ArcticDEM Validation and Accuracy Assessment

Science.gov (United States)

Candela, S. G.; Howat, I.; Noh, M. J.; Porter, C. C.; Morin, P. J.

2017-12-01

ArcticDEM comprises a growing inventory Digital Elevation Models (DEMs) covering all land above 60°N. As of August, 2017, ArcticDEM had openly released 2-m resolution, individual DEM covering over 51 million km2, which includes areas of repeat coverage for change detection, as well as over 15 million km2 of 5-m resolution seamless mosaics. By the end of the project, over 80 million km2 of 2-m DEMs will be produced, averaging four repeats of the 20 million km2 Arctic landmass. ArcticDEM is produced from sub-meter resolution, stereoscopic imagery using open source software (SETSM) on the NCSA Blue Waters supercomputer. These DEMs have known biases of several meters due to errors in the sensor models generated from satellite positioning. These systematic errors are removed through three-dimensional registration to high-precision Lidar or other control datasets. ArcticDEM is registered to seasonally-subsetted ICESat elevations due its global coverage and high report accuracy ( 10 cm). The vertical accuracy of ArcticDEM is then obtained from the statistics of the fit to the ICESat point cloud, which averages -0.01 m ± 0.07 m. ICESat, however, has a relatively coarse measurement footprint ( 70 m) which may impact the precision of the registration. Further, the ICESat data predates the ArcticDEM imagery by a decade, so that temporal changes in the surface may also impact the registration. Finally, biases may exist between different the different sensors in the ArcticDEM constellation. Here we assess the accuracy of ArcticDEM and the ICESat registration through comparison to multiple high-resolution airborne lidar datasets that were acquired within one year of the imagery used in ArcticDEM. We find the ICESat dataset is performing as anticipated, introducing no systematic bias during the coregistration process, and reducing vertical errors to within the uncertainty of the airborne Lidars. Preliminary sensor comparisons show no significant difference post coregistration

Accuracy assessment of a mobile terrestrial lidar survey at Padre Island National Seashore

Science.gov (United States)

Lim, Samsung; Thatcher, Cindy A.; Brock, John C.; Kimbrow, Dustin R.; Danielson, Jeffrey J.; Reynolds, B.J.

2013-01-01

The higher point density and mobility of terrestrial laser scanning (light detection and ranging (lidar)) is desired when extremely detailed elevation data are needed for mapping vertically orientated complex features such as levees, dunes, and cliffs, or when highly accurate data are needed for monitoring geomorphic changes. Mobile terrestrial lidar scanners have the capability for rapid data collection on a larger spatial scale compared with tripod-based terrestrial lidar, but few studies have examined the accuracy of this relatively new mapping technology. For this reason, we conducted a field test at Padre Island National Seashore of a mobile lidar scanner mounted on a sport utility vehicle and integrated with a position and orientation system. The purpose of the study was to assess the vertical and horizontal accuracy of data collected by the mobile terrestrial lidar system, which is georeferenced to the Universal Transverse Mercator coordinate system and the North American Vertical Datum of 1988. To accomplish the study objectives, independent elevation data were collected by conducting a high-accuracy global positioning system survey to establish the coordinates and elevations of 12 targets spaced throughout the 12 km transect. These independent ground control data were compared to the lidar scanner-derived elevations to quantify the accuracy of the mobile lidar system. The performance of the mobile lidar system was also tested at various vehicle speeds and scan density settings (e.g. field of view and linear point spacing) to estimate the optimal parameters for desired point density. After adjustment of the lever arm parameters, the final point cloud accuracy was 0.060 m (east), 0.095 m (north), and 0.053 m (height). The very high density of the resulting point cloud was sufficient to map fine-scale topographic features, such as the complex shape of the sand dunes.

Accuracy Assessment of Different Digital Surface Models

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Ugur Alganci

2018-03-01

Full Text Available Digital elevation models (DEMs, which can occur in the form of digital surface models (DSMs or digital terrain models (DTMs, are widely used as important geospatial information sources for various remote sensing applications, including the precise orthorectification of high-resolution satellite images, 3D spatial analyses, multi-criteria decision support systems, and deformation monitoring. The accuracy of DEMs has direct impacts on specific calculations and process chains; therefore, it is important to select the most appropriate DEM by considering the aim, accuracy requirement, and scale of each study. In this research, DSMs obtained from a variety of satellite sensors were compared to analyze their accuracy and performance. For this purpose, freely available Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER 30 m, Shuttle Radar Topography Mission (SRTM 30 m, and Advanced Land Observing Satellite (ALOS 30 m resolution DSM data were obtained. Additionally, 3 m and 1 m resolution DSMs were produced from tri-stereo images from the SPOT 6 and Pleiades high-resolution (PHR 1A satellites, respectively. Elevation reference data provided by the General Command of Mapping, the national mapping agency of Turkey—produced from 30 cm spatial resolution stereo aerial photos, with a 5 m grid spacing and ±3 m or better overall vertical accuracy at the 90% confidence interval (CI—were used to perform accuracy assessments. Gross errors and water surfaces were removed from the reference DSM. The relative accuracies of the different DSMs were tested using a different number of checkpoints determined by different methods. In the first method, 25 checkpoints were selected from bare lands to evaluate the accuracies of the DSMs on terrain surfaces. In the second method, 1000 randomly selected checkpoints were used to evaluate the methods’ accuracies for the whole study area. In addition to the control point approach, vertical cross

Analysis of point source size on measurement accuracy of lateral point-spread function of confocal Raman microscopy

Science.gov (United States)

Fu, Shihang; Zhang, Li; Hu, Yao; Ding, Xiang

2018-01-01

Confocal Raman Microscopy (CRM) has matured to become one of the most powerful instruments in analytical science because of its molecular sensitivity and high spatial resolution. Compared with conventional Raman Microscopy, CRM can perform three dimensions mapping of tiny samples and has the advantage of high spatial resolution thanking to the unique pinhole. With the wide application of the instrument, there is a growing requirement for the evaluation of the imaging performance of the system. Point-spread function (PSF) is an important approach to the evaluation of imaging capability of an optical instrument. Among a variety of measurement methods of PSF, the point source method has been widely used because it is easy to operate and the measurement results are approximate to the true PSF. In the point source method, the point source size has a significant impact on the final measurement accuracy. In this paper, the influence of the point source sizes on the measurement accuracy of PSF is analyzed and verified experimentally. A theoretical model of the lateral PSF for CRM is established and the effect of point source size on full-width at half maximum of lateral PSF is simulated. For long-term preservation and measurement convenience, PSF measurement phantom using polydimethylsiloxane resin, doped with different sizes of polystyrene microspheres is designed. The PSF of CRM with different sizes of microspheres are measured and the results are compared with the simulation results. The results provide a guide for measuring the PSF of the CRM.

Accuracy assessment of topographic mapping using UAV image integrated with satellite images

International Nuclear Information System (INIS)

Azmi, S M; Ahmad, Baharin; Ahmad, Anuar

2014-01-01

Unmanned Aerial Vehicle or UAV is extensively applied in various fields such as military applications, archaeology, agriculture and scientific research. This study focuses on topographic mapping and map updating. UAV is one of the alternative ways to ease the process of acquiring data with lower operating costs, low manufacturing and operational costs, plus it is easy to operate. Furthermore, UAV images will be integrated with QuickBird images that are used as base maps. The objective of this study is to make accuracy assessment and comparison between topographic mapping using UAV images integrated with aerial photograph and satellite image. The main purpose of using UAV image is as a replacement for cloud covered area which normally exists in aerial photograph and satellite image, and for updating topographic map. Meanwhile, spatial resolution, pixel size, scale, geometric accuracy and correction, image quality and information contents are important requirements needed for the generation of topographic map using these kinds of data. In this study, ground control points (GCPs) and check points (CPs) were established using real time kinematic Global Positioning System (RTK-GPS) technique. There are two types of analysis that are carried out in this study which are quantitative and qualitative assessments. Quantitative assessment is carried out by calculating root mean square error (RMSE). The outputs of this study include topographic map and orthophoto. From this study, the accuracy of UAV image is ± 0.460 m. As conclusion, UAV image has the potential to be used for updating of topographic maps

Testing an Automated Accuracy Assessment Method on Bibliographic Data

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Marlies Olensky

2014-12-01

Full Text Available This study investigates automated data accuracy assessment as described in data quality literature for its suitability to assess bibliographic data. The data samples comprise the publications of two Nobel Prize winners in the field of Chemistry for a 10-year-publication period retrieved from the two bibliometric data sources, Web of Science and Scopus. The bibliographic records are assessed against the original publication (gold standard and an automatic assessment method is compared to a manual one. The results show that the manual assessment method reflects truer accuracy scores. The automated assessment method would need to be extended by additional rules that reflect specific characteristics of bibliographic data. Both data sources had higher accuracy scores per field than accumulated per record. This study contributes to the research on finding a standardized assessment method of bibliographic data accuracy as well as defining the impact of data accuracy on the citation matching process.

Reconstruction Accuracy Assessment of Surface and Underwater 3D Motion Analysis: A New Approach

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Kelly de Jesus

2015-01-01

Full Text Available This study assessed accuracy of surface and underwater 3D reconstruction of a calibration volume with and without homography. A calibration volume (6000 × 2000 × 2500 mm with 236 markers (64 above and 88 underwater control points—with 8 common points at water surface—and 92 validation points was positioned on a 25 m swimming pool and recorded with two surface and four underwater cameras. Planar homography estimation for each calibration plane was computed to perform image rectification. Direct linear transformation algorithm for 3D reconstruction was applied, using 1600000 different combinations of 32 and 44 points out of the 64 and 88 control points for surface and underwater markers (resp.. Root Mean Square (RMS error with homography of control and validations points was lower than without it for surface and underwater cameras (P≤0.03. With homography, RMS errors of control and validation points were similar between surface and underwater cameras (P≥0.47. Without homography, RMS error of control points was greater for underwater than surface cameras (P≤0.04 and the opposite was observed for validation points (P≤0.04. It is recommended that future studies using 3D reconstruction should include homography to improve swimming movement analysis accuracy.

Explicit area-based accuracy assessment for mangrove tree crown delineation using Geographic Object-Based Image Analysis (GEOBIA)

Science.gov (United States)

Kamal, Muhammad; Johansen, Kasper

2017-10-01

Effective mangrove management requires spatially explicit information of mangrove tree crown map as a basis for ecosystem diversity study and health assessment. Accuracy assessment is an integral part of any mapping activities to measure the effectiveness of the classification approach. In geographic object-based image analysis (GEOBIA) the assessment of the geometric accuracy (shape, symmetry and location) of the created image objects from image segmentation is required. In this study we used an explicit area-based accuracy assessment to measure the degree of similarity between the results of the classification and reference data from different aspects, including overall quality (OQ), user's accuracy (UA), producer's accuracy (PA) and overall accuracy (OA). We developed a rule set to delineate the mangrove tree crown using WorldView-2 pan-sharpened image. The reference map was obtained by visual delineation of the mangrove tree crowns boundaries form a very high-spatial resolution aerial photograph (7.5cm pixel size). Ten random points with a 10 m radius circular buffer were created to calculate the area-based accuracy assessment. The resulting circular polygons were used to clip both the classified image objects and reference map for area comparisons. In this case, the area-based accuracy assessment resulted 64% and 68% for the OQ and OA, respectively. The overall quality of the calculation results shows the class-related area accuracy; which is the area of correctly classified as tree crowns was 64% out of the total area of tree crowns. On the other hand, the overall accuracy of 68% was calculated as the percentage of all correctly classified classes (tree crowns and canopy gaps) in comparison to the total class area (an entire image). Overall, the area-based accuracy assessment was simple to implement and easy to interpret. It also shows explicitly the omission and commission error variations of object boundary delineation with colour coded polygons.

Accuracy Assessment of Digital Surface Models from Unmanned Aerial Vehicles’ Imagery on Glaciers

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Saskia Gindraux

2017-02-01

Full Text Available The use of Unmanned Aerial Vehicles (UAV for photogrammetric surveying has recently gained enormous popularity. Images taken from UAVs are used for generating Digital Surface Models (DSMs and orthorectified images. In the glaciological context, these can serve for quantifying ice volume change or glacier motion. This study focuses on the accuracy of UAV-derived DSMs. In particular, we analyze the influence of the number and disposition of Ground Control Points (GCPs needed for georeferencing the derived products. A total of 1321 different DSMs were generated from eight surveys distributed on three glaciers in the Swiss Alps during winter, summer and autumn. The vertical and horizontal accuracy was assessed by cross-validation with thousands of validation points measured with a Global Positioning System. Our results show that the accuracy increases asymptotically with increasing number of GCPs until a certain density of GCPs is reached. We call this the optimal GCP density. The results indicate that DSMs built with this optimal GCP density have a vertical (horizontal accuracy ranging between 0.10 and 0.25 m (0.03 and 0.09 m across all datasets. In addition, the impact of the GCP distribution on the DSM accuracy was investigated. The local accuracy of a DSM decreases when increasing the distance to the closest GCP, typically at a rate of 0.09 m per 100-m distance. The impact of the glacier’s surface texture (ice or snow was also addressed. The results show that besides cases with a surface covered by fresh snow, the surface texture does not significantly influence the DSM accuracy.

AN ASSESSMENT OF CITIZEN CONTRIBUTED GROUND REFERENCE DATA FOR LAND COVER MAP ACCURACY ASSESSMENT

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G. M. Foody

2015-08-01

Full Text Available It is now widely accepted that an accuracy assessment should be part of a thematic mapping programme. Authoritative good or best practices for accuracy assessment have been defined but are often impractical to implement. Key reasons for this situation are linked to the ground reference data used in the accuracy assessment. Typically, it is a challenge to acquire a large sample of high quality reference cases in accordance to desired sampling designs specified as conforming to good practice and the data collected are normally to some degree imperfect limiting their value to an accuracy assessment which implicitly assumes the use of a gold standard reference. Citizen sensors have great potential to aid aspects of accuracy assessment. In particular, they may be able to act as a source of ground reference data that may, for example, reduce sample size problems but concerns with data quality remain. The relative strengths and limitations of citizen contributed data for accuracy assessment are reviewed in the context of the authoritative good practices defined for studies of land cover by remote sensing. The article will highlight some of the ways that citizen contributed data have been used in accuracy assessment as well as some of the problems that require further attention, and indicate some of the potential ways forward in the future.

Ultraprecision Pointing Accuracy for SmallSat/CubeSat Attitude Control Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The primary objective of the Phase I investigation is to develop and demonstrate an innovative solution that can enable very high precision pointing accuracy...

An automated method for the evaluation of the pointing accuracy of Sun-tracking devices

Science.gov (United States)

Baumgartner, Dietmar J.; Pötzi, Werner; Freislich, Heinrich; Strutzmann, Heinz; Veronig, Astrid M.; Rieder, Harald E.

2017-03-01

The accuracy of solar radiation measurements, for direct (DIR) and diffuse (DIF) radiation, depends significantly on the precision of the operational Sun-tracking device. Thus, rigid targets for instrument performance and operation have been specified for international monitoring networks, e.g., the Baseline Surface Radiation Network (BSRN) operating under the auspices of the World Climate Research Program (WCRP). Sun-tracking devices that fulfill these accuracy requirements are available from various instrument manufacturers; however, none of the commercially available systems comprise an automatic accuracy control system allowing platform operators to independently validate the pointing accuracy of Sun-tracking sensors during operation. Here we present KSO-STREAMS (KSO-SunTRackEr Accuracy Monitoring System), a fully automated, system-independent, and cost-effective system for evaluating the pointing accuracy of Sun-tracking devices. We detail the monitoring system setup, its design and specifications, and the results from its application to the Sun-tracking system operated at the Kanzelhöhe Observatory (KSO) Austrian radiation monitoring network (ARAD) site. The results from an evaluation campaign from March to June 2015 show that the tracking accuracy of the device operated at KSO lies within BSRN specifications (i.e., 0.1° tracking accuracy) for the vast majority of observations (99.8 %). The evaluation of manufacturer-specified active-tracking accuracies (0.02°), during periods with direct solar radiation exceeding 300 W m-2, shows that these are satisfied in 72.9 % of observations. Tracking accuracies are highest during clear-sky conditions and on days where prevailing clear-sky conditions are interrupted by frontal movement; in these cases, we obtain the complete fulfillment of BSRN requirements and 76.4 % of observations within manufacturer-specified active-tracking accuracies. Limitations to tracking surveillance arise during overcast conditions and

Accuracy assessment of high resolution satellite imagery orientation by leave-one-out method

Science.gov (United States)

Brovelli, Maria Antonia; Crespi, Mattia; Fratarcangeli, Francesca; Giannone, Francesca; Realini, Eugenio

Interest in high-resolution satellite imagery (HRSI) is spreading in several application fields, at both scientific and commercial levels. Fundamental and critical goals for the geometric use of this kind of imagery are their orientation and orthorectification, processes able to georeference the imagery and correct the geometric deformations they undergo during acquisition. In order to exploit the actual potentialities of orthorectified imagery in Geomatics applications, the definition of a methodology to assess the spatial accuracy achievable from oriented imagery is a crucial topic. In this paper we want to propose a new method for accuracy assessment based on the Leave-One-Out Cross-Validation (LOOCV), a model validation method already applied in different fields such as machine learning, bioinformatics and generally in any other field requiring an evaluation of the performance of a learning algorithm (e.g. in geostatistics), but never applied to HRSI orientation accuracy assessment. The proposed method exhibits interesting features which are able to overcome the most remarkable drawbacks involved by the commonly used method (Hold-Out Validation — HOV), based on the partitioning of the known ground points in two sets: the first is used in the orientation-orthorectification model (GCPs — Ground Control Points) and the second is used to validate the model itself (CPs — Check Points). In fact the HOV is generally not reliable and it is not applicable when a low number of ground points is available. To test the proposed method we implemented a new routine that performs the LOOCV in the software SISAR, developed by the Geodesy and Geomatics Team at the Sapienza University of Rome to perform the rigorous orientation of HRSI; this routine was tested on some EROS-A and QuickBird images. Moreover, these images were also oriented using the world recognized commercial software OrthoEngine v. 10 (included in the Geomatica suite by PCI), manually performing the LOOCV

PET-MR image fusion in soft tissue sarcoma: accuracy, reliability and practicality of interactive point-based and automated mutual information techniques

International Nuclear Information System (INIS)

Somer, Edward J.R.; Marsden, Paul K.; Benatar, Nigel A.; O'Doherty, Michael J.; Goodey, Joanne; Smith, Michael A.

2003-01-01

The fusion of functional positron emission tomography (PET) data with anatomical magnetic resonance (MR) or computed tomography images, using a variety of interactive and automated techniques, is becoming commonplace, with the technique of choice dependent on the specific application. The case of PET-MR image fusion in soft tissue is complicated by a lack of conspicuous anatomical features and deviation from the rigid-body model. Here we compare a point-based external marker technique with an automated mutual information algorithm and discuss the practicality, reliability and accuracy of each when applied to the study of soft tissue sarcoma. Ten subjects with suspected sarcoma in the knee, thigh, groin, flank or back underwent MR and PET scanning after the attachment of nine external fiducial markers. In the assessment of the point-based technique, three error measures were considered: fiducial localisation error (FLE), fiducial registration error (FRE) and target registration error (TRE). FLE, which represents the accuracy with which the fiducial points can be located, is related to the FRE minimised by the registration algorithm. The registration accuracy is best characterised by the TRE, which is the distance between corresponding points in each image space after registration. In the absence of salient features within the target volume, the TRE can be measured at fiducials excluded from the registration process. To assess the mutual information technique, PET data, acquired after physically removing the markers, were reconstructed in a variety of ways and registered with MR. Having applied the transform suggested by the algorithm to the PET scan acquired before the markers were removed, the residual distance between PET and MR marker-pairs could be measured. The manual point-based technique yielded the best results (RMS TRE =8.3 mm, max =22.4 mm, min =1.7 mm), performing better than the automated algorithm (RMS TRE =20.0 mm, max =30.5 mm, min =7.7 mm) when

Assessing the accuracy of TDR-based water leak detection system

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S.M. Fatemi Aghda

2018-03-01

Full Text Available The use of TDR system to detect leakage locations in underground pipes has been developed in recent years. In this system, a bi-wire is installed in parallel with the underground pipes and is considered as a TDR sensor. This approach greatly covers the limitations arisen with using the traditional method of acoustic leak positioning. TDR based leak detection method is relatively accurate when the TDR sensor is in contact with water in just one point. Researchers have been working to improve the accuracy of this method in recent years.In this study, the ability of TDR method was evaluated in terms of the appearance of multi leakage points simultaneously. For this purpose, several laboratory tests were conducted. In these tests in order to simulate leakage points, the TDR sensor was put in contact with water at some points, then the number and the dimension of the simulated leakage points were gradually increased. The results showed that with the increase in the number and dimension of the leakage points, the error rate of the TDR-based water leak detection system increases.The authors tried, according to the results obtained from the laboratory tests, to develop a method to improve the accuracy of the TDR-based leak detection systems. To do that, they defined a few reference points on the TDR sensor. These points were created via increasing the distance between two conductors of TDR sensor and were easily identifiable in the TDR waveform. The tests were repeated again using the TDR sensor having reference points. In order to calculate the exact distance of the leakage point, the authors developed an equation in accordance to the reference points. A comparison between the results obtained from both tests (with and without reference points showed that using the method and equation developed by the authors can significantly improve the accuracy of positioning the leakage points. Keywords: Multiple leakage points, TDR, Reference points

Star Tracker Based ATP System Conceptual Design and Pointing Accuracy Estimation

Science.gov (United States)

Orfiz, Gerardo G.; Lee, Shinhak

2006-01-01

A star tracker based beaconless (a.k.a. non-cooperative beacon) acquisition, tracking and pointing concept for precisely pointing an optical communication beam is presented as an innovative approach to extend the range of high bandwidth (> 100 Mbps) deep space optical communication links throughout the solar system and to remove the need for a ground based high power laser as a beacon source. The basic approach for executing the ATP functions involves the use of stars as the reference sources from which the attitude knowledge is obtained and combined with high bandwidth gyroscopes for propagating the pointing knowledge to the beam pointing mechanism. Details of the conceptual design are presented including selection of an orthogonal telescope configuration and the introduction of an optical metering scheme to reduce misalignment error. Also, estimates are presented that demonstrate that aiming of the communications beam to the Earth based receive terminal can be achieved with a total system pointing accuracy of better than 850 nanoradians (3 sigma) from anywhere in the solar system.

3D MODELLING AND ACCURACY ASSESSMENT OF GRANITE QUARRY USING UNMMANNED AERIAL VEHICLE

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D. González-Aguilera

2012-07-01

Full Text Available The unmanned aerial vehicles (UAVs are automated systems whose main characteristic is that can be remotely piloted. This property is especially interesting in those civil engineering works in which the accuracy of the model is not reachable by common aerial or satellite systems, there is a difficult accessibility to the infrastructure due to location and geometry aspects, and the economic resources are limited. This paper aims to show the research, development and application of a UAV that will generate georeferenced spatial information at low cost, high quality, and high availability. In particular, a 3D modelling and accuracy assessment of granite quarry using UAV is applied. With regard to the image-based modelling pipeline, an automatic approach supported by open source tools is performed. The process encloses the well-known image-based modelling steps: calibration, extraction and matching of features; relative and absolute orientation of images and point cloud and surface generation. Beside this, an assessment of the final model accuracy is carried out by means of terrestrial laser scanner (TLS, imaging total station (ITS and global navigation satellite system (GNSS in order to ensure its validity. This step follows a twofold approach: (i firstly, using singular check points to provide a dimensional control of the model and (ii secondly, analyzing the level of agreement between the realitybased 3D model obtained from UAV and the generated with TLS. The main goal is to establish and validate an image-based modelling workflow using UAV technology which can be applied in the surveying and monitoring of different quarries.

Accuracy Assessment of Underwater Photogrammetric Three Dimensional Modelling for Coral Reefs

Science.gov (United States)

Guo, T.; Capra, A.; Troyer, M.; Gruen, A.; Brooks, A. J.; Hench, J. L.; Schmitt, R. J.; Holbrook, S. J.; Dubbini, M.

2016-06-01

Recent advances in automation of photogrammetric 3D modelling software packages have stimulated interest in reconstructing highly accurate 3D object geometry in unconventional environments such as underwater utilizing simple and low-cost camera systems. The accuracy of underwater 3D modelling is affected by more parameters than in single media cases. This study is part of a larger project on 3D measurements of temporal change of coral cover in tropical waters. It compares the accuracies of 3D point clouds generated by using images acquired from a system camera mounted in an underwater housing and the popular GoPro cameras respectively. A precisely measured calibration frame was placed in the target scene in order to provide accurate control information and also quantify the errors of the modelling procedure. In addition, several objects (cinder blocks) with various shapes were arranged in the air and underwater and 3D point clouds were generated by automated image matching. These were further used to examine the relative accuracy of the point cloud generation by comparing the point clouds of the individual objects with the objects measured by the system camera in air (the best possible values). Given a working distance of about 1.5 m, the GoPro camera can achieve a relative accuracy of 1.3 mm in air and 2.0 mm in water. The system camera achieved an accuracy of 1.8 mm in water, which meets our requirements for coral measurement in this system.

Assessing the accuracy of TDR-based water leak detection system

Science.gov (United States)

Fatemi Aghda, S. M.; GanjaliPour, K.; Nabiollahi, K.

2018-03-01

The use of TDR system to detect leakage locations in underground pipes has been developed in recent years. In this system, a bi-wire is installed in parallel with the underground pipes and is considered as a TDR sensor. This approach greatly covers the limitations arisen with using the traditional method of acoustic leak positioning. TDR based leak detection method is relatively accurate when the TDR sensor is in contact with water in just one point. Researchers have been working to improve the accuracy of this method in recent years. In this study, the ability of TDR method was evaluated in terms of the appearance of multi leakage points simultaneously. For this purpose, several laboratory tests were conducted. In these tests in order to simulate leakage points, the TDR sensor was put in contact with water at some points, then the number and the dimension of the simulated leakage points were gradually increased. The results showed that with the increase in the number and dimension of the leakage points, the error rate of the TDR-based water leak detection system increases. The authors tried, according to the results obtained from the laboratory tests, to develop a method to improve the accuracy of the TDR-based leak detection systems. To do that, they defined a few reference points on the TDR sensor. These points were created via increasing the distance between two conductors of TDR sensor and were easily identifiable in the TDR waveform. The tests were repeated again using the TDR sensor having reference points. In order to calculate the exact distance of the leakage point, the authors developed an equation in accordance to the reference points. A comparison between the results obtained from both tests (with and without reference points) showed that using the method and equation developed by the authors can significantly improve the accuracy of positioning the leakage points.

New Criteria for Assessing the Accuracy of Blood Glucose Monitors meeting, October 28, 2011.

Science.gov (United States)

Walsh, John; Roberts, Ruth; Vigersky, Robert A; Schwartz, Frank

2012-03-01

Glucose meters (GMs) are routinely used for self-monitoring of blood glucose by patients and for point-of-care glucose monitoring by health care providers in outpatient and inpatient settings. Although widely assumed to be accurate, numerous reports of inaccuracies with resulting morbidity and mortality have been noted. Insulin dosing errors based on inaccurate GMs are most critical. On October 28, 2011, the Diabetes Technology Society invited 45 diabetes technology clinicians who were attending the 2011 Diabetes Technology Meeting to participate in a closed-door meeting entitled New Criteria for Assessing the Accuracy of Blood Glucose Monitors. This report reflects the opinions of most of the attendees of that meeting. The Food and Drug Administration (FDA), the public, and several medical societies are currently in dialogue to establish a new standard for GM accuracy. This update to the FDA standard is driven by improved meter accuracy, technological advances (pumps, bolus calculators, continuous glucose monitors, and insulin pens), reports of hospital and outpatient deaths, consumer complaints about inaccuracy, and research studies showing that several approved GMs failed to meet FDA or International Organization for Standardization standards in postapproval testing. These circumstances mandate a set of new GM standards that appropriately match the GMs' analytical accuracy to the clinical accuracy required for their intended use, as well as ensuring their ongoing accuracy following approval. The attendees of the New Criteria for Assessing the Accuracy of Blood Glucose Monitors meeting proposed a graduated standard and other methods to improve GM performance, which are discussed in this meeting report. © 2012 Diabetes Technology Society.

Accuracy of multi-point boundary crossing time analysis

Directory of Open Access Journals (Sweden)

J. Vogt

2011-12-01

Full Text Available Recent multi-spacecraft studies of solar wind discontinuity crossings using the timing (boundary plane triangulation method gave boundary parameter estimates that are significantly different from those of the well-established single-spacecraft minimum variance analysis (MVA technique. A large survey of directional discontinuities in Cluster data turned out to be particularly inconsistent in the sense that multi-point timing analyses did not identify any rotational discontinuities (RDs whereas the MVA results of the individual spacecraft suggested that RDs form the majority of events. To make multi-spacecraft studies of discontinuity crossings more conclusive, the present report addresses the accuracy of the timing approach to boundary parameter estimation. Our error analysis is based on the reciprocal vector formalism and takes into account uncertainties both in crossing times and in the spacecraft positions. A rigorous error estimation scheme is presented for the general case of correlated crossing time errors and arbitrary spacecraft configurations. Crossing time error covariances are determined through cross correlation analyses of the residuals. The principal influence of the spacecraft array geometry on the accuracy of the timing method is illustrated using error formulas for the simplified case of mutually uncorrelated and identical errors at different spacecraft. The full error analysis procedure is demonstrated for a solar wind discontinuity as observed by the Cluster FGM instrument.

ACCURACY ASSESSMENT OF UNDERWATER PHOTOGRAMMETRIC THREE DIMENSIONAL MODELLING FOR CORAL REEFS

Directory of Open Access Journals (Sweden)

T. Guo

2016-06-01

Full Text Available Recent advances in automation of photogrammetric 3D modelling software packages have stimulated interest in reconstructing highly accurate 3D object geometry in unconventional environments such as underwater utilizing simple and low-cost camera systems. The accuracy of underwater 3D modelling is affected by more parameters than in single media cases. This study is part of a larger project on 3D measurements of temporal change of coral cover in tropical waters. It compares the accuracies of 3D point clouds generated by using images acquired from a system camera mounted in an underwater housing and the popular GoPro cameras respectively. A precisely measured calibration frame was placed in the target scene in order to provide accurate control information and also quantify the errors of the modelling procedure. In addition, several objects (cinder blocks with various shapes were arranged in the air and underwater and 3D point clouds were generated by automated image matching. These were further used to examine the relative accuracy of the point cloud generation by comparing the point clouds of the individual objects with the objects measured by the system camera in air (the best possible values. Given a working distance of about 1.5 m, the GoPro camera can achieve a relative accuracy of 1.3 mm in air and 2.0 mm in water. The system camera achieved an accuracy of 1.8 mm in water, which meets our requirements for coral measurement in this system.

Effects of LiDAR point density, sampling size and height threshold on estimation accuracy of crop biophysical parameters.

Science.gov (United States)

Luo, Shezhou; Chen, Jing M; Wang, Cheng; Xi, Xiaohuan; Zeng, Hongcheng; Peng, Dailiang; Li, Dong

2016-05-30

Vegetation leaf area index (LAI), height, and aboveground biomass are key biophysical parameters. Corn is an important and globally distributed crop, and reliable estimations of these parameters are essential for corn yield forecasting, health monitoring and ecosystem modeling. Light Detection and Ranging (LiDAR) is considered an effective technology for estimating vegetation biophysical parameters. However, the estimation accuracies of these parameters are affected by multiple factors. In this study, we first estimated corn LAI, height and biomass (R2 = 0.80, 0.874 and 0.838, respectively) using the original LiDAR data (7.32 points/m2), and the results showed that LiDAR data could accurately estimate these biophysical parameters. Second, comprehensive research was conducted on the effects of LiDAR point density, sampling size and height threshold on the estimation accuracy of LAI, height and biomass. Our findings indicated that LiDAR point density had an important effect on the estimation accuracy for vegetation biophysical parameters, however, high point density did not always produce highly accurate estimates, and reduced point density could deliver reasonable estimation results. Furthermore, the results showed that sampling size and height threshold were additional key factors that affect the estimation accuracy of biophysical parameters. Therefore, the optimal sampling size and the height threshold should be determined to improve the estimation accuracy of biophysical parameters. Our results also implied that a higher LiDAR point density, larger sampling size and height threshold were required to obtain accurate corn LAI estimation when compared with height and biomass estimations. In general, our results provide valuable guidance for LiDAR data acquisition and estimation of vegetation biophysical parameters using LiDAR data.

Effect of Heart rate on Basketball Three-Point Shot Accuracy

OpenAIRE

Luca P. Ardigò; Goran Kuvacic; Antonio D. Iacono; Giacomo Dascanio; Johnny Padulo; Johnny Padulo

2018-01-01

The three-point shot (3S) is a fundamental basketball skill used frequently during a game, and is often a main determinant of the final result. The aim of the study was to investigate the effect of different metabolic conditions, in terms of heart rates, on 3S accuracy (3S%) in 24 male (Under 17) basketball players (age 16.3 ± 0.6 yrs). 3S performance was specifically investigated at different heart rates. All sessions consisted of 10 consecutive 3Ss from five different significant field spot...

Improving the accuracy of self-assessment of practical clinical skills using video feedback--the importance of including benchmarks.

Science.gov (United States)

Hawkins, S C; Osborne, A; Schofield, S J; Pournaras, D J; Chester, J F

2012-01-01

Isolated video recording has not been demonstrated to improve self-assessment accuracy. This study examines if the inclusion of a defined standard benchmark performance in association with video feedback of a student's own performance improves the accuracy of student self-assessment of clinical skills. Final year medical students were video recorded performing a standardised suturing task in a simulated environment. After the exercise, the students self-assessed their performance using global rating scales (GRSs). An identical self-assessment process was repeated following video review of their performance. Students were then shown a video-recorded 'benchmark performance', which was specifically developed for the study. This demonstrated the competency levels required to score full marks (30 points). A further self-assessment task was then completed. Students' scores were correlated against expert assessor scores. A total of 31 final year medical students participated. Student self-assessment scores before video feedback demonstrated moderate positive correlation with expert assessor scores (r = 0.48, p benchmark performance demonstration, self-assessment scores demonstrated a very strong positive correlation with expert scores (r = 0.83, p benchmark performance in combination with video feedback may significantly improve the accuracy of students' self-assessments.

Assessment of osteoporotic vertebral fractures using specialized workflow software for 6-point morphometry

International Nuclear Information System (INIS)

Guglielmi, Giuseppe; Palmieri, Francesco; Placentino, Maria Grazia; D'Errico, Francesco; Stoppino, Luca Pio

2009-01-01

Purpose: To evaluate the time required, the accuracy and the precision of a model-based image analysis software tool for the diagnosis of osteoporotic fractures using a 6-point morphometry protocol. Materials and methods: Lateral dorsal and lumbar radiographs were performed on 92 elderly women (mean age 69.2 ± 5.7 years). Institutional review board approval and patient informed consent were obtained for all subjects. The semi-automated and the manual correct annotations of 6-point placement were compared to calculate the time consumed and the accuracy of the software. Twenty test images were randomly selected and the data obtained by multiple perturbed initialisation points on the same image were compared to assess the precision of the system. Results: The time requirement data of the semi-automated system (420 ± 67 s) were statistically different (p < 0.05) from that of manual placement (900 ± 77 s). In the accuracy test, the mean reproducibility error for semi-automatic 6-point placement was 2.50 ± 0.72% [95% CI] for the anterior-posterior reference and 2.16 ± 0.5% [95% CI] for the superior-inferior reference. In the precision test the mean error resulted averaged over all vertebrae was 2.6 ± 1.3% in terms of vertebral width. Conclusions: The technique is time effective, accurate and precise and can, therefore, be recommended in large epidemiological studies and pharmaceutical trials for reporting of osteoporotic vertebral fractures.

Positional and Dimensional Accuracy Assessment of Drone Images Geo-referenced with Three Different GPSs

Science.gov (United States)

Cao, C.; Lee, X.; Xu, J.

2017-12-01

Unmanned Aerial Vehicles (UAVs) or drones have been widely used in environmental, ecological and engineering applications in recent years. These applications require assessment of positional and dimensional accuracy. In this study, positional accuracy refers to the accuracy of the latitudinal and longitudinal coordinates of locations on the mosaicked image in reference to the coordinates of the same locations measured by a Global Positioning System (GPS) in a ground survey, and dimensional accuracy refers to length and height of a ground target. Here, we investigate the effects of the number of Ground Control Points (GCPs) and the accuracy of the GPS used to measure the GCPs on positional and dimensional accuracy of a drone 3D model. Results show that using on-board GPS and a hand-held GPS produce a positional accuracy on the order of 2-9 meters. In comparison, using a differential GPS with high accuracy (30 cm) improves the positional accuracy of the drone model by about 40 %. Increasing the number of GCPs can compensate for the uncertainty brought by the GPS equipment with low accuracy. In terms of the dimensional accuracy of the drone model, even with the use of a low resolution GPS onboard the vehicle, the mean absolute errors are only 0.04 m for height and 0.10 m for length, which are well suited for some applications in precision agriculture and in land survey studies.

Reliable and Valid Assessment of Point-of-care Ultrasonography

DEFF Research Database (Denmark)

Todsen, Tobias; Tolsgaard, Martin Grønnebæk; Olsen, Beth Härstedt

2015-01-01

physicians' OSAUS scores with diagnostic accuracy. RESULTS: The generalizability coefficient was high (0.81) and a D-study demonstrated that 1 assessor and 5 cases would result in similar reliability. The construct validity of the OSAUS scale was supported by a significant difference in the mean scores......OBJECTIVE: To explore the reliability and validity of the Objective Structured Assessment of Ultrasound Skills (OSAUS) scale for point-of-care ultrasonography (POC US) performance. BACKGROUND: POC US is increasingly used by clinicians and is an essential part of the management of acute surgical...... conditions. However, the quality of performance is highly operator-dependent. Therefore, reliable and valid assessment of trainees' ultrasonography competence is needed to ensure patient safety. METHODS: Twenty-four physicians, representing novices, intermediates, and experts in POC US, scanned 4 different...

DESIGNA ND ANALYSIS FOR THEMATIC MAP ACCURACY ASSESSMENT: FUNDAMENTAL PRINCIPLES

Science.gov (United States)

Before being used in scientific investigations and policy decisions, thematic maps constructed from remotely sensed data should be subjected to a statistically rigorous accuracy assessment. The three basic components of an accuracy assessment are: 1) the sampling design used to s...

Accuracy Assessment of a Complex Building 3d Model Reconstructed from Images Acquired with a Low-Cost Uas

Science.gov (United States)

Oniga, E.; Chirilă, C.; Stătescu, F.

2017-02-01

Nowadays, Unmanned Aerial Systems (UASs) are a wide used technique for acquisition in order to create buildings 3D models, providing the acquisition of a high number of images at very high resolution or video sequences, in a very short time. Since low-cost UASs are preferred, the accuracy of a building 3D model created using this platforms must be evaluated. To achieve results, the dean's office building from the Faculty of "Hydrotechnical Engineering, Geodesy and Environmental Engineering" of Iasi, Romania, has been chosen, which is a complex shape building with the roof formed of two hyperbolic paraboloids. Seven points were placed on the ground around the building, three of them being used as GCPs, while the remaining four as Check points (CPs) for accuracy assessment. Additionally, the coordinates of 10 natural CPs representing the building characteristic points were measured with a Leica TCR 405 total station. The building 3D model was created as a point cloud which was automatically generated based on digital images acquired with the low-cost UASs, using the image matching algorithm and different software like 3DF Zephyr, Visual SfM, PhotoModeler Scanner and Drone2Map for ArcGIS. Except for the PhotoModeler Scanner software, the interior and exterior orientation parameters were determined simultaneously by solving a self-calibrating bundle adjustment. Based on the UAS point clouds, automatically generated by using the above mentioned software and GNSS data respectively, the parameters of the east side hyperbolic paraboloid were calculated using the least squares method and a statistical blunder detection. Then, in order to assess the accuracy of the building 3D model, several comparisons were made for the facades and the roof with reference data, considered with minimum errors: TLS mesh for the facades and GNSS mesh for the roof. Finally, the front facade of the building was created in 3D based on its characteristic points using the PhotoModeler Scanner

New dual-energy X-ray absorptiometry equipment in the assessment of vertebral fractures: technical limits and software accuracy

Energy Technology Data Exchange (ETDEWEB)

Bazzocchi, Alberto; Diano, Danila; Battista, Giuseppe [University of Bologna, Sant' Orsola - Malpighi Hospital, Imaging Division, Clinical Department of Radiological and Histocytopathological Sciences, Bologna (Italy); Albisinni, Ugo [Rizzoli Orthopaedic Institute, Department of Radiology, Bologna (Italy); Rossi, Cristina [University of Parma, Section of Radiological Sciences, Department of Clinic Sciences, Parma (Italy); Guglielmi, Giuseppe [University of Foggia, Department of Radiology, Foggia (Italy); Department of Radiology, Scientific Institute Hospital ' ' Casa Sollievo della Sofferenza' ' , San Giovanni Rotondo (Italy)

2012-07-15

The aim of this study was to investigate software accuracy and influence of body mass index on image quality of Lunar iDXA (Lunar, Madison, WI, USA; software enCORE 12.0) in vertebral fracture (VFs) assessment. We enrolled 65 normal or overweight patients (group 1) and 64 obese patients (group 2) with indication for morphometric evaluation of the spine. Patients underwent iDXA, with scans performed in the standard manner by an expert technologist. Lateral images of the spine were subsequently evaluated by a musculoskeletal radiologist as the gold standard. Our analysis considered five points: vertebral bodies missed or not assessable or wrongly labeled on T4-L4 segment, diagnostic performance of the automatic morphometric point-positioning system in the detection of VFs, upgrading and downgrading of fractures, radiologist intervention rate, and BMI influence. In group 1, 57/845 (6.7%) vertebral bodies and 34/832 (4.1%) in group 2 were not assessable - the upper thoracic spine. enCORE failed to recognize vertebral levels in 5.4% of the patients (7.7% in group 1 vs. 3.1% in group 2). On a lesion-based analysis sensitivity, specificity and accuracy of the software were 81.4, 93.8, and 93.1% in group 1 and 69.1, 88.3, and 86.7% in group 2, respectively. For 52.7% of the vertebrae in group 1 (51/8 upgraded/downgraded) and 70.0% in group 2 (96/26 upgraded/downgraded), a point correction was necessary and this changed the diagnosis respectively in 29.2 and 50.0% of the patients. Differences in diagnostic performance and point correction rate were significantly different between the two groups; however, BMI did not significantly affect vertebral level labeling and was correlated with a better visualization of the whole T4-L4 spine segment. This study provides new and interesting information about the accuracy, reliability, and imaging quality provided by iDXA in the assessment of VFs. (orig.)

Rigorous accuracy assessment for 3D reconstruction using time-series Dual Fluoroscopy (DF) image pairs

Science.gov (United States)

Al-Durgham, Kaleel; Lichti, Derek D.; Kuntze, Gregor; Ronsky, Janet

2017-06-01

High-speed biplanar videoradiography, or clinically referred to as dual fluoroscopy (DF), imaging systems are being used increasingly for skeletal kinematics analysis. Typically, a DF system comprises two X-ray sources, two image intensifiers and two high-speed video cameras. The combination of these elements provides time-series image pairs of articulating bones of a joint, which permits the measurement of bony rotation and translation in 3D at high temporal resolution (e.g., 120-250 Hz). Assessment of the accuracy of 3D measurements derived from DF imaging has been the subject of recent research efforts by several groups, however with methodological limitations. This paper presents a novel and simple accuracy assessment procedure based on using precise photogrammetric tools. We address the fundamental photogrammetry principles for the accuracy evaluation of an imaging system. Bundle adjustment with selfcalibration is used for the estimation of the system parameters. The bundle adjustment calibration uses an appropriate sensor model and applies free-network constraints and relative orientation stability constraints for a precise estimation of the system parameters. A photogrammetric intersection of time-series image pairs is used for the 3D reconstruction of a rotating planar object. A point-based registration method is used to combine the 3D coordinates from the intersection and independently surveyed coordinates. The final DF accuracy measure is reported as the distance between 3D coordinates from image intersection and the independently surveyed coordinates. The accuracy assessment procedure is designed to evaluate the accuracy over the full DF image format and a wide range of object rotation. Experiment of reconstruction of a rotating planar object reported an average positional error of 0.44 +/- 0.2 mm in the derived 3D coordinates (minimum 0.05 and maximum 1.2 mm).

Study into Point Cloud Geometric Rigidity and Accuracy of TLS-Based Identification of Geometric Bodies

Science.gov (United States)

Klapa, Przemyslaw; Mitka, Bartosz; Zygmunt, Mariusz

2017-12-01

Capability of obtaining a multimillion point cloud in a very short time has made the Terrestrial Laser Scanning (TLS) a widely used tool in many fields of science and technology. The TLS accuracy matches traditional devices used in land surveying (tacheometry, GNSS - RTK), but like any measurement it is burdened with error which affects the precise identification of objects based on their image in the form of a point cloud. The point’s coordinates are determined indirectly by means of measuring the angles and calculating the time of travel of the electromagnetic wave. Each such component has a measurement error which is translated into the final result. The XYZ coordinates of a measuring point are determined with some uncertainty and the very accuracy of determining these coordinates is reduced as the distance to the instrument increases. The paper presents the results of examination of geometrical stability of a point cloud obtained by means terrestrial laser scanner and accuracy evaluation of solids determined using the cloud. Leica P40 scanner and two different settings of measuring points were used in the tests. The first concept involved placing a few balls in the field and then scanning them from various sides at similar distances. The second part of measurement involved placing balls and scanning them a few times from one side but at varying distances from the instrument to the object. Each measurement encompassed a scan of the object with automatic determination of its position and geometry. The desk studies involved a semiautomatic fitting of solids and measurement of their geometrical elements, and comparison of parameters that determine their geometry and location in space. The differences of measures of geometrical elements of balls and translations vectors of the solids centres indicate the geometrical changes of the point cloud depending on the scanning distance and parameters. The results indicate the changes in the geometry of scanned objects

Auscultation versus Point-of-care Ultrasound to Determine Endotracheal versus Bronchial Intubation: A Diagnostic Accuracy Study.

Science.gov (United States)

Ramsingh, Davinder; Frank, Ethan; Haughton, Robert; Schilling, John; Gimenez, Kimberly M; Banh, Esther; Rinehart, Joseph; Cannesson, Maxime

2016-05-01

Unrecognized malposition of the endotracheal tube (ETT) can lead to severe complications in patients under general anesthesia. The focus of this double-blinded randomized study was to assess the accuracy of point-of-care ultrasound in verifying the correct position of the ETT and to compare it with the accuracy of auscultation. Forty-two adult patients requiring general anesthesia with ETT were consented. Patients were randomized to right main bronchus, left main bronchus, or tracheal intubation. After randomization, the ETT was placed via fiber-optic visualization. Next, the location of the ETT was assessed using auscultation by a separate blinded anesthesiologist, followed by an ultrasound performed by a third blinded anesthesiologist. Ultrasound examination included assessment of tracheal dilation via cuff inflation with air and evaluation of pleural lung sliding. Statistical analysis included sensitivity, specificity, positive predictive value, negative predictive value, and interobserver agreement for the ultrasound examination (95% CI). In differentiating tracheal versus bronchial intubations, auscultation showed a sensitivity of 66% (0.39 to 0.87) and a specificity of 59% (0.39 to 0.77), whereas ultrasound showed a sensitivity of 93% (0.66 to 0.99) and specificity of 96% (0.79 to 1). Identification of tracheal versus bronchial intubation was 62% (26 of 42) in the auscultation group and 95% (40 of 42) in the ultrasound group (P = 0.0005) (CI for difference, 0.15 to 0.52), and the McNemar comparison showed statistically significant improvement with ultrasound (P auscultation in determining the location of ETT.

Error and Uncertainty in the Accuracy Assessment of Land Cover Maps

Science.gov (United States)

Sarmento, Pedro Alexandre Reis

Traditionally the accuracy assessment of land cover maps is performed through the comparison of these maps with a reference database, which is intended to represent the "real" land cover, being this comparison reported with the thematic accuracy measures through confusion matrixes. Although, these reference databases are also a representation of reality, containing errors due to the human uncertainty in the assignment of the land cover class that best characterizes a certain area, causing bias in the thematic accuracy measures that are reported to the end users of these maps. The main goal of this dissertation is to develop a methodology that allows the integration of human uncertainty present in reference databases in the accuracy assessment of land cover maps, and analyse the impacts that uncertainty may have in the thematic accuracy measures reported to the end users of land cover maps. The utility of the inclusion of human uncertainty in the accuracy assessment of land cover maps is investigated. Specifically we studied the utility of fuzzy sets theory, more precisely of fuzzy arithmetic, for a better understanding of human uncertainty associated to the elaboration of reference databases, and their impacts in the thematic accuracy measures that are derived from confusion matrixes. For this purpose linguistic values transformed in fuzzy intervals that address the uncertainty in the elaboration of reference databases were used to compute fuzzy confusion matrixes. The proposed methodology is illustrated using a case study in which the accuracy assessment of a land cover map for Continental Portugal derived from Medium Resolution Imaging Spectrometer (MERIS) is made. The obtained results demonstrate that the inclusion of human uncertainty in reference databases provides much more information about the quality of land cover maps, when compared with the traditional approach of accuracy assessment of land cover maps. None

Assessment of the thematic accuracy of land cover maps

DEFF Research Database (Denmark)

Høhle, Joachim

2015-01-01

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...... 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......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...

Accuracy assessment of TanDEM-X IDEM using airborne LiDAR on the area of Poland

Directory of Open Access Journals (Sweden)

Woroszkiewicz Małgorzata

2017-06-01

Full Text Available The TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X mission launched in 2010 is another programme – after the Shuttle Radar Topography Mission (SRTM in 2000 – that uses space-borne radar interferometry to build a global digital surface model. This article presents the accuracy assessment of the TanDEM-X intermediate Digital Elevation Model (IDEM provided by the German Aerospace Center (DLR under the project “Accuracy assessment of a Digital Elevation Model based on TanDEM-X data” for the southwestern territory of Poland. The study area included: open terrain, urban terrain and forested terrain. Based on a set of 17,498 reference points acquired by airborne laser scanning, the mean errors of average heights and standard deviations were calculated for areas with a terrain slope below 2 degrees, between 2 and 6 degrees and above 6 degrees. The absolute accuracy of the IDEM data for the analysed area, expressed as a root mean square error (Total RMSE, was 0.77 m.

Fine-resolution repeat topographic surveying of dryland landscapes using UAS-based structure-from-motion photogrammetry: Assessing accuracy and precision against traditional ground-based erosion measurements

Science.gov (United States)

Gillian, Jeffrey K.; Karl, Jason W.; Elaksher, Ahmed; Duniway, Michael C.

2017-01-01

Structure-from-motion (SfM) photogrammetry from unmanned aerial system (UAS) imagery is an emerging tool for repeat topographic surveying of dryland erosion. These methods are particularly appealing due to the ability to cover large landscapes compared to field methods and at reduced costs and finer spatial resolution compared to airborne laser scanning. Accuracy and precision of high-resolution digital terrain models (DTMs) derived from UAS imagery have been explored in many studies, typically by comparing image coordinates to surveyed check points or LiDAR datasets. In addition to traditional check points, this study compared 5 cm resolution DTMs derived from fixed-wing UAS imagery with a traditional ground-based method of measuring soil surface change called erosion bridges. We assessed accuracy by comparing the elevation values between DTMs and erosion bridges along thirty topographic transects each 6.1 m long. Comparisons occurred at two points in time (June 2014, February 2015) which enabled us to assess vertical accuracy with 3314 data points and vertical precision (i.e., repeatability) with 1657 data points. We found strong vertical agreement (accuracy) between the methods (RMSE 2.9 and 3.2 cm in June 2014 and February 2015, respectively) and high vertical precision for the DTMs (RMSE 2.8 cm). Our results from comparing SfM-generated DTMs to check points, and strong agreement with erosion bridge measurements suggests repeat UAS imagery and SfM processing could replace erosion bridges for a more synoptic landscape assessment of shifting soil surfaces for some studies. However, while collecting the UAS imagery and generating the SfM DTMs for this study was faster than collecting erosion bridge measurements, technical challenges related to the need for ground control networks and image processing requirements must be addressed before this technique could be applied effectively to large landscapes.

Assessing the Accuracy of Ancestral Protein Reconstruction Methods

OpenAIRE

Williams, Paul D; Pollock, David D; Blackburne, Benjamin P; Goldstein, Richard A

2006-01-01

The phylogenetic inference of ancestral protein sequences is a powerful technique for the study of molecular evolution, but any conclusions drawn from such studies are only as good as the accuracy of the reconstruction method. Every inference method leads to errors in the ancestral protein sequence, resulting in potentially misleading estimates of the ancestral protein's properties. To assess the accuracy of ancestral protein reconstruction methods, we performed computational population evolu...

Effect of Anisotropy on Shape Measurement Accuracy of Silicon Wafer Using Three-Point-Support Inverting Method

Science.gov (United States)

Ito, Yukihiro; Natsu, Wataru; Kunieda, Masanori

This paper describes the influences of anisotropy found in the elastic modulus of monocrystalline silicon wafers on the measurement accuracy of the three-point-support inverting method which can measure the warp and thickness of thin large panels simultaneously. Deflection due to gravity depends on the crystal orientation relative to the positions of the three-point-supports. Thus the deviation of actual crystal orientation from the direction indicated by the notch fabricated on the wafer causes measurement errors. Numerical analysis of the deflection confirmed that the uncertainty of thickness measurement increases from 0.168µm to 0.524µm due to this measurement error. In addition, experimental results showed that the rotation of crystal orientation relative to the three-point-supports is effective for preventing wafer vibration excited by disturbance vibration because the resonance frequency of wafers can be changed. Thus, surface shape measurement accuracy was improved by preventing resonant vibration during measurement.

Accuracy Assessment in Determining the Location of Corners of Building Structures Using a Combination of Various Measurement Methods

Science.gov (United States)

Krzyżek, Robert; Przewięźlikowska, Anna

2017-12-01

When surveys of corners of building structures are carried out, surveyors frequently use a compilation of two surveying methods. The first one involves the determination of several corners with reference to a geodetic control using classical methods of surveying field details. The second method relates to the remaining corner points of a structure, which are determined in sequence from distance-distance intersection, using control linear values of the wall faces of the building, the so-called tie distances. This paper assesses the accuracy of coordinates of corner points of a building structure, determined using the method of distance-distance intersection, based on the corners which had previously been determined by the conducted surveys tied to a geodetic control. It should be noted, however, that such a method of surveying the corners of building structures from linear measures is based on the details of the first-order accuracy, while the regulations explicitly allow such measurement only for the details of the second- and third-order accuracy. Therefore, a question arises whether this legal provision is unfounded, or whether surveyors are acting not only against the applicable standards but also without due diligence while performing surveys? This study provides answers to the formulated problem. The main purpose of the study was to verify whether the actual method which is used in practice for surveying building structures allows to obtain the required accuracy of coordinates of the points being determined, or whether it should be strictly forbidden. The results of the conducted studies clearly demonstrate that the problem is definitely more complex. Eventually, however, it might be assumed that assessment of the accuracy in determining a location of corners of a building using a combination of two different surveying methods will meet the requirements of the regulation [MIA, 2011), subject to compliance with relevant baseline criteria, which have been

NEPR Accuracy Assessment Points - 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater photos and videos taken in shallow water (0-35m) benthic habitats surrounding Northeast Puerto Rico and Culebra...

Gulf of Maine - Control Points Used to Validate the Accuracies of the Interpolated Water Density Rasters

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This feature dataset contains the control points used to validate the accuracies of the interpolated water density rasters for the Gulf of Maine. These control...

