations only when functionally appropriate as determined by genomic data and can be used with any prediction algorithm to combine transferred gene function knowledge with organism-specific high-throughput data to enable accurate function prediction. We show that diverse state-of-art machine learning algorithms leveraging functional knowledge transfer (FKT) dramatically improve their accuracy in predicting gene-pathway membership, particularly for processes with little experimental knowledge in an organism. We also show that our method compares favorably to annotation transfer by sequence similarity. Next, we deploy FKT with state-of-the-art SVM classifier to predict novel genes to 11,000 biological processes across six diverse organisms and expand the coverage of accurate function predictions to processes that are often ignored because of a dearth of annotated genes in an organism. Finally, we perform in vivo experimental investigation in Danio rerio and confirm the regulatory role of our top predicted novel gene, wnt5b, in leftward cell migration during heart development. FKT is immediately applicable to many bioinformatics techniques and will

  2. Hepatic perfusion in a tumor model using DCE-CT: an accuracy and precision study

    NASA Astrophysics Data System (ADS)

    Stewart, Errol E.; Chen, Xiaogang; Hadway, Jennifer; Lee, Ting-Yim

    2008-08-01

    In the current study we investigate the accuracy and precision of hepatic perfusion measurements based on the Johnson and Wilson model with the adiabatic approximation. VX2 carcinoma cells were implanted into the livers of New Zealand white rabbits. Simultaneous dynamic contrast-enhanced computed tomography (DCE-CT) and radiolabeled microsphere studies were performed under steady-state normo-, hyper- and hypo-capnia. The hepatic arterial blood flows (HABF) obtained using both techniques were compared with ANOVA. The precision was assessed by the coefficient of variation (CV). Under normo-capnia the microsphere HABF were 51.9 ± 4.2, 40.7 ± 4.9 and 99.7 ± 6.0 ml min-1 (100 g)-1 while DCE-CT HABF were 50.0 ± 5.7, 37.1 ± 4.5 and 99.8 ± 6.8 ml min-1 (100 g)-1 in normal tissue, tumor core and rim, respectively. There were no significant differences between HABF measurements obtained with both techniques (P > 0.05). Furthermore, a strong correlation was observed between HABF values from both techniques: slope of 0.92 ± 0.05, intercept of 4.62 ± 2.69 ml min-1 (100 g)-1 and R2 = 0.81 ± 0.05 (P < 0.05). The Bland-Altman plot comparing DCE-CT and microsphere HABF measurements gives a mean difference of -0.13 ml min-1 (100 g)-1, which is not significantly different from zero. DCE-CT HABF is precise, with CV of 5.7, 24.9 and 1.4% in the normal tissue, tumor core and rim, respectively. Non-invasive measurement of HABF with DCE-CT is accurate and precise. DCE-CT can be an important extension of CT to assess hepatic function besides morphology in liver diseases.

  3. Application accuracy study of a semipermanent fiducial system for frameless stereotaxis.

    PubMed

    Vinas, F C; Zamorano, L; Buciuc, R; Li, Q H; Shamsa, F; Jiang, Z; Diaz, F G

    1997-01-01

    The accuracy of a semipermanent fiducial marker system developed at Wayne State University in collaboration with Fisher-Leibinger (Freiburg, Germany) was compared with reference to a standard stereotactic frame (Zamorano-Dujovny Localizing Unit; Fisher-Leibinger). For each patient in our study, 10 semipermanent markers were placed on the skull through a small incision and a pilot hole drilled for the marker; five markers were used for registration, and five were used for comparison. Gadolinium-enhanced magnetic resonance imaging was performed, and, upon registration using both ring and fiducial markers, 184 random points were collected by infrared digitization. All three-dimensional measurements (x, y, z) were converted into distance values correlating each value to the origin by the formula dij = SQRT (xij2 + yij2 + zij2). The mean difference of fiducial coordinates vs. absolute image coordinates was 1.72 +/- 0.42 mm (P = .0001), implying no significant difference. The mean difference in dij of the stereotactic ring coordinates vs. the absolute image coordinates was 3.35 +/- 0.59 mm (P = .00011). The mean difference in the fiducial markers vs. the stereotactic ring coordinates was 2.95 +/- 0.45 mm (P = .0001). All tests were declared significant at alpha = .016. The combination of interactive guidance with semipermanent fiducial markers allows for accurate localization of intracranial targets (as accurate or even more accurate than the stereotactic frame). Semipermanent fiducial markers facilitate the procedure logistically, allow for staged procedures (i.e., at the skull base or in epilepsy), and provide access for combined supra- and infratentorial approaches. We believe that the semipermanent fiducial markers system might represent an important development leading toward widespread use of interactive image guidance in conventional neurosurgery. PMID:9484586

  4. Alaska Case Study: Scientists Venturing Into Field with Journalists Improves Accuracy

    NASA Astrophysics Data System (ADS)

    Ekwurzel, B.; Detjen, J.; Hayes, R.; Nurnberger, L.; Pavangadkar, A.; Poulson, D.

    2008-12-01

    Issues such as climate change, stem cell research, public health vaccination, etc., can be fraught with public misunderstanding, myths, as well as deliberate distortions of the fundamental science. Journalists are adept at creating print, radio, and video content that can be both compelling and informative to the public. Yet most scientists have little time or training to devote to developing media content for the public and spend little time with journalists who cover science stories. We conducted a case study to examine whether the time and funding invested in exposing journalists to scientists in the field over several days would improve accuracy of media stories about complex scientific topics. Twelve journalists were selected from the 70 who applied for a four-day environmental journalism fellowship in Alaska. The final group achieved the goal of a broad geographic spectrum of the media outlets (small regional to large national organizations), medium (print, radio, online), and experience (early career to senior producers). Reporters met with a diverse group of scientists. The lessons learned and successful techniques will be presented. Initial results demonstrate that stories were highly accurate and rich with audio or visual content for lay audiences. The journalists have also maintained contact with the scientists, asking for leads on emerging stories and seeking new experts that can assist in their reporting. Science-based institutions should devote more funding to foster direct journalist-scientist interactions in the lab and field. These positive goals can be achieved: (1) more accurate dissemination of science information to the public; (2) a broader portion of the scientific community will become a resource to journalists instead of the same eloquent few in the community; (3) scientists will appreciate the skill and pressures of those who survive the media downsizing and provide media savvy content; and (4) the public may incorporate science evidence

  5. Accuracy of migrant landbird habitat maps produced from LANDSAT TM data: Two case studies in southern Belize

    USGS Publications Warehouse

    Spruce, J.P.; Sader, S.; Robbins, C.S.; Dowell, B.A.; Wilson, Marcia H.; Sader, Steven A.

    1995-01-01

    The study investigated the utility of Landsat TM data applied to produce geo-referenced habitat maps for two study areas (Toledo and Stann Creek). Locational and non-site-specific map accuracy was evaluated by stratified random sampling and statistical analysis of satellite classification (SCR) versus air photo interpretation results (PIR) for the overall classification and individual classes. The effect of classification scheme specificity on map accuracy was also assessed. A decision criteria was developed for the minimum acceptable level of map performance (i.e., classification accuracy and scheme specificity). A satellite map was deemed acceptable if it has a useful degree of classification specificity, plus either an adequate overall locational agreement (< 70%) and/or non-site specific agreement (Chi Square goodness of fit test results indicating insufficient evidence to reject the null hypothesis that the overall classification distribution for the SCR and PIR are equal). For the most detailed revised classification, overall locational accuracy ranges from 52% (5 classes) for the Toledo to 63% (9 classes) for the Stann Creek. For the least detailed revised classification, overall locational accuracy ranges from 91% (2 classes) for Toledo to 86% (5 classes) for Stann Creek. Considering both location and non-site-specific accuracy results, the most detailed yet insufficient accurate classification for both sites includes low/medium/tall broadleaf forest, broadleaf forest scrub and herb-dominated openings. For these classifications, the overall locational accuracy is 72% for Toledo (4 classes) and 75% for Stann Creek (7 classes). This level of classification detail is suitable for aiding many analyses of migrant landbird habitat use.

  6. Accuracy of Person-Fit Statistics: A Monte Carlo Study of the Influence of Aberrance Rates

    ERIC Educational Resources Information Center

    St-Onge, Christina; Valois, Pierre; Abdous, Belkacem; Germain, Stephane

    2011-01-01

    Using a Monte Carlo experimental design, this research examined the relationship between answer patterns' aberrance rates and person-fit statistics (PFS) accuracy. It was observed that as the aberrance rate increased, the detection rates of PFS also increased until, in some situations, a peak was reached and then the detection rates of PFS…

  7. Accuracy of Range Restriction Correction with Multiple Imputation in Small and Moderate Samples: A Simulation Study

    ERIC Educational Resources Information Center

    Pfaffel, Andreas; Spiel, Christiane

    2016-01-01

    Approaches to correcting correlation coefficients for range restriction have been developed under the framework of large sample theory. The accuracy of missing data techniques for correcting correlation coefficients for range restriction has thus far only been investigated with relatively large samples. However, researchers and evaluators are…

  8. Applying Signal-Detection Theory to the Study of Observer Accuracy and Bias in Behavioral Assessment

    ERIC Educational Resources Information Center

    Lerman, Dorothea C.; Tetreault, Allison; Hovanetz, Alyson; Bellaci, Emily; Miller, Jonathan; Karp, Hilary; Mahmood, Angela; Strobel, Maggie; Mullen, Shelley; Keyl, Alice; Toupard, Alexis

    2010-01-01

    We evaluated the feasibility and utility of a laboratory model for examining observer accuracy within the framework of signal-detection theory (SDT). Sixty-one individuals collected data on aggression while viewing videotaped segments of simulated teacher-child interactions. The purpose of Experiment 1 was to determine if brief feedback and…

  9. Accuracy of stated energy contents of restaurant foods in a multi-site study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Context National recommendations for prevention and treatment of obesity emphasize reducing energy intake. Foods purchased in restaurants provide approximately 35% of daily energy intake, but the accuracy of information on the energy contents of these foods is unknown. Objective To examine the a...

  10. A study of the accuracy of wing calculations based on different schemes

    NASA Astrophysics Data System (ADS)

    Putilin, S. I.; Savchenko, V. T.

    Solutions obtained for the same flow problem using different vortex and computation point distribution laws are presented. The problem considered here is the plane problem for a plate near a circular contour, which is relevant to the design of wings with optimal load distribution and low aspect ratio wings in a bounded fluid. Ways to improve the accuracy of the results are discussed.

  11. Influence of Blood on the Accuracy of Raypex 5 and Root ZX Electronic Foramen Locators: An In Vivo Study.

    PubMed

    Saatchi, Masoud; Aminozarbian, Mohammad Ghasem; Noormohammadi, Hamid; Baghaei, Badri

    2016-01-01

    The aim of this study was to evaluate in vivo the accuracy of the Raypex 5 and Root ZX electronic foramen locators (EFLs) in the presence of blood in the root canal space. Forty single-canal teeth scheduled for extraction were selected. Access cavity was prepared and coronal enlargement was carried out. Approximately two drops of blood were collected by finger prick and injected into the root canal space. The electronic working length (EWL) of each tooth by each device was established twice before (NB group) and after (WB group) injecting blood into the root canal. The tooth was extracted and the actual working length (AWL) was determined. Data were analyzed using McNemar's test. The accuracy rates of Raypex 5 and Root ZX within 0.5 mm in the NB group were 88.9% and 91.5%, with 83.3% and 86.2% in the WB group, respectively. There were no significant differences between the accuracy of each EFL in the two groups (p>0.05). Considering the NB and WB groups, there were no statistically significant differences in the accuracy of the EFLs (p>0.05). The presence of blood in the root canal space did not influence the accuracy of the EFLs.

  12. Influence of Blood on the Accuracy of Raypex 5 and Root ZX Electronic Foramen Locators: An In Vivo Study.

    PubMed

    Saatchi, Masoud; Aminozarbian, Mohammad Ghasem; Noormohammadi, Hamid; Baghaei, Badri

    2016-01-01

    The aim of this study was to evaluate in vivo the accuracy of the Raypex 5 and Root ZX electronic foramen locators (EFLs) in the presence of blood in the root canal space. Forty single-canal teeth scheduled for extraction were selected. Access cavity was prepared and coronal enlargement was carried out. Approximately two drops of blood were collected by finger prick and injected into the root canal space. The electronic working length (EWL) of each tooth by each device was established twice before (NB group) and after (WB group) injecting blood into the root canal. The tooth was extracted and the actual working length (AWL) was determined. Data were analyzed using McNemar's test. The accuracy rates of Raypex 5 and Root ZX within 0.5 mm in the NB group were 88.9% and 91.5%, with 83.3% and 86.2% in the WB group, respectively. There were no significant differences between the accuracy of each EFL in the two groups (p>0.05). Considering the NB and WB groups, there were no statistically significant differences in the accuracy of the EFLs (p>0.05). The presence of blood in the root canal space did not influence the accuracy of the EFLs. PMID:27224570

  13. Comparative Accuracy Evaluation of Fine-Scale Global and Local Digital Surface Models: The Tshwane Case Study I

    NASA Astrophysics Data System (ADS)

    Breytenbach, A.

    2016-10-01

    Conducted in the City of Tshwane, South Africa, this study set about to test the accuracy of DSMs derived from different remotely sensed data locally. VHR digital mapping camera stereo-pairs, tri-stereo imagery collected by a Pléiades satellite and data detected from the Tandem-X InSAR satellite configuration were fundamental in the construction of seamless DSM products at different postings, namely 2 m, 4 m and 12 m. The three DSMs were sampled against independent control points originating from validated airborne LiDAR data. The reference surfaces were derived from the same dense point cloud at grid resolutions corresponding to those of the samples. The absolute and relative positional accuracies were computed using well-known DEM error metrics and accuracy statistics. Overall vertical accuracies were also assessed and compared across seven slope classes and nine primary land cover classes. Although all three DSMs displayed significantly more vertical errors where solid waterbodies, dense natural and/or alien woody vegetation and, in a lesser degree, urban residential areas with significant canopy cover were encountered, all three surpassed their expected positional accuracies overall.

  14. Design and Preliminary Accuracy Studies of an MRI-Guided Transrectal Prostate Intervention System

    PubMed Central

    Krieger, Axel; Csoma, Csaba; Iordachita, Iulian I.; Guion, Peter; Singh, Anurag K.; Fichtinger, Gabor; Whitcomb, Louis L.

    2012-01-01

    This paper reports a novel system for magnetic resonance imaging (MRI) guided transrectal prostate interventions, such as needle biopsy, fiducial marker placement, and therapy delivery. The system utilizes a hybrid tracking method, comprised of passive fiducial tracking for initial registration and subsequent incremental motion measurement along the degrees of freedom using fiber-optical encoders and mechanical scales. Targeting accuracy of the system is evaluated in prostate phantom experiments. Achieved targeting accuracy and procedure times were found to compare favorably with existing systems using passive and active tracking methods. Moreover, the portable design of the system using only standard MRI image sequences and minimal custom scanner interfacing allows the system to be easily used on different MRI scanners. PMID:18044553

  15. Recognition Accuracy Using 3D Endoscopic Images for Superficial Gastrointestinal Cancer: A Crossover Study

    PubMed Central

    Kaise, Mitsuru; Kikuchi, Daisuke; Iizuka, Toshiro; Fukuma, Yumiko; Kuribayashi, Yasutaka; Tanaka, Masami; Toba, Takahito; Furuhata, Tsukasa; Yamashita, Satoshi; Matsui, Akira; Mitani, Toshifumi; Hoteya, Shu

    2016-01-01

    Aim. To determine whether 3D endoscopic images improved recognition accuracy for superficial gastrointestinal cancer compared with 2D images. Methods. We created an image catalog using 2D and 3D images of 20 specimens resected by endoscopic submucosal dissection. The twelve participants were allocated into two groups. Group 1 evaluated only 2D images at first, group 2 evaluated 3D images, and, after an interval of 2 weeks, group 1 next evaluated 3D and group 2 evaluated 2D images. The evaluation items were as follows: (1) diagnostic accuracy of the tumor extent and (2) confidence levels in assessing (a) tumor extent, (b) morphology, (c) microsurface structure, and (d) comprehensive recognition. Results. The use of 3D images resulted in an improvement in diagnostic accuracy in both group 1 (2D: 76.9%, 3D: 78.6%) and group 2 (2D: 79.9%, 3D: 83.6%), with no statistically significant difference. The confidence levels were higher for all items ((a) to (d)) when 3D images were used. With respect to experience, the degree of the improvement showed the following trend: novices > trainees > experts. Conclusions. By conversion into 3D images, there was a significant improvement in the diagnostic confidence level for superficial tumors, and the improvement was greater in individuals with lower endoscopic expertise. PMID:27597863

  16. Recognition Accuracy Using 3D Endoscopic Images for Superficial Gastrointestinal Cancer: A Crossover Study

    PubMed Central

    Kaise, Mitsuru; Kikuchi, Daisuke; Iizuka, Toshiro; Fukuma, Yumiko; Kuribayashi, Yasutaka; Tanaka, Masami; Toba, Takahito; Furuhata, Tsukasa; Yamashita, Satoshi; Matsui, Akira; Mitani, Toshifumi; Hoteya, Shu

    2016-01-01

    Aim. To determine whether 3D endoscopic images improved recognition accuracy for superficial gastrointestinal cancer compared with 2D images. Methods. We created an image catalog using 2D and 3D images of 20 specimens resected by endoscopic submucosal dissection. The twelve participants were allocated into two groups. Group 1 evaluated only 2D images at first, group 2 evaluated 3D images, and, after an interval of 2 weeks, group 1 next evaluated 3D and group 2 evaluated 2D images. The evaluation items were as follows: (1) diagnostic accuracy of the tumor extent and (2) confidence levels in assessing (a) tumor extent, (b) morphology, (c) microsurface structure, and (d) comprehensive recognition. Results. The use of 3D images resulted in an improvement in diagnostic accuracy in both group 1 (2D: 76.9%, 3D: 78.6%) and group 2 (2D: 79.9%, 3D: 83.6%), with no statistically significant difference. The confidence levels were higher for all items ((a) to (d)) when 3D images were used. With respect to experience, the degree of the improvement showed the following trend: novices > trainees > experts. Conclusions. By conversion into 3D images, there was a significant improvement in the diagnostic confidence level for superficial tumors, and the improvement was greater in individuals with lower endoscopic expertise.

  17. Recognition Accuracy Using 3D Endoscopic Images for Superficial Gastrointestinal Cancer: A Crossover Study.

    PubMed

    Nomura, Kosuke; Kaise, Mitsuru; Kikuchi, Daisuke; Iizuka, Toshiro; Fukuma, Yumiko; Kuribayashi, Yasutaka; Tanaka, Masami; Toba, Takahito; Furuhata, Tsukasa; Yamashita, Satoshi; Matsui, Akira; Mitani, Toshifumi; Hoteya, Shu

    2016-01-01

    Aim. To determine whether 3D endoscopic images improved recognition accuracy for superficial gastrointestinal cancer compared with 2D images. Methods. We created an image catalog using 2D and 3D images of 20 specimens resected by endoscopic submucosal dissection. The twelve participants were allocated into two groups. Group 1 evaluated only 2D images at first, group 2 evaluated 3D images, and, after an interval of 2 weeks, group 1 next evaluated 3D and group 2 evaluated 2D images. The evaluation items were as follows: (1) diagnostic accuracy of the tumor extent and (2) confidence levels in assessing (a) tumor extent, (b) morphology, (c) microsurface structure, and (d) comprehensive recognition. Results. The use of 3D images resulted in an improvement in diagnostic accuracy in both group 1 (2D: 76.9%, 3D: 78.6%) and group 2 (2D: 79.9%, 3D: 83.6%), with no statistically significant difference. The confidence levels were higher for all items ((a) to (d)) when 3D images were used. With respect to experience, the degree of the improvement showed the following trend: novices > trainees > experts. Conclusions. By conversion into 3D images, there was a significant improvement in the diagnostic confidence level for superficial tumors, and the improvement was greater in individuals with lower endoscopic expertise.

  18. Recognition Accuracy Using 3D Endoscopic Images for Superficial Gastrointestinal Cancer: A Crossover Study.

    PubMed

    Nomura, Kosuke; Kaise, Mitsuru; Kikuchi, Daisuke; Iizuka, Toshiro; Fukuma, Yumiko; Kuribayashi, Yasutaka; Tanaka, Masami; Toba, Takahito; Furuhata, Tsukasa; Yamashita, Satoshi; Matsui, Akira; Mitani, Toshifumi; Hoteya, Shu

    2016-01-01

    Aim. To determine whether 3D endoscopic images improved recognition accuracy for superficial gastrointestinal cancer compared with 2D images. Methods. We created an image catalog using 2D and 3D images of 20 specimens resected by endoscopic submucosal dissection. The twelve participants were allocated into two groups. Group 1 evaluated only 2D images at first, group 2 evaluated 3D images, and, after an interval of 2 weeks, group 1 next evaluated 3D and group 2 evaluated 2D images. The evaluation items were as follows: (1) diagnostic accuracy of the tumor extent and (2) confidence levels in assessing (a) tumor extent, (b) morphology, (c) microsurface structure, and (d) comprehensive recognition. Results. The use of 3D images resulted in an improvement in diagnostic accuracy in both group 1 (2D: 76.9%, 3D: 78.6%) and group 2 (2D: 79.9%, 3D: 83.6%), with no statistically significant difference. The confidence levels were higher for all items ((a) to (d)) when 3D images were used. With respect to experience, the degree of the improvement showed the following trend: novices > trainees > experts. Conclusions. By conversion into 3D images, there was a significant improvement in the diagnostic confidence level for superficial tumors, and the improvement was greater in individuals with lower endoscopic expertise. PMID:27597863

  19. Additional studies of forest classification accuracy as influenced by multispectral scanner spatial resolution

    NASA Technical Reports Server (NTRS)

    Sadowski, F. E.; Sarno, J. E.

    1976-01-01

    First, an analysis of forest feature signatures was used to help explain the large variation in classification accuracy that can occur among individual forest features for any one case of spatial resolution and the inconsistent changes in classification accuracy that were demonstrated among features as spatial resolution was degraded. Second, the classification rejection threshold was varied in an effort to reduce the large proportion of unclassified resolution elements that previously appeared in the processing of coarse resolution data when a constant rejection threshold was used for all cases of spatial resolution. For the signature analysis, two-channel ellipse plots showing the feature signature distributions for several cases of spatial resolution indicated that the capability of signatures to correctly identify their respective features is dependent on the amount of statistical overlap among signatures. Reductions in signature variance that occur in data of degraded spatial resolution may not necessarily decrease the amount of statistical overlap among signatures having large variance and small mean separations. Features classified by such signatures may thus continue to have similar amounts of misclassified elements in coarser resolution data, and thus, not necessarily improve in classification accuracy.

  20. Classification Accuracy of MMPI-2 Validity Scales in the Detection of Pain-Related Malingering: A Known-Groups Study

    ERIC Educational Resources Information Center

    Bianchini, Kevin J.; Etherton, Joseph L.; Greve, Kevin W.; Heinly, Matthew T.; Meyers, John E.

    2008-01-01

    The purpose of this study was to determine the accuracy of "Minnesota Multiphasic Personality Inventory" 2nd edition (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) validity indicators in the detection of malingering in clinical patients with chronic pain using a hybrid clinical-known groups/simulator design. The sample consisted…

  1. The Diagnostic Accuracy of Serologic and Molecular Methods for Detecting Visceral Leishmaniasis in HIV Infected Patients: Meta-Analysis

    PubMed Central

    Cota, Gláucia Fernandes; de Sousa, Marcos Roberto; Demarqui, Fábio Nogueira; Rabello, Ana

    2012-01-01

    Background Human visceral leishmaniasis (VL), a potentially fatal disease, has emerged as an important opportunistic condition in HIV infected patients. In immunocompromised patients, serological investigation is considered not an accurate diagnostic method for VL diagnosis and molecular techniques seem especially promising. Objective This work is a comprehensive systematic review and meta-analysis to evaluate the accuracy of serologic and molecular tests for VL diagnosis specifically in HIV-infected patients. Methods Two independent reviewers searched PubMed and LILACS databases. The quality of studies was assessed by QUADAS score. Sensitivity and specificity were pooled separately and compared with overall accuracy measures: diagnostic odds ratio (DOR) and symmetric summary receiver operating characteristic (sROC). Results Thirty three studies recruiting 1,489 patients were included. The following tests were evaluated: Immunofluorescence Antibody Test (IFAT), Enzyme linked immunosorbent assay (ELISA), immunoblotting (Blot), direct agglutination test (DAT) and polimerase chain reaction (PCR) in whole blood and bone marrow. Most studies were carried out in Europe. Serological tests varied widely in performance, but with overall limited sensitivity. IFAT had poor sensitivity ranging from 11% to 82%. DOR (95% confidence interval) was higher for DAT 36.01 (9.95–130.29) and Blot 27.51 (9.27–81.66) than for IFAT 7.43 (3.08–1791) and ELISA 3.06 (0.71–13.10). PCR in whole blood had the highest DOR: 400.35 (58.47–2741.42). The accuracy of PCR based on Q-point was 0.95; 95%CI 0.92–0.97, which means good overall performance. Conclusion Based mainly on evidence gained by infection with Leishmania infantum chagasi, serological tests should not be used to rule out a diagnosis of VL among the HIV-infected, but a positive test at even low titers has diagnostic value when combined with the clinical case definition. Considering the available evidence, tests based on DNA

  2. Accuracy of magnetic resonance imaging for measuring maturing cartilage: A phantom study

    PubMed Central

    McKinney, Jennifer R; Sussman, Marshall S; Moineddin, Rahim; Amirabadi, Afsaneh; Rayner, Tammy; Doria, Andrea S

    2016-01-01

    OBJECTIVES: To evaluate the accuracy of magnetic resonance imaging measurements of cartilage tissue-mimicking phantoms and to determine a combination of magnetic resonance imaging parameters to optimize accuracy while minimizing scan time. METHOD: Edge dimensions from 4 rectangular agar phantoms ranging from 10.5 to 14.5 mm in length and 1.25 to 5.5 mm in width were independently measured by two readers using a steel ruler. Coronal T1 spin echo (T1 SE), fast spoiled gradient-recalled echo (FSPGR) and multiplanar gradient-recalled echo (GRE MPGR) sequences were used to obtain phantom images on a 1.5-T scanner. RESULTS: Inter- and intra-reader reliability were high for both direct measurements and for magnetic resonance imaging measurements of phantoms. Statistically significant differences were noted between the mean direct measurements and the mean magnetic resonance imaging measurements for phantom 1 when using a GRE MPGR sequence (512x512 pixels, 1.5-mm slice thickness, 5:49 min scan time), while borderline differences were noted for T1 SE sequences with the following parameters: 320x320 pixels, 1.5-mm slice thickness, 6:11 min scan time; 320x320 pixels, 4-mm slice thickness, 6:11 min scan time; and 512x512 pixels, 1.5-mm slice thickness, 9:48 min scan time. Borderline differences were also noted when using a FSPGR sequence with 512x512 pixels, a 1.5-mm slice thickness and a 3:36 min scan time. CONCLUSIONS: FSPGR sequences, regardless of the magnetic resonance imaging parameter combination used, provided accurate measurements. The GRE MPGR sequence using 512x512 pixels, a 1.5-mm slice thickness and a 5:49 min scan time and, to a lesser degree, all tested T1 SE sequences produced suboptimal accuracy when measuring the widest phantom. PMID:27464298

  3. A statistical study of the surface accuracy of a planar truss beam

    NASA Technical Reports Server (NTRS)

    Kenner, W. Scott; Fichter, W. B.

    1990-01-01

    Surface error statistics for single-layer and double-layer planar truss beams with random member-length errors were calculated using a Monte-Carlo technique in conjunction with finite-element analysis. Surface error was calculated in terms of the normal distance from a regression line to the surface nodes of the distorted beam. Results for both single-layer and double-layer beams indicate that a minimum root-mean-square surface error can be achieved by optimizing the depth-to-length ratio of a truss beam. The statically indeterminate double-layer beams can provide greater surface accuracy, though at the expense of significantly greater complexity.

  4. Agricultural case studies of classification accuracy, spectral resolution, and model over-fitting.

    PubMed

    Nansen, Christian; Geremias, Leandro Delalibera; Xue, Yingen; Huang, Fangneng; Parra, Jose Roberto

    2013-11-01

    This paper describes the relationship between spectral resolution and classification accuracy in analyses of hyperspectral imaging data acquired from crop leaves. The main scope is to discuss and reduce the risk of model over-fitting. Over-fitting of a classification model occurs when too many and/or irrelevant model terms are included (i.e., a large number of spectral bands), and it may lead to low robustness/repeatability when the classification model is applied to independent validation data. We outline a simple way to quantify the level of model over-fitting by comparing the observed classification accuracies with those obtained from explanatory random data. Hyperspectral imaging data were acquired from two crop-insect pest systems: (1) potato psyllid (Bactericera cockerelli) infestations of individual bell pepper plants (Capsicum annuum) with the acquisition of hyperspectral imaging data under controlled-light conditions (data set 1), and (2) sugarcane borer (Diatraea saccharalis) infestations of individual maize plants (Zea mays) with the acquisition of hyperspectral imaging data from the same plants under two markedly different image-acquisition conditions (data sets 2a and b). For each data set, reflectance data were analyzed based on seven spectral resolutions by dividing 160 spectral bands from 405 to 907 nm into 4, 16, 32, 40, 53, 80, or 160 bands. In the two data sets, similar classification results were obtained with spectral resolutions ranging from 3.1 to 12.6 nm. Thus, the size of the initial input data could be reduced fourfold with only a negligible loss of classification accuracy. In the analysis of data set 1, several validation approaches all demonstrated consistently that insect-induced stress could be accurately detected and that therefore there was little indication of model over-fitting. In the analyses of data set 2, inconsistent validation results were obtained and the observed classification accuracy (81.06%) was only a few percentage

  5. Comparative evaluation of dimensional accuracy of different polyvinyl siloxane putty-wash impression techniques-in vitro study.

    PubMed Central

    Dugal, Ramandeep; Railkar, Bhargavi; Musani, Smita

    2013-01-01

    Background: Dimensional accuracy when making impressions is crucial to the quality of fixed prosthodontic treatment, and the impression technique is a critical factor affecting this accuracy. The purpose of this in vitro study was to compare the dimensional accuracy of the casts obtained from one step double mix, two step double mix polyvinyl siloxane putty- wash impression techniques using three different spacer thicknesses (0.5mm, 1mm and 1.5mm), in order to determine the impression technique that displays the maximum linear dimensional accuracy. Materials & Methods: A Mild steel model with 2 abutment preparations was fabricated, and impressions were made 15 times with each technique. All impressions were made with an addition-reaction silicone impression material (Express, 3M ESPE) and customarily made perforated metal trays. The 1-step putty/light-body impressions were made with simultaneous use of putty and light-body materials. The 2-step putty/light-body impressions were made with 0.5-mm, 1mm and 1.5mm-thick metal-prefabricated spacer caps. The accuracy of the 4 different impression techniques was assessed by measuring 7 dimensions (intra- and inter abutment) (20-μm accuracy) on stone casts poured from the impressions of the mild steel model. The data were analyzed by one sample‘t’ test. Results: The stone dies obtained with all the techniques had significantly larger or smaller dimensions as compared to those of the mild steel model (P<0.05). The order for highest to lowest deviation from the mild steel model was: single step putty/light body, 2-step putty/light body with 0.5mm spacer thickness, 2-step putty/light body1.5mm spacer thickness, and 2-step putty/light body with 1mm spacer thickness. Significant differences among all of the groups for both absolute dimensions of the stone dies, and their standard deviations from the master model (P<0.05), were noted. Conclusions: The 2-step putty/light-body impression technique with 1mm spacer thickness was

  6. A retrospective study to validate an intraoperative robotic classification system for assessing the accuracy of kirschner wire (K-wire) placements with postoperative computed tomography classification system for assessing the accuracy of pedicle screw placements

    PubMed Central

    Tsai, Tai-Hsin; Wu, Dong-Syuan; Su, Yu-Feng; Wu, Chieh-Hsin; Lin, Chih-Lung

    2016-01-01

    Abstract This purpose of this retrospective study is validation of an intraoperative robotic grading classification system for assessing the accuracy of Kirschner-wire (K-wire) placements with the postoperative computed tomography (CT)-base classification system for assessing the accuracy of pedicle screw placements. We conducted a retrospective review of prospectively collected data from 35 consecutive patients who underwent 176 robotic assisted pedicle screws instrumentation at Kaohsiung Medical University Hospital from September 2014 to November 2015. During the operation, we used a robotic grading classification system for verifying the intraoperative accuracy of K-wire placements. Three months after surgery, we used the common CT-base classification system to assess the postoperative accuracy of pedicle screw placements. The distributions of accuracy between the intraoperative robot-assisted and various postoperative CT-based classification systems were compared using kappa statistics of agreement. The intraoperative accuracies of K-wire placements before and after repositioning were classified as excellent (131/176, 74.4% and 133/176, 75.6%, respectively), satisfactory (36/176, 20.5% and 41/176, 23.3%, respectively), and malpositioned (9/176, 5.1% and 2/176, 1.1%, respectively) In postoperative CT-base classification systems were evaluated. No screw placements were evaluated as unacceptable under any of these systems. Kappa statistics revealed no significant differences between the proposed system and the aforementioned classification systems (P <0.001). Our results revealed no significant differences between the intraoperative robotic grading system and various postoperative CT-based grading systems. The robotic grading classification system is a feasible method for evaluating the accuracy of K-wire placements. Using the intraoperative robot grading system to classify the accuracy of K-wire placements enables predicting the postoperative accuracy of

  7. A retrospective study to validate an intraoperative robotic classification system for assessing the accuracy of kirschner wire (K-wire) placements with postoperative computed tomography classification system for assessing the accuracy of pedicle screw placements.

    PubMed

    Tsai, Tai-Hsin; Wu, Dong-Syuan; Su, Yu-Feng; Wu, Chieh-Hsin; Lin, Chih-Lung

    2016-09-01

    This purpose of this retrospective study is validation of an intraoperative robotic grading classification system for assessing the accuracy of Kirschner-wire (K-wire) placements with the postoperative computed tomography (CT)-base classification system for assessing the accuracy of pedicle screw placements.We conducted a retrospective review of prospectively collected data from 35 consecutive patients who underwent 176 robotic assisted pedicle screws instrumentation at Kaohsiung Medical University Hospital from September 2014 to November 2015. During the operation, we used a robotic grading classification system for verifying the intraoperative accuracy of K-wire placements. Three months after surgery, we used the common CT-base classification system to assess the postoperative accuracy of pedicle screw placements. The distributions of accuracy between the intraoperative robot-assisted and various postoperative CT-based classification systems were compared using kappa statistics of agreement.The intraoperative accuracies of K-wire placements before and after repositioning were classified as excellent (131/176, 74.4% and 133/176, 75.6%, respectively), satisfactory (36/176, 20.5% and 41/176, 23.3%, respectively), and malpositioned (9/176, 5.1% and 2/176, 1.1%, respectively)In postoperative CT-base classification systems were evaluated. No screw placements were evaluated as unacceptable under any of these systems. Kappa statistics revealed no significant differences between the proposed system and the aforementioned classification systems (P <0.001).Our results revealed no significant differences between the intraoperative robotic grading system and various postoperative CT-based grading systems. The robotic grading classification system is a feasible method for evaluating the accuracy of K-wire placements. Using the intraoperative robot grading system to classify the accuracy of K-wire placements enables predicting the postoperative accuracy of pedicle screw

  8. A study on the grinding accuracy of a copy milling machine for dental use.

    PubMed

    Seido, T; Hasegawa, K; Kawada, E; Oda, Y

    1997-08-01

    In order to assess the relationship between the profiling pressure of a copy milling machine for dental use and the accuracy of the dimensions of the objects produced, a Celay System was used to profile a metal-cylinder model, and its dimensions were compared with the workpieces. The results showed that, when a cylindrical model with a diameter of 6 mm was subjected to freehand profiling, the mean processing error of the object produced was -0.026 mm, and the profiling pressure was 4.6 gf to 131.7 gf (mean: 76.6 gf). However, the fluctuations in profiling pressure decreased by 1/5 during profiling operations when accessories that fixed the profiling pressure and the profiling loci were used. Moreover, while the processing error when the model was profiled at a profiling pressure of 76 gf or less was a mere 0.005 mm, at 110 gf it rose to 0.022 mm. Based on the above, the processing error that occurred as a result of profiling pressure appeared to affect processing accuracy. On the basis of these findings, profiling as light weight must be performed with as possible in order to obtain accurate products using the copy milling machine for dental use, and the results suggested the necessity of attaching control devices to the copy milling machine to make accurate restorations.

  9. The effect of a low radiation CT protocol on accuracy of CT guided implant migration measurement: A cadaver study.

    PubMed

    Boettner, Friedrich; Sculco, Peter K; Lipman, Joseph; Saboeiro, Gregory; Renner, Lisa; Faschingbauer, Martin

    2016-04-01

    The current study compared the impact of low radiation CT protocols on the accuracy, repeatability, and inter- and intra-observer variability of implant migration studies in total hip arthroplasty. Two total hip replacements were performed in two human cadavers and six tantalum beads were inserted into the femur similar to radiostereometric analysis. Six different 28 mm heads (-3 mm, 0 mm, 2.5 mm, 5.0 mm, 7.5 mm, and 10 mm) were added to simulate five reproducible translations (maximum total point migration) of the center of the head. Three CT scans with varying levels of radiation were performed for each head position. The effective dose (mSv) was 3.8 mSv for Protocol A (standard protocol), 0.7 mSv for Protocol B and 1.6 mSv for Protocol C. Implant migration was measured in a 3-D analysis software (Geomagic Studio 7). The accuracy was 0.16 mm for CT Protocol A, 0.13 mm for Protocol B and 0.14 mm for Protocol C; The repeatability was 0.22 mm for CT Protocol A, 0.18 mm for Protocol B and 0.20 mm for Protocol C; ICC for inter observer reliability was 0.89, intra observer reliability was 0.95. The difference in accuracy between standard protocol A and the two low radiation protocols (B, C) was less than 0.05 mm. The accuracy, inter- and intra-observer reliability of all three CT protocols is comparable to radiostereometric analysis. Reducing the CT radiation exposure to numbers similar to an AP Pelvis radiograph (0.7 mSv protocol B) does not affect the accuracy of implant migration measurements. PMID:26425921

  10. The effect of a low radiation CT protocol on accuracy of CT guided implant migration measurement: A cadaver study.

    PubMed

    Boettner, Friedrich; Sculco, Peter K; Lipman, Joseph; Saboeiro, Gregory; Renner, Lisa; Faschingbauer, Martin

    2016-04-01

    The current study compared the impact of low radiation CT protocols on the accuracy, repeatability, and inter- and intra-observer variability of implant migration studies in total hip arthroplasty. Two total hip replacements were performed in two human cadavers and six tantalum beads were inserted into the femur similar to radiostereometric analysis. Six different 28 mm heads (-3 mm, 0 mm, 2.5 mm, 5.0 mm, 7.5 mm, and 10 mm) were added to simulate five reproducible translations (maximum total point migration) of the center of the head. Three CT scans with varying levels of radiation were performed for each head position. The effective dose (mSv) was 3.8 mSv for Protocol A (standard protocol), 0.7 mSv for Protocol B and 1.6 mSv for Protocol C. Implant migration was measured in a 3-D analysis software (Geomagic Studio 7). The accuracy was 0.16 mm for CT Protocol A, 0.13 mm for Protocol B and 0.14 mm for Protocol C; The repeatability was 0.22 mm for CT Protocol A, 0.18 mm for Protocol B and 0.20 mm for Protocol C; ICC for inter observer reliability was 0.89, intra observer reliability was 0.95. The difference in accuracy between standard protocol A and the two low radiation protocols (B, C) was less than 0.05 mm. The accuracy, inter- and intra-observer reliability of all three CT protocols is comparable to radiostereometric analysis. Reducing the CT radiation exposure to numbers similar to an AP Pelvis radiograph (0.7 mSv protocol B) does not affect the accuracy of implant migration measurements.

  11. Accuracy Study of the Space-Time CE/SE Method for Computational Aeroacoustics Problems Involving Shock Waves

    NASA Technical Reports Server (NTRS)

    Wang, Xiao Yen; Chang, Sin-Chung; Jorgenson, Philip C. E.

    1999-01-01

    The space-time conservation element and solution element(CE/SE) method is used to study the sound-shock interaction problem. The order of accuracy of numerical schemes is investigated. The linear model problem.govemed by the 1-D scalar convection equation, sound-shock interaction problem governed by the 1-D Euler equations, and the 1-D shock-tube problem which involves moving shock waves and contact surfaces are solved to investigate the order of accuracy of numerical schemes. It is concluded that the accuracy of the CE/SE numerical scheme with designed 2nd-order accuracy becomes 1st order when a moving shock wave exists. However, the absolute error in the CE/SE solution downstream of the shock wave is on the same order as that obtained using a fourth-order accurate essentially nonoscillatory (ENO) scheme. No special techniques are used for either high-frequency low-amplitude waves or shock waves.

  12. Accuracy studies with carbon clusters at the Penning trap mass spectrometer TRIGA-TRAP

    NASA Astrophysics Data System (ADS)

    Ketelaer, J.; Beyer, T.; Blaum, K.; Block, M.; Eberhardt, K.; Eibach, M.; Herfurth, F.; Smorra, C.; Nagy, Sz.

    2010-05-01

    Extensive cross-reference measurements of well-known frequency ratios using various sizes of carbon cluster ions 12Cn + (10≤n≤23) were performed to determine the effects limiting the accuracy of mass measurements at the Penning-trap facility TRIGA-TRAP. Two major contributions to the uncertainty of a mass measurement have been identified. Fluctuations of the magnetic field cause an uncertainty in the frequency ratio due to the required calibration by a reference ion of uf(νref)/νref = 6(2) × 10-11/min × Δt. A mass-dependent systematic shift of the frequency ratio of epsilonm(r)/r = -2.2(2) × 10-9 × (m-mref)/u has been found as well. Finally, the nuclide 197Au was used as a cross-check since its mass is already known with an uncertainty of 0.6 keV.

  13. Study on Improving the Accuracy of Satellite Measurement in Urban Areas

    NASA Astrophysics Data System (ADS)

    Matsushita, Takashi; Tanaka, Toshiyuki

    GPS/GNSS (Global Positioning System/Global Navigation Satellite System) is a 3D positioning system using space satellites for measuring a receiver's current position. Recently, many people use GPS as the navigation system in car and cellular phone, so the positioning accuracy of several meters is required to satisfy the user's need. However the measurement error reaches hundreds of meters in urban areas. One of the reasons is that the receiver fails to measure pseudo range accurately due to multipath from the buildings and so on. The other reason is that the satellite constellation is biased because of the decreasing number of observable satellites. Therefore, we proposed methods for reducing the multipath error and the lack of visible satellites. At the present day, although multipath error is reduced by the choke ring antenna and the correlators, this method has a problem that the antenna is expensive, big or complex. We devise methods to reduce the multipath error by only using measurement data. By these methods, we can reduce the size of the receiver and to use the satellite that contains the multipath error for the measurement. We achieved the improvement from 35.3m to 30.5m in 2drms by this method. We achieved about 69% improvement in 2drms and about 5% increase in measurement rate. We can describe that we succeeded not only in improving the measurement accuracy but also in increasing the measurement rate in urban area. The results show that our proposed method is effective in urban areas measurement.

  14. Diagnostic Accuracy of 2D-Shear Wave Elastography for Liver Fibrosis Severity: A Meta-Analysis

    PubMed Central

    Jiang, Tian’an; Tian, Guo; Zhao, Qiyu; Kong, Dexing; Cheng, Chao; Zhong, Liyun; Li, Lanjuan

    2016-01-01

    Purpose To evaluate the accuracy of shear wave elastography (SWE) in the quantitative diagnosis of liver fibrosis severity. Methods The published literatures were systematically retrieved from PubMed, Embase, Web of science and Scopus up to May 13th, 2016. Included studies reported the pooled sensitivity, specificity, positive and negative predictive values, as well as the diagnostic odds ratio of SWE in populations with liver fibrosis. A bivariate mixed-effects regression model was used, which was estimated by the I2 statistics. The quality of articles was evaluated by quality assessment of diagnostic accuracy studies (QUADAS). Results Thirteen articles including 2303 patients were qualified for the study. The pooled sensitivity and specificity of SWE for the diagnosis of liver fibrosis are as follows: ≥F1 0.76 (p<0.001, 95% CI, 0.71–0.81, I2 = 75.33%), 0.92 (p<0.001, 95% CI, 0.80–0.97, I2 = 79.36%); ≥F2 0.84 (p = 0.35, 95% CI, 0.81–0.86, I2 = 9.55%), 0.83 (p<0.001, 95% CI, 0.77–0.88, I2 = 86.56%); ≥F3 0.89 (p = 0.56, 95% CI, 0.86–0.92, I2 = 0%), 0.86 (p<0.001, 95% CI, 0.82–0.90, I2 = 75.73%); F4 0.89 (p = 0.24, 95% CI, 0.84–0.92, I2 = 20.56%), 0.88 (p<0.001, 95% CI, 0.84–0.92, I2 = 82.75%), respectively. Sensitivity analysis showed no significant changes if any one of the studies was excluded. Publication bias was not detected in this meta-analysis. Conclusions Our study suggests that SWE is a helpful method to appraise liver fibrosis severity. Future studies that validate these findings would be appropriate. PMID:27300569

  15. Meta-analysis for diagnostic accuracy studies: a new statistical model using beta-binomial distributions and bivariate copulas.

    PubMed

    Kuss, Oliver; Hoyer, Annika; Solms, Alexander

    2014-01-15

    There are still challenges when meta-analyzing data from studies on diagnostic accuracy. This is mainly due to the bivariate nature of the response where information on sensitivity and specificity must be summarized while accounting for their correlation within a single trial. In this paper, we propose a new statistical model for the meta-analysis for diagnostic accuracy studies. This model uses beta-binomial distributions for the marginal numbers of true positives and true negatives and links these margins by a bivariate copula distribution. The new model comes with all the features of the current standard model, a bivariate logistic regression model with random effects, but has the additional advantages of a closed likelihood function and a larger flexibility for the correlation structure of sensitivity and specificity. In a simulation study, which compares three copula models and two implementations of the standard model, the Plackett and the Gauss copula do rarely perform worse but frequently better than the standard model. We use an example from a meta-analysis to judge the diagnostic accuracy of telomerase (a urinary tumor marker) for the diagnosis of primary bladder cancer for illustration.

  16. A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference.

    PubMed

    Storey, Helen L; Huang, Ying; Crudder, Chris; Golden, Allison; de los Santos, Tala; Hawkins, Kenneth

    2015-01-01

    Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates.

  17. Linked color imaging application for improving the endoscopic diagnosis accuracy: a pilot study.

    PubMed

    Sun, Xiaotian; Dong, Tenghui; Bi, Yiliang; Min, Min; Shen, Wei; Xu, Yang; Liu, Yan

    2016-01-01

    Endoscopy has been widely used in diagnosing gastrointestinal mucosal lesions. However, there are still lack of objective endoscopic criteria. Linked color imaging (LCI) is newly developed endoscopic technique which enhances color contrast. Thus, we investigated the clinical application of LCI and further analyzed pixel brightness for RGB color model. All the lesions were observed by white light endoscopy (WLE), LCI and blue laser imaging (BLI). Matlab software was used to calculate pixel brightness for red (R), green (G) and blue color (B). Of the endoscopic images for lesions, LCI had significantly higher R compared with BLI but higher G compared with WLE (all P < 0.05). R/(G + B) was significantly different among 3 techniques and qualified as a composite LCI marker. Our correlation analysis of endoscopic diagnosis with pathology revealed that LCI was quite consistent with pathological diagnosis (P = 0.000) and the color could predict certain kinds of lesions. ROC curve demonstrated at the cutoff of R/(G+B) = 0.646, the area under curve was 0.646, and the sensitivity and specificity was 0.514 and 0.773. Taken together, LCI could improve efficiency and accuracy of diagnosing gastrointestinal mucosal lesions and benefit target biopsy. R/(G + B) based on pixel brightness may be introduced as a objective criterion for evaluating endoscopic images. PMID:27641243

  18. Linked color imaging application for improving the endoscopic diagnosis accuracy: a pilot study

    PubMed Central

    Sun, Xiaotian; Dong, Tenghui; Bi, Yiliang; Min, Min; Shen, Wei; Xu, Yang; Liu, Yan

    2016-01-01

    Endoscopy has been widely used in diagnosing gastrointestinal mucosal lesions. However, there are still lack of objective endoscopic criteria. Linked color imaging (LCI) is newly developed endoscopic technique which enhances color contrast. Thus, we investigated the clinical application of LCI and further analyzed pixel brightness for RGB color model. All the lesions were observed by white light endoscopy (WLE), LCI and blue laser imaging (BLI). Matlab software was used to calculate pixel brightness for red (R), green (G) and blue color (B). Of the endoscopic images for lesions, LCI had significantly higher R compared with BLI but higher G compared with WLE (all P < 0.05). R/(G + B) was significantly different among 3 techniques and qualified as a composite LCI marker. Our correlation analysis of endoscopic diagnosis with pathology revealed that LCI was quite consistent with pathological diagnosis (P = 0.000) and the color could predict certain kinds of lesions. ROC curve demonstrated at the cutoff of R/(G+B) = 0.646, the area under curve was 0.646, and the sensitivity and specificity was 0.514 and 0.773. Taken together, LCI could improve efficiency and accuracy of diagnosing gastrointestinal mucosal lesions and benefit target biopsy. R/(G + B) based on pixel brightness may be introduced as a objective criterion for evaluating endoscopic images. PMID:27641243

  19. A study of the accuracy of neutrally buoyant bubbles used as flow tracers in air

    NASA Technical Reports Server (NTRS)

    Kerho, Michael F.

    1993-01-01

    Research has been performed to determine the accuracy of neutrally buoyant and near neutrally buoyant bubbles used as flow tracers in air. Theoretical, computational, and experimental results are presented to evaluate the dynamics of bubble trajectories and factors affecting their ability to trace flow-field streamlines. The equation of motion for a single bubble was obtained and evaluated using a computational scheme to determine the factors which affect a bubble's trajectory. A two-dimensional experiment was also conducted to experimentally determine bubble trajectories in the stagnation region of NACA 0012 airfoil at 0 deg angle of attack using a commercially available helium bubble generation system. Physical properties of the experimental bubble trajectories were estimated using the computational scheme. These properties included the density ratio and diameter of the individual bubbles. the helium bubble system was then used to visualize and document the flow field about a 30 deg swept semispan wing with simulated glaze ice. Results were compared to Navier-Stokes calculations and surface oil flow visualization. The theoretical and computational analysis have shown that neutrally buoyant bubbles will trace even the most complex flow patterns. Experimental analysis revealed that the use of bubbles to trace flow patterns should be limited to qualitative measurements unless care is taken to ensure neutral buoyancy. This is due to the difficulty in the production of neutrally buoyant bubbles.

  20. An observational study of the accuracy and completeness of an anesthesia information management system: recommendations for documentation system changes.

    PubMed

    Wilbanks, Bryan A; Moss, Jacqueline A; Berner, Eta S

    2013-08-01

    Anesthesia information management systems must often be tailored to fit the environment in which they are implemented. Extensive customization necessitates that systems be analyzed for both accuracy and completeness of documentation design to ensure that the final record is a true representation of practice. The purpose of this study was to determine the accuracy of a recently installed system in the capture of key perianesthesia data. This study used an observational design and was conducted using a convenience sample of nurse anesthetists. Observational data of the nurse anesthetists'delivery of anesthesia care were collected using a touch-screen tablet computer utilizing an Access database customized observational data collection tool. A questionnaire was also administered to these nurse anesthetists to assess perceived accuracy, completeness, and satisfaction with the electronic documentation system. The major sources of data not documented in the system were anesthesiologist presence (20%) and placement of intravenous lines (20%). The major sources of inaccuracies in documentation were gas flow rates (45%), medication administration times (30%), and documentation of neuromuscular function testing (20%)-all of the sources of inaccuracies were related to the use of charting templates that were not altered to reflect the actual interventions performed. PMID:23851709

  1. An observational study of the accuracy and completeness of an anesthesia information management system: recommendations for documentation system changes.

    PubMed

    Wilbanks, Bryan A; Moss, Jacqueline A; Berner, Eta S

    2013-08-01

    Anesthesia information management systems must often be tailored to fit the environment in which they are implemented. Extensive customization necessitates that systems be analyzed for both accuracy and completeness of documentation design to ensure that the final record is a true representation of practice. The purpose of this study was to determine the accuracy of a recently installed system in the capture of key perianesthesia data. This study used an observational design and was conducted using a convenience sample of nurse anesthetists. Observational data of the nurse anesthetists'delivery of anesthesia care were collected using a touch-screen tablet computer utilizing an Access database customized observational data collection tool. A questionnaire was also administered to these nurse anesthetists to assess perceived accuracy, completeness, and satisfaction with the electronic documentation system. The major sources of data not documented in the system were anesthesiologist presence (20%) and placement of intravenous lines (20%). The major sources of inaccuracies in documentation were gas flow rates (45%), medication administration times (30%), and documentation of neuromuscular function testing (20%)-all of the sources of inaccuracies were related to the use of charting templates that were not altered to reflect the actual interventions performed.

  2. Accuracy of the unified approach in maternally influenced traits - illustrated by a simulation study in the honey bee (Apis mellifera)

    PubMed Central

    2013-01-01

    Background The honey bee is an economically important species. With a rapid decline of the honey bee population, it is necessary to implement an improved genetic evaluation methodology. In this study, we investigated the applicability of the unified approach and its impact on the accuracy of estimation of breeding values for maternally influenced traits on a simulated dataset for the honey bee. Due to the limitation to the number of individuals that can be genotyped in a honey bee population, the unified approach can be an efficient strategy to increase the genetic gain and to provide a more accurate estimation of breeding values. We calculated the accuracy of estimated breeding values for two evaluation approaches, the unified approach and the traditional pedigree based approach. We analyzed the effects of different heritabilities as well as genetic correlation between direct and maternal effects on the accuracy of estimation of direct, maternal and overall breeding values (sum of maternal and direct breeding values). The genetic and reproductive biology of the honey bee was accounted for by taking into consideration characteristics such as colony structure, uncertain paternity, overlapping generations and polyandry. In addition, we used a modified numerator relationship matrix and a realistic genome for the honey bee. Results For all values of heritability and correlation, the accuracy of overall estimated breeding values increased significantly with the unified approach. The increase in accuracy was always higher for the case when there was no correlation as compared to the case where a negative correlation existed between maternal and direct effects. Conclusions Our study shows that the unified approach is a useful methodology for genetic evaluation in honey bees, and can contribute immensely to the improvement of traits of apicultural interest such as resistance to Varroa or production and behavioural traits. In particular, the study is of great interest for

  3. Assessing the accuracy of the International Classification of Diseases codes to identify abusive head trauma: a feasibility study

    PubMed Central

    Berger, Rachel P; Parks, Sharyn; Fromkin, Janet; Rubin, Pamela; Pecora, Peter J

    2016-01-01

    Objective To assess the accuracy of an International Classification of Diseases (ICD) code-based operational case definition for abusive head trauma (AHT). Methods Subjects were children <5 years of age evaluated for AHT by a hospital-based Child Protection Team (CPT) at a tertiary care paediatric hospital with a completely electronic medical record (EMR) system. Subjects were designated as non-AHT traumatic brain injury (TBI) or AHT based on whether the CPT determined that the injuries were due to AHT. The sensitivity and specificity of the ICD-based definition were calculated. Results There were 223 children evaluated for AHT: 117 AHT and 106 non-AHT TBI. The sensitivity and specificity of the ICD-based operational case definition were 92% (95% CI 85.8 to 96.2) and 96% (95% CI 92.3 to 99.7), respectively. All errors in sensitivity and three of the four specificity errors were due to coder error; one specificity error was a physician error. Conclusions In a paediatric tertiary care hospital with an EMR system, the accuracy of an ICD-based case definition for AHT was high. Additional studies are needed to assess the accuracy of this definition in all types of hospitals in which children with AHT are cared for. PMID:24167034

  4. Comparison of Accuracy of Uncorrected and Corrected Sagittal Tomography in Detection of Mandibular Condyle Erosions: an Exvivo Study

    PubMed Central

    Naser, Asieh Zamani; Shirani, Amir Mansour; Hekmatian, Ehsan; Valiani, Ali; Ardestani, Pegah; Vali, Ava

    2010-01-01

    Background: Radiographic examination of TMJ is indicated when there are clinical signs of pathological conditions, mainly bone changes that may influence the diagnosis and treatment planning. The purpose of this study was to evaluate and to compare the validity and diagnostic accuracy of uncorrected and corrected sagittal tomographic images in the detection of simulated mandibular condyle erosions. Methods Simulated lesions were created in 10 dry mandibles using a dental round bur. Using uncorrected and corrected sagittal tomography techniques, mandibular condyles were imaged by a Cranex Tome X-ray unit before and after creating the lesions. The uncorrected and corrected tomography images were examined by two independent observers for absence or presence of a lesion. The accuracy for detecting mandibular condyle lesions was expressed as sensitivity, specificity, and validity values. Differences between the two radiographic modalities were tested by Wilcoxon for paired data tests. Inter-observer agreement was determined by Cohen's Kappa. Results: The sensitivity, specificity and validity were 45%, 85% and 30% in uncorrected sagittal tomographic images, respectively, and 70%, 92.5% and 60% in corrected sagittal tomographic images, respectively. There was a significant statistical difference between the accuracy of uncorrected and corrected sagittal tomography in detection of mandibular condyle erosions (P = 0.016). The inter-observer agreement was slight for uncorrected sagittal tomography and moderate for corrected sagittal tomography. Conclusion: The accuracy of corrected sagittal tomography is significantly higher than that of uncorrected sagittal tomography. Therefore, corrected sagittal tomography seems to be a better modality in detection of mandibular condyle erosions. PMID:22013461

  5. Accuracy of tablet splitting: Comparison study between hand splitting and tablet cutter

    PubMed Central

    Habib, Walid A.; Alanizi, Abdulaziz S.; Abdelhamid, Magdi M.; Alanizi, Fars K.

