Science.gov

Sample records for accuracy precision recovery

  1. Bullet trajectory reconstruction - Methods, accuracy and precision.

    PubMed

    Mattijssen, Erwin J A T; Kerkhoff, Wim

    2016-05-01

    Based on the spatial relation between a primary and secondary bullet defect or on the shape and dimensions of the primary bullet defect, a bullet's trajectory prior to impact can be estimated for a shooting scene reconstruction. The accuracy and precision of the estimated trajectories will vary depending on variables such as, the applied method of reconstruction, the (true) angle of incidence, the properties of the target material and the properties of the bullet upon impact. This study focused on the accuracy and precision of estimated bullet trajectories when different variants of the probing method, ellipse method, and lead-in method are applied on bullet defects resulting from shots at various angles of incidence on drywall, MDF and sheet metal. The results show that in most situations the best performance (accuracy and precision) is seen when the probing method is applied. Only for the lowest angles of incidence the performance was better when either the ellipse or lead-in method was applied. The data provided in this paper can be used to select the appropriate method(s) for reconstruction and to correct for systematic errors (accuracy) and to provide a value of the precision, by means of a confidence interval of the specific measurement.

  2. Precision cosmology, Accuracy cosmology and Statistical cosmology

    NASA Astrophysics Data System (ADS)

    Verde, Licia

    2014-05-01

    The avalanche of data over the past 10-20 years has propelled cosmology into the ``precision era''. The next challenge cosmology has to meet is to enter the era of accuracy. Because of the intrinsic nature of studying the Cosmos and the sheer amount of data available now and coming soon, the only way to meet this challenge is by developing suitable and specific statistical techniques. The road from precision Cosmology to accurate Cosmology goes through statistical Cosmology. I will outline some open challenges and discuss some specific examples.

  3. Ultra-wideband ranging precision and accuracy

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    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.

  4. Accuracy and Precision of an IGRT Solution

    SciTech Connect

    Webster, Gareth J. Rowbottom, Carl G.; Mackay, Ranald I.

    2009-07-01

    Image-guided radiotherapy (IGRT) can potentially improve the accuracy of delivery of radiotherapy treatments by providing high-quality images of patient anatomy in the treatment position that can be incorporated into the treatment setup. The achievable accuracy and precision of delivery of highly complex head-and-neck intensity modulated radiotherapy (IMRT) plans with an IGRT technique using an Elekta Synergy linear accelerator and the Pinnacle Treatment Planning System (TPS) was investigated. Four head-and-neck IMRT plans were delivered to a semi-anthropomorphic head-and-neck phantom and the dose distribution was measured simultaneously by up to 20 microMOSFET (metal oxide semiconductor field-effect transmitter) detectors. A volumetric kilovoltage (kV) x-ray image was then acquired in the treatment position, fused with the phantom scan within the TPS using Syntegra software, and used to recalculate the dose with the precise delivery isocenter at the actual position of each detector within the phantom. Three repeat measurements were made over a period of 2 months to reduce the effect of random errors in measurement or delivery. To ensure that the noise remained below 1.5% (1 SD), minimum doses of 85 cGy were delivered to each detector. The average measured dose was systematically 1.4% lower than predicted and was consistent between repeats. Over the 4 delivered plans, 10/76 measurements showed a systematic error > 3% (3/76 > 5%), for which several potential sources of error were investigated. The error was ultimately attributable to measurements made in beam penumbrae, where submillimeter positional errors result in large discrepancies in dose. The implementation of an image-guided technique improves the accuracy of dose verification, particularly within high-dose gradients. The achievable accuracy of complex IMRT dose delivery incorporating image-guidance is within {+-} 3% in dose over the range of sample points. For some points in high-dose gradients

  5. [History, accuracy and precision of SMBG devices].

    PubMed

    Dufaitre-Patouraux, L; Vague, P; Lassmann-Vague, V

    2003-04-01

    Self-monitoring of blood glucose started only fifty years ago. Until then metabolic control was evaluated by means of qualitative urinary blood measure often of poor reliability. Reagent strips were the first semi quantitative tests to monitor blood glucose, and in the late seventies meters were launched on the market. Initially the use of such devices was intended for medical staff, but thanks to handiness improvement they became more and more adequate to patients and are now a necessary tool for self-blood glucose monitoring. The advanced technologies allow to develop photometric measurements but also more recently electrochemical one. In the nineties, improvements were made mainly in meters' miniaturisation, reduction of reaction time and reading, simplification of blood sampling and capillary blood laying. Although accuracy and precision concern was in the heart of considerations at the beginning of self-blood glucose monitoring, the recommendations of societies of diabetology came up in the late eighties. Now, the French drug agency: AFSSAPS asks for a control of meter before any launching on the market. According to recent publications very few meters meet reliability criteria set up by societies of diabetology in the late nineties. Finally because devices may be handled by numerous persons in hospitals, meters use as possible source of nosocomial infections have been recently questioned and is subject to very strict guidelines published by AFSSAPS.

  6. Establishing precision and accuracy in PDV results

    SciTech Connect

    Briggs, Matthew E.; Howard, Marylesa; Diaz, Abel

    2016-04-19

    We need to know uncertainties and systematic errors because we create and compare against archival weapons data, we constrain the models, and we provide scientific results. Good estimates of precision from the data record are available and should be incorporated into existing results; reanalysis of valuable data is suggested. Estimates of systematic errors are largely absent. The original work by Jensen et al. using gun shots for window corrections, and the integrated velocity comparison with X-rays by Schultz are two examples where any systematic errors appear to be <1% level.

  7. Precision and Accuracy of Topography Measurements on Europa

    NASA Astrophysics Data System (ADS)

    Greenberg, R.; Hurford, T. A.; Foley, M. A.; Varland, K.

    2007-03-01

    Reports of the death of the melt-through model for chaotic terrain on Europa have been greatly exaggerated, to paraphrase Mark Twain. They are based on topographic maps of insufficient quantitative accuracy and precision.

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

    SciTech Connect

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

    1989-06-22

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

  9. On precision and accuracy (bias) statements for measurement procedures

    SciTech Connect

    Bruckner, L.A.; Hume, M.W.; Delvin, W.L.

    1988-01-01

    Measurement procedures are often required to contain precision and accuracy of precision and bias statements. This paper contains a glossary that explains various terms that often appear in these statements as well as an example illustrating such statements for a specific set of data. Precision and bias statements are shown to vary according to the conditions under which the data were collected. This paper emphasizes that the error model (an algebraic expression that describes how the various sources of variation affect the measurement) is an important consideration in the formation of precision and bias statements.

  10. Accuracy and precision of temporal artery thermometers in febrile patients.

    PubMed

    Wolfson, Margaret; Granstrom, Patsy; Pomarico, Bernie; Reimanis, Cathryn

    2013-01-01

    The noninvasive temporal artery thermometer offers a way to measure temperature when oral assessment is contraindicated, uncomfortable, or difficult to obtain. In this study, the accuracy and precision of the temporal artery thermometer exceeded levels recommended by experts for use in acute care clinical practice.

  11. Precise RFID localization in impaired environment through sparse signal recovery

    NASA Astrophysics Data System (ADS)

    Subedi, Saurav; Zhang, Yimin D.; Amin, Moeness G.

    2013-05-01

    Radio frequency identification (RFID) is a rapidly developing wireless communication technology for electronically identifying, locating, and tracking products, assets, and personnel. RFID has become one of the most important means to construct real-time locating systems (RTLS) that track and identify the location of objects in real time using simple, inexpensive tags and readers. The applicability and usefulness of RTLS techniques depend on their achievable accuracy. In particular, when multilateration-based localization techniques are exploited, the achievable accuracy primarily relies on the precision of the range estimates between a reader and the tags. Such range information can be obtained by using the received signal strength indicator (RSSI) and/or the phase difference of arrival (PDOA). In both cases, however, the accuracy is significantly compromised when the operation environment is impaired. In particular, multipath propagation significantly affects the measurement accuracy of both RSSI and phase information. In addition, because RFID systems are typically operated in short distances, RSSI and phase measurements are also coupled with the reader and tag antenna patterns, making accurate RFID localization very complicated and challenging. In this paper, we develop new methods to localize RFID tags or readers by exploiting sparse signal recovery techniques. The proposed method allows the channel environment and antenna patterns to be taken into account and be properly compensated at a low computational cost. As such, the proposed technique yields superior performance in challenging operation environments with the above-mentioned impairments.

  12. Characterizing geometric accuracy and precision in image guided gated radiotherapy

    NASA Astrophysics Data System (ADS)

    Tenn, Stephen Edward

    Gated radiotherapy combined with intensity modulated or three-dimensional conformal radiotherapy for tumors in the thorax and abdomen can deliver dose distributions which conform closely to tumor shapes allowing increased tumor dose while sparing healthy tissues. These conformal fields require more accurate and precise placement than traditional fields or tumors may receive suboptimal dose thereby reducing tumor control probability. Image guidance based on four-dimensional computed tomography (4DCT) provides a means to improve accuracy and precision in radiotherapy. The ability of 4DCT to accurately reproduce patient geometry and the ability of image guided gating equipment to position tumors and place fields around them must be characterized in order to determine treatment parameters such as tumor margins. Fiducial based methods of characterizing accuracy and precision of equipment for 4DCT planning and image guided gated radiotherapy (IGGRT) are presented with results for specific equipment. Fiducial markers of known geometric orientation are used to characterize 4DCT image reconstruction accuracy. Accuracy is determined under different acquisition protocols, reconstruction phases, and phantom trajectories. Targeting accuracy of fiducial based image guided gating is assessed by measuring in-phantom field positions for different motions, gating levels and target rotations. Synchronization parameters for gating equipment are also determined. Finally, end-to-end testing is performed to assess overall accuracy and precision of the equipment under controlled conditions. 4DCT limits fiducial geometric distance errors to 2 mm for repeatable target trajectories and to 5 mm for a pseudo-random trajectory. Largest offsets were in the longitudinal direction. If correctly calibrated and synchronized, the IGGRT system tested here can target reproducibly moving tumors with accuracy better than 1.2 mm. Gating level can affect accuracy if target motion is asymmetric about the

  13. Accuracy, precision, and lower detection limits (a deficit reduction approach)

    SciTech Connect

    Bishop, C.T.

    1993-10-12

    The evaluation of the accuracy, precision and lower detection limits of the determination of trace radionuclides in environmental samples can become quite sophisticated and time consuming. This in turn could add significant cost to the analyses being performed. In the present method, a {open_quotes}deficit reduction approach{close_quotes} has been taken to keep costs low, but at the same time provide defensible data. In order to measure the accuracy of a particular method, reference samples are measured over the time period that the actual samples are being analyzed. Using a Lotus spreadsheet, data are compiled and an average accuracy is computed. If pairs of reference samples are analyzed, then precision can also be evaluated from the duplicate data sets. The standard deviation can be calculated if the reference concentrations of the duplicates are all in the same general range. Laboratory blanks are used to estimate the lower detection limits. The lower detection limit is calculated as 4.65 times the standard deviation of a set of blank determinations made over a given period of time. A Lotus spreadsheet is again used to compile data and LDLs over different periods of time can be compared.

  14. The Plus or Minus Game - Teaching Estimation, Precision, and Accuracy

    NASA Astrophysics Data System (ADS)

    Forringer, Edward R.; Forringer, Richard S.; Forringer, Daniel S.

    2016-03-01

    A quick survey of physics textbooks shows that many (Knight, Young, and Serway for example) cover estimation, significant digits, precision versus accuracy, and uncertainty in the first chapter. Estimation "Fermi" questions are so useful that there has been a column dedicated to them in TPT (Larry Weinstein's "Fermi Questions.") For several years the authors (a college physics professor, a retired algebra teacher, and a fifth-grade teacher) have been playing a game, primarily at home to challenge each other for fun, but also in the classroom as an educational tool. We call the game "The Plus or Minus Game." The game combines estimation with the principle of precision and uncertainty in a competitive and fun way.

  15. Calibration, linearity, precision, and accuracy of a PIXE system

    NASA Astrophysics Data System (ADS)

    Richter, F.-W.; Wätjen, U.

    1984-04-01

    An accuracy and precision of better than 10% each can be achieved with PIXE analysis, with both thin and thick samples. Measures we took to obtain these values for routine analyses in the Marburg PIXE system are discussed. The advantages of an experimental calibration procedure, using thin evaporated standard foils, over the "absolute" method of employing X-ray production cross sections are outlined. The importance of X-ray line intensity ratios, even of weak transitions, for the accurate analysis of interfering elements of low mass content is demonstrated for the Se K α-Pb L ηline overlap. Matrix effects including secondary excitation can be corrected for very well without degrading accuracy under certain conditions.

  16. Fluorescence Axial Localization with Nanometer Accuracy and Precision

    SciTech Connect

    Li, Hui; Yen, Chi-Fu; Sivasankar, Sanjeevi

    2012-06-15

    We describe a new technique, standing wave axial nanometry (SWAN), to image the axial location of a single nanoscale fluorescent object with sub-nanometer accuracy and 3.7 nm precision. A standing wave, generated by positioning an atomic force microscope tip over a focused laser beam, is used to excite fluorescence; axial position is determined from the phase of the emission intensity. We use SWAN to measure the orientation of single DNA molecules of different lengths, grafted on surfaces with different functionalities.

  17. On the recovery of gravity anomalies from high precision altimeter data

    NASA Technical Reports Server (NTRS)

    Lelgemann, D.

    1976-01-01

    A model for the recovery of gravity anomalies from high precision altimeter data is derived which consists of small correction terms to the inverse Stokes' formula. The influence of unknown sea surface topography in the case of meandering currents such as the Gulf Stream is discussed. A formula was derived in order to estimate the accuracy of the gravity anomalies from the known accuracy of the altimeter data. It is shown that for the case of known harmonic coefficients of lower order the range of integration in Stokes inverse formula can be reduced very much.

  18. Improved DORIS accuracy for precise orbit determination and geodesy

    NASA Technical Reports Server (NTRS)

    Willis, Pascal; Jayles, Christian; Tavernier, Gilles

    2004-01-01

    In 2001 and 2002, 3 more DORIS satellites were launched. Since then, all DORIS results have been significantly improved. For precise orbit determination, 20 cm are now available in real-time with DIODE and 1.5 to 2 cm in post-processing. For geodesy, 1 cm precision can now be achieved regularly every week, making now DORIS an active part of a Global Observing System for Geodesy through the IDS.

  19. Mineral element analyses of switchgrass biomass: comparison of the accuracy and precision of laboratories

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mineral concentration of plant biomass can affect its use in thermal conversion to energy. The objective of this study was to compare the precision and accuracy of university and private laboratories that conduct mineral analyses of plant biomass on a fee basis. Accuracy and precision of the laborat...

  20. S-193 scatterometer backscattering cross section precision/accuracy for Skylab 2 and 3 missions

    NASA Technical Reports Server (NTRS)

    Krishen, K.; Pounds, D. J.

    1975-01-01

    Procedures for measuring the precision and accuracy with which the S-193 scatterometer measured the background cross section of ground scenes are described. Homogeneous ground sites were selected, and data from Skylab missions were analyzed. The precision was expressed as the standard deviation of the scatterometer-acquired backscattering cross section. In special cases, inference of the precision of measurement was made by considering the total range from the maximum to minimum of the backscatter measurements within a data segment, rather than the standard deviation. For Skylab 2 and 3 missions a precision better than 1.5 dB is indicated. This procedure indicates an accuracy of better than 3 dB for the Skylab 2 and 3 missions. The estimates of precision and accuracy given in this report are for backscattering cross sections from -28 to 18 dB. Outside this range the precision and accuracy decrease significantly.

  1. Accuracy and Precision of GPS Carrier-Phase Clock Estimates

    DTIC Science & Technology

    2001-01-01

    L‘Geodesy using the Global Positioning System : The eflects of signal scattering o n esti- mates of site positions , ” Journal of Geophysical Research...maia.usno.navy.mil Abstract The accuracy of GPS -based clock estimates is determined by the pseudorange data. For 24-hour arcs of global data sampled...ps) for 1-day integrations. Assuming such positioning results can be realized also as equivalent light-travel times, the po- tential of GPS carrier

  2. Spectropolarimetry with PEPSI at the LBT: accuracy vs. precision in magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Ilyin, Ilya; Strassmeier, Klaus G.; Woche, Manfred; Hofmann, Axel

    2009-04-01

    We present the design of the new PEPSI spectropolarimeter to be installed at the Large Binocular Telescope (LBT) in Arizona to measure the full set of Stokes parameters in spectral lines and outline its precision and the accuracy limiting factors.

  3. Precision and Accuracy in Measurements: A Tale of Four Graduated Cylinders.

    ERIC Educational Resources Information Center

    Treptow, Richard S.

    1998-01-01

    Expands upon the concepts of precision and accuracy at a level suitable for general chemistry. Serves as a bridge to the more extensive treatments in analytical chemistry textbooks and the advanced literature on error analysis. Contains 22 references. (DDR)

  4. Accuracy and Precision of Silicon Based Impression Media for Quantitative Areal Texture Analysis

    PubMed Central

    Goodall, Robert H.; Darras, Laurent P.; Purnell, Mark A.

    2015-01-01

    Areal surface texture analysis is becoming widespread across a diverse range of applications, from engineering to ecology. In many studies silicon based impression media are used to replicate surfaces, and the fidelity of replication defines the quality of data collected. However, while different investigators have used different impression media, the fidelity of surface replication has not been subjected to quantitative analysis based on areal texture data. Here we present the results of an analysis of the accuracy and precision with which different silicon based impression media of varying composition and viscosity replicate rough and smooth surfaces. Both accuracy and precision vary greatly between different media. High viscosity media tested show very low accuracy and precision, and most other compounds showed either the same pattern, or low accuracy and high precision, or low precision and high accuracy. Of the media tested, mid viscosity President Jet Regular Body and low viscosity President Jet Light Body (Coltène Whaledent) are the only compounds to show high levels of accuracy and precision on both surface types. Our results show that data acquired from different impression media are not comparable, supporting calls for greater standardisation of methods in areal texture analysis. PMID:25991505

  5. Accuracy and Precision of Silicon Based Impression Media for Quantitative Areal Texture Analysis

    NASA Astrophysics Data System (ADS)

    Goodall, Robert H.; Darras, Laurent P.; Purnell, Mark A.

    2015-05-01

    Areal surface texture analysis is becoming widespread across a diverse range of applications, from engineering to ecology. In many studies silicon based impression media are used to replicate surfaces, and the fidelity of replication defines the quality of data collected. However, while different investigators have used different impression media, the fidelity of surface replication has not been subjected to quantitative analysis based on areal texture data. Here we present the results of an analysis of the accuracy and precision with which different silicon based impression media of varying composition and viscosity replicate rough and smooth surfaces. Both accuracy and precision vary greatly between different media. High viscosity media tested show very low accuracy and precision, and most other compounds showed either the same pattern, or low accuracy and high precision, or low precision and high accuracy. Of the media tested, mid viscosity President Jet Regular Body and low viscosity President Jet Light Body (Coltène Whaledent) are the only compounds to show high levels of accuracy and precision on both surface types. Our results show that data acquired from different impression media are not comparable, supporting calls for greater standardisation of methods in areal texture analysis.

  6. [Assessment of precision and accuracy of digital surface photogrammetry with the DSP 400 system].

    PubMed

    Krimmel, M; Kluba, S; Dietz, K; Reinert, S

    2005-03-01

    The objective of the present study was to evaluate the precision and accuracy of facial anthropometric measurements obtained through digital 3-D surface photogrammetry with the DSP 400 system in comparison to traditional 2-D photogrammetry. Fifty plaster casts of cleft infants were imaged and 21 standard anthropometric measurements were obtained. For precision assessment the measurements were performed twice in a subsample. Accuracy was determined by comparison of direct measurements and indirect 2-D and 3-D image measurements. Precision of digital surface photogrammetry was almost as good as direct anthropometry and clearly better than 2-D photogrammetry. Measurements derived from 3-D images showed better congruence to direct measurements than from 2-D photos. Digital surface photogrammetry with the DSP 400 system is sufficiently precise and accurate for craniofacial anthropometric examinations.

  7. A Comparison of the Astrometric Precision and Accuracy of Double Star Observations with Two Telescopes

    NASA Astrophysics Data System (ADS)

    Alvarez, Pablo; Fishbein, Amos E.; Hyland, Michael W.; Kight, Cheyne L.; Lopez, Hairold; Navarro, Tanya; Rosas, Carlos A.; Schachter, Aubrey E.; Summers, Molly A.; Weise, Eric D.; Hoffman, Megan A.; Mires, Robert C.; Johnson, Jolyon M.; Genet, Russell M.; White, Robin

    2009-01-01

    Using a manual Meade 6" Newtonian telescope and a computerized Meade 10" Schmidt-Cassegrain telescope, students from Arroyo Grande High School measured the well-known separation and position angle of the bright visual double star Albireo. The precision and accuracy of the observations from the two telescopes were compared to each other and to published values of Albireo taken as the standard. It was hypothesized that the larger, computerized telescope would be both more precise and more accurate.

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

    PubMed

    Sanders, Geoff; Sinclair, Kamila

    2011-12-01

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

  9. Accuracy and Precision of Partial-Volume Correction in Oncological PET/CT Studies.

    PubMed

    Cysouw, Matthijs C F; Kramer, Gerbrand Maria; Hoekstra, Otto S; Frings, Virginie; de Langen, Adrianus Johannes; Smit, Egbert F; van den Eertwegh, Alfons J M; Oprea-Lager, Daniela E; Boellaard, Ronald

    2016-10-01

    Accurate quantification of tracer uptake in small tumors using PET is hampered by the partial-volume effect as well as by the method of volume-of-interest (VOI) delineation. This study aimed to investigate the effect of partial-volume correction (PVC) combined with several VOI methods on the accuracy and precision of quantitative PET.

  10. Improving the accuracy and precision of cognitive testing in mild dementia.

    PubMed

    Wouters, Hans; Appels, Bregje; van der Flier, Wiesje M; van Campen, Jos; Klein, Martin; Zwinderman, Aeilko H; Schmand, Ben; van Gool, Willem A; Scheltens, Philip; Lindeboom, Robert

    2012-03-01

    The CAMCOG, ADAS-cog, and MMSE, designed to grade global cognitive ability in dementia have inadequate precision and accuracy in distinguishing mild dementia from normal ageing. Adding neuropsychological tests to their scale might improve precision and accuracy in mild dementia. We, therefore, pooled neuropsychological test-batteries from two memory clinics (ns = 135 and 186) with CAMCOG data from a population study and 2 memory clinics (n = 829) and ADAS-cog data from 3 randomized controlled trials (n = 713) to estimate a common dimension of global cognitive ability using Rasch analysis. Item difficulties and individuals' global cognitive ability levels were estimated. Difficulties of 57 items (of 64) could be validly estimated. Neuropsychological tests were more difficult than the CAMCOG, ADAS-cog, and MMSE items. Most neuropsychological tests had difficulties in the ability range of normal ageing to mild dementia. Higher than average ability levels were more precisely measured when neuropsychological tests were added to the MMSE than when these were measured with the MMSE alone. Diagnostic accuracy in mild dementia was consistently better after adding neuropsychological tests to the MMSE. We conclude that extending dementia specific instruments with neuropsychological tests improves measurement precision and accuracy of cognitive impairment in mild dementia.

  11. The Plus or Minus Game--Teaching Estimation, Precision, and Accuracy

    ERIC Educational Resources Information Center

    Forringer, Edward R.; Forringer, Richard S.; Forringer, Daniel S.

    2016-01-01

    A quick survey of physics textbooks shows that many (Knight, Young, and Serway for example) cover estimation, significant digits, precision versus accuracy, and uncertainty in the first chapter. Estimation "Fermi" questions are so useful that there has been a column dedicated to them in "TPT" (Larry Weinstein's "Fermi…

  12. 40 CFR 80.584 - What are the precision and accuracy criteria for approval of test methods for determining the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 16 2011-07-01 2011-07-01 false What are the precision and accuracy....584 What are the precision and accuracy criteria for approval of test methods for determining the sulfur content of motor vehicle diesel fuel, NRLM diesel fuel, and ECA marine fuel? (a) Precision....

  13. 40 CFR 80.584 - What are the precision and accuracy criteria for approval of test methods for determining the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What are the precision and accuracy....584 What are the precision and accuracy criteria for approval of test methods for determining the sulfur content of motor vehicle diesel fuel, NRLM diesel fuel, and ECA marine fuel? (a) Precision....

  14. Commissioning Procedures for Mechanical Precision and Accuracy in a Dedicated LINAC

    NASA Astrophysics Data System (ADS)

    Ballesteros-Zebadúa, P.; Lárrga-Gutierrez, J. M.; García-Garduño, O. A.; Juárez, J.; Prieto, I.; Moreno-Jiménez, S.; Celis, M. A.

    2008-08-01

    Mechanical precision measurements are fundamental procedures for the commissioning of a dedicated LINAC. At our Radioneurosurgery Unit, these procedures can be suitable as quality assurance routines that allow the verification of the equipment geometrical accuracy and precision. In this work mechanical tests were performed for gantry and table rotation, obtaining mean associated uncertainties of 0.3 mm and 0.71 mm, respectively. Using an anthropomorphic phantom and a series of localized surface markers, isocenter accuracy showed to be smaller than 0.86 mm for radiosurgery procedures and 0.95 mm for fractionated treatments with mask. All uncertainties were below tolerances. The highest contribution to mechanical variations is due to table rotation, so it is important to correct variations using a localization frame with printed overlays. Mechanical precision knowledge would allow to consider the statistical errors in the treatment planning volume margins.

  15. Commissioning Procedures for Mechanical Precision and Accuracy in a Dedicated LINAC

    SciTech Connect

    Ballesteros-Zebadua, P.; Larrga-Gutierrez, J. M.; Garcia-Garduno, O. A.; Juarez, J.; Prieto, I.; Moreno-Jimenez, S.; Celis, M. A.

    2008-08-11

    Mechanical precision measurements are fundamental procedures for the commissioning of a dedicated LINAC. At our Radioneurosurgery Unit, these procedures can be suitable as quality assurance routines that allow the verification of the equipment geometrical accuracy and precision. In this work mechanical tests were performed for gantry and table rotation, obtaining mean associated uncertainties of 0.3 mm and 0.71 mm, respectively. Using an anthropomorphic phantom and a series of localized surface markers, isocenter accuracy showed to be smaller than 0.86 mm for radiosurgery procedures and 0.95 mm for fractionated treatments with mask. All uncertainties were below tolerances. The highest contribution to mechanical variations is due to table rotation, so it is important to correct variations using a localization frame with printed overlays. Mechanical precision knowledge would allow to consider the statistical errors in the treatment planning volume margins.

  16. Evaluation of the Accuracy and Precision of a Next Generation Computer-Assisted Surgical System

    PubMed Central

    Dai, Yifei; Liebelt, Ralph A.; Gao, Bo; Gulbransen, Scott W.; Silver, Xeve S.

    2015-01-01

    Background Computer-assisted orthopaedic surgery (CAOS) improves accuracy and reduces outliers in total knee arthroplasty (TKA). However, during the evaluation of CAOS systems, the error generated by the guidance system (hardware and software) has been generally overlooked. Limited information is available on the accuracy and precision of specific CAOS systems with regard to intraoperative final resection measurements. The purpose of this study was to assess the accuracy and precision of a next generation CAOS system and investigate the impact of extra-articular deformity on the system-level errors generated during intraoperative resection measurement. Methods TKA surgeries were performed on twenty-eight artificial knee inserts with various types of extra-articular deformity (12 neutral, 12 varus, and 4 valgus). Surgical resection parameters (resection depths and alignment angles) were compared between postoperative three-dimensional (3D) scan-based measurements and intraoperative CAOS measurements. Using the 3D scan-based measurements as control, the accuracy (mean error) and precision (associated standard deviation) of the CAOS system were assessed. The impact of extra-articular deformity on the CAOS system measurement errors was also investigated. Results The pooled mean unsigned errors generated by the CAOS system were equal or less than 0.61 mm and 0.64° for resection depths and alignment angles, respectively. No clinically meaningful biases were found in the measurements of resection depths (< 0.5 mm) and alignment angles (< 0.5°). Extra-articular deformity did not show significant effect on the measurement errors generated by the CAOS system investigated. Conclusions This study presented a set of methodology and workflow to assess the system-level accuracy and precision of CAOS systems. The data demonstrated that the CAOS system investigated can offer accurate and precise intraoperative measurements of TKA resection parameters, regardless of the presence

  17. Bloch-Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T.

    PubMed

    Whisenant, Jennifer G; Dortch, Richard D; Grissom, William; Kang, Hakmook; Arlinghaus, Lori R; Yankeelov, Thomas E

    2016-12-01

    Variable flip angle (VFA) sequences are a popular method of calculating T1 values, which are required in a quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). B1 inhomogeneities are substantial in the breast at 3 T, and these errors negatively impact the accuracy of the VFA approach, thus leading to large errors in the DCE-MRI parameters that could limit clinical adoption of the technique. This study evaluated the ability of Bloch-Siegert B1 mapping to improve the accuracy and precision of VFA-derived T1 measurements in the breast. Test-retest MRI sessions were performed on 16 women with no history of breast disease. T1 was calculated using the VFA sequence, and B1 field variations were measured using the Bloch-Siegert methodology. As a gold standard, inversion recovery (IR) measurements of T1 were performed. Fibroglandular tissue and adipose tissue from each breast were segmented using the IR images, and the mean T1 was calculated for each tissue. Accuracy was evaluated by percent error (%err). Reproducibility was assessed via the 95% confidence interval (CI) of the mean difference and repeatability coefficient (r). After B1 correction, %err significantly (P < .001) decreased from 17% to 8.6%, and the 95% CI and r decreased from ±94 to ±38 milliseconds and from 276 to 111 milliseconds, respectively. Similar accuracy and reproducibility results were observed in the adipose tissue of the right breast and in both tissues of the left breast. Our data show that Bloch-Siegert B1 mapping improves accuracy and precision of VFA-derived T1 measurements in the breast.

  18. Evaluation of precision and accuracy assessment of different 3-D surface imaging systems for biomedical purposes.

    PubMed

    Eder, Maximilian; Brockmann, Gernot; Zimmermann, Alexander; Papadopoulos, Moschos A; Schwenzer-Zimmerer, Katja; Zeilhofer, Hans Florian; Sader, Robert; Papadopulos, Nikolaos A; Kovacs, Laszlo

    2013-04-01

    Three-dimensional (3-D) surface imaging has gained clinical acceptance, especially in the field of cranio-maxillo-facial and plastic, reconstructive, and aesthetic surgery. Six scanners based on different scanning principles (Minolta Vivid 910®, Polhemus FastSCAN™, GFM PRIMOS®, GFM TopoCAM®, Steinbichler Comet® Vario Zoom 250, 3dMD DSP 400®) were used to measure five sheep skulls of different sizes. In three areas with varying anatomical complexity (areas, 1 = high; 2 = moderate; 3 = low), 56 distances between 20 landmarks are defined on each skull. Manual measurement (MM), coordinate machine measurements (CMM) and computer tomography (CT) measurements were used to define a reference method for further precision and accuracy evaluation of different 3-D scanning systems. MM showed high correlation to CMM and CT measurements (both r = 0.987; p < 0.001) and served as the reference method. TopoCAM®, Comet® and Vivid 910® showed highest measurement precision over all areas of complexity; Vivid 910®, the Comet® and the DSP 400® demonstrated highest accuracy over all areas with Vivid 910® being most accurate in areas 1 and 3, and the DSP 400® most accurate in area 2. In accordance to the measured distance length, most 3-D devices present higher measurement precision and accuracy for large distances and lower degrees of precision and accuracy for short distances. In general, higher degrees of complexity are associated with lower 3-D assessment accuracy, suggesting that for optimal results, different types of scanners should be applied to specific clinical applications and medical problems according to their special construction designs and characteristics.

  19. A Comparative Study of Precise Point Positioning (PPP) Accuracy Using Online Services

    NASA Astrophysics Data System (ADS)

    Malinowski, Marcin; Kwiecień, Janusz

    2016-12-01

    Precise Point Positioning (PPP) is a technique used to determine the position of receiver antenna without communication with the reference station. It may be an alternative solution to differential measurements, where maintaining a connection with a single RTK station or a regional network of reference stations RTN is necessary. This situation is especially common in areas with poorly developed infrastructure of ground stations. A lot of research conducted so far on the use of the PPP technique has been concerned about the development of entire day observation sessions. However, this paper presents the results of a comparative analysis of accuracy of absolute determination of position from observations which last between 1 to 7 hours with the use of four permanent services which execute calculations with PPP technique such as: Automatic Precise Positioning Service (APPS), Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP), GNSS Analysis and Positioning Software (GAPS) and magicPPP - Precise Point Positioning Solution (magicGNSS). On the basis of acquired results of measurements, it can be concluded that at least two-hour long measurements allow acquiring an absolute position with an accuracy of 2-4 cm. An evaluation of the impact on the accuracy of simultaneous positioning of three points test network on the change of the horizontal distance and the relative height difference between measured triangle vertices was also conducted. Distances and relative height differences between points of the triangular test network measured with a laser station Leica TDRA6000 were adopted as references. The analyses of results show that at least two hours long measurement sessions can be used to determine the horizontal distance or the difference in height with an accuracy of 1-2 cm. Rapid products employed in calculations conducted with PPP technique reached the accuracy of determining coordinates on a close level as in elaborations which employ Final products.

  20. A Method for Assessing the Accuracy of a Photogrammetry System for Precision Deployable Structures

    NASA Technical Reports Server (NTRS)

    Moore, Ashley

    2005-01-01

    The measurement techniques used to validate analytical models of large deployable structures are an integral Part of the technology development process and must be precise and accurate. Photogrammetry and videogrammetry are viable, accurate, and unobtrusive methods for measuring such large Structures. Photogrammetry uses Software to determine the three-dimensional position of a target using camera images. Videogrammetry is based on the same principle, except a series of timed images are analyzed. This work addresses the accuracy of a digital photogrammetry system used for measurement of large, deployable space structures at JPL. First, photogrammetry tests are performed on a precision space truss test article, and the images are processed using Photomodeler software. The accuracy of the Photomodeler results is determined through, comparison with measurements of the test article taken by an external testing group using the VSTARS photogrammetry system. These two measurements are then compared with Australis photogrammetry software that simulates a measurement test to predict its accuracy. The software is then used to study how particular factors, such as camera resolution and placement, affect the system accuracy to help design the setup for the videogrammetry system that will offer the highest level of accuracy for measurement of deploying structures.

  1. Impact of improved models for precise orbits of altimetry satellites on the orbit accuracy and regional mean sea level trends

    NASA Astrophysics Data System (ADS)

    Rudenko, Sergei; Esselborn, Saskia; Dettmering, Denise; Schöne, Tilo; Neumayer, Karl-Hans

    2015-04-01

    Precise orbits of altimetry satellites are a prerequisite for investigations of global and regional sea level changes. We show a significant progress obtained in the recent decades in modeling and determination of the orbits of altimetry satellites. This progress was reached due to the improved knowledge of the Earth gravity field obtained by using CHAMP (CHAllenging Mini-Satellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity field and Ocean Circulation Explorer) data, improved realizations of the terrestrial and celestial reference frames and transformations between these reference frames, improved modeling of ocean and solid Earth tides, improved accuracy of observations and other effects. New precise orbits of altimetry satellites ERS-1 (1991-1996), TOPEX/Poseidon (1992-2005), ERS-2 (1995-2006), Envisat (2002-2012) and Jason-1 (2002-2012) have been recently derived at the time intervals given within the DFG UHR-GravDat project and the ESA Climate Change Initiative Sea Level project using satellite laser ranging (SLR), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Precise Range And Range-Rate Equipment (PRARE) and altimetry single-satellite crossover data (various observation types were used for various satellites). We show the current state of the orbit accuracy and the improvements obtained in the recent years. In particular, we demonstrate the impact of recently developed time-variable Earth gravity field models, improved tropospheric refraction models for DORIS observations, latest release 05 of the atmosphere-ocean dealiasing product (AOD1B) and some other models on the orbit accuracy of these altimetry satellites and regional mean sea level trends computed using these new orbit solutions.

  2. The Use of Scale-Dependent Precision to Increase Forecast Accuracy in Earth System Modelling

    NASA Astrophysics Data System (ADS)

    Thornes, Tobias; Duben, Peter; Palmer, Tim

    2016-04-01

    At the current pace of development, it may be decades before the 'exa-scale' computers needed to resolve individual convective clouds in weather and climate models become available to forecasters, and such machines will incur very high power demands. But the resolution could be improved today by switching to more efficient, 'inexact' hardware with which variables can be represented in 'reduced precision'. Currently, all numbers in our models are represented as double-precision floating points - each requiring 64 bits of memory - to minimise rounding errors, regardless of spatial scale. Yet observational and modelling constraints mean that values of atmospheric variables are inevitably known less precisely on smaller scales, suggesting that this may be a waste of computer resources. More accurate forecasts might therefore be obtained by taking a scale-selective approach whereby the precision of variables is gradually decreased at smaller spatial scales to optimise the overall efficiency of the model. To study the effect of reducing precision to different levels on multiple spatial scales, we here introduce a new model atmosphere developed by extending the Lorenz '96 idealised system to encompass three tiers of variables - which represent large-, medium- and small-scale features - for the first time. In this chaotic but computationally tractable system, the 'true' state can be defined by explicitly resolving all three tiers. The abilities of low resolution (single-tier) double-precision models and similar-cost high resolution (two-tier) models in mixed-precision to produce accurate forecasts of this 'truth' are compared. The high resolution models outperform the low resolution ones even when small-scale variables are resolved in half-precision (16 bits). This suggests that using scale-dependent levels of precision in more complicated real-world Earth System models could allow forecasts to be made at higher resolution and with improved accuracy. If adopted, this new

  3. Measuring changes in Plasmodium falciparum transmission: Precision, accuracy and costs of metrics

    PubMed Central

    Tusting, Lucy S.; Bousema, Teun; Smith, David L.; Drakeley, Chris

    2016-01-01

    As malaria declines in parts of Africa and elsewhere, and as more countries move towards elimination, it is necessary to robustly evaluate the effect of interventions and control programmes on malaria transmission. To help guide the appropriate design of trials to evaluate transmission-reducing interventions, we review eleven metrics of malaria transmission, discussing their accuracy, precision, collection methods and costs, and presenting an overall critique. We also review the non-linear scaling relationships between five metrics of malaria transmission; the entomological inoculation rate, force of infection, sporozoite rate, parasite rate and the basic reproductive number, R0. Our review highlights that while the entomological inoculation rate is widely considered the gold standard metric of malaria transmission and may be necessary for measuring changes in transmission in highly endemic areas, it has limited precision and accuracy and more standardised methods for its collection are required. In areas of low transmission, parasite rate, sero-conversion rates and molecular metrics including MOI and mFOI may be most appropriate. When assessing a specific intervention, the most relevant effects will be detected by examining the metrics most directly affected by that intervention. Future work should aim to better quantify the precision and accuracy of malaria metrics and to improve methods for their collection. PMID:24480314

  4. Evaluation of precision and accuracy of selenium measurements in biological materials using neutron activation analysis

    SciTech Connect

    Greenberg, R.R.

    1988-01-01

    In recent years, the accurate determination of selenium in biological materials has become increasingly important in view of the essential nature of this element for human nutrition and its possible role as a protective agent against cancer. Unfortunately, the accurate determination of selenium in biological materials is often difficult for most analytical techniques for a variety of reasons, including interferences, complicated selenium chemistry due to the presence of this element in multiple oxidation states and in a variety of different organic species, stability and resistance to destruction of some of these organo-selenium species during acid dissolution, volatility of some selenium compounds, and potential for contamination. Neutron activation analysis (NAA) can be one of the best analytical techniques for selenium determinations in biological materials for a number of reasons. Currently, precision at the 1% level (1s) and overall accuracy at the 1 to 2% level (95% confidence interval) can be attained at the U.S. National Bureau of Standards (NBS) for selenium determinations in biological materials when counting statistics are not limiting (using the {sup 75}Se isotope). An example of this level of precision and accuracy is summarized. Achieving this level of accuracy, however, requires strict attention to all sources of systematic error. Precise and accurate results can also be obtained after radiochemical separations.

  5. Large format focal plane array integration with precision alignment, metrology and accuracy capabilities

    NASA Astrophysics Data System (ADS)

    Neumann, Jay; Parlato, Russell; Tracy, Gregory; Randolph, Max

    2015-09-01

    Focal plane alignment for large format arrays and faster optical systems require enhanced precision methodology and stability over temperature. The increase in focal plane array size continues to drive the alignment capability. Depending on the optical system, the focal plane flatness of less than 25μm (.001") is required over transition temperatures from ambient to cooled operating temperatures. The focal plane flatness requirement must also be maintained in airborne or launch vibration environments. This paper addresses the challenge of the detector integration into the focal plane module and housing assemblies, the methodology to reduce error terms during integration and the evaluation of thermal effects. The driving factors influencing the alignment accuracy include: datum transfers, material effects over temperature, alignment stability over test, adjustment precision and traceability to NIST standard. The FPA module design and alignment methodology reduces the error terms by minimizing the measurement transfers to the housing. In the design, the proper material selection requires matched coefficient of expansion materials minimizes both the physical shift over temperature as well as lowering the stress induced into the detector. When required, the co-registration of focal planes and filters can achieve submicron relative positioning by applying precision equipment, interferometry and piezoelectric positioning stages. All measurements and characterizations maintain traceability to NIST standards. The metrology characterizes the equipment's accuracy, repeatability and precision of the measurements.

  6. Accuracy, precision, usability, and cost of portable silver test methods for ceramic filter factories.

    PubMed

    Meade, Rhiana D; Murray, Anna L; Mittelman, Anjuliee M; Rayner, Justine; Lantagne, Daniele S

    2017-02-01

    Locally manufactured ceramic water filters are one effective household drinking water treatment technology. During manufacturing, silver nanoparticles or silver nitrate are applied to prevent microbiological growth within the filter and increase bacterial removal efficacy. Currently, there is no recommendation for manufacturers to test silver concentrations of application solutions or filtered water. We identified six commercially available silver test strips, kits, and meters, and evaluated them by: (1) measuring in quintuplicate six samples from 100 to 1,000 mg/L (application range) and six samples from 0.0 to 1.0 mg/L (effluent range) of silver nanoparticles and silver nitrate to determine accuracy and precision; (2) conducting volunteer testing to assess ease-of-use; and (3) comparing costs. We found no method accurately detected silver nanoparticles, and accuracy ranged from 4 to 91% measurement error for silver nitrate samples. Most methods were precise, but only one method could test both application and effluent concentration ranges of silver nitrate. Volunteers considered test strip methods easiest. The cost for 100 tests ranged from 36 to 1,600 USD. We found no currently available method accurately and precisely measured both silver types at reasonable cost and ease-of-use, thus these methods are not recommended to manufacturers. We recommend development of field-appropriate methods that accurately and precisely measure silver nanoparticle and silver nitrate concentrations.