ACCURACY ASSESSMENT OF COASTAL TOPOGRAPHY DERIVED FROM UAV IMAGES

Directory of Open Access Journals (Sweden)

N. Long

2016-06-01

Full Text Available To monitor coastal environments, Unmanned Aerial Vehicle (UAV is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR or Terrestrial Laser Scanning (TLS, this solution produces Digital Surface Model (DSM with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm, a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs and the influence of spatial image resolution (4.6 cm vs 2 cm. The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (< 10 cm. The georeferencing of the DSM require a homogeneous distribution and a large number of GCPs. The accuracy is correlated with the number of GCPs (use 19 GCPs instead of 10 allows to reduce the difference of 4 cm; the required accuracy should be dependant of the research problematic. Last, in this particular environment, the presence of very small water surfaces on the sand bank does not allow to improve the accuracy when the spatial resolution of images is decreased.

Improvement of the Accuracy of InSAR Image Co-Registration Based On Tie Points – A Review

Directory of Open Access Journals (Sweden)

Xiaoli Ding

2009-02-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR is a new measurement technology, making use of the phase information contained in the Synthetic Aperture Radar (SAR images. InSAR has been recognized as a potential tool for the generation of digital elevation models (DEMs and the measurement of ground surface deformations. However, many critical factors affect the quality of InSAR data and limit its applications. One of the factors is InSAR data processing, which consists of image co-registration, interferogram generation, phase unwrapping and geocoding. The co-registration of InSAR images is the first step and dramatically influences the accuracy of InSAR products. In this paper, the principle and processing procedures of InSAR techniques are reviewed. One of important factors, tie points, to be considered in the improvement of the accuracy of InSAR image co-registration are emphatically reviewed, such as interval of tie points, extraction of feature points, window size for tie point matching and the measurement for the quality of an interferogram.

Diagnostic accuracy of refractometry for assessing bovine colostrum quality: A systematic review and meta-analysis.

Science.gov (United States)

Buczinski, S; Vandeweerd, J M

2016-09-01

Provision of good quality colostrum [i.e., immunoglobulin G (IgG) concentration ≥50g/L] is the first step toward ensuring proper passive transfer of immunity for young calves. Precise quantification of colostrum IgG levels cannot be easily performed on the farm. Assessment of the refractive index using a Brix scale with a refractometer has been described as being highly correlated with IgG concentration in colostrum. The aim of this study was to perform a systematic review of the diagnostic accuracy of Brix refractometry to diagnose good quality colostrum. From 101 references initially obtain ed, 11 were included in the systematic review meta-analysis representing 4,251 colostrum samples. The prevalence of good colostrum samples with IgG ≥50g/L varied from 67.3 to 92.3% (median 77.9%). Specific estimates of accuracy [sensitivity (Se) and specificity (Sp)] were obtained for different reported cut-points using a hierarchical summary receiver operating characteristic curve model. For the cut-point of 22% (n=8 studies), Se=80.2% (95% CI: 71.1-87.0%) and Sp=82.6% (71.4-90.0%). Decreasing the cut-point to 18% increased Se [96.1% (91.8-98.2%)] and decreased Sp [54.5% (26.9-79.6%)]. Modeling the effect of these Brix accuracy estimates using a stochastic simulation and Bayes theorem showed that a positive result with the 22% Brix cut-point can be used to diagnose good quality colostrum (posttest probability of a good colostrum: 94.3% (90.7-96.9%). The posttest probability of good colostrum with a Brix value <18% was only 22.7% (12.3-39.2%). Based on this study, the 2 cut-points could be alternatively used to select good quality colostrum (sample with Brix ≥22%) or to discard poor quality colostrum (sample with Brix <18%). When sample results are between these 2 values, colostrum supplementation should be considered. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Accuracy assessment of the global TanDEM-X Digital Elevation Model with GPS data

Science.gov (United States)

Wessel, Birgit; Huber, Martin; Wohlfart, Christian; Marschalk, Ursula; Kosmann, Detlev; Roth, Achim

2018-05-01

The primary goal of the German TanDEM-X mission is the generation of a highly accurate and global Digital Elevation Model (DEM) with global accuracies of at least 10 m absolute height error (linear 90% error). The global TanDEM-X DEM acquired with single-pass SAR interferometry was finished in September 2016. This paper provides a unique accuracy assessment of the final TanDEM-X global DEM using two different GPS point reference data sets, which are distributed across all continents, to fully characterize the absolute height error. Firstly, the absolute vertical accuracy is examined by about three million globally distributed kinematic GPS (KGPS) points derived from 19 KGPS tracks covering a total length of about 66,000 km. Secondly, a comparison is performed with more than 23,000 "GPS on Bench Marks" (GPS-on-BM) points provided by the US National Geodetic Survey (NGS) scattered across 14 different land cover types of the US National Land Cover Data base (NLCD). Both GPS comparisons prove an absolute vertical mean error of TanDEM-X DEM smaller than ±0.20 m, a Root Means Square Error (RMSE) smaller than 1.4 m and an excellent absolute 90% linear height error below 2 m. The RMSE values are sensitive to land cover types. For low vegetation the RMSE is ±1.1 m, whereas it is slightly higher for developed areas (±1.4 m) and for forests (±1.8 m). This validation confirms an outstanding absolute height error at 90% confidence level of the global TanDEM-X DEM outperforming the requirement by a factor of five. Due to its extensive and globally distributed reference data sets, this study is of considerable interests for scientific and commercial applications.

Scan-To Output Validation: Towards a Standardized Geometric Quality Assessment of Building Information Models Based on Point Clouds

Science.gov (United States)

Bonduel, M.; Bassier, M.; Vergauwen, M.; Pauwels, P.; Klein, R.

2017-11-01

The use of Building Information Modeling (BIM) for existing buildings based on point clouds is increasing. Standardized geometric quality assessment of the BIMs is needed to make them more reliable and thus reusable for future users. First, available literature on the subject is studied. Next, an initial proposal for a standardized geometric quality assessment is presented. Finally, this method is tested and evaluated with a case study. The number of specifications on BIM relating to existing buildings is limited. The Levels of Accuracy (LOA) specification of the USIBD provides definitions and suggestions regarding geometric model accuracy, but lacks a standardized assessment method. A deviation analysis is found to be dependent on (1) the used mathematical model, (2) the density of the point clouds and (3) the order of comparison. Results of the analysis can be graphical and numerical. An analysis on macro (building) and micro (BIM object) scale is necessary. On macro scale, the complete model is compared to the original point cloud and vice versa to get an overview of the general model quality. The graphical results show occluded zones and non-modeled objects respectively. Colored point clouds are derived from this analysis and integrated in the BIM. On micro scale, the relevant surface parts are extracted per BIM object and compared to the complete point cloud. Occluded zones are extracted based on a maximum deviation. What remains is classified according to the LOA specification. The numerical results are integrated in the BIM with the use of object parameters.

Accuracy of young male drivers’ self-assessments of driving skill

DEFF Research Database (Denmark)

Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

2017-01-01

Accurate self-assessment of skill is important because it creates an appropriate level of confidence and hence behaviour. Inaccurate self-assessment of driving ability has been linked to reckless driving and accidents. Inaccurate self-assessment of driving skills may be a contributing factor...... to the over-representation of young male drivers in accident statistics. Most previous research on self-assessment of driving skills did not compare self-reported skills to objectively measured driving skills, so the aims of this study were: (1) to test the accuracy of young male drivers’ self......-assessments of specific driving skills by comparing them with performance in a driving simulator; (2) to test whether self-assessment accuracy varied with driving skill, driving experience and sensation-seeking propensity. We found that young male drivers’ self-assessments were inconsistent with their driving performance...

Two-point paraxial traveltime formula for inhomogeneous isotropic and anisotropic media: Tests of accuracy

KAUST Repository

Waheed, Umair bin; Psencik, Ivan; Cerveny, Vlastislav; Iversen, Einar; Alkhalifah, Tariq Ali

2013-01-01

On several simple models of isotropic and anisotropic media, we have studied the accuracy of the two-point paraxial traveltime formula designed for the approximate calculation of the traveltime between points S' and R' located in the vicinity of points S and R on a reference ray. The reference ray may be situated in a 3D inhomogeneous isotropic or anisotropic medium with or without smooth curved interfaces. The twopoint paraxial traveltime formula has the form of the Taylor expansion of the two-point traveltime with respect to spatial Cartesian coordinates up to quadratic terms at points S and R on the reference ray. The constant term and the coefficients of the linear and quadratic terms are determined from quantities obtained from ray tracing and linear dynamic ray tracing along the reference ray. The use of linear dynamic ray tracing allows the evaluation of the quadratic terms in arbitrarily inhomogeneous media and, as shown by examples, it extends the region of accurate results around the reference ray between S and R (and even outside this interval) obtained with the linear terms only. Although the formula may be used for very general 3D models, we concentrated on simple 2D models of smoothly inhomogeneous isotropic and anisotropic (~8% and ~20% anisotropy) media only. On tests, in which we estimated twopoint traveltimes between a shifted source and a system of shifted receivers, we found that the formula may yield more accurate results than the numerical solution of an eikonal-based differential equation. The tests also indicated that the accuracy of the formula depends primarily on the length and the curvature of the reference ray and only weakly depends on anisotropy. The greater is the curvature of the reference ray, the narrower its vicinity, in which the formula yields accurate results.

Two-point paraxial traveltime formula for inhomogeneous isotropic and anisotropic media: Tests of accuracy

KAUST Repository

Waheed, Umair bin

2013-09-01

On several simple models of isotropic and anisotropic media, we have studied the accuracy of the two-point paraxial traveltime formula designed for the approximate calculation of the traveltime between points S\\' and R\\' located in the vicinity of points S and R on a reference ray. The reference ray may be situated in a 3D inhomogeneous isotropic or anisotropic medium with or without smooth curved interfaces. The twopoint paraxial traveltime formula has the form of the Taylor expansion of the two-point traveltime with respect to spatial Cartesian coordinates up to quadratic terms at points S and R on the reference ray. The constant term and the coefficients of the linear and quadratic terms are determined from quantities obtained from ray tracing and linear dynamic ray tracing along the reference ray. The use of linear dynamic ray tracing allows the evaluation of the quadratic terms in arbitrarily inhomogeneous media and, as shown by examples, it extends the region of accurate results around the reference ray between S and R (and even outside this interval) obtained with the linear terms only. Although the formula may be used for very general 3D models, we concentrated on simple 2D models of smoothly inhomogeneous isotropic and anisotropic (~8% and ~20% anisotropy) media only. On tests, in which we estimated twopoint traveltimes between a shifted source and a system of shifted receivers, we found that the formula may yield more accurate results than the numerical solution of an eikonal-based differential equation. The tests also indicated that the accuracy of the formula depends primarily on the length and the curvature of the reference ray and only weakly depends on anisotropy. The greater is the curvature of the reference ray, the narrower its vicinity, in which the formula yields accurate results.

Control over structure-specific flexibility improves anatomical accuracy for point-based deformable registration in bladder cancer radiotherapy.

Science.gov (United States)

Wognum, S; Bondar, L; Zolnay, A G; Chai, X; Hulshof, M C C M; Hoogeman, M S; Bel, A

2013-02-01

Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors' unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight parameters were determined

Control over structure-specific flexibility improves anatomical accuracy for point-based deformable registration in bladder cancer radiotherapy

International Nuclear Information System (INIS)

Wognum, S.; Chai, X.; Hulshof, M. C. C. M.; Bel, A.; Bondar, L.; Zolnay, A. G.; Hoogeman, M. S.

2013-01-01

Purpose: Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors’ unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. Methods: The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight

Control over structure-specific flexibility improves anatomical accuracy for point-based deformable registration in bladder cancer radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Wognum, S.; Chai, X.; Hulshof, M. C. C. M.; Bel, A. [Department of Radiotherapy, Academic Medical Center, Meiberdreef 9, 1105 AZ Amsterdam (Netherlands); Bondar, L.; Zolnay, A. G.; Hoogeman, M. S. [Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus Medical Center, Groene Hilledijk 301, 3075 EA Rotterdam (Netherlands)

2013-02-15

Purpose: Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors' unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. Methods: The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight

Image-based in vivo assessment of targeting accuracy of stereotactic brain surgery in experimental rodent models

Science.gov (United States)

Rangarajan, Janaki Raman; Vande Velde, Greetje; van Gent, Friso; de Vloo, Philippe; Dresselaers, Tom; Depypere, Maarten; van Kuyck, Kris; Nuttin, Bart; Himmelreich, Uwe; Maes, Frederik

2016-11-01

Stereotactic neurosurgery is used in pre-clinical research of neurological and psychiatric disorders in experimental rat and mouse models to engraft a needle or electrode at a pre-defined location in the brain. However, inaccurate targeting may confound the results of such experiments. In contrast to the clinical practice, inaccurate targeting in rodents remains usually unnoticed until assessed by ex vivo end-point histology. We here propose a workflow for in vivo assessment of stereotactic targeting accuracy in small animal studies based on multi-modal post-operative imaging. The surgical trajectory in each individual animal is reconstructed in 3D from the physical implant imaged in post-operative CT and/or its trace as visible in post-operative MRI. By co-registering post-operative images of individual animals to a common stereotaxic template, targeting accuracy is quantified. Two commonly used neuromodulation regions were used as targets. Target localization errors showed not only variability, but also inaccuracy in targeting. Only about 30% of electrodes were within the subnucleus structure that was targeted and a-specific adverse effects were also noted. Shifting from invasive/subjective 2D histology towards objective in vivo 3D imaging-based assessment of targeting accuracy may benefit a more effective use of the experimental data by excluding off-target cases early in the study.

Meditation experience predicts introspective accuracy.

Directory of Open Access Journals (Sweden)

Kieran C R Fox

Full Text Available The accuracy of subjective reports, especially those involving introspection of one's own internal processes, remains unclear, and research has demonstrated large individual differences in introspective accuracy. It has been hypothesized that introspective accuracy may be heightened in persons who engage in meditation practices, due to the highly introspective nature of such practices. We undertook a preliminary exploration of this hypothesis, examining introspective accuracy in a cross-section of meditation practitioners (1-15,000 hrs experience. Introspective accuracy was assessed by comparing subjective reports of tactile sensitivity for each of 20 body regions during a 'body-scanning' meditation with averaged, objective measures of tactile sensitivity (mean size of body representation area in primary somatosensory cortex; two-point discrimination threshold as reported in prior research. Expert meditators showed significantly better introspective accuracy than novices; overall meditation experience also significantly predicted individual introspective accuracy. These results suggest that long-term meditators provide more accurate introspective reports than novices.

A Photogrammetric Approach for Assessing Positional Accuracy of OpenStreetMap© Roads

Directory of Open Access Journals (Sweden)

Peter Doucette

2013-04-01

Full Text Available As open source volunteered geographic information continues to gain popularity, the user community and data contributions are expected to grow, e.g., CloudMade, Apple, and Ushahidi now provide OpenStreetMap© (OSM as a base layer for some of their mapping applications. This, coupled with the lack of cartographic standards and the expectation to one day be able to use this vector data for more geopositionally sensitive applications, like GPS navigation, leaves potential users and researchers to question the accuracy of the database. This research takes a photogrammetric approach to determining the positional accuracy of OSM road features using stereo imagery and a vector adjustment model. The method applies rigorous analytical measurement principles to compute accurate real world geolocations of OSM road vectors. The proposed approach was tested on several urban gridded city streets from the OSM database with the results showing that the post adjusted shape points improved positionally by 86%. Furthermore, the vector adjustment was able to recover 95% of the actual positional displacement present in the database. To demonstrate a practical application, a head-to-head positional accuracy assessment between OSM, the USGS National Map (TNM, and United States Census Bureau’s Topologically Integrated Geographic Encoding Referencing (TIGER 2007 roads was conducted.

An ultrahigh-accuracy Miniature Dew Point Sensor based on an Integrated Photonics Platform

Science.gov (United States)

Tao, Jifang; Luo, Yu; Wang, Li; Cai, Hong; Sun, Tao; Song, Junfeng; Liu, Hui; Gu, Yuandong

2016-07-01

The dew point is the temperature at which vapour begins to condense out of the gaseous phase. The deterministic relationship between the dew point and humidity is the basis for the industry-standard “chilled-mirror” dew point hygrometers used for highly accurate humidity measurements, which are essential for a broad range of industrial and metrological applications. However, these instruments have several limitations, such as high cost, large size and slow response. In this report, we demonstrate a compact, integrated photonic dew point sensor (DPS) that features high accuracy, a small footprint, and fast response. The fundamental component of this DPS is a partially exposed photonic micro-ring resonator, which serves two functions simultaneously: 1) sensing the condensed water droplets via evanescent fields and 2) functioning as a highly accurate, in situ temperature sensor based on the thermo-optic effect (TOE). This device virtually eliminates most of the temperature-related errors that affect conventional “chilled-mirror” hygrometers. Moreover, this DPS outperforms conventional “chilled-mirror” hygrometers with respect to size, cost and response time, paving the way for on-chip dew point detection and extension to applications for which the conventional technology is unsuitable because of size, cost, and other constraints.

The Assessment of Quality, Accuracy, and Readability of Online Educational Resources for Platelet-Rich Plasma.

Science.gov (United States)

Ghodasra, Jason H; Wang, Dean; Jayakar, Rohit G; Jensen, Andrew R; Yamaguchi, Kent T; Hegde, Vishal V; Jones, Kristofer J

2018-01-01

To critically evaluate the quality, accuracy, and readability of readily available Internet patient resources for platelet-rich plasma (PRP) as a treatment modality for musculoskeletal injuries. Using the 3 most commonly used Internet search engines (Google, Bing, Yahoo), the search term "platelet rich plasma" was entered, and the first 50 websites from each search were reviewed. The website's affiliation was identified. Quality was evaluated using 25-point criteria based on guidelines published by the American Academy of Orthopaedic Surgeons, and accuracy was assessed with a previously described 12-point grading system by 3 reviewers independently. Readability was evaluated using the Flesch-Kincaid (FK) grade score. A total of 46 unique websites were identified and evaluated. The average quality and accuracy was 9.4 ± 3.4 (maximum 25) and 7.9 ± 2.3 (maximum 12), respectively. The average FK grade level was 12.6 ± 2.4, which is several grades higher than the recommended eighth-grade level for patient education material. Ninety-one percent (42/46) of websites were authored by physicians, and 9% (4/46) contained commercial bias. Mean quality was significantly greater in websites authored by health care providers (9.8 ± 3.1 vs 5.9 ± 4.7, P = .029) and in websites without commercial bias (9.9 ± 3.1 vs 4.5 ± 3.2, P = .002). Mean accuracy was significantly lower in websites authored by health care providers (7.6 ± 2.2 vs 11.0 ± 1.2, P = .004). Only 24% (11/46) reported that PRP remains an investigational treatment. The accuracy and quality of online patient resources for PRP are poor, and the information overestimates the reading ability of the general population. Websites authored by health care providers had higher quality but lower accuracy. Additionally, the majority of websites do not identify PRP as an experimental treatment, which may fail to provide appropriate patient understanding and expectations. Physicians should educate patients that many online

Segmenting Bone Parts for Bone Age Assessment using Point Distribution Model and Contour Modelling

Science.gov (United States)

Kaur, Amandeep; Singh Mann, Kulwinder, Dr.

2018-01-01

Bone age assessment (BAA) is a task performed on radiographs by the pediatricians in hospitals to predict the final adult height, to diagnose growth disorders by monitoring skeletal development. For building an automatic bone age assessment system the step in routine is to do image pre-processing of the bone X-rays so that features row can be constructed. In this research paper, an enhanced point distribution algorithm using contours has been implemented for segmenting bone parts as per well-established procedure of bone age assessment that would be helpful in building feature row and later on; it would be helpful in construction of automatic bone age assessment system. Implementation of the segmentation algorithm shows high degree of accuracy in terms of recall and precision in segmenting bone parts from left hand X-Rays.

Dose delivery verification and accuracy assessment of stereotaxy in stereotactic radiotherapy and radiosurgery

International Nuclear Information System (INIS)

Pelagade, S.M.; Bopche, T.T.; Namitha, K.; Munshi, M.; Bhola, S.; Sharma, H.; Patel, B.K.; Vyas, R.K.

2008-01-01

The outcome of stereotactic radiotherapy (SRT) and stereotactic radiosurgery (SRS) in both benign and malignant tumors within the cranial region highly depends on precision in dosimetry, dose delivery and the accuracy assessment of stereotaxy associated with the unit. The frames BRW (Brown-Roberts-Wells) and GTC (Gill- Thomas-Cosman) can facilitate accurate patient positioning as well as precise targeting of tumours. The implementation of this technique may result in a significant benefit as compared to conventional therapy. As the target localization accuracy is improved, the demand for treatment planning accuracy of a TPS is also increased. The accuracy of stereotactic X Knife treatment planning system has two components to verify: (i) the dose delivery verification and the accuracy assessment of stereotaxy; (ii) to ensure that the Cartesian coordinate system associated is well established within the TPS for accurate determination of a target position. Both dose delivery verification and target positional accuracy affect dose delivery accuracy to a defined target. Hence there is a need to verify these two components in quality assurance protocol. The main intention of this paper is to present our dose delivery verification procedure using cylindrical wax phantom and accuracy assessment (target position) of stereotaxy using Geometric Phantom on Elekta's Precise linear accelerator for stereotactic installation

Pixels, Blocks of Pixels, and Polygons: Choosing a Spatial Unit for Thematic Accuracy Assessment

Science.gov (United States)

Pixels, polygons, and blocks of pixels are all potentially viable spatial assessment units for conducting an accuracy assessment. We develop a statistical population-based framework to examine how the spatial unit chosen affects the outcome of an accuracy assessment. The populati...

Temporal subtraction in chest radiography: Automated assessment of registration accuracy

International Nuclear Information System (INIS)

Armato, Samuel G. III; Doshi, Devang J.; Engelmann, Roger; Croteau, Charles L.; MacMahon, Heber

2006-01-01

Radiologists routinely compare multiple chest radiographs acquired from the same patient over time to more completely understand changes in anatomy and pathology. While such comparisons are achieved conventionally through a side-by-side display of images, image registration techniques have been developed to combine information from two separate radiographic images through construction of a 'temporal subtraction image'. Although temporal subtraction images provide a powerful mechanism for the enhanced visualization of subtle change, errors in the clinical evaluation of these images may arise from misregistration artifacts that can mimic or obscure pathologic change. We have developed a computerized method for the automated assessment of registration accuracy as demonstrated in temporal subtraction images created from radiographic chest image pairs. The registration accuracy of 150 temporal subtraction images constructed from the computed radiography images of 72 patients was rated manually using a five-point scale ranging from '5-excellent' to '1-poor'; ratings of 3, 4, or 5 reflected clinically acceptable subtraction images, and ratings of 1 or 2 reflected clinically unacceptable images. Gray-level histogram-based features and texture measures are computed at multiple spatial scales within a 'lung mask' region that encompasses both lungs in the temporal subtraction images. A subset of these features is merged through a linear discriminant classifier. With a leave-one-out-by-patient training/testing paradigm, the automated method attained an A z value of 0.92 in distinguishing between temporal subtraction images that demonstrated clinically acceptable and clinically unacceptable registration accuracy. A second linear discriminant classifier yielded an A z value of 0.82 based on a feature subset selected from an independent database of digitized film images. These methods are expected to advance the clinical utility of temporal subtraction images for chest

Accuracy enhancement of point triangulation probes for linear displacement measurement

Science.gov (United States)

Kim, Kyung-Chan; Kim, Jong-Ahn; Oh, SeBaek; Kim, Soo Hyun; Kwak, Yoon Keun

2000-03-01

Point triangulation probes (PTBs) fall into a general category of noncontact height or displacement measurement devices. PTBs are widely used for their simple structure, high resolution, and long operating range. However, there are several factors that must be taken into account in order to obtain high accuracy and reliability; measurement errors from inclinations of an object surface, probe signal fluctuations generated by speckle effects, power variation of a light source, electronic noises, and so on. In this paper, we propose a novel signal processing algorithm, named as EASDF (expanded average square difference function), for a newly designed PTB which is composed of an incoherent source (LED), a line scan array detector, a specially selected diffuse reflecting surface, and several optical components. The EASDF, which is a modified correlation function, is able to calculate displacement between the probe and the object surface effectively even if there are inclinations, power fluctuations, and noises.

Assessing the accuracy of remote sensing techniques in vegetation ...

African Journals Online (AJOL)

Assessing the accuracy of remote sensing techniques in vegetation fractions estimation. ... This study aimed at exploring different remote sensing (RS) techniques for quantitatively measuring vegetation and bare soil ... HOW TO USE AJOL.

The reproducibility of some thermometric fixed points and the accuracy of temperature measurements using platinum resistance thermometers

Energy Technology Data Exchange (ETDEWEB)

Ancsin, J. [National Research Council of Canada, Ottawa, ON (Canada). Inst. for National Measurement Standards; Mendez-Lango, E. [Centro Nacional de Metrologia (CENAM), Div. Termometria, Queretaro (Mexico)

1999-07-01

The reproducibility of some thermometric fixed points and the accuracy of four platinum resistance thermometers (PRTs) were studied. It was found that the fixed points of aluminium (Al), zinc (Zn), tin (Sn), indium (In) and gallium (Ga) were realized reproducibly within {+-}0.17 mK; {+-}0.11 mK; {+-}0.10 mK; {+-}0.13 mK and {+-}0.12 mK, respectively. Because the actual impurities and their concentration in our samples (of 99.9999 % or 99.999 99 % purity) are unknown, the systematic uncertainly due to impurities cannot be estimated. However, any of the samples of Ga, In, Sn, Zn and Al is consistent with the rest within {+-}0.2 mK, using a cubic or quadratic deviation function, in the temperature range 0 deg C to 660 deg C. This indicates that the effect of impurities is negligible. Four PRTs were selected at random. They were calibrated repeatedly, first up to the Zn point and then up to the Al point. The resistance of each PRT drifted. From time to time, for each PRT, a seemingly well-established resistance drift suddenly and unpredictably changed to a different rate of drift. Occasionally, the resistance of the PRTs shifted. Such unpredictable changes obviously limit the accuracy of temperature measurements using PRTs no matter what the accuracy of their calibrations. In the case of our four PRTs, the uncertainty of temperature measurements near 660 deg C ranged from about {+-}1 mK to about {+-}2,5 mK even though they were all calibrated at all fixed points well within {+-}0.25 mK uncertainty. Possible explanations are offered for the apparently permanent drifts and the erratic shifts in the resistance of the PRTs. Some comments are made concerning the ambiguity of 'immersion tests' in general. The furnaces of the National Research Council of Canada used in this work are high-temperature adiabatic calorimeters. (authors)

End points and assessments in esthetic dental treatment.

Science.gov (United States)

Ishida, Yuichi; Fujimoto, Keiko; Higaki, Nobuaki; Goto, Takaharu; Ichikawa, Tetsuo

2015-10-01

There are two key considerations for successful esthetic dental treatments. This article systematically describes the two key considerations: the end points of esthetic dental treatments and assessments of esthetic outcomes, which are also important for acquiring clinical skill in esthetic dental treatments. The end point and assessment of esthetic dental treatment were discussed through literature reviews and clinical practices. Before designing a treatment plan, the end point of dental treatment should be established. The section entitled "End point of esthetic dental treatment" discusses treatments for maxillary anterior teeth and the restoration of facial profile with prostheses. The process of assessing treatment outcomes entitled "Assessments of esthetic dental treatment" discusses objective and subjective evaluation methods. Practitioners should reach an agreement regarding desired end points with patients through medical interviews, and continuing improvements and developments of esthetic assessments are required to raise the therapeutic level of esthetic dental treatments. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Sampling and assessment accuracy in mate choice: a random-walk model of information processing in mating decision.

Science.gov (United States)

Castellano, Sergio; Cermelli, Paolo

2011-04-07

Mate choice depends on mating preferences and on the manner in which mate-quality information is acquired and used to make decisions. We present a model that describes how these two components of mating decision interact with each other during a comparative evaluation of prospective mates. The model, with its well-explored precedents in psychology and neurophysiology, assumes that decisions are made by the integration over time of noisy information until a stopping-rule criterion is reached. Due to this informational approach, the model builds a coherent theoretical framework for developing an integrated view of functions and mechanisms of mating decisions. From a functional point of view, the model allows us to investigate speed-accuracy tradeoffs in mating decision at both population and individual levels. It shows that, under strong time constraints, decision makers are expected to make fast and frugal decisions and to optimally trade off population-sampling accuracy (i.e. the number of sampled males) against individual-assessment accuracy (i.e. the time spent for evaluating each mate). From the proximate-mechanism point of view, the model makes testable predictions on the interactions of mating preferences and choosiness in different contexts and it might be of compelling empirical utility for a context-independent description of mating preference strength. Copyright © 2011 Elsevier Ltd. All rights reserved.

Urban Land Cover Mapping Accuracy Assessment - A Cost-benefit Analysis Approach

Science.gov (United States)

Xiao, T.

2012-12-01

One of the most important components in urban land cover mapping is mapping accuracy assessment. Many statistical models have been developed to help design simple schemes based on both accuracy and confidence levels. It is intuitive that an increased number of samples increases the accuracy as well as the cost of an assessment. Understanding cost and sampling size is crucial in implementing efficient and effective of field data collection. Few studies have included a cost calculation component as part of the assessment. In this study, a cost-benefit sampling analysis model was created by combining sample size design and sampling cost calculation. The sampling cost included transportation cost, field data collection cost, and laboratory data analysis cost. Simple Random Sampling (SRS) and Modified Systematic Sampling (MSS) methods were used to design sample locations and to extract land cover data in ArcGIS. High resolution land cover data layers of Denver, CO and Sacramento, CA, street networks, and parcel GIS data layers were used in this study to test and verify the model. The relationship between the cost and accuracy was used to determine the effectiveness of each sample method. The results of this study can be applied to other environmental studies that require spatial sampling.

Accuracy improvement techniques in Precise Point Positioning method using multiple GNSS constellations

Science.gov (United States)

Vasileios Psychas, Dimitrios; Delikaraoglou, Demitris

2016-04-01

The future Global Navigation Satellite Systems (GNSS), including modernized GPS, GLONASS, Galileo and BeiDou, offer three or more signal carriers for civilian use and much more redundant observables. The additional frequencies can significantly improve the capabilities of the traditional geodetic techniques based on GPS signals at two frequencies, especially with regard to the availability, accuracy, interoperability and integrity of high-precision GNSS applications. Furthermore, highly redundant measurements can allow for robust simultaneous estimation of static or mobile user states including more parameters such as real-time tropospheric biases and more reliable ambiguity resolution estimates. This paper presents an investigation and analysis of accuracy improvement techniques in the Precise Point Positioning (PPP) method using signals from the fully operational (GPS and GLONASS), as well as the emerging (Galileo and BeiDou) GNSS systems. The main aim was to determine the improvement in both the positioning accuracy achieved and the time convergence it takes to achieve geodetic-level (10 cm or less) accuracy. To this end, freely available observation data from the recent Multi-GNSS Experiment (MGEX) of the International GNSS Service, as well as the open source program RTKLIB were used. Following a brief background of the PPP technique and the scope of MGEX, the paper outlines the various observational scenarios that were used in order to test various data processing aspects of PPP solutions with multi-frequency, multi-constellation GNSS systems. Results from the processing of multi-GNSS observation data from selected permanent MGEX stations are presented and useful conclusions and recommendations for further research are drawn. As shown, data fusion from GPS, GLONASS, Galileo and BeiDou systems is becoming increasingly significant nowadays resulting in a position accuracy increase (mostly in the less favorable East direction) and a large reduction of convergence

Diagnostic Accuracy of the Barthel Index for Measuring Activities of Daily Living Outcome After Ischemic Hemispheric Stroke Does Early Poststroke Timing of Assessment Matter?

OpenAIRE

Kwakkel, G.; Veerbeek, J.M.; Harmeling-van der Wel, B.C.; Wegen, van, E.E.H.; Kollen, B.J.

2011-01-01

Background and Purpose- This study investigated the diagnostic accuracy of the Barthel Index (BI) in 206 stroke patients, measured within 72 hours, for activities of daily living at 6 months and determined whether the timing of BI assessment during the first days affects the accuracy of predicting activities of daily living outcome at 6 months. Methods- Receiver operating characteristic curves were constructed to determine the area under the curve and optimal cutoff points for BI at Days 2, 5...

Accuracy and reliability of peer assessment of athletic training psychomotor laboratory skills.

Science.gov (United States)

Marty, Melissa C; Henning, Jolene M; Willse, John T

2010-01-01

Peer assessment is defined as students judging the level or quality of a fellow student's understanding. No researchers have yet demonstrated the accuracy or reliability of peer assessment in athletic training education. To determine the accuracy and reliability of peer assessment of athletic training students' psychomotor skills. Cross-sectional study. Entry-level master's athletic training education program. First-year (n  =  5) and second-year (n  =  8) students. Participants evaluated 10 videos of a peer performing 3 psychomotor skills (middle deltoid manual muscle test, Faber test, and Slocum drawer test) on 2 separate occasions using a valid assessment tool. Accuracy of each peer-assessment score was examined through percentage correct scores. We used a generalizability study to determine how reliable athletic training students were in assessing a peer performing the aforementioned skills. Decision studies using generalizability theory demonstrated how the peer-assessment scores were affected by the number of participants and number of occasions. Participants had a high percentage of correct scores: 96.84% for the middle deltoid manual muscle test, 94.83% for the Faber test, and 97.13% for the Slocum drawer test. They were not able to reliably assess a peer performing any of the psychomotor skills on only 1 occasion. However, the φ increased (exceeding the 0.70 minimal standard) when 2 participants assessed the skill on 3 occasions (φ  =  0.79) for the Faber test, with 1 participant on 2 occasions (φ  =  0.76) for the Slocum drawer test, and with 3 participants on 2 occasions for the middle deltoid manual muscle test (φ  =  0.72). Although students did not detect all errors, they assessed their peers with an average of 96% accuracy. Having only 1 student assess a peer performing certain psychomotor skills was less reliable than having more than 1 student assess those skills on more than 1 occasion. Peer assessment of psychomotor skills

Diagnostic accuracy of point-of-care tests for hepatitis C virus infection: a systematic review and meta-analysis.

Directory of Open Access Journals (Sweden)

Mehnaaz Sultan Khuroo

Full Text Available Point-of-care tests provide a plausible diagnostic strategy for hepatitis C infection in economically impoverished areas. However, their utility depends upon the overall performance of individual tests.A literature search was conducted using the metasearch engine Mettā, a query interface for retrieving articles from five leading medical databases. Studies were included if they employed point-of-care tests to detect antibodies of hepatitis C virus and compared the results with reference tests. Two reviewers performed a quality assessment of the studies and extracted data for estimating test accuracy.Thirty studies that had evaluated 30 tests fulfilled the inclusion criteria. The overall pooled sensitivity, specificity, positive likelihood-ratio, negative likelihood-ratio and diagnostic odds ratio for all tests were 97.4% (95% CI: 95.9-98.4, 99.5% (99.2-99.7, 80.17 (55.35-116.14, 0.03 (0.02-0.04, and 3032.85 (1595.86-5763.78, respectively. This suggested a high pooled accuracy for all studies. We found substantial heterogeneity between studies, but none of the subgroups investigated could account for the heterogeneity. Genotype diversity of HCV had no or minimal influence on test performance. Of the seven tests evaluated in the meta-regression model, OraQuick had the highest test sensitivity and specificity and showed better performance than a third generation enzyme immunoassay in seroconversion panels. The next highest test sensitivities and specificities were from TriDot and SDBioline, followed by Genedia and Chembio. The Spot and Multiplo tests produced poor test sensitivities but high test specificities. Nine of the remaining 23 tests produced poor test sensitivities and specificities and/or showed poor performances in seroconversion panels, while 14 tests had high test performances with diagnostic odds ratios ranging from 590.70 to 28822.20.Performances varied widely among individual point-of-care tests for diagnosis of hepatitis C virus

Effect of Heart rate on Basketball Three-Point Shot Accuracy

Directory of Open Access Journals (Sweden)

Luca P. Ardigò

2018-02-01

Full Text Available The three-point shot (3S is a fundamental basketball skill used frequently during a game, and is often a main determinant of the final result. The aim of the study was to investigate the effect of different metabolic conditions, in terms of heart rates, on 3S accuracy (3S% in 24 male (Under 17 basketball players (age 16.3 ± 0.6 yrs. 3S performance was specifically investigated at different heart rates. All sessions consisted of 10 consecutive 3Ss from five different significant field spots just beyond the FIBA three-point line, i.e., about 7 m from the basket (two counter-clockwise “laps” at different heart rates: rest (0HR, after warm-up (50%HRMAX [50HR], and heart rate corresponding to 80% of its maximum value (80%HRMAX [80HR]. We found that 50HR does not significantly decrease 3S% (−15%, P = 0.255, while 80HR significantly does when compared to 0HR (−28%, P = 0.007. Given that 50HR does not decrease 3S% compared to 0HR, we believe that no preliminary warm-up is needed before entering a game in order to specifically achieve a high 3S%. Furthermore, 3S training should be performed in conditions of moderate-to-high fatigued state so that a high 3S% can be maintained during game-play.

Assessing accuracy of an electronic provincial medication repository

Directory of Open Access Journals (Sweden)

Price Morgan

2012-05-01

Full Text Available Abstract Background Jurisdictional drug information systems are being implemented in many regions around the world. British Columbia, Canada has had a provincial medication dispensing record, PharmaNet, system since 1995. Little is known about how accurately PharmaNet reflects actual medication usage. Methods This prospective, multi-centre study compared pharmacist collected Best Possible Medication Histories (BPMH to PharmaNet profiles to assess accuracy of the PharmaNet profiles for patients receiving a BPMH as part of clinical care. A review panel examined the anonymized BPMHs and discrepancies to estimate clinical significance of discrepancies. Results 16% of medication profiles were accurate, with 48% of the discrepant profiles considered potentially clinically significant by the clinical review panel. Cardiac medications tended to be more accurate (e.g. ramipril was accurate >90% of the time, while insulin, warfarin, salbutamol and pain relief medications were often inaccurate (80–85% of the time. 1215 sequential BPMHs were collected and reviewed for this study. Conclusions The PharmaNet medication repository has a low accuracy and should be used in conjunction with other sources for medication histories for clinical or research purposes. This finding is consistent with other, smaller medication repository accuracy studies in other jurisdictions. Our study highlights specific medications that tend to be lower in accuracy.

Lessons learned from accuracy assessment of IAEA-SPE-4 experiment predictions

International Nuclear Information System (INIS)

Prosek, A.

2002-01-01

The use of methods for code accuracy assessment has strongly increased in the last years. The methods suitable to provide quantitative comparison between the thermalhydraulic code predictions and experimental measurements were proposed e.g. fast Fourier transform based method (FFTBM), stochastic approximation ratio based method (SARBM) and a few methods used in the frame of the recently developed automated code assessment program (ACAP). Further, in the frame of FFTBM also a procedure to quantify the whole calculation was proposed with averaging of the results. The problem is that averaging may hide discrepancies highlighted in the qualitative analysis when only quantitative results are published. The purpose of the study was therefore to propose additional accuracy measures. New proposed measures were tested with IAEA-SPE-4 pre- and post-test predictions. The obtained results showed that the proposed measures improve the whole picture of the code accuracy. This is important when the reader is not provided with the accompanied qualitative analysis. The study shows that proposed accuracy measures efficiently increase the confidence in the quantitative results.(author)

Diagnostic Accuracy of Fall Risk Assessment Tools in People With Diabetic Peripheral Neuropathy

Science.gov (United States)

Pohl, Patricia S.; Mahnken, Jonathan D.; Kluding, Patricia M.

2012-01-01

Background Diabetic peripheral neuropathy affects nearly half of individuals with diabetes and leads to increased fall risk. Evidence addressing fall risk assessment for these individuals is lacking. Objective The purpose of this study was to identify which of 4 functional mobility fall risk assessment tools best discriminates, in people with diabetic peripheral neuropathy, between recurrent “fallers” and those who are not recurrent fallers. Design A cross-sectional study was conducted. Setting The study was conducted in a medical research university setting. Participants The participants were a convenience sample of 36 individuals between 40 and 65 years of age with diabetic peripheral neuropathy. Measurements Fall history was assessed retrospectively and was the criterion standard. Fall risk was assessed using the Functional Reach Test, the Timed “Up & Go” Test, the Berg Balance Scale, and the Dynamic Gait Index. Sensitivity, specificity, positive and negative likelihood ratios, and overall diagnostic accuracy were calculated for each fall risk assessment tool. Receiver operating characteristic curves were used to estimate modified cutoff scores for each fall risk assessment tool; indexes then were recalculated. Results Ten of the 36 participants were classified as recurrent fallers. When traditional cutoff scores were used, the Dynamic Gait Index and Functional Reach Test demonstrated the highest sensitivity at only 30%; the Dynamic Gait Index also demonstrated the highest overall diagnostic accuracy. When modified cutoff scores were used, all tools demonstrated improved sensitivity (80% or 90%). Overall diagnostic accuracy improved for all tests except the Functional Reach Test; the Timed “Up & Go” Test demonstrated the highest diagnostic accuracy at 88.9%. Limitations The small sample size and retrospective fall history assessment were limitations of the study. Conclusions Modified cutoff scores improved diagnostic accuracy for 3 of 4 fall risk

Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

International Nuclear Information System (INIS)

Saghafi, Mahdi; Ghofrani, Mohammad Bagher; D’Auria, Francesco

2016-01-01

Highlights: • FFTBM-SM is an improved Fast Fourier Transform Base Method by signal mirroring. • FFTBM-SM has been applied to accuracy assessment of MELCOR code predictions. • The case studied was Station Black-Out accident in PSB-VVER integral test facility. • FFTBM-SM eliminates fluctuations of accuracy indices when signals sharply change. • Accuracy assessment is performed in a more realistic and consistent way by FFTBM-SM. - Abstract: This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the investigated signals sharply increase or decrease. In the current study, accuracy of MELCOR code is quantified using FFTBM-SM in a series of increasing time-intervals, and the results are compared to those with original FFTBM. Also, differences between the accuracy indices of original FFTBM and FFTBM-SM are investigated and correction factors calculated to eliminate unphysical effects in original FFTBM. The main findings are: (1) replacing limited number of phenomena-based time-intervals by a series of increasing time-intervals provides deeper insights about accuracy variation of the MELCOR calculations, and (2) application of FFTBM-SM for accuracy evaluation of the MELCOR predictions, provides more reliable results than original FFTBM by eliminating the fluctuations of accuracy indices when experimental signals sharply increase or

Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

Energy Technology Data Exchange (ETDEWEB)

Saghafi, Mahdi [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Ghofrani, Mohammad Bagher, E-mail: ghofrani@sharif.edu [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); D’Auria, Francesco [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, San Piero a Grado, Pisa (Italy)

2016-11-15

Highlights: • FFTBM-SM is an improved Fast Fourier Transform Base Method by signal mirroring. • FFTBM-SM has been applied to accuracy assessment of MELCOR code predictions. • The case studied was Station Black-Out accident in PSB-VVER integral test facility. • FFTBM-SM eliminates fluctuations of accuracy indices when signals sharply change. • Accuracy assessment is performed in a more realistic and consistent way by FFTBM-SM. - Abstract: This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the investigated signals sharply increase or decrease. In the current study, accuracy of MELCOR code is quantified using FFTBM-SM in a series of increasing time-intervals, and the results are compared to those with original FFTBM. Also, differences between the accuracy indices of original FFTBM and FFTBM-SM are investigated and correction factors calculated to eliminate unphysical effects in original FFTBM. The main findings are: (1) replacing limited number of phenomena-based time-intervals by a series of increasing time-intervals provides deeper insights about accuracy variation of the MELCOR calculations, and (2) application of FFTBM-SM for accuracy evaluation of the MELCOR predictions, provides more reliable results than original FFTBM by eliminating the fluctuations of accuracy indices when experimental signals sharply increase or

PUSHBROOM HYPERSPECTRAL IMAGING FROM AN UNMANNED AIRCRAFT SYSTEM (UAS) – GEOMETRIC PROCESSINGWORKFLOW AND ACCURACY ASSESSMENT

KAUST Repository

Turner, D.

2017-08-31

In this study, we assess two push broom hyperspectral sensors as carried by small (10-15 kg) multi-rotor Unmanned Aircraft Systems (UAS). We used a Headwall Photonics micro-Hyperspec push broom sensor with 324 spectral bands (4-5 nm FWHM) and a Headwall Photonics nano-Hyperspec sensor with 270 spectral bands (6 nm FWHM) both in the VNIR spectral range (400-1000 nm). A gimbal was used to stabilise the sensors in relation to the aircraft flight dynamics, and for the micro-Hyperspec a tightly coupled dual frequency Global Navigation Satellite System (GNSS) receiver, an Inertial Measurement Unit (IMU), and Machine Vision Camera (MVC) were used for attitude and position determination. For the nano-Hyperspec, a navigation grade GNSS system and IMU provided position and attitude data. This study presents the geometric results of one flight over a grass oval on which a dense Ground Control Point (GCP) network was deployed. The aim being to ascertain the geometric accuracy achievable with the system. Using the PARGE software package (ReSe - Remote Sensing Applications) we ortho-rectify the push broom hyperspectral image strips and then quantify the accuracy of the ortho-rectification by using the GCPs as check points. The orientation (roll, pitch, and yaw) of the sensor is measured by the IMU. Alternatively imagery from a MVC running at 15 Hz, with accurate camera position data can be processed with Structure from Motion (SfM) software to obtain an estimated camera orientation. In this study, we look at which of these data sources will yield a flight strip with the highest geometric accuracy.

Accuracy of the Approximation Function Deduced from the Fixed 3-Points Calibration Delivered with the Cernox™ Sensor

CERN Document Server

Balle, C; Fortescue-Beck, E; Vauthier, N

2013-01-01

The cernox™ sensor is delivered with a 3-point resistance versus temperature cal-ibration that permits the construction of an individual interpolation table by using the data in the CERN thermometer database. For instance at the 4.2 K point, the individual calibration and the manufacturer data are within +/-0.1 K for 99.39% of a sample population of about 5700 sensors. Preliminary results also indicate that accuracies of 0.1 K and 1 K can be obtained below respectively 5 K and 77 K.

A Framework for the Objective Assessment of Registration Accuracy

Directory of Open Access Journals (Sweden)

Francesca Pizzorni Ferrarese

2014-01-01

Full Text Available Validation and accuracy assessment are the main bottlenecks preventing the adoption of image processing algorithms in the clinical practice. In the classical approach, a posteriori analysis is performed through objective metrics. In this work, a different approach based on Petri nets is proposed. The basic idea consists in predicting the accuracy of a given pipeline based on the identification and characterization of the sources of inaccuracy. The concept is demonstrated on a case study: intrasubject rigid and affine registration of magnetic resonance images. Both synthetic and real data are considered. While synthetic data allow the benchmarking of the performance with respect to the ground truth, real data enable to assess the robustness of the methodology in real contexts as well as to determine the suitability of the use of synthetic data in the training phase. Results revealed a higher correlation and a lower dispersion among the metrics for simulated data, while the opposite trend was observed for pathologic ones. Results show that the proposed model not only provides a good prediction performance but also leads to the optimization of the end-to-end chain in terms of accuracy and robustness, setting the ground for its generalization to different and more complex scenarios.

Accuracy and Reliability of Peer Assessment of Athletic Training Psychomotor Laboratory Skills

Science.gov (United States)

Marty, Melissa C.; Henning, Jolene M.; Willse, John T.

2010-01-01

Abstract Context: Peer assessment is defined as students judging the level or quality of a fellow student's understanding. No researchers have yet demonstrated the accuracy or reliability of peer assessment in athletic training education. Objective: To determine the accuracy and reliability of peer assessment of athletic training students' psychomotor skills. Design: Cross-sectional study. Setting: Entry-level master's athletic training education program. Patients or Other Participants: First-year (n  =  5) and second-year (n  =  8) students. Main Outcome Measure(s): Participants evaluated 10 videos of a peer performing 3 psychomotor skills (middle deltoid manual muscle test, Faber test, and Slocum drawer test) on 2 separate occasions using a valid assessment tool. Accuracy of each peer-assessment score was examined through percentage correct scores. We used a generalizability study to determine how reliable athletic training students were in assessing a peer performing the aforementioned skills. Decision studies using generalizability theory demonstrated how the peer-assessment scores were affected by the number of participants and number of occasions. Results: Participants had a high percentage of correct scores: 96.84% for the middle deltoid manual muscle test, 94.83% for the Faber test, and 97.13% for the Slocum drawer test. They were not able to reliably assess a peer performing any of the psychomotor skills on only 1 occasion. However, the ϕ increased (exceeding the 0.70 minimal standard) when 2 participants assessed the skill on 3 occasions (ϕ  =  0.79) for the Faber test, with 1 participant on 2 occasions (ϕ  =  0.76) for the Slocum drawer test, and with 3 participants on 2 occasions for the middle deltoid manual muscle test (ϕ  =  0.72). Conclusions: Although students did not detect all errors, they assessed their peers with an average of 96% accuracy. Having only 1 student assess a peer performing certain psychomotor skills was

Testing of the McMath-Pierce 0.8-Meter East Auxiliary Telescope's Acquisition and Slewing Accuracy

Science.gov (United States)

Harshaw, Richard; Ray, Jimmy; Prause, Lori; Douglass, David; Branston, Detrick; Genet, Russell M.

2015-09-01

Following mediocre results with pointing tests of the McMath-Pierce 0.8-meter East Auxiliary Telescope in April 2014, a team of astronomers/engineers met again in May 2014 to test other pointing models and assess the telescope's ability to point with enough accuracy to permit the efficient use of speckle interferometry. Results show that accurate collimation is a pre-requisite for such accuracy. Once attained, the telescope performs extremely well.

Feature relevance assessment for the semantic interpretation of 3D point cloud data

Directory of Open Access Journals (Sweden)

M. Weinmann

2013-10-01

Full Text Available The automatic analysis of large 3D point clouds represents a crucial task in photogrammetry, remote sensing and computer vision. In this paper, we propose a new methodology for the semantic interpretation of such point clouds which involves feature relevance assessment in order to reduce both processing time and memory consumption. Given a standard benchmark dataset with 1.3 million 3D points, we first extract a set of 21 geometric 3D and 2D features. Subsequently, we apply a classifier-independent ranking procedure which involves a general relevance metric in order to derive compact and robust subsets of versatile features which are generally applicable for a large variety of subsequent tasks. This metric is based on 7 different feature selection strategies and thus addresses different intrinsic properties of the given data. For the example of semantically interpreting 3D point cloud data, we demonstrate the great potential of smaller subsets consisting of only the most relevant features with 4 different state-of-the-art classifiers. The results reveal that, instead of including as many features as possible in order to compensate for lack of knowledge, a crucial task such as scene interpretation can be carried out with only few versatile features and even improved accuracy.

Data accuracy assessment using enterprise architecture

Science.gov (United States)

Närman, Per; Holm, Hannes; Johnson, Pontus; König, Johan; Chenine, Moustafa; Ekstedt, Mathias

2011-02-01

Errors in business processes result in poor data accuracy. This article proposes an architecture analysis method which utilises ArchiMate and the Probabilistic Relational Model formalism to model and analyse data accuracy. Since the resources available for architecture analysis are usually quite scarce, the method advocates interviews as the primary data collection technique. A case study demonstrates that the method yields correct data accuracy estimates and is more resource-efficient than a competing sampling-based data accuracy estimation method.

Accuracy of micro four-point probe measurements on inhomogeneous samples: A probe spacing dependence study

DEFF Research Database (Denmark)

Wang, Fei; Petersen, Dirch Hjorth; Østerberg, Frederik Westergaard

2009-01-01

In this paper, we discuss a probe spacing dependence study in order to estimate the accuracy of micro four-point probe measurements on inhomogeneous samples. Based on sensitivity calculations, both sheet resistance and Hall effect measurements are studied for samples (e.g. laser annealed samples...... the probe spacing is smaller than 1/40 of the variation wavelength, micro four-point probes can provide an accurate record of local properties with less than 1% measurement error. All the calculations agree well with previous experimental results.......) with periodic variations of sheet resistance, sheet carrier density, and carrier mobility. With a variation wavelength of ¿, probe spacings from 0.0012 to 1002 have been applied to characterize the local variations. The calculations show that the measurement error is highly dependent on the probe spacing. When...

Venous, Arterialized-Venous, or Capillary Glucose Reference Measurements for the Accuracy Assessment of a Continuous Glucose Monitoring System.

Science.gov (United States)

Kropff, Jort; van Steen, Sigrid C; deGraaff, Peter; Chan, Man W; van Amstel, Rombout B E; DeVries, J Hans

2017-11-01

Different reference methods are used for the accuracy assessment of continuous glucose monitoring (CGM) systems. The effect of using venous, arterialized-venous, or capillary reference measurements on CGM accuracy is unclear. We evaluated 21 individuals with type 1 diabetes using a capillary calibrated CGM system. Venous or arterialized-venous reference glucose samples were taken every 15 min at two separate visits and assessed per YSI 2300 STAT Plus. Arterialization was achieved by heated-hand technique. Capillary samples were collected hourly during the venous reference visit. The investigation sequence (venous or arterialized-venous) was randomized. Effectiveness of arterialization was measured by comparing free venous oxygen pressure (PO2) of both visit days. Primary endpoint was the median absolute relative difference (ARD). Median ARD using arterialized-venous reference samples was not different from venous samples (point estimated difference 0.52%, P = 0.181). When comparing the three reference methods, median ARD was also not different over the full glycemic range (venous 9.0% [n = 681], arterialized-venous 8.3% [n = 684], and capillary 8.1% [n = 205], P = 0.216), nor over the separate glucose ranges. Arterialization was successful (PO2 venous 5.4 kPa vs. arterialized-venous 8.9 kPa, P reference measurements did not significantly impact CGM accuracy. Venous reference seems preferable due to its ease of operation.

Assessment of an extended Nijboer-Zernike approach for the computation of optical point-spread functions.

Science.gov (United States)

Braat, Joseph; Dirksen, Peter; Janssen, Augustus J E M

2002-05-01

We assess the validity of an extended Nijboer-Zernike approach [J. Opt. Soc. Am. A 19, 849 (2002)], based on ecently found Bessel-series representations of diffraction integrals comprising an arbitrary aberration and a defocus part, for the computation of optical point-spread functions of circular, aberrated optical systems. These new series representations yield a flexible means to compute optical point-spread functions, both accurately and efficiently, under defocus and aberration conditions that seem to cover almost all cases of practical interest. Because of the analytical nature of the formulas, there are no discretization effects limiting the accuracy, as opposed to the more commonly used numerical packages based on strictly numerical integration methods. Instead, we have an easily managed criterion, expressed in the number of terms to be included in the Bessel-series representations, guaranteeing the desired accuracy. For this reason, the analytical method can also serve as a calibration tool for the numerically based methods. The analysis is not limited to pointlike objects but can also be used for extended objects under various illumination conditions. The calculation schemes are simple and permit one to trace the relative strength of the various interfering complex-amplitude terms that contribute to the final image intensity function.

Factors influencing medical students' self-assessment of examination performance accuracy: A United Arab Emirates study.

Science.gov (United States)

Shaban, Sami; Aburawi, Elhadi H; Elzubeir, Khalifa; Elango, Sambandam; El-Zubeir, Margaret

2016-01-01

Assessment of one's academic capabilities is essential to being an effective, self-directed, life-long learner. The primary objective of this study was to analyze self-assessment accuracy of medical students attending the College of Medicine and Health Sciences, United Arab Emirates University, by examining their ability to assess their own performance on an MCQ examination. 1 st and 2 nd year medical students (n = 235) self-assessed pre and post-examination performance were compared with objectively measured scores (actual examination performance). Associations between accuracy of score prediction (pre and post assessment), and students' gender, year of education, perceived preparation, confidence and anxiety were also determined. Expected mark correlated significantly with objectively assessed marks (r = 0.407; P self-assessment accuracy. Findings reinforce existing evidence indicating that medical students are poor self-assessors. There are potentially multiple explanations for misjudgment of this multidimensional construct that require further investigation and change in learning cultures. The study offers clear targets for change aimed at optimizing self-assessment capabilities.