    2013-01-01

    Background Tablet splitting is often used in pharmacy practice to adjust the administered doses. It is also used as a method of reducing medication costs. Objective To investigate the accuracy of tablet splitting by comparing hand splitting vs. a tablet cutter for a low dose drug tablet. Methods Salbutamol tablets (4 mg) were chosen as low dose tablets. A randomly selected equal number of tablets were split by hand and a tablet cutter, and the remaining tablets were kept whole. Weight variation and drug content were analysed for salbutamol in 0.1 N HCl using a validated spectrophotometric method. The percentages by which each whole tablet’s or half-tablet’s drug content and weight difference from sample mean values were compared with USP specification ranges for drug content. The %RSD was also calculated in order to determine whether the drugs met USP specification for %RSD. The tablets and half tablets were scanned using electron microscopy to show any visual differences arising from splitting. Results 27.5% of samples differed from sample mean values by a percentage that fell outside of USP specification for weight, of which 15% from the tablet cutter and 25% from those split by hand fell outside the specifications. All whole tablets and half tablets met the USP specifications for drug content but the variation of content between the two halves reached 21.3% of total content in case of hand splitting, and 7.13% only for the tablet cutter. The %RSDs for drug content and weight met the USP specification for whole salbutamol tablets and the half tablets which were split by tablet cutter. The halves which were split by hand fell outside the specification for %RSD (drug content = 6.43%, weight = 8.33%). The differences were visually clear in the electron microscope scans. Conclusion Drug content variation in half-tablets appeared to be attributable to weight variation occurring during the splitting process. This could have serious clinical consequences for

  6. Long noncoding RNAs as auxiliary biomarkers for gastric cancer screening: A pooled analysis of individual studies

    PubMed Central

    Cui, Zhaolei; Chen, Yan; Xiao, Zhenzhou; Hu, Minhua; Lin, Yingying; Chen, Yansong; Zheng, Yuhong

    2016-01-01

    Background Long non-coding RNAs (lncRNAs) are highlighted as novel cancer biomarkers with great promise. Herein, we focused on summarizing the overall diagnostic performance of lncRNAs for gastric cancer (GC). Methods Publications fulfilling the search criteria were selected from the online databases. Study quality was assessed according to the Quality Assessment for Studies of Diagnostic Accuracy (QUADAS) checklist. The summary receiver operator characteristic (SROC) curve was plotted using a bivariate meta-analysis model. Statistical analysis was performed based on the platforms of STATA 12.0 and Meta-Disc 1.4 software. Results Fifteen studies with 1252 patients and 1283 matched controls were included. The pooled sensitivity and specificity for lncRNA expression profile in differentiating GC patients from cancer-free individuals were 0.68 (95%CI: 0.61-0.74) and 0.79 (95%CI: 0.72-0.84), respectively, corresponding to an area under curve (AUC) of 0.80. Moreover, the stratified analyses demonstrated that plasma-based lncRNA profiling harbored higher accuracy than that tissue-based assay (specificity: 0.80 versus 0.75; AUC: 0.84 versus 0.77). Conclusions LncRNA profiling hallmarks a moderate diagnostic value in the management of GC and that lncRNA expression patterns may potentially be utilized as auxiliary biomarkers in confirming GC. PMID:27015554

  7. Accuracy of a Computer-Aided Surgical Simulation (CASS) Protocol for Orthognathic Surgery: A Prospective Multicenter Study

    PubMed Central

    Hsu, Sam Sheng-Pin; Gateno, Jaime; Bell, R. Bryan; Hirsch, David L.; Markiewicz, Michael R.; Teichgraeber, John F.; Zhou, Xiaobo; Xia, James J.

    2012-01-01

    Purpose The purpose of this prospective multicenter study was to assess the accuracy of a computer-aided surgical simulation (CASS) protocol for orthognathic surgery. Materials and Methods The accuracy of the CASS protocol was assessed by comparing planned and postoperative outcomes of 65 consecutive patients enrolled from 3 centers. Computer-generated surgical splints were used for all patients. For the genioplasty, one center utilized computer-generated chin templates to reposition the chin segment only for patients with asymmetry. Standard intraoperative measurements were utilized without the chin templates for the remaining patients. The primary outcome measurements were linear and angular differences for the maxilla, mandible and chin when the planned and postoperative models were registered at the cranium. The secondary outcome measurements were: maxillary dental midline difference between the planned and postoperative positions; and linear and angular differences of the chin segment between the groups with and without the use of the template. The latter was measured when the planned and postoperative models were registered at mandibular body. Statistical analyses were performed, and the accuracy was reported using root mean square deviation (RMSD) and Bland and Altman's method for assessing measurement agreement. Results In the primary outcome measurements, there was no statistically significant difference among the 3 centers for the maxilla and mandible. The largest RMSD was 1.0mm and 1.5° for the maxilla, and 1.1mm and 1.8° for the mandible. For the chin, there was a statistically significant difference between the groups with and without the use of the chin template. The chin template group showed excellent accuracy with largest positional RMSD of 1.0mm and the largest orientational RSMD of 2.2°. However, larger variances were observed in the group not using the chin template. This was significant in anteroposterior and superoinferior directions, as in

  8. An Evaluation of the Effects of an Oven Timer Study Behavior and Concurrent Completion and Accuracy of Assignments for a First Grade Repeater: A Case Study.

    ERIC Educational Resources Information Center

    Riegelman, Elizabeth D.; And Others

    The effects of an oven timer as an antecedent stimulus on study behavior and concurrent completion and accuracy of reading and writing assignments were investigated for an 8-year-old first grade repeater who lacked motivation. Following baseline observations during which the teacher recorded study behavior and collected assignments with no…

  9. A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference

    PubMed Central

    Storey, Helen L.; Huang, Ying; Crudder, Chris; Golden, Allison; de los Santos, Tala; Hawkins, Kenneth

    2015-01-01

    Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates. PMID:26566275

  10. A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference.

    PubMed

    Storey, Helen L; Huang, Ying; Crudder, Chris; Golden, Allison; de los Santos, Tala; Hawkins, Kenneth

    2015-01-01

    Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates. PMID:26566275

  11. Oral Fluency, Accuracy, and Complexity in Formal Instruction and Study Abroad Learning Contexts

    ERIC Educational Resources Information Center

    Mora, Joan C.; Valls-Ferrer, Margalida

    2012-01-01

    This study investigates the differential effects of two learning contexts, formal instruction (FI) at home and a study abroad period (SA), on the oral production skills of advanced-level Catalan-Spanish undergraduate learners of English. Speech samples elicited through an interview at three data collection times over a 2-year period were…

  12. Effects of a Word Study Intervention on Spelling Accuracy among Low-Literate Adults

    ERIC Educational Resources Information Center

    Shaw, Donita Massengill; Berg, Margaret A.

    2008-01-01

    The purpose of this study was to evaluate the impact of an instructional spelling approach, Word Study, on the spelling ability of adults with limited literacy proficiency. Ten adults (five control and five experimental) were given the Developmental Spelling Assessment. The control participants received traditional spelling instruction, and the…

  13. The accuracy of endometrial sampling in women with postmenopausal bleeding: a systematic review and meta-analysis.

    PubMed

    van Hanegem, Nehalennia; Prins, Marileen M C; Bongers, Marlies Y; Opmeer, Brent C; Sahota, Daljit Singh; Mol, Ben Willem J; Timmermans, Anne

    2016-02-01

    Postmenopausal bleeding (PMB) can be the first sign of endometrial cancer. In case of thickened endometrium, endometrial sampling is often used in these women. In this systematic review, we studied the accuracy of endometrial sampling for the diagnoses of endometrial cancer, atypical hyperplasia and endometrial disease (endometrial pathology, including benign polyps). We systematically searched the literature for studies comparing the results of endometrial sampling in women with postmenopausal bleeding with two different reference standards: blind dilatation and curettage (D&C) and hysteroscopy with histology. We assessed the quality of the detected studies by the QUADAS-2 tool. For each included study, we calculated the fraction of women in whom endometrial sampling failed. Furthermore, we extracted numbers of cases of endometrial cancer, atypical hyperplasia and endometrial disease that were identified or missed by endometrial sampling. We detected 12 studies reporting on 1029 women with postmenopausal bleeding: five studies with dilatation and curettage (D&C) and seven studies with hysteroscopy as a reference test. The weighted sensitivity of endometrial sampling with D&C as a reference for the diagnosis of endometrial cancer was 100% (range 100-100%) and 92% (71-100) for the diagnosis of atypical hyperplasia. Only one study reported sensitivity for endometrial disease, which was 76%. When hysteroscopy was used as a reference, weighted sensitivities of endometrial sampling were 90% (range 50-100), 82% (range 56-94) and 39% (21-69) for the diagnosis of endometrial cancer, atypical hyperplasia and endometrial disease, respectively. For all diagnosis studied and the reference test used, specificity was 98-100%. The weighted failure rate of endometrial sampling was 11% (range 1-53%), while insufficient samples were found in 31% (range 7-76%). In these women with insufficient or failed samples, an endometrial (pre) cancer was found in 7% (range 0-18%). In women with

  14. Comparison of Diagnostic Accuracy of PCR Targeting the 47-Kilodalton Protein Membrane Gene of Treponema pallidum and PCR Targeting the DNA Polymerase I Gene: Systematic Review and Meta-analysis.

    PubMed

    Gayet-Ageron, Angèle; Combescure, Christophe; Lautenschlager, Stephan; Ninet, Béatrice; Perneger, Thomas V

    2015-11-01

    Treponema pallidum PCR (Tp-PCR) testing now is recommended as a valid tool for the diagnosis of primary or secondary syphilis. The objectives were to systematically review and determine the optimal specific target gene to be used for Tp-PCR. Comparisons of the performance of the two main targets are tpp47 and polA genes were done using meta-analysis. Three electronic bibliographic databases, representing abstract books from five conferences specialized in infectious diseases from January 1990 to March 2015, were searched. Search keywords included ("syphilis" OR "Treponema pallidum" OR "neurosyphilis") AND ("PCR" OR "PCR" OR "molecular amplification"). We included diagnostic studies assessing the performance of Tp-PCR targeting tpp47 (tpp47-Tp-PCR) or the polA gene (polA-Tp-PCR) in ulcers from early syphilis. All studies were assessed against quality criteria using the QUADAS-2 tool. Of 37 studies identified, 62.2% were judged at low risk of bias or applicability. Most used the U.S. Centers for Disease Control and Prevention (CDC) case definitions for primary or secondary (early) syphilis (89.2%; n = 33); 15 (40.5%) used darkfield microscopy (DFM). We did not find differences in sensitivity and specificity between the two Tp-PCR methods in the subgroup of studies using adequate reference tests. Among studies using DFM as the reference test, sensitivities were 79.8% (95% confidence intervals [CI], 72.7 to 85.4%) and 71.4% (46.0 to 88.0%) for tpp47-Tp-PCR and polA-Tp-PCR (P = 0.217), respectively; respective specificities were 95.3% (93.5 to 96.6%) and 93.7% (91.8 to 95.2%) (P = 0.304). Our findings suggest that the two Tp-PCR methods have similar accuracy and could be used interchangeably. PMID:26311859

  15. A Longitudinal Study of Novice-Level Changes in Fluency and Accuracy in Student Monologues

    ERIC Educational Resources Information Center

    Long, Robert W., III.

    2012-01-01

    Detailed research concerning the issue fluency, specifically relating to pauses, mean length runs, and fluency rates in Japanese EFL learners, is limited. Furthermore, the issue of tracking fluency gains has often been ignored, misunderstood or minimized in EFL educational research. The present study, which is based on six monologues conducted…

  16. A Longitudinal Study of Complexity, Accuracy and Fluency Variation in Second Language Development

    ERIC Educational Resources Information Center

    Ferraris, Stefania

    2012-01-01

    This chapter presents the results of a study on interlanguage variation. The production of four L2 learners of Italian, tested four times at yearly intervals while engaged in four oral tasks, is compared to that of two native speakers, and analysed with quantitative CAF measures. Thus, time, task type, nativeness, as well as group vs. individual…

  17. The Accuracy of a Simple, Low-Cost GPS Data Logger/Receiver to Study Outdoor Human Walking in View of Health and Clinical Studies

    PubMed Central

    Noury-Desvaux, Bénédicte; Abraham, Pierre; Mahé, Guillaume; Sauvaget, Thomas; Leftheriotis, Georges; Le Faucheur, Alexis

    2011-01-01

    Introduction Accurate and objective measurements of physical activity and lower-extremity function are important in health and disease monitoring, particularly given the current epidemic of chronic diseases and their related functional impairment. Purpose The aim of the present study was to determine the accuracy of a handy (lightweight, small, only one stop/start button) and low-cost (∼$75 with its external antenna) Global Positioning System (GPS) data logger/receiver (the DG100) as a tool to study outdoor human walking in perspective of health and clinical research studies. Methods. Healthy subjects performed two experiments that consisted of different prescribed outdoor walking protocols. Experiment 1. We studied the accuracy of the DG100 for detecting bouts of walking and resting. Experiment 2. We studied the accuracy of the DG100 for estimating distances and speeds of walking. Results Experiment 1. The performance in the detection of bouts, expressed as the percentage of walking and resting bouts that were correctly detected, was 92.4% [95% Confidence Interval: 90.6–94.3]. Experiment 2. The coefficients of variation [95% Confidence Interval] for the accuracy of estimating the distances and speeds of walking were low: 3.1% [2.9–3.3] and 2.8% [2.6–3.1], respectively. Conclusion The DG100 produces acceptable accuracy both in detecting bouts of walking and resting and in estimating distances and speeds of walking during the detected walking bouts. However, before we can confirm that the DG100 can be used to study walking with respect to health and clinical studies, the inter- and intra-DG100 variability should be studied. Trial Registration ClinicalTrials.gov NCT00485147 PMID:21931593

  18. Accuracy study of the main screening tools for temporomandibular disorder in children and adolescents.

    PubMed

    de Santis, Tatiana Oliveira; Motta, Lara Jansiski; Biasotto-Gonzalez, Daniela Aparecida; Mesquita-Ferrari, Raquel Agnelli; Fernandes, Kristianne Porta Santos; de Godoy, Camila Haddad Leal; Alfaya, Thays Almeida; Bussadori, Sandra Kalil

    2014-01-01

    The aims of the present study were to assess the degree of sensitivity and specificity of the screening questionnaire recommended by the American Academy of Orofacial Pain (AAOP) and the patient-history index proposed by Helkimo (modified by Fonseca) and correlate the findings with a clinical exam. All participants answered the questionnaires and were submitted to a clinical exam by a dentist who had undergone calibration training. Both the AAOP questionnaire and Helkimo index achieved low degrees of sensitivity for the detection of temporomandibular disorder (TMD), but exhibited a high degree of specificity. With regard to concordance, the AAOP questionnaire and Helkimo index both achieved low levels of agreement with the clinical exam. The different instruments available in the literature for the assessment of TMD and examined herein exhibit low sensitivity and high specificity when administered to children and adolescents stemming from difficulties in comprehension due to the age group studied and the language used in the self-explanatory questions.

  19. The impact of registration accuracy on imaging validation study design: A novel statistical power calculation.

    PubMed

    Gibson, Eli; Fenster, Aaron; Ward, Aaron D

    2013-10-01

    Novel imaging modalities are pushing the boundaries of what is possible in medical imaging, but their signal properties are not always well understood. The evaluation of these novel imaging modalities is critical to achieving their research and clinical potential. Image registration of novel modalities to accepted reference standard modalities is an important part of characterizing the modalities and elucidating the effect of underlying focal disease on the imaging signal. The strengths of the conclusions drawn from these analyses are limited by statistical power. Based on the observation that in this context, statistical power depends in part on uncertainty arising from registration error, we derive a power calculation formula relating registration error, number of subjects, and the minimum detectable difference between normal and pathologic regions on imaging, for an imaging validation study design that accommodates signal correlations within image regions. Monte Carlo simulations were used to evaluate the derived models and test the strength of their assumptions, showing that the model yielded predictions of the power, the number of subjects, and the minimum detectable difference of simulated experiments accurate to within a maximum error of 1% when the assumptions of the derivation were met, and characterizing sensitivities of the model to violations of the assumptions. The use of these formulae is illustrated through a calculation of the number of subjects required for a case study, modeled closely after a prostate cancer imaging validation study currently taking place at our institution. The power calculation formulae address three central questions in the design of imaging validation studies: (1) What is the maximum acceptable registration error? (2) How many subjects are needed? (3) What is the minimum detectable difference between normal and pathologic image regions?

  20. Assessing accuracy of a probabilistic model for very large fire in the Rocky Mountains: A High Park Fire case study

    NASA Astrophysics Data System (ADS)

    Stavros, E.; Abatzoglou, J. T.; Larkin, N.; McKenzie, D.; Steel, A.

    2012-12-01

    Across the western United States, the largest wildfires account for a major proportion of the area burned and substantially affect mountain forests and their associated ecosystem services, among which is pristine air quality. These fires commandeer national attention and significant fire suppression resources. Despite efforts to understand the influence of fuel loading, climate, and weather on annual area burned, few studies have focused on understanding what abiotic factors enable and drive the very largest wildfires. We investigated the correlation between both antecedent climate and in-situ biophysical variables and very large (>20,000 ha) fires in the western United States from 1984 to 2009. We built logistic regression models, at the spatial scale of the national Geographic Area Coordination Centers (GACCs), to estimate the probability that a given day is conducive to a very large wildfire. Models vary in accuracy and in which variables are the best predictors. In a case study of the conditions of the High Park Fire, neighboring Fort Collins, Colorado, occurring in early summer 2012, we evaluate the predictive accuracy of the Rocky Mountain model.

  1. Improved accuracy of markerless motion tracking on bone suppression images: preliminary study for image-guided radiation therapy (IGRT)

    NASA Astrophysics Data System (ADS)

    Tanaka, Rie; Sanada, Shigeru; Sakuta, Keita; Kawashima, Hiroki

    2015-05-01

    The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images obtained by the dual-energy subtraction technique. This study was performed to evaluate the usefulness of bone suppression image processing in image-guided radiation therapy. We demonstrated the improved accuracy of markerless motion tracking on bone suppression images. Chest fluoroscopic images of nine patients with lung nodules during respiration were obtained using a flat-panel detector system (120 kV, 0.1 mAs/pulse, 5 fps). Commercial bone suppression image processing software was applied to the fluoroscopic images to create corresponding bone suppression images. Regions of interest were manually located on lung nodules and automatic target tracking was conducted based on the template matching technique. To evaluate the accuracy of target tracking, the maximum tracking error in the resulting images was compared with that of conventional fluoroscopic images. The tracking errors were decreased by half in eight of nine cases. The average maximum tracking errors in bone suppression and conventional fluoroscopic images were 1.3   ±   1.0 and 3.3   ±   3.3 mm, respectively. The bone suppression technique was especially effective in the lower lung area where pulmonary vessels, bronchi, and ribs showed complex movements. The bone suppression technique improved tracking accuracy without special equipment and implantation of fiducial markers, and with only additional small dose to the patient. Bone suppression fluoroscopy is a potential measure for respiratory displacement of the target. This paper was presented at RSNA 2013 and was carried out at Kanazawa University, JAPAN.

  2. Improved accuracy of markerless motion tracking on bone suppression images: preliminary study for image-guided radiation therapy (IGRT).

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Sakuta, Keita; Kawashima, Hiroki

    2015-05-21

    The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images obtained by the dual-energy subtraction technique. This study was performed to evaluate the usefulness of bone suppression image processing in image-guided radiation therapy. We demonstrated the improved accuracy of markerless motion tracking on bone suppression images. Chest fluoroscopic images of nine patients with lung nodules during respiration were obtained using a flat-panel detector system (120 kV, 0.1 mAs/pulse, 5 fps). Commercial bone suppression image processing software was applied to the fluoroscopic images to create corresponding bone suppression images. Regions of interest were manually located on lung nodules and automatic target tracking was conducted based on the template matching technique. To evaluate the accuracy of target tracking, the maximum tracking error in the resulting images was compared with that of conventional fluoroscopic images. The tracking errors were decreased by half in eight of nine cases. The average maximum tracking errors in bone suppression and conventional fluoroscopic images were 1.3 ± 1.0 and 3.3 ± 3.3 mm, respectively. The bone suppression technique was especially effective in the lower lung area where pulmonary vessels, bronchi, and ribs showed complex movements. The bone suppression technique improved tracking accuracy without special equipment and implantation of fiducial markers, and with only additional small dose to the patient. Bone suppression fluoroscopy is a potential measure for respiratory displacement of the target.

  3. Effect of considering the initial parameters on accuracy of experimental studies conclusions

    NASA Astrophysics Data System (ADS)

    Zagulova, D.; Nesterenko, A.; Kapilevich, L.; Popova, J.

    2015-11-01

    The presented paper contains the evidences of the necessity to take into account the initial level of physiological parameters while conducting the biomedical research; it is exemplified by certain indicators of cardiorespiratory system. The analysis is based on the employment of data obtained via the multiple surveys of medical and pharmaceutical college students. There has been revealed a negative correlation of changes of the studied parameters of cardiorespiratory system in the repeated measurements compared to their initial level. It is assumed that the dependence of the changes of physiological parameters from the baseline can be caused by the biorhythmic changes inherent for all body systems.

  4. Strategies to Improve the Accuracy of Mars-GRAM Sensitivity Studies at Large Optical Depths

    NASA Technical Reports Server (NTRS)

    Justh, Hilary L.; Justus, Carl G.; Badger, Andrew M.

    2010-01-01

    The poster provides an overview of techniques to improve the Mars Global Reference Atmospheric Model (Mars-GRAM) sensitivity. It has been discovered during the Mars Science Laboratory (MSL) site selection process that the Mars Global Reference Atmospheric Model (Mars-GRAM) when used for sensitivity studies for TES MapYear = 0 and large optical depth values such as tau = 3 is less than realistic. A preliminary fix has been made to Mars-GRAM by adding a density factor value that was determined for tau = 0.3, 1 and 3.

  5. Improving Mars-GRAM: Increasing the Accuracy of Sensitivity Studies at Large Optical Depths

    NASA Technical Reports Server (NTRS)

    Justh, Hilary L.; Justus, C. G.; Badger, Andrew M.

    2010-01-01

    Extensively utilized for numerous mission applications, the Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model. In a Monte-Carlo mode, Mars-GRAM's perturbation modeling capability is used to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). Mars-GRAM has been found to be inexact when used during the Mars Science Laboratory (MSL) site selection process for sensitivity studies for MapYear=0 and large optical depth values such as tau=3. Mars-GRAM is based on the NASA Ames Mars General Circulation Model (MGCM) from the surface to 80 km altitude. Mars-GRAM with the MapYear parameter set to 0 utilizes results from a MGCM run with a fixed value of tau=3 at all locations for the entire year. Imprecise atmospheric density and pressure at all altitudes is a consequence of this use of MGCM with tau=3. Density factor values have been determined for tau=0.3, 1 and 3 as a preliminary fix to this pressure-density problem. These factors adjust the input values of MGCM MapYear 0 pressure and density to achieve a better match of Mars-GRAM MapYear 0 with Thermal Emission Spectrometer (TES) observations for MapYears 1 and 2 at comparable dust loading. These density factors are fixed values for all latitudes and Ls and are included in Mars-GRAM Release 1.3. Work currently being done, to derive better multipliers by including variations with latitude and/or Ls by comparison of MapYear 0 output directly against TES limb data, will be highlighted in the presentation. The TES limb data utilized in this process has been validated by a comparison study between Mars atmospheric density estimates from Mars-GRAM and measurements by Mars Global Surveyor (MGS). This comparison study was undertaken for locations on Mars of varying latitudes, Ls, and LTST. The more precise density factors will be included in Mars-GRAM 2005 Release 1.4 and thus improve the results of future sensitivity studies done for large

  6. Strategies to Improve the Accuracy of Mars-GRAM Sensitivity Studies at Large Optical Depths

    NASA Astrophysics Data System (ADS)

    Justh, H. L.; Justus, C. G.; Badger, A. M.

    2009-12-01

    The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM’s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). It has been discovered during the Mars Science Laboratory (MSL) site selection process that Mars-GRAM when used for sensitivity studies for MapYear=0 and large optical depth values such as tau=3 is less than realistic. A comparison study between Mars atmospheric density estimates from Mars-GRAM and measurements by Mars Global Surveyor (MGS) has been undertaken for locations of varying latitudes, Ls, and LTST on Mars. The preliminary results from this study have validated the Thermal Emission Spectrometer (TES) limb data. From the surface to 80 km altitude, Mars-GRAM is based on the NASA Ames Mars General Circulation Model (MGCM). MGCM results that were used for Mars-GRAM with MapYear=0 were from a MGCM run with a fixed value of tau=3 for the entire year at all locations. Unrealistic energy absorption by uniform atmospheric dust leads to an unrealistic thermal energy balance on the polar caps. The outcome is an inaccurate cycle of condensation/sublimation of the polar caps and, as a consequence, an inaccurate cycle of total atmospheric mass and global-average surface pressure. Under an assumption of unchanged temperature profile and hydrostatic equilibrium, a given percentage change in surface pressure would produce a corresponding percentage change in density at all altitudes. Consequently, the final result of a change in surface pressure is an imprecise atmospheric density at all altitudes. To solve this pressure-density problem, a density factor value was determined for tau=.3, 1 and 3 that will adjust the input values of MGCM MapYear 0 pressure and density to achieve a better match of Mars-GRAM MapYear 0 with MapYears 1 and 2 MGCM output

  7. Strategies to Improve the Accuracy of Mars-GRAM Sensitivity Studies at Large Optical Depths

    NASA Technical Reports Server (NTRS)

    Justh, Hilary L.; Justus, Carl G.; Badger, Andrew M.

    2009-01-01

    The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). It has been discovered during the Mars Science Laboratory (MSL) site selection process that Mars-GRAM when used for sensitivity studies for MapYear=0 and large optical depth values such as tau=3 is less than realistic. A comparison study between Mars atmospheric density estimates from Mars- GRAM and measurements by Mars Global Surveyor (MGS) has been undertaken for locations of varying latitudes, Ls, and LTST on Mars. The preliminary results from this study have validated the Thermal Emission Spectrometer (TES) limb data. From the surface to 80 km altitude, Mars- GRAM is based on the NASA Ames Mars General Circulation Model (MGCM). MGCM results that were used for Mars-GRAM with MapYear=0 were from a MGCM run with a fixed value of tau=3 for the entire year at all locations. Unrealistic energy absorption by uniform atmospheric dust leads to an unrealistic thermal energy balance on the polar caps. The outcome is an inaccurate cycle of condensation/sublimation of the polar caps and, as a consequence, an inaccurate cycle of total atmospheric mass and global-average surface pressure. Under an assumption of unchanged temperature profile and hydrostatic equilibrium, a given percentage change in surface pressure would produce a corresponding percentage change in density at all altitudes. Consequently, the final result of a change in surface pressure is an imprecise atmospheric density at all altitudes. To solve this pressure-density problem, a density factor value was determined for tau=.3, 1 and 3 that will adjust the input values of MGCM MapYear 0 pressure and density to achieve a better match of Mars-GRAM MapYear=0 with MapYears 1 and 2 MGCM output

  8. A case control study to improve accuracy of an electronic fall prevention toolkit.

    PubMed

    Dykes, Patricia C; I-Ching, Evita Hou; Soukup, Jane R; Chang, Frank; Lipsitz, Stuart

    2012-01-01

    Patient falls are a serious and commonly report adverse event in hospitals. In 2009, our team conducted the first randomized control trial of a health information technology-based intervention that significantly reduced falls in acute care hospitals. However, some patients on intervention units with access to the electronic toolkit fell. The purpose of this case control study was to use data mining and modeling techniques to identify the factors associated with falls in hospitalized patients when the toolkit was in place. Our ultimate aim was to apply our findings to improve the toolkit logic and to generate practice recommendations. The results of our evaluation suggest that the fall prevention toolkit logic is accurate but strategies are needed to improve adherence with the fall prevention intervention recommendations generated by the electronic toolkit.

  9. Associations between visual perception accuracy and confidence in a dopaminergic manipulation study

    PubMed Central

    Andreou, Christina; Bozikas, Vasilis P.; Luedtke, Thies; Moritz, Steffen

    2015-01-01

    Delusions are defined as fixed erroneous beliefs that are based on misinterpretation of events or perception, and cannot be corrected by argumentation to the opposite. Cognitive theories of delusions regard this symptom as resulting from specific distorted thinking styles that lead to biased integration and interpretation of perceived stimuli (i.e., reasoning biases). In previous studies, we were able to show that one of these reasoning biases, overconfidence in errors, can be modulated by drugs that act on the dopamine system, a major neurotransmitter system implicated in the pathogenesis of delusions and other psychotic symptoms. Another processing domain suggested to involve the dopamine system and to be abnormal in psychotic disorders is sensory perception. The present study aimed to investigate whether (lower-order) sensory perception and (higher-order) overconfidence in errors are similarly affected by dopaminergic modulation in healthy subjects. Thirty-four healthy individuals were assessed upon administration of l-dopa, placebo, or haloperidol within a randomized, double-blind, cross-over design. Variables of interest were hits and false alarms in an illusory perception paradigm requiring speeded detection of pictures over a noisy background, and subjective confidence ratings for correct and incorrect responses. There was a significant linear increase of false alarm rates from haloperidol to placebo to l-dopa, whereas hit rates were not affected by dopaminergic manipulation. As hypothesized, confidence in error responses was significantly higher with l-dopa compared to placebo. Moreover, confidence in erroneous responses significantly correlated with false alarm rates. These findings suggest that overconfidence in errors and aberrant sensory processing might be both interdependent and related to dopaminergic transmission abnormalities in patients with psychosis. PMID:25932015

  10. Updating Mars-GRAM to Increase the Accuracy of Sensitivity Studies at Large Optical Depths

    NASA Technical Reports Server (NTRS)

    Justh, Hiliary L.; Justus, C. G.; Badger, Andrew M.

    2010-01-01

    The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). During the Mars Science Laboratory (MSL) site selection process, it was discovered that Mars-GRAM, when used for sensitivity studies for MapYear=0 and large optical depth values such as tau=3, is less than realistic. From the surface to 80 km altitude, Mars-GRAM is based on the NASA Ames Mars General Circulation Model (MGCM). MGCM results that were used for Mars-GRAM with MapYear set to 0 were from a MGCM run with a fixed value of tau=3 for the entire year at all locations. This has resulted in an imprecise atmospheric density at all altitudes. As a preliminary fix to this pressure-density problem, density factor values were determined for tau=0.3, 1 and 3 that will adjust the input values of MGCM MapYear 0 pressure and density to achieve a better match of Mars-GRAM MapYear 0 with Thermal Emission Spectrometer (TES) observations for MapYears 1 and 2 at comparable dust loading. Currently, these density factors are fixed values for all latitudes and Ls. Results will be presented from work being done to derive better multipliers by including variation with latitude and/or Ls by comparison of MapYear 0 output directly against TES limb data. The addition of these more precise density factors to Mars-GRAM 2005 Release 1.4 will improve the results of the sensitivity studies done for large optical depths.

  11. Accuracy of navigation-assisted acetabular component positioning studied by computed tomography measurements: methods and results.

    PubMed

    Ybinger, Thomas; Kumpan, W; Hoffart, H E; Muschalik, B; Bullmann, W; Zweymüller, K

    2007-09-01

    The postoperative position of the acetabular component is key for the outcome of total hip arthroplasty. Various aids have been developed to support the surgeon during implant placement. In a prospective study involving 4 centers, the computer-recorded cup alignment of 37 hip systems at the end of navigation-assisted surgery was compared with the cup angles measured on postoperative computerized tomograms. This comparison showed an average difference of 3.5 degrees (SD, 4.4 degrees ) for inclination and 6.5 degrees (SD, 7.3 degrees ) for anteversion angles. The differences in inclination correlated with the thickness of the soft tissue overlying the anterior superior iliac spine (r = 0.44; P = .007), whereas the differences in anteversion showed a correlation with the thickness of the soft tissue overlying the pubic tubercles (r = 0.52; P = .001). In centers experienced in the use of navigational tools, deviations were smaller than in units with little experience in their use. PMID:17826270

  12. The accuracy of dose-rate-regulated tracking: a parametric study

    NASA Astrophysics Data System (ADS)

    Han-Oh, S.; Yi, B.; Berman, B. L.; Lerma, F.; Yu, C.

    2010-02-01

    Dose-rate-regulated tracking (DRRT) is a novel tumor-tracking technique based on a preprogrammed multileaf-collimator (MLC) sequence and dose-rate modulation. We have performed a parametric study on how limitations of the DRRT system and breathing irregularities affect the tracking error and the duty cycle of DRRT. The time delay and the allowed dose-rate increment (continuous-, discrete-increment or beam switching) were used as two parameters for the DRRT system limitation. The breathing irregularity was quantified in terms of three variables, namely, breathing period variation, variation of peak-to-peak amplitude and baseline drift. DRRT treatments were simulated using 2126 breathing cycles obtained from 24 lung-cancer patients. Tracking errors and duty cycles from all 24 patients were combined to evaluate their dependence on each parameter or variable. The tracking error and the duty cycle show a modest difference among the three dose-rate-increment cases. Time delay, breathing peak-to-peak variation and baseline drift are the main factors affecting tracking error. The duty cycle is affected mostly by the allowed dose-rate increment, peak-to-peak variation and baseline drift.

  13. Paramedic accuracy in using a decision support algorithm when recognising adult death: a prospective cohort study

    PubMed Central

    Jones, T; Woollard, M

    2003-01-01

    Method: This prospective 16 month cohort study evaluated 188 events of recognition of adult death (ROAD) by paramedics in the period from November 1999 to February 2001. Results: Of 188 ROAD applications, errors were made in 13 cases (6.9%, 95% CI 3.7 to 11.5. Additionally, there was one adverse clinical incident associated with a case in which ROAD was applied (0.5%, 95% CI 0.01 to 2.9%). ECG strips were unavailable for eight cases, although ambulance records indicated a rhythm of asystole for each of these. Assuming this diagnosis was correct, ROAD was used 174 times without errors (93%, 95% CI 88 to 96%). Assuming that it was not, the ROAD protocol was applied without errors in 166 cases (88.3%, 95% CI 82.8 to 92.5%). None of the errors made appeared to be attributable to poor clinical decision making, compromised treatment, or changed patient outcome. The mean on-scene time for ambulance crews using the ROAD policy was 60 minutes. Conclusion: Paramedics can accurately apply a decision support algorithm when recognising adult death. It could be argued that the attendance of a medical practitioner to confirm death is therefore an inappropriate use of such personnel and may result in unnecessarily protracted on-scene times for ambulance crews. Further research is required to confirm this, and to determine the proportion of patients suitable for recognition of adult death who are actually identified as such by paramedics. PMID:12954697

  14. Effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies

    NASA Astrophysics Data System (ADS)

    Murase, Kenya; Nanjo, Takafumi; Satoshi, Ii; Miyazaki, Shohei; Hirata, Masaaki; Sugawara, Yoshifumi; Kudo, Masayuki; Sasaki, Kousuke; Mochizuki, Teruhito

    2005-11-01

    The purpose of this study was to investigate the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using multi-detector row CT (MDCT). Following the standard CT perfusion study protocol, continuous (cine) scans (1 s/rotation × 60 s) consisting of four 5 mm thick contiguous slices were performed using an MDCT scanner with a tube voltage of 80 kVp and a tube current of 200 mA. We generated the simulated images with tube currents of 50 mA, 100 mA and 150 mA by adding the corresponding noise to the raw scan data of the original image acquired above using a noise simulation tool. From the original and simulated images, we generated the functional images of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in seven patients with cerebrovascular disease, and compared the correlation coefficients (CCs) between the perfusion parameter values obtained from the original and simulated images. The coefficients of variation (CVs) in the white matter were also compared. The CC values deteriorated with decreasing tube current. There was a significant difference between 50 mA and 100 mA for all perfusion parameters. The CV values increased with decreasing tube current. There were significant differences between 50 mA and 100 mA and between 100 mA and 150 mA for CBF. For CBV and MTT, there was also a significant difference between 150 mA and 200 mA. This study will be useful for understanding the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using MDCT, and for selecting the tube current.

  15. Acute Response in vivo of a Fiber-Optic Sensor for Continuous Glucose Monitoring from Canine Studies on Point Accuracy

    PubMed Central

    Liao, Kuo-Chih; Chang, Shih-Chieh; Chiu, Cheng-Yang; Chou, Yu-Hsiang

    2010-01-01

    The objective of this study was to evaluate the acute response of Sencil™, a fiber-optic sensor, in point accuracy for glucose monitoring in vivo on healthy dogs under anesthesia. A total of four dogs with clinically normal glycemia were implanted with one sensor each in the chest region to measure the interstitial glucose concentration during the ovariohysterectomy procedure. The data was acquired every 10 seconds after initiation, and was compared to the concentration of venous plasma glucose sampled during the surgery procedures for accuracy of agreement analysis. In the four trials with a range of 71–297 mg/dL plasma glucose, the collected 21 pairs of ISF readings from the Sencil™ and the plasma reference showed superior dispersion of residue values than the conventional system, and a linear correlation (the Pearson correlation coefficient is 0.9288 and the y-intercept is 14.22 mg/dL). The MAD (17.6 mg/dL) and RMAD (16.16%) of Sencil™ measurements were in the comparable range of the conventional system. The Clarke error grid analysis indicated that 100% of the paired points were in the clinically acceptable zone A (61.9%) and B (38.1%). PMID:22163627

  16. Acute response in vivo of a fiber-optic sensor for continuous glucose monitoring from canine studies on point accuracy.

    PubMed

    Liao, Kuo-Chih; Chang, Shih-Chieh; Chiu, Cheng-Yang; Chou, Yu-Hsiang

    2010-01-01

    The objective of this study was to evaluate the acute response of Sencil(™), a fiber-optic sensor, in point accuracy for glucose monitoring in vivo on healthy dogs under anesthesia. A total of four dogs with clinically normal glycemia were implanted with one sensor each in the chest region to measure the interstitial glucose concentration during the ovariohysterectomy procedure. The data was acquired every 10 seconds after initiation, and was compared to the concentration of venous plasma glucose sampled during the surgery procedures for accuracy of agreement analysis. In the four trials with a range of 71-297 mg/dL plasma glucose, the collected 21 pairs of ISF readings from the Sencil™ and the plasma reference showed superior dispersion of residue values than the conventional system, and a linear correlation (the Pearson correlation coefficient is 0.9288 and the y-intercept is 14.22 mg/dL). The MAD (17.6 mg/dL) and RMAD (16.16%) of Sencil™ measurements were in the comparable range of the conventional system. The Clarke error grid analysis indicated that 100% of the paired points were in the clinically acceptable zone A (61.9%) and B (38.1%). PMID:22163627

  17. Improving accuracy and usability of growth charts: case study in Rwanda

    PubMed Central

    Brown, Suzana; McSharry, Patrick

    2016-01-01

    Objectives We evaluate and compare manually collected paper records against electronic records for monitoring the weights of children under the age of 5. Setting Data were collected by 24 community health workers (CHWs) in 2 Rwandan communities, 1 urban and 1 rural. Participants The same CHWs collected paper and electronic records. Paper data contain weight and age for 320 boys and 380 girls. Electronic data contain weight and age for 922 girls and 886 boys. Electronic data were collected over 9 months; most of the data is cross-sectional, with about 330 children with time-series data. Both data sets are compared with the international standard provided by the WHO growth chart. Primary and secondary outcome measures The plan was to collect 2000 individual records for the electronic data set—we finally collected 1878 records. Paper data were collected by the same CHWs, but most data were fragmented and hard to read. We transcribed data only from children for whom we were able to obtain the date of birth, to determine the exact age at the time of measurement. Results Mean absolute error (MAE) and mean absolute percentage error (MAPE) provide a way to quantify the magnitude of the error in using a given model. Comparing a model, log(weight)=a+b log(age), shows that electronic records provide considerable improvements over paper records, with 40% reduction in both performance metrics. Electronic data improve performance over the WHO model by 10% in MAPE and 7% in MAE. Results are statistically significant using the Kolmogorov-Smirnov test at p<0.01. Conclusions This study demonstrates that using modern electronic tools for health data collection is allowing better tracking of health indicators. We have demonstrated that electronic records facilitate development of a country-specific model that is more accurate than the international standard provided by the WHO growth chart. PMID:26817635

  18. Accuracy of tumor motion compensation algorithm from a robotic respiratory tracking system: A simulation study

    SciTech Connect

    Seppenwoolde, Yvette; Berbeco, Ross I.; Nishioka, Seiko; Shirato, Hiroki; Heijmen, Ben

    2007-07-15

    The Synchrony{sup TM} Respiratory Tracking System (RTS) is a treatment option of the CyberKnife robotic treatment device to irradiate extra-cranial tumors that move due to respiration. Advantages of RTS are that patients can breath normally and that there is no loss of linac duty cycle such as with gated therapy. Tracking is based on a measured correspondence model (linear or polynomial) between internal tumor motion and external (chest/abdominal) marker motion. The radiation beam follows the tumor movement via the continuously measured external marker motion. To establish the correspondence model at the start of treatment, the 3D internal tumor position is determined at 15 discrete time points by automatic detection of implanted gold fiducials in two orthogonal x-ray images; simultaneously, the positions of the external markers are measured. During the treatment, the relationship between internal and external marker positions is continuously accounted for and is regularly checked and updated. Here we use computer simulations based on continuously and simultaneously recorded internal and external marker positions to investigate the effectiveness of tumor tracking by the RTS. The Cyberknife does not allow continuous acquisition of x-ray images to follow the moving internal markers (typical imaging frequency is once per minute). Therefore, for the simulations, we have used data for eight lung cancer patients treated with respiratory gating. All of these patients had simultaneous and continuous recordings of both internal tumor motion and external abdominal motion. The available continuous relationship between internal and external markers for these patients allowed investigation of the consequences of the lower acquisition frequency of the RTS. With the use of the RTS, simulated treatment errors due to breathing motion were reduced largely and consistently over treatment time for all studied patients. A considerable part of the maximum reduction in treatment error

  19. Methodological quality and outcomes of studies addressing manual cervical spine examinations: a review.

    PubMed

    Hollerwöger, Dieter

    2006-05-01

    The aims of this review were, first to rate the methodological quality of studies which investigate the reliability of manual tests for cervical spine dysfunctions by applying a new quality assessment tool; secondly to compare the outcomes of these studies. The literature search included databases of CINAHL, MEDLINE, AMED, AMI, and SPORT DISCUS, the Cochrane Library, the Physiotherapy Evidence Database (PEDro), the National Library of Medicine (PubMed), Factiva, the EBSCOT HOST Research Database, online journal databases of ELSEVIER Science periodicals, LIPPINCOTT WILLIAMS & WILKINS, ELSEVIER Science @ Direct, THIEME ONLINE, and BLACKWELL SYNERGY. The application of the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS) to the 15 studies which met the inclusion criteria showed methodological weaknesses such as not considering an independent reference standard, or a representative study population. The studies demonstrated methodological strength in describing selection criteria and in interpreting results. The studies' outcomes make the claim to be able to detect segmental cervical dysfunction based on a manual assessment only questionable. Further improvements in quality, uniform study designs, and a valid reference standard would be necessary in order to obtain more reliable data in the future.

  20. The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

    PubMed Central

    Kumari, Nirmala; Nandeeshwar, D. B.

    2015-01-01

    Aim of the Study: To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique. Methodology: A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint™ II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector. Statistical Analysis: The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student's Newman–Keul's test. Results: When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint™ II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint™ II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint™ II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively. Conclusion: Among the impression materials Imprint™ II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results. PMID:26929515

  1. A Comparison of Accuracy of Matrix Impression System with Putty Reline Technique and Multiple Mix Technique: An In Vitro Study

    PubMed Central

    Kumar, M Praveen; Patil, Suneel G; Dheeraj, Bhandari; Reddy, Keshav; Goel, Dinker; Krishna, Gopi

    2015-01-01

    Background: The difficulty in obtaining an acceptable impression increases exponentially as the number of abutments increases. Accuracy of the impression material and the use of a suitable impression technique are of utmost importance in the fabrication of a fixed partial denture. This study compared the accuracy of the matrix impression system with conventional putty reline and multiple mix technique for individual dies by comparing the inter-abutment distance in the casts obtained from the impressions. Materials and Methods: Three groups, 10 impressions each with three impression techniques (matrix impression system, putty reline technique and multiple mix technique) were made of a master die. Typodont teeth were embedded in a maxillary frasaco model base. The left first premolar was removed to create a three-unit fixed partial denture situation and the left canine and second premolar were prepared conservatively, and hatch marks were made on the abutment teeth. The final casts obtained from the impressions were examined under a profile projector and the inter-abutment distance was calculated for all the casts and compared. Results: The results from this study showed that in the mesiodistal dimensions the percentage deviation from master model in Group I was 0.1 and 0.2, in Group II was 0.9 and 0.3, and Group III was 1.6 and 1.5, respectively. In the labio-palatal dimensions the percentage deviation from master model in Group I was 0.01 and 0.4, Group II was 1.9 and 1.3, and Group III was 2.2 and 2.0, respectively. In the cervico-incisal dimensions the percentage deviation from the master model in Group I was 1.1 and 0.2, Group II was 3.9 and 1.7, and Group III was 1.9 and 3.0, respectively. In the inter-abutment dimension of dies, percentage deviation from master model in Group I was 0.1, Group II was 0.6, and Group III was 1.0. Conclusion: The matrix impression system showed more accuracy of reproduction for individual dies when compared with putty reline

  2. Dosimetric accuracy of the cone-beam CT-based treatment planning of the Vero system: a phantom study.

    PubMed

    Yohannes, Indra; Prasetio, Heru; Kallis, Karoline; Bert, Christoph

    2016-01-01

    We report an investigation on the accuracy of dose calculation based on the cone-beam computed tomography (CBCT) images of the nonbowtie filter kV imaging system of the Vero linear accelerator. Different sets of materials and tube voltages were employed to generate the Hounsfield unit lookup tables (HLUTs) for both CBCT and fan-beam CT (FBCT) systems. The HLUTs were then implemented for the dose calculation in a treatment planning system (TPS). Dosimetric evaluation was carried out on an in-house-developed cube phantom that consists of water-equivalent slabs and inhomogeneity inserts. Two independent dosimeters positioned in the cube phantom were used in this study for point-dose and two-dimensional (2D) dose distribution measurements. The differences of HLUTs from various materials and tube voltages in both CT systems resulted in differences in dose calculation accuracy. We found that the higher the tube voltage used to obtain CT images, the better the point-dose calculation and the gamma passing rate of the 2D dose distribution agree to the values determined in the TPS. Moreover, the insert materials that are not tissue-equivalent led to higher dose-calculation inaccuracy. There were negligible differences in dosimetric evaluation between the CBCT- and FBCT-based treatment planning if the HLUTs were generated using the tissue-equivalent materials. In this study, the CBCT images of the Vero system from a complex inhomogeneity phantom can be applied for the TPS dose calculation if the system is calibrated using tissue-equivalent materials scanned at high tube voltage (i.e., 120 kV). PMID:27455496

  3. Precision and accuracy in the quantitative analysis of biological samples by accelerator mass spectrometry: application in microdose absolute bioavailability studies.

    PubMed

    Gao, Lan; Li, Jing; Kasserra, Claudia; Song, Qi; Arjomand, Ali; Hesk, David; Chowdhury, Swapan K

    2011-07-15

    Determination of the pharmacokinetics and absolute bioavailability of an experimental compound, SCH 900518, following a 89.7 nCi (100 μg) intravenous (iv) dose of (14)C-SCH 900518 2 h post 200 mg oral administration of nonradiolabeled SCH 900518 to six healthy male subjects has been described. The plasma concentration of SCH 900518 was measured using a validated LC-MS/MS system, and accelerator mass spectrometry (AMS) was used for quantitative plasma (14)C-SCH 900518 concentration determination. Calibration standards and quality controls were included for every batch of sample analysis by AMS to ensure acceptable quality of the assay. Plasma (14)C-SCH 900518 concentrations were derived from the regression function established from the calibration standards, rather than directly from isotopic ratios from AMS measurement. The precision and accuracy of quality controls and calibration standards met the requirements of bioanalytical guidance (U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research, Center for Veterinary Medicine. Guidance for Industry: Bioanalytical Method Validation (ucm070107), May 2001. http://www.fda.gov/downloads/Drugs/GuidanceCompilanceRegulatoryInformation/Guidances/ucm070107.pdf ). The AMS measurement had a linear response range from 0.0159 to 9.07 dpm/mL for plasma (14)C-SCH 900158 concentrations. The CV and accuracy were 3.4-8.5% and 94-108% (82-119% for the lower limit of quantitation (LLOQ)), respectively, with a correlation coefficient of 0.9998. The absolute bioavailability was calculated from the dose-normalized area under the curve of iv and oral doses after the plasma concentrations were plotted vs the sampling time post oral dose. The mean absolute bioavailability of SCH 900518 was 40.8% (range 16.8-60.6%). The typical accuracy and standard deviation in AMS quantitative analysis of drugs from human plasma samples have been reported for the first time, and the impact of these

  4. Accuracy of a Wrist-Worn Wearable Device for Monitoring Heart Rates in Hospital Inpatients: A Prospective Observational Study

    PubMed Central

    Kroll, Ryan R; Boyd, J Gordon

    2016-01-01

    Background As the sensing capabilities of wearable devices improve, there is increasing interest in their application in medical settings. Capabilities such as heart rate monitoring may be useful in hospitalized patients as a means of enhancing routine monitoring or as part of an early warning system to detect clinical deterioration. Objective To evaluate the accuracy of heart rate monitoring by a personal fitness tracker (PFT) among hospital inpatients. Methods We conducted a prospective observational study of 50 stable patients in the intensive care unit who each completed 24 hours of heart rate monitoring using a wrist-worn PFT. Accuracy of heart rate recordings was compared with gold standard measurements derived from continuous electrocardiographic (cECG) monitoring. The accuracy of heart rates measured by pulse oximetry (Spo2.R) was also measured as a positive control. Results On a per-patient basis, PFT-derived heart rate values were slightly lower than those derived from cECG monitoring (average bias of −1.14 beats per minute [bpm], with limits of agreement of 24 bpm). By comparison, Spo2.R recordings produced more accurate values (average bias of +0.15 bpm, limits of agreement of 13 bpm, P<.001 as compared with PFT). Personal fitness tracker device performance was significantly better in patients in sinus rhythm than in those who were not (average bias −0.99 bpm vs −5.02 bpm, P=.02). Conclusions Personal fitness tracker–derived heart rates were slightly lower than those derived from cECG monitoring in real-world testing and not as accurate as Spo2.R-derived heart rates. Performance was worse among patients who were not in sinus rhythm. Further clinical evaluation is indicated to see if PFTs can augment early warning systems in hospitals. Trial Registration ClinicalTrials.gov NCT02527408; https://clinicaltrials.gov/ct2/show/NCT02527408 (Archived by WebCite at  http://www.webcitation.org/6kOFez3on) PMID:27651304

  5. A comparative evaluation of the marginal accuracy of crowns fabricated from four commercially available provisional materials: An in vitro study

    PubMed Central

    Amin, Bhavya Mohandas; Aras, Meena Ajay; Chitre, Vidya

    2015-01-01

    Purpose: The purpose of this in vitro study was to evaluate and compare the primary marginal accuracy of four commercially available provisional materials (Protemp 4, Luxatemp Star, Visalys Temp and DPI tooth moulding powder and liquid) at 2 time intervals (10 and 30 min). Materials and Methods: A customized stainless steel master model containing two interchangeable dies was used for fabrication of provisional crowns. Forty crowns (n = 10) were fabricated, and each crown was evaluated under a stereomicroscope. Vertical marginal discrepancies were noted and compared at 10 min since the start of mixing and then at 30 min. Observations and Results: Protemp 4 showed the least vertical marginal discrepancy (71.59 μ), followed by Luxatemp Star (91.93 μ) at 10 min. DPI showed a marginal discrepancy of 95.94 μ while Visalys Temp crowns had vertical marginal discrepancy of 106.81 μ. There was a significant difference in the marginal discrepancy values of Protemp 4 and Visalys Temp. At 30 min, there was a significant difference between the marginal discrepancy of Protemp 4 crowns (83.11 μ) and Visalys Temp crowns (128.97 μ) and between Protemp 4 and DPI (118.88 μ). No significant differences were observed between Protemp 4 and Luxatemp Star. Conclusion: The vertical marginal discrepancy of temporary crowns fabricated from the four commercially available provisional materials ranged from 71 to 106 μ immediately after fabrication (at 10 min from the start of mix) to 83–128 μ (30 min from the start of mix). The time elapsed after mixing had a significant influence on the marginal accuracy of the crowns. PMID:26097348

  6. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study

    PubMed Central

    Olivecrona, Henrik; Maguire, Gerald Q.; Noz, Marilyn E.; Zeleznik, Michael P.

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  7. Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

    2011-02-01

    Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS.

  8. A new automatic blood pressure kit auscultates for accurate reading with a smartphone: A diagnostic accuracy study.

    PubMed

    Wu, Hongjun; Wang, Bingjian; Zhu, Xinpu; Chu, Guang; Zhang, Zhi

    2016-08-01

    The widely used oscillometric automated blood pressure (BP) monitor was continuously questioned on its accuracy. A novel BP kit named Accutension which adopted Korotkoff auscultation method was then devised. Accutension worked with a miniature microphone, a pressure sensor, and a smartphone. The BP values were automatically displayed on the smartphone screen through the installed App. Data recorded in the phone could be played back and reconfirmed after measurement. They could also be uploaded and saved to the iCloud. The accuracy and consistency of this novel electronic auscultatory sphygmomanometer was preliminarily verified here. Thirty-two subjects were included and 82 qualified readings were obtained. The mean differences ± SD for systolic and diastolic BP readings between Accutension and mercury sphygmomanometer were 0.87 ± 2.86 and -0.94 ± 2.93 mm Hg. Agreements between Accutension and mercury sphygmomanometer were highly significant for systolic (ICC = 0.993, 95% confidence interval (CI): 0.989-0.995) and diastolic (ICC = 0.987, 95% CI: 0.979-0.991). In conclusion, Accutension worked accurately based on our pilot study data. The difference was acceptable. ICC and Bland-Altman plot charts showed good agreements with manual measurements. Systolic readings of Accutension were slightly higher than those of manual measurement, while diastolic readings were slightly lower. One possible reason was that Accutension captured the first and the last korotkoff sound more sensitively than human ear during manual measurement and avoided sound missing, so that it might be more accurate than traditional mercury sphygmomanometer. By documenting and analyzing of variant tendency of BP values, Accutension helps management of hypertension and therefore contributes to the mobile heath service. PMID:27512876

  9. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study.

    PubMed

    Brodén, Cyrus; Olivecrona, Henrik; Maguire, Gerald Q; Noz, Marilyn E; Zeleznik, Michael P; Sköldenberg, Olof

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  10. Multinomial tree models for assessing the status of the reference in studies of the accuracy of tools for binary classification

    PubMed Central

    Botella, Juan; Huang, Huiling; Suero, Manuel

    2013-01-01

    Studies that evaluate the accuracy of binary classification tools are needed. Such studies provide 2 × 2 cross-classifications of test outcomes and the categories according to an unquestionable reference (or gold standard). However, sometimes a suboptimal reliability reference is employed. Several methods have been proposed to deal with studies where the observations are cross-classified with an imperfect reference. These methods require that the status of the reference, as a gold standard or as an imperfect reference, is known. In this paper a procedure for determining whether it is appropriate to maintain the assumption that the reference is a gold standard or an imperfect reference, is proposed. This procedure fits two nested multinomial tree models, and assesses and compares their absolute and incremental fit. Its implementation requires the availability of the results of several independent studies. These should be carried out using similar designs to provide frequencies of cross-classification between a test and the reference under investigation. The procedure is applied in two examples with real data. PMID:24106484

  11. Multinomial tree models for assessing the status of the reference in studies of the accuracy of tools for binary classification.

    PubMed

    Botella, Juan; Huang, Huiling; Suero, Manuel

    2013-01-01

    Studies that evaluate the accuracy of binary classification tools are needed. Such studies provide 2 × 2 cross-classifications of test outcomes and the categories according to an unquestionable reference (or gold standard). However, sometimes a suboptimal reliability reference is employed. Several methods have been proposed to deal with studies where the observations are cross-classified with an imperfect reference. These methods require that the status of the reference, as a gold standard or as an imperfect reference, is known. In this paper a procedure for determining whether it is appropriate to maintain the assumption that the reference is a gold standard or an imperfect reference, is proposed. This procedure fits two nested multinomial tree models, and assesses and compares their absolute and incremental fit. Its implementation requires the availability of the results of several independent studies. These should be carried out using similar designs to provide frequencies of cross-classification between a test and the reference under investigation. The procedure is applied in two examples with real data.

  12. Zagreb Amblyopia Preschool Screening Study: near and distance visual acuity testing increase the diagnostic accuracy of screening for amblyopia

    PubMed Central

    Bušić, Mladen; Bjeloš, Mirjana; Petrovečki, Mladen; Kuzmanović Elabjer, Biljana; Bosnar, Damir; Ramić, Senad; Miletić, Daliborka; Andrijašević, Lidija; Kondža Krstonijević, Edita; Jakovljević, Vid; Bišćan Tvrdi, Ana; Predović, Jurica; Kokot, Antonio; Bišćan, Filip; Kovačević Ljubić, Mirna; Motušić Aras, Ranka

    2016-01-01

    Aim To present and evaluate a new screening protocol for amblyopia in preschool children. Methods Zagreb Amblyopia Preschool Screening (ZAPS) study protocol performed screening for amblyopia by near and distance visual acuity (VA) testing of 15 648 children aged 48-54 months attending kindergartens in the City of Zagreb County between September 2011 and June 2014 using Lea Symbols in lines test. If VA in either eye was >0.1 logMAR, the child was re-tested, if failed at re-test, the child was referred to comprehensive eye examination at the Eye Clinic. Results 78.04% of children passed the screening test. Estimated prevalence of amblyopia was 8.08%. Testability, sensitivity, and specificity of the ZAPS study protocol were 99.19%, 100.00%, and 96.68% respectively. Conclusion The ZAPS study used the most discriminative VA test with optotypes in lines as they do not underestimate amblyopia. The estimated prevalence of amblyopia was considerably higher than reported elsewhere. To the best of our knowledge, the ZAPS study protocol reached the highest sensitivity and specificity when evaluating diagnostic accuracy of VA tests for screening. The pass level defined at ≤0.1 logMAR for 4-year-old children, using Lea Symbols in lines missed no amblyopia cases, advocating that both near and distance VA testing should be performed when screening for amblyopia. PMID:26935612

  13. Does gadolinium-based contrast material improve diagnostic accuracy of local invasion in rectal cancer MRI? A multireader study.

    PubMed

    Gollub, Marc J; Lakhman, Yulia; McGinty, Katrina; Weiser, Martin R; Sohn, Michael; Zheng, Junting; Shia, Jinru

    2015-02-01

    OBJECTIVE. The purpose of this study was to compare reader accuracy and agreement on rectal MRI with and without gadolinium administration in the detection of T4 rectal cancer. MATERIALS AND METHODS. In this study, two radiologists and one fellow independently interpreted all posttreatment MRI studies for patients with locally advanced or recurrent rectal cancer using unenhanced images alone or combined with contrast-enhanced images, with a minimum interval of 4 weeks. Readers evaluated involvement of surrounding structures on a 5-point scale and were blinded to pathology and disease stage. Sensitivity, specificity, negative predictive value, positive predictive value, and AUC were calculated and kappa statistics were used to describe interreader agreement. RESULTS. Seventy-two patients (38 men and 34 women) with a mean age of 61 years (range, 32-86 years) were evaluated. Fifteen patients had 32 organs invaded. Global AUCs without and with gadolinium administration were 0.79 and 0.77, 0.91 and 0.86, and 0.83 and 0.78 for readers 1, 2, and 3, respectively. AUCs before and after gadolinium administration were similar. Kappa values before and after gadolinium administration for pairs of readers ranged from 0.5 to 0.7. CONCLUSION. On the basis of pathology as a reference standard, the use of gadolinium during rectal MRI did not significantly improve radiologists' agreement or ability to detect T4 disease.

  14. Pitfalls at the root of facial assessment on photographs: a quantitative study of accuracy in positioning facial landmarks.