  7. Theoretical study of precision and accuracy of strain analysis by nano-beam electron diffraction.

    PubMed

    Mahr, Christoph; Müller-Caspary, Knut; Grieb, Tim; Schowalter, Marco; Mehrtens, Thorsten; Krause, Florian F; Zillmann, Dennis; Rosenauer, Andreas

    2015-11-01

    Measurement of lattice strain is important to characterize semiconductor nanostructures. As strain has large influence on the electronic band structure, methods for the measurement of strain with high precision, accuracy and spatial resolution in a large field of view are mandatory. In this paper we present a theoretical study of precision and accuracy of measurement of strain by convergent nano-beam electron diffraction. It is found that the accuracy of the evaluation suffers from halos in the diffraction pattern caused by a variation of strain within the area covered by the focussed electron beam. This effect, which is expected to be strong at sharp interfaces between materials with different lattice plane distances, will be discussed for convergent-beam electron diffraction patterns using a conventional probe and for patterns formed by a precessing electron beam. Furthermore, we discuss approaches to optimize the accuracy of strain measured at interfaces. The study is based on the evaluation of diffraction patterns simulated for different realistic structures that have been investigated experimentally in former publications. These simulations account for thermal diffuse scattering using the frozen-lattice approach and the modulation-transfer function of the image-recording system. The influence of Poisson noise is also investigated.

  8. Accelerator mass spectrometry best practices for accuracy and precision in bioanalytical (14)C measurements.

    PubMed

    Vogel, John S; Giacomo, Jason A; Schulze-König, Tim; Keck, Bradly D; Lohstroh, Peter; Dueker, Stephen

    2010-03-01

    Accelerator mass spectrometers have an energy acceleration and charge exchange between mass definition stages to destroy molecular isobars and allow single ion counting of long-lived isotopes such as (14)C (t½=5370 years.). 'Low' voltage accelerations to 200 kV allow laboratory-sized accelerator mass spectrometers instruments for bioanalytical quantitation of (14)C to 2-3% precision and accuracy in isolated biochemical fractions. After demonstrating this accuracy and precision for our new accelerator mass spectrometer, we discuss the critical aspects of maintaining quantitative accuracy from the defined biological fraction to the accelerator mass spectrometry quantitation. These aspects include sufficient sample mass for routine rapid sample preparation, isotope dilution to assure this mass, isolation of the carbon from other sample combustion gasses and use of high-efficiency biochemical separations. This review seeks to address a bioanalytical audience, who should know that high accuracy data of physiochemical processes within living human subjects are available, as long as a (14)C quantitation can be made indicative of the physiochemistry of interest.

  9. Accuracy, Precision, and Reproducibility of Four T1 Mapping Sequences: A Head-to-Head Comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE

    PubMed Central

    Roujol, Sébastien; Weingärtner, Sebastian; Foppa, Murilo; Chow, Kelvin; Kawaji, Keigo; Ngo, Long H.; Kellman, Peter; Manning, Warren J.; Thompson, Richard B.

    2014-01-01

    Purpose To compare accuracy, precision, and reproducibility of four commonly used myocardial T1 mapping sequences: modified Look-Locker inversion recovery (MOLLI), shortened MOLLI (ShMOLLI), saturation recovery single-shot acquisition (SASHA), and saturation pulse prepared heart rate independent inversion recovery (SAPPHIRE). Materials and Methods This HIPAA-compliant study was approved by the institutional review board. All subjects provided written informed consent. Accuracy, precision, and reproducibility of the four T1 mapping sequences were first compared in phantom experiments. In vivo analysis was performed in seven healthy subjects (mean age ± standard deviation, 38 years ± 19; four men, three women) who were imaged twice on two separate days. In vivo reproducibility of native T1 mapping and extracellular volume (ECV) were measured. Differences between the sequences were assessed by using Kruskal-Wallis and Wilcoxon rank sum tests (phantom data) and mixed-effect models (in vivo data). Results T1 mapping accuracy in phantoms was lower with ShMOLLI (62 msec) and MOLLI (44 msec) than with SASHA (13 msec; P < .05) and SAPPHIRE (12 msec; P < .05). MOLLI had similar precision to ShMOLLI (4.0 msec vs 5.6 msec; P = .07) but higher precision than SAPPHIRE (6.8 msec; P = .002) and SASHA (8.7 msec; P < .001). All sequences had similar reproducibility in phantoms (P = .1). The four sequences had similar in vivo reproducibility for native T1 mapping (∼25–50 msec; P > .05) and ECV quantification (∼0.01–0.02; P > .05). Conclusion SASHA and SAPPHIRE yield higher accuracy, lower precision, and similar reproducibility compared with MOLLI and ShMOLLI for T1 measurement. Different sequences yield different ECV values; however, all sequences have similar reproducibility for ECV quantification. © RSNA, 2014 Online supplemental material is available for this article. PMID:24702727

  10. Accuracy or precision: Implications of sample design and methodology on abundance estimation

    USGS Publications Warehouse

    Kowalewski, Lucas K.; Chizinski, Christopher J.; Powell, Larkin A.; Pope, Kevin L.; Pegg, Mark A.

    2015-01-01

    Sampling by spatially replicated counts (point-count) is an increasingly popular method of estimating population size of organisms. Challenges exist when sampling by point-count method, and it is often impractical to sample entire area of interest and impossible to detect every individual present. Ecologists encounter logistical limitations that force them to sample either few large-sample units or many small sample-units, introducing biases to sample counts. We generated a computer environment and simulated sampling scenarios to test the role of number of samples, sample unit area, number of organisms, and distribution of organisms in the estimation of population sizes using N-mixture models. Many sample units of small area provided estimates that were consistently closer to true abundance than sample scenarios with few sample units of large area. However, sample scenarios with few sample units of large area provided more precise abundance estimates than abundance estimates derived from sample scenarios with many sample units of small area. It is important to consider accuracy and precision of abundance estimates during the sample design process with study goals and objectives fully recognized, although and with consequence, consideration of accuracy and precision of abundance estimates is often an afterthought that occurs during the data analysis process.

  11. Recovery of SINIS turnstile accuracy in a strongly nonequilibrium regime

    NASA Astrophysics Data System (ADS)

    Khaymovich, I. M.; Basko, D. M.

    2016-10-01

    We perform a theoretical study of nonequilibrium effects in charge transport through a hybrid single-electron transistor based on a small normal metal (N) island with the gate-controlled number of electrons, tunnel-coupled to voltage-biased superconducting (S) electrodes (SINIS). Focusing on the turnstile mode of the transistor operation with the gate voltage driven periodically, and electrons on the island being out of equilibrium, we find that the current quantization accuracy is a nonmonotonic function of the relaxation rate ΓF of the distribution function F (ɛ ) on the island due to tunneling, as compared to the drive frequency f , electron-electron 1 /τe e , and electron-phonon 1 /τe p h relaxation rates. Surprisingly, in the strongly nonequilibrium regime, f ≫ΓF≫τee -1,τep h -1 , the turnstile current plateau is recovered, similarly to the ideal equilibrium regime, τep h -1≫ΓF . The plateau is destroyed in the quasiequilibrium regime when the electron-electron relaxation is faster than tunneling.

  12. Assessing accuracy and precision for field and laboratory data: a perspective in ecosystem restoration

    USGS Publications Warehouse

    Stapanian, Martin A.; Lewis, Timothy E; Palmer, Craig J.; Middlebrook Amos, Molly

    2016-01-01

    Unlike most laboratory studies, rigorous quality assurance/quality control (QA/QC) procedures may be lacking in ecosystem restoration (“ecorestoration”) projects, despite legislative mandates in the United States. This is due, in part, to ecorestoration specialists making the false assumption that some types of data (e.g. discrete variables such as species identification and abundance classes) are not subject to evaluations of data quality. Moreover, emergent behavior manifested by complex, adapting, and nonlinear organizations responsible for monitoring the success of ecorestoration projects tend to unconsciously minimize disorder, QA/QC being an activity perceived as creating disorder. We discuss similarities and differences in assessing precision and accuracy for field and laboratory data. Although the concepts for assessing precision and accuracy of ecorestoration field data are conceptually the same as laboratory data, the manner in which these data quality attributes are assessed is different. From a sample analysis perspective, a field crew is comparable to a laboratory instrument that requires regular “recalibration,” with results obtained by experts at the same plot treated as laboratory calibration standards. Unlike laboratory standards and reference materials, the “true” value for many field variables is commonly unknown. In the laboratory, specific QA/QC samples assess error for each aspect of the measurement process, whereas field revisits assess precision and accuracy of the entire data collection process following initial calibration. Rigorous QA/QC data in an ecorestoration project are essential for evaluating the success of a project, and they provide the only objective “legacy” of the dataset for potential legal challenges and future uses.

  13. Mapping stream habitats with a global positioning system: Accuracy, precision, and comparison with traditional methods

    USGS Publications Warehouse

    Dauwalter, D.C.; Fisher, W.L.; Belt, K.C.

    2006-01-01

    We tested the precision and accuracy of the Trimble GeoXT??? global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement. ?? 2006 Springer Science+Business Media

  14. Radiographic total disc replacement angle measurement accuracy using the Oxford Cobbometer: precision and bias

    PubMed Central

    Stafylas, Kosmas; McManus, John; Schizas, Constantin

    2008-01-01

    Total disc replacement (TDR) clinical success has been reported to be related to the residual motion of the operated level. Thus, accurate measurement of TDR range of motion (ROM) is of utmost importance. One commonly used tool in measuring ROM is the Oxford Cobbometer. Little is known however on its accuracy (precision and bias) in measuring TDR angles. The aim of this study was to assess the ability of the Cobbometer to accurately measure radiographic TDR angles. An anatomically accurate synthetic L4–L5 motion segment was instrumented with a CHARITE artificial disc. The TDR angle and anatomical position between L4 and L5 was fixed to prohibit motion while the motion segment was radiographically imaged in various degrees of rotation and elevation, representing a sample of possible patient placement positions. An experienced observer made ten readings of the TDR angle using the Cobbometer at each different position. The Cobbometer readings were analyzed to determine measurement accuracy at each position. Furthermore, analysis of variance was used to study rotation and elevation of the motion segment as treatment factors. Cobbometer TDR angle measurements were most accurate (highest precision and lowest bias) at the centered position (95.5%), which placed the TDR directly inline with the x-ray beam source without any rotation. In contrast, the lowest accuracy (75.2%) was observed in the most rotated and off-centered view. A difference as high as 4° between readings at any individual position, and as high as 6° between all the positions was observed. Furthermore, the Cobbometer was unable to detect the expected trend in TDR angle projection with changing position. Although the Cobbometer has been reported to be reliable in different clinical applications, it lacks the needed accuracy to measure TDR angles and ROM. More accurate ROM measurement methods need to be developed to help surgeons and researchers assess radiological success of TDRs. PMID:18496719

  15. 40 CFR Appendix D to Part 136 - Precision and Recovery Statements for Methods for Measuring Metals

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Methods for Measuring Metals D Appendix D to Part 136 Protection of Environment ENVIRONMENTAL PROTECTION... Metals Twenty-eight selected methods from “Methods for Chemical Analysis of Water and Wastes,” EPA-600/4... Accuracy Section with the following: Precision and Accuracy An interlaboratory study on metal analyses...

  16. 40 CFR Appendix D to Part 136 - Precision and Recovery Statements for Methods for Measuring Metals

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Methods for Measuring Metals D Appendix D to Part 136 Protection of Environment ENVIRONMENTAL PROTECTION... Metals Twenty-eight selected methods from “Methods for Chemical Analysis of Water and Wastes,” EPA-600/4... Accuracy Section with the following: Precision and Accuracy An interlaboratory study on metal analyses...

  17. Integrated multi-ISE arrays with improved sensitivity, accuracy and precision

    PubMed Central

    Wang, Chunling; Yuan, Hongyan; Duan, Zhijuan; Xiao, Dan

    2017-01-01

    Increasing use of ion-selective electrodes (ISEs) in the biological and environmental fields has generated demand for high-sensitivity ISEs. However, improving the sensitivities of ISEs remains a challenge because of the limit of the Nernstian slope (59.2/n mV). Here, we present a universal ion detection method using an electronic integrated multi-electrode system (EIMES) that bypasses the Nernstian slope limit of 59.2/n mV, thereby enabling substantial enhancement of the sensitivity of ISEs. The results reveal that the response slope is greatly increased from 57.2 to 1711.3 mV, 57.3 to 564.7 mV and 57.7 to 576.2 mV by electronic integrated 30 Cl− electrodes, 10 F− electrodes and 10 glass pH electrodes, respectively. Thus, a tiny change in the ion concentration can be monitored, and correspondingly, the accuracy and precision are substantially improved. The EIMES is suited for all types of potentiometric sensors and may pave the way for monitoring of various ions with high accuracy and precision because of its high sensitivity. PMID:28303939

  18. Accuracy and Precision in Measurements of Biomass Oxidative Ratio and Carbon Oxidation State

    NASA Astrophysics Data System (ADS)

    Gallagher, M. E.; Masiello, C. A.; Randerson, J. T.; Chadwick, O. A.; Robertson, G. P.

    2007-12-01

    Ecosystem oxidative ratio (OR) is a critical parameter in the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean carbon reservoirs. OR is the ratio of O2 to CO2 in gas exchange fluxes between the terrestrial biosphere and atmosphere. Ecosystem OR is linearly related to biomass carbon oxidation state (Cox), a fundamental property of the earth system describing the bonding environment of carbon in molecules. Cox can range from -4 to +4 (CH4 to CO2). Variations in both Cox and OR are driven by photosynthesis, respiration, and decomposition. We are developing several techniques to accurately measure variations in ecosystem Cox and OR; these include elemental analysis, bomb calorimetry, and 13C nuclear magnetic resonance spectroscopy. A previous study, comparing the accuracy and precision of elemental analysis versus bomb calorimetry for pure chemicals, showed that elemental analysis-based measurements are more accurate, while calorimetry- based measurements yield more precise data. However, the limited biochemical range of natural samples makes it possible that calorimetry may ultimately prove most accurate, as well as most cost-effective. Here we examine more closely the accuracy of Cox and OR values generated by calorimetry on a large set of natural biomass samples collected from the Kellogg Biological Station-Long Term Ecological Research (KBS-LTER) site in Michigan.

  19. Integrated multi-ISE arrays with improved sensitivity, accuracy and precision

    NASA Astrophysics Data System (ADS)

    Wang, Chunling; Yuan, Hongyan; Duan, Zhijuan; Xiao, Dan

    2017-03-01

    Increasing use of ion-selective electrodes (ISEs) in the biological and environmental fields has generated demand for high-sensitivity ISEs. However, improving the sensitivities of ISEs remains a challenge because of the limit of the Nernstian slope (59.2/n mV). Here, we present a universal ion detection method using an electronic integrated multi-electrode system (EIMES) that bypasses the Nernstian slope limit of 59.2/n mV, thereby enabling substantial enhancement of the sensitivity of ISEs. The results reveal that the response slope is greatly increased from 57.2 to 1711.3 mV, 57.3 to 564.7 mV and 57.7 to 576.2 mV by electronic integrated 30 Cl‑ electrodes, 10 F‑ electrodes and 10 glass pH electrodes, respectively. Thus, a tiny change in the ion concentration can be monitored, and correspondingly, the accuracy and precision are substantially improved. The EIMES is suited for all types of potentiometric sensors and may pave the way for monitoring of various ions with high accuracy and precision because of its high sensitivity.

  20. Integrated multi-ISE arrays with improved sensitivity, accuracy and precision.

    PubMed

    Wang, Chunling; Yuan, Hongyan; Duan, Zhijuan; Xiao, Dan

    2017-03-17

    Increasing use of ion-selective electrodes (ISEs) in the biological and environmental fields has generated demand for high-sensitivity ISEs. However, improving the sensitivities of ISEs remains a challenge because of the limit of the Nernstian slope (59.2/n mV). Here, we present a universal ion detection method using an electronic integrated multi-electrode system (EIMES) that bypasses the Nernstian slope limit of 59.2/n mV, thereby enabling substantial enhancement of the sensitivity of ISEs. The results reveal that the response slope is greatly increased from 57.2 to 1711.3 mV, 57.3 to 564.7 mV and 57.7 to 576.2 mV by electronic integrated 30 Cl(-) electrodes, 10 F(-) electrodes and 10 glass pH electrodes, respectively. Thus, a tiny change in the ion concentration can be monitored, and correspondingly, the accuracy and precision are substantially improved. The EIMES is suited for all types of potentiometric sensors and may pave the way for monitoring of various ions with high accuracy and precision because of its high sensitivity.

  1. To address accuracy and precision using methods from analytical chemistry and computational physics.

    PubMed

    Kozmutza, Cornelia; Picó, Yolanda

    2009-04-01

    In this work the pesticides were determined by liquid chromatography-mass spectrometry (LC-MS). In present study the occurrence of imidacloprid in 343 samples of oranges, tangerines, date plum, and watermelons from Valencian Community (Spain) has been investigated. The nine additional pesticides were chosen as they have been recommended for orchard treatment together with imidacloprid. The Mulliken population analysis has been applied to present the charge distribution in imidacloprid. Partitioned energy terms and the virial ratios have been calculated for certain molecules entering in interaction. A new technique based on the comparison of the decomposed total energy terms at various configurations is demonstrated in this work. The interaction ability could be established correctly in the studied case. An attempt is also made in this work to address accuracy and precision. These quantities are well-known in experimental measurements. In case precise theoretical description is achieved for the contributing monomers and also for the interacting complex structure some properties of this latter system can be predicted to quite a good accuracy. Based on simple hypothetical considerations we estimate the impact of applying computations on reducing the amount of analytical work.

  2. Automated tracking of colloidal clusters with sub-pixel accuracy and precision

    NASA Astrophysics Data System (ADS)

    van der Wel, Casper; Kraft, Daniela J.

    2017-02-01

    Quantitative tracking of features from video images is a basic technique employed in many areas of science. Here, we present a method for the tracking of features that partially overlap, in order to be able to track so-called colloidal molecules. Our approach implements two improvements into existing particle tracking algorithms. Firstly, we use the history of previously identified feature locations to successfully find their positions in consecutive frames. Secondly, we present a framework for non-linear least-squares fitting to summed radial model functions and analyze the accuracy (bias) and precision (random error) of the method on artificial data. We find that our tracking algorithm correctly identifies overlapping features with an accuracy below 0.2% of the feature radius and a precision of 0.1 to 0.01 pixels for a typical image of a colloidal cluster. Finally, we use our method to extract the three-dimensional diffusion tensor from the Brownian motion of colloidal dimers. , which features invited work from the best early-career researchers working within the scope of Journal of Physics: Condensed Matter. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Daniela Kraft was selected by the Editorial Board of Journal of Physics: Condensed Matter as an Emerging Leader.

  3. Estimates of laboratory accuracy and precision on Hanford waste tank samples

    SciTech Connect

    Dodd, D.A.

    1995-02-02

    A review was performed on three sets of analyses generated in Battelle, Pacific Northwest Laboratories and three sets generated by Westinghouse Hanford Company, 222-S Analytical Laboratory. Laboratory accuracy and precision was estimated by analyte and is reported in tables. The sources used to generate this estimate is of limited size but does include the physical forms, liquid and solid, which are representative of samples from tanks to be characterized. This estimate was published as an aid to programs developing data quality objectives in which specified limits are established. Data resulting from routine analyses of waste matrices can be expected to be bounded by the precision and accuracy estimates of the tables. These tables do not preclude or discourage direct negotiations between program and laboratory personnel while establishing bounding conditions. Programmatic requirements different than those listed may be reliably met on specific measurements and matrices. It should be recognized, however, that these are specific to waste tank matrices and may not be indicative of performance on samples from other sources.

  4. Training to Improve Precision and Accuracy in the Measurement of Fiber Morphology

    PubMed Central

    Jeon, Jun; Wade, Mary Beth; Luong, Derek; Palmer, Xavier-Lewis; Bharti, Kapil; Simon, Carl G.

    2016-01-01

    An estimated $7.1 billion dollars a year is spent due to irreproducibility in pre-clinical data from errors in data analysis and reporting. Therefore, developing tools to improve measurement comparability is paramount. Recently, an open source tool, DiameterJ, has been deployed for the automated analysis of scanning electron micrographs of fibrous scaffolds designed for tissue engineering applications. DiameterJ performs hundreds to thousands of scaffold fiber diameter measurements from a single micrograph within a few seconds, along with a variety of other scaffold morphological features, which enables a more rigorous and thorough assessment of scaffold properties. Herein, an online, publicly available training module is introduced for educating DiameterJ users on how to effectively analyze scanning electron micrographs of fibers and the large volume of data that a DiameterJ analysis yields. The end goal of this training was to improve user data analysis and reporting to enhance reproducibility of analysis of nanofiber scaffolds. User performance was assessed before and after training to evaluate the effectiveness of the training modules. Users were asked to use DiameterJ to analyze reference micrographs of fibers that had known diameters. The results showed that training improved the accuracy and precision of measurements of fiber diameter in scanning electron micrographs. Training also improved the precision of measurements of pore area, porosity, intersection density, and characteristic fiber length between fiber intersections. These results demonstrate that the DiameterJ training module improves precision and accuracy in fiber morphology measurements, which will lead to enhanced data comparability. PMID:27907145

  5. Freehand liver volumetry by using an electromagnetic pen tablet: accuracy, precision, and rapidity.

    PubMed

    Perandini, Simone; Faccioli, Niccolò; Inama, Marco; Pozzi Mucelli, Roberto

    2011-04-01

    The purpose of this study is to assess the accuracy, precision, and rapidity of liver volumes calculated by using a freehand electromagnetic pen tablet contourtracing method as compared with the volumes calculated by using the standard optical mouse contourtracing method. The imaging data used as input for accuracy and precision testing were computed by software developed in our institution. This computer software can generate models of solid organs and allows both standard mouse-based and electromagnetic pen-driven segmentation (number of data sets, n = 70). The images used as input for rapidity testing was partly computed by modeling software (n = 70) and partly selected from contrast-enhanced computed tomography (CT) examinations (n = 12). Mean volumes and time required to perform the segmentation, along with standard deviation and range values with both techniques, were calculated. Student's t test was used to assess significance regarding mean volumes and time calculated by using both segmentation techniques on phantom and CT data sets. P value was also calculated. The mean volume difference was significantly lower with the use of the freehand electromagnetic pen as compared with the optical mouse (0.2% vs. 1.8%; P < .001). The mean segmentation time per patient was significantly shorter with the use of the freehand electromagnetic pen contourtracing method (354.5 vs. 499.1 s on phantoms; 457.4 vs. 610.0 s on CT images; P < .001). Freehand electromagnetic pen-based volumetric technique represents a technologic advancement over manual mouse-based contourtracing because of the superior statistical accuracy and sensibly shorter time required. Further studies focused on intra- and interobserver variability of the technique need to be performed before its introduction in clinical application.

  6. Keystroke dynamics and timing: accuracy, precision and difference between hands in pianist's performance.

    PubMed

    Minetti, Alberto E; Ardigò, Luca P; McKee, Tom

    2007-01-01

    A commercially available acoustic grand piano, originally provided with keystroke speed sensors, is proposed as a standard instrument to quantitatively assess the technical side of pianist's performance, after the mechanical characteristics of the keyboard have been measured. We found a positional dependence of the relationship between the applied force and the resulting downstroke speed (i.e. treble keys descend fastest) due to the different hammer/hammer shaft mass to be accelerated. When this effect was removed by a custom software, the ability of 14 pianists was analysed in terms of variability in stroke intervals and keystroke speeds. C-major scales played by separate hands at different imposed tempos and at 5 subjectively chosen graded force levels were analysed to get insights into the achieved neuromuscular control. Accuracy and precision of time intervals and descent velocity of keystrokes were obtained by processing the generated MIDI files. The results quantitatively show: the difference between hands, the trade off between force range and tempo, and between time interval precision and tempo, the lower precision of descent speed associated to 'soft' playing, etc. Those results reflect well-established physiological and motor control characteristics of our movement system. Apart from revealing fundamental aspects of pianism, the proposed method could be used as a standard tool also for ergonomic (e.g. the mechanical work and power of playing), didactic and rehabilitation monitoring of pianists.

  7. Improvement in precision, accuracy, and efficiency in sstandardizing the characterization of granular materials

    SciTech Connect

    Tucker, Jonathan R.; Shadle, Lawrence J.; Benyahia, Sofiane; Mei, Joseph; Guenther, Chris; Koepke, M. E.

    2013-01-01

    Useful prediction of the kinematics, dynamics, and chemistry of a system relies on precision and accuracy in the quantification of component properties, operating mechanisms, and collected data. In an attempt to emphasize, rather than gloss over, the benefit of proper characterization to fundamental investigations of multiphase systems incorporating solid particles, a set of procedures were developed and implemented for the purpose of providing a revised methodology having the desirable attributes of reduced uncertainty, expanded relevance and detail, and higher throughput. Better, faster, cheaper characterization of multiphase systems result. Methodologies are presented to characterize particle size, shape, size distribution, density (particle, skeletal and bulk), minimum fluidization velocity, void fraction, particle porosity, and assignment within the Geldart Classification. A novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Accuracy of properties-characterization methodology was validated on materials of known properties prior to testing materials of unknown properties. Several of the standard present-day techniques were scrutinized and improved upon where appropriate. Validity, accuracy, and repeatability were assessed for the procedures presented and deemed higher than present-day techniques. A database of over seventy materials has been developed to assist in model validation efforts and future desig

  8. Slight pressure imbalances can affect accuracy and precision of dual inlet-based clumped isotope analysis.

    PubMed

    Fiebig, Jens; Hofmann, Sven; Löffler, Niklas; Lüdecke, Tina; Methner, Katharina; Wacker, Ulrike

    2016-01-01

    It is well known that a subtle nonlinearity can occur during clumped isotope analysis of CO2 that - if remaining unaddressed - limits accuracy. The nonlinearity is induced by a negative background on the m/z 47 ion Faraday cup, whose magnitude is correlated with the intensity of the m/z 44 ion beam. The origin of the negative background remains unclear, but is possibly due to secondary electrons. Usually, CO2 gases of distinct bulk isotopic compositions are equilibrated at 1000 °C and measured along with the samples in order to be able to correct for this effect. Alternatively, measured m/z 47 beam intensities can be corrected for the contribution of secondary electrons after monitoring how the negative background on m/z 47 evolves with the intensity of the m/z 44 ion beam. The latter correction procedure seems to work well if the m/z 44 cup exhibits a wider slit width than the m/z 47 cup. Here we show that the negative m/z 47 background affects precision of dual inlet-based clumped isotope measurements of CO2 unless raw m/z 47 intensities are directly corrected for the contribution of secondary electrons. Moreover, inaccurate results can be obtained even if the heated gas approach is used to correct for the observed nonlinearity. The impact of the negative background on accuracy and precision arises from small imbalances in m/z 44 ion beam intensities between reference and sample CO2 measurements. It becomes the more significant the larger the relative contribution of secondary electrons to the m/z 47 signal is and the higher the flux rate of CO2 into the ion source is set. These problems can be overcome by correcting the measured m/z 47 ion beam intensities of sample and reference gas for the contributions deriving from secondary electrons after scaling these contributions to the intensities of the corresponding m/z 49 ion beams. Accuracy and precision of this correction are demonstrated by clumped isotope analysis of three internal carbonate standards. The

  9. Precision and accuracy testing of FMCW ladar-based length metrology.

    PubMed

    Mateo, Ana Baselga; Barber, Zeb W

    2015-07-01

    The calibration and traceability of high-resolution frequency modulated continuous wave (FMCW) ladar sources is a requirement for their use in length and volume metrology. We report the calibration of FMCW ladar length measurement systems by use of spectroscopy of molecular frequency references HCN (C-band) or CO (L-band) to calibrate the chirp rate of the FMCW sources. Propagating the stated uncertainties from the molecular calibrations provided by NIST and measurement errors provide an estimated uncertainty of a few ppm for the FMCW system. As a test of this calibration, a displacement measurement interferometer with a laser wavelength close to that of our FMCW system was built to make comparisons of the relative precision and accuracy. The comparisons performed show <10  ppm agreement, which was within the combined estimated uncertainties of the FMCW system and interferometer.

  10. Improved precision and accuracy in quantifying plutonium isotope ratios by RIMS

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Kucher, A.; Gates, S. D.; Knight, K. B.; Hutcheon, I. D.

    2015-09-01

    Resonance ionization mass spectrometry (RIMS) holds the promise of rapid, isobar-free quantification of actinide isotope ratios in as-received materials (i.e. not chemically purified). Recent progress in achieving this potential using two Pu test materials is presented. RIMS measurements were conducted multiple times over a period of two months on two different Pu solutions deposited on metal surfaces. Measurements were bracketed with a Pu isotopic standard, and yielded absolute accuracies of the measured 240Pu/239Pu ratios of 0.7% and 0.58%, with precisions (95% confidence intervals) of 1.49% and 0.91%. In conclusion, the minor isotope 238Pu was also quantified despite the presence of a significant quantity of 238U in the samples.

  11. Estimated results analysis and application of the precise point positioning based high-accuracy ionosphere delay

    NASA Astrophysics Data System (ADS)

    Wang, Shi-tai; Peng, Jun-huan

    2015-12-01

    The characterization of ionosphere delay estimated with precise point positioning is analyzed in this paper. The estimation, interpolation and application of the ionosphere delay are studied based on the processing of 24-h data from 5 observation stations. The results show that the estimated ionosphere delay is affected by the hardware delay bias from receiver so that there is a difference between the estimated and interpolated results. The results also show that the RMSs (root mean squares) are bigger, while the STDs (standard deviations) are better than 0.11 m. When the satellite difference is used, the hardware delay bias can be canceled. The interpolated satellite-differenced ionosphere delay is better than 0.11 m. Although there is a difference between the between the estimated and interpolated ionosphere delay results it cannot affect its application in single-frequency positioning and the positioning accuracy can reach cm level.

  12. Improved precision and accuracy in quantifying plutonium isotope ratios by RIMS

    DOE PAGES

    Isselhardt, B. H.; Savina, M. R.; Kucher, A.; ...

    2015-09-01

    Resonance ionization mass spectrometry (RIMS) holds the promise of rapid, isobar-free quantification of actinide isotope ratios in as-received materials (i.e. not chemically purified). Recent progress in achieving this potential using two Pu test materials is presented. RIMS measurements were conducted multiple times over a period of two months on two different Pu solutions deposited on metal surfaces. Measurements were bracketed with a Pu isotopic standard, and yielded absolute accuracies of the measured 240Pu/239Pu ratios of 0.7% and 0.58%, with precisions (95% confidence intervals) of 1.49% and 0.91%. In conclusion, the minor isotope 238Pu was also quantified despite the presence ofmore » a significant quantity of 238U in the samples.« less

  13. Accuracy and precision of estimating age of gray wolves by tooth wear

    USGS Publications Warehouse

    Gipson, P.S.; Ballard, W.B.; Nowak, R.M.; Mech, L.D.

    2000-01-01

    We evaluated the accuracy and precision of tooth wear for aging gray wolves (Canis lupus) from Alaska, Minnesota, and Ontario based on 47 known-age or known-minimum-age skulls. Estimates of age using tooth wear and a commercial cementum annuli-aging service were useful for wolves up to 14 years old. The precision of estimates from cementum annuli was greater than estimates from tooth wear, but tooth wear estimates are more applicable in the field. We tended to overestimate age by 1-2 years and occasionally by 3 or 4 years. The commercial service aged young wolves with cementum annuli to within ?? 1 year of actual age, but under estimated ages of wolves ???9 years old by 1-3 years. No differences were detected in tooth wear patterns for wild wolves from Alaska, Minnesota, and Ontario, nor between captive and wild wolves. Tooth wear was not appropriate for aging wolves with an underbite that prevented normal wear or severely broken and missing teeth.

  14. A benchmark test of accuracy and precision in estimating dynamical systems characteristics from a time series.

    PubMed

    Rispens, S M; Pijnappels, M; van Dieën, J H; van Schooten, K S; Beek, P J; Daffertshofer, A

    2014-01-22

    Characteristics of dynamical systems are often estimated to describe physiological processes. For instance, Lyapunov exponents have been determined to assess the stability of the cardio-vascular system, respiration, and, more recently, human gait and posture. However, the systematic evaluation of the accuracy and precision of these estimates is problematic because the proper values of the characteristics are typically unknown. We fill this void with a set of standardized time series with well-defined dynamical characteristics that serve as a benchmark. Estimates ought to match these characteristics, at least to good approximation. We outline a procedure to employ this generic benchmark test and illustrate its capacity by examining methods for estimating the maximum Lyapunov exponent. In particular, we discuss algorithms by Wolf and co-workers and by Rosenstein and co-workers and evaluate their performances as a function of signal length and signal-to-noise ratio. In all scenarios, the precision of Rosenstein's algorithm was found to be equal to or greater than Wolf's algorithm. The latter, however, appeared more accurate if reasonably large signal lengths are available and noise levels are sufficiently low. Due to its modularity, the presented benchmark test can be used to evaluate and tune any estimation method to perform optimally for arbitrary experimental data.

  15. Increasing accuracy and precision of digital image correlation through pattern optimization

    NASA Astrophysics Data System (ADS)

    Bomarito, G. F.; Hochhalter, J. D.; Ruggles, T. J.; Cannon, A. H.

    2017-04-01

    The accuracy and precision of digital image correlation (DIC) is based on three primary components: image acquisition, image analysis, and the subject of the image. Focus on the third component, the image subject, has been relatively limited and primarily concerned with comparing pseudo-random surface patterns. In the current work, a strategy is proposed for the creation of optimal DIC patterns. In this strategy, a pattern quality metric is developed as a combination of quality metrics from the literature rather than optimization based on any single one of them. In this way, optimization produces a pattern which balances the benefits of multiple quality metrics. Specifically, sum of square of subset intensity gradients (SSSIG) was found to be the metric most strongly correlated to DIC accuracy and thus is the main component of the newly proposed pattern quality metric. A term related to the secondary auto-correlation peak height is also part of the proposed quality metric which effectively acts as a constraint upon SSSIG ensuring that a regular (e.g., checkerboard-type) pattern is not achieved. The combined pattern quality metric is used to generate a pattern that was on average 11.6% more accurate than a randomly generated pattern in a suite of numerical experiments. Furthermore, physical experiments were performed which confirm that there is indeed improvement of a similar magnitude in DIC measurements for the optimized pattern compared to a random pattern.

  16. Gaining Precision and Accuracy on Microprobe Trace Element Analysis with the Multipoint Background Method

    NASA Astrophysics Data System (ADS)

    Allaz, J. M.; Williams, M. L.; Jercinovic, M. J.; Donovan, J. J.

    2014-12-01

    Electron microprobe trace element analysis is a significant challenge, but can provide critical data when high spatial resolution is required. Due to the low peak intensity, the accuracy and precision of such analyses relies critically on background measurements, and on the accuracy of any pertinent peak interference corrections. A linear regression between two points selected at appropriate off-peak positions is a classical approach for background characterization in microprobe analysis. However, this approach disallows an accurate assessment of background curvature (usually exponential). Moreover, if present, background interferences can dramatically affect the results if underestimated or ignored. The acquisition of a quantitative WDS scan over the spectral region of interest is still a valuable option to determine the background intensity and curvature from a fitted regression of background portions of the scan, but this technique retains an element of subjectivity as the analyst has to select areas in the scan, which appear to represent background. We present here a new method, "Multi-Point Background" (MPB), that allows acquiring up to 24 off-peak background measurements from wavelength positions around the peaks. This method aims to improve the accuracy, precision, and objectivity of trace element analysis. The overall efficiency is amended because no systematic WDS scan needs to be acquired in order to check for the presence of possible background interferences. Moreover, the method is less subjective because "true" backgrounds are selected by the statistical exclusion of erroneous background measurements, reducing the need for analyst intervention. This idea originated from efforts to refine EPMA monazite U-Th-Pb dating, where it was recognised that background errors (peak interference or background curvature) could result in errors of several tens of million years on the calculated age. Results obtained on a CAMECA SX-100 "UltraChron" using monazite

  17. Impact of survey workflow on precision and accuracy of terrestrial LiDAR datasets

    NASA Astrophysics Data System (ADS)

    Gold, P. O.; Cowgill, E.; Kreylos, O.

    2009-12-01

    Ground-based LiDAR (Light Detection and Ranging) survey techniques are enabling remote visualization and quantitative analysis of geologic features at unprecedented levels of detail. For example, digital terrain models computed from LiDAR data have been used to measure displaced landforms along active faults and to quantify fault-surface roughness. But how accurately do terrestrial LiDAR data represent the true ground surface, and in particular, how internally consistent and precise are the mosaiced LiDAR datasets from which surface models are constructed? Addressing this question is essential for designing survey workflows that capture the necessary level of accuracy for a given project while minimizing survey time and equipment, which is essential for effective surveying of remote sites. To address this problem, we seek to define a metric that quantifies how scan registration error changes as a function of survey workflow. Specifically, we are using a Trimble GX3D laser scanner to conduct a series of experimental surveys to quantify how common variables in field workflows impact the precision of scan registration. Primary variables we are testing include 1) use of an independently measured network of control points to locate scanner and target positions, 2) the number of known-point locations used to place the scanner and point clouds in 3-D space, 3) the type of target used to measure distances between the scanner and the known points, and 4) setting up the scanner over a known point as opposed to resectioning of known points. Precision of the registered point cloud is quantified using Trimble Realworks software by automatic calculation of registration errors (errors between locations of the same known points in different scans). Accuracy of the registered cloud (i.e., its ground-truth) will be measured in subsequent experiments. To obtain an independent measure of scan-registration errors and to better visualize the effects of these errors on a registered point

  18. Cumulative incidence of childhood autism: a total population study of better accuracy and precision.

    PubMed

    Honda, Hideo; Shimizu, Yasuo; Imai, Miho; Nitto, Yukari

    2005-01-01

    Most studies on the frequency of autism have had methodological problems. Most notable of these have been differences in diagnostic criteria between studies, degree of cases overlooked by the initial screening, and type of measurement. This study aimed to replicate the first report on childhood autism to address cumulative incidence as well as prevalence, as defined in the International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) Diagnostic Criteria for Research. Here, the same methodological accuracy (exactness of a measurement to the true value) as the first study was used, but population size was four times larger to achieve greater precision (reduction of random error). A community-oriented system of early detection and early intervention for developmental disorders was established in the northern part of Yokohama, Japan. The city's routine health checkup for 18-month-old children served as the initial mass screening, and all facilities that provided child care services aimed to detect all cases of childhood autism and refer them to the Yokohama Rehabilitation Center. Cumulative incidence up to age 5 years was calculated for childhood autism among a birth cohort from four successive years (1988 to 1991). Cumulative incidence of childhood autism was 27.2 per 10000. Cumulative incidences by sex were 38.4 per 10000 in males, and 15.5 per 10000 in females. The male:female ratio was 2.5:1. The proportions of children with high-functioning autism who had Binet IQs of 70 and over and those with Binet IQs of 85 and over were 25.3% and 13.7% respectively. Data on cumulative incidence of childhood autism derived from this study are the first to be drawn from an accurate, as well as precise, screening methodology.

  19. The Accuracy and Precision of Flow Measurements Using Phase Contrast Techniques

    NASA Astrophysics Data System (ADS)

    Tang, Chao

    Quantitative volume flow rate measurements using the magnetic resonance imaging technique are studied in this dissertation because the volume flow rates have a special interest in the blood supply of the human body. The method of quantitative volume flow rate measurements is based on the phase contrast technique, which assumes a linear relationship between the phase and flow velocity of spins. By measuring the phase shift of nuclear spins and integrating velocity across the lumen of the vessel, we can determine the volume flow rate. The accuracy and precision of volume flow rate measurements obtained using the phase contrast technique are studied by computer simulations and experiments. The various factors studied include (1) the partial volume effect due to voxel dimensions and slice thickness relative to the vessel dimensions; (2) vessel angulation relative to the imaging plane; (3) intravoxel phase dispersion; (4) flow velocity relative to the magnitude of the flow encoding gradient. The partial volume effect is demonstrated to be the major obstacle to obtaining accurate flow measurements for both laminar and plug flow. Laminar flow can be measured more accurately than plug flow in the same condition. Both the experiment and simulation results for laminar flow show that, to obtain the accuracy of volume flow rate measurements to within 10%, at least 16 voxels are needed to cover the vessel lumen. The accuracy of flow measurements depends strongly on the relative intensity of signal from stationary tissues. A correction method is proposed to compensate for the partial volume effect. The correction method is based on a small phase shift approximation. After the correction, the errors due to the partial volume effect are compensated, allowing more accurate results to be obtained. An automatic program based on the correction method is developed and implemented on a Sun workstation. The correction method is applied to the simulation and experiment results. The

  20. Analysis of Current Position Determination Accuracy in Natural Resources Canada Precise Point Positioning Service

    NASA Astrophysics Data System (ADS)

    Krzan, Grzegorz; Dawidowicz, Karol; Krzysztof, Świaţek

    2013-09-01

    Precise Point Positioning (PPP) is a technique used to determine highprecision position with a single GNSS receiver. Unlike DGPS or RTK, satellite observations conducted by the PPP technique are not differentiated, therefore they require that parameter models should be used in data processing, such as satellite clock and orbit corrections. Apart from explaining the theory of the PPP technique, this paper describes the available web-based online services used in the post-processing of observation results. The results obtained in the post-processing of satellite observations at three points, with different characteristics of environment conditions, using the CSRS-PPP service, will be presented as the results of the experiment. This study examines the effect of the duration of the measurement session on the results and compares the results obtained by working out observations made by the GPS system and the combined observations from GPS and GLONASS. It also presents the analysis of the position determination accuracy using one and two measurement frequencies

  1. Precision and accuracy of regional radioactivity quantitation using the maximum likelihood EM reconstruction algorithm

    SciTech Connect

    Carson, R.E.; Yan, Y.; Chodkowski, B.; Yap, T.K.; Daube-Witherspoon, M.E. )

    1994-09-01

    The imaging characteristics of maximum likelihood (ML) reconstruction using the EM algorithm for emission tomography have been extensively evaluated. There has been less study of the precision and accuracy of ML estimates of regional radioactivity concentration. The authors developed a realistic brain slice simulation by segmenting a normal subject's MRI scan into gray matter, white matter, and CSF and produced PET sinogram data with a model that included detector resolution and efficiencies, attenuation, scatter, and randoms. Noisy realizations at different count levels were created, and ML and filtered backprojection (FBP) reconstructions were performed. The bias and variability of ROI values were determined. In addition, the effects of ML pixel size, image smoothing and region size reduction were assessed. ML estimates at 1,000 iterations (0.6 sec per iteration on a parallel computer) for 1-cm[sup 2] gray matter ROIs showed negative biases of 6% [+-] 2% which can be reduced to 0% [+-] 3% by removing the outer 1-mm rim of each ROI. FBP applied to the full-size ROIs had 15% [+-] 4% negative bias with 50% less noise than ML. Shrinking the FBP regions provided partial bias compensation with noise increases to levels similar to ML. Smoothing of ML images produced biases comparable to FBP with slightly less noise. Because of its heavy computational requirements, the ML algorithm will be most useful for applications in which achieving minimum bias is important.