Accuracy Assessment Measures for Image Segmentation Goodness of the Land Parcel Identification System

DEFF Research Database (Denmark)

Montaghi, Alessandro; Larsen, Rene; Greve, Mogens Humlekrog

2013-01-01

, was employed in order to assess the quality of segmentation. An accuracy assessment was performed using seven metrics based on the topological or geometric similarity between segmented polygons and reference polygons, which were derived through manual delineation. The results indicate that (1) segmentation...... accuracy is influenced by the size of the reference polygons and (2) the presence of clear boundaries (e.g. hedgerow, ponds, ditches and road) drives the segmentation algorithm when the scale parameter exceeds a certain value....

ASSESSMENT OF SURFACE FINISH AND DIMENSIONAL ACCURACY OF TOOLS MANUFACTURED BY METAL CASTING IN RAPID PROTOTYPING SAND MOULDS

Directory of Open Access Journals (Sweden)

Nyembwe, K.

2012-11-01

Full Text Available In this paper, an initial assessment of the quality parameters of the surface finish and dimensional accuracy of tools made by metal casting in rapid prototyping (RP sand moulds is undertaken. A case study from a local tool room, dealing with the manufacturing of an aluminium die for the lost wax process, is employed. Modern techniques, including surface roughness analysis and three dimensional scanning, are used to determine and understand how each manufacturing step influences the final quality of the cast tool. The best surface finish obtained for the cast die had arithmetic average roughness (Ra and mean average roughness (Rz respectively equal to 3.23m and 11.38m. In terms of dimensional accuracy, 82% of cast-die points coincided with the Computer Aided Design (CAD data, which is within the typical tolerances of sand cast products. The investigation shows that mould coating contributes slightly to the improvement of the cast tool surface finish. The study also found that the additive manufacturing of the sand mould was the chief factor responsible for the loss of dimensional accuracy. These findings indicate that machining will always be required to improve the surface finish and the dimensional accuracy of cast tools in RP sand moulds.

The Value of Clinical Needs Assessments for Point-of-Care Diagnostics.

Science.gov (United States)

Weigl, Bernhard H; Gaydos, Charlotte A; Kost, Gerald; Beyette, Fred R; Sabourin, Stephanie; Rompalo, Anne; de Los Santos, Tala; McMullan, Jason T; Haller, John

2012-06-01

Most entrepreneurial ventures fail long before the core technology can be brought to the marketplace because of disconnects in performance and usability measures such as accuracy, cost, complexity, assay stability, and time requirements between technology developers' specifications and needs of the end-users. By going through a clinical needs assessment (CNA) process, developers will gain vital information and a clear focus that will help minimize the risks associated with the development of new technologies available for use within the health care system. This article summarizes best practices of the principal investigators of the National Institute of Biomedical Imaging and Bioengineering point-of-care (POC) centers within the National Institute of Biomedical Imaging and Bioengineering POC Technologies Research Network. Clinical needs assessments are particularly important for product development areas that do not sufficiently benefit from traditional market research, such as grant-funded research and development, new product lines using cutting-edge technologies developed in start-up companies, and products developed through product development partnerships for low-resource settings. The objectives of this article were to (1) highlight the importance of CNAs for development of POC devices, (2) discuss methods applied by POC Technologies Research Network for assessing clinical needs, and (3) provide a road map for future CNAs.

The Value of Clinical Needs Assessments for Point-of-Care Diagnostics

Science.gov (United States)

Weigl, Bernhard H.; Gaydos, Charlotte A.; Kost, Gerald; Beyette, Fred R.; Sabourin, Stephanie; Rompalo, Anne; de los Santos, Tala; McMullan, Jason T.; Haller, John

2013-01-01

Most entrepreneurial ventures fail long before the core technology can be brought to the marketplace because of disconnects in performance and usability measures such as accuracy, cost, complexity, assay stability, and time requirements between technology developers’ specifications and needs of the end-users. By going through a clinical needs assessment (CNA) process, developers will gain vital information and a clear focus that will help minimize the risks associated with the development of new technologies available for use within the health care system. This article summarizes best practices of the principal investigators of the National Institute of Biomedical Imaging and Bioengineering point-of-care (POC) centers within the National Institute of Biomedical Imaging and Bioengineering POC Technologies Research Network. Clinical needs assessments are particularly important for product development areas that do not sufficiently benefit from traditional market research, such as grant-funded research and development, new product lines using cutting-edge technologies developed in start-up companies, and products developed through product development partnerships for low-resource settings. The objectives of this article were to (1) highlight the importance of CNAs for development of POC devices, (2) discuss methods applied by POC Technologies Research Network for assessing clinical needs, and (3) provide a road map for future CNAs. PMID:23935405

An accuracy assessment of realtime GNSS time series toward semi- real time seafloor geodetic observation

Science.gov (United States)

Osada, Y.; Ohta, Y.; Demachi, T.; Kido, M.; Fujimoto, H.; Azuma, R.; Hino, R.

2013-12-01

Large interplate earthquake repeatedly occurred in Japan Trench. Recently, the detail crustal deformation revealed by the nation-wide inland GPS network called as GEONET by GSI. However, the maximum displacement region for interplate earthquake is mainly located offshore region. GPS/Acoustic seafloor geodetic observation (hereafter GPS/A) is quite important and useful for understanding of shallower part of the interplate coupling between subducting and overriding plates. We typically conduct GPS/A in specific ocean area based on repeated campaign style using research vessel or buoy. Therefore, we cannot monitor the temporal variation of seafloor crustal deformation in real time. The one of technical issue on real time observation is kinematic GPS analysis because kinematic GPS analysis based on reference and rover data. If the precise kinematic GPS analysis will be possible in the offshore region, it should be promising method for real time GPS/A with USV (Unmanned Surface Vehicle) and a moored buoy. We assessed stability, precision and accuracy of StarFireTM global satellites based augmentation system. We primarily tested for StarFire in the static condition. In order to assess coordinate precision and accuracy, we compared 1Hz StarFire time series and post-processed precise point positioning (PPP) 1Hz time series by GIPSY-OASIS II processing software Ver. 6.1.2 with three difference product types (ultra-rapid, rapid, and final orbits). We also used difference interval clock information (30 and 300 seconds) for the post-processed PPP processing. The standard deviation of real time StarFire time series is less than 30 mm (horizontal components) and 60 mm (vertical component) based on 1 month continuous processing. We also assessed noise spectrum of the estimated time series by StarFire and post-processed GIPSY PPP results. We found that the noise spectrum of StarFire time series is similar pattern with GIPSY-OASIS II processing result based on JPL rapid orbit

Effects of point configuration on the accuracy in 3D reconstruction from biplane images

International Nuclear Information System (INIS)

Dmochowski, Jacek; Hoffmann, Kenneth R.; Singh, Vikas; Xu Jinhui; Nazareth, Daryl P.

2005-01-01

Two or more angiograms are being used frequently in medical imaging to reconstruct locations in three-dimensional (3D) space, e.g., for reconstruction of 3D vascular trees, implanted electrodes, or patient positioning. A number of techniques have been proposed for this task. In this simulation study, we investigate the effect of the shape of the configuration of the points in 3D (the 'cloud' of points) on reconstruction errors for one of these techniques developed in our laboratory. Five types of configurations (a ball, an elongated ellipsoid (cigar), flattened ball (pancake), flattened cigar, and a flattened ball with a single distant point) are used in the evaluations. For each shape, 100 random configurations were generated, with point coordinates chosen from Gaussian distributions having a covariance matrix corresponding to the desired shape. The 3D data were projected into the image planes using a known imaging geometry. Gaussian distributed errors were introduced in the x and y coordinates of these projected points. Gaussian distributed errors were also introduced into the gantry information used to calculate the initial imaging geometry. The imaging geometries and 3D positions were iteratively refined using the enhanced-Metz-Fencil technique. The image data were also used to evaluate the feasible R-t solution volume. The 3D errors between the calculated and true positions were determined. The effects of the shape of the configuration, the number of points, the initial geometry error, and the input image error were evaluated. The results for the number of points, initial geometry error, and image error are in agreement with previously reported results, i.e., increasing the number of points and reducing initial geometry and/or image error, improves the accuracy of the reconstructed data. The shape of the 3D configuration of points also affects the error of reconstructed 3D configuration; specifically, errors decrease as the 'volume' of the 3D configuration

Diagnostic accuracy of surgeons and trainees in assessment of patients with acute abdominal pain.

Science.gov (United States)

2016-09-01

Diagnostic accuracy in the assessment of patients with acute abdominal pain in the emergency ward is not adequate. It has been argued that this is because the investigations are carried out predominantly by a trainee. Resource utilization could be lowered if surgeons had a higher initial diagnostic accuracy. Patients with acute abdominal pain were included in a prospective cohort study. A surgical trainee and a surgeon made independent assessments in the emergency department, recording the clinical diagnosis and proposed diagnostic investigations. A reference standard diagnosis was established by an expert panel, and the proportion of correct diagnoses was calculated. Diagnostic accuracy was expressed in terms of sensitivity, specificity, positive predictive value and negative predictive value. Interobserver agreement for the diagnosis and elements of history-taking and physical examination were expressed by means of Cohen's κ. Certainty of diagnosis was recorded using a visual analogue scale. A trainee and a surgeon independently assessed 126 patients. Trainees made a correct diagnosis in 44·4 per cent of patients and surgeons in 42·9 per cent (P = 0·839). Surgeons, however, recorded a higher level of diagnostic certainty. Diagnostic accuracy was comparable in distinguishing urgent from non-urgent diagnoses, and for the most common diseases. Interobserver agreement for the clinical diagnosis varied from fair to moderate (κ = 0·28-0·57). The diagnostic accuracy of the initial clinical assessment is not improved when a surgeon rather than a surgical trainee assesses a patient with abdominal pain in the emergency department. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

Estimating the Accuracy of the Chedoke-McMaster Stroke Assessment Predictive Equations for Stroke Rehabilitation.

Science.gov (United States)

Dang, Mia; Ramsaran, Kalinda D; Street, Melissa E; Syed, S Noreen; Barclay-Goddard, Ruth; Stratford, Paul W; Miller, Patricia A

2011-01-01

To estimate the predictive accuracy and clinical usefulness of the Chedoke-McMaster Stroke Assessment (CMSA) predictive equations. A longitudinal prognostic study using historical data obtained from 104 patients admitted post cerebrovascular accident was undertaken. Data were abstracted for all patients undergoing rehabilitation post stroke who also had documented admission and discharge CMSA scores. Published predictive equations were used to determine predicted outcomes. To determine the accuracy and clinical usefulness of the predictive model, shrinkage coefficients and predictions with 95% confidence bands were calculated. Complete data were available for 74 patients with a mean age of 65.3±12.4 years. The shrinkage values for the six Impairment Inventory (II) dimensions varied from -0.05 to 0.09; the shrinkage value for the Activity Inventory (AI) was 0.21. The error associated with predictive values was greater than ±1.5 stages for the II dimensions and greater than ±24 points for the AI. This study shows that the large error associated with the predictions (as defined by the confidence band) for the CMSA II and AI limits their clinical usefulness as a predictive measure. Further research to establish predictive models using alternative statistical procedures is warranted.

ACCURACY ASSESSMENT OF GO PRO HERO 3 (BLACK CAMERA IN UNDERWATER ENVIRONMENT

Directory of Open Access Journals (Sweden)

P. Helmholz,

2016-06-01

Full Text Available Modern digital cameras are increasing in quality whilst decreasing in size. In the last decade, a number of waterproof consumer digital cameras (action cameras have become available, which often cost less than $500. A possible application of such action cameras is in the field of Underwater Photogrammetry. Especially with respect to the fact that with the change of the medium to below water can in turn counteract the distortions present. The goal of this paper is to investigate the suitability of such action cameras for underwater photogrammetric applications focusing on the stability of the camera and the accuracy of the derived coordinates for possible photogrammetric applications. For this paper a series of image sequences was capture in a water tank. A calibration frame was placed in the water tank allowing the calibration of the camera and the validation of the measurements using check points. The accuracy assessment covered three test sets operating three GoPro sports cameras of the same model (Hero 3 black. The test set included the handling of the camera in a controlled manner where the camera was only dunked into the water tank using 7MP and 12MP resolution and a rough handling where the camera was shaken as well as being removed from the waterproof case using 12MP resolution. The tests showed that the camera stability was given with a maximum standard deviation of the camera constant σc of 0.0031mm for 7MB (for an average c of 2.720mm and 0.0072 mm for 12MB (for an average c of 3.642mm. The residual test of the check points gave for the 7MB test series the largest rms value with only 0.450mm and the largest maximal residual of only 2.5 mm. For the 12MB test series the maximum rms value is 0. 653mm.

Accuracy Assessment of GO Pro Hero 3 (black) Camera in Underwater Environment

Science.gov (United States)

Helmholz, , P.; Long, J.; Munsie, T.; Belton, D.

2016-06-01

Modern digital cameras are increasing in quality whilst decreasing in size. In the last decade, a number of waterproof consumer digital cameras (action cameras) have become available, which often cost less than 500. A possible application of such action cameras is in the field of Underwater Photogrammetry. Especially with respect to the fact that with the change of the medium to below water can in turn counteract the distortions present. The goal of this paper is to investigate the suitability of such action cameras for underwater photogrammetric applications focusing on the stability of the camera and the accuracy of the derived coordinates for possible photogrammetric applications. For this paper a series of image sequences was capture in a water tank. A calibration frame was placed in the water tank allowing the calibration of the camera and the validation of the measurements using check points. The accuracy assessment covered three test sets operating three GoPro sports cameras of the same model (Hero 3 black). The test set included the handling of the camera in a controlled manner where the camera was only dunked into the water tank using 7MP and 12MP resolution and a rough handling where the camera was shaken as well as being removed from the waterproof case using 12MP resolution. The tests showed that the camera stability was given with a maximum standard deviation of the camera constant σc of 0.0031mm for 7MB (for an average c of 2.720mm) and 0.0072 mm for 12MB (for an average c of 3.642mm). The residual test of the check points gave for the 7MB test series the largest rms value with only 0.450mm and the largest maximal residual of only 2.5 mm. For the 12MB test series the maximum rms value is 0. 653mm.

The Accuracy and Prognostic Value of Point-of-care Ultrasound for Nephrolithiasis in the Emergency Department: A Systematic Review and Meta-analysis.

Science.gov (United States)

Wong, Charles; Teitge, Braden; Ross, Marshall; Young, Paul; Robertson, Helen Lee; Lang, Eddy

2018-02-10

Point-of-care ultrasound (POCUS) has been suggested as an initial investigation in the management of renal colic. Our objectives were: 1) to determine the accuracy of POCUS for the diagnosis of nephrolithiasis and 2) to assess its prognostic value in the management of renal colic. The review protocol was registered to the PROSPERO database (CRD42016035331). An electronic database search of MEDLINE, Embase, and PubMed was conducted utilizing subject headings, keywords, and synonyms that address our research question. Bibliographies of included studies and narrative reviews were manually examined. Studies of adult emergency department patients with renal colic symptoms were included. Any degree of hydronephrosis was considered a positive POCUS finding. Accepted criterion standards were computed tomography evidence of renal stone or hydronephrosis, direct stone visualization, or surgical findings. Screening of abstracts, quality assessment with the QUADAS-2 instrument, and data extraction were performed by two reviewers, with discrepancies resolved by consensus with a third reviewer. Test performance was assessed by pooled sensitivity and specificity, calculated likelihood ratios, and a summary receiver operator curve (SROC). The secondary objective of prognostic value was reported as a narrative summary. The electronic search yielded 627 unique titles. After relevance screening, 26 papers underwent full-text review, and nine articles met all inclusion criteria. Of these, five high-quality studies (N = 1,773) were included in the meta-analysis for diagnostic accuracy and the remaining yielded data on prognostic value. The pooled results for sensitivity and specificity were 70.2% (95% confidence interval [CI] = 67.1%-73.2%) and 75.4% (95% CI = 72.5%-78.2%), respectively. The calculated positive and negative likelihood ratios were 2.85 and 0.39. The SROC generated did not show evidence of a threshold effect. Two of the studies in the meta-analysis found that the

Assessing the consistency of UAV-derived point clouds and images acquired at different altitudes

Science.gov (United States)

Ozcan, O.

2016-12-01

Unmanned Aerial Vehicles (UAVs) offer several advantages in terms of cost and image resolution compared to terrestrial photogrammetry and satellite remote sensing system. Nowadays, UAVs that bridge the gap between the satellite scale and field scale applications were initiated to be used in various application areas to acquire hyperspatial and high temporal resolution imageries due to working capacity and acquiring in a short span of time with regard to conventional photogrammetry methods. UAVs have been used for various fields such as for the creation of 3-D earth models, production of high resolution orthophotos, network planning, field monitoring and agricultural lands as well. Thus, geometric accuracy of orthophotos and volumetric accuracy of point clouds are of capital importance for land surveying applications. Correspondingly, Structure from Motion (SfM) photogrammetry, which is frequently used in conjunction with UAV, recently appeared in environmental sciences as an impressive tool allowing for the creation of 3-D models from unstructured imagery. In this study, it was aimed to reveal the spatial accuracy of the images acquired from integrated digital camera and the volumetric accuracy of Digital Surface Models (DSMs) which were derived from UAV flight plans at different altitudes using SfM methodology. Low-altitude multispectral overlapping aerial photography was collected at the altitudes of 30 to 100 meters and georeferenced with RTK-GPS ground control points. These altitudes allow hyperspatial imagery with the resolutions of 1-5 cm depending upon the sensor being used. Preliminary results revealed that the vertical comparison of UAV-derived point clouds with respect to GPS measurements pointed out an average distance at cm-level. Larger values are found in areas where instantaneous changes in surface are present.

The design of visible system for improving the measurement accuracy of imaging points

Science.gov (United States)

Shan, Qiu-sha; Li, Gang; Zeng, Luan; Liu, Kai; Yan, Pei-pei; Duan, Jing; Jiang, Kai

2018-02-01

It has a widely applications in robot vision and 3D measurement for binocular stereoscopic measurement technology. And the measure precision is an very important factor, especially in 3D coordination measurement, high measurement accuracy is more stringent to the distortion of the optical system. In order to improving the measurement accuracy of imaging points, to reducing the distortion of the imaging points, the optical system must be satisfied the requirement of extra low distortion value less than 0.1#65285;, a transmission visible optical lens was design, which has characteristic of telecentric beam path in image space, adopted the imaging model of binocular stereo vision, and imaged the drone at the finity distance. The optical system was adopted complex double Gauss structure, and put the pupil stop on the focal plane of the latter groups, maked the system exit pupil on the infinity distance, and realized telecentric beam path in image space. The system mainly optical parameter as follows: the system spectrum rangement is visible light wave band, the optical effective length is f '=30mm, the relative aperture is 1/3, and the fields of view is 21°. The final design results show that the RMS value of the spread spots of the optical lens in the maximum fields of view is 2.3μm, which is less than one pixel(3.45μm) the distortion value is less than 0.1%, the system has the advantage of extra low distortion value and avoids the latter image distortion correction; the proposed modulation transfer function of the optical lens is 0.58(@145 lp/mm), the imaging quality of the system is closed to the diffraction limited; the system has simply structure, and can satisfies the requirements of the optical indexes. Ultimately, based on the imaging model of binocular stereo vision was achieved to measuring the drone at the finity distance.

Teacher Compliance and Accuracy in State Assessment of Student Motor Skill Performance

Science.gov (United States)

Hall, Tina J.; Hicklin, Lori K.; French, Karen E.

2015-01-01

Purpose: The purpose of this study was to investigate teacher compliance with state mandated assessment protocols and teacher accuracy in assessing student motor skill performance. Method: Middle school teachers (N = 116) submitted eighth grade student motor skill performance data from 318 physical education classes to a trained monitoring…

Accuracy of endoscopic intraoperative assessment of urologic stone size.

Science.gov (United States)

Patel, Nishant; Chew, Ben; Knudsen, Bodo; Lipkin, Michael; Wenzler, David; Sur, Roger L

2014-05-01

Endoscopic treatment of renal calculi relies on surgeon assessment of residual stone fragment size for either basket removal or for the passage of fragments postoperatively. We therefore sought to determine the accuracy of endoscopic assessment of renal calculi size. Between January and May 2013, five board-certified endourologists participated in an ex vivo artificial endoscopic simulation. A total of 10 stones (pebbles) were measured (mm) by nonparticipating urologist (N.D.P.) with electronic calibers and placed into separate labeled opaque test tubes to prevent visualization of the stones through the side of the tube. Endourologists were blinded to the actual size of the stones. A flexible digital ureteroscope with a 200-μm core sized laser fiber in the working channel as a size reference was placed through the ureteroscope into the test tube to estimate the stone size (mm). Accuracy was determined by obtaining the correlation coefficient (r) and constructing an Altman-Bland plot. Endourologists tended to overestimate actual stone size by a margin of 0.05 mm. The Pearson correlation coefficient was r=0.924, with a p-valuestones (stones (≥4 mm), r=0.911 vs r=0.666. Altman-bland plot analysis suggests that surgeons are able to accurately estimate stone size within a range of -1.8 to +1.9 mm. This ex vivo simulation study demonstrates that endoscopic assessment is reliable when assessing stone size. On average, there was a slight tendency to overestimate stone size by 0.05 mm. Most endourologists could visually estimate stone size within 2 mm of the actual size. These findings could be generalized to state that endourologists are accurately able to intraoperatively assess residual stone fragment size to guide decision making.

High accuracy mapping with cartographic assessment for a fixed-wing remotely piloted aircraft system

Science.gov (United States)

Alves Júnior, Leomar Rufino; Ferreira, Manuel Eduardo; Côrtes, João Batista Ramos; de Castro Jorge, Lúcio André

2018-01-01

The lack of updated maps on large scale representations has encouraged the use of remotely piloted aircraft systems (RPAS) to generate maps for a wide range of professionals. However, some questions arise: do the orthomosaics generated by these systems have the cartographic precision required to use them? Which problems can be identified in stitching orthophotos to generate orthomosaics? To answer these questions, an aerophotogrammetric survey was conducted in an environmental conservation unit in the city of Goiânia. The flight plan was set up using the E-motion software, provided by Sensefly-a Swiss manufacturer of the RPAS Swinglet CAM used in this work. The camera installed in the RPAS was the Canon IXUS 220 HS, with the number of pixels in the sensor array of 12.1 megapixel, complementary metal oxide semiconductor 1 ∶ 2.3 ? (4000 × 3000 pixel), horizontal and vertical pixel sizes of 1.54 μm. Using the orthophotos, four orthomosaics were generated in the Pix4D mapper software. The first orthomosaic was generated without using the control points. The other three mosaics were generated using 4, 8, and 16 premarked ground control points. To check the precision and accuracy of the orthomosaics, 46 premarked targets were uniformly distributed in the block. The three-dimensional (3-D) coordinates of the premarked targets were read on the orthomosaic and compared with the coordinates obtained by the geodetic survey real-time kinematic positioning method using the global navigation satellite system receiver signals. The cartographic accuracy standard was evaluated by discrepancies between these coordinates. The bias was analyzed by the Student's t test and the accuracy by the chi-square probability considering the orthomosaic on a scale of 1 ∶ 250, in which 90% of the points tested must have a planimetric error of control points the scale was 10-fold smaller (1 ∶ 3000).

Data for Program Management: An Accuracy Assessment of Data Collected in Household Registers by Community Health Workers in Southern Kayonza, Rwanda.

Science.gov (United States)

Mitsunaga, Tisha; Hedt-Gauthier, Bethany L; Ngizwenayo, Elias; Farmer, Didi Bertrand; Gaju, Erick; Drobac, Peter; Basinga, Paulin; Hirschhorn, Lisa; Rich, Michael L; Winch, Peter J; Ngabo, Fidele; Mugeni, Cathy

2015-08-01

Community health workers (CHWs) collect data for routine services, surveys and research in their communities. However, quality of these data is largely unknown. Utilizing poor quality data can result in inefficient resource use, misinformation about system gaps, and poor program management and effectiveness. This study aims to measure CHW data accuracy, defined as agreement between household registers compared to household member interview and client records in one district in Eastern province, Rwanda. We used cluster-lot quality assurance sampling to randomly sample six CHWs per cell and six households per CHW. We classified cells as having 'poor' or 'good' accuracy for household registers for five indicators, calculating point estimates of percent of households with accurate data by health center. We evaluated 204 CHW registers and 1,224 households for accuracy across 34 cells in southern Kayonza. Point estimates across health centers ranged from 79 to 100% for individual indicators and 61 to 72% for the composite indicator. Recording error appeared random for all but the widely under-reported number of women on modern family planning method. Overall, accuracy was largely 'good' across cells, with varying results by indicator. Program managers should identify optimum thresholds for 'good' data quality and interventions to reach them according to data use. Decreasing variability and improving quality will facilitate potential of these routinely-collected data to be more meaningful for community health program management. We encourage further studies assessing CHW data quality and the impact training, supervision and other strategies have on improving it.

Accuracy of point-of-care serum creatinine devices for detecting patients at risk of contrast-induced nephropathy: a critical overview.

Science.gov (United States)

Martínez Lomakin, Felipe; Tobar, Catalina

2014-12-01

Contrast-induced nephropathy (CIN) is a common event in hospitals, with reported incidences ranging from 1 to 30%. Patients with underlying kidney disease have an increased risk of developing CIN. Point-of-care (POC) creatinine devices are handheld devices capable of providing quantitative data on a patient's kidney function that could be useful in stratifying preventive measures. This overview aims to synthesize the current evidence on diagnostic accuracy and clinical utility of POC creatinine devices in detecting patients at risk of CIN. Five databases were searched for diagnostic accuracy studies or clinical trials that evaluated the usefulness of POC devices in detecting patients at risk of CIN. Selected articles were critically appraised to assess their individual risk of bias by the use of standard criteria; 13 studies were found that addressed the diagnostic accuracy or clinical utility of POC creatinine devices. Most studies incurred a moderate to high risk of bias. Overall concordance between POC devices and reference standards (clinical laboratory procedures) was found to be moderate, with 95% limits of agreement often lying between -35.4 and +35.4 µmol/L (-0.4 and +0.4 mg/dL). Concordance was shown to decrease with worsening kidney function. Data on the clinical utility of these devices were limited, but a significant reduction in time to diagnosis was reported in two studies. Overall, POC creatinine devices showed a moderate concordance with standard clinical laboratory creatinine measurements. Several biases could have induced optimism in these estimations. Results obtained from these devices may be unreliable in cases of severe kidney failure. Randomized trials are needed to address the clinical utility of these devices.

Fluency or Accuracy - Two Different ‘Colours’ in Writing Assessment

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Listyani Listyani

2017-01-01

Full Text Available Fluency and accuracy. These two things have victoriously won many teachers’ attention at tertiary level. In the case of writing, these two remain debatable, and have always attracted many people, both lecturers’ and students’ attention. These language production measures have distracted many lecturers’ concentration: should they be faithful to fluency of ideas, or grammatical and language accuracy in correcting students’ essays? This paper tries to present the classical yet never-ending dilemmatic conflicts within the area of writing assessment. This debate still remains interesting to follow. Data were gained from close observation on documents, that is, 21 students’ essays and interviews with 2 students of Academic Writing in Semester II, 2015-2016. Four writing lecturers were also interviewed for their intellectual and critical opinions on these dilemmatic problems in assessing writing. Discussion results of FGD (Forum Group Discussion involving all writing lecturers at the English Education Study Program at the Faculty of Language and Literature of Satya Wacana Christian University which were held in June, 2016, were also included as source of data. Hopefully, this paper gives a little more “colour” in the area of writing assessment, and gives a little enlightenment for other writing lecturers.   DOI: https://doi.org/10.24071/llt.2016.190201

Design and analysis for thematic map accuracy assessment: Fundamental principles

Science.gov (United States)

Stephen V. Stehman; Raymond L. Czaplewski

1998-01-01

Land-cover maps are used in numerous natural resource applications to describe the spatial distribution and pattern of land-cover, to estimate areal extent of various cover classes, or as input into habitat suitability models, land-cover change analyses, hydrological models, and risk analyses. Accuracy assessment quantifies data quality so that map users may evaluate...

Assessing Accuracy in Varying LIDAR Data Point Densities in Digital Elevation Maps

Science.gov (United States)

2008-09-01

describes the project undertaken for delimiting the data collected on the regions and outlines the statistical methodology used to assess research...not hydrologically corrected (to enforce flow- direction) • Generated contours not aesthetically appealing • Lidar returns on water are unreliable...and ground “bottom” returns. In his 21 1984 paper, Krabill concluded that the results of the test over the Wolf River Basin “were sufficient to

Accuracy Assessment of Geometrical Elements for Setting-Out in Horizontal Plane of Conveying Chambers at the Bauxite Mine "KOSTURI" Srebrenica

Science.gov (United States)

Milutinović, Aleksandar; Ganić, Aleksandar; Tokalić, Rade

2014-03-01

Setting-out of objects on the exploitation field of the mine, both in surface mining and in the underground mines, is determined by the specified setting-out accuracy of reference points, which are best to define spatial position of the object projected. For the purpose of achieving of the specified accuracy, it is necessary to perform a priori accuracy assessment of parameters, which are to be used when performing setting-out. Based on the a priori accuracy assessment, verification of the quality of geometrical setting- -out elements specified in the layout; definition of the accuracy for setting-out of geometrical elements; selection of setting-out method; selection at the type and class of instruments and tools that need to be applied in order to achieve predefined accuracy. The paper displays the accuracy assessment of geometrical elements for setting-out of the main haul gallery, haul downcast and helical conveying downcasts in shape of an inclined helix in horizontal plane, using the example of the underground bauxite mine »Kosturi«, Srebrenica. Wytyczanie obiektów na polu wydobywczym w kopalniach, zarówno podziemnych jak i odkrywkowych, zależy w dużej mierze od określonej dokładności wytyczania punktów referencyjnych, przy pomocy których określane jest następnie położenie przestrzenne pozostałych obiektów. W celu uzyskania założonej dokładności, należy przeprowadzić wstępną analizę dokładności oszacowania parametrów które następnie wykorzystane będą w procesie wytyczania. W oparciu o wyniki wstępnej analizy dokładności dokonuje się weryfikacji jakości geometrycznego wytyczenia elementów zaznaczonych na szkicu, uwzględniając te wyniki dobrać należy odpowiednią metodę wytyczania i rodzaj oraz klasę wykorzystywanych narzędzi i instrumentów, tak by osiągnąć założony poziom dokładności. W pracy przedstawiono oszacowanie dokładności wytyczania elementów geometrycznych dla głównego chodnika transportowego

Estimating the Accuracy of the Chedoke–McMaster Stroke Assessment Predictive Equations for Stroke Rehabilitation

Science.gov (United States)

Dang, Mia; Ramsaran, Kalinda D.; Street, Melissa E.; Syed, S. Noreen; Barclay-Goddard, Ruth; Miller, Patricia A.

2011-01-01

ABSTRACT Purpose: To estimate the predictive accuracy and clinical usefulness of the Chedoke–McMaster Stroke Assessment (CMSA) predictive equations. Method: A longitudinal prognostic study using historical data obtained from 104 patients admitted post cerebrovascular accident was undertaken. Data were abstracted for all patients undergoing rehabilitation post stroke who also had documented admission and discharge CMSA scores. Published predictive equations were used to determine predicted outcomes. To determine the accuracy and clinical usefulness of the predictive model, shrinkage coefficients and predictions with 95% confidence bands were calculated. Results: Complete data were available for 74 patients with a mean age of 65.3±12.4 years. The shrinkage values for the six Impairment Inventory (II) dimensions varied from −0.05 to 0.09; the shrinkage value for the Activity Inventory (AI) was 0.21. The error associated with predictive values was greater than ±1.5 stages for the II dimensions and greater than ±24 points for the AI. Conclusions: This study shows that the large error associated with the predictions (as defined by the confidence band) for the CMSA II and AI limits their clinical usefulness as a predictive measure. Further research to establish predictive models using alternative statistical procedures is warranted. PMID:22654239

Measuring Adolescent Self-Awareness and Accuracy Using a Performance-Based Assessment and Parental Report

Directory of Open Access Journals (Sweden)

Sharon Zlotnik

2018-02-01

Full Text Available AimThe aim of this study was to assess awareness of performance and performance accuracy for a task that requires executive functions (EF, among healthy adolescents and to compare their performance to their parent’s ratings.MethodParticipants: 109 healthy adolescents (mean age 15.2 ± 1.86 years completed the Weekly Calendar Planning Activity (WCPA. The discrepancy between self-estimated and actual performance was used to measure the level of awareness. The participants were divided into high and low accuracy groups according to the WCPA accuracy median score. The participants were also divided into high and low awareness groups. A comparison was conducted between groups using WCPA performance and parent ratings on the Behavior Rating Inventory of Executive Function (BRIEF.ResultsHigher awareness was associated with better EF performance. Participants with high accuracy scores were more likely to show high awareness of performance as compared to participants with low accuracy scores. The high accuracy group had better parental ratings of EF, higher efficiency, followed more rules, and were more aware of their WCPA performance.ConclusionOur results highlight the important contribution that self-awareness of performance may have on the individual’s function. Assessing the level of awareness and providing metacognitive training techniques for those adolescents who are less aware, could support their performance.

Probabilistic tsunami hazard assessment for Point Lepreau Generating Station

Energy Technology Data Exchange (ETDEWEB)

Mullin, D., E-mail: dmullin@nbpower.com [New Brunswick Power Corporation, Point Lepreau Generating Station, Point Lepreau (Canada); Alcinov, T.; Roussel, P.; Lavine, A.; Arcos, M.E.M.; Hanson, K.; Youngs, R., E-mail: trajce.alcinov@amecfw.com, E-mail: patrick.roussel@amecfw.com [AMEC Foster Wheeler Environment & Infrastructure, Dartmouth, NS (Canada)

2015-07-01

In 2012 the Geological Survey of Canada published a preliminary probabilistic tsunami hazard assessment in Open File 7201 that presents the most up-to-date information on all potential tsunami sources in a probabilistic framework on a national level, thus providing the underlying basis for conducting site-specific tsunami hazard assessments. However, the assessment identified a poorly constrained hazard for the Atlantic Coastline and recommended further evaluation. As a result, NB Power has embarked on performing a Probabilistic Tsunami Hazard Assessment (PTHA) for Point Lepreau Generating Station. This paper provides the methodology and progress or hazard evaluation results for Point Lepreau G.S. (author)

Assessing the accuracy of forecasting: applying standard diagnostic assessment tools to a health technology early warning system.

Science.gov (United States)

Simpson, Sue; Hyde, Chris; Cook, Alison; Packer, Claire; Stevens, Andrew

2004-01-01

Early warning systems are an integral part of many health technology assessment programs. Despite this finding, to date, there have been no quantitative evaluations of the accuracy of predictions made by these systems. We report a study evaluating the accuracy of predictions made by the main United Kingdom early warning system. As prediction of impact is analogous to diagnosis, a method normally applied to determine the accuracy of diagnostic tests was used. The sensitivity, specificity, and predictive values of the National Horizon Scanning Centre's prediction methods were estimated with reference to an (imperfect) gold standard, that is, expert opinion of impact 3 to 5 years after prediction. The sensitivity of predictions was 71 percent (95 percent confidence interval [CI], 0.36-0.92), and the specificity was 73 percent (95 percent CI, 0.64-0.8). The negative predictive value was 98 percent (95 percent CI, 0.92-0.99), and the positive predictive value was 14 percent (95 percent CI, 0.06-0.3). Forecasting is difficult, but the results suggest that this early warning system's predictions have an acceptable level of accuracy. However, there are caveats. The first is that early warning systems may themselves reduce the impact of a technology, as helping to control adoption and diffusion is their main purpose. The second is that the use of an imperfect gold standard may bias the results. As early warning systems are viewed as an increasingly important component of health technology assessment and decision making, their outcomes must be evaluated. The method used here should be investigated further and the accuracy of other early warning systems explored.

Magnetic Tomography - Assessing Tie Bar and Dowel Bar Placement Accuracy : Technical Summary

Science.gov (United States)

2017-12-01

Timely detection of misplaced steel would provide feedback needed to correct the construction process. To address this need, KDOT developed a field instrument capable of non-destructively assessing the placement (depth and orientation) accuracy of re...

On the automated assessment of nuclear reactor systems code accuracy

International Nuclear Information System (INIS)

Kunz, Robert F.; Kasmala, Gerald F.; Mahaffy, John H.; Murray, Christopher J.

2002-01-01

An automated code assessment program (ACAP) has been developed to provide quantitative comparisons between nuclear reactor systems (NRS) code results and experimental measurements. The tool provides a suite of metrics for quality of fit to specific data sets, and the means to produce one or more figures of merit (FOM) for a code, based on weighted averages of results from the batch execution of a large number of code-experiment and code-code data comparisons. Accordingly, this tool has the potential to significantly streamline the verification and validation (V and V) processes in NRS code development environments which are characterized by rapidly evolving software, many contributing developers and a large and growing body of validation data. In this paper, a survey of data conditioning and analysis techniques is summarized which focuses on their relevance to NRS code accuracy assessment. A number of methods are considered for their applicability to the automated assessment of the accuracy of NRS code simulations. A variety of data types and computational modeling methods are considered from a spectrum of mathematical and engineering disciplines. The goal of the survey was to identify needs, issues and techniques to be considered in the development of an automated code assessment procedure, to be used in United States Nuclear Regulatory Commission (NRC) advanced thermal-hydraulic T/H code consolidation efforts. The ACAP software was designed based in large measure on the findings of this survey. An overview of this tool is summarized and several NRS data applications are provided. The paper is organized as follows: The motivation for this work is first provided by background discussion that summarizes the relevance of this subject matter to the nuclear reactor industry. Next, the spectrum of NRS data types are classified into categories, in order to provide a basis for assessing individual comparison methods. Then, a summary of the survey is provided, where each

A Systematic Review to Uncover a Universal Protocol for Accuracy Assessment of 3-Dimensional Virtually Planned Orthognathic Surgery.

Science.gov (United States)

Gaber, Ramy M; Shaheen, Eman; Falter, Bart; Araya, Sebastian; Politis, Constantinus; Swennen, Gwen R J; Jacobs, Reinhilde

2017-11-01

The aim of this study was to systematically review methods used for assessing the accuracy of 3-dimensional virtually planned orthognathic surgery in an attempt to reach an objective assessment protocol that could be universally used. A systematic review of the currently available literature, published until September 12, 2016, was conducted using PubMed as the primary search engine. We performed secondary searches using the Cochrane Database, clinical trial registries, Google Scholar, and Embase, as well as a bibliography search. Included articles were required to have stated clearly that 3-dimensional virtual planning was used and accuracy assessment performed, along with validation of the planning and/or assessment method. Descriptive statistics and quality assessment of included articles were performed. The initial search yielded 1,461 studies. Only 7 studies were included in our review. An important variability was found regarding methods used for 1) accuracy assessment of virtually planned orthognathic surgery or 2) validation of the tools used. Included studies were of moderate quality; reviewers' agreement regarding quality was calculated to be 0.5 using the Cohen κ test. On the basis of the findings of this review, it is evident that the literature lacks consensus regarding accuracy assessment. Hence, a protocol is suggested for accuracy assessment of virtually planned orthognathic surgery with the lowest margin of error. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

In the Right Ballpark? Assessing the Accuracy of Net Price Calculators

Science.gov (United States)

Anthony, Aaron M.; Page, Lindsay C.; Seldin, Abigail

2016-01-01

Large differences often exist between a college's sticker price and net price after accounting for financial aid. Net price calculators (NPCs) were designed to help students more accurately estimate their actual costs to attend a given college. This study assesses the accuracy of information provided by net price calculators. Specifically, we…

ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA

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J. Lei

2017-09-01

Full Text Available Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8 is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Accuracy Assessment of Recent Global Ocean Tide Models around Antarctica

Science.gov (United States)

Lei, J.; Li, F.; Zhang, S.; Ke, H.; Zhang, Q.; Li, W.

2017-09-01

Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Application of data analysis techniques to nuclear reactor systems code to accuracy assessment

International Nuclear Information System (INIS)

Kunz, R.F.; Kasmala, G.F.; Murray, C.J.; Mahaffy, J.H.

2000-01-01

An automated code assessment program (ACAP) has been developed by the authors to provide quantitative comparisons between nuclear reactor systems (NRS) code results and experimental measurements. This software was developed under subcontract to the United States Nuclear Regulatory Commission for use in its NRS code consolidation efforts. In this paper, background on the topic of NRS accuracy and uncertainty assessment is provided which motivates the development of and defines basic software requirements for ACAP. A survey of data analysis techniques was performed, focusing on the applicability of methods in the construction of NRS code-data comparison measures. The results of this review process, which further defined the scope, user interface and process for using ACAP are also summarized. A description of the software package and several sample applications to NRS data sets are provided. Its functionality and ability to provide objective accuracy assessment figures are demonstrated. (author)

Accuracy of renal volume assessment in children by three-dimensional sonography

International Nuclear Information System (INIS)

Fritz, G.A.; Riccabona, M.; Bohdal, G.; Quehenberger, F.

2003-01-01

Purpose: Prospective evaluation of the accuracy of three-dimensional ultrasound (3DUS) to assess the renal parenchymal volume. Materials and Methods: CT, MRI, 2DUS and 3DUS were used to measure the renal volume in 40 patients (range: neonate to 17 years; mean age: 8.95 years). The 3DUS was determined with a Voluson 730 (Kretztechnik, GE) or an external 3D-system (EchoTech, GE) using electromagnetic positioning sensors attached to conventional 2DUS-equipment. The 2DUS volume was calculated with the ellipsoid equation and the 3DUS volume computed with the system integrated software. For CT and MRI, planimetric analysis was used to determine the renal parenchymal volume, whereby the dilated collecting system of a hydronephrosis was subtracted to obtain the real renal parenchymal volume. The results of 2DUS and 3DUS were compared to the results of CT and MRI, and inter- and intraobserver variabilities were calculated. Results: In 74 of 77 kidneys, the 3DUS study was of diagnostic quality. The accuracy of the 3DUS volumes compared well to the CT and MRI volumes with a mean difference of -1.8 ± 4.6% versus a mean difference of -2.4 ± 15.4% for 2DUS. In normal kidneys, the accuracy was -2.6 ± 4.4% for 3DUS and -3.8 ± 14.7% for 2DUS. In hydronephrosis, the accuracy was +4.0 ± 5.9% and +9.6 ± 21.3%, respectively, indicating that 3DUS is more accurate than 2DUS, particularly in kidneys with a dilated collecting system. Inter- and intraobserver variabilities were ± 7.3% and ± 5.3%. Conclusion: For assessing the renal parenchymal volume in children, 3DUS is feasible and comparable to CT and MRI. (orig.) [de

Accuracy Assessment of Immediate and Delayed Implant Placements Using CAD/CAM Surgical Guides.

Science.gov (United States)

Alzoubi, Fawaz; Massoomi, Nima; Nattestad, Anders

2016-10-01

The aim of this study is to assess the accuracy of immediately placed implants using Anatomage Invivo5 computer-assisted design/computer-assisted manufacturing (CAD/CAM) surgical guides and compare the accuracy to delayed implant placement protocol. Patients who had implants placed using Anatomage Invivo5 CAD/CAM surgical guides during the period of 2012-2015 were evaluated retrospectively. Patients who received immediate implant placements and/or delayed implant placements replacing 1-2 teeth were included in this study. Pre- and postsurgical images were superimposed to evaluate deviations at the crest, apex, and angle. A total of 40 implants placed in 29 patients were included in this study. The overall mean deviations measured at the crest, apex, and angle were 0.86 mm, 1.25 mm, and 3.79°, respectively. The means for the immediate group deviations were: crest = 0.85 mm, apex = 1.10, and angle = 3.49°. The means for the delayed group deviations were: crest = 0.88 mm, apex = 1.59, and angle = 4.29°. No statistically significant difference was found at the crest and angle; however, there was a statistically significant difference between the immediate and delayed group at the apex, with the immediate group presenting more accurate placements at the apical point than the delayed group. CAD/CAM surgical guides can be reliable tools to accurately place implants immediately and/or in a delayed fashion. No statistically significant differences were found between the delayed and the immediate group at the crest and angle, however apical position was more accurate in the immediate group.

Accuracy of quantitative visual soil assessment

Science.gov (United States)

van Leeuwen, Maricke; Heuvelink, Gerard; Stoorvogel, Jetse; Wallinga, Jakob; de Boer, Imke; van Dam, Jos; van Essen, Everhard; Moolenaar, Simon; Verhoeven, Frank; Stoof, Cathelijne

2016-04-01

Visual soil assessment (VSA) is a method to assess soil quality visually, when standing in the field. VSA is increasingly used by farmers, farm organisations and companies, because it is rapid and cost-effective, and because looking at soil provides understanding about soil functioning. Often VSA is regarded as subjective, so there is a need to verify VSA. Also, many VSAs have not been fine-tuned for contrasting soil types. This could lead to wrong interpretation of soil quality and soil functioning when contrasting sites are compared to each other. We wanted to assess accuracy of VSA, while taking into account soil type. The first objective was to test whether quantitative visual field observations, which form the basis in many VSAs, could be validated with standardized field or laboratory measurements. The second objective was to assess whether quantitative visual field observations are reproducible, when used by observers with contrasting backgrounds. For the validation study, we made quantitative visual observations at 26 cattle farms. Farms were located at sand, clay and peat soils in the North Friesian Woodlands, the Netherlands. Quantitative visual observations evaluated were grass cover, number of biopores, number of roots, soil colour, soil structure, number of earthworms, number of gley mottles and soil compaction. Linear regression analysis showed that four out of eight quantitative visual observations could be well validated with standardized field or laboratory measurements. The following quantitative visual observations correlated well with standardized field or laboratory measurements: grass cover with classified images of surface cover; number of roots with root dry weight; amount of large structure elements with mean weight diameter; and soil colour with soil organic matter content. Correlation coefficients were greater than 0.3, from which half of the correlations were significant. For the reproducibility study, a group of 9 soil scientists and 7

The Investigation of Accuracy of 3 Dimensional Models Generated From Point Clouds with Terrestrial Laser Scanning

Science.gov (United States)

Gumus, Kutalmis; Erkaya, Halil

2013-04-01

In Terrestrial laser scanning (TLS) applications, it is necessary to take into consideration the conditions that affect the scanning process, especially the general characteristics of the laser scanner, geometric properties of the scanned object (shape, size, etc.), and its spatial location in the environment. Three dimensional models obtained with TLS, allow determining the geometric features and relevant magnitudes of the scanned object in an indirect way. In order to compare the spatial location and geometric accuracy of the 3-dimensional model created by Terrestrial laser scanning, it is necessary to use measurement tools that give more precise results than TLS. Geometric comparisons are performed by analyzing the differences between the distances, the angles between surfaces and the measured values taken from cross-sections between the data from the 3-dimensional model created with TLS and the values measured by other measurement devices The performance of the scanners, the size and shape of the scanned objects are tested using reference objects the sizes of which are determined with high precision. In this study, the important points to consider when choosing reference objects were highlighted. The steps up to processing the point clouds collected by scanning, regularizing these points and modeling in 3 dimensions was presented visually. In order to test the geometric correctness of the models obtained by Terrestrial laser scanners, sample objects with simple geometric shapes such as cubes, rectangular prisms and cylinders that are made of concrete were used as reference models. Three dimensional models were generated by scanning these reference models with Trimble Mensi GS 100. The dimension of the 3D model that is created from point clouds was compared with the precisely measured dimensions of the reference objects. For this purpose, horizontal and vertical cross-sections were taken from the reference objects and generated 3D models and the proximity of

Reliability and accuracy of a video analysis protocol to assess core ability.

Science.gov (United States)

McDonald, Dawn A; Delgadillo, James Q; Fredericson, Michael; McConnell, Jennifer; Hodgins, Melissa; Besier, Thor F

2011-03-01

To develop and test a method to measure core ability in healthy athletes with 2-dimensional video analysis software (SiliconCOACH). Specific objectives were to: (1) develop a standardized exercise battery with progressions of increasing difficulty to evaluate areas of core ability in elite athletes; (2) develop an objective and quantitative grading rubric with the use of video analysis software; (3) assess the test-retest reliability of the exercise battery; (4) assess the interrater and intrarater reliability of the video analysis system; and (5) assess the accuracy of the assessment. Test-retest repeatability and accuracy. Testing was conducted in the Stanford Human Performance Laboratory, Stanford University, Stanford, CA. Nine female gymnasts currently training with the Stanford Varsity Women's Gymnastics Team participated in testing. Participants completed a test battery composed of planks, side planks, and leg bridges of increasing difficulty. Subjects completed two 20-minute testing sessions within a 4- to 10-day period. Two-dimensional sagittal-plane video was captured simultaneously with 3-dimensional motion capture. The main outcome measures were pelvic displacement and time that elapsed until failure occurred, as measured with SiliconCOACH video analysis software. Test-retest and interrater and intrarater reliability of the video analysis measures was assessed. Accuracy as compared with 3-dimensional motion capture also was assessed. Levels reached during the side planks and leg bridges had an excellent test-retest correlation (r(2) = 0.84, r(2) = 0.95). Pelvis displacements measured by examiner 1 and examiner 2 had an excellent correlation (r(2) = 0.86, intraclass correlation coefficient = 0.92). Pelvis displacements measured by examiner 1 during independent grading sessions had an excellent correlation (r(2) = 0.92). Pelvis displacements from the plank and from a set of combined plank and side plank exercises both had an excellent correlation with 3

Accuracy of Automatic Cephalometric Software on Landmark Identification

Science.gov (United States)

Anuwongnukroh, N.; Dechkunakorn, S.; Damrongsri, S.; Nilwarat, C.; Pudpong, N.; Radomsutthisarn, W.; Kangern, S.

2017-11-01

This study was to assess the accuracy of an automatic cephalometric analysis software in the identification of cephalometric landmarks. Thirty randomly selected digital lateral cephalograms of patients undergoing orthodontic treatment were used in this study. Thirteen landmarks (S, N, Or, A-point, U1T, U1A, B-point, Gn, Pog, Me, Go, L1T, and L1A) were identified on the digital image by an automatic cephalometric software and on cephalometric tracing by manual method. Superimposition of printed image and manual tracing was done by registration at the soft tissue profiles. The accuracy of landmarks located by the automatic method was compared with that of the manually identified landmarks by measuring the mean differences of distances of each landmark on the Cartesian plane where X and Y coordination axes passed through the center of ear rod. One-Sample T test was used to evaluate the mean differences. Statistically significant mean differences (pmean differences in both horizontal and vertical directions. Small mean differences (mean differences were found for A-point (3.0 4mm) in vertical direction. Only 5 of 13 landmarks (38.46%; S, N, Gn, Pog, and Go) showed no significant mean difference between the automatic and manual landmarking methods. It is concluded that if this automatic cephalometric analysis software is used for orthodontic diagnosis, the orthodontist must correct or modify the position of landmarks in order to increase the accuracy of cephalometric analysis.

78 FR 58570 - Environmental Assessment; Entergy Nuclear Operations, Inc., Big Rock Point

Science.gov (United States)

2013-09-24

... Assessment; Entergy Nuclear Operations, Inc., Big Rock Point AGENCY: Nuclear Regulatory Commission. ACTION... applicant or the licensee), for the Big Rock Point (BRP) Independent Spent Fuel Storage Installation (ISFSI... Rock Point (BRP) Independent Spent Fuel Storage Installation (ISFSI). II. Environmental Assessment (EA...

Accuracy evaluation of pendulum gravity measurements of Robert von Sterneck

Directory of Open Access Journals (Sweden)

Alena Pešková

2015-06-01

Full Text Available The accuracy of first pendulum gravity measurements in the Czech territory was determined using both original surveying notebooks of Robert Daublebsky von Sterneck and modern technologies. Since more accurate methods are used for gravity measurements nowadays, our work is mostly important from the historical point of view. In previous  works, the accuracy of Sterneck’s gravity measurements was determined using only a small dataset. Here we process all Sterneck’s measurements from the Czech territory (a dataset ten times larger than in the previous works, and we complexly assess the accuracy of these measurements. Locations of the measurements were found with the help of original notebooks. Gravity in the site was interpolated using actual gravity models. Finally, the accuracy of Sterneck’s measurements was evaluated as the difference between the measured and interpolated gravity.

Accuracy Assessment and Analysis for GPT2

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YAO Yibin

2015-07-01

Full Text Available GPT(global pressure and temperature is a global empirical model usually used to provide temperature and pressure for the determination of tropospheric delay, there are some weakness to GPT, these have been improved with a new empirical model named GPT2, which not only improves the accuracy of temperature and pressure, but also provides specific humidity, water vapor pressure, mapping function coefficients and other tropospheric parameters, and no accuracy analysis of GPT2 has been made until now. In this paper high-precision meteorological data from ECWMF and NOAA were used to test and analyze the accuracy of temperature, pressure and water vapor pressure expressed by GPT2, testing results show that the mean Bias of temperature is -0.59℃, average RMS is 3.82℃; absolute value of average Bias of pressure and water vapor pressure are less than 1 mb, GPT2 pressure has average RMS of 7 mb, and water vapor pressure no more than 3 mb, accuracy is different in different latitudes, all of them have obvious seasonality. In conclusion, GPT2 model has high accuracy and stability on global scale.

Point-of-care outcome assessment in the cancer clinic: Audit of data quality

International Nuclear Information System (INIS)

Wong, Karen; Huang, Shao Hui; O'Sullivan, Brian; Lockwood, Gina; Dale, Darlene; Michaelson, Terry; Waldron, John; Bayley, Andrew; Cummings, Bernard; Dawson, Laura A.; Kim, John; Liu, Geoffrey; Ringash, Jolie

2010-01-01

Background and purpose: To assess the completeness and accuracy of stage and outcome data in the Anthology of Outcomes (AOs), a prospective point-of-care physician-collected electronic data system for patients at Princess Margaret Hospital. Material and methods: A random sample of 10% of the AO cases registered between July 2003 and December 2005 was drawn. An audit was conducted of the AO data compared with chart review and cancer registry. Results: The AO system was applied first to a head and neck (HN) cancer patient cohort. From 1152 HN cases, 120 were audited. TNM stage was recorded in all cases. Discrepancy was found between the AO and primary data sources in 3-13% of cases. Physician review showed a 3% error rate in overall stage recorded in the AO. Sixty-two outcomes in 43 patients were found on chart review. No outcomes were incorrectly recorded in the AO. Nineteen (31%) outcomes in 17 patients were missed in the AO. Conclusions: Our experience has demonstrated the feasibility of real-time outcome recording at point-of-care. New processes needed to improve the completeness of capture of patient outcomes in the AO have more recently been introduced. This successful system has been expanded to other disease sites.

Horizontal Positional Accuracy of Google Earth’s High-Resolution Imagery Archive

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David Potere

2008-12-01

Full Text Available Google Earth now hosts high-resolution imagery that spans twenty percent of the Earth’s landmass and more than a third of the human population. This contemporary highresolution archive represents a significant, rapidly expanding, cost-free and largely unexploited resource for scientific inquiry. To increase the scientific utility of this archive, we address horizontal positional accuracy (georegistration by comparing Google Earth with Landsat GeoCover scenes over a global sample of 436 control points located in 109 cities worldwide. Landsat GeoCover is an orthorectified product with known absolute positional accuracy of less than 50 meters root-mean-squared error (RMSE. Relative to Landsat GeoCover, the 436 Google Earth control points have a positional accuracy of 39.7 meters RMSE (error magnitudes range from 0.4 to 171.6 meters. The control points derived from satellite imagery have an accuracy of 22.8 meters RMSE, which is significantly more accurate than the 48 control-points based on aerial photography (41.3 meters RMSE; t-test p-value < 0.01. The accuracy of control points in more-developed countries is 24.1 meters RMSE, which is significantly more accurate than the control points in developing countries (44.4 meters RMSE; t-test p-value < 0.01. These findings indicate that Google Earth highresolution imagery has a horizontal positional accuracy that is sufficient for assessing moderate-resolution remote sensing products across most of the world’s peri-urban areas.