    PubMed

    Cummaudo, M; Guerzoni, M; Marasciuolo, L; Gibelli, D; Cigada, A; Obertovà, Z; Ratnayake, M; Poppa, P; Gabriel, P; Ritz-Timme, S; Cattaneo, C

    2013-05-01

    In the last years, facial analysis has gained great interest also for forensic anthropology. The application of facial landmarks may bring about relevant advantages for the analysis of 2D images by measuring distances and extracting quantitative indices. However, this is a complex task which depends upon the variability in positioning facial landmarks. In addition, literature provides only general indications concerning the reliability in positioning facial landmarks on photographic material, and no study is available concerning the specific errors which may be encountered in such an operation. The aim of this study is to analyze the inter- and intra-observer error in defining facial landmarks on photographs by using a software specifically developed for this purpose. Twenty-four operators were requested to define 22 facial landmarks on frontal view photographs and 11 on lateral view images; in addition, three operators repeated the procedure on the same photographs 20 times (at distance of 24 h). In the frontal view, the landmarks with less dispersion were the pupil, cheilion, endocanthion, and stomion (sto), and the landmarks with the highest dispersion were gonion, zygion, frontotemporale, tragion, and selion (se). In the lateral view, the landmarks with the least dispersion were se, pronasale, subnasale, and sto, whereas landmarks with the highest dispersion were gnathion, pogonion, and tragion. Results confirm that few anatomical points can be defined with the highest accuracy and show the importance of the preliminary investigation of reliability in positioning facial landmarks. PMID:23515681

  15. Pitfalls at the root of facial assessment on photographs: a quantitative study of accuracy in positioning facial landmarks.

    PubMed

    Cummaudo, M; Guerzoni, M; Marasciuolo, L; Gibelli, D; Cigada, A; Obertovà, Z; Ratnayake, M; Poppa, P; Gabriel, P; Ritz-Timme, S; Cattaneo, C

    2013-05-01

    In the last years, facial analysis has gained great interest also for forensic anthropology. The application of facial landmarks may bring about relevant advantages for the analysis of 2D images by measuring distances and extracting quantitative indices. However, this is a complex task which depends upon the variability in positioning facial landmarks. In addition, literature provides only general indications concerning the reliability in positioning facial landmarks on photographic material, and no study is available concerning the specific errors which may be encountered in such an operation. The aim of this study is to analyze the inter- and intra-observer error in defining facial landmarks on photographs by using a software specifically developed for this purpose. Twenty-four operators were requested to define 22 facial landmarks on frontal view photographs and 11 on lateral view images; in addition, three operators repeated the procedure on the same photographs 20 times (at distance of 24 h). In the frontal view, the landmarks with less dispersion were the pupil, cheilion, endocanthion, and stomion (sto), and the landmarks with the highest dispersion were gonion, zygion, frontotemporale, tragion, and selion (se). In the lateral view, the landmarks with the least dispersion were se, pronasale, subnasale, and sto, whereas landmarks with the highest dispersion were gnathion, pogonion, and tragion. Results confirm that few anatomical points can be defined with the highest accuracy and show the importance of the preliminary investigation of reliability in positioning facial landmarks.

  16. A computer simulation study comparing lesion detection accuracy with digital mammography, breast tomosynthesis, and cone-beam CT breast imaging

    SciTech Connect

    Gong Xing; Glick, Stephen J.; Liu, Bob; Vedula, Aruna A.; Thacker, Samta

    2006-04-15

    Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a three-dimensional (3D) object onto a 2D plane. Recently, two promising approaches for 3D volumetric breast imaging have been proposed, breast tomosynthesis (BT) and CT breast imaging (CTBI). To investigate possible improvements in lesion detection accuracy with either breast tomosynthesis or CT breast imaging as compared to digital mammography (DM), a computer simulation study was conducted using simulated lesions embedded into a structured 3D breast model. The computer simulation realistically modeled x-ray transport through a breast model, as well as the signal and noise propagation through a CsI based flat-panel imager. Polyenergetic x-ray spectra of Mo/Mo 28 kVp for digital mammography, Mo/Rh 28 kVp for BT, and W/Ce 50 kVp for CTBI were modeled. For the CTBI simulation, the intensity of the x-ray spectra for each projection view was determined so as to provide a total average glandular dose of 4 mGy, which is approximately equivalent to that given in conventional two-view screening mammography. The same total dose was modeled for both the DM and BT simulations. Irregular lesions were simulated by using a stochastic growth algorithm providing lesions with an effective diameter of 5 mm. Breast tissue was simulated by generating an ensemble of backgrounds with a power law spectrum, with the composition of 50% fibroglandular and 50% adipose tissue. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with five observers reading an ensemble of images for each case. The average area under the ROC curves (A{sub z}) was 0.76 for DM, 0.93 for BT, and 0.94 for CTBI. Results indicated that for the same dose, a 5 mm lesion embedded in a structured breast phantom was detected by the two volumetric breast imaging systems, BT and CTBI, with statistically

  17. Assessing accuracy of gas-driven permeability measurements: a comparative study of diverse Hassler-cell and probe permeameter devices

    NASA Astrophysics Data System (ADS)

    Filomena, C. M.; Hornung, J.; Stollhofen, H.

    2013-08-01

    Permeability is one of the most important petrophysical parameters to describe the reservoir potential of sedimentary rocks, contributing to problems in hydrology, geothermics, or hydrocarbon reservoir analysis. Outcrop analog studies, well core measurements, or individual sample analysis take advantage of a variety of commercially available devices for permeability measurements. Very often, permeability data derived from different devices need to be merged within one study, e.g. outcrop mini-permeametry and lab-based core plug measurements. To enhance accuracy of different gas-driven permeability measurements, device-specific aberrations need to be taken into account. The application of simple one-to-one correlations may draw a wrong picture of permeability trends. For this purpose, transform equations need to be established. This study presents a detailed comparison of permeability data derived from a selection of commonly used Hassler cells and probe permeameters. As a result of individual cross-plots, typical aberrations and transform equations are elaborated which enable corrections for the specific permeameters. Permeability measurements of the commercially available ErgoTech Gas Permeameter and the TinyPerm II probe-permeameter are well-comparable over the entire range of permeability, with R2 = 0.967. Major aberrations are identified among the TinyPerm II and the mini-permeameter/Hassler-cell combination at Darmstadt University, which need to be corrected and standardized within one study. However, transforms are critical to their use, as aberrations are frequently limited to certain permeability intervals. In the presented examples, deviations typically tend to occur in the lower permeability range < 10 mD. Applying standardizations which consider these aberration intervals strongly improve the comparability of permeability datasets and facilitate the combination of measurement principles. Therefore, the utilization of such correlation tests is highly

  18. A Meta-Analysis of the Accuracy of Prostate Cancer Studies Which Use Magnetic Resonance Spectroscopy as a Diagnostic Tool

    PubMed Central

    Guo, You-min; Liu, Min; Qiang, Yong-qian; Guo, Xiao-juan; Zhang, Yi-li; Duan, Xiao-Yi; Zhang, Qiu-Juan; Liang, Weifeng

    2008-01-01

    Objective We aimed to do a meta-analysis of the existing literature to assess the accuracy of prostate cancer studies which use magnetic resonance spectroscopy (MRS) as a diagnostic tool. Materials and Methods Prospectively, independent, blind studies were selected from the Cochrane library, Pubmed, and other network databases. The criteria for inclusion and exclusion in this study referenced the criteria of diagnostic research published by the Cochrane center. The statistical analysis was adopted by using Meta-Test version 6.0. Using the homogeneity test, a statistical effect model was chosen to calculate different pooled weighted values of sensitivity, specificity, and the corresponding 95% confidence intervals (95% CI). The summary receiver operating characteristic (SROC) curves method was used to assess the results. Results We chose two cut-off values (0.75 and 0.86) as the diagnostic criteria for discriminating between benign and malignant. In the first diagnostic criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI (expressed as area under curve [AUC]) were 0.82 (0.73, 0.89), 0.68 (0.58, 0.76), and 83.4% (74.97, 91.83). In the second criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI were 0.64 (0.55, 0.72), 0.86 (0.79, 0.91) and 82.7% (68.73, 96.68). Conclusion As a new method in the diagnostic of prostate cancer, MRS has a better applied value compared to other common modalities. Ultimately, large scale RCT randomized controlled trial studies are necessary to assess its clinical value. PMID:18838853

  19. Assessing accuracy of gas-driven permeability measurements: a comparative study of diverse Hassler-cell and probe permeameter devices

    NASA Astrophysics Data System (ADS)

    Filomena, C. M.; Hornung, J.; Stollhofen, H.

    2014-01-01

    Permeability is one of the most important petrophysical parameters to describe the reservoir properties of sedimentary rocks, pertaining to problems in hydrology, geothermics, and hydrocarbon reservoir analysis. Outcrop analogue studies, well core measurements, and individual sample analysis take advantage of a variety of commercially available devices for permeability measurements. Very often, permeability data derived from different devices need to be merged within one study (e.g. outcrop minipermeametry and lab-based core plug measurements). To enhance accuracy of different gas-driven permeability measurements, device-specific aberrations need to be taken into account. The application of simple one-to-one correlations may draw the wrong picture of permeability trends. For this purpose, transform equations need to be established. This study presents a detailed comparison of permeability data derived from a selection of commonly used Hassler cells and probe permeameters. As a result of individual cross-plots, typical aberrations and transform equations are elaborated, which enable corrections for the specific permeameters. Permeability measurements of the commercially available ErgoTech gas permeameter and the TinyPerm II probe permeameter are well-comparable over the entire range of permeability, with R2 = 0.955. Aberrations are mostly identified in the permeability range < 10 mD, regarding the TinyPerm II and the minipermeameter/Hassler-cell combination at Darmstadt University, which need to be corrected and standardized. Applying standardizations which consider these aberration intervals strongly improves the comparability of permeability data sets and facilitates the combination of measurement principles. Therefore, the utilization of such correlation tests is highly recommended for all kinds of reservoir studies using integrated permeability databases.

  20. Improved Accuracy of Continuous Glucose Monitoring Systems in Pediatric Patients with Diabetes Mellitus: Results from Two Studies

    PubMed Central

    2016-01-01

    Abstract Objective: This study was designed to evaluate accuracy, performance, and safety of the Dexcom (San Diego, CA) G4® Platinum continuous glucose monitoring (CGM) system (G4P) compared with the Dexcom G4 Platinum with Software 505 algorithm (SW505) when used as adjunctive management to blood glucose (BG) monitoring over a 7-day period in youth, 2–17 years of age, with diabetes. Research Design and Methods: Youth wore either one or two sensors placed on the abdomen or upper buttocks for 7 days, calibrating the device twice daily with a uniform BG meter. Participants had one in-clinic session on Day 1, 4, or 7, during which fingerstick BG measurements (self-monitoring of blood glucose [SMBG]) were obtained every 30 ± 5 min for comparison with CGM, and in youth 6–17 years of age, reference YSI glucose measurements were obtained from arterialized venous blood collected every 15 ± 5 min for comparison with CGM. The sensor was removed by the participant/family after 7 days. Results: In comparison of 2,922 temporally paired points of CGM with the reference YSI measurement for G4P and 2,262 paired points for SW505, the mean absolute relative difference (MARD) was 17% for G4P versus 10% for SW505 (P < 0.0001). In comparison of 16,318 temporally paired points of CGM with SMBG for G4P and 4,264 paired points for SW505, MARD was 15% for G4P versus 13% for SW505 (P < 0.0001). Similarly, error grid analyses indicated superior performance with SW505 compared with G4P in comparison of CGM with YSI and CGM with SMBG results, with greater percentages of SW505 results falling within error grid Zone A or the combined Zones A plus B. There were no serious adverse events or device-related serious adverse events for either the G4P or the SW505, and there was no sensor breakoff. Conclusions: The updated algorithm offers substantial improvements in accuracy and performance in pediatric patients with diabetes. Use of CGM with improved performance has

  1. Cost-Saving Early Diagnosis of Functional Pain in Nonmalignant Pain: A Noninferiority Study of Diagnostic Accuracy

    PubMed Central

    Cámara, Rafael J. A.; Merz, Christian; von Känel, Roland; Egloff, Niklaus

    2016-01-01

    Objectives. We compared two index screening tests for early diagnosis of functional pain: pressure pain measurement by electronic diagnostic equipment, which is accurate but too specialized for primary health care, versus peg testing, which is cost-saving and more easily manageable but of unknown sensitivity and specificity. Early distinction of functional (altered pain perception; nervous sensitization) from neuropathic or nociceptive pain improves pain management. Methods. Clinicians blinded for the index screening tests assessed the reference standard of this noninferiority diagnostic accuracy study, namely, comprehensive medical history taking with all previous findings and treatment outcomes. All consenting patients referred to a university hospital for nonmalignant musculoskeletal pain participated. The main analysis compared the receiver operating characteristic (ROC) curves of both index screening tests. Results. The area under the ROC curve for peg testing was not inferior to that of electronic equipment: it was at least 95% as large for finger measures (two-sided p = 0.038) and at least equally as large for ear measures (two-sided p = 0.003). Conclusions. Routine diagnostic testing by peg, which is accessible for general practitioners, is at least as accurate as specialized equipment. This may shorten time-to-treatment in general practices, thereby improving the prognosis and quality of life. PMID:27088013

  2. Accuracy of cut-off value by measurement of third molar index: Study of a Colombian sample.

    PubMed

    De Luca, Stefano; Aguilar, Lina; Rivera, Marcela; Palacio, Luz Andrea Velandia; Riccomi, Giulia; Bestetti, Fiorella; Cameriere, Roberto

    2016-04-01

    The aim of this cross-sectional study was to test the accuracy of cut-off value of 0.08 by measurement of third molar index (I3M) in assessing legal adult age of 18 years in a sample of Colombian children and young adults. Digital orthopantomographs of 288 Colombian children and young adults (163 girls and 125 boys), aged between 13 and 22 years, were analysed. Concordance correlation coefficient (ρc) and κ statistics (Cohen's Kappa coefficient) showed that repeatability and reproducibility are high for both intra- and inter-observer error. κ statistics for intra- and inter-observer agreement in decision on adult or minor was 0.913 and 0.877, respectively. Age distribution gradually decreases as I3M increases in both girls and boys. For girls, the sensitivity test was 95.1% (95% CI 87.1%-95%) and specificity was 93.8% (95% CI 87.1%-98.8%). The proportion of correctly classified individuals was 95.1%. For boys, the sensitivity test was 91.7% (95% CI 85.1%-96.8%) and specificity was 90.6% (95% CI 82.1%-97.8%). The proportion of correctly classified individuals was 89.7%. The cut-off value of 0.08 is highly useful to determine if a subject is 18 years of age or older or not. PMID:26898677

  3. Accuracy of cut-off value by measurement of third molar index: Study of a Colombian sample.

    PubMed

    De Luca, Stefano; Aguilar, Lina; Rivera, Marcela; Palacio, Luz Andrea Velandia; Riccomi, Giulia; Bestetti, Fiorella; Cameriere, Roberto

    2016-04-01

    The aim of this cross-sectional study was to test the accuracy of cut-off value of 0.08 by measurement of third molar index (I3M) in assessing legal adult age of 18 years in a sample of Colombian children and young adults. Digital orthopantomographs of 288 Colombian children and young adults (163 girls and 125 boys), aged between 13 and 22 years, were analysed. Concordance correlation coefficient (ρc) and κ statistics (Cohen's Kappa coefficient) showed that repeatability and reproducibility are high for both intra- and inter-observer error. κ statistics for intra- and inter-observer agreement in decision on adult or minor was 0.913 and 0.877, respectively. Age distribution gradually decreases as I3M increases in both girls and boys. For girls, the sensitivity test was 95.1% (95% CI 87.1%-95%) and specificity was 93.8% (95% CI 87.1%-98.8%). The proportion of correctly classified individuals was 95.1%. For boys, the sensitivity test was 91.7% (95% CI 85.1%-96.8%) and specificity was 90.6% (95% CI 82.1%-97.8%). The proportion of correctly classified individuals was 89.7%. The cut-off value of 0.08 is highly useful to determine if a subject is 18 years of age or older or not.

  4. Evaluation of accuracy of non-linear finite element computations for surgical simulation: study using brain phantom.

    PubMed

    Ma, J; Wittek, A; Singh, S; Joldes, G; Washio, T; Chinzei, K; Miller, K

    2010-12-01

    In this paper, the accuracy of non-linear finite element computations in application to surgical simulation was evaluated by comparing the experiment and modelling of indentation of the human brain phantom. The evaluation was realised by comparing forces acting on the indenter and the deformation of the brain phantom. The deformation of the brain phantom was measured by tracking 3D motions of X-ray opaque markers, placed within the brain phantom using a custom-built bi-plane X-ray image intensifier system. The model was implemented using the ABAQUS(TM) finite element solver. Realistic geometry obtained from magnetic resonance images and specific constitutive properties determined through compression tests were used in the model. The model accurately predicted the indentation force-displacement relations and marker displacements. Good agreement between modelling and experimental results verifies the reliability of the finite element modelling techniques used in this study and confirms the predictive power of these techniques in surgical simulation. PMID:21153973

  5. Improving the Accuracy of Whole Genome Prediction for Complex Traits Using the Results of Genome Wide Association Studies

    PubMed Central

    Zhang, Zhe; Ober, Ulrike; Erbe, Malena; Zhang, Hao; Gao, Ning; He, Jinlong; Li, Jiaqi; Simianer, Henner

    2014-01-01

    Utilizing the whole genomic variation of complex traits to predict the yet-to-be observed phenotypes or unobserved genetic values via whole genome prediction (WGP) and to infer the underlying genetic architecture via genome wide association study (GWAS) is an interesting and fast developing area in the context of human disease studies as well as in animal and plant breeding. Though thousands of significant loci for several species were detected via GWAS in the past decade, they were not used directly to improve WGP due to lack of proper models. Here, we propose a generalized way of building trait-specific genomic relationship matrices which can exploit GWAS results in WGP via a best linear unbiased prediction (BLUP) model for which we suggest the name BLUP|GA. Results from two illustrative examples show that using already existing GWAS results from public databases in BLUP|GA improved the accuracy of WGP for two out of the three model traits in a dairy cattle data set, and for nine out of the 11 traits in a rice diversity data set, compared to the reference methods GBLUP and BayesB. While BLUP|GA outperforms BayesB, its required computing time is comparable to GBLUP. Further simulation results suggest that accounting for publicly available GWAS results is potentially more useful for WGP utilizing smaller data sets and/or traits of low heritability, depending on the genetic architecture of the trait under consideration. To our knowledge, this is the first study incorporating public GWAS results formally into the standard GBLUP model and we think that the BLUP|GA approach deserves further investigations in animal breeding, plant breeding as well as human genetics. PMID:24663104

  6. Improving the accuracy of whole genome prediction for complex traits using the results of genome wide association studies.

    PubMed

    Zhang, Zhe; Ober, Ulrike; Erbe, Malena; Zhang, Hao; Gao, Ning; He, Jinlong; Li, Jiaqi; Simianer, Henner

    2014-01-01

    Utilizing the whole genomic variation of complex traits to predict the yet-to-be observed phenotypes or unobserved genetic values via whole genome prediction (WGP) and to infer the underlying genetic architecture via genome wide association study (GWAS) is an interesting and fast developing area in the context of human disease studies as well as in animal and plant breeding. Though thousands of significant loci for several species were detected via GWAS in the past decade, they were not used directly to improve WGP due to lack of proper models. Here, we propose a generalized way of building trait-specific genomic relationship matrices which can exploit GWAS results in WGP via a best linear unbiased prediction (BLUP) model for which we suggest the name BLUP|GA. Results from two illustrative examples show that using already existing GWAS results from public databases in BLUP|GA improved the accuracy of WGP for two out of the three model traits in a dairy cattle data set, and for nine out of the 11 traits in a rice diversity data set, compared to the reference methods GBLUP and BayesB. While BLUP|GA outperforms BayesB, its required computing time is comparable to GBLUP. Further simulation results suggest that accounting for publicly available GWAS results is potentially more useful for WGP utilizing smaller data sets and/or traits of low heritability, depending on the genetic architecture of the trait under consideration. To our knowledge, this is the first study incorporating public GWAS results formally into the standard GBLUP model and we think that the BLUP|GA approach deserves further investigations in animal breeding, plant breeding as well as human genetics.

  7. A comparative study between evaluation methods for quality control procedures for determining the accuracy of PET/CT registration

    NASA Astrophysics Data System (ADS)

    Cha, Min Kyoung; Ko, Hyun Soo; Jung, Woo Young; Ryu, Jae Kwang; Choe, Bo-Young

    2015-08-01

    The Accuracy of registration between positron emission tomography (PET) and computed tomography (CT) images is one of the important factors for reliable diagnosis in PET/CT examinations. Although quality control (QC) for checking alignment of PET and CT images should be performed periodically, the procedures have not been fully established. The aim of this study is to determine optimal quality control (QC) procedures that can be performed at the user level to ensure the accuracy of PET/CT registration. Two phantoms were used to carry out this study: the American college of Radiology (ACR)-approved PET phantom and National Electrical Manufacturers Association (NEMA) International Electrotechnical Commission (IEC) body phantom, containing fillable spheres. All PET/CT images were acquired on a Biograph TruePoint 40 PET/CT scanner using routine protocols. To measure registration error, the spatial coordinates of the estimated centers of the target slice (spheres) was calculated independently for the PET and the CT images in two ways. We compared the images from the ACR-approved PET phantom to that from the NEMA IEC body phantom. Also, we measured the total time required from phantom preparation to image analysis. The first analysis method showed a total difference of 0.636 ± 0.11 mm for the largest hot sphere and 0.198 ± 0.09 mm for the largest cold sphere in the case of the ACR-approved PET phantom. In the NEMA IEC body phantom, the total difference was 3.720 ± 0.97 mm for the largest hot sphere and 4.800 ± 0.85 mm for the largest cold sphere. The second analysis method showed that the differences in the x location at the line profile of the lesion on PET and CT were (1.33, 1.33) mm for a bone lesion, (-1.26, -1.33) mm for an air lesion and (-1.67, -1.60) mm for a hot sphere lesion for the ACR-approved PET phantom. For the NEMA IEC body phantom, the differences in the x location at the line profile of the lesion on PET and CT were (-1.33, 4.00) mm for the air

  8. The ADENOMA Study. Accuracy of Detection using Endocuff Vision™ Optimization of Mucosal Abnormalities: study protocol for randomized controlled trial

    PubMed Central

    Bevan, Roisin; Ngu, Wee Sing; Saunders, Brian P.; Tsiamoulos, Zacharias; Bassett, Paul; Hoare, Zoe; Rees, Colin J.

    2016-01-01

    Background: Colonoscopy is the gold standard investigation for the diagnosis of bowel pathology and colorectal cancer screening. Adenoma detection rate is a marker of high quality colonoscopy and a high adenoma detection rate is associated with a lower incidence of interval cancers. Several technological advancements have been explored to improve adenoma detection rate. A new device called Endocuff Vision™ has been shown to improve adenoma detection rate in pilot studies. Methods/Design: This is a prospective, multicenter, randomized controlled trial comparing the adenoma detection rate in patients undergoing Endocuff Vision™-assisted colonoscopy with standard colonoscopy. All patients above 18 years of age referred for screening, surveillance, or diagnostic colonoscopy who are able to consent are invited to the study. Patients with absolute contraindications to colonoscopy, large bowel obstruction or pseudo-obstruction, colon cancer or polyposis syndromes, colonic strictures, severe diverticular segments, active colitis, anticoagulant therapy, or pregnancy are excluded. Patients are randomized according to site, age, sex, and bowel cancer screening status to receive Endocuff Vision™-assisted colonoscopy or standard colonoscopy on the day of procedure. Baseline data, colonoscopy, and polyp data including histology are collected. Nurse assessment of patient comfort and patient comfort questionnaires are completed post procedure. Patients are followed up at 21 days and complete a patient experience questionnaire. This study will take place across seven NHS Hospital Trusts: one in London and six within the Northern Region Endoscopy Group. A maximum of 10 colonoscopists per site will recruit a total of 1772 patients, with a maximum of four bowel screening colonoscopists permitted per site. Discussion: This is the first trial to evaluate the adenoma detection rate of Endocuff Vision™ in all screening, surveillance, and diagnostic patient groups. This timely

  9. The efficacy of screening for common dental diseases by hygiene-therapists: a diagnostic test accuracy study.

    PubMed

    Macey, R; Glenny, A; Walsh, T; Tickle, M; Worthington, H; Ashley, J; Brocklehurst, P

    2015-03-01

    Regularly attending adult patients are increasingly asymptomatic and not in need of treatment when attending for their routine dental examinations. As oral health improves further, using the general dental practitioner to undertake the "checkup" on regular "low-risk" patients represents a substantial and potentially unnecessary cost for state-funded systems. Given recent regulatory changes in the United Kingdom, it is now theoretically possible to delegate a range of tasks to hygiene-therapists. This has the potential to release the general dental practitioner's time and increase the capacity to care. The aim of this study is to compare the diagnostic test accuracy of hygiene-therapists when screening for dental caries and periodontal disease in regularly attending asymptomatic adults who attend for their checkup. A visual screen by hygiene-therapists acted as the index test, and the general dental practitioner acted as the reference standard. Consenting asymptomatic adult patients, who were regularly attending patients at 10 practices across the Northwest of England, entered the study. Both sets of clinicians made an assessment of dental caries and periodontal disease. The primary outcomes measured were the sensitivity and specificity values for dental caries and periodontal disease. In total, 1899 patients were screened. The summary point for sensitivity of dental care professionals when screening for caries and periodontal disease was 0.81 (95% CI, 0.74 to 0.87) and 0.89 (0.86 to 0.92), respectively. The summary point for specificity of dental care professionals when screening for caries and periodontal disease was 0.87 (0.78 to 0.92) and 0.75 (0.66 to 0.82), respectively. The results suggest that hygiene-therapists could be used to screen for dental caries and periodontal disease. This has important ramifications for service design in public-funded health systems.

  10. The effect of mandibular buccal tilting on the accuracy of posterior mandibular spiral tomographic images: An in vitro study

    PubMed Central

    Sheikhi, Mahnaz; Maleki, Vida

    2011-01-01

    Background: Accurate measurement of the height and buccolingual thickness of available bone has a significant role in dental implantology. The shadow of ramus on the mandibular second molar region disturbs the sharpness of conventional tomographic images. The aim of this study was to evaluate the effect of transferring the shadow of ramus from the center of the focal plane, by changing the position of mandible, on the sharpness of the posterior mandibular region. Materials and Methods: In this experimental study, we used 10 dry human mandibles. Three metal balls were mounted on the midline and mandibular second molar regions bilaterally. Standard panoramic and tomographic images were taken. Then, the mandible was tilted buccaly for 8° – compensating the normal lingual inclination of the mandibular ridge and teeth on this region – and tomographic images were taken again. The height and thickness of bone were measured on the images and then compared with the real amounts measured directly on mandibles. Also, the sharpness of mandibular canals was compared between the two tomographic methods. Findings were analyzed with repeated measured ANOVA test (P<0.05). Results: The height of mandibular bone, on the images of the tilted tomography technique was more accurate compared to standard (P<0.001), but standard tomography had more accuracy in estimating the buccolingual thickness at the half-height point. Regarding the sharpness of mandibular canals, we found no significant differences between two tomographic methods. Conclusion: Buccal tilting is recommended when measuring the bone height is more important, but routine standard tomography is preferred when the thickness is requested. PMID:23372586

  11. In-vitro study on the accuracy of a simple-design CT-guided stent for dental implants

    PubMed Central

    Huh, Young-June; Choi, Bo-Ram; Huh, Kyung-Hoe; Yi, Won-Jin; Heo, Min-Suk; Lee, Sam-Sun

    2012-01-01

    Purpose An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results The deviation of the entry point and angulation of the central axis in the reference plane were 0.47±0.27 mm, 0.57±0.23 mm, and 0.64±0.16°, 0.57±0.15°, respectively. However, for the two different angulations in each group, the 20° angulation showed a greater error in the deviation of the entry point than did the 10° angulation. Conclusion The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort. PMID:23071963

  12. A Comparative Study on Diagnostic Accuracy of Colour Coded Digital Images, Direct Digital Images and Conventional Radiographs for Periapical Lesions – An In Vitro Study

    PubMed Central

    Mubeen; K.R., Vijayalakshmi; Bhuyan, Sanat Kumar; Panigrahi, Rajat G; Priyadarshini, Smita R; Misra, Satyaranjan; Singh, Chandravir

    2014-01-01

    Objectives: The identification and radiographic interpretation of periapical bone lesions is important for accurate diagnosis and treatment. The present study was undertaken to study the feasibility and diagnostic accuracy of colour coded digital radiographs in terms of presence and size of lesion and to compare the diagnostic accuracy of colour coded digital images with direct digital images and conventional radiographs for assessing periapical lesions. Materials and Methods: Sixty human dry cadaver hemimandibles were obtained and periapical lesions were created in first and second premolar teeth at the junction of cancellous and cortical bone using a micromotor handpiece and carbide burs of sizes 2, 4 and 6. After each successive use of round burs, a conventional, RVG and colour coded image was taken for each specimen. All the images were evaluated by three observers. The diagnostic accuracy for each bur and image mode was calculated statistically. Results: Our results showed good interobserver (kappa > 0.61) agreement for the different radiographic techniques and for the different bur sizes. Conventional Radiography outperformed Digital Radiography in diagnosing periapical lesions made with Size two bur. Both were equally diagnostic for lesions made with larger bur sizes. Colour coding method was least accurate among all the techniques. Conclusion: Conventional radiography traditionally forms the backbone in the diagnosis, treatment planning and follow-up of periapical lesions. Direct digital imaging is an efficient technique, in diagnostic sense. Colour coding of digital radiography was feasible but less accurate however, this imaging technique, like any other, needs to be studied continuously with the emphasis on safety of patients and diagnostic quality of images. PMID:25584318

  13. Diagnostic Accuracy Study of Intraoperative and Perioperative Serum Intact PTH Level for Successful Parathyroidectomy in 501 Secondary Hyperparathyroidism Patients

    PubMed Central

    Zhang, Lina; Xing, Changying; Shen, Chong; Zeng, Ming; Yang, Guang; Mao, Huijuan; Zhang, Bo; Yu, Xiangbao; Cui, Yiyao; Sun, Bin; Ouyang, Chun; Ge, Yifei; Jiang, Yao; Yin, Caixia; Zha, Xiaoming; Wang, Ningning

    2016-01-01

    Parathyroidectomy (PTX) is an effective treatment for severe secondary hyperparathyroidism (SHPT); however, persistent SHPT may occur because of supernumerary and ectopic parathyroids. Here a diagnostic accuracy study of intraoperative and perioperative serum intact parathyroid hormone (iPTH) was performed to predict successful surgery in 501 patients, who received total PTX + autotransplantation without thymectomy. Serum iPTH values before incision (io-iPTH0), 10 and 20 min after removing the last parathyroid (io-iPTH10, io-iPTH20), and the first and fourth day after PTX (D1-iPTH, D4-iPTH) were recoded. Patients whose serum iPTH was >50 pg/mL at the first postoperative week were followed up within six months. Successful PTX was defined if iPTH was <300 pg/mL, on the contrary, persistent SHPT was regarded. There were 86.4% patients underwent successful PTX, 9.8% remained as persistent SHPT and 3.8% were undetermined. Intraoperative serum iPTH demonstrated no significant differences in two subgroups with or without chronic hepatitis. Receiver operating characteristic (ROC) curves showed that >88.9% of io-iPTH20% could predict successful PTX (area under the curve [AUC] 0.909, sensitivity 78.6%, specificity 88.5%), thereby avoiding unnecessary exploration to reduce operative complications. D4-iPTH >147.4 pg/mL could predict persistent SHPT (AUC 0.998, sensitivity 100%, specificity 99.5%), so that medical intervention or reoperation start timely. PMID:27231027

  14. Physical Activity Level Improves the Predictive Accuracy of Cardiovascular Disease Risk Score: The ATTICA Study (2002–2012)

    PubMed Central

    Georgousopoulou, Ekavi N.; Panagiotakos, Demosthenes B.; Bougatsas, Dimitrios; Chatzigeorgiou, Michael; Kavouras, Stavros A.; Chrysohoou, Christina; Skoumas, Ioannis; Tousoulis, Dimitrios; Stefanadis, Christodoulos; Pitsavos, Christos

    2016-01-01

    Background: Although physical activity (PA) has long been associated with cardiovascular disease (CVD), assessment of PA status has never been used as a part of CVD risk prediction tools. The aim of the present work was to examine whether the inclusion of PA status in a CVD risk model improves its predictive accuracy. Methods: Data from the 10-year follow-up (2002–2012) of the n = 2020 participants (aged 18–89 years) of the ATTICA prospective study were used to test the research hypothesis. The HellenicSCORE (that incorporates age, sex, smoking, total cholesterol, and systolic blood pressure levels) was calculated to estimate the baseline 10-year CVD risk; assessment of PA status was based on the International Physical Activity Questionnaire. The estimated CVD risk was tested against the observed 10-year incidence (i.e., development of acute coronary syndromes, stroke, or other CVD according to the World Health Organization [WHO]-International Classification of Diseases [ICD]-10 criteria). Changes in the predictive ability of the nested CVD risk model that contained the HellenicSCORE plus PA assessment were evaluated using Harrell's C and net reclassification index. Results: Both HellenicSCORE and PA status were predictors of future CVD events (P < 0.05). However, the estimating classification bias of the model that included only the HellenicSCORE was significantly reduced when PA assessment was included (Harrel's C = 0.012, P = 0.032); this reduction remained significant even when adjusted for diabetes mellitus and dietary habits (P < 0.05). Conclusions: CVD risk scores seem to be more accurate by incorporating individuals’ PA status; thus, may be more effective tools in primary prevention by efficiently allocating CVD candidates. PMID:27076890

  15. Diagnostic Accuracy Study of Intraoperative and Perioperative Serum Intact PTH Level for Successful Parathyroidectomy in 501 Secondary Hyperparathyroidism Patients.

    PubMed

    Zhang, Lina; Xing, Changying; Shen, Chong; Zeng, Ming; Yang, Guang; Mao, Huijuan; Zhang, Bo; Yu, Xiangbao; Cui, Yiyao; Sun, Bin; Ouyang, Chun; Ge, Yifei; Jiang, Yao; Yin, Caixia; Zha, Xiaoming; Wang, Ningning

    2016-01-01

    Parathyroidectomy (PTX) is an effective treatment for severe secondary hyperparathyroidism (SHPT); however, persistent SHPT may occur because of supernumerary and ectopic parathyroids. Here a diagnostic accuracy study of intraoperative and perioperative serum intact parathyroid hormone (iPTH) was performed to predict successful surgery in 501 patients, who received total PTX + autotransplantation without thymectomy. Serum iPTH values before incision (io-iPTH0), 10 and 20 min after removing the last parathyroid (io-iPTH10, io-iPTH20), and the first and fourth day after PTX (D1-iPTH, D4-iPTH) were recoded. Patients whose serum iPTH was >50 pg/mL at the first postoperative week were followed up within six months. Successful PTX was defined if iPTH was <300 pg/mL, on the contrary, persistent SHPT was regarded. There were 86.4% patients underwent successful PTX, 9.8% remained as persistent SHPT and 3.8% were undetermined. Intraoperative serum iPTH demonstrated no significant differences in two subgroups with or without chronic hepatitis. Receiver operating characteristic (ROC) curves showed that >88.9% of io-iPTH20% could predict successful PTX (area under the curve [AUC] 0.909, sensitivity 78.6%, specificity 88.5%), thereby avoiding unnecessary exploration to reduce operative complications. D4-iPTH >147.4 pg/mL could predict persistent SHPT (AUC 0.998, sensitivity 100%, specificity 99.5%), so that medical intervention or reoperation start timely. PMID:27231027

  16. A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

    NASA Astrophysics Data System (ADS)

    Mangote, B.; Gallais, L.; Zerrad, M.; Lemarchand, F.; Gao, L. H.; Commandré, M.; Lequime, M.

    2012-01-01

    A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al2O3, Nb2O5, HfO2, SiO2, Ta2O5, and ZrO2. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

  17. Accuracy of Intraocular Lens Power Formulas Involving 148 Eyes with Long Axial Lengths: A Retrospective Chart-Review Study

    PubMed Central

    Chen, Chong; Xu, Xian; Miao, Yuyu; Zheng, Gaoxin; Sun, Yong; Xu, Xun

    2015-01-01

    Purpose. This study aims to compare the accuracy of intraocular lens power calculation formulas in eyes with long axial lengths from Chinese patients subjected to cataract surgery. Methods. A total of 148 eyes with an axial length of >26 mm from 148 patients who underwent phacoemulsification with intraocular lens implantation were included. The Haigis, Hoffer Q, Holladay 1, and SRK/T formulas were used to calculate the refractive power of the intraocular lenses and the postoperative estimated power. Results. Overall, the Haigis formula achieved the lowest level of median absolute error 1.025 D (P < 0.01 for Haigis versus each of the other formulas), followed by SRK/T formula (1.040 D). All formulas were least accurate when eyes were with axial length of >33 mm, and median absolute errors were significantly higher for those eyes than eyes with axial length = 26.01–30.00 mm. Absolute error was correlated with axial length for the SRK/T (r = 0.212, P = 0.010) and Hoffer Q (r = 0.223, P = 0.007) formulas. For axial lengths > 33 mm, eyes exhibited a postoperative hyperopic refractive error. Conclusions. The Haigis and SRK/T formulas may be more suitable for calculating intraocular lens power for eyes with axial lengths ranging from 26 to 33 mm. And for axial length over 33 mm, the Haigis formula could be more accurate. PMID:26793392

  18. Diagnostic accuracy of cardiothoracic ratio on admission chest radiography to detect left or right ventricular systolic dysfunction: a retrospective study

    PubMed Central

    Chana, Harmeet S; Martin, Claire A; Cakebread, Holly E; Adjei, Felicia D

    2015-01-01

    Objectives To determine the diagnostic accuracy of the cardiothoracic ratio on postero-anterior or antero-posterior chest radiographs in predicting left ventricular or right ventricular dysfunction on echocardiography in an inpatient population. Design Retrospective study. Setting Two secondary care hospitals in the United Kingdom. Participants Four hundred consecutive inpatient echocardiograms were screened for inclusion along with chest radiographs (both postero-anterior and antero-posterior). The cardiothoracic ratio was calculated from chest radiographs along with quantitative and qualitative measures of left ventricular or right ventricular dysfunction on echocardiography. Main outcome measures Sensitivity and specificity of cardiothoracic ratio across a range of values to detect moderate/severe left ventricular and/or right ventricular dysfunction on echocardiography. Results Overall, 272 records met inclusion criteria. The prevalence of left ventricular/right ventricular dysfunction on echocardiography was 26% in an inpatient population with high clinical suspicion of cardiac disease referred for echocardiography. Over a range of cardiothoracic ratio values on postero-anterior films, a value of >0.55 yielded the best sensitivity (62.5%) and specificity (76.5%) for diagnosing left ventricular/right ventricular impairment (positive likelihood ratio 2.56), with a positive predictive value of 29.5%. Cardiothoracic ratio on antero-posterior film was not predictive of left ventricular/right ventricular impairment on echocardiography. Conclusions In conclusion, in the context of an acute admission, cardiothoracic ratio measured on postero-anterior or antero-posterior films has limited value in detecting moderate left ventricular and/or right ventricular systolic dysfunction. Previously established absolute values may be unreliable by modern standards. PMID:26152673

  19. A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films

    SciTech Connect

    Mangote, B.; Gallais, L.; Zerrad, M.; Lemarchand, F.; Gao, L. H.; Commandre, M.; Lequime, M.

    2012-01-15

    A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al{sub 2}O{sub 3}, Nb{sub 2}O{sub 5}, HfO{sub 2}, SiO{sub 2}, Ta{sub 2}O{sub 5}, and ZrO{sub 2}. The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

  20. Positional Accuracy Assessment of the Openstreetmap Buildings Layer Through Automatic Homologous Pairs Detection: the Method and a Case Study

    NASA Astrophysics Data System (ADS)

    Brovelli, M. A.; Minghini, M.; Molinari, M. E.; Zamboni, G.

    2016-06-01

    OpenStreetMap (OSM) is currently the largest openly licensed collection of geospatial data. Being OSM increasingly exploited in a variety of applications, research has placed great attention on the assessment of its quality. This work focuses on assessing the quality of OSM buildings. While most of the studies available in literature are limited to the evaluation of OSM building completeness, this work proposes an original approach to assess the positional accuracy of OSM buildings based on comparison with a reference dataset. The comparison relies on a quasi-automated detection of homologous pairs on the two datasets. Based on the homologous pairs found, warping algorithms like e.g. affine transformations and multi-resolution splines can be applied to the OSM buildings to generate a new version having an optimal local match to the reference layer. A quality assessment of the OSM buildings of Milan Municipality (Northern Italy), having an area of about 180 km2, is then presented. After computing some measures of completeness, the algorithm based on homologous points is run using the building layer of the official vector cartography of Milan Municipality as the reference dataset. Approximately 100000 homologous points are found, which show a systematic translation of about 0.4 m on both the X and Y directions and a mean distance of about 0.8 m between the datasets. Besides its efficiency and high degree of automation, the algorithm generates a warped version of OSM buildings which, having by definition a closest match to the reference buildings, can be eventually integrated in the OSM database.

  1. The Effect of Delayed-JOLs and Sentence Generation on Children's Monitoring Accuracy and Regulation of Idiom Study

    ERIC Educational Resources Information Center

    van Loon, Mariëtte H.; de Bruin, Anique B. H.; van Gog, Tamara; van Merriënboer, Jeroen J. G.

    2013-01-01

    When studying verbal materials, both adults and children are often poor at accurately monitoring their level of learning and regulating their subsequent restudy of materials, which leads to suboptimal test performance. The present experiment investigated how monitoring accuracy and regulation of study could be improved when learning idiomatic…

  2. A Monte Carlo Study of the Effect of Item Characteristic Curve Estimation on the Accuracy of Three Person-Fit Statistics

    ERIC Educational Resources Information Center

    St-Onge, Christina; Valois, Pierre; Abdous, Belkacem; Germain, Stephane

    2009-01-01

    To date, there have been no studies comparing parametric and nonparametric Item Characteristic Curve (ICC) estimation methods on the effectiveness of Person-Fit Statistics (PFS). The primary aim of this study was to determine if the use of ICCs estimated by nonparametric methods would increase the accuracy of item response theory-based PFS for…

  3. Effects of random study checks and guided notes study cards on middle school special education students' notetaking accuracy and science vocabulary quiz scores

    NASA Astrophysics Data System (ADS)

    Wood, Charles L.

    Federal legislation mandates that all students with disabilities have meaningful access to the general education curriculum and that students with and without disabilities be held equally accountable to the same academic standards (IDEIA, 2004; NCLB, 2001). Many students with disabilities, however, perform poorly in academic content courses, especially at the middle and secondary school levels. Previous research has reported increased notetaking accuracy and quiz scores over lecture content when students completed guided notes compared to taking their own notes. This study evaluated the effects of a pre-quiz review procedure and specially formatted guided notes on middle school special education students' learning of science vocabulary. This study compared the effects of three experimental conditions. (a) Own Notes (ON), (b) Own Notes+Random Study Checks (ON+RSC), and (c) Guided Notes Study Cards+Random Study Checks (GNSC+RSC) on each student's accuracy of notes, next-day quiz scores, and review quiz scores. Each session, the teacher presented 12 science vocabulary terms and definitions during a lecture and students took notes. The students were given 5 minutes to study their notes at the end of each session and were reminded to study their notes at home and in study hall period. In the ON condition students took notes on a sheet of paper with numbered lines from 1 to 12. Just before each next-day quiz in the ON+RSC condition students used write-on response cards to answer two teacher-posed questions over randomly selected vocabulary terms from the previous day's lecture. If the answer on a randomly selected student's response card was correct, that student earned a lottery ticket for inexpensive prizes and a quiz bonus point for herself and each classmate. In the GNSC+RSC condition students took notes on specially formatted guided notes that after the lecture they cut into a set of flashcards that could used for study. The students' mean notetaking accuracy was 75

  4. Real-Word and Nonword Repetition in Italian-Speaking Children with Specific Language Impairment: A Study of Diagnostic Accuracy

    ERIC Educational Resources Information Center

    Dispaldro, Marco; Leonard, Laurence B.; Deevy, Patricia

    2013-01-01

    Purpose: Using 2 different scoring methods, the authors examined the diagnostic accuracy of both real-word and nonword repetition in identifying Italian-speaking children with and without specific language impairment (SLI). Method: A total of 34 children ages 3;11-5;8 (years;months) participated--17 children with SLI and 17 typically developing…

  5. The effects of relatedness and GxE interaction on prediction accuracies in genomic selection: a study in cassava

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prior to implementation of genomic selection, an evaluation of the potential accuracy of prediction can be obtained by cross validation. In this procedure, a population with both phenotypes and genotypes is split into training and validation sets. The prediction model is fitted using the training se...

  6. Referential Communication Accuracy of Mother-Child Pairs and Children's Later Scholastic Achievement: A Follow-Up Study.

    ERIC Educational Resources Information Center

    McDevitt, Teresa M.; And Others

    1987-01-01

    The relationship between the referential communication accuracy of mothers and their 4-year-old children and the children's achievement in vocabulary and mathematics at age 12 was examined in 47 American and 44 Japanese mother-child pairs. Positive correlations were found in both cultures. (Author/BN)

  7. Accuracy and efficacy of percutaneous biopsy and ablation using robotic assistance under computed tomography guidance: a phantom study

    PubMed Central

    Koethe, Yilun; Xu, Sheng; Velusamy, Gnanasekar; Wood, Bradford J.; Venkatesan, Aradhana M.

    2014-01-01

    Objective To compare the accuracy of a robotic interventional radiologist (IR) assistance platform with a standard freehand technique for computed-tomography (CT)-guided biopsy and simulated radiofrequency ablation (RFA). Methods The accuracy of freehand single-pass needle insertions into abdominal phantoms was compared with insertions facilitated with the use of a robotic assistance platform (n = 20 each). Post-procedural CTs were analysed for needle placement error. Percutaneous RFA was simulated by sequentially placing five 17-gauge needle introducers into 5-cm diameter masses (n = 5) embedded within an abdominal phantom. Simulated ablations were planned based on pre-procedural CT, before multi-probe placement was executed freehand. Multi-probe placement was then performed on the same 5-cm mass using the ablation planning software and robotic assistance. Post-procedural CTs were analysed to determine the percentage of untreated residual target. Results Mean needle tip-to-target errors were reduced with use of the IR assistance platform (both P < 0.0001). Reduced percentage residual tumour was observed with treatment planning (P = 0.02). Conclusion Improved needle accuracy and optimised probe geometry are observed during simulated CT-guided biopsy and percutaneous ablation with use of a robotic IR assistance platform. This technology may be useful for clinical CT-guided biopsy and RFA, when accuracy may have an impact on outcome. PMID:24220755

  8. Urine BLCA-4 exerts potential role in detecting patients with bladder cancers: a pooled analysis of individual studies

    PubMed Central

    Cai, Qiliang; Wu, Yudong; Guo, Zhanjun; Gong, Rui; Tang, Yang; Yang, Kuo; Li, Xiaodong; Guo, Xuemei; Niu, Yuanjie; Zhao, Yan

    2015-01-01

    Epidemiological studies have explored the diagnostic effect of urine BLCA-4 in bladder cancer. However, the results remain controversial. Therefore, we conducted this pooled analyses to determine the overall accuracy of urine BLCA-4 in bladder cancer. A comprehensive electronic and hand search was conducted for related literatures though several databases. QUADAS-2 was used to assess the quality of each included studies. Diagnostic parameters were calculated using Meta-Disc (version 1.4) and Stata (version 12.0) software. Nine published articles with 1,119 subjects were included. The summary estimates were: sensitivity 0.93 (95% confidence interval [CI] = 0.90-0.95), specificity 0.97 (95% CI, 0.95-0.98), positive likelihood ratio 48.16 (95% CI, 11.77-197.01), negative likelihood ratio 0.08 (95% CI, 0.06-0.11), diagnostic odds ratio 534.03 (95% CI, 150.15-1899.31), and the AUC was 0.9607. In conclusion, urine BLCA-4 is a promising marker in diagnosing bladder cancer. PMID:26462026

  9. Refining Ovarian Cancer Test accuracy Scores (ROCkeTS): protocol for a prospective longitudinal test accuracy study to validate new risk scores in women with symptoms of suspected ovarian cancer

    PubMed Central

    Sundar, Sudha; Rick, Caroline; Dowling, Francis; Au, Pui; Rai, Nirmala; Champaneria, Rita; Stobart, Hilary; Neal, Richard; Davenport, Clare; Mallett, Susan; Sutton, Andrew; Kehoe, Sean; Timmerman, Dirk; Bourne, Tom; Van Calster, Ben; Gentry-Maharaj, Aleksandra; Deeks, Jon

    2016-01-01

    Introduction Ovarian cancer (OC) is associated with non-specific symptoms such as bloating, making accurate diagnosis challenging: only 1 in 3 women with OC presents through primary care referral. National Institute for Health and Care Excellence guidelines recommends sequential testing with CA125 and routine ultrasound in primary care. However, these diagnostic tests have limited sensitivity or specificity. Improving accurate triage in women with vague symptoms is likely to improve mortality by streamlining referral and care pathways. The Refining Ovarian Cancer Test Accuracy Scores (ROCkeTS; HTA 13/13/01) project will derive and validate new tests/risk prediction models that estimate the probability of having OC in women with symptoms. This protocol refers to the prospective study only (phase III). Methods and analysis ROCkeTS comprises four parallel phases. The full ROCkeTS protocol can be found at http://www.birmingham.ac.uk/ROCKETS. Phase III is a prospective test accuracy study. The study will recruit 2450 patients from 15 UK sites. Recruited patients complete symptom and anxiety questionnaires, donate a serum sample and undergo ultrasound scored as per International Ovarian Tumour Analysis (IOTA) criteria. Recruitment is at rapid access clinics, emergency departments and elective clinics. Models to be evaluated include those based on ultrasound derived by the IOTA group and novel models derived from analysis of existing data sets. Estimates of sensitivity, specificity, c-statistic (area under receiver operating curve), positive predictive value and negative predictive value of diagnostic tests are evaluated and a calibration plot for models will be presented. ROCkeTS has received ethical approval from the NHS West Midlands REC (14/WM/1241) and is registered on the controlled trials website (ISRCTN17160843) and the National Institute of Health Research Cancer and Reproductive Health portfolios. PMID:27507231

  10. Test Expectancy Affects Metacomprehension Accuracy

    ERIC Educational Resources Information Center

    Thiede, Keith W.; Wiley, Jennifer; Griffin, Thomas D.

    2011-01-01

    Background: Theory suggests that the accuracy of metacognitive monitoring is affected by the cues used to judge learning. Researchers have improved monitoring accuracy by directing attention to more appropriate cues; however, this is the first study to more directly point students to more appropriate cues using instructions regarding tests and…

  11. Applying measures of discriminatory accuracy to revisit traditional risk factors for being small for gestational age in Sweden: a national cross-sectional study

    PubMed Central

    Juárez, Sol Pía; Wagner, Phillip; Merlo, Juan

    2014-01-01

    Objectives Small for gestational age (SGA) is considered as an indicator of intrauterine growth restriction, and multiple maternal and newborn characteristics have been identified as risk factors for SGA. This knowledge is mainly based on measures of average association (ie, OR) that quantify differences in average risk between exposed and unexposed groups. Nevertheless, average associations do not assess the discriminatory accuracy of the risk factors (ie, its ability to discriminate the babies who will develop SGA from those that will not). Therefore, applying measures of discriminatory accuracy rather than measures of association only, our study revisits known risk factors of SGA and discusses their role from a public health perspective. Design Cross-sectional study. We measured maternal (ie, smoking, hypertension, age, marital status, education) and delivery (ie, sex, gestational age, birth order) characteristics and performed logistic regression models to estimate both ORs and measures of discriminatory accuracy, like the area under the receiver operating characteristic curve (AU-ROC) and the net reclassification improvement. Setting Data were obtained from the Swedish Medical Birth Registry. Participants Our sample included 731 989 babies born during 1987–1993. Results We replicated the expected associations. For instance, smoking (OR=2.57), having had a previous SGA baby (OR=5.48) and hypertension (OR=4.02) were strongly associated with SGA. However, they show a very small discriminatory accuracy (AU-ROC≈0.5). The discriminatory accuracy increased, but remained unsatisfactorily low (AU-ROC=0.6), when including all variables studied in the same model. Conclusions Traditional risk factors for SGA alone or in combination have a low accuracy for discriminating babies with SGA from those without SGA. A proper understanding of these findings is of fundamental relevance to address future research and to design policymaking recommendations in a more informed

  12. Sampling strategies for improving tree accuracy and phylogenetic analyses: a case study in ciliate protists, with notes on the genus Paramecium.

    PubMed

    Yi, Zhenzhen; Strüder-Kypke, Michaela; Hu, Xiaozhong; Lin, Xiaofeng; Song, Weibo

    2014-02-01

    In order to assess how dataset-selection for multi-gene analyses affects the accuracy of inferred phylogenetic trees in ciliates, we chose five genes and the genus Paramecium, one of the most widely used model protist genera, and compared tree topologies of the single- and multi-gene analyses. Our empirical study shows that: (1) Using multiple genes improves phylogenetic accuracy, even when their one-gene topologies are in conflict with each other. (2) The impact of missing data on phylogenetic accuracy is ambiguous: resolution power and topological similarity, but not number of represented taxa, are the most important criteria of a dataset for inclusion in concatenated analyses. (3) As an example, we tested the three classification models of the genus Paramecium with a multi-gene based approach, and only the monophyly of the subgenus Paramecium is supported.

  13. Study on the maximum accuracy of the pseudopotential density functional method with localized atomic orbitals versus plane-wave basis sets.

    PubMed

    Gusso, Michele

    2008-01-28

    A detailed study on the accuracy attainable with numerical atomic orbitals in the context of pseudopotential first-principles density functional theory is presented. Dimers of first- and second-row elements are analyzed: bond lengths, atomization energies, and Kohn-Sham eigenvalue spectra obtained with localized orbitals and with plane-wave basis sets are compared. For each dimer, the cutoff radius, the shape, and the number of the atomic basis orbitals are varied in order to maximize the accuracy of the calculations. Optimized atomic orbitals are obtained following two routes: (i) maximization of the projection of plane wave results into atomic orbital basis sets and (ii) minimization of the total energy with respect to a set of primitive atomic orbitals as implemented in the OPENMX software package. It is found that by optimizing the numerical basis, chemical accuracy can be obtained even with a small set of orbitals.

  14. Phase segmentation of X-ray computer tomography rock images using machine learning techniques: an accuracy and performance study

    NASA Astrophysics Data System (ADS)

    Chauhan, Swarup; Rühaak, Wolfram; Anbergen, Hauke; Kabdenov, Alen; Freise, Marcus; Wille, Thorsten; Sass, Ingo

    2016-07-01

    Performance and accuracy of machine learning techniques to segment rock grains, matrix and pore voxels from a 3-D volume of X-ray tomographic (XCT) grayscale rock images was evaluated. The segmentation and classification capability of unsupervised (k-means, fuzzy c-means, self-organized maps), supervised (artificial neural networks, least-squares support vector machines) and ensemble classifiers (bragging and boosting) were tested using XCT images of andesite volcanic rock, Berea sandstone, Rotliegend sandstone and a synthetic sample. The averaged porosity obtained for andesite (15.8 ± 2.5 %), Berea sandstone (16.3 ± 2.6 %), Rotliegend sandstone (13.4 ± 7.4 %) and the synthetic sample (48.3 ± 13.3 %) is in very good agreement with the respective laboratory measurement data and varies by a factor of 0.2. The k-means algorithm is the fastest of all machine learning algorithms, whereas a least-squares support vector machine is the most computationally expensive. Metrics entropy, purity, mean square root error, receiver operational characteristic curve and 10 K-fold cross-validation were used to determine the accuracy of unsupervised, supervised and ensemble classifier techniques. In general, the accuracy was found to be largely affected by the feature vector selection scheme. As it is always a trade-off between performance and accuracy, it is difficult to isolate one particular machine learning algorithm which is best suited for the complex phase segmentation problem. Therefore, our investigation provides parameters that can help in selecting the appropriate machine learning techniques for phase segmentation.