  2. 13 Years of TOPEX/POSEIDON Precision Orbit Determination and the 10-fold Improvement in Expected Orbit Accuracy

    NASA Technical Reports Server (NTRS)

    Lemoine, F. G.; Zelensky, N. P.; Luthcke, S. B.; Rowlands, D. D.; Beckley, B. D.; Klosko, S. M.

    2006-01-01

    Launched in the summer of 1992, TOPEX/POSEIDON (T/P) was a joint mission between NASA and the Centre National d Etudes Spatiales (CNES), the French Space Agency, to make precise radar altimeter measurements of the ocean surface. After the remarkably successful 13-years of mapping the ocean surface T/P lost its ability to maneuver and was de-commissioned January 2006. T/P revolutionized the study of the Earth s oceans by vastly exceeding pre-launch estimates of surface height accuracy recoverable from radar altimeter measurements. The precision orbit lies at the heart of the altimeter measurement providing the reference frame from which the radar altimeter measurements are made. The expected quality of orbit knowledge had limited the measurement accuracy expectations of past altimeter missions, and still remains a major component in the error budget of all altimeter missions. This paper describes critical improvements made to the T/P orbit time series over the 13-years of precise orbit determination (POD) provided by the GSFC Space Geodesy Laboratory. The POD improvements from the pre-launch T/P expectation of radial orbit accuracy and Mission requirement of 13-cm to an expected accuracy of about 1.5-cm with today s latest orbits will be discussed. The latest orbits with 1.5 cm RMS radial accuracy represent a significant improvement to the 2.0-cm accuracy orbits currently available on the T/P Geophysical Data Record (GDR) altimeter product.

  3. Accuracy and precision of the three-dimensional assessment of the facial surface using a 3-D laser scanner.

    PubMed

    Kovacs, L; Zimmermann, A; Brockmann, G; Baurecht, H; Schwenzer-Zimmerer, K; Papadopulos, N A; Papadopoulos, M A; Sader, R; Biemer, E; Zeilhofer, H F

    2006-06-01

    Three-dimensional (3-D) recording of the surface of the human body or anatomical areas has gained importance in many medical specialties. Thus, it is important to determine scanner precision and accuracy in defined medical applications and to establish standards for the recording procedure. Here we evaluated the precision and accuracy of 3-D assessment of the facial area with the Minolta Vivid 910 3D Laser Scanner. We also investigated the influence of factors related to the recording procedure and the processing of scanner data on final results. These factors include lighting, alignment of scanner and object, the examiner, and the software used to convert measurements into virtual images. To assess scanner accuracy, we compared scanner data to those obtained by manual measurements on a dummy. Less than 7% of all results with the scanner method were outside a range of error of 2 mm when compared to corresponding reference measurements. Accuracy, thus, proved to be good enough to satisfy requirements for numerous clinical applications. Moreover, the experiments completed with the dummy yielded valuable information for optimizing recording parameters for best results. Thus, under defined conditions, precision and accuracy of surface models of the human face recorded with the Minolta Vivid 910 3D Scanner presumably can also be enhanced. Future studies will involve verification of our findings using test persons. The current findings indicate that the Minolta Vivid 910 3D Scanner might be used with benefit in medicine when recording the 3-D surface structures of the face.

  4. Variance decomposition: a tool enabling strategic improvement of the precision of analytical recovery and concentration estimates associated with microorganism enumeration methods.

    PubMed

    Schmidt, P J; Emelko, M B; Thompson, M E

    2014-05-15

    Concentrations of particular types of microorganisms are commonly measured in various waters, yet the accuracy and precision of reported microorganism concentration values are often questioned due to the imperfect analytical recovery of quantitative microbiological methods and the considerable variation among fully replicated measurements. The random error in analytical recovery estimates and unbiased concentration estimates may be attributable to several sources, and knowing the relative contribution from each source can facilitate strategic design of experiments to yield more precise data or provide an acceptable level of information with fewer data. Herein, variance decomposition using the law of total variance is applied to previously published probabilistic models to explore the relative contributions of various sources of random error and to develop tools to aid experimental design. This work focuses upon enumeration-based methods with imperfect analytical recovery (such as enumeration of Cryptosporidium oocysts), but the results also yield insights about plating methods and microbial methods in general. Using two hypothetical analytical recovery profiles, the variance decomposition method is used to explore 1) the design of an experiment to quantify variation in analytical recovery (including the size and precision of seeding suspensions and the number of samples), and 2) the design of an experiment to estimate a single microorganism concentration (including sample volume, effects of improving analytical recovery, and replication). In one illustrative example, a strategically designed analytical recovery experiment with 6 seeded samples would provide as much information as an alternative experiment with 15 seeded samples. Several examples of diminishing returns are illustrated to show that efforts to reduce error in analytical recovery and concentration estimates can have negligible effect if they are directed at trivial error sources.

  5. Using statistics and software to maximize precision and accuracy in U-Pb geochronological measurements

    NASA Astrophysics Data System (ADS)

    McLean, N.; Bowring, J. F.; Bowring, S. A.

    2009-12-01

    Uncertainty in U-Pb geochronology results from a wide variety of factors, including isotope ratio determinations, common Pb corrections, initial daughter product disequilibria, instrumental mass fractionation, isotopic tracer calibration, and U decay constants and isotopic composition. The relative contribution of each depends on the proportion of radiogenic to common Pb, the measurement technique, and the quality of systematic error determinations. Random and systematic uncertainty contributions may be propagated into individual analyses or for an entire population, and must be propagated correctly to accurately interpret data. Tripoli and U-Pb_Redux comprise a new data reduction and error propagation software package that combines robust cycle measurement statistics with rigorous multivariate data analysis and presents the results graphically and interactively. Maximizing the precision and accuracy of a measurement begins with correct appraisal and codification of the systematic and random errors for each analysis. For instance, a large dataset of total procedural Pb blank analyses defines a multivariate normal distribution, describing the mean of and variation in isotopic composition (IC) that must be subtracted from each analysis. Uncertainty in the size and IC of each Pb blank is related to the (random) uncertainty in ratio measurements and the (systematic) uncertainty involved in tracer subtraction. Other sample and measurement parameters can be quantified in the same way, represented as statistical distributions that describe their uncertainty or variation, and are input into U-Pb_Redux as such before the raw sample isotope ratios are measured. During sample measurement, U-Pb_Redux and Tripoli can relay cycle data in real time, calculating a date and uncertainty for each new cycle or block. The results are presented in U-Pb_Redux as an interactive user interface with multiple visualization tools. One- and two-dimensional plots of each calculated date and

  6. Compensation of Environment and Motion Error for Accuracy Improvement of Ultra-Precision Lathe

    NASA Astrophysics Data System (ADS)

    Kwac, Lee-Ku; Kim, Jae-Yeol; Kim, Hong-Gun

    The technological manipulation of the piezo-electric actuator could compensate for the errors of the machining precision during the process of machining which lead to an elevation and enhancement in overall precisions. This manipulation is a very convenient method to advance the precision for nations without the solid knowledge of the ultra-precision machining technology. There were 2 divisions of researches conducted to develop the UPCU for precision enhancement of the current lathe and compensation for the environmental errors as shown below; The first research was designed to measure and real-time correct any deviations in variety of areas to achieve a compensation system through more effective optical fiber laser encoder than the encoder resolution which was currently used in the existing lathe. The deviations for a real-time correction were composed of followings; the surrounding air temperature, the thermal deviations of the machining materials, the thermal deviations in spindles, and the overall thermal deviation occurred due to the machine structure. The second research was to develop the UPCU and to improve the machining precision through the ultra-precision positioning and the real-time operative error compensation. The ultimate goal was to improve the machining precision of the existing lathe through completing the 2 research tasks mentioned above.

  7. Accuracy and precision of total mixed rations fed on commercial dairy farms.

    PubMed

    Sova, A D; LeBlanc, S J; McBride, B W; DeVries, T J

    2014-01-01

    Despite the significant time and effort spent formulating total mixed rations (TMR), it is evident that the ration delivered by the producer and that consumed by the cow may not accurately reflect that originally formulated. The objectives of this study were to (1) determine how TMR fed agrees with or differs from TMR formulation (accuracy), (2) determine daily variability in physical and chemical characteristics of TMR delivered (precision), and (3) investigate the relationship between daily variability in ration characteristics and group-average measures of productivity [dry matter intake (DMI), milk yield, milk components, efficiency, and feed sorting] on commercial dairy farms. Twenty-two commercial freestall herds were visited for 7 consecutive days in both summer and winter months. Fresh and refusal feed samples were collected daily to assess particle size distribution, dry matter, and chemical composition. Milk test data, including yield, fat, and protein were collected from a coinciding Dairy Herd Improvement test. Multivariable mixed-effect regression models were used to analyze associations between productivity measures and daily ration variability, measured as coefficient of variation (CV) over 7d. The average TMR [crude protein=16.5%, net energy for lactation (NEL) = 1.7 Mcal/kg, nonfiber carbohydrates = 41.3%, total digestible nutrients = 73.3%, neutral detergent fiber=31.3%, acid detergent fiber=20.5%, Ca = 0.92%, p=0.42%, Mg = 0.35%, K = 1.45%, Na = 0.41%] delivered exceeded TMR formulation for NEL (+0.05 Mcal/kg), nonfiber carbohydrates (+1.2%), acid detergent fiber (+0.7%), Ca (+0.08%), P (+0.02%), Mg (+0.02%), and K (+0.04%) and underfed crude protein (-0.4%), neutral detergent fiber (-0.6%), and Na (-0.1%). Dietary measures with high day-to-day CV were average feed refusal rate (CV = 74%), percent long particles (CV = 16%), percent medium particles (CV = 7.7%), percent short particles (CV = 6.1%), percent fine particles (CV = 13%), Ca (CV = 7

  8. Long-term accuracy and precision of PIXE and PIGE measurements for thin and thick sample analyses

    NASA Astrophysics Data System (ADS)

    Cohen, David D.; Siegele, Rainer; Orlic, Ivo; Stelcer, Ed

    2002-04-01

    This paper describes PIXE/PIGE measurements on thin Micromatter Standard (±5%) foils run over a period of 10 years. The selected foils were typically 50 μg/cm 2 thick and covered the commonly used PIXE X-ray energy range 1.4-20 keV and the light elements F and Na for PIGE studies. For the thousands of thick obsidian and pottery samples analysed over a 6-year period, the Ohio Red Clay standard has been used for both PIXE and PIGE calibration of a range of elements from Li to Rb. For PIXE, the long-term accuracy could be as low as ±1.6% for major elements with precision ranging from ±5% to ±10% depending on the elemental concentration. For PIGE, accuracies were around ±5% with precision ranging from ±5% in thick samples to ±15% in thin samples or for low yield γ-ray production.

  9. Precision and accuracy of ST-EDXRF performance for As determination comparing with ICP-MS and evaluation of As deviation in the soil media.

    PubMed

    Akbulut, Songul; Cevik, Ugur; Van, Aydın Ali; De Wael, Karolien; Van Grieken, Rene

    2014-02-01

    The present study was conducted to (i) determine the precision and accuracy of arsenic measurement in soil samples using ST-EDXRF by comparison with the results of ICP-MS analyses and (ii) identify the relationship of As concentration with soil characteristics. For the analysis of samples, inductively coupled plasma mass spectrometry (ICP-MS) and energy dispersive X-ray fluorescence spectrometry (EDXRF) were performed. According to the results found in the soil samples, the addition of HCl to HNO3, used for the digestion gave significant variations in the recovery of As. However, spectral interferences between peaks for As and Pb can affect detection limits and accuracy for XRF analysis. When comparing the XRF and ICP-MS results a correlation was observed with R(2)=0.8414. This means that using a ST-EDXRF spectrometer, it is possible to achieve accurate and precise analysis by the calibration of certified reference materials and choosing an appropriate secondary target. On the other hand, with regard to soil characteristics analyses, the study highlighted that As is mostly anthropogenically enriched in the studied area.

  10. Quantifying Vegetation Change in Semiarid Environments: Precision and Accuracy of Spectral Mixture Analysis and the Normalized Difference Vegetation Index

    NASA Technical Reports Server (NTRS)

    Elmore, Andrew J.; Mustard, John F.; Manning, Sara J.; Elome, Andrew J.

    2000-01-01

    Because in situ techniques for determining vegetation abundance in semiarid regions are labor intensive, they usually are not feasible for regional analyses. Remotely sensed data provide the large spatial scale necessary, but their precision and accuracy in determining vegetation abundance and its change through time have not been quantitatively determined. In this paper, the precision and accuracy of two techniques, Spectral Mixture Analysis (SMA) and Normalized Difference Vegetation Index (NDVI) applied to Landsat TM data, are assessed quantitatively using high-precision in situ data. In Owens Valley, California we have 6 years of continuous field data (1991-1996) for 33 sites acquired concurrently with six cloudless Landsat TM images. The multitemporal remotely sensed data were coregistered to within 1 pixel, radiometrically intercalibrated using temporally invariante surface features and geolocated to within 30 m. These procedures facilitated the accurate location of field-monitoring sites within the remotely sensed data. Formal uncertainties in the registration, radiometric alignment, and modeling were determined. Results show that SMA absolute percent live cover (%LC) estimates are accurate to within ?4.0%LC and estimates of change in live cover have a precision of +/-3.8%LC. Furthermore, even when applied to areas of low vegetation cover, the SMA approach correctly determined the sense of clump, (i.e., positive or negative) in 87% of the samples. SMA results are superior to NDVI, which, although correlated with live cover, is not a quantitative measure and showed the correct sense of change in only 67%, of the samples.

  11. Interproton distance determinations by NOE--surprising accuracy and precision in a rigid organic molecule.

    PubMed

    Butts, Craig P; Jones, Catharine R; Towers, Emma C; Flynn, Jennifer L; Appleby, Lara; Barron, Nicholas J

    2011-01-07

    The accuracy inherent in the measurement of interproton distances in small molecules by nuclear Overhauser enhancement (NOE) and rotational Overhauser enhancement (ROE) methods is investigated with the rigid model compound strychnine. The results suggest that interproton distances can be established with a remarkable level of accuracy, within a few percent of their true values, using a straight-forward data analysis method if experiments are conducted under conditions that support the initial rate approximation. Dealing with deviations from these conditions and other practical issues regarding these measurements are discussed.

  12. Meta-analysis of time perception and temporal processing in schizophrenia: Differential effects on precision and accuracy.

    PubMed

    Thoenes, Sven; Oberfeld, Daniel

    2017-03-29

    Numerous studies have reported that time perception and temporal processing are impaired in schizophrenia. In a meta-analytical review, we differentiate between time perception (judgments of time intervals) and basic temporal processing (e.g., judgments of temporal order) as well as between effects on accuracy (deviation of estimates from the veridical value) and precision (variability of judgments). In a meta-regression approach, we also included the specific tasks and the different time interval ranges as covariates. We considered 68 publications of the past 65years, and meta-analyzed data from 957 patients with schizophrenia and 1060 healthy control participants. Independent of tasks and interval durations, our results demonstrate that time perception and basic temporal processing are less precise (more variable) in patients (Hedges' g>1.00), whereas effects of schizophrenia on accuracy of time perception are rather small and task-dependent. Our review also shows that several aspects, e.g., potential influences of medication, have not yet been investigated in sufficient detail. In conclusion, the results are in accordance with theoretical assumptions and the notion of a more variable internal clock in patients with schizophrenia, but not with a strong effect of schizophrenia on clock speed. The impairment of temporal precision, however, may also be clock-unspecific as part of a general cognitive deficiency in schizophrenia.

  13. A high-precision Jacob's staff with improved spatial accuracy and laser sighting capability

    NASA Astrophysics Data System (ADS)

    Patacci, Marco

    2016-04-01

    A new Jacob's staff design incorporating a 3D positioning stage and a laser sighting stage is described. The first combines a compass and a circular spirit level on a movable bracket and the second introduces a laser able to slide vertically and rotate on a plane parallel to bedding. The new design allows greater precision in stratigraphic thickness measurement while restricting the cost and maintaining speed of measurement to levels similar to those of a traditional Jacob's staff. Greater precision is achieved as a result of: a) improved 3D positioning of the rod through the use of the integrated compass and spirit level holder; b) more accurate sighting of geological surfaces by tracing with height adjustable rotatable laser; c) reduced error when shifting the trace of the log laterally (i.e. away from the dip direction) within the trace of the laser plane, and d) improved measurement of bedding dip and direction necessary to orientate the Jacob's staff, using the rotatable laser. The new laser holder design can also be used to verify parallelism of a geological surface with structural dip by creating a visual planar datum in the field and thus allowing determination of surfaces which cut the bedding at an angle (e.g., clinoforms, levees, erosion surfaces, amalgamation surfaces, etc.). Stratigraphic thickness measurements and estimates of measurement uncertainty are valuable to many applications of sedimentology and stratigraphy at different scales (e.g., bed statistics, reconstruction of palaeotopographies, depositional processes at bed scale, architectural element analysis), especially when a quantitative approach is applied to the analysis of the data; the ability to collect larger data sets with improved precision will increase the quality of such studies.

  14. Event Clustering: Accuracy and Precision of Multiple Event Locations with Sparse Networks

    NASA Astrophysics Data System (ADS)

    Baldwin, T. K.; Wallace, T. C.

    2002-12-01

    In the last 15 years passive PASSCAL experiments have been fielded on every continent. Most of these deployments were designed to record teleseismic or large local seismic events to infer crustal and mantle structure. However, the deployments inevitably record small, local seismicity. Unfortunately, the configuration of the experiments are not optimal for location (typically the stations are arranged in linear arrays), and the seismicity is recorded at a very limited number of stations. The standard location procedure (Geiger's method) is severely limited without a detailed crustal model. A number of methods have been developed to improve relative location precision, including Joint Hypocenter Determination (JHD) and Progressive Multiple Event Location (PMEL). In this study we investigate the performance of PMEL for a very sparse network where there appears to be strong event clustering. CHARGE is a passive deployment of broadband seismometers in Chile and Argentina, with a primary focus of investigating the changes in dip along the descending Nazca Plate. The CHARGE stations recorded a large number of small, local events in 2000-2002. For this study events were selected from the northern profile (approximately along 30o S) in Chile. The events look similar, and appear to be clustered southeast of the city of La Serena. We performed three sets of experiments to investigate precision: (1) iterative Master Event Corrections to measure the scale length of clusters, (2) PMEL locations, and (3) PMEL locations using a cross-correlation to determine accurate relative phase timing. The analysis shows that for the PMEL experiment clusters must occupy an area of 600 km2 for the results to be consistent. We will present a method to estimate the precision errors based on bootstrapping. Charge Team: S. Beck, G. Zandt, M. Anderson, H. Folsom, R. Fromm, T. Shearer, L. Wagner, and P. Alvarado (all University of Arizona), J. Campos, E. Kausel, and J. Paredes (all University of

  15. [Studies on the accuracy and precision of total serum cholesterol in regional interlaboratory trials (author's transl)].

    PubMed

    Hohenwallner, W; Sommer, R; Wimmer, E

    1976-01-02

    The between-run precision of the Liebermann-Burchard reaction modified by Watson was, in our laboratory, 2-3%, the within-run coefficient of variation was 1-2%. The between-run precision of the enzymatic test was 3-4%, the within-run coefficient of variation was 3%. The regression analysis of 92 serum specimens from patients was y = -17.31 + 1.04 chi, the coefficient of regression was r = 0.996. Interlaboratory trials of serum cholesterol were studied in the normal and pathological range. Lyophilized samples of serum prepared commercially and from fresh specimens from patients were analysed by the method of Liebermann-Burchard as well as by the enzymatic procedure. Acceptable results estimated by Liebermann-Burchard were obtained in the different laboratories after using a common standard of cholesterol. The coefficient of variation of the enzymatic test in the interlaboratory trial was higher in comparison to the Liebermann-Burchard reaction. Methodological difficulties of the Liebermann-Burchard reaction are discussed and compared with the specific, enzymatic assay.

  16. Precision and Accuracy in the Determination of Sulfur Oxides, Fluoride, and Spherical Aluminosilicate Fly Ash Particles in Project MOHAVE.

    PubMed

    Eatough, Norman L; Eatough, Michele; Joseph, Jyothi M; Caka, Fern M; Lewis, Laura; Eatough, Delbert J

    1997-04-01

    The precision and accuracy of the determination of particulate sulfate and fluoride, and gas phase S02 and HF are estimated from the results obtained from collocated replicate samples and from collocated comparison samples for highland low-volume filter pack and annular diffusion denuder samplers. The results of replicate analysis of collocated samples and replicate analyses of a given sample for the determination of spherical aluminosilicate fly ash particles have also been compared. Each of these species is being used in the chemical mass balance source apportionment of sulfur oxides in the Grand Canyon region as part of Project MOHAVE, and the precision and accuracy analyses given in this paper provide input to that analysis. The precision of the various measurements reported here is ±1.8 nmol/m(3) and ±2.5 nmol/m(3) for the determination of S02 and sulfate, respectively, with an annular denuder. The precision is ±0.5 nmol/m(3) and ±2.0 nmol/m(3) for the determination of the same species with a high-volume or low-volume filter pack. The precision for the determination of the sum of HF(g) and fine particulate fluoride is +0.3 nmol/m(3). The precision for the determination of aluminosilicate fly ash particles is ±100 particles/m(3). At high concentrations of the various species, reproducibility of the various measurements is ±10% to ±14% of the measured concentration. The concentrations of sulfate determined using filter pack samplers are frequently higher than those determined using diffusion denuder sampling systems. The magnitude of the difference (e.g., 2-10 nmol sulfate/m(3)) is small, but important relative to the precision of the data and the concentrations of particulate sulfate present (typically 5-20 nmol sulfate/m(3)). The concentrations of S02(g) determined using a high-volume cascade impactor filter pack sampler are correspondingly lower than those obtained with diffusion denuder samplers. The concentrations of SOx (SOz(g) plus particulate

  17. ACCURACY AND PRECISION OF A METHOD TO STUDY KINEMATICS OF THE TEMPOROMANDIBULAR JOINT: COMBINATION OF MOTION DATA AND CT IMAGING

    PubMed Central

    Baltali, Evre; Zhao, Kristin D.; Koff, Matthew F.; Keller, Eugene E.; An, Kai-Nan

    2008-01-01

    The purpose of the study was to test the precision and accuracy of a method used to track selected landmarks during motion of the temporomandibular joint (TMJ). A precision phantom device was constructed and relative motions between two rigid bodies on the phantom device were measured using optoelectronic (OE) and electromagnetic (EM) motion tracking devices. The motion recordings were also combined with a 3D CT image for each type of motion tracking system (EM+CT and OE+CT) to mimic methods used in previous studies. In the OE and EM data collections, specific landmarks on the rigid bodies were determined using digitization. In the EM+CT and OE+CT data sets, the landmark locations were obtained from the CT images. 3D linear distances and 3D curvilinear path distances were calculated for the points. The accuracy and precision for all 4 methods were evaluated (EM, OE, EM+CT and OE+CT). In addition, results were compared with and without the CT imaging (EM vs. EM+CT, OE vs. OE+CT). All systems overestimated the actual 3D curvilinear path lengths. All systems also underestimated the actual rotation values. The accuracy of all methods was within 0.5 mm for 3D curvilinear path calculations, 0.05 mm for 3D linear distance calculations, and 0.2° for rotation calculations. In addition, Bland-Altman plots for each configuration of the systems suggest that measurements obtained from either system are repeatable and comparable. PMID:18617178

  18. Performance characterization of precision micro robot using a machine vision system over the Internet for guaranteed positioning accuracy

    NASA Astrophysics Data System (ADS)

    Kwon, Yongjin; Chiou, Richard; Rauniar, Shreepud; Sosa, Horacio

    2005-11-01

    There is a missing link between a virtual development environment (e.g., a CAD/CAM driven offline robotic programming) and production requirements of the actual robotic workcell. Simulated robot path planning and generation of pick-and-place coordinate points will not exactly coincide with the robot performance due to lack of consideration in variations in individual robot repeatability and thermal expansion of robot linkages. This is especially important when robots are controlled and programmed remotely (e.g., through Internet or Ethernet) since remote users have no physical contact with robotic systems. Using the current technology in Internet-based manufacturing that is limited to a web camera for live image transfer has been a significant challenge for the robot task performance. Consequently, the calibration and accuracy quantification of robot critical to precision assembly have to be performed on-site and the verification of robot positioning accuracy cannot be ascertained remotely. In worst case, the remote users have to assume the robot performance envelope provided by the manufacturers, which may causes a potentially serious hazard for system crash and damage to the parts and robot arms. Currently, there is no reliable methodology for remotely calibrating the robot performance. The objective of this research is, therefore, to advance the current state-of-the-art in Internet-based control and monitoring technology, with a specific aim in the accuracy calibration of micro precision robotic system for the development of a novel methodology utilizing Ethernet-based smart image sensors and other advanced precision sensory control network.

  19. Note: electronic circuit for two-way time transfer via a single coaxial cable with picosecond accuracy and precision.

    PubMed

    Prochazka, Ivan; Kodet, Jan; Panek, Petr

    2012-11-01

    We have designed, constructed, and tested the overall performance of the electronic circuit for the two-way time transfer between two timing devices over modest distances with sub-picosecond precision and a systematic error of a few picoseconds. The concept of the electronic circuit enables to carry out time tagging of pulses of interest in parallel to the comparison of the time scales of these timing devices. The key timing parameters of the circuit are: temperature change of the delay is below 100 fs/K, timing stability time deviation better than 8 fs for averaging time from minutes to hours, sub-picosecond time transfer precision, and a few picoseconds time transfer accuracy.

  20. The development and flight test of a deployable precision landing system for spacecraft recovery

    NASA Astrophysics Data System (ADS)

    Sim, Alex G.; Murray, James E.; Neufeld, David C.; Reed, R. Dale

    1993-09-01

    A joint NASA Dryden Flight Research Facility and Johnson Space Center program was conducted to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space that included a precision landing. The feasibility of this system was studied using a flight model of a spacecraft in the generic shape of a flattened biconic which weighed approximately 150 lb and was flown under a commercially available, ram-air parachute. Key elements of the vehicle included the Global Positioning System guidance for navigation, flight control computer, ultrasonic sensing for terminal altitude, electronic compass, and onboard data recording. A flight test program was used to develop and refine the vehicle. This vehicle completed an autonomous flight from an altitude of 10,000 ft and a lateral offset of 1.7 miles which resulted in a precision flare and landing into the wind at a predetermined location. At times, the autonomous flight was conducted in the presence of winds approximately equal to vehicle airspeed. Several techniques for computing the winds postflight were evaluated. Future program objectives are also presented.

  1. A time projection chamber for high accuracy and precision fission cross-section measurements

    DOE PAGES

    Heffner, M.; Asner, D. M.; Baker, R. G.; ...

    2014-05-22

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This study provides a detailed description of the design requirements, the design solutions, and the initial performance ofmore » the fissionTPC.« less

  2. A time projection chamber for high accuracy and precision fission cross-section measurements

    SciTech Connect

    Heffner, M.; Asner, D. M.; Baker, R. G.; Baker, J.; Barrett, S.; Brune, C.; Bundgaard, J.; Burgett, E.; Carter, D.; Cunningham, M.; Deaven, J.; Duke, D. L.; Greife, U.; Grimes, S.; Hager, U.; Hertel, N.; Hill, T.; Isenhower, D.; Jewell, K.; King, J.; Klay, J. L.; Kleinrath, V.; Kornilov, N.; Kudo, R.; Laptev, A. B.; Leonard, M.; Loveland, W.; Massey, T. N.; McGrath, C.; Meharchand, R.; Montoya, L.; Pickle, N.; Qu, H.; Riot, V.; Ruz, J.; Sangiorgio, S.; Seilhan, B.; Sharma, S.; Snyder, L.; Stave, S.; Tatishvili, G.; Thornton, R. T.; Tovesson, F.; Towell, D.; Towell, R. S.; Watson, S.; Wendt, B.; Wood, L.; Yao, L.

    2014-05-22

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This study provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  3. A time projection chamber for high accuracy and precision fission cross-section measurements

    NASA Astrophysics Data System (ADS)

    Heffner, M.; Asner, D. M.; Baker, R. G.; Baker, J.; Barrett, S.; Brune, C.; Bundgaard, J.; Burgett, E.; Carter, D.; Cunningham, M.; Deaven, J.; Duke, D. L.; Greife, U.; Grimes, S.; Hager, U.; Hertel, N.; Hill, T.; Isenhower, D.; Jewell, K.; King, J.; Klay, J. L.; Kleinrath, V.; Kornilov, N.; Kudo, R.; Laptev, A. B.; Leonard, M.; Loveland, W.; Massey, T. N.; McGrath, C.; Meharchand, R.; Montoya, L.; Pickle, N.; Qu, H.; Riot, V.; Ruz, J.; Sangiorgio, S.; Seilhan, B.; Sharma, S.; Snyder, L.; Stave, S.; Tatishvili, G.; Thornton, R. T.; Tovesson, F.; Towell, D.; Towell, R. S.; Watson, S.; Wendt, B.; Wood, L.; Yao, L.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4π acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  4. A Time Projection Chamber for High Accuracy and Precision Fission Cross-Section Measurements

    SciTech Connect

    T. Hill; K. Jewell; M. Heffner; D. Carter; M. Cunningham; V. Riot; J. Ruz; S. Sangiorgio; B. Seilhan; L. Snyder; D. M. Asner; S. Stave; G. Tatishvili; L. Wood; R. G. Baker; J. L. Klay; R. Kudo; S. Barrett; J. King; M. Leonard; W. Loveland; L. Yao; C. Brune; S. Grimes; N. Kornilov; T. N. Massey; J. Bundgaard; D. L. Duke; U. Greife; U. Hager; E. Burgett; J. Deaven; V. Kleinrath; C. McGrath; B. Wendt; N. Hertel; D. Isenhower; N. Pickle; H. Qu; S. Sharma; R. T. Thornton; D. Tovwell; R. S. Towell; S.

    2014-09-01

    The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross-section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4p acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross-sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC.

  5. Accuracy and precision of the i-STAT portable clinical analyzer: an analytical point of view.

    PubMed

    Pidetcha, P; Ornvichian, S; Chalachiva, S

    2000-04-01

    The introduction of a new point-of-care testing (POCT) instrument into the market affects medical practice and laboratory services. The i-STAT is designed to improve the speed in the decision making of the medical profession. However, reliability of results would ensure the quality of laboratory data. We, therefore, made an evaluation of the performance of i-STAT using a disposable cartridge EG7 + which is capable of measuring pH, pO2, pCO2 (blood gas), Sodium, Potassium (Electrolytes), Ionized calcium and Hematocrit with only 10 microliters of lithium heparinized blood in 2 minutes. The results were compared with those obtained from routine methods. The results were found to be accurate, precise and correlated with acceptable methods used routinely in the laboratory.

  6. Factors controlling precision and accuracy in isotope-ratio-monitoring mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Hayes, J. M.

    1994-01-01

    The performance of systems in which picomole quantities of sample are mixed with a carrier gas and passed through an isotope-ratio mass spectrometer system was examined experimentally and theoretically. Two different mass spectrometers were used, both having electron-impact ion sources and Faraday cup collector systems. One had an accelerating potential of 10kV and accepted 0.2 mL of He/min, producing, under those conditions, a maximum efficiency of 1 CO2 molecular ion collected per 700 molecules introduced. Comparable figures for the second instrument were 3 kV, 0.5 mL of He/min, and 14000 molecules/ion. Signal pathways were adjusted so that response times were <200 ms. Sample-related ion currents appeared as peaks with widths of 3-30 s. Isotope ratios were determined by comparison to signals produced by standard gases. In spite of rapid variations in signals, observed levels of performance were within a factor of 2 of shot-noise limits. For the 10-kV instrument, sample requirements for standard deviations of 0.1 and 0.5% were 45 and 1.7 pmol, respectively. Comparable requirements for the 3-kV instrument were 900 and 36 pmol. Drifts in instrumental characteristics were adequately neutralized when standards were observed at 20-min intervals. For the 10-kV instrument, computed isotopic compositions were independent of sample size and signal strength over the ranges examined. Nonlinearities of <0.04%/V were observed for the 3-kV system. Procedures for observation and subtraction of background ion currents were examined experimentally and theoretically. For sample/ background ratios varying from >10 to 0.3, precision is expected and observed to decrease approximately 2-fold and to depend only weakly on the precision with which background ion currents have been measured.

  7. Pupil size dynamics during fixation impact the accuracy and precision of video-based gaze estimation.

    PubMed

    Choe, Kyoung Whan; Blake, Randolph; Lee, Sang-Hun

    2016-01-01

    Video-based eye tracking relies on locating pupil center to measure gaze positions. Although widely used, the technique is known to generate spurious gaze position shifts up to several degrees in visual angle because pupil centration can change without eye movement during pupil constriction or dilation. Since pupil size can fluctuate markedly from moment to moment, reflecting arousal state and cognitive processing during human behavioral and neuroimaging experiments, the pupil size artifact is prevalent and thus weakens the quality of the video-based eye tracking measurements reliant on small fixational eye movements. Moreover, the artifact may lead to erroneous conclusions if the spurious signal is taken as an actual eye movement. Here, we measured pupil size and gaze position from 23 human observers performing a fixation task and examined the relationship between these two measures. Results disclosed that the pupils contracted as fixation was prolonged, at both small (<16s) and large (∼4min) time scales, and these pupil contractions were accompanied by systematic errors in gaze position estimation, in both the ellipse and the centroid methods of pupil tracking. When pupil size was regressed out, the accuracy and reliability of gaze position measurements were substantially improved, enabling differentiation of 0.1° difference in eye position. We confirmed the presence of systematic changes in pupil size, again at both small and large scales, and its tight relationship with gaze position estimates when observers were engaged in a demanding visual discrimination task.

  8. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment

    PubMed Central

    Vu, An T.; Phillips, Jeffrey S.; Kay, Kendrick; Phillips, Matthew E.; Johnson, Matthew R.; Shinkareva, Svetlana V.; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2017-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms. PMID:27686111

  9. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment.

    PubMed

    Vu, An T; Phillips, Jeffrey S; Kay, Kendrick; Phillips, Matthew E; Johnson, Matthew R; Shinkareva, Svetlana V; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2016-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms.

  10. Accuracy and precision of cone beam computed tomography in periodontal defects measurement (systematic review)

    PubMed Central

    Anter, Enas; Zayet, Mohammed Khalifa; El-Dessouky, Sahar Hosny

    2016-01-01

    Systematic review of literature was made to assess the extent of accuracy of cone beam computed tomography (CBCT) as a tool for measurement of alveolar bone loss in periodontal defect. A systematic search of PubMed electronic database and a hand search of open access journals (from 2000 to 2015) yielded abstracts that were potentially relevant. The original articles were then retrieved and their references were hand searched for possible missing articles. Only articles that met the selection criteria were included and criticized. The initial screening revealed 47 potentially relevant articles, of which only 14 have met the selection criteria; their CBCT average measurements error ranged from 0.19 mm to 1.27 mm; however, no valid meta-analysis could be made due to the high heterogeneity between the included studies. Under the limitation of the number and strength of the available studies, we concluded that CBCT provides an assessment of alveolar bone loss in periodontal defect with a minimum reported mean measurements error of 0.19 ± 0.11 mm and a maximum reported mean measurements error of 1.27 ± 1.43 mm, and there is no agreement between the studies regarding the direction of the deviation whether over or underestimation. However, we should emphasize that the evidence to this data is not strong. PMID:27563194

  11. Onset-Duration Matching of Acoustic Stimuli Revisited: Conventional Arithmetic vs. Proposed Geometric Measures of Accuracy and Precision

    PubMed Central

    Friedrich, Björn; Heil, Peter

    2017-01-01

    Onsets of acoustic stimuli are salient transients and are relevant in humans for the perception of music and speech. Previous studies of onset-duration discrimination and matching focused on whether onsets are perceived categorically. In this study, we address two issues. First, we revisit onset-duration matching and measure, for 79 conditions, how accurately and precisely human listeners can adjust the onset duration of a comparison stimulus to subjectively match that of a standard stimulus. Second, we explore measures for quantifying performance in this and other matching tasks. The conventional measures of accuracy and precision are defined by arithmetic descriptive statistics and the Euclidean distance function on the real numbers. We propose novel measures based on geometric descriptive statistics and the log-ratio distance function, the Euclidean distance function on the positive-real numbers. Only these properly account for the fact that the magnitude of onset durations, like the magnitudes of most physical quantities, can attain only positive real values. The conventional (arithmetic) measures possess a convexity bias that yields errors that grow with the width of the distribution of matches. This convexity bias leads to misrepresentations of the constant error and could even imply the existence of perceptual illusions where none exist. This is not so for the proposed (geometric) measures. We collected up to 68 matches from a given listener for each condition (about 34,000 matches in total) and examined inter-listener variability and the effects of onset duration, plateau duration, sound level, carrier, and restriction of the range of adjustable comparison stimuli on measures of accuracy and precision. Results obtained with the conventional measures generally agree with those reported in the literature. The variance across listeners is highly heterogeneous for the conventional measures but is homogeneous for the proposed measures. Furthermore, the proposed

  12. Accuracy and reliability of multi-GNSS real-time precise positioning: GPS, GLONASS, BeiDou, and Galileo

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Ge, Maorong; Dai, Xiaolei; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-06-01

    In this contribution, we present a GPS+GLONASS+BeiDou+Galileo four-system model to fully exploit the observations of all these four navigation satellite systems for real-time precise orbit determination, clock estimation and positioning. A rigorous multi-GNSS analysis is performed to achieve the best possible consistency by processing the observations from different GNSS together in one common parameter estimation procedure. Meanwhile, an efficient multi-GNSS real-time precise positioning service system is designed and demonstrated by using the multi-GNSS Experiment, BeiDou Experimental Tracking Network, and International GNSS Service networks including stations all over the world. The statistical analysis of the 6-h predicted orbits show that the radial and cross root mean square (RMS) values are smaller than 10 cm for BeiDou and Galileo, and smaller than 5 cm for both GLONASS and GPS satellites, respectively. The RMS values of the clock differences between real-time and batch-processed solutions for GPS satellites are about 0.10 ns, while the RMS values for BeiDou, Galileo and GLONASS are 0.13, 0.13 and 0.14 ns, respectively. The addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing, reduces the convergence time almost by 70 %, while the positioning accuracy is improved by about 25 %. Some outliers in the GPS-only solutions vanish when multi-GNSS observations are processed simultaneous. The availability and reliability of GPS precise positioning decrease dramatically as the elevation cutoff increases. However, the accuracy of multi-GNSS precise point positioning (PPP) is hardly decreased and few centimeter are still achievable in the horizontal components even with 40 elevation cutoff. At 30 and 40 elevation cutoffs, the availability rates of GPS-only solution drop significantly to only around 70 and 40 %, respectively. However, multi-GNSS PPP can provide precise position estimates continuously (availability rate is more than 99

  13. Precision and accuracy of in vivo bone mineral measurement in rats using dual-energy X-ray absorptiometry.

    PubMed

    Rozenberg, S; Vandromme, J; Neve, J; Aguilera, A; Muregancuro, A; Peretz, A; Kinthaert, J; Ham, H

    1995-01-01

    The aim of this study was to evaluate the precision and accuracy of dual-energy X-ray absorptiometry (DXA) for measuring bone mineral content at different sites of the skeleton in rats. In vitro the reproducibility error was very small (< 1%), but in vivo the intra-observer variability ranged from 0.9% to 6.0%. Several factors have been shown to affect in vivo reproducibility: the reproducibility was better when the results were expressed as bone mineral density (BMD) rather than bone mineral content (BMC), intra-observer variability was better than the inter-observer variability, and a higher error was observed for the tibia compared with that for vertebrae and femur. The accuracy of measurement at the femur and tibia was assessed by comparing the values with ash weight and with biochemically determined calcium content. The correlation coefficients (R) between the in vitro BMC and the dry weight or the calcium content were higher than 0.99 for both the femur and the tibia. SEE ranged between 0.0 g (ash weight) and 2.0 mg (Ca content). Using in vitro BMC, ash weight could be estimated with an accuracy error close to 0 and calcium content with an error ranging between 0.82% and 6.80%. The R values obtained between the in vivo and in vitro BMC were 0.98 and 0.97 respectively for femur and tibia, with SEE of 0.04 and 0.02 g respectively. In conclusion, the in vivo precision of the technique was found to be too low. To be of practical use it is important in the design of experimentation to try to reduce the measurement error.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Accuracy and precision of equine gait event detection during walking with limb and trunk mounted inertial sensors.

    PubMed

    Olsen, Emil; Andersen, Pia Haubro; Pfau, Thilo

    2012-01-01

    The increased variations of temporal gait events when pathology is present are good candidate features for objective diagnostic tests. We hypothesised that the gait events hoof-on/off and stance can be detected accurately and precisely using features from trunk and distal limb-mounted Inertial Measurement Units (IMUs). Four IMUs were mounted on the distal limb and five IMUs were attached to the skin over the dorsal spinous processes at the withers, fourth lumbar vertebrae and sacrum as well as left and right tuber coxae. IMU data were synchronised to a force plate array and a motion capture system. Accuracy (bias) and precision (SD of bias) was calculated to compare force plate and IMU timings for gait events. Data were collected from seven horses. One hundred and twenty three (123) front limb steps were analysed; hoof-on was detected with a bias (SD) of -7 (23) ms, hoof-off with 0.7 (37) ms and front limb stance with -0.02 (37) ms. A total of 119 hind limb steps were analysed; hoof-on was found with a bias (SD) of -4 (25) ms, hoof-off with 6 (21) ms and hind limb stance with 0.2 (28) ms. IMUs mounted on the distal limbs and sacrum can detect gait events accurately and precisely.