Accuracy assessment of ALOS optical instruments: PRISM and AVNIR-2

Science.gov (United States)

Tadono, Takeo; Shimada, Masanobu; Iwata, Takanori; Takaku, Junichi; Kawamoto, Sachi

2017-11-01

This paper describes the updated results of calibration and validation to assess the accuracies for optical instruments onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi"), which was successfully launched on January 24th, 2006 and it is continuously operating very well. ALOS has an L-band Synthetic Aperture Radar called PALSAR and two optical instruments i.e. the Panchromatic Remotesensing Instrument for Stereo Mapping (PRISM) and the Advanced Visible and Near Infrared Radiometer type-2 (AVNIR-2). PRISM consists of three radiometers and is used to derive a digital surface model (DSM) with high spatial resolution that is an objective of the ALOS mission. Therefore, geometric calibration is important in generating a precise DSM with stereo pair images of PRISM. AVNIR-2 has four radiometric bands from blue to near infrared and uses for regional environment and disaster monitoring etc. The radiometric calibration and image quality evaluation are also important for AVNIR-2 as well as PRISM. This paper describes updated results of geometric calibration including geolocation determination accuracy evaluations of PRISM and AVNIR-2, image quality evaluation of PRISM, and validation of generated PRISM DSM. These works will be done during the ALOS mission life as an operational calibration to keep absolute accuracies of the standard products.

DIRECT GEOREFERENCING ON SMALL UNMANNED AERIAL PLATFORMS FOR IMPROVED RELIABILITY AND ACCURACY OF MAPPING WITHOUT THE NEED FOR GROUND CONTROL POINTS

Directory of Open Access Journals (Sweden)

O. Mian

2015-08-01

Full Text Available This paper presents results from a Direct Mapping Solution (DMS comprised of an Applanix APX-15 UAV GNSS-Inertial system integrated with a Sony a7R camera to produce highly accurate ortho-rectified imagery without Ground Control Points on a Microdrones md4-1000 platform. A 55 millimeter Nikkor f/1.8 lens was mounted on the Sony a7R and the camera was then focused and calibrated terrestrially using the Applanix camera calibration facility, and then integrated with the APX-15 UAV GNSS-Inertial system using a custom mount specifically designed for UAV applications. In July 2015, Applanix and Avyon carried out a test flight of this system. The goal of the test flight was to assess the performance of DMS APX-15 UAV direct georeferencing system on the md4-1000. The area mapped during the test was a 250 x 300 meter block in a rural setting in Ontario, Canada. Several ground control points are distributed within the test area. The test included 8 North-South lines and 1 cross strip flown at 80 meters AGL, resulting in a ~1 centimeter Ground Sample Distance (GSD. Map products were generated from the test flight using Direct Georeferencing, and then compared for accuracy against the known positions of ground control points in the test area. The GNSS-Inertial data collected by the APX-15 UAV was post-processed in Single Base mode, using a base station located in the project area via POSPac UAV. The base-station’s position was precisely determined by processing a 12-hour session using the CSRS-PPP Post Processing service. The ground control points were surveyed in using differential GNSS post-processing techniques with respect to the base-station.

Precision and Accuracy of a Digital Impression Scanner in Full-Arch Implant Rehabilitation.

Science.gov (United States)

Pesce, Paolo; Pera, Francesco; Setti, Paolo; Menini, Maria

To evaluate the accuracy and precision of a digital scanner used to scan four implants positioned according to an immediate loading implant protocol and to assess the accuracy of an aluminum framework fabricated from a digital impression. Five master casts reproducing different edentulous maxillae with four tilted implants were used. Four scan bodies were screwed onto the low-profile abutments, and a digital intraoral scanner was used to perform five digital impressions of each master cast. To assess trueness, a metal framework of the best digital impression was produced with computer-aided design/computer-assisted manufacture (CAD/CAM) technology and passive fit was assessed with the Sheffield test. Gaps between the frameworks and the implant analogs were measured with a stereomicroscope. To assess precision, three-dimensional (3D) point cloud processing software was used to measure the deviations between the five digital impressions of each cast by producing a color map. The deviation values were grouped in three classes, and differences were assessed between class 2 (representing lower discrepancies) and the assembled classes 1 and 3 (representing the higher negative and positive discrepancies, respectively). The frameworks showed a mean gap of 3D point cloud software, with higher frequencies of points in class 2 than in grouped classes 1 and 3 (P impression may represent a reliable method for fabricating full-arch implant frameworks with good passive fit when tilted implants are present.

Quantitative accuracy assessment of thermalhydraulic code predictions with SARBM

International Nuclear Information System (INIS)

Prosek, A.

2001-01-01

In recent years, the nuclear reactor industry has focused significant attention on nuclear reactor systems code accuracy and uncertainty issues. A few methods suitable to quantify code accuracy of thermalhydraulic code calculations were proposed and applied in the past. In this study a Stochastic Approximation Ratio Based Method (SARBM) was adapted and proposed for accuracy quantification. The objective of the study was to qualify the SARBM. The study compare the accuracy obtained by SARBM with the results obtained by widely used Fast Fourier Transform Based Method (FFTBM). The methods were applied to RELAP5/MOD3.2 code calculations of various BETHSY experiments. The obtained results showed that the SARBM was able to satisfactorily predict the accuracy of the calculated trends when visually comparing plots and comparing the results with the qualified FFTBM. The analysis also showed that the new figure-of-merit called accuracy factor (AF) is more convenient than stochastic approximation ratio for combining single variable accuracy's into total accuracy. The accuracy results obtained for the selected tests suggest that the acceptability factors for the SAR method were reasonably defined. The results also indicate that AF is a useful quantitative measure of accuracy.(author)

The validity and reliability of the StationMaster: a device to improve the accuracy of station assessment in labour.

Science.gov (United States)

Awan, Noveen; Rhoades, Anthony; Weeks, Andrew D

2009-07-01

To compare the accuracy of digital assessment and the StationMaster (SM) in the assessment of fetal head station. The SM is a simple modification of the amniotomy hook which works by relocating the point of reference for station assessment from the ischial spines to the posterior fourchette. It is first adjusted to the woman's pelvic size, and then inserted into the vagina until it touches the fetal head. The station is then read off at the posterior fourchette in cm. An in vitro study of test validity and reliability was conducted at Liverpool Women's Hospital, Liverpool, UK. An apparatus was constructed in which a model fetal head could be accurately positioned within a mannequin's pelvis. Twenty midwives and 20 doctors (in current labour ward practice) gave their consent to take part. First, the head was placed in 5 random stations (-2 to +7 cm) and the participant asked to record their digital assessment for each. The participant was then taught to use the SM and the experiment repeated with 5 new stations. The complete experiment was repeated at least 2 weeks later using the same stations but in reverse order. The true values were compared with both the digital and SM assessments using mean differences with 95% limits of agreement. The repeatability of the two methods was assessed in the same way. Overall, the SM was more accurate than digital examination. The mean error (S.D.) ranged from 0.1 (1.2) to 2.6 (1.6) for the StationMaster and 0.3 (1.3) to 4.3 (1.1) for digital examination. Inaccuracies increased as the head descended through the pelvis. When assessed digitally, the true value fell outside one standard deviation for stations of more than +1cm. In contrast, with the SM the true value remained inside one standard deviation for all stations up to +5. In vitro the SM improves the accuracy of intrapartum station assessment.

Accuracy assessment of vegetation community maps generated by aerial photography interpretation: perspective from the tropical savanna, Australia

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Lewis, Donna L.; Phinn, Stuart

2011-01-01

Aerial photography interpretation is the most common mapping technique in the world. However, unlike an algorithm-based classification of satellite imagery, accuracy of aerial photography interpretation generated maps is rarely assessed. Vegetation communities covering an area of 530 km2 on Bullo River Station, Northern Territory, Australia, were mapped using an interpretation of 1:50,000 color aerial photography. Manual stereoscopic line-work was delineated at 1:10,000 and thematic maps generated at 1:25,000 and 1:100,000. Multivariate and intuitive analysis techniques were employed to identify 22 vegetation communities within the study area. The accuracy assessment was based on 50% of a field dataset collected over a 4 year period (2006 to 2009) and the remaining 50% of sites were used for map attribution. The overall accuracy and Kappa coefficient for both thematic maps was 66.67% and 0.63, respectively, calculated from standard error matrices. Our findings highlight the need for appropriate scales of mapping and accuracy assessment of aerial photography interpretation generated vegetation community maps.

Automated Registration of Multimodal Optic Disc Images: Clinical Assessment of Alignment Accuracy.

Science.gov (United States)

Ng, Wai Siene; Legg, Phil; Avadhanam, Venkat; Aye, Kyaw; Evans, Steffan H P; North, Rachel V; Marshall, Andrew D; Rosin, Paul; Morgan, James E

2016-04-01

To determine the accuracy of automated alignment algorithms for the registration of optic disc images obtained by 2 different modalities: fundus photography and scanning laser tomography. Images obtained with the Heidelberg Retina Tomograph II and paired photographic optic disc images of 135 eyes were analyzed. Three state-of-the-art automated registration techniques Regional Mutual Information, rigid Feature Neighbourhood Mutual Information (FNMI), and nonrigid FNMI (NRFNMI) were used to align these image pairs. Alignment of each composite picture was assessed on a 5-point grading scale: "Fail" (no alignment of vessels with no vessel contact), "Weak" (vessels have slight contact), "Good" (vessels with 50% contact), and "Excellent" (complete alignment). Custom software generated an image mosaic in which the modalities were interleaved as a series of alternate 5×5-pixel blocks. These were graded independently by 3 clinically experienced observers. A total of 810 image pairs were assessed. All 3 registration techniques achieved a score of "Good" or better in >95% of the image sets. NRFNMI had the highest percentage of "Excellent" (mean: 99.6%; range, 95.2% to 99.6%), followed by Regional Mutual Information (mean: 81.6%; range, 86.3% to 78.5%) and FNMI (mean: 73.1%; range, 85.2% to 54.4%). Automated registration of optic disc images by different modalities is a feasible option for clinical application. All 3 methods provided useful levels of alignment, but the NRFNMI technique consistently outperformed the others and is recommended as a practical approach to the automated registration of multimodal disc images.

Impact of dual-time-point F-18 FDG PET/CT in the assessment of pleural effusion in patients with non-small-cell lung cancer.

Science.gov (United States)

Alkhawaldeh, Khaled; Biersack, Hans-J; Henke, Anna; Ezziddin, Samer

2011-06-01

The aim of this study was to assess the utility of dual-time-point F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) in differentiating benign from malignant pleural disease, in patients with non-small-cell lung cancer. A total of 61 patients with non-small-cell lung cancer and pleural effusion were included in this retrospective study. All patients had whole-body FDG PET/CT imaging at 60 ± 10 minutes post-FDG injection, whereas 31 patients had second-time delayed imaging repeated at 90 ± 10 minutes for the chest. Maximum standardized uptake values (SUV(max)) and the average percent change in SUV(max) (%SUV) between time point 1 and time point 2 were calculated. Malignancy was defined using the following criteria: (1) visual assessment using 3-points grading scale; (2) SUV(max) ≥2.4; (3) %SUV ≥ +9; and (4) SUV(max) ≥2.4 and/or %SUV ≥ +9. Analysis of variance test and receiver operating characteristic analysis were used in statistical analysis. P < 0.05 was considered significant. Follow-up revealed 29 patient with malignant pleural disease and 31 patients with benign pleural effusion. The average SUV(max) in malignant effusions was 6.5 ± 4 versus 2.2 ± 0.9 in benign effusions (P < 0.0001). The average %SUV in malignant effusions was +13 ± 10 versus -8 ± 11 in benign effusions (P < 0.0004). Sensitivity, specificity, and accuracy for the 5 criteria were as follows: (1) 86%, 72%, and 79%; (2) 93%, 72%, and 82%; (3) 67%, 94%, and 81%; (4) 100%, 94%, and 97%. Dual-time-point F-18 FDG PET can improve the diagnostic accuracy in differentiating benign from malignant pleural disease, with high sensitivity and good specificity.

Influence of Sample Size on Automatic Positional Accuracy Assessment Methods for Urban Areas

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Francisco J. Ariza-López

2018-05-01

Full Text Available In recent years, new approaches aimed to increase the automation level of positional accuracy assessment processes for spatial data have been developed. However, in such cases, an aspect as significant as sample size has not yet been addressed. In this paper, we study the influence of sample size when estimating the planimetric positional accuracy of urban databases by means of an automatic assessment using polygon-based methodology. Our study is based on a simulation process, which extracts pairs of homologous polygons from the assessed and reference data sources and applies two buffer-based methods. The parameter used for determining the different sizes (which range from 5 km up to 100 km has been the length of the polygons’ perimeter, and for each sample size 1000 simulations were run. After completing the simulation process, the comparisons between the estimated distribution functions for each sample and population distribution function were carried out by means of the Kolmogorov–Smirnov test. Results show a significant reduction in the variability of estimations when sample size increased from 5 km to 100 km.

Two- and three-dimensional accuracy of dental impression materials: effects of storage time and moisture contamination.

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Chandran, Deepa T; Jagger, Daryll C; Jagger, Robert G; Barbour, Michele E

2010-01-01

Dental impression materials are used to create an inverse replica of the dental hard and soft tissues, and are used in processes such as the fabrication of crowns and bridges. The accuracy and dimensional stability of impression materials are of paramount importance to the accuracy of fit of the resultant prosthesis. Conventional methods for assessing the dimensional stability of impression materials are two-dimensional (2D), and assess shrinkage or expansion between selected fixed points on the impression. In this study, dimensional changes in four impression materials were assessed using an established 2D and an experimental three-dimensional (3D) technique. The former involved measurement of the distance between reference points on the impression; the latter a contact scanning method for producing a computer map of the impression surface showing localised expansion, contraction and warpage. Dimensional changes were assessed as a function of storage times and moisture contamination comparable to that found in clinical situations. It was evident that dimensional changes observed using the 3D technique were not always apparent using the 2D technique, and that the former offers certain advantages in terms of assessing dimensional accuracy and predictability of impression methods. There are, however, drawbacks associated with 3D techniques such as the more time-consuming nature of the data acquisition and difficulty in statistically analysing the data.

The Osteoporosis Self-Assessment Tool versus alternative tests for selecting postmenopausal women for bone mineral density assessment: a comparative systematic review of accuracy

DEFF Research Database (Denmark)

Rud, B; Hilden, J; Hyldstrup, L

2008-01-01

for Stiffness Index assessed by calcaneal quantitative ultrasonography than for OST (relative sDOR: 1.9, p = 0.005). Studies were few in Asian and black women. Methodological quality, assessed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) checklist, was generally low. CONCLUSIONS: In white......We performed a systematic review of studies comparing the Osteoporosis Self-Assessment Tool (OST) and other tests used to select women for bone mineral density (BMD) assessment. In comparative meta-analyses, we found that the accuracy of OST was similar to other tests that are based on information...... from the medical history. By contrast, assessment by quantitative ultrasonography at the heel was more accurate than OST in discriminating between women with high and low BMD. The methodological quality of the included studies was generally low. INTRODUCTION: Numerous tests are suggested for triaging...

Test Expectancy Affects Metacomprehension Accuracy

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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…

Application of large-eddy simulation to pressurized thermal shock: Assessment of the accuracy

International Nuclear Information System (INIS)

Loginov, M.S.; Komen, E.M.J.; Hoehne, T.

2011-01-01

Highlights: → We compare large-eddy simulation with experiment on the single-phase pressurized thermal shock problem. → Three test cases are considered, they cover entire range of mixing patterns. → The accuracy of the flow mixing in the reactor pressure vessel is assessed qualitatively and quantitatively. - Abstract: Pressurized Thermal Shock (PTS) is identified as one of the safety issues where Computational Fluid Dynamics (CFD) can bring real benefits. The turbulence modeling may impact overall accuracy of the calculated thermal loads on the vessel walls, therefore advanced methods for turbulent flows are required. The feasibility and mesh resolution of LES for single-phase PTS are assessed earlier in a companion paper. The current investigation deals with the accuracy of LES approach with respect to the experiment. Experimental data from the Rossendorf Coolant Mixing (ROCOM) facility is used as a basis for validation. Three test cases with different flow rates are considered. They correspond to a buoyancy-driven, a momentum-driven, and a transitional coolant mixing pattern in the downcomer. Time- and frequency-domain analysis are employed for comparison of the numerical and experimental data. The investigation shows a good qualitative prediction of the bulk flow patterns. The fluctuations are modeled correctly. A conservative estimate of the temperature drop near the wall can be obtained from the numerical results with safety factor of 1.1-1.3. In general, the current LES gives a realistic and reliable description of the considered coolant mixing experiments. The accuracy of the prediction is definitely improved with respect to earlier CFD simulations.

Assessment of Relative Accuracy of AHN-2 Laser Scanning Data Using Planar Features

NARCIS (Netherlands)

Khoshelham, K.; Soudarissanane, S.; Van der Sande, C.

2010-01-01

AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements,

Assessment Of Accuracies Of Remote-Sensing Maps

Science.gov (United States)

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.

Accuracy limitations for low velocity measurements and draft assessment in rooms

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Popiolek, Zbigniew J.; Silva, M.G.

2007-01-01

must be known in order to perform reliable assessment and validation. At present, a low-velocity thermal anemometer (LVTA) with an omnidirectional (spherical) sensor is most often used in practice for measuring air speed due to its low price and easy and convenient operation. The accuracy of the speed......, the definition of realistic requirements in thermal comfort standards as well as validation of CFD predictions is made possible.......The measurement of air temperature, mean air speed, and turbulence intensity is required in order to assess air distribution and draft discomfort in ventilated rooms. The measurements are also used for validation of computational fluid dynamics (CFD) predictions. The uncertainty of the measurements...

The Word Writing CAFE: Assessing Student Writing for Complexity, Accuracy, and Fluency

Science.gov (United States)

Leal, Dorothy J.

2005-01-01

The Word Writing CAFE is a new assessment tool designed for teachers to evaluate objectively students' word-writing ability for fluency, accuracy, and complexity. It is designed to be given to the whole class at one time. This article describes the development of the CAFE and provides directions for administering and scoring it. The author also…

The Accuracy of Student Self-Assessments of English-Chinese Bidirectional Interpretation: A Longitudinal Quantitative Study

Science.gov (United States)

Han, Chao; Riazi, Mehdi

2018-01-01

The accuracy of self-assessment has long been examined empirically in higher education research, producing a substantial body of literature that casts light on numerous potential moderators. However, despite the growing popularity of self-assessment in interpreter training and education, very limited evidence-based research has been initiated to…

Assessing the accuracy of ancestral protein reconstruction methods.

Directory of Open Access Journals (Sweden)

Paul D Williams

2006-06-01

Full Text Available The phylogenetic inference of ancestral protein sequences is a powerful technique for the study of molecular evolution, but any conclusions drawn from such studies are only as good as the accuracy of the reconstruction method. Every inference method leads to errors in the ancestral protein sequence, resulting in potentially misleading estimates of the ancestral protein's properties. To assess the accuracy of ancestral protein reconstruction methods, we performed computational population evolution simulations featuring near-neutral evolution under purifying selection, speciation, and divergence using an off-lattice protein model where fitness depends on the ability to be stable in a specified target structure. We were thus able to compare the thermodynamic properties of the true ancestral sequences with the properties of "ancestral sequences" inferred by maximum parsimony, maximum likelihood, and Bayesian methods. Surprisingly, we found that methods such as maximum parsimony and maximum likelihood that reconstruct a "best guess" amino acid at each position overestimate thermostability, while a Bayesian method that sometimes chooses less-probable residues from the posterior probability distribution does not. Maximum likelihood and maximum parsimony apparently tend to eliminate variants at a position that are slightly detrimental to structural stability simply because such detrimental variants are less frequent. Other properties of ancestral proteins might be similarly overestimated. This suggests that ancestral reconstruction studies require greater care to come to credible conclusions regarding functional evolution. Inferred functional patterns that mimic reconstruction bias should be reevaluated.

Assessing the accuracy of ancestral protein reconstruction methods.

Science.gov (United States)

Williams, Paul D; Pollock, David D; Blackburne, Benjamin P; Goldstein, Richard A

2006-06-23

The phylogenetic inference of ancestral protein sequences is a powerful technique for the study of molecular evolution, but any conclusions drawn from such studies are only as good as the accuracy of the reconstruction method. Every inference method leads to errors in the ancestral protein sequence, resulting in potentially misleading estimates of the ancestral protein's properties. To assess the accuracy of ancestral protein reconstruction methods, we performed computational population evolution simulations featuring near-neutral evolution under purifying selection, speciation, and divergence using an off-lattice protein model where fitness depends on the ability to be stable in a specified target structure. We were thus able to compare the thermodynamic properties of the true ancestral sequences with the properties of "ancestral sequences" inferred by maximum parsimony, maximum likelihood, and Bayesian methods. Surprisingly, we found that methods such as maximum parsimony and maximum likelihood that reconstruct a "best guess" amino acid at each position overestimate thermostability, while a Bayesian method that sometimes chooses less-probable residues from the posterior probability distribution does not. Maximum likelihood and maximum parsimony apparently tend to eliminate variants at a position that are slightly detrimental to structural stability simply because such detrimental variants are less frequent. Other properties of ancestral proteins might be similarly overestimated. This suggests that ancestral reconstruction studies require greater care to come to credible conclusions regarding functional evolution. Inferred functional patterns that mimic reconstruction bias should be reevaluated.

Orthorectification of KOMPSAT Optical Images Using Various Ground Reference Data and Accuracy Assessment

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Kwangjae Lee

2017-01-01

Full Text Available Along with the appearance of high resolution satellite images, image correction using Rational Polynomial Coefficients (RPCs has become common. Location accuracy of Korea Multipurpose Satellite (KOMPSAT standard images is still not adequate, so, in order to leverage the KOMPSAT images for applications such as mapping and change detection, it is necessary to orthorectify the images. In this study, using updated RPCs, we performed orthorectification of KOMPSAT-2, KOMPSAT-3, and KOMPSAT-3A images using various data. Through this study, we discovered that the orthorectification result using precise Ground Control Points (GCPs and Digital Elevation Model (DEM is the best, but it was found that the correction results through image matching are also excellent. In particular, it was confirmed that orthoimages with a planimetric accuracy around 3 m (Root Mean Square Error (RMSE can be generated by using well-known matching algorithms with open data such as OpenStreetMap (OSM and Shuttle Radar Topography Mission (SRTM DEM, which can be acquired by anyone. Although the accuracy was low in some mountainous terrain, it was confirmed that it could be used for generating KOMPSAT orthoimages using open data. This paper describes the results for orthorectifying high resolution KOMPSAT optical images using various reference data.

Convergence Time and Positioning Accuracy Comparison between BDS and GPS Precise Point Positioning

Directory of Open Access Journals (Sweden)

ZHANG Xiaohong

2015-03-01

Full Text Available BDS/GPS data from MGEX were processed by TriP 2.0 software developed at Wuhan University. Both static and kinematic float PPP are tested by adopting precise satellite orbits and clocks provided by Research Center of GNSS, Wuhan University. The results show that the convergence time of BDS static PPP is about 80min while kinematic PPP is about 100min. For 3h observations, static positioning accuracy of 5 cm and kinematic positioning accuracy of 8 cm in horizontal, about 12 cm in vertical can be achieved. Similar to GPS PPP, precision in east component is worse than north. At present, BDS PPP needs longer convergence time than GPS PPP to reach an absolute positioning accuracy of cm~dm due to the lack of global tracking stations and the limited accuracy of orbit and clock products.

Objective assessment of the aesthetic outcomes of breast cancer treatment: toward automatic localization of fiducial points on digital photographs

Science.gov (United States)

Udpa, Nitin; Sampat, Mehul P.; Kim, Min Soon; Reece, Gregory P.; Markey, Mia K.

2007-03-01

The contemporary goals of breast cancer treatment are not limited to cure but include maximizing quality of life. All breast cancer treatment can adversely affect breast appearance. Developing objective, quantifiable methods to assess breast appearance is important to understand the impact of deformity on patient quality of life, guide selection of current treatments, and make rational treatment advances. A few measures of aesthetic properties such as symmetry have been developed. They are computed from the distances between manually identified fiducial points on digital photographs. However, this is time-consuming and subject to intra- and inter-observer variability. The purpose of this study is to investigate methods for automatic localization of fiducial points on anterior-posterior digital photographs taken to document the outcomes of breast reconstruction. Particular emphasis is placed on automatic localization of the nipple complex since the most widely used aesthetic measure, the Breast Retraction Assessment, quantifies the symmetry of nipple locations. The nipple complexes are automatically localized using normalized cross-correlation with a template bank of variants of Gaussian and Laplacian of Gaussian filters. A probability map of likely nipple locations determined from the image database is used to reduce the number of false positive detections from the matched filter operation. The accuracy of the nipple detection was evaluated relative to markings made by three human observers. The impact of using the fiducial point locations as identified by the automatic method, as opposed to the manual method, on the calculation of the Breast Retraction Assessment was also evaluated.

FIELD ACCURACY TEST OF RPAS PHOTOGRAMMETRY

Directory of Open Access Journals (Sweden)

P. Barry

2013-08-01

Full Text Available Baseline Surveys Ltd is a company which specialises in the supply of accurate geospatial data, such as cadastral, topographic and engineering survey data to commercial and government bodies. Baseline Surveys Ltd invested in aerial drone photogrammetric technology and had a requirement to establish the spatial accuracy of the geographic data derived from our unmanned aerial vehicle (UAV photogrammetry before marketing our new aerial mapping service. Having supplied the construction industry with survey data for over 20 years, we felt that is was crucial for our clients to clearly understand the accuracy of our photogrammetry so they can safely make informed spatial decisions, within the known accuracy limitations of our data. This information would also inform us on how and where UAV photogrammetry can be utilised. What we wanted to find out was the actual accuracy that can be reliably achieved using a UAV to collect data under field conditions throughout a 2 Ha site. We flew a UAV over the test area in a "lawnmower track" pattern with an 80% front and 80% side overlap; we placed 45 ground markers as check points and surveyed them in using network Real Time Kinematic Global Positioning System (RTK GPS. We specifically designed the ground markers to meet our accuracy needs. We established 10 separate ground markers as control points and inputted these into our photo modelling software, Agisoft PhotoScan. The remaining GPS coordinated check point data were added later in ArcMap to the completed orthomosaic and digital elevation model so we could accurately compare the UAV photogrammetry XYZ data with the RTK GPS XYZ data at highly reliable common points. The accuracy we achieved throughout the 45 check points was 95% reliably within 41 mm horizontally and 68 mm vertically and with an 11.7 mm ground sample distance taken from a flight altitude above ground level of 90 m.The area covered by one image was 70.2 m × 46.4 m, which equals 0.325 Ha. This

The influence of image sensor irradiation damage on the tracking and pointing accuracy of optical communication system

Science.gov (United States)

Li, Xiaoliang; Luo, Lei; Li, Pengwei; Yu, Qingkui

2018-03-01

The image sensor in satellite optical communication system may generate noise due to space irradiation damage, leading to deviation for the determination of the light spot centroid. Based on the irradiation test data of CMOS devices, simulated defect spots in different sizes have been used for calculating the centroid deviation value by grey-level centroid algorithm. The impact on tracking & pointing accuracy of the system has been analyzed. The results show that both the amount and the position of irradiation-induced defect pixels contribute to spot centroid deviation. And the larger spot has less deviation. At last, considering the space radiation damage, suggestions are made for the constraints of spot size selection.

Venous, Arterialized-Venous, or Capillary Glucose Reference Measurements for the Accuracy Assessment of a Continuous Glucose Monitoring System

NARCIS (Netherlands)

Kropff, Jort; van Steen, Sigrid C.; deGraaff, Peter; Chan, Man W.; van Amstel, Rombout B. E.; DeVries, J. Hans

2017-01-01

Background: Different reference methods are used for the accuracy assessment of continuous glucose monitoring (CGM) systems. The effect of using venous, arterialized-venous, or capillary reference measurements on CGM accuracy is unclear. Methods: We evaluated 21 individuals with type 1 diabetes

The Feasibility of 3d Point Cloud Generation from Smartphones

Science.gov (United States)

Alsubaie, N.; El-Sheimy, N.

2016-06-01

This paper proposes a new technique for increasing the accuracy of direct geo-referenced image-based 3D point cloud generated from low-cost sensors in smartphones. The smartphone's motion sensors are used to directly acquire the Exterior Orientation Parameters (EOPs) of the captured images. These EOPs, along with the Interior Orientation Parameters (IOPs) of the camera/ phone, are used to reconstruct the image-based 3D point cloud. However, because smartphone motion sensors suffer from poor GPS accuracy, accumulated drift and high signal noise, inaccurate 3D mapping solutions often result. Therefore, horizontal and vertical linear features, visible in each image, are extracted and used as constraints in the bundle adjustment procedure. These constraints correct the relative position and orientation of the 3D mapping solution. Once the enhanced EOPs are estimated, the semi-global matching algorithm (SGM) is used to generate the image-based dense 3D point cloud. Statistical analysis and assessment are implemented herein, in order to demonstrate the feasibility of 3D point cloud generation from the consumer-grade sensors in smartphones.

Accuracy assessment of Terra-MODIS aerosol optical depth retrievals

International Nuclear Information System (INIS)

Safarpour, Sahabeh; Abdullah, Khiruddin; Lim, Hwee San; Dadras, Mohsen

2014-01-01

Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products have been widely used to address environment and climate change subjects with daily global coverage. Aerosol optical depth (AOD) is retrieved by different algorithms based on the pixel surface, determining between land and ocean. MODIS-Terra and Global Aerosol Robotic Network (AERONET) products can be obtained from the Multi-sensor Aerosol Products Sampling System (MAPSS) for coastal regions during 2000-2010. Using data collected from 83 coastal stations worldwide from AERONET from 2000-2010, accuracy assessments are made for coastal aerosol optical depth (AOD) retrieved from MODIS aboard the Terra satellite. AOD retrieved from MODIS at 0.55μm wavelength has been compared With the AERONET derived AOD, because it is reliable with the major wavelength used by many chemistry transport and climate models as well as previous MODIS validation studies. After removing retrievals with quality flags below1 for Ocean algorithm and below 3 for Land algorithm, The accuracy of AOD retrieved from MODIS Dark Target Ocean algorithms (correlation coefficient R 2 is 0.844 and a regression equation of τ M = 0.91·τ A + 0.02 (where subscripts M and A represent MODIS and AERONET respectively), is the greater than the MODIS Dark Target Land algorithms (correlation coefficient R 2 is 0.764 and τ M = 0.95·τ A + 0.03) and the Deep Blue algorithm (correlation coefficient R 2 is 0.652 and τ M = 0.81·τ A + 0.04). The reasons of the retrieval error in AOD are found to be the various underlying surface reflectance. Therefore, the aerosol models and underlying surface reflectance are the dominant factors which influence the accuracy of MODIS retrieval performance. Generally the MODIS Land algorithm implements better than the Ocean algorithm for coastal sites

Methodological quality of diagnostic accuracy studies on non-invasive coronary CT angiography: influence of QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) items on sensitivity and specificity

International Nuclear Information System (INIS)

Schueler, Sabine; Walther, Stefan; Schuetz, Georg M.; Schlattmann, Peter; Dewey, Marc

2013-01-01

To evaluate the methodological quality of diagnostic accuracy studies on coronary computed tomography (CT) angiography using the QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) tool. Each QUADAS item was individually defined to adapt it to the special requirements of studies on coronary CT angiography. Two independent investigators analysed 118 studies using 12 QUADAS items. Meta-regression and pooled analyses were performed to identify possible effects of methodological quality items on estimates of diagnostic accuracy. The overall methodological quality of coronary CT studies was merely moderate. They fulfilled a median of 7.5 out of 12 items. Only 9 of the 118 studies fulfilled more than 75 % of possible QUADAS items. One QUADAS item (''Uninterpretable Results'') showed a significant influence (P = 0.02) on estimates of diagnostic accuracy with ''no fulfilment'' increasing specificity from 86 to 90 %. Furthermore, pooled analysis revealed that each QUADAS item that is not fulfilled has the potential to change estimates of diagnostic accuracy. The methodological quality of studies investigating the diagnostic accuracy of non-invasive coronary CT is only moderate and was found to affect the sensitivity and specificity. An improvement is highly desirable because good methodology is crucial for adequately assessing imaging technologies. (orig.)

Methodological quality of diagnostic accuracy studies on non-invasive coronary CT angiography: influence of QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) items on sensitivity and specificity

Energy Technology Data Exchange (ETDEWEB)

Schueler, Sabine; Walther, Stefan; Schuetz, Georg M. [Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Charite Medical School, Department of Radiology, Berlin (Germany); Schlattmann, Peter [University Hospital of Friedrich Schiller University Jena, Department of Medical Statistics, Informatics, and Documentation, Jena (Germany); Dewey, Marc [Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Charite Medical School, Department of Radiology, Berlin (Germany); Charite, Institut fuer Radiologie, Berlin (Germany)

2013-06-15

To evaluate the methodological quality of diagnostic accuracy studies on coronary computed tomography (CT) angiography using the QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) tool. Each QUADAS item was individually defined to adapt it to the special requirements of studies on coronary CT angiography. Two independent investigators analysed 118 studies using 12 QUADAS items. Meta-regression and pooled analyses were performed to identify possible effects of methodological quality items on estimates of diagnostic accuracy. The overall methodological quality of coronary CT studies was merely moderate. They fulfilled a median of 7.5 out of 12 items. Only 9 of the 118 studies fulfilled more than 75 % of possible QUADAS items. One QUADAS item (''Uninterpretable Results'') showed a significant influence (P = 0.02) on estimates of diagnostic accuracy with ''no fulfilment'' increasing specificity from 86 to 90 %. Furthermore, pooled analysis revealed that each QUADAS item that is not fulfilled has the potential to change estimates of diagnostic accuracy. The methodological quality of studies investigating the diagnostic accuracy of non-invasive coronary CT is only moderate and was found to affect the sensitivity and specificity. An improvement is highly desirable because good methodology is crucial for adequately assessing imaging technologies. (orig.)

Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions - Effect of Velocity

Science.gov (United States)

Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

2013-01-01

Background Inertial measurement of motion with Attitude and Heading Reference Systems (AHRS) is emerging as an alternative to 3D motion capture systems in biomechanics. The objectives of this study are: 1) to describe the absolute and relative accuracy of multiple units of commercially available AHRS under various types of motion; and 2) to evaluate the effect of motion velocity on the accuracy of these measurements. Methods The criterion validity of accuracy was established under controlled conditions using an instrumented Gimbal table. AHRS modules were carefully attached to the center plate of the Gimbal table and put through experimental static and dynamic conditions. Static and absolute accuracy was assessed by comparing the AHRS orientation measurement to those obtained using an optical gold standard. Relative accuracy was assessed by measuring the variation in relative orientation between modules during trials. Findings Evaluated AHRS systems demonstrated good absolute static accuracy (mean error < 0.5o) and clinically acceptable absolute accuracy under condition of slow motions (mean error between 0.5o and 3.1o). In slow motions, relative accuracy varied from 2o to 7o depending on the type of AHRS and the type of rotation. Absolute and relative accuracy were significantly affected (p<0.05) by velocity during sustained motions. The extent of that effect varied across AHRS. Interpretation Absolute and relative accuracy of AHRS are affected by environmental magnetic perturbations and conditions of motions. Relative accuracy of AHRS is mostly affected by the ability of all modules to locate the same global reference coordinate system at all time. Conclusions Existing AHRS systems can be considered for use in clinical biomechanics under constrained conditions of use. While their individual capacity to track absolute motion is relatively consistent, the use of multiple AHRS modules to compute relative motion between rigid bodies needs to be optimized according to

A fuzzy set approach to assess the predictive accuracy of land use simulations

NARCIS (Netherlands)

van Vliet, J.; Hagen-Zanker, A.; Hurkens, J.; van van Delden, H.

2013-01-01

The predictive accuracy of land use models is frequently assessed by comparing two data sets: the simulated land use map and the observed land use map at the end of the simulation period. A common statistic for this is Kappa, which expresses the agreement between two categorical maps, corrected for

Accuracy and interobserver concordance of echocardiographic assessment of right ventricular size and systolic function: a quality control exercise.

Science.gov (United States)

Ling, Lee Fong; Obuchowski, Nancy A; Rodriguez, Leonardo; Popovic, Zoran; Kwon, Deborah; Marwick, Thomas H

2012-07-01

Accurate assessment of right ventricular (RV) size (RVS) and RV systolic function (RVSF) is vital in the management of various conditions, but their assessment is challenging using echocardiography. The aim of this study was to determine the accuracy and interobserver concordance of qualitative and quantitative RV echocardiography. Fifteen readers evaluated RV function in 12 patients (360 readings) who underwent echocardiography and cardiac magnetic resonance for RV assessment. Readers qualitatively estimated RVS and RVSF as normal, mild, moderate, or severe and then reassessed quantitatively by adding RV dimensions, fractional area change, S', tricuspid annular plane systolic excursion, and RV index of myocardial performance. Cardiac magnetic resonance was used as the reference standard for grading RVS and RVSF. Quantitative measurements increased accuracy and interreader agreement compared to qualitative assessment alone, especially in normal categories. Readers' accuracy for diagnosing normal and severe RVS increased from 38% to 78% (P = .001) and from 70% to 97% (P = .018), and readers' accuracy for diagnosing normal and mild RVSF increased from 52% to 84% (P value of 0.40 to 0.77 (fair to good agreement) for RVS and from 0.43 to 0.66 (moderate to good agreement) for RVSF. Visual estimation of RVS and RVSF is inaccurate and has wide interobserver variability. Quantitation improves accuracy and reliability, especially in distinction of normal and abnormal. The reliability of mild and moderate grades remains inadequate, and further guidance is needed for the classification of abnormal categories. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

The Q* Index: A Useful Global Measure of Dementia Screening Test Accuracy

Directory of Open Access Journals (Sweden)

A.J. Larner

2015-06-01

Full Text Available Background/Aims: Single, global or unitary, indicators of test diagnostic performance have intuitive appeal for clinicians. The Q* index, the point in receiver operating characteristic (ROC curve space closest to the ideal top left-hand corner and where test sensitivity and specificity are equal, is one such measure. Methods: Datasets from four pragmatic accuracy studies which examined the Mini-Mental State Examination, Addenbrooke's Cognitive Examination-Revised, Montreal Cognitive Assessment, Test Your Memory test, and Mini-Addenbrooke's Cognitive Examination were examined to calculate and compare the Q* index, the maximal correct classification accuracy, and the maximal Youden index, as well as the sensitivity and specificity at these cutoffs. Results: Tests ranked similarly for the Q* index and the area under the ROC curve (AUC ROC. The Q* index cutoff was more sensitive (and less specific than the maximal correct classification accuracy cutoff, and less sensitive (and more specific than the maximal Youden index cutoff. Conclusion: The Q* index may be a useful global parameter summarising the test accuracy of cognitive screening instruments, facilitating comparison between tests, and defining a possible test cutoff value. As the point of equal sensitivity and specificity, its use may be more intuitive and appealing for clinicians than AUC ROC.

Coupling Uncertainties with Accuracy Assessment in Object-Based Slum Detections, Case Study: Jakarta, Indonesia

NARCIS (Netherlands)

Pratomo, J.; Kuffer, M.; Martinez, Javier; Kohli, D.

2017-01-01

Object-Based Image Analysis (OBIA) has been successfully used to map slums. In general, the occurrence of uncertainties in producing geographic data is inevitable. However, most studies concentrated solely on assessing the classification accuracy and neglecting the inherent uncertainties. Our

Assessment of Photogrammetric Mapping Accuracy Based on Variation Flying Altitude Using Unmanned Aerial Vehicle

International Nuclear Information System (INIS)

Udin, W S; Ahmad, A

2014-01-01

Photogrammetry is the earliest technique used to collect data for topographic mapping. The recent development in aerial photogrammetry is the used of large format digital aerial camera for producing topographic map. The aerial photograph can be in the form of metric or non-metric imagery. The cost of mapping using aerial photogrammetry is very expensive. In certain application, there is a need to map small area with limited budget. Due to the development of technology, small format aerial photogrammetry technology has been introduced and offers many advantages. Currently, digital map can be extracted from digital aerial imagery of small format camera mounted on light weight platform such as unmanned aerial vehicle (UAV). This study utilizes UAV system for large scale stream mapping. The first objective of this study is to investigate the use of light weight rotary-wing UAV for stream mapping based on different flying height. Aerial photograph were acquired at 60% forward lap and 30% sidelap specifications. Ground control points and check points were established using Total Station technique. The digital camera attached to the UAV was calibrated and the recovered camera calibration parameters were then used in the digital images processing. The second objective is to determine the accuracy of the photogrammetric output. In this study, the photogrammetric output such as stereomodel in three dimensional (3D), contour lines, digital elevation model (DEM) and orthophoto were produced from a small stream of 200m long and 10m width. The research output is evaluated for planimetry and vertical accuracy using root mean square error (RMSE). Based on the finding, sub-meter accuracy is achieved and the RMSE value decreases as the flying height increases. The difference is relatively small. Finally, this study shows that UAV is very useful platform for obtaining aerial photograph and subsequently used for photogrammetric mapping and other applications

Research on Horizontal Accuracy Method of High Spatial Resolution Remotely Sensed Orthophoto Image

Science.gov (United States)

Xu, Y. M.; Zhang, J. X.; Yu, F.; Dong, S.

2018-04-01

At present, in the inspection and acceptance of high spatial resolution remotly sensed orthophoto image, the horizontal accuracy detection is testing and evaluating the accuracy of images, which mostly based on a set of testing points with the same accuracy and reliability. However, it is difficult to get a set of testing points with the same accuracy and reliability in the areas where the field measurement is difficult and the reference data with high accuracy is not enough. So it is difficult to test and evaluate the horizontal accuracy of the orthophoto image. The uncertainty of the horizontal accuracy has become a bottleneck for the application of satellite borne high-resolution remote sensing image and the scope of service expansion. Therefore, this paper proposes a new method to test the horizontal accuracy of orthophoto image. This method using the testing points with different accuracy and reliability. These points' source is high accuracy reference data and field measurement. The new method solves the horizontal accuracy detection of the orthophoto image in the difficult areas and provides the basis for providing reliable orthophoto images to the users.

75 FR 14206 - FPL Energy Point Beach, LLC; Point Beach Nuclear Plant, Units 1 and 2; Environmental Assessment...

Science.gov (United States)

2010-03-24

... NUCLEAR REGULATORY COMMISSION [Docket Nos. 50-266 And 50-301; NRC-2010-0123 FPL Energy Point Beach, LLC; Point Beach Nuclear Plant, Units 1 and 2; Environmental Assessment and Finding of No Significant Impact The U.S. Nuclear Regulatory Commission (NRC) is considering issuance of an Exemption, pursuant to...

Accuracy of self-reported tobacco assessments in a head and neck cancer treatment population

International Nuclear Information System (INIS)

Warren, Graham W.; Arnold, Susanne M.; Valentino, Joseph P.; Gal, Thomas J.; Hyland, Andrew J.; Singh, Anurag K.; Rangnekar, Vivek M.; Cummings, K. Michael; Marshall, James R.; Kudrimoti, Mahesh R.

2012-01-01

Prospective analysis was performed of self-reported and biochemically confirmed tobacco use in 50 head and neck cancer patients during treatment. With 93.5% compliance to complete weekly self-report and biochemical confirmatory tests, 29.4% of smokers required biochemical assessment for identification. Accuracy increased by 14.9% with weekly vs. baseline self-reported assessments. Data confirm that head and neck cancer patients misrepresent true tobacco use during treatment.

Wind hazard assessment for Point Lepreau Generating Station

International Nuclear Information System (INIS)

Mullin, D.; Moland, M.; Sciaudone, J.C.; Twisdale, L.A.; Vickery, P.J.; Mizzen, D.R.

2015-01-01

In response to the CNSC Fukushima Action Plan, NB Power has embarked on a wind hazard assessment for the Point Lepreau Generating Station site that incorporates the latest up to date wind information and modeling. The objective was to provide characterization of the wind hazard from all potential sources and estimate wind-driven missile fragilities and wind pressure fragilities for various structures, systems and components that would provide input to a possible high wind Probabilistic Safety Assessment. The paper will discuss the overall methodology used to assess hazards related to tornadoes, hurricanes and straight-line winds, and site walk-down and hazard/fragility results. (author)

Effects of LiDAR point density and landscape context on the retrieval of urban forest biomass

Science.gov (United States)

Singh, K. K.; Chen, G.; McCarter, J. B.; Meentemeyer, R. K.

2014-12-01

Light Detection and Ranging (LiDAR), as an alternative to conventional optical remote sensing, is being increasingly used to accurately estimate aboveground forest biomass ranging from individual tree to stand levels. Recent advancements in LiDAR technology have resulted in higher point densities and better data accuracies, which however pose challenges to the procurement and processing of LiDAR data for large-area assessments. Reducing point density cuts data acquisition costs and overcome computational challenges for broad-scale forest management. However, how does that impact the accuracy of biomass estimation in an urban environment containing a great level of anthropogenic disturbances? The main goal of this study is to evaluate the effects of LiDAR point density on the biomass estimation of remnant forests in the rapidly urbanizing regions of Charlotte, North Carolina, USA. We used multiple linear regression to establish the statistical relationship between field-measured biomass and predictor variables (PVs) derived from LiDAR point clouds with varying densities. We compared the estimation accuracies between the general Urban Forest models (no discrimination of forest type) and the Forest Type models (evergreen, deciduous, and mixed), which was followed by quantifying the degree to which landscape context influenced biomass estimation. The explained biomass variance of Urban Forest models, adjusted R2, was fairly consistent across the reduced point densities with the highest difference of 11.5% between the 100% and 1% point densities. The combined estimates of Forest Type biomass models outperformed the Urban Forest models using two representative point densities (100% and 40%). The Urban Forest biomass model with development density of 125 m radius produced the highest adjusted R2 (0.83 and 0.82 at 100% and 40% LiDAR point densities, respectively) and the lowest RMSE values, signifying the distance impact of development on biomass estimation. Our evaluation

Clinical assessment of the accuracy of blood glucose measurement devices.

Science.gov (United States)

Pfützner, Andreas; Mitri, Michael; Musholt, Petra B; Sachsenheimer, Daniela; Borchert, Marcus; Yap, Andrew; Forst, Thomas

2012-04-01

Blood glucose meters for patient self-measurement need to comply with the accuracy standards of the ISO 15197 guideline. We investigated the accuracy of the two new blood glucose meters BG*Star and iBG*Star (Sanofi-Aventis) in comparison to four other competitive devices (Accu-Chek Aviva, Roche Diagnostics; FreeStyle Freedom Lite, Abbott Medisense; Contour, Bayer; OneTouch Ultra 2, Lifescan) at different blood glucose ranges in a clinical setting with healthy subjects and patients with type 1 and type 2 diabetes. BGStar and iBGStar are employ dynamic electrochemistry, which is supposed to result in highly accurate results. The study was performed on 106 participants (53 female, 53 male, age (mean ± SD): 46 ± 16 years, type 1: 32 patients, type 2: 34 patients, and 40 healthy subjects). Two devices from each type and strips from two different production lots were used for glucose assessment (∼200 readings/meter). Spontaneous glucose assessments and glucose or insulin interventions under medical supervision were applied to perform measurements in the different glucose ranges in accordance with the ISO 15197 requirements. Sample values 400 mg/dL were prepared by laboratory manipulations. The YSI glucose analyzer (glucose oxidase method) served as the standard reference method which may be considered to be a limitation in light of glucose hexokinase-based meters. For all devices, there was a very close correlation between the glucose results compared to the YSI reference method results. The correlation coefficients were r = 0.995 for BGStar and r = 0.992 for iBGStar (Aviva: 0.995, Freedom Lite: 0.990, Contour: 0.993, Ultra 2: 0.990). Error-grid analysis according to Parkes and Clarke revealed both 100% of the readings to be within the clinically acceptable areas (Clarke: A + B with BG*Star (100 + 0), Aviva (97 + 3), and Contour (97 + 3); and 99.5% with iBG*Star (97.5 + 2), Freedom Lite (98 + 1.5), and Ultra 2 (97.5 + 2

A Proposed Methodology to Assess the Accuracy of 3D Scanners and Casts and Monitor Tooth Wear Progression in Patients.

Science.gov (United States)

Ahmed, Khaled E; Whitters, John; Ju, Xiangyang; Pierce, S Gareth; MacLeod, Charles N; Murray, Colin A

2016-01-01

The aim of this study was to detail and assess the capability of a novel methodology to 3D-quantify tooth wear progression in a patient over a period of 12 months. A calibrated stainless steel model was used to identify the accuracy of the scanning system by assessing the accuracy and precision of the contact scanner and the dimensional accuracy and stability of casts fabricated from three different types of impression materials. Thereafter, the overall accuracy of the 3D scanning system (scanner and casts) was ascertained. Clinically, polyether impressions were made of the patient's dentition at the initial examination and at the 12-month review, then poured in type IV dental stone to assess the tooth wear. The anterior teeth on the resultant casts were scanned, and images were analyzed using 3D matching software to detect dimensional variations between the patient's impressions. The accuracy of the 3D scanning system was established to be 33 μm. 3D clinical analysis demonstrated localized wear on the incisal and palatal surfaces of the patient's maxillary central incisors. The identified wear extended to a depth of 500 μm with a distribution of 4% to 7% of affected tooth surfaces. The newly developed 3D scanning methodology was found to be capable of assessing and accounting for the various factors affecting tooth wear scanning. Initial clinical evaluation of the methodology demonstrates successful monitoring of tooth wear progression. However, further clinical assessment is needed.

Fixed-Point Configurable Hardware Components

Directory of Open Access Journals (Sweden)

Rocher Romuald

2006-01-01

Full Text Available To reduce the gap between the VLSI technology capability and the designer productivity, design reuse based on IP (intellectual properties is commonly used. In terms of arithmetic accuracy, the generated architecture can generally only be configured through the input and output word lengths. In this paper, a new kind of method to optimize fixed-point arithmetic IP has been proposed. The architecture cost is minimized under accuracy constraints defined by the user. Our approach allows exploring the fixed-point search space and the algorithm-level search space to select the optimized structure and fixed-point specification. To significantly reduce the optimization and design times, analytical models are used for the fixed-point optimization process.

Diagnostic accuracy of surface coil MRI in assessing cartilaginous invasion in laryngeal tumours. Do we need contrast-agent administration?

International Nuclear Information System (INIS)

Preda, Lorenzo; Conte, Giorgio; Bonello, Luke; Giannitto, Caterina; Tagliabue, Elena; Raimondi, Sara; Ansarin, Mohssen; De Benedetto, Luigi; Cattaneo, Augusto; Maffini, Fausto; Bellomi, Massimo

2017-01-01

To assess the diagnostic accuracy of MRI performed using surface coils, with and without contrast medium, in predicting thyroid and cricoid cartilage infiltration in laryngeal tumours, and to investigate whether the radiologist's experience influences diagnostic accuracy. We retrospectively enrolled patients with biopsy-proven laryngeal cancer who had undergone preoperative staging MRI and open surgery. Two radiologists with different experience (senior vs. junior) reviewed the MR images without (session A1) and with contrast medium (session A2) separately. We calculated the accuracy of MRI with and without contrast medium in detecting infiltration of the thyroid and cricoid cartilages. Interobserver agreement was calculated by Cohen's Kappa (k). Forty-two patients were enrolled, for a total of 62 cartilages. In session A1 the senior and junior radiologists showed an accuracy of 85% and 71%, respectively, with k = 0.53 (0.33-0.72). In session A2 the senior and junior radiologists showed an accuracy of 84% and 77%, respectively, with k = 0.68 (0.49-0.86). Staging of laryngeal tumours with surface coil MRI showed good diagnostic accuracy in assessing cartilaginous infiltration. We observed similar values of diagnostic accuracy for the analysis performed with and without contrast medium for the senior radiologist. (orig.)

Diagnostic accuracy of surface coil MRI in assessing cartilaginous invasion in laryngeal tumours. Do we need contrast-agent administration?

Energy Technology Data Exchange (ETDEWEB)

Preda, Lorenzo [Universita degli Studi di Pavia, Department of Clinical-Surgical Diagnostic and Pediatric Sciences, Pavia (Italy); Division of Radiology, National Center of Oncological Hadrontherapy (CNAO Foundation), Pavia (Italy); Conte, Giorgio [Universita degli Studi di Milano, Postgraduation School in Radiodiagnostics, Milan (Italy); Bonello, Luke [Division of Radiology, Poliambulanza Hospital, Brescia (Italy); Giannitto, Caterina [European Institute of Oncology, Division of Radiology, Milan (Italy); Tagliabue, Elena; Raimondi, Sara [European Institute of Oncology, Division of Epidemiology and Biostatistics, Milan (Italy); Ansarin, Mohssen; De Benedetto, Luigi; Cattaneo, Augusto [European Institute of Oncology, Division of Head and Neck Surgery, Milan (Italy); Maffini, Fausto [European Institute of Oncology, Division of Pathology, Milan (Italy); Bellomi, Massimo [European Institute of Oncology, Division of Radiology, Milan (Italy); Universita degli Studi di Milano, Oncology and Haematology/Oncology Department, Milan (Italy)

2017-11-15

To assess the diagnostic accuracy of MRI performed using surface coils, with and without contrast medium, in predicting thyroid and cricoid cartilage infiltration in laryngeal tumours, and to investigate whether the radiologist's experience influences diagnostic accuracy. We retrospectively enrolled patients with biopsy-proven laryngeal cancer who had undergone preoperative staging MRI and open surgery. Two radiologists with different experience (senior vs. junior) reviewed the MR images without (session A1) and with contrast medium (session A2) separately. We calculated the accuracy of MRI with and without contrast medium in detecting infiltration of the thyroid and cricoid cartilages. Interobserver agreement was calculated by Cohen's Kappa (k). Forty-two patients were enrolled, for a total of 62 cartilages. In session A1 the senior and junior radiologists showed an accuracy of 85% and 71%, respectively, with k = 0.53 (0.33-0.72). In session A2 the senior and junior radiologists showed an accuracy of 84% and 77%, respectively, with k = 0.68 (0.49-0.86). Staging of laryngeal tumours with surface coil MRI showed good diagnostic accuracy in assessing cartilaginous infiltration. We observed similar values of diagnostic accuracy for the analysis performed with and without contrast medium for the senior radiologist. (orig.)

Eye Tracker Accuracy: Quantitative Evaluation of the Invisible Eye Center Location

OpenAIRE

Wyder, Stephan; Cattin, Philippe C.

2017-01-01

Purpose. We present a new method to evaluate the accuracy of an eye tracker based eye localization system. Measuring the accuracy of an eye tracker's primary intention, the estimated point of gaze, is usually done with volunteers and a set of fixation points used as ground truth. However, verifying the accuracy of the location estimate of a volunteer's eye center in 3D space is not easily possible. This is because the eye center is an intangible point hidden by the iris. Methods. We evaluate ...

The accuracy of Internet search engines to predict diagnoses from symptoms can be assessed with a validated scoring system.

Science.gov (United States)

Shenker, Bennett S

2014-02-01

To validate a scoring system that evaluates the ability of Internet search engines to correctly predict diagnoses when symptoms are used as search terms. We developed a five point scoring system to evaluate the diagnostic accuracy of Internet search engines. We identified twenty diagnoses common to a primary care setting to validate the scoring system. One investigator entered the symptoms for each diagnosis into three Internet search engines (Google, Bing, and Ask) and saved the first five webpages from each search. Other investigators reviewed the webpages and assigned a diagnostic accuracy score. They rescored a random sample of webpages two weeks later. To validate the five point scoring system, we calculated convergent validity and test-retest reliability using Kendall's W and Spearman's rho, respectively. We used the Kruskal-Wallis test to look for differences in accuracy scores for the three Internet search engines. A total of 600 webpages were reviewed. Kendall's W for the raters was 0.71 (psearch engines is a valid and reliable instrument. The scoring system may be used in future Internet research. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Improving Accuracy for Image Fusion in Abdominal Ultrasonography

Directory of Open Access Journals (Sweden)

Caroline Ewertsen

2012-08-01

Full Text Available Image fusion involving real-time ultrasound (US is a technique where previously recorded computed tomography (CT or magnetic resonance images (MRI are reformatted in a projection to fit the real-time US images after an initial co-registration. The co-registration aligns the images by means of common planes or points. We evaluated the accuracy of the alignment when varying parameters as patient position, respiratory phase and distance from the co-registration points/planes. We performed a total of 80 co-registrations and obtained the highest accuracy when the respiratory phase for the co-registration procedure was the same as when the CT or MRI was obtained. Furthermore, choosing co-registration points/planes close to the area of interest also improved the accuracy. With all settings optimized a mean error of 3.2 mm was obtained. We conclude that image fusion involving real-time US is an accurate method for abdominal examinations and that the accuracy is influenced by various adjustable factors that should be kept in mind.