  15. Immediate effects of lower cervical spine manipulation on handgrip strength and free-throw accuracy of asymptomatic basketball players: a pilot study

    PubMed Central

    Humphries, Kelley M.; Ward, John; Coats, Jesse; Nobert, Jeannique; Amonette, William; Dyess, Stephen

    2013-01-01

    Objective The purpose of this pilot study was to collect preliminary information for a study to determine the immediate effects of a single unilateral chiropractic manipulation to the lower cervical spine on handgrip strength and free-throw accuracy in asymptomatic male recreational basketball players. Methods For this study, 24 asymptomatic male recreational right-handed basketball players (age = 26.3 ± 9.2 years, height = 1.81 ± 0.07 m, body mass = 82.6 ± 10.4 kg [mean ± SD]) underwent baseline dominant handgrip isometric strength and free-throw accuracy testing in an indoor basketball court. They were then equally randomized to receive either (1) diversified left lower cervical spine chiropractic manipulative therapy (CMT) at C5/C6 or (2) placebo CMT at C5/C6 using an Activator adjusting instrument on zero force setting. Participants then underwent posttesting of isometric handgrip strength and free-throw accuracy. A paired-samples t test was used to make within-group pre to post comparisons and between-group pre to post comparisons. Results No statistically significant difference was shown between either of the 2 basketball performance variables measured in either group. Isometric handgrip strength marginally improved by 0.7 kg (mean) in the CMT group (P = .710). Free-throw accuracy increased by 13.2% in the CMT group (P = .058). The placebo CMT group performed the same or more poorly during their second test session. Conclusions The results of this preliminary study showed that a single lower cervical spine manipulation did not significantly impact basketball performance for this group of healthy asymptomatic participants. A slight increase in free-throw percentage was seen, which deserves further investigation. This pilot study demonstrates that a larger study to evaluate if CMT affects handgrip strength and free-throw accuracy is feasible. PMID:24396315

  16. Prostate intrafraction motion evaluation using kV fluoroscopy during treatment delivery: A feasibility and accuracy study

    SciTech Connect

    Adamson, Justus; Wu Qiuwen

    2008-05-15

    Margin reduction for prostate radiotherapy is limited by uncertainty in prostate localization during treatment. We investigated the feasibility and accuracy of measuring prostate intrafraction motion using kV fluoroscopy performed simultaneously with radiotherapy. Three gold coils used for target localization were implanted into the patient's prostate gland before undergoing hypofractionated online image-guided step-and-shoot intensity modulated radiation therapy (IMRT) on an Elekta Synergy linear accelerator. At each fraction, the patient was aligned using a cone-beam computed tomography (CBCT), after which the IMRT treatment delivery and fluoroscopy were performed simultaneously. In addition, a post-treatment CBCT was acquired with the patient still on the table. To measure the intrafraction motion, we developed an algorithm to register the fluoroscopy images to a reference image derived from the post-treatment CBCT, and we estimated coil motion in three-dimensional (3D) space by combining information from registrations at different gantry angles. We also detected the MV beam turning on and off using MV scatter incident in the same fluoroscopy images, and used this information to synchronize our intrafraction evaluation with the treatment delivery. In addition, we assessed the following: the method to synchronize with treatment delivery, the dose from kV imaging, the accuracy of the localization, and the error propagated into the 3D localization from motion between fluoroscopy acquisitions. With 0.16 mAs/frame and a bowtie filter implemented, the coils could be localized with the gantry at both 0 deg. and 270 deg. with the MV beam off, and at 270 deg. with the MV beam on when multiple fluoroscopy frames were averaged. The localization in two-dimensions for phantom and patient measurements was performed with submillimeter accuracy. After backprojection into 3D the patient localization error was (-0.04{+-}0.30) mm, (0.09{+-}0.36) mm, and (0.03{+-}0.68) mm in the

  17. Prostate intrafraction motion evaluation using kV fluoroscopy during treatment delivery: A feasibility and accuracy study

    PubMed Central

    Adamson, Justus; Wu, Qiuwen

    2008-01-01

    Margin reduction for prostate radiotherapy is limited by uncertainty in prostate localization during treatment. We investigated the feasibility and accuracy of measuring prostate intrafraction motion using kV fluoroscopy performed simultaneously with radiotherapy. Three gold coils used for target localization were implanted into the patient’s prostate gland before undergoing hypofractionated online image-guided step-and-shoot intensity modulated radiation therapy (IMRT) on an Elekta Synergy linear accelerator. At each fraction, the patient was aligned using a cone-beam computed tomography (CBCT), after which the IMRT treatment delivery and fluoroscopy were performed simultaneously. In addition, a post-treatment CBCT was acquired with the patient still on the table. To measure the intrafraction motion, we developed an algorithm to register the fluoroscopy images to a reference image derived from the post-treatment CBCT, and we estimated coil motion in three-dimensional (3D) space by combining information from registrations at different gantry angles. We also detected the MV beam turning on and off using MV scatter incident in the same fluoroscopy images, and used this information to synchronize our intrafraction evaluation with the treatment delivery. In addition, we assessed the following: the method to synchronize with treatment delivery, the dose from kV imaging, the accuracy of the localization, and the error propagated into the 3D localization from motion between fluoroscopy acquisitions. With 0.16 mAs∕frame and a bowtie filter implemented, the coils could be localized with the gantry at both 0° and 270° with the MV beam off, and at 270° with the MV beam on when multiple fluoroscopy frames were averaged. The localization in two-dimensions for phantom and patient measurements was performed with submillimeter accuracy. After backprojection into 3D the patient localization error was (−0.04±0.30) mm, (0.09±0.36) mm, and (0.03±0.68) mm in the right

  18. Accuracy of autofluorescence in diagnosing oral squamous cell carcinoma and oral potentially malignant disorders: a comparative study with aero-digestive lesions

    PubMed Central

    Luo, Xiaobo; Xu, Hao; He, Mingjing; Han, Qi; Wang, Hui; Sun, Chongkui; Li, Jing; Jiang, Lu; Zhou, Yu; Dan, Hongxia; Feng, Xiaodong; Zeng, Xin; Chen, Qianming

    2016-01-01

    Presently, various studies had investigated the accuracy of autofluorescence in diagnosing oral squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD) with diverse conclusions. This study aimed to assess its accuracy for OSCC and OPMD and to investigate its applicability in general dental practice. After a comprehensive literature search, a meta-analysis was conducted to calculate the pooled diagnostic indexes of autofluorescence for premalignant lesions (PML) and malignant lesions (ML) of the oral cavity, lung, esophagus, stomach and colorectum and to compute indexes regarding the detection of OSCC aided by algorithms. Besides, a u test was performed. Twenty-four studies detecting OSCC and OPMD in 2761 lesions were included. This demonstrated that the overall accuracy of autofluorescence for OSCC and OPMD was superior to PML and ML of the lung, esophagus and stomach, slightly inferior to the colorectum. Additionally, the sensitivity and specificity for OSCC and OPMD were 0.89 and 0.8, respectively. Furthermore, the specificity could be remarkably improved by additional algorithms. With relatively high accuracy, autofluorescence could be potentially applied as an adjunct for early diagnosis of OSCC and OPMD. Moreover, approaches such as algorithms could enhance its specificity to ensure its efficacy in primary care. PMID:27416981

  19. Accuracy of surface registration compared to conventional volumetric registration in patient positioning for head-and-neck radiotherapy: A simulation study using patient data

    SciTech Connect

    Kim, Youngjun; Li, Ruijiang; Na, Yong Hum; Xing, Lei; Lee, Rena

    2014-12-15

    Purpose: 3D optical surface imaging has been applied to patient positioning in radiation therapy (RT). The optical patient positioning system is advantageous over conventional method using cone-beam computed tomography (CBCT) in that it is radiation free, frameless, and is capable of real-time monitoring. While the conventional radiographic method uses volumetric registration, the optical system uses surface matching for patient alignment. The relative accuracy of these two methods has not yet been sufficiently investigated. This study aims to investigate the theoretical accuracy of the surface registration based on a simulation study using patient data. Methods: This study compares the relative accuracy of surface and volumetric registration in head-and-neck RT. The authors examined 26 patient data sets, each consisting of planning CT data acquired before treatment and patient setup CBCT data acquired at the time of treatment. As input data of surface registration, patient’s skin surfaces were created by contouring patient skin from planning CT and treatment CBCT. Surface registration was performed using the iterative closest points algorithm by point–plane closest, which minimizes the normal distance between source points and target surfaces. Six degrees of freedom (three translations and three rotations) were used in both surface and volumetric registrations and the results were compared. The accuracy of each method was estimated by digital phantom tests. Results: Based on the results of 26 patients, the authors found that the average and maximum root-mean-square translation deviation between the surface and volumetric registrations were 2.7 and 5.2 mm, respectively. The residual error of the surface registration was calculated to have an average of 0.9 mm and a maximum of 1.7 mm. Conclusions: Surface registration may lead to results different from those of the conventional volumetric registration. Only limited accuracy can be achieved for patient

  20. A comparative study of the quantitative accuracy of three-dimensional reconstructions of spinal cord from serial histological sections.

    PubMed

    Duerstock, B S; Bajaj, C L; Borgens, R B

    2003-05-01

    We evaluated the accuracy of estimating the volume of biological soft tissues from their three-dimensional (3D) computer wireframe models, reconstructed from histological data sets obtained from guinea-pig spinal cords. We compared quantification from two methods of three-dimensional surface reconstruction to standard quantitative techniques, Cavalieri method employing planimetry and point counting and Geometric Best-Fitting. This involved measuring a group of spinal cord segments and test objects to evaluate the accuracy of our novel quantification approaches. Once a quantitative methodology was standardized there was no statistical difference in volume measurement of spinal segments between quantification methods. We found that our 3D surface reconstructions' ability to model precisely actual soft tissues provided an accurate volume quantification of complex anatomical structures as standard approaches of Cavalieri estimation and Geometric Best-Fitting. Additionally, 3D reconstruction quantitatively interrogates and three-dimensionally images spinal cord segments and obscured internal pathological features with approximately the same effort required for standard quantification alone.

  1. Accuracy of the Chinese lunar calendar method to predict a baby's sex: a population-based study.

    PubMed

    Villamor, Eduardo; Dekker, Louise; Svensson, Tobias; Cnattingius, Sven

    2010-07-01

    We estimated the accuracy of a non-invasive, inexpensive method (the Chinese lunar calendar, CLC) to predict the sex of a baby from around the time of conception, using 2,840,755 singleton births occurring in Sweden between 1973 and 2006. Maternal lunar age and month of conception were estimated, and used to predict each baby's sex, according to a published algorithm. Kappa statistics were estimated for the actual vs. the CLC-predicted sex of the baby. Overall kappa was 0.0002 [95% CI -0.0009, 0.0014]. Accuracy was not modified by year of conception, maternal age, level of education, body mass index or parity. In a validation subset of 1000 births in which we used a website-customised algorithm to estimate lunar dates, kappa was -0.02 [95% CI -0.08, 0.04]. Simulating the misuse of the method by failing to convert Gregorian dates into lunar did not change the results. We conclude that the CLC method is no better at predicting the sex of a baby than tossing a coin and advise against painting the nursery based on this method's result. PMID:20618730

  2. Accuracy of the Chinese lunar calendar method to predict a baby's sex: a population-based study.

    PubMed

    Villamor, Eduardo; Dekker, Louise; Svensson, Tobias; Cnattingius, Sven

    2010-07-01

    We estimated the accuracy of a non-invasive, inexpensive method (the Chinese lunar calendar, CLC) to predict the sex of a baby from around the time of conception, using 2,840,755 singleton births occurring in Sweden between 1973 and 2006. Maternal lunar age and month of conception were estimated, and used to predict each baby's sex, according to a published algorithm. Kappa statistics were estimated for the actual vs. the CLC-predicted sex of the baby. Overall kappa was 0.0002 [95% CI -0.0009, 0.0014]. Accuracy was not modified by year of conception, maternal age, level of education, body mass index or parity. In a validation subset of 1000 births in which we used a website-customised algorithm to estimate lunar dates, kappa was -0.02 [95% CI -0.08, 0.04]. Simulating the misuse of the method by failing to convert Gregorian dates into lunar did not change the results. We conclude that the CLC method is no better at predicting the sex of a baby than tossing a coin and advise against painting the nursery based on this method's result.

  3. A mixed effect model for bivariate meta-analysis of diagnostic test accuracy studies using a copula representation of the random effects distribution.

    PubMed

    Nikoloulopoulos, Aristidis K

    2015-12-20

    Diagnostic test accuracy studies typically report the number of true positives, false positives, true negatives and false negatives. There usually exists a negative association between the number of true positives and true negatives, because studies that adopt less stringent criterion for declaring a test positive invoke higher sensitivities and lower specificities. A generalized linear mixed model (GLMM) is currently recommended to synthesize diagnostic test accuracy studies. We propose a copula mixed model for bivariate meta-analysis of diagnostic test accuracy studies. Our general model includes the GLMM as a special case and can also operate on the original scale of sensitivity and specificity. Summary receiver operating characteristic curves are deduced for the proposed model through quantile regression techniques and different characterizations of the bivariate random effects distribution. Our general methodology is demonstrated with an extensive simulation study and illustrated by re-analysing the data of two published meta-analyses. Our study suggests that there can be an improvement on GLMM in fit to data and makes the argument for moving to copula random effects models. Our modelling framework is implemented in the package CopulaREMADA within the open source statistical environment R.

  4. Accuracy and Uncertainty of Asymmetric Magnetization Transfer Ratio Quantification for Amide Proton Transfer (APT) Imaging at 3T: A Monte Carlo Study

    PubMed Central

    Yuan, Jing; Zhang, Qinwei; Wang, Yi-Xiang; Wei, Juan; Zhou, Jinyuan

    2014-01-01

    Amide proton transfer (APT) imaging offers a novel and powerful MRI contrast mechanism for quantitative molecular imaging based on the principle of chemical exchange saturation transfer (CEST). Asymmetric magnetization transfer ratio (MTRasym) quantification is crucial for Z-spectrum analysis of APT imaging, but is still challenging, particularly at clinical field strength. This paper studies the accuracy and uncertainty in the quantification of MTRasym for APT imaging at 3T, by using high-order polynomial fitting of Z-spectrum through Monte Carlo simulation. Results show that polynomial fitting is a biased estimator that consistently underestimates MTRasym. For a fixed polynomial order, the accuracy of MTRasym is almost constant with regard to signal-to-noise ratio (SNR) while the uncertainty decreases exponentially with SNR. The higher order polynomial fitting increases both the accuracy and the uncertainty of MTRasym. For different APT signal intensity levels, the relative accuracy and the absolute uncertainty keep constant for a fixed polynomial order. These results indicate the limitations and pitfalls of polynomial fitting for MTRasym quantification so better quantification technique for MTRasym estimation is warranted. PMID:24110892

  5. Accuracy and uncertainty of asymmetric magnetization transfer ratio quantification for amide proton transfer (APT) imaging at 3T: a Monte Carlo study.

    PubMed

    Yuan, Jing; Zhang, Qinwei; Wang, Yi-Xiang; Wei, Juan; Zhou, Jinyuan

    2013-01-01

    Amide proton transfer (APT) imaging offers a novel and powerful MRI contrast mechanism for quantitative molecular imaging based on the principle of chemical exchange saturation transfer (CEST). Asymmetric magnetization transfer ratio (MTR(asym)) quantification is crucial for Z-spectrum analysis of APT imaging, but is still challenging, particularly at clinical field strength. This paper studies the accuracy and uncertainty in the quantification of MTR(asym) for APT imaging at 3T, by using high-order polynomial fitting of Z-spectrum through Monte Carlo simulation. Results show that polynomial fitting is a biased estimator that consistently underestimates MTR(asym). For a fixed polynomial order, the accuracy of MTR(asym) is almost constant with regard to signal-to-noise ratio (SNR) while the uncertainty decreases exponentially with SNR. The higher order polynomial fitting increases both the accuracy and the uncertainty of MTR(asym). For different APT signal intensity levels, the relative accuracy and the absolute uncertainty keep constant for a fixed polynomial order. These results indicate the limitations and pitfalls of polynomial fitting for MTR(asym) quantification so better quantification technique for MTR(asym) estimation is warranted.

  6. Recommended reporting standards for test accuracy studies of infectious diseases of finfish, amphibians, molluscs and crustaceans: the STRADAS-aquatic checklist.

    PubMed

    Gardner, Ian A; Whittington, Richard J; Caraguel, Charles G B; Hick, Paul; Moody, Nicholas J G; Corbeil, Serge; Garver, Kyle A; Warg, Janet V; Arzul, Isabelle; Purcell, Maureen K; Crane, Mark St J; Waltzek, Thomas B; Olesen, Niels J; Gallardo Lagno, Alicia

    2016-02-25

    Complete and transparent reporting of key elements of diagnostic accuracy studies for infectious diseases in cultured and wild aquatic animals benefits end-users of these tests, enabling the rational design of surveillance programs, the assessment of test results from clinical cases and comparisons of diagnostic test performance. Based on deficiencies in the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines identified in a prior finfish study (Gardner et al. 2014), we adapted the Standards for Reporting of Animal Diagnostic Accuracy Studies-paratuberculosis (STRADAS-paraTB) checklist of 25 reporting items to increase their relevance to finfish, amphibians, molluscs, and crustaceans and provided examples and explanations for each item. The checklist, known as STRADAS-aquatic, was developed and refined by an expert group of 14 transdisciplinary scientists with experience in test evaluation studies using field and experimental samples, in operation of reference laboratories for aquatic animal pathogens, and in development of international aquatic animal health policy. The main changes to the STRADAS-paraTB checklist were to nomenclature related to the species, the addition of guidelines for experimental challenge studies, and the designation of some items as relevant only to experimental studies and ante-mortem tests. We believe that adoption of these guidelines will improve reporting of primary studies of test accuracy for aquatic animal diseases and facilitate assessment of their fitness-for-purpose. Given the importance of diagnostic tests to underpin the Sanitary and Phytosanitary agreement of the World Trade Organization, the principles outlined in this paper should be applied to other World Organisation for Animal Health (OIE)-relevant species.

  7. Recommended reporting standards for test accuracy studies of infectious diseases of finfish, amphibians, molluscs and crustaceans: the STRADAS-aquatic checklist.

    PubMed

    Gardner, Ian A; Whittington, Richard J; Caraguel, Charles G B; Hick, Paul; Moody, Nicholas J G; Corbeil, Serge; Garver, Kyle A; Warg, Janet V; Arzul, Isabelle; Purcell, Maureen K; Crane, Mark St J; Waltzek, Thomas B; Olesen, Niels J; Gallardo Lagno, Alicia

    2016-02-25

    Complete and transparent reporting of key elements of diagnostic accuracy studies for infectious diseases in cultured and wild aquatic animals benefits end-users of these tests, enabling the rational design of surveillance programs, the assessment of test results from clinical cases and comparisons of diagnostic test performance. Based on deficiencies in the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines identified in a prior finfish study (Gardner et al. 2014), we adapted the Standards for Reporting of Animal Diagnostic Accuracy Studies-paratuberculosis (STRADAS-paraTB) checklist of 25 reporting items to increase their relevance to finfish, amphibians, molluscs, and crustaceans and provided examples and explanations for each item. The checklist, known as STRADAS-aquatic, was developed and refined by an expert group of 14 transdisciplinary scientists with experience in test evaluation studies using field and experimental samples, in operation of reference laboratories for aquatic animal pathogens, and in development of international aquatic animal health policy. The main changes to the STRADAS-paraTB checklist were to nomenclature related to the species, the addition of guidelines for experimental challenge studies, and the designation of some items as relevant only to experimental studies and ante-mortem tests. We believe that adoption of these guidelines will improve reporting of primary studies of test accuracy for aquatic animal diseases and facilitate assessment of their fitness-for-purpose. Given the importance of diagnostic tests to underpin the Sanitary and Phytosanitary agreement of the World Trade Organization, the principles outlined in this paper should be applied to other World Organisation for Animal Health (OIE)-relevant species. PMID:26912041

  8. Recommended reporting standards for test accuracy studies of infectious diseases of finfish, amphibians, molluscs and crustaceans: the STRADAS-aquatic checklist

    USGS Publications Warehouse

    Gardner, Ian A; Whittington, Richard J; Caraguel, Charles G B; Hick, Paul; Moody, Nicholas J G; Corbeil, Serge; Garver, Kyle A.; Warg, Janet V; Arzul, Isabelle; Purcell, Maureen; St. J. Crane, Mark; Waltzek, Thomas B.; Olesen, Niels J; Lagno, Alicia Gallardo

    2016-01-01

    Complete and transparent reporting of key elements of diagnostic accuracy studies for infectious diseases in cultured and wild aquatic animals benefits end-users of these tests, enabling the rational design of surveillance programs, the assessment of test results from clinical cases and comparisons of diagnostic test performance. Based on deficiencies in the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines identified in a prior finfish study (Gardner et al. 2014), we adapted the Standards for Reporting of Animal Diagnostic Accuracy Studies—paratuberculosis (STRADAS-paraTB) checklist of 25 reporting items to increase their relevance to finfish, amphibians, molluscs, and crustaceans and provided examples and explanations for each item. The checklist, known as STRADAS-aquatic, was developed and refined by an expert group of 14 transdisciplinary scientists with experience in test evaluation studies using field and experimental samples, in operation of reference laboratories for aquatic animal pathogens, and in development of international aquatic animal health policy. The main changes to the STRADAS-paraTB checklist were to nomenclature related to the species, the addition of guidelines for experimental challenge studies, and the designation of some items as relevant only to experimental studies and ante-mortem tests. We believe that adoption of these guidelines will improve reporting of primary studies of test accuracy for aquatic animal diseases and facilitate assessment of their fitness-for-purpose. Given the importance of diagnostic tests to underpin the Sanitary and Phytosanitary agreement of the World Trade Organization, the principles outlined in this paper should be applied to other World Organisation for Animal Health (OIE)-relevant species.

  9. Relative Accuracy Evaluation

    PubMed Central

    Zhang, Yan; Wang, Hongzhi; Yang, Zhongsheng; Li, Jianzhong

    2014-01-01

    The quality of data plays an important role in business analysis and decision making, and data accuracy is an important aspect in data quality. Thus one necessary task for data quality management is to evaluate the accuracy of the data. And in order to solve the problem that the accuracy of the whole data set is low while a useful part may be high, it is also necessary to evaluate the accuracy of the query results, called relative accuracy. However, as far as we know, neither measure nor effective methods for the accuracy evaluation methods are proposed. Motivated by this, for relative accuracy evaluation, we propose a systematic method. We design a relative accuracy evaluation framework for relational databases based on a new metric to measure the accuracy using statistics. We apply the methods to evaluate the precision and recall of basic queries, which show the result's relative accuracy. We also propose the method to handle data update and to improve accuracy evaluation using functional dependencies. Extensive experimental results show the effectiveness and efficiency of our proposed framework and algorithms. PMID:25133752

  10. Expected accuracy of tilt measurements on a novel hexapod-based digital zenith camera system: a Monte-Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Hirt, Christian; Papp, Gábor; Pál, András; Benedek, Judit; Szũcs, Eszter

    2014-08-01

    Digital zenith camera systems (DZCS) are dedicated astronomical-geodetic measurement systems for the observation of the direction of the plumb line. A DZCS key component is a pair of tilt meters for the determination of the instrumental tilt with respect to the plumb line. Highest accuracy (i.e., 0.1 arc-seconds or better) is achieved in practice through observation with precision tilt meters in opposite faces (180° instrumental rotation), and application of rigorous tilt reduction models. A novel concept proposes the development of a hexapod (Stewart platform)-based DZCS. However, hexapod-based total rotations are limited to about 30°-60° in azimuth (equivalent to ±15° to ±30° yaw rotation), which raises the question of the impact of the rotation angle between the two faces on the accuracy of the tilt measurement. The goal of the present study is the investigation of the expected accuracy of tilt measurements to be carried out on future hexapod-based DZCS, with special focus placed on the role of the limited rotation angle. A Monte-Carlo simulation study is carried out in order to derive accuracy estimates for the tilt determination as a function of several input parameters, and the results are validated against analytical error propagation. As the main result of the study, limitation of the instrumental rotation to 60° (30°) deteriorates the tilt accuracy by a factor of about 2 (4) compared to a 180° rotation between the faces. Nonetheless, a tilt accuracy at the 0.1 arc-second level is expected when the rotation is at least 45°, and 0.05 arc-second (about 0.25 microradian) accurate tilt meters are deployed. As such, a hexapod-based DZCS can be expected to allow sufficiently accurate determination of the instrumental tilt. This provides supporting evidence for the feasibility of such a novel instrumentation. The outcomes of our study are not only relevant to the field of DZCS, but also to all other types of instruments where the instrumental tilt

  11. SU-E-J-147: Monte Carlo Study of the Precision and Accuracy of Proton CT Reconstructed Relative Stopping Power Maps

    SciTech Connect

    Dedes, G; Asano, Y; Parodi, K; Arbor, N; Dauvergne, D; Testa, E; Letang, J; Rit, S

    2015-06-15

    Purpose: The quantification of the intrinsic performances of proton computed tomography (pCT) as a modality for treatment planning in proton therapy. The performance of an ideal pCT scanner is studied as a function of various parameters. Methods: Using GATE/Geant4, we simulated an ideal pCT scanner and scans of several cylindrical phantoms with various tissue equivalent inserts of different sizes. Insert materials were selected in order to be of clinical relevance. Tomographic images were reconstructed using a filtered backprojection algorithm taking into account the scattering of protons into the phantom. To quantify the performance of the ideal pCT scanner, we study the precision and the accuracy with respect to the theoretical relative stopping power ratios (RSP) values for different beam energies, imaging doses, insert sizes and detector positions. The planning range uncertainty resulting from the reconstructed RSP is also assessed by comparison with the range of the protons in the analytically simulated phantoms. Results: The results indicate that pCT can intrinsically achieve RSP resolution below 1%, for most examined tissues at beam energies below 300 MeV and for imaging doses around 1 mGy. RSP maps accuracy of less than 0.5 % is observed for most tissue types within the studied dose range (0.2–1.5 mGy). Finally, the uncertainty in the proton range due to the accuracy of the reconstructed RSP map is well below 1%. Conclusion: This work explores the intrinsic performance of pCT as an imaging modality for proton treatment planning. The obtained results show that under ideal conditions, 3D RSP maps can be reconstructed with an accuracy better than 1%. Hence, pCT is a promising candidate for reducing the range uncertainties introduced by the use of X-ray CT alongside with a semiempirical calibration to RSP.Supported by the DFG Cluster of Excellence Munich-Centre for Advanced Photonics (MAP)

  12. Hermite finite elements for high accuracy electromagnetic field calculations: A case study of homogeneous and inhomogeneous waveguides

    NASA Astrophysics Data System (ADS)

    Boucher, C. R.; Li, Zehao; Ahheng, C. I.; Albrecht, J. D.; Ram-Mohan, L. R.

    2016-04-01

    Maxwell's vector field equations and their numerical solution represent significant challenges for physical domains with complex geometries. There are several limitations in the presently prevalent approaches to the calculation of field distributions in physical domains, in particular, with the vector finite elements. In order to quantify and resolve issues, we consider the modeling of the field equations for the prototypical examples of waveguides. We employ the finite element method with a new set of Hermite interpolation polynomials derived recently by us using group theoretic considerations. We show that (i) the approach presented here yields better accuracy by several orders of magnitude, with a smoother representation of fields than the vector finite elements for waveguide calculations. (ii) This method does not generate any spurious solutions that plague Lagrange finite elements, even though the C1 -continuous Hermite polynomials are also scalar in nature. (iii) We present solutions for propagating modes in inhomogeneous waveguides satisfying dispersion relations that can be derived directly, and investigate their behavior as the ratio of dielectric constants is varied both theoretically and numerically. Additional comparisons and advantages of the proposed method are detailed in this article. The Hermite interpolation polynomials are shown to provide a robust, accurate, and efficient means of solving Maxwell's equations in a variety of media, potentially offering a computationally inexpensive means of designing devices for optoelectronics and plasmonics of increasing complexity.

  13. Studying the Effect of Adaptive Momentum in Improving the Accuracy of Gradient Descent Back Propagation Algorithm on Classification Problems

    NASA Astrophysics Data System (ADS)

    Rehman, Muhammad Zubair; Nawi, Nazri Mohd.

    Despite being widely used in the practical problems around the world, Gradient Descent Back-propagation algorithm comes with problems like slow convergence and convergence to local minima. Previous researchers have suggested certain modifications to improve the convergence in gradient Descent Back-propagation algorithm such as careful selection of input weights and biases, learning rate, momentum, network topology, activation function and value for 'gain' in the activation function. This research proposed an algorithm for improving the working performance of back-propagation algorithm which is 'Gradient Descent with Adaptive Momentum (GDAM)' by keeping the gain value fixed during all network trials. The performance of GDAM is compared with 'Gradient Descent with fixed Momentum (GDM)' and 'Gradient Descent Method with Adaptive Gain (GDM-AG)'. The learning rate is fixed to 0.4 and maximum epochs are set to 3000 while sigmoid activation function is used for the experimentation. The results show that GDAM is a better approach than previous methods with an accuracy ratio of 1.0 for classification problems like Wine Quality, Mushroom and Thyroid disease.

  14. Real-Word and Nonword Repetition in Italian-Speaking Children with Specific Language Impairment: A Study of Diagnostic Accuracy

    PubMed Central

    Dispaldro, Marco; Leonard, Laurence B.; Deevy, Patricia

    2013-01-01

    Purpose: Using two different scoring methods, we examined the diagnostic accuracy of both real-word and nonword repetition in identifying Italian-speaking children with and without specific language impairment (SLI). Method: A total of 34 children aged 3;11 to 5;8 participated – 17 children with SLI and 17 typically developing children matched for age (TD-A children). Children completed real-word and nonword repetition tasks. The capacity of real-word and nonword repetition tasks to discriminate children with SLI from TD-A was examined through binary logistic regression and response operating characteristics curves. Results: Both real-word and nonword repetition showed good (or excellent) sensitivity and specificity in distinguishing children with SLI from their typically developing peers. Conclusions: Nonword repetition appears to be a useful diagnostic indicator for Italian, as in other languages. In addition, real-word repetition also holds promise. The contributions of each type of measure are discussed. PMID:22761319

  15. Cognitive Abilities Underlying Reading Accuracy, Fluency and Spelling Acquisition in Korean Hangul Learners from Grades 1 to 4: A Cross-Sectional Study.

    PubMed

    Park, Hyun-Rin; Uno, Akira

    2015-08-01

    The purpose of this cross-sectional study was to examine the cognitive abilities that predict reading and spelling performance in Korean children in Grades 1 to 4, depending on expertise and reading experience. As a result, visual cognition, phonological awareness, naming speed and receptive vocabulary significantly predicted reading accuracy in children in Grades 1 and 2, whereas visual cognition, phonological awareness and rapid naming speed did not predict reading accuracy in children in higher grades. For reading, fluency, phonological awareness, rapid naming speed and receptive vocabulary were crucial abilities in children in Grades 1 to 3, whereas phonological awareness was not a significant predictor in children in Grade 4. In spelling, reading ability and receptive vocabulary were the most important abilities for accurate Hangul spelling. The results suggested that the degree of cognitive abilities required for reading and spelling changed depending on expertise and reading experience.

  16. Systematic Review and Meta-Analysis of Studies Evaluating Diagnostic Test Accuracy: A Practical Review for Clinical Researchers-Part I. General Guidance and Tips

    PubMed Central

    Kim, Kyung Won; Lee, Juneyoung; Choi, Sang Hyun; Huh, Jimi

    2015-01-01

    In the field of diagnostic test accuracy (DTA), the use of systematic review and meta-analyses is steadily increasing. By means of objective evaluation of all available primary studies, these two processes generate an evidence-based systematic summary regarding a specific research topic. The methodology for systematic review and meta-analysis in DTA studies differs from that in therapeutic/interventional studies, and its content is still evolving. Here we review the overall process from a practical standpoint, which may serve as a reference for those who implement these methods. PMID:26576106

  17. Systematic Review and Meta-Analysis of Studies Evaluating Diagnostic Test Accuracy: A Practical Review for Clinical Researchers-Part I. General Guidance and Tips.

    PubMed

    Kim, Kyung Won; Lee, Juneyoung; Choi, Sang Hyun; Huh, Jimi; Park, Seong Ho

    2015-01-01

    In the field of diagnostic test accuracy (DTA), the use of systematic review and meta-analyses is steadily increasing. By means of objective evaluation of all available primary studies, these two processes generate an evidence-based systematic summary regarding a specific research topic. The methodology for systematic review and meta-analysis in DTA studies differs from that in therapeutic/interventional studies, and its content is still evolving. Here we review the overall process from a practical standpoint, which may serve as a reference for those who implement these methods. PMID:26576106

  18. Accuracy of self-reported intake of signature foods in a school meal intervention study: comparison between control and intervention period.

    PubMed

    Biltoft-Jensen, Anja; Damsgaard, Camilla Trab; Andersen, Rikke; Ygil, Karin Hess; Andersen, Elisabeth Wreford; Ege, Majken; Christensen, Tue; Sørensen, Louise Bergmann; Stark, Ken D; Tetens, Inge; Thorsen, Anne-Vibeke

    2015-08-28

    Bias in self-reported dietary intake is important when evaluating the effect of dietary interventions, particularly for intervention foods. However, few have investigated this in children, and none have investigated the reporting accuracy of fish intake in children using biomarkers. In a Danish school meal study, 8- to 11-year-old children (n 834) were served the New Nordic Diet (NND) for lunch. The present study examined the accuracy of self-reported intake of signature foods (berries, cabbage, root vegetables, legumes, herbs, potatoes, wild plants, mushrooms, nuts and fish) characterising the NND. Children, assisted by parents, self-reported their diet in a Web-based Dietary Assessment Software for Children during the intervention and control (packed lunch) periods. The reported fish intake by children was compared with their ranking according to fasting whole-blood EPA and DHA concentration and weight percentage using the Spearman correlations and cross-classification. Direct observation of school lunch intake (n 193) was used to score the accuracy of food-reporting as matches, intrusions, omissions and faults. The reporting of all lunch foods had higher percentage of matches compared with the reporting of signature foods in both periods, and the accuracy was higher during the control period compared with the intervention period. Both Spearman's rank correlations and linear mixed models demonstrated positive associations between EPA+DHA and reported fish intake. The direct observations showed that both reported and real intake of signature foods did increase during the intervention period. In conclusion, the self-reported data represented a true increase in the intake of signature foods and can be used to examine dietary intervention effects. PMID:26189886

  19. A validation study concerning the effects of interview content, retention interval, and grade on children’s recall accuracy for dietary intake and/or physical activity

    PubMed Central

    Baxter, Suzanne D.; Hitchcock, David B.; Guinn, Caroline H.; Vaadi, Kate K.; Puryear, Megan P.; Royer, Julie A.; McIver, Kerry L.; Dowda, Marsha; Pate, Russell R.; Wilson, Dawn K.

    2014-01-01

    interactions mentioned. Content effects depended on other factors. Grade effects were mixed. Dietary accuracy was better with same-day than previous-day retention interval. Conclusions Results do not support integrating dietary intake and physical activity in children’s recalls, but do support using shorter rather than longer retention intervals to yield more accurate dietary recalls. Further validation studies need to clarify age effects and identify evidence-based practices to improve children’s accuracy for recalling dietary intake and/or physical activity. PMID:24767807

  20. Effects of accuracy motivation and anchoring on metacomprehension judgment and accuracy.

    PubMed

    Zhao, Qin

    2012-01-01

    The current research investigates how accuracy motivation impacts anchoring and adjustment in metacomprehension judgment and how accuracy motivation and anchoring affect metacomprehension accuracy. Participants were randomly assigned to one of six conditions produced by the between-subjects factorial design involving accuracy motivation (incentive or no) and peer performance anchor (95%, 55%, or no). Two studies showed that accuracy motivation did not impact anchoring bias, but the adjustment-from-anchor process occurred. Accuracy incentive increased anchor-judgment gap for the 95% anchor but not for the 55% anchor, which induced less certainty about the direction of adjustment. The findings offer support to the integrative theory of anchoring. Additionally, the two studies revealed a "power struggle" between accuracy motivation and anchoring in influencing metacomprehension accuracy. Accuracy motivation could improve metacomprehension accuracy in spite of anchoring effect, but if anchoring effect is too strong, it could overpower the motivation effect. The implications of the findings were discussed.

  1. Comparison of Diagnostic Accuracy of PCR Targeting the 47-Kilodalton Protein Membrane Gene of Treponema pallidum and PCR Targeting the DNA Polymerase I Gene: Systematic Review and Meta-analysis

    PubMed Central

    Combescure, Christophe; Lautenschlager, Stephan; Ninet, Béatrice; Perneger, Thomas V.

    2015-01-01

    Treponema pallidum PCR (Tp-PCR) testing now is recommended as a valid tool for the diagnosis of primary or secondary syphilis. The objectives were to systematically review and determine the optimal specific target gene to be used for Tp-PCR. Comparisons of the performance of the two main targets are tpp47 and polA genes were done using meta-analysis. Three electronic bibliographic databases, representing abstract books from five conferences specialized in infectious diseases from January 1990 to March 2015, were searched. Search keywords included (“syphilis” OR “Treponema pallidum” OR “neurosyphilis”) AND (“PCR” OR “PCR” OR “molecular amplification”). We included diagnostic studies assessing the performance of Tp-PCR targeting tpp47 (tpp47-Tp-PCR) or the polA gene (polA-Tp-PCR) in ulcers from early syphilis. All studies were assessed against quality criteria using the QUADAS-2 tool. Of 37 studies identified, 62.2% were judged at low risk of bias or applicability. Most used the U.S. Centers for Disease Control and Prevention (CDC) case definitions for primary or secondary (early) syphilis (89.2%; n = 33); 15 (40.5%) used darkfield microscopy (DFM). We did not find differences in sensitivity and specificity between the two Tp-PCR methods in the subgroup of studies using adequate reference tests. Among studies using DFM as the reference test, sensitivities were 79.8% (95% confidence intervals [CI], 72.7 to 85.4%) and 71.4% (46.0 to 88.0%) for tpp47-Tp-PCR and polA-Tp-PCR (P = 0.217), respectively; respective specificities were 95.3% (93.5 to 96.6%) and 93.7% (91.8 to 95.2%) (P = 0.304). Our findings suggest that the two Tp-PCR methods have similar accuracy and could be used interchangeably. PMID:26311859

  2. A pilot study to determine whether using a lightweight, wearable micro-camera improves dietary assessment accuracy and offers information on macronutrients and eating rate.

    PubMed

    Pettitt, Claire; Liu, Jindong; Kwasnicki, Richard M; Yang, Guang-Zhong; Preston, Thomas; Frost, Gary

    2016-01-14

    A major limitation in nutritional science is the lack of understanding of the nutritional intake of free-living people. There is an inverse relationship between accuracy of reporting of energy intake by all current nutritional methodologies and body weight. In this pilot study we aim to explore whether using a novel lightweight, wearable micro-camera improves the accuracy of dietary intake assessment. Doubly labelled water (DLW) was used to estimate energy expenditure and intake over a 14-d period, over which time participants (n 6) completed a food diary and wore a micro-camera on 2 of the days. Comparisons were made between the estimated energy intake from the reported food diary alone and together with the images from the micro-camera recordings. There was an average daily deficit of 3912 kJ using food diaries to estimate energy intake compared with estimated energy expenditure from DLW (P=0·0118), representing an under-reporting rate of 34 %. Analysis of food diaries alone showed a significant deficit in estimated daily energy intake compared with estimated intake from food diary analysis with images from the micro-camera recordings (405 kJ). Use of the micro-camera images in conjunction with food diaries improves the accuracy of dietary assessment and provides valuable information on macronutrient intake and eating rate. There is a need to develop this recording technique to remove user and assessor bias.

  3. Comparative evaluation of the accuracy of two electronic apex locators in determining the working length in teeth with simulated apical root resorption: An in vitro study

    PubMed Central

    Saraswathi, Vidya; Kedia, Archit; Purayil, Tina Puthen; Ballal, Vasudev; Saini, Aakriti

    2016-01-01

    Introduction: Accurate determination of working length (WL) is a critical factor for endodontic success. This is commonly achieved using an apex locator which is influenced by the presence or absence of the apical constriction. Hence, this study was done to compare the accuracy of two generations of apex locators in teeth with simulated apical root resorption. Materials and Methods: Forty maxillary central incisors were selected and after access preparation, were embedded in an alginate mold. On achieving partial set, teeth were removed, and a 45° oblique cut was made at the apex. The teeth were replanted and stabilized in the mold, and WL was determined using two generations of apex locators (Raypex 5 and Apex NRG XFR). Actual length of teeth (control) was determined by visual method. Statistical Analysis: Results were subjected to statistical analysis using the paired t-test. Results: Raypex 5 and Apex NRG was accurate for only 33.75% and 23.75% of samples, respectively. However, with ±0.5 mm acceptance limit, they showed an average accuracy of 56.2% and 57.5%, respectively. There was no significant difference in the accuracy between the two apex locators. Conclusion: Neither of the two apex locators were 100% accurate in determining the WL.

  4. Comparative evaluation of the accuracy of two electronic apex locators in determining the working length in teeth with simulated apical root resorption: An in vitro study

    PubMed Central

    Saraswathi, Vidya; Kedia, Archit; Purayil, Tina Puthen; Ballal, Vasudev; Saini, Aakriti

    2016-01-01

    Introduction: Accurate determination of working length (WL) is a critical factor for endodontic success. This is commonly achieved using an apex locator which is influenced by the presence or absence of the apical constriction. Hence, this study was done to compare the accuracy of two generations of apex locators in teeth with simulated apical root resorption. Materials and Methods: Forty maxillary central incisors were selected and after access preparation, were embedded in an alginate mold. On achieving partial set, teeth were removed, and a 45° oblique cut was made at the apex. The teeth were replanted and stabilized in the mold, and WL was determined using two generations of apex locators (Raypex 5 and Apex NRG XFR). Actual length of teeth (control) was determined by visual method. Statistical Analysis: Results were subjected to statistical analysis using the paired t-test. Results: Raypex 5 and Apex NRG was accurate for only 33.75% and 23.75% of samples, respectively. However, with ±0.5 mm acceptance limit, they showed an average accuracy of 56.2% and 57.5%, respectively. There was no significant difference in the accuracy between the two apex locators. Conclusion: Neither of the two apex locators were 100% accurate in determining the WL. PMID:27656055

  5. When Does Choice of Accuracy Measure Alter Imputation Accuracy Assessments?

    PubMed

    Ramnarine, Shelina; Zhang, Juan; Chen, Li-Shiun; Culverhouse, Robert; Duan, Weimin; Hancock, Dana B; Hartz, Sarah M; Johnson, Eric O; Olfson, Emily; Schwantes-An, Tae-Hwi; Saccone, Nancy L

    2015-01-01

    Imputation, the process of inferring genotypes for untyped variants, is used to identify and refine genetic association findings. Inaccuracies in imputed data can distort the observed association between variants and a disease. Many statistics are used to assess accuracy; some compare imputed to genotyped data and others are calculated without reference to true genotypes. Prior work has shown that the Imputation Quality Score (IQS), which is based on Cohen's kappa statistic and compares imputed genotype probabilities to true genotypes, appropriately adjusts for chance agreement; however, it is not commonly used. To identify differences in accuracy assessment, we compared IQS with concordance rate, squared correlation, and accuracy measures built into imputation programs. Genotypes from the 1000 Genomes reference populations (AFR N = 246 and EUR N = 379) were masked to match the typed single nucleotide polymorphism (SNP) coverage of several SNP arrays and were imputed with BEAGLE 3.3.2 and IMPUTE2 in regions associated with smoking behaviors. Additional masking and imputation was conducted for sequenced subjects from the Collaborative Genetic Study of Nicotine Dependence and the Genetic Study of Nicotine Dependence in African Americans (N = 1,481 African Americans and N = 1,480 European Americans). Our results offer further evidence that concordance rate inflates accuracy estimates, particularly for rare and low frequency variants. For common variants, squared correlation, BEAGLE R2, IMPUTE2 INFO, and IQS produce similar assessments of imputation accuracy. However, for rare and low frequency variants, compared to IQS, the other statistics tend to be more liberal in their assessment of accuracy. IQS is important to consider when evaluating imputation accuracy, particularly for rare and low frequency variants. PMID:26458263

  6. Fourth-grade children's dietary recall accuracy for energy intake at school meals differs by social desirability and body mass index percentile in a study concerning retention interval.

    PubMed

    Guinn, Caroline H; Baxter, Suzanne D; Royer, Julie A; Hardin, James W; Mackelprang, Alyssa J; Smith, Albert F

    2010-05-01

    Data from a study concerning retention interval and school-meal observation on children's dietary recalls were used to investigate relationships of social desirability score (SDS) and body mass index percentile (BMI%) to recall accuracy for energy for observed (n = 327) children, and to reported energy for observed and unobserved (n = 152) children. Report rates (reported/observed) correlated negatively with SDS and BMI%. Correspondence rates (correctly reported/observed) correlated negatively with SDS. Inflation ratios (overreported/observed) correlated negatively with BMI%. The relationship between reported energy and each of SDS and BMI% did not depend on observation status. Studies utilizing children's dietary recalls should assess SDS and BMI%. PMID:20460407

  7. Do Proficiency and Study-Abroad Experience Affect Speech Act Production? Analysis of Appropriateness, Accuracy, and Fluency

    ERIC Educational Resources Information Center

    Taguchi, Naoko

    2011-01-01

    This cross-sectional study examined the effect of general proficiency and study-abroad experience in production of speech acts among learners of L2 English. Participants were 25 native speakers of English and 64 Japanese college students of English divided into three groups. Group 1 (n = 22) had lower proficiency and no study-abroad experience.…

  8. Ground Truth Sampling and LANDSAT Accuracy Assessment

    NASA Technical Reports Server (NTRS)

    Robinson, J. W.; Gunther, F. J.; Campbell, W. J.

    1982-01-01

    It is noted that the key factor in any accuracy assessment of remote sensing data is the method used for determining the ground truth, independent of the remote sensing data itself. The sampling and accuracy procedures developed for nuclear power plant siting study are described. The purpose of the sampling procedure was to provide data for developing supervised classifications for two study sites and for assessing the accuracy of that and the other procedures used. The purpose of the accuracy assessment was to allow the comparison of the cost and accuracy of various classification procedures as applied to various data types.

  9. Updating flood maps efficiently using existing hydraulic models, very-high-accuracy elevation data, and a geographic information system; a pilot study on the Nisqually River, Washington

    USGS Publications Warehouse

    Jones, Joseph L.; Haluska, Tana L.; Kresch, David L.

    2001-01-01

    A method of updating flood inundation maps at a fraction of the expense of using traditional methods was piloted in Washington State as part of the U.S. Geological Survey Urban Geologic and Hydrologic Hazards Initiative. Large savings in expense may be achieved by building upon previous Flood Insurance Studies and automating the process of flood delineation with a Geographic Information System (GIS); increases in accuracy and detail result from the use of very-high-accuracy elevation data and automated delineation; and the resulting digital data sets contain valuable ancillary information such as flood depth, as well as greatly facilitating map storage and utility. The method consists of creating stage-discharge relations from the archived output of the existing hydraulic model, using these relations to create updated flood stages for recalculated flood discharges, and using a GIS to automate the map generation process. Many of the effective flood maps were created in the late 1970?s and early 1980?s, and suffer from a number of well recognized deficiencies such as out-of-date or inaccurate estimates of discharges for selected recurrence intervals, changes in basin characteristics, and relatively low quality elevation data used for flood delineation. FEMA estimates that 45 percent of effective maps are over 10 years old (FEMA, 1997). Consequently, Congress has mandated the updating and periodic review of existing maps, which have cost the Nation almost 3 billion (1997) dollars. The need to update maps and the cost of doing so were the primary motivations for piloting a more cost-effective and efficient updating method. New technologies such as Geographic Information Systems and LIDAR (Light Detection and Ranging) elevation mapping are key to improving the efficiency of flood map updating, but they also improve the accuracy, detail, and usefulness of the resulting digital flood maps. GISs produce digital maps without manual estimation of inundated areas between

  10. Achieving plane wave accuracy in linear-scaling density functional theory applied to periodic systems: A case study on crystalline silicon

    NASA Astrophysics Data System (ADS)

    Skylaris, Chris-Kriton; Haynes, Peter D.

    2007-10-01

    Linear-scaling methods for density functional theory promise to revolutionize the scope and scale of first-principles quantum mechanical calculations. Crystalline silicon has been the system of choice for exploratory tests of such methods in the literature, yet attempts at quantitative comparisons under linear-scaling conditions with traditional methods or experimental results have not been forthcoming. A detailed study using the ONETEP code is reported here, demonstrating for the first time that plane wave accuracy can be achieved in linear-scaling calculations on periodic systems.

  11. A simulation study of predictive ability measures in a survival model II: explained randomness and predictive accuracy.

    PubMed

    Choodari-Oskooei, B; Royston, P; Parmar, Mahesh K B

    2012-10-15

    Several R(2) -type measures have been proposed to evaluate the predictive ability of a survival model. In Part I, we classified the measures into four categories and studied the measures in the explained variation category. In this paper, we study the remaining measures in a similar fashion, discussing their strengths and shortcomings. Simulation studies are used to examine the performance of the measures with respect to the criteria we set out in Part I. Our simulation studies showed that among the measures studied in this paper, the measures proposed by Kent and O'Quigley ρ(W)(2) (and its approximation ρ(W,A)(2)) and Schemper and Kaider R(SK)(2) perform better with respect to our criteria. However, our investigations showed that ρ(W)(2) is adversely affected by the distribution of covariate and the presence of influential observations. The results show that the other measures perform poorly, primarily because they are affected either by the degree of censoring or the follow-up period.

  12. GEOSPATIAL DATA ACCURACY ASSESSMENT

    EPA Science Inventory

    The development of robust accuracy assessment methods for the validation of spatial data represent's a difficult scientific challenge for the geospatial science community. The importance and timeliness of this issue is related directly to the dramatic escalation in the developmen...

  13. Classification accuracy improvement

    NASA Technical Reports Server (NTRS)

    Kistler, R.; Kriegler, F. J.

    1977-01-01

    Improvements made in processing system designed for MIDAS (prototype multivariate interactive digital analysis system) effects higher accuracy in classification of pixels, resulting in significantly-reduced processing time. Improved system realizes cost reduction factor of 20 or more.

  14. Overlay accuracy fundamentals

    NASA Astrophysics Data System (ADS)

    Kandel, Daniel; Levinski, Vladimir; Sapiens, Noam; Cohen, Guy; Amit, Eran; Klein, Dana; Vakshtein, Irina

    2012-03-01

    Currently, the performance of overlay metrology is evaluated mainly based on random error contributions such as precision and TIS variability. With the expected shrinkage of the overlay metrology budget to < 0.5nm, it becomes crucial to include also systematic error contributions which affect the accuracy of the metrology. Here we discuss fundamental aspects of overlay accuracy and a methodology to improve accuracy significantly. We identify overlay mark imperfections and their interaction with the metrology technology, as the main source of overlay inaccuracy. The most important type of mark imperfection is mark asymmetry. Overlay mark asymmetry leads to a geometrical ambiguity in the definition of overlay, which can be ~1nm or less. It is shown theoretically and in simulations that the metrology may enhance the effect of overlay mark asymmetry significantly and lead to metrology inaccuracy ~10nm, much larger than the geometrical ambiguity. The analysis is carried out for two different overlay metrology technologies: Imaging overlay and DBO (1st order diffraction based overlay). It is demonstrated that the sensitivity of DBO to overlay mark asymmetry is larger than the sensitivity of imaging overlay. Finally, we show that a recently developed measurement quality metric serves as a valuable tool for improving overlay metrology accuracy. Simulation results demonstrate that the accuracy of imaging overlay can be improved significantly by recipe setup optimized using the quality metric. We conclude that imaging overlay metrology, complemented by appropriate use of measurement quality metric, results in optimal overlay accuracy.

  15. Accuracy of thoracolumbar transpedicular and vertebral body percutaneous screw placement: coupling the Rosa® Spine robot with intraoperative flat-panel CT guidance--a cadaver study.

    PubMed

    Lefranc, M; Peltier, J

    2015-12-01

    The primary objective of the present study was to evaluate the accuracy of a new robotic device when coupled with intraoperative flat-panel CT guidance. Screws (D8-S1) were implanted during two separate cadaver sessions by coupling the Rosa(®) Spine robot with the flat-panel CT device. Of 38 implanted screws, 37 (97.4 %) were fully contained within the pedicle. One screw breached the lateral cortical of one pedicle by <1 mm. The mean ± SD accuracy (relative to pre-operative planning) was 2.05 ± 1.2 mm for the screw head, 1.65 ± 1.11 for the middle of the pedicle and 1.57 ± 1.01 for the screw tip. When coupled with intraoperative flat-panel CT guidance, the Rosa(®) Spine robot appears to be accurate in placing pedicle screws within both pedicles and the vertebral body. Large clinical studies are mandatory to confirm this preliminary cadaveric report. PMID:26530846

  16. Experimental and numerical study of the accuracy of flame-speed measurements for methane/air combustion in a slot burner

    SciTech Connect

    Selle, L.; Ferret, B.; Poinsot, T.

    2011-01-15

    Measuring the velocities of premixed laminar flames with precision remains a controversial issue in the combustion community. This paper studies the accuracy of such measurements in two-dimensional slot burners and shows that while methane/air flame speeds can be measured with reasonable accuracy, the method may lack precision for other mixtures such as hydrogen/air. Curvature at the flame tip, strain on the flame sides and local quenching at the flame base can modify local flame speeds and require corrections which are studied using two-dimensional DNS. Numerical simulations also provide stretch, displacement and consumption flame speeds along the flame front. For methane/air flames, DNS show that the local stretch remains small so that the local consumption speed is very close to the unstretched premixed flame speed. The only correction needed to correctly predict flame speeds in this case is due to the finite aspect ratio of the slot used to inject the premixed gases which induces a flow acceleration in the measurement region (this correction can be evaluated from velocity measurement in the slot section or from an analytical solution). The method is applied to methane/air flames with and without water addition and results are compared to experimental data found in the literature. The paper then discusses the limitations of the slot-burner method to measure flame speeds for other mixtures and shows that it is not well adapted to mixtures with a Lewis number far from unity, such as hydrogen/air flames. (author)

  17. Accuracy assessment on the analysis of unbound drug in plasma by comparing traditional centrifugal ultrafiltration with hollow fiber centrifugal ultrafiltration and application in pharmacokinetic study.

    PubMed

    Zhang, Lin; Zhang, Zhi-Qing; Dong, Wei-Chong; Jing, Shao-Jun; Zhang, Jin-Feng; Jiang, Ye

    2013-11-29

    In present study, accuracy assessment on the analysis of unbound drug in plasma was made by comparing traditional centrifugal ultrafiltration (CF-UF) with hollow fiber centrifugal ultrafiltration (HFCF-UF). We used metformin (MET) as a model drug and studied the influence of centrifugal time, plasma condition and freeze-thaw circle times on the ultrafiltrate volume and related effect on the measurement of MET. Our results demonstrated that ultrafiltrate volume was a crucial factor which influenced measurement accuracy of unbound drug in plasma. For traditional CF-UF, the ultrafiltrate volume cannot be well-controlled due to a series of factors. Compared with traditional CF-UF, the ultrafiltrate volume by HFCF-UF can be easily controlled by the inner capacity of the U-shaped hollow fiber inserted into the sample under enough centrifugal force and centrifugal time, which contributes to a more accurate measurement. Moreover, the developed HFCF-UF method achieved a successful application in real plasma samples and exhibited several advantages including high precision, extremely low detection limit and perfect recovery. The HFCF-UF method offers the advantage of highly satisfactory performance in addition to being simple and fast in pretreatment, with these characteristics being consistent with the practicability requirements in current scientific research.

  18. Image-Guided Localization Accuracy of Stereoscopic Planar and Volumetric Imaging Methods for Stereotactic Radiation Surgery and Stereotactic Body Radiation Therapy: A Phantom Study

    SciTech Connect

    Kim, Jinkoo; Jin, Jian-Yue; Walls, Nicole; Nurushev, Teamour; Movsas, Benjamin; Chetty, Indrin J.; Ryu, Samuel

    2011-04-01

    Purpose: To evaluate the positioning accuracies of two image-guided localization systems, ExacTrac and On-Board Imager (OBI), in a stereotactic treatment unit. Methods and Materials: An anthropomorphic pelvis phantom with eight internal metal markers (BBs) was used. The center of one BB was set as plan isocenter. The phantom was set up on a treatment table with various initial setup errors. Then, the errors were corrected using each of the investigated systems. The residual errors were measured with respect to the radiation isocenter using orthogonal portal images with field size 3 x 3 cm{sup 2}. The angular localization discrepancies of the two systems and the correction accuracy of the robotic couch were also studied. A pair of pre- and post-cone beam computed tomography (CBCT) images was acquired for each angular correction. Then, the correction errors were estimated by using the internal BBs through fiducial marker-based registrations. Results: The isocenter localization errors ({mu} {+-}{sigma}) in the left/right, posterior/anterior, and superior/inferior directions were, respectively, -0.2 {+-} 0.2 mm, -0.8 {+-} 0.2 mm, and -0.8 {+-} 0.4 mm for ExacTrac, and 0.5 {+-} 0.7 mm, 0.6 {+-} 0.5 mm, and 0.0 {+-} 0.5 mm for OBI CBCT. The registration angular discrepancy was 0.1 {+-} 0.2{sup o} between the two systems, and the maximum angle correction error of the robotic couch was 0.2{sup o} about all axes. Conclusion: Both the ExacTrac and the OBI CBCT systems showed approximately 1 mm isocenter localization accuracies. The angular discrepancy of two systems was minimal, and the robotic couch angle correction was accurate. These positioning uncertainties should be taken as a lower bound because the results were based on a rigid dosimetry phantom.

  19. Improving power and accuracy of genome-wide association studies via a multi-locus mixed linear model methodology

    PubMed Central

    Wang, Shi-Bo; Feng, Jian-Ying; Ren, Wen-Long; Huang, Bo; Zhou, Ling; Wen, Yang-Jun; Zhang, Jin; Dunwell, Jim M.; Xu, Shizhong; Zhang, Yuan-Ming

    2016-01-01

    Genome-wide association studies (GWAS) have been widely used in genetic dissection of complex traits. However, common methods are all based on a fixed-SNP-effect mixed linear model (MLM) and single marker analysis, such as efficient mixed model analysis (EMMA). These methods require Bonferroni correction for multiple tests, which often is too conservative when the number of markers is extremely large. To address this concern, we proposed a random-SNP-effect MLM (RMLM) and a multi-locus RMLM (MRMLM) for GWAS. The RMLM simply treats the SNP-effect as random, but it allows a modified Bonferroni correction to be used to calculate the threshold p value for significance tests. The MRMLM is a multi-locus model including markers selected from the RMLM method with a less stringent selection criterion. Due to the multi-locus nature, no multiple test correction is needed. Simulation studies show that the MRMLM is more powerful in QTN detection and more accurate in QTN effect estimation than the RMLM, which in turn is more powerful and accurate than the EMMA. To demonstrate the new methods, we analyzed six flowering time related traits in Arabidopsis thaliana and detected more genes than previous reported using the EMMA. Therefore, the MRMLM provides an alternative for multi-locus GWAS. PMID:26787347

  20. Improving power and accuracy of genome-wide association studies via a multi-locus mixed linear model methodology.

    PubMed

    Wang, Shi-Bo; Feng, Jian-Ying; Ren, Wen-Long; Huang, Bo; Zhou, Ling; Wen, Yang-Jun; Zhang, Jin; Dunwell, Jim M; Xu, Shizhong; Zhang, Yuan-Ming

    2016-01-01

    Genome-wide association studies (GWAS) have been widely used in genetic dissection of complex traits. However, common methods are all based on a fixed-SNP-effect mixed linear model (MLM) and single marker analysis, such as efficient mixed model analysis (EMMA). These methods require Bonferroni correction for multiple tests, which often is too conservative when the number of markers is extremely large. To address this concern, we proposed a random-SNP-effect MLM (RMLM) and a multi-locus RMLM (MRMLM) for GWAS. The RMLM simply treats the SNP-effect as random, but it allows a modified Bonferroni correction to be used to calculate the threshold p value for significance tests. The MRMLM is a multi-locus model including markers selected from the RMLM method with a less stringent selection criterion. Due to the multi-locus nature, no multiple test correction is needed. Simulation studies show that the MRMLM is more powerful in QTN detection and more accurate in QTN effect estimation than the RMLM, which in turn is more powerful and accurate than the EMMA. To demonstrate the new methods, we analyzed six flowering time related traits in Arabidopsis thaliana and detected more genes than previous reported using the EMMA. Therefore, the MRMLM provides an alternative for multi-locus GWAS. PMID:26787347

  1. Accuracy of erythrogram and serum ferritin for the maternal anemia diagnosis (AMA): a phase 3 diagnostic study on prediction of the therapeutic responsiveness to oral iron in pregnancy

    PubMed Central

    2013-01-01

    Background Pregnancy anemia remains as a public health problem, since the official reports in the 70’s. To guide the treatment of iron-deficiency anemia in pregnancy, the haemoglobin concentration is the most used test in spite of its low accuracy, and serum ferritin is the most reliable test, although its cutoff point remains an issue. Methods/design The aim of this protocol is to verify the accuracy of erythrocyte indices and serum ferritin (studied tests) for the diagnosis of functional iron-deficiency in pregnancy using the iron-therapy responsiveness as the gold-standard. This is an ongoing phase III accuracy study initiated in August 2011 and to be concluded in April 2013. The subjects are anemic pregnant women (haemoglobin concentration < 11.0 g/dL) attended at a low-risk prenatal care center in the Northeast of Brazil. The sample size (n 278) was calculated to estimate sensitivity of 90% and 80% of specificity with relative error of 10% and power of 95%. This study has a prospective design with a before-after intervention of 80 mg of daily oral iron during 90 days and will be analyzed as a delayed-type cross-sectional study. Women at the second trimester of pregnancy are being evaluated with clinical and laboratorial examinations at the enrollment and monthly. The ‘responsiveness to therapeutic test with oral iron’ (gold-standard) was defined to an increase of at least 0.55 Z-score in haemoglobin after 4 weeks of treatment and a total dose of 1200 mg of iron. At the study conclusion, sensitivities, specificities, predictive values, likelihood ratios and areas under the ROC (Receiver Operating Characteristic) curves of serum ferritin and erythrocyte indices (red blood cell count, haematocrit, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red blood cell distribution width, reticulocyte count) will be tested. The compliance and adverse effects are considered

  2. The relationship between articulatory control and improved phonemic accuracy in childhood apraxia of speech: A longitudinal case study

    PubMed Central

    Grigos, Maria I.; Kolenda, Nicole

    2010-01-01

    Jaw movement patterns were examined longitudinally in a 3-year-old male with childhood apraxia of speech (CAS) and compared with a typically developing control group. The child with CAS was followed for 8 months, until he began accurately and consistently producing the bilabial phonemes /p/, /b/, and /m/. A movement tracking system was used to study jaw duration, displacement, velocity, and stability. A transcription analysis determined the percentage of phoneme errors and consistency. Results showed phoneme-specific changes which included increases in jaw velocity and stability over time, as well as decreases in duration. Kinematic parameters became more similar to patterns seen in the controls during final sessions where tokens were produced most accurately and consistently. Closing velocity and stability, however, were the only measures to fall within a 95% confidence interval established for the controls across all three target phonemes. These findings suggest that motor processes may differ between children with CAS and their typically developing peers. PMID:20030551

  3. A case-study on the accuracy of mass balances for xenobiotics in full-scale wastewater treatment plants.

    PubMed

    Majewsky, Marius; Farlin, Julien; Bayerle, Michael; Gallé, Tom

    2013-04-01

    Removal efficiencies of micropollutants in wastewater treatment plants (WWTPs) are usually evaluated from mass balance calculations using a small number of observations drawn from short sampling campaigns. Since micropollutant loads can vary greatly in both influent and effluent and reactor tanks exhibit specific hydraulic residence times, these short-term approaches are particularly prone to yield erroneous removal values. A detailed investigation of micropollutant transit times at full-scale and on how this affects mass balancing results was still lacking. The present study used hydraulic residence time distributions to scrutinize the match of influent loads to effluent loads of 10 polar micropollutants with different influent dynamics in a full-scale WWTP. Prior hydraulic modeling indicated that a load sampled over one day in the effluent is composed of influent load fractions of five preceding days. Results showed that the error of the mass balance can be reduced with increasing influent sampling duration. The approach presented leads to a more reliable estimation of the removal efficiencies of those micropollutants which can be constantly detected in influents, such as pharmaceuticals, but provides no advantage for pesticides due to their sporadic occurrence. The mismatch between sampled influent and effluent loads was identified as a major error source and an explanation was provided for the occurrence of negative mass balances regularly reported. This study indicates that the accurate determination of global removal values is only feasible in full-scale investigations with sampling durations much longer than 1 day. In any case, the uncertainty of these values needs to be reported when used in removal assessment, model selection or validation. PMID:23474799

  4. Benefit of cerebrospinal fluid spectrophotometry in the assessment of CT scan negative suspected subarachnoid haemorrhage: a diagnostic accuracy study.