  15. Accuracy and precision of free-energy calculations via molecular simulation

    NASA Astrophysics Data System (ADS)

    Lu, Nandou

    A quantitative characterization of the methodologies of free-energy perturbation (FEP) calculations is presented, and optimal implementation of the methods for reliable and efficient calculation is addressed. Some common misunderstandings in the FEP calculations are corrected. The two opposite directions of FEP calculations are uniquely defined as generalized insertion and generalized deletion, according to the entropy change along the perturbation direction. These two calculations are not symmetric; they produce free-energy results differing systematically due to the different capability of each to sample the important phase-space in a finite-length simulation. The FEP calculation errors are quantified by characterizing the simulation sampling process with the help of probability density functions for the potential energy change. While the random error in the FEP calculation is analyzed with a probabilistic approach, the systematic error is characterized as the most-likely inaccuracy, which is modeled considering the poor sampling of low-probability energy distribution tails. Our analysis shows that the entropy difference between the perturbation systems plays a key role in determining the reliability of FEP results, and the perturbation should be carried out in the insertion direction in order to ensure a good sampling and thus a reliable calculation. Easy-to-use heuristics are developed to estimate the simulation errors, as well as the simulation length that ensures a certain accuracy level of the calculation. The fundamental understanding obtained is then applied to tackle the problem of multistage FEP optimization. We provide the first principle of optimal staging: For each substage FEP calculation, the higher entropy system should be used as the reference to govern the sampling, i.e., the calculation should be conducted in the generalized insertion direction for each stage of perturbation. To minimize the simulation error, intermediate states should be

  16. Minimally invasive measurement of cardiac output during surgery and critical care: a meta-analysis of accuracy and precision.

    PubMed

    Peyton, Philip J; Chong, Simon W

    2010-11-01

    When assessing the accuracy and precision of a new technique for cardiac output measurement, the commonly quoted criterion for acceptability of agreement with a reference standard is that the percentage error (95% limits of agreement/mean cardiac output) should be 30% or less. We reviewed published data on four different minimally invasive methods adapted for use during surgery and critical care: pulse contour techniques, esophageal Doppler, partial carbon dioxide rebreathing, and transthoracic bioimpedance, to assess their bias, precision, and percentage error in agreement with thermodilution. An English language literature search identified published papers since 2000 which examined the agreement in adult patients between bolus thermodilution and each method. For each method a meta-analysis was done using studies in which the first measurement point for each patient could be identified, to obtain a pooled mean bias, precision, and percentage error weighted according to the number of measurements in each study. Forty-seven studies were identified as suitable for inclusion: N studies, n measurements: mean weighted bias [precision, percentage error] were: pulse contour N = 24, n = 714: -0.00 l/min [1.22 l/min, 41.3%]; esophageal Doppler N = 2, n = 57: -0.77 l/min [1.07 l/min, 42.1%]; partial carbon dioxide rebreathing N = 8, n = 167: -0.05 l/min [1.12 l/min, 44.5%]; transthoracic bioimpedance N = 13, n = 435: -0.10 l/min [1.14 l/min, 42.9%]. None of the four methods has achieved agreement with bolus thermodilution which meets the expected 30% limits. The relevance in clinical practice of these arbitrary limits should be reassessed.

  17. Accuracy, Precision, Ease-Of-Use, and Cost of Methods to Test Ebola-Relevant Chlorine Solutions.

    PubMed

    Wells, Emma; Wolfe, Marlene K; Murray, Anna; Lantagne, Daniele

    2016-01-01

    To prevent transmission in Ebola Virus Disease (EVD) outbreaks, it is recommended to disinfect living things (hands and people) with 0.05% chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% chlorine solution. In the current West African EVD outbreak, these solutions (manufactured from calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and sodium hypochlorite (NaOCl)) have been widely used in both Ebola Treatment Unit and community settings. To ensure solution quality, testing is necessary, however test method appropriateness for these Ebola-relevant concentrations has not previously been evaluated. We identified fourteen commercially-available methods to test Ebola-relevant chlorine solution concentrations, including two titration methods, four DPD dilution methods, and six test strips. We assessed these methods by: 1) determining accuracy and precision by measuring in quintuplicate five different 0.05% and 0.5% chlorine solutions manufactured from NaDCC, HTH, and NaOCl; 2) conducting volunteer testing to assess ease-of-use; and, 3) determining costs. Accuracy was greatest in titration methods (reference-12.4% error compared to reference method), then DPD dilution methods (2.4-19% error), then test strips (5.2-48% error); precision followed this same trend. Two methods had an accuracy of <10% error across all five chlorine solutions with good precision: Hach digital titration for 0.05% and 0.5% solutions (recommended for contexts with trained personnel and financial resources), and Serim test strips for 0.05% solutions (recommended for contexts where rapid, inexpensive, and low-training burden testing is needed). Measurement error from test methods not including pH adjustment varied significantly across the five chlorine solutions, which had pH values 5-11. Volunteers found test strip easiest and titration hardest; costs per 100 tests were $14-37 for test strips and $33-609 for titration. Given the

  18. Accuracy, Precision, Ease-Of-Use, and Cost of Methods to Test Ebola-Relevant Chlorine Solutions

    PubMed Central

    Wells, Emma; Wolfe, Marlene K.; Murray, Anna; Lantagne, Daniele

    2016-01-01

    To prevent transmission in Ebola Virus Disease (EVD) outbreaks, it is recommended to disinfect living things (hands and people) with 0.05% chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% chlorine solution. In the current West African EVD outbreak, these solutions (manufactured from calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and sodium hypochlorite (NaOCl)) have been widely used in both Ebola Treatment Unit and community settings. To ensure solution quality, testing is necessary, however test method appropriateness for these Ebola-relevant concentrations has not previously been evaluated. We identified fourteen commercially-available methods to test Ebola-relevant chlorine solution concentrations, including two titration methods, four DPD dilution methods, and six test strips. We assessed these methods by: 1) determining accuracy and precision by measuring in quintuplicate five different 0.05% and 0.5% chlorine solutions manufactured from NaDCC, HTH, and NaOCl; 2) conducting volunteer testing to assess ease-of-use; and, 3) determining costs. Accuracy was greatest in titration methods (reference-12.4% error compared to reference method), then DPD dilution methods (2.4–19% error), then test strips (5.2–48% error); precision followed this same trend. Two methods had an accuracy of <10% error across all five chlorine solutions with good precision: Hach digital titration for 0.05% and 0.5% solutions (recommended for contexts with trained personnel and financial resources), and Serim test strips for 0.05% solutions (recommended for contexts where rapid, inexpensive, and low-training burden testing is needed). Measurement error from test methods not including pH adjustment varied significantly across the five chlorine solutions, which had pH values 5–11. Volunteers found test strip easiest and titration hardest; costs per 100 tests were $14–37 for test strips and $33–609 for titration

  19. Accuracy and precision of minimally-invasive cardiac output monitoring in children: a systematic review and meta-analysis.

    PubMed

    Suehiro, Koichi; Joosten, Alexandre; Murphy, Linda Suk-Ling; Desebbe, Olivier; Alexander, Brenton; Kim, Sang-Hyun; Cannesson, Maxime

    2016-10-01

    Several minimally-invasive technologies are available for cardiac output (CO) measurement in children, but the accuracy and precision of these devices have not yet been evaluated in a systematic review and meta-analysis. We conducted a comprehensive search of the medical literature in PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science from its inception to June 2014 assessing the accuracy and precision of all minimally-invasive CO monitoring systems used in children when compared with CO monitoring reference methods. Pooled mean bias, standard deviation, and mean percentage error of included studies were calculated using a random-effects model. The inter-study heterogeneity was also assessed using an I(2) statistic. A total of 20 studies (624 patients) were included. The overall random-effects pooled bias, and mean percentage error were 0.13 ± 0.44 l min(-1) and 29.1 %, respectively. Significant inter-study heterogeneity was detected (P < 0.0001, I(2) = 98.3 %). In the sub-analysis regarding the device, electrical cardiometry showed the smallest bias (-0.03 l min(-1)) and lowest percentage error (23.6 %). Significant residual heterogeneity remained after conducting sensitivity and subgroup analyses based on the various study characteristics. By meta-regression analysis, we found no independent effects of study characteristics on weighted mean difference between reference and tested methods. Although the pooled bias was small, the mean pooled percentage error was in the gray zone of clinical applicability. In the sub-group analysis, electrical cardiometry was the device that provided the most accurate measurement. However, a high heterogeneity between studies was found, likely due to a wide range of study characteristics.

  20. Community-based Approaches to Improving Accuracy, Precision, and Reproducibility in U-Pb and U-Th Geochronology

    NASA Astrophysics Data System (ADS)

    McLean, N. M.; Condon, D. J.; Bowring, S. A.; Schoene, B.; Dutton, A.; Rubin, K. H.

    2015-12-01

    The last two decades have seen a grassroots effort by the international geochronology community to "calibrate Earth history through teamwork and cooperation," both as part of the EARTHTIME initiative and though several daughter projects with similar goals. Its mission originally challenged laboratories "to produce temporal constraints with uncertainties approaching 0.1% of the radioisotopic ages," but EARTHTIME has since exceeded its charge in many ways. Both the U-Pb and Ar-Ar chronometers first considered for high-precision timescale calibration now regularly produce dates at the sub-per mil level thanks to instrumentation, laboratory, and software advances. At the same time new isotope systems, including U-Th dating of carbonates, have developed comparable precision. But the larger, inter-related scientific challenges envisioned at EARTHTIME's inception remain - for instance, precisely calibrating the global geologic timescale, estimating rates of change around major climatic perturbations, and understanding evolutionary rates through time - and increasingly require that data from multiple geochronometers be combined. To solve these problems, the next two decades of uranium-daughter geochronology will require further advances in accuracy, precision, and reproducibility. The U-Th system has much in common with U-Pb, in that both parent and daughter isotopes are solids that can easily be weighed and dissolved in acid, and have well-characterized reference materials certified for isotopic composition and/or purity. For U-Pb, improving lab-to-lab reproducibility has entailed dissolving precisely weighed U and Pb metals of known purity and isotopic composition together to make gravimetric solutions, then using these to calibrate widely distributed tracers composed of artificial U and Pb isotopes. To mimic laboratory measurements, naturally occurring U and Pb isotopes were also mixed in proportions to mimic samples of three different ages, to be run as internal

  1. The Precision and Accuracy of Early Epoch of Reionization Foreground Models: Comparing MWA and PAPER 32-antenna Source Catalogs

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Bowman, Judd; Aguirre, James E.

    2013-05-01

    As observations of the Epoch of Reionization (EoR) in redshifted 21 cm emission begin, we assess the accuracy of the early catalog results from the Precision Array for Probing the Epoch of Reionization (PAPER) and the Murchison Wide-field Array (MWA). The MWA EoR approach derives much of its sensitivity from subtracting foregrounds to <1% precision, while the PAPER approach relies on the stability and symmetry of the primary beam. Both require an accurate flux calibration to set the amplitude of the measured power spectrum. The two instruments are very similar in resolution, sensitivity, sky coverage, and spectral range and have produced catalogs from nearly contemporaneous data. We use a Bayesian Markov Chain Monte Carlo fitting method to estimate that the two instruments are on the same flux scale to within 20% and find that the images are mostly in good agreement. We then investigate the source of the errors by comparing two overlapping MWA facets where we find that the differences are primarily related to an inaccurate model of the primary beam but also correlated errors in bright sources due to CLEAN. We conclude with suggestions for mitigating and better characterizing these effects.

  2. Precision and accuracy of manual water-level measurements taken in the Yucca Mountain area, Nye County, Nevada, 1988-90

    USGS Publications Warehouse

    Boucher, M.S.

    1994-01-01

    Water-level measurements have been made in deep boreholes in the Yucca Mountain area, Nye County, Nevada, since 1983 in support of the U.S. Department of Energy's Yucca Mountain Project, which is an evaluation of the area to determine its suitability as a potential storage area for high-level nuclear waste. Water-level measurements were taken either manually, using various water-level measuring equipment such as steel tapes, or they were taken continuously, using automated data recorders and pressure transducers. This report presents precision range and accuracy data established for manual water-level measurements taken in the Yucca Mountain area, 1988-90. Precision and accuracy ranges were determined for all phases of the water-level measuring process, and overall accuracy ranges are presented. Precision ranges were determined for three steel tapes using a total of 462 data points. Mean precision ranges of these three tapes ranged from 0.014 foot to 0.026 foot. A mean precision range of 0.093 foot was calculated for the multiconductor cable, using 72 data points. Mean accuracy values were calculated on the basis of calibrations of the steel tapes and the multiconductor cable against a reference steel tape. The mean accuracy values of the steel tapes ranged from 0.053 foot, based on three data points to 0.078, foot based on six data points. The mean accuracy of the multiconductor cable was O. 15 foot, based on six data points. Overall accuracy of the water-level measurements was calculated by taking the square root of the sum of the squares of the individual accuracy values. Overall accuracy was calculated to be 0.36 foot for water-level measurements taken with steel tapes, without accounting for the inaccuracy of borehole deviations from vertical. An overall accuracy of 0.36 foot for measurements made with steel tapes is considered satisfactory for this project.

  3. Bracketing method with certified reference materials for high precision and accuracy determination of trace cadmium in drinking water by Inductively Coupled Plasma - Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ketrin, Rosi; Handayani, Eka Mardika; Komalasari, Isna

    2017-01-01

    Two significant parameters to evaluate the measurement results are known as precision and accuracy. Both are associated with indeterminate and determinate error, respectively, that normally happen in such spectrometric measurement method as Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). These errors must be eliminated or suppressed to get high precision and accuracy of the method. Decreasing the errors thus increasing the precision and accuracy of the method. In this study, bracketing method using two-point standard calibration was proposed in order to suppress the indeterminate error caused by instrumental drift thus increasing the result precision, and applied for measuring cadmium in drinking water samples. Certified reference material of ERM CA011b-Hard drinking water UK-metals was used to know the determinate error or measurement bias. When bias is obtained, some corrections are needed to get the accurate measurement result. The result was compared to that by external calibration method.

  4. An evaluation of the accuracy and precision of a stand-alone submersible continuous ruminal pH measurement system.

    PubMed

    Penner, G B; Beauchemin, K A; Mutsvangwa, T

    2006-06-01

    The objectives of this study were 1) to develop and evaluate the accuracy and precision of a new stand-alone submersible continuous ruminal pH measurement system called the Lethbridge Research Centre ruminal pH measurement system (LRCpH; Experiment 1); 2) to establish the accuracy and precision of a well-documented, previously used continuous indwelling ruminal pH system (CIpH) to ensure that the new system (LRCpH) was as accurate and precise as the previous system (CIpH; Experiment 2); and 3) to determine the required frequency for pH electrode standardization by comparing baseline millivolt readings of pH electrodes in pH buffers 4 and 7 after 0, 24, 48, and 72 h of ruminal incubation (Experiment 3). In Experiment 1, 6 pregnant Holstein heifers, 3 lactating, primiparous Holstein cows, and 2 Black Angus heifers were used. All experimental animals were fitted with permanent ruminal cannulas. In Experiment 2, the 3 cannulated, lactating, primiparous Holstein cows were used. In both experiments, ruminal pH was determined continuously using indwelling pH electrodes. Subsequently, mean pH values were then compared with ruminal pH values obtained using spot samples of ruminal fluid (MANpH) obtained at the same time. A correlation coefficient accounting for repeated measures was calculated and results were used to calculate the concordance correlation to examine the relationships between the LRCpH-derived values and MANpH, and the CIpH-derived values and MANpH. In Experiment 3, the 6 pregnant Holstein heifers were used along with 6 new submersible pH electrodes. In Experiments 1 and 2, the comparison of the LRCpH output (1- and 5-min averages) to MANpH had higher correlation coefficients after accounting for repeated measures (0.98 and 0.97 for 1- and 5-min averages, respectively) and concordance correlation coefficients (0.96 and 0.97 for 1- and 5-min averages, respectively) than the comparison of CIpH to MANpH (0.88 and 0.87, correlation coefficient and concordance

  5. Single-frequency receivers as master permanent stations in GNSS networks: precision and accuracy of the positioning in mixed networks

    NASA Astrophysics Data System (ADS)

    Dabove, Paolo; Manzino, Ambrogio Maria

    2015-04-01

    The use of GPS/GNSS instruments is a common practice in the world at both a commercial and academic research level. Since last ten years, Continuous Operating Reference Stations (CORSs) networks were born in order to achieve the possibility to extend a precise positioning more than 15 km far from the master station. In this context, the Geomatics Research Group of DIATI at the Politecnico di Torino has carried out several experiments in order to evaluate the achievable precision obtainable with different GNSS receivers (geodetic and mass-market) and antennas if a CORSs network is considered. This work starts from the research above described, in particular focusing the attention on the usefulness of single frequency permanent stations in order to thicken the existing CORSs, especially for monitoring purposes. Two different types of CORSs network are available today in Italy: the first one is the so called "regional network" and the second one is the "national network", where the mean inter-station distances are about 25/30 and 50/70 km respectively. These distances are useful for many applications (e.g. mobile mapping) if geodetic instruments are considered but become less useful if mass-market instruments are used or if the inter-station distance between master and rover increases. In this context, some innovative GNSS networks were developed and tested, analyzing the performance of rover's positioning in terms of quality, accuracy and reliability both in real-time and post-processing approach. The use of single frequency GNSS receivers leads to have some limits, especially due to a limited baseline length, the possibility to obtain a correct fixing of the phase ambiguity for the network and to fix the phase ambiguity correctly also for the rover. These factors play a crucial role in order to reach a positioning with a good level of accuracy (as centimetric o better) in a short time and with an high reliability. The goal of this work is to investigate about the

  6. A comparative study of submicron particle sizing platforms: accuracy, precision and resolution analysis of polydisperse particle size distributions.

    PubMed

    Anderson, Will; Kozak, Darby; Coleman, Victoria A; Jämting, Åsa K; Trau, Matt

    2013-09-01

    The particle size distribution (PSD) of a polydisperse or multimodal system can often be difficult to obtain due to the inherent limitations in established measurement techniques. For this reason, the resolution, accuracy and precision of three new and one established, commercially available and fundamentally different particle size analysis platforms were compared by measuring both individual and a mixed sample of monodisperse, sub-micron (220, 330, and 410 nm - nominal modal size) polystyrene particles. The platforms compared were the qNano Tunable Resistive Pulse Sensor, Nanosight LM10 Particle Tracking Analysis System, the CPS Instruments's UHR24000 Disc Centrifuge, and the routinely used Malvern Zetasizer Nano ZS Dynamic Light Scattering system. All measurements were subjected to a peak detection algorithm so that the detected particle populations could be compared to 'reference' Transmission Electron Microscope measurements of the individual particle samples. Only the Tunable Resistive Pulse Sensor and Disc Centrifuge platforms provided the resolution required to resolve all three particle populations present in the mixed 'multimodal' particle sample. In contrast, the light scattering based Particle Tracking Analysis and Dynamic Light Scattering platforms were only able to detect a single population of particles corresponding to either the largest (410 nm) or smallest (220 nm) particles in the multimodal sample, respectively. When the particle sets were measured separately (monomodal) each platform was able to resolve and accurately obtain a mean particle size within 10% of the Transmission Electron Microscope reference values. However, the broadness of the PSD measured in the monomodal samples deviated greatly, with coefficients of variation being ~2-6-fold larger than the TEM measurements across all four platforms. The large variation in the PSDs obtained from these four, fundamentally different platforms, indicates that great care must still be taken in

  7. Standardization of Operator-Dependent Variables Affecting Precision and Accuracy of the Disk Diffusion Method for Antibiotic Susceptibility Testing

    PubMed Central

    Maurer, Florian P.; Pfiffner, Tamara; Böttger, Erik C.; Furrer, Reinhard

    2015-01-01

    Parameters like zone reading, inoculum density, and plate streaking influence the precision and accuracy of disk diffusion antibiotic susceptibility testing (AST). While improved reading precision has been demonstrated using automated imaging systems, standardization of the inoculum and of plate streaking have not been systematically investigated yet. This study analyzed whether photometrically controlled inoculum preparation and/or automated inoculation could further improve the standardization of disk diffusion. Suspensions of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213 of 0.5 McFarland standard were prepared by 10 operators using both visual comparison to turbidity standards and a Densichek photometer (bioMérieux), and the resulting CFU counts were determined. Furthermore, eight experienced operators each inoculated 10 Mueller-Hinton agar plates using a single 0.5 McFarland standard bacterial suspension of E. coli ATCC 25922 using regular cotton swabs, dry flocked swabs (Copan, Brescia, Italy), or an automated streaking device (BD-Kiestra, Drachten, Netherlands). The mean CFU counts obtained from 0.5 McFarland standard E. coli ATCC 25922 suspensions were significantly different for suspensions prepared by eye and by Densichek (P < 0.001). Preparation by eye resulted in counts that were closer to the CLSI/EUCAST target of 108 CFU/ml than those resulting from Densichek preparation. No significant differences in the standard deviations of the CFU counts were observed. The interoperator differences in standard deviations when dry flocked swabs were used decreased significantly compared to the differences when regular cotton swabs were used, whereas the mean of the standard deviations of all operators together was not significantly altered. In contrast, automated streaking significantly reduced both interoperator differences, i.e., the individual standard deviations, compared to the standard deviations for the manual method, and the mean of the

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

    PubMed

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

    2011-07-15

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

  9. Accuracy and precision of hind limb foot contact timings of horses determined using a pelvis-mounted inertial measurement unit.

    PubMed

    Starke, Sandra D; Witte, Thomas H; May, Stephen A; Pfau, Thilo

    2012-05-11

    Gait analysis using small sensor units is becoming increasingly popular in the clinical context. In order to segment continuous movement from a defined point of the stride cycle, knowledge about footfall timings is essential. We evaluated the accuracy and precision of foot contact timings of a defined limb determined using an inertial sensor mounted on the pelvis of ten horses during walk and trot at different speeds and in different directions. Foot contact was estimated from vertical velocity events occurring before maximum sensor roll towards the contralateral limb. Foot contact timings matched data from a synchronised hoof mounted accelerometer well when velocity minimum was used for walk (mean (SD) difference of 15 (18)ms across horses) and velocity zero-crossing for trot (mean (SD) difference from -4 (14) to 12 (7)ms depending on the condition). The stride segmentation method also remained robust when applied to movement data of hind limb lame horses. In future, this method may find application in segmenting overground sensor data of various species.

  10. A first investigation of accuracy, precision and sensitivity of phase-based x-ray dark-field imaging

    NASA Astrophysics Data System (ADS)

    Astolfo, Alberto; Endrizzi, Marco; Kallon, Gibril; Millard, Thomas P.; Vittoria, Fabio A.; Olivo, Alessandro

    2016-12-01

    In the last two decades, x-ray phase contrast imaging (XPCI) has attracted attention as a potentially significant improvement over widespread and established x-ray imaging. The key is its capability to access a new physical quantity (the ‘phase shift’), which can be complementary to x-ray absorption. One additional advantage of XPCI is its sensitivity to micro structural details through the refraction induced dark-field (DF). While DF is extensively mentioned and used for several applications, predicting the capability of an XPCI system to retrieve DF quantitatively is not straightforward. In this article, we evaluate the impact of different design options and algorithms on DF retrieval for the edge-illumination (EI) XPCI technique. Monte Carlo simulations, supported by experimental data, are used to measure the accuracy, precision and sensitivity of DF retrieval performed with several EI systems based on conventional x-ray sources. The introduced tools are easy to implement, and general enough to assess the DF performance of systems based on alternative (i.e. non-EI) XPCI approaches.

  11. Evaluation of the accuracy and precision of four intraoral scanners with 70% reduced inlay and four-unit bridge models of international standard.

    PubMed

    Uhm, Soo-Hyuk; Kim, Jae-Hong; Jiang, Heng Bo; Woo, Chang-Woo; Chang, Minho; Kim, Kyoung-Nam; Bae, Ji-Myung; Oh, Seunghan

    2017-01-31

    The aims of this study were to evaluate the feasibility of 70% reduced inlay and 4-unit bridge models of International Standard (ISO 12836) assessing the accuracy of laboratory scanners to measure the accuracy of intraoral scanner. Four intraoral scanners (CS3500, Trios, Omnicam, and Bluecam) and one laboratory scanner (Ceramill MAP400) were used in this study. The height, depth, length, and angle of the models were measured from thirty scanned stereolithography (STL) images. There were no statistically significant mean deviations in distance accuracy and precision values of scanned images, except the angulation values of the inlay and 4-unit bridge models. The relative errors of inlay model and 4-unit bridge models quantifying the accuracy and precision of obtained mean deviations were less than 0.023 and 0.021, respectively. Thus, inlay and 4-unit bridge models suggested by this study is expected to be feasible tools for testing intraoral scanners.

  12. Application of U-Pb ID-TIMS dating to the end-Triassic global crisis: testing the limits on precision and accuracy in a multidisciplinary whodunnit (Invited)

    NASA Astrophysics Data System (ADS)

    Schoene, B.; Schaltegger, U.; Guex, J.; Bartolini, A.

    2010-12-01

    The ca. 201.4 Ma Triassic-Jurassic boundary is characterized by one of the most devastating mass-extinctions in Earth history, subsequent biologic radiation, rapid carbon cycle disturbances and enormous flood basalt volcanism (Central Atlantic Magmatic Province - CAMP). Considerable uncertainty remains regarding the temporal and causal relationship between these events though this link is important for understanding global environmental change under extreme stresses. We present ID-TIMS U-Pb zircon geochronology on volcanic ash beds from two marine sections that span the Triassic-Jurassic boundary and from the CAMP in North America. To compare the timing of the extinction with the onset of the CAMP, we assess the precision and accuracy of ID-TIMS U-Pb zircon geochronology by exploring random and systematic uncertainties, reproducibility, open-system behavior, and pre-eruptive crystallization of zircon. We find that U-Pb ID-TIMS dates on single zircons can be internally and externally reproducible at 0.05% of the age, consistent with recent experiments coordinated through the EARTHTIME network. Increased precision combined with methods alleviating Pb-loss in zircon reveals that these ash beds contain zircon that crystallized between 10^5 and 10^6 years prior to eruption. Mineral dates older than eruption ages are prone to affect all geochronologic methods and therefore new tools exploring this form of “geologic uncertainty” will lead to better time constraints for ash bed deposition. In an effort to understand zircon dates within the framework of a magmatic system, we analyzed zircon trace elements by solution ICPMS for the same volume of zircon dated by ID-TIMS. In one example we argue that zircon trace element patterns as a function of time result from a mix of xeno-, ante-, and autocrystic zircons in the ash bed, and approximate eruption age with the youngest zircon date. In a contrasting example from a suite of Cretaceous andesites, zircon trace elements

  13. An Examination of the Precision and Technical Accuracy of the First Wave of Group-Randomized Trials Funded by the Institute of Education Sciences

    ERIC Educational Resources Information Center

    Spybrook, Jessaca; Raudenbush, Stephen W.

    2009-01-01

    This article examines the power analyses for the first wave of group-randomized trials funded by the Institute of Education Sciences. Specifically, it assesses the precision and technical accuracy of the studies. The authors identified the appropriate experimental design and estimated the minimum detectable standardized effect size (MDES) for each…

  14. Geocoding accuracy and the recovery of relationships between environmental exposures and health

    PubMed Central

    Mazumdar, Soumya; Rushton, Gerard; Smith, Brian J; Zimmerman, Dale L; Donham, Kelley J

    2008-01-01

    Background This research develops methods for determining the effect of geocoding quality on relationships between environmental exposures and health. The likelihood of detecting an existing relationship – statistical power – between measures of environmental exposures and health depends not only on the strength of the relationship but also on the level of positional accuracy and completeness of the geocodes from which the measures of environmental exposure are made. This paper summarizes the results of simulation studies conducted to examine the impact of inaccuracies of geocoded addresses generated by three types of geocoding processes: a) addresses located on orthophoto maps, b) addresses matched to TIGER files (U.S Census or their derivative street files); and, c) addresses from E-911 geocodes (developed by local authorities for emergency dispatch purposes). Results The simulated odds of disease using exposures modelled from the highest quality geocodes could be sufficiently recovered using other, more commonly used, geocoding processes such as TIGER and E-911; however, the strength of the odds relationship between disease exposures modelled at geocodes generally declined with decreasing geocoding accuracy. Conclusion Although these specific results cannot be generalized to new situations, the methods used to determine the sensitivity of results can be used in new situations. Estimated measures of positional accuracy must be used in the interpretation of results of analyses that investigate relationships between health outcomes and exposures measured at residential locations. Analyses similar to those employed in this paper can be used to validate interpretation of results from empirical analyses that use geocoded locations with estimated measures of positional accuracy. PMID:18387189

  15. Deformable Image Registration for Adaptive Radiation Therapy of Head and Neck Cancer: Accuracy and Precision in the Presence of Tumor Changes

    SciTech Connect

    Mencarelli, Angelo; Kranen, Simon Robert van; Hamming-Vrieze, Olga; Beek, Suzanne van; Nico Rasch, Coenraad Robert; Herk, Marcel van; Sonke, Jan-Jakob

    2014-11-01

    Purpose: To compare deformable image registration (DIR) accuracy and precision for normal and tumor tissues in head and neck cancer patients during the course of radiation therapy (RT). Methods and Materials: Thirteen patients with oropharyngeal tumors, who underwent submucosal implantation of small gold markers (average 6, range 4-10) around the tumor and were treated with RT were retrospectively selected. Two observers identified 15 anatomical features (landmarks) representative of normal tissues in the planning computed tomography (pCT) scan and in weekly cone beam CTs (CBCTs). Gold markers were digitally removed after semiautomatic identification in pCTs and CBCTs. Subsequently, landmarks and gold markers on pCT were propagated to CBCTs, using a b-spline-based DIR and, for comparison, rigid registration (RR). To account for observer variability, the pair-wise difference analysis of variance method was applied. DIR accuracy (systematic error) and precision (random error) for landmarks and gold markers were quantified. Time trend of the precisions for RR and DIR over the weekly CBCTs were evaluated. Results: DIR accuracies were submillimeter and similar for normal and tumor tissue. DIR precision (1 SD) on the other hand was significantly different (P<.01), with 2.2 mm vector length in normal tissue versus 3.3 mm in tumor tissue. No significant time trend in DIR precision was found for normal tissue, whereas in tumor, DIR precision was significantly (P<.009) degraded during the course of treatment by 0.21 mm/week. Conclusions: DIR for tumor registration proved to be less precise than that for normal tissues due to limited contrast and complex non-elastic tumor response. Caution should therefore be exercised when applying DIR for tumor changes in adaptive procedures.

  16. A critical period for the recovery of sound localization accuracy following monaural occlusion in the barn owl.

    PubMed

    Knudsen, E I; Knudsen, P F; Esterly, S D

    1984-04-01

    We studied the ability of barn owls to recover accurate sound localization after being raised with one ear occluded. Most of the owls had ear plugs inserted before they reached adult size, and therefore they never experienced normal adult localization cues until their ear plugs were removed. Upon removal of their ear plugs, these owls exhibited large systematic sound localization errors. The rate at which they recovered accurate localization decreased with the age of the bird at the time of plug removal, and recovery essentially ceased when owls reached 38 to 42 weeks of age. We interpret this age as the end of a critical period for the consolidation of associations between auditory cues and locations in space. Owls that had experienced adult localization cues for a short period of time before ear plugging recovered normal accuracy rapidly, even if they remained plugged well past the end of the critical period. This suggests that a brief exposure to normal adult cues early in the critical period is sufficient to enable the recovery of localization accuracy much later in life.

  17. Towards the GEOSAT Follow-On Precise Orbit Determination Goals of High Accuracy and Near-Real-Time Processing

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank G.; Zelensky, Nikita P.; Chinn, Douglas S.; Beckley, Brian D.; Lillibridge, John L.

    2006-01-01

    The US Navy's GEOSAT Follow-On spacecraft (GFO) primary mission objective is to map the oceans using a radar altimeter. Satellite laser ranging data, especially in combination with altimeter crossover data, offer the only means of determining high-quality precise orbits. Two tuned gravity models, PGS7727 and PGS7777b, were created at NASA GSFC for GFO that reduce the predicted radial orbit through degree 70 to 13.7 and 10.0 mm. A macromodel was developed to model the nonconservative forces and the SLR spacecraft measurement offset was adjusted to remove a mean bias. Using these improved models, satellite-ranging data, altimeter crossover data, and Doppler data are used to compute both daily medium precision orbits with a latency of less than 24 hours. Final precise orbits are also computed using these tracking data and exported with a latency of three to four weeks to NOAA for use on the GFO Geophysical Data Records (GDR s). The estimated orbit precision of the daily orbits is between 10 and 20 cm, whereas the precise orbits have a precision of 5 cm.

  18. Accuracy And Precision Of Algorithms To Determine The Extent Of Aquatic Plants: Empirical Scaling Of Spectral Indices Vs. Spectral Unmixing

    NASA Astrophysics Data System (ADS)

    Cheruiyot, E.; Menenti, M.; Gorte, B.; Mito, C.; Koenders, R.

    2013-12-01

    Assessing the accuracy of image classification results is an important but often neglected step. Accuracy information is necessary in assessing the reliability of map products, hence neglecting this step renders the products unusable. With a classified Landsat-7 TM image as reference, we assessed the accuracy of NDVI and linear spectral unmixing (LSU) in vegetation detection from 20 randomly selected MERIS sample pixels in the Winam Gulf section of Lake Victoria. We noted that though easy to compute, empirical scaling of NDVI is not suitable for quantitative estimation of vegetation cover as it is misleading and often omits useful information. LSU performed at 87% based on RMSE. For quick solutions, we propose the use of a conversion factor from NDVI to vegetation fractional abundance (FA). With this conversion which is 96% reliable, the resulting FA from our samples were classified at 84% accuracy, only 3% less than those directly computed using LSU.

  19. Validation Test Report for NFLUX PRE: Validation of Specific Humidity, Surface Air Temperature, and Wind Speed Precision and Accuracy for Assimilation into Global and Regional Models

    DTIC Science & Technology

    2014-04-02

    Test Report for NFLUX PRE: Validation of Specific Humidity, Surface Air Temperature, and Wind Speed Precision and Accuracy for Assimilation into...THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Validation Test Report for NFLUX PRE: Validation of Specific Humidity, Surface Air...The regional algorithm products overlay the existing global product estimate. The location of the observations is tested to see if it falls within one

  20. Accuracy and precision of a custom camera-based system for 2D and 3D motion tracking during speech and nonspeech motor tasks

    PubMed Central

    Feng, Yongqiang; Max, Ludo

    2014-01-01

    Purpose Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories, and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable alternative, provided that they offer high temporal resolution and sub-millimeter accuracy. Method We examined the accuracy and precision of 2D and 3D data recorded with a system that combines consumer-grade digital cameras capturing 60, 120, or 240 frames per second (fps), retro-reflective markers, commercially-available computer software (APAS, Ariel Dynamics), and a custom calibration device. Results Overall mean error (RMSE) across tests was 0.15 mm for static tracking and 0.26 mm for dynamic tracking, with corresponding precision (SD) values of 0.11 and 0.19 mm, respectively. The effect of frame rate varied across conditions, but, generally, accuracy was reduced at 240 fps. The effect of marker size (3 vs. 6 mm diameter) was negligible at all frame rates for both 2D and 3D data. Conclusion Motion tracking with consumer-grade digital cameras and the APAS software can achieve sub-millimeter accuracy at frame rates that are appropriate for kinematic analyses of lip/jaw movements for both research and clinical purposes. PMID:24686484

  1. Accuracy and precision of a custom camera-based system for 2-d and 3-d motion tracking during speech and nonspeech motor tasks.

    PubMed

    Feng, Yongqiang; Max, Ludo

    2014-04-01

    PURPOSE Studying normal or disordered motor control requires accurate motion tracking of the effectors (e.g., orofacial structures). The cost of electromagnetic, optoelectronic, and ultrasound systems is prohibitive for many laboratories and limits clinical applications. For external movements (lips, jaw), video-based systems may be a viable alternative, provided that they offer high temporal resolution and submillimeter accuracy. METHOD The authors examined the accuracy and precision of 2-D and 3-D data recorded with a system that combines consumer-grade digital cameras capturing 60, 120, or 240 frames per second (fps), retro-reflective markers, commercially available computer software (APAS, Ariel Dynamics), and a custom calibration device. RESULTS Overall root-mean-square error (RMSE) across tests was 0.15 mm for static tracking and 0.26 mm for dynamic tracking, with corresponding precision (SD) values of 0.11 and 0.19 mm, respectively. The effect of frame rate varied across conditions, but, generally, accuracy was reduced at 240 fps. The effect of marker size (3- vs. 6-mm diameter) was negligible at all frame rates for both 2-D and 3-D data. CONCLUSION Motion tracking with consumer-grade digital cameras and the APAS software can achieve submillimeter accuracy at frame rates that are appropriate for kinematic analyses of lip/jaw movements for both research and clinical purposes.

  2. 40 CFR 80.584 - What are the precision and accuracy criteria for approval of test methods for determining the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... diesel fuel, and ECA marine fuel? 80.584 Section 80.584 Protection of Environment ENVIRONMENTAL... Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Sampling and Testing § 80... sulfur content of motor vehicle diesel fuel, NRLM diesel fuel, and ECA marine fuel? (a) Precision....

  3. Study of the Effect of Modes of Electroerosion Treatment on the Microstructure and Accuracy of Precision Sizes of Small Parts

    NASA Astrophysics Data System (ADS)

    Korobova, N. V.; Aksenenko, A. Yu.; Bashevskaya, O. S.; Nikitin, A. A.

    2016-01-01

    Results of a study of the effect of the parameters of electroerosion treatment in a GF Agie Charmilles CUT 1000 OilTech wire-cutting bench on the size accuracy, the quality of the surface layer of cuts, and the microstructure of the surface of the treated parts are presented.

  4. Recovery of Precision Grasping after Motor Cortex Lesion does not require Forced use of the Impaired Hand in Macaca mulatta

    PubMed Central

    Darling, Warren G.; Morecraft, Robert J.; Rotella, Diane L.; Pizzimenti, Marc A.; Ge, Jizhi; Stilwell-Morecraft, Kimberly S.; Zhang, Hongyu; Soliman, Hesham; Seecharan, Dave; Edwards, Ian; McNeal, David; Nudo, Randolph J.; Cheney, Paul

    2014-01-01

    We investigated whether precision grasping of small objects between the index and thumb of the impaired hand recovers without forced use after surgically placed lesions to the hand/arm areas of M1 and M1 + lateral premotor cortex (LPMC) in two monkeys. The unilateral lesions were contralateral to the monkey's preferred hand, which was established in pre-lesion testing as the hand used most often to acquire raisins in a foraging board task in which the monkey was free to use either hand to acquire the treats. The lesions initially produced a clear paresis of the contralesional hand and use of only the ipsilesional hand to acquire raisins in the foraging board task. However, beginning about 3 weeks after the lesion the monkey spontaneously began using the impaired contralesional hand in the foraging board task and increased use of that hand over the next few tests. Moreover, the monkeys clearly used precision grasp to acquire the raisins in a similar manner to pre-lesion performances, although grasp durations were longer. Although the monkeys used the contralesional hand more often than the ipsilesional hand in some post-lesion testing sessions they did not recover to use the hand as often as in pre-lesion testing when the preferred hand was used almost exclusively. These findings suggest that recovery of fine hand/digit motor function after localized damage to the lateral frontal motor areas in rhesus monkeys does not require forced use of the impaired hand. PMID:25163672

  5. Optimizing the accuracy and precision of the single-pulse Laue technique for synchrotron photo-crystallography

    PubMed Central

    Kamiński, Radosław; Graber, Timothy; Benedict, Jason B.; Henning, Robert; Chen, Yu-Sheng; Scheins, Stephan; Messerschmidt, Marc; Coppens, Philip

    2010-01-01

    The accuracy that can be achieved in single-pulse pump-probe Laue experiments is discussed. It is shown that with careful tuning of the experimental conditions a reproducibility of the intensity ratios of equivalent intensities obtained in different measurements of 3–4% can be achieved. The single-pulse experiments maximize the time resolution that can be achieved and, unlike stroboscopic techniques in which the pump-probe cycle is rapidly repeated, minimize the temperature increase due to the laser exposure of the sample. PMID:20567080

  6. Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique

    PubMed Central

    Kim, Jae-Hong; Kim, Ki-Baek; Kim, Woong-Chul; Kim, Ji-Hwan

    2014-01-01

    Objective This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. Methods Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability. Results The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. Conclusions The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models. PMID:24696823

  7. Analysis of the accuracy and precision of the Axis-Shield Afinion hemoglobin A1c measurement device.

    PubMed

    Little, Randie R

    2012-03-01

    Point-of-care (POC) hemoglobin A1c measurement is now used by many physicians to make more timely decisions on therapy changes. A few studies have highlighted the drawbacks of some POC methods, e.g., poor precision and lot-to-lot variability. Evaluating performance in the clinical setting is difficult because there is minimal proficiency testing data on POC methods. In this issue of Journal of Diabetes Science and Technology, Wood and colleagues describe their experience with the Afinion method in a pediatric clinic network, comparing these results to another POC method as well as to a laboratory high-performance liquid chromatography method. Although they conclude that the Afinion exhibits adequate performance, they do not evaluate lot-to-lot variability. As with laboratory methods, potential assay interferences must also be considered.

  8. Quantitative Thin-Film X-ray Microanalysis by STEM/HAADF: Statistical Analysis for Precision and Accuracy Determination

    NASA Astrophysics Data System (ADS)

    Armigliato, Aldo; Balboni, Roberto; Rosa, Rodolfo

    2006-07-01

    Silicon-germanium thin films have been analyzed by EDS microanalysis in a field emission gun scanning transmission electron microscope (FEG-STEM) equipped with a high angular dark-field detector (STEM/HAADF). Several spectra have been acquired in the same homogeneous area of the cross-sectioned sample by drift-corrected linescan acquisitions. The Ge concentrations and the local film thickness have been obtained by using a previously described Monte Carlo based “two tilt angles” method. Although the concentrations are in excellent agreement with the known values, the resulting confidence intervals are not as good as expected from the precision in beam positioning and tilt angle position and readout offered by our state-of-the-art microscope. The Gaussian shape of the SiK[alpha] and GeK[alpha] X-ray intensities allows one to use the parametric bootstrap method of statistics, whereby it becomes possible to perform the same quantitative analysis in sample regions of different compositions and thicknesses, but by doing only one measurement at the two angles.