Diagnostic accuracy in virtual dermatopathology

DEFF Research Database (Denmark)

Mooney, E.; Kempf, W.; Jemec, G.B.E.

2012-01-01

Background Virtual microscopy is used for teaching medical students and residents and for in-training and certification examinations in the United States. However, no existing studies compare diagnostic accuracy using virtual slides and photomicrographs. The objective of this study was to compare...... diagnostic accuracy of dermatopathologists and pathologists using photomicrographs vs. digitized images, through a self-assessment examination, and to elucidate assessment of virtual dermatopathology. Methods Forty-five dermatopathologists and pathologists received a randomized combination of 15 virtual...... slides and photomicrographs with corresponding clinical photographs and information in a self-assessment examination format. Descriptive data analysis and comparison of groups were performed using a chi-square test. Results Diagnostic accuracy in dermatopathology using virtual dermatopathology...

Assessing the Accuracy of MODIS-NDVI Derived Land-Cover Across the Great Lakes Basin

Science.gov (United States)

This research describes the accuracy assessment process for a land-cover dataset developed for the Great Lakes Basin (GLB). This land-cover dataset was developed from the 2007 MODIS Normalized Difference Vegetation Index (NDVI) 16-day composite (MOD13Q) 250 m time-series data. Tr...

COMPARISON OF UAS-BASED PHOTOGRAMMETRY SOFTWARE FOR 3D POINT CLOUD GENERATION: A SURVEY OVER A HISTORICAL SITE

Directory of Open Access Journals (Sweden)

F. Alidoost

2017-11-01

Full Text Available Nowadays, Unmanned Aerial System (UAS-based photogrammetry offers an affordable, fast and effective approach to real-time acquisition of high resolution geospatial information and automatic 3D modelling of objects for numerous applications such as topography mapping, 3D city modelling, orthophoto generation, and cultural heritages preservation. In this paper, the capability of four different state-of-the-art software packages as 3DSurvey, Agisoft Photoscan, Pix4Dmapper Pro and SURE is examined to generate high density point cloud as well as a Digital Surface Model (DSM over a historical site. The main steps of this study are including: image acquisition, point cloud generation, and accuracy assessment. The overlapping images are first captured using a quadcopter and next are processed by different software to generate point clouds and DSMs. In order to evaluate the accuracy and quality of point clouds and DSMs, both visual and geometric assessments are carry out and the comparison results are reported.

Comparison of Uas-Based Photogrammetry Software for 3d Point Cloud Generation: a Survey Over a Historical Site

Science.gov (United States)

Alidoost, F.; Arefi, H.

2017-11-01

Nowadays, Unmanned Aerial System (UAS)-based photogrammetry offers an affordable, fast and effective approach to real-time acquisition of high resolution geospatial information and automatic 3D modelling of objects for numerous applications such as topography mapping, 3D city modelling, orthophoto generation, and cultural heritages preservation. In this paper, the capability of four different state-of-the-art software packages as 3DSurvey, Agisoft Photoscan, Pix4Dmapper Pro and SURE is examined to generate high density point cloud as well as a Digital Surface Model (DSM) over a historical site. The main steps of this study are including: image acquisition, point cloud generation, and accuracy assessment. The overlapping images are first captured using a quadcopter and next are processed by different software to generate point clouds and DSMs. In order to evaluate the accuracy and quality of point clouds and DSMs, both visual and geometric assessments are carry out and the comparison results are reported.

Assessing sensor accuracy for non-adjunct use of continuous glucose monitoring.

Science.gov (United States)

Kovatchev, Boris P; Patek, Stephen D; Ortiz, Edward Andrew; Breton, Marc D

2015-03-01

The level of continuous glucose monitoring (CGM) accuracy needed for insulin dosing using sensor values (i.e., the level of accuracy permitting non-adjunct CGM use) is a topic of ongoing debate. Assessment of this level in clinical experiments is virtually impossible because the magnitude of CGM errors cannot be manipulated and related prospectively to clinical outcomes. A combination of archival data (parallel CGM, insulin pump, self-monitoring of blood glucose [SMBG] records, and meals for 56 pump users with type 1 diabetes) and in silico experiments was used to "replay" real-life treatment scenarios and relate sensor error to glycemic outcomes. Nominal blood glucose (BG) traces were extracted using a mathematical model, yielding 2,082 BG segments each initiated by insulin bolus and confirmed by SMBG. These segments were replayed at seven sensor accuracy levels (mean absolute relative differences [MARDs] of 3-22%) testing six scenarios: insulin dosing using sensor values, threshold, and predictive alarms, each without or with considering CGM trend arrows. In all six scenarios, the occurrence of hypoglycemia (frequency of BG levels ≤50 mg/dL and BG levels ≤39 mg/dL) increased with sensor error, displaying an abrupt slope change at MARD =10%. Similarly, hyperglycemia (frequency of BG levels ≥250 mg/dL and BG levels ≥400 mg/dL) increased and displayed an abrupt slope change at MARD=10%. When added to insulin dosing decisions, information from CGM trend arrows, threshold, and predictive alarms resulted in improvement in average glycemia by 1.86, 8.17, and 8.88 mg/dL, respectively. Using CGM for insulin dosing decisions is feasible below a certain level of sensor error, estimated in silico at MARD=10%. In our experiments, further accuracy improvement did not contribute substantively to better glycemic outcomes.

Accuracy Assessment of Digital Surface Models Based on WorldView-2 and ADS80 Stereo Remote Sensing Data

Directory of Open Access Journals (Sweden)

Christian Ginzler

2012-05-01

Full Text Available Digital surface models (DSMs are widely used in forest science to model the forest canopy. Stereo pairs of very high resolution satellite and digital aerial images are relatively new and their absolute accuracy for DSM generation is largely unknown. For an assessment of these input data two DSMs based on a WorldView-2 stereo pair and a ADS80 DSM were generated with photogrammetric instruments. Rational polynomial coefficients (RPCs are defining the orientation of the WorldView-2 satellite images, which can be enhanced with ground control points (GCPs. Thus two WorldView-2 DSMs were distinguished: a WorldView-2 RPCs-only DSM and a WorldView-2 GCP-enhanced RPCs DSM. The accuracy of the three DSMs was estimated with GPS measurements, manual stereo-measurements, and airborne laser scanning data (ALS. With GCP-enhanced RPCs the WorldView-2 image orientation could be optimised to a root mean square error (RMSE of 0.56 m in planimetry and 0.32 m in height. This improvement in orientation allowed for a vertical median error of −0.24 m for the WorldView-2 GCP-enhanced RPCs DSM in flat terrain. Overall, the DSM based on ADS80 images showed the highest accuracy of the three models with a median error of 0.08 m over bare ground. As the accuracy of a DSM varies with land cover three classes were distinguished: herb and grass, forests, and artificial areas. The study suggested the ADS80 DSM to best model actual surface height in all three land cover classes, with median errors < 1.1 m. The WorldView-2 GCP-enhanced RPCs model achieved good accuracy, too, with median errors of −0.43 m for the herb and grass vegetation and −0.26 m for artificial areas. Forested areas emerged as the most difficult land cover type for height modelling; still, with median errors of −1.85 m for the WorldView-2 GCP-enhanced RPCs model and −1.12 m for the ADS80 model, the input data sets evaluated here are quite promising for forest canopy modelling.

Determining the cut-off point of osteoporosis based on the osteoporosis self-assessment tool, body mass index and weight in Taiwanese young adult women.

Science.gov (United States)

Chang, Shu Fang; Yang, Rong Sen

2014-09-01

To examine the cut-off point of the osteoporosis self-assessment tool, age, weight and body mass index for osteoporosis among young adult Taiwanese women, using a large-scale health examination database containing bone mineral density tests. The cut-off points of osteoporosis risk factors identified earlier focus on menopausal or senior Caucasian and Asian women. However, young adult Asian women have seldom been identified. A retrospective historical cohort study. Using the 2009-2011 health examination database of a large-scale medical centre in northern Taiwan, this study investigated young adult Asian women (i.e. range in age from 30-49 years) in Taiwan who had received dual-energy X-ray absorptiometry test. This study also explored the cut-off point, sensitivity, specificity and diagnostic accuracy of receiver operating characteristics of osteoporosis among young adult females in Taiwan. This study collected 2454 young adult Asian women in Taiwan. Cochran-Armitage analysis results indicated that the prevalence of osteoporosis increased with decreasing weight, body mass index and osteoporosis self-assessment method quartiles. According to the results of receiver operating characteristics, weight, body mass index and osteoporosis self-assessment tool approaches can generally be used as indicators to predict osteoporosis among young adult Asian women. Results of this study demonstrate that Taiwanese women contracting osteoporosis tend to be young and underweight, as well as having a low body mass index and osteoporosis self-assessment scores. Those results further suggest that the assessment indicators for cut-off points are appropriately suitable for young adult women in Taiwan. Early detection is the only available means of preventing osteoporosis. Professional nurses should apply convenient and accurate assessment procedures to help young adult women to adopt preventive strategies against osteoporosis early, thus eliminating the probability of osteoporotic

Evaluating the effect of learning style and student background on self-assessment accuracy

Science.gov (United States)

Alaoutinen, Satu

2012-06-01

This study evaluates a new taxonomy-based self-assessment scale and examines factors that affect assessment accuracy and course performance. The scale is based on Bloom's Revised Taxonomy and is evaluated by comparing students' self-assessment results with course performance in a programming course. Correlation has been used to reveal possible connections between student information and both self-assessment and course performance. The results show that students can place their knowledge along the taxonomy-based scale quite well and the scale seems to fit engineering students' learning style. Advanced students assess themselves more accurately than novices. The results also show that reflective students were better in programming than active. The scale used in this study gives a more objective picture of students' knowledge than general scales and with modifications it can be used in other classes than programming.

Hematocrit correction does not improve glucose monitor accuracy in the assessment of neonatal hypoglycemia.

Science.gov (United States)

Wang, Li; Sievenpiper, John L; de Souza, Russell J; Thomaz, Michele; Blatz, Susan; Grey, Vijaylaxmi; Fusch, Christoph; Balion, Cynthia

2013-08-01

The lack of accuracy of point of care (POC) glucose monitors has limited their use in the diagnosis of neonatal hypoglycemia. Hematocrit plays an important role in explaining discordant results. The objective of this study was to to assess the effect of hematocrit on the diagnostic performance of Abbott Precision Xceed Pro (PXP) and Nova StatStrip (StatStrip) monitors in neonates. All blood samples ordered for laboratory glucose measurement were analyzed using the PXP and StatStrip and compared with the laboratory analyzer (ABL 800 Blood Gas analyzer [ABL]). Acceptable error targets were ±15% for glucose monitoring and ±5% for diagnosis. A total of 307 samples from 176 neonates were analyzed. Overall, 90% of StatStrip and 75% of PXP values met the 15% error limit and 45% of StatStrip and 32% of PXP values met the 5% error limit. At glucose concentrations ≤4 mmol/L, 83% of StatStrip and 79% of PXP values met the 15% error limit, while 37% of StatStrip and 38% of PXP values met the 5% error limit. Hematocrit explained 7.4% of the difference between the PXP and ABL whereas it accounted for only 0.09% of the difference between the StatStrip and ABL. The ROC analysis showed the screening cut point with the best performance for identifying neonatal hypoglycemia was 3.2 mmol/L for StatStrip and 3.3 mmol/L for PXP. Despite a negligible hematocrit effect for the StatStrip, it did not achieve recommended error limits. The StatStrip and PXP glucose monitors remain suitable only for neonatal hypoglycemia screening with confirmation required from a laboratory analyzer.

A critical analysis of the tender points in fibromyalgia.

Science.gov (United States)

Harden, R Norman; Revivo, Gadi; Song, Sharon; Nampiaparampil, Devi; Golden, Gary; Kirincic, Marie; Houle, Timothy T

2007-03-01

To pilot methodologies designed to critically assess the American College of Rheumatology's (ACR) diagnostic criteria for fibromyalgia. Prospective, psychophysical testing. An urban teaching hospital. Twenty-five patients with fibromyalgia and 31 healthy controls (convenience sample). Pressure pain threshold was determined at the 18 ACR tender points and five sham points using an algometer (dolorimeter). The patients "algometric total scores" (sums of the patients' average pain thresholds at the 18 tender points) were derived, as well as pain thresholds across sham points. The "algometric total score" could differentiate patients with fibromyalgia from normals with an accuracy of 85.7% (P pain across sham points than across ACR tender points, sham points also could be used for diagnosis (85.7%; Ps tested vs other painful conditions. The points specified by the ACR were only modestly superior to sham points in making the diagnosis. Most importantly, this pilot suggests single points, smaller groups of points, or sham points may be as effective in diagnosing fibromyalgia as the use of all 18 points, and suggests methodologies to definitively test that hypothesis.

A point of application study to determine the accuracy, precision and reliability of a low-cost balance plate for center of pressure measurement.

Science.gov (United States)

Goble, Daniel J; Khan, Ehran; Baweja, Harsimran S; O'Connor, Shawn M

2018-04-11

Changes in postural sway measured via force plate center of pressure have been associated with many aspects of human motor ability. A previous study validated the accuracy and precision of a relatively new, low-cost and portable force plate called the Balance Tracking System (BTrackS). This work compared a laboratory-grade force plate versus BTrackS during human-like dynamic sway conditions generated by an inverted pendulum device. The present study sought to extend previous validation attempts for BTrackS using a more traditional point of application (POA) approach. Computer numerical control (CNC) guided application of ∼155 N of force was applied five times to each of 21 points on five different BTrackS Balance Plate (BBP) devices with a hex-nose plunger. Results showed excellent agreement (ICC > 0.999) between the POAs and measured COP by the BBP devices, as well as high accuracy ( 0.999) providing evidence of almost perfect inter-device reliability. Taken together, these results provide an important, static corollary to the previously obtained dynamic COP results from inverted pendulum testing of the BBP. Copyright © 2018 Elsevier Ltd. All rights reserved.

Accuracy assessment of an industrial actuator

DEFF Research Database (Denmark)

Dalla Costa, Giuseppe; Genta, Gianfranco; Barbato, Giulio

2016-01-01

A commercial linear actuator equipped with a 0.1 μm resolution encoder was used as a contact displacement sensor with adjustable force. The accuracy of the position reading of the actuator was evaluated from experimental data taking into account the uncertainty contributions. The tests consisted ...

Assessing the accuracy of different simplified frictional rolling contact algorithms

Science.gov (United States)

Vollebregt, E. A. H.; Iwnicki, S. D.; Xie, G.; Shackleton, P.

2012-01-01

This paper presents an approach for assessing the accuracy of different frictional rolling contact theories. The main characteristic of the approach is that it takes a statistically oriented view. This yields a better insight into the behaviour of the methods in diverse circumstances (varying contact patch ellipticities, mixed longitudinal, lateral and spin creepages) than is obtained when only a small number of (basic) circumstances are used in the comparison. The range of contact parameters that occur for realistic vehicles and tracks are assessed using simulations with the Vampire vehicle system dynamics (VSD) package. This shows that larger values for the spin creepage occur rather frequently. Based on this, our approach is applied to typical cases for which railway VSD packages are used. The results show that particularly the USETAB approach but also FASTSIM give considerably better results than the linear theory, Vermeulen-Johnson, Shen-Hedrick-Elkins and Polach methods, when compared with the 'complete theory' of the CONTACT program.

Trait Perception Accuracy and Acquaintance Within Groups: Tracking Accuracy Development.

Science.gov (United States)

Brown, Jill A; Bernieri, Frank

2017-05-01

Previous work on trait perception has evaluated accuracy at discrete stages of relationships (e.g., strangers, best friends). A relatively limited body of literature has investigated changes in accuracy as acquaintance within a dyad or group increases. Small groups of initially unacquainted individuals spent more than 30 hr participating in a wide range of activities designed to represent common interpersonal contexts (e.g., eating, traveling). We calculated how accurately each participant judged others in their group on the big five traits across three distinct points within the acquaintance process: zero acquaintance, after a getting-to-know-you conversation, and after 10 weeks of interaction and activity. Judgments of all five traits exhibited accuracy above chance levels after 10 weeks. An examination of the trait rating stability revealed that much of the revision in judgments occurred not over the course of the 10-week relationship as suspected, but between zero acquaintance and the getting-to-know-you conversation.

Quantitative modeling of the accuracy in registering preoperative patient-specific anatomic models into left atrial cardiac ablation procedures

Energy Technology Data Exchange (ETDEWEB)

Rettmann, Maryam E., E-mail: rettmann.maryam@mayo.edu; Holmes, David R.; Camp, Jon J.; Cameron, Bruce M.; Robb, Richard A. [Biomedical Imaging Resource, Mayo Clinic College of Medicine, Rochester, Minnesota 55905 (United States); Kwartowitz, David M. [Department of Bioengineering, Clemson University, Clemson, South Carolina 29634 (United States); Gunawan, Mia [Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington D.C. 20057 (United States); Johnson, Susan B.; Packer, Douglas L. [Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905 (United States); Dalegrave, Charles [Clinical Cardiac Electrophysiology, Cardiology Division Hospital Sao Paulo, Federal University of Sao Paulo, 04024-002 Brazil (Brazil); Kolasa, Mark W. [David Grant Medical Center, Fairfield, California 94535 (United States)

2014-02-15

Purpose: In cardiac ablation therapy, accurate anatomic guidance is necessary to create effective tissue lesions for elimination of left atrial fibrillation. While fluoroscopy, ultrasound, and electroanatomic maps are important guidance tools, they lack information regarding detailed patient anatomy which can be obtained from high resolution imaging techniques. For this reason, there has been significant effort in incorporating detailed, patient-specific models generated from preoperative imaging datasets into the procedure. Both clinical and animal studies have investigated registration and targeting accuracy when using preoperative models; however, the effect of various error sources on registration accuracy has not been quantitatively evaluated. Methods: Data from phantom, canine, and patient studies are used to model and evaluate registration accuracy. In the phantom studies, data are collected using a magnetically tracked catheter on a static phantom model. Monte Carlo simulation studies were run to evaluate both baseline errors as well as the effect of different sources of error that would be present in a dynamicin vivo setting. Error is simulated by varying the variance parameters on the landmark fiducial, physical target, and surface point locations in the phantom simulation studies. In vivo validation studies were undertaken in six canines in which metal clips were placed in the left atrium to serve as ground truth points. A small clinical evaluation was completed in three patients. Landmark-based and combined landmark and surface-based registration algorithms were evaluated in all studies. In the phantom and canine studies, both target registration error and point-to-surface error are used to assess accuracy. In the patient studies, no ground truth is available and registration accuracy is quantified using point-to-surface error only. Results: The phantom simulation studies demonstrated that combined landmark and surface-based registration improved

Diagnostic accuracy of the STRATIFY clinical prediction rule for falls: A systematic review and meta-analysis

LENUS (Irish Health Repository)

Billington, Jennifer

2012-08-07

AbstractBackgroundThe STRATIFY score is a clinical prediction rule (CPR) derived to assist clinicians to identify patients at risk of falling. The purpose of this systematic review and meta-analysis is to determine the overall diagnostic accuracy of the STRATIFY rule across a variety of clinical settings.MethodsA literature search was performed to identify all studies that validated the STRATIFY rule. The methodological quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. A STRATIFY score of ≥2 points was used to identify individuals at higher risk of falling. All included studies were combined using a bivariate random effects model to generate pooled sensitivity and specificity of STRATIFY at ≥2 points. Heterogeneity was assessed using the variance of logit transformed sensitivity and specificity.ResultsSeventeen studies were included in our meta-analysis, incorporating 11,378 patients. At a score ≥2 points, the STRATIFY rule is more useful at ruling out falls in those classified as low risk, with a greater pooled sensitivity estimate (0.67, 95% CI 0.52–0.80) than specificity (0.57, 95% CI 0.45 – 0.69). The sensitivity analysis which examined the performance of the rule in different settings and subgroups also showed broadly comparable results, indicating that the STRATIFY rule performs in a similar manner across a variety of different ‘at risk’ patient groups in different clinical settings.ConclusionThis systematic review shows that the diagnostic accuracy of the STRATIFY rule is limited and should not be used in isolation for identifying individuals at high risk of falls in clinical practice.

AN ACCURACY ASSESSMENT OF GEOREFERENCED POINT CLOUDS PRODUCED VIA MULTI-VIEW STEREO TECHNIQUES APPLIED TO IMAGERY ACQUIRED VIA UNMANNED AERIAL VEHICLE

Directory of Open Access Journals (Sweden)

S. Harwin

2012-08-01

Full Text Available Low-cost Unmanned Aerial Vehicles (UAVs are becoming viable environmental remote sensing tools. Sensor and battery technology is expanding the data capture opportunities. The UAV, as a close range remote sensing platform, can capture high resolution photography on-demand. This imagery can be used to produce dense point clouds using multi-view stereopsis techniques (MVS combining computer vision and photogrammetry. This study examines point clouds produced using MVS techniques applied to UAV and terrestrial photography. A multi-rotor micro UAV acquired aerial imagery from a altitude of approximately 30–40 m. The point clouds produced are extremely dense (<1–3 cm point spacing and provide a detailed record of the surface in the study area, a 70 m section of sheltered coastline in southeast Tasmania. Areas with little surface texture were not well captured, similarly, areas with complex geometry such as grass tussocks and woody scrub were not well mapped. The process fails to penetrate vegetation, but extracts very detailed terrain in unvegetated areas. Initially the point clouds are in an arbitrary coordinate system and need to be georeferenced. A Helmert transformation is applied based on matching ground control points (GCPs identified in the point clouds to GCPs surveying with differential GPS. These point clouds can be used, alongside laser scanning and more traditional techniques, to provide very detailed and precise representations of a range of landscapes at key moments. There are many potential applications for the UAV-MVS technique, including coastal erosion and accretion monitoring, mine surveying and other environmental monitoring applications. For the generated point clouds to be used in spatial applications they need to be converted to surface models that reduce dataset size without loosing too much detail. Triangulated meshes are one option, another is Poisson Surface Reconstruction. This latter option makes use of point normal

COMPARATIVE ACCURACY EVALUATION OF FINE-SCALE GLOBAL AND LOCAL DIGITAL SURFACE MODELS: THE TSHWANE CASE STUDY I

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A. Breytenbach

2016-10-01

Full Text Available 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.

Analysis of parameters for technological equipment of parallel kinematics based on rods of variable length for processing accuracy assurance

Science.gov (United States)

Koltsov, A. G.; Shamutdinov, A. H.; Blokhin, D. A.; Krivonos, E. V.

2018-01-01

A new classification of parallel kinematics mechanisms on symmetry coefficient, being proportional to mechanism stiffness and accuracy of the processing product using the technological equipment under study, is proposed. A new version of the Stewart platform with a high symmetry coefficient is presented for analysis. The workspace of the mechanism under study is described, this space being a complex solid figure. The workspace end points are reached by the center of the mobile platform which moves in parallel related to the base plate. Parameters affecting the processing accuracy, namely the static and dynamic stiffness, natural vibration frequencies are determined. The capability assessment of the mechanism operation under various loads, taking into account resonance phenomena at different points of the workspace, was conducted. The study proved that stiffness and therefore, processing accuracy with the use of the above mentioned mechanisms are comparable with the stiffness and accuracy of medium-sized series-produced machines.

Maximum Attainable Accuracy of Inexact Saddle Point Solvers

Czech Academy of Sciences Publication Activity Database

Jiránek, P.; Rozložník, Miroslav

2008-01-01

Roč. 29, č. 4 (2008), s. 1297-1321 ISSN 0895-4798 R&D Projects: GA MŠk 1M0554; GA AV ČR 1ET400300415 Institutional research plan: CEZ:AV0Z10300504 Keywords : saddle point problems * Schur complement reduction * null-space projection method * rounding error analysis Subject RIV: BA - General Mathematics Impact factor: 1.328, year: 2008

Assessing the Accuracy and Readability of Online Health Information for Patients With Pancreatic Cancer.

Science.gov (United States)

Storino, Alessandra; Castillo-Angeles, Manuel; Watkins, Ammara A; Vargas, Christina; Mancias, Joseph D; Bullock, Andrea; Demirjian, Aram; Moser, A James; Kent, Tara S

2016-09-01

The degree to which patients are empowered by written educational materials depends on the text's readability level and the accuracy of the information provided. The association of a website's affiliation or focus on treatment modality with its readability and accuracy has yet to be thoroughly elucidated. To compare the readability and accuracy of patient-oriented online resources for pancreatic cancer by treatment modality and website affiliation. An online search of 50 websites discussing 5 pancreatic cancer treatment modalities (alternative therapy, chemotherapy, clinical trials, radiation therapy, and surgery) was conducted. The website's affiliation was identified. Readability was measured by 9 standardized tests, and accuracy was assessed by an expert panel. Nine standardized tests were used to compute the median readability level of each website. The median readability scores were compared among treatment modality and affiliation categories. Accuracy was determined by an expert panel consisting of 2 medical specialists and 2 surgical specialists. The 4 raters independently evaluated all websites belonging to the 5 treatment modalities (a score of 1 indicates that readability and accuracy based on the focus of the treatment modality and the website's affiliation. Websites discussing surgery (with a median readability level of 13.7 and an interquartile range [IQR] of 11.9-15.6) were easier to read than those discussing radiotherapy (median readability level, 15.2 [IQR, 13.0-17.0]) (P = .003) and clinical trials (median readability level, 15.2 [IQR, 12.8-17.0]) (P = .002). Websites of nonprofit organizations (median readability level, 12.9 [IQR, 11.2-15.0]) were easier to read than media (median readability level, 16.0 [IQR, 13.4-17.0]) (P readability level, 14.8 [IQR, 12.9-17.0]) (P readability level, 14.0 [IQR, 12.1-16.1]) were easier to read than media websites (P = .001). Among treatment modalities, alternative therapy websites exhibited the

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Guguan, Marianas in 2011

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Aguijan, Marianas in 2011

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Saipan, Marianas in 2011

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Guam, Marianas in 2011

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

Diagnostic accuracy of the MMPI-2 to assess imbalances emphasising in people with substance dependence

Directory of Open Access Journals (Sweden)

Pablo González-Romero

2017-07-01

Full Text Available The acceptance and respect of the rules governing society and the family unit are essential pillars for the development of a therapeutic program for people with substance dependence disorders. This study proposes a double objective using the scales of the MMPI-2 detectors of mismatches emphasising: what information can provide and what the diagnostic accuracy of the MMPI-2 is to assess these mismatches. As a reference, psychopathic deviation (Pd, social introversion (Si, antisocial practices (ASP, social responsibility (Re, social unrest (SOD, introversion/low positive emotion (PSY-INTR, family problems (FAM, and conjugal stress (MDS were taken. Of the 226 participants, 113 are people with substance dependence and 113 have no dependence or any pathology. Their differences and diagnostic accuracy through the ROC curve were analysed. The results showed different contribution and diagnostic accuracy of the scales.

A highly accurate algorithm for the solution of the point kinetics equations

International Nuclear Information System (INIS)

Ganapol, B.D.

2013-01-01

Highlights: • Point kinetics equations for nuclear reactor transient analysis are numerically solved to extreme accuracy. • Results for classic benchmarks found in the literature are given to 9-digit accuracy. • Recent results of claimed accuracy are shown to be less accurate than claimed. • Arguably brings a chapter of numerical evaluation of the PKEs to a close. - Abstract: Attempts to resolve the point kinetics equations (PKEs) describing nuclear reactor transients have been the subject of numerous articles and texts over the past 50 years. Some very innovative methods, such as the RTS (Reactor Transient Simulation) and CAC (Continuous Analytical Continuation) methods of G.R. Keepin and J. Vigil respectively, have been shown to be exceptionally useful. Recently however, several authors have developed methods they consider accurate without a clear basis for their assertion. In response, this presentation will establish a definitive set of benchmarks to enable those developing PKE methods to truthfully assess the degree of accuracy of their methods. Then, with these benchmarks, two recently published methods, found in this journal will be shown to be less accurate than claimed and a legacy method from 1984 will be confirmed

Accuracy of Assessment of Eligibility for Early Medical Abortion by Community Health Workers in Ethiopia, India and South Africa.

Science.gov (United States)

Johnston, Heidi Bart; Ganatra, Bela; Nguyen, My Huong; Habib, Ndema; Afework, Mesganaw Fantahun; Harries, Jane; Iyengar, Kirti; Moodley, Jennifer; Lema, Hailu Yeneneh; Constant, Deborah; Sen, Swapnaleen

2016-01-01

To assess the accuracy of assessment of eligibility for early medical abortion by community health workers using a simple checklist toolkit. Diagnostic accuracy study. Ethiopia, India and South Africa. Two hundred seventeen women in Ethiopia, 258 in India and 236 in South Africa were enrolled into the study. A checklist toolkit to determine eligibility for early medical abortion was validated by comparing results of clinician and community health worker assessment of eligibility using the checklist toolkit with the reference standard exam. Accuracy was over 90% and the negative likelihood ratio India and 6.3 in South Africa. When used by community health workers the overall accuracy of the toolkit was 92% in Ethiopia, 80% in India and 77% in South Africa negative likelihood ratios were 0.08 in Ethiopia, 0.25 in India and 0.22 in South Africa and positive likelihood ratios were 5.9 in Ethiopia and 2.0 in India and South Africa. The checklist toolkit, as used by clinicians, was excellent at ruling out participants who were not eligible, and moderately effective at ruling in participants who were eligible for medical abortion. Results were promising when used by community health workers particularly in Ethiopia where they had more prior experience with use of diagnostic aids and longer professional training. The checklist toolkit assessments resulted in some participants being wrongly assessed as eligible for medical abortion which is an area of concern. Further research is needed to streamline the components of the tool, explore optimal duration and content of training for community health workers, and test feasibility and acceptability.

Accuracy Evaluation of a Stereolithographic Surgical Template for Dental Implant Insertion Using 3D Superimposition Protocol

Directory of Open Access Journals (Sweden)

Corina Marilena Cristache

2017-01-01

Full Text Available The aim of this study was to evaluate the accuracy of a stereolithographic template, with sleeve structure incorporated into the design, for computer-guided dental implant insertion in partially edentulous patients. Materials and Methods. Sixty-five implants were placed in twenty-five consecutive patients with a stereolithographic surgical template. After surgery, digital impression was taken and 3D inaccuracy of implants position at entry point, apex, and angle deviation was measured using an inspection tool software. Mann–Whitney U test was used to compare accuracy between maxillary and mandibular surgical guides. A p value < .05 was considered significant. Results. Mean (and standard deviation of 3D error at the entry point was 0.798 mm (±0.52, at the implant apex it was 1.17 mm (±0.63, and mean angular deviation was 2.34 (±0.85. A statistically significant reduced 3D error was observed at entry point p=.037, at implant apex p=.008, and also in angular deviation p=.030 in mandible when comparing to maxilla. Conclusions. The surgical template used has proved high accuracy for implant insertion. Within the limitations of the present study, the protocol for comparing a digital file (treatment plan with postinsertion digital impression may be considered a useful procedure for assessing surgical template accuracy, avoiding radiation exposure, during postoperative CBCT scanning.

The accuracy and reproducibility of video assessment in the pitch-side management of concussion in elite rugby.

Science.gov (United States)

Fuller, G W; Kemp, S P T; Raftery, M

2017-03-01

To investigate the accuracy and reliability of side-line video review of head impact events to aid identification of concussion in elite sport. Diagnostic accuracy and inter-rater agreement study. Immediate care, match day and team doctors involved in the 2015 Rugby Union World Cup viewed 20 video clips showing broadcaster's footage of head impact events occurring during elite Rugby matches. Subjects subsequently recorded whether any criteria warranting permanent removal from play or medical room head injury assessment were present. The accuracy of these ratings were compared to consensus expert opinion by calculating mean sensitivity and specificity across raters. The reproducibility of doctor's decisions was additionally assessed using raw agreement and Gwets AC1 chance corrected agreement coefficient. Forty rugby medicine doctors were included in the study. Compared to the expert reference standard overall sensitivity and specificity of doctors decisions were 77.5% (95% CI 73.1-81.5%) and 53.3% (95% CI 48.2-58.2%) respectively. Overall there was raw agreement of 67.8% (95% CI 57.9-77.7%) between doctors across all video clips. Chance corrected Gwets AC1 agreement coefficient was 0.39 (95% CI 0.17-0.62), indicating fair agreement. Rugby World Cup doctors' demonstrated moderate accuracy and fair reproducibility in head injury event decision making when assessing video clips of head impact events. The use of real-time video may improve the identification, decision making and management of concussion in elite sports. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

MIN-CUT BASED SEGMENTATION OF AIRBORNE LIDAR POINT CLOUDS

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S. Ural

2012-07-01

Full Text Available Introducing an organization to the unstructured point cloud before extracting information from airborne lidar data is common in many applications. Aggregating the points with similar features into segments in 3-D which comply with the nature of actual objects is affected by the neighborhood, scale, features and noise among other aspects. In this study, we present a min-cut based method for segmenting the point cloud. We first assess the neighborhood of each point in 3-D by investigating the local geometric and statistical properties of the candidates. Neighborhood selection is essential since point features are calculated within their local neighborhood. Following neighborhood determination, we calculate point features and determine the clusters in the feature space. We adapt a graph representation from image processing which is especially used in pixel labeling problems and establish it for the unstructured 3-D point clouds. The edges of the graph that are connecting the points with each other and nodes representing feature clusters hold the smoothness costs in the spatial domain and data costs in the feature domain. Smoothness costs ensure spatial coherence, while data costs control the consistency with the representative feature clusters. This graph representation formalizes the segmentation task as an energy minimization problem. It allows the implementation of an approximate solution by min-cuts for a global minimum of this NP hard minimization problem in low order polynomial time. We test our method with airborne lidar point cloud acquired with maximum planned post spacing of 1.4 m and a vertical accuracy 10.5 cm as RMSE. We present the effects of neighborhood and feature determination in the segmentation results and assess the accuracy and efficiency of the implemented min-cut algorithm as well as its sensitivity to the parameters of the smoothness and data cost functions. We find that smoothness cost that only considers simple distance

Assessing the accuracy and stability of variable selection methods for random forest modeling in ecology.

Science.gov (United States)

Fox, Eric W; Hill, Ryan A; Leibowitz, Scott G; Olsen, Anthony R; Thornbrugh, Darren J; Weber, Marc H

2017-07-01

Random forest (RF) modeling has emerged as an important statistical learning method in ecology due to its exceptional predictive performance. However, for large and complex ecological data sets, there is limited guidance on variable selection methods for RF modeling. Typically, either a preselected set of predictor variables are used or stepwise procedures are employed which iteratively remove variables according to their importance measures. This paper investigates the application of variable selection methods to RF models for predicting probable biological stream condition. Our motivating data set consists of the good/poor condition of n = 1365 stream survey sites from the 2008/2009 National Rivers and Stream Assessment, and a large set (p = 212) of landscape features from the StreamCat data set as potential predictors. We compare two types of RF models: a full variable set model with all 212 predictors and a reduced variable set model selected using a backward elimination approach. We assess model accuracy using RF's internal out-of-bag estimate, and a cross-validation procedure with validation folds external to the variable selection process. We also assess the stability of the spatial predictions generated by the RF models to changes in the number of predictors and argue that model selection needs to consider both accuracy and stability. The results suggest that RF modeling is robust to the inclusion of many variables of moderate to low importance. We found no substantial improvement in cross-validated accuracy as a result of variable reduction. Moreover, the backward elimination procedure tended to select too few variables and exhibited numerous issues such as upwardly biased out-of-bag accuracy estimates and instabilities in the spatial predictions. We use simulations to further support and generalize results from the analysis of real data. A main purpose of this work is to elucidate issues of model selection bias and instability to ecologists interested in

Evaluating horizontal positional accuracy of low-cost UAV orthomosaics over forest terrain using ground control points extracted from different sources

Science.gov (United States)

Patias, Petros; Giagkas, Fotis; Georgiadis, Charalampos; Mallinis, Giorgos; Kaimaris, Dimitris; Tsioukas, Vassileios

2017-09-01

Within the field of forestry, forest road mapping and inventory plays an important role in management activities related to wood harvesting industry, sentiment and water run-off modelling, biodiversity distribution and ecological connectivity, recreation activities, future planning of forest road networks and wildfire protection and fire-fighting. Especially in countries of the Mediterranean Rim, knowledge at regional and national scales regarding the distribution and the characteristics of rural and forest road network is essential in order to ensure an effective emergency management and rapid response of the fire-fighting mechanism. Yet, the absence of accurate and updated geodatabases and the drawbacks related to the use of traditional cartographic methods arising from the forest environment settings, and the cost and efforts needed, as thousands of meters need to be surveyed per site, trigger the need for new data sources and innovative mapping approaches. Monitoring the condition of unpaved forest roads with unmanned aerial vehicle technology is an attractive option for substituting objective, laboursome surveys. Although photogrammetric processing of UAV imagery can achieve accuracy of 1-2 centimeters and dense point clouds, the process is commonly based on the establishment of control points. In the case of forest road networks, which are linear features, there is a need for a great number of control points. Our aim is to evaluate low-cost UAV orthoimages generated over forest areas with GCP's captured from existing national scale aerial orthoimagery, satellite imagery available through a web mapping service (WMS), field surveys using Mobile Mapping System and GNSS receiver. We also explored the direct georeferencing potential through the GNSS onboard the low cost UAV. The results suggest that the GNSS approach proved to most accurate, while the positional accuracy derived using the WMS and the aerial orthoimagery datasets deemed satisfactory for the

Accuracy Analysis of a Dam Model from Drone Surveys

Science.gov (United States)

Buffi, Giulia; Venturi, Sara

2017-01-01

This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs) used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D) model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations. PMID:28771185

Accuracy Analysis of a Dam Model from Drone Surveys

Directory of Open Access Journals (Sweden)

Elena Ridolfi

2017-08-01

Full Text Available This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations.

Accuracy Analysis of a Dam Model from Drone Surveys.

Science.gov (United States)

Ridolfi, Elena; Buffi, Giulia; Venturi, Sara; Manciola, Piergiorgio

2017-08-03

This paper investigates the accuracy of models obtained by drone surveys. To this end, this work analyzes how the placement of ground control points (GCPs) used to georeference the dense point cloud of a dam affects the resulting three-dimensional (3D) model. Images of a double arch masonry dam upstream face are acquired from drone survey and used to build the 3D model of the dam for vulnerability analysis purposes. However, there still remained the issue of understanding the real impact of a correct GCPs location choice to properly georeference the images and thus, the model. To this end, a high number of GCPs configurations were investigated, building a series of dense point clouds. The accuracy of these resulting dense clouds was estimated comparing the coordinates of check points extracted from the model and their true coordinates measured via traditional topography. The paper aims at providing information about the optimal choice of GCPs placement not only for dams but also for all surveys of high-rise structures. The knowledge a priori of the effect of the GCPs number and location on the model accuracy can increase survey reliability and accuracy and speed up the survey set-up operations.

On the Accuracy of Iranian EFL Students' Reading Self-assessment and their Level of Reading Proficiency

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Moein Shokr

2015-10-01

Full Text Available Reviewing the literature on self-assessment as an alternative method of assessment we find advocates claiming for the accuracy of the students’ self-assessments in general with little focus on their level of proficiency. With an eye on the students’ level of reading proficiency, the present study aimed at investigating the relationship between students’ reading self-assessment (as a formative and alternative method of assessment on the one hand, and teacher assessment (as a formative type of assessment as well as students’ final examination scores (as a summative and traditional method of assessment on the other. To this end, 65 students of Islamic Azad University- Tehran South Branch were selected to participate in this study. Initially, participants received PET test as pretest for assigning them into different levels of reading proficiency. Based upon the results of the pretest, participants were assigned to elementary and intermediate levels. Throughout the whole semester self-assessment questionnaire was employed for five times. Descriptive statistics and Pearson correlation were the data analysis techniques performed. The results of the study revealed a significant relationship between the intermediate learners’ self-ratings and teacher assessments; however, the results indicated no significant relationship between elementary learners’ self-assessments and teacher assessments. Also, the correlations between students’ self-assessments and their final examination scores were not significant for both levels. Therefore, given the teacher assessment as the yardstick, the accuracy of the intermediate levels and the inaccuracy of the elementary learners’ self-assessments could be concluded. Finally, the low correlation between the learners’ self-assessments and their scores on traditional final examination led the researcher to attribute it to the different nature of these two assessment types.

Accuracy of MFCC-Based Speaker Recognition in Series 60 Device

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Pasi Fränti

2005-10-01

Full Text Available A fixed point implementation of speaker recognition based on MFCC signal processing is considered. We analyze the numerical error of the MFCC and its effect on the recognition accuracy. Techniques to reduce the information loss in a converted fixed point implementation are introduced. We increase the signal processing accuracy by adjusting the ratio of presentation accuracy of the operators and the signal. The signal processing error is found out to be more important to the speaker recognition accuracy than the error in the classification algorithm. The results are verified by applying the alternative technique to speech data. We also discuss the specific programming requirements set up by the Symbian and Series 60.

Diagnostic accuracy of contrast-enhanced ultrasound in assessing the therapeutic response to radio frequency ablation for liver tumors: systematic review and meta-analysis.

Science.gov (United States)

Xuan, Min; Zhou, Fengsheng; Ding, Yan; Zhu, Qiaoying; Dong, Ji; Zhou, Hao; Cheng, Jun; Jiang, Xiao; Wu, Pengxi

2018-04-01

To review the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) used to detect residual or recurrent liver tumors after radiofrequency ablation (RFA). This technique uses contrast-enhanced computer tomography or/and contrast-enhanced magnetic resonance imaging as the gold standard of investigation. MEDLINE, EMBASE, and COCHRANE were systematically searched for all potentially eligible studies comparing CEUS with the reference standard that follows RFA. Risk of bias and applicability concerns were addressed by adopting the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Pooled point estimates for sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratios (DOR) with 95% CI were computed before plotting the sROC (summary receiver operating characteristic) curve. Meta-regression and subgroup analysis were used to identify the source of the heterogeneity that was detected. Publication bias was evaluated using Deeks' funnel plot asymmetry test. Ten eligible studies on 1162 lesions that occurred between 2001 and 2016 were included in the final analysis. The quality of the included studies assessed by the QUADAS-2 tool was considered reasonable. The pooled sensitivity and specificity of CEUS in detecting residual or recurrent liver tumors had the following values: 0.90 (95% CI 0.85-0.94) and 1.00 (95% CI 0.99-1.00), respectively. Overall DOR was 420.10 (95% CI 142.30-1240.20). The sources of heterogeneity could not be precisely identified by meta-regression or subgroup analysis. No evidence of publication bias was found. This study confirmed that CEUS exhibits high sensitivity and specificity in assessing therapeutic responses to RFA for liver tumors.

Assessment of the impact of point source pollution from the ...

African Journals Online (AJOL)

Assessment of the impact of point source pollution from the Keiskammahoek Sewage ... Water SA. Journal Home · ABOUT THIS JOURNAL · Advanced Search ... Also, significant pollution of the receiving Keiskamma River was indicated for ...

Point Lepreau refurbishment: plant condition assessment

International Nuclear Information System (INIS)

Allen, P.J.; Soulard, M.R.; David, F.; Clefton, G.; Weeks, R.

2001-01-01

New Brunswick Power (NB Power) has initiated a study into the refurbishment of the Point Lepreau Generating Station, with the objective to extend plant operation another 25 to 30 years. The end product of this study will be a business case that compares the costs of refurbishing Point Lepreau with costs of alternate means of generation. The Project Execution Plan and business case are being developed by an integrated team of AECL, NB Power and subcontractor staff under the project management of AECL. The refurbishment scope will include replacement of the pressure tubes, calandria tubes and part of the feeder piping. Planning of these replacements is part of the refurbishment study work. Planning is also underway for the environmental, safety and licensing issues that would need to be addressed to ensure future operation of the unit. In addition to these studies, a systematic review of the plant has been carried out to determine what other equipment refurbishment or replacement will be required due to ageing or obsolescence of plant equipment. This Plant Condition Assessment (PCA) follows a highly structured approach to ensure consistency. This paper presents an overview of the engineering process and the main findings from the work. (author)

TU-H-CAMPUS-JeP3-02: Automated Dose Accumulation and Dose Accuracy Assessment for Online Or Offline Adaptive Replanning

International Nuclear Information System (INIS)

Chen, G; Ahunbay, E; Li, X

2016-01-01

Purpose: With introduction of high-quality treatment imaging during radiation therapy (RT) delivery, e.g., MR-Linac, adaptive replanning of either online or offline becomes appealing. Dose accumulation of delivered fractions, a prerequisite for the adaptive replanning, can be cumbersome and inaccurate. The purpose of this work is to develop an automated process to accumulate daily doses and to assess the dose accumulation accuracy voxel-by-voxel for adaptive replanning. Methods: The process includes the following main steps: 1) reconstructing daily dose for each delivered fraction with a treatment planning system (Monaco, Elekta) based on the daily images using machine delivery log file and considering patient repositioning if applicable, 2) overlaying the daily dose to the planning image based on deformable image registering (DIR) (ADMIRE, Elekta), 3) assessing voxel dose deformation accuracy based on deformation field using predetermined criteria, and 4) outputting accumulated dose and dose-accuracy volume histograms and parameters. Daily CTs acquired using a CT-on-rails during routine CT-guided RT for sample patients with head and neck and prostate cancers were used to test the process. Results: Daily and accumulated doses (dose-volume histograms, etc) along with their accuracies (dose-accuracy volume histogram) can be robustly generated using the proposed process. The test data for a head and neck cancer case shows that the gross tumor volume decreased by 20% towards the end of treatment course, and the parotid gland mean dose increased by 10%. Such information would trigger adaptive replanning for the subsequent fractions. The voxel-based accuracy in the accumulated dose showed that errors in accumulated dose near rigid structures were small. Conclusion: A procedure as well as necessary tools to automatically accumulate daily dose and assess dose accumulation accuracy is developed and is useful for adaptive replanning. Partially supported by Elekta, Inc.

Therapy evaluation and diagnostic accuracy in neuroendocrine tumours: assessment of radiological methods

International Nuclear Information System (INIS)

Elvin, A.

1993-01-01

The diagnostic accuracy of ultrasonically guided biopsy-gun biopsies was assessed in a group of 47 patients with suspected pancreatic carcinoma. A correct diagnosis was obtained in 44 of the 47 patients (94%). Biopsy-gun biopsy of the pancreas is considered a useful, reliable and non-traumatic method for the diagnosis of pancreatic malignancy. Twenty-five patients with known neuroendocrine tumour disease were biopsied with 1.2 mm and 0.9 mm biopsy-gun needles. The influence of treatment-related fibrosis was also evaluated. The overall diagnostic accuracy with the 0.9 mm needle was 69% as compared to 92% with the 1.2 mm needle. In order to assess the diagnostic accuracy rate for radiologists with different experience of biopsy procedures 175 cases of renal biopsy-gun biopsies were evaluated. No statistical significant difference was found between the different operators. The role of duplex Doppler ultrasound in monitoring interferon treatment-related changes in carcinoid metastases was evaluated. It present duplex Doppler ultrasound does not seem to play a role in the evaluation of tumour therapy in carcinoid patients. Therapy response evaluation was performed with MR imaging in a group of 17 patients with neuroendocrine liver metastases. A significant difference was found between patients responding to and patients with failure of treatment in terms of tumour T1, contrast enhancement and signal intensity ratio. This indicates that MR investigation may be used in therapy monitoring of patients with neuroendocrine metastases. The neuroendocrine-differentiated colonic carcinoma cell line (LCC-18) was transplanted to 29 mice to establish a tumour/animal model that would allow the monitoring of changes with MR imaging induced by interferon therapy and to evaluate whether the therapeutic response could be modulated by different interferon dosages. Interferon does not seem to have any prolonged anti-proliferative effect on the LCC-18 tumour cell line when transplanted to

Particle Filter-Based Target Tracking Algorithm for Magnetic Resonance-Guided Respiratory Compensation : Robustness and Accuracy Assessment

NARCIS (Netherlands)

Bourque, Alexandra E; Bedwani, Stéphane; Carrier, Jean-François; Ménard, Cynthia; Borman, Pim; Bos, Clemens; Raaymakers, Bas W; Mickevicius, Nikolai; Paulson, Eric; Tijssen, Rob H N

PURPOSE: To assess overall robustness and accuracy of a modified particle filter-based tracking algorithm for magnetic resonance (MR)-guided radiation therapy treatments. METHODS AND MATERIALS: An improved particle filter-based tracking algorithm was implemented, which used a normalized

COMPARISON OF POINT CLOUDS DERIVED FROM AERIAL IMAGE MATCHING WITH DATA FROM AIRBORNE LASER SCANNING

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Dominik Wojciech

2017-04-01

Full Text Available The aim of this study was to invest igate the properties of point clouds derived from aerial image matching and to compare them with point clouds from airborne laser scanning. A set of aerial images acquired in years 2010 - 2013 over the city of Elblag were used for the analysis. Images were acquired with the use of three digital cameras: DMC II 230, DMC I and DigiCAM60 with a GSD varying from 4.5 cm to 15 cm. Eight sets of images that were used in the study were acquired at different stages of the growing season – from March to December. Two L iDAR point clouds were used for the comparison – one with a density of 1.3 p/m 2 and a second with a density of 10 p/m 2 . Based on the input images point clouds were created with the use of the semi - global matching method. The properties of the obtained poi nt clouds were analyzed in three ways: – b y the comparison of the vertical accuracy of point clouds with reference to a terrain profile surveyed on bare ground with GPS - RTK method – b y visual assessment of point cloud profiles generated both from SGM and LiDAR point clouds – b y visual assessment of a digital surface model generated from a SGM point cloud with reference to a digital surface model generated from a LiDAR point cloud. The conducted studies allowed a number of observations about the quality o f SGM point clouds to be formulated with respect to different factors. The main factors having influence on the quality of SGM point clouds are GSD and base/height ratio. The essential problem related to SGM point clouds are areas covered with vegetation w here SGM point clouds are visibly worse in terms of both accuracy and the representation of terrain surface. It is difficult to expect that in these areas SG M point clouds could replace LiDAR point clouds. This leads to a general conclusion that SGM point clouds are less reliable, more unpredictable and are dependent on more factors than LiDAR point clouds. Nevertheless, SGM point

Procedural Documentation and Accuracy Assessment of Bathymetric Maps and Area/Capacity Tables for Small Reservoirs

Science.gov (United States)

Wilson, Gary L.; Richards, Joseph M.

2006-01-01

Because of the increasing use and importance of lakes for water supply to communities, a repeatable and reliable procedure to determine lake bathymetry and capacity is needed. A method to determine the accuracy of the procedure will help ensure proper collection and use of the data and resulting products. It is important to clearly define the intended products and desired accuracy before conducting the bathymetric survey to ensure proper data collection. A survey-grade echo sounder and differential global positioning system receivers were used to collect water-depth and position data in December 2003 at Sugar Creek Lake near Moberly, Missouri. Data were collected along planned transects, with an additional set of quality-assurance data collected for use in accuracy computations. All collected data were imported into a geographic information system database. A bathymetric surface model, contour map, and area/capacity tables were created from the geographic information system database. An accuracy assessment was completed on the collected data, bathymetric surface model, area/capacity table, and contour map products. Using established vertical accuracy standards, the accuracy of the collected data, bathymetric surface model, and contour map product was 0.67 foot, 0.91 foot, and 1.51 feet at the 95 percent confidence level. By comparing results from different transect intervals with the quality-assurance transect data, it was determined that a transect interval of 1 percent of the longitudinal length of Sugar Creek Lake produced nearly as good results as 0.5 percent transect interval for the bathymetric surface model, area/capacity table, and contour map products.

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

Science.gov (United States)

Linden, Ariel

2006-04-01

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

Modeling and Accuracy Assessment for 3D-VIRTUAL Reconstruction in Cultural Heritage Using Low-Cost Photogrammetry: Surveying of the "santa MARÍA Azogue" Church's Front

Science.gov (United States)

Robleda Prieto, G.; Pérez Ramos, A.

2015-02-01

Sometimes it could be difficult to represent "on paper" an architectural idea, a solution, a detail or a newly created element, depending on the complexity what it want be conveyed through its graphical representation but it may be even harder to represent the existing reality. (a building, a detail,...), at least with an acceptable degree of definition and accuracy. As a solution to this hypothetical problem, this paper try to show a methodology to collect measure data by combining different methods or techniques, to obtain the characteristic geometry of architectonic elements, especially in those highly decorated and/or complex geometry, as well as to assess the accuracy of the results obtained, but in an accuracy level enough and not very expensive costs. In addition, we can obtain a 3D recovery model that allows us a strong support, beyond point clouds obtained through another more expensive methods as using laser scanner, to obtain orthoimages. This methodology was used in the study case of the 3D-virtual reconstruction of a main medieval church façade because of the geometrical complexity in many elements as the existing main doorway with archivolts and many details, as well as the rose window located above it so it's inaccessible due to the height.

Assessment of the accuracy of ABC/2 variations in traumatic epidural hematoma volume estimation: a retrospective study

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Pengfei Yan

2016-04-01

Full Text Available Background. The traumatic epidural hematoma (tEDH volume is often used to assist in tEDH treatment planning and outcome prediction. ABC/2 is a well-accepted volume estimation method that can be used for tEDH volume estimation. Previous studies have proposed different variations of ABC/2; however, it is unclear which variation will provide a higher accuracy. Given the promising clinical contribution of accurate tEDH volume estimations, we sought to assess the accuracy of several ABC/2 variations in tEDH volume estimation. Methods. The study group comprised 53 patients with tEDH who had undergone non-contrast head computed tomography scans. For each patient, the tEDH volume was automatically estimated by eight ABC/2 variations (four traditional and four newly derived with an in-house program, and results were compared to those from manual planimetry. Linear regression, the closest value, percentage deviation, and Bland-Altman plot were adopted to comprehensively assess accuracy. Results. Among all ABC/2 variations assessed, the traditional variations y = 0.5 × A1B1C1 (or A2B2C1 and the newly derived variations y = 0.65 × A1B1C1 (or A2B2C1 achieved higher accuracy than the other variations. No significant differences were observed between the estimated volume values generated by these variations and those of planimetry (p > 0.05. Comparatively, the former performed better than the latter in general, with smaller mean percentage deviations (7.28 ± 5.90% and 6.42 ± 5.74% versus 19.12 ± 6.33% and 21.28 ± 6.80%, respectively and more values closest to planimetry (18/53 and 18/53 versus 2/53 and 0/53, respectively. Besides, deviations of most cases in the former fell within the range of 20% (90.57% and 96.23, respectively. Discussion. In the current study, we adopted an automatic approach to assess the accuracy of several ABC/2 variations for tEDH volume estimation. Our initial results showed that the variations y = 0.5 × A1B1C1 (or A2B2C1

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Swains, American Samoa in 2012

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National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Tau, American Samoa in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

Accuracy assessment of planimetric large-scale map data for decision-making

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Doskocz Adam

2016-06-01

Full Text Available This paper presents decision-making risk estimation based on planimetric large-scale map data, which are data sets or databases which are useful for creating planimetric maps on scales of 1:5,000 or larger. The studies were conducted on four data sets of large-scale map data. Errors of map data were used for a risk assessment of decision-making about the localization of objects, e.g. for land-use planning in realization of investments. An analysis was performed for a large statistical sample set of shift vectors of control points, which were identified with the position errors of these points (errors of map data.

Accuracy of physical diagnostic tests for assessing ruptures of the anterior curciate ligament: a meta-analysis.

NARCIS (Netherlands)

Scholten, R.J.P.M.; Opstelten, W.; Plas, C.G. van der; Bijl, D.; Devillé, W.L.J.M.; Bouter, L.M.