    PubMed

    Hann, Angus; Chu, Kevin; Greenslade, Jaimi; Williams, Julian; Brown, Anthony

    2015-01-01

    This study aimed to determine if performing cerebrospinal fluid spectrophotometry in addition to visual inspection detects more ruptured cerebral aneurysms than performing cerebrospinal fluid visual inspection alone in patients with a normal head CT scan but suspected of suffering an aneurysmal subarachnoid haemorrhage (SAH). We performed a single-centre retrospective study of patients presenting to the emergency department of a tertiary hospital who underwent both head CT scan and lumbar puncture to exclude SAH. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of an approach utilising both spectrophotometry and visual inspection (combined approach) was compared to visual inspection alone. A total of 409 patients (mean age 37.8 years, 56.2% female) were recruited and six (1.5%) had a cerebral aneurysm on angiography. The sensitivity of visual inspection was 50% (95% confidence interval [CI]: 12.4-82.6%), specificity was 99% (95% CI: 97.5-99.7%), PPV was 42.9% (95% CI: 10.4-81.3%) and NPV was 99.2% (95% CI: 97.8-99.8%). The combined approach had a sensitivity of 100% (95% CI: 54.1-100%), specificity of 79.7% (95% CI: 75.4-83.5%), PPV of 6.8% (95% CI: 2.6-14.3%) and a NPV of 100% (95% CI: 98.8-100%). The sensitivity of the combined approach was not significantly different to that of visual inspection alone (p=0.25). Visual inspection had a significantly higher specificity than the combined approach (p<0.01). The combined approach detected more cases of aneurysmal SAH than visual inspection alone, however the difference in sensitivity was not statistically significant. Visual xanthochromia should prompt angiography because of a superior specificity and PPV. Due to its reduced sensitivity, caution should be applied when using only visual inspection of the supernatant.

  5. Accuracy of malaria rapid diagnostic tests in community studies and their impact on treatment of malaria in an area with declining malaria burden in north-eastern Tanzania

    PubMed Central

    2011-01-01

    Background Despite some problems related to accuracy and applicability of malaria rapid diagnostic tests (RDTs), they are currently the best option in areas with limited laboratory services for improving case management through parasitological diagnosis and reducing over-treatment. This study was conducted in areas with declining malaria burden to assess; 1) the accuracy of RDTs when used at different community settings, 2) the impact of using RDTs on anti-malarial dispensing by community-owned resource persons (CORPs) and 3) adherence of CORPs to treatment guidelines by providing treatment based on RDT results. Methods Data were obtained from: 1) a longitudinal study of passive case detection of fevers using CORPs in six villages in Korogwe; and 2) cross-sectional surveys (CSS) in six villages of Korogwe and Muheza districts, north-eastern, Tanzania. Performance of RDTs was compared with microscopy as a gold standard, and factors affecting their accuracy were explored using a multivariate logistic regression model. Results Overall sensitivity and specificity of RDTs in the longitudinal study (of 23,793 febrile cases; 18,154 with microscopy and RDTs results) were 88.6% and 88.2%, respectively. In the CSS, the sensitivity was significantly lower (63.4%; χ2 = 367.7, p < 0.001), while the specificity was significantly higher (94.3%; χ2 = 143.1, p < 0.001) when compared to the longitudinal study. As determinants of sensitivity of RDTs in both studies, parasite density of < 200 asexual parasites/μl was significantly associated with high risk of false negative RDTs (OR≥16.60, p < 0.001), while the risk of false negative test was significantly lower among cases with fever (axillary temperature ≥37.5°C) (OR ≤ 0.63, p ≤ 0.027). The risk of false positive RDT (as a determinant of specificity) was significantly higher in cases with fever compared to afebrile cases (OR≥2.40, p < 0.001). Using RDTs reduced anti-malarials dispensing from 98.9% to 32.1% in cases

  6. Multiple interfacing between classical ray-tracing and wave-optical simulation approaches: a study on applicability and accuracy.

    PubMed

    Leiner, Claude; Nemitz, Wolfgang; Schweitzer, Susanne; Wenzl, Franz P; Hartmann, Paul; Hohenester, Ulrich; Sommer, Christian

    2014-06-30

    In this study the applicability of an interface procedure for combined ray-tracing and finite difference time domain (FDTD) simulations of optical systems which contain two diffractive gratings is discussed. The simulation of suchlike systems requires multiple FDTD↔RT steps. In order to minimize the error due to the loss of the phase information in an FDTD→RT step, we derive an equation for a maximal coherence correlation function (MCCF) which describes the maximum degree of impact of phase effects between these two different diffraction gratings and which depends on: the spatial distance between the gratings, the degree of spatial coherence of the light source and the diffraction angle of the first grating for the wavelength of light used. This MCCF builds an envelope of the oscillations caused by the distance dependent coupling effects between the two diffractive optical elements. Furthermore, by comparing the far field projections of pure FDTD simulations with the results of an RT→FDTD→RT→FDTD→RT interface procedure simulation we show that this function strongly correlates with the error caused by the interface procedure.

  7. Accuracy in the Diagnosis of the Mental Nerve Loop. A Comparative Study Between Panoramic Radiography and Cone Beam Computed Tomography

    PubMed Central

    do Couto-Filho, Carlos Eduardo Gomes; de Moraes, Paulo Hemerson; Alonso, Maria Beatriz Carrazzone; Haiter-Neto, Francisco; Olate, Sergio; de Albergaria-Barbosa, José Ricardo

    2016-01-01

    Summary Dental implant and chin osteotomy are executed on the mandible body and the mental nerve is an important anatomical limit. The aim of this research was to know the position of the mental nerve loop comparing result in panoramic radiography and cone beam computed tomography. We analyzed 94 hemimandibles and the patient sample comprised female and male subjects of ages ranging from 18 to 52 years (mean age, 35 years) selected randomly from the database of patients at the Division of Oral Radiology at Piracicaba Dental School State University of Campinas; the anterior loop (AL) of the mental nerve was evaluated regarding the presence or absence, which was classified as rectilinear or curvilinear and measurement of its length was obtained. The observations were made in the digital panoramic radiography (PR) and the cone beam computed tomography (CBCT) according to a routine technique. The frequencies of the AL identified through PR and CBCT were different: in PR the loop was identified in 42.6% of cases, and only 12.8% were bilateral. In contrast, the AL was detected in 29.8% of the samples using CBCT, with 6.4% being bilateral; Statistical comparison between PR and CBCT showed that the PR led to false-positive diagnosis of the AL in this sample. According to the results of this study, the frequency of AL is low. Thus, it can be assumed that it is not a common condition in this population. PMID:27667898

  8. Evaluation of effect of tray space on the accuracy of condensation silicone, addition silicone and polyether impression materials: an in vitro study.

    PubMed

    Kumar, Varun; Aeran, Himanshu

    2012-09-01

    Optimal thickness of impression materials in the custom tray in order to get the most accurate impression. To investigate the effect of different tray spacer thickness on the accuracy and the dimensional stability of impressions made from monophasic condensation silicone, addition silicone and polyether impression materials. Three different types of elastomeric monophasic impression materials were used for making the impression of a master die with tray having tray spacer thickness of 2, 4 and 6 mm. Each type of impression was poured in die stone after 1 h. Each cast was analyzed by a travelling microscope and compared with the master die. The data was tabulated and subjected to statistical evaluation. The results of the study indicated that the impressions made from 2 to 4 mm spaced trays produced more accurate stone casts when compared to 6 mm spaced tray. No statistical significant differences were observed between the accuracy and dimensional stability of the three materials tested. Minimum changes were observed when the cast was poured after 1 h and the tray space was 2 mm for all the materials tested. It is therefore advisable not to exceed tray space of 2 mm.

  9. Manual landmark identification and tracking during the medial rotation test of the shoulder: an accuracy study using three-dimensional ultrasound and motion analysis measures.

    PubMed

    Morrissey, D; Morrissey, M C; Driver, W; King, J B; Woledge, R C

    2008-12-01

    Palpation of movement is a common clinical tool for assessment of movement in patients with musculoskeletal symptoms. The purpose of this study was to measure the accuracy of palpation of shoulder girdle translation during the medial rotation test (MRT) of the shoulder. The translation of the gleno-humeral and scapulo-thoracic joints was measured using both three-dimensional ultrasound and palpation in order to determine the accuracy of translation tracking during the MRT of the shoulder. Two movements of 11 normal subjects (mean age 24 (SD=4), range 19-47 years) were measured. The agreement between measures was good for scapulo-thoracic translation (r=0.83). Gleno-humeral translation was systematically under estimated (p=0.03) although moderate correlation was found (r=0.65). These results indicate that translation of the measured joints can be tracked by palpation and further tests of the efficacy of palpation tracking during musculoskeletal assessment may be warranted. PMID:18359266

  10. Pilot Study to Explore the Accuracy of Current Prediction Equations in Assessing Energy Needs of Patients with Newly Diagnosed Glioblastoma Multiforme.

    PubMed

    Little, Rebecca B; Oster, Robert A; Darnell, Betty E; Demark-Wahnefried, Wendy; Nabors, L Burt

    2016-01-01

    Glioblastoma multiforme (GBM) is rare, yet it is the most common brain malignancy and has a poor prognosis. In regard to GBM, there is a dearth of research on resting energy expenditure (REE) and the accuracy of extant prediction equations. The aim of this cross-sectional study was to compare measured REE (mREE) to commonly used prediction equations in newly diagnosed GBM patients. REE was collected by indirect calorimetry in 20 GBM patients. Calculated REE was derived from Harris-Benedict (again with weight adjusted for obesity), Mifflin-St Jeor, and the 20 kcal/kg body weight ratio method. Paired t-tests and Bland-Altman analyses were used to compare group means, evaluate the bias, and find the limits of agreement. Clinical accuracy was assessed by determining the percentage of patients with predicted REE within ±10% of mREE. Subjects were evenly distributed with regard to gender, primarily Caucasian, and largely overweight or obese and had a mean age of 57 years. All equations overestimated mREE. Mifflin-St Jeor and adjusted Harris-Benedict had the narrowest limits of agreement and accurately predicted 60% and 65% of subjects, respectively. Clinicians should be aware of the discrepancy between commonly used prediction equations and REE. More research is needed to verify these findings and decipher the cause and significance in the GBM population. PMID:27341142

  11. Diagnostic accuracy study of a factor VIII ELISA for detection of factor VIII antibodies in congenital and acquired haemophilia A.

    PubMed

    Batty, Paul; Moore, Gary W; Platton, Sean; Maloney, James C; Palmer, Ben; Bowles, Louise; Pasi, K John; Rangarajan, Savita; Hart, Daniel P

    2015-10-01

    Antibody formation to factor VIII (FVIII) remains the greatest clinical and diagnostic challenge to the haemophilia-treating physician. Current guidance for testing for inhibitory FVIII antibodies (inhibitors) recommends the functional Nijmegen-Bethesda assay (NBA). A FVIII ELISA offers a complementary, immunological approach for FVIII antibody testing. It was the aim of this study to retrospectively evaluate the performance of a FVIII ELISA (index) for detection of FVIII antibodies, compared with the NBA (reference). All samples sent for routine FVIII antibody testing at two haemophilia Comprehensive Care Centres, were tested in parallel using the NBA and a solid-phase, indirect FVIII ELISA kit (Immucor). A total of 497 samples from 239 patients (severe haemophilia A=140, non-severe haemophilia A=85, acquired haemophilia A=14) were available for analysis. Sixty-three samples tested positive by the NBA (prevalence 12.7%, 95% confidence interval [CI], 9.9-15.9 %), with a median inhibitor titre of 1.2 BU/ml (range 0.7-978.0). The FVIII ELISA demonstrated a specificity of 94.0% (95%CI, 91.3-96.0), sensitivity of 77.8% (95%CI, 65.5-87.3), negative predictive value of 96.7% (95%CI, 94.5-98.2), positive predictive value 65.3% (95%CI, 53.5-76.0), negative likelihood ratio 0.2 (95%CI, 0.1-0.4), positive likelihood ratio 13.0 (95%CI, 8.7-19.3) and a diagnostic odds ratio of 54.9 (95%CI, 27.0-112.0). Strong positive correlation (r=0.77, p<0.001) was seen between the results of the NBA (log adjusted) and FVIII ELISA optical density. In conclusion, FVIII ELISA offers a simple, specific, surveillance method enabling batch testing of non-urgent samples for the presence of FVIII antibodies.

  12. The Accuracy of Paleoenvironmental Reconstructions Based on Spring and Wetland Gastropod 18O Values: A Field Study

    NASA Astrophysics Data System (ADS)

    Sharpe, S. E.; Forester, R. M.

    2008-12-01

    Paired live gastropods and water samples were collected monthly for over two years from two localities near Reno, Nevada: a relatively stable cold, low-flow spring and a highly-variable wetland. Shell samples from gastropods (Gyraulus, Physella, Planorbella, Stagnicola) were crushed to a homogeneous powder and analyzed for stable isotopes (n=115). Annual δ18O water values varied between -15.6 and - 14.8‰ (SMOW) and water temperature varied between 12 and 23° C at the spring locality. Shell δ18O values at the spring locality ranged from 15.5 to 19.9‰ (SMOW). The gastropod δ18O values exhibited the general pattern of seasonal variability (lower values in warm months and higher values in cold months) although they were offset from the expected equilibrium fractionation value, possibly reflecting a vital effect, calcification in a microhabitat, or error in estimating the timing (e.g., month) of calcification. The offset averaged 0.8‰ for Physella and 2.8‰ for Stagnicola. In contrast to the spring, the wetland annual δ18O water varied between -13.0 and -2.4‰, while water temperature varied between 4 and 26° C. Shell δ18O values ranged from 20.7 to 30.2‰ reflecting seasonal extremes of hydrologic input (springflow and runoff) to output (evaporation) in the wetland and possibly diurnal and monthly variability in the system and differential seasonal or diurnal shell growth. Different hydrologic systems have characteristic isotope systematics. This study shows that δ18O gastropod shell values are useful to infer seasonal changes and annual variability in hydrologic settings. Settings with limited seasonal variability host mollusks with relatively limited shell δ18O variability and vice versa. Life strategies (e.g., mobility, behavior, reproduction, and longevity) and possibly physiology (e.g., gills, lungs, or pseudobranch) of different genera, however, can affect isotopic values in the same setting and therefore, may be of critical importance when

  13. Study of accuracy in the position determination with SALSA, a γ-scanning system for the characterization of segmented HPGe detectors

    NASA Astrophysics Data System (ADS)

    Hernandez-Prieto, A.; Quintana, B.; Martìn, S.; Domingo-Pardo, C.

    2016-07-01

    Accurate characterization of the electric response of segmented high-purity germanium (HPGe) detectors as a function of the interaction position is one of the current goals of the Nuclear Physics community seeking to perform γ-ray tracking or even imaging with these detectors. For this purpose, scanning devices must be developed to achieve the signal-position association with the highest precision. With a view to studying the accuracy achieved with SALSA, the SAlamanca Lyso-based Scanning Array, here we report a detailed study on the uncertainty sources and their effect in the position determination inside the HPGe detector to be scanned. The optimization performed on the design of SALSA, aimed at minimizing the effect of the uncertainty sources, afforded an intrinsic uncertainty of ∼2 mm for large coaxial detectors and ∼1 mm for planar ones.

  14. Rapid detection of health-care-associated bloodstream infection in critical care using multipathogen real-time polymerase chain reaction technology: a diagnostic accuracy study and systematic review.

    PubMed Central

    Warhurst, Geoffrey; Dunn, Graham; Chadwick, Paul; Blackwood, Bronagh; McAuley, Daniel; Perkins, Gavin D; McMullan, Ronan; Gates, Simon; Bentley, Andrew; Young, Duncan; Carlson, Gordon L; Dark, Paul

    2015-01-01

    BACKGROUND There is growing interest in the potential utility of real-time polymerase chain reaction (PCR) in diagnosing bloodstream infection by detecting pathogen deoxyribonucleic acid (DNA) in blood samples within a few hours. SeptiFast (Roche Diagnostics GmBH, Mannheim, Germany) is a multipathogen probe-based system targeting ribosomal DNA sequences of bacteria and fungi. It detects and identifies the commonest pathogens causing bloodstream infection. As background to this study, we report a systematic review of Phase III diagnostic accuracy studies of SeptiFast, which reveals uncertainty about its likely clinical utility based on widespread evidence of deficiencies in study design and reporting with a high risk of bias. OBJECTIVE Determine the accuracy of SeptiFast real-time PCR for the detection of health-care-associated bloodstream infection, against standard microbiological culture. DESIGN Prospective multicentre Phase III clinical diagnostic accuracy study using the standards for the reporting of diagnostic accuracy studies criteria. SETTING Critical care departments within NHS hospitals in the north-west of England. PARTICIPANTS Adult patients requiring blood culture (BC) when developing new signs of systemic inflammation. MAIN OUTCOME MEASURES SeptiFast real-time PCR results at species/genus level compared with microbiological culture in association with independent adjudication of infection. Metrics of diagnostic accuracy were derived including sensitivity, specificity, likelihood ratios and predictive values, with their 95% confidence intervals (CIs). Latent class analysis was used to explore the diagnostic performance of culture as a reference standard. RESULTS Of 1006 new patient episodes of systemic inflammation in 853 patients, 922 (92%) met the inclusion criteria and provided sufficient information for analysis. Index test assay failure occurred on 69 (7%) occasions. Adult patients had been exposed to a median of 8 days (interquartile range 4

  15. Impact of scanning parameters and breathing patterns on image quality and accuracy of tumor motion reconstruction in 4D CBCT: a phantom study.

    PubMed

    Lee, Soyoung; Yan, Guanghua; Lu, Bo; Kahler, Darren; Li, Jonathan G; Sanjiv, Samat S

    2015-01-01

    Four-dimensional, cone-beam CT (4D CBCT) substantially reduces respiration-induced motion blurring artifacts in three-dimension (3D) CBCT. However, the image quality of 4D CBCT is significantly degraded which may affect its accuracy in localizing a mobile tumor for high-precision, image-guided radiation therapy (IGRT). The purpose of this study was to investigate the impact of scanning parameters hereinafter collectively referred to as scanning sequence) and breathing patterns on the image quality and the accuracy of computed tumor trajectory for a commercial 4D CBCT system, in preparation for its clinical implementation. We simulated a series of periodic and aperiodic sinusoidal breathing patterns with a respiratory motion phantom. The aperiodic pattern was created by varying the period or amplitude of individual sinusoidal breathing cycles. 4D CBCT scans of the phantom were acquired with a manufacturer-supplied scanning sequence (4D-S-slow) and two in-house modified scanning sequences (4D-M-slow and 4D-M-fast). While 4D-S-slow used small field of view (FOV), partial rotation (200°), and no imaging filter, 4D-M-slow and 4D-M-fast used medium FOV, full rotation, and the F1 filter. The scanning speed was doubled in 4D-M-fast (100°/min gantry rotation). The image quality of the 4D CBCT scans was evaluated using contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and motion blurring ratio (MBR). The trajectory of the moving target was reconstructed by registering each phase of the 4D CBCT with a reference CT. The root-mean-squared-error (RMSE) analysis was used to quantify its accuracy. Significant decrease in CNR and SNR from 3D CBCT to 4D CBCT was observed. The 4D-S-slow and 4D-M-fast scans had comparable image quality, while the 4D-M-slow scans had better performance due to doubled projections. Both CNR and SNR decreased slightly as the breathing period increased, while no dependence on the amplitude was observed. The difference of both CNR and SNR

  16. Measures of Diagnostic Accuracy: Basic Definitions

    PubMed Central

    Šimundić, Ana-Maria

    2009-01-01

    Diagnostic accuracy relates to the ability of a test to discriminate between the target condition and health. This discriminative potential can be quantified by the measures of diagnostic accuracy such as sensitivity and specificity, predictive values, likelihood ratios, the area under the ROC curve, Youden's index and diagnostic odds ratio. Different measures of diagnostic accuracy relate to the different aspects of diagnostic procedure: while some measures are used to assess the discriminative property of the test, others are used to assess its predictive ability. Measures of diagnostic accuracy are not fixed indicators of a test performance, some are very sensitive to the disease prevalence, while others to the spectrum and definition of the disease. Furthermore, measures of diagnostic accuracy are extremely sensitive to the design of the study. Studies not meeting strict methodological standards usually over- or under-estimate the indicators of test performance as well as they limit the applicability of the results of the study. STARD initiative was a very important step toward the improvement the quality of reporting of studies of diagnostic accuracy. STARD statement should be included into the Instructions to authors by scientific journals and authors should be encouraged to use the checklist whenever reporting their studies on diagnostic accuracy. Such efforts could make a substantial difference in the quality of reporting of studies of diagnostic accuracy and serve to provide the best possible evidence to the best for the patient care. This brief review outlines some basic definitions and characteristics of the measures of diagnostic accuracy.

  17. Diagnostic test accuracy of D-dimer for acute aortic syndrome: systematic review and meta-analysis of 22 studies with 5000 subjects

    PubMed Central

    Watanabe, Hiroki; Horita, Nobuyuki; Shibata, Yuji; Minegishi, Shintaro; Ota, Erika; Kaneko, Takeshi

    2016-01-01

    Diagnostic test accuracy of D-dimer for acute aortic dissection (AAD) has not been evaluated by meta-analysis with the bivariate model methodology. Four databases were electrically searched. We included both case-control and cohort studies that could provide sufficient data concerning both sensitivity and specificity of D-dimer for AAD. Non-English language articles and conference abstract were allowed. Intramural hematoma and penetrating aortic ulcer were regarded as AAD. Based on 22 eligible articles consisting of 1140 AAD subjects and 3860 non-AAD subjects, the diagnostic odds ratio was 28.5 (95% CI 17.6–46.3, I2 = 17.4%) and the area under curve was 0.946 (95% CI 0.903–0.994). Based on 833 AAD subjects and 1994 non-AAD subjects constituting 12 studies that used the cutoff value of 500 ng/ml, the sensitivity was 0.952 (95% CI 0.901–0.978), the specificity was 0.604 (95% CI 0.485–0.712), positive likelihood ratio was 2.4 (95% CI 1.8–3.3), and negative likelihood ratio was 0.079 (95% CI 0.036–0.172). Sensitivity analysis using data of three high-quality studies almost replicated these results. In conclusion, D-dimer has very good overall accuracy. D-dimer <500 ng/ml largely decreases the possibility of AAD. D-dimer >500 ng/ml moderately increases the possibility of AAD. PMID:27230962

  18. Drawing accuracy measured using polygons

    NASA Astrophysics Data System (ADS)

    Carson, Linda; Millard, Matthew; Quehl, Nadine; Danckert, James

    2013-03-01

    The study of drawing, for its own sake and as a probe into human visual perception, generally depends on ratings by human critics and self-reported expertise of the drawers. To complement those approaches, we have developed a geometric approach to analyzing drawing accuracy, one whose measures are objective, continuous and performance-based. Drawing geometry is represented by polygons formed by landmark points found in the drawing. Drawing accuracy is assessed by comparing the geometric properties of polygons in the drawn image to the equivalent polygon in a ground truth photo. There are four distinct properties of a polygon: its size, its position, its orientation and the proportionality of its shape. We can decompose error into four components and investigate how each contributes to drawing performance. We applied a polygon-based accuracy analysis to a pilot data set of representational drawings and found that an expert drawer outperformed a novice on every dimension of polygon error. The results of the pilot data analysis correspond well with the apparent quality of the drawings, suggesting that the landmark and polygon analysis is a method worthy of further study. Applying this geometric analysis to a within-subjects comparison of accuracy in the positive and negative space suggests there is a trade-off on dimensions of error. The performance-based analysis of geometric deformations will allow the study of drawing accuracy at different levels of organization, in a systematic and quantitative manner. We briefly describe the method and its potential applications to research in drawing education and visual perception.

  19. Investigation of the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection method: a phantom study

    NASA Astrophysics Data System (ADS)

    Abuhadi, Nouf; Bradley, David; Katarey, Dev; Podolyak, Zsolt; Sassi, Salem

    2014-03-01

    Introduction: Single-Photon Emission Computed Tomography (SPECT) is used to measure and quantify radiopharmaceutical distribution within the body. The accuracy of quantification depends on acquisition parameters and reconstruction algorithms. Until recently, most SPECT images were constructed using Filtered Back Projection techniques with no attenuation or scatter corrections. The introduction of 3-D Iterative Reconstruction algorithms with the availability of both computed tomography (CT)-based attenuation correction and scatter correction may provide for more accurate measurement of radiotracer bio-distribution. The effect of attenuation and scatter corrections on accuracy of SPECT measurements is well researched. It has been suggested that the combination of CT-based attenuation correction and scatter correction can allow for more accurate quantification of radiopharmaceutical distribution in SPECT studies (Bushberg et al., 2012). However, The effect of respiratory induced cardiac motion on SPECT images acquired using higher resolution algorithms such 3-D iterative reconstruction with attenuation and scatter corrections has not been investigated. Aims: To investigate the quantitative accuracy of 3D iterative reconstruction algorithms in comparison to filtered back projection (FBP) methods implemented on cardiac SPECT/CT imaging with and without CT-attenuation and scatter corrections. Also to investigate the effects of respiratory induced cardiac motion on myocardium perfusion quantification. Lastly, to present a comparison of spatial resolution for FBP and ordered subset expectation maximization (OSEM) Flash 3D together with and without respiratory induced motion, and with and without attenuation and scatter correction. Methods: This study was performed on a Siemens Symbia T16 SPECT/CT system using clinical acquisition protocols. Respiratory induced cardiac motion was simulated by imaging a cardiac phantom insert whilst moving it using a respiratory motion motor

  20. Accuracy of a direct drill-guiding system with minimal tolerance of surgical instruments used for implant surgery: a prospective clinical study

    PubMed Central

    2016-01-01

    PURPOSE A recently introduced direct drill-guiding implant surgery system features minimal tolerance of surgical instruments in the metal sleeve by using shank-modified drills and a sleeve-incorporated stereolithographic guide template. The purpose of this study was to evaluate the accuracy of this new guided surgery system in partially edentulous patients using geometric analyses. MATERIALS AND METHODS For the study, 21 implants were placed in 11 consecutive patients using the direct drill-guiding implant surgery system. The stereolithographic surgical guide was fabricated using cone-beam computed tomography, digital scanning, computer-aided design and computer-assisted manufacturing, and additive manufacturing processes. After surgery, the positional and angular deviations between planned and placed implants were measured at the abutment level using implant-planning software. The Kruskal-Wallis test and Mann-Whitney U test were used to compare the deviations (α=.05). RESULTS The mean horizontal deviations were 0.593 mm (SD 0.238) mesiodistally and 0.691 mm (SD 0.344) buccolingually. The mean vertical deviation was 0.925 mm (SD 0.376) occlusogingivally. The vertical deviation was significantly larger than the horizontal deviation (P=.018). The mean angular deviation was 2.024 degrees (SD 0.942) mesiodistally and 2.390 degrees (SD 1.142) buccolingually. CONCLUSION The direct drill-guiding implant surgery system demonstrates high accuracy in placing implants. Use of the drill shank as the guiding component is an effective way for reducing tolerance. PMID:27350855

  1. Accuracy of Percutaneous Pedicle Screw Insertion Technique with Conventional Dual Fluoroscopy Units and a Retrospective Comparative Study Based on Surgeon Experience.

    PubMed

    Nakahara, Masayuki; Yasuhara, Takao; Inoue, Takafumi; Takahashi, Yuichi; Kumamoto, Shinji; Hijikata, Yasukazu; Kusumegi, Akira; Sakamoto, Yushi; Ogawa, Koichi; Nishida, Kenki

    2016-06-01

    Study Design Retrospective comparative study. Objective To evaluate the accuracy of percutaneous pedicle screw (PPS) placement and intraoperative imaging time using dual fluoroscopy units and their differences between surgeons with more versus less experience. Methods One hundred sixty-one patients who underwent lumbar fusion surgery were divided into two groups, A (n = 74) and B (n = 87), based on the performing surgeon's experience. The accuracy of PPS placement and radiation time for PPS insertion were compared. PPSs were inserted with classic technique under the assistance of dual fluoroscopy units placed in two planes. The breach definition of PPS misplacement was based on postoperative computed tomography (grade I: no breach; grade II: <2 mm; grade III: ≤2 to <4 mm). Results Of 658 PPSs, only 21 screws were misplaced. The breach rates of groups A and B were 3.3% (grade II: 3.4%, grade III: 0%) and 3.1% (grade II: 2.6%, grade III: 0.6%; p = 0.91). One patient in grade III misplacement had a transient symptom of leg numbness. Median radiation exposure time during PPS insertion was 25 seconds and 51 seconds, respectively (p < 0.01). Conclusions Without using an expensive imaging support system, the classic technique of PPS insertion using dual fluoroscopy units in the lumbar and sacral spine is fairly accurate and provides good clinical outcomes, even among surgeons lacking experience. PMID:27190733

  2. Comparative study of accuracy and clinical agreement of the CoaguChek XS portable device versus standard laboratory practice in unexperienced patients.

    PubMed

    Torreiro, Eduardo G; Fernández, Elizabeth Gómez; Rodríguez, Rosa Mariño; López, Carmen Vázquez; Núñez, Julia Barreal

    2009-05-01

    The objective of the study was to compare the accuracy and clinical agreement of the CoaguChek XS versus the standard laboratory practice. Forty-one patients on long-term anticoagulation with acenocumarol without previous experience in self-monitoring participated to obtain 218 pairs of data. Several methods for comparative statistics were applied to assess the possible disagreements between techniques as well as a range of previously published criteria of clinical agreement and the very recently described error-grid for INR comparison that we partially modify. The mean age was 52.1 and the indications for oral anticoagulation were prosthetic valves (36.59%), atrial fibrillation (34.15%), venous thromboembolic disease (21.95%) and others (7.31%) with a target range of 2-3 INR units (63.4%) or 2.5-3.5 (36.6%). Analyzing the whole series of data, the Pearsons rho correlation coefficient for precision between methods was 0.95 and the C(b) bias correction factor for accuracy 0.99 with a minimal bias of 0.1 INR units between methods applying the Bland-Altman plot. The linear regression procedure described by Passing and Bablok showed a minimal deviation from the best-fit line and a slope of 0.90. The mean of the absolute relative differences was 7% which is in the "very good" range of agreement. No results were found in the clinically "dangerous" D zone of the error-grids with 99% of data in the clinically irrelevant and low relevant areas A and B. In this study self-management with the CoaguChek XS was clinically safe and reliable.

  3. Diagnostic Accuracy of APRI, AAR, FIB-4, FI, and King Scores for Diagnosis of Esophageal Varices in Liver Cirrhosis: A Retrospective Study.

    PubMed

    Deng, Han; Qi, Xingshun; Peng, Ying; Li, Jing; Li, Hongyu; Zhang, Yongguo; Liu, Xu; Sun, Xiaolin; Guo, Xiaozhong

    2015-12-20

    BACKGROUND Aspartate aminotransferase-to-platelet ratio index (APRI), aspartate aminotransferase-to-alanine aminotransferase ratio (AAR), FIB-4, fibrosis index (FI), and King scores might be alternatives to the use of upper gastrointestinal endoscopy for the diagnosis of esophageal varices (EVs) in liver cirrhosis. This study aimed to evaluate their diagnostic accuracy in predicting the presence and severity of EVs in liver cirrhosis. MATERIAL AND METHODS All patients who were consecutively admitted to our hospital and underwent upper gastrointestinal endoscopy between January 2012 and June 2014 were eligible for this retrospective study. Areas under curve (AUCs) were calculated. Subgroup analyses were performed according to the history of upper gastrointestinal bleeding (UGIB) and splenectomy. RESULTS A total of 650 patients with liver cirrhosis were included, and 81.4% of them had moderate-severe EVs. In the overall analysis, the AUCs of these non-invasive scores for predicting moderate-severe EVs and presence of any EVs were 0.506-0.6 and 0.539-0.612, respectively. In the subgroup analysis of patients without UGIB, their AUCs for predicting moderate-severe varices and presence of any EVs were 0.601-0.664 and 0.596-0.662, respectively. In the subgroup analysis of patients without UGIB or splenectomy, their AUCs for predicting moderate-severe varices and presence of any EVs were 0.627-0.69 and 0.607-0.692, respectively. CONCLUSIONS APRI, AAR, FIB-4, FI, and King scores had modest diagnostic accuracy of EVs in liver cirrhosis. They might not be able to replace the utility of upper gastrointestinal endoscopy for the diagnosis of EVs in liver cirrhosis.

  4. The reliability and accuracy of two methods for proximal caries detection and depth on directly visible proximal surfaces: an in vitro study.

    PubMed

    Ekstrand, K R; Luna, L E; Promisiero, L; Cortes, A; Cuevas, S; Reyes, J F; Torres, C E; Martignon, S

    2011-01-01

    This study aimed to determine the reliability and accuracy of the ICDAS and radiographs in detecting and estimating the depth of proximal lesions on extracted teeth. The lesions were visible to the naked eye. Three trained examiners scored a total of 132 sound/carious proximal surfaces from 106 primary teeth and 160 sound/carious proximal surfaces from 140 permanent teeth. The selected surfaces were first scored visually, using the 7 classes in the ICDAS. They were then assessed on radiographs using a 5-point classification system. Reexaminations were conducted with both scoring systems. Teeth were then sectioned and the selected surfaces histologically classified using a stereomicroscope (×5). Intrareproducibility values (weighted kappa statistics) for the ICDAS for both primary and permanent teeth were >0.9, and for the radiographs between 0.6 and 0.8. Interreproducibility values for the ICDAS were >0.85, for the radiographs >0.6. For both primary and permanent teeth, the accuracy of each examiner (Spearman's correlation coefficient) for the ICDAS was ≥0.85, and for the radiographs ≥0.45. Corresponding data were achieved when using pooled data from the 3 examiners for both the ICDAS and the radiographs. The associations between the 2 detection methods were measured to be moderate. In particular, the ICDAS was accurate in predicting lesion depth (histologically) confined to the enamel/outer third of the dentine versus deeper lesions. This study shows that when proximal lesions are open for inspection, the ICDAS is a more reliable and accurate method than the radiograph for detecting and estimating the depth of the lesion in both primary and permanent teeth.

  5. Accuracy of Carbohydrate Counting in Adults.

    PubMed

    Meade, Lisa T; Rushton, Wanda E

    2016-07-01

    In Brief This study investigates carbohydrate counting accuracy in patients using insulin through a multiple daily injection regimen or continuous subcutaneous insulin infusion. The average accuracy test score for all patients was 59%. The carbohydrate test in this study can be used to emphasize the importance of carbohydrate counting to patients and to provide ongoing education. PMID:27621531

  6. High-resolution terrain and landcover mapping with a lightweight, semi-autonomous, remotely-piloted aircraft (RPA): a case study and accuracy assessment

    NASA Astrophysics Data System (ADS)

    Hugenholtz, C.; Whitehead, K.; Moorman, B.; Brown, O.; Hamilton, T.; Barchyn, T.; Riddell, K.; LeClair, A.

    2012-04-01

    Remotely-piloted aircraft (RPA) have evolved into a viable research tool for a range of Earth science applications. Significant technological advances driven by military and surveillance programs have steadily become mainstream and affordable. Thus, RPA technology has the potential to reinvigorate various aspects of geomorphological research, especially at the landform scale. In this presentation we will report results and experiences using a lightweight, semi-autonomous RPA for high-resolution terrain and landcover mapping. The goal was to test the accuracy of the photogrammetrically-derived terrain model and assess the overall performance of the RPA system for landform characterization. The test site was comprised an area of semi-vegetated sand dunes in the Canadian Prairies. The RPA survey was conducted with a RQ-84Z AreoHawk (Hawkeye UAV Ltd) and a low-cost digital camera. During the survey the RPA acquired images semi-autonomously with the aid of proprietary mission planning software developed by Accuas Inc. A total of 44 GCPs were used in the block adjustment to create the terrain model, while an additional 400 independent GPS check points were used for accuracy assessment. The 1 m resolution terrain model developed with Trimble's INPHO photogrammetric software was compared to the independent check points, yielding a RMS error comparable to airborne LiDAR data. The resulting orthophoto mosaic had a resolution of 0.1 m, revealing a number of geomorphic features beyond the resolution of airborne and QuickBird imagery. Overall, this case study highlights the potential of RPA technology for resolving terrain and landcover attributes at the landform scale. We believe one of the most significant and emerging applications of RPA in geomorphology is their potential to quantify rates of landform erosion/deposition in an affordable and flexible manner, allowing investigators to reduce the gap between recorded and natural morphodynamics.

  7. An administrative data validation study of the accuracy of algorithms for identifying rheumatoid arthritis: the influence of the reference standard on algorithm performance

    PubMed Central

    2014-01-01

    Background We have previously validated administrative data algorithms to identify patients with rheumatoid arthritis (RA) using rheumatology clinic records as the reference standard. Here we reassessed the accuracy of the algorithms using primary care records as the reference standard. Methods We performed a retrospective chart abstraction study using a random sample of 7500 adult patients under the care of 83 family physicians contributing to the Electronic Medical Record Administrative data Linked Database (EMRALD) in Ontario, Canada. Using physician-reported diagnoses as the reference standard, we computed and compared the sensitivity, specificity, and predictive values for over 100 administrative data algorithms for RA case ascertainment. Results We identified 69 patients with RA for a lifetime RA prevalence of 0.9%. All algorithms had excellent specificity (>97%). However, sensitivity varied (75-90%) among physician billing algorithms. Despite the low prevalence of RA, most algorithms had adequate positive predictive value (PPV; 51-83%). The algorithm of “[1 hospitalization RA diagnosis code] or [3 physician RA diagnosis codes with ≥1 by a specialist over 2 years]” had a sensitivity of 78% (95% CI 69–88), specificity of 100% (95% CI 100–100), PPV of 78% (95% CI 69–88) and NPV of 100% (95% CI 100–100). Conclusions Administrative data algorithms for detecting RA patients achieved a high degree of accuracy amongst the general population. However, results varied slightly from our previous report, which can be attributed to differences in the reference standards with respect to disease prevalence, spectrum of disease, and type of comparator group. PMID:24956925

  8. Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study

    PubMed Central

    Velthuis, Birgitta K; Rinkel, Gabriël J E; Algra, Ale; de Kort, Gérard A P; Witkamp, Theo D; de Ridder, Johanna C M; van Nieuwenhuizen, Koen M; de Leeuw, Frank-Erik; Schonewille, Wouter J; de Kort, Paul L M; Dippel, Diederik W; Raaymakers, Theodora W M; Hofmeijer, Jeannette; Wermer, Marieke J H; Kerkhoff, Henk; Jellema, Korné; Bronner, Irene M; Remmers, Michel J M; Bienfait, Henri Paul; Witjes, Ron J G M; Greving, Jacoba P; Klijn, Catharina J M

    2015-01-01

    Study question What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? Methods This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MRA was performed four to eight weeks later. DSA was performed when the CT angiography or MRI/MRA results were inconclusive or negative. The main outcome was a macrovascular cause, including arteriovenous malformation, aneurysm, dural arteriovenous fistula, and cavernoma. Three blinded neuroradiologists independently evaluated the images for macrovascular causes of haemorrhage. The reference standard was the best available evidence from all findings during one year’s follow-up. Study answer and limitations A macrovascular cause was identified in 69 patients (23%). 291 patients (98%) underwent CT angiography; 214 with a negative result underwent additional MRI/MRA and 97 with a negative result for both CT angiography and MRI/MRA underwent DSA. Early CT angiography detected 51 macrovascular causes (yield 17%, 95% confidence interval 13% to 22%). CT angiography with MRI/MRA identified two additional macrovascular causes (18%, 14% to 23%) and these modalities combined with DSA another 15 (23%, 18% to 28%). This last extensive strategy failed to detect a cavernoma, which was identified on MRI during follow-up (reference strategy). The positive predictive value of CT angiography was 72% (60% to 82%), of additional MRI/MRA was 35% (14% to 62%), and of additional DSA was 100% (75% to 100%). None of the patients experienced complications with CT angiography or MRI/MRA; 0.6% of patients who underwent DSA experienced permanent sequelae. Not all patients with negative CT angiography and

  9. Scientific Sources' Perception of Network News Accuracy.

    ERIC Educational Resources Information Center

    Moore, Barbara; Singletary, Michael

    Recent polls seem to indicate that many Americans rely on television as a credible and primary source of news. To test the accuracy of this news, a study examined three networks' newscasts of science news, the attitudes of the science sources toward reporting in their field, and the factors related to accuracy. The Vanderbilt News Archives Index…

  10. A Multicenter Prospective Study to Investigate the Diagnostic Accuracy of the SeHCAT Test in Measuring Bile Acid Malabsorption: Research Protocol

    PubMed Central

    Peacock, Janet; Coker, Bola; McMillan, Viktoria; Lewis, Cornelius; Keevil, Stephen; Sherwood, Roy; Vivian, Gill; Logan, Robert; Summers, Jennifer

    2016-01-01

    Background Bile acid malabsorption (BAM) is one possible explanation for chronic diarrhea. BAM may be idiopathic, or result from ileal resection or inflammation including Crohn’s disease, or may be secondary to other conditions, including cholecystectomy, peptic ulcer surgery, and chronic pancreatitis. No “gold standard” exists for clinical diagnosis of BAM, but response to treatment with a bile acid sequestrant (BAS) is often accepted as confirmation. The SeHCAT (tauroselcholic [selenium-75] acid) test uses a radiolabeled synthetic bile acid and provides a diagnostic test for BAM, but its performance against “trial of treatment” is unknown. Fibroblast growth factor 19 (FGF-19) and 7-alpha-hydroxy-4-cholesten-3-one (C4) also offer potential new biomarkers of BAM. Objective This protocol describes a multicenter prospective study to evaluate the diagnostic accuracy of SeHCAT and 2 biomarkers in predicting BAM as assessed by trial of treatment. Methods Participating gastroenterology centers should have a minimum workload of 30 SeHCAT patients per annum. Patients should not be pregnant, on medication that could confound follow-up, or have any severe comorbidity. All eligible patients attending a gastrointestinal appointment will be invited to participate. On attending the SeHCAT test, blood and fecal samples will be collected for analysis of FGF-19 by enzyme-linked immunosorbent assay and for C4 and fractionated bile acids by liquid chromatography–mass spectrometry. A capsule containing radiolabeled SeHCAT will be administered orally and a scan performed to measure SeHCAT activity. Patients will return on day 7 to undergo a second scan to measure percentage SeHCAT retention. The test result will be concealed from clinicians and patients. BAS will be dispensed to all patients, with a follow-up gastroenterologist appointment at 2 weeks for clinical assessment of treatment response and adherence. Patients responding positively will continue treatment for a

  11. Municipal water consumption forecast accuracy

    NASA Astrophysics Data System (ADS)

    Fullerton, Thomas M.; Molina, Angel L.

    2010-06-01

    Municipal water consumption planning is an active area of research because of infrastructure construction and maintenance costs, supply constraints, and water quality assurance. In spite of that, relatively few water forecast accuracy assessments have been completed to date, although some internal documentation may exist as part of the proprietary "grey literature." This study utilizes a data set of previously published municipal consumption forecasts to partially fill that gap in the empirical water economics literature. Previously published municipal water econometric forecasts for three public utilities are examined for predictive accuracy against two random walk benchmarks commonly used in regional analyses. Descriptive metrics used to quantify forecast accuracy include root-mean-square error and Theil inequality statistics. Formal statistical assessments are completed using four-pronged error differential regression F tests. Similar to studies for other metropolitan econometric forecasts in areas with similar demographic and labor market characteristics, model predictive performances for the municipal water aggregates in this effort are mixed for each of the municipalities included in the sample. Given the competitiveness of the benchmarks, analysts should employ care when utilizing econometric forecasts of municipal water consumption for planning purposes, comparing them to recent historical observations and trends to insure reliability. Comparative results using data from other markets, including regions facing differing labor and demographic conditions, would also be helpful.

  12. Spacecraft attitude determination accuracy from mission experience

    NASA Technical Reports Server (NTRS)

    Brasoveanu, D.; Hashmall, J.

    1994-01-01

    This paper summarizes a compilation of attitude determination accuracies attained by a number of satellites supported by the Goddard Space Flight Center Flight Dynamics Facility. The compilation is designed to assist future mission planners in choosing and placing attitude hardware and selecting the attitude determination algorithms needed to achieve given accuracy requirements. The major goal of the compilation is to indicate realistic accuracies achievable using a given sensor complement based on mission experience. It is expected that the use of actual spacecraft experience will make the study especially useful for mission design. A general description of factors influencing spacecraft attitude accuracy is presented. These factors include determination algorithms, inertial reference unit characteristics, and error sources that can affect measurement accuracy. Possible techniques for mitigating errors are also included. Brief mission descriptions are presented with the attitude accuracies attained, grouped by the sensor pairs used in attitude determination. The accuracies for inactive missions represent a compendium of missions report results, and those for active missions represent measurements of attitude residuals. Both three-axis and spin stabilized missions are included. Special emphasis is given to high-accuracy sensor pairs, such as two fixed-head star trackers (FHST's) and fine Sun sensor plus FHST. Brief descriptions of sensor design and mode of operation are included. Also included are brief mission descriptions and plots summarizing the attitude accuracy attained using various sensor complements.

  13. Intelligence: The Speed and Accuracy Tradeoff in High Aptitude Individuals.

    ERIC Educational Resources Information Center

    Lajoie, Suzanne P.; Shore, Bruce M.

    1986-01-01

    The relative contributions of mental speed and accuracy to Primary Mental Ability (PMA) IQ prediction were studied in 52 high ability grade 10 students. Both speed and accuracy independently predicted IQ, but not speed over and above accuracy. Accuracy was demonstrated to be universally advantageous in IQ performance, but speed varied according to…

  14. Evaluation of accuracy of casts of multiple internal connection implant prosthesis obtained from different impression materials and techniques: an in vitro study.

    PubMed

    Pujari, Malesh; Garg, Pooja; Prithviraj, D R

    2014-04-01

    Movement of impression copings inside the impression material using a direct (open tray) impression technique during clinical and laboratory phases may cause inaccuracy in transferring the 3-dimensional spatial orientation of implants intraorally to the cast. Consequently, the prosthesis may require corrective procedures. This in vitro study evaluated the accuracy of 3 different impression techniques using polyether and vinyl polysiloxane (VPS) impression material to obtain a precise cast for multiple internal connection implants. A reference acrylic resin model with 4 internal connection implants was fabricated. Impressions of the reference model were made using 3 different techniques and 2 different impression materials. The study consisted of 24 specimens divided into 6 groups of 4 each. Impressions were poured with ADA type IV stone (Kalrock, Kalabhai Karson Pvt Ltd, Mumbai, India). All casts were evaluated for the positional accuracy (mm) of the implant replica heads using a profile projector. These measurements were compared to the measurements calculated on the reference resin model, which served as a control. Data were analyzed with 2-way analysis of variance (ANOVA) followed by Bonferroni multiple comparison procedures to evaluate group means. The results revealed significant difference for anterior implant distance between the 2 impression materials (P < .01) and also among the 3 different techniques (P < .05). The lowest mean variation was found with the polyether impression material and the splinted technique. For posterior implants, the results suggested no significant difference between the 2 impression materials (P ≥ .05). Although results were not statistically significant, the polyether impression material showed the lowest mean variation as compared to the VPS impression material. However, there was a significant difference among the 3 different techniques (P < .05). Among the 3 different techniques, the lowest mean variation between 2 posterior

  15. Diagnostic accuracy of a point-of-care urine test for tuberculosis screening among newly-diagnosed hiv-infected adults: a prospective, clinic-based study

    PubMed Central

    2014-01-01

    Background A rapid diagnostic test for active tuberculosis (TB) at the clinical point-of-care could expedite case detection and accelerate TB treatment initiation. We assessed the diagnostic accuracy of a rapid urine lipoarabinomannan (LAM) test for TB screening among HIV-infected adults in a TB-endemic setting. Methods We prospectively enrolled newly-diagnosed HIV-infected adults (≥18 years) at 4 outpatient clinics in Durban from Oct 2011-May 2012, excluding those on TB therapy. A physician evaluated all participants and offered CD4 cell count testing. Trained study nurses collected a sputum sample for acid-fast bacilli smear microscopy (AFB) and mycobacterial culture, and performed urine LAM testing using Determine™ TB LAM in the clinic. The presence of a band regardless of intensity on the urine LAM test was considered positive. We defined as the gold standard for active pulmonary TB a positive sputum culture for Mycobacterium tuberculosis. Diagnostic accuracy of urine LAM was assessed, alone and in combination with smear microscopy, and stratified by CD4 cell count. Results Among 342 newly-diagnosed HIV-infected participants, 190 (56%) were male, mean age was 35.6 years, and median CD4 was 182/mm3. Sixty participants had culture-positive pulmonary TB, resulting in an estimated prevalence of 17.5% (95% CI 13.7-22.0%). Forty-five (13.2%) participants were urine LAM positive. Mean time from urine specimen collection to LAM test result was 40 minutes (95% CI 34–46 minutes). Urine LAM test sensitivity was 28.3% (95% CI 17.5-41.4) overall, and 37.5% (95% CI 21.1-56.3) for those with CD4 count <100/mm3, while specificity was 90.1% (95% CI 86.0-93.3) overall, and 86.9% (95% CI 75.8-94.2) for those with CD4 < 100/mm3. When combined with sputum AFB (either test positive), sensitivity increased to 38.3% (95% CI 26.0-51.8), but specificity decreased to 85.8% (95% CI 81.1-89.7). Conclusions In this prospective, clinic-based study with trained nurses, a rapid

  16. High accuracy OMEGA timekeeping

    NASA Technical Reports Server (NTRS)

    Imbier, E. A.

    1982-01-01

    The Smithsonian Astrophysical Observatory (SAO) operates a worldwide satellite tracking network which uses a combination of OMEGA as a frequency reference, dual timing channels, and portable clock comparisons to maintain accurate epoch time. Propagational charts from the U.S. Coast Guard OMEGA monitor program minimize diurnal and seasonal effects. Daily phase value publications of the U.S. Naval Observatory provide corrections to the field collected timing data to produce an averaged time line comprised of straight line segments called a time history file (station clock minus UTC). Depending upon clock location, reduced time data accuracies of between two and eight microseconds are typical.

  17. Dose reduction and its influence on diagnostic accuracy and radiation risk in digital mammography: an observer performance study using an anthropomorphic breast phantom

    PubMed Central

    Svahn, Tony; Hemdal, Bengt; Ruschin, Mark; Chakraborty, Dev P; Andersson, Ingvar; Tingberg, Anders; Mattsson, Sören

    2008-01-01

    This study aimed to investigate the effect of dose reduction on diagnostic accuracy and radiation risk in digital mammography. Simulated masses and microcalcifications were positioned in an anthropomorphic breast phantom. Thirty digital images, 14 with lesions, 16 without, were acquired of the phantom using a Mammomat Novation (Siemens, Erlangen, Germany) at each of three dose levels. These corresponded to 100%, 50% and 30% of the normally used average glandular dose (AGD; 1.3 mGy for a standard breast). Eight observers interpreted the 90 unprocessed images in a free-response study and the data was analyzed with the jackknife free-response receiver operating characteristic (JAFROC) method. Observer performance was assessed using the JAFROC figure of merit (FOM). The benefit of radiation risk reduction was estimated based on several risk models. There was no statistically significant difference in performance, as described by the FOM, between the 100% and the 50% dose levels. However, the FOMs for both the 100% and the 50% dose were significantly different from the corresponding quantity for the 30% dose level (F-statistic = 4.95, p-value = 0.01). A dose reduction of 50% would result in 3-9 fewer breast cancer fatalities per 100,000 women undergoing annual screening from the age of 40 to 49 years. The results of the study indicate a possibility of reducing the dose to the breast to half of the dose level currently used. This has to be confirmed in clinical studies and possible differences depending on lesion type should be further examined. PMID:17704316

  18. The impacts of thyroid function on the diagnostic accuracy of Cystatin C to detect acute kidney injury in ICU patients: a prospective, observational study

    PubMed Central

    2014-01-01

    Introduction Cystatin C (Cysc) could be affected by thyroid function both in vivo and in vitro and thereby may have limited ability to reflect renal function. We aimed to assess the association between Cysc and thyroid hormones as well as the effect of thyroid function on the diagnostic accuracy of Cysc to detect acute kidney injury (AKI). Methods A total of 446 consecutive intensive care unit (ICU) patients were screened for eligibility in this prospective AKI observational study. Serum Cysc, thyroid hormones and serum creatinine (Scr) were measured upon entry to the ICU. We also collected each patient's baseline characteristics including the Acute Physiology and Chronic Health Evaluation II (APACHE-II) score. The diagnostic performance of Cysc was assessed from the area under the receiver operator characteristic curve (AUC) in each quartile of thyroid hormone(s). Results A total of 114 (25.6%) patients had a clinical diagnosis of AKI upon entry to the ICU. The range of free thyroxine (FT4) value was 4.77 to 39.57 pmol/L. Multivariate linear regression showed that age (standardized beta = 0.128, P < 0.0001), baseline Scr level (standardized beta = 0.290, P < 0.0001), current Scr (standardized beta = 0.453, P < 0.0001), albumin (standardized beta = -0.086, P = 0.006), and FT4 (standardized beta = 0.062, P = 0.039) were related with Cysc. Patients were divided into four quartiles based on FT4 levels. The AUC for Cysc in detecting AKI in each quartile were as follows: 0.712 in quartile I, 0.754 in quartile II, 0.829 in quartile III and 0.797 in quartile IV. There was no significant difference in the AUC between any two groups (all P > 0.05). The optimal cut-off value of Cysc for diagnosing AKI increased across FT4 quartiles (1.15 mg/L in quartile I, 1.15 mg/L in quartile II, 1.35 mg/L in quartile III and 1.45 mg/L in quartile IV). Conclusions There was no significant impact of thyroid function on the diagnostic accuracy

  19. Fit accuracy of metal partial removable dental prosthesis frameworks fabricated by traditional or light curing modeling material technique: An in vitro study

    PubMed Central

    Anan, Mohammad Tarek M.; Al-Saadi, Mohannad H.

    2015-01-01

    Objective The aim of this study was to compare the fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks fabricated by the traditional technique (TT) or the light-curing modeling material technique (LCMT). Materials and methods A metal model of a Kennedy class III modification 1 mandibular dental arch with two edentulous spaces of different spans, short and long, was used for the study. Thirty identical working casts were used to produce 15 PRDP frameworks each by TT and by LCMT. Every framework was transferred to a metal master cast to measure the gap between the metal base of the framework and the crest of the alveolar ridge of the cast. Gaps were measured at three points on each side by a USB digital intraoral camera at ×16.5 magnification. Images were transferred to a graphics editing program. A single examiner performed all measurements. The two-tailed t-test was performed at the 5% significance level. Results The mean gap value was significantly smaller in the LCMT group compared to the TT group. The mean value of the short edentulous span was significantly smaller than that of the long edentulous span in the LCMT group, whereas the opposite result was obtained in the TT group. Conclusion Within the limitations of this study, it can be concluded that the fit of the LCMT-fabricated frameworks was better than the fit of the TT-fabricated frameworks. The framework fit can differ according to the span of the edentate ridge and the fabrication technique for the metal framework. PMID:26236129

  20. Significant Improvement of Puncture Accuracy and Fluoroscopy Reduction in Percutaneous Transforaminal Endoscopic Discectomy With Novel Lumbar Location System: Preliminary Report of Prospective Hello Study.

    PubMed

    Fan, Guoxin; Guan, Xiaofei; Zhang, Hailong; Wu, Xinbo; Gu, Xin; Gu, Guangfei; Fan, Yunshan; He, Shisheng

    2015-12-01

    Prospective nonrandomized control study.The study aimed to investigate the implication of the HE's Lumbar LOcation (HELLO) system in improving the puncture accuracy and reducing fluoroscopy in percutaneous transforaminal endoscopic discectomy (PTED).Percutaneous transforaminal endoscopic discectomy is one of the most popular minimally invasive spine surgeries that heavily depend on repeated fluoroscopy. Increased fluoroscopy will induce higher radiation exposure to surgeons and patients. Accurate puncture in PTED can be achieved by accurate preoperative location and definite trajectory.The HELLO system mainly consists of self-made surface locator and puncture-assisted device. The surface locator was used to identify the exact puncture target and the puncture-assisted device was used to optimize the puncture trajectory. Patients who had single L4/5 or L5/S1 lumbar intervertebral disc herniation and underwent PTED were included the study. Patients receiving the HELLO system were assigned in Group A, and those taking conventional method were assigned in Group B. Study primary endpoint was puncture times and fluoroscopic times, and the secondary endpoint was location time and operation time.A total of 62 patients who received PTED were included in this study. The average age was 45.35 ± 8.70 years in Group A and 46.61 ± 7.84 years in Group B (P = 0.552). There were no significant differences in gender, body mass index, conservative time, and surgical segment between the 2 groups (P > 0.05). The puncture times were 1.19 ± 0.48 in Group A and 6.03 ± 1.87 in Group B (P < 0.001). The fluoroscopic times were 14.03 ± 2.54 in Group A and 25.19 ± 4.28 in Group B (P < 0.001). The preoperative location time was 4.67 ± 1.41 minutes in Group A and 6.98 ± 0.94 minutes in Group B (P < 0.001). The operation time was 79.42 ± 10.15 minutes in Group A and 89.65 ± 14.06 minutes in Group B (P = 0.002). The

  1. Significant Improvement of Puncture Accuracy and Fluoroscopy Reduction in Percutaneous Transforaminal Endoscopic Discectomy With Novel Lumbar Location System: Preliminary Report of Prospective Hello Study.