  9. Toward High-precision Seismic Studies of White Dwarf Stars: Parametrization of the Core and Tests of Accuracy

    NASA Astrophysics Data System (ADS)

    Giammichele, N.; Charpinet, S.; Fontaine, G.; Brassard, P.

    2017-01-01

    We present a prescription for parametrizing the chemical profile in the core of white dwarfs in light of the recent discovery that pulsation modes may sometimes be deeply confined in some cool pulsating white dwarfs. Such modes may be used as unique probes of the complicated chemical stratification that results from several processes that occurred in previous evolutionary phases of intermediate-mass stars. This effort is part of our ongoing quest for more credible and realistic seismic models of white dwarfs using static, parametrized equilibrium structures. Inspired by successful techniques developed in design optimization fields (such as aerodynamics), we exploit Akima splines for the tracing of the chemical profile of oxygen (carbon) in the core of a white dwarf model. A series of tests are then presented to better seize the precision and significance of the results that can be obtained in an asteroseismological context. We also show that the new parametrization passes an essential basic test, as it successfully reproduces the chemical stratification of a full evolutionary model.

  10. Leaf vein length per unit area is not intrinsically dependent on image magnification: avoiding measurement artifacts for accuracy and precision.

    PubMed

    Sack, Lawren; Caringella, Marissa; Scoffoni, Christine; Mason, Chase; Rawls, Michael; Markesteijn, Lars; Poorter, Lourens

    2014-10-01

    Leaf vein length per unit leaf area (VLA; also known as vein density) is an important determinant of water and sugar transport, photosynthetic function, and biomechanical support. A range of software methods are in use to visualize and measure vein systems in cleared leaf images; typically, users locate veins by digital tracing, but recent articles introduced software by which users can locate veins using thresholding (i.e. based on the contrasting of veins in the image). Based on the use of this method, a recent study argued against the existence of a fixed VLA value for a given leaf, proposing instead that VLA increases with the magnification of the image due to intrinsic properties of the vein system, and recommended that future measurements use a common, low image magnification for measurements. We tested these claims with new measurements using the software LEAFGUI in comparison with digital tracing using ImageJ software. We found that the apparent increase of VLA with magnification was an artifact of (1) using low-quality and low-magnification images and (2) errors in the algorithms of LEAFGUI. Given the use of images of sufficient magnification and quality, and analysis with error-free software, the VLA can be measured precisely and accurately. These findings point to important principles for improving the quantity and quality of important information gathered from leaf vein systems.

  11. Anthropometric precision and accuracy of digital three-dimensional photogrammetry: comparing the Genex and 3dMD imaging systems with one another and with direct anthropometry.

    PubMed

    Weinberg, Seth M; Naidoo, Sybill; Govier, Daniel P; Martin, Rick A; Kane, Alex A; Marazita, Mary L

    2006-05-01

    A variety of commercially available three-dimensional (3D) surface imaging systems are currently in use by craniofacial specialists. Little is known, however, about how measurement data generated from alternative 3D systems compare, specifically in terms of accuracy and precision. The purpose of this study was to compare anthropometric measurements obtained by way of two different digital 3D photogrammetry systems (Genex and 3dMD) as well as direct anthropometry and to evaluate intraobserver precision across these three methods. On a sample of 18 mannequin heads, 12 linear distances were measured twice by each method. A two-factor repeated measures analysis of variance was used to test simultaneously for mean differences in precision across methods. Additional descriptive statistics (e.g., technical error of measurement [TEM]) were used to quantify measurement error magnitude. Statistically significant (P < 0.05) mean differences were observed across methods for nine anthropometric variables; however, the magnitude of these differences was consistently at the submillimeter level. No significant differences were noted for precision. Moreover, the magnitude of imprecision was determined to be very small, with TEM scores well under 1 mm, and intraclass correlation coefficients ranging from 0.98 to 1. Results indicate that overall mean differences across these three methods were small enough to be of little practical importance. In terms of intraobserver precision, all methods fared equally well. This study is the first attempt to simultaneously compare 3D surface imaging systems directly with one another and with traditional anthropometry. Results suggest that craniofacial surface data obtained by way of alternative 3D photogrammetric systems can be combined or compared statistically.

  12. Accuracy and Precision in the Southern Hemisphere Additional Ozonesondes (SHADOZ) Dataset in Light of the JOSIE-2000 Results

    NASA Technical Reports Server (NTRS)

    Witte, Jacquelyn C.; Thompson, Anne M.; Schmidlin, F. J.; Oltmans, S. J.; Smit, H. G. J.

    2004-01-01

    Since 1998 the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has provided over 2000 ozone profiles over eleven southern hemisphere tropical and subtropical stations. Balloon-borne electrochemical concentration cell (ECC) ozonesondes are used to measure ozone. The data are archived at: &ttp://croc.gsfc.nasa.gov/shadoz>. In analysis of ozonesonde imprecision within the SHADOZ dataset, Thompson et al. [JGR, 108,8238,20031 we pointed out that variations in ozonesonde technique (sensor solution strength, instrument manufacturer, data processing) could lead to station-to-station biases within the SHADOZ dataset. Imprecisions and accuracy in the SHADOZ dataset are examined in light of new data. First, SHADOZ total ozone column amounts are compared to version 8 TOMS (2004 release). As for TOMS version 7, satellite total ozone is usually higher than the integrated column amount from the sounding. Discrepancies between the sonde and satellite datasets decline two percentage points on average, compared to version 7 TOMS offsets. Second, the SHADOZ station data are compared to results of chamber simulations (JOSE-2000, Juelich Ozonesonde Intercomparison Experiment) in which the various SHADOZ techniques were evaluated. The range of JOSE column deviations from a standard instrument (-10%) in the chamber resembles that of the SHADOZ station data. It appears that some systematic variations in the SHADOZ ozone record are accounted for by differences in solution strength, data processing and instrument type (manufacturer).

  13. Charts of operational process specifications ("OPSpecs charts") for assessing the precision, accuracy, and quality control needed to satisfy proficiency testing performance criteria.

    PubMed

    Westgard, J O

    1992-07-01

    "Operational process specifications" have been derived from an analytical quality-planning model to assess the precision, accuracy, and quality control (QC) needed to satisfy Proficiency Testing (PT) criteria. These routine operating specifications are presented in the form of an "OPSpecs chart," which describes the operational limits for imprecision and inaccuracy when a desired level of quality assurance is provided by a specific QC procedure. OPSpecs charts can be used to compare the operational limits for different QC procedures and to select a QC procedure that is appropriate for the precision and accuracy of a specific measurement procedure. To select a QC procedure, one plots the inaccuracy and imprecision observed for a measurement procedure on the OPSpecs chart to define the current operating point, which is then compared with the operational limits of candidate QC procedures. Any QC procedure whose operational limits are greater than the measurement procedure's operating point will provide a known assurance, with the percent chance specified by the OPSpecs chart, that critical analytical errors will be detected. OPSpecs charts for a 10% PT criterion are presented to illustrate the selection of QC procedures for measurement procedures with different amounts of imprecision and inaccuracy. Normalized OPSpecs charts are presented to permit a more general assessment of the analytical performance required with commonly used QC procedures.

  14. TanDEM-X IDEM precision and accuracy assessment based on a large assembly of differential GNSS measurements in Kruger National Park, South Africa

    NASA Astrophysics Data System (ADS)

    Baade, J.; Schmullius, C.

    2016-09-01

    High resolution Digital Elevation Models (DEM) represent fundamental data for a wide range of Earth surface process studies. Over the past years, the German TanDEM-X mission acquired data for a new, truly global Digital Elevation Model with unprecedented geometric resolution, precision and accuracy. First TanDEM Intermediate Digital Elevation Models (i.e. IDEM) with a geometric resolution from 0.4 to 3 arcsec have been made available for scientific purposes in November 2014. This includes four 1° × 1° tiles covering the Kruger National Park in South Africa. Here, we document the results of a local scale IDEM height accuracy validation exercise utilizing over 10,000 RTK-GNSS-based ground survey points from fourteen sites characterized by mainly pristine Savanna vegetation. The vertical precision of the ground checkpoints is 0.02 m (1σ). Selected precursor data sets (SRTMGL1, SRTM41, ASTER-GDEM2) are included in the analysis to facilitate the comparison. Although IDEM represents an intermediate product on the way to the new global TanDEM-X DEM, expected to be released in late 2016, it allows first insight into the properties of the forthcoming product. Remarkably, the TanDEM-X tiles include a number of auxiliary files providing detailed information pertinent to a user-based quality assessment. We present examples for the utilization of this information in the framework of a local scale study including the identification of height readings contaminated by water. Furthermore, this study provides evidence for the high precision and accuracy of IDEM height readings and the sensitivity to canopy cover. For open terrain, the 0.4 arcsec resolution edition (IDEM04) yields an average bias of 0.20 ± 0.05 m (95% confidence interval, Cl95), a RMSE = 1.03 m and an absolute vertical height error (LE90) of 1.5 [1.4, 1.7] m (Cl95). The corresponding values for the lower resolution IDEM editions are about the same and provide evidence for the high quality of the IDEM products

  15. Evaluating precision and accuracy when quantifying different endogenous control reference genes in maize using real-time PCR.

    PubMed

    Scholdberg, Tandace A; Norden, Tim D; Nelson, Daishia D; Jenkins, G Ronald

    2009-04-08

    The agricultural biotechnology industry routinely utilizes real-time quantitative PCR (RT-qPCR) for the detection of biotechnology-derived traits in plant material, particularly for meeting the requirements of legislative mandates that rely upon the trace detection of DNA. Quantification via real-time RT-qPCR in plant species involves the measurement of the copy number of a taxon-specific, endogenous control gene exposed to the same manipulations as the target gene prior to amplification. The International Organization for Standardization (ISO 21570:2005) specifies that the copy number of an endogenous reference gene be used for normalizing the concentration (expressed as a % w/w) of a trait-specific target gene when using RT-qPCR. For this purpose, the copy number of a constitutively expressed endogenous reference gene in the same sample is routinely monitored. Real-time qPCR was employed to evaluate the predictability and performance of commonly used endogenous control genes (starch synthase, SSIIb-2, SSIIb-3; alcohol dehydrogenase, ADH; high-mobility group, HMG; zein; and invertase, IVR) used to detect biotechnology-derived traits in maize. The data revealed relatively accurate and precise amplification efficiencies when isogenic maize was compared to certified reference standards, but highly variable results when 23 nonisogenic maize cultivars were compared to an IRMM Bt-11 reference standard. Identifying the most suitable endogenous control gene, one that amplifies consistently and predictably across different maize cultivars, and implementing this as an internationally recognized standard would contribute toward harmonized testing of biotechnology-derived traits in maize.

  16. EFFECT OF RADIATION DOSE LEVEL ON ACCURACY AND PRECISION OF MANUAL SIZE MEASUREMENTS IN CHEST TOMOSYNTHESIS EVALUATED USING SIMULATED PULMONARY NODULES

    PubMed Central

    Söderman, Christina; Johnsson, Åse Allansdotter; Vikgren, Jenny; Norrlund, Rauni Rossi; Molnar, David; Svalkvist, Angelica; Månsson, Lars Gunnar; Båth, Magnus

    2016-01-01

    The aim of the present study was to investigate the dependency of the accuracy and precision of nodule diameter measurements on the radiation dose level in chest tomosynthesis. Artificial ellipsoid-shaped nodules with known dimensions were inserted in clinical chest tomosynthesis images. Noise was added to the images in order to simulate radiation dose levels corresponding to effective doses for a standard-sized patient of 0.06 and 0.04 mSv. These levels were compared with the original dose level, corresponding to an effective dose of 0.12 mSv for a standard-sized patient. Four thoracic radiologists measured the longest diameter of the nodules. The study was restricted to nodules located in high-dose areas of the tomosynthesis projection radiographs. A significant decrease of the measurement accuracy and intraobserver variability was seen for the lowest dose level for a subset of the observers. No significant effect of dose level on the interobserver variability was found. The number of non-measurable small nodules (≤5 mm) was higher for the two lowest dose levels compared with the original dose level. In conclusion, for pulmonary nodules at positions in the lung corresponding to locations in high-dose areas of the projection radiographs, using a radiation dose level resulting in an effective dose of 0.06 mSv to a standard-sized patient may be possible in chest tomosynthesis without affecting the accuracy and precision of nodule diameter measurements to any large extent. However, an increasing number of non-measurable small nodules (≤5 mm) with decreasing radiation dose may raise some concerns regarding an applied general dose reduction for chest tomosynthesis examinations in the clinical praxis. PMID:26994093

  17. Effects of Recovery Behavior and Strain-Rate Dependence of Stress-Strain Curve on Prediction Accuracy of Thermal Stress Analysis During Casting

    NASA Astrophysics Data System (ADS)

    Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto

    2017-03-01

    Recovery behavior (recovery) and strain-rate dependence of the stress-strain curve (strain-rate dependence) are incorporated into constitutive equations of alloys to predict residual stress and thermal stress during casting. Nevertheless, few studies have systematically investigated the effects of these metallurgical phenomena on the prediction accuracy of thermal stress in a casting. This study compares the thermal stress analysis results with in situ thermal stress measurement results of an Al-Si-Cu specimen during casting. The results underscore the importance for the alloy constitutive equation of incorporating strain-rate dependence to predict thermal stress that develops at high temperatures where the alloy shows strong strain-rate dependence of the stress-strain curve. However, the prediction accuracy of the thermal stress developed at low temperatures did not improve by considering the strain-rate dependence. Incorporating recovery into the constitutive equation improved the accuracy of the simulated thermal stress at low temperatures. Results of comparison implied that the constitutive equation should include strain-rate dependence to simulate defects that develop from thermal stress at high temperatures, such as hot tearing and hot cracking. Recovery should be incorporated into the alloy constitutive equation to predict the casting residual stress and deformation caused by the thermal stress developed mainly in the low temperature range.

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

    SciTech Connect

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

    2015-06-15

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

  19. An evaluation of the accuracy and precision of methane prediction equations for beef cattle fed high-forage and high-grain diets.

    PubMed

    Escobar-Bahamondes, P; Oba, M; Beauchemin, K A

    2017-01-01

    The study determined the performance of equations to predict enteric methane (CH4) from beef cattle fed forage- and grain-based diets. Many equations are available to predict CH4 from beef cattle and the predictions vary substantially among equations. The aims were to (1) construct a database of CH4 emissions for beef cattle from published literature, and (2) identify the most precise and accurate extant CH4 prediction models for beef cattle fed diets varying in forage content. The database was comprised of treatment means of CH4 production from in vivo beef studies published from 2000 to 2015. Criteria to include data in the database were as follows: animal description, intakes, diet composition and CH4 production. In all, 54 published equations that predict CH4 production from diet composition were evaluated. Precision and accuracy of the equations were evaluated using the concordance correlation coefficient (r c ), root mean square prediction error (RMSPE), model efficiency and analysis of errors. Equations were ranked using a combined index of the various statistical assessments based on principal component analysis. The final database contained 53 studies and 207 treatment means that were divided into two data sets: diets containing ⩾400 g/kg dry matter (DM) forage (n=116) and diets containing ⩽200 g/kg DM forage (n=42). Diets containing between ⩽400 and ⩾200 g/kg DM forage were not included in the analysis because of their limited numbers (n=6). Outliers, treatment means where feed was fed restrictively and diets with CH4 mitigation additives were omitted (n=43). Using the high-forage dataset the best-fit equations were the International Panel on Climate Change Tier 2 method, 3 equations for steers that considered gross energy intake (GEI) and body weight and an equation that considered dry matter intake and starch:neutral detergent fiber with r c ranging from 0.60 to 0.73 and RMSPE from 35.6 to 45.9 g/day. For the high-grain diets, the 5 best

  20. Recovery

    NASA Video Gallery

    This video discusses the recovery events that occur in high-power rocketry and the various devices used in safely recovering the rocket. The video includes a discussion of black powder and ejection...

  1. In situ sulfur isotope analysis of sulfide minerals by SIMS: Precision and accuracy, with application to thermometry of ~3.5Ga Pilbara cherts

    USGS Publications Warehouse

    Kozdon, R.; Kita, N.T.; Huberty, J.M.; Fournelle, J.H.; Johnson, C.A.; Valley, J.W.

    2010-01-01

    Secondary ion mass spectrometry (SIMS) measurement of sulfur isotope ratios is a potentially powerful technique for in situ studies in many areas of Earth and planetary science. Tests were performed to evaluate the accuracy and precision of sulfur isotope analysis by SIMS in a set of seven well-characterized, isotopically homogeneous natural sulfide standards. The spot-to-spot and grain-to-grain precision for δ34S is ± 0.3‰ for chalcopyrite and pyrrhotite, and ± 0.2‰ for pyrite (2SD) using a 1.6 nA primary beam that was focused to 10 µm diameter with a Gaussian-beam density distribution. Likewise, multiple δ34S measurements within single grains of sphalerite are within ± 0.3‰. However, between individual sphalerite grains, δ34S varies by up to 3.4‰ and the grain-to-grain precision is poor (± 1.7‰, n = 20). Measured values of δ34S correspond with analysis pit microstructures, ranging from smooth surfaces for grains with high δ34S values, to pronounced ripples and terraces in analysis pits from grains featuring low δ34S values. Electron backscatter diffraction (EBSD) shows that individual sphalerite grains are single crystals, whereas crystal orientation varies from grain-to-grain. The 3.4‰ variation in measured δ34S between individual grains of sphalerite is attributed to changes in instrumental bias caused by different crystal orientations with respect to the incident primary Cs+ beam. High δ34S values in sphalerite correlate to when the Cs+ beam is parallel to the set of directions , from [111] to [110], which are preferred directions for channeling and focusing in diamond-centered cubic crystals. Crystal orientation effects on instrumental bias were further detected in galena. However, as a result of the perfect cleavage along {100} crushed chips of galena are typically cube-shaped and likely to be preferentially oriented, thus crystal orientation effects on instrumental bias may be obscured. Test were made to improve the analytical

  2. An in-depth evaluation of accuracy and precision in Hg isotopic analysis via pneumatic nebulization and cold vapor generation multi-collector ICP-mass spectrometry.

    PubMed

    Rua-Ibarz, Ana; Bolea-Fernandez, Eduardo; Vanhaecke, Frank

    2016-01-01

    Mercury (Hg) isotopic analysis via multi-collector inductively coupled plasma (ICP)-mass spectrometry (MC-ICP-MS) can provide relevant biogeochemical information by revealing sources, pathways, and sinks of this highly toxic metal. In this work, the capabilities and limitations of two different sample introduction systems, based on pneumatic nebulization (PN) and cold vapor generation (CVG), respectively, were evaluated in the context of Hg isotopic analysis via MC-ICP-MS. The effect of (i) instrument settings and acquisition parameters, (ii) concentration of analyte element (Hg), and internal standard (Tl)-used for mass discrimination correction purposes-and (iii) different mass bias correction approaches on the accuracy and precision of Hg isotope ratio results was evaluated. The extent and stability of mass bias were assessed in a long-term study (18 months, n = 250), demonstrating a precision ≤0.006% relative standard deviation (RSD). CVG-MC-ICP-MS showed an approximately 20-fold enhancement in Hg signal intensity compared with PN-MC-ICP-MS. For CVG-MC-ICP-MS, the mass bias induced by instrumental mass discrimination was accurately corrected for by using either external correction in a sample-standard bracketing approach (SSB) or double correction, consisting of the use of Tl as internal standard in a revised version of the Russell law (Baxter approach), followed by SSB. Concomitant matrix elements did not affect CVG-ICP-MS results. Neither with PN, nor with CVG, any evidence for mass-independent discrimination effects in the instrument was observed within the experimental precision obtained. CVG-MC-ICP-MS was finally used for Hg isotopic analysis of reference materials (RMs) of relevant environmental origin. The isotopic composition of Hg in RMs of marine biological origin testified of mass-independent fractionation that affected the odd-numbered Hg isotopes. While older RMs were used for validation purposes, novel Hg isotopic data are provided for the

  3. Accuracy and precision of 88Sr/86Sr and 87Sr/86Sr measurements by MC-ICPMS compromised by high barium concentrations

    NASA Astrophysics Data System (ADS)

    Scher, Howie D.; Griffith, Elizabeth M.; Buckley, Wayne P.

    2014-02-01

    (BaSO4) is a widely distributed mineral that incorporates strontium (Sr) during formation. Mass-dependent fractionation of Sr isotopes occurs during abiotic precipitation of barite and formation of barite associated with biological processes (e.g., bacterial sulfide oxidation). Sr isotopes in barite can provide provenance information as well as potentially reconstruct sample formation conditions (e.g., saturation state, temperature, biotic versus abiotic). Incomplete separation of Ba from Sr has complicated measurements of Sr isotopes by MC-ICPMS. In this study, we tested the effects of Ba in Sr sample solutions and modified extraction chromatography of Sr using Eichrom Sr Spec (Eichrom Technologies LLC, USA) resin to enable rapid, accurate, and precise measurements of 88Sr/86Sr and 87Sr/86Sr ratios from Ba-rich matrices. Sr isotope ratios of sample solutions doped with Ba were statistically indistinguishable from Ba-free sample solutions below 1 ppm Ba. Deviations in both 87Sr/86Sr and δ88/86Sr occurred above 1 ppm Ba. An updated extraction chromatography method tested with barite and Ba-doped seawater produces Sr sample solutions containing 10-100 ppb levels of Ba. The practice of Zr spiking for external mass-discrimination correction of 88Sr/86Sr ratios was also evaluated, and it was confirmed that variable Zr levels do not have adverse effects on the accuracy and precision of 87Sr/86Sr ratios in the Zr concentration range required to produce accurate δ88/86Sr values.

  4. Functional limits of agreement applied as a novel method comparison tool for accuracy and precision of inertial measurement unit derived displacement of the distal limb in horses.

    PubMed

    Olsen, Emil; Pfau, Thilo; Ritz, Christian

    2013-09-03

    Over ground motion analysis in horses is limited by a small number of strides and restraints of the indoor gait laboratory. Inertial measurement units (IMUs) are transforming the knowledge of human motion and objective clinical assessment through the opportunity to obtain clinically relevant data under various conditions. When using IMUs on the limbs of horses to determine local position estimates, conditions with high dynamic range of both accelerations and rotational velocities prove particularly challenging. Here we apply traditional method agreement and suggest a novel method of functional data analysis to compare motion capture with IMUs placed over the fetlock joint in seven horses. We demonstrate acceptable accuracy and precision at less than or equal to 5% of the range of motion for detection of distal limb mounted cranio-caudal and vertical position. We do not recommend the use of the latero-medial position estimate of the distal metacarpus/metatarsus during walk where the average error is 10% and the maximum error 111% of the range. We also show that functional data analysis and functional limits of agreement are sensitive methods for comparison of cyclical data and could be applied to differentiate changes in gait for individuals across time and conditions.

  5. Performing elemental microanalysis with high accuracy and high precision by scanning electron microscopy/silicon drift detector energy-dispersive X-ray spectrometry (SEM/SDD-EDS).

    PubMed

    Newbury, Dale E; Ritchie, Nicholas W M

    Electron-excited X-ray microanalysis performed in the scanning electron microscope with energy-dispersive X-ray spectrometry (EDS) is a core technique for characterization of the microstructure of materials. The recent advances in EDS performance with the silicon drift detector (SDD) enable accuracy and precision equivalent to that of the high spectral resolution wavelength-dispersive spectrometer employed on the electron probe microanalyzer platform. SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2. Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041). Accurate analyses of low atomic number elements, C, N, O, and F, are demonstrated. Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.

  6. Using Global Analysis to Extend the Accuracy and Precision of Binding Measurements with T cell Receptors and Their Peptide/MHC Ligands

    PubMed Central

    Blevins, Sydney J.; Baker, Brian M.

    2017-01-01

    In cellular immunity, clonally distributed T cell receptors (TCRs) engage complexes of peptides bound to major histocompatibility complex proteins (pMHCs). In the interactions of TCRs with pMHCs, regions of restricted and variable diversity align in a structurally complex fashion. Many studies have used mutagenesis to attempt to understand the “roles” played by various interface components in determining TCR recognition properties such as specificity and cross-reactivity. However, these measurements are often complicated or even compromised by the weak affinities TCRs maintain toward pMHC. Here, we demonstrate how global analysis of multiple datasets can be used to significantly extend the accuracy and precision of such TCR binding experiments. Application of this approach should positively impact efforts to understand TCR recognition and facilitate the creation of mutational databases to help engineer TCRs with tuned molecular recognition properties. We also show how global analysis can be used to analyze double mutant cycles in TCR-pMHC interfaces, which can lead to new insights into immune recognition. PMID:28197404

  7. High-Precision Surface Inspection: Uncertainty Evaluation within an Accuracy Range of 15μm with Triangulation-based Laser Line Scanners

    NASA Astrophysics Data System (ADS)

    Dupuis, Jan; Kuhlmann, Heiner

    2014-06-01

    Triangulation-based range sensors, e.g. laser line scanners, are used for high-precision geometrical acquisition of free-form surfaces, for reverse engineering tasks or quality management. In contrast to classical tactile measuring devices, these scanners generate a great amount of 3D-points in a short period of time and enable the inspection of soft materials. However, for accurate measurements, a number of aspects have to be considered to minimize measurement uncertainties. This study outlines possible sources of uncertainties during the measurement process regarding the scanner warm-up, the impact of laser power and exposure time as well as scanner’s reaction to areas of discontinuity, e.g. edges. All experiments were performed using a fixed scanner position to avoid effects resulting from imaging geometry. The results show a significant dependence of measurement accuracy on the correct adaption of exposure time as a function of surface reflectivity and laser power. Additionally, it is illustrated that surface structure as well as edges can cause significant systematic uncertainties.

  8. Technical Note: Precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index

    SciTech Connect

    Vrieze, Thomas J.; Sturchio, Glenn M.; McCollough, Cynthia H.

    2012-11-15

    Purpose: To determine the precision and accuracy of CTDI{sub 100} measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. Methods: One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements were made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI{sub 100}. Results: The mean precision averaged over 28 datasets containing five measurements each was 1.4%{+-} 0.6%, range = 0.6%-2.7% for OSL and 0.08%{+-} 0.06%, range = 0.02%-0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI{sub 100} values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI{sub 100} relative to the ion chamber 21/28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Conclusions: Measurements of CTDI{sub 100} with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI{sub 100} values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile.

  9. Results from a round-robin study assessing the precision and accuracy of LA-ICPMS U/Pb geochronology of zircon

    NASA Astrophysics Data System (ADS)

    Hanchar, J. M.

    2009-12-01

    A round-robin study was undertaken to assess the current state of precision and accuracy that can be achieved in LA-ICPMS U/Pb geochronology of zircon. The initial plan was to select abundant, well-characterized zircon samples to distribute to participants in the study. Three suitable samples were found, evaluated, and dated using ID-TIMS. Twenty-five laboratories in North America and Europe were asked to participate in the study. Eighteen laboratories agreed to participate, of which seventeen submitted final results. It was decided at the outset of the project that the identities of the participating researchers and laboratories not be revealed until the manuscript stemming from the project was completed. Participants were sent either fragments of zircon crystal or whole zircon crystals, selected randomly after being thoroughly mixed. Participants were asked to conform to specific requirements. These include providing all analytical conditions and equipment used, submission of all data acquired, and submitting their preferred data and preferred ages for the three samples. The participating researchers used a wide range of analytical methods (e.g., instrumentation, data reduction, error propagation) for the LA-ICPMS U/Th geochronology. These combined factors made it difficult for direct comparison of the results that were submitted. Most of the LA-ICPMS results submitted were within 2% r.s.d. of the ID-TIMS values for the three samples in the study. However, the error bars for the majority of the LA-ICPMS results for the three samples did not overlap with the ID-TIMS results. These results suggest a general underestimation of the errors calculated for the LA-ICPMS analyses U/Pb zircon analyses.

  10. The 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Tropical Ozone Climatology: Ozonesonde Precision, Accuracy and Station-to-Station Variability

    NASA Technical Reports Server (NTRS)

    Witte, J. C.; Thompson, Anne M.; McPeters, R. D.; Oltmans, S. J.; Schmidlin, F. J.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    As part of the SAFARI-2000 campaign, additional launches of ozonesondes were made at Irene, South Africa and at Lusaka, Zambia. These represent campaign augmentations to the SHADOZ database described in this paper. This network of 10 southern hemisphere tropical and subtropical stations, designated the Southern Hemisphere ADditional OZonesondes (SHADOZ) project and established from operational sites, provided over 1000 profiles from ozonesondes and radiosondes during the period 1998-2000. (Since that time, two more stations, one in southern Africa, have joined SHADOZ). Archived data are available at: http://code9l6.gsfc.nasa.gov/Data-services/shadoz>. Uncertainties and accuracies within the SHADOZ ozone data set are evaluated by analyzing: (1) imprecisions in stratospheric ozone profiles and in methods of extrapolating ozone above balloon burst; (2) comparisons of column-integrated total ozone from sondes with total ozone from the Earth-Probe/TOMS (Total Ozone Mapping Spectrometer) satellite and ground-based instruments; (3) possible biases from station-to-station due to variations in ozonesonde characteristics. The key results are: (1) Ozonesonde precision is 5%; (2) Integrated total ozone column amounts from the sondes are in good agreement (2-10%) with independent measurements from ground-based instruments at five SHADOZ sites and with overpass measurements from the TOMS satellite (version 7 data). (3) Systematic variations in TOMS-sonde offsets and in groundbased-sonde offsets from station to station reflect biases in sonde technique as well as in satellite retrieval. Discrepancies are present in both stratospheric and tropospheric ozone. (4) There is evidence for a zonal wave-one pattern in total and tropospheric ozone, but not in stratospheric ozone.

  11. Two dimensional assisted liquid chromatography - a chemometric approach to improve accuracy and precision of quantitation in liquid chromatography using 2D separation, dual detectors, and multivariate curve resolution.

    PubMed

    Cook, Daniel W; Rutan, Sarah C; Stoll, Dwight R; Carr, Peter W

    2015-02-15

    Comprehensive two-dimensional liquid chromatography (LC×LC) is rapidly evolving as the preferred method for the analysis of complex biological samples owing to its much greater resolving power compared to conventional one-dimensional (1D-LC). While its enhanced resolving power makes this method appealing, it has been shown that the precision of quantitation in LC×LC is generally not as good as that obtained with 1D-LC. The poorer quantitative performance of LC×LC is due to several factors including but not limited to the undersampling of the first dimension and the dilution of analytes during transit from the first dimension ((1)D) column to the second dimension ((2)D) column, and the larger relative background signals. A new strategy, 2D assisted liquid chromatography (2DALC), is presented here. 2DALC makes use of a diode array detector placed at the end of each column, producing both multivariate (1)D and two-dimensional (2D) chromatograms. The increased resolution of the analytes provided by the addition of a second dimension of separation enables the determination of analyte absorbance spectra from the (2)D detector signal that are relatively pure and can be used to initiate the treatment of data from the first dimension detector using multivariate curve resolution-alternating least squares (MCR-ALS). In this way, the approach leverages the strengths of both separation methods in a single analysis: the (2)D detector data is used to provide relatively pure analyte spectra to the MCR-ALS algorithm, and the final quantitative results are obtained from the resolved (1)D chromatograms, which has a much higher sampling rate and lower background signal than obtained in conventional single detector LC×LC, to obtain accurate and precise quantitative results. It is shown that 2DALC is superior to both single detector selective or comprehensive LC×LC and 1D-LC for quantitation of compounds that appear as severely overlapped peaks in the (1)D chromatogram - this is

  12. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y.-L.; Szidat, S.; Czimczik, C. I.

    2015-09-01

    Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small sample sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal-optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to a vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average, 91 % of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our setup, we quantified the total amount of extraneous carbon introduced during the TOA sample processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of sample size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) samples with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our setup were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively

  13. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y. L.; Szidat, S.; Czimczik, C. I.

    2015-04-01

    Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small sample sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal-optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average 91% of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our set-up, we quantified the total amount of extraneous carbon introduced during the TOA sample processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of sample size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) samples with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our set-up were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively

  14. Prognosis for recovery from multiple organ system failure: the accuracy of objective estimates of chances for survival. The French Multicentric Group of ICU Research.

    PubMed

    Rauss, A; Knaus, W A; Patois, E; Le Gall, J R; Loirat, P

    1990-01-01

    This study evaluated the accuracy and reliability of predictions for recovery from multiple organ system failure (OSF). A previous analysis had provided estimates of the probabilities of recovery from various combinations of OSF for 2,843 intensive care unit (ICU) patients treated in 13 U.S. hospitals. These estimates were applied prospectively to 2,405 ICU admissions in 27 French hospitals. Despite variations in the incidences of underlying disease and the distributions of OSF between the two countries, clinical outcomes were similar for the 5,248 total patients. In both countries, two OSFs persisting for more than one day resulted in a hospital death rate of 60%. Hospital mortality rates for patients with three or more OSFs persisting after one day consistently exceeded 90%. Isolated neurologic failure had the poorest overall prognosis, but various other combinations of OSFs did not result in significantly different outcomes. The stability of the prognostic estimates in the two countries suggests that, despite pathogenetic variations, persistent multiple OSF results in consistent clinical outcomes. These mortality projections provide firm reference data for assessing efficacy of new treatments within institutions with similar standards of care. The narrow confidence intervals associated with these estimates also provide objectively defined opportunities to review future treatment plans for individual patients.

  15. Non-Destructive Assay (NDA) Uncertainties Impact on Physical Inventory Difference (ID) and Material Balance Determination: Sources of Error, Precision/Accuracy, and ID/Propagation of Error (POV)

    SciTech Connect

    Wendelberger, James G.

    2016-10-31

    These are slides from a presentation made by a researcher from Los Alamos National Laboratory. The following topics are covered: sources of error for NDA gamma measurements, precision and accuracy are two important characteristics of measurements, four items processed in a material balance area during the inventory time period, inventory difference and propagation of variance, sum in quadrature, and overview of the ID/POV process.

  16. SU-E-J-03: Characterization of the Precision and Accuracy of a New, Preclinical, MRI-Guided Focused Ultrasound System for Image-Guided Interventions in Small-Bore, High-Field Magnets

    SciTech Connect

    Ellens, N; Farahani, K

    2015-06-15

    Purpose: MRI-guided focused ultrasound (MRgFUS) has many potential and realized applications including controlled heating and localized drug delivery. The development of many of these applications requires extensive preclinical work, much of it in small animal models. The goal of this study is to characterize the spatial targeting accuracy and reproducibility of a preclinical high field MRgFUS system for thermal ablation and drug delivery applications. Methods: The RK300 (FUS Instruments, Toronto, Canada) is a motorized, 2-axis FUS positioning system suitable for small bore (72 mm), high-field MRI systems. The accuracy of the system was assessed in three ways. First, the precision of the system was assessed by sonicating regular grids of 5 mm squares on polystyrene plates and comparing the resulting focal dimples to the intended pattern, thereby assessing the reproducibility and precision of the motion control alone. Second, the targeting accuracy was assessed by imaging a polystyrene plate with randomly drilled holes and replicating the hole pattern by sonicating the observed hole locations on intact polystyrene plates and comparing the results. Third, the practicallyrealizable accuracy and precision were assessed by comparing the locations of transcranial, FUS-induced blood-brain-barrier disruption (BBBD) (observed through Gadolinium enhancement) to the intended targets in a retrospective analysis of animals sonicated for other experiments. Results: The evenly-spaced grids indicated that the precision was 0.11 +/− 0.05 mm. When image-guidance was included by targeting random locations, the accuracy was 0.5 +/− 0.2 mm. The effective accuracy in the four rodent brains assessed was 0.8 +/− 0.6 mm. In all cases, the error appeared normally distributed (p<0.05) in both orthogonal axes, though the left/right error was systematically greater than the superior/inferior error. Conclusions: The targeting accuracy of this device is sub-millimeter, suitable for many

  17. Accuracy and precision of pseudo-continuous arterial spin labeling perfusion during baseline and hypercapnia: a head-to-head comparison with ¹⁵O H₂O positron emission tomography.

    PubMed

    Heijtel, D F R; Mutsaerts, H J M M; Bakker, E; Schober, P; Stevens, M F; Petersen, E T; van Berckel, B N M; Majoie, C B L M; Booij, J; van Osch, M J P; Vanbavel, E; Boellaard, R; Lammertsma, A A; Nederveen, A J

    2014-05-15

    Measurements of the cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) provide useful information about cerebrovascular condition and regional metabolism. Pseudo-continuous arterial spin labeling (pCASL) is a promising non-invasive MRI technique to quantitatively measure the CBF, whereas additional hypercapnic pCASL measurements are currently showing great promise to quantitatively assess the CVR. However, the introduction of pCASL at a larger scale awaits further evaluation of the exact accuracy and precision compared to the gold standard. (15)O H₂O positron emission tomography (PET) is currently regarded as the most accurate and precise method to quantitatively measure both CBF and CVR, though it is one of the more invasive methods as well. In this study we therefore assessed the accuracy and precision of quantitative pCASL-based CBF and CVR measurements by performing a head-to-head comparison with (15)O H₂O PET, based on quantitative CBF measurements during baseline and hypercapnia. We demonstrate that pCASL CBF imaging is accurate during both baseline and hypercapnia with respect to (15)O H₂O PET with a comparable precision. These results pave the way for quantitative usage of pCASL MRI in both clinical and research settings.

  18. Detecting declines in the abundance of a bull trout (Salvelinus confluentus) population: Understanding the accuracy, precision, and costs of our efforts

    USGS Publications Warehouse

    Al-Chokhachy, R.; Budy, P.; Conner, M.

    2009-01-01

    Using empirical field data for bull trout (Salvelinus confluentus), we evaluated the trade-off between power and sampling effort-cost using Monte Carlo simulations of commonly collected mark-recapture-resight and count data, and we estimated the power to detect changes in abundance across different time intervals. We also evaluated the effects of monitoring different components of a population and stratification methods on the precision of each method. Our results illustrate substantial variability in the relative precision, cost, and information gained from each approach. While grouping estimates by age or stage class substantially increased the precision of estimates, spatial stratification of sampling units resulted in limited increases in precision. Although mark-resight methods allowed for estimates of abundance versus indices of abundance, our results suggest snorkel surveys may be a more affordable monitoring approach across large spatial scales. Detecting a 25% decline in abundance after 5 years was not possible, regardless of technique (power = 0.80), without high sampling effort (48% of study site). Detecting a 25% decline was possible after 15 years, but still required high sampling efforts. Our results suggest detecting moderate changes in abundance of freshwater salmonids requires considerable resource and temporal commitments and highlight the difficulties of using abundance measures for monitoring bull trout populations.

  19. GOCE Precise Science Orbits

    NASA Astrophysics Data System (ADS)

    Bock, Heike; Jäggi, Adrian; Meyer, Ulrich; Beutler, Gerhard; Heinze, Markus; Hugentobler, Urs

    GOCE (Gravity field and steady-state Ocean Circulation Explorer), as the first ESA (European Space Agency) Earth Explorer Core Mission, is dedicated for gravity field recovery of unprece-dented accuracy using data from the gradiometer, its primary science instrument. Data from the secondary instrument, the 12-channel dual-frequency GPS (Global Positioning System) receiver, is used for precise orbit determination of the satellite. These orbits are used to accu-rately geolocate the gradiometer observations and to provide complementary information for the long-wavelength part of the gravity field. A precise science orbit (PSO) product is provided by the GOCE High-Level Processing Facility (HPF) with a precision of about 2 cm and a 1-week latency. The reduced-dynamic and kinematic orbit determination strategies for the PSO product are presented together with results of about one year of data. The focus is on the improvement achieved by the use of empirically derived azimuth-and elevation-dependent variations of the phase center of the GOCE GPS antenna. The orbits are validated with satellite laser ranging (SLR) measurements.

  20. Improving accuracy and precision of ice core δD (CH4) analyses using methane pre- and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

    NASA Astrophysics Data System (ADS)

    Bock, M.; Schmitt, J.; Beck, J.; Schneider, R.; Fischer, H.

    2013-12-01

    Firn and polar ice cores offer the only direct paleoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD (CH4)) 0.5 to 1.5 kg of ice was previously necessary to achieve the required precision. Here we present a method to improve precision and reduce the sample amount for δD (CH4) measurements on (ice core) air. Pre-concentrated methane is focused before a high temperature oven (pre pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post pyrolysis trapping), both on a carbon-PLOT capillary at -196 °C. A small amount of methane and krypton are trapped together with H2 and must be separated using a short second chromatographic column to ensure accurate results. Pre and post pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods we estimate a precision of 2.2‰ for 350 g of ice (or roughly 30 mL (at standard temperature and pressure (STP)) of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.

  1. Accuracy and precision of a new portable ultrasound scanner, the BME-150A, in residual urine volume measurement: a comparison with the BladderScan BVI 3000.

    PubMed

    Choe, Jin Ho; Lee, Ji Yeon; Lee, Kyu-Sung

    2007-06-01

    The objective of the study was to determine the relative accuracy of a new portable ultrasound unit, BME-150A, and the BladderScan BVI 3000, as assessed in comparison with the catheterized residual urine volume. We used both of these machines to prospectively measure the residual urine volumes of 89 patients (40 men and 49 women) who were undergoing urodynamic studies. The ultrasound measurements were compared with the post-scan bladder volumes obtained by catheterization in the same patients. The ultrasounds were followed immediately (within 5 min) by in-and-out catheterizations while the patients were in a supine position. There were a total of 116 paired measurements made. The BME-150A and the BVI 3000 demonstrated a correlation with the residual volume of 0.92 and 0.94, and a mean difference from the true residual volume of 7.8 and 3.6 ml, respectively. Intraclass correlation coefficients for the accuracy of the two bladder scans were 0.90 for BME-150A and 0.95 for BVI 3000. The difference of accuracy between the two models was not significant (p = 0.2421). There were six cases in which a follow-up evaluation of falsely elevated post-void residual urine volume measurements on the ultrasound studies resulted in comparatively low catheterized volumes, with a range of differences from 66 to 275.5 ml. These cases were diagnosed with an ovarian cyst, uterine myoma, or uterine adenomyosis on pelvic ultrasonography. The accuracy of the BME-150A is comparable to that of the BVI 3000 in estimating the true residual urine volumes and is sufficient enough for us to recommend its use as an alternative to catheterization.

  2. Improving accuracy and precision of ice core δD(CH4) analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

    NASA Astrophysics Data System (ADS)

    Bock, M.; Schmitt, J.; Beck, J.; Schneider, R.; Fischer, H.