2003-01-01

OBJECTIVE: This systematic review summarizes the evidence on the accuracy of tests for assessing ACL ruptures of the knee. SEARCH STRATEGY: A computerized search of MEDLINE (1966-2003) and EMBASE (1980-2003) with additional reference tracking. SELECTION CRITERIA: Articles included were written in

Assessing the sleeping habits of patients in a sleep disorder centre: a review of sleep diary accuracy

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Lawrence, Geoffrey

2018-01-01

Background Excessive daytime sleepiness (EDS) is a complaint common to many aspects of medicine. There are primary and secondary causes for EDS, with secondary causes including a large number of common conditions. Primary causes, such as narcolepsy, are much rarer. When assessing for primary hypersomnia, restricted or fragmented sleep must be ruled out. This process involves assessment of sleeping habits using a sleep diary and/or actigraphy. Clinicians are suspicious of the accuracy with which patients use the former. This review aims to evaluate the accuracy of a sleep diary study against the ‘objective gold standard’ actigraphy report. Methods Data from 35 patients at a Sleep Disorder Centre who underwent both a sleep diary and actigraphy study for suspected primary hypersomnia in 2016 was collected. Mean values of four variables were calculated: ‘time of lights out’, ‘time to fall asleep’, ‘time of waking’ and ‘sleep time’. The ‘similarity’ was assessed. This was a term defined in three different ways: if sleep diary values are accurate to within 20, 30 and 60 min respectively. Percentage ‘similarity’, mean time differences and standard deviations (SDs) were calculated for each variable. A paired t-test was also performed to assess the significance of the time differences between the two modalities. Results Least accurate was ‘sleep time’, with 14.7%, 23.5% and 58.8% of patients within 20, 30 and 60 min of the actigraphy respectively. Mean time difference for this variable was 66 min (versus 33, 15 and 22). ‘Time to fall asleep’ was most accurate, with 76.5%, 82.4% and 100% ‘similarity’ respectively. Conclusions The clinically acceptable accuracy has no universal definition, so clinicians must use experience and reasoning to determine this level to interpret this data. The review suggests that some variables are entered with high accuracy, and the diary is low cost and adds subjective information that cannot be gathered

Optimal Design of Fixed-Point and Floating-Point Arithmetic Units for Scientific Applications

OpenAIRE

Pongyupinpanich, Surapong

2012-01-01

The challenge in designing a floating-point arithmetic co-processor/processor for scientific and engineering applications is to improve the performance, efficiency, and computational accuracy of the arithmetic unit. The arithmetic unit should efficiently support several mathematical functions corresponding to scientific and engineering computation demands. Moreover, the computations should be performed as fast as possible with a high degree of accuracy. Thus, this thesis proposes algorithm, d...

Accuracy Assessment of Satellite Derived Forest Cover Products in South and Southeast Asia

Science.gov (United States)

Gilani, H.; Xu, X.; Jain, A. K.

2017-12-01

South and Southeast Asia (SSEA) region occupies 16 % of worlds land area. It is home to over 50% of the world's population. The SSEA's countries are experiencing significant land-use and land-cover changes (LULCCs), primarily in agriculture, forest, and urban land. For this study, we compiled four existing global forest cover maps for year 2010 by Gong et al.(2015), Hansen et al. (2013), Sexton et al.(2013) and Shimada et al. (2014), which were all medium resolution (≤30 m) products based on Landsat and/or PALSAR satellite images. To evaluate the accuracy of these forest products, we used three types of information: (1) ground measurements, (2) high resolution satellite images and (3) forest cover maps produced at the national scale. The stratified random sampling technique was used to select a set of validation data points from the ground and high-resolution satellite images. Then the confusion matrix method was used to assess and rank the accuracy of the forest cover products for the entire SSEA region. We analyzed the spatial consistency of different forest cover maps, and further evaluated the consistency with terrain characteristics. Our study suggests that global forest cover mapping algorithms are trained and tested using limited ground measurement data. We found significant uncertainties in mountainous areas due to the topographical shadow effect and the dense tree canopies effects. The findings of this study will facilitate to improve our understanding of the forest cover dynamics and their impacts on the quantities and pathways of terrestrial carbon and nitrogen fluxes. Gong, P., et al. (2012). "Finer resolution observation and monitoring of global land cover: first mapping results with Landsat TM and ETM+ data." International Journal of Remote Sensing 34(7): 2607-2654. Hansen, M. C., et al. (2013). "High-Resolution Global Maps of 21st-Century Forest Cover Change." Science 342(6160): 850-853. Sexton, J. O., et al. (2013). "Global, 30-m resolution

Family of Quantum Sources for Improving Near Field Accuracy in Transducer Modeling by the Distributed Point Source Method

Directory of Open Access Journals (Sweden)

Dominique Placko

2016-10-01

Full Text Available The distributed point source method, or DPSM, developed in the last decade has been used for solving various engineering problems—such as elastic and electromagnetic wave propagation, electrostatic, and fluid flow problems. Based on a semi-analytical formulation, the DPSM solution is generally built by superimposing the point source solutions or Green’s functions. However, the DPSM solution can be also obtained by superimposing elemental solutions of volume sources having some source density called the equivalent source density (ESD. In earlier works mostly point sources were used. In this paper the DPSM formulation is modified to introduce a new kind of ESD, replacing the classical single point source by a family of point sources that are referred to as quantum sources. The proposed formulation with these quantum sources do not change the dimension of the global matrix to be inverted to solve the problem when compared with the classical point source-based DPSM formulation. To assess the performance of this new formulation, the ultrasonic field generated by a circular planer transducer was compared with the classical DPSM formulation and analytical solution. The results show a significant improvement in the near field computation.

Point-of-care echocardiography in simulation-based education and assessment

Directory of Open Access Journals (Sweden)

Amini R

2016-05-01

Full Text Available Richard Amini, Lori A Stolz, Parisa P Javedani, Kevin Gaskin, Nicola Baker, Vivienne Ng, Srikar Adhikari Department of Emergency Medicine, University of Arizona Medical Center, Tucson, AZ, USA Background: Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US. The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. Objectives: We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents’ competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. Methods: This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. Results: A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. Conclusion: The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution. Keywords: point-of care ultrasound, simulation education

Accuracy assessment of landslide prediction models

International Nuclear Information System (INIS)

Othman, A N; Mohd, W M N W; Noraini, S

2014-01-01

The increasing population and expansion of settlements over hilly areas has greatly increased the impact of natural disasters such as landslide. Therefore, it is important to developed models which could accurately predict landslide hazard zones. Over the years, various techniques and models have been developed to predict landslide hazard zones. The aim of this paper is to access the accuracy of landslide prediction models developed by the authors. The methodology involved the selection of study area, data acquisition, data processing and model development and also data analysis. The development of these models are based on nine different landslide inducing parameters i.e. slope, land use, lithology, soil properties, geomorphology, flow accumulation, aspect, proximity to river and proximity to road. Rank sum, rating, pairwise comparison and AHP techniques are used to determine the weights for each of the parameters used. Four (4) different models which consider different parameter combinations are developed by the authors. Results obtained are compared to landslide history and accuracies for Model 1, Model 2, Model 3 and Model 4 are 66.7, 66.7%, 60% and 22.9% respectively. From the results, rank sum, rating and pairwise comparison can be useful techniques to predict landslide hazard zones

Rectal cancer staging: Multidetector-row computed tomography diagnostic accuracy in assessment of mesorectal fascia invasion

Science.gov (United States)

Ippolito, Davide; Drago, Silvia Girolama; Franzesi, Cammillo Talei; Fior, Davide; Sironi, Sandro

2016-01-01

AIM: To assess the diagnostic accuracy of multidetector-row computed tomography (MDCT) as compared with conventional magnetic resonance imaging (MRI), in identifying mesorectal fascia (MRF) invasion in rectal cancer patients. METHODS: Ninety-one patients with biopsy proven rectal adenocarcinoma referred for thoracic and abdominal CT staging were enrolled in this study. The contrast-enhanced MDCT scans were performed on a 256 row scanner (ICT, Philips) with the following acquisition parameters: tube voltage 120 KV, tube current 150-300 mAs. Imaging data were reviewed as axial and as multiplanar reconstructions (MPRs) images along the rectal tumor axis. MRI study, performed on 1.5 T with dedicated phased array multicoil, included multiplanar T2 and axial T1 sequences and diffusion weighted images (DWI). Axial and MPR CT images independently were compared to MRI and MRF involvement was determined. Diagnostic accuracy of both modalities was compared and statistically analyzed. RESULTS: According to MRI, the MRF was involved in 51 patients and not involved in 40 patients. DWI allowed to recognize the tumor as a focal mass with high signal intensity on high b-value images, compared with the signal of the normal adjacent rectal wall or with the lower tissue signal intensity background. The number of patients correctly staged by the native axial CT images was 71 out of 91 (41 with involved MRF; 30 with not involved MRF), while by using the MPR 80 patients were correctly staged (45 with involved MRF; 35 with not involved MRF). Local tumor staging suggested by MDCT agreed with those of MRI, obtaining for CT axial images sensitivity and specificity of 80.4% and 75%, positive predictive value (PPV) 80.4%, negative predictive value (NPV) 75% and accuracy 78%; while performing MPR the sensitivity and specificity increased to 88% and 87.5%, PPV was 90%, NPV 85.36% and accuracy 88%. MPR images showed higher diagnostic accuracy, in terms of MRF involvement, than native axial images

The succinonitrile triple-point standard: a fixed point to improve the accuracy of temperature measurements in the clinical laboratory.

Science.gov (United States)

Mangum, B W

1983-07-01

In an investigation of the melting and freezing behavior of succinonitrile, the triple-point temperature was determined to be 58.0805 degrees C, with an estimated uncertainty of +/- 0.0015 degrees C relative to the International Practical Temperature Scale of 1968 (IPTS-68). The triple-point temperature of this material is evaluated as a temperature-fixed point, and some clinical laboratory applications of this fixed point are proposed. In conjunction with the gallium and ice points, the availability of succinonitrile permits thermistor thermometers to be calibrated accurately and easily on the IPTS-68.

Interethnic differences in the accuracy of anthropometric indicators of obesity in screening for high risk of coronary heart disease

Science.gov (United States)

Herrera, VM; Casas, JP; Miranda, JJ; Perel, P; Pichardo, R; González, A; Sanchez, JR; Ferreccio, C; Aguilera, X; Silva, E; Oróstegui, M; Gómez, LF; Chirinos, JA; Medina-Lezama, J; Pérez, CM; Suárez, E; Ortiz, AP; Rosero, L; Schapochnik, N; Ortiz, Z; Ferrante, D; Diaz, M; Bautista, LE

2009-01-01

Background Cut points for defining obesity have been derived from mortality data among Whites from Europe and the United States and their accuracy to screen for high risk of coronary heart disease (CHD) in other ethnic groups has been questioned. Objective To compare the accuracy and to define ethnic and gender-specific optimal cut points for body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) when they are used in screening for high risk of CHD in the Latin-American and the US populations. Methods We estimated the accuracy and optimal cut points for BMI, WC and WHR to screen for CHD risk in Latin Americans (n=18 976), non-Hispanic Whites (Whites; n=8956), non-Hispanic Blacks (Blacks; n=5205) and Hispanics (n=5803). High risk of CHD was defined as a 10-year risk ≥20% (Framingham equation). The area under the receiver operator characteristic curve (AUC) and the misclassification-cost term were used to assess accuracy and to identify optimal cut points. Results WHR had the highest AUC in all ethnic groups (from 0.75 to 0.82) and BMI had the lowest (from 0.50 to 0.59). Optimal cut point for BMI was similar across ethnic/gender groups (27 kg/m2). In women, cut points for WC (94 cm) and WHR (0.91) were consistent by ethnicity. In men, cut points for WC and WHR varied significantly with ethnicity: from 91 cm in Latin Americans to 102 cm in Whites, and from 0.94 in Latin Americans to 0.99 in Hispanics, respectively. Conclusion WHR is the most accurate anthropometric indicator to screen for high risk of CHD, whereas BMI is almost uninformative. The same BMI cut point should be used in all men and women. Unique cut points for WC and WHR should be used in all women, but ethnic-specific cut points seem warranted among men. PMID:19238159

VERTICAL ACCURACY ASSESSMENT OF ZY-3 DIGITAL SURFACE MODEL USING ICESAT/GLAS LASER ALTIMETER DATA

Directory of Open Access Journals (Sweden)

G. Li

2017-05-01

Full Text Available The Ziyuan-3 (ZY-3 satellite, as the first civilian high resolution surveying and mapping satellite in China, has a very important role in national 1 : 50,000 stereo mapping project. High accuracy digital surface Model (DSMs can be generated from the three line-array images of ZY-3, and ZY-3 DSMs of China can be produced without using any ground control points (GCPs by selecting SRTM (Shuttle Radar Topography Mission and ICESat/GLAS (Ice, Cloud, and land Elevation Satellite, Geo-science Laser Altimeter System as the datum reference in the Satellite Surveying and Mapping Application Center, which is the key institute that manages and distributes ZY-3 products. To conduct the vertical accuracy evaluation of ZY-3 DSMs of China, three representative regions were chosen and the results were compared to ICESat/GLAS data. The experimental results demonstrated that the root mean square error (RMSE elevation accuracy of the ZY-3 DSMs was better than 5.0 m, and it even reached to less than 2.5 m in the second region of eastern China. While this work presents preliminary results, it is an important reference for expanding the application of ZY-3 satellite imagery to widespread regions. And the satellite laser altimetry data can be used as referenced data for wide-area DSM evaluation.

Probabilistic seismic hazard assessment for Point Lepreau Generating Station

Energy Technology Data Exchange (ETDEWEB)

Mullin, D. [New Brunswick Power Corp., Point Lepreau Generating Station, Lepreau, New Brunswick (Canada); Lavine, A. [AMEC Foster Wheeler Environment and Infrastructure Americas, Oakland, California (United States); Egan, J. [SAGE Engineers, Oakland, California (United States)

2015-09-15

A Probabilistic Seismic Hazard Assessment (PSHA) has been performed for the Point Lepreau Generating Station (PLGS). The objective is to provide characterization of the earthquake ground shaking that will be used to evaluate seismic safety. The assessment is based on the current state of knowledge of the informed scientific and engineering community regarding earthquake hazards in the site region, and includes two primary components-a seismic source model and a ground motion model. This paper provides the methodology and results of the PLGS PSHA. The implications of the updated hazard information for site safety are discussed in a separate paper. (author)

Probabilistic seismic hazard assessment for Point Lepreau Generating Station

Energy Technology Data Exchange (ETDEWEB)

Mullin, D., E-mail: dmullin@nbpower.com [New Brunswick Power Corporation, Point Lepreau Generating Station, Point Lepreau, NB (Canada); Lavine, A., E-mail: alexis.lavine@amecfw.com [AMEC Foster Wheeler Environment & Infrastructure Americas, Oakland, CA (United States); Egan, J., E-mail: jegan@sageengineers.com [SAGE Engineers, Oakland, CA (United States)

2015-07-01

A Probabilistic Seismic Hazard Assessment (PSHA) has been performed for the Point Lepreau Generating Station (PLGS). The objective is to provide characterization of the earthquake ground shaking that will be used to evaluate seismic safety. The assessment is based on the current state of knowledge of the informed scientific and engineering community regarding earthquake hazards in the site region, and includes two primary components--a seismic source model and a ground motion model. This paper provides the methodology and results of the PLGS PSHA. The implications of the updated hazard information for site safety are discussed in a separate paper. (author)

Improvement of the accuracy of phase observation by modification of phase-shifting electron holography

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Takahiro; Aizawa, Shinji; Tanigaki, Toshiaki [Advanced Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Ota, Keishin, E-mail: ota@microphase.co.jp [Microphase Co., Ltd., Onigakubo 1147-9, Tsukuba, Ibaragi 300-2651 (Japan); Matsuda, Tsuyoshi [Japan Science and Technology Agency, Kawaguchi-shi, Saitama 332-0012 (Japan); Tonomura, Akira [Advanced Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Okinawa Institute of Science and Technology, Graduate University, Kunigami, Okinawa 904-0495 (Japan); Central Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama 350-0395 (Japan)

2012-07-15

We found that the accuracy of the phase observation in phase-shifting electron holography is strongly restricted by time variations of mean intensity and contrast of the holograms. A modified method was developed for correcting these variations. Experimental results demonstrated that the modification enabled us to acquire a large number of holograms, and as a result, the accuracy of the phase observation has been improved by a factor of 5. -- Highlights: Black-Right-Pointing-Pointer A modified phase-shifting electron holography was proposed. Black-Right-Pointing-Pointer The time variation of mean intensity and contrast of holograms were corrected. Black-Right-Pointing-Pointer These corrections lead to a great improvement of the resultant phase accuracy. Black-Right-Pointing-Pointer A phase accuracy of about 1/4000 rad was achieved from experimental results.

Magic Pointing for Eyewear Computers

DEFF Research Database (Denmark)

Jalaliniya, Shahram; Mardanbegi, Diako; Pederson, Thomas

2015-01-01

In this paper, we propose a combination of head and eye movements for touchlessly controlling the "mouse pointer" on eyewear devices, exploiting the speed of eye pointing and accuracy of head pointing. The method is a wearable computer-targeted variation of the original MAGIC pointing approach...... which combined gaze tracking with a classical mouse device. The result of our experiment shows that the combination of eye and head movements is faster than head pointing for far targets and more accurate than eye pointing....

Test expectancy affects metacomprehension accuracy.

Science.gov (United States)

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

2011-06-01

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 practice tests. The purpose of the present study was to examine whether the accuracy metacognitive monitoring was affected by the nature of the test expected. Students (N= 59) were randomly assigned to one of two test expectancy groups (memory vs. inference). Then after reading texts, judging learning, completed both memory and inference tests. Test performance and monitoring accuracy were superior when students received the kind of test they had been led to expect rather than the unexpected test. Tests influence students' perceptions of what constitutes learning. Our findings suggest that this could affect how students prepare for tests and how they monitoring their own learning. ©2010 The British Psychological Society.

Estimate of cryoscopic calculations accuracy from fusibility diagrams

International Nuclear Information System (INIS)

Viting, L.M.; Gorbovskaya, G.P.

1975-01-01

The melting points of some lead and zinc salts, that can be used as solvents for ferrites in systems: PbMoO 4 -MgFe 2 O 4 , Zn 2 V 2 O 7 -NiFe 2 O 4 , Pb 3 (VO 4 ) 2 -MgFe 2 O 4 , have been calculated in accordance with the hypotetical mechanism of the solvent dissociation. The accuracy of cryoscopic calculations based on melting point curves is evaluated. Cryoscopic calculations permit to determin the solvent activity with the accuracy of +-0.3% and the heat of its fusion, with the accuracy of +-3%. The comparison of the calculated and experimental values of the entropy of melting, as well as calculated and experimental values of the cryoscopic constant elucidates the mechanism of dissociation of both the dissolved compound and the solvent

Diagnostic accuracy of CT in assessing extra-regional lymphadenopathy in pancreatic and peri-ampullary cancer: a systematic review and meta-analysis.

Science.gov (United States)

Tseng, Dorine S J; van Santvoort, Hjalmar C; Fegrachi, Samira; Besselink, Marc G; Zuithoff, Nicolaas P A; Borel Rinkes, Inne H; van Leeuwen, Maarten S; Molenaar, I Quintus

2014-12-01

Computed tomography (CT) is the most widely used method to assess resectability of pancreatic and peri-ampullary cancer. One of the contra-indications for curative resection is the presence of extra-regional lymph node metastases. This meta-analysis investigates the accuracy of CT in assessing extra-regional lymph node metastases in pancreatic and peri-ampullary cancer. We systematically reviewed the literature according to the PRISMA guidelines. Studies reporting on CT assessment of extra-regional lymph nodes in patients undergoing pancreatoduodenectomy were included. Data on baseline characteristics, CT-investigations and histopathological outcomes were extracted. Diagnostic accuracy, positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity were calculated for individual studies and pooled data. After screening, 4 cohort studies reporting on CT-findings and histopathological outcome in 157 patients with pancreatic or peri-ampullary cancer were included. Overall, diagnostic accuracy, specificity and NPV varied from 63 to 81, 80-100% and 67-90% respectively. However, PPV and sensitivity ranged from 0 to 100% and 0-38%. Pooled sensitivity, specificity, PPV and NPV were 25%, 86%, 28% and 84% respectively. CT has a low diagnostic accuracy in assessing extra-regional lymph node metastases in pancreatic and peri-ampullary cancer. Therefore, suspicion of extra-regional lymph node metastases on CT alone should not be considered a contra-indication for exploration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Visual assessment of the cervical vertebral maturation stages: A study of diagnostic accuracy and repeatability.

Science.gov (United States)

Perinetti, Giuseppe; Caprioglio, Alberto; Contardo, Luca

2014-11-01

To evaluate the diagnostic accuracy and repeatability of the visual assessment of the cervical vertebral maturation (CVM) stages. Ten operators underwent training sessions in visual assessment of CVM staging. Subsequently, they were asked to stage 72 cases equally divided into the six stages. Such assessment was repeated twice in two sessions (T1 and T2) 4 weeks apart. A reference standard for each case was created according to a cephalometric analysis of both the concavities and shapes of the cervical vertebrae. The overall agreement with the reference standard was about 68% for both sessions and 76.9% for intrarater repeatability. The overall kappa coefficients with the reference standard were up to 0.86 for both sessions, and 0.88 for intrarater repeatability. Overall, disagreements one stage and twp stage apart were 23.5% (T1) and 5.1% (T2), respectively. Sensitivity ranged from 53.3% for CS5 (T1) to 99.9% for CS1 (T2), positive predictive values ranged from 52.4% for CS5 (T2) to 94.3% for CS6 (T1), and accuracy ranged from 83.6% for CS4 (T2) to 94.9% for CS1 (T1). Visual assessment of the CVM stages is accurate and repeatable to a satisfactory level. About one in three cases remain misclassified; disagreement is generally limited to one stage and is mostly seen in stages 4 and 5.

Image quality, radiation dose and diagnostic accuracy of 70 kVp whole brain volumetric CT perfusion imaging: a preliminary study

Energy Technology Data Exchange (ETDEWEB)

Fang, Xiao Kun; Ni, Qian Qian; Zhou, Chang Sheng; Chen, Guo Zhong; Luo, Song; Zhang, Long Jiang; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Schoepf, U.J. [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Medical University of South Carolina, Ashley River Tower, Division of Cardiovascular Imaging, Charleston, SC (United States); Fuller, Stephen R.; De Cecco, Carlo N. [Medical University of South Carolina, Ashley River Tower, Division of Cardiovascular Imaging, Charleston, SC (United States)

2016-11-15

To evaluate image quality and diagnostic accuracy for acute infarct detection and radiation dose of 70 kVp whole brain CT perfusion (CTP) and CT angiography (CTA) reconstructed from CTP source data. Patients were divided into three groups (n = 50 each): group A, 80 kVp, 21 scanning time points; groups B, 70 kVp, 21 scanning time points; group C, 70 kVp, 17 scanning time points. Objective and subjective image quality of CTP and CTA were compared. Diagnostic accuracy for detecting acute infarct and cerebral artery stenosis ≥ 50 % was calculated for CTP and CTA with diffusion weighted imaging and digital subtraction angiography as reference standards. Effective radiation dose was compared. There were no differences in any perfusion parameter value between three groups (P > 0.05). No difference was found in subjective image quality between three groups (P > 0.05). Diagnostic accuracy for detecting acute infarct and vascular stenosis showed no difference between three groups (P > 0.05). Compared with group A, radiation doses of groups B and C were decreased by 28 % and 37 % (both P < 0.001), respectively. Compared with 80 kVp protocol, 70 kVp brain CTP allows comparable vascular and perfusion assessment and lower radiation dose while maintaining high diagnostic accuracy in detecting acute infarct. (orig.)

On the Accuracy of Language Trees

Science.gov (United States)

Pompei, Simone; Loreto, Vittorio; Tria, Francesca

2011-01-01

Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic) features or characters for many different languages: a set of parallel corpora whose compilation represents a paramount achievement in linguistics. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve it. PMID:21674034

On the accuracy of language trees.

Directory of Open Access Journals (Sweden)

Simone Pompei

Full Text Available Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic features or characters for many different languages: a set of parallel corpora whose compilation represents a paramount achievement in linguistics. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve

Influence of Ephemeris Error on GPS Single Point Positioning Accuracy

Science.gov (United States)

Lihua, Ma; Wang, Meng

2013-09-01

The Global Positioning System (GPS) user makes use of the navigation message transmitted from GPS satellites to achieve its location. Because the receiver uses the satellite's location in position calculations, an ephemeris error, a difference between the expected and actual orbital position of a GPS satellite, reduces user accuracy. The influence extent is decided by the precision of broadcast ephemeris from the control station upload. Simulation analysis with the Yuma almanac show that maximum positioning error exists in the case where the ephemeris error is along the line-of-sight (LOS) direction. Meanwhile, the error is dependent on the relationship between the observer and spatial constellation at some time period.

Uncertainty in real-time voltage stability assessment methods based on Thevenin equivalent due to PMU’s accuracy

DEFF Research Database (Denmark)

Perez, Angel; Møller, Jakob Glarbo; Jóhannsson, Hjörtur

2014-01-01

This article studies the influence of PMU’s accuracy in voltage stability assessment, considering the specific case of Th ́ evenin equivalent based methods that include wide-area information in its calculations. The objective was achieved by producing a set of synthesized PMU measurements from...... a time domain simulation and using the Monte Carlo method to reflect the accuracy for the PMUs. This is given by the maximum value for the Total Vector Error defined in the IEEE standard C37.118. Those measurements allowed to estimate the distribution pa- rameters (mean and standard deviation...

Accuracy of Focused Assessment with Sonography for Trauma (FAST) in Blunt Trauma Abdomen-A Prospective Study.

Science.gov (United States)

Kumar, Subodh; Bansal, Virinder Kumar; Muduly, Dillip Kumar; Sharma, Pawan; Misra, Mahesh C; Chumber, Sunil; Singh, Saraman; Bhardwaj, D N

2015-12-01

Focused assessment with sonography for trauma (FAST) is a limited ultrasound examination, primarily aimed at the identification of the presence of free intraperitoneal or pericardial fluid. In the context of blunt trauma abdomen (BTA), free fluid is usually due to hemorrhage, bowel contents, or both; contributes towards the timely diagnosis of potentially life-threatening hemorrhage; and is a decision-making tool to help determine the need for further evaluation or operative intervention. Fifty patients with blunt trauma abdomen were evaluated prospectively with FAST. The findings of FAST were compared with contrast-enhanced computed tomography (CECT), laparotomy, and autopsy. Any free fluid in the abdomen was presumed to be hemoperitoneum. Sonographic findings of intra-abdominal free fluid were confirmed by CECT, laparotomy, or autopsy wherever indicated. In comparing with CECT scan, FAST had a sensitivity, specificity, and accuracy of 77.27, 100, and 79.16 %, respectively, in the detection of free fluid. When compared with surgical findings, it had a sensitivity, specificity, and accuracy of 94.44, 50, and 90 %, respectively. The sensitivity of FAST was 75 % in determining free fluid in patients who died when compared with autopsy findings. Overall sensitivity, specificity, and accuracy of FAST were 80.43, 75 and 80 %, respectively, for the detection of free fluid in the abdomen. From this study, we can safely conclude that FAST is a rapid, reliable, and feasible investigation in patients with BTA, and it can be performed easily, safely, and quickly in the emergency room with a reasonable sensitivity, specificity, and accuracy. It helps in the initial triage of patients for assessing the need for urgent surgery.

Accuracy Assessment of Lidar-Derived Digital Terrain Model (dtm) with Different Slope and Canopy Cover in Tropical Forest Region

Science.gov (United States)

Salleh, M. R. M.; Ismail, Z.; Rahman, M. Z. A.

2015-10-01

Airborne Light Detection and Ranging (LiDAR) technology has been widely used recent years especially in generating high accuracy of Digital Terrain Model (DTM). High density and good quality of airborne LiDAR data promises a high quality of DTM. This study focussing on the analysing the error associated with the density of vegetation cover (canopy cover) and terrain slope in a LiDAR derived-DTM value in a tropical forest environment in Bentong, State of Pahang, Malaysia. Airborne LiDAR data were collected can be consider as low density captured by Reigl system mounted on an aircraft. The ground filtering procedure use adaptive triangulation irregular network (ATIN) algorithm technique in producing ground points. Next, the ground control points (GCPs) used in generating the reference DTM and these DTM was used for slope classification and the point clouds belong to non-ground are then used in determining the relative percentage of canopy cover. The results show that terrain slope has high correlation for both study area (0.993 and 0.870) with the RMSE of the LiDAR-derived DTM. This is similar to canopy cover where high value of correlation (0.989 and 0.924) obtained. This indicates that the accuracy of airborne LiDAR-derived DTM is significantly affected by terrain slope and canopy caver of study area.

ACCURACY ASSESSMENT OF LIDAR-DERIVED DIGITAL TERRAIN MODEL (DTM WITH DIFFERENT SLOPE AND CANOPY COVER IN TROPICAL FOREST REGION

Directory of Open Access Journals (Sweden)

M. R. M. Salleh

2015-10-01

Full Text Available Airborne Light Detection and Ranging (LiDAR technology has been widely used recent years especially in generating high accuracy of Digital Terrain Model (DTM. High density and good quality of airborne LiDAR data promises a high quality of DTM. This study focussing on the analysing the error associated with the density of vegetation cover (canopy cover and terrain slope in a LiDAR derived-DTM value in a tropical forest environment in Bentong, State of Pahang, Malaysia. Airborne LiDAR data were collected can be consider as low density captured by Reigl system mounted on an aircraft. The ground filtering procedure use adaptive triangulation irregular network (ATIN algorithm technique in producing ground points. Next, the ground control points (GCPs used in generating the reference DTM and these DTM was used for slope classification and the point clouds belong to non-ground are then used in determining the relative percentage of canopy cover. The results show that terrain slope has high correlation for both study area (0.993 and 0.870 with the RMSE of the LiDAR-derived DTM. This is similar to canopy cover where high value of correlation (0.989 and 0.924 obtained. This indicates that the accuracy of airborne LiDAR-derived DTM is significantly affected by terrain slope and canopy caver of study area.

New technology in dietary assessment: a review of digital methods in improving food record accuracy.

Science.gov (United States)

Stumbo, Phyllis J

2013-02-01

Methods for conducting dietary assessment in the United States date back to the early twentieth century. Methods of assessment encompassed dietary records, written and spoken dietary recalls, FFQ using pencil and paper and more recently computer and internet applications. Emerging innovations involve camera and mobile telephone technology to capture food and meal images. This paper describes six projects sponsored by the United States National Institutes of Health that use digital methods to improve food records and two mobile phone applications using crowdsourcing. The techniques under development show promise for improving accuracy of food records.

Positional Accuracy Assessment for Effective Shoreline Change ...

African Journals Online (AJOL)

Ghana Mining Journal ... Data quality may be expressed in terms of several indicators such as attributes, temporal or positional accuracies. ... It is concluded that for the purpose of shoreline change analysis, such as shoreline change trends, large scale data sources should be used where possible for accurate ...

Remote Sensing Based Two-Stage Sampling for Accuracy Assessment and Area Estimation of Land Cover Changes

Directory of Open Access Journals (Sweden)

Heinz Gallaun

2015-09-01

Full Text Available Land cover change processes are accelerating at the regional to global level. The remote sensing community has developed reliable and robust methods for wall-to-wall mapping of land cover changes; however, land cover changes often occur at rates below the mapping errors. In the current publication, we propose a cost-effective approach to complement wall-to-wall land cover change maps with a sampling approach, which is used for accuracy assessment and accurate estimation of areas undergoing land cover changes, including provision of confidence intervals. We propose a two-stage sampling approach in order to keep accuracy, efficiency, and effort of the estimations in balance. Stratification is applied in both stages in order to gain control over the sample size allocated to rare land cover change classes on the one hand and the cost constraints for very high resolution reference imagery on the other. Bootstrapping is used to complement the accuracy measures and the area estimates with confidence intervals. The area estimates and verification estimations rely on a high quality visual interpretation of the sampling units based on time series of satellite imagery. To demonstrate the cost-effective operational applicability of the approach we applied it for assessment of deforestation in an area characterized by frequent cloud cover and very low change rate in the Republic of Congo, which makes accurate deforestation monitoring particularly challenging.

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Maui, Main Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Hawaii, Main Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Ofu & Olosega, American Samoa in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Niihau, Main Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Kauai, Main Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Farallon de Pajaros, Marianas in 2011

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Lanai, Main Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

Biased binomial assessment of cross-validated estimation of classification accuracies illustrated in diagnosis predictions.

Science.gov (United States)

Noirhomme, Quentin; Lesenfants, Damien; Gomez, Francisco; Soddu, Andrea; Schrouff, Jessica; Garraux, Gaëtan; Luxen, André; Phillips, Christophe; Laureys, Steven

2014-01-01

Multivariate classification is used in neuroimaging studies to infer brain activation or in medical applications to infer diagnosis. Their results are often assessed through either a binomial or a permutation test. Here, we simulated classification results of generated random data to assess the influence of the cross-validation scheme on the significance of results. Distributions built from classification of random data with cross-validation did not follow the binomial distribution. The binomial test is therefore not adapted. On the contrary, the permutation test was unaffected by the cross-validation scheme. The influence of the cross-validation was further illustrated on real-data from a brain-computer interface experiment in patients with disorders of consciousness and from an fMRI study on patients with Parkinson disease. Three out of 16 patients with disorders of consciousness had significant accuracy on binomial testing, but only one showed significant accuracy using permutation testing. In the fMRI experiment, the mental imagery of gait could discriminate significantly between idiopathic Parkinson's disease patients and healthy subjects according to the permutation test but not according to the binomial test. Hence, binomial testing could lead to biased estimation of significance and false positive or negative results. In our view, permutation testing is thus recommended for clinical application of classification with cross-validation.

Continuous Extraction of Subway Tunnel Cross Sections Based on Terrestrial Point Clouds

Directory of Open Access Journals (Sweden)

Zhizhong Kang

2014-01-01

Full Text Available An efficient method for the continuous extraction of subway tunnel cross sections using terrestrial point clouds is proposed. First, the continuous central axis of the tunnel is extracted using a 2D projection of the point cloud and curve fitting using the RANSAC (RANdom SAmple Consensus algorithm, and the axis is optimized using a global extraction strategy based on segment-wise fitting. The cross-sectional planes, which are orthogonal to the central axis, are then determined for every interval. The cross-sectional points are extracted by intersecting straight lines that rotate orthogonally around the central axis within the cross-sectional plane with the tunnel point cloud. An interpolation algorithm based on quadric parametric surface fitting, using the BaySAC (Bayesian SAmpling Consensus algorithm, is proposed to compute the cross-sectional point when it cannot be acquired directly from the tunnel points along the extraction direction of interest. Because the standard shape of the tunnel cross section is a circle, circle fitting is implemented using RANSAC to reduce the noise. The proposed approach is tested on terrestrial point clouds that cover a 150-m-long segment of a Shanghai subway tunnel, which were acquired using a LMS VZ-400 laser scanner. The results indicate that the proposed quadric parametric surface fitting using the optimized BaySAC achieves a higher overall fitting accuracy (0.9 mm than the accuracy (1.6 mm obtained by the plain RANSAC. The results also show that the proposed cross section extraction algorithm can achieve high accuracy (millimeter level, which was assessed by comparing the fitted radii with the designed radius of the cross section and comparing corresponding chord lengths in different cross sections and high efficiency (less than 3 s/section on average.

Accuracy, precision, and economic efficiency for three methods of thrips (Thysanoptera: Thripidae) population density assessment.

Science.gov (United States)

Sutherland, Andrew M; Parrella, Michael P

2011-08-01

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major horticultural pest and an important vector of plant viruses in many parts of the world. Methods for assessing thrips population density for pest management decision support are often inaccurate or imprecise due to thrips' positive thigmotaxis, small size, and naturally aggregated populations. Two established methods, flower tapping and an alcohol wash, were compared with a novel method, plant desiccation coupled with passive trapping, using accuracy, precision and economic efficiency as comparative variables. Observed accuracy was statistically similar and low (37.8-53.6%) for all three methods. Flower tapping was the least expensive method, in terms of person-hours, whereas the alcohol wash method was the most expensive. Precision, expressed by relative variation, depended on location within the greenhouse, location on greenhouse benches, and the sampling week, but it was generally highest for the flower tapping and desiccation methods. Economic efficiency, expressed by relative net precision, was highest for the flower tapping method and lowest for the alcohol wash method. Advantages and disadvantages are discussed for all three methods used. If relative density assessment methods such as these can all be assumed to accurately estimate a constant proportion of absolute density, then high precision becomes the methodological goal in terms of measuring insect population density, decision making for pest management, and pesticide efficacy assessments.

Environmental tipping points significantly affect the cost−benefit assessment of climate policies

Science.gov (United States)

Cai, Yongyang; Judd, Kenneth L.; Lenton, Timothy M.; Lontzek, Thomas S.; Narita, Daiju

2015-01-01

Most current cost−benefit analyses of climate change policies suggest an optimal global climate policy that is significantly less stringent than the level required to meet the internationally agreed 2 °C target. This is partly because the sum of estimated economic damage of climate change across various sectors, such as energy use and changes in agricultural production, results in only a small economic loss or even a small economic gain in the gross world product under predicted levels of climate change. However, those cost−benefit analyses rarely take account of environmental tipping points leading to abrupt and irreversible impacts on market and nonmarket goods and services, including those provided by the climate and by ecosystems. Here we show that including environmental tipping point impacts in a stochastic dynamic integrated assessment model profoundly alters cost−benefit assessment of global climate policy. The risk of a tipping point, even if it only has nonmarket impacts, could substantially increase the present optimal carbon tax. For example, a risk of only 5% loss in nonmarket goods that occurs with a 5% annual probability at 4 °C increase of the global surface temperature causes an immediate two-thirds increase in optimal carbon tax. If the tipping point also has a 5% impact on market goods, the optimal carbon tax increases by more than a factor of 3. Hence existing cost−benefit assessments of global climate policy may be significantly underestimating the needs for controlling climate change. PMID:25825719

Environmental tipping points significantly affect the cost-benefit assessment of climate policies.

Science.gov (United States)

Cai, Yongyang; Judd, Kenneth L; Lenton, Timothy M; Lontzek, Thomas S; Narita, Daiju

2015-04-14

Most current cost-benefit analyses of climate change policies suggest an optimal global climate policy that is significantly less stringent than the level required to meet the internationally agreed 2 °C target. This is partly because the sum of estimated economic damage of climate change across various sectors, such as energy use and changes in agricultural production, results in only a small economic loss or even a small economic gain in the gross world product under predicted levels of climate change. However, those cost-benefit analyses rarely take account of environmental tipping points leading to abrupt and irreversible impacts on market and nonmarket goods and services, including those provided by the climate and by ecosystems. Here we show that including environmental tipping point impacts in a stochastic dynamic integrated assessment model profoundly alters cost-benefit assessment of global climate policy. The risk of a tipping point, even if it only has nonmarket impacts, could substantially increase the present optimal carbon tax. For example, a risk of only 5% loss in nonmarket goods that occurs with a 5% annual probability at 4 °C increase of the global surface temperature causes an immediate two-thirds increase in optimal carbon tax. If the tipping point also has a 5% impact on market goods, the optimal carbon tax increases by more than a factor of 3. Hence existing cost-benefit assessments of global climate policy may be significantly underestimating the needs for controlling climate change.

Experimental assessment of the accuracy of genomic selection in sugarcane.

Science.gov (United States)

Gouy, M; Rousselle, Y; Bastianelli, D; Lecomte, P; Bonnal, L; Roques, D; Efile, J-C; Rocher, S; Daugrois, J; Toubi, L; Nabeneza, S; Hervouet, C; Telismart, H; Denis, M; Thong-Chane, A; Glaszmann, J C; Hoarau, J-Y; Nibouche, S; Costet, L

2013-10-01

Sugarcane cultivars are interspecific hybrids with an aneuploid, highly heterozygous polyploid genome. The complexity of the sugarcane genome is the main obstacle to the use of marker-assisted selection in sugarcane breeding. Given the promising results of recent studies of plant genomic selection, we explored the feasibility of genomic selection in this complex polyploid crop. Genetic values were predicted in two independent panels, each composed of 167 accessions representing sugarcane genetic diversity worldwide. Accessions were genotyped with 1,499 DArT markers. One panel was phenotyped in Reunion Island and the other in Guadeloupe. Ten traits concerning sugar and bagasse contents, digestibility and composition of the bagasse, plant morphology, and disease resistance were used. We used four statistical predictive models: bayesian LASSO, ridge regression, reproducing kernel Hilbert space, and partial least square regression. The accuracy of the predictions was assessed through the correlation between observed and predicted genetic values by cross validation within each panel and between the two panels. We observed equivalent accuracy among the four predictive models for a given trait, and marked differences were observed among traits. Depending on the trait concerned, within-panel cross validation yielded median correlations ranging from 0.29 to 0.62 in the Reunion Island panel and from 0.11 to 0.5 in the Guadeloupe panel. Cross validation between panels yielded correlations ranging from 0.13 for smut resistance to 0.55 for brix. This level of correlations is promising for future implementations. Our results provide the first validation of genomic selection in sugarcane.

Integrated three-dimensional digital assessment of accuracy of anterior tooth movement using clear aligners

OpenAIRE

Zhang, Xiao-Juan; He, Li; Guo, Hong-Ming; Tian, Jie; Bai, Yu-Xing; Li, Song

2015-01-01

Objective To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by St...

Localisation accuracy of semi-dense monocular SLAM

Science.gov (United States)

Schreve, Kristiaan; du Plessies, Pieter G.; Rätsch, Matthias

2017-06-01

Understanding the factors that influence the accuracy of visual SLAM algorithms is very important for the future development of these algorithms. So far very few studies have done this. In this paper, a simulation model is presented and used to investigate the effect of the number of scene points tracked, the effect of the baseline length in triangulation and the influence of image point location uncertainty. It is shown that the latter is very critical, while the other all play important roles. Experiments with a well known semi-dense visual SLAM approach are also presented, when used in a monocular visual odometry mode. The experiments shows that not including sensor bias and scale factor uncertainty is very detrimental to the accuracy of the simulation results.

A new mechatronic assistance system for the neurosurgical operating theatre: implementation, assessment of accuracy and application concepts.

Science.gov (United States)

Rachinger, Jens; Bumm, Klaus; Wurm, Jochen; Bohr, Christopher; Nissen, Urs; Dannenmann, Tim; Buchfelder, Michael; Iro, Heinrich; Nimsky, Christopher

2007-01-01

To introduce a new robotic system to the field of neurosurgery and report on a preliminary assessment of accuracy as well as on envisioned application concepts. Based on experience with another system (Evolution 1, URS Inc., Schwerin, Germany), technical advancements are discussed. The basic module is an industrial 6 degrees of freedom robotic arm with a modified control element. The system combines frameless stereotaxy, robotics, and endoscopy. The robotic reproducibility error and the overall error were evaluated. For accuracy testing CT markers were placed on a cadaveric head and pinpointed with the robot's tool tip, both fully automated and telemanipulatory. Applicability in a clinical setting, user friendliness, safety and flexibility were assessed. The new system is suitable for use in the neurosurgical operating theatre. Hard- and software are user-friendly and flexible. The mean reproducibility error was 0.052-0.062 mm, the mean overall error was 0.816 mm. The system is less cumbersome and much easier to use than the Evolution 1. With its user-friendly interface and reliable safety features, its high application accuracy and flexibility, the new system is a versatile robotic platform for various neurosurgical applications. Adaptations for different applications are currently being realized. Copyright (c) 2007 S. Karger AG, Basel.

How could the replica method improve accuracy of performance assessment of channel coding?

Energy Technology Data Exchange (ETDEWEB)

Kabashima, Yoshiyuki [Department of Computational Intelligence and Systems Science, Tokyo Institute of technology, Yokohama 226-8502 (Japan)], E-mail: kaba@dis.titech.ac.jp

2009-12-01

We explore the relation between the techniques of statistical mechanics and information theory for assessing the performance of channel coding. We base our study on a framework developed by Gallager in IEEE Trans. Inform. Theory IT-11, 3 (1965), where the minimum decoding error probability is upper-bounded by an average of a generalized Chernoff's bound over a code ensemble. We show that the resulting bound in the framework can be directly assessed by the replica method, which has been developed in statistical mechanics of disordered systems, whereas in Gallager's original methodology further replacement by another bound utilizing Jensen's inequality is necessary. Our approach associates a seemingly ad hoc restriction with respect to an adjustable parameter for optimizing the bound with a phase transition between two replica symmetric solutions, and can improve the accuracy of performance assessments of general code ensembles including low density parity check codes, although its mathematical justification is still open.

Point-of-care echocardiography in simulation-based education and assessment.

Science.gov (United States)

Amini, Richard; Stolz, Lori A; Javedani, Parisa P; Gaskin, Kevin; Baker, Nicola; Ng, Vivienne; Adhikari, Srikar

2016-01-01

Emergency medicine milestones released by the Accreditation Council for Graduate Medical Education require residents to demonstrate competency in bedside ultrasound (US). The acquisition of these skills necessitates a combination of exposure to clinical pathology, hands-on US training, and feedback. We describe a novel simulation-based educational and assessment tool designed to evaluate emergency medicine residents' competency in point-of-care echocardiography for evaluation of a hypotensive patient with chest pain using bedside US. This was a cross-sectional study conducted at an academic medical center. A simulation-based module was developed to teach and assess the use of point-of-care echocardiography in the evaluation of the hypotensive patient. The focus of this module was sonographic imaging of cardiac pathology, and this focus was incorporated in all components of the session: asynchronous learning, didactic lecture, case-based learning, and hands-on stations. A total of 52 residents with varying US experience participated in this study. Questions focused on knowledge assessment demonstrated improvement across the postgraduate year (PGY) of training. Objective standardized clinical examination evaluation demonstrated improvement between PGY I and PGY III; however, it was noted that there was a small dip in hands-on scanning skills during the PGY II. Clinical diagnosis and management skills also demonstrated incremental improvement across the PGY of training. The 1-day, simulation-based US workshop was an effective educational and assessment tool at our institution.

Accuracy Of Stereometry In Assessing Orthognathic Surgery

Science.gov (United States)

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.

The geometric accuracy of frameless stereotactic radiosurgery using a 6D robotic couch system

Energy Technology Data Exchange (ETDEWEB)

Takakura, T; Nakata, M; Yano, S; Fujimoto, T [Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto (Japan); Mizowaki, T; Miyabe, Y; Nakamura, M; Hiraoka, M [Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto (Japan)], E-mail: toru1@kuhp.kyoto-u.ac.jp

2010-01-07

The aim of this paper is to assess the overall geometric accuracy of the Novalis system using the Robotic Tilt Module in terms of the uncertainty in frameless stereotactic radiotherapy. We analyzed the following three metrics: (1) the correction accuracy of the robotic couch, (2) the uncertainty of the isocenter position with gantry and couch rotation, and (3) the shift in position between the isocenter and central point detected with the ExacTrac x-ray system. Based on the concept of uncertainty, the overall accuracy was calculated from these values. The accuracy in positional correction with the robotic couch was 0.07 {+-} 0.22 mm, the positional shift of the isocenter associated with gantry rotation was 0.35 mm, the positional shift of the isocenter associated with couch rotation was 0.38 mm and the difference in position between the isocenter and the ExacTrac x-ray system was 0.30 mm. The accuracy of intracranial stereotactic radiosurgery with the Novalis system in our clinic was 0.31 {+-} 0.77 mm. The overall geometric accuracy based on the concept of uncertainty was 0.31 {+-} 0.77 mm, which is within the tolerance given in the American Association of Physicists in Medicine report no. 54.

The geometric accuracy of frameless stereotactic radiosurgery using a 6D robotic couch system

International Nuclear Information System (INIS)

Takakura, T; Nakata, M; Yano, S; Fujimoto, T; Mizowaki, T; Miyabe, Y; Nakamura, M; Hiraoka, M

2010-01-01

The aim of this paper is to assess the overall geometric accuracy of the Novalis system using the Robotic Tilt Module in terms of the uncertainty in frameless stereotactic radiotherapy. We analyzed the following three metrics: (1) the correction accuracy of the robotic couch, (2) the uncertainty of the isocenter position with gantry and couch rotation, and (3) the shift in position between the isocenter and central point detected with the ExacTrac x-ray system. Based on the concept of uncertainty, the overall accuracy was calculated from these values. The accuracy in positional correction with the robotic couch was 0.07 ± 0.22 mm, the positional shift of the isocenter associated with gantry rotation was 0.35 mm, the positional shift of the isocenter associated with couch rotation was 0.38 mm and the difference in position between the isocenter and the ExacTrac x-ray system was 0.30 mm. The accuracy of intracranial stereotactic radiosurgery with the Novalis system in our clinic was 0.31 ± 0.77 mm. The overall geometric accuracy based on the concept of uncertainty was 0.31 ± 0.77 mm, which is within the tolerance given in the American Association of Physicists in Medicine report no. 54.

An assessment of the accuracy of visual diagnosis of meconium-stained amniotic fluid

International Nuclear Information System (INIS)

Sanlialp, C.; Caglar, G.S.; Tapisiz, O.L.; Avsar, A.F.

2004-01-01

Objective: The assessment of meconium content in the amniotic fluid depends on visual observation by clinicians at the bedside. The aim of the present study was to compare visual evaluation of meconium-stained amniotic fluid with spectrophotometer evaluation. Study Design: Ten gram of meconium was added to 100 ml of amniotic fluid and mixed. The solution was serially two-fold diluted with amniotic fluid. The serially diluted tubes' absorbance spectrum was measured at 420 nm and thus a standard scale was established. Ninety five samples of meconium- stained amniotic fluid were collected from labouring women and the grade of meconium was deter- mined visually at the bedside. The samples' absorbance spectrum was measured at 420 nm and recorded. Spectrophotometer was considered gold standard and the ranges of optical density in the standard scale was used to test the accuracy of visual categorization of the samples. In the statistical analysis chi-square test was used and significance was p<0.05. Results: The accuracy rate of visual diagnosis of meconium-stained amniotic fluid were found as statistically significant (accuracy rate=54.74%, p<0.001). Visual evaluation was correct in 19.4% of thin, 53.1 % of moderate and 90.6% of thick meconium samples when examined with spectrophotometer. Conclusion: Visually diagnosed thin meconium can be moderate or thick meconium when examined objectively. The visual diagnosis at bedside is not always reliable and should be replaced with an objective method like spectrophotometry. (author)

AECB staff annual assessment of the Point Lepreau Nuclear Generating Station

International Nuclear Information System (INIS)

1997-06-01

The Atomic Energy Control Board is the independent federal agency that controls all nuclear activities in Canada. A major use of nuclear energy in Canada is electricity production. The AECB assesses every station's performance against legal requirements, including the conditions in the operating licence. Each station is inspected and all aspects of the station's operation and management is reviewed. This report is the AECB staff assessment of reactor safety at the Point Lepreau Generating Station in 1996. Point Lepreau operated safely but the worsening trends in NB Power's safety performance leads to the conclusion that urgent action is required. NB Power is required to report formally to the AECB on progress with measures to improve safety management every six months. Further licensing action will be taken on NB Power if it fails to make the improvements

Assessing accuracy of genotype imputation in American Indians.

Directory of Open Access Journals (Sweden)

Alka Malhotra

Full Text Available Genotype imputation is commonly used in genetic association studies to test untyped variants using information on linkage disequilibrium (LD with typed markers. Imputing genotypes requires a suitable reference population in which the LD pattern is known, most often one selected from HapMap. However, some populations, such as American Indians, are not represented in HapMap. In the present study, we assessed accuracy of imputation using HapMap reference populations in a genome-wide association study in Pima Indians.Data from six randomly selected chromosomes were used. Genotypes in the study population were masked (either 1% or 20% of SNPs available for a given chromosome. The masked genotypes were then imputed using the software Markov Chain Haplotyping Algorithm. Using four HapMap reference populations, average genotype error rates ranged from 7.86% for Mexican Americans to 22.30% for Yoruba. In contrast, use of the original Pima Indian data as a reference resulted in an average error rate of 1.73%.Our results suggest that the use of HapMap reference populations results in substantial inaccuracy in the imputation of genotypes in American Indians. A possible solution would be to densely genotype or sequence a reference American Indian population.

ACS Photometric Zero Point Verification

Science.gov (United States)

Dolphin, Andrew

2003-07-01

The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes in the Johnson filters. The reason for this is that ACS observations of excellent ground-based standard fields, such as the omega Cen field used for WFPC2 calibrations, have not been obtained. Instead, the ACS photometric calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS broadband images of the omega Cen standard field with both the WFC and HRC. This will permit the direct determination of the ACS transformations, and is expected to double the accuracy to which the ACS zero points are known. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager.

Northeast Puerto Rico and Culebra Island Accuracy Assessment Points - 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater photos and videos taken in shallow water (0-35m) benthic habitats surrounding Northeast Puerto Rico and Culebra...

DIRECT GEOREFERENCING : A NEW STANDARD IN PHOTOGRAMMETRY FOR HIGH ACCURACY MAPPING

Directory of Open Access Journals (Sweden)

A. Rizaldy

2012-07-01

Full Text Available Direct georeferencing is a new method in photogrammetry, especially in the digital camera era. Theoretically, this method does not require ground control points (GCP and the Aerial Triangulation (AT, to process aerial photography into ground coordinates. Compared with the old method, this method has three main advantages: faster data processing, simple workflow and less expensive project, at the same accuracy. Direct georeferencing using two devices, GPS and IMU. GPS recording the camera coordinates (X, Y, Z, and IMU recording the camera orientation (omega, phi, kappa. Both parameters merged into Exterior Orientation (EO parameter. This parameters required for next steps in the photogrammetric projects, such as stereocompilation, DSM generation, orthorectification and mosaic. Accuracy of this method was tested on topographic map project in Medan, Indonesia. Large-format digital camera Ultracam X from Vexcel is used, while the GPS / IMU is IGI AeroControl. 19 Independent Check Point (ICP were used to determine the accuracy. Horizontal accuracy is 0.356 meters and vertical accuracy is 0.483 meters. Data with this accuracy can be used for 1:2.500 map scale project.

Accuracy assessment of the National Forest Inventory map of Mexico: sampling designs and the fuzzy characterization of landscapes

Directory of Open Access Journals (Sweden)

Stéphane Couturier

2009-10-01

Full Text Available There is no record so far in the literature of a comprehensive method to assess the accuracy of regional scale Land Cover/ Land Use (LCLU maps in the sub-tropical belt. The elevated biodiversity and the presence of highly fragmented classes hamper the use of sampling designs commonly employed in previous assessments of mainly temperate zones. A sampling design for assessing the accuracy of the Mexican National Forest Inventory (NFI map at community level is presented. A pilot study was conducted on the Cuitzeo Lake watershed region covering 400 000 ha of the 2000 Landsat-derived map. Various sampling designs were tested in order to find a trade-off between operational costs, a good spatial distribution of the sample and the inclusion of all scarcely distributed classes (‘rare classes’. A two-stage sampling design where the selection of Primary Sampling Units (PSU was done under separate schemes for commonly and scarcely distributed classes, showed best characteristics. A total of 2 023 punctual secondary sampling units were verified against their NFI map label. Issues regarding the assessment strategy and trends of class confusions are devised.