    PubMed

    Fan, Guoxin; Guan, Xiaofei; Zhang, Hailong; Wu, Xinbo; Gu, Xin; Gu, Guangfei; Fan, Yunshan; He, Shisheng

    2015-12-01

    Prospective nonrandomized control study.The study aimed to investigate the implication of the HE's Lumbar LOcation (HELLO) system in improving the puncture accuracy and reducing fluoroscopy in percutaneous transforaminal endoscopic discectomy (PTED).Percutaneous transforaminal endoscopic discectomy is one of the most popular minimally invasive spine surgeries that heavily depend on repeated fluoroscopy. Increased fluoroscopy will induce higher radiation exposure to surgeons and patients. Accurate puncture in PTED can be achieved by accurate preoperative location and definite trajectory.The HELLO system mainly consists of self-made surface locator and puncture-assisted device. The surface locator was used to identify the exact puncture target and the puncture-assisted device was used to optimize the puncture trajectory. Patients who had single L4/5 or L5/S1 lumbar intervertebral disc herniation and underwent PTED were included the study. Patients receiving the HELLO system were assigned in Group A, and those taking conventional method were assigned in Group B. Study primary endpoint was puncture times and fluoroscopic times, and the secondary endpoint was location time and operation time.A total of 62 patients who received PTED were included in this study. The average age was 45.35 ± 8.70 years in Group A and 46.61 ± 7.84 years in Group B (P = 0.552). There were no significant differences in gender, body mass index, conservative time, and surgical segment between the 2 groups (P > 0.05). The puncture times were 1.19 ± 0.48 in Group A and 6.03 ± 1.87 in Group B (P < 0.001). The fluoroscopic times were 14.03 ± 2.54 in Group A and 25.19 ± 4.28 in Group B (P < 0.001). The preoperative location time was 4.67 ± 1.41 minutes in Group A and 6.98 ± 0.94 minutes in Group B (P < 0.001). The operation time was 79.42 ± 10.15 minutes in Group A and 89.65 ± 14.06 minutes in Group B (P = 0.002). The

  2. Combining pseudo dinucleotide composition with the Z curve method to improve the accuracy of predicting DNA elements: a case study in recombination spots.

    PubMed

    Dong, Chuan; Yuan, Ya-Zhou; Zhang, Fa-Zhan; Hua, Hong-Li; Ye, Yuan-Nong; Labena, Abraham Alemayehu; Lin, Hao; Chen, Wei; Guo, Feng-Biao

    2016-08-16

    Pseudo dinucleotide composition (PseDNC) and Z curve showed excellent performance in the classification issues of nucleotide sequences in bioinformatics. Inspired by the principle of Z curve theory, we improved PseDNC to give the phase-specific PseDNC (psPseDNC). In this study, we used the prediction of recombination spots as a case to illustrate the capability of psPseDNC and also PseDNC fused with Z curve theory based on a novel machine learning method named large margin distribution machine (LDM). We verified that combining the two widely used approaches could generate better performance compared to only using PseDNC with a support vector machine based (SVM-based) model. The best Mathew's correlation coefficient (MCC) achieved by our LDM-based model was 0.7037 through the rigorous jackknife test and improved by ∼6.6%, ∼3.2%, and ∼2.4% compared with three previous studies. Similarly, the accuracy was improved by 3.2% compared with our previous iRSpot-PseDNC web server through an independent data test. These results demonstrate that the joint use of PseDNC and Z curve enhances performance and can extract more information from a biological sequence. To facilitate research in this area, we constructed a user-friendly web server for predicting hot/cold spots, HcsPredictor, which can be freely accessed from . In summary, we provided a united algorithm by integrating Z curve with PseDNC. We hope this united algorithm could be extended to other classification issues in DNA elements.

  3. Combining pseudo dinucleotide composition with the Z curve method to improve the accuracy of predicting DNA elements: a case study in recombination spots.

    PubMed

    Dong, Chuan; Yuan, Ya-Zhou; Zhang, Fa-Zhan; Hua, Hong-Li; Ye, Yuan-Nong; Labena, Abraham Alemayehu; Lin, Hao; Chen, Wei; Guo, Feng-Biao

    2016-08-16

    Pseudo dinucleotide composition (PseDNC) and Z curve showed excellent performance in the classification issues of nucleotide sequences in bioinformatics. Inspired by the principle of Z curve theory, we improved PseDNC to give the phase-specific PseDNC (psPseDNC). In this study, we used the prediction of recombination spots as a case to illustrate the capability of psPseDNC and also PseDNC fused with Z curve theory based on a novel machine learning method named large margin distribution machine (LDM). We verified that combining the two widely used approaches could generate better performance compared to only using PseDNC with a support vector machine based (SVM-based) model. The best Mathew's correlation coefficient (MCC) achieved by our LDM-based model was 0.7037 through the rigorous jackknife test and improved by ∼6.6%, ∼3.2%, and ∼2.4% compared with three previous studies. Similarly, the accuracy was improved by 3.2% compared with our previous iRSpot-PseDNC web server through an independent data test. These results demonstrate that the joint use of PseDNC and Z curve enhances performance and can extract more information from a biological sequence. To facilitate research in this area, we constructed a user-friendly web server for predicting hot/cold spots, HcsPredictor, which can be freely accessed from . In summary, we provided a united algorithm by integrating Z curve with PseDNC. We hope this united algorithm could be extended to other classification issues in DNA elements. PMID:27410247

  4. A comparative study of accuracy of linear measurements using cone beam and multi-slice computed tomographies for evaluation of mandibular canal location in dry mandibles

    PubMed Central

    Naser, Asieh Zamani; Mehr, Bahar Behdad

    2013-01-01

    Background: Cross- sectional tomograms have been used for optimal pre-operative planning of dental implant placement. The aim of the present study was to assess the accuracy of Cone Beam Computed Tomography (CBCT) measurements of specific distances around the mandibular canal by comparing them to those obtained from Multi-Slice Computed Tomography (MSCT) images. Materials and Methods: Ten hemi-mandible specimens were examined using CBCT and MSCT. Before imaging, wires were placed at 7 locations between the anterior margin of the third molar and the anterior margin of the second premolar as reference points. Following distances were measured by two observers on each cross-sectional CBCT and MSCT image: Mandibular Width (W), Length (L), Upper Distance (UD), Lower Distance (LD), Buccal Distance (BD), and Lingual Distance (LID). The obtained data were evaluated using SPSS software, applying paired t-test and intra-class correlation coefficient (ICC). Results: There was a significant difference between the values obtained by MSCT and CBCT measurement for all areas such as H, W, UD, LD, BD, and LID, (P < 0.001), with a difference less than 1 mm. The ICC for all distances by both techniques, measured by a single observer with a one week interval and between 2 observers was 99% and 98%, respectively. Comparing the obtained data of both techniques indicates that the difference between two techniques is 2.17% relative to MSCT. Conclusion: The results of this study showed that there is significant difference between measurements obtained by CBCT and MSCT. However, the difference is not clinically significant. PMID:23878558

  5. An evaluation of dimensional accuracy of one-step and two-step impression technique using addition silicone impression material: an in vitro study.

    PubMed

    Pande, Neelam A; Parkhedkar, R D

    2013-09-01

    The study is aimed to evaluate the dimensional accuracy, the effect of undercut of two different configurations and the elastic recovery of addition silicone impression material assessed indirectly, by measuring the dimensions on stone models recorded from the impression of the master model, using one-step and two-step impression technique, for addition silicone impression materials. Measurements are taken to evaluate horizontal or linear and vertical dimensional changes, of the abutment V and abutment C from the stainless steel model. Heavy body/light body material is used for making one-step impression technique in a custom tray. Putty/light body is used for taking two-step technique in a stock metal tray. Improved die stone is used for pouring the impression. The different 11 locations on the dies produced by two different techniques are measured microscopically on image analyzer and compared with those of stainless steel model. Anova test was applied to test the differences of mean values of inter and intra abutment measurements, to calculate p value. Unpaired t test was applied to calculate t value. Results showed less deviation of stone models produced by one-step technique from stainless steel model, whereas the deviation of stone models produced by two-step is comparatively more. (p < 0.01). This difference of deviation is significantly less in one-step as compared to two-step technique. One-step is sufficiently dimensionally accurate than two-step technique in conjunction with addition silicone impression material. They have the best elastic recovery from the two undercut configurations.

  6. Accuracy assessment of a marker-free method for registration of CT and stereo images applied in image-guided implantology: a phantom study.

    PubMed

    Mohagheghi, Saeed; Ahmadian, Alireza; Yaghoobee, Siamak

    2014-12-01

    To assess the accuracy of a proposed marker-free registration method as opposed to the conventional marker-based method using an image-guided dental system, and investigating the best configurations of anatomical landmarks for various surgical fields in a phantom study, a CT-compatible dental phantom consisting of implanted targets was used. Two marker-free registration methods were evaluated, first using dental anatomical landmarks and second, using a reference marker tool. Six implanted markers, distributed in the inner space of the phantom were used as the targets; the values of target registration error (TRE) for each target were measured and compared with the marker-based method. Then, the effects of different landmark configurations on TRE values, measured using the Parsiss IV Guided Navigation system (Parsiss, Tehran, Iran), were investigated to find the best landmark arrangement for reaching the minimum registration error in each target region. It was proved that marker-free registration can be as precise as the marker-based method. This has a great impact on image-guided implantology systems whereby the drawbacks of fiducial markers for patient and surgeon are removed. It was also shown that smaller values of TRE could be achieved by using appropriate landmark configurations and moving the center of the landmark set closer to the surgery target. Other common factors would not necessarily decrease the TRE value so the conventional rules accepted in the clinical community about the ways to reduce TRE should be adapted to the selected field of dental surgery.

  7. Measuring Diagnoses: ICD Code Accuracy

    PubMed Central

    O'Malley, Kimberly J; Cook, Karon F; Price, Matt D; Wildes, Kimberly Raiford; Hurdle, John F; Ashton, Carol M

    2005-01-01

    Objective To examine potential sources of errors at each step of the described inpatient International Classification of Diseases (ICD) coding process. Data Sources/Study Setting The use of disease codes from the ICD has expanded from classifying morbidity and mortality information for statistical purposes to diverse sets of applications in research, health care policy, and health care finance. By describing a brief history of ICD coding, detailing the process for assigning codes, identifying where errors can be introduced into the process, and reviewing methods for examining code accuracy, we help code users more systematically evaluate code accuracy for their particular applications. Study Design/Methods We summarize the inpatient ICD diagnostic coding process from patient admission to diagnostic code assignment. We examine potential sources of errors at each step and offer code users a tool for systematically evaluating code accuracy. Principle Findings Main error sources along the “patient trajectory” include amount and quality of information at admission, communication among patients and providers, the clinician's knowledge and experience with the illness, and the clinician's attention to detail. Main error sources along the “paper trail” include variance in the electronic and written records, coder training and experience, facility quality-control efforts, and unintentional and intentional coder errors, such as misspecification, unbundling, and upcoding. Conclusions By clearly specifying the code assignment process and heightening their awareness of potential error sources, code users can better evaluate the applicability and limitations of codes for their particular situations. ICD codes can then be used in the most appropriate ways. PMID:16178999

  8. The Accuracy of IOS Device-based uHear as a Screening Tool for Hearing Loss: A Preliminary Study From the Middle East

    PubMed Central

    Al-Abri, Rashid; Al-Balushi, Mustafa; Kolethekkat, Arif; Bhargava, Deepa; Al-Alwi, Amna; Al-Bahlani, Hana; Al-Garadi, Manal

    2016-01-01

    Objectives To determine and explore the potential use of uHear as a screening test for determining hearing disability by evaluating its accuracy in a clinical setting and a soundproof booth when compared to the gold standard conventional audiometry.   Methods Seventy Sultan Qaboos University students above the age of 17 years who had normal hearing were recruited for the study. They underwent a hearing test using conventional audiometry in a soundproof room, a self-administered uHear evaluation in a side room resembling a clinic setting, and a self-administered uHear test in a soundproof booth. The mean pure tone average (PTA) of thresholds at 500, 1000, 2000 and 4000 Hz for all the three test modalities was calculated, compared, and analyzed statistically.   Results There were 36 male and 34 female students in the study. The PTA with conventional audiometry ranged from 1 to 21 dB across left and right ears. The PTA using uHear in the side room for the same participants was 25 dB in the right ear and 28 dB in the left ear (3–54 dB across all ears). The PTA for uHear in the soundproof booth was 18 dB and 17 dB (1–43 dB) in the right and left ears, respectively. Twenty-three percent of participants were reported to have a mild hearing impairment (PTA > 25 dB) using the soundproof uHear test, and this number was 64% for the same test in the side room. For the same group, only 3% of participants were reported to have a moderate hearing impairment (PTA > 40 dB) using the uHear test in a soundproof booth, and 13% in the side room.   Conclusion uHear in any setting lacks specificity in the range of normal hearing and is highly unreliable in giving the exact hearing threshold in clinical settings. However, there is a potential for the use of uHear if it is used to rule out moderate hearing loss, even in a clinical setting, as exemplified by our study. This method needs standardization through further research. PMID:27168926

  9. Reticence, Accuracy and Efficacy

    NASA Astrophysics Data System (ADS)

    Oreskes, N.; Lewandowsky, S.

    2015-12-01

    James Hansen has cautioned the scientific community against "reticence," by which he means a reluctance to speak in public about the threat of climate change. This may contribute to social inaction, with the result that society fails to respond appropriately to threats that are well understood scientifically. Against this, others have warned against the dangers of "crying wolf," suggesting that reticence protects scientific credibility. We argue that both these positions are missing an important point: that reticence is not only a matter of style but also of substance. In previous work, Bysse et al. (2013) showed that scientific projections of key indicators of climate change have been skewed towards the low end of actual events, suggesting a bias in scientific work. More recently, we have shown that scientific efforts to be responsive to contrarian challenges have led scientists to adopt the terminology of a "pause" or "hiatus" in climate warming, despite the lack of evidence to support such a conclusion (Lewandowsky et al., 2015a. 2015b). In the former case, scientific conservatism has led to under-estimation of climate related changes. In the latter case, the use of misleading terminology has perpetuated scientific misunderstanding and hindered effective communication. Scientific communication should embody two equally important goals: 1) accuracy in communicating scientific information and 2) efficacy in expressing what that information means. Scientists should strive to be neither conservative nor adventurous but to be accurate, and to communicate that accurate information effectively.

  10. Discrimination in measures of knowledge monitoring accuracy

    PubMed Central

    Was, Christopher A.

    2014-01-01

    Knowledge monitoring predicts academic outcomes in many contexts. However, measures of knowledge monitoring accuracy are often incomplete. In the current study, a measure of students’ ability to discriminate known from unknown information as a component of knowledge monitoring was considered. Undergraduate students’ knowledge monitoring accuracy was assessed and used to predict final exam scores in a specific course. It was found that gamma, a measure commonly used as the measure of knowledge monitoring accuracy, accounted for a small, but significant amount of variance in academic performance whereas the discrimination and bias indexes combined to account for a greater amount of variance in academic performance. PMID:25339979

  11. Accuracy and consistency of modern elastomeric pumps.

    PubMed

    Weisman, Robyn S; Missair, Andres; Pham, Phung; Gutierrez, Juan F; Gebhard, Ralf E

    2014-01-01

    Continuous peripheral nerve blockade has become a popular method of achieving postoperative analgesia for many surgical procedures. The safety and reliability of infusion pumps are dependent on their flow rate accuracy and consistency. Knowledge of pump rate profiles can help physicians determine which infusion pump is best suited for their clinical applications and specific patient population. Several studies have investigated the accuracy of portable infusion pumps. Using methodology similar to that used by Ilfeld et al, we investigated the accuracy and consistency of several current elastomeric pumps. PMID:25140510

  12. High-accuracy EUV reflectometer

    NASA Astrophysics Data System (ADS)

    Hinze, U.; Fokoua, M.; Chichkov, B.

    2007-03-01

    Developers and users of EUV-optics need precise tools for the characterization of their products. Often a measurement accuracy of 0.1% or better is desired to detect and study slow-acting aging effect or degradation by organic contaminants. To achieve a measurement accuracy of 0.1% an EUV-source is required which provides an excellent long-time stability, namely power stability, spatial stability and spectral stability. Naturally, it should be free of debris. An EUV-source particularly suitable for this task is an advanced electron-based EUV-tube. This EUV source provides an output of up to 300 μW at 13.5 nm. Reflectometers benefit from the excellent long-time stability of this tool. We design and set up different reflectometers using EUV-tubes for the precise characterisation of EUV-optics, such as debris samples, filters, multilayer mirrors, grazing incidence optics, collectors and masks. Reflectivity measurements from grazing incidence to near normal incidence as well as transmission studies were realised at a precision of down to 0.1%. The reflectometers are computer-controlled and allow varying and scanning all important parameters online. The concepts of a sample reflectometer is discussed and results are presented. The devices can be purchased from the Laser Zentrum Hannover e.V.

  13. Validity of ICD-9-CM codes for breast, lung and colorectal cancers in three Italian administrative healthcare databases: a diagnostic accuracy study protocol

    PubMed Central

    Abraha, Iosief; Serraino, Diego; Giovannini, Gianni; Stracci, Fabrizio; Casucci, Paola; Alessandrini, Giuliana; Bidoli, Ettore; Chiari, Rita; Cirocchi, Roberto; De Giorgi, Marcello; Franchini, David; Vitale, Maria Francesca; Fusco, Mario; Montedori, Alessandro

    2016-01-01

    Introduction Administrative healthcare databases are useful tools to study healthcare outcomes and to monitor the health status of a population. Patients with cancer can be identified through disease-specific codes, prescriptions and physician claims, but prior validation is required to achieve an accurate case definition. The objective of this protocol is to assess the accuracy of International Classification of Diseases Ninth Revision—Clinical Modification (ICD-9-CM) codes for breast, lung and colorectal cancers in identifying patients diagnosed with the relative disease in three Italian administrative databases. Methods and analysis Data from the administrative databases of Umbria Region (910 000 residents), Local Health Unit 3 of Napoli (1 170 000 residents) and Friuli-Venezia Giulia Region (1 227 000 residents) will be considered. In each administrative database, patients with the first occurrence of diagnosis of breast, lung or colorectal cancer between 2012 and 2014 will be identified using the following groups of ICD-9-CM codes in primary position: (1) 233.0 and (2) 174.x for breast cancer; (3) 162.x for lung cancer; (4) 153.x for colon cancer and (5) 154.0–154.1 and 154.8 for rectal cancer. Only incident cases will be considered, that is, excluding cases that have the same diagnosis in the 5 years (2007–2011) before the period of interest. A random sample of cases and non-cases will be selected from each administrative database and the corresponding medical charts will be assessed for validation by pairs of trained, independent reviewers. Case ascertainment within the medical charts will be based on (1) the presence of a primary nodular lesion in the breast, lung or colon–rectum, documented with imaging or endoscopy and (2) a cytological or histological documentation of cancer from a primary or metastatic site. Sensitivity and specificity with 95% CIs will be calculated. Dissemination Study results will be disseminated widely through

  14. Accuracy and precision of manual baseline determination.

    PubMed

    Jirasek, A; Schulze, G; Yu, M M L; Blades, M W; Turner, R F B

    2004-12-01

    Vibrational spectra often require baseline removal before further data analysis can be performed. Manual (i.e., user) baseline determination and removal is a common technique used to perform this operation. Currently, little data exists that details the accuracy and precision that can be expected with manual baseline removal techniques. This study addresses this current lack of data. One hundred spectra of varying signal-to-noise ratio (SNR), signal-to-baseline ratio (SBR), baseline slope, and spectral congestion were constructed and baselines were subtracted by 16 volunteers who were categorized as being either experienced or inexperienced in baseline determination. In total, 285 baseline determinations were performed. The general level of accuracy and precision that can be expected for manually determined baselines from spectra of varying SNR, SBR, baseline slope, and spectral congestion is established. Furthermore, the effects of user experience on the accuracy and precision of baseline determination is estimated. The interactions between the above factors in affecting the accuracy and precision of baseline determination is highlighted. Where possible, the functional relationships between accuracy, precision, and the given spectral characteristic are detailed. The results provide users of manual baseline determination useful guidelines in establishing limits of accuracy and precision when performing manual baseline determination, as well as highlighting conditions that confound the accuracy and precision of manual baseline determination.

  15. Accuracy of a newly developed cone-beam computerized tomography-aided surgical guidance system for dental implant placement: an ex vivo study.

    PubMed

    Murat, Sema; Kamburoğlu, Kivanç; Özen, Tuncer

    2012-12-01

    The aim of the present study was to measure the accuracy of the cone-beam computerized tomography (CBCT)- aided StentCad Beyond surgical guidance system and to compare bone-supported and tooth/bone-supported guidance by using this system in dental implant placement ex vivo. Five cadaver mandibles were scanned using an Iluma CBCT scanner. After scanning, DICOM slices were transferred to the StentCad Beyond implant simulation software, which was used for preoperative implant planning. Using the StentCad Beyond guidance system, 9 implant drills were inserted using a bone-supported guidance system and 11 using a tooth/bone-supported guidance system. Mandibles were scanned again and these data were transferred to the StentCad Beyond software. Pre- and postoperative information was superimposed using the Rhinoceros version 4 software program, and deviations between planned and actual drill positions were calculated for each implant. In addition, differences between bone-supported and tooth/bone-supported guidance systems were analyzed by t-test, with a significance level of P < .05. Data analysis found a mean coronal deviation of 1.2 ± 0.3 mm and 0.6 ± 0.6 mm, mean apical deviation of 1.3 ± 0.6 mm and 0.7 ± 0.6 mm, mean apical and coronal depth deviation of 1.4 ± 0.3 mm and 1.3 ± 0.3 mm, and mean angular deviation of 4.2° ± 2.0° and 3.0° ± 1.5° for tooth/bone supported and bone-supported guides, respectively. No statistical differences were found in depth or angular deviations between groups (P > .05); however, statistically significant differences between groups were found in mean horizontal coronal deviation (P = .016) and mean horizontal apical deviation (P = .047). The StentCad Beyond system was found to be a reliable guide for placing implants ex vivo.

  16. MRI-based Preplanning Using CT and MRI Data Fusion in Patients With Cervical Cancer Treated With 3D-based Brachytherapy: Feasibility and Accuracy Study

    SciTech Connect

    Dolezel, Martin; Odrazka, Karel; Zizka, Jan; Vanasek, Jaroslav; Kohlova, Tereza; Kroulik, Tomas; Spitzer, Dusan; Ryska, Pavel; Tichy, Michal; Kostal, Milan; Jalcova, Lubica

    2012-09-01

    Purpose: Magnetic resonance imaging (MRI)-assisted radiation treatment planning enables enhanced target contouring. The purpose of this study is to analyze the feasibility and accuracy of computed tomography (CT) and MRI data fusion for MRI-based treatment planning in an institution where an MRI scanner is not available in the radiotherapy department. Methods and Materials: The registration inaccuracy of applicators and soft tissue was assessed in 42 applications with CT/MRI data fusion. The absolute positional difference of the center of the applicators was measured in four different planes from the top of the tandem to the cervix. Any inaccuracy of registration of soft tissue in relation to the position of applicators was determined and dose-volume parameters for MRI preplans and for CT/MRI fusion plans with or without target and organs at risk (OAR) adaptation were evaluated. Results: We performed 6,132 measurements in 42 CT/MRI image fusions. Median absolute difference of the center of tandem on CT and MRI was 1.1 mm. Median distance between the center of the right ovoid on CT and MRI was 1.7 and 1.9 mm in the laterolateral and anteroposterior direction, respectively. Corresponding values for the left ovoid were 1.6 and 1.8 mm. Rotation of applicators was 3.1 Degree-Sign . Median absolute difference in position of applicators in relation to soft tissue was 1.93, 1.50, 1.05, and 0.84 mm in the respective transverse planes, and 1.17, 1.28, 1.27, and 1.17 mm in selected angular directions. The dosimetric parameters for organs at risk on CT/MRI fusion plans without OAR adaptation were significantly impaired whereas the target coverage was not influenced. Planning without target adaptation led to overdosing of the target volume, especially high-risk clinical target volume - D{sub 90} 88.2 vs. 83.1 (p < 0.05). Conclusions: MRI-based preplanning with consecutive CT/MRI data fusion can be safe and feasible, with an acceptable inaccuracy of soft tissue registration.

  17. Finite-volume versus streaming-based lattice Boltzmann algorithm for fluid-dynamics simulations: A one-to-one accuracy and performance study.

    PubMed

    Shrestha, Kalyan; Mompean, Gilmar; Calzavarini, Enrico

    2016-02-01

    A finite-volume (FV) discretization method for the lattice Boltzmann (LB) equation, which combines high accuracy with limited computational cost is presented. In order to assess the performance of the FV method we carry out a systematic comparison, focused on accuracy and computational performances, with the standard streaming lattice Boltzmann equation algorithm. In particular we aim at clarifying whether and in which conditions the proposed algorithm, and more generally any FV algorithm, can be taken as the method of choice in fluid-dynamics LB simulations. For this reason the comparative analysis is further extended to the case of realistic flows, in particular thermally driven flows in turbulent conditions. We report the successful simulation of high-Rayleigh number convective flow performed by a lattice Boltzmann FV-based algorithm with wall grid refinement.

  18. Short-term solar pressure effect and GM uncertainty on TDRS orbital accuracy: A study of the interaction of modeling error with tracking and orbit determination

    NASA Technical Reports Server (NTRS)

    Fang, B. T.

    1979-01-01

    The TDRS was modeled as a combination of a sun-pointing solar panel and earth-pointing plate. Based on this model, explanations are given for the following orbit determination error characteristics: inherent limits in orbital accuracy, the variation of solar pressure induced orbital error with time of the day of epoch, the insensitivity of range-rate orbits to GM error, and optimum bilateration baseline.

  19. Empathic Embarrassment Accuracy in Autism Spectrum Disorder.

    PubMed

    Adler, Noga; Dvash, Jonathan; Shamay-Tsoory, Simone G

    2015-06-01

    Empathic accuracy refers to the ability of perceivers to accurately share the emotions of protagonists. Using a novel task assessing embarrassment, the current study sought to compare levels of empathic embarrassment accuracy among individuals with autism spectrum disorders (ASD) with those of matched controls. To assess empathic embarrassment accuracy, we compared the level of embarrassment experienced by protagonists to the embarrassment felt by participants while watching the protagonists. The results show that while the embarrassment ratings of participants and protagonists were highly matched among controls, individuals with ASD failed to exhibit this matching effect. Furthermore, individuals with ASD rated their embarrassment higher than controls when viewing themselves and protagonists on film, but not while performing the task itself. These findings suggest that individuals with ASD tend to have higher ratings of empathic embarrassment, perhaps due to difficulties in emotion regulation that may account for their impaired empathic accuracy and aberrant social behavior. PMID:25732043

  20. Landsat classification accuracy assessment procedures

    USGS Publications Warehouse

    Mead, R. R.; Szajgin, John

    1982-01-01

    A working conference was held in Sioux Falls, South Dakota, 12-14 November, 1980 dealing with Landsat classification Accuracy Assessment Procedures. Thirteen formal presentations were made on three general topics: (1) sampling procedures, (2) statistical analysis techniques, and (3) examples of projects which included accuracy assessment and the associated costs, logistical problems, and value of the accuracy data to the remote sensing specialist and the resource manager. Nearly twenty conference attendees participated in two discussion sessions addressing various issues associated with accuracy assessment. This paper presents an account of the accomplishments of the conference.

  1. Cochrane diagnostic test accuracy reviews.

    PubMed

    Leeflang, Mariska M G; Deeks, Jonathan J; Takwoingi, Yemisi; Macaskill, Petra

    2013-10-07

    In 1996, shortly after the founding of The Cochrane Collaboration, leading figures in test evaluation research established a Methods Group to focus on the relatively new and rapidly evolving methods for the systematic review of studies of diagnostic tests. Seven years later, the Collaboration decided it was time to develop a publication format and methodology for Diagnostic Test Accuracy (DTA) reviews, as well as the software needed to implement these reviews in The Cochrane Library. A meeting hosted by the German Cochrane Centre in 2004 brought together key methodologists in the area, many of whom became closely involved in the subsequent development of the methodological framework for DTA reviews. DTA reviews first appeared in The Cochrane Library in 2008 and are now an integral part of the work of the Collaboration.

  2. Increasing Accuracy in Environmental Measurements

    NASA Astrophysics Data System (ADS)

    Jacksier, Tracey; Fernandes, Adelino; Matthew, Matt; Lehmann, Horst

    2016-04-01

    Human activity is increasing the concentrations of green house gases (GHG) in the atmosphere which results in temperature increases. High precision is a key requirement of atmospheric measurements to study the global carbon cycle and its effect on climate change. Natural air containing stable isotopes are used in GHG monitoring to calibrate analytical equipment. This presentation will examine the natural air and isotopic mixture preparation process, for both molecular and isotopic concentrations, for a range of components and delta values. The role of precisely characterized source material will be presented. Analysis of individual cylinders within multiple batches will be presented to demonstrate the ability to dynamically fill multiple cylinders containing identical compositions without isotopic fractionation. Additional emphasis will focus on the ability to adjust isotope ratios to more closely bracket sample types without the reliance on combusting naturally occurring materials, thereby improving analytical accuracy.

  3. Accuracy of Pressure Sensitive Paint

    NASA Technical Reports Server (NTRS)

    Liu, Tianshu; Guille, M.; Sullivan, J. P.

    2001-01-01

    Uncertainty in pressure sensitive paint (PSP) measurement is investigated from a standpoint of system modeling. A functional relation between the imaging system output and luminescent emission from PSP is obtained based on studies of radiative energy transports in PSP and photodetector response to luminescence. This relation provides insights into physical origins of various elemental error sources and allows estimate of the total PSP measurement uncertainty contributed by the elemental errors. The elemental errors and their sensitivity coefficients in the error propagation equation are evaluated. Useful formulas are given for the minimum pressure uncertainty that PSP can possibly achieve and the upper bounds of the elemental errors to meet required pressure accuracy. An instructive example of a Joukowsky airfoil in subsonic flows is given to illustrate uncertainty estimates in PSP measurements.

  4. The effect of relining on the accuracy and stability of maxillary complete dentures--an in vitro and in vivo study.

    PubMed

    Barco, M T; Moore, B K; Swartz, M L; Boone, M E; Dykema, R W; Phillips, R W

    1979-07-01

    A technique was developed for evaluating in vitro the accuracy or fit of experimental denture bases using a low-viscosity impression material for determining the space between the master die and the processed denture base. These measurements indicated that relining heat-cured maxillary denture bases with autopolymerizing acrylic resin improved their adaptation to the ridges. Interestingly, if no teeth were present in the heat-cured denture base, markedly less distortion occurred after processing. Limited clinical measurements on the stability of maxillary dentures in function showed no statistically significant change in stability after relining, but the trend was toward increased stability with the relined denture.

  5. Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study.

    PubMed

    Phang, Isaac; Zoumprouli, Argyro; Saadoun, Samira; Papadopoulos, Marios C

    2016-09-01

    OBJECTIVE A novel technique for monitoring intraspinal pressure and spinal cord perfusion pressure in patients with traumatic spinal cord injury was recently described. This is analogous to monitoring intracranial pressure and cerebral perfusion pressure in patients with traumatic brain injury. Because intraspinal pressure monitoring is a new technique, its safety profile and impact on early patient care and long-term outcome after traumatic spinal cord injury are unknown. The object of this study is to review all patients who had intraspinal pressure monitoring to date at the authors' institution in order to define the accuracy of intraspinal pressure probe placement and the safety of the technique. METHODS At the end of surgery to fix spinal fractures, a pressure probe was inserted intradurally to monitor intraspinal pressure at the injury site. Postoperatively, CT scanning was performed within 48 hours and MRI at 2 weeks and 6 months. Neurointensive care management and complications were reviewed. The American Spinal Injury Association Impairment Scale (AIS) grade was determined on admission and at 2 to 4 weeks and 12 to 18 months postoperation. RESULTS To date, 42 patients with severe traumatic spinal cord injuries (AIS Grades A-C) had undergone intraspinal pressure monitoring. Monitoring started within 72 hours of injury and continued for up to a week. Based on postoperative CT and MRI, the probe position was acceptable in all patients, i.e., the probe was located at the site of maximum spinal cord swelling. Complications were probe displacement in 1 of 42 patients (2.4%), CSF leakage that required wound resuturing in 3 of 42 patients (7.1%), and asymptomatic pseudomeningocele that was diagnosed in 8 of 42 patients (19.0%). Pseudomeningocele was diagnosed on MRI and resolved within 6 months in all patients. Based on the MRI and neurological examination results, there were no serious probe-related complications such as meningitis, wound infection, hematoma

  6. Social class, contextualism, and empathic accuracy.

    PubMed

    Kraus, Michael W; Côté, Stéphane; Keltner, Dacher

    2010-11-01

    Recent research suggests that lower-class individuals favor explanations of personal and political outcomes that are oriented to features of the external environment. We extended this work by testing the hypothesis that, as a result, individuals of a lower social class are more empathically accurate in judging the emotions of other people. In three studies, lower-class individuals (compared with upper-class individuals) received higher scores on a test of empathic accuracy (Study 1), judged the emotions of an interaction partner more accurately (Study 2), and made more accurate inferences about emotion from static images of muscle movements in the eyes (Study 3). Moreover, the association between social class and empathic accuracy was explained by the tendency for lower-class individuals to explain social events in terms of features of the external environment. The implications of class-based patterns in empathic accuracy for well-being and relationship outcomes are discussed. PMID:20974714

  7. Two-dimensional temperature distribution measurement of flames by absorption CT employing CO{sub 2} (Experimental study on the wave number employed and the accuracy of measurement)

    SciTech Connect

    Wakai, Kazunori; Moroto, Masakazu; Takahashi, Shuhei; Bhattacharjee, S.

    1999-07-01

    The authors have developed the algorithm of infrared two-band absorption CT (computed tomography) not only for short optical path where Lambert-Beer law is applicable but also for long optical path where some band model should be applied. The authors have also shown employing CO{sub 2} as an absorption medium, statistical model as a band model and Curtis-Godson model to treat non-uniform temperature fields that when optical path is long and spectrum has steep change, there are suitable wavelengths and widths to keep good accuracy. However, it was done only by computer simulation, and in this report, those results are discussed experimentally. The flat burner was used to compare temperature measured by above method with the temperature measured by sodium D-line reversal method. The results showed good correspondence and it means that the predicted suitable wavelengths and widths are experimentally confirmed. The accuracy, namely, standard deviation of the temperature, at the best wavelength conditions was lower than 20K. Temperature distributions around non-uniform temperature distribution on the flat disk burner and domestic boiler were also measured as applications and the results show that this method is applicable for the measurement of rather complicated two-dimensional temperature distributions.

  8. The impact of accuracy motivation on interpretation, comparison, and correction processes: accuracy x knowledge accessibility effects.

    PubMed

    Stapel, D A; Koomen, W; Zeelenberg, M

    1998-04-01

    Four studies provide evidence for the notion that there may be boundaries to the extent to which accuracy motivation may help perceivers to escape the influence of fortuitously activated information. Specifically, although accuracy motivations may eliminate assimilative accessibility effects, they are less likely to eliminate contrastive accessibility effects. It was found that the occurrence of different types of contrast effects (comparison and correction) was not significantly affected by participants' accuracy motivations. Furthermore, it was found that the mechanisms instigated by accuracy motivations differ from those ignited by correction instructions: Accuracy motivations attenuate assimilation effects because perceivers add target interpretations to the one suggested by primed information. Conversely, it was found that correction instructions yield contrast and prompt respondents to remove the priming event's influence from their reaction to the target. PMID:9569650

  9. Point-based superimposition of a digital dental model on to a three-dimensional computed tomographic skull: an accuracy study in vitro.

    PubMed

    Lin, X; Chen, T; Liu, J; Jiang, T; Yu, D; Shen, S G F

    2015-01-01

    We investigated the accuracy of point-based superimposition of a digital dental model on to a 3-dimensional computed tomographic (CT) skull with intact dentition. The physical model was scanned by CT to give a virtual skull model, and a plaster dental model was taken and laser-scanned to give a digital dental model. Three different background investigators were recruited and calibrated to make the point-based superimposition, and afterwards were asked to repeat 5 superimpositions each. Five bone-to-tooth measurements for the maxilla and 6 for the mandible were selected to indicate the relation of teeth to skull. Repeated measures were made on the physical model to act as a control group, and on the virtual model to act as the test group. The absolute agreement intra-class correlation coefficient (ICC) was used to assess the intra/inter-investigator reliability; Bland-Altman analysis was used to calculate the general differences, limits of agreement, and precision ranges of the estimated limits. Inter/intra-investigator reliability was excellent with ICC varying from 0.986 to 1; Bland-Altman analysis indicated that general difference was 0.01 (0.25)mm, the upper limit of agreement was 0.50mm and the lower limit -0.47 mm, and the precision range for the upper limit was 0.43 mm to 0.57 mm and for the lower limit -0.54 mm to -0.40 mm. Clinically acceptable accuracy can be achieved using a direct point-based method to superimpose a digital dental model on to a 3-dimensional CT skull.

  10. Accuracy and Reproducibility of HER2 Status in Breast Cancer Using Immunohistochemistry: A Quality Control Study in Tuscany Evaluating the Impact of Updated 2013 ASCO/CAP Recommendations.

    PubMed

    Bianchi, S; Caini, S; Paglierani, M; Saieva, C; Vezzosi, V; Baroni, G; Simoni, A; Palli, D

    2015-04-01

    The correct identification of HER2-positive cases is a key point to provide the most appropriate therapy to breast cancer (BC) patients. We aimed at investigating the reproducibility and accuracy of HER2 expression by immunohistochemistry (IHC) in a selected series of 35 invasive BC cases across the pathological anatomy laboratories in Tuscany, Italy. Unstained sections of each BC case were sent to 12 participating laboratories. Pathologists were required to score according to the Food and Drug Administration (FDA) four-tier scoring system (0, 1+, 2+, 3+). Sixteen and nineteen cases were HER2 non-amplified and amplified respectively on fluorescence in situ hybridization. Among 192 readings of the 16 HER2 non-amplified samples, 153 (79.7%) were coded as 0 or 1+, 39 (20.3%) were 2+, and none was 3+ (false positive rate 0%). Among 228 readings of the 19 HER2 amplified samples, 56 (24.6%) were scored 0 or 1+, 79 (34.6%) were 2+, and 93 (40.8%) were 3+. The average sensitivity was 75.4%, ranging between 47% and 100%, and the overall false negative rate was 24.6%. Participation of pathological anatomy laboratories performing HER2 testing by IHC in external quality assurance programs should be made mandatory, as the system is able to identify laboratories with suboptimal performance that may need technical advice. Updated 2013 ASCO/CAP recommendations should be adopted as the widening of IHC 2+ "equivocal" category would improve overall accuracy of HER2 testing, as more cases would be classified in this category and, consequently, tested with an in situ hybridisation method. PMID:25367072

  11. ACCURACY OF CO2 SENSORS

    SciTech Connect

    Fisk, William J.; Faulkner, David; Sullivan, Douglas P.

    2008-10-01

    Are the carbon dioxide (CO2) sensors in your demand controlled ventilation systems sufficiently accurate? The data from these sensors are used to automatically modulate minimum rates of outdoor air ventilation. The goal is to keep ventilation rates at or above design requirements while adjusting the ventilation rate with changes in occupancy in order to save energy. Studies of energy savings from demand controlled ventilation and of the relationship of indoor CO2 concentrations with health and work performance provide a strong rationale for use of indoor CO2 data to control minimum ventilation rates1-7. However, this strategy will only be effective if, in practice, the CO2 sensors have a reasonable accuracy. The objective of this study was; therefore, to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. This article provides a summary of study methods and findings ? additional details are available in a paper in the proceedings of the ASHRAE IAQ?2007 Conference8.

  12. Towards Experimental Accuracy from the First Principles

    NASA Astrophysics Data System (ADS)

    Polyansky, O. L.; Lodi, L.; Tennyson, J.; Zobov, N. F.

    2013-06-01

    Producing ab initio ro-vibrational energy levels of small, gas-phase molecules with an accuracy of 0.10 cm^{-1} would constitute a significant step forward in theoretical spectroscopy and would place calculated line positions considerably closer to typical experimental accuracy. Such an accuracy has been recently achieved for the H_3^+ molecular ion for line positions up to 17 000 cm ^{-1}. However, since H_3^+ is a two-electron system, the electronic structure methods used in this study are not applicable to larger molecules. A major breakthrough was reported in ref., where an accuracy of 0.10 cm^{-1} was achieved ab initio for seven water isotopologues. Calculated vibrational and rotational energy levels up to 15 000 cm^{-1} and J=25 resulted in a standard deviation of 0.08 cm^{-1} with respect to accurate reference data. As far as line intensities are concerned, we have already achieved for water a typical accuracy of 1% which supersedes average experimental accuracy. Our results are being actively extended along two major directions. First, there are clear indications that our results for water can be improved to an accuracy of the order of 0.01 cm^{-1} by further, detailed ab initio studies. Such level of accuracy would already be competitive with experimental results in some situations. A second, major, direction of study is the extension of such a 0.1 cm^{-1} accuracy to molecules containg more electrons or more than one non-hydrogen atom, or both. As examples of such developments we will present new results for CO, HCN and H_2S, as well as preliminary results for NH_3 and CH_4. O.L. Polyansky, A. Alijah, N.F. Zobov, I.I. Mizus, R. Ovsyannikov, J. Tennyson, L. Lodi, T. Szidarovszky and A.G. Csaszar, Phil. Trans. Royal Soc. London A, {370}, 5014-5027 (2012). O.L. Polyansky, R.I. Ovsyannikov, A.A. Kyuberis, L. Lodi, J. Tennyson and N.F. Zobov, J. Phys. Chem. A, (in press). L. Lodi, J. Tennyson and O.L. Polyansky, J. Chem. Phys. {135}, 034113 (2011).

  13. High accuracy broadband infrared spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Venkataramanan

    Mueller matrix spectroscopy or Spectropolarimetry combines conventional spectroscopy with polarimetry, providing more information than can be gleaned from spectroscopy alone. Experimental studies on infrared polarization properties of materials covering a broad spectral range have been scarce due to the lack of available instrumentation. This dissertation aims to fill the gap by the design, development, calibration and testing of a broadband Fourier Transform Infra-Red (FT-IR) spectropolarimeter. The instrument operates over the 3-12 mum waveband and offers better overall accuracy compared to the previous generation instruments. Accurate calibration of a broadband spectropolarimeter is a non-trivial task due to the inherent complexity of the measurement process. An improved calibration technique is proposed for the spectropolarimeter and numerical simulations are conducted to study the effectiveness of the proposed technique. Insights into the geometrical structure of the polarimetric measurement matrix is provided to aid further research towards global optimization of Mueller matrix polarimeters. A high performance infrared wire-grid polarizer is characterized using the spectropolarimeter. Mueller matrix spectrum measurements on Penicillin and pine pollen are also presented.

  14. Astrophysics with Microarcsecond Accuracy Astrometry

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    2008-01-01

    Space-based astrometry promises to provide a powerful new tool for astrophysics. At a precision level of a few microarcsonds, a wide range of phenomena are opened up for study. In this paper we discuss the capabilities of the SIM Lite mission, the first space-based long-baseline optical interferometer, which will deliver parallaxes to 4 microarcsec. A companion paper in this volume will cover the development and operation of this instrument. At the level that SIM Lite will reach, better than 1 microarcsec in a single measurement, planets as small as one Earth can be detected around many dozen of the nearest stars. Not only can planet masses be definitely measured, but also the full orbital parameters determined, allowing study of system stability in multiple planet systems. This capability to survey our nearby stellar neighbors for terrestrial planets will be a unique contribution to our understanding of the local universe. SIM Lite will be able to tackle a wide range of interesting problems in stellar and Galactic astrophysics. By tracing the motions of stars in dwarf spheroidal galaxies orbiting our Milky Way, SIM Lite will probe the shape of the galactic potential history of the formation of the galaxy, and the nature of dark matter. Because it is flexibly scheduled, the instrument can dwell on faint targets, maintaining its full accuracy on objects as faint as V=19. This paper is a brief survey of the diverse problems in modern astrophysics that SIM Lite will be able to address.

  15. Accuracy of polyp localization at colonoscopy

    PubMed Central

    O’Connor, Sam A.; Hewett, David G.; Watson, Marcus O.; Kendall, Bradley J.; Hourigan, Luke F.; Holtmann, Gerald

    2016-01-01

    Background and study aims: Accurate documentation of lesion localization at the time of colonoscopic polypectomy is important for future surveillance, management of complications such as delayed bleeding, and for guiding surgical resection. We aimed to assess the accuracy of endoscopic localization of polyps during colonoscopy and examine variables that may influence this accuracy. Patients and methods: We conducted a prospective observational study in consecutive patients presenting for elective, outpatient colonoscopy. All procedures were performed by Australian certified colonoscopists. The endoscopic location of each polyp was reported by the colonoscopist at the time of resection and prospectively recorded. Magnetic endoscope imaging was used to determine polyp location, and colonoscopists were blinded to this image. Three experienced colonoscopists, blinded to the endoscopist’s assessment of polyp location, independently scored the magnetic endoscope images to obtain a reference standard for polyp location (Cronbach alpha 0.98). The accuracy of colonoscopist polyp localization using this reference standard was assessed, and colonoscopist, procedural and patient variables affecting accuracy were evaluated. Results: A total of 155 patients were enrolled and 282 polyps were resected in 95 patients by 14 colonoscopists. The overall accuracy of polyp localization was 85 % (95 % confidence interval, CI; 60 – 96 %). Accuracy varied significantly (P < 0.001) by colonic segment: caecum 100 %, ascending 77 % (CI;65 – 90), transverse 84 % (CI;75 – 92), descending 56 % (CI;32 – 81), sigmoid 88 % (CI;79 – 97), rectum 96 % (CI;90 – 101). There were significant differences in accuracy between colonoscopists (P < 0.001), and colonoscopist experience was a significant independent predictor of accuracy (OR 3.5, P = 0.028) after adjustment for patient and procedural variables. Conclusions: Accuracy of

  16. Accuracy assessment of GOCE-based geopotential models and their use for modelling the gravimetric quasigeoid - A case study for Poland

    NASA Astrophysics Data System (ADS)

    Godah, Walyeldeen; Szelachowska, Malgorzata; Krynski, Jan

    2014-06-01

    The GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) has significantly upgraded the knowledge on the Earth gravity field. In this contribution the accuracy of height anomalies determined from Global Geopotential Models (GGMs) based on approximately 27 months GOCE satellite gravity gradiometry (SGG) data have been assessed over Poland using three sets of precise GNSS/levelling data. The fits of height anomalies obtained from 4th release GOCE-based GGMs to GNSS/levelling data were discussed and compared with the respective ones of 3rd release GOCE-based GGMs and the EGM08. Furthermore, two highly accurate gravimetric quasigeoid models were developed over the area of Poland using high resolution Faye gravity anomalies. In the first, the GOCE-based GGM was used as a reference geopotential model, and in the second - the EGM08. They were evaluated with GNSS/levelling data and their accuracy performance was assessed. The use of GOCE-based GGMs for recovering the long-wavelength gravity signal in gravimetric quasigeoid modelling was discussed. Misja GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) przyczyniła się do znacznego poprawienia znajomości pola siły ciężkości Ziemi. W artykule przedstawiono wyniki oszacowania dokładności anomalii wysokości, wyznaczonych z globalnych modeli geopotencjału opracowanych na podstawie blisko 27 miesięcy pomiarów z satelitarnej misji gradiometrycznej GOCE. Do oszacowania wykorzystano trzy zbiory dokładnych danych satelitarno-niwelacyjnych z obszaru Polski. Omówiono wyniki wpasowania wartości anomalii wysokości otrzymanych z czwartej wersji globalnych modeli geopotencjału wyznaczonych na podstawie danych misji GOCE do danych satelitarno-niwelacyjnych oraz porównano je z wynikami odpowiedniego wpasowania trzeciej wersji globalnych modeli geopotencjału otrzymanych z GOCE oraz z modelu EGM08. Ponadto, wykorzystując wysokorozdzielczy zbiór grawimetrycznych anomalii Faye'a, wyznaczono dla

  17. Asymptotic accuracy of two-class discrimination

    SciTech Connect

    Ho, T.K.; Baird, H.S.

    1994-12-31

    Poor quality-e.g. sparse or unrepresentative-training data is widely suspected to be one cause of disappointing accuracy of isolated-character classification in modern OCR machines. We conjecture that, for many trainable classification techniques, it is in fact the dominant factor affecting accuracy. To test this, we have carried out a study of the asymptotic accuracy of three dissimilar classifiers on a difficult two-character recognition problem. We state this problem precisely in terms of high-quality prototype images and an explicit model of the distribution of image defects. So stated, the problem can be represented as a stochastic source of an indefinitely long sequence of simulated images labeled with ground truth. Using this sequence, we were able to train all three classifiers to high and statistically indistinguishable asymptotic accuracies (99.9%). This result suggests that the quality of training data was the dominant factor affecting accuracy. The speed of convergence during training, as well as time/space trade-offs during recognition, differed among the classifiers.

  18. Seasonal Effects on GPS PPP Accuracy

    NASA Astrophysics Data System (ADS)

    Saracoglu, Aziz; Ugur Sanli, D.

    2016-04-01

    GPS Precise Point Positioning (PPP) is now routinely used in many geophysical applications. Static positioning and 24 h data are requested for high precision results however real life situations do not always let us collect 24 h data. Thus repeated GPS surveys of 8-10 h observation sessions are still used by some research groups. Positioning solutions from shorter data spans are subject to various systematic influences, and the positioning quality as well as the estimated velocity is degraded. Researchers pay attention to the accuracy of GPS positions and of the estimated velocities derived from short observation sessions. Recently some research groups turned their attention to the study of seasonal effects (i.e. meteorological seasons) on GPS solutions. Up to now usually regional studies have been reported. In this study, we adopt a global approach and study the various seasonal effects (including the effect of the annual signal) on GPS solutions produced from short observation sessions. We use the PPP module of the NASA/JPL's GIPSY/OASIS II software and globally distributed GPS stations' data of the International GNSS Service. Accuracy studies previously performed with 10-30 consecutive days of continuous data. Here, data from each month of a year, incorporating two years in succession, is used in the analysis. Our major conclusion is that a reformulation for the GPS positioning accuracy is necessary when taking into account the seasonal effects, and typical one term accuracy formulation is expanded to a two-term one.

  19. Comparing the accuracy of high-dimensional neural network potentials and the systematic molecular fragmentation method: A benchmark study for all-trans alkanes

    NASA Astrophysics Data System (ADS)

    Gastegger, Michael; Kauffmann, Clemens; Behler, Jörg; Marquetand, Philipp

    2016-05-01

    Many approaches, which have been developed to express the potential energy of large systems, exploit the locality of the atomic interactions. A prominent example is the fragmentation methods in which the quantum chemical calculations are carried out for overlapping small fragments of a given molecule that are then combined in a second step to yield the system's total energy. Here we compare the accuracy of the systematic molecular fragmentation approach with the performance of high-dimensional neural network (HDNN) potentials introduced by Behler and Parrinello. HDNN potentials are similar in spirit to the fragmentation approach in that the total energy is constructed as a sum of environment-dependent atomic energies, which are derived indirectly from electronic structure calculations. As a benchmark set, we use all-trans alkanes containing up to eleven carbon atoms at the coupled cluster level of theory. These molecules have been chosen because they allow to extrapolate reliable reference energies for very long chains, enabling an assessment of the energies obtained by both methods for alkanes including up to 10 000 carbon atoms. We find that both methods predict high-quality energies with the HDNN potentials yielding smaller errors with respect to the coupled cluster reference.

  20. Predictive accuracy in the neuroprediction of rearrest

    PubMed Central

    Aharoni, Eyal; Mallett, Joshua; Vincent, Gina M.; Harenski, Carla L.; Calhoun, Vince D.; Sinnott-Armstrong, Walter; Gazzaniga, Michael S.; Kiehl, Kent A.

    2014-01-01

    A recently published study by the present authors (Aharoni et al., 2013) reported evidence that functional changes in the anterior cingulate cortex (ACC) within a sample of 96 criminal offenders who were engaged in a Go/No-Go impulse control task significantly predicted their rearrest following release from prison. In an extended analysis, we use discrimination and calibration techniques to test the accuracy of these predictions relative to more traditional models and their ability to generalize to new observations in both full and reduced models. Modest to strong discrimination and calibration accuracy were found, providing additional support for the utility of neurobiological measures in predicting rearrest. PMID:24720689

  1. Decreased interoceptive accuracy following social exclusion.

    PubMed

    Durlik, Caroline; Tsakiris, Manos

    2015-04-01

    The need for social affiliation is one of the most important and fundamental human needs. Unsurprisingly, humans display strong negative reactions to social exclusion. In the present study, we investigated the effect of social exclusion on interoceptive accuracy - accuracy in detecting signals arising inside the body - measured with a heartbeat perception task. We manipulated exclusion using Cyberball, a widely used paradigm of a virtual ball-tossing game, with half of the participants being included during the game and the other half of participants being ostracized during the game. Our results indicated that heartbeat perception accuracy decreased in the excluded, but not in the included, participants. We discuss these results in the context of social and physical pain overlap, as well as in relation to internally versus externally oriented attention. PMID:25701592

  2. Metrical Patterns of Words and Production Accuracy.

    ERIC Educational Resources Information Center

    Schwartz, Richard G.; Goffman, Lisa

    1995-01-01

    This study examined the influence of metrical patterns (syllable stress and serial position) of words on the production accuracy of 20 children (ages 22 months to 28 months). Among results were that one-fourth of the initial unstressed syllables were omitted and that consonant omissions, though few, tended to occur in the initial position.…

  3. Task Speed and Accuracy Decrease When Multitasking

    ERIC Educational Resources Information Center

    Lin, Lin; Cockerham, Deborah; Chang, Zhengsi; Natividad, Gloria

    2016-01-01

    As new technologies increase the opportunities for multitasking, the need to understand human capacities for multitasking continues to grow stronger. Is multitasking helping us to be more efficient? This study investigated the multitasking abilities of 168 participants, ages 6-72, by measuring their task accuracy and completion time when they…

  4. Observed Consultation: Confidence and Accuracy of Assessors

    ERIC Educational Resources Information Center

    Tweed, Mike; Ingham, Christopher

    2010-01-01

    Judgments made by the assessors observing consultations are widely used in the assessment of medical students. The aim of this research was to study judgment accuracy and confidence and the relationship between these. Assessors watched recordings of consultations, scoring the students on: a checklist of items; attributes of consultation; a…

  5. Accuracy Of Stereometry In Assessing Orthognathic Surgery

    NASA Astrophysics Data System (ADS)

    King, Geoffrey E.; Bays, R. A.

    1983-07-01

    An X-ray stereometric technique has been developed for the determination of 3-dimensional coordinates of spherical metallic markers previously implanted in monkey skulls. The accuracy of the technique is better than 0.5mm. and uses readily available demountable X-ray equipment. The technique is used to study the effects and stability of experimental orthognathic surgery.

  6. Practical Classification Guidelines for Diabetes in patients treated with insulin: a cross-sectional study of the accuracy of diabetes diagnosis

    PubMed Central

    Hope, Suzy V; Wienand-Barnett, Sophie; Shepherd, Maggie; King, Sophie M; Fox, Charles; Khunti, Kamlesh; Oram, Richard A; Knight, Bea A; Hattersley, Andrew T; Jones, Angus G; Shields, Beverley M

    2016-01-01

    Background Differentiating between type 1 and type 2 diabetes is fundamental to ensuring appropriate management of patients, but can be challenging, especially when treating with insulin. The 2010 UK Practical Classification Guidelines for Diabetes were developed to help make the differentiation. Aim To assess diagnostic accuracy of the UK guidelines against ‘gold standard’ definitions of type 1 and type 2 diabetes based on measured C-peptide levels. Design and setting In total, 601 adults with insulin-treated diabetes and diabetes duration ≥5 years were recruited in Devon, Northamptonshire, and Leicestershire. Method Baseline information and home urine sample were collected. Urinary C-peptide creatinine ratio (UCPCR) measures endogenous insulin production. Gold standard type 1 diabetes was defined as continuous insulin treatment within 3 years of diagnosis and absolute insulin deficiency (UCPCR<0.2 nmol/mmol ≥5 years post-diagnosis); all others classed as having type 2 diabetes. Diagnostic performance of the clinical criteria was assessed and other criteria explored using receiver operating characteristic (ROC) curves. Results UK guidelines correctly classified 86% of participants. Most misclassifications occurred in patients classed as having type 1 diabetes who had significant endogenous insulin levels (57 out of 601; 9%); most in those diagnosed ≥35 years and treated with insulin from diagnosis, where 37 out of 66 (56%) were misclassified. Time to insulin and age at diagnosis performed best in predicting long-term endogenous insulin production (ROC AUC = 0.904 and 0.871); BMI was a less strong predictor of diabetes type (AUC = 0.824). Conclusion Current UK guidelines provide a pragmatic clinical approach to classification reflecting long-term endogenous insulin production; caution is needed in older patients commencing insulin from diagnosis, where misclassification rates are increased. PMID:27080317

  7. The Uptake and Accuracy of Oral Kits for HIV Self-Testing in High HIV Prevalence Setting: A Cross-Sectional Feasibility Study in Blantyre, Malawi

    PubMed Central

    Choko, Augustine Talumba; Desmond, Nicola; Webb, Emily L.; Chavula, Kondwani; Napierala-Mavedzenge, Sue; Gaydos, Charlotte A.; Makombe, Simon D.; Chunda, Treza; Squire, S. Bertel; French, Neil; Mwapasa, Victor; Corbett, Elizabeth L.