    2014-07-01

    Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4) or δ2H(CH4)) 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4) measurements in (ice core) air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping), both on a carbon-PLOT capillary at -196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL - at standard temperature and pressure (STP) - of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.

  3. Simultaneous Variable Flip Angle – Actual Flip Angle Imaging (VAFI) Method for Improved Accuracy and Precision of Three-dimensional T1 and B1 Measurements

    PubMed Central

    Hurley, Samuel A.; Yarnykh, Vasily L.; Johnson, Kevin M.; Field, Aaron S.; Alexander, Andrew L.; Samsonov, Alexey A.

    2011-01-01

    A new time-efficient and accurate technique for simultaneous mapping of T1 and B1 is proposed based on a combination of the Actual Flip angle Imaging (AFI) and Variable Flip Angle (VFA) methods: VAFI. VAFI utilizes a single AFI and one or more spoiled gradient-echo (SPGR) acquisitions with a simultaneous non-linear fitting procedure to yield accurate T1/B1 maps. The advantage of VAFI is high accuracy at either short T1 times or long TR in the AFI sequence. Simulations show this method is accurate to 0.03% in FA and 0.07% in T1 for TR/T1 times over the range of 0.01 to 0.45. We show for the case of brain imaging that it is sufficient to use only one small flip angle SPGR acquisition, which results in reduced spoiling requirements and a significant scan time reduction compared to the original VFA. In-vivo validation yielded high-quality 3D T1 maps and T1 measurements within 10% of previously published values, and within a clinically acceptable scan time. The VAFI method will increase the accuracy and clinical feasibility of many quantitative MRI methods requiring T1/B1 mapping such as DCE perfusion and quantitative MTI. PMID:22139819

  4. Method and system using power modulation for maskless vapor deposition of spatially graded thin film and multilayer coatings with atomic-level precision and accuracy

    DOEpatents

    Montcalm, Claude; Folta, James Allen; Tan, Swie-In; Reiss, Ira

    2002-07-30

    A method and system for producing a film (preferably a thin film with highly uniform or highly accurate custom graded thickness) on a flat or graded substrate (such as concave or convex optics), by sweeping the substrate across a vapor deposition source operated with time-varying flux distribution. In preferred embodiments, the source is operated with time-varying power applied thereto during each sweep of the substrate to achieve the time-varying flux distribution as a function of time. A user selects a source flux modulation recipe for achieving a predetermined desired thickness profile of the deposited film. The method relies on precise modulation of the deposition flux to which a substrate is exposed to provide a desired coating thickness distribution.

  5. Accuracy and precision of reconstruction of complex refractive index in near-field single-distance propagation-based phase-contrast tomography

    NASA Astrophysics Data System (ADS)

    Gureyev, Timur; Mohammadi, Sara; Nesterets, Yakov; Dullin, Christian; Tromba, Giuliana

    2013-10-01

    We investigate the quantitative accuracy and noise sensitivity of reconstruction of the 3D distribution of complex refractive index, n(r)=1-δ(r)+iβ(r), in samples containing materials with different refractive indices using propagation-based phase-contrast computed tomography (PB-CT). Our present study is limited to the case of parallel-beam geometry with monochromatic synchrotron radiation, but can be readily extended to cone-beam CT and partially coherent polychromatic X-rays at least in the case of weakly absorbing samples. We demonstrate that, except for regions near the interfaces between distinct materials, the distribution of imaginary part of the refractive index, β(r), can be accurately reconstructed from a single projection image per view angle using phase retrieval based on the so-called homogeneous version of the Transport of Intensity equation (TIE-Hom) in combination with conventional CT reconstruction. In contrast, the accuracy of reconstruction of δ(r) depends strongly on the choice of the "regularization" parameter in TIE-Hom. We demonstrate by means of an instructive example that for some multi-material samples, a direct application of the TIE-Hom method in PB-CT produces qualitatively incorrect results for δ(r), which can be rectified either by collecting additional projection images at each view angle, or by utilising suitable a priori information about the sample. As a separate observation, we also show that, in agreement with previous reports, it is possible to significantly improve signal-to-noise ratio by increasing the sample-to-detector distance in combination with TIE-Hom phase retrieval in PB-CT compared to conventional ("contact") CT, with the maximum achievable gain of the order of 0.3δ /β. This can lead to improved image quality and/or reduction of the X-ray dose delivered to patients in medical imaging.

  6. Preliminary assessment of the accuracy and precision of TOPEX/POSEIDON altimeter data with respect to the large-scale ocean circulation

    NASA Technical Reports Server (NTRS)

    Wunsch, Carl; Stammer, Detlef

    1994-01-01

    TOPEX/POSEIDON sea surface height measurements are examined for quantitative consistency with known elements of the oceanic general circulation and its variability. Project-provided corrections were accepted but are at tested as part of the overall results. The ocean was treated as static over each 10-day repeat cycle and maps constructed of the absolute sea surface topography from simple averages in 2 deg x 2 deg bins. A hybrid geoid model formed from a combination of the recent Joint Gravity Model-2 and the project-provided Ohio State University geoid was used to estimate the absolute topography in each 10-day period. Results are examined in terms of the annual average, seasonal average, seasonal variations, and variations near the repeat period. Conclusion are as follows: the orbit error is now difficult to observe, having been reduced to a level at or below the level of other error sources; the geoid dominates the error budget of the estimates of the absolute topography; the estimated seasonal cycle is consistent with prior estimates; shorter-period variability is dominated on the largest scales by an oscillation near 50 days in spherical harmonics Y(sup m)(sub 1)(theta, lambda) with an amplitude near 10 cm, close to the simplest alias of the M(sub 2) tide. This spectral peak and others visible in the periodograms support the hypothesis that the largest remaining time-dependent errors lie in the tidal models. Though discrepancies attribute to the geoid are within the formal uncertainties of the good estimates, removal of them is urgent for circulation studies. Current gross accuracy of the TOPEX/POSEIDON mission is in the range of 5-10 cm, distributed overbroad band of frequencies and wavenumbers. In finite bands, accuracies approach the 1-cm level, and expected improvements arising from extended mission duration should reduce these numbers by nearly an order of magnitude.

  7. The Influence of External Loads on Movement Precision During Active Shoulder Internal Rotation Movements as Measured by 3 Indices of Accuracy

    PubMed Central

    Brindle, Timothy J; Uhl, Timothy L; Nitz, Arthur J; Shapiro, Robert

    2006-01-01

    Context: Using constant, variable, and absolute error to measure movement accuracy might provide a more complete description of joint position sense than any of these values alone. Objective: To determine the effect of loaded movements and type of feedback on shoulder joint position sense and movement velocity. Design: Applied study with repeated measures comparing type of feedback and the presence of a load. Setting: Laboratory. Patients or Other Participants: Twenty healthy subjects (age = 27.2 ± 3.3 years, height = 173.2 ± 18.1 cm, mass = 70.8 ± 14.5 kg) were seated with their arms in a custom shoulder wheel. Intervention(s): Subjects internally rotated 27° in the plane of the scapula, with either visual feedback provided by a video monitor or proprioceptive feedback provided by prior passive positioning, to a target at 48° of external rotation. Subjects performed the internal rotation movements with video feedback and proprioceptive feedback and with and without load (5% of body weight). Main Outcome Measure(s): High-speed motion analysis recorded peak rotational velocity and accuracy. Constant, variable, and absolute error for joint position sense was calculated from the final position. Results: Unloaded movements demonstrated significantly greater variable error than for loaded movements (2.0 ± 0.7° and 1.5 ± 0.4°, respectively) (P < .05), but there were no differences in constant or absolute error. Peak velocity was greater for movements with proprioceptive feedback (45.6 ± 2.9°/s) than visual feedback (39.1 ± 2.1°/s) and for unloaded (47.8 ± 3.6°/s) than loaded (36.9 ± 1.0°/s) movements (P < .05). Conclusions: Shoulder joint position sense demonstrated greater variable error unloaded versus loaded movements. Both visual feedback and additional loads decreased peak rotational velocity. PMID:16619096

  8. Accuracy for detection of simulated lesions: comparison of fluid-attenuated inversion-recovery, proton density--weighted, and T2-weighted synthetic brain MR imaging

    NASA Technical Reports Server (NTRS)

    Herskovits, E. H.; Itoh, R.; Melhem, E. R.

    2001-01-01

    OBJECTIVE: The objective of our study was to determine the effects of MR sequence (fluid-attenuated inversion-recovery [FLAIR], proton density--weighted, and T2-weighted) and of lesion location on sensitivity and specificity of lesion detection. MATERIALS AND METHODS: We generated FLAIR, proton density-weighted, and T2-weighted brain images with 3-mm lesions using published parameters for acute multiple sclerosis plaques. Each image contained from zero to five lesions that were distributed among cortical-subcortical, periventricular, and deep white matter regions; on either side; and anterior or posterior in position. We presented images of 540 lesions, distributed among 2592 image regions, to six neuroradiologists. We constructed a contingency table for image regions with lesions and another for image regions without lesions (normal). Each table included the following: the reviewer's number (1--6); the MR sequence; the side, position, and region of the lesion; and the reviewer's response (lesion present or absent [normal]). We performed chi-square and log-linear analyses. RESULTS: The FLAIR sequence yielded the highest true-positive rates (p < 0.001) and the highest true-negative rates (p < 0.001). Regions also differed in reviewers' true-positive rates (p < 0.001) and true-negative rates (p = 0.002). The true-positive rate model generated by log-linear analysis contained an additional sequence-location interaction. The true-negative rate model generated by log-linear analysis confirmed these associations, but no higher order interactions were added. CONCLUSION: We developed software with which we can generate brain images of a wide range of pulse sequences and that allows us to specify the location, size, shape, and intrinsic characteristics of simulated lesions. We found that the use of FLAIR sequences increases detection accuracy for cortical-subcortical and periventricular lesions over that associated with proton density- and T2-weighted sequences.

  9. High-accuracy, high-precision, high-resolution, continuous monitoring of urban greenhouse gas emissions? Results to date from INFLUX

    NASA Astrophysics Data System (ADS)

    Davis, K. J.; Brewer, A.; Cambaliza, M. O. L.; Deng, A.; Hardesty, M.; Gurney, K. R.; Heimburger, A. M. F.; Karion, A.; Lauvaux, T.; Lopez-Coto, I.; McKain, K.; Miles, N. L.; Patarasuk, R.; Prasad, K.; Razlivanov, I. N.; Richardson, S.; Sarmiento, D. P.; Shepson, P. B.; Sweeney, C.; Turnbull, J. C.; Whetstone, J. R.; Wu, K.

    2015-12-01

    The Indianapolis Flux Experiment (INFLUX) is testing the boundaries of our ability to use atmospheric measurements to quantify urban greenhouse gas (GHG) emissions. The project brings together inventory assessments, tower-based and aircraft-based atmospheric measurements, and atmospheric modeling to provide high-accuracy, high-resolution, continuous monitoring of emissions of GHGs from the city. Results to date include a multi-year record of tower and aircraft based measurements of the urban CO2 and CH4 signal, long-term atmospheric modeling of GHG transport, and emission estimates for both CO2 and CH4 based on both tower and aircraft measurements. We will present these emissions estimates, the uncertainties in each, and our assessment of the primary needs for improvements in these emissions estimates. We will also present ongoing efforts to improve our understanding of atmospheric transport and background atmospheric GHG mole fractions, and to disaggregate GHG sources (e.g. biogenic vs. fossil fuel CO2 fluxes), topics that promise significant improvement in urban GHG emissions estimates.

  10. Accuracy and Precision in the Southern Hemisphere Additional Ozonesondes (SHADOZ) Dataset 1998-2000 in Light of the JOSIE-2000 Results

    NASA Technical Reports Server (NTRS)

    Witte, J. C.; Thompson, A. M.; Schmidlin, F. J.; Oltmans, S. J.; McPeters, R. D.; Smit, H. G. J.

    2003-01-01

    A network of 12 southern hemisphere tropical and subtropical stations in the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has provided over 2000 profiles of stratospheric and tropospheric ozone since 1998. Balloon-borne electrochemical concentration cell (ECC) ozonesondes are used with standard radiosondes for pressure, temperature and relative humidity measurements. The archived data are available at:http: //croc.gsfc.nasa.gov/shadoz. In Thompson et al., accuracies and imprecisions in the SHADOZ 1998- 2000 dataset were examined using ground-based instruments and the TOMS total ozone measurement (version 7) as references. Small variations in ozonesonde technique introduced possible biases from station-to-station. SHADOZ total ozone column amounts are now compared to version 8 TOMS; discrepancies between the two datasets are reduced 2\\% on average. An evaluation of ozone variations among the stations is made using the results of a series of chamber simulations of ozone launches (JOSIE-2000, Juelich Ozonesonde Intercomparison Experiment) in which a standard reference ozone instrument was employed with the various sonde techniques used in SHADOZ. A number of variations in SHADOZ ozone data are explained when differences in solution strength, data processing and instrument type (manufacturer) are taken into account.

  11. The effect of dilution and the use of a post-extraction nucleic acid purification column on the accuracy, precision, and inhibition of environmental DNA samples

    USGS Publications Warehouse

    Mckee, Anna M.; Spear, Stephen F.; Pierson, Todd W.

    2015-01-01

    Isolation of environmental DNA (eDNA) is an increasingly common method for detecting presence and assessing relative abundance of rare or elusive species in aquatic systems via the isolation of DNA from environmental samples and the amplification of species-specific sequences using quantitative PCR (qPCR). Co-extracted substances that inhibit qPCR can lead to inaccurate results and subsequent misinterpretation about a species’ status in the tested system. We tested three treatments (5-fold and 10-fold dilutions, and spin-column purification) for reducing qPCR inhibition from 21 partially and fully inhibited eDNA samples collected from coastal plain wetlands and mountain headwater streams in the southeastern USA. All treatments reduced the concentration of DNA in the samples. However, column purified samples retained the greatest sensitivity. For stream samples, all three treatments effectively reduced qPCR inhibition. However, for wetland samples, the 5-fold dilution was less effective than other treatments. Quantitative PCR results for column purified samples were more precise than the 5-fold and 10-fold dilutions by 2.2× and 3.7×, respectively. Column purified samples consistently underestimated qPCR-based DNA concentrations by approximately 25%, whereas the directional bias in qPCR-based DNA concentration estimates differed between stream and wetland samples for both dilution treatments. While the directional bias of qPCR-based DNA concentration estimates differed among treatments and locations, the magnitude of inaccuracy did not. Our results suggest that 10-fold dilution and column purification effectively reduce qPCR inhibition in mountain headwater stream and coastal plain wetland eDNA samples, and if applied to all samples in a study, column purification may provide the most accurate relative qPCR-based DNA concentrations estimates while retaining the greatest assay sensitivity.

  12. Evaluation of the automated hematology analyzer Sysmex XT-2000iV™ compared to the ADVIA® 2120 for its use in dogs, cats, and horses: Part I--precision, linearity, and accuracy of complete blood cell count.

    PubMed

    Bauer, Natali; Nakagawa, Julia; Dunker, Cathrin; Failing, Klaus; Moritz, Andreas

    2011-11-01

    The automated laser-based hematology analyzer Sysmex XT-2000iV™ providing a complete blood cell count (CBC) and 5-part differential has been introduced in large veterinary laboratories. The aim of the current study was to determine precision, linearity, and accuracy of the Sysmex analyzer. Reference method for the accuracy study was the laser-based hematology analyzer ADVIA® 2120. For evaluation of accuracy, consecutive fresh blood samples from healthy and diseased cats (n = 216), dogs (n = 314), and horses (n = 174) were included. A low intra-assay coefficient of variation (CV) of approximately 1% was seen for the CBC except platelet count (PLT). An intra-assay CV ranging between 2% and 5.5% was evident for the differential count except for feline and equine monocytes (7.7%) and horse eosinophils (15.7%). Linearity was excellent for white blood cell count (WBC), hematocrit value, red blood cell count (RBC), and PLT. For all evaluated species, agreement was excellent for WBC and RBC, with Spearman rank correlation coefficients (r(s)) ranging from >0.99 to 0.98. Hematocrit value correlated excellently in cats and dogs, whereas for horses, a good correlation was evident. A good correlation between both analyzers was seen in feline and equine PLT (r(s) = 0.89 and 0.92, respectively), whereas correlation was excellent for dogs (r(s) = 0.93). Biases were close to 0 except for mean corpuscular hemoglobin concentration (4.11 to -7.25 mmol/l) and canine PLT (57 × 10(9)/l). Overall, the performance of the Sysmex analyzer was excellent and compared favorably with the ADVIA analyzer.

  13. Precision volume measurement system.

    SciTech Connect

    Fischer, Erin E.; Shugard, Andrew D.

    2004-11-01

    A new precision volume measurement system based on a Kansas City Plant (KCP) design was built to support the volume measurement needs of the Gas Transfer Systems (GTS) department at Sandia National Labs (SNL) in California. An engineering study was undertaken to verify or refute KCP's claims of 0.5% accuracy. The study assesses the accuracy and precision of the system. The system uses the ideal gas law and precise pressure measurements (of low-pressure helium) in a temperature and computer controlled environment to ratio a known volume to an unknown volume.

  14. Comparative Analysis of the Equivital EQ02 Lifemonitor with Holter Ambulatory ECG Device for Continuous Measurement of ECG, Heart Rate, and Heart Rate Variability: A Validation Study for Precision and Accuracy.

    PubMed

    Akintola, Abimbola A; van de Pol, Vera; Bimmel, Daniel; Maan, Arie C; van Heemst, Diana

    2016-01-01

    Background: The Equivital (EQ02) is a multi-parameter telemetric device offering both real-time and/or retrospective, synchronized monitoring of ECG, HR, and HRV, respiration, activity, and temperature. Unlike the Holter, which is the gold standard for continuous ECG measurement, EQO2 continuously monitors ECG via electrodes interwoven in the textile of a wearable belt. Objective: To compare EQ02 with the Holter for continuous home measurement of ECG, heart rate (HR), and heart rate variability (HRV). Methods: Eighteen healthy participants wore, simultaneously for 24 h, the Holter and EQ02 monitors. Per participant, averaged HR, and HRV per 5 min from the two devices were compared using Pearson correlation, paired T-test, and Bland-Altman analyses. Accuracy and precision metrics included mean absolute relative difference (MARD). Results: Artifact content of EQ02 data varied widely between (range 1.93-56.45%) and within (range 0.75-9.61%) participants. Comparing the EQ02 to the Holter, the Pearson correlations were respectively 0.724, 0.955, and 0.997 for datasets containing all data and data with < 50 or < 20% artifacts respectively. For datasets containing respectively all data, data with < 50, or < 20% artifacts, bias estimated by Bland-Altman analysis was -2.8, -1.0, and -0.8 beats per minute and 24 h MARD was 7.08, 3.01, and 1.5. After selecting a 3-h stretch of data containing 1.15% artifacts, Pearson correlation was 0.786 for HRV measured as standard deviation of NN intervals (SDNN). Conclusions: Although the EQ02 can accurately measure ECG and HRV, its accuracy and precision is highly dependent on artifact content. This is a limitation for clinical use in individual patients. However, the advantages of the EQ02 (ability to simultaneously monitor several physiologic parameters) may outweigh its disadvantages (higher artifact load) for research purposes and/ or for home monitoring in larger groups of study participants. Further studies can be aimed at

  15. Comparative Analysis of the Equivital EQ02 Lifemonitor with Holter Ambulatory ECG Device for Continuous Measurement of ECG, Heart Rate, and Heart Rate Variability: A Validation Study for Precision and Accuracy

    PubMed Central

    Akintola, Abimbola A.; van de Pol, Vera; Bimmel, Daniel; Maan, Arie C.; van Heemst, Diana

    2016-01-01

    Background: The Equivital (EQ02) is a multi-parameter telemetric device offering both real-time and/or retrospective, synchronized monitoring of ECG, HR, and HRV, respiration, activity, and temperature. Unlike the Holter, which is the gold standard for continuous ECG measurement, EQO2 continuously monitors ECG via electrodes interwoven in the textile of a wearable belt. Objective: To compare EQ02 with the Holter for continuous home measurement of ECG, heart rate (HR), and heart rate variability (HRV). Methods: Eighteen healthy participants wore, simultaneously for 24 h, the Holter and EQ02 monitors. Per participant, averaged HR, and HRV per 5 min from the two devices were compared using Pearson correlation, paired T-test, and Bland-Altman analyses. Accuracy and precision metrics included mean absolute relative difference (MARD). Results: Artifact content of EQ02 data varied widely between (range 1.93–56.45%) and within (range 0.75–9.61%) participants. Comparing the EQ02 to the Holter, the Pearson correlations were respectively 0.724, 0.955, and 0.997 for datasets containing all data and data with < 50 or < 20% artifacts respectively. For datasets containing respectively all data, data with < 50, or < 20% artifacts, bias estimated by Bland-Altman analysis was −2.8, −1.0, and −0.8 beats per minute and 24 h MARD was 7.08, 3.01, and 1.5. After selecting a 3-h stretch of data containing 1.15% artifacts, Pearson correlation was 0.786 for HRV measured as standard deviation of NN intervals (SDNN). Conclusions: Although the EQ02 can accurately measure ECG and HRV, its accuracy and precision is highly dependent on artifact content. This is a limitation for clinical use in individual patients. However, the advantages of the EQ02 (ability to simultaneously monitor several physiologic parameters) may outweigh its disadvantages (higher artifact load) for research purposes and/ or for home monitoring in larger groups of study participants. Further studies can be aimed

  16. Excretion kinetics of 13C-urea breath test: influences of endogenous CO2 production and dose recovery on the diagnostic accuracy of Helicobacter pylori infection.

    PubMed

    Som, Suman; Maity, Abhijit; Banik, Gourab Dutta; Ghosh, Chiranjit; Chaudhuri, Sujit; Daschakraborty, Sunil Baran; Ghosh, Shibendu; Pradhan, Manik

    2014-09-01

    We report for the first time the excretion kinetics of the percentage dose of (13)C recovered/h ((13)C-PDR %/h) and cumulative PDR, i.e. c-PDR (%) to accomplish the highest diagnostic accuracy of the (13)C-urea breath test ((13)C-UBT) for the detection of Helicobacter pylori infection without any risk of diagnostic errors using an optical cavity-enhanced integrated cavity output spectroscopy (ICOS) method. An optimal diagnostic cut-off point for the presence of H. pylori infection was determined to be c-PDR (%) = 1.47 % at 60 min, using the receiver operating characteristic curve (ROC) analysis to overcome the "grey zone" containing false-positive and false-negative results of the (13)C-UBT. The present (13)C-UBT exhibited 100 % diagnostic sensitivity (true-positive rate) and 100 % specificity (true-negative rate) with an accuracy of 100 % compared with invasive endoscopy and biopsy tests. Our c-PDR (%) methodology also manifested both diagnostic positive and negative predictive values of 100 %, demonstrating excellent diagnostic accuracy. We also observed that the effect of endogenous CO2 production related to basal metabolic rates in individuals was statistically insignificant (p = 0.78) on the diagnostic accuracy. However, the presence of H. pylori infection was indicated by the profound effect of urea hydrolysis rate (UHR). Our findings suggest that the current c-PDR (%) is a valid and sufficiently robust novel approach for an accurate, specific, fast and noninvasive diagnosis of H. pylori infection, which could routinely be used for large-scale screening purposes and diagnostic assessment, i.e. for early detection and follow-up of patients.

  17. Optimetrics for Precise Navigation

    NASA Technical Reports Server (NTRS)

    Yang, Guangning; Heckler, Gregory; Gramling, Cheryl

    2017-01-01

    Optimetrics for Precise Navigation will be implemented on existing optical communication links. The ranging and Doppler measurements are conducted over communication data frame and clock. The measurement accuracy is two orders of magnitude better than TDRSS. It also has other advantages of: The high optical carrier frequency enables: (1) Immunity from ionosphere and interplanetary Plasma noise floor, which is a performance limitation for RF tracking; and (2) High antenna gain reduces terminal size and volume, enables high precision tracking in Cubesat, and in deep space smallsat. High Optical Pointing Precision provides: (a) spacecraft orientation, (b) Minimal additional hardware to implement Precise Optimetrics over optical comm link; and (c) Continuous optical carrier phase measurement will enable the system presented here to accept future optical frequency standard with much higher clock accuracy.

  18. Precision electron polarimetry

    SciTech Connect

    Chudakov, Eugene A.

    2013-11-01

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. M{\\o}ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at ~300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100\\%-polarized electron target for M{\\o}ller polarimetry.

  19. Precision electron polarimetry

    NASA Astrophysics Data System (ADS)

    Chudakov, E.

    2013-11-01

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. Mo/ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at 300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100%-polarized electron target for Mo/ller polarimetry.

  20. Precision electron polarimetry

    SciTech Connect

    Chudakov, E.

    2013-11-07

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. Mo/ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at 300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100%-polarized electron target for Mo/ller polarimetry.

  1. SU-E-P-54: Evaluation of the Accuracy and Precision of IGPS-O X-Ray Image-Guided Positioning System by Comparison with On-Board Imager Cone-Beam Computed Tomography

    SciTech Connect

    Zhang, D; Wang, W; Jiang, B; Fu, D

    2015-06-15

    Purpose: The purpose of this study is to assess the positioning accuracy and precision of IGPS-O system which is a novel radiographic kilo-voltage x-ray image-guided positioning system developed for clinical IGRT applications. Methods: IGPS-O x-ray image-guided positioning system consists of two oblique sets of radiographic kilo-voltage x-ray projecting and imaging devices which were equiped on the ground and ceiling of treatment room. This system can determine the positioning error in the form of three translations and three rotations according to the registration of two X-ray images acquired online and the planning CT image. An anthropomorphic head phantom and an anthropomorphic thorax phantom were used for this study. The phantom was set up on the treatment table with correct position and various “planned” setup errors. Both IGPS-O x-ray image-guided positioning system and the commercial On-board Imager Cone-beam Computed Tomography (OBI CBCT) were used to obtain the setup errors of the phantom. Difference of the Result between the two image-guided positioning systems were computed and analyzed. Results: The setup errors measured by IGPS-O x-ray image-guided positioning system and the OBI CBCT system showed a general agreement, the means and standard errors of the discrepancies between the two systems in the left-right, anterior-posterior, superior-inferior directions were −0.13±0.09mm, 0.03±0.25mm, 0.04±0.31mm, respectively. The maximum difference was only 0.51mm in all the directions and the angular discrepancy was 0.3±0.5° between the two systems. Conclusion: The spatial and angular discrepancies between IGPS-O system and OBI CBCT for setup error correction was minimal. There is a general agreement between the two positioning system. IGPS-O x-ray image-guided positioning system can achieve as good accuracy as CBCT and can be used in the clinical IGRT applications.

  2. Characterizing accuracy of total hemoglobin recovery using contrast-detail analysis in 3D image-guided near infrared spectroscopy with the boundary element method

    PubMed Central

    Ghadyani, Hamid R.; Srinivasan, Subhadra; Pogue, Brian W.; Paulsen, Keith D.

    2010-01-01

    The quantification of total hemoglobin concentration (HbT) obtained from multi-modality image-guided near infrared spectroscopy (IG-NIRS) was characterized using the boundary element method (BEM) for 3D image reconstruction. Multi-modality IG-NIRS systems use a priori information to guide the reconstruction process. While this has been shown to improve resolution, the effect on quantitative accuracy is unclear. Here, through systematic contrast-detail analysis, the fidelity of IG-NIRS in quantifying HbT was examined using 3D simulations. These simulations show that HbT could be recovered for medium sized (20mm in 100mm total diameter) spherical inclusions with an average error of 15%, for the physiologically relevant situation of 2:1 or higher contrast between background and inclusion. Using partial 3D volume meshes to reduce the ill-posed nature of the image reconstruction, inclusions as small as 14mm could be accurately quantified with less than 15% error, for contrasts of 1.5 or higher. This suggests that 3D IG-NIRS provides quantitatively accurate results for sizes seen early in treatment cycle of patients undergoing neoadjuvant chemotherapy when the tumors are larger than 30mm. PMID:20720975

  3. Application of AFINCH as a tool for evaluating the effects of streamflow-gaging-network size and composition on the accuracy and precision of streamflow estimates at ungaged locations in the southeast Lake Michigan hydrologic subregion

    USGS Publications Warehouse

    Koltun, G.F.; Holtschlag, David J.

    2010-01-01

    Bootstrapping techniques employing random subsampling were used with the AFINCH (Analysis of Flows In Networks of CHannels) model to gain insights into the effects of variation in streamflow-gaging-network size and composition on the accuracy and precision of streamflow estimates at ungaged locations in the 0405 (Southeast Lake Michigan) hydrologic subregion. AFINCH uses stepwise-regression techniques to estimate monthly water yields from catchments based on geospatial-climate and land-cover data in combination with available streamflow and water-use data. Calculations are performed on a hydrologic-subregion scale for each catchment and stream reach contained in a National Hydrography Dataset Plus (NHDPlus) subregion. Water yields from contributing catchments are multiplied by catchment areas and resulting flow values are accumulated to compute streamflows in stream reaches which are referred to as flow lines. AFINCH imposes constraints on water yields to ensure that observed streamflows are conserved at gaged locations.  Data from the 0405 hydrologic subregion (referred to as Southeast Lake Michigan) were used for the analyses. Daily streamflow data were measured in the subregion for 1 or more years at a total of 75 streamflow-gaging stations during the analysis period which spanned water years 1971–2003. The number of streamflow gages in operation each year during the analysis period ranged from 42 to 56 and averaged 47. Six sets (one set for each censoring level), each composed of 30 random subsets of the 75 streamflow gages, were created by censoring (removing) approximately 10, 20, 30, 40, 50, and 75 percent of the streamflow gages (the actual percentage of operating streamflow gages censored for each set varied from year to year, and within the year from subset to subset, but averaged approximately the indicated percentages).Streamflow estimates for six flow lines each were aggregated by censoring level, and results were analyzed to assess (a) how the

  4. Precision Measurement.

    ERIC Educational Resources Information Center

    Radius, Marcie; And Others

    The manual provides information for precision measurement (counting of movements per minute of a chosen activity) of achievement in special education students. Initial sections give guidelines for the teacher, parent, and student to follow for various methods of charting behavior. It is explained that precision measurement is a way to measure the…

  5. Precision Medicine

    PubMed Central

    Cholerton, Brenna; Larson, Eric B.; Quinn, Joseph F.; Zabetian, Cyrus P.; Mata, Ignacio F.; Keene, C. Dirk; Flanagan, Margaret; Crane, Paul K.; Grabowski, Thomas J.; Montine, Kathleen S.; Montine, Thomas J.

    2017-01-01

    Three key elements to precision medicine are stratification by risk, detection of pathophysiological processes as early as possible (even before clinical presentation), and alignment of mechanism of action of intervention(s) with an individual's molecular driver(s) of disease. Used for decades in the management of some rare diseases and now gaining broad currency in cancer care, a precision medicine approach is beginning to be adapted to cognitive impairment and dementia. This review focuses on the application of precision medicine to address the clinical and biological complexity of two common neurodegenerative causes of dementia: Alzheimer disease and Parkinson disease. PMID:26724389

  6. Overlay accuracy fundamentals

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  7. Precision optical navigation guidance system

    NASA Astrophysics Data System (ADS)

    Starodubov, D.; McCormick, K.; Nolan, P.; Johnson, D.; Dellosa, M.; Volfson, L.; Fallahpour, A.; Willner, A.

    2016-05-01

    We present the new precision optical navigation guidance system approach that provides continuous, high quality range and bearing data to fixed wing aircraft during landing approach to an aircraft carrier. The system uses infrared optical communications to measure range between ship and aircraft with accuracy and precision better than 1 meter at ranges more than 7.5 km. The innovative receiver design measures bearing from aircraft to ship with accuracy and precision better than 0.5 mRad. The system provides real-time range and bearing updates to multiple aircraft at rates up to several kHz, and duplex data transmission between ship and aircraft.

  8. Precise Orbit Determination for ALOS

    NASA Technical Reports Server (NTRS)

    Nakamura, Ryo; Nakamura, Shinichi; Kudo, Nobuo; Katagiri, Seiji

    2007-01-01

    The Advanced Land Observing Satellite (ALOS) has been developed to contribute to the fields of mapping, precise regional land coverage observation, disaster monitoring, and resource surveying. Because the mounted sensors need high geometrical accuracy, precise orbit determination for ALOS is essential for satisfying the mission objectives. So ALOS mounts a GPS receiver and a Laser Reflector (LR) for Satellite Laser Ranging (SLR). This paper deals with the precise orbit determination experiments for ALOS using Global and High Accuracy Trajectory determination System (GUTS) and the evaluation of the orbit determination accuracy by SLR data. The results show that, even though the GPS receiver loses lock of GPS signals more frequently than expected, GPS-based orbit is consistent with SLR-based orbit. And considering the 1 sigma error, orbit determination accuracy of a few decimeters (peak-to-peak) was achieved.

  9. Precision metrology.

    PubMed

    Jiang, X; Whitehouse, D J

    2012-08-28

    This article is a summary of the Satellite Meeting, which followed on from the Discussion Meeting at the Royal Society on 'Ultra-precision engineering: from physics to manufacture', held at the Kavli Royal Society International Centre, Chicheley Hall, Buckinghamshire, UK. The meeting was restricted to 18 invited experts in various aspects of precision metrology from academics from the UK and Sweden, Government Institutes from the UK and Germany and global aerospace industries. It examined and identified metrology problem areas that are, or may be, limiting future developments in precision engineering and, in particular, metrology. The Satellite Meeting was intended to produce a vision that will inspire academia and industry to address the solutions of those open-ended problems identified. The discussion covered three areas, namely the function of engineering parts, their measurement and their manufacture, as well as their interactions.

  10. Precision translator

    DOEpatents

    Reedy, Robert P.; Crawford, Daniel W.

    1984-01-01

    A precision translator for focusing a beam of light on the end of a glass fiber which includes two turning fork-like members rigidly connected to each other. These members have two prongs each with its separation adjusted by a screw, thereby adjusting the orthogonal positioning of a glass fiber attached to one of the members. This translator is made of simple parts with capability to keep adjustment even in condition of rough handling.

  11. Precision translator

    DOEpatents

    Reedy, R.P.; Crawford, D.W.

    1982-03-09

    A precision translator for focusing a beam of light on the end of a glass fiber which includes two turning fork-like members rigidly connected to each other. These members have two prongs each with its separation adjusted by a screw, thereby adjusting the orthogonal positioning of a glass fiber attached to one of the members. This translator is made of simple parts with capability to keep adjustment even in condition of rough handling.

  12. Precision GPS ephemerides and baselines

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Based on the research, the area of precise ephemerides for GPS satellites, the following observations can be made pertaining to the status and future work needed regarding orbit accuracy. There are several aspects which need to be addressed in discussing determination of precise orbits, such as force models, kinematic models, measurement models, data reduction/estimation methods, etc. Although each one of these aspects was studied at CSR in research efforts, only points pertaining to the force modeling aspect are addressed.

  13. Assessing the Accuracy and Precision of Inorganic Geochemical Data Produced through Flux Fusion and Acid Digestions: Multiple (60+) Comprehensive Analyses of BHVO-2 and the Development of Improved "Accepted" Values

    NASA Astrophysics Data System (ADS)

    Ireland, T. J.; Scudder, R.; Dunlea, A. G.; Anderson, C. H.; Murray, R. W.

    2014-12-01

    The use of geological standard reference materials (SRMs) to assess both the accuracy and the reproducibility of geochemical data is a vital consideration in determining the major and trace element abundances of geologic, oceanographic, and environmental samples. Calibration curves commonly are generated that are predicated on accurate analyses of these SRMs. As a means to verify the robustness of these calibration curves, a SRM can also be run as an unknown item (i.e., not included as a data point in the calibration). The experimentally derived composition of the SRM can thus be compared to the certified (or otherwise accepted) value. This comparison gives a direct measure of the accuracy of the method used. Similarly, if the same SRM is analyzed as an unknown over multiple analytical sessions, the external reproducibility of the method can be evaluated. Two common bulk digestion methods used in geochemical analysis are flux fusion and acid digestion. The flux fusion technique is excellent at ensuring complete digestion of a variety of sample types, is quick, and does not involve much use of hazardous acids. However, this technique is hampered by a high amount of total dissolved solids and may be accompanied by an increased analytical blank for certain trace elements. On the other hand, acid digestion (using a cocktail of concentrated nitric, hydrochloric and hydrofluoric acids) provides an exceptionally clean digestion with very low analytical blanks. However, this technique results in a loss of Si from the system and may compromise results for a few other elements (e.g., Ge). Our lab uses flux fusion for the determination of major elements and a few key trace elements by ICP-ES, while acid digestion is used for Ti and trace element analyses by ICP-MS. Here we present major and trace element data for BHVO-2, a frequently used SRM derived from a Hawaiian basalt, gathered over a period of over two years (30+ analyses by each technique). We show that both digestion

  14. Precise Measurement for Manufacturing

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A metrology instrument known as PhaseCam supports a wide range of applications, from testing large optics to controlling factory production processes. This dynamic interferometer system enables precise measurement of three-dimensional surfaces in the manufacturing industry, delivering speed and high-resolution accuracy in even the most challenging environments.Compact and reliable, PhaseCam enables users to make interferometric measurements right on the factory floor. The system can be configured for many different applications, including mirror phasing, vacuum/cryogenic testing, motion/modal analysis, and flow visualization.

  15. Precision GPS ephemerides and baselines

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The emphasis of this grant was focused on precision ephemerides for the Global Positioning System (GPS) satellites for geodynamics applications. During the period of this grant, major activities were in the areas of thermal force modeling, numerical integration accuracy improvement for eclipsing satellites, analysis of GIG '91 campaign data, and the Southwest Pacific campaign data analysis.

  16. Precision spectroscopy of Helium

    SciTech Connect

    Cancio, P.; Giusfredi, G.; Mazzotti, D.; De Natale, P.; De Mauro, C.; Krachmalnicoff, V.; Inguscio, M.

    2005-05-05

    Accurate Quantum-Electrodynamics (QED) tests of the simplest bound three body atomic system are performed by precise laser spectroscopic measurements in atomic Helium. In this paper, we present a review of measurements between triplet states at 1083 nm (23S-23P) and at 389 nm (23S-33P). In 4He, such data have been used to measure the fine structure of the triplet P levels and, then, to determine the fine structure constant when compared with equally accurate theoretical calculations. Moreover, the absolute frequencies of the optical transitions have been used for Lamb-shift determinations of the levels involved with unprecedented accuracy. Finally, determination of the He isotopes nuclear structure and, in particular, a measurement of the nuclear charge radius, are performed by using hyperfine structure and isotope-shift measurements.

  17. Precision ozone vapor pressure measurements

    NASA Technical Reports Server (NTRS)

    Hanson, D.; Mauersberger, K.

    1985-01-01

    The vapor pressure above liquid ozone has been measured with a high accuracy over a temperature range of 85 to 95 K. At the boiling point of liquid argon (87.3 K) an ozone vapor pressure of 0.0403 Torr was obtained with an accuracy of + or - 0.7 percent. A least square fit of the data provided the Clausius-Clapeyron equation for liquid ozone; a latent heat of 82.7 cal/g was calculated. High-precision vapor pressure data are expected to aid research in atmospheric ozone measurements and in many laboratory ozone studies such as measurements of cross sections and reaction rates.

  18. Quality, precision and accuracy of the maximum No. 40 anemometer

    SciTech Connect

    Obermeir, J.; Blittersdorf, D.

    1996-12-31

    This paper synthesizes available calibration data for the Maximum No. 40 anemometer. Despite its long history in the wind industry, controversy surrounds the choice of transfer function for this anemometer. Many users are unaware that recent changes in default transfer functions in data loggers are producing output wind speed differences as large as 7.6%. Comparison of two calibration methods used for large samples of Maximum No. 40 anemometers shows a consistent difference of 4.6% in output speeds. This difference is significantly larger than estimated uncertainty levels. Testing, initially performed to investigate related issues, reveals that Gill and Maximum cup anemometers change their calibration transfer functions significantly when calibrated in the open atmosphere compared with calibration in a laminar wind tunnel. This indicates that atmospheric turbulence changes the calibration transfer function of cup anemometers. These results call into question the suitability of standard wind tunnel calibration testing for cup anemometers. 6 refs., 10 figs., 4 tabs.

  19. Tomography & Geochemistry: Precision, Repeatability, Accuracy and Joint Interpretations

    NASA Astrophysics Data System (ADS)

    Foulger, G. R.; Panza, G. F.; Artemieva, I. M.; Bastow, I. D.; Cammarano, F.; Doglioni, C.; Evans, J. R.; Hamilton, W. B.; Julian, B. R.; Lustrino, M.; Thybo, H.; Yanovskaya, T. B.

    2015-12-01

    Seismic tomography can reveal the spatial seismic structure of the mantle, but has little ability to constrain composition, phase or temperature. In contrast, petrology and geochemistry can give insights into mantle composition, but have severely limited spatial control on magma sources. For these reasons, results from these three disciplines are often interpreted jointly. Nevertheless, the limitations of each method are often underestimated, and underlying assumptions de-emphasized. Examples of the limitations of seismic tomography include its ability to image in detail the three-dimensional structure of the mantle or to determine with certainty the strengths of anomalies. Despite this, published seismic anomaly strengths are often unjustifiably translated directly into physical parameters. Tomography yields seismological parameters such as wave speed and attenuation, not geological or thermal parameters. Much of the mantle is poorly sampled by seismic waves, and resolution- and error-assessment methods do not express the true uncertainties. These and other problems have become highlighted in recent years as a result of multiple tomography experiments performed by different research groups, in areas of particular interest e.g., Yellowstone. The repeatability of the results is often poorer than the calculated resolutions. The ability of geochemistry and petrology to identify magma sources and locations is typically overestimated. These methods have little ability to determine source depths. Models that assign geochemical signatures to specific layers in the mantle, including the transition zone, the lower mantle, and the core-mantle boundary, are based on speculative models that cannot be verified and for which viable, less-astonishing alternatives are available. Our knowledge is poor of the size, distribution and location of protoliths, and of metasomatism of magma sources, the nature of the partial-melting and melt-extraction process, the mixing of disparate melts, and the re-assimilation of crust and mantle lithosphere by rising melt. Interpretations of seismic tomography, petrologic and geochemical observations, and all three together, are ambiguous, and this needs to be emphasized more in presenting interpretations so that the viability of the models can be assessed more reliably.

  20. Precision and accuracy of visual foliar injury assessments

    SciTech Connect

    Gumpertz, M.L.; Tingey, D.T.; Hogsett, W.E.