Accounting for professionalism: an innovative point system to assess resident professionalism

Directory of Open Access Journals (Sweden)

Gary L. Malakoff

2014-04-01

Full Text Available Background: Professionalism is a core competency for residency required by the Accreditation Council of Graduate Medical Education. We sought a means to objectively assess professionalism among internal medicine and transitional year residents. Innovation: We established a point system to document unprofessional behaviors demonstrated by internal medicine and transitional year residents along with opportunities to redeem such negative points by deliberate positive professional acts. The intent of the policy is to assist residents in becoming aware of what constitutes unprofessional behavior and to provide opportunities for remediation by accruing positive points. A committee of core faculty and department leadership including the program director and clinic nurse manager determines professionalism points assigned. Negative points might be awarded for tardiness to mandatory or volunteered for events without a valid excuse, late evaluations or other paperwork required by the department, non-attendance at meetings prepaid by the department, and inappropriate use of personal days or leave. Examples of actions through which positive points can be gained to erase negative points include delivery of a mentored pre-conference talk, noon conference, medical student case/shelf review session, or a written reflection. Results: Between 2009 and 2012, 83 residents have trained in our program. Seventeen categorical internal medicine and two transitional year residents have been assigned points. A total of 55 negative points have been assigned and 19 points have been remediated. There appears to be a trend of fewer negative points and more positive points being assigned over each of the past three academic years. Conclusion: Commitment to personal professional behavior is a lifelong process that residents must commit to during their training. A professionalism policy, which employs a point system, has been instituted in our programs and may be a novel tool to

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Palmyra, Pacific Remote Island Areas in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Jarvis, Pacific Remote Island Areas in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Kingman, Pacific Remote Island Areas in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Johnston, Pacific Remote Island Areas in 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Pearl & Hermes, Northwestern Hawaiian Islands in 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

A Survey on the Accuracy of Radiovisiography in the Assessment of Interproximal Intrabony Defects

Directory of Open Access Journals (Sweden)

A.R. Talaiepour

2005-03-01

Full Text Available Statement of problem: Digital measurement of RVG may improve diagnostic interpretation of radiographs in terms of accuracy, although it has been shown that validity of linear measurements of interproximal bone loss could not be improved by basic digital manipulations.Purpose: The aim of this study was to evaluate the accuracy of RadioVisioGraphy (RVG in the linear measurement of interproximal bone loss in intrabony defects.Materials and Methods: Thirty two radiographs of 56 periodontally diseased teeth exhibiting interproximal intrabony defects were obtained by a standardized RVG technique and Intrabony defect depths were determined by linear measurement analysis of RVG. The following four distances were assessed intrasurgically: the cemento enamel junction (CEJ to the alveolar crest, the CEJ to the deepest extention of the bony defect (BD, the occlusal plane to the BD and the OP to the AC. Comparison between RVG measures and intrasurgical estimates were performed using paired t-test.Results: The radiographic measurements overestimated interproximal bone loss as compared to the intrasurgical measurements: CEJ-BD measurement by RVG was 6.803±3.589 mm and intra-surgically was 6.492±3.492 (P<0.000. No statistically significant difference was seen between CEJ and occlusal references in RVG measurements (P<0.729.Conclusion: Radiographic assessment by either the CEJ or occlusal references overestimated bone loss as compared to the intrasurgical gold standard.

Biased binomial assessment of cross-validated estimation of classification accuracies illustrated in diagnosis predictions

Directory of Open Access Journals (Sweden)

Quentin Noirhomme

2014-01-01

Full Text Available Multivariate classification is used in neuroimaging studies to infer brain activation or in medical applications to infer diagnosis. Their results are often assessed through either a binomial or a permutation test. Here, we simulated classification results of generated random data to assess the influence of the cross-validation scheme on the significance of results. Distributions built from classification of random data with cross-validation did not follow the binomial distribution. The binomial test is therefore not adapted. On the contrary, the permutation test was unaffected by the cross-validation scheme. The influence of the cross-validation was further illustrated on real-data from a brain–computer interface experiment in patients with disorders of consciousness and from an fMRI study on patients with Parkinson disease. Three out of 16 patients with disorders of consciousness had significant accuracy on binomial testing, but only one showed significant accuracy using permutation testing. In the fMRI experiment, the mental imagery of gait could discriminate significantly between idiopathic Parkinson's disease patients and healthy subjects according to the permutation test but not according to the binomial test. Hence, binomial testing could lead to biased estimation of significance and false positive or negative results. In our view, permutation testing is thus recommended for clinical application of classification with cross-validation.

Ultra-wideband ranging precision and accuracy

International Nuclear Information System (INIS)

MacGougan, Glenn; O'Keefe, Kyle; Klukas, Richard

2009-01-01

This paper provides an overview of ultra-wideband (UWB) in the context of ranging applications and assesses the precision and accuracy of UWB ranging from both a theoretical perspective and a practical perspective using real data. The paper begins with a brief history of UWB technology and the most current definition of what constitutes an UWB signal. The potential precision of UWB ranging is assessed using Cramer–Rao lower bound analysis. UWB ranging methods are described and potential error sources are discussed. Two types of commercially available UWB ranging radios are introduced which are used in testing. Actual ranging accuracy is assessed from line-of-sight testing under benign signal conditions by comparison to high-accuracy electronic distance measurements and to ranges derived from GPS real-time kinematic positioning. Range measurements obtained in outdoor testing with line-of-sight obstructions and strong reflection sources are compared to ranges derived from classically surveyed positions. The paper concludes with a discussion of the potential applications for UWB ranging

Precise orbit determination and point positioning using GPS, Glonass, Galileo and BeiDou

Directory of Open Access Journals (Sweden)

Tegedor J.

2014-04-01

Full Text Available State of the art Precise Point Positioning (PPP is currently based on dual-frequency processing of GPS and Glonass navigation systems. The International GNSS Service (IGS is routinely providing the most accurate orbit and clock products for these constellations, allowing point positioning at centimeter-level accuracy. At the same time, the GNSS landscape is evolving rapidly, with the deployment of new constellations, such as Galileo and BeiDou. The BeiDou constellation currently consists of 14 operational satellites, and the 4 Galileo In-Orbit Validation (IOV satellites are transmitting initial Galileo signals. This paper focuses on the integration of Galileo and BeiDou in PPP, together with GPS and Glonass. Satellite orbits and clocks for all constellations are generated using a network adjustment with observation data collected by the IGS Multi-GNSS Experiment (MGEX, as well as from Fugro proprietary reference station network. The orbit processing strategy is described, and orbit accuracy for Galileo and BeiDou is assessed via orbit overlaps, for different arc lengths. Kinematic post-processed multi-GNSS positioning results are presented. The benefits of multiconstellation PPP are discussed in terms of enhanced availability and positioning accuracy.

Pre-analytical Factors Influence Accuracy of Urine Spot Iodine Assessment in Epidemiological Surveys.

Science.gov (United States)

Doggui, Radhouene; El Ati-Hellal, Myriam; Traissac, Pierre; El Ati, Jalila

2018-03-26

Urinary iodine concentration (UIC) is commonly used to assess iodine status of subjects in epidemiological surveys. As pre-analytical factors are an important source of measurement error and studies about this phase are scarce, our objective was to assess the influence of urine sampling conditions on UIC, i.e., whether the child ate breakfast or not, urine void rank of the day, and time span between last meal and urine collection. A nationwide, two-stage, stratified, cross-sectional study including 1560 children (6-12 years) was performed in 2012. UIC was determined by the Sandell-Kolthoff method. Pre-analytical factors were assessed from children's mothers by using a questionnaire. Association between iodine status and pre-analytical factors were adjusted for one another and socio-economic characteristics by multivariate linear and multinomial regression models (RPR: relative prevalence ratios). Skipping breakfast prior to morning urine sampling decreased UIC by 40 to 50 μg/L and the proportion of UIC analytical factors is a key step toward improving accuracy and comparability of survey results for assessing iodine status from spot urine samples. These recommendations have to be evaluated by future research.

Comparison of Single and Multi-Scale Method for Leaf and Wood Points Classification from Terrestrial Laser Scanning Data

Science.gov (United States)

Wei, Hongqiang; Zhou, Guiyun; Zhou, Junjie

2018-04-01

The classification of leaf and wood points is an essential preprocessing step for extracting inventory measurements and canopy characterization of trees from the terrestrial laser scanning (TLS) data. The geometry-based approach is one of the widely used classification method. In the geometry-based method, it is common practice to extract salient features at one single scale before the features are used for classification. It remains unclear how different scale(s) used affect the classification accuracy and efficiency. To assess the scale effect on the classification accuracy and efficiency, we extracted the single-scale and multi-scale salient features from the point clouds of two oak trees of different sizes and conducted the classification on leaf and wood. Our experimental results show that the balanced accuracy of the multi-scale method is higher than the average balanced accuracy of the single-scale method by about 10 % for both trees. The average speed-up ratio of single scale classifiers over multi-scale classifier for each tree is higher than 30.

Assessing Genomic Selection Prediction Accuracy in a Dynamic Barley Breeding Population

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A. H. Sallam

2015-03-01

Full Text Available Prediction accuracy of genomic selection (GS has been previously evaluated through simulation and cross-validation; however, validation based on progeny performance in a plant breeding program has not been investigated thoroughly. We evaluated several prediction models in a dynamic barley breeding population comprised of 647 six-row lines using four traits differing in genetic architecture and 1536 single nucleotide polymorphism (SNP markers. The breeding lines were divided into six sets designated as one parent set and five consecutive progeny sets comprised of representative samples of breeding lines over a 5-yr period. We used these data sets to investigate the effect of model and training population composition on prediction accuracy over time. We found little difference in prediction accuracy among the models confirming prior studies that found the simplest model, random regression best linear unbiased prediction (RR-BLUP, to be accurate across a range of situations. In general, we found that using the parent set was sufficient to predict progeny sets with little to no gain in accuracy from generating larger training populations by combining the parent set with subsequent progeny sets. The prediction accuracy ranged from 0.03 to 0.99 across the four traits and five progeny sets. We explored characteristics of the training and validation populations (marker allele frequency, population structure, and linkage disequilibrium, LD as well as characteristics of the trait (genetic architecture and heritability, . Fixation of markers associated with a trait over time was most clearly associated with reduced prediction accuracy for the mycotoxin trait DON. Higher trait in the training population and simpler trait architecture were associated with greater prediction accuracy.

Diagnostic accuracy of refractometer and Brix refractometer to assess failure of passive transfer in calves: protocol for a systematic review and meta-analysis.

Science.gov (United States)

Buczinski, S; Fecteau, G; Chigerwe, M; Vandeweerd, J M

2016-06-01

Calves are highly dependent of colostrum (and antibody) intake because they are born agammaglobulinemic. The transfer of passive immunity in calves can be assessed directly by dosing immunoglobulin G (IgG) or by refractometry or Brix refractometry. The latter are easier to perform routinely in the field. This paper presents a protocol for a systematic review meta-analysis to assess the diagnostic accuracy of refractometry or Brix refractometry versus dosage of IgG as a reference standard test. With this review protocol we aim to be able to report refractometer and Brix refractometer accuracy in terms of sensitivity and specificity as well as to quantify the impact of any study characteristic on test accuracy.

Comparison of Point Placement by Veterinary Professionals with Different Levels of Acupuncture Training in a Canine Cadaver Model.

Science.gov (United States)

Yang, Toni; Shmalberg, Justin; Hochman, Lindsay; Miscioscia, Erin; Brumby, Meghan; McKenna, Kelsey; Roth, Amber

2017-10-01

Veterinary acupuncture is becoming increasingly implemented for various disease processes, with growing numbers of veterinarians pursuing advanced training to meet the rising demand for this relatively new intervention. Accurate acupoint placement remains challenging, with individual practitioners relying on varying methods of point identification, often compounded by the transpositional nature of points for companion animals. The aim of this study was to assess for differences in acupuncture needle placement of select points between veterinary professionals with three different levels of acupuncture training in an academic teaching environment. Seven participants placed a total of six acupoints on a canine cadaver. Digital radiography was used to document each participant's point placement. Each participant's point location was then compared to a control "correct" point, and the distance between the two points was measured. A significant difference in placement accuracy was identified between the participants when grouped by training level (p = 0.03). These results indicate that veterinary patients receiving acupuncture treatment from veterinarians with different levels of training may subsequently experience varying effects, although further studies are warranted on more specific acupoint description as well as the clinical implications of needle placement accuracy. Copyright © 2017. Published by Elsevier B.V.

Real-Time Tropospheric Product Establishment and Accuracy Assessment in China

Science.gov (United States)

Chen, M.; Guo, J.; Wu, J.; Song, W.; Zhang, D.

2018-04-01

Tropospheric delay has always been an important issue in Global Navigation Satellite System (GNSS) processing. Empirical tropospheric delay models are difficult to simulate complex and volatile atmospheric environments, resulting in poor accuracy of the empirical model and difficulty in meeting precise positioning demand. In recent years, some scholars proposed to establish real-time tropospheric product by using real-time or near-real-time GNSS observations in a small region, and achieved some good results. This paper uses real-time observing data of 210 Chinese national GNSS reference stations to estimate the tropospheric delay, and establishes ZWD grid model in the country wide. In order to analyze the influence of tropospheric grid product on wide-area real-time PPP, this paper compares the method of taking ZWD grid product as a constraint with the model correction method. The results show that the ZWD grid product estimated based on the national reference stations can improve PPP accuracy and convergence speed. The accuracy in the north (N), east (E) and up (U) direction increase by 31.8 %,15.6 % and 38.3 %, respectively. As with the convergence speed, the accuracy of U direction experiences the most improvement.

A Method for Assessing Ground-Truth Accuracy of the 5DCT Technique

International Nuclear Information System (INIS)

Dou, Tai H.; Thomas, David H.; O'Connell, Dylan P.; Lamb, James M.; Lee, Percy; Low, Daniel A.

2015-01-01

Purpose: To develop a technique that assesses the accuracy of the breathing phase-specific volume image generation process by patient-specific breathing motion model using the original free-breathing computed tomographic (CT) scans as ground truths. Methods: Sixteen lung cancer patients underwent a previously published protocol in which 25 free-breathing fast helical CT scans were acquired with a simultaneous breathing surrogate. A patient-specific motion model was constructed based on the tissue displacements determined by a state-of-the-art deformable image registration. The first image was arbitrarily selected as the reference image. The motion model was used, along with the free-breathing phase information of the original 25 image datasets, to generate a set of deformation vector fields that mapped the reference image to the 24 nonreference images. The high-pitch helically acquired original scans served as ground truths because they captured the instantaneous tissue positions during free breathing. Image similarity between the simulated and the original scans was assessed using deformable registration that evaluated the pointwise discordance throughout the lungs. Results: Qualitative comparisons using image overlays showed excellent agreement between the simulated images and the original images. Even large 2-cm diaphragm displacements were very well modeled, as was sliding motion across the lung–chest wall boundary. The mean error across the patient cohort was 1.15 ± 0.37 mm, and the mean 95th percentile error was 2.47 ± 0.78 mm. Conclusion: The proposed ground truth–based technique provided voxel-by-voxel accuracy analysis that could identify organ-specific or tumor-specific motion modeling errors for treatment planning. Despite a large variety of breathing patterns and lung deformations during the free-breathing scanning session, the 5-dimensionl CT technique was able to accurately reproduce the original helical CT scans, suggesting its

A Method for Assessing Ground-Truth Accuracy of the 5DCT Technique

Energy Technology Data Exchange (ETDEWEB)

Dou, Tai H., E-mail: tdou@mednet.ucla.edu; Thomas, David H.; O' Connell, Dylan P.; Lamb, James M.; Lee, Percy; Low, Daniel A.

2015-11-15

Purpose: To develop a technique that assesses the accuracy of the breathing phase-specific volume image generation process by patient-specific breathing motion model using the original free-breathing computed tomographic (CT) scans as ground truths. Methods: Sixteen lung cancer patients underwent a previously published protocol in which 25 free-breathing fast helical CT scans were acquired with a simultaneous breathing surrogate. A patient-specific motion model was constructed based on the tissue displacements determined by a state-of-the-art deformable image registration. The first image was arbitrarily selected as the reference image. The motion model was used, along with the free-breathing phase information of the original 25 image datasets, to generate a set of deformation vector fields that mapped the reference image to the 24 nonreference images. The high-pitch helically acquired original scans served as ground truths because they captured the instantaneous tissue positions during free breathing. Image similarity between the simulated and the original scans was assessed using deformable registration that evaluated the pointwise discordance throughout the lungs. Results: Qualitative comparisons using image overlays showed excellent agreement between the simulated images and the original images. Even large 2-cm diaphragm displacements were very well modeled, as was sliding motion across the lung–chest wall boundary. The mean error across the patient cohort was 1.15 ± 0.37 mm, and the mean 95th percentile error was 2.47 ± 0.78 mm. Conclusion: The proposed ground truth–based technique provided voxel-by-voxel accuracy analysis that could identify organ-specific or tumor-specific motion modeling errors for treatment planning. Despite a large variety of breathing patterns and lung deformations during the free-breathing scanning session, the 5-dimensionl CT technique was able to accurately reproduce the original helical CT scans, suggesting its

Reduction Assessment of Agricultural Non-Point Source Pollutant Loading

OpenAIRE

Fu, YiCheng; Zang, Wenbin; Zhang, Jian; Wang, Hongtao; Zhang, Chunling; Shi, Wanli

2018-01-01

NPS (Non-point source) pollution has become a key impact element to watershed environment at present. With the development of technology, application of models to control NPS pollution has become a very common practice for resource management and Pollutant reduction control in the watershed scale of China. The SWAT (Soil and Water Assessment Tool) model is a semi-conceptual model, which was put forward to estimate pollutant production & the influences on water quantity-quality under different...

3D Documentation of Archaeological Excavations Using Image-Based Point Cloud

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Umut Ovalı

2017-03-01

Full Text Available Rapid progress in digital technology enables us to create three-dimensional models using digital images. Low cost, time efficiency and accurate results of this method put to question if this technique can be an alternative to conventional documentation techniques, which generally are 2D orthogonal drawings. Accurate and detailed 3D models of archaeological features have potential for many other purposes besides geometric documentation. This study presents a recent image-based three-dimensional registration technique employed in 2013 at one of the ancient city in Turkey, using “Structure from Motion” (SfM algorithms. A commercial software is applied to investigate whether this method can be used as an alternative to other techniques. Mesh model of the some section of the excavation section of the site were produced using point clouds were produced from the digital photographs. Accuracy assessment of the produced model was realized using the comparison of the directly measured coordinates of the ground control points with produced from model. Obtained results presented that the accuracy is around 1.3 cm.

[Dancing with Pointe Shoes: Characteristics and Assessment Criteria for Pointe Readiness].

Science.gov (United States)

Wanke, Eileen M; Exner-Grave, Elisabeth

2017-12-01

Training with pointe shoes is an integral part of professional dance education and ambitious hobby dancing. Pointe shoes - developed more than hundred years ago and almost unaltered since then - are highly specific and strike a balance between aesthetics, function, protection, and health care. Therefore, pointe readiness should be tested prior to all dance training or career training. Medical specialists are often confronted with this issue. Specific anatomical dance technique-orientated general conditional and coordinative preconditions as well as dance-technical prerequisites must be met by pointe readiness tests in order to keep traumatic injuries or long-term damage at a minimum. In addition to a (training) history, medical counselling sessions have come to include various tests that enable a reliable decision for or against pointe work. This article suggests adequate testing procedures (STT TEST), taking account of professional dancing as well as hobby dancing. © Georg Thieme Verlag KG Stuttgart · New York.

Self-Assessment: The Disconnect between Research and Rhetoric

Science.gov (United States)

2008-01-01

Purpose: Physical therapists are expected to engage in self-assessment in order to ensure competent practice and to identify appropriate professional development activities. Summary of Key Points: This paper reviews the current literature on the accuracy and role of self-assessment in physical therapy. Current literature indicating that self-assessment cannot be conducted with any degree of accuracy is discussed, and a proposed reformulation of the concept of self-assessment is presented. Recommendations: Practical strategies are offered for clinicians to improve the potential for obtaining reliable and valid information about their own clinical performance to guide the selection of appropriate professional development activities and to promote the provision of competent patient care. PMID:20145775

Accuracy of Inferior Vena Cava Ultrasound for Predicting Dehydration in Children with Acute Diarrhea in Resource-Limited Settings.

Science.gov (United States)

Modi, Payal; Glavis-Bloom, Justin; Nasrin, Sabiha; Guy, Allysia; Chowa, Erika P; Dvor, Nathan; Dworkis, Daniel A; Oh, Michael; Silvestri, David M; Strasberg, Stephen; Rege, Soham; Noble, Vicki E; Alam, Nur H; Levine, Adam C

2016-01-01

Although dehydration from diarrhea is a leading cause of morbidity and mortality in children under five, existing methods of assessing dehydration status in children have limited accuracy. To assess the accuracy of point-of-care ultrasound measurement of the aorta-to-IVC ratio as a predictor of dehydration in children. A prospective cohort study of children under five years with acute diarrhea was conducted in the rehydration unit of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). Ultrasound measurements of aorta-to-IVC ratio and dehydrated weight were obtained on patient arrival. Percent weight change was monitored during rehydration to classify children as having "some dehydration" with weight change 3-9% or "severe dehydration" with weight change > 9%. Logistic regression analysis and Receiver-Operator Characteristic (ROC) curves were used to evaluate the accuracy of aorta-to-IVC ratio as a predictor of dehydration severity. 850 children were enrolled, of which 771 were included in the final analysis. Aorta to IVC ratio was a significant predictor of the percent dehydration in children with acute diarrhea, with each 1-point increase in the aorta to IVC ratio predicting a 1.1% increase in the percent dehydration of the child. However, the area under the ROC curve (0.60), sensitivity (67%), and specificity (49%), for predicting severe dehydration were all poor. Point-of-care ultrasound of the aorta-to-IVC ratio was statistically associated with volume status, but was not accurate enough to be used as an independent screening tool for dehydration in children under five years presenting with acute diarrhea in a resource-limited setting.

Accuracy of Inferior Vena Cava Ultrasound for Predicting Dehydration in Children with Acute Diarrhea in Resource-Limited Settings.

Directory of Open Access Journals (Sweden)

Payal Modi

Full Text Available Although dehydration from diarrhea is a leading cause of morbidity and mortality in children under five, existing methods of assessing dehydration status in children have limited accuracy.To assess the accuracy of point-of-care ultrasound measurement of the aorta-to-IVC ratio as a predictor of dehydration in children.A prospective cohort study of children under five years with acute diarrhea was conducted in the rehydration unit of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b. Ultrasound measurements of aorta-to-IVC ratio and dehydrated weight were obtained on patient arrival. Percent weight change was monitored during rehydration to classify children as having "some dehydration" with weight change 3-9% or "severe dehydration" with weight change > 9%. Logistic regression analysis and Receiver-Operator Characteristic (ROC curves were used to evaluate the accuracy of aorta-to-IVC ratio as a predictor of dehydration severity.850 children were enrolled, of which 771 were included in the final analysis. Aorta to IVC ratio was a significant predictor of the percent dehydration in children with acute diarrhea, with each 1-point increase in the aorta to IVC ratio predicting a 1.1% increase in the percent dehydration of the child. However, the area under the ROC curve (0.60, sensitivity (67%, and specificity (49%, for predicting severe dehydration were all poor.Point-of-care ultrasound of the aorta-to-IVC ratio was statistically associated with volume status, but was not accurate enough to be used as an independent screening tool for dehydration in children under five years presenting with acute diarrhea in a resource-limited setting.

Proposed Testing to Assess the Accuracy of Glass-To-Metal Seal Stress Analyses.

Energy Technology Data Exchange (ETDEWEB)

Chambers, Robert S.; Emery, John M; Tandon, Rajan; Antoun, Bonnie R.; Stavig, Mark E.; Newton, Clay S.; Gibson, Cory S; Bencoe, Denise N.

2014-09-01

The material characterization tests conducted on 304L VAR stainless steel and Schott 8061 glass have provided higher fidelity data for calibration of material models used in Glass - T o - Metal (GTM) seal analyses. Specifically, a Thermo - Multi - Linear Elastic Plastic ( thermo - MLEP) material model has be en defined for S S304L and the Simplified Potential Energy Clock nonlinear visc oelastic model has been calibrated for the S8061 glass. To assess the accuracy of finite element stress analyses of GTM seals, a suite of tests are proposed to provide data for comparison to mo del predictions.

Accuracy of Handheld Point-of-Care Fingertip Lactate Measurement in the Emergency Department

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Gaieski, David G

2013-02-01

Full Text Available Introduction: Early recognition of elevated lactate levels in sepsis may hasten the detection of those patients eligible for aggressive resuscitation. Point-of-care (POC testing is now increasingly available for use in the emergency department (ED. We examined the accuracy and time-saving effect of a handheld POC device for the measurement of fingertip and whole blood lactate as compared with reference laboratory testing in critically ill ED patients.Methods: A convenience sample of adult ED patients receiving serum lactate testing was prospectively enrolled at an urban, tertiary care US hospital. Consenting patients underwent fingertip POC lactate measurement with a portable device and simultaneous whole blood sampling for analysis by both the POC device and standard laboratory analyzer (‘‘reference method’’. Lactate measurements were compared by intraclass correlation (ICC and Bland and Altman plots. Differences in time to test result were compared by paired t test.Results: Twenty-four patients, 19 (79% with sepsis and 21 (88% with lactate levels below 4 mmol/L, were included from April 2005 to May 2005. Fingertip POC and whole blood POC lactate measurements each correlated tightly with the reference method (ICC ¼ 0.90 and ICC ¼ 0.92, respectively. Mean time between obtaining fingertip lactate samples and whole blood reference lactate samples was 8 6 13 minutes. Mean time between obtaining POC and reference laboratory lactate results was 65 minutes (95% confidence interval, 30–103.Conclusion: Fingertip POC lactate measurement is an accurate method to determine lactate levels in infected ED patients with normal or modestly elevated lactate values and significantly decreases time to test results. These findings should be verified in a larger, more critically ill, ED population. [West J Emerg Med. 2013;14(1:58-62.

Evaluation of spatial dependence of point spread function-based PET reconstruction using a traceable point-like 22Na source

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Taisuke Murata

2016-10-01

Full Text Available Abstract Background The point spread function (PSF of positron emission tomography (PET depends on the position across the field of view (FOV. Reconstruction based on PSF improves spatial resolution and quantitative accuracy. The present study aimed to quantify the effects of PSF correction as a function of the position of a traceable point-like 22Na source over the FOV on two PET scanners with a different detector design. Methods We used Discovery 600 and Discovery 710 (GE Healthcare PET scanners and traceable point-like 22Na sources (<1 MBq with a spherical absorber design that assures uniform angular distribution of the emitted annihilation photons. The source was moved in three directions at intervals of 1 cm from the center towards the peripheral FOV using a three-dimensional (3D-positioning robot, and data were acquired over a period of 2 min per point. The PET data were reconstructed by filtered back projection (FBP, the ordered subset expectation maximization (OSEM, OSEM + PSF, and OSEM + PSF + time-of-flight (TOF. Full width at half maximum (FWHM was determined according to the NEMA method, and total counts in regions of interest (ROI for each reconstruction were quantified. Results The radial FWHM of FBP and OSEM increased towards the peripheral FOV, whereas PSF-based reconstruction recovered the FWHM at all points in the FOV of both scanners. The radial FWHM for PSF was 30–50 % lower than that of OSEM at the center of the FOV. The accuracy of PSF correction was independent of detector design. Quantitative values were stable across the FOV in all reconstruction methods. The effect of TOF on spatial resolution and quantitation accuracy was less noticeable. Conclusions The traceable 22Na point-like source allowed the evaluation of spatial resolution and quantitative accuracy across the FOV using different reconstruction methods and scanners. PSF-based reconstruction reduces dependence of the spatial resolution on the

The spatial accuracy of geographic ecological momentary assessment (GEMA): Error and bias due to subject and environmental characteristics.

Science.gov (United States)

Mennis, Jeremy; Mason, Michael; Ambrus, Andreea; Way, Thomas; Henry, Kevin

2017-09-01

Geographic ecological momentary assessment (GEMA) combines ecological momentary assessment (EMA) with global positioning systems (GPS) and geographic information systems (GIS). This study evaluates the spatial accuracy of GEMA location data and bias due to subject and environmental data characteristics. Using data for 72 subjects enrolled in a study of urban adolescent substance use, we compared the GPS-based location of EMA responses in which the subject indicated they were at home to the geocoded home address. We calculated the percentage of EMA locations within a sixteenth, eighth, quarter, and half miles from the home, and the percentage within the same tract and block group as the home. We investigated if the accuracy measures were associated with subject demographics, substance use, and emotional dysregulation, as well as environmental characteristics of the home neighborhood. Half of all subjects had more than 88% of their EMA locations within a half mile, 72% within a quarter mile, 55% within an eighth mile, 50% within a sixteenth of a mile, 83% in the correct tract, and 71% in the correct block group. There were no significant associations with subject or environmental characteristics. Results support the use of GEMA for analyzing subjects' exposures to urban environments. Researchers should be aware of the issue of spatial accuracy inherent in GEMA, and interpret results accordingly. Understanding spatial accuracy is particularly relevant for the development of 'ecological momentary interventions' (EMI), which may depend on accurate location information, though issues of privacy protection remain a concern. Copyright © 2017 Elsevier B.V. All rights reserved.

Classification Accuracy of a Wearable Activity Tracker for Assessing Sedentary Behavior and Physical Activity in 3–5-Year-Old Children

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Wonwoo Byun

2018-03-01

Full Text Available This study examined the accuracy of the Fitbit activity tracker (FF for quantifying sedentary behavior (SB and varying intensities of physical activity (PA in 3–5-year-old children. Twenty-eight healthy preschool-aged children (Girls: 46%, Mean age: 4.8 ± 1.0 years wore the FF and were directly observed while performing a set of various unstructured and structured free-living activities from sedentary to vigorous intensity. The classification accuracy of the FF for measuring SB, light PA (LPA, moderate-to-vigorous PA (MVPA, and total PA (TPA was examined calculating Pearson correlation coefficients (r, mean absolute percent error (MAPE, Cohen’s kappa (k, sensitivity (Se, specificity (Sp, and area under the receiver operating curve (ROC-AUC. The classification accuracies of the FF (ROC-AUC were 0.92, 0.63, 0.77 and 0.92 for SB, LPA, MVPA and TPA, respectively. Similarly, values of kappa, Se, Sp and percentage of correct classification were consistently high for SB and TPA, but low for LPA and MVPA. The FF demonstrated excellent classification accuracy for assessing SB and TPA, but lower accuracy for classifying LPA and MVPA. Our findings suggest that the FF should be considered as a valid instrument for assessing time spent sedentary and overall physical activity in preschool-aged children.

Psychometric Properties and Diagnostic Accuracy of the Edinburgh Postnatal Depression Scale in a Sample of Iranian Women

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Gholam Reza Kheirabadi

2012-03-01

Full Text Available Background: Edinburgh Postnatal Depression Scale (EPDS has been used as a reliable screening tool for postpartum depression in many countries. This study aimed to assess the psychometric properties and diagnostic accuracy of the EPDS in a sample of Iranian women.Methods: Using stratified sampling 262 postpartum women (2 weeks-3 months after delivery were selected from urban and rural health center in the city of Isfahan. They were interviewed using EPDS and Hamilton depression rating scale (HDRS. Data were assessed using factor analysis, diagnosis analysis of receiver operating characteristic (ROC curve, Cronbach's alpha and Pearson correlation coefficient.Results: The age of then participants ranged 18-45 years (26.6±5.1. Based on a cut-off point of >13 for HDRS, 18.3% of the participants. The overall reliability (Cronbach's alpha of EPDS was 0.79. There was a significant correlation (r2=0.60, P value<0.01 between EPDS and HDRS. Two factor analysis showed that anhedonia and depression were two explanatory factors. At a cut-off point12 the sensitivity of the questionnaire was 78% (95% CI: 73%-83% and its specificity was 75% (95% CI: 72%-78%. Conclusion: The Persian version of the EPDS showed appropriate psychometric properties diagnostic accuracy index. It can be used by health system professionals for detection, assessment and treatment for mothers with post partum depression.

The Little Schmidy Pediatric Hospital Fall Risk Assessment Index: A diagnostic accuracy study.

Science.gov (United States)

Franck, Linda S; Gay, Caryl L; Cooper, Bruce; Ezrre, Suzanne; Murphy, Barbette; Chan, June Shu-Ling; Buick, Maureen; Meer, Carrie R

2017-03-01

Falls are among the most common potentially preventable adverse events. Current pediatric falls risk assessment methods have poor precision and accuracy. To evaluate an inpatient pediatric fall risk assessment index, known as the Little Schmidy, and describe characteristics of pediatric falls. Retrospective case control and descriptive study. The dataset included 114 reported falls and 151,678 Little Schmidy scores documented in medical records during the 5-year study period (2007-2011). Pediatric medical and surgical inpatient units of an academic medical center in the western United States. Pediatric hospital inpatients fall risk each day and night shift throughout the patient's hospitalization. Conditional fixed-effects logistic regressions were used to examine predictive relationships between Little Schmidy scores (at admission, highest prior to fall, and just prior to fall) and the patient's fall status (fell or not). The sensitivity and specificity of different cut-off scores were explored. Associations between Little Schmidy scores and patient and hospitalization factors were examined using multilevel mixed-effects logistic regression and multilevel mixed-effects ordinal logistic regression. Little Schmidy scores were significantly associated with pediatric falls (pfall risk with sensitivity of 79% and specificity of 49%. Patients with an LS4 score ≥1 were 4 times more likely to fall before the next assessment than patients with a score of 0. LS4 scores indicative of fall risk were associated with age ≥5 years, neurological diagnosis, multiple hospitalizations, and night shift, but not with sex, length of hospital stay, or hospital unit. Of the 114 reported falls, 64% involved a male patient, nearly one third (32%) involved adolescents (13-17 years), most resulted in no (59%) or mild (36%) injury, and most (54%) were related to diagnosis or clinical characteristics. For 60% of the falls, fall precautions had been implemented prior to the fall. The

Supernova pointing with low- and high-energy neutrino detectors

CERN Document Server

Tomás, R; Raffelt, Georg G; Kachelriess, M; Dighe, Amol S

2003-01-01

A future galactic SN can be located several hours before the optical explosion through the MeV-neutrino burst, exploiting the directionality of $nu$-$e$-scattering in a water Cherenkov detector such as Super-Kamiokande. We study the statistical efficiency of different methods for extracting the SN direction and identify a simple approach that is nearly optimal, yet independent of the exact SN neutrino spectra. We use this method to quantify the increase in the pointing accuracy by the addition of gadolinium to water, which tags neutrons from the inverse beta decay background. We also study the dependence of the pointing accuracy on neutrino mixing scenarios and initial spectra. We find that in the ``worst case'' scenario the pointing accuracy is $8^circ$ at 95% C.L. in the absence of tagging, which improves to $3^circ$ with a tagging efficiency of 95%. At a megaton detector, this accuracy can be as good as $0.6^circ$. A TeV-neutrino burst is also expected to be emitted contemporaneously with the SN optical ex...

A model for the two-point velocity correlation function in turbulent channel flow

International Nuclear Information System (INIS)

Sahay, A.; Sreenivasan, K.R.

1996-01-01

A relatively simple analytical expression is presented to approximate the equal-time, two-point, double-velocity correlation function in turbulent channel flow. To assess the accuracy of the model, we perform the spectral decomposition of the integral operator having the model correlation function as its kernel. Comparisons of the empirical eigenvalues and eigenfunctions with those constructed from direct numerical simulations data show good agreement. copyright 1996 American Institute of Physics

Standardization of figures and assessment procedures for DTM verticalaccuracy

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Vittorio Casella

2015-07-01

Full Text Available Digital Terrain Models (DTMs are widely used in many sectors. They play a key role in hydrological risk prevention, risk mitigation and numeric simulations. This paper deals with two questions: (i when it is stated that a DTM has a given vertical accuracy, is this assertion univocal? (ii when DTM vertical accuracy is assessed by means of checkpoints, does their location influence results? First, the paper illustrates that two vertical accuracy definitions are conceivable: Vertical Accuracy at the Nodes (VAN, the average vertical distance between the model and the terrain, evaluated at the DTM's nodes and Vertical Accuracy at the interpolated Points (VAP, in which the vertical distance is evaluated at the generic points. These two quantities are not coincident and, when they are calculated for the same DTM, different numeric values are reached. Unfortunately, the two quantities are often interchanged, but this is misleading. Second, the paper shows a simulated example of a DTM vertical accuracy assessment, highlighting that the checkpoints’ location plays a key role: when checkpoints coincide with the DTM nodes, VAN is estimated; when checkpoints are randomly located, VAP is estimated, instead. Third, an in-depth, theoretical characterization of the two considered quantities is performed, based on symbolic computation, and suitable standardization coefficients are proposed. Finally, our discussion has a well-defined frame: it doesn't deal with all the items of the DTM vertical accuracy budget, which would require a much longer essay, but only with one, usually called fundamental vertical accuracy.

INFLUENCE OF RIVER BED ELEVATION SURVEY CONFIGURATIONS AND INTERPOLATION METHODS ON THE ACCURACY OF LIDAR DTM-BASED RIVER FLOW SIMULATIONS

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J. R. Santillan

2016-09-01

Full Text Available In this paper, we investigated how survey configuration and the type of interpolation method can affect the accuracy of river flow simulations that utilize LIDAR DTM integrated with interpolated river bed as its main source of topographic information. Aside from determining the accuracy of the individually-generated river bed topographies, we also assessed the overall accuracy of the river flow simulations in terms of maximum flood depth and extent. Four survey configurations consisting of river bed elevation data points arranged as cross-section (XS, zig-zag (ZZ, river banks-centerline (RBCL, and river banks-centerline-zig-zag (RBCLZZ, and two interpolation methods (Inverse Distance-Weighted and Ordinary Kriging were considered. Major results show that the choice of survey configuration, rather than the interpolation method, has significant effect on the accuracy of interpolated river bed surfaces, and subsequently on the accuracy of river flow simulations. The RMSEs of the interpolated surfaces and the model results vary from one configuration to another, and depends on how each configuration evenly collects river bed elevation data points. The large RMSEs for the RBCL configuration and the low RMSEs for the XS configuration confirm that as the data points become evenly spaced and cover more portions of the river, the resulting interpolated surface and the river flow simulation where it was used also become more accurate. The XS configuration with Ordinary Kriging (OK as interpolation method provided the best river bed interpolation and river flow simulation results. The RBCL configuration, regardless of the interpolation algorithm used, resulted to least accurate river bed surfaces and simulation results. Based on the accuracy analysis, the use of XS configuration to collect river bed data points and applying the OK method to interpolate the river bed topography are the best methods to use to produce satisfactory river flow simulation outputs

Higher-order triangular spectral element method with optimized cubature points for seismic wavefield modeling

Science.gov (United States)

Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José

2017-05-01

The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant-Friedrichs-Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational

Dew Point modelling using GEP based multi objective optimization

OpenAIRE

Shroff, Siddharth; Dabhi, Vipul

2013-01-01

Different techniques are used to model the relationship between temperatures, dew point and relative humidity. Gene expression programming is capable of modelling complex realities with great accuracy, allowing at the same time, the extraction of knowledge from the evolved models compared to other learning algorithms. We aim to use Gene Expression Programming for modelling of dew point. Generally, accuracy of the model is the only objective used by selection mechanism of GEP. This will evolve...

Simulation assessment center in the service of the company as a factor in the accuracy and validity of the information about the employee

OpenAIRE

Borodai V.A.

2017-01-01

The article reveals the relevance of evaluation method for personnel assessment center technologies. The efficiency of the method in terms of accuracy and validity of the assessment of employees. Identified positive factors and problematic use of assessment center technology service company/

A Quantitative Point-of-Need Assay for the Assessment of Vitamin D3 Deficiency.

Science.gov (United States)

Vemulapati, S; Rey, E; O'Dell, D; Mehta, S; Erickson, D

2017-10-26

Vitamin D is necessary for the healthy growth and development of bone and muscle. Vitamin D deficiency, which is present in 42% of the US population, is often undiagnosed as symptoms may not manifest for several years and long-term deficiency has been linked to osteoporosis, diabetes and cancer. Currently the majority of vitamin D testing is performed in large-scale commercial laboratories which have high operational costs and long times-to-result. Development of a low-cost point-of-need assay could be transformative to deficiency analysis in limited-resource settings. The best biomarker of vitamin D status, 25hydroxyvitamin D 3 (25(OH)D 3 ), however, is particularly challenging to measure in such a format due to complexities involved in sample preparation, including the need to separate the marker from its binding protein. Here we present a rapid diagnostic test for the accurate, quantitative assessment of 25(OH)D 3 in finger-stick blood. The assay is accompanied by a smartphone-assisted portable imaging device that can autonomously perform the necessary image processing. To achieve accurate quantification of 25(OH)D 3 , we also demonstrate a novel elution buffer that separates 25(OH)D 3 from its binding protein in situ, eliminating the need for sample preparation. In human trials, the accuracy of our platform is 90.5%.

REGISTRATION OF OVERLAPPING 3D POINT CLO UDS USING EXTRACTED LINE SEGMENTS

Directory of Open Access Journals (Sweden)

Poręba Martyna

2014-12-01

Full Text Available The registration of 3D point clouds collected from different scanner positions is necessary in order to avoid occlusions, ensure a full coverage of areas, and collect useful data for analyzing an d documenting the surrounding environment. This procedure involves three main stages: 1 choosing appropriate features, which can be reliably extracted; 2 matching conjugate primitives; 3 estimating the transformation parameters. Currently, points and spheres are most frequently chosen as the registration features. However, due to limited point cloud resolution, proper identification and precise measurement of a common point within the overlapping laser data is almost impossible. One possible solution to this problem may be a registration process based on the Iterative Closest Point (ICP algorithm or its variation. Alternatively, planar and linear feature - based registration techniques can also be applied. In this paper, we propose the use of line segments obtained from intersecting planes modelled within individual scans. Such primitives can be easily extracted even from low - density point clouds. Working with synthetic data, several existing line - based registration methods are evaluated according to their robustness to noise and the precision of the estimated transformation parameters. For the purpose of quantitative assessment, an accuracy criterion based on a modified Hausdorff distance is defined. Since a n automated matching of segments is a challenging task that influences the correctness of the transformation parameters, a correspondence - finding algorithm is developed. The tests show that our matching algorithm provides a correct pairing with an accuracy of 99 % at least, and about 8% of omitted line pairs.

Higher-order triangular spectral element method with optimized cubature points for seismic wavefield modeling

Energy Technology Data Exchange (ETDEWEB)

Liu, Youshan, E-mail: ysliu@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); Teng, Jiwen, E-mail: jwteng@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); Xu, Tao, E-mail: xutao@mail.iggcas.ac.cn [State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101 (China); Badal, José, E-mail: badal@unizar.es [Physics of the Earth, Sciences B, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain)

2017-05-01

The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant–Friedrichs–Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational

Higher-order triangular spectral element method with optimized cubature points for seismic wavefield modeling

International Nuclear Information System (INIS)

Liu, Youshan; Teng, Jiwen; Xu, Tao; Badal, José

2017-01-01

The mass-lumped method avoids the cost of inverting the mass matrix and simultaneously maintains spatial accuracy by adopting additional interior integration points, known as cubature points. To date, such points are only known analytically in tensor domains, such as quadrilateral or hexahedral elements. Thus, the diagonal-mass-matrix spectral element method (SEM) in non-tensor domains always relies on numerically computed interpolation points or quadrature points. However, only the cubature points for degrees 1 to 6 are known, which is the reason that we have developed a p-norm-based optimization algorithm to obtain higher-order cubature points. In this way, we obtain and tabulate new cubature points with all positive integration weights for degrees 7 to 9. The dispersion analysis illustrates that the dispersion relation determined from the new optimized cubature points is comparable to that of the mass and stiffness matrices obtained by exact integration. Simultaneously, the Lebesgue constant for the new optimized cubature points indicates its surprisingly good interpolation properties. As a result, such points provide both good interpolation properties and integration accuracy. The Courant–Friedrichs–Lewy (CFL) numbers are tabulated for the conventional Fekete-based triangular spectral element (TSEM), the TSEM with exact integration, and the optimized cubature-based TSEM (OTSEM). A complementary study demonstrates the spectral convergence of the OTSEM. A numerical example conducted on a half-space model demonstrates that the OTSEM improves the accuracy by approximately one order of magnitude compared to the conventional Fekete-based TSEM. In particular, the accuracy of the 7th-order OTSEM is even higher than that of the 14th-order Fekete-based TSEM. Furthermore, the OTSEM produces a result that can compete in accuracy with the quadrilateral SEM (QSEM). The high accuracy of the OTSEM is also tested with a non-flat topography model. In terms of computational

Influence of mammographic density on the diagnostic accuracy of tumor size assessment and association with breast cancer tumor characteristics

International Nuclear Information System (INIS)

Fasching, Peter A.; Heusinger, Katharina; Loehberg, Christian R.; Wenkel, Evelyn; Lux, Michael P.; Schrauder, Michael; Koscheck, Thomas; Bautz, Werner; Schulz-Wendtland, Ruediger; Beckmann, Matthias W.; Bani, Mayada R.

2006-01-01

Purpose: The accuracy of breast cancer staging involves the estimation of the tumor size for the initial decision-making in the treatment. We investigated the accuracy of tumor size estimation and the association between tumor characteristics and breast density (BD). Materials and methods: A total of 434 women with a primary diagnosis of breast cancer were included in this prospective study at a specialist breast unit. Estimated tumor characteristics included tumor size, nodal status, estrogen/progesterone receptor status, Ki-67, HER2/neu, vascular invasion. Radiomorphological data included tumor size as assessed by mammography, breast ultrasonography, and clinical examination, and American College of Radiology (ACR) categories for BD. Results: BD did not have a significant impact on the assessment of tumor size using breast ultrasound (deviation from ACR categories 1-4: 0.55-0.68 cm; P = 0.331). The deviation in mammography was significantly different dependent on BD (0.42-0.9 cm; P 2 cm). Conclusion: Breast ultrasonography is more accurate than mammography for assessing tumor size in breasts with a higher BD. The difference in tumor size assessment needs to be taken into consideration in the design of clinical trials and treatment decisions

Accuracy assessment of seven global land cover datasets over China

Science.gov (United States)

Yang, Yongke; Xiao, Pengfeng; Feng, Xuezhi; Li, Haixing

2017-03-01

Land cover (LC) is the vital foundation to Earth science. Up to now, several global LC datasets have arisen with efforts of many scientific communities. To provide guidelines for data usage over China, nine LC maps from seven global LC datasets (IGBP DISCover, UMD, GLC, MCD12Q1, GLCNMO, CCI-LC, and GlobeLand30) were evaluated in this study. First, we compared their similarities and discrepancies in both area and spatial patterns, and analysed their inherent relations to data sources and classification schemes and methods. Next, five sets of validation sample units (VSUs) were collected to calculate their accuracy quantitatively. Further, we built a spatial analysis model and depicted their spatial variation in accuracy based on the five sets of VSUs. The results show that, there are evident discrepancies among these LC maps in both area and spatial patterns. For LC maps produced by different institutes, GLC 2000 and CCI-LC 2000 have the highest overall spatial agreement (53.8%). For LC maps produced by same institutes, overall spatial agreement of CCI-LC 2000 and 2010, and MCD12Q1 2001 and 2010 reach up to 99.8% and 73.2%, respectively; while more efforts are still needed if we hope to use these LC maps as time series data for model inputting, since both CCI-LC and MCD12Q1 fail to represent the rapid changing trend of several key LC classes in the early 21st century, in particular urban and built-up, snow and ice, water bodies, and permanent wetlands. With the highest spatial resolution, the overall accuracy of GlobeLand30 2010 is 82.39%. For the other six LC datasets with coarse resolution, CCI-LC 2010/2000 has the highest overall accuracy, and following are MCD12Q1 2010/2001, GLC 2000, GLCNMO 2008, IGBP DISCover, and UMD in turn. Beside that all maps exhibit high accuracy in homogeneous regions; local accuracies in other regions are quite different, particularly in Farming-Pastoral Zone of North China, mountains in Northeast China, and Southeast Hills. Special

Accuracy and Utility of Deformable Image Registration in 68Ga 4D PET/CT Assessment of Pulmonary Perfusion Changes During and After Lung Radiation Therapy

International Nuclear Information System (INIS)

Hardcastle, Nicholas; Hofman, Michael S.; Hicks, Rodney J.; Callahan, Jason; Kron, Tomas; MacManus, Michael P.; Ball, David L.; Jackson, Price; Siva, Shankar

2015-01-01

Purpose: Measuring changes in lung perfusion resulting from radiation therapy dose requires registration of the functional imaging to the radiation therapy treatment planning scan. This study investigates registration accuracy and utility for positron emission tomography (PET)/computed tomography (CT) perfusion imaging in radiation therapy for non–small cell lung cancer. Methods: 68 Ga 4-dimensional PET/CT ventilation-perfusion imaging was performed before, during, and after radiation therapy for 5 patients. Rigid registration and deformable image registration (DIR) using B-splines and Demons algorithms was performed with the CT data to obtain a deformation map between the functional images and planning CT. Contour propagation accuracy and correspondence of anatomic features were used to assess registration accuracy. Wilcoxon signed-rank test was used to determine statistical significance. Changes in lung perfusion resulting from radiation therapy dose were calculated for each registration method for each patient and averaged over all patients. Results: With B-splines/Demons DIR, median distance to agreement between lung contours reduced modestly by 0.9/1.1 mm, 1.3/1.6 mm, and 1.3/1.6 mm for pretreatment, midtreatment, and posttreatment (P<.01 for all), and median Dice score between lung contours improved by 0.04/0.04, 0.05/0.05, and 0.05/0.05 for pretreatment, midtreatment, and posttreatment (P<.001 for all). Distance between anatomic features reduced with DIR by median 2.5 mm and 2.8 for pretreatment and midtreatment time points, respectively (P=.001) and 1.4 mm for posttreatment (P>.2). Poorer posttreatment results were likely caused by posttreatment pneumonitis and tumor regression. Up to 80% standardized uptake value loss in perfusion scans was observed. There was limited change in the loss in lung perfusion between registration methods; however, Demons resulted in larger interpatient variation compared with rigid and B-splines registration. Conclusions

An assessment of the accuracy of contrast enema for the diagnosis ...

African Journals Online (AJOL)

Diagnostic accuracy levels were calculated by comparing radiological results with histology results, which is the gold standard. Results: Diagnostic accuracy of contrast enema was 78%, sensitivity was 94.4% and the negative predictive value was 95.7%. Specificity (68.8%) and positive predictive values (63%) were ...

Accuracy of treatment planning based on stereolithography in computer assisted surgery

International Nuclear Information System (INIS)

Schicho, Kurt; Figl, Michael; Seemann, Rudolf; Ewers, Rolf; Lambrecht, J. Thomas; Wagner, Arne; Watzinger, Franz; Baumann, Arnulf; Kainberger, Franz; Fruehwald, Julia; Klug, Clemens

2006-01-01

Three-dimensional stereolithographic models (SL models), made of solid acrylic resin derived from computed-tomography (CT) data, are an established tool for preoperative treatment planning in numerous fields of medicine. An innovative approach, combining stereolithography with computer-assisted point-to-point navigation, can support the precise surgical realization of a plan that has been defined on an SL model preoperatively. The essential prerequisites for the application of such an approach are: (1) The accuracy of the SL models (including accuracy of the CT scan and correspondence of the model with the patient's anatomy) and (2) the registration method used for the transfer of the plan from the SL model to the patient (i.e., whether the applied registration markers can be added to the SL model corresponding to the markers at the patient with an accuracy that keeps the ''cumulative error'' at the end of the chain of errors, in the order of the accuracy of contemporary navigation systems). In this study, we focus on these two topics: By applying image-matching techniques, we fuse the original CT data of the patient with the corresponding CT data of the scanned SL model, and measure the deviations of defined parameter (e.g., distances between anatomical points). To evaluate the registration method used for the planning transfer, we apply a point-merge algorithm, using four marker points that should be located at exactly corresponding positions at the patient and at connective bars that are added to the surface of the SL model. Again, deviations at defined anatomical structures are measured and analyzed statistically. Our results prove sufficient correspondence of the two data sets and accuracy of the registration method for routine clinical application. The evaluation of the SL model accuracy revealed an arithmetic mean of the relative deviations from 0.8% to 5.4%, with an overall mean deviation of 2.2%. Mean deviations of the investigated anatomical structures

PLÉIADES PROJECT: ASSESSMENT OF GEOREFERENCING ACCURACY, IMAGE QUALITY, PANSHARPENING PERFORMENCE AND DSM/DTM QUALITY

Directory of Open Access Journals (Sweden)

H. Topan

2016-06-01

Full Text Available Pléiades 1A and 1B are twin optical satellites of Optical and Radar Federated Earth Observation (ORFEO program jointly running by France and Italy. They are the first satellites of Europe with sub-meter resolution. Airbus DS (formerly Astrium Geo runs a MyGIC (formerly Pléiades Users Group program to validate Pléiades images worldwide for various application purposes. The authors conduct three projects, one is within this program, the second is supported by BEU Scientific Research Project Program, and the third is supported by TÜBİTAK. Assessment of georeferencing accuracy, image quality, pansharpening performance and Digital Surface Model/Digital Terrain Model (DSM/DTM quality subjects are investigated in these projects. For these purposes, triplet panchromatic (50 cm Ground Sampling Distance (GSD and VNIR (2 m GSD Pléiades 1A images were investigated over Zonguldak test site (Turkey which is urbanised, mountainous and covered by dense forest. The georeferencing accuracy was estimated with a standard deviation in X and Y (SX, SY in the range of 0.45m by bias corrected Rational Polynomial Coefficient (RPC orientation, using ~170 Ground Control Points (GCPs. 3D standard deviation of ±0.44m in X, ±0.51m in Y, and ±1.82m in Z directions have been reached in spite of the very narrow angle of convergence by bias corrected RPC orientation. The image quality was also investigated with respect to effective resolution, Signal to Noise Ratio (SNR and blur coefficient. The effective resolution was estimated with factor slightly below 1.0, meaning that the image quality corresponds to the nominal resolution of 50cm. The blur coefficients were achieved between 0.39-0.46 for triplet panchromatic images, indicating a satisfying image quality. SNR is in the range of other comparable space borne images which may be caused by de-noising of Pléiades images. The pansharpened images were generated by various methods, and are validated by most common

The accuracy assessment of PPS in fixed beam proton therapy: isocentric rotation movement

International Nuclear Information System (INIS)

Li Xinping; Zeng Xianwen; Xu Wenling; Li Jiamin; Lv Mingming

2005-01-01

Objective: To assess the accuracy of isocentric rotation movement of Patient Positioning System (PPS) in fixed beam proton therapy. Methods: A 2 mm-diameter radioopaque sphere was positioned above the couch and was aligned to room iso-center (ISO). 11 PPS angles were selected to make isocentric rotation test respectively. The displacement of the sphere to ISO were measured and calculated by Digital Image Positioning System (DIPS) respectively when PPS reached each designed position. Totally four group measurements were repeated at different time. all data were collected and statistical analysis were performed. Results: The maximum shifts are (0.29 ± 0.05) mm, (0.21 ± 0.04) mm and (-0.21 ± 0.04) mm on X, Y, Z axes at - 110 degree PPS position, the absolute displacement of the sphere to ISO is (0.41 ± 0.07) mm(1SD). The minimum shifts are (-0.03 ± 0.05) mm, (0.05 ± 0.05) mm and (0.00 ± 0.00) mm on three principle axes at 30 degree PPS position, the absolute displacement of the sphere to ISO is (0.05 ± 0.06) mm. Conclusion: The isocentric rotation movement is the linchpin to realize multi-angle isocentric irradiation in fixed beamproton therapy. It is a complicated combined movement including PPS rotation and PPS translations. Since the high demand in the of precision of patient positioning, the accuracy of this combined movement played important role in proton therapy. In our tests, all shifts are less than 0.5 mm, can reach the requirement of positioning accuracy in proton therapy. (authors)

Three-dimensional repositioning accuracy of semiadjustable articulator cast mounting systems.