    2011-01-01

    Background Although HIV testing and counseling (HTC) uptake has increased dramatically in Africa, facility-based services are unlikely to ever meet ongoing need to the full. A major constraint in scaling up community and home-based HTC services is the unacceptability of receiving HTC from a provider known personally to prospective clients. We investigated the potential of supervised oral HIV self-testing from this perspective. Methods and Findings Adult members of 60 households and 72 members of community peer groups in urban Blantyre, Malawi, were selected using population-weighted random cluster sampling. Participants were offered self-testing plus confirmatory HTC (parallel testing with two rapid finger-prick blood tests), standard HTC alone, or no testing. 283 (95.6%) of 298 selected adults participated, including 136 (48.0%) men. 175 (61.8%) had previously tested (19 known HIV positive), although only 64 (21.5%) within the last year. HIV prevalence was 18.5%. Among 260 (91.9%) who opted to self-test after brief demonstration and illustrated instructions, accuracy was 99.2% (two false negatives). Although 98.5% rated the test “not hard at all to do,” 10.0% made minor procedural errors, and 10.0% required extra help. Most participants indicated willingness to accept self-test kits, but not HTC, from a neighbor (acceptability 94.5% versus 46.8%, p = 0.001). Conclusions Oral supervised self-testing was highly acceptable and accurate, although minor errors and need for supervisory support were common. This novel option has potential for high uptake at local community level if it can be supervised and safely linked to counseling and care. Please see later in the article for the Editors' Summary PMID:21990966

  8. Accuracy in optical overlay metrology

    NASA Astrophysics Data System (ADS)

    Bringoltz, Barak; Marciano, Tal; Yaziv, Tal; DeLeeuw, Yaron; Klein, Dana; Feler, Yoel; Adam, Ido; Gurevich, Evgeni; Sella, Noga; Lindenfeld, Ze'ev; Leviant, Tom; Saltoun, Lilach; Ashwal, Eltsafon; Alumot, Dror; Lamhot, Yuval; Gao, Xindong; Manka, James; Chen, Bryan; Wagner, Mark

    2016-03-01

    In this paper we discuss the mechanism by which process variations determine the overlay accuracy of optical metrology. We start by focusing on scatterometry, and showing that the underlying physics of this mechanism involves interference effects between cavity modes that travel between the upper and lower gratings in the scatterometry target. A direct result is the behavior of accuracy as a function of wavelength, and the existence of relatively well defined spectral regimes in which the overlay accuracy and process robustness degrades (`resonant regimes'). These resonances are separated by wavelength regions in which the overlay accuracy is better and independent of wavelength (we term these `flat regions'). The combination of flat and resonant regions forms a spectral signature which is unique to each overlay alignment and carries certain universal features with respect to different types of process variations. We term this signature the `landscape', and discuss its universality. Next, we show how to characterize overlay performance with a finite set of metrics that are available on the fly, and that are derived from the angular behavior of the signal and the way it flags resonances. These metrics are used to guarantee the selection of accurate recipes and targets for the metrology tool, and for process control with the overlay tool. We end with comments on the similarity of imaging overlay to scatterometry overlay, and on the way that pupil overlay scatterometry and field overlay scatterometry differ from an accuracy perspective.

  9. Multi-temporal topographic models in fluvial systems: are accuracies enough to change the temporal and spatial scales of our studies?

    NASA Astrophysics Data System (ADS)

    Vericat, Damià; Ramos, Ester; Brasington, James; Muñoz, Efrén; Béjar, María; Gibbins, Chris; Batalla, Ramon J.; Tena, Álvaro; Smith, Mark; Wheaton, Joe

    2015-04-01

    Recent advances in topography are offering a set of opportunities that deserve a critical evaluation before being successfully applied. Terrestrial Laser Scanning opened a new world by offering the opportunity to obtain topographic models at unprecedented resolutions. The time involved in data acquisition, although has substantially improved by means of fast scanners and new mobile platforms, limited the spatial and temporal scales in which such technique could be applied. Automatic Digital Photogrammetry or Structure from Motion is now offering a new set of opportunities and challenges. This technique possesses the trilogy a geomorphologist is looking to fully understand how landforms change and which are the main causes and consequences: speed, cost and resolution. But, a set of questions arise after all post-processing involved in these novel datasets: are accuracies enough to jump at large spatial scales? Can we repeat topographic surveys and depict small magnitude but relatively high frequent landform deformations overcoming the minimum level of detection of our comparisons? In this paper we present some of the preliminary results obtained in the background of MorphSed (www.morphsed.es). Morphsed is analysing the morpho-sedimentary dynamics of a fluvial system at multiple temporal scales. Multi-event topographic models (DEMs) are obtained by means of Structure from Motion using close range aerial photography obtained in a 12-km channel reach of the wandering Upper River Cinca (Southern Pyrenees, Iberian Peninsula). Topographic channel changes are critically analysed based on the quality of the developed models. DEMs obtained at different periods are compared (DoD). Two general comparisons are performed: (a) comparison of topographic models obtained before and after low magnitude channel changes, and (b) comparison of models acquired before and after major channel disturbances. Special attention is paid to the role of the ground control, data density and

  10. Investigating the accuracy of parentally reported weights and lengths at 12 months of age as compared to measured weights and lengths in a longitudinal childhood genome study

    PubMed Central

    Hazrati, Sahel; Hourigan, Suchitra K; Waller, Allison; Yui, Yvonne; Gilchrist, Nancy; Huddleston, Kathi; Niederhuber, John

    2016-01-01

    Background Childhood obesity studies rely on parentally reported anthropometrics. However, the accuracy of such data has not been evaluated for 12-month-old children. Moreover, methods to improve the accuracy of reported data have not been assessed in prior studies. Methods A total of 185 children enrolled in a northern Virginia childhood longitudinal cohort genomic study had parentally completed surveys at 12 months. Measured weights and lengths were recorded for the same children from their 12-month paediatrician visit. Weight for length percentiles were calculated using World Health Organization gender-specific growth charts. The agreement between reported and measured values was examined using Pearson's correlation, paired t-test and κ statistics. The interquartile outlier rule was used to detect and remove outliers. Results Parentally reported weight was strongly associated with measured weight at 12 months (r=0.90). There was only a moderate correlation between parentally reported and measured lengths (r=0.52) and calculated weight for length percentiles (r=0.65). After removing outliers from parentally reported data, there was an increase in correlation between parentally reported and measured data for weight (r=0.93), length (r=0.69) and weight for length percentiles (r=0.76). Outliers removed compared to all children included were more likely to have maternal education less than a bachelor's degree (p=0.007). Conclusions After removal of outliers from reported data, there is a strong correlation between calculated reported and measured weight for length percentiles suggesting that this may be an effective method to increase accuracy when conducting large-scale obesity studies in young children where study costs benefit from using parentally reported data. PMID:27491670

  11. A Comparative Evaluation of Dimensional Accuracy and Surface Detail Reproduction of Four Hydrophilic Vinyl Polysiloxane Impression Materials Tested Under Dry, Moist, and Wet Conditions-An In Vitro Study.

    PubMed

    Nagrath, Rahul; Lahori, Manesh; Agrawal, Manjari

    2014-12-01

    Vinyl polysiloxane (VPS) impression materials have application in a wide variety of situations in both fixed and removable prosthodontics. A major limitation of VPS impression materials is their hydrophobicity. There are two aspects of this problem, the wettability of the polymerized impression by dental gypsum materials and the ability of the unpolymerized material to wet intraoral tissues. To address this problem, manufacturers have added surfactants and labelled these new products as "hydrophilic vinyl polysiloxane." The purpose of this study was to evaluate and compare dimensional accuracy and surface detail reproduction of four hydrophilic VPS impression materials, when used under dry, moist, and wet conditions. A total of 180 samples were made of stainless steel die similar to as described in ADA sp. no. 19. The die was scored with three horizontal and two vertical lines. Impressions were made under dry, moist and wet conditions. Dimensional accuracy was measured by comparing the length of the middle horizontal line in each impression to the same line on the metal die, by using Universal Length Measuring machine. A 2-way ANOVA was performed on the percentage change data for measured lengths of the 4 impression materials under the 3 conditions to evaluate dimensional accuracy. Surface detail was evaluated in two ways: (1) by use of criteria similar to ADA sp. no. 19 for detail reproduction, and (2) by use of a method that categorized the impressions as satisfactory or unsatisfactory based on their surface characteristics: presence of pits, voids, or roughness. Pearson X2 (α = 0.05) was used to compare surface detail reproduction results. Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of all the four material. With both surface detail analyses, dry, moist, and wet conditions had a significant effect on the detail reproduction of all the four materials (P < 0.05). The study concluded that the

  12. Orbit accuracy assessment for Seasat

    NASA Technical Reports Server (NTRS)

    Schutz, B. E.; Tapley, B. D.

    1980-01-01

    Laser range measurements are used to determine the orbit of Seasat during the period from July 28, 1978, to Aug. 14, 1978, and the influence of the gravity field, atmospheric drag, and solar radiation pressure on the orbit accuracy is investigated. It is noted that for the orbits of three-day duration, little distinction can be made between the influence of different atmospheric models. It is found that the special Seasat gravity field PGS-S3 is most consistent with the data for three-day orbits, but an unmodeled systematic effect in radiation pressure is noted. For orbits of 18-day duration, little distinction can be made between the results derived from the PGS gravity fields. It is also found that the geomagnetic field is an influential factor in the atmospheric modeling during this time period. Seasat altimeter measurements are used to determine the accuracy of the altimeter measurement time tag and to evaluate the orbital accuracy.

  13. Screening for Depression in the General Population with the Center for Epidemiologic Studies Depression (CES-D): A Systematic Review with Meta-Analysis

    PubMed Central

    Vilagut, Gemma; Forero, Carlos G.; Barbaglia, Gabriela; Alonso, Jordi

    2016-01-01

    Objective We aimed to collect and meta-analyse the existing evidence regarding the performance of the Center for Epidemiologic Studies Depression (CES-D) for detecting depression in general population and primary care settings. Method Systematic literature search in PubMed and PsychINFO. Eligible studies were: a) validation studies of screening questionnaires with information on the accuracy of the CES-D; b) samples from general populations or primary care settings; c) standardized diagnostic interviews following standard classification systems used as gold standard; and d) English or Spanish language of publication. Pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratio were estimated for several cut-off points using bivariate mixed effects models for each threshold. The summary receiver operating characteristic curve was estimated with Rutter and Gatsonis mixed effects models; area under the curve was calculated. Quality of the studies was assessed with the QUADAS tool. Causes of heterogeneity were evaluated with the Rutter and Gatsonis mixed effects model including each covariate at a time. Results 28 studies (10,617 participants) met eligibility criteria. The median prevalence of Major Depression was 8.8% (IQ range from 3.8% to 12.6%). The overall area under the curve was 0.87. At the cut-off 16, sensitivity was 0.87 (95% CI: 0.82–0.92), specificity 0.70 (95% CI: 0.65–0.75), and DOR 16.2 (95% CI: 10.49–25.10). Better trade-offs between sensitivity and specificity were observed (Sensitivity = 0.83, Specificity = 0.78, diagnostic odds ratio = 16.64) for cut-off 20. None of the variables assessed as possible sources of heterogeneity was found to be statistically significant. Conclusion The CES-D has acceptable screening accuracy in the general population or primary care settings, but it should not be used as an isolated diagnostic measure of depression. Depending on the test objectives, the cut-off 20 may be more adequate than the value

  14. Improving Speaking Accuracy through Awareness

    ERIC Educational Resources Information Center

    Dormer, Jan Edwards

    2013-01-01

    Increased English learner accuracy can be achieved by leading students through six stages of awareness. The first three awareness stages build up students' motivation to improve, and the second three provide learners with crucial input for change. The final result is "sustained language awareness," resulting in ongoing…

  15. Multi-Reader Multi-Case Studies Using the Area under the Receiver Operator Characteristic Curve as a Measure of Diagnostic Accuracy: Systematic Review with a Focus on Quality of Data Reporting

    PubMed Central

    Dendumrongsup, Thaworn; Plumb, Andrew A.; Halligan, Steve; Fanshawe, Thomas R.; Altman, Douglas G.; Mallett, Susan

    2014-01-01

    Introduction We examined the design, analysis and reporting in multi-reader multi-case (MRMC) research studies using the area under the receiver-operating curve (ROC AUC) as a measure of diagnostic performance. Methods We performed a systematic literature review from 2005 to 2013 inclusive to identify a minimum 50 studies. Articles of diagnostic test accuracy in humans were identified via their citation of key methodological articles dealing with MRMC ROC AUC. Two researchers in consensus then extracted information from primary articles relating to study characteristics and design, methods for reporting study outcomes, model fitting, model assumptions, presentation of results, and interpretation of findings. Results were summarized and presented with a descriptive analysis. Results Sixty-four full papers were retrieved from 475 identified citations and ultimately 49 articles describing 51 studies were reviewed and extracted. Radiological imaging was the index test in all. Most studies focused on lesion detection vs. characterization and used less than 10 readers. Only 6 (12%) studies trained readers in advance to use the confidence scale used to build the ROC curve. Overall, description of confidence scores, the ROC curve and its analysis was often incomplete. For example, 21 (41%) studies presented no ROC curve and only 3 (6%) described the distribution of confidence scores. Of 30 studies presenting curves, only 4 (13%) presented the data points underlying the curve, thereby allowing assessment of extrapolation. The mean change in AUC was 0.05 (−0.05 to 0.28). Non-significant change in AUC was attributed to underpowering rather than the diagnostic test failing to improve diagnostic accuracy. Conclusions Data reporting in MRMC studies using ROC AUC as an outcome measure is frequently incomplete, hampering understanding of methods and the reliability of results and study conclusions. Authors using this analysis should be encouraged to provide a full description of

  16. Accuracy of Digital vs. Conventional Implant Impressions

    PubMed Central

    Lee, Sang J.; Betensky, Rebecca A.; Gianneschi, Grace E.; Gallucci, German O.

    2015-01-01

    The accuracy of digital impressions greatly influences the clinical viability in implant restorations. The aim of this study is to compare the accuracy of gypsum models acquired from the conventional implant impression to digitally milled models created from direct digitalization by three-dimensional analysis. Thirty gypsum and 30 digitally milled models impressed directly from a reference model were prepared. The models were scanned by a laboratory scanner and 30 STL datasets from each group were imported to an inspection software. The datasets were aligned to the reference dataset by a repeated best fit algorithm and 10 specified contact locations of interest were measured in mean volumetric deviations. The areas were pooled by cusps, fossae, interproximal contacts, horizontal and vertical axes of implant position and angulation. The pooled areas were statistically analysed by comparing each group to the reference model to investigate the mean volumetric deviations accounting for accuracy and standard deviations for precision. Milled models from digital impressions had comparable accuracy to gypsum models from conventional impressions. However, differences in fossae and vertical displacement of the implant position from the gypsum and digitally milled models compared to the reference model, exhibited statistical significance (p<0.001, p=0.020 respectively). PMID:24720423

  17. Bullet trajectory reconstruction - Methods, accuracy and precision.

    PubMed

    Mattijssen, Erwin J A T; Kerkhoff, Wim

    2016-05-01

    Based on the spatial relation between a primary and secondary bullet defect or on the shape and dimensions of the primary bullet defect, a bullet's trajectory prior to impact can be estimated for a shooting scene reconstruction. The accuracy and precision of the estimated trajectories will vary depending on variables such as, the applied method of reconstruction, the (true) angle of incidence, the properties of the target material and the properties of the bullet upon impact. This study focused on the accuracy and precision of estimated bullet trajectories when different variants of the probing method, ellipse method, and lead-in method are applied on bullet defects resulting from shots at various angles of incidence on drywall, MDF and sheet metal. The results show that in most situations the best performance (accuracy and precision) is seen when the probing method is applied. Only for the lowest angles of incidence the performance was better when either the ellipse or lead-in method was applied. The data provided in this paper can be used to select the appropriate method(s) for reconstruction and to correct for systematic errors (accuracy) and to provide a value of the precision, by means of a confidence interval of the specific measurement. PMID:27044032

  18. Accuracy investigation of phthalate metabolite standards.

    PubMed

    Langlois, Éric; Leblanc, Alain; Simard, Yves; Thellen, Claude

    2012-05-01

    Phthalates are ubiquitous compounds whose metabolites are usually determined in urine for biomonitoring studies. Following suspect and unexplained results from our laboratory in an external quality-assessment scheme, we investigated the accuracy of all phthalate metabolite standards in our possession by comparing them with those of several suppliers. Our findings suggest that commercial phthalate metabolite certified solutions are not always accurate and that lot-to-lot discrepancies significantly affect the accuracy of the results obtained with several of these standards. These observations indicate that the reliability of the results obtained from different lots of standards is not equal, which reduces the possibility of intra-laboratory and inter-laboratory comparisons of results. However, agreements of accuracy have been observed for a majority of neat standards obtained from different suppliers, which indicates that a solution to this issue is available. Data accuracy of phthalate metabolites should be of concern for laboratories performing phthalate metabolite analysis because of the standards used. The results of our investigation are presented from the perspective that laboratories performing phthalate metabolite analysis can obtain accurate and comparable results in the future. Our findings will contribute to improving the quality of future phthalate metabolite analyses and will affect the interpretation of past results.

  19. [Influence of the type of impression material, impression tray and making impression technology on the dimensional accuracy and depth of impression material penetration into "gingival sulcus". In vitro study].

    PubMed

    Riakhovskiĭ, A N; Muradov, M A

    2005-01-01

    Results of the profound study of influence of the type of impression material, impression tray and making impression technology upon main quality characteristics of the precise impression (dimensional accuracy and depth of impression material penetration into gingival sulcus) are reviewed. Original method to investigate depth of impression material penetration into gingival sulcus on experimental model is described. The impression technology exercises more influence on quality characteristics of the precise impression than type of the used material and impression tray. Optimal combination of different viscosity impression materials with technology of making impression has been defined.

  20. Dissociating Appraisals of Accuracy and Recollection in Autobiographical Remembering

    ERIC Educational Resources Information Center

    Scoboria, Alan; Pascal, Lisa

    2016-01-01

    Recent studies of metamemory appraisals implicated in autobiographical remembering have established distinct roles for judgments of occurrence, recollection, and accuracy for past events. In studies involving everyday remembering, measures of recollection and accuracy correlate highly (>.85). Thus although their measures are structurally…

  1. MAPPING SPATIAL THEMATIC ACCURACY WITH FUZZY SETS

    EPA Science Inventory

    Thematic map accuracy is not spatially homogenous but variable across a landscape. Properly analyzing and representing spatial pattern and degree of thematic map accuracy would provide valuable information for using thematic maps. However, current thematic map accuracy measures (...

  2. Accuracy of DXA scanning of the thoracic spine: cadaveric studies comparing BMC, areal BMD and geometric estimates of volumetric BMD against ash weight and CT measures of bone volume.

    PubMed

    Sran, Meena M; Khan, Karim M; Keiver, Kathy; Chew, Jason B; McKay, Heather A; Oxland, Thomas R

    2005-12-01

    Biomechanical studies of the thoracic spine often scan cadaveric segments by dual energy X-ray absorptiometry (DXA) to obtain measures of bone mass. Only one study has reported the accuracy of lateral scans of thoracic vertebral bodies. The accuracy of DXA scans of thoracic spine segments and of anterior-posterior (AP) thoracic scans has not been investigated. We have examined the accuracy of AP and lateral thoracic DXA scans by comparison with ash weight, the gold-standard for measuring bone mineral content (BMC). We have also compared three methods of estimating volumetric bone mineral density (vBMD) with a novel standard-ash weight (g)/bone volume (cm3) as measured by computed tomography (CT). Twelve T5-T8 spine segments were scanned with DXA (AP and lateral) and CT. The T6 vertebrae were excised, the posterior elements removed and then the vertebral bodies were ashed in a muffle furnace. We proposed a new method of estimating vBMD and compared it with two previously published methods. BMC values from lateral DXA scans displayed the strongest correlation with ash weight (r=0.99) and were on average 12.8% higher (p<0.001). As expected, BMC (AP or lateral) was more strongly correlated with ash weight than areal bone mineral density (aBMD; AP: r=0.54, or lateral: r=0.71) or estimated vBMD. Estimates of vBMD with either of the three methods were strongly and similarly correlated with volumetric BMD calculated by dividing ash weight by CT-derived volume. These data suggest that readily available DXA scanning is an appropriate surrogate measure for thoracic spine bone mineral and that the lateral scan might be the scan method of choice. PMID:15616862

  3. The Relationship between Phonological Awareness and Word Reading Accuracy in Oriya and English: A Study of Oriya-Speaking Fifth-Graders

    ERIC Educational Resources Information Center

    Mishra, Ranjita; Stainthorp, Rhona

    2007-01-01

    This study investigated the relationships between phonological awareness and reading in Oriya and English. Oriya is the official language of Orissa, an eastern state of India. The writing system is an alphasyllabary. Ninety-nine fifth grade children (mean age 9 years 7 months) were assessed on measures of phonological awareness, word reading and…

  4. An Exploratory Study into Trade-Off Effects of Complexity, Accuracy, and Fluency on Young Learners' Oral Task Repetition

    ERIC Educational Resources Information Center

    Sample, Evelyn; Michel, Marije

    2014-01-01

    Studying task repetition for adult and young foreign language learners of English (EFL) has received growing interest in recent literature within the task-based approach (Bygate, 2009; Hawkes, 2012; Mackey, Kanganas, & Oliver, 2007; Pinter, 2007b). Earlier work suggests that second language (L2) learners benefit from repeating the same or a…

  5. Thermocouple Calibration and Accuracy in a Materials Testing Laboratory

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Nathal, M. V.; Keller, D. J.

    2002-01-01

    A consolidation of information has been provided that can be used to define procedures for enhancing and maintaining accuracy in temperature measurements in materials testing laboratories. These studies were restricted to type R and K thermocouples (TCs) tested in air. Thermocouple accuracies, as influenced by calibration methods, thermocouple stability, and manufacturer's tolerances were all quantified in terms of statistical confidence intervals. By calibrating specific TCs the benefits in accuracy can be as great as 6 C or 5X better compared to relying on manufacturer's tolerances. The results emphasize strict reliance on the defined testing protocol and on the need to establish recalibration frequencies in order to maintain these levels of accuracy.

  6. Rats' Visual-Spatial Working Memory: New Object Choice Accuracy as a Function of Number of Objects in the Study Array

    ERIC Educational Resources Information Center

    Cohen, Jerome; Han, Xue; Matei, Anca; Parameswaran, Varakini; Zuniga, Robert; Hlynka, Myron

    2010-01-01

    When rats had to find new (jackpot) objects for rewards from among previously sampled baited objects, increasing the number of objects in the sample (study) segment of a trial from 3 to 5 and then to 7 (Experiment 1) or from 3 to 6 and 9 (Experiments 2 and 3) or from 6 to 9 and 12 (Experiment 4) did not reduce rats' test segment performance.…

  7. The accuracy with which the 5 times sit-to-stand test, versus gait speed, can identify poor exercise tolerance in patients with COPD: A cross-sectional study.

    PubMed

    Bernabeu-Mora, Roberto; Medina-Mirapeix, Francesc; Llamazares-Herrán, Eduardo; Oliveira-Sousa, Silvana Loana de; Sánchez-Martinez, M Piedad; Escolar-Reina, Pilar

    2016-08-01

    Identifying those patients who underperform in the 6-minute walk test (6MWT <350 m), and the reasons for their poor performance, is a major concern in the management of chronic obstructive pulmonary disease.To explore the accuracy and relevance of the 4-m gait-speed (4MGS) test, and the 5-repetition sit-to-stand (5STS) test, as diagnostic markers, and clinical determinants, of poor performance in the 6MWT.We recruited 137 patients with stable chronic obstructive pulmonary disease to participate in our cross-sectional study. Patients completed the 4MGS and 5STS tests, with quantitative (in seconds) and qualitative ordinal data collected; the latter were categorized using a scale of 0 to 4. The following potential covariates and clinical determinants of poor 6MWT were collated: age, quadriceps muscle-strength (QMS), health status, dyspnea, depression, and airflow limitation. Area under the receiver-operating characteristic curve data (AUC) was used to assess accuracy, with logistic regression used to explore relevance as clinical determinants.The AUCs generated using the 4MGS and 5STS tests were comparable, at 0.719 (95% confidence interval [CI] 0.629-0.809) and 0.711 (95% CI 0.613-0.809), respectively. With ordinal data, the 5STS test was most accurate (AUC of 0.732; 95% CI 0.645-0.819); the 4MGS test showed poor discriminatory power (AUC <0.7), although accuracy improved (0.726, 95% CI 0.637-0.816) when covariates were included. Unlike the 4MGS test, the 5STS test provided a significant clinical determinant of a poor 6MWT (odds ratio 1.23, 95% CI 1.05-1.44).The 5STS test reliably predicts a poor 6MWT, especially when using ordinal data. Used alone, the 4MGS test is reliable when measured with continuous data. PMID:27583918

  8. High accuracy flexural hinge development

    NASA Astrophysics Data System (ADS)

    Santos, I.; Ortiz de Zárate, I.; Migliorero, G.

    2005-07-01

    This document provides a synthesis of the technical results obtained in the frame of the HAFHA (High Accuracy Flexural Hinge Assembly) development performed by SENER (in charge of design, development, manufacturing and testing at component and mechanism levels) with EADS Astrium as subcontractor (in charge of doing an inventory of candidate applications among existing and emerging projects, establishing the requirements and perform system level testing) under ESA contract. The purpose of this project has been to develop a competitive technology for a flexural pivot, usuable in highly accurate and dynamic pointing/scanning mechanisms. Compared with other solutions (e.g. magnetic or ball bearing technologies) flexural hinges are the appropriate technology for guiding with accuracy a mobile payload over a limited angular ranges around one rotation axes.

  9. Monitoring Pharmacologically Induced Immunosuppression by Immune Repertoire Sequencing to Detect Acute Allograft Rejection in Heart Transplant Patients: A Proof-of-Concept Diagnostic Accuracy Study

    PubMed Central

    Valantine, Hannah A.; Penland, Lolita; Luikart, Helen; Strehl, Calvin; Cohen, Garrett; Khush, Kiran K.; Quake, Stephen R.

    2015-01-01

    Background It remains difficult to predict and to measure the efficacy of pharmacological immunosuppression. We hypothesized that measuring the B-cell repertoire would enable assessment of the overall level of immunosuppression after heart transplantation. Methods and Findings In this proof-of-concept study, we implemented a molecular-barcode-based immune repertoire sequencing assay that sensitively and accurately measures the isotype and clonal composition of the circulating B cell repertoire. We used this assay to measure the temporal response of the B cell repertoire to immunosuppression after heart transplantation. We selected a subset of 12 participants from a larger prospective cohort study (ClinicalTrials.gov NCT01985412) that is ongoing at Stanford Medical Center and for which enrollment started in March 2010. This subset of 12 participants was selected to represent post-heart-transplant events, with and without acute rejection (six participants with moderate-to-severe rejection and six without). We analyzed 130 samples from these patients, with an average follow-up period of 15 mo. Immune repertoire sequencing enables the measurement of a patient’s net state of immunosuppression (correlation with tacrolimus level, r = −0.867, 95% CI −0.968 to −0.523, p = 0.0014), as well as the diagnosis of acute allograft rejection, which is preceded by increased immune activity with a sensitivity of 71.4% (95% CI 30.3% to 94.9%) and a specificity of 82.0% (95% CI 72.1% to 89.1%) (cell-free donor-derived DNA as noninvasive gold standard). To illustrate the potential of immune repertoire sequencing to monitor atypical post-transplant trajectories, we analyzed two more patients, one with chronic infections and one with amyloidosis. A larger, prospective study will be needed to validate the power of immune repertoire sequencing to predict rejection events, as this proof-of-concept study is limited to a small number of patients who were selected based on several

  10. An Accuracy Assessment of the CALIOP/CALIPSO Version 2/Version 3 Daytime Aerosol Extinction Product Based on a Detailed Multi-Sensor, Multi-Platform Case Study

    NASA Technical Reports Server (NTRS)

    Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

    2011-01-01

    The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP s level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. spaceborne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth s Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP s low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth s surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP s extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case

  11. Comparison of the accuracy of patients' recall of the content of telephone and face-to-face consultations: an exploratory study.

    PubMed

    McKinstry, Brian; Watson, Philip; Elton, Robert A; Pinnock, Hilary; Kidd, Gillian; Meyer, Barbara; Logie, Robert; Sheikh, Aziz

    2011-06-01

    BACKGROUND To comply with an action plan patients need to recall information accurately. Little is known about how well patients recall consultations, particularly telephone consultations increasingly used to triage acute problems. PURPOSE OF STUDY This was an exploratory study to measure how accurately patients recall the content of face-to-face and telephone consultations and what factors may be associated with accurate recall. STUDY DESIGN In Scotland in 2008, the advice (diagnoses; management plan(s); and safety-netting arrangements) given in audio recorded face-to-face and telephone consultations was compared with the advice recalled by patients at interview approximately 13 days later. Patients also performed a memory test. Interactions were sought between accurate recall, consultation type, and factors postulated to influence recall. RESULTS Ten general practitioners (GPs) and 175 patients participated; 144 (82%) patients were interviewed. Patients recalled most important components of telephone and face-to-face consultations equally accurately or with only minor errors. Overall, patients presenting multiple problems (p<0.001), with brain injury (p<0.01) or low memory score (p<0.01) had reduced recall. GPs rarely used strategies to improve recall; however, these were not associated with improved recall. CONCLUSIONS Contrary to previous hospital based research, patients tended to remember important components of both face-to-face and telephone consultations-perhaps reflecting the familiar, less anxiety provoking environment of primary care. The unsuccessful use of strategies to improve recall may reflect selective use in cognitively impaired patients. Clinicians should compensate for situations where recall is poorer such as patients presenting multiple problems or with brain injury. Patients might be advised to restrict the number of problems they present in any one consultation.

  12. Phantom study and accuracy evaluation of an image-to-world registration approach used with electro-magnetic tracking system for neurosurgery

    NASA Astrophysics Data System (ADS)

    Li, Senhu; Sarment, David

    2015-12-01

    Minimally invasive neurosurgery needs intraoperative imaging updates and high efficient image guide system to facilitate the procedure. An automatic image guided system utilized with a compact and mobile intraoperative CT imager was introduced in this work. A tracking frame that can be easily attached onto the commercially available skull clamp was designed. With known geometry of fiducial and tracking sensor arranged on this rigid frame that was fabricated through high precision 3D printing, not only was an accurate, fully automatic registration method developed in a simple and less-costly approach, but also it helped in estimating the errors from fiducial localization in image space through image processing, and in patient space through the calibration of tracking frame. Our phantom study shows the fiducial registration error as 0.348+/-0.028mm, comparing the manual registration error as 1.976+/-0.778mm. The system in this study provided a robust and accurate image-to-patient registration without interruption of routine surgical workflow and any user interactions involved through the neurosurgery.

  13. Accuracy of self-reported versus measured weight over adolescence and young adulthood: findings from the national longitudinal study of adolescent health, 1996-2008.

    PubMed

    Clarke, Philippa; Sastry, Narayan; Duffy, Denise; Ailshire, Jennifer

    2014-07-15

    Many studies rely on self-reports to capture population trends and trajectories in weight gain over adulthood, but the validity of self-reports is often considered a limitation. The purpose of this work was to examine long-term trajectories of self-reporting bias in a national sample of American youth. With 3 waves of data from the National Longitudinal Study of Adolescent Health (1996-2008), we used growth curve models to examine self-reporting bias in trajectories of weight gain across adolescence and early adulthood (ages 13-32 years). We investigated whether self-reporting bias is constant over time, or whether adolescents become more accurate in reporting their weight as they move into young adulthood, and we examined differences in self-reporting bias by sex, race/ethnicity, and attained education. Adolescent girls underreported their weight by 0.86 kg on average, and this rate of underreporting increased over early adulthood. In contrast, we found no evidence that boys underreported their weight either in adolescence or over the early adult years. For young men, self-reports of weight were unbiased estimates of measured weight among all racial/ethnic and educational subpopulations over adolescence and early adulthood. PMID:24944288

  14. Accuracy of self-reported versus measured weight over adolescence and young adulthood: findings from the national longitudinal study of adolescent health, 1996-2008.

    PubMed

    Clarke, Philippa; Sastry, Narayan; Duffy, Denise; Ailshire, Jennifer

    2014-07-15

    Many studies rely on self-reports to capture population trends and trajectories in weight gain over adulthood, but the validity of self-reports is often considered a limitation. The purpose of this work was to examine long-term trajectories of self-reporting bias in a national sample of American youth. With 3 waves of data from the National Longitudinal Study of Adolescent Health (1996-2008), we used growth curve models to examine self-reporting bias in trajectories of weight gain across adolescence and early adulthood (ages 13-32 years). We investigated whether self-reporting bias is constant over time, or whether adolescents become more accurate in reporting their weight as they move into young adulthood, and we examined differences in self-reporting bias by sex, race/ethnicity, and attained education. Adolescent girls underreported their weight by 0.86 kg on average, and this rate of underreporting increased over early adulthood. In contrast, we found no evidence that boys underreported their weight either in adolescence or over the early adult years. For young men, self-reports of weight were unbiased estimates of measured weight among all racial/ethnic and educational subpopulations over adolescence and early adulthood.

  15. Accuracy of Self-Reported Versus Measured Weight Over Adolescence and Young Adulthood: Findings From the National Longitudinal Study of Adolescent Health, 1996–2008

    PubMed Central

    Clarke, Philippa; Sastry, Narayan; Duffy, Denise; Ailshire, Jennifer

    2014-01-01

    Many studies rely on self-reports to capture population trends and trajectories in weight gain over adulthood, but the validity of self-reports is often considered a limitation. The purpose of this work was to examine long-term trajectories of self-reporting bias in a national sample of American youth. With 3 waves of data from the National Longitudinal Study of Adolescent Health (1996–2008), we used growth curve models to examine self-reporting bias in trajectories of weight gain across adolescence and early adulthood (ages 13–32 years). We investigated whether self-reporting bias is constant over time, or whether adolescents become more accurate in reporting their weight as they move into young adulthood, and we examined differences in self-reporting bias by sex, race/ethnicity, and attained education. Adolescent girls underreported their weight by 0.86 kg on average, and this rate of underreporting increased over early adulthood. In contrast, we found no evidence that boys underreported their weight either in adolescence or over the early adult years. For young men, self-reports of weight were unbiased estimates of measured weight among all racial/ethnic and educational subpopulations over adolescence and early adulthood. PMID:24944288

  16. A dosimetric phantom study of dose accuracy and build-up effects using IMRT and RapidArc in stereotactic irradiation of lung tumours

    PubMed Central

    2012-01-01

    Background and purpose Stereotactic lung radiotherapy (SLRT) has emerged as a curative treatment for medically inoperable patients with early-stage non-small cell lung cancer (NSCLC) and the use of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc treatments (VMAT) have been proposed as the best practical approaches for the delivery of SLRT. However, a large number of narrow field shapes are needed in the dose delivery of intensity-modulated techniques and the probability of underdosing the tumour periphery increases as the effective field size is decreased. The purpose of this study was to evaluate small lung tumour doses irradiated by intensity-modulated techniques to understand the risk for dose calculation errors in precision radiotherapy such as SLRT. Materials and methods The study was executed with two heterogeneous phantoms with targets of Ø1.5 and Ø4.0 cm. Dose distributions in the simulated tumours delivered by small sliding window apertures (SWAs), IMRT and RapidArc treatment plans were measured with radiochromic film. Calculation algorithms of pencil beam convolution (PBC) and anisotropic analytic algorithm (AAA) were used to calculate the corresponding dose distributions. Results Peripheral doses of the tumours were decreased as SWA decreased, which was not modelled by the calculation algorithms. The smallest SWA studied was 2 mm, which reduced the 90% isodose line width by 4.2 mm with the Ø4.0 cm tumour as compared to open field irradiation. PBC was not able to predict the dose accurately as the gamma evaluation failed to meet the criteria of ±3%/±1 mm on average in 61% of the defined volume with the smaller tumour. With AAA the corresponding value was 16%. The dosimetric inaccuracy of AAA was within ±3% with the optimized treatment plans of IMRT and RapidArc. The exception was the clinical RapidArc plan with dose overestimation of 4%. Conclusions Overall, the peripheral doses of the simulated lung tumours were

  17. Accuracy of flow convergence estimates of mitral regurgitant flow rates obtained by use of multiple color flow Doppler M-mode aliasing boundaries: an experimental animal study.

    PubMed

    Zhang, J; Jones, M; Shandas, R; Valdes-Cruz, L M; Murillo, A; Yamada, I; Kang, S U; Weintraub, R G; Shiota, T; Sahn, D J

    1993-02-01

    The proximal flow convergence method of multiplying color Doppler aliasing velocity by flow convergence surface area has yielded a new means of quantifying flow rate by noninvasively derived measurements. Unlike previous methods of visualizing the turbulent jet of mitral regurgitation on color flow Doppler mapping, flow convergence methods are less influenced by machine factors because of the systematic structure of the laminar flow convergence region. However, recent studies have demonstrated that the flow rate calculated from the first aliasing boundary of color flow Doppler imaging is dependent on orifice size, flow rate, aliasing velocity and therefore on the distance from the orifice chosen for measurement. In this study we calculated the regurgitant flow rates acquired by use of multiple proximal aliasing boundaries on color Doppler M-mode traces and assessed the effect of distances of measurement and aliasing velocities on the calculated regurgitant flow rate. Six sheep with surgically induced mitral regurgitation were studied. The distances from the mitral valve leaflet M-mode line to the first, second, and third sequential aliasing boundaries on color Doppler M-mode traces were measured and converted to the regurgitant flow rates calculated by applying the hemispheric flow equation and averaging instantaneous flow rates throughout systole. The flow rates that were calculated from the first, second, and third aliasing boundaries correlated well with the actual regurgitant flow rates (r = 0.91 to 0.96). The mean percentage error from the actual flow rates were 151% for the first aliasing boundary, 7% for the second aliasing boundary, and -43% for the third aliasing boundary; and the association between aliasing velocities and calculated flow rates indicates an inverse relationship, which suggests that in this model, there were limited velocity-distance combinations that fit with a hemispheric assumption for flow convergence geometry. The second aliasing

  18. Diagnostic accuracy and use of non-mydriatic ocular fundus photography by emergency department physicians: Phase II of the FOTO-ED study

    PubMed Central

    Bruce, Beau B.; Thulasi, Praneetha; Fraser, Clare L.; Keadey, Matthew T.; Ward, Antoinette; Heilpern, Katherine L.; Wright, David W.; Newman, Nancy J.; Biousse, Valérie

    2013-01-01

    Objective During the first phase of the FOTO-ED Study, 13% (44/350;95%CI:9–17%) of patients had an ocular fundus finding, such as papilledema, relevant to their emergency department (ED) management found by non-mydriatic ocular fundus photography reviewed by neuro-opthalmologists. All of these findings were missed by ED physicians (EPs), who only examined 14% of enrolled patients by direct ophthalmoscopy. In the present study, we evaluated the sensitivity of non-mydriatic ocular fundus photography, an alternative to direct ophthalmoscopy, for relevant findings when photographs were made available for use by EPs during routine clinical care. Methods 354 patients presenting to our ED with headache, focal neurologic deficit, visual change, or diastolic blood pressure ≥120 mmHg had non-mydriatic fundus photography obtained (Kowa nonmyd-alpha-D). Photographs were placed on the electronic medical record for EPs review. Identification of relevant findings on photographs by EPs was compared to a reference standard of neuro-ophthalmologist review. Results EPs reviewed photographs of 239 patients (68%). 35 patients (10%;95%CI:7–13%) had relevant findings identified by neuro-ophthalmologist review (6 disc edema, 6 grade III/IV hypertensive retinopathy, 7 isolated hemorrhages, 15 optic disc pallor, and 1 retinal vascular occlusion). EPs identified 16/35 relevant findings (sensitivity:46%;95%CI:29–63%), and also identified 289/319 normal findings (specificity:96%; 95%CI:87–94%). EPs reported that photographs were helpful for 125 patients (35%). Conclusions EPs used non-mydriatic fundus photographs more frequently than they perform direct ophthalmoscopy, and their detection of relevant abnormalities improved. Ocular fundus photography often assisted ED care even when normal. Non-mydriatic ocular fundus photography offers a promising alternative to direct ophthalmoscopy. PMID:23433654

  19. Identification of benign and malignant thyroid nodules by in vivo iodine concentration measurement using single-source dual energy CT: A retrospective diagnostic accuracy study.

    PubMed

    Gao, Shun-Yu; Zhang, Xiao-Yan; Wei, Wei; Li, Xiao-Ting; Li, Yan-Ling; Xu, Min; Sun, Ying-Shi; Zhang, Xiao-Peng

    2016-09-01

    This study proposed to determine whether in vivo iodine concentration measurement by single-source dual energy (SSDE) CT can improve differentiation between benign and malignant thyroid nodules. In total, 53 patients presenting with thyroid nodules underwent SSDE CT scanning. Iodine concentrations were measured for each nodule and normal thyroid tissue using the GSI-viewer image analysis software. A total of 26 thyroid nodules were malignant in 26 patients and confirmed by surgery; 33 nodules from 27 patients were benign, with 10 confirmed by surgery and others after follow-up. Iodine concentrations with plain CT were significantly lower in malignant than benign nodules (0.47 ± 0.20 vs 1.17 ± 0.38 mg/mL, P = 0.00). Receiver operating characteristic (ROC) curve showed an area under the curve (AUC) of 0.93; with a cutoff of 0.67, iodine concentration showed 92.3% sensitivity and 88.5% specificity in diagnosing malignancy. Iodine concentration obtained by enhanced and plain CT were significantly higher in malignant than benign nodules (9.05 ± 3.35 vs 3.46 ± 2.24 mg/mL, P = 0.00). ROC curve analysis showed an AUC of 0.93; with a cutoff value of 3.37, iodine concentration displayed 78% sensitivity, 95% specificity in diagnosing malignancy. Combining unenhanced with enhanced iodine concentrations, the diagnostic equation was: Y = -8.641 × unenhanced iodine concentration + 0.663 × iodine concentration. ROC curve showed an AUC of 0.98 (95% CI, 0.94, 1.00). With Y ≥ -2 considered malignancy, diagnostic sensitivity and specificity were 96%, 96.3%, respectively. This study concluded that SSDE CT can detect the differences in iodine uptake and blood supply between benign and malignant thyroid lesions. PMID:27684811

  20. Evaluation and comparison of the internal fit and marginal accuracy of base metal (nickelchromium) and zirconia copings before and after ceramic veneering: a sem study.

    PubMed

    Regish, K M; Sharma, D; Prithviraj, D R; Nair, A; Raghavan, R

    2013-03-01

    This study compares the internal fit and marginal adaptation of copy milled Zirconia copings with Nickel-Chromium (Ni-Cr) copings fabricated using a lost wax technique before and after ceramic veneering. A standardized metal master die simulating a prepared crown was fabricated and twenty impressions of the metal die were made and poured with die stone. Wax patterns were made on ten dies and cast while light cure resin patterns were made on the other ten dies for copy milling the Zirconia copings. Five specimens from each group were subjected to ceramic veneering. All the test specimens were luted on to the fresh dies, embedded in dental plaster, sectioned and image analysis done using scanning electron microscopy. Thereafter statistical analysis is done using student t-test. The linear measurements for internal fit and marginal discrepancy were increased for Zirconia compared with Ni-Cr copings. The difference in the values of all the specimens of all the groups were not statistically significant (P > 0.05) except the values comparing the internal fit of Zirconia and Ni-Cr copings before ceramic veneering (P < 0.001) which was statistically significant. The internal fit and marginal adaptability of Ni-Cr copings were found to be better than the Copy milled Zirconia copings but internal fit and marginal adaptability deteriorated after ceramic veneering. PMID:23682510

  1. Evaluation and comparison of the internal fit and marginal accuracy of base metal (nickelchromium) and zirconia copings before and after ceramic veneering: a sem study.

    PubMed

    Regish, K M; Sharma, D; Prithviraj, D R; Nair, A; Raghavan, R

    2013-03-01

    This study compares the internal fit and marginal adaptation of copy milled Zirconia copings with Nickel-Chromium (Ni-Cr) copings fabricated using a lost wax technique before and after ceramic veneering. A standardized metal master die simulating a prepared crown was fabricated and twenty impressions of the metal die were made and poured with die stone. Wax patterns were made on ten dies and cast while light cure resin patterns were made on the other ten dies for copy milling the Zirconia copings. Five specimens from each group were subjected to ceramic veneering. All the test specimens were luted on to the fresh dies, embedded in dental plaster, sectioned and image analysis done using scanning electron microscopy. Thereafter statistical analysis is done using student t-test. The linear measurements for internal fit and marginal discrepancy were increased for Zirconia compared with Ni-Cr copings. The difference in the values of all the specimens of all the groups were not statistically significant (P > 0.05) except the values comparing the internal fit of Zirconia and Ni-Cr copings before ceramic veneering (P < 0.001) which was statistically significant. The internal fit and marginal adaptability of Ni-Cr copings were found to be better than the Copy milled Zirconia copings but internal fit and marginal adaptability deteriorated after ceramic veneering.

  2. Magnesium-Cationic Dummy Atom Molecules Enhance Representation of DNA Polymerase β in Molecular Dynamics Simulations: Improved Accuracy in Studies of Structural Features and Mutational Effects

    PubMed Central

    Oelschlaeger, Peter; Klahn, Marco; Beard, William A.; Wilson, Samuel H.; Warshel, Arieh

    2007-01-01

    Summary Human DNA polymerase β (pol β) fills gaps in DNA as part of base excision DNA repair. Due to its small size it is a convenient model enzyme for other DNA polymerases. Its active site contains two Mg2+ ions, of which one binds an incoming dNTP and one catalyzes its condensation with the DNA primer strand. Simulating such binuclear metalloenzymes accurately but computationally efficiently is a challenging task. Here, we present a magnesium-cationic dummy atom approach that can easily be implemented in molecular mechanical force fields such as the ENZYMIX or the AMBER force fields. All properties investigated in this paper, that is, structure and energetics of both Michaelis complexes and transition state (TS) complexes were represented more accurately using the magnesium-cationic dummy atom model than using the traditional one-atom representation for Mg2+ ions. The improved agreement between calculated free energies of binding of TS models to different pol β variants and the experimentally determined activation free energies indicates that this model will be useful in studying mutational effects on catalytic efficiency and fidelity of DNA polymerases. The model should also have broad applicability to the modeling of other magnesium-containing proteins. PMID:17174326

  3. Students' Accuracy of Measurement Estimation: Context, Units, and Logical Thinking

    ERIC Educational Resources Information Center

    Jones, M. Gail; Gardner, Grant E.; Taylor, Amy R.; Forrester, Jennifer H.; Andre, Thomas

    2012-01-01

    This study examined students' accuracy of measurement estimation for linear distances, different units of measure, task context, and the relationship between accuracy estimation and logical thinking. Middle school students completed a series of tasks that included estimating the length of various objects in different contexts and completed a test…

  4. Assessment Of Accuracies Of Remote-Sensing Maps

    NASA Technical Reports Server (NTRS)

    Card, Don H.; Strong, Laurence L.

    1992-01-01

    Report describes study of accuracies of classifications of picture elements in map derived by digital processing of Landsat-multispectral-scanner imagery of coastal plain of Arctic National Wildlife Refuge. Accuracies of portions of map analyzed with help of statistical sampling procedure called "stratified plurality sampling", in which all picture elements in given cluster classified in stratum to which plurality of them belong.

  5. ACCURACY OF INTERPERSONAL PERCEPTION--A FUNCTION OF SUPERORDINATE ROLE.

    ERIC Educational Resources Information Center

    BRUMBAUGH, ROBERT B.

    ONE ASPECT OF THE PERCEPTUAL ACCURACY OF STUDENT TEACHERS AND THEIR SUPERVISORS IN JUDGING THEIR INTERPERSONAL RELATIONS WAS EXPLORED. A FIELD STUDY OF 40 STUDENT TEACHERS AND THEIR PUBLIC SCHOOL SUPERVISING TEACHERS EXPLORED THE POSSIBILITY OF SUBORDINATE ROLE BEING A CORRELATE TO THE ACCURACY OF THEIR INTERPERSONAL PERCEPTION. AT THE END OF 6…

  6. Accuracy in Detecting Truths and Lies: Documenting the "Veracity Effect."

    ERIC Educational Resources Information Center

    Levine, Timothy R.; Park, Hee Sun; McCornack, Steven A.

    1999-01-01

    Conducts four studies on detecting truth and lies. Suggest that the single best predictor of detection accuracy may be the veracity of message being judged. Finds that truths are judged with substantially greater accuracy than lies. Findings suggest that there is a need for reassessment of many commonly held conclusions about deceptive…

  7. Task-Based Variability in Children's Singing Accuracy

    ERIC Educational Resources Information Center

    Nichols, Bryan E.

    2013-01-01

    The purpose of this study was to explore task-based variability in children's singing accuracy performance. The research questions were: Does children's singing accuracy vary based on the nature of the singing assessment employed? Is there a hierarchy of difficulty and discrimination ability among singing assessment tasks? What is the…

  8. The Accuracy of Self-Reported High School Grades

    ERIC Educational Resources Information Center

    Jung, Steven M.; Moore, James C.

    1970-01-01

    In a study to investigate accuracy of self-reported grades, length of time between testing and high school graduation was apparently the reason for a significant loss in accuracy in recalling grade reports of highschool graduates and college applicants who had been out of school for more than one year. (IR)

  9. Recognition accuracy by experienced men and women players of basketball.

    PubMed

    Millslagle, Duane G

    2002-08-01

    This study examined 30 experienced basketball players' recognition accuracy by sex, playing position (guard, forward, and center), and situations in the game of basketball. The study used a perceptual cognitive paradigm in which subjects viewed slides of structured and unstructured game situations and accurately recognized the presence or absence of the basketball. A significant difference in recognition accuracy by sex, players' position, and structure of the game situation was found. Male players' recognition accuracy was better than the female players'. The recognition accuracy of subjects who played guard was better than that of subjects who played forward or center. The players' recognition accuracy was more accurate when observing structured plays versus unstructured plays. The conclusion of this study suggested that experienced basketball players differ in their cognitive and visual searching processes by sex and player position within the sport of basketball.

  10. Do saccharide doped PAGAT dosimeters increase accuracy?

    NASA Astrophysics Data System (ADS)

    Berndt, B.; Skyt, P. S.; Holloway, L.; Hill, R.; Sankar, A.; De Deene, Y.

    2015-01-01

    To improve the dosimetric accuracy of normoxic polyacrylamide gelatin (PAGAT) gel dosimeters, the addition of saccharides (glucose and sucrose) has been suggested. An increase in R2-response sensitivity upon irradiation will result in smaller uncertainties in the derived dose if all other uncertainties are conserved. However, temperature variations during the magnetic resonance scanning of polymer gels result in one of the highest contributions to dosimetric uncertainties. The purpose of this project was to study the dose sensitivity against the temperature sensitivity. The overall dose uncertainty of PAGAT gel dosimeters with different concentrations of saccharides (0, 10 and 20%) was investigated. For high concentrations of glucose or sucrose, a clear improvement of the dose sensitivity was observed. For doses up to 6 Gy, the overall dose uncertainty was reduced up to 0.3 Gy for all saccharide loaded gels compared to PAGAT gel. Higher concentrations of glucose and sucrose deteriorate the accuracy of PAGAT dosimeters for doses above 9 Gy.

  11. Accuracy of NHANES periodontal examination protocols.

    PubMed

    Eke, P I; Thornton-Evans, G O; Wei, L; Borgnakke, W S; Dye, B A

    2010-11-01

    This study evaluates the accuracy of periodontitis prevalence determined by the National Health and Nutrition Examination Survey (NHANES) partial-mouth periodontal examination protocols. True periodontitis prevalence was determined in a new convenience sample of 454 adults ≥ 35 years old, by a full-mouth "gold standard" periodontal examination. This actual prevalence was compared with prevalence resulting from analysis of the data according to the protocols of NHANES III and NHANES 2001-2004, respectively. Both NHANES protocols substantially underestimated the prevalence of periodontitis by 50% or more, depending on the periodontitis case definition used, and thus performed below threshold levels for moderate-to-high levels of validity for surveillance. Adding measurements from lingual or interproximal sites to the NHANES 2001-2004 protocol did not improve the accuracy sufficiently to reach acceptable sensitivity thresholds. These findings suggest that NHANES protocols produce high levels of misclassification of periodontitis cases and thus have low validity for surveillance and research.

  12. Positional Accuracy Assessment of Googleearth in Riyadh

    NASA Astrophysics Data System (ADS)

    Farah, Ashraf; Algarni, Dafer

    2014-06-01

    Google Earth is a virtual globe, map and geographical information program that is controlled by Google corporation. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. With millions of users all around the globe, GoogleEarth® has become the ultimate source of spatial data and information for private and public decision-support systems besides many types and forms of social interactions. Many users mostly in developing countries are also using it for surveying applications, the matter that raises questions about the positional accuracy of the Google Earth program. This research presents a small-scale assessment study of the positional accuracy of GoogleEarth® Imagery in Riyadh; capital of Kingdom of Saudi Arabia (KSA). The results show that the RMSE of the GoogleEarth imagery is 2.18 m and 1.51 m for the horizontal and height coordinates respectively.

  13. Influence of the Accuracy of Angiography-Based Reconstructions on Velocity and Wall Shear Stress Computations in Coronary Bifurcations: A Phantom Study

    PubMed Central

    Schrauwen, Jelle T. C.; Karanasos, Antonios; van Ditzhuijzen, Nienke S.; Aben, Jean-Paul; van der Steen, Antonius F. W.

    2015-01-01

    Introduction Wall shear stress (WSS) plays a key role in the onset and progression of atherosclerosis in human coronary arteries. Especially sites with low and oscillating WSS near bifurcations have a higher propensity to develop atherosclerosis. WSS computations in coronary bifurcations can be performed in angiography-based 3D reconstructions. It is essential to evaluate how reconstruction errors influence WSS computations in mildly-diseased coronary bifurcations. In mildly-diseased lesions WSS could potentially provide more insight in plaque progression. Materials Methods Four Plexiglas phantom models of coronary bifurcations were imaged with bi-plane angiography. The lumens were segmented by two clinically experienced readers. Based on the segmentations 3D models were generated. This resulted in three models per phantom: one gold-standard from the phantom model itself, and one from each reader. Steady-state and transient simulations were performed with computational fluid dynamics to compute the WSS. A similarity index and a noninferiority test were used to compare the WSS in the phantoms and their reconstructions. The margin for this test was based on the resolution constraints of angiography. Results The reconstruction errors were similar to previously reported data; in seven out of eight reconstructions less than 0.10 mm. WSS in the regions proximal and far distal of the stenosis showed a good agreement. However, the low WSS areas directly distal of the stenosis showed some disagreement between the phantoms and the readers. This was due to small deviations in the reconstruction of the stenosis that caused differences in the resulting jet, and consequently the size and location of the low WSS area. Discussion This study showed that WSS can accurately be computed within angiography-based 3D reconstructions of coronary arteries with early stage atherosclerosis. Qualitatively, there was a good agreement between the phantoms and the readers. Quantitatively, the

  14. Interpersonal Deception: V. Accuracy in Deception Detection.

    ERIC Educational Resources Information Center

    Burgoon, Judee K.; And Others

    1994-01-01

    Investigates the influence of several factors on accuracy in detecting truth and deceit. Found that accuracy was much higher on truth than deception, novices were more accurate than experts, accuracy depended on type of deception and whether suspicion was present or absent, suspicion impaired accuracy for experts, and questions strategy…

  15. Assessment of the Thematic Accuracy of Land Cover Maps

    NASA Astrophysics Data System (ADS)

    Höhle, J.

    2015-08-01

    Several land cover maps are generated from aerial imagery and assessed by different approaches. The test site is an urban area in Europe for which six classes (`building', `hedge and bush', `grass', `road and parking lot', `tree', `wall and car port') had to be derived. Two classification methods were applied (`Decision Tree' and `Support Vector Machine') using only two attributes (height above ground and normalized difference vegetation index) which both are derived from the images. The assessment of the thematic accuracy applied a stratified design and was based on accuracy measures such as user's and producer's accuracy, and kappa coefficient. In addition, confidence intervals were computed for several accuracy measures. The achieved accuracies and confidence intervals are thoroughly analysed and recommendations are derived from the gained experiences. Reliable reference values are obtained using stereovision, false-colour image pairs, and positioning to the checkpoints with 3D coordinates. The influence of the training areas on the results is studied. Cross validation has been tested with a few reference points in order to derive approximate accuracy measures. The two classification methods perform equally for five classes. Trees are classified with a much better accuracy and a smaller confidence interval by means of the decision tree method. Buildings are classified by both methods with an accuracy of 99% (95% CI: 95%-100%) using independent 3D checkpoints. The average width of the confidence interval of six classes was 14% of the user's accuracy.

  16. Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

    PubMed Central

    Alex, Deepa; Shetty, Y. Bharath; Miranda, Glynis Anita; Prabhu, M. Bharath; Karkera, Reshma

    2015-01-01

    shown the least vertical marginal discrepancies among the four methods evaluated in this study. PMID:26929488

  17. Determining gas-meter accuracy

    SciTech Connect

    Valenti, M.

    1997-03-01

    This article describes how engineers at the Metering Research Facility are helping natural-gas companies improve pipeline efficiency by evaluating and refining the instruments used for measuring and setting prices. Accurate metering of natural gas is more important than ever as deregulation subjects pipeline companies to competition. To help improve that accuracy, the Gas Research Institute (GRI) in Chicago has sponsored the Metering Research Facility (MRF) at the Southwest Research Institute (SWRI) in San Antonio, Tex. The MRF evaluates and improves the performance of orifice, turbine, diaphragm, and ultrasonic meters as well as the gas-sampling methods that pipeline companies use to measure the flow of gas and determine its price.

  18. On the Accuracy of Genomic Selection

    PubMed Central

    Rabier, Charles-Elie; Barre, Philippe; Asp, Torben; Charmet, Gilles; Mangin, Brigitte

    2016-01-01

    Genomic selection is focused on prediction of breeding values of selection candidates by means of high density of markers. It relies on the assumption that all quantitative trait loci (QTLs) tend to be in strong linkage disequilibrium (LD) with at least one marker. In this context, we present theoretical results regarding the accuracy of genomic selection, i.e., the correlation between predicted and true breeding values. Typically, for individuals (so-called test individuals), breeding values are predicted by means of markers, using marker effects estimated by fitting a ridge regression model to a set of training individuals. We present a theoretical expression for the accuracy; this expression is suitable for any configurations of LD between QTLs and markers. We also introduce a new accuracy proxy that is free of the QTL parameters and easily computable; it outperforms the proxies suggested in the literature, in particular, those based on an estimated effective number of independent loci (Me). The theoretical formula, the new proxy, and existing proxies were compared for simulated data, and the results point to the validity of our approach. The calculations were also illustrated on a new perennial ryegrass set (367 individuals) genotyped for 24,957 single nucleotide polymorphisms (SNPs). In this case, most of the proxies studied yielded similar results because of the lack of markers for coverage of the entire genome (2.7 Gb). PMID:27322178

  19. Piezoresistive position microsensors with ppm-accuracy

    NASA Astrophysics Data System (ADS)

    Stavrov, Vladimir; Shulev, Assen; Stavreva, Galina; Todorov, Vencislav

    2015-05-01

    In this article, the relation between position accuracy and the number of simultaneously measured values, such as coordinates, has been analyzed. Based on this, a conceptual layout of MEMS devices (microsensors) for multidimensional position monitoring comprising a single anchored and a single actuated part has been developed. Both parts are connected with a plurality of micromechanical flexures, and each flexure includes position detecting cantilevers. Microsensors having detecting cantilevers oriented in X and Y direction have been designed and prototyped. Experimentally measured results at characterization of 1D, 2D and 3D position microsensors are reported as well. Exploiting different flexure layouts, a travel range between 50μm and 1.8mm and sensors' sensitivity in the range between 30μV/μm and 5mV/μm@ 1V DC supply voltage have been demonstrated. A method for accurate calculation of all three Cartesian coordinates, based on measurement of at least three microsensors' signals has also been described. The analyses of experimental results prove the capability of position monitoring with ppm-(part per million) accuracy. The technology for fabrication of MEMS devices with sidewall embedded piezoresistors removes restrictions in strong improvement of their usability for position sensing with a high accuracy. The present study is, also a part of a common strategy for developing a novel MEMS-based platform for simultaneous accurate measurement of various physical values when they are transduced to a change of position.