    1982-07-01

    The study compared three measures of foliar injury: (i) mean percent leaf area injured of all leaves on the plant, (ii) mean percent leaf area injured of the three most injured leaves, and (iii) the proportion of injured leaves to total number of leaves. For the first measure, the variation caused by reader biases and day-to-day variations were compared with the innate plant-to-plant variation. Bean (Phaseolus vulgaris 'Pinto'), pea (Pisum sativum 'Little Marvel'), radish (Rhaphanus sativus 'Cherry Belle'), and spinach (Spinacia oleracea 'Northland') plants were exposed to either 3 ..mu..L L/sup -1/ SO/sub 2/ or 0.3 ..mu..L L/sup -1/ ozone for 2 h. Three leaf readers visually assessed the percent injury on every leaf of each plant while a fourth reader used a transparent grid to make an unbiased assessment for each plant. The mean leaf area injured of the three most injured leaves was highly correlated with all leaves on the plant only if the three most injured leaves were <100% injured. The proportion of leaves injured was not highly correlated with percent leaf area injured of all leaves on the plant for any species in this study. The largest source of variation in visual assessments was plant-to-plant variation, which ranged from 44 to 97% of the total variance, followed by variation among readers (0-32% of the variance). Except for radish exposed to ozone, the day-to-day variation accounted for <18% of the total. Reader bias in assessment of ozone injury was significant but could be adjusted for each reader by a simple linear regression (R/sup 2/ = 0.89-0.91) of the visual assessments against the grid assessments.

  1. Global positioning system measurements for crustal deformation: Precision and accuracy

    USGS Publications Warehouse

    Prescott, W.H.; Davis, J.L.; Svarc, J.L.

    1989-01-01

    Analysis of 27 repeated observations of Global Positioning System (GPS) position-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million.

  2. Accuracy and Precision of Radioactivity Quantification in Nuclear Medicine Images

    PubMed Central

    Frey, Eric C.; Humm, John L.; Ljungberg, Michael

    2012-01-01

    The ability to reliably quantify activity in nuclear medicine has a number of increasingly important applications. Dosimetry for targeted therapy treatment planning or for approval of new imaging agents requires accurate estimation of the activity in organs, tumors, or voxels at several imaging time points. Another important application is the use of quantitative metrics derived from images, such as the standard uptake value commonly used in positron emission tomography (PET), to diagnose and follow treatment of tumors. These measures require quantification of organ or tumor activities in nuclear medicine images. However, there are a number of physical, patient, and technical factors that limit the quantitative reliability of nuclear medicine images. There have been a large number of improvements in instrumentation, including the development of hybrid single-photon emission computed tomography/computed tomography and PET/computed tomography systems, and reconstruction methods, including the use of statistical iterative reconstruction methods, which have substantially improved the ability to obtain reliable quantitative information from planar, single-photon emission computed tomography, and PET images. PMID:22475429

  3. Precision and Accuracy of Intercontinental Distance Determinations Using Radio Interferometry.

    DTIC Science & Technology

    1983-07-01

    Variations of the dispersion of at least this amount occur in the Mark III system. We cannot place an upper bound on the variations of the dispersion...final two terms will be 0.002 psec and 0.020 psec when t23=2.OxlO 6 sec/sec and vl2-0.02 sec. The latter two values are upper bounds for Earth based...neglected in the derivations in Section 4.1. We will now analyze each of these terms and try to place upper bounds on their contributions to the

  4. Arrival Metering Precision Study

    NASA Technical Reports Server (NTRS)

    Prevot, Thomas; Mercer, Joey; Homola, Jeffrey; Hunt, Sarah; Gomez, Ashley; Bienert, Nancy; Omar, Faisal; Kraut, Joshua; Brasil, Connie; Wu, Minghong, G.

    2015-01-01

    This paper describes the background, method and results of the Arrival Metering Precision Study (AMPS) conducted in the Airspace Operations Laboratory at NASA Ames Research Center in May 2014. The simulation study measured delivery accuracy, flight efficiency, controller workload, and acceptability of time-based metering operations to a meter fix at the terminal area boundary for different resolution levels of metering delay times displayed to the air traffic controllers and different levels of airspeed information made available to the Time-Based Flow Management (TBFM) system computing the delay. The results show that the resolution of the delay countdown timer (DCT) on the controllers display has a significant impact on the delivery accuracy at the meter fix. Using the 10 seconds rounded and 1 minute rounded DCT resolutions resulted in more accurate delivery than 1 minute truncated and were preferred by the controllers. Using the speeds the controllers entered into the fourth line of the data tag to update the delay computation in TBFM in high and low altitude sectors increased air traffic control efficiency and reduced fuel burn for arriving aircraft during time based metering.

  5. Mixed-Precision Spectral Deferred Correction: Preprint

    SciTech Connect

    Grout, Ray W. S.

    2015-09-02

    Convergence of spectral deferred correction (SDC), where low-order time integration methods are used to construct higher-order methods through iterative refinement, can be accelerated in terms of computational effort by using mixed-precision methods. Using ideas from multi-level SDC (in turn based on FAS multigrid ideas), some of the SDC correction sweeps can use function values computed in reduced precision without adversely impacting the accuracy of the final solution. This is particularly beneficial for the performance of combustion solvers such as S3D [6] which require double precision accuracy but are performance limited by the cost of data motion.

  6. A consensus on protein structure accuracy in NMR?

    PubMed

    Billeter, Martin

    2015-02-03

    The precision of an NMR structure may be manipulated by calculation parameters such as calibration factors. Its accuracy is, however, a different issue. In this issue of Structure, Buchner and Güntert present "consensus structure bundles," where precision analysis allows estimation of accuracy.

  7. Precision injection molding of freeform optics

    NASA Astrophysics Data System (ADS)

    Fang, Fengzhou; Zhang, Nan; Zhang, Xiaodong

    2016-08-01

    Precision injection molding is the most efficient mass production technology for manufacturing plastic optics. Applications of plastic optics in field of imaging, illumination, and concentration demonstrate a variety of complex surface forms, developing from conventional plano and spherical surfaces to aspheric and freeform surfaces. It requires high optical quality with high form accuracy and lower residual stresses, which challenges both optical tool inserts machining and precision injection molding process. The present paper reviews recent progress in mold tool machining and precision injection molding, with more emphasis on precision injection molding. The challenges and future development trend are also discussed.

  8. Precision powder feeder

    DOEpatents

    Schlienger, M. Eric; Schmale, David T.; Oliver, Michael S.

    2001-07-10

    A new class of precision powder feeders is disclosed. These feeders provide a precision flow of a wide range of powdered materials, while remaining robust against jamming or damage. These feeders can be precisely controlled by feedback mechanisms.

  9. Examination of Numerical Integration Accuracy and Modeling for GRACE-FO and GRACE-II

    NASA Astrophysics Data System (ADS)

    McCullough, C.; Bettadpur, S.

    2012-12-01

    As technological advances throughout the field of satellite geodesy improve the accuracy of satellite measurements, numerical methods and algorithms must be able to keep pace. Currently, the Gravity Recovery and Climate Experiment's (GRACE) dual one-way microwave ranging system can determine changes in inter-satellite range to a precision of a few microns; however, with the advent of laser measurement systems nanometer precision ranging is a realistic possibility. With this increase in measurement accuracy, a reevaluation of the accuracy inherent in the linear multi-step numerical integration methods is necessary. Two areas where this can be a primary concern are the ability of the numerical integration methods to accurately predict the satellite's state in the presence of numerous small accelerations due to operation of the spacecraft attitude control thrusters, and due to small, point-mass anomalies on the surface of the Earth. This study attempts to quantify and minimize these numerical errors in an effort to improve the accuracy of modeling and propagation of these perturbations; helping to provide further insight into the behavior and evolution of the Earth's gravity field from the more capable gravity missions in the future.

  10. Airborne Topographic Mapper Calibration Procedures and Accuracy Assessment

    NASA Technical Reports Server (NTRS)

    Martin, Chreston F.; Krabill, William B.; Manizade, Serdar S.; Russell, Rob L.; Sonntag, John G.; Swift, Robert N.; Yungel, James K.

    2012-01-01

    Description of NASA Airborn Topographic Mapper (ATM) lidar calibration procedures including analysis of the accuracy and consistancy of various ATM instrument parameters and the resulting influence on topographic elevation measurements. The ATM elevations measurements from a nominal operating altitude 500 to 750 m above the ice surface was found to be: Horizontal Accuracy 74 cm, Horizontal Precision 14 cm, Vertical Accuracy 6.6 cm, Vertical Precision 3 cm.

  11. Reading Recovery.

    ERIC Educational Resources Information Center

    Jones, Joanna R., Ed.

    1992-01-01

    This issue of the Arizona Reading Journal focuses on the theme "reading recovery" and includes the following articles: "Why Is an Inservice Programme for Reading Recovery Teachers Necessary?" (Marie M. Clay); "What Is Reading Recovery?" (Gay Su Pinnell); "Teaching a Hard To Teach Child" (Constance A.…

  12. High precision modeling for fundamental physics experiments

    NASA Astrophysics Data System (ADS)

    Rievers, Benny; Nesemann, Leo; Costea, Adrian; Andres, Michael; Stephan, Ernst P.; Laemmerzahl, Claus

    With growing experimental accuracies and high precision requirements for fundamental physics space missions the needs for accurate numerical modeling techniques are increasing. Motivated by the challenge of length stability in cavities and optical resonators we propose the develop-ment of a high precision modeling tool for the simulation of thermomechanical effects up to a numerical precision of 10-20 . Exemplary calculations for simplified test cases demonstrate the general feasibility of high precision calculations and point out the high complexity of the task. A tool for high precision analysis of complex geometries will have to use new data types, advanced FE solver routines and implement new methods for the evaluation of numerical precision.

  13. Increasing Accuracy in Environmental Measurements

    NASA Astrophysics Data System (ADS)

    Jacksier, Tracey; Fernandes, Adelino; Matthew, Matt; Lehmann, Horst

    2016-04-01

    Human activity is increasing the concentrations of green house gases (GHG) in the atmosphere which results in temperature increases. High precision is a key requirement of atmospheric measurements to study the global carbon cycle and its effect on climate change. Natural air containing stable isotopes are used in GHG monitoring to calibrate analytical equipment. This presentation will examine the natural air and isotopic mixture preparation process, for both molecular and isotopic concentrations, for a range of components and delta values. The role of precisely characterized source material will be presented. Analysis of individual cylinders within multiple batches will be presented to demonstrate the ability to dynamically fill multiple cylinders containing identical compositions without isotopic fractionation. Additional emphasis will focus on the ability to adjust isotope ratios to more closely bracket sample types without the reliance on combusting naturally occurring materials, thereby improving analytical accuracy.

  14. Precise predictions for slepton pair production

    SciTech Connect

    Ayres Freitas; Andreas von Manteuffel

    2002-11-07

    At a future linear collider, the masses and couplings of scalar leptons can be measured with high accuracy, thus requiring precise theoretical predictions for the relevant processes. In this work, after a discussion of the expected experimental precision, the complete one-loop corrections to smuon and selectron pair production in the MSSM are presented and the effect of different contributions in the result is analyzed.

  15. High-precision arithmetic in mathematical physics

    DOE PAGES

    Bailey, David H.; Borwein, Jonathan M.

    2015-05-12

    For many scientific calculations, particularly those involving empirical data, IEEE 32-bit floating-point arithmetic produces results of sufficient accuracy, while for other applications IEEE 64-bit floating-point is more appropriate. But for some very demanding applications, even higher levels of precision are often required. Furthermore, this article discusses the challenge of high-precision computation, in the context of mathematical physics, and highlights what facilities are required to support future computation, in light of emerging developments in computer architecture.

  16. Accuracy of percentage of signal intensity recovery and relative cerebral blood volume derived from dynamic susceptibility-weighted, contrast-enhanced MRI in the preoperative diagnosis of cerebral tumours

    PubMed Central

    Steel, Timothy; Chaganti, Joga

    2015-01-01

    Conventional magnetic resonance imaging (MRI) is the technique of choice for diagnosis of cerebral tumours, and has become an increasingly powerful tool for their evaluation; however, the diagnosis of common contrast-enhancing lesions can be challenging, as it is sometimes impossible to differentiate them using conventional imaging. Histopathological analysis of biopsy specimens is the gold standard for diagnosis; however, there are significant risks associated with the invasive procedure and definitive diagnosis is not always achieved. Early accurate diagnosis is important, as management differs accordingly. Advanced MRI techniques have increasing utility for aiding diagnosis in a variety of clinical scenarios. Dynamic susceptibility-weighted contrast-enhanced (DSC) MRI is a perfusion imaging technique and a potentially important tool for the characterisation of cerebral tumours. The percentage of signal intensity recovery (PSR) and relative cerebral blood volume (rCBV) derived from DSC MRI provide information about tumour capillary permeability and neoangiogenesis, which can be used to characterise tumour type and grade, and distinguish tumour recurrence from treatment-related effects. Therefore, PSR and rCBV potentially represent a non-invasive means of diagnosis; however, the clinical utility of these parameters has yet to be established. We present a review of the literature to date. PMID:26475485

  17. Precise Countersinking Tool

    NASA Technical Reports Server (NTRS)

    Jenkins, Eric S.; Smith, William N.

    1992-01-01

    Tool countersinks holes precisely with only portable drill; does not require costly machine tool. Replaceable pilot stub aligns axis of tool with centerline of hole. Ensures precise cut even with imprecise drill. Designed for relatively low cutting speeds.

  18. Precision agricultural systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision agriculture is a new farming practice that has been developing since late 1980s. It has been variously referred to as precision farming, prescription farming, site-specific crop management, to name but a few. There are numerous definitions for precision agriculture, but the central concept...

  19. Recovery Online

    ERIC Educational Resources Information Center

    Clark, John R.

    2007-01-01

    Since the founding of Alcoholics Anonymous (AA) in 1935, programs offering opportunity for recovery from alcoholism and other addictions have undergone vast changes. The Internet has created nearly limitless opportunities for recovering people and those seeking recovery to find both meetings and places where they can gather virtually and discuss…

  20. Precision CW laser automatic tracking system investigated

    NASA Technical Reports Server (NTRS)

    Lang, K. T.; Lucy, R. F.; Mcgann, E. J.; Peters, C. J.

    1966-01-01

    Precision laser tracker capable of tracking a low acceleration target to an accuracy of about 20 microradians rms is being constructed and tested. This laser tracking has the advantage of discriminating against other optical sources and the capability of simultaneously measuring range.

  1. Automatic precision measurement of spectrograms.

    PubMed

    Palmer, B A; Sansonetti, C J; Andrew, K L

    1978-08-01

    A fully automatic comparator has been designed and implemented to determine precision wavelengths from high-resolution spectrograms. The accuracy attained is superior to that of an experienced operator using a semiautomatic comparator with a photoelectric setting device. The system consists of a comparator, slightly modified for simultaneous data acquisition from two parallel scans of the spectrogram, interfaced to a minicomputer. The software which controls the system embodies three innovations of special interest. (1) Data acquired from two parallel scans are compared and used to separate unknown from standard lines, to eliminate spurious lines, to identify blends of unknown with standard lines, to improve the accuracy of the measured positions, and to flag lines which require special examination. (2) Two classes of lines are automatically recognized and appropriate line finding methods are applied to each. This provides precision measurement for both simple and complex line profiles. (3) Wavelength determination using a least-squares fitted grating equation is supported in addition to polynomial interpolation. This is most useful in spectral regions with sparsely distributed standards. The principles and implementation of these techniques are fully described.

  2. Precision performance lamp technology

    NASA Astrophysics Data System (ADS)

    Bell, Dean A.; Kiesa, James E.; Dean, Raymond A.

    1997-09-01

    A principal function of a lamp is to produce light output with designated spectra, intensity, and/or geometric radiation patterns. The function of a precision performance lamp is to go beyond these parameters and into the precision repeatability of performance. All lamps are not equal. There are a variety of incandescent lamps, from the vacuum incandescent indictor lamp to the precision lamp of a blood analyzer. In the past the definition of a precision lamp was described in terms of wattage, light center length (LCL), filament position, and/or spot alignment. This paper presents a new view of precision lamps through the discussion of a new segment of lamp design, which we term precision performance lamps. The definition of precision performance lamps will include (must include) the factors of a precision lamp. But what makes a precision lamp a precision performance lamp is the manner in which the design factors of amperage, mscp (mean spherical candlepower), efficacy (lumens/watt), life, not considered individually but rather considered collectively. There is a statistical bias in a precision performance lamp for each of these factors; taken individually and as a whole. When properly considered the results can be dramatic to the system design engineer, system production manage and the system end-user. It can be shown that for the lamp user, the use of precision performance lamps can translate to: (1) ease of system design, (2) simplification of electronics, (3) superior signal to noise ratios, (4) higher manufacturing yields, (5) lower system costs, (6) better product performance. The factors mentioned above are described along with their interdependent relationships. It is statistically shown how the benefits listed above are achievable. Examples are provided to illustrate how proper attention to precision performance lamp characteristics actually aid in system product design and manufacturing to build and market more, market acceptable product products in the

  3. Factors relating to eating style, social desirability, body image and eating meals at home increase the precision of calibration equations correcting self-report measures of diet using recovery biomarkers: findings from the Women’s Health Initiative

    PubMed Central

    2013-01-01

    significantly different between the calibration equations with or without the six psychosocial and diet variables for protein density (p = 0.02), but not for energy (p = 0.119) or protein intake (p = 0.077). Conclusions The addition of psychosocial and diet behavior factors to calibration equations significantly increases the amount of total variance explained for protein density and their inclusion would be expected to strengthen the precision of calibration equations correcting self-report for measurement error. Trial registration ClinicalTrials.gov identifier: NCT00000611 PMID:23679960

  4. Precision optical metrology without lasers

    NASA Astrophysics Data System (ADS)

    Bergmann, Ralf B.; Burke, Jan; Falldorf, Claas

    2015-07-01

    Optical metrology is a key technique when it comes to precise and fast measurement with a resolution down to the micrometer or even nanometer regime. The choice of a particular optical metrology technique and the quality of results depends on sample parameters such as size, geometry and surface roughness as well as user requirements such as resolution, measurement time and robustness. Interferometry-based techniques are well known for their low measurement uncertainty in the nm range, but usually require careful isolation against vibration and a laser source that often needs shielding for reasons of eye-safety. In this paper, we concentrate on high precision optical metrology without lasers by using the gradient based measurement technique of deflectometry and the finite difference based technique of shear interferometry. Careful calibration of deflectometry systems allows one to investigate virtually all kinds of reflecting surfaces including aspheres or free-form surfaces with measurement uncertainties below the μm level. Computational Shear Interferometry (CoSI) allows us to combine interferometric accuracy and the possibility to use cheap and eye-safe low-brilliance light sources such as e.g. fiber coupled LEDs or even liquid crystal displays. We use CoSI e.g. for quantitative phase contrast imaging in microscopy. We highlight the advantages of both methods, discuss their transfer functions and present results on the precision of both techniques.

  5. Addiction recovery: its definition and conceptual boundaries.

    PubMed

    White, William L

    2007-10-01

    The addiction field's failure to achieve consensus on a definition of "recovery" from severe and persistent alcohol and other drug problems undermines clinical research, compromises clinical practice, and muddles the field's communications to service constituents, allied service professionals, the public, and policymakers. This essay discusses 10 questions critical to the achievement of such a definition and offers a working definition of recovery that attempts to meet the criteria of precision, inclusiveness, exclusiveness, measurability, acceptability, and simplicity. The key questions explore who has professional and cultural authority to define recovery, the defining ingredients of recovery, the boundaries (scope and depth) of recovery, and temporal benchmarks of recovery (when recovery begins and ends). The process of defining recovery touches on some of the most controversial issues within the addictions field.

  6. [Precision and personalized medicine].

    PubMed

    Sipka, Sándor

    2016-10-01

    The author describes the concept of "personalized medicine" and the newly introduced "precision medicine". "Precision medicine" applies the terms of "phenotype", "endotype" and "biomarker" in order to characterize more precisely the various diseases. Using "biomarkers" the homogeneous type of a disease (a "phenotype") can be divided into subgroups called "endotypes" requiring different forms of treatment and financing. The good results of "precision medicine" have become especially apparent in relation with allergic and autoimmune diseases. The application of this new way of thinking is going to be necessary in Hungary, too, in the near future for participants, controllers and financing boards of healthcare. Orv. Hetil., 2016, 157(44), 1739-1741.

  7. Precision positioning device

    DOEpatents

    McInroy, John E.

    2005-01-18

    A precision positioning device is provided. The precision positioning device comprises a precision measuring/vibration isolation mechanism. A first plate is provided with the precision measuring mean secured to the first plate. A second plate is secured to the first plate. A third plate is secured to the second plate with the first plate being positioned between the second plate and the third plate. A fourth plate is secured to the third plate with the second plate being positioned between the third plate and the fourth plate. An adjusting mechanism for adjusting the position of the first plate, the second plate, the third plate, and the fourth plate relative to each other.

  8. Precision aerial application for site-specific rice crop management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision agriculture includes different technologies that allow agricultural professional to use information management tools to optimize agriculture production. The new technologies allow aerial application applicators to improve application accuracy and efficiency, which saves time and money for...

  9. System and method for high precision isotope ratio destructive analysis

    DOEpatents

    Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

    2013-07-02

    A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

  10. Precision antenna reflector structures

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.

    1985-01-01

    The assembly of the Large Precise Reflector Infrared Telescope is detailed. Also given are the specifications for the Aft Cargo Carrier and the Large Precision Reflector structure. Packaging concepts and options, stowage depth and support truss geometry are also considered. An example of a construction scenario is given.

  11. Precision Optics Curriculum.

    ERIC Educational Resources Information Center

    Reid, Robert L.; And Others

    This guide outlines the competency-based, two-year precision optics curriculum that the American Precision Optics Manufacturers Association has proposed to fill the void that it suggests will soon exist as many of the master opticians currently employed retire. The model, which closely resembles the old European apprenticeship model, calls for 300…

  12. GEOSPATIAL DATA ACCURACY ASSESSMENT

    EPA Science Inventory

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

  13. Landsat wildland mapping accuracy

    USGS Publications Warehouse

    Todd, William J.; Gehring, Dale G.; Haman, J. F.

    1980-01-01

    A Landsat-aided classification of ten wildland resource classes was developed for the Shivwits Plateau region of the Lake Mead National Recreation Area. Single stage cluster sampling (without replacement) was used to verify the accuracy of each class.

  14. System for precise position registration

    DOEpatents

    Sundelin, Ronald M.; Wang, Tong

    2005-11-22

    An apparatus for enabling accurate retaining of a precise position, such as for reacquisition of a microscopic spot or feature having a size of 0.1 mm or less, on broad-area surfaces after non-in situ processing. The apparatus includes a sample and sample holder. The sample holder includes a base and three support posts. Two of the support posts interact with a cylindrical hole and a U-groove in the sample to establish location of one point on the sample and a line through the sample. Simultaneous contact of the third support post with the surface of the sample defines a plane through the sample. All points of the sample are therefore uniquely defined by the sample and sample holder. The position registration system of the current invention provides accuracy, as measured in x, y repeatability, of at least 140 .mu.m.

  15. A 3-D Multilateration: A Precision Geodetic Measurement System

    NASA Technical Reports Server (NTRS)

    Escobal, P. R.; Fliegel, H. F.; Jaffe, R. M.; Muller, P. M.; Ong, K. M.; Vonroos, O. H.

    1972-01-01

    A system was designed with the capability of determining 1-cm accuracy station positions in three dimensions using pulsed laser earth satellite tracking stations coupled with strictly geometric data reduction. With this high accuracy, several crucial geodetic applications become possible, including earthquake hazards assessment, precision surveying, plate tectonics, and orbital determination.

  16. Accuracy of analyses of microelectronics nanostructures in atom probe tomography

    NASA Astrophysics Data System (ADS)

    Vurpillot, F.; Rolland, N.; Estivill, R.; Duguay, S.; Blavette, D.

    2016-07-01

    The routine use of atom probe tomography (APT) as a nano-analysis microscope in the semiconductor industry requires the precise evaluation of the metrological parameters of this instrument (spatial accuracy, spatial precision, composition accuracy or composition precision). The spatial accuracy of this microscope is evaluated in this paper in the analysis of planar structures such as high-k metal gate stacks. It is shown both experimentally and theoretically that the in-depth accuracy of reconstructed APT images is perturbed when analyzing this structure composed of an oxide layer of high electrical permittivity (higher-k dielectric constant) that separates the metal gate and the semiconductor channel of a field emitter transistor. Large differences in the evaporation field between these layers (resulting from large differences in material properties) are the main sources of image distortions. An analytic model is used to interpret inaccuracy in the depth reconstruction of these devices in APT.

  17. Precision liquid level sensor

    DOEpatents

    Field, M.E.; Sullivan, W.H.

    A precision liquid level sensor utilizes a balanced bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

  18. Precision Measurement in Biology

    NASA Astrophysics Data System (ADS)

    Quake, Stephen

    Is biology a quantitative science like physics? I will discuss the role of precision measurement in both physics and biology, and argue that in fact both fields can be tied together by the use and consequences of precision measurement. The elementary quanta of biology are twofold: the macromolecule and the cell. Cells are the fundamental unit of life, and macromolecules are the fundamental elements of the cell. I will describe how precision measurements have been used to explore the basic properties of these quanta, and more generally how the quest for higher precision almost inevitably leads to the development of new technologies, which in turn catalyze further scientific discovery. In the 21st century, there are no remaining experimental barriers to biology becoming a truly quantitative and mathematical science.

  19. Precision Environmental Radiation Monitoring System

    SciTech Connect

    Vladimir Popov, Pavel Degtiarenko

    2010-07-01

    A new precision low-level environmental radiation monitoring system has been developed and tested at Jefferson Lab. This system provides environmental radiation measurements with accuracy and stability of the order of 1 nGy/h in an hour, roughly corresponding to approximately 1% of the natural cosmic background at the sea level. Advanced electronic front-end has been designed and produced for use with the industry-standard High Pressure Ionization Chamber detector hardware. A new highly sensitive readout electronic circuit was designed to measure charge from the virtually suspended ionization chamber ion collecting electrode. New signal processing technique and dedicated data acquisition were tested together with the new readout. The designed system enabled data collection in a remote Linux-operated computer workstation, which was connected to the detectors using a standard telephone cable line. The data acquisition system algorithm is built around the continuously running 24-bit resolution 192 kHz data sampling analog to digital convertor. The major features of the design include: extremely low leakage current in the input circuit, true charge integrating mode operation, and relatively fast response to the intermediate radiation change. These features allow operating of the device as an environmental radiation monitor, at the perimeters of the radiation-generating installations in densely populated areas, like in other monitoring and security applications requiring high precision and long-term stability. Initial system evaluation results are presented.

  20. Precision displacement reference system

    DOEpatents

    Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

    2000-02-22

    A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

  1. Principles of precision medicine in stroke.

    PubMed

    Hinman, Jason D; Rost, Natalia S; Leung, Thomas W; Montaner, Joan; Muir, Keith W; Brown, Scott; Arenillas, Juan F; Feldmann, Edward; Liebeskind, David S

    2017-01-01

    The era of precision medicine has arrived and conveys tremendous potential, particularly for stroke neurology. The diagnosis of stroke, its underlying aetiology, theranostic strategies, recurrence risk and path to recovery are populated by a series of highly individualised questions. Moreover, the phenotypic complexity of a clinical diagnosis of stroke makes a simple genetic risk assessment only partially informative on an individual basis. The guiding principles of precision medicine in stroke underscore the need to identify, value, organise and analyse the multitude of variables obtained from each individual to generate a precise approach to optimise cerebrovascular health. Existing data may be leveraged with novel technologies, informatics and practical clinical paradigms to apply these principles in stroke and realise the promise of precision medicine. Importantly, precision medicine in stroke will only be realised once efforts to collect, value and synthesise the wealth of data collected in clinical trials and routine care starts. Stroke theranostics, the ultimate vision of synchronising tailored therapeutic strategies based on specific diagnostic data, demand cerebrovascular expertise on big data approaches to clinically relevant paradigms. This review considers such challenges and delineates the principles on a roadmap for rational application of precision medicine to stroke and cerebrovascular health.

  2. Precision medicine in cardiology.

    PubMed

    Antman, Elliott M; Loscalzo, Joseph

    2016-10-01

    The cardiovascular research and clinical communities are ideally positioned to address the epidemic of noncommunicable causes of death, as well as advance our understanding of human health and disease, through the development and implementation of precision medicine. New tools will be needed for describing the cardiovascular health status of individuals and populations, including 'omic' data, exposome and social determinants of health, the microbiome, behaviours and motivations, patient-generated data, and the array of data in electronic medical records. Cardiovascular specialists can build on their experience and use precision medicine to facilitate discovery science and improve the efficiency of clinical research, with the goal of providing more precise information to improve the health of individuals and populations. Overcoming the barriers to implementing precision medicine will require addressing a range of technical and sociopolitical issues. Health care under precision medicine will become a more integrated, dynamic system, in which patients are no longer a passive entity on whom measurements are made, but instead are central stakeholders who contribute data and participate actively in shared decision-making. Many traditionally defined diseases have common mechanisms; therefore, elimination of a siloed approach to medicine will ultimately pave the path to the creation of a universal precision medicine environment.

  3. Numerical accuracy assessment

    NASA Astrophysics Data System (ADS)

    Boerstoel, J. W.

    1988-12-01

    A framework is provided for numerical accuracy assessment. The purpose of numerical flow simulations is formulated. This formulation concerns the classes of aeronautical configurations (boundaries), the desired flow physics (flow equations and their properties), the classes of flow conditions on flow boundaries (boundary conditions), and the initial flow conditions. Next, accuracy and economical performance requirements are defined; the final numerical flow simulation results of interest should have a guaranteed accuracy, and be produced for an acceptable FLOP-price. Within this context, the validation of numerical processes with respect to the well known topics of consistency, stability, and convergence when the mesh is refined must be done by numerical experimentation because theory gives only partial answers. This requires careful design of text cases for numerical experimentation. Finally, the results of a few recent evaluation exercises of numerical experiments with a large number of codes on a few test cases are summarized.

  4. Seasonal Effects on GPS PPP Accuracy

    NASA Astrophysics Data System (ADS)

    Saracoglu, Aziz; Ugur Sanli, D.

    2016-04-01

    GPS Precise Point Positioning (PPP) is now routinely used in many geophysical applications. Static positioning and 24 h data are requested for high precision results however real life situations do not always let us collect 24 h data. Thus repeated GPS surveys of 8-10 h observation sessions are still used by some research groups. Positioning solutions from shorter data spans are subject to various systematic influences, and the positioning quality as well as the estimated velocity is degraded. Researchers pay attention to the accuracy of GPS positions and of the estimated velocities derived from short observation sessions. Recently some research groups turned their attention to the study of seasonal effects (i.e. meteorological seasons) on GPS solutions. Up to now usually regional studies have been reported. In this study, we adopt a global approach and study the various seasonal effects (including the effect of the annual signal) on GPS solutions produced from short observation sessions. We use the PPP module of the NASA/JPL's GIPSY/OASIS II software and globally distributed GPS stations' data of the International GNSS Service. Accuracy studies previously performed with 10-30 consecutive days of continuous data. Here, data from each month of a year, incorporating two years in succession, is used in the analysis. Our major conclusion is that a reformulation for the GPS positioning accuracy is necessary when taking into account the seasonal effects, and typical one term accuracy formulation is expanded to a two-term one.

  5. The Paradox of Abstraction: Precision Versus Concreteness.

    PubMed

    Iliev, Rumen; Axelrod, Robert

    2016-11-22

    We introduce a novel measure of abstractness based on the amount of information of a concept computed from its position in a semantic taxonomy. We refer to this measure as precision. We propose two alternative ways to measure precision, one based on the path length from a concept to the root of the taxonomic tree, and another one based on the number of direct and indirect descendants. Since more information implies greater processing load, we hypothesize that nouns higher in precision will have a processing disadvantage in a lexical decision task. We contrast precision to concreteness, a common measure of abstractness based on the proportion of sensory-based information associated with a concept. Since concreteness facilitates cognitive processing, we predict that while both concreteness and precision are measures of abstractness, they will have opposite effects on performance. In two studies we found empirical support for our hypothesis. Precision and concreteness had opposite effects on latency and accuracy in a lexical decision task, and these opposite effects were observable while controlling for word length, word frequency, affective content and semantic diversity. Our results support the view that concepts organization includes amodal semantic structures which are independent of sensory information. They also suggest that we should distinguish between sensory-based and amount-of-information-based abstractness.

  6. Estimating sparse precision matrices

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Nikhil; White, Martin; Zhou, Harrison H.; O'Connell, Ross

    2016-08-01

    We apply a method recently introduced to the statistical literature to directly estimate the precision matrix from an ensemble of samples drawn from a corresponding Gaussian distribution. Motivated by the observation that cosmological precision matrices are often approximately sparse, the method allows one to exploit this sparsity of the precision matrix to more quickly converge to an asymptotic 1/sqrt{N_sim} rate while simultaneously providing an error model for all of the terms. Such an estimate can be used as the starting point for further regularization efforts which can improve upon the 1/sqrt{N_sim} limit above, and incorporating such additional steps is straightforward within this framework. We demonstrate the technique with toy models and with an example motivated by large-scale structure two-point analysis, showing significant improvements in the rate of convergence. For the large-scale structure example, we find errors on the precision matrix which are factors of 5 smaller than for the sample precision matrix for thousands of simulations or, alternatively, convergence to the same error level with more than an order of magnitude fewer simulations.

  7. Precision Muonium Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jungmann, Klaus P.

    2016-09-01

    The muonium atom is the purely leptonic bound state of a positive muon and an electron. It has a lifetime of 2.2 µs. The absence of any known internal structure provides for precision experiments to test fundamental physics theories and to determine accurate values of fundamental constants. In particular ground state hyperfine structure transitions can be measured by microwave spectroscopy to deliver the muon magnetic moment. The frequency of the 1s-2s transition in the hydrogen-like atom can be determined with laser spectroscopy to obtain the muon mass. With such measurements fundamental physical interactions, in particular quantum electrodynamics, can also be tested at highest precision. The results are important input parameters for experiments on the muon magnetic anomaly. The simplicity of the atom enables further precise experiments, such as a search for muonium-antimuonium conversion for testing charged lepton number conservation and searches for possible antigravity of muons and dark matter.

  8. How Physics Got Precise

    SciTech Connect

    Kleppner, Daniel

    2005-01-19

    Although the ancients knew the length of the year to about ten parts per million, it was not until the end of the 19th century that precision measurements came to play a defining role in physics. Eventually such measurements made it possible to replace human-made artifacts for the standards of length and time with natural standards. For a new generation of atomic clocks, time keeping could be so precise that the effects of the local gravitational potentials on the clock rates would be important. This would force us to re-introduce an artifact into the definition of the second - the location of the primary clock. I will describe some of the events in the history of precision measurements that have led us to this pleasing conundrum, and some of the unexpected uses of atomic clocks today.

  9. Precision gap particle separator

    DOEpatents

    Benett, William J.; Miles, Robin; Jones, II., Leslie M.; Stockton, Cheryl

    2004-06-08

    A system for separating particles entrained in a fluid includes a base with a first channel and a second channel. A precision gap connects the first channel and the second channel. The precision gap is of a size that allows small particles to pass from the first channel into the second channel and prevents large particles from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An port directs the fluid containing the entrained particles into the first channel. An output port directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.

  10. Precision manometer gauge

    DOEpatents

    McPherson, M.J.; Bellman, R.A.

    1982-09-27

    A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

  11. Precision manometer gauge

    DOEpatents

    McPherson, Malcolm J.; Bellman, Robert A.

    1984-01-01

    A precision manometer gauge which locates a zero height and a measured height of liquid using an open tube in communication with a reservoir adapted to receive the pressure to be measured. The open tube has a reference section carried on a positioning plate which is moved vertically with machine tool precision. Double scales are provided to read the height of the positioning plate accurately, the reference section being inclined for accurate meniscus adjustment, and means being provided to accurately locate a zero or reference position.

  12. Precision Heating Process

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A heat sealing process was developed by SEBRA based on technology that originated in work with NASA's Jet Propulsion Laboratory. The project involved connecting and transferring blood and fluids between sterile plastic containers while maintaining a closed system. SEBRA markets the PIRF Process to manufacturers of medical catheters. It is a precisely controlled method of heating thermoplastic materials in a mold to form or weld catheters and other products. The process offers advantages in fast, precise welding or shape forming of catheters as well as applications in a variety of other industries.

  13. Sparsity optimized compressed sensing image recovery

    NASA Astrophysics Data System (ADS)

    Wang, Sha; Chen, Yueting; Feng, Huajun; Xu, Zhihai; Li, Qi

    2014-05-01

    Training over-complete dictionaries which facilitate a sparse representation of the image leads to state-of-the-art results in compressed sensing image restoration. The training sparsity should be specified when training, while the recovering sparsity should also be set when image recovery. We find that the recovering sparsity has significant effects on the image reconstruction properties. To further improve the compressed sensing image recover accuracy, in this paper, we proposed a method by optimal estimation of the recovering sparsity according to the training sparsity to control the reconstruction method, and better reconstruction results can be achieved successfully. The method mainly includes three procedures. Firstly, forecasting the possible sparsity range by analyzing a large test data set to obtain a possible sparsity set. We find that the possible sparsity is always 3~5 times the training sparsity. Secondly, to precisely estimate the optimal recovering sparsity, we choose only several samples randomly from the compressed sensing measurements and using the sparsity candidates in the possible sparsity set to reconstruct the original image patches. Thirdly, choosing the sparsity corresponding to the best recovered result as the optimal recovering sparsity to be used in image reconstruction. The estimation computational cost is relatively small and the reconstruction result can be much better than the traditional method. The experimental results show that, the PSNR of the recovered images adopting our estimation method can be higher up to 4dB compared to the traditional method without the sparsity estimation.

  14. Aging affects neural precision of speech encoding

    PubMed Central

    Anderson, Samira; Parbery-Clark, Alexandra; White-Schwoch, Travis; Kraus, Nina

    2012-01-01

    Older adults frequently report they can hear what is said but cannot understand the meaning, especially in noise. This difficulty may arise from the inability to process rapidly changing elements of speech. Aging is accompanied by a general slowing of neural processing and decreased neural inhibition, both of which likely interfere with temporal processing in auditory and other sensory domains. Age-related reductions in inhibitory neurotransmitter levels and delayed neural recovery can contribute to decreases in the auditory system’s temporal precision. Decreased precision may lead to neural timing delays, reductions in neural response magnitude, and a disadvantage in processing the rapid acoustic changes in speech. The auditory brainstem response (ABR), a scalp-recorded electrical potential, is known for its ability to capture precise neural synchrony within subcortical auditory nuclei; therefore, we hypothesized that a loss of temporal precision results in subcortical timing delays and decreases in response consistency and magnitude. To assess this hypothesis, we recorded ABRs to the speech syllable /da/ in normal hearing younger (ages 18 to 30) and older adult humans (60 to 67). Older adults had delayed ABRs, especially in response to the rapidly changing formant transition, and greater response variability. We also found that older adults had decreased phase locking and smaller response magnitudes than younger adults. Taken together, our results support the theory that older adults have a loss of temporal precision in subcortical encoding of sound, which may account, at least in part, for their difficulties with speech perception. PMID:23055485

  15. Teaching with Precision.

    ERIC Educational Resources Information Center

    Raybould, Ted; Solity, Jonathan

    1982-01-01

    Use of precision teaching principles with learning problem students involves five steps: specifying performance, recording daily behavior, charting daily behavior, recording the teaching approach, and analyzing data. The approach has been successfully implemented through consultation of school psychologists in Walsall, England. (CL)

  16. Precision bolometer bridge

    NASA Technical Reports Server (NTRS)

    White, D. R.

    1968-01-01

    Prototype precision bolometer calibration bridge is manually balanced device for indicating dc bias and balance with either dc or ac power. An external galvanometer is used with the bridge for null indication, and the circuitry monitors voltage and current simultaneously without adapters in testing 100 and 200 ohm thin film bolometers.

  17. Precision liquid level sensor

    DOEpatents

    Field, M.E.; Sullivan, W.H.

    1985-01-29

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.

  18. Precision liquid level sensor

    DOEpatents

    Field, Michael E.; Sullivan, William H.

    1985-01-01

    A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

  19. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

  20. Astrophysics with Microarcsecond Accuracy Astrometry

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    2008-01-01

    Space-based astrometry promises to provide a powerful new tool for astrophysics. At a precision level of a few microarcsonds, a wide range of phenomena are opened up for study. In this paper we discuss the capabilities of the SIM Lite mission, the first space-based long-baseline optical interferometer, which will deliver parallaxes to 4 microarcsec. A companion paper in this volume will cover the development and operation of this instrument. At the level that SIM Lite will reach, better than 1 microarcsec in a single measurement, planets as small as one Earth can be detected around many dozen of the nearest stars. Not only can planet masses be definitely measured, but also the full orbital parameters determined, allowing study of system stability in multiple planet systems. This capability to survey our nearby stellar neighbors for terrestrial planets will be a unique contribution to our understanding of the local universe. SIM Lite will be able to tackle a wide range of interesting problems in stellar and Galactic astrophysics. By tracing the motions of stars in dwarf spheroidal galaxies orbiting our Milky Way, SIM Lite will probe the shape of the galactic potential history of the formation of the galaxy, and the nature of dark matter. Because it is flexibly scheduled, the instrument can dwell on faint targets, maintaining its full accuracy on objects as faint as V=19. This paper is a brief survey of the diverse problems in modern astrophysics that SIM Lite will be able to address.

  1. [Accuracy of HDL cholesterol measurements].

    PubMed

    Niedmann, P D; Luthe, H; Wieland, H; Schaper, G; Seidel, D

    1983-02-01

    The widespread use of different methods for the determination of HDL-cholesterol (in Europe: sodium phosphotungstic acid/MgCl2) in connection with enzymatic procedures (in the USA: heparin/MnCl2 followed by the Liebermann-Burchard method) but common reference values makes it necessary to evaluate not only accuracy, specificity, and precision of the precipitation step but also of the subsequent cholesterol determination. A high ratio of serum vs. concentrated precipitation reagent (10:1 V/V) leads to the formation of variable amounts of delta-3.5-cholestadiene. This substance is not recognized by cholesterol oxidase but leads to an 1.6 times overestimation by the Liebermann-Burchard method. Therefore, errors in HDL-cholesterol determination should be considered and differences up to 30% may occur between HDL-cholesterol values determined by the different techniques (heparin/MnCl2 - Liebermann-Burchard and NaPW/MgCl2-CHOD-PAP).

  2. High-precision positioning of radar scatterers

    NASA Astrophysics Data System (ADS)

    Dheenathayalan, Prabu; Small, David; Schubert, Adrian; Hanssen, Ramon F.

    2016-05-01

    Remote sensing radar satellites cover wide areas and provide spatially dense measurements, with millions of scatterers. Knowledge of the precise position of each radar scatterer is essential to identify the corresponding object and interpret the estimated deformation. The absolute position accuracy of synthetic aperture radar (SAR) scatterers in a 2D radar coordinate system, after compensating for atmosphere and tidal effects, is in the order of centimeters for TerraSAR-X (TSX) spotlight images. However, the absolute positioning in 3D and its quality description are not well known. Here, we exploit time-series interferometric SAR to enhance the positioning capability in three dimensions. The 3D positioning precision is parameterized by a variance-covariance matrix and visualized as an error ellipsoid centered at the estimated position. The intersection of the error ellipsoid with objects in the field is exploited to link radar scatterers to real-world objects. We demonstrate the estimation of scatterer position and its quality using 20 months of TSX stripmap acquisitions over Delft, the Netherlands. Using trihedral corner reflectors (CR) for validation, the accuracy of absolute positioning in 2D is about 7 cm. In 3D, an absolute accuracy of up to ˜ 66 cm is realized, with a cigar-shaped error ellipsoid having centimeter precision in azimuth and range dimensions, and elongated in cross-range dimension with a precision in the order of meters (the ratio of the ellipsoid axis lengths is 1/3/213, respectively). The CR absolute 3D position, along with the associated error ellipsoid, is found to be accurate and agree with the ground truth position at a 99 % confidence level. For other non-CR coherent scatterers, the error ellipsoid concept is validated using 3D building models. In both cases, the error ellipsoid not only serves as a quality descriptor, but can also help to associate radar scatterers to real-world objects.

  3. High-precision laser machining of ceramics

    NASA Astrophysics Data System (ADS)

    Toenshoff, Hans K.; von Alvensleben, Ferdinand; Graumann, Christoph; Willmann, Guido

    1998-09-01

    The increasing demand for highly developed ceramic materials for various applications calls for innovative machining technologies yielding high accuracy and efficiency. Associated problems with conventional, i.e. mechanical methods, are unacceptable tool wear as well as force induced damages on ceramic components. Furthermore, the established grinding techniques often meet their limits if accurate complex 2D or 3D structures are required. In contrast to insufficient mechanical processes, UV-laser precision machining of ceramics offers not only a valuable technological alternative but a considerable economical aspect as well. In particular, excimer lasers provide a multitude of advantages for applications in high precision and micro technology. Within the UV wavelength range and pulses emitted in the nano-second region, minimal thermal effects on ceramics and polymers are observed. Thus, the ablation geometry can be controlled precisely in the lateral and vertical directions. In this paper, the excimer laser machining technology developed at the Laser Zentrum Hannover is explained. Representing current and future industrial applications, examinations concerning the precision cutting of alumina (Al2O3), and HF-composite materials, the ablation of ferrite ceramics for precision inductors and the structuring of SiC sealing and bearing rings are presented.

  4. A passion for precision

    ScienceCinema

    None

    2016-07-12

    For more than three decades, the quest for ever higher precision in laser spectroscopy of the simple hydrogen atom has inspired many advances in laser, optical, and spectroscopic techniques, culminating in femtosecond laser optical frequency combs  as perhaps the most precise measuring tools known to man. Applications range from optical atomic clocks and tests of QED and relativity to searches for time variations of fundamental constants. Recent experiments are extending frequency comb techniques into the extreme ultraviolet. Laser frequency combs can also control the electric field of ultrashort light pulses, creating powerful new tools for the emerging field of attosecond science.Organiser(s): L. Alvarez-Gaume / PH-THNote: * Tea & coffee will be served at 16:00.

  5. A passion for precision

    SciTech Connect

    2010-05-19

    For more than three decades, the quest for ever higher precision in laser spectroscopy of the simple hydrogen atom has inspired many advances in laser, optical, and spectroscopic techniques, culminating in femtosecond laser optical frequency combs  as perhaps the most precise measuring tools known to man. Applications range from optical atomic clocks and tests of QED and relativity to searches for time variations of fundamental constants. Recent experiments are extending frequency comb techniques into the extreme ultraviolet. Laser frequency combs can also control the electric field of ultrashort light pulses, creating powerful new tools for the emerging field of attosecond science.Organiser(s): L. Alvarez-Gaume / PH-THNote: * Tea & coffee will be served at 16:00.

  6. The Precision Field Lysimeter Concept

    NASA Astrophysics Data System (ADS)

    Fank, J.

    2009-04-01

    The understanding and interpretation of leaching processes have improved significantly during the past decades. Unlike laboratory experiments, which are mostly performed under very controlled conditions (e.g. homogeneous, uniform packing of pre-treated test material, saturated steady-state flow conditions, and controlled uniform hydraulic conditions), lysimeter experiments generally simulate actual field conditions. Lysimeters may be classified according to different criteria such as type of soil block used (monolithic or reconstructed), drainage (drainage by gravity or vacuum or a water table may be maintained), or weighing or non-weighing lysimeters. In 2004 experimental investigations have been set up to assess the impact of different farming systems on groundwater quality of the shallow floodplain aquifer of the river Mur in Wagna (Styria, Austria). The sediment is characterized by a thin layer (30 - 100 cm) of sandy Dystric Cambisol and underlying gravel and sand. Three precisely weighing equilibrium tension block lysimeters have been installed in agricultural test fields to compare water flow and solute transport under (i) organic farming, (ii) conventional low input farming and (iii) extensification by mulching grass. Specific monitoring equipment is used to reduce the well known shortcomings of lysimeter investigations: The lysimeter core is excavated as an undisturbed monolithic block (circular, 1 m2 surface area, 2 m depth) to prevent destruction of the natural soil structure, and pore system. Tracing experiments have been achieved to investigate the occurrence of artificial preferential flow and transport along the walls of the lysimeters. The results show that such effects can be neglected. Precisely weighing load cells are used to constantly determine the weight loss of the lysimeter due to evaporation and transpiration and to measure different forms of precipitation. The accuracy of the weighing apparatus is 0.05 kg, or 0.05 mm water equivalent

  7. Principles and techniques for designing precision machines

    SciTech Connect

    Hale, Layton Carter

    1999-02-01

    This thesis is written to advance the reader's knowledge of precision-engineering principles and their application to designing machines that achieve both sufficient precision and minimum cost. It provides the concepts and tools necessary for the engineer to create new precision machine designs. Four case studies demonstrate the principles and showcase approaches and solutions to specific problems that generally have wider applications. These come from projects at the Lawrence Livermore National Laboratory in which the author participated: the Large Optics Diamond Turning Machine, Accuracy Enhancement of High- Productivity Machine Tools, the National Ignition Facility, and Extreme Ultraviolet Lithography. Although broad in scope, the topics go into sufficient depth to be useful to practicing precision engineers and often fulfill more academic ambitions. The thesis begins with a chapter that presents significant principles and fundamental knowledge from the Precision Engineering literature. Following this is a chapter that presents engineering design techniques that are general and not specific to precision machines. All subsequent chapters cover specific aspects of precision machine design. The first of these is Structural Design, guidelines and analysis techniques for achieving independently stiff machine structures. The next chapter addresses dynamic stiffness by presenting several techniques for Deterministic Damping, damping designs that can be analyzed and optimized with predictive results. Several chapters present a main thrust of the thesis, Exact-Constraint Design. A main contribution is a generalized modeling approach developed through the course of creating several unique designs. The final chapter is the primary case study of the thesis, the Conceptual Design of a Horizontal Machining Center.

  8. High accuracy OMEGA timekeeping

    NASA Technical Reports Server (NTRS)

    Imbier, E. A.

    1982-01-01

    The Smithsonian Astrophysical Observatory (SAO) operates a worldwide satellite tracking network which uses a combination of OMEGA as a frequency reference, dual timing channels, and portable clock comparisons to maintain accurate epoch time. Propagational charts from the U.S. Coast Guard OMEGA monitor program minimize diurnal and seasonal effects. Daily phase value publications of the U.S. Naval Observatory provide corrections to the field collected timing data to produce an averaged time line comprised of straight line segments called a time history file (station clock minus UTC). Depending upon clock location, reduced time data accuracies of between two and eight microseconds are typical.

  9. Precision disablement aiming system

    SciTech Connect

    Monda, Mark J.; Hobart, Clinton G.; Gladwell, Thomas Scott

    2016-02-16

    A disrupter to a target may be precisely aimed by positioning a radiation source to direct radiation towards the target, and a detector is positioned to detect radiation that passes through the target. An aiming device is positioned between the radiation source and the target, wherein a mechanical feature of the aiming device is superimposed on the target in a captured radiographic image. The location of the aiming device in the radiographic image is used to aim a disrupter towards the target.

  10. Ultra-Precision Optics

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Under a Joint Sponsored Research Agreement with Goddard Space Flight Center, SEMATECH, Inc., the Silicon Valley Group, Inc. and Tinsley Laboratories, known as SVG-Tinsley, developed an Ultra-Precision Optics Manufacturing System for space and microlithographic applications. Continuing improvements in optics manufacture will be able to meet unique NASA requirements and the production needs of the lithography industry for many years to come.

  11. Precision laser aiming system

    DOEpatents

    Ahrens, Brandon R.; Todd, Steven N.

    2009-04-28

    A precision laser aiming system comprises a disrupter tool, a reflector, and a laser fixture. The disrupter tool, the reflector and the laser fixture are configurable for iterative alignment and aiming toward an explosive device threat. The invention enables a disrupter to be quickly and accurately set up, aligned, and aimed in order to render safe or to disrupt a target from a standoff position.

  12. Precision orbit determination of altimetric satellites

    NASA Technical Reports Server (NTRS)

    Shum, C. K.; Ries, John C.; Tapley, Byron D.

    1994-01-01

    The ability to determine accurate global sea level variations is important to both detection and understanding of changes in climate patterns. Sea level variability occurs over a wide spectrum of temporal and spatial scales, and precise global measurements are only recently possible with the advent of spaceborne satellite radar altimetry missions. One of the inherent requirements for accurate determination of absolute sea surface topography is that the altimetric satellite orbits be computed with sub-decimeter accuracy within a well defined terrestrial reference frame. SLR tracking in support of precision orbit determination of altimetric satellites is significant. Recent examples are the use of SLR as the primary tracking systems for TOPEX/Poseidon and for ERS-1 precision orbit determination. The current radial orbit accuracy for TOPEX/Poseidon is estimated to be around 3-4 cm, with geographically correlated orbit errors around 2 cm. The significance of the SLR tracking system is its ability to allow altimetric satellites to obtain absolute sea level measurements and thereby provide a link to other altimetry measurement systems for long-term sea level studies. SLR tracking allows the production of precise orbits which are well centered in an accurate terrestrial reference frame. With proper calibration of the radar altimeter, these precise orbits, along with the altimeter measurements, provide long term absolute sea level measurements. The U.S. Navy's Geosat mission is equipped with only Doppler beacons and lacks laser retroreflectors. However, its orbits, and even the Geosat orbits computed using the available full 40-station Tranet tracking network, yield orbits with significant north-south shifts with respect to the IERS terrestrial reference frame. The resulting Geosat sea surface topography will be tilted accordingly, making interpretation of long-term sea level variability studies difficult.

  13. High Precision GPS Measurements

    DTIC Science & Technology

    2010-02-28

    troposphere delays with cm-level accuracy [15]. For example, the modified Hopfield model (MHM) has been shown to accurately calculate both the...differences between two locations near Rayleigh, North Carolina; RALR and NCRD which are part of the network of Continuously Operating Reference...Fritsche, M., R. Dietrich, A. Rulke, M. Rothacher, R. Steigenberger, “Impact of higher-order ionosphere terms on GPS-derived global network solutions

  14. Energy Recovery

    NASA Astrophysics Data System (ADS)

    1987-01-01

    The United States and other countries face the problem of waste disposal in an economical, environmentally safe manner. A widely applied solution adopted by Americans is "waste to energy," incinerating the refuse and using the steam produced by trash burning to drive an electricity producing generator. NASA's computer program PRESTO II, (Performance of Regenerative Superheated Steam Turbine Cycles), provides power engineering companies, including Blount Energy Resources Corporation of Alabama, with the ability to model such features as process steam extraction, induction and feedwater heating by external sources, peaking and high back pressure. Expansion line efficiency, exhaust loss, leakage, mechanical losses and generator losses are used to calculate the cycle heat rate. The generator output program is sufficiently precise that it can be used to verify performance quoted in turbine generator supplier's proposals.

  15. Relationship Between Magnitude of Applied Spin Recovery Moment and Ensuing Number of Recovery Turns

    NASA Technical Reports Server (NTRS)

    Anglin, Ernie L.

    1967-01-01

    An analytical study has been made to investigate the relationship between the magnitude of the applied spin recovery moment and the ensuing number of turns made during recovery from a developed spin with a view toward determining how to interpolate or extrapolate spin recovery results with regard to determining the amount of control required for a satisfactory recovery. Five configurations were used which are considered to be representative of modern airplanes: a delta-wing fighter, a stub-wing research vehicle, a boostglide configuration, a supersonic trainer, and a sweptback-wing fighter. The results obtained indicate that there is a direct relationship between the magnitude of the applied spin recovery moments and the ensuing number of recovery turns made and that this relationship can be expressed in either simple multiplicative or exponential form. Either type of relationship was adequate for interpolating or extrapolating to predict turns required for recovery with satisfactory accuracy for configurations having relatively steady recovery motions. Any two recoveries from the same developed spin condition can be used as a basis for the predicted results provided these recoveries are obtained with the same ratio of recovery control deflections. No such predictive method can be expected to give satisfactory results for oscillatory recoveries.

  16. Highly Parallel, High-Precision Numerical Integration

    SciTech Connect

    Bailey, David H.; Borwein, Jonathan M.

    2005-04-22

    This paper describes a scheme for rapidly computing numerical values of definite integrals to very high accuracy, ranging from ordinary machine precision to hundreds or thousands of digits, even for functions with singularities or infinite derivatives at endpoints. Such a scheme is of interest not only in computational physics and computational chemistry, but also in experimental mathematics, where high-precision numerical values of definite integrals can be used to numerically discover new identities. This paper discusses techniques for a parallel implementation of this scheme, then presents performance results for 1-D and 2-D test suites. Results are also given for a certain problem from mathematical physics, which features a difficult singularity, confirming a conjecture to 20,000 digit accuracy. The performance rate for this latter calculation on 1024 CPUs is 690 Gflop/s. We believe that this and one other 20,000-digit integral evaluation that we report are the highest-precision non-trivial numerical integrations performed to date.

  17. Evaluating model accuracy for model-based reasoning

    NASA Technical Reports Server (NTRS)

    Chien, Steve; Roden, Joseph

    1992-01-01

    Described here is an approach to automatically assessing the accuracy of various components of a model. In this approach, actual data from the operation of a target system is used to drive statistical measures to evaluate the prediction accuracy of various portions of the model. We describe how these statistical measures of model accuracy can be used in model-based reasoning for monitoring and design. We then describe the application of these techniques to the monitoring and design of the water recovery system of the Environmental Control and Life Support System (ECLSS) of Space Station Freedom.

  18. Accuracy of Digital vs. Conventional Implant Impressions

    PubMed Central

    Lee, Sang J.; Betensky, Rebecca A.; Gianneschi, Grace E.; Gallucci, German O.

    2015-01-01

    The accuracy of digital impressions greatly influences the clinical viability in implant restorations. The aim of this study is to compare the accuracy of gypsum models acquired from the conventional implant impression to digitally milled models created from direct digitalization by three-dimensional analysis. Thirty gypsum and 30 digitally milled models impressed directly from a reference model were prepared. The models were scanned by a laboratory scanner and 30 STL datasets from each group were imported to an inspection software. The datasets were aligned to the reference dataset by a repeated best fit algorithm and 10 specified contact locations of interest were measured in mean volumetric deviations. The areas were pooled by cusps, fossae, interproximal contacts, horizontal and vertical axes of implant position and angulation. The pooled areas were statistically analysed by comparing each group to the reference model to investigate the mean volumetric deviations accounting for accuracy and standard deviations for precision. Milled models from digital impressions had comparable accuracy to gypsum models from conventional impressions. However, differences in fossae and vertical displacement of the implant position from the gypsum and digitally milled models compared to the reference model, exhibited statistical significance (p<0.001, p=0.020 respectively). PMID:24720423

  19. Arizona Vegetation Resource Inventory (AVRI) accuracy assessment

    USGS Publications Warehouse

    Szajgin, John; Pettinger, L.R.; Linden, D.S.; Ohlen, D.O.

    1982-01-01

    A quantitative accuracy assessment was performed for the vegetation classification map produced as part of the Arizona Vegetation Resource Inventory (AVRI) project. This project was a cooperative effort between the Bureau of Land Management (BLM) and the Earth Resources Observation Systems (EROS) Data Center. The objective of the accuracy assessment was to estimate (with a precision of ?10 percent at the 90 percent confidence level) the comission error in each of the eight level II hierarchical vegetation cover types. A stratified two-phase (double) cluster sample was used. Phase I consisted of 160 photointerpreted plots representing clusters of Landsat pixels, and phase II consisted of ground data collection at 80 of the phase I cluster sites. Ground data were used to refine the phase I error estimates by means of a linear regression model. The classified image was stratified by assigning each 15-pixel cluster to the stratum corresponding to the dominant cover type within each cluster. This method is known as stratified plurality sampling. Overall error was estimated to be 36 percent with a standard error of 2 percent. Estimated error for individual vegetation classes ranged from a low of 10 percent ?6 percent for evergreen woodland to 81 percent ?7 percent for cropland and pasture. Total cost of the accuracy assessment was $106,950 for the one-million-hectare study area. The combination of the stratified plurality sampling (SPS) method of sample allocation with double sampling provided the desired estimates within the required precision levels. The overall accuracy results confirmed that highly accurate digital classification of vegetation is difficult to perform in semiarid environments, due largely to the sparse vegetation cover. Nevertheless, these techniques show promise for providing more accurate information than is presently available for many BLM-administered lands.

  20. Radiocarbon dating accuracy improved

    NASA Astrophysics Data System (ADS)

    Scientists have extended the accuracy of carbon-14 (14C) dating by correlating dates older than 8,000 years with uranium-thorium dates that span from 8,000 to 30,000 years before present (ybp, present = 1950). Edouard Bard, Bruno Hamelin, Richard Fairbanks and Alan Zindler, working at Columbia University's Lamont-Doherty Geological Observatory, dated corals from reefs off Barbados using both 14C and uranium-234/thorium-230 by thermal ionization mass spectrometry techniques. They found that the two age data sets deviated in a regular way, allowing the scientists to correlate the two sets of ages. The 14C dates were consistently younger than those determined by uranium-thorium, and the discrepancy increased to about 3,500 years at 20,000 ybp.

  1. Instrument Attitude Precision Control

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan

    2004-01-01

    A novel approach is presented in this paper to analyze attitude precision and control for an instrument gimbaled to a spacecraft subject to an internal disturbance caused by a moving component inside the instrument. Nonlinear differential equations of motion for some sample cases are derived and solved analytically to gain insight into the influence of the disturbance on the attitude pointing error. A simple control law is developed to eliminate the instrument pointing error caused by the internal disturbance. Several cases are presented to demonstrate and verify the concept presented in this paper.

  2. Precision Robotic Assembly Machine

    ScienceCinema

    None

    2016-07-12

    The world's largest laser system is the National Ignition Facility (NIF), located at Lawrence Livermore National Laboratory. NIF's 192 laser beams are amplified to extremely high energy, and then focused onto a tiny target about the size of a BB, containing frozen hydrogen gas. The target must be perfectly machined to incredibly demanding specifications. The Laboratory's scientists and engineers have developed a device called the "Precision Robotic Assembly Machine" for this purpose. Its unique design won a prestigious R&D-100 award from R&D Magazine.

  3. Precision electroweak measurements

    SciTech Connect

    Demarteau, M.

    1996-11-01

    Recent electroweak precision measurements fro {ital e}{sup +}{ital e}{sup -} and {ital p{anti p}} colliders are presented. Some emphasis is placed on the recent developments in the heavy flavor sector. The measurements are compared to predictions from the Standard Model of electroweak interactions. All results are found to be consistent with the Standard Model. The indirect constraint on the top quark mass from all measurements is in excellent agreement with the direct {ital m{sub t}} measurements. Using the world`s electroweak data in conjunction with the current measurement of the top quark mass, the constraints on the Higgs` mass are discussed.

  4. Galvanometer deflection: a precision high-speed system.

    PubMed

    Jablonowski, D P; Raamot, J

    1976-06-01

    An X-Y galvanometer deflection system capable of high precision in a random access mode of operation is described. Beam positional information in digitized form is obtained by employing a Ronchi grating with a sophisticated optical detection scheme. This information is used in a control interface to locate the beam to the required precision. The system is characterized by high accuracy at maximum speed and is designed for operation in a variable environment, with particular attention placed on thermal insensitivity.

  5. Precision Joining Center

    SciTech Connect

    Powell, J.W.; Westphal, D.A.

    1991-08-01

    A workshop to obtain input from industry on the establishment of the Precision Joining Center (PJC) was held on July 10--12, 1991. The PJC is a center for training Joining Technologists in advanced joining techniques and concepts in order to promote the competitiveness of US industry. The center will be established as part of the DOE Defense Programs Technology Commercialization Initiative, and operated by EG G Rocky Flats in cooperation with the American Welding Society and the Colorado School of Mines Center for Welding and Joining Research. The overall objectives of the workshop were to validate the need for a Joining Technologists to fill the gap between the welding operator and the welding engineer, and to assure that the PJC will train individuals to satisfy that need. The consensus of the workshop participants was that the Joining Technologist is a necessary position in industry, and is currently used, with some variation, by many companies. It was agreed that the PJC core curriculum, as presented, would produce a Joining Technologist of value to industries that use precision joining techniques. The advantage of the PJC would be to train the Joining Technologist much more quickly and more completely. The proposed emphasis of the PJC curriculum on equipment intensive and hands-on training was judged to be essential.

  6. Precision flyer initiator

    DOEpatents

    Frank, A.M.; Lee, R.S.

    1998-05-26

    A precision flyer initiator forms a substantially spherical detonation wave in a high explosive (HE) pellet. An explosive driver, such as a detonating cord, a wire bridge circuit or a small explosive, is detonated. A flyer material is sandwiched between the explosive driver and an end of a barrel that contains an inner channel. A projectile or ``flyer`` is sheared from the flyer material by the force of the explosive driver and projected through the inner channel. The flyer than strikes the HE pellet, which is supported above a second end of the barrel by a spacer ring. A gap or shock decoupling material delays the shock wave in the barrel from predetonating the HE pellet before the flyer. A spherical detonation wave is formed in the HE pellet. Thus, a shock wave traveling through the barrel fails to reach the HE pellet before the flyer strikes the HE pellet. The precision flyer initiator can be used in mining devices, well-drilling devices and anti-tank devices. 10 figs.

  7. Precision flyer initiator

    DOEpatents

    Frank, Alan M.; Lee, Ronald S.

    1998-01-01

    A precision flyer initiator forms a substantially spherical detonation wave in a high explosive (HE) pellet. An explosive driver, such as a detonating cord, a wire bridge circuit or a small explosive, is detonated. A flyer material is sandwiched between the explosive driver and an end of a barrel that contains an inner channel. A projectile or "flyer" is sheared from the flyer material by the force of the explosive driver and projected through the inner channel. The flyer than strikes the HE pellet, which is supported above a second end of the barrel by a spacer ring. A gap or shock decoupling material delays the shock wave in the barrel from predetonating the HE pellet before the flyer. A spherical detonation wave is formed in the HE pellet. Thus, a shock wave traveling through the barrel fails to reach the HE pellet before the flyer strikes the HE pellet. The precision flyer initiator can be used in mining devices, well-drilling devices and anti-tank devices.

  8. Advanced composite materials for precision segmented reflectors

    NASA Technical Reports Server (NTRS)

    Stein, Bland A.; Bowles, David E.

    1988-01-01

    The objective in the NASA Precision Segmented Reflector (PSR) project is to develop new composite material concepts for highly stable and durable reflectors with precision surfaces. The project focuses on alternate material concepts such as the development of new low coefficient of thermal expansion resins as matrices for graphite fiber reinforced composites, quartz fiber reinforced epoxies, and graphite reinforced glass. Low residual stress fabrication methods will be developed. When coupon specimens of these new material concepts have demonstrated the required surface accuracies and resistance to thermal distortion and microcracking, reflector panels will be fabricated and tested in simulated space environments. An important part of the program is the analytical modeling of environmental stability of these new composite materials concepts through constitutive equation development, modeling of microdamage in the composite matrix, and prediction of long term stability (including viscoelasticity). These analyses include both closed form and finite element solutions at the micro and macro levels.

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

    PubMed Central

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

    2015-01-01

    Despite benefits for precision, ecologists rarely use informative priors. One reason that ecologists may prefer vague priors is the perception that informative priors reduce accuracy. To date, no ecological study has empirically evaluated data-derived informative priors' effects on precision and accuracy. To determine the impacts of priors, we evaluated mortality models for tree species using data from a forest dynamics plot in Thailand. Half the models used vague priors, and the remaining half had informative priors. We found precision was greater when using informative priors, but effects on accuracy were more variable. In some cases, prior information improved accuracy, while in others, it was reduced. On average, models with informative priors were no more or less accurate than models without. Our analyses provide a detailed case study on the simultaneous effect of prior information on precision and accuracy and demonstrate that when priors are specified appropriately, they lead to greater precision without systematically reducing model accuracy. PMID:25628867

  10. Visual inspection reliability for precision manufactured parts

    DOE PAGES

    See, Judi E.

    2015-09-04

    Sandia National Laboratories conducted an experiment for the National Nuclear Security Administration to determine the reliability of visual inspection of precision manufactured parts used in nuclear weapons. In addition visual inspection has been extensively researched since the early 20th century; however, the reliability of visual inspection for nuclear weapons parts has not been addressed. In addition, the efficacy of using inspector confidence ratings to guide multiple inspections in an effort to improve overall performance accuracy is unknown. Further, the workload associated with inspection has not been documented, and newer measures of stress have not been applied.

  11. Precise and automated microfluidic sample preparation.

    SciTech Connect

    Crocker, Robert W.; Patel, Kamlesh D.; Mosier, Bruce P.; Harnett, Cindy K.

    2004-07-01

    Autonomous bio-chemical agent detectors require sample preparation involving multiplex fluid control. We have developed a portable microfluidic pump array for metering sub-microliter volumes at flowrates of 1-100 {micro}L/min. Each pump is composed of an electrokinetic (EK) pump and high-voltage power supply with 15-Hz feedback from flow sensors. The combination of high pump fluid impedance and active control results in precise fluid metering with nanoliter accuracy. Automated sample preparation will be demonstrated by labeling proteins with fluorescamine and subsequent injection to a capillary gel electrophoresis (CGE) chip.

  12. The GBT precision telescope control system

    NASA Astrophysics Data System (ADS)

    Prestage, Richard M.; Constantikes, Kim T.; Balser, Dana S.; Condon, James J.

    2004-10-01

    The NRAO Robert C. Byrd Green Bank Telescope (GBT) is a 100m diameter advanced single dish radio telescope designed for a wide range of astronomical projects with special emphasis on precision imaging. Open-loop adjustments of the active surface, and real-time corrections to pointing and focus on the basis of structural temperatures already allow observations at frequencies up to 50GHz. Our ultimate goal is to extend the observing frequency limit up to 115GHz; this will require a two dimensional tracking error better than 1.3", and an rms surface accuracy better than 210μm. The Precision Telescope Control System project has two main components. One aspect is the continued deployment of appropriate metrology systems, including temperature sensors, inclinometers, laser rangefinders and other devices. An improved control system architecture will harness this measurement capability with the existing servo systems, to deliver the precision operation required. The second aspect is the execution of a series of experiments to identify, understand and correct the residual pointing and surface accuracy errors. These can have multiple causes, many of which depend on variable environmental conditions. A particularly novel approach is to solve simultaneously for gravitational, thermal and wind effects in the development of the telescope pointing and focus tracking models. Our precision temperature sensor system has already allowed us to compensate for thermal gradients in the antenna, which were previously responsible for the largest "non-repeatable" pointing and focus tracking errors. We are currently targetting the effects of wind as the next, currently uncompensated, source of error.

  13. Recovery position - series (image)

    MedlinePlus

    ... CPR, the victim should be placed in the recovery position. The recovery position helps keep the victim's airway open. To put the victim in the recovery position grab the victim's leg and shoulder and ...

  14. Heart Attack Recovery FAQs

    MedlinePlus

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Heart Attack Recovery FAQs Updated:Sep 19,2016 Most people ... recovery. View an animation of a heart attack . Heart Attack Recovery Questions and Answers What treatments will I ...

  15. Reticence, Accuracy and Efficacy

    NASA Astrophysics Data System (ADS)

    Oreskes, N.; Lewandowsky, S.

    2015-12-01

    James Hansen has cautioned the scientific community against "reticence," by which he means a reluctance to speak in public about the threat of climate change. This may contribute to social inaction, with the result that society fails to respond appropriately to threats that are well understood scientifically. Against this, others have warned against the dangers of "crying wolf," suggesting that reticence protects scientific credibility. We argue that both these positions are missing an important point: that reticence is not only a matter of style but also of substance. In previous work, Bysse et al. (2013) showed that scientific projections of key indicators of climate change have been skewed towards the low end of actual events, suggesting a bias in scientific work. More recently, we have shown that scientific efforts to be responsive to contrarian challenges have led scientists to adopt the terminology of a "pause" or "hiatus" in climate warming, despite the lack of evidence to support such a conclusion (Lewandowsky et al., 2015a. 2015b). In the former case, scientific conservatism has led to under-estimation of climate related changes. In the latter case, the use of misleading terminology has perpetuated scientific misunderstanding and hindered effective communication. Scientific communication should embody two equally important goals: 1) accuracy in communicating scientific information and 2) efficacy in expressing what that information means. Scientists should strive to be neither conservative nor adventurous but to be accurate, and to communicate that accurate information effectively.

  16. Groves model accuracy study

    NASA Astrophysics Data System (ADS)

    Peterson, Matthew C.

    1991-08-01

    The United States Air Force Environmental Technical Applications Center (USAFETAC) was tasked to review the scientific literature for studies of the Groves Neutral Density Climatology Model and compare the Groves Model with others in the 30-60 km range. The tasking included a request to investigate the merits of comparing accuracy of the Groves Model to rocketsonde data. USAFETAC analysts found the Groves Model to be state of the art for middle-atmospheric climatological models. In reviewing previous comparisons with other models and with space shuttle-derived atmospheric densities, good density vs altitude agreement was found in almost all cases. A simple technique involving comparison of the model with range reference atmospheres was found to be the most economical way to compare the Groves Model with rocketsonde data; an example of this type is provided. The Groves 85 Model is used routinely in USAFETAC's Improved Point Analysis Model (IPAM). To create this model, Dr. Gerald Vann Groves produced tabulations of atmospheric density based on data derived from satellite observations and modified by rocketsonde observations. Neutral Density as presented here refers to the monthly mean density in 10-degree latitude bands as a function of altitude. The Groves 85 Model zonal mean density tabulations are given in their entirety.

  17. Precision Medicine in Cancer Treatment

    Cancer.gov

    Precision medicine helps doctors select cancer treatments that are most likely to help patients based on a genetic understanding of their disease. Learn about the promise of precision medicine and the role it plays in cancer treatment.

  18. Precision Joining Center

    NASA Technical Reports Server (NTRS)

    Powell, John W.

    1991-01-01

    The establishment of a Precision Joining Center (PJC) is proposed. The PJC will be a cooperatively operated center with participation from U.S. private industry, the Colorado School of Mines, and various government agencies, including the Department of Energy's Nuclear Weapons Complex (NWC). The PJC's primary mission will be as a training center for advanced joining technologies. This will accomplish the following objectives: (1) it will provide an effective mechanism to transfer joining technology from the NWC to private industry; (2) it will provide a center for testing new joining processes for the NWC and private industry; and (3) it will provide highly trained personnel to support advance joining processes for the NWC and private industry.

  19. Truss Assembly and Welding by Intelligent Precision Jigging Robots

    NASA Technical Reports Server (NTRS)

    Komendera, Erik; Dorsey, John T.; Doggett, William R.; Correll, Nikolaus

    2014-01-01

    This paper describes an Intelligent Precision Jigging Robot (IPJR) prototype that enables the precise alignment and welding of titanium space telescope optical benches. The IPJR, equipped with micron accuracy sensors and actuators, worked in tandem with a lower precision remote controlled manipulator. The combined system assembled and welded a 2 m truss from stock titanium components. The calibration of the IPJR, and the difference between the predicted and the truss dimensions as-built, identified additional sources of error that should be addressed in the next generation of IPJRs in 2D and 3D.

  20. Precision spectroscopy of hydrogen and femtosecond laser frequency combs.

    PubMed

    Hänsch, T W; Alnis, J; Fendel, P; Fischer, M; Gohle, C; Herrmann, M; Holzwarth, R; Kolachevsky, N; Udem, Th; Zimmermann, M

    2005-09-15

    Precision spectroscopy of the simple hydrogen atom has inspired dramatic advances in optical frequency metrology: femtosecond laser optical frequency comb synthesizers have revolutionized the precise measurement of optical frequencies, and they provide a reliable clock mechanism for optical atomic clocks. Precision spectroscopy of the hydrogen 1S-2S two-photon resonance has reached an accuracy of 1.4 parts in 10(14), and considerable future improvements are envisioned. Such laboratory experiments are setting new limits for possible slow variations of the fine structure constant alpha and the magnetic moment of the caesium nucleus mu(Cs) in units of the Bohr magneton mu(B).

  1. Precision Spectroscopy of Tellurium

    NASA Astrophysics Data System (ADS)

    Coker, J.; Furneaux, J. E.

    2013-06-01

    Tellurium (Te_2) is widely used as a frequency reference, largely due to the fact that it has an optical transition roughly every 2-3 GHz throughout a large portion of the visible spectrum. Although a standard atlas encompassing over 5200 cm^{-1} already exists [1], Doppler broadening present in that work buries a significant portion of the features [2]. More recent studies of Te_2 exist which do not exhibit Doppler broadening, such as Refs. [3-5], and each covers different parts of the spectrum. This work adds to that knowledge a few hundred transitions in the vicinity of 444 nm, measured with high precision in order to improve measurement of the spectroscopic constants of Te_2's excited states. Using a Fabry Perot cavity in a shock-absorbing, temperature and pressure regulated chamber, locked to a Zeeman stabilized HeNe laser, we measure changes in frequency of our diode laser to ˜1 MHz precision. This diode laser is scanned over 1000 GHz for use in a saturated-absorption spectroscopy cell filled with Te_2 vapor. Details of the cavity and its short and long-term stability are discussed, as well as spectroscopic properties of Te_2. References: J. Cariou, and P. Luc, Atlas du spectre d'absorption de la molecule de tellure, Laboratoire Aime-Cotton (1980). J. Coker et al., J. Opt. Soc. Am. B {28}, 2934 (2011). J. Verges et al., Physica Scripta {25}, 338 (1982). Ph. Courteille et al., Appl. Phys. B {59}, 187 (1994) T.J. Scholl et al., J. Opt. Soc. Am. B {22}, 1128 (2005).

  2. Mathematics for modern precision engineering.

    PubMed

    Scott, Paul J; Forbes, Alistair B

    2012-08-28

    The aim of precision engineering is the accurate control of geometry. For this reason, mathematics has a long association with precision engineering: from the calculation and correction of angular scales used in surveying and astronomical instrumentation to statistical averaging techniques used to increase precision. This study illustrates the enabling role the mathematical sciences are playing in precision engineering: modelling physical processes, instruments and complex geometries, statistical characterization of metrology systems and error compensation.

  3. Micromechanical silicon precision scale

    NASA Astrophysics Data System (ADS)

    Oja, Aarne S.; Sillanpaa, Teuvo; Seppae, H.; Kiihamaki, Jyrki; Seppala, P.; Karttunen, Jani; Riski, Kari

    2000-04-01

    A micro machined capacitive silicon scale has been designed and fabricated. It is intended for weighing masses on the order of 1 g at the resolution of about 1 ppm and below. The device consists of a micro machined SOI chip which is anodically bonded to a glass chip. The flexible electrode is formed in the SOI device layer. The other electrode is metallized on the glass and is divided into three sections. The sections are used for detecting tilting of the top electrode due to a possible off-centering of the mass load. The measuring circuit implements electrostatic force feedback and keeps the top electrode at a constant horizontal position irrespective of its mass loading. First measurements have demonstrated the stability allowing measurement of 1 g masses at an accuracy of 2...3 ppm.

  4. Precision laser automatic tracking system.

    PubMed

    Lucy, R F; Peters, C J; McGann, E J; Lang, K T

    1966-04-01

    A precision laser tracker has been constructed and tested that is capable of tracking a low-acceleration target to an accuracy of about 25 microrad root mean square. In tracking high-acceleration targets, the error is directly proportional to the angular acceleration. For an angular acceleration of 0.6 rad/sec(2), the measured tracking error was about 0.1 mrad. The basic components in this tracker, similar in configuration to a heliostat, are a laser and an image dissector, which are mounted on a stationary frame, and a servocontrolled tracking mirror. The daytime sensitivity of this system is approximately 3 x 10(-10) W/m(2); the ultimate nighttime sensitivity is approximately 3 x 10(-14) W/m(2). Experimental tests were performed to evaluate both dynamic characteristics of this system and the system sensitivity. Dynamic performance of the system was obtained, using a small rocket covered with retroreflective material launched at an acceleration of about 13 g at a point 204 m from the tracker. The daytime sensitivity of the system was checked, using an efficient retroreflector mounted on a light aircraft. This aircraft was tracked out to a maximum range of 15 km, which checked the daytime sensitivity of the system measured by other means. The system also has been used to track passively stars and the Echo I satellite. Also, the system tracked passively a +7.5 magnitude star, and the signal-to-noise ratio in this experiment indicates that it should be possible to track a + 12.5 magnitude star.

  5. Precision cosmological parameter estimation

    NASA Astrophysics Data System (ADS)

    Fendt, William Ashton, Jr.

    2009-09-01

    Experimental efforts of the last few decades have brought. a golden age to mankind's endeavor to understand tine physical properties of the Universe throughout its history. Recent measurements of the cosmic microwave background (CMB) provide strong confirmation of the standard big bang paradigm, as well as introducing new mysteries, to unexplained by current physical models. In the following decades. even more ambitious scientific endeavours will begin to shed light on the new physics by looking at the detailed structure of the Universe both at very early and recent times. Modern data has allowed us to begins to test inflationary models of the early Universe, and the near future will bring higher precision data and much stronger tests. Cracking the codes hidden in these cosmological observables is a difficult and computationally intensive problem. The challenges will continue to increase as future experiments bring larger and more precise data sets. Because of the complexity of the problem, we are forced to use approximate techniques and make simplifying assumptions to ease the computational workload. While this has been reasonably sufficient until now, hints of the limitations of our techniques have begun to come to light. For example, the likelihood approximation used for analysis of CMB data from the Wilkinson Microwave Anistropy Probe (WMAP) satellite was shown to have short falls, leading to pre-emptive conclusions drawn about current cosmological theories. Also it can he shown that an approximate method used by all current analysis codes to describe the recombination history of the Universe will not be sufficiently accurate for future experiments. With a new CMB satellite scheduled for launch in the coming months, it is vital that we develop techniques to improve the analysis of cosmological data. This work develops a novel technique of both avoiding the use of approximate computational codes as well as allowing the application of new, more precise analysis

  6. High Accuracy Wavelength Calibration For A Scanning Visible Spectrometer

    SciTech Connect

    Filippo Scotti and Ronald Bell

    2010-07-29

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies ≤ 0.2Â. An automated calibration for a scanning spectrometer has been developed to achieve a high wavelength accuracy overr the visible spectrum, stable over time and environmental conditions, without the need to recalibrate after each grating movement. The method fits all relevant spectrometer paraameters using multiple calibration spectra. With a steping-motor controlled sine-drive, accuracies of ~0.025 Â have been demonstrated. With the addition of high resolution (0.075 aresec) optical encoder on the grading stage, greater precision (~0.005 Â) is possible, allowing absolute velocity measurements with ~0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

  7. Endochronic theory of transient creep and creep recovery

    NASA Technical Reports Server (NTRS)

    Wu, H. C.; Chen, L.

    1979-01-01

    Short time creep and creep recovery were investigated by means of the endochronic theory of viscoplasticity. It is shown that the constitutive equations for constant-strain-rate stress-strain behavior, creep, creep recovery, and stress relaxation can all ber derived from the general constitutive equation by imposing appropriate constraints. In this unified approach, the effect of strain-hardening is naturally accounted for when describing creep and creep recovery. The theory predicts with reasonable accuracy the creep and creep recovery behaviors for Aluminum 1100-0 at 150 C. It was found that the strain-rate history at prestraining stage affects the subsequent creep. A critical stress was also established for creep recovery. The theory predicts a forward creep for creep recovery stress greater than the critical stress. For creep recovery stress less than the critical stress, the theory then predicts a normal strain recovery.

  8. Precision Astronomy with Imperfect Deep Depletion CCDs

    NASA Astrophysics Data System (ADS)

    Stubbs, Christopher; LSST Sensor Team; PanSTARRS Team

    2014-01-01

    While thick CCDs do provide definite advantages in terms of increased quantum efficiency at wavelengths 700 nm<λ < 1.1 microns and reduced fringing from atmospheric emission lines, these devices also exhibit undesirable features that pose a challenge to precision determination of the positions, fluxes, and shapes of astronomical objects, and for the precision extraction of features in astronomical spectra. For example, the assumptions of a perfectly rectilinear pixel grid and of an intensity-independent point spread function become increasingly invalid as we push to higher precision measurements. Many of the effects seen in these devices arise from lateral electrical fields within the detector, that produce charge transport anomalies that have been previously misinterpreted as quantum efficiency variations. Performing simplistic flat-fielding therefore introduces systematic errors in the image processing pipeline. One measurement challenge we face is devising a combination of calibration methods and algorithms that can distinguish genuine quantum efficiency variations from charge transport effects. These device imperfections also confront spectroscopic applications, such as line centroid determination for precision radial velocity studies. Given the scientific benefits of improving both