Science.gov (United States)

Tan, Ming Yi; Ung, Justina Youlin; Low, Ada Hui Yin; Tan, En En; Tan, Keson Beng Choon

2014-10-01

In spite of its importance in prosthesis precision and quality, the 3-dimensional repositioning accuracy of cast mounting systems has not been reported in detail. The purpose of this study was to quantify the 3-dimensional repositioning accuracy of 6 selected cast mounting systems. Five magnetic mounting systems were compared with a conventional screw-on system. Six systems on 3 semiadjustable articulators were evaluated: Denar Mark II with conventional screw-on mounting plates (DENSCR) and magnetic mounting system with converter plates (DENCON); Denar Mark 330 with in-built magnetic mounting system (DENMAG) and disposable mounting plates; and Artex CP with blue (ARTBLU), white (ARTWHI), and black (ARTBLA) magnetic mounting plates. Test casts with 3 high-precision ceramic ball bearings at the mandibular central incisor (Point I) and the right and left second molar (Point R; Point L) positions were mounted on 5 mounting plates (n=5) for all 6 systems. Each cast was repositioned 10 times by 4 operators in random order. Nine linear (Ix, Iy, Iz; Rx, Ry, Rz; Lx, Ly, Lz) and 3 angular (anteroposterior, mediolateral, twisting) displacements were measured with a coordinate measuring machine. The mean standard deviations of the linear and angular displacements defined repositioning accuracy. Anteroposterior linear repositioning accuracy ranged from 23.8 ±3.7 μm (DENCON) to 4.9 ±3.2 μm (DENSCR). Mediolateral linear repositioning accuracy ranged from 46.0 ±8.0 μm (DENCON) to 3.7 ±1.5 μm (ARTBLU), and vertical linear repositioning accuracy ranged from 7.2 ±9.6 μm (DENMAG) to 1.5 ±0.9 μm (ARTBLU). Anteroposterior angular repositioning accuracy ranged from 0.0084 ±0.0080 degrees (DENCON) to 0.0020 ±0.0006 degrees (ARTBLU), and mediolateral angular repositioning accuracy ranged from 0.0120 ±0.0111 degrees (ARTWHI) to 0.0027 ±0.0008 degrees (ARTBLU). Twisting angular repositioning accuracy ranged from 0.0419 ±0.0176 degrees (DENCON) to 0.0042 ±0.0038 degrees

High diagnostic yield and accuracy of history, physical examination, and ECG in patients with transient loss of consciousness in FAST: The fainting assessment study

NARCIS (Netherlands)

van Dijk, Nynke; Boer, Kimberly R.; Colman, Nancy; Bakker, Annemieke; Stam, Jan; van Grieken, Johannes J. M.; Wilde, Arthur A. M.; Linzer, Mark; Reitsma, Johannes B.; Wieling, Wouter

2008-01-01

Yield and Accuracy of Diagnosing TLOC. Background: Transient loss of consciousness (TLOC) is a common clinical problem. Objective: The aim of this study was to assess the yield and accuracy of the initial evaluation, consisting of standardized history, physical examination, and ECG performed by

Comparison of vascular width and accuracy of subjective assessment of pulmonary flow X-ray films of children with left-right shunt

International Nuclear Information System (INIS)

Hegenbarth, R.; Toeroek, M.; Hannover Medizinische Hochschule

1985-01-01

The authors established a comparative relationship between accuracy of measurement of pulmonary flow and extent of vascular widening in 72 children with Left-Right shunt vitiae; this accuracy of pulmonary flow measurement had been subjectively estimated by 4 investigators without knowing the diagnosis and in comparison to the haemodynamic values (percentage of correct findings). The following procedure was adopted: In a control group of 143 healthy children, we first determined the vascular diameter of the right descending pulmonary artery, of the right upper lobal vein, and of the peripheral vessels in the upper and lower pulmonary fields, at an accurately defined distance from the point of the hilus, and compared with the vascular diameters of the children with left-right shunt, employing the method of discrimination analysis. Comparison of the judgement by the 4 investigators with the degree of increase of the vascular diameters showed an accuracy of 65-100% if the right descending pulmonary artery became wider by 2.6 mm, and an accuracy of 79-95% if the mean vascular width in the right upper field increased by 0.7 mm. The accuracy was 83-94% if the mean vascular width in the right lower field increased by 0.6 mm. Statistical studies also showed that the judgement of the 4 investigators was influenced by different vessels. (orig.) [de

Minimally invasive registration for computer-assisted orthopedic surgery: combining tracked ultrasound and bone surface points via the P-IMLOP algorithm.

Science.gov (United States)

Billings, Seth; Kang, Hyun Jae; Cheng, Alexis; Boctor, Emad; Kazanzides, Peter; Taylor, Russell

2015-06-01

We present a registration method for computer-assisted total hip replacement (THR) surgery, which we demonstrate to improve the state of the art by both reducing the invasiveness of current methods and increasing registration accuracy. A critical element of computer-guided procedures is the determination of the spatial correspondence between the patient and a computational model of patient anatomy. The current method for establishing this correspondence in robot-assisted THR is to register points intraoperatively sampled by a tracked pointer from the exposed proximal femur and, via auxiliary incisions, from the distal femur. In this paper, we demonstrate a noninvasive technique for sampling points on the distal femur using tracked B-mode ultrasound imaging and present a new algorithm for registering these data called Projected Iterative Most-Likely Oriented Point (P-IMLOP). Points and normal orientations of the distal bone surface are segmented from ultrasound images and registered to the patient model along with points sampled from the exposed proximal femur via a tracked pointer. The proposed approach is evaluated using a bone- and tissue-mimicking leg phantom constructed to enable accurate assessment of experimental registration accuracy with respect to a CT-image-based model of the phantom. These experiments demonstrate that localization of the femur shaft is greatly improved by tracked ultrasound. The experiments further demonstrate that, for ultrasound-based data, the P-IMLOP algorithm significantly improves registration accuracy compared to the standard ICP algorithm. Registration via tracked ultrasound and the P-IMLOP algorithm has high potential to reduce the invasiveness and improve the registration accuracy of computer-assisted orthopedic procedures.

Calorimetry end-point predictions

International Nuclear Information System (INIS)

Fox, M.A.

1981-01-01

This paper describes a portion of the work presently in progress at Rocky Flats in the field of calorimetry. In particular, calorimetry end-point predictions are outlined. The problems associated with end-point predictions and the progress made in overcoming these obstacles are discussed. The two major problems, noise and an accurate description of the heat function, are dealt with to obtain the most accurate results. Data are taken from an actual calorimeter and are processed by means of three different noise reduction techniques. The processed data are then utilized by one to four algorithms, depending on the accuracy desired to determined the end-point

Accuracy assessment of cadastral maps using high resolution aerial photos

Directory of Open Access Journals (Sweden)

Alwan Imzahim

2018-01-01

Full Text Available A cadastral map is a map that shows the boundaries and ownership of land parcels. Some cadastral maps show additional details, such as survey district names, unique identifying numbers for parcels, certificate of title numbers, positions of existing structures, section or lot numbers and their respective areas, adjoining and adjacent street names, selected boundary dimensions and references to prior maps. In Iraq / Baghdad Governorate, the main problem is that the cadastral maps are georeferenced to a local geodetic datum known as Clark 1880 while the widely used reference system for navigation purpose (GPS and GNSS and uses Word Geodetic System 1984 (WGS84 as a base reference datum. The objective of this paper is to produce a cadastral map with scale 1:500 (metric scale by using aerial photographs 2009 with high ground spatial resolution 10 cm reference WGS84 system. The accuracy assessment for the cadastral maps updating approach to urban large scale cadastral maps (1:500-1:1000 was ± 0.115 meters; which complies with the American Social for Photogrammetry and Remote Sensing Standards (ASPRS.

An assessment of the melting, boiling, and critical point data of the alkali metals

International Nuclear Information System (INIS)

Ohse, R.W.; Babelot, J.F.; Magill, J.

1985-01-01

The measured melting, boiling and critical point data of the alkali metals are reviewed. Emphasis has been given to the assessment of the critical point data. The main experimental techniques for measurements in the critical region are described. The selected data are given. Best estimates of the critical constants of lithium are given. (author)

Assessment of Thailand indoor set-point impact on energy consumption and environment

International Nuclear Information System (INIS)

Yamtraipat, N.; Khedari, J.; Hirunlabh, J.; Kunchornrat, J.

2006-01-01

The paper presents an investigation of indoor set-point standard of air-conditioned spaces as a tool to control electrical energy consumption of air-conditioners in Thailand office buildings and to reduce air pollutants. One hundred and forty-seven air-conditioned rooms in 13 buildings nationwide were used as models to analyze the electricity consumption of air-conditioning systems according to their set indoor temperatures, which were below the standard set-point and were accounted into a large scale. Then, the electrical energy and environmental saving potentials in the country were assessed by the assumption that adaptation of indoor set-point temperature is increased up to the standard set-point of 26 o C. It was concluded that the impacts of indoor set-point of air-conditioned rooms, set at 26 o C, on energy saving and on environment are as follows: The overall electricity consumption saving would be 804.60 GWh/year, which would reduce the corresponding GHGs emissions (mainly CO 2 ) from power plant by 579.31x10 3 tons/year

Accuracy of the photogrametric measuring system for large size elements

Directory of Open Access Journals (Sweden)

M. Grzelka

2011-04-01

Full Text Available The aim of this paper is to present methods of estimating and guidelines for verifying the accuracy of optical photogrammetric measuringsystems, using for measurement of large size elements. Measuring systems applied to measure workpieces of a large size which oftenreach more than 10000mm require use of appropriate standards. Those standards provided by the manufacturer of photogrammetricsystems are certified and are inspected annually. To make sure that these systems work properly there was developed a special standardVDI / VDE 2634, "Optical 3D measuring systems. Imaging systems with point - by - point probing. " According to recommendationsdescribed in this standard research on accuracy of photogrametric measuring system was conducted using K class gauge blocks dedicatedto calibrate and test accuracy of classic CMMs. The paper presents results of research of estimation the actual error of indication for sizemeasurement MPEE for photogrammetric coordinate measuring system TRITOP.

COMPREHENSIVE COMPARISON OF TWO IMAGE-BASED POINT CLOUDS FROM AERIAL PHOTOS WITH AIRBORNE LIDAR FOR LARGE-SCALE MAPPING

Directory of Open Access Journals (Sweden)

E. Widyaningrum

2017-09-01

Full Text Available The integration of computer vision and photogrammetry to generate three-dimensional (3D information from images has contributed to a wider use of point clouds, for mapping purposes. Large-scale topographic map production requires 3D data with high precision and accuracy to represent the real conditions of the earth surface. Apart from LiDAR point clouds, the image-based matching is also believed to have the ability to generate reliable and detailed point clouds from multiple-view images. In order to examine and analyze possible fusion of LiDAR and image-based matching for large-scale detailed mapping purposes, point clouds are generated by Semi Global Matching (SGM and by Structure from Motion (SfM. In order to conduct comprehensive and fair comparison, this study uses aerial photos and LiDAR data that were acquired at the same time. Qualitative and quantitative assessments have been applied to evaluate LiDAR and image-matching point clouds data in terms of visualization, geometric accuracy, and classification result. The comparison results conclude that LiDAR is the best data for large-scale mapping.

Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

Directory of Open Access Journals (Sweden)

Liang Wang

2018-02-01

Full Text Available Precise Point Positioning (PPP is a popular technology for precise applications based on the Global Navigation Satellite System (GNSS. Multi-GNSS combined PPP has become a hot topic in recent years with the development of multiple GNSSs. Meanwhile, with the operation of the real-time service (RTS of the International GNSS Service (IGS agency that provides satellite orbit and clock corrections to broadcast ephemeris, it is possible to obtain the real-time precise products of satellite orbits and clocks and to conduct real-time PPP. In this contribution, the real-time multi-GNSS orbit and clock corrections of the CLK93 product are applied for real-time multi-GNSS PPP processing, and its orbit and clock qualities are investigated, first with a seven-day experiment by comparing them with the final multi-GNSS precise product ‘GBM’ from GFZ. Then, an experiment involving real-time PPP processing for three stations in the Multi-GNSS Experiment (MGEX network with a testing period of two weeks is conducted in order to evaluate the convergence performance of real-time PPP in a simulated kinematic mode. The experimental result shows that real-time PPP can achieve a convergence performance of less than 15 min for an accuracy level of 20 cm. Finally, the real-time data streams from 12 globally distributed IGS/MGEX stations for one month are used to assess and validate the positioning accuracy of real-time multi-GNSS PPP. The results show that the simulated kinematic positioning accuracy achieved by real-time PPP on different stations is about 3.0 to 4.0 cm for the horizontal direction and 5.0 to 7.0 cm for the three-dimensional (3D direction.

Determination of fuel irradiation parameters. Required accuracies and available methods

International Nuclear Information System (INIS)

Mas, P.

1977-01-01

This paper reports on the present point of some main methods to determine the nuclear parameters of fuel irradiation in testing reactors (nuclear power, burn up, ...) The different methods (theoretical or experimental) are reviewed: neutron measurements and calculations, gamma scanning, heat balance, ... . The required accuracies are reviewed: they are of 3-5 % on flux, fluences, nuclear power, burn-up, conversion factor. These required accuracies are compared with the real accuracies available which are the present time of order of 5-20 % on these parameters

Sensitivity, uncertainty assessment, and target accuracies related to radiotoxicity evaluation

International Nuclear Information System (INIS)

Palmiotti, G.; Salvatores, M.; Hill, R.N.

1994-01-01

Time-dependent sensitivity techniques, which have been used in the past for standard reactor applications, are adapted to calculate the impact of data uncertainties and to estimate target data accuracies in radiotoxicity evaluations. The methodology is applied to different strategies of radioactive waste management connected with the European Fast Reactor and the Integral Fast Reactor fuel cycles. Results are provided in terms of sensitivity coefficients of basic data (cross sections and decay constants), uncertainties of global radiotoxicity at different times of storing after discharge, and target data accuracies needed to satisfy maximum uncertainty limits

Accuracy of image guidance using free-breathing cone-beam computed tomography for stereotactic lung radiotherapy.

Science.gov (United States)

Kamomae, Takeshi; Monzen, Hajime; Nakayama, Shinichi; Mizote, Rika; Oonishi, Yuuichi; Kaneshige, Soichiro; Sakamoto, Takashi

2015-01-01

Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.

Accuracy assessment of high-rate GPS measurements for seismology

Science.gov (United States)

Elosegui, P.; Davis, J. L.; Ekström, G.

2007-12-01

Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

Use of point-of-sale data to assess food and nutrient quality in remote stores.

Science.gov (United States)

Brimblecombe, Julie; Liddle, Robyn; O'Dea, Kerin

2013-07-01

To examine the feasibility of using point-of-sale data to assess dietary quality of food sales in remote stores. A multi-site cross-sectional assessment of food and nutrient composition of food sales. Point-of-sale data were linked to Australian Food and Nutrient Data and compared across study sites and with nutrient requirements. Remote Aboriginal Australia. Six stores. Point-of-sale data were readily available and provided a low-cost, efficient and objective assessment of food and nutrient sales. Similar patterns in macronutrient distribution, food expenditure and key food sources of nutrients were observed across stores. In all stores, beverages, cereal and cereal products, and meat and meat products comprised approximately half of food sales (range 49–57 %). Fruit and vegetable sales comprised 10.4 (SD 1.9) % on average. Carbohydrate contributed 54.4 (SD 3.0) % to energy; protein 13.5 (SD 1.1) %; total sugars 28.9 (SD 4.3) %; and the contribution of total saturated fat to energy ranged from 11.0 to 14.4% across stores. Mg, Ca, K and fibre were limiting nutrients, and Na was four to five times higher than the midpoint of the average intake range. Relatively few foods were major sources of nutrients. Point-of-sale data enabled an assessment of dietary quality within stores and across stores with no burden on communities and at no cost, other than time required for analysis and reporting. Similar food spending patterns and nutrient profiles were observed across the six stores. This suggests potential in using point-of-sale data to monitor and evaluate dietary quality in remote Australian communities.

Accuracy and Utility of Deformable Image Registration in {sup 68}Ga 4D PET/CT Assessment of Pulmonary Perfusion Changes During and After Lung Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Hardcastle, Nicholas, E-mail: nick.hardcastle@gmail.com [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Centre for Medical Radiation Physics, University of Wollongong, Wollongong (Australia); Hofman, Michael S. [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Hicks, Rodney J. [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Department of Medicine, University of Melbourne, Melbourne (Australia); Callahan, Jason [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Kron, Tomas [Department of Medical Imaging and Radiation Sciences, Monash University, Clayton (Australia); The Sir Peter MacCallum Department of Oncology, Melbourne University, Victoria (Australia); MacManus, Michael P.; Ball, David L. [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia); The Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne (Australia); Jackson, Price [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Siva, Shankar [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia)

2015-09-01

Purpose: Measuring changes in lung perfusion resulting from radiation therapy dose requires registration of the functional imaging to the radiation therapy treatment planning scan. This study investigates registration accuracy and utility for positron emission tomography (PET)/computed tomography (CT) perfusion imaging in radiation therapy for non–small cell lung cancer. Methods: {sup 68}Ga 4-dimensional PET/CT ventilation-perfusion imaging was performed before, during, and after radiation therapy for 5 patients. Rigid registration and deformable image registration (DIR) using B-splines and Demons algorithms was performed with the CT data to obtain a deformation map between the functional images and planning CT. Contour propagation accuracy and correspondence of anatomic features were used to assess registration accuracy. Wilcoxon signed-rank test was used to determine statistical significance. Changes in lung perfusion resulting from radiation therapy dose were calculated for each registration method for each patient and averaged over all patients. Results: With B-splines/Demons DIR, median distance to agreement between lung contours reduced modestly by 0.9/1.1 mm, 1.3/1.6 mm, and 1.3/1.6 mm for pretreatment, midtreatment, and posttreatment (P<.01 for all), and median Dice score between lung contours improved by 0.04/0.04, 0.05/0.05, and 0.05/0.05 for pretreatment, midtreatment, and posttreatment (P<.001 for all). Distance between anatomic features reduced with DIR by median 2.5 mm and 2.8 for pretreatment and midtreatment time points, respectively (P=.001) and 1.4 mm for posttreatment (P>.2). Poorer posttreatment results were likely caused by posttreatment pneumonitis and tumor regression. Up to 80% standardized uptake value loss in perfusion scans was observed. There was limited change in the loss in lung perfusion between registration methods; however, Demons resulted in larger interpatient variation compared with rigid and B-splines registration

Gran method for end point anticipation in monosegmented flow titration

Directory of Open Access Journals (Sweden)

Aquino Emerson V

2004-01-01

Full Text Available An automatic potentiometric monosegmented flow titration procedure based on Gran linearisation approach has been developed. The controlling program can estimate the end point of the titration after the addition of three or four aliquots of titrant. Alternatively, the end point can be determined by the second derivative procedure. In this case, additional volumes of titrant are added until the vicinity of the end point and three points before and after the stoichiometric point are used for end point calculation. The performance of the system was assessed by the determination of chloride in isotonic beverages and parenteral solutions. The system employs a tubular Ag2S/AgCl indicator electrode. A typical titration, performed according to the IUPAC definition, requires only 60 mL of sample and about the same volume of titrant (AgNO3 solution. A complete titration can be carried out in 1 - 5 min. The accuracy and precision (relative standard deviation of ten replicates are 2% and 1% for the Gran and 1% and 0.5% for the Gran/derivative end point determination procedures, respectively. The proposed system reduces the time to perform a titration, ensuring low sample and reagent consumption, and full automatic sampling and titrant addition in a calibration-free titration protocol.

Accuracy in the legal age estimation according to the third molars mineralization among Mexicans and Columbians.

Science.gov (United States)

Costa, José; Montero, Javier; Serrano, Sarai; Albaladejo, Alberto; López-Valverde, Antonio; Bica, Isabel

2014-11-01

This study aims to assess the accuracy of age estimation according to two cut-off points of Demirjian's developmental stages (G and H) in the wisdom teeth, using panoramic radiographs from Colombian and Mexican teenagers. The degree of maturation of the third molars was classified according to Demirjian in 8 stages (from A to H) by a blinded trained assessor. The sensitivity, specificity and efficacy of two cut-off points (G and H) were calculated for both samples. The orthopantomographies of 316 subjects, 171 Colombians (54.1%) and 145 Mexicans (45.9%), were analyzed. The stage H was found to be the best threshold for detecting juveniles (because the high specificity) in all the third molars assessed. The specificity was higher for lower third molars than for upper third molars, but no asymmetrical discrepancy was noted. The stage H is the best cut-off point for detecting the adulthood when a high-specificity test is required. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Parameter Deduction and Accuracy Analysis of Track Beam Curves in Straddle-type Monorail Systems

Directory of Open Access Journals (Sweden)

Xiaobo Zhao

2015-12-01

Full Text Available The accuracy of the bottom curve of a PC track beam is strongly related to the production quality of the entire beam. Many factors may affect the parameters of the bottom curve, such as the superelevation of the curve and the deformation of a PC track beam. At present, no effective method has been developed to determine the bottom curve of a PC track beam; therefore, a new technique is presented in this paper to deduce the parameters of such a curve and to control the accuracy of the computation results. First, the domain of the bottom curve of a PC track beam is assumed to be a spindle plane. Then, the corresponding supposed top curve domain is determined based on a geometrical relationship that is the opposite of that identified by the conventional method. Second, several optimal points are selected from the supposed top curve domain according to the dichotomy algorithm; the supposed top curve is thus generated by connecting these points. Finally, one rigorous criterion is established in the fractal dimension to assess the accuracy of the assumed top curve deduced in the previous step. If this supposed curve coincides completely with the known top curve, then the assumed bottom curve corresponding to the assumed top curve is considered to be the real bottom curve. This technique of determining the bottom curve of a PC track beam is thus proven to be efficient and accurate.

La Parguera Accuracy Assessment Point Data for Benthic Habitats of Puerto Rico and the U.S. Virgin Islands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This project is a cooperative effort among the National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Monitoring and Assessment; the...

Accuracy of densitometric vertebral fracture assessment when performed by DXA technicians-a cross-sectional, multiobserver study

DEFF Research Database (Denmark)

Rud, B; Vestergaard, A; Hyldstrup, L

2016-01-01

Six dual-energy X-ray absorptiometry (DXA) technicians reviewed lateral images of the spine for deformed vertebrae. The images were acquired with a DXA scanner in 235 patients referred for osteoporosis assessment. The outcome was compared to findings on spinal radiographs assessed by two radiolog......Six dual-energy X-ray absorptiometry (DXA) technicians reviewed lateral images of the spine for deformed vertebrae. The images were acquired with a DXA scanner in 235 patients referred for osteoporosis assessment. The outcome was compared to findings on spinal radiographs assessed by two...... radiologists. Three DXA technicians performed acceptable or better in identifying patients with fractured vertebrae. INTRODUCTION: This is the first study to evaluate the accuracy of vertebral fracture assessment (VFA) when used by DXA technicians as a triage test to select patients with deformed vertebrae...... for spinal radiographs. METHODS: Lateral single-energy scans and radiographs of the thoracolumbar spine (T4-L4) were acquired in 235 patients aged 65 years or more referred for osteoporosis assessment. Six DXA technicians evaluated lateral scans using dedicated software. The DXA technicians were trained...

Assessing the accuracy of weather radar to track intense rain cells in the Greater Lyon area, France

Science.gov (United States)

Renard, Florent; Chapon, Pierre-Marie; Comby, Jacques

2012-01-01

The Greater Lyon is a dense area located in the Rhône Valley in the south east of France. The conurbation counts 1.3 million inhabitants and the rainfall hazard is a great concern. However, until now, studies on rainfall over the Greater Lyon have only been based on the network of rain gauges, despite the presence of a C-band radar located in the close vicinity. Consequently, the first aim of this study was to investigate the hydrological quality of this radar. This assessment, based on comparison of radar estimations and rain-gauges values concludes that the radar data has overall a good quality since 2006. Given this good accuracy, this study made a next step and investigated the characteristics of intense rain cells that are responsible of the majority of floods in the Greater Lyon area. Improved knowledge on these rainfall cells is important to anticipate dangerous events and to improve the monitoring of the sewage system. This paper discusses the analysis of the ten most intense rainfall events in the 2001-2010 period. Spatial statistics pointed towards straight and linear movements of intense rainfall cells, independently on the ground surface conditions and the topography underneath. The speed of these cells was found nearly constant during a rainfall event, but depend from event to ranges on average from 25 to 66 km/h.

Accuracy assessment of the vegetation continuous field tree cover product using 3954 ground plots in the southwestern USA

Science.gov (United States)

M. A. White; J. D. Shaw; R. D. Ramsey

2005-01-01

An accuracy assessment of the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation continuous field (VCF) tree cover product using two independent ground-based tree cover databases was conducted. Ground data included 1176 Forest Inventory and Analysis (FIA) plots for Arizona and 2778 Southwest Regional GAP (SWReGAP) plots for Utah and western Colorado....

Accuracy of 11-year-olds selfreported school lunch consumption

DEFF Research Database (Denmark)

Lyng, Nina

accuracy differ by the lunch format consumed (Paper III) Material and methods The study was conducted as a cross-sectional dietary reporting study. The population consisted of 11-year-old children from three public schools in Copenhagen. The study was conducted on two consecutive days and assessed...... in general. Objectives The aim of the present thesis was to assess food level reporting accuracy in Danish 11-year-old children’s self-reported school lunch consumption, and the aim was operationalized in following objectives. 1- To identify food items clustering by lunch format (Preliminary analyses) 2......- To assess reporting accuracy in relation to gender and self-reported methods (Paper I) 3- To address aspects of reporting inaccuracy from intrusions by food group, against different objective measures, and classification of intrusions in stretches and confabulations (Paper II) 4- To assess how reporting...

Hand-eye calibration for rigid laparoscopes using an invariant point.

Science.gov (United States)

Thompson, Stephen; Stoyanov, Danail; Schneider, Crispin; Gurusamy, Kurinchi; Ourselin, Sébastien; Davidson, Brian; Hawkes, David; Clarkson, Matthew J

2016-06-01

Laparoscopic liver resection has significant advantages over open surgery due to less patient trauma and faster recovery times, yet it can be difficult due to the restricted field of view and lack of haptic feedback. Image guidance provides a potential solution but one current challenge is in accurate "hand-eye" calibration, which determines the position and orientation of the laparoscope camera relative to the tracking markers. In this paper, we propose a simple and clinically feasible calibration method based on a single invariant point. The method requires no additional hardware, can be constructed by theatre staff during surgical setup, requires minimal image processing and can be visualised in real time. Real-time visualisation allows the surgical team to assess the calibration accuracy before use in surgery. In addition, in the laboratory, we have developed a laparoscope with an electromagnetic tracking sensor attached to the camera end and an optical tracking marker attached to the distal end. This enables a comparison of tracking performance. We have evaluated our method in the laboratory and compared it to two widely used methods, "Tsai's method" and "direct" calibration. The new method is of comparable accuracy to existing methods, and we show RMS projected error due to calibration of 1.95 mm for optical tracking and 0.85 mm for EM tracking, versus 4.13 and 1.00 mm respectively, using existing methods. The new method has also been shown to be workable under sterile conditions in the operating room. We have proposed a new method of hand-eye calibration, based on a single invariant point. Initial experience has shown that the method provides visual feedback, satisfactory accuracy and can be performed during surgery. We also show that an EM sensor placed near the camera would provide significantly improved image overlay accuracy.

Assessing nonchoosers' eyewitness identification accuracy from photographic showups by using confidence and response times.

Science.gov (United States)

Sauerland, Melanie; Sagana, Anna; Sporer, Siegfried L

2012-10-01

While recent research has shown that the accuracy of positive identification decisions can be assessed via confidence and decision times, gauging lineup rejections has been less successful. The current study focused on 2 different aspects which are inherent in lineup rejections. First, we hypothesized that decision times and confidence ratings should be postdictive of identification rejections if they refer to a single lineup member only. Second, we hypothesized that dividing nonchoosers according to the reasons they provided for their decisions can serve as a useful postdictor for nonchoosers' accuracy. To test these assumptions, we used (1) 1-person lineups (showups) in order to obtain confidence and response time measures referring to a single lineup member, and (2) asked nonchoosers about their reasons for making a rejection. Three hundred and eighty-four participants were asked to identify 2 different persons after watching 1 of 2 stimulus films. The results supported our hypotheses. Nonchoosers' postdecision confidence ratings were well-calibrated. Likewise, we successfully established optimum time and confidence boundaries for nonchoosers. Finally, combinations of postdictors increased the number of accurate classifications compared with individual postdictors. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Reliability and accuracy assessment of radiation therapy oncology group-endorsed guidelines for brachial plexus contouring

Energy Technology Data Exchange (ETDEWEB)

Velde, Joris van de [Ghent University, Department of Anatomy, Ghent (Belgium); Ghent University, Department of Radiotherapy, Ghent (Belgium); Vercauteren, Tom; Gersem, Werner de; Vandecasteele, Katrien; Vuye, Philippe; Vanpachtenbeke, Frank; Neve, Wilfried de [Ghent University, Department of Radiotherapy, Ghent (Belgium); Wouters, Johan; Herde, Katharina d' ; Kerckaert, Ingrid; Hoof, Tom van [Ghent University, Department of Anatomy, Ghent (Belgium)

2014-07-15

The goal of this work was to validate the Radiation Therapy Oncology Group (RTOG)-endorsed guidelines for brachial plexus (BP) contouring by determining the intra- and interobserver agreement. Accuracy of the delineation process was determined using anatomically validated imaging datasets as a gold standard. Five observers delineated the right BP on three cadaver computed tomography (CT) datasets. To assess intraobserver variation, every observer repeated each delineation three times with a time interval of 2 weeks. The BP contours were divided into four regions for detailed analysis. Inter- and intraobserver variation was verified using the Computerized Environment for Radiation Research (CERR) software. Accuracy was measured using anatomically validated fused CT-magnetic resonance imaging (MRI) datasets by measuring the BP inclusion of the delineations. The overall kappa (κ) values were rather low (mean interobserver overall κ: 0.29, mean intraobserver overall κ: 0.45), indicating poor inter- and intraobserver reliability. In general, the κ coefficient decreased gradually from the medial to lateral BP regions. The total agreement volume (TAV) was much smaller than the union volume (UV) for all delineations, resulting in a low Jaccard index (JI; interobserver agreement 0-0.124; intraobserver agreement 0.004-0.636). The overall accuracy was poor, with an average total BP inclusion of 38 %. Inclusions were insufficient for the most lateral regions (region 3: 21.5 %; region 4: 12.6 %). The inter- and intraobserver reliability of the RTOG-endorsed BP contouring guidelines was poor. BP inclusion worsened from the medial to lateral regions. Accuracy assessment of the contours showed an average BP inclusion of 38 %. For the first time, this was assessed using the original anatomically validated BP volume. The RTOG-endorsed BP guidelines have insufficient accuracy and reliability, especially for the lateral head-and-neck regions. (orig.) [German] Ziel der Studie war

Floating-to-Fixed-Point Conversion for Digital Signal Processors

Directory of Open Access Journals (Sweden)

Menard Daniel

2006-01-01

Full Text Available Digital signal processing applications are specified with floating-point data types but they are usually implemented in embedded systems with fixed-point arithmetic to minimise cost and power consumption. Thus, methodologies which establish automatically the fixed-point specification are required to reduce the application time-to-market. In this paper, a new methodology for the floating-to-fixed point conversion is proposed for software implementations. The aim of our approach is to determine the fixed-point specification which minimises the code execution time for a given accuracy constraint. Compared to previous methodologies, our approach takes into account the DSP architecture to optimise the fixed-point formats and the floating-to-fixed-point conversion process is coupled with the code generation process. The fixed-point data types and the position of the scaling operations are optimised to reduce the code execution time. To evaluate the fixed-point computation accuracy, an analytical approach is used to reduce the optimisation time compared to the existing methods based on simulation. The methodology stages are described and several experiment results are presented to underline the efficiency of this approach.

Floating-to-Fixed-Point Conversion for Digital Signal Processors

Science.gov (United States)

Menard, Daniel; Chillet, Daniel; Sentieys, Olivier

2006-12-01

Digital signal processing applications are specified with floating-point data types but they are usually implemented in embedded systems with fixed-point arithmetic to minimise cost and power consumption. Thus, methodologies which establish automatically the fixed-point specification are required to reduce the application time-to-market. In this paper, a new methodology for the floating-to-fixed point conversion is proposed for software implementations. The aim of our approach is to determine the fixed-point specification which minimises the code execution time for a given accuracy constraint. Compared to previous methodologies, our approach takes into account the DSP architecture to optimise the fixed-point formats and the floating-to-fixed-point conversion process is coupled with the code generation process. The fixed-point data types and the position of the scaling operations are optimised to reduce the code execution time. To evaluate the fixed-point computation accuracy, an analytical approach is used to reduce the optimisation time compared to the existing methods based on simulation. The methodology stages are described and several experiment results are presented to underline the efficiency of this approach.

Chilean version of the INECO Frontal Screening (IFS-Ch: Psychometric properties and diagnostic accuracy

Directory of Open Access Journals (Sweden)

Josefina Ihnen

Full Text Available ABSTRACT Objective: This study sought to analyze the psychometric properties and diagnostic accuracy of the Chilean version of the INECO Frontal Screening (IFS-Ch in a sample of dementia patients and control Methods: After adapting the instrument to the Chilean context and obtaining content validity evidence through expert consultation, the IFS-Ch was administered to 31 dementia patients and 30 control subjects together with other executive assessments (Frontal Assessment Battery [FAB], Modified version of the Wisconsin Card Sorting Test [MCST], phonemic verbal fluencies [letters A and P] and semantic verbal fluency [animals] and global cognitive efficiency tests (Mini mental State Examination [MMSE] and Addenbrooke's Cognitive Examination-Revised [ACE-R]. Caregivers of dementia patients and proxies of control subjects were interviewed with instruments measuring dysexecutive symptoms (Dysexecutive Questionnaire [DEX], dementia severity (Clinical Dementia Rating Scale [CDR] and functional status in activities of daily living (Activities of Daily Living Scale [IADL] and Technology-Activities of Daily Living Questionnaire [T-ADLQ]. Convergent and discriminant validity, internal consistency reliability, cut-off points, sensitivity and specificity for the IFS-Ch were estimated. Results: Evidence of content validity was obtained. Evidence of convergent validity was also found showing significant correlations (p<0.05 between the IFS-Ch and the other instruments measuring: executive functions (FAB, r=0.935; categories achieved in the MCST, r=0.791; perseverative errors in the MCST, r= -0.617; animal verbal fluency, r=0.728; A verbal fluency, r=0.681; and P verbal fluency, r=0.783, dysexecutive symptoms in daily living (DEX, r= -0.494, dementia severity (CDR, r= -0.75 and functional status in activities of daily living (T-ADLQ, r= -0.745; IADL, r=0.717. Regarding reliability, a Cronbach's alpha coefficient of 0.905 was obtained. For diagnostic accuracy

Accuracy Assessment for the Three-Dimensional Coordinates by High-Speed Videogrammetric Measurement

Directory of Open Access Journals (Sweden)

Xianglei Liu

2018-01-01

Full Text Available High-speed CMOS camera is a new kind of transducer to make the videogrammetric measurement for monitoring the displacement of high-speed shaking table structure. The purpose of this paper is to validate the three-dimensional coordinate accuracy of the shaking table structure acquired from the presented high-speed videogrammetric measuring system. In the paper, all of the key intermediate links are discussed, including the high-speed CMOS videogrammetric measurement system, the layout of the control network, the elliptical target detection, and the accuracy validation of final 3D spatial results. Through the accuracy analysis, the submillimeter accuracy can be made for the final the three-dimensional spatial coordinates which certify that the proposed high-speed videogrammetric technique is a better alternative technique which can replace the traditional transducer technique for monitoring the dynamic response for the shaking table structure.

A New Blind Pointing Model Improves Large Reflector Antennas Precision Pointing at Ka-Band (32 GHz)

Science.gov (United States)

Rochblatt, David J.

2009-01-01

The National Aeronautics and Space Administration (NASA), Jet Propulsion Laboratory (JPL)-Deep Space Network (DSN) subnet of 34-m Beam Waveguide (BWG) Antennas was recently upgraded with Ka-Band (32-GHz) frequency feeds for space research and communication. For normal telemetry tracking a Ka-Band monopulse system is used, which typically yields 1.6-mdeg mean radial error (MRE) pointing accuracy on the 34-m diameter antennas. However, for the monopulse to be able to acquire and lock, for special radio science applications where monopulse cannot be used, or as a back-up for the monopulse, high-precision open-loop blind pointing is required. This paper describes a new 4th order pointing model and calibration technique, which was developed and applied to the DSN 34-m BWG antennas yielding 1.8 to 3.0-mdeg MRE pointing accuracy and amplitude stability of 0.2 dB, at Ka-Band, and successfully used for the CASSINI spacecraft occultation experiment at Saturn and Titan. In addition, the new 4th order pointing model was used during a telemetry experiment at Ka-Band (32 GHz) utilizing the Mars Reconnaissance Orbiter (MRO) spacecraft while at a distance of 0.225 astronomical units (AU) from Earth and communicating with a DSN 34-m BWG antenna at a record high rate of 6-megabits per second (Mb/s).

Technique for Increasing Accuracy of Positioning System of Machine Tools

Directory of Open Access Journals (Sweden)

Sh. Ji

2014-01-01

Full Text Available The aim of research is to improve the accuracy of positioning and processing system using a technique for optimization of pressure diagrams of guides in machine tools. The machining quality is directly related to its accuracy, which characterizes an impact degree of various errors of machines. The accuracy of the positioning system is one of the most significant machining characteristics, which allow accuracy evaluation of processed parts.The literature describes that the working area of the machine layout is rather informative to characterize the effect of the positioning system on the macro-geometry of the part surfaces to be processed. To enhance the static accuracy of the studied machine, in principle, two groups of measures are possible. One of them points toward a decrease of the cutting force component, which overturns the slider moments. Another group of measures is related to the changing sizes of the guide facets, which may lead to their profile change.The study was based on mathematical modeling and optimization of the cutting zone coordinates. And we find the formula to determine the surface pressure of the guides. The selected parameters of optimization are vectors of the cutting force and values of slides and guides. Obtained results show that a technique for optimization of coordinates in the cutting zone was necessary to increase a processing accuracy.The research has established that to define the optimal coordinates of the cutting zone we have to change the sizes of slides, value and coordinates of applied forces, reaching the pressure equalization and improving the accuracy of positioning system of machine tools. In different points of the workspace a vector of forces is applied, pressure diagrams are found, which take into account the changes in the parameters of positioning system, and the pressure diagram equalization to provide the most accuracy of machine tools is achieved.

Multitemporal Accuracy and Precision Assessment of Unmanned Aerial System Photogrammetry for Slope-Scale Snow Depth Maps in Alpine Terrain

Science.gov (United States)

Adams, Marc S.; Bühler, Yves; Fromm, Reinhard

2017-12-01

Reliable and timely information on the spatio-temporal distribution of snow in alpine terrain plays an important role for a wide range of applications. Unmanned aerial system (UAS) photogrammetry is increasingly applied to cost-efficiently map the snow depth at very high resolution with flexible applicability. However, crucial questions regarding quality and repeatability of this technique are still under discussion. Here we present a multitemporal accuracy and precision assessment of UAS photogrammetry for snow depth mapping on the slope-scale. We mapped a 0.12 km2 large snow-covered study site, located in a high-alpine valley in Western Austria. 12 UAS flights were performed to acquire imagery at 0.05 m ground sampling distance in visible (VIS) and near-infrared (NIR) wavelengths with a modified commercial, off-the-shelf sensor mounted on a custom-built fixed-wing UAS. The imagery was processed with structure-from-motion photogrammetry software to generate orthophotos, digital surface models (DSMs) and snow depth maps (SDMs). Accuracy of DSMs and SDMs were assessed with terrestrial laser scanning and manual snow depth probing, respectively. The results show that under good illumination conditions (study site in full sunlight), the DSMs and SDMs were acquired with an accuracy of ≤ 0.25 and ≤ 0.29 m (both at 1σ), respectively. In case of poorly illuminated snow surfaces (study site shadowed), the NIR imagery provided higher accuracy (0.19 m; 0.23 m) than VIS imagery (0.49 m; 0.37 m). The precision of the UASSDMs was 0.04 m for a small, stable area and below 0.33 m for the whole study site (both at 1σ).

Automatic markerless registration of point clouds with semantic-keypoint-based 4-points congruent sets

Science.gov (United States)

Ge, Xuming

2017-08-01

The coarse registration of point clouds from urban building scenes has become a key topic in applications of terrestrial laser scanning technology. Sampling-based algorithms in the random sample consensus (RANSAC) model have emerged as mainstream solutions to address coarse registration problems. In this paper, we propose a novel combined solution to automatically align two markerless point clouds from building scenes. Firstly, the method segments non-ground points from ground points. Secondly, the proposed method detects feature points from each cross section and then obtains semantic keypoints by connecting feature points with specific rules. Finally, the detected semantic keypoints from two point clouds act as inputs to a modified 4PCS algorithm. Examples are presented and the results compared with those of K-4PCS to demonstrate the main contributions of the proposed method, which are the extension of the original 4PCS to handle heavy datasets and the use of semantic keypoints to improve K-4PCS in relation to registration accuracy and computational efficiency.

Accuracy and reliability of stitched cone-beam computed tomography images

Energy Technology Data Exchange (ETDEWEB)

Egbert, Nicholas [Private Practice, Reconstructive Dental Specialists of Utah, Salt Lake (United States); Cagna, David R.; Ahuja, Swati; Wicks, Russell A. [Dept. of rosthodontics, University of Tennessee Health Science Center College of Dentistry, Memphis (United States)

2015-03-15

This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software. The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

Accuracy and reliability of stitched cone-beam computed tomography images

International Nuclear Information System (INIS)

Egbert, Nicholas; Cagna, David R.; Ahuja, Swati; Wicks, Russell A.

2015-01-01

This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software. The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

Accuracy and reliability of stitched cone-beam computed tomography images.

Science.gov (United States)

Egbert, Nicholas; Cagna, David R; Ahuja, Swati; Wicks, Russell A

2015-03-01

This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturer's imaging software. The same measurements were then taken with the CBCT software. The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

100% classification accuracy considered harmful: the normalized information transfer factor explains the accuracy paradox.

Directory of Open Access Journals (Sweden)

Francisco J Valverde-Albacete

Full Text Available The most widely spread measure of performance, accuracy, suffers from a paradox: predictive models with a given level of accuracy may have greater predictive power than models with higher accuracy. Despite optimizing classification error rate, high accuracy models may fail to capture crucial information transfer in the classification task. We present evidence of this behavior by means of a combinatorial analysis where every possible contingency matrix of 2, 3 and 4 classes classifiers are depicted on the entropy triangle, a more reliable information-theoretic tool for classification assessment. Motivated by this, we develop from first principles a measure of classification performance that takes into consideration the information learned by classifiers. We are then able to obtain the entropy-modulated accuracy (EMA, a pessimistic estimate of the expected accuracy with the influence of the input distribution factored out, and the normalized information transfer factor (NIT, a measure of how efficient is the transmission of information from the input to the output set of classes. The EMA is a more natural measure of classification performance than accuracy when the heuristic to maximize is the transfer of information through the classifier instead of classification error count. The NIT factor measures the effectiveness of the learning process in classifiers and also makes it harder for them to "cheat" using techniques like specialization, while also promoting the interpretability of results. Their use is demonstrated in a mind reading task competition that aims at decoding the identity of a video stimulus based on magnetoencephalography recordings. We show how the EMA and the NIT factor reject rankings based in accuracy, choosing more meaningful and interpretable classifiers.

ACCURACY OF MEASUREMENTS IN OBLIQUE AERIAL IMAGES FOR URBAN ENVIRONMENT

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W. Ostrowski

2016-10-01

Full Text Available Oblique aerial images have been a source of data for urban areas for several years. However, the accuracy of measurements in oblique images during this time has been limited to a single meter due to the use of direct -georeferencing technology and the underlying digital elevation model. Therefore, oblique images have been used mostly for visualization purposes. This situation changed in recent years as new methods, which allowed for a higher accuracy of exterior orientation, were developed. Current developments include the process of determining exterior orientation and the previous but still crucial process of tie point extraction. Progress in this area was shown in the ISPRS/EUROSDR Benchmark on Multi-Platform Photogrammetry and is also noticeable in the growing interest in the use of this kind of imagery. The higher level of accuracy in the orientation of oblique aerial images that has become possible in the last few years should result in a higher level of accuracy in the measurements of these types of images. The main goal of this research was to set and empirically verify the accuracy of measurements in oblique aerial images. The research focused on photogrammetric measurements composed of many images, which use a high overlap within an oblique dataset and different view angles. During the experiments, two series of images of urban areas were used. Both were captured using five DigiCam cameras in a Maltese cross configuration. The tilt angles of the oblique cameras were 45 degrees, and the position of the cameras during flight used a high grade GPS/INS navigation system. The orientation of the images was set using the Pix4D Mapper Pro software with both measurements of the in-flight camera position and the ground control points (measured with GPS RTK technology. To control the accuracy, check points were used (which were also measured with GPS RTK technology. As reference data for the whole study, an area of the city-based map was used

LIFE CYCLE ASSESSMENT AND HAZARD ANALYSIS AND CRITICAL CONTROL POINTS TO THE PASTA PRODUCT

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Yulexis Meneses Linares

2016-10-01

Full Text Available The objective of this work is to combine the Life Cycle Assessment (LCA and Hazard Analysis and Critical Control Points (HACCP methodologies for the determination of risks that the food production represents to the human health and the ecosystem. The environmental performance of the production of pastas in the “Marta Abreu” Pasta Factory of Cienfuegos is assessed, where the critical control points determined by the biological dangers (mushrooms and plagues and the physical dangers (wood, paper, thread and ferromagnetic particles were the raw materials: flour, semolina and its mixtures, and the disposition and extraction of them. Resources are the most affected damage category due to the consumption of fossil fuels.

Efficient point cloud data processing in shipbuilding: Reformative component extraction method and registration method

Directory of Open Access Journals (Sweden)

Jingyu Sun

2014-07-01

Full Text Available To survive in the current shipbuilding industry, it is of vital importance for shipyards to have the ship components’ accuracy evaluated efficiently during most of the manufacturing steps. Evaluating components’ accuracy by comparing each component’s point cloud data scanned by laser scanners and the ship’s design data formatted in CAD cannot be processed efficiently when (1 extract components from point cloud data include irregular obstacles endogenously, or when (2 registration of the two data sets have no clear direction setting. This paper presents reformative point cloud data processing methods to solve these problems. K-d tree construction of the point cloud data fastens a neighbor searching of each point. Region growing method performed on the neighbor points of the seed point extracts the continuous part of the component, while curved surface fitting and B-spline curved line fitting at the edge of the continuous part recognize the neighbor domains of the same component divided by obstacles’ shadows. The ICP (Iterative Closest Point algorithm conducts a registration of the two sets of data after the proper registration’s direction is decided by principal component analysis. By experiments conducted at the shipyard, 200 curved shell plates are extracted from the scanned point cloud data, and registrations are conducted between them and the designed CAD data using the proposed methods for an accuracy evaluation. Results show that the methods proposed in this paper support the accuracy evaluation targeted point cloud data processing efficiently in practice.

Grade Point Average System of Assessment: the Implementation Peculiarities in Russia

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B. A. Sazonov

2012-01-01

Full Text Available The paper analyzes the specificity, as well as flaws and faults of implementing the Grade Point Average (GPA system of students’ personal assessment in Russian higher schools. Nowadays, the above system is regarded as the basic functional element of educational process organization at the world’s leading universities. The author summarizes the foreign experience and demonstrates the advantages of the GPA system in comparison with the traditional domestic scale of assessment: full records of student’s assessment, objectivity, activation of responsibility for the results achieved, and self-control motivation. The standard GPA model is demonstrated, its application systemizing both the Russian and European requirements to the higher school graduates. The author suggests his own version of the assessment scale estimating and comparing the quality of education in Russian universities and worldwide. The research findings can be of interest to the specialists in the sphere of quality measurement and educational management. 

Variational estimates of point-kinetics parameters

International Nuclear Information System (INIS)

Favorite, J.A.; Stacey, W.M. Jr.

1995-01-01

Variational estimates of the effect of flux shifts on the integral reactivity parameter of the point-kinetics equations and on regional power fractions were calculated for a variety of localized perturbations in two light water reactor (LWR) model problems representing a small, tightly coupled core and a large, loosely coupled core. For the small core, the flux shifts resulting from even relatively large localized reactivity changes (∼600 pcm) were small, and the standard point-kinetics approximation estimates of reactivity were in error by only ∼10% or less, while the variational estimates were accurate to within ∼1%. For the larger core, significant (>50%) flux shifts occurred in response to local perturbations, leading to errors of the same magnitude in the standard point-kinetics approximation of the reactivity worth. For positive reactivity, the error in the variational estimate of reactivity was only a few percent in the larger core, and the resulting transient power prediction was 1 to 2 orders of magnitude more accurate than with the standard point-kinetics approximation. For a large, local negative reactivity insertion resulting in a large flux shift, the accuracy of the variational estimate broke down. The variational estimate of the effect of flux shifts on reactivity in point-kinetics calculations of transients in LWR cores was found to generally result in greatly improved accuracy, relative to the standard point-kinetics approximation, the exception being for large negative reactivity insertions with large flux shifts in large, loosely coupled cores

Maintenance of equilibrium point control during an unexpectedly loaded rapid limb movement.

Science.gov (United States)

Simmons, R W; Richardson, C

1984-06-08

Two experiments investigated whether the equilibrium point hypothesis or the mass-spring model of motor control subserves positioning accuracy during spring loaded, rapid, bi-articulated movement. For intact preparations, the equilibrium point hypothesis predicts response accuracy to be determined by a mixture of afferent and efferent information, whereas the mass-spring model predicts positioning to be under a direct control system. Subjects completed a series of load-resisted training trials to a spatial target. The magnitude of a sustained spring load was unexpectedly increased on selected trials. Results indicated positioning accuracy and applied force varied with increases in load, which suggests that the original efferent commands are modified by afferent information during the movement as predicted by the equilibrium point hypothesis.

Effects of orbit and pointing geometry of a spaceborne formation for monostatic-bistatic radargrammetry on terrain elevation measurement accuracy.

Science.gov (United States)

Renga, Alfredo; Moccia, Antonio

2009-01-01

During the last decade a methodology for the reconstruction of surface relief by Synthetic Aperture Radar (SAR) measurements - SAR interferometry - has become a standard. Different techniques developed before, such as stereo-radargrammetry, have been experienced from space only in very limiting geometries and time series, and, hence, branded as less accurate. However, novel formation flying configurations achievable by modern spacecraft allow fulfillment of SAR missions able to produce pairs of monostatic-bistatic images gathered simultaneously, with programmed looking angles. Hence it is possible to achieve large antenna separations, adequate for exploiting to the utmost the stereoscopic effect, and to make negligible time decorrelation, a strong liming factor for repeat-pass stereo-radargrammetric techniques. This paper reports on design of a monostatic-bistatic mission, in terms of orbit and pointing geometry, and taking into account present generation SAR and technology for accurate relative navigation. Performances of different methods for monostatic-bistatic stereo-radargrammetry are then evaluated, showing the possibility to determine the local surface relief with a metric accuracy over a wide range of Earth latitudes.

Assessment of the accuracy and reliability of the Topcon CT80 non-contact tonometer.

Science.gov (United States)

Ogbuehi, Kelechi C

2006-09-01

The reliability of non-contact tonometers has been reported extensively in the literature. This study was designed to assess reliability of the new Topcon CT80 non-contact tonometer in normotensive subjects, using the Goldmann tonometer as the standard. The accuracy of the Topcon CT 80 non-contact tonometer was assessed by comparing its IOP assessments with those of the Goldmann applanation tonometer, on 60 right eyes of young healthy subjects with normal intraocular pressures. Each subject's intraocular pressure was assessed with each technique on two separate occasions, one week apart. The reliability of each technique was determined by the assessment of its inter-session repeatability using the Bland-Altman method. The 95 per cent limits of agreement for the two methods were also determined. No statistically significant difference was found between the average intraocular pressures measured with the two techniques (p > 0.05). The inter-session repeatability indices for the two techniques did not differ significantly (p > 0.05). The mean difference in intraocular measurements between the two techniques was 0.2 +/- 1.5 mmHg (mean +/- SD) and the 95 per cent limits of agreement were -3.14 and +2.74 mmHg, with the non-contact tonometer returning higher readings than the Goldmann tonometer. In this sample of normotensive subjects, the Topcon CT80 non-contact tonometer proved to be accurate and as reliable as the Goldmann tonometer in the assessment of intraocular pressure. Thus, it can be used as an objective clinical method for the assessment of normal intraocular pressure.

Coordinate alignment of combined measurement systems using a modified common points method

Science.gov (United States)

Zhao, G.; Zhang, P.; Xiao, W.

2018-03-01

The co-ordinate metrology has been extensively researched for its outstanding advantages in measurement range and accuracy. The alignment of different measurement systems is usually achieved by integrating local coordinates via common points before measurement. The alignment errors would accumulate and significantly reduce the global accuracy, thus need to be minimized. In this thesis, a modified common points method (MCPM) is proposed to combine different traceable system errors of the cooperating machines, and optimize the global accuracy by introducing mutual geometric constraints. The geometric constraints, obtained by measuring the common points in individual local coordinate systems, provide the possibility to reduce the local measuring uncertainty whereby enhance the global measuring certainty. A simulation system is developed in Matlab to analyze the feature of MCPM using the Monto-Carlo method. An exemplary setup is constructed to verify the feasibility and efficiency of the proposed method associated with laser tracker and indoor iGPS systems. Experimental results show that MCPM could significantly improve the alignment accuracy.

Set point calculations for RAPID project

International Nuclear Information System (INIS)

HICKMAN, G.L.

1999-01-01

This change modifies accuracies of the water skid temperature indicators and controllers TIC-410. TI-412, TI-413, TIC-413, TIC-414, TIC-415. Acknowledges ability to calibrate PQIT-367 and modifies the accuracy of that instrument loop. Adjusts the allowable dilution dater temperature from 110-130F to 102-130F based on PCP Rev.2 and adjusts alarm and other points to reflect that change. Removes revision numbers for all references. Numerous additional changes (fixing typos, more detailed explanations etc.) throughout

Accuracy assessment of digital surface models based on a small format action camera in a North-East Hungarian sample area

Directory of Open Access Journals (Sweden)

Barkóczi Norbert

2017-01-01

Full Text Available The use of the small format digital action cameras has been increased in the past few years in various applications, due to their low budget cost, flexibility and reliability. We can mount these small cameras on several devices, like unmanned air vehicles (UAV and create 3D models with photogrammetric technique. Either creating or receiving these kind of databases, one of the most important questions will always be that how accurate these systems are, what the accuracy that can be achieved is. We gathered the overlapping images, created point clouds, and then we generated 21 different digital surface models (DSM. The differences based on the number of images we used in each model, and on the flight height. We repeated the flights three times, to compare the same models with each other. Besides, we measured 129 reference points with RTK-GPS, to compare the height differences with the extracted cell values from each DSM. The results showed that higher flight height has lower errors, and the optimal air base distance is one fourth of the flying height in both cases. The lowest median was 0.08 meter, at the 180 meter flight, 50 meter air base distance model. Raising the number of images does not increase the overall accuracy. The connection between the amount of error and distance from the nearest GCP is not linear in every case.

A laboratory assessment of the measurement accuracy of weighing type rainfall intensity gauges

Science.gov (United States)

Colli, M.; Chan, P. W.; Lanza, L. G.; La Barbera, P.

2012-04-01

In recent years the WMO Commission for Instruments and Methods of Observation (CIMO) fostered noticeable advancements in the accuracy of precipitation measurement issue by providing recommendations on the standardization of equipment and exposure, instrument calibration and data correction as a consequence of various comparative campaigns involving manufacturers and national meteorological services from the participating countries (Lanza et al., 2005; Vuerich et al., 2009). Extreme events analysis is proven to be highly affected by the on-site RI measurement accuracy (see e.g. Molini et al., 2004) and the time resolution of the available RI series certainly constitutes another key-factor in constructing hyetographs that are representative of real rain events. The OTT Pluvio2 weighing gauge (WG) and the GEONOR T-200 vibrating-wire precipitation gauge demonstrated very good performance under previous constant flow rate calibration efforts (Lanza et al., 2005). Although WGs do provide better performance than more traditional Tipping Bucket Rain gauges (TBR) under continuous and constant reference intensity, dynamic effects seem to affect the accuracy of WG measurements under real world/time varying rainfall conditions (Vuerich et al., 2009). The most relevant is due to the response time of the acquisition system and the derived systematic delay of the instrument in assessing the exact weight of the bin containing cumulated precipitation. This delay assumes a relevant role in case high resolution rain intensity time series are sought from the instrument, as is the case of many hydrologic and meteo-climatic applications. This work reports the laboratory evaluation of Pluvio2 and T-200 rainfall intensity measurements accuracy. Tests are carried out by simulating different artificial precipitation events, namely non-stationary rainfall intensity, using a highly accurate dynamic rainfall generator. Time series measured by an Ogawa drop counter (DC) at a field test site