  20. Arizona Vegetation Resource Inventory (AVRI) accuracy assessment

    USGS Publications Warehouse

    Szajgin, John; Pettinger, L.R.; Linden, D.S.; Ohlen, D.O.

    1982-01-01

    A quantitative accuracy assessment was performed for the vegetation classification map produced as part of the Arizona Vegetation Resource Inventory (AVRI) project. This project was a cooperative effort between the Bureau of Land Management (BLM) and the Earth Resources Observation Systems (EROS) Data Center. The objective of the accuracy assessment was to estimate (with a precision of ?10 percent at the 90 percent confidence level) the comission error in each of the eight level II hierarchical vegetation cover types. A stratified two-phase (double) cluster sample was used. Phase I consisted of 160 photointerpreted plots representing clusters of Landsat pixels, and phase II consisted of ground data collection at 80 of the phase I cluster sites. Ground data were used to refine the phase I error estimates by means of a linear regression model. The classified image was stratified by assigning each 15-pixel cluster to the stratum corresponding to the dominant cover type within each cluster. This method is known as stratified plurality sampling. Overall error was estimated to be 36 percent with a standard error of 2 percent. Estimated error for individual vegetation classes ranged from a low of 10 percent ?6 percent for evergreen woodland to 81 percent ?7 percent for cropland and pasture. Total cost of the accuracy assessment was $106,950 for the one-million-hectare study area. The combination of the stratified plurality sampling (SPS) method of sample allocation with double sampling provided the desired estimates within the required precision levels. The overall accuracy results confirmed that highly accurate digital classification of vegetation is difficult to perform in semiarid environments, due largely to the sparse vegetation cover. Nevertheless, these techniques show promise for providing more accurate information than is presently available for many BLM-administered lands.

  1. Knowledge discovery by accuracy maximization.

    PubMed

    Cacciatore, Stefano; Luchinat, Claudio; Tenori, Leonardo

    2014-04-01

    Here we describe KODAMA (knowledge discovery by accuracy maximization), an unsupervised and semisupervised learning algorithm that performs feature extraction from noisy and high-dimensional data. Unlike other data mining methods, the peculiarity of KODAMA is that it is driven by an integrated procedure of cross-validation of the results. The discovery of a local manifold's topology is led by a classifier through a Monte Carlo procedure of maximization of cross-validated predictive accuracy. Briefly, our approach differs from previous methods in that it has an integrated procedure of validation of the results. In this way, the method ensures the highest robustness of the obtained solution. This robustness is demonstrated on experimental datasets of gene expression and metabolomics, where KODAMA compares favorably with other existing feature extraction methods. KODAMA is then applied to an astronomical dataset, revealing unexpected features. Interesting and not easily predictable features are also found in the analysis of the State of the Union speeches by American presidents: KODAMA reveals an abrupt linguistic transition sharply separating all post-Reagan from all pre-Reagan speeches. The transition occurs during Reagan's presidency and not from its beginning.

  2. High accuracy time transfer synchronization

    NASA Technical Reports Server (NTRS)

    Wheeler, Paul J.; Koppang, Paul A.; Chalmers, David; Davis, Angela; Kubik, Anthony; Powell, William M.

    1995-01-01

    In July 1994, the U.S. Naval Observatory (USNO) Time Service System Engineering Division conducted a field test to establish a baseline accuracy for two-way satellite time transfer synchronization. Three Hewlett-Packard model 5071 high performance cesium frequency standards were transported from the USNO in Washington, DC to Los Angeles, California in the USNO's mobile earth station. Two-Way Satellite Time Transfer links between the mobile earth station and the USNO were conducted each day of the trip, using the Naval Research Laboratory(NRL) designed spread spectrum modem, built by Allen Osborne Associates(AOA). A Motorola six channel GPS receiver was used to track the location and altitude of the mobile earth station and to provide coordinates for calculating Sagnac corrections for the two-way measurements, and relativistic corrections for the cesium clocks. This paper will discuss the trip, the measurement systems used and the results from the data collected. We will show the accuracy of using two-way satellite time transfer for synchronization and the performance of the three HP 5071 cesium clocks in an operational environment.

  3. Knowledge discovery by accuracy maximization

    PubMed Central

    Cacciatore, Stefano; Luchinat, Claudio; Tenori, Leonardo

    2014-01-01

    Here we describe KODAMA (knowledge discovery by accuracy maximization), an unsupervised and semisupervised learning algorithm that performs feature extraction from noisy and high-dimensional data. Unlike other data mining methods, the peculiarity of KODAMA is that it is driven by an integrated procedure of cross-validation of the results. The discovery of a local manifold’s topology is led by a classifier through a Monte Carlo procedure of maximization of cross-validated predictive accuracy. Briefly, our approach differs from previous methods in that it has an integrated procedure of validation of the results. In this way, the method ensures the highest robustness of the obtained solution. This robustness is demonstrated on experimental datasets of gene expression and metabolomics, where KODAMA compares favorably with other existing feature extraction methods. KODAMA is then applied to an astronomical dataset, revealing unexpected features. Interesting and not easily predictable features are also found in the analysis of the State of the Union speeches by American presidents: KODAMA reveals an abrupt linguistic transition sharply separating all post-Reagan from all pre-Reagan speeches. The transition occurs during Reagan’s presidency and not from its beginning. PMID:24706821

  4. High accuracy time transfer synchronization

    NASA Astrophysics Data System (ADS)

    Wheeler, Paul J.; Koppang, Paul A.; Chalmers, David; Davis, Angela; Kubik, Anthony; Powell, William M.

    1995-05-01

    In July 1994, the U.S. Naval Observatory (USNO) Time Service System Engineering Division conducted a field test to establish a baseline accuracy for two-way satellite time transfer synchronization. Three Hewlett-Packard model 5071 high performance cesium frequency standards were transported from the USNO in Washington, DC to Los Angeles, California in the USNO's mobile earth station. Two-Way Satellite Time Transfer links between the mobile earth station and the USNO were conducted each day of the trip, using the Naval Research Laboratory(NRL) designed spread spectrum modem, built by Allen Osborne Associates(AOA). A Motorola six channel GPS receiver was used to track the location and altitude of the mobile earth station and to provide coordinates for calculating Sagnac corrections for the two-way measurements, and relativistic corrections for the cesium clocks. This paper will discuss the trip, the measurement systems used and the results from the data collected. We will show the accuracy of using two-way satellite time transfer for synchronization and the performance of the three HP 5071 cesium clocks in an operational environment.

  5. Accuracy of a new patch pump based on a microelectromechanical system (MEMS) compared to other commercially available insulin pumps: results of the first in vitro and in vivo studies.

    PubMed

    Borot, Sophie; Franc, Sylvia; Cristante, Justine; Penfornis, Alfred; Benhamou, Pierre-Yves; Guerci, Bruno; Hanaire, Hélène; Renard, Eric; Reznik, Yves; Simon, Chantal; Charpentier, Guillaume

    2014-11-01

    The JewelPUMP™ (JP) is a new patch pump based on a microelectromechanical system that operates without any plunger. The study aimed to evaluate the infusion accuracy of the JP in vitro and in vivo. For the in vitro studies, commercially available pumps meeting the ISO standard were compared to the JP: the MiniMed® Paradigm® 712 (MP), Accu-Chek® Combo (AC), OmniPod® (OP), Animas® Vibe™ (AN). Pump accuracy was measured over 24 hours using a continuous microweighing method, at 0.1 and 1 IU/h basal rates. The occlusion alarm threshold was measured after a catheter occlusion. The JP, filled with physiological serum, was then tested in 13 patients with type 1 diabetes simultaneously with their own pump for 2 days. The weight difference was used to calculate the infused insulin volume. The JP showed reduced absolute median error rate in vitro over a 15-minute observation window compared to other pumps (1 IU/h): ±1.02% (JP) vs ±1.60% (AN), ±1.66% (AC), ±2.22% (MP), and ±4.63% (OP), P < .0001. But there was no difference over 24 hours. At 0.5 IU/h, the JP was able to detect an occlusion earlier than other pumps: 21 (19; 25) minutes vs 90 (85; 95), 58 (42; 74), and 143 (132; 218) minutes (AN, AC, MP), P < .05 vs AN and MP. In patients, the 24-hour flow error was not significantly different between the JP and usual pumps (-2.2 ± 5.6% vs -0.37 ± 4.0%, P = .25). The JP was found to be easier to wear than conventional pumps. The JP is more precise over a short time period, more sensitive to catheter occlusion, well accepted by patients, and consequently, of potential interest for a closed-loop insulin delivery system.

  6. Accuracy of a new patch pump based on a microelectromechanical system (MEMS) compared to other commercially available insulin pumps: results of the first in vitro and in vivo studies.

    PubMed

    Borot, Sophie; Franc, Sylvia; Cristante, Justine; Penfornis, Alfred; Benhamou, Pierre-Yves; Guerci, Bruno; Hanaire, Hélène; Renard, Eric; Reznik, Yves; Simon, Chantal; Charpentier, Guillaume

    2014-11-01

    The JewelPUMP™ (JP) is a new patch pump based on a microelectromechanical system that operates without any plunger. The study aimed to evaluate the infusion accuracy of the JP in vitro and in vivo. For the in vitro studies, commercially available pumps meeting the ISO standard were compared to the JP: the MiniMed® Paradigm® 712 (MP), Accu-Chek® Combo (AC), OmniPod® (OP), Animas® Vibe™ (AN). Pump accuracy was measured over 24 hours using a continuous microweighing method, at 0.1 and 1 IU/h basal rates. The occlusion alarm threshold was measured after a catheter occlusion. The JP, filled with physiological serum, was then tested in 13 patients with type 1 diabetes simultaneously with their own pump for 2 days. The weight difference was used to calculate the infused insulin volume. The JP showed reduced absolute median error rate in vitro over a 15-minute observation window compared to other pumps (1 IU/h): ±1.02% (JP) vs ±1.60% (AN), ±1.66% (AC), ±2.22% (MP), and ±4.63% (OP), P < .0001. But there was no difference over 24 hours. At 0.5 IU/h, the JP was able to detect an occlusion earlier than other pumps: 21 (19; 25) minutes vs 90 (85; 95), 58 (42; 74), and 143 (132; 218) minutes (AN, AC, MP), P < .05 vs AN and MP. In patients, the 24-hour flow error was not significantly different between the JP and usual pumps (-2.2 ± 5.6% vs -0.37 ± 4.0%, P = .25). The JP was found to be easier to wear than conventional pumps. The JP is more precise over a short time period, more sensitive to catheter occlusion, well accepted by patients, and consequently, of potential interest for a closed-loop insulin delivery system. PMID:25079676

  7. Dissociating appraisals of accuracy and recollection in autobiographical remembering.

    PubMed

    Scoboria, Alan; Pascal, Lisa

    2016-07-01

    Recent studies of metamemory appraisals implicated in autobiographical remembering have established distinct roles for judgments of occurrence, recollection, and accuracy for past events. In studies involving everyday remembering, measures of recollection and accuracy correlate highly (>.85). Thus although their measures are structurally distinct, such high correspondence might suggest conceptual redundancy. This article examines whether recollection and accuracy dissociate when studying different types of autobiographical event representations. In Study 1, 278 participants described a believed memory, a nonbelieved memory, and a believed-not-remembered event and rated each on occurrence, recollection, accuracy, and related covariates. In Study 2, 876 individuals described and rated 1 of these events, as well as an event about which they were uncertain about their memory. Confirmatory structural equation modeling indicated that the measurement dissociation between occurrence, recollection and accuracy held across all types of events examined. Relative to believed memories, the relationship between recollection and belief in accuracy was meaningfully lower for the other event types. These findings support the claim that recollection and accuracy arise from distinct underlying mechanisms. (PsycINFO Database Record

  8. Modeling Individual Differences in Response Time and Accuracy in Numeracy

    PubMed Central

    Ratcliff, Roger; Thompson, Clarissa A.; McKoon, Gail

    2015-01-01

    In the study of numeracy, some hypotheses have been based on response time (RT) as a dependent variable and some on accuracy, and considerable controversy has arisen about the presence or absence of correlations between RT and accuracy, between RT or accuracy and individual differences like IQ and math ability, and between various numeracy tasks. In this article, we show that an integration of the two dependent variables is required, which we accomplish with a theory-based model of decision making. We report data from four tasks: numerosity discrimination, number discrimination, memory for two-digit numbers, and memory for three-digit numbers. Accuracy correlated across tasks, as did RTs. However, the negative correlations that might be expected between RT and accuracy were not obtained; if a subject was accurate, it did not mean that they were fast (and vice versa). When the diffusion decision-making model was applied to the data (Ratcliff, 1978), we found significant correlations across the tasks between the quality of the numeracy information (drift rate) driving the decision process and between the speed/ accuracy criterion settings, suggesting that similar numeracy skills and similar speed-accuracy settings are involved in the four tasks. In the model, accuracy is related to drift rate and RT is related to speed-accuracy criteria, but drift rate and criteria are not related to each other across subjects. This provides a theoretical basis for understanding why negative correlations were not obtained between accuracy and RT. We also manipulated criteria by instructing subjects to maximize either speed or accuracy, but still found correlations between the criteria settings between and within tasks, suggesting that the settings may represent an individual trait that can be modulated but not equated across subjects. Our results demonstrate that a decision-making model may provide a way to reconcile inconsistent and sometimes contradictory results in numeracy

  9. Automated imaging technologies for the diagnosis of glaucoma: a comparative diagnostic study for the evaluation of the diagnostic accuracy, performance as triage tests and cost-effectiveness (GATE study).

    PubMed Central

    Azuara-Blanco, Augusto; Banister, Katie; Boachie, Charles; McMeekin, Peter; Gray, Joanne; Burr, Jennifer; Bourne, Rupert; Garway-Heath, David; Batterbury, Mark; Hernández, Rodolfo; McPherson, Gladys; Ramsay, Craig; Cook, Jonathan

    2016-01-01

    BACKGROUND Many glaucoma referrals from the community to hospital eye services are unnecessary. Imaging technologies can potentially be useful to triage this population. OBJECTIVES To assess the diagnostic performance and cost-effectiveness of imaging technologies as triage tests for identifying people with glaucoma. DESIGN Within-patient comparative diagnostic accuracy study. Markov economic model comparing the cost-effectiveness of a triage test with usual care. SETTING Secondary care. PARTICIPANTS Adults referred from the community to hospital eye services for possible glaucoma. INTERVENTIONS Heidelberg Retinal Tomography (HRT), including two diagnostic algorithms, glaucoma probability score (HRT-GPS) and Moorfields regression analysis (HRT-MRA); scanning laser polarimetry [glaucoma diagnostics (GDx)]; and optical coherence tomography (OCT). The reference standard was clinical examination by a consultant ophthalmologist with glaucoma expertise including visual field testing and intraocular pressure (IOP) measurement. MAIN OUTCOME MEASURES (1) Diagnostic performance of imaging, using data from the eye with most severe disease. (2) Composite triage test performance (imaging test, IOP measurement and visual acuity measurement), using data from both eyes, in correctly identifying clinical management decisions, that is 'discharge' or 'do not discharge'. Outcome measures were sensitivity, specificity and incremental cost per quality-adjusted life-year (QALY). RESULTS Data from 943 of 955 participants were included in the analysis. The average age was 60.5 years (standard deviation 13.8 years) and 51.1% were females. Glaucoma was diagnosed by the clinician in at least one eye in 16.8% of participants; 37.9% of participants were discharged after the first visit. Regarding diagnosing glaucoma, HRT-MRA had the highest sensitivity [87.0%, 95% confidence interval (CI) 80.2% to 92.1%] but the lowest specificity (63.9%, 95% CI 60.2% to 67.4%) and GDx had the lowest

  10. Diagnostic accuracy of quantitative PCR (Xpert MTB/RIF) for tuberculous pericarditis compared to adenosine deaminase and unstimulated interferon-γ in a high burden setting: a prospective study

    PubMed Central

    2014-01-01

    Background Tuberculous pericarditis (TBP) is associated with high morbidity and mortality, and is an important treatable cause of heart failure in developing countries. Tuberculous aetiology of pericarditis is difficult to diagnose promptly. The utility of the new quantitative PCR test (Xpert MTB/RIF) for the diagnosis of TBP is unknown. This study sought to evaluate the diagnostic accuracy of the Xpert MTB/RIF test compared to pericardial adenosine deaminase (ADA) and unstimulated interferon-gamma (uIFNγ) in suspected TBP. Methods From October 2009 through September 2012, 151 consecutive patients with suspected TBP were enrolled at a single centre in Cape Town, South Africa. Mycobacterium tuberculosis culture and/or pericardial histology served as the reference standard for definite TBP. Receiver-operating-characteristic curve analysis was used for selection of ADA and uIFNγ cut-points. Results Of the participants, 49% (74/151) were classified as definite TBP, 33% (50/151) as probable TBP and 18% (27/151) as non TBP. A total of 105 (74%) participants were human immunodeficiency virus (HIV) positive. Xpert-MTB/RIF had a sensitivity and specificity (95% confidence interval (CI)) of 63.8% (52.4% to 75.1%) and 100% (85.6% to 100%), respectively. Concentration of pericardial fluid by centrifugation and using standard sample processing did not improve Xpert MTB/RIF accuracy. ADA (≥35 IU/L) and uIFNγ (≥44 pg/ml) both had a sensitivity of 95.7% (88.1% to 98.5%) and a negative likelihood ratio of 0.05 (0.02 to 0.10). However, the specificity and positive likelihood ratio of uIFNγ was higher than ADA (96.3% (81.7% to 99.3%) and 25.8 (3.6 to 183.4) versus 84% (65.4% to 93.6%) and 6.0 (3.7 to 9.8); P = 0.03) at an estimated background prevalence of TB of 30%. The sensitivity and negative predictive value of both uIFNγ and ADA were higher than Xpert-MT/RIF (P < 0.001). Conclusions uIFNγ offers superior accuracy for the diagnosis of microbiologically

  11. Accuracy testing of electric groundwater-level measurement tapes

    USGS Publications Warehouse

    Jelinski, Jim; Clayton, Christopher S.; Fulford, Janice M.

    2015-01-01

    The accuracy tests demonstrated that none of the electric-tape models tested consistently met the suggested USGS accuracy of ±0.01 ft. The test data show that the tape models in the study should give a water-level measurement that is accurate to roughly ±0.05 ft per 100 ft without additional calibration. To meet USGS accuracy guidelines, the electric-tape models tested will need to be individually calibrated. Specific conductance also plays a part in tape accuracy. The probes will not work in water with specific conductance values near zero, and the accuracy of one probe was unreliable in very high conductivity water (10,000 microsiemens per centimeter).

  12. Geometric accuracy of three-dimensional molecular overlays.

    PubMed

    Chen, Qi; Higgs, Richard E; Vieth, Michal

    2006-01-01

    This study examines the dependence of molecular alignment accuracy on a variety of factors including the choice of molecular template, alignment method, conformational flexibility, and type of protein target. We used eight test systems for which X-ray data on 145 ligand-protein complexes were available. The use of X-ray structures allowed an unambiguous assignment of bioactive overlays for each compound set. The alignment accuracy depended on multiple factors and ranged from 6% for flexible overlays to 73% for X-ray rigid overlays, when the conformation of the template ligand came from X-ray structures. The dependence of the overlay accuracy on the choice of templates and molecules to be aligned was found to be the most significant factor in six and seven of the eight ligand-protein complex data sets, respectively. While finding little preference for the overlay method, we observed that the introduction of molecule flexibility resulted in a decrease of overlay accuracy in 50% of the cases. We derived rules to maximize the accuracy of alignment, leading to a more than 2-fold improvement in accuracy (from 19% to 48%). The rules also allowed the identification of compounds with a low (<5%) chance to be correctly aligned. Last, the accuracy of the alignment derived without any utilization of X-ray conformers varied from <1% for the human immunodeficiency virus data set to 53% for the trypsin data set. We found that the accuracy was directly proportional to the product of the overlay accuracy from the templates in their bioactive conformations and the chance of obtaining the correct bioactive conformation of the templates. This study generates a much needed benchmark for the expectations of molecular alignment accuracy and shows appropriate usages and best practices to maximize hypothesis generation success.

  13. A comparative evaluation of the dimensional accuracy of heat polymerised PMMA denture base cured by different curing cycles and clamped by R S technique and conventional method – An In-vitro study

    PubMed Central

    Babu, Mandava Ramesh; Rao, C Satyanageswar; Ahmed, Syed Tauqheer; Bharat, J S V; Rao, N Venugopal; Vinod, V

    2014-01-01

    Background: The aim of this study is to evaluate the dimensional accuracy of heat polymerized PMMA denture base clamped by the conventional method and by R.S technique and cured by a different curing cycle. Materials & Methods: In this study, a total of 40 standardized maxillary record bases were fabricated with seven reference points: Point A - Incisive papilla, Point B & C - Canine region on either side, Point E & G - Midpoint of tuberosities on either side, Point F- Midpoint of the line joining the two tuberosities, Point D- Midpoint between the line joining A and F. Group A: Ten maxillary record bases were fabricated by conventional clamping method and cured by long curing cycle. Group A1: Ten maxillary record bases were fabricated by R.S tension clamping method and cured by long curing cycle. Group B: Ten maxillary record bases were fabricated by conventional clamping method and cured by short curing cycle. Group B1: Ten maxillary record bases were fabricated by R.S tension clamping method and cured by short curing cycle. The distances between the reference points i.e. A-B, A-C, A-D, D-F, B-E, C-G, E-F, F-G, B-D, D-G, CD, D-E of all three thermoplastic denture base plates were measured and recorded with the help of a travelling microscope and were used for comparison with the measured and recorded readings of processed acrylic denture bases. The data obtained was analyzed by using the One Way Analysis of Variance. Results: The overall results of the in vitro study indicate that among all the PMMA bases cured by the two clamping systems and the different curing cycle, group A` was the most dimensionally stable, followed by control group A, then followed by B` and B was most unstable. Conclusion: The study concluded that the denture bases fabricated by the R.S Technique using the long curing cycle would produce the most dimensionally stable PMMA denture bases. How to cite the article: Babu MR, Rao CS, Ahmed ST, Bharat JS, Rao NV, Vinod V. A comparative

  14. Insensitivity of the octahedral spherical hohlraum to power imbalance, pointing accuracy, and assemblage accuracy

    SciTech Connect

    Huo, Wen Yi; Zhao, Yiqing; Zheng, Wudi; Liu, Jie; Lan, Ke

    2014-11-15

    The random radiation asymmetry in the octahedral spherical hohlraum [K. Lan et al., Phys. Plasmas 21, 0 10704 (2014)] arising from the power imbalance, pointing accuracy of laser quads, and the assemblage accuracy of capsule is investigated by using the 3-dimensional view factor model. From our study, for the spherical hohlraum, the random radiation asymmetry arising from the power imbalance of the laser quads is about half of that in the cylindrical hohlraum; the random asymmetry arising from the pointing error is about one order lower than that in the cylindrical hohlraum; and the random asymmetry arising from the assemblage error of capsule is about one third of that in the cylindrical hohlraum. Moreover, the random radiation asymmetry in the spherical hohlraum is also less than the amount in the elliptical hohlraum. The results indicate that the spherical hohlraum is more insensitive to the random variations than the cylindrical hohlraum and the elliptical hohlraum. Hence, the spherical hohlraum can relax the requirements to the power imbalance and pointing accuracy of laser facility and the assemblage accuracy of capsule.

  15. [Ovarian tumours--accuracy of frozen section diagnosis].

    PubMed

    Ivanov, S; Ivanov, S; Khadzhiolov, N

    2005-01-01

    A retrospective study of 450 ovarian biopsy results were examined for the period of 1998 till 2004 to evaluate the accuracy of frozen section diagnosis. In addition to this we performed a review of the literature for all previous studies in this field in order to study the accuracy rates of the different clinics throughout the world. The histhopathological results of the frozen section diagnosis were equal with the diagnosis of the paraffin blocks in 90%. The sensitivity rates for benign, malignant and borderline tumours, were 96%, 84% and 60% respectively. We had 10 patients (2,1%) false-positive results (overdiagnosed) and 26 (5,2%) false-negative results (underdiagnosed) in frozen section examinations. Frozen section examination of mucinous tumours showed hogher underdiagnosis--18%. The review of the literature showed that there is no significant difference in accuracy rates of frozen section diagnosis for benign and malignant ovarian tumours in relation with time. We found low accuracy rates for borderline tumours which was similar with most of the foreign publications. However the accuracy of the frozen section diagnosis is bettering with the time. As a result of this we conclude that the accuracy rates of the frozen section diagnosis for evaluation of the malignant and benign tumours is quite enough for correct diagnosis. Since accuracy rates for borderline ovarian tumours are low we have to take care and attention of improvement in this field.

  16. Improvement of focus accuracy on processed wafer

    NASA Astrophysics Data System (ADS)

    Higashibata, Satomi; Komine, Nobuhiro; Fukuhara, Kazuya; Koike, Takashi; Kato, Yoshimitsu; Hashimoto, Kohji

    2013-04-01

    As feature size shrinkage in semiconductor device progress, process fluctuation, especially focus strongly affects device performance. Because focus control is an ongoing challenge in optical lithography, various studies have sought for improving focus monitoring and control. Focus errors are due to wafers, exposure tools, reticles, QCs, and so on. Few studies are performed to minimize the measurement errors of auto focus (AF) sensors of exposure tool, especially when processed wafers are exposed. With current focus measurement techniques, the phase shift grating (PSG) focus monitor 1) has been already proposed and its basic principle is that the intensity of the diffraction light of the mask pattern is made asymmetric by arranging a π/2 phase shift area on a reticle. The resist pattern exposed at the defocus position is shifted on the wafer and shifted pattern can be easily measured using an overlay inspection tool. However, it is difficult to measure shifted pattern for the pattern on the processed wafer because of interruptions caused by other patterns in the underlayer. In this paper, we therefore propose "SEM-PSG" technique, where the shift of the PSG resist mark is measured by employing critical dimension-scanning electron microscope (CD-SEM) to measure the focus error on the processed wafer. First, we evaluate the accuracy of SEM-PSG technique. Second, by applying the SEM-PSG technique and feeding the results back to the exposure, we evaluate the focus accuracy on processed wafers. By applying SEM-PSG feedback, the focus accuracy on the processed wafer was improved from 40 to 29 nm in 3σ.

  17. Accuracy of endoscopic ultrasonography for diagnosing ulcerative early gastric cancers.

    PubMed

    Park, Jin-Seok; Kim, Hyungkil; Bang, Byongwook; Kwon, Kyesook; Shin, Youngwoon

    2016-07-01

    Although endoscopic ultrasonography (EUS) is the first-choice imaging modality for predicting the invasion depth of early gastric cancer (EGC), the prediction accuracy of EUS is significantly decreased when EGC is combined with ulceration.The aim of present study was to compare the accuracy of EUS and conventional endoscopy (CE) for determining the depth of EGC. In addition, the various clinic-pathologic factors affecting the diagnostic accuracy of EUS, with a particular focus on endoscopic ulcer shapes, were evaluated.We retrospectively reviewed data from 236 consecutive patients with ulcerative EGC. All patients underwent EUS for estimating tumor invasion depth, followed by either curative surgery or endoscopic treatment. The diagnostic accuracy of EUS and CE was evaluated by comparing the final histologic result of resected specimen. The correlation between accuracy of EUS and characteristics of EGC (tumor size, histology, location in stomach, tumor invasion depth, and endoscopic ulcer shapes) was analyzed. Endoscopic ulcer shapes were classified into 3 groups: definite ulcer, superficial ulcer, and ill-defined ulcer.The overall accuracy of EUS and CE for predicting the invasion depth in ulcerative EGC was 68.6% and 55.5%, respectively. Of the 236 patients, 36 patients were classified as definite ulcers, 98 were superficial ulcers, and 102 were ill-defined ulcers, In univariate analysis, EUS accuracy was associated with invasion depth (P = 0.023), tumor size (P = 0.034), and endoscopic ulcer shapes (P = 0.001). In multivariate analysis, there is a significant association between superficial ulcer in CE and EUS accuracy (odds ratio: 2.977; 95% confidence interval: 1.255-7.064; P = 0.013).The accuracy of EUS for determining tumor invasion depth in ulcerative EGC was superior to that of CE. In addition, ulcer shape was an important factor that affected EUS accuracy. PMID:27472672

  18. Review article: Diagnostic accuracy of risk stratification tools for patients with chest pain in the rural emergency department: A systematic review.

    PubMed

    Roche, Tina; Jennings, Natasha; Clifford, Stuart; O'connell, Jane; Lutze, Matthew; Gosden, Edward; Hadden, N Fionna; Gardner, Glenn

    2016-10-01

    Risk stratification tools for patients presenting to rural EDs with undifferentiated chest pain enable early definitive treatment in high-risk patients. This systematic review compares the most commonly used risk stratification tools used to predict the risk of major adverse cardiac event (MACE) for patients presenting to rural EDs with chest pain. A comprehensive search of MEDLINE and Embase for studies published between January 2011 and January 2015 was undertaken. Study quality was assessed using QUADAS-2 criteria and the PRISMA guidelines.Eleven studies using eight risk stratification tools met the inclusion criteria. The percentage of MACE in the patients stratified as suitable for discharge, and the percentage of patients whose scores would have recommended admission that did not experience a MACE event were used as comparisons. Using the findings of a survey of emergency physicians that found a 1% MACE rate acceptable in discharged patients, the EDACS-ADP was considered the best performer. EDACS-ADP had one of the lowest rates of MACE in those discharged (3/1148, 0.3%) and discharged one of the highest percentage of patients (44.5%). Only the GRACE tool discharged more patients (69% - all patients with scores <100) but had a MACE rate of 0.3% in discharged patients. The HFA/CSANZ guidelines achieved zero cases of MACE but discharged only 1.3% of patients.EDACS-ADP can potentially increase diagnostic efficiency of patients presenting at ED with chest pain. Further assessment of tool in a rural context is recommended.

  19. Integrated zone comparison polygraph technique accuracy with scoring algorithms.

    PubMed

    Gordon, Nathan J; Mohamed, Feroze B; Faro, Scott H; Platek, Steven M; Ahmad, Harris; Williams, J Michael

    2006-02-28

    The Integrated Zone Comparison Technique (IZCT) was utilized with computerized polygraph instrumentation as part of a blind study in the detection of deception. Three scoring algorithms: ASIT Poly Suite (Academy for Scientific Investigative Training's Horizontal Scoring and Algorithm for Chart Interpretation), PolyScore 5.5, and the Objective Scoring System (OSS) were assessed in the interpretation of the charts generated. Where "Inconclusives" were excluded, accuracy for the IZCT with all three algorithms was 100%. When "Inconclusives" were counted as errors, overall accuracy for the IZCT with ASIT Poly Suite was 90% and accuracy with PolyScore and the Objective Scoring System was 72%.

  20. [True color accuracy in digital forensic photography].

    PubMed

    Ramsthaler, Frank; Birngruber, Christoph G; Kröll, Ann-Katrin; Kettner, Mattias; Verhoff, Marcel A

    2016-01-01

    Forensic photographs not only need to be unaltered and authentic and capture context-relevant images, along with certain minimum requirements for image sharpness and information density, but color accuracy also plays an important role, for instance, in the assessment of injuries or taphonomic stages, or in the identification and evaluation of traces from photos. The perception of color not only varies subjectively from person to person, but as a discrete property of an image, color in digital photos is also to a considerable extent influenced by technical factors such as lighting, acquisition settings, camera, and output medium (print, monitor). For these reasons, consistent color accuracy has so far been limited in digital photography. Because images usually contain a wealth of color information, especially for complex or composite colors or shades of color, and the wavelength-dependent sensitivity to factors such as light and shadow may vary between cameras, the usefulness of issuing general recommendations for camera capture settings is limited. Our results indicate that true image colors can best and most realistically be captured with the SpyderCheckr technical calibration tool for digital cameras tested in this study. Apart from aspects such as the simplicity and quickness of the calibration procedure, a further advantage of the tool is that the results are independent of the camera used and can also be used for the color management of output devices such as monitors and printers. The SpyderCheckr color-code patches allow true colors to be captured more realistically than with a manual white balance tool or an automatic flash. We therefore recommend that the use of a color management tool should be considered for the acquisition of all images that demand high true color accuracy (in particular in the setting of injury documentation). PMID:27386623

  1. [True color accuracy in digital forensic photography].

    PubMed

    Ramsthaler, Frank; Birngruber, Christoph G; Kröll, Ann-Katrin; Kettner, Mattias; Verhoff, Marcel A

    2016-01-01

    Forensic photographs not only need to be unaltered and authentic and capture context-relevant images, along with certain minimum requirements for image sharpness and information density, but color accuracy also plays an important role, for instance, in the assessment of injuries or taphonomic stages, or in the identification and evaluation of traces from photos. The perception of color not only varies subjectively from person to person, but as a discrete property of an image, color in digital photos is also to a considerable extent influenced by technical factors such as lighting, acquisition settings, camera, and output medium (print, monitor). For these reasons, consistent color accuracy has so far been limited in digital photography. Because images usually contain a wealth of color information, especially for complex or composite colors or shades of color, and the wavelength-dependent sensitivity to factors such as light and shadow may vary between cameras, the usefulness of issuing general recommendations for camera capture settings is limited. Our results indicate that true image colors can best and most realistically be captured with the SpyderCheckr technical calibration tool for digital cameras tested in this study. Apart from aspects such as the simplicity and quickness of the calibration procedure, a further advantage of the tool is that the results are independent of the camera used and can also be used for the color management of output devices such as monitors and printers. The SpyderCheckr color-code patches allow true colors to be captured more realistically than with a manual white balance tool or an automatic flash. We therefore recommend that the use of a color management tool should be considered for the acquisition of all images that demand high true color accuracy (in particular in the setting of injury documentation).

  2. Accuracy Assessment of Altimeter Derived Geostrophic Velocities

    NASA Astrophysics Data System (ADS)

    Leben, R. R.; Powell, B. S.; Born, G. H.; Guinasso, N. L.

    2002-12-01

    Along track sea surface height anomaly gradients are proportional to cross track geostrophic velocity anomalies allowing satellite altimetry to provide much needed satellite observations of changes in the geostrophic component of surface ocean currents. Often, surface height gradients are computed from altimeter data archives that have been corrected to give the most accurate absolute sea level, a practice that may unnecessarily increase the error in the cross track velocity anomalies and thereby require excessive smoothing to mitigate noise. Because differentiation along track acts as a high-pass filter, many of the path length corrections applied to altimeter data for absolute height accuracy are unnecessary for the corresponding gradient calculations. We report on a study to investigate appropriate altimetric corrections and processing techniques for improving geostrophic velocity accuracy. Accuracy is assessed by comparing cross track current measurements from two moorings placed along the descending TOPEX/POSEIDON ground track number 52 in the Gulf of Mexico to the corresponding altimeter velocity estimates. The buoys are deployed and maintained by the Texas Automated Buoy System (TABS) under Interagency Contracts with Texas A&M University. The buoys telemeter observations in near real-time via satellite to the TABS station located at the Geochemical and Environmental Research Group (GERG) at Texas A&M. Buoy M is located in shelf waters of 57 m depth with a second, Buoy N, 38 km away on the shelf break at 105 m depth. Buoy N has been operational since the beginning of 2002 and has a current meter at 2m depth providing in situ measurements of surface velocities coincident with Jason and TOPEX/POSEIDON altimeter over flights. This allows one of the first detailed comparisons of shallow water near surface current meter time series to coincident altimetry.

  3. Comparative Evaluation of Marginal Accuracy of a Cast Fixed Partial Denture Compared to Soldered Fixed Partial Denture Made of Two Different Base Metal Alloys and Casting Techniques: An In vitro Study.

    PubMed

    Jei, J Brintha; Mohan, Jayashree

    2014-03-01

    The periodontal health of abutment teeth and the durability of fixed partial denture depends on the marginal adaptation of the prosthesis. Any discrepancy in the marginal area leads to dissolution of luting agent and plaque accumulation. This study was done with the aim of evaluating the accuracy of marginal fit of four unit crown and bridge made up of Ni-Cr and Cr-Co alloys under induction and centrifugal casting. They were compared to cast fixed partial denture (FPD) and soldered FPD. For the purpose of this study a metal model was fabricated. A total of 40 samples (4-unit crown and bridge) were prepared in which 20 Cr-Co samples and 20 Ni-Cr samples were fabricated. Within these 20 samples of each group 10 samples were prepared by induction casting technique and other 10 samples with centrifugal casting technique. The cast FPD samples obtained were seated on the model and the samples were then measured with travelling microscope having precision of 0.001 cm. Sectioning of samples was done between the two pontics and measurements were made, then the soldering was made with torch soldering unit. The marginal discrepancy of soldered samples was measured and all findings were statistically analysed. The results revealed minimal marginal discrepancy with Cr-Co samples when compared to Ni-Cr samples done under induction casting technique. When compared to cast FPD samples, the soldered group showed reduced marginal discrepancy. PMID:24605006

  4. Comparative Analysis of the Equivital EQ02 Lifemonitor with Holter Ambulatory ECG Device for Continuous Measurement of ECG, Heart Rate, and Heart Rate Variability: A Validation Study for Precision and Accuracy

    PubMed Central

    Akintola, Abimbola A.; van de Pol, Vera; Bimmel, Daniel; Maan, Arie C.; van Heemst, Diana

    2016-01-01

    Background: The Equivital (EQ02) is a multi-parameter telemetric device offering both real-time and/or retrospective, synchronized monitoring of ECG, HR, and HRV, respiration, activity, and temperature. Unlike the Holter, which is the gold standard for continuous ECG measurement, EQO2 continuously monitors ECG via electrodes interwoven in the textile of a wearable belt. Objective: To compare EQ02 with the Holter for continuous home measurement of ECG, heart rate (HR), and heart rate variability (HRV). Methods: Eighteen healthy participants wore, simultaneously for 24 h, the Holter and EQ02 monitors. Per participant, averaged HR, and HRV per 5 min from the two devices were compared using Pearson correlation, paired T-test, and Bland-Altman analyses. Accuracy and precision metrics included mean absolute relative difference (MARD). Results: Artifact content of EQ02 data varied widely between (range 1.93–56.45%) and within (range 0.75–9.61%) participants. Comparing the EQ02 to the Holter, the Pearson correlations were respectively 0.724, 0.955, and 0.997 for datasets containing all data and data with < 50 or < 20% artifacts respectively. For datasets containing respectively all data, data with < 50, or < 20% artifacts, bias estimated by Bland-Altman analysis was −2.8, −1.0, and −0.8 beats per minute and 24 h MARD was 7.08, 3.01, and 1.5. After selecting a 3-h stretch of data containing 1.15% artifacts, Pearson correlation was 0.786 for HRV measured as standard deviation of NN intervals (SDNN). Conclusions: Although the EQ02 can accurately measure ECG and HRV, its accuracy and precision is highly dependent on artifact content. This is a limitation for clinical use in individual patients. However, the advantages of the EQ02 (ability to simultaneously monitor several physiologic parameters) may outweigh its disadvantages (higher artifact load) for research purposes and/ or for home monitoring in larger groups of study participants. Further studies can be aimed

  5. Quantifying the prediction accuracy of a 1-D SVAT model at a range of ecosystems in the USA and Australia: evidence towards its use as a tool to study Earth's system interactions

    NASA Astrophysics Data System (ADS)

    Petropoulos, G. P.; North, M. R.; Ireland, G.; Srivastava, P. K.; Rendall, D. V.

    2015-10-01

    This paper describes the validation of the SimSphere SVAT (Soil-Vegetation-Atmosphere Transfer) model conducted at a range of US and Australian ecosystem types. Specific focus was given to examining the models' ability in predicting shortwave incoming solar radiation (Rg), net radiation (Rnet), latent heat (LE), sensible heat (H), air temperature at 1.3 m (Tair 1.3 m) and air temperature at 50 m (Tair 50 m). Model predictions were compared against corresponding in situ measurements acquired for a total of 72 selected days of the year 2011 obtained from eight sites belonging to the AmeriFlux (USA) and OzFlux (Australia) monitoring networks. Selected sites were representative of a variety of environmental, biome and climatic conditions, to allow for the inclusion of contrasting conditions in the model evaluation. Overall, results showed a good agreement between the model predictions and the in situ measurements, particularly so for the Rg, Rnet, Tair 1.3 m and Tair 50 m parameters. The simulated Rg parameter exhibited a root mean square deviation (RMSD) within 25 % of the observed fluxes for 58 of the 72 selected days, whereas an RMSD within ~ 24 % of the observed fluxes was reported for the Rnet parameter for all days of study (RMSD = 58.69 W m-2). A systematic underestimation of Rg and Rnet (mean bias error (MBE) = -19.48 and -16.46 W m-2) was also found. Simulations for the Tair 1.3 m and Tair 50 m showed good agreement with the in situ observations, exhibiting RMSDs of 3.23 and 3.77 °C (within ~ 15 and ~ 18 % of the observed) for all days of analysis, respectively. Comparable, yet slightly less satisfactory simulation accuracies were exhibited for the H and LE parameters (RMSDs = 38.47 and 55.06 W m-2, ~ 34 and ~ 28 % of the observed). Highest simulation accuracies were obtained for the open woodland savannah and mulga woodland sites for most of the compared parameters. The Nash-Sutcliffe efficiency index for all parameters ranges from 0.720 to 0.998, suggesting

  6. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    LRO definitive and predictive accuracy requirements were easily met in the nominal mission orbit, using the LP150Q lunar gravity model. center dot Accuracy of the LP150Q model is poorer in the extended mission elliptical orbit. center dot Later lunar gravity models, in particular GSFC-GRAIL-270, improve OD accuracy in the extended mission. center dot Implementation of a constrained plane when the orbit is within 45 degrees of the Earth-Moon line improves cross-track accuracy. center dot Prediction accuracy is still challenged during full-Sun periods due to coarse spacecraft area modeling - Implementation of a multi-plate area model with definitive attitude input can eliminate prediction violations. - The FDF is evaluating using analytic and predicted attitude modeling to improve full-Sun prediction accuracy. center dot Comparison of FDF ephemeris file to high-precision ephemeris files provides gross confirmation that overlap compares properly assess orbit accuracy.

  7. Accuracy of TCP performance models

    NASA Astrophysics Data System (ADS)

    Schwefel, Hans Peter; Jobmann, Manfred; Hoellisch, Daniel; Heyman, Daniel P.

    2001-07-01

    Despite the fact that most of todays' Internet traffic is transmitted via the TCP protocol, the performance behavior of networks with TCP traffic is still not well understood. Recent research activities have lead to a number of performance models for TCP traffic, but the degree of accuracy of these models in realistic scenarios is still questionable. This paper provides a comparison of the results (in terms of average throughput per connection) of three different `analytic' TCP models: I. the throughput formula in [Padhye et al. 98], II. the modified Engset model of [Heyman et al. 97], and III. the analytic TCP queueing model of [Schwefel 01] that is a packet based extension of (II). Results for all three models are computed for a scenario of N identical TCP sources that transmit data in individual TCP connections of stochastically varying size. The results for the average throughput per connection in the analytic models are compared with simulations of detailed TCP behavior. All of the analytic models are expected to show deficiencies in certain scenarios, since they neglect highly influential parameters of the actual real simulation model: The approach of Model (I) and (II) only indirectly considers queueing in bottleneck routers, and in certain scenarios those models are not able to adequately describe the impact of buffer-space, neither qualitatively nor quantitatively. Furthermore, (II) is insensitive to the actual distribution of the connection sizes. As a consequence, their prediction would also be insensitive of so-called long-range dependent properties in the traffic that are caused by heavy-tailed connection size distributions. The simulation results show that such properties cannot be neglected for certain network topologies: LRD properties can even have counter-intuitive impact on the average goodput, namely the goodput can be higher for small buffer-sizes.

  8. Acceptability, Precision and Accuracy of 3D Photonic Scanning for Measurement of Body Shape in a Multi-Ethnic Sample of Children Aged 5-11 Years: The SLIC Study

    PubMed Central

    Wells, Jonathan C. K.; Stocks, Janet; Bonner, Rachel; Raywood, Emma; Legg, Sarah; Lee, Simon; Treleaven, Philip; Lum, Sooky

    2015-01-01

    Background Information on body size and shape is used to interpret many aspects of physiology, including nutritional status, cardio-metabolic risk and lung function. Such data have traditionally been obtained through manual anthropometry, which becomes time-consuming when many measurements are required. 3D photonic scanning (3D-PS) of body surface topography represents an alternative digital technique, previously applied successfully in large studies of adults. The acceptability, precision and accuracy of 3D-PS in young children have not been assessed. Methods We attempted to obtain data on girth, width and depth of the chest and waist, and girth of the knee and calf, manually and by 3D-PS in a multi-ethnic sample of 1484 children aged 5–11 years. The rate of 3D-PS success, and reasons for failure, were documented. Precision and accuracy of 3D-PS were assessed relative to manual measurements using the methods of Bland and Altman. Results Manual measurements were successful in all cases. Although 97.4% of children agreed to undergo 3D-PS, successful scans were only obtained in 70.7% of these. Unsuccessful scans were primarily due to body movement, or inability of the software to extract shape outputs. The odds of scan failure, and the underlying reason, differed by age, size and ethnicity. 3D-PS measurements tended to be greater than those obtained manually (p<0.05), however ranking consistency was high (r2>0.90 for most outcomes). Conclusions 3D-PS is acceptable in children aged ≥5 years, though with current hardware/software, and body movement artefacts, approximately one third of scans may be unsuccessful. The technique had poorer technical success than manual measurements, and had poorer precision when the measurements were viable. Compared to manual measurements, 3D-PS showed modest average biases but acceptable limits of agreement for large surveys, and little evidence that bias varied substantially with size. Most of the issues we identified could be

  9. Curation accuracy of model organism databases.

    PubMed

    Keseler, Ingrid M; Skrzypek, Marek; Weerasinghe, Deepika; Chen, Albert Y; Fulcher, Carol; Li, Gene-Wei; Lemmer, Kimberly C; Mladinich, Katherine M; Chow, Edmond D; Sherlock, Gavin; Karp, Peter D

    2014-01-01

    Manual extraction of information from the biomedical literature-or biocuration-is the central methodology used to construct many biological databases. For example, the UniProt protein database, the EcoCyc Escherichia coli database and the Candida Genome Database (CGD) are all based on biocuration. Biological databases are used extensively by life science researchers, as online encyclopedias, as aids in the interpretation of new experimental data and as golden standards for the development of new bioinformatics algorithms. Although manual curation has been assumed to be highly accurate, we are aware of only one previous study of biocuration accuracy. We assessed the accuracy of EcoCyc and CGD by manually selecting curated assertions within randomly chosen EcoCyc and CGD gene pages and by then validating that the data found in the referenced publications supported those assertions. A database assertion is considered to be in error if that assertion could not be found in the publication cited for that assertion. We identified 10 errors in the 633 facts that we validated across the two databases, for an overall error rate of 1.58%, and individual error rates of 1.82% for CGD and 1.40% for EcoCyc. These data suggest that manual curation of the experimental literature by Ph.D-level scientists is highly accurate. Database URL: http://ecocyc.org/, http://www.candidagenome.org//

  10. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2004-07-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the rms scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes, with some dependence on filter. The largest errors seen are 0.07 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  11. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2002-12-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  12. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B. C.; Lubin, L. M.

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The tentative agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.03 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  13. Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions – Changes in Accuracy over Time

    PubMed Central

    Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

    2015-01-01

    Background Interest in 3D inertial motion tracking devices (AHRS) has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven’t been extensively documented. The objectives of this study are: 1) to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2) to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time. Methods This study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT) and 12 minutes multiple dynamic phases motion trials (12MDP). Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials. Findings Both absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase. Interpretation The variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame. Conclusions Mean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their

  14. Comparative Study of the Accuracy of Different Techniques for the Laboratory Diagnosis of Schistosomiasis Mansoni in Areas of Low Endemicity in Barra Mansa City, Rio de Janeiro State, Brazil.

    PubMed

    Espírito-Santo, Maria Cristina Carvalho; Alvarado-Mora, Mónica Viviana; Pinto, Pedro Luiz Silva; Sanchez, Maria Carmen Arroyo; Dias-Neto, Emmanuel; Castilho, Vera Lúcia Pagliusi; Gonçalves, Elenice Messias do Nascimento; Chieffi, Pedro Paulo; Luna, Expedito José de Albuquerque; Pinho, João Renato Rebello; Carrilho, Flair José; Gryschek, Ronaldo Cesar Borges

    2015-01-01

    Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82-95.5%), differed significantly from COPT in positivity (P < 0.05), and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs.

  15. Comparative Study of the Accuracy of Different Techniques for the Laboratory Diagnosis of Schistosomiasis Mansoni in Areas of Low Endemicity in Barra Mansa City, Rio de Janeiro State, Brazil

    PubMed Central

    Espírito-Santo, Maria Cristina Carvalho; Alvarado-Mora, Mónica Viviana; Pinto, Pedro Luiz Silva; Sanchez, Maria Carmen Arroyo; Dias-Neto, Emmanuel; Castilho, Vera Lúcia Pagliusi; Gonçalves, Elenice Messias do Nascimento; Chieffi, Pedro Paulo; Luna, Expedito José de Albuquerque; Pinho, João Renato Rebello; Carrilho, Flair José; Gryschek, Ronaldo Cesar Borges

    2015-01-01

    Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82–95.5%), differed significantly from COPT in positivity (P < 0.05), and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs. PMID:26504777

  16. Comparative Study of the Accuracy of Different Techniques for the Laboratory Diagnosis of Schistosomiasis Mansoni in Areas of Low Endemicity in Barra Mansa City, Rio de Janeiro State, Brazil.

    PubMed

    Espírito-Santo, Maria Cristina Carvalho; Alvarado-Mora, Mónica Viviana; Pinto, Pedro Luiz Silva; Sanchez, Maria Carmen Arroyo; Dias-Neto, Emmanuel; Castilho, Vera Lúcia Pagliusi; Gonçalves, Elenice Messias do Nascimento; Chieffi, Pedro Paulo; Luna, Expedito José de Albuquerque; Pinho, João Renato Rebello; Carrilho, Flair José; Gryschek, Ronaldo Cesar Borges

    2015-01-01

    Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82-95.5%), differed significantly from COPT in positivity (P < 0.05), and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs. PMID:26504777

  17. The empirical accuracy of uncertain inference models

    NASA Technical Reports Server (NTRS)

    Vaughan, David S.; Yadrick, Robert M.; Perrin, Bruce M.; Wise, Ben P.

    1987-01-01

    Uncertainty is a pervasive feature of the domains in which expert systems are designed to function. Research design to test uncertain inference methods for accuracy and robustness, in accordance with standard engineering practice is reviewed. Several studies were conducted to assess how well various methods perform on problems constructed so that correct answers are known, and to find out what underlying features of a problem cause strong or weak performance. For each method studied, situations were identified in which performance deteriorates dramatically. Over a broad range of problems, some well known methods do only about as well as a simple linear regression model, and often much worse than a simple independence probability model. The results indicate that some commercially available expert system shells should be used with caution, because the uncertain inference models that they implement can yield rather inaccurate results.

  18. Accuracy in determining voice source parameters

    NASA Astrophysics Data System (ADS)

    Leonov, A. S.; Sorokin, V. N.

    2014-11-01

    The paper addresses the accuracy of an approximate solution to the inverse problem of retrieving the shape of a voice source from a speech signal for a known signal-to-noise ratio (SNR). It is shown that if the source is found as a function of time with the A.N. Tikhonov regularization method, the accuracy of the found approximation is worse than the accuracy of speech signal recording by an order of magnitude. In contrast, adequate parameterization of the source ensures approximate solution accuracy comparable with the accuracy of the problem data. A corresponding algorithm is considered. On the basis of linear (in terms of data errors) estimates of approximate parametric solution accuracy, parametric models with the best accuracy can be chosen. This comparison has been carried out for the known voice source models, i.e., model [17] and the LF model [18]. The advantages of the latter are shown. Thus, for SNR = 40 dB, the relative accuracy of an approximate solution found with this algorithm is about 1% for the LF model and about 2% for model [17] as compared to an accuracy of 7-8% in the regularization method. The role of accuracy estimates found in speaker identification problems is discussed.

  19. Diagnostic Accuracy of Procalcitonin in Bacterial Meningitis Versus Nonbacterial Meningitis

    PubMed Central

    Wei, Ting-Ting; Hu, Zhi-De; Qin, Bao-Dong; Ma, Ning; Tang, Qing-Qin; Wang, Li-Li; Zhou, Lin; Zhong, Ren-Qian

    2016-01-01

    Abstract Several studies have investigated the diagnostic accuracy of procalcitonin (PCT) levels in blood or cerebrospinal fluid (CSF) in bacterial meningitis (BM), but the results were heterogeneous. The aim of the present study was to ascertain the diagnostic accuracy of PCT as a marker for BM detection. A systematic search of the EMBASE, Scopus, Web of Science, and PubMed databases was performed to identify studies published before December 7, 2015 investigating the diagnostic accuracy of PCT for BM. The quality of the eligible studies was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy method. The overall diagnostic accuracy of PCT detection in CSF or blood was pooled using the bivariate model. Twenty-two studies involving 2058 subjects were included in this systematic review and meta-analysis. The overall specificities and sensitivities were 0.86 and 0.80 for CSF PCT, and 0.97 and 0.95 for blood PCT, respectively. Areas under the summary receiver operating characteristic curves were 0.90 and 0.98 for CSF PCT and blood PCT, respectively. The major limitation of this systematic review and meta-analysis was the small number of studies included and the heterogeneous diagnostic thresholds adopted by eligible studies. Our meta-analysis shows that PCT is a useful biomarker for BM diagnosis. PMID:26986140

  20. What do we mean by accuracy in geomagnetic measurements?

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  1. Accuracy testing of a new intraoral 3D camera.

    PubMed

    Mehl, A; Ender, A; Mörmann, W; Attin, T

    2009-01-01

    Surveying intraoral structures by optical means has reached the stage where it is being discussed as a serious clinical alternative to conventional impression taking. Ease of handling and, more importantly, accuracy are important criteria for the clinical suitability of these systems. This article presents a new intraoral camera for the Cerec procedure. It reports on a study investigating the accuracy of this camera and its potential clinical indications. Single-tooth and quadrant images were taken with the camera and the results compared to those obtained with a reference scanner and with the previous 3D camera model. Differences were analyzed by superimposing the data records. Accuracy was higher with the new camera than with the previous model, reaching up to 19 microm in single-tooth images. Quadrant images can also be taken with sufficient accuracy (ca 35 microm) and are simple to perform in clinical practice, thanks to built-in shake detection in automatic capture mode.

  2. Spacecraft attitude determination accuracy from mission experience

    NASA Technical Reports Server (NTRS)

    Brasoveanu, D.; Hashmall, J.; Baker, D.

    1994-01-01

    This document presents a compilation of the attitude accuracy attained by a number of satellites that have been supported by the Flight Dynamics Facility (FDF) at Goddard Space Flight Center (GSFC). It starts with a general description of the factors that influence spacecraft attitude accuracy. After brief descriptions of the missions supported, it presents the attitude accuracy results for currently active and older missions, including both three-axis stabilized and spin-stabilized spacecraft. The attitude accuracy results are grouped by the sensor pair used to determine the attitudes. A supplementary section is also included, containing the results of theoretical computations of the effects of variation of sensor accuracy on overall attitude accuracy.

  3. Haptic perception accuracy depending on self-produced movement.

    PubMed

    Park, Chulwook; Kim, Seonjin

    2014-01-01

    This study measured whether self-produced movement influences haptic perception ability (experiment 1) as well as the factors associated with levels of influence (experiment 2) in racket sports. For experiment 1, the haptic perception accuracy levels of five male table tennis experts and five male novices were examined under two different conditions (no movement vs. movement). For experiment 2, the haptic afferent subsystems of five male table tennis experts and five male novices were investigated in only the self-produced movement-coupled condition. Inferential statistics (ANOVA, t-test) and custom-made devices (shock & vibration sensor, Qualisys Track Manager) of the data were used to determine the haptic perception accuracy (experiment 1, experiment 2) and its association with expertise. The results of this research show that expert-level players acquire higher accuracy with less variability (racket vibration and angle) than novice-level players, especially in their self-produced movement coupled performances. The important finding from this result is that, in terms of accuracy, the skill-associated differences were enlarged during self-produced movement. To explain the origin of this difference between experts and novices, the functional variability of haptic afferent subsystems can serve as a reference. These two factors (self-produced accuracy and the variability of haptic features) as investigated in this study would be useful criteria for educators in racket sports and suggest a broader hypothesis for further research into the effects of the haptic accuracy related to variability.

  4. Kinematics of a striking task: accuracy and speed-accuracy considerations.

    PubMed

    Parrington, Lucy; Ball, Kevin; MacMahon, Clare

    2015-01-01

    Handballing in Australian football (AF) is the most efficient passing method, yet little research exists examining technical factors associated with accuracy. This study had three aims: (a) To explore the kinematic differences between accurate and inaccurate handballers, (b) to compare within-individual successful (hit target) and unsuccessful (missed target) handballs and (c) to assess handballing when both accuracy and speed of ball-travel were combined using a novel approach utilising canonical correlation analysis. Three-dimensional data were collected on 18 elite AF players who performed handballs towards a target. More accurate handballers exhibited a significantly straighter hand-path, slower elbow angular velocity and smaller elbow range of motion (ROM) compared to the inaccurate group. Successful handballs displayed significantly larger trunk ROM, maximum trunk rotation velocity and step-angle and smaller elbow ROM in comparison to the unsuccessful handballs. The canonical model explained 73% of variance shared between the variable sets, with a significant relationship found between hand-path, elbow ROM and maximum elbow angular velocity (predictors) and hand-speed and accuracy (dependant variables). Interestingly, not all parameters were the same across each of the analyses, with technical differences between inaccurate and accurate handballers different from those between successful and unsuccessful handballs in the within-individual analysis. PMID:25079111

  5. Accuracy in prescriptions compounded by pharmacy students.

    PubMed

    Shrewsbury, R P; Deloatch, K H

    1998-01-01

    Most compounded prescriptions are not analyzed to determine the accuracy of the employed instruments and procedures. The assumption is that the compounded prescription will be +/- 5% the labeled claim. Two classes of School of Pharmcacy students who received repeated instruction and supervision on proper compounding techniques and procedures were assessed to determine their accuracy of compounding a diphenhydramine hydrochloride prescription. After two attempts, only 62% to 68% of the students could compound the prescription within +/- 5% the labeled claim; but 84% to 96% could attain an accuracy of +/- 10%. The results suggest that an accuracy of +/- 10% labeled claim is the least variation a pharmacist can expect when extemporaneously compounding prescriptions.

  6. The neural bases of empathic accuracy

    PubMed Central

    Zaki, Jamil; Weber, Jochen; Bolger, Niall; Ochsner, Kevin

    2009-01-01

    Theories of empathy suggest that an accurate understanding of another's emotions should depend on affective, motor, and/or higher cognitive brain regions, but until recently no experimental method has been available to directly test these possibilities. Here, we present a functional imaging paradigm that allowed us to address this issue. We found that empathically accurate, as compared with inaccurate, judgments depended on (i) structures within the human mirror neuron system thought to be involved in shared sensorimotor representations, and (ii) regions implicated in mental state attribution, the superior temporal sulcus and medial prefrontal cortex. These data demostrate that activity in these 2 sets of brain regions tracks with the accuracy of attributions made about another's internal emotional state. Taken together, these results provide both an experimental approach and theoretical insights for studying empathy and its dysfunction. PMID:19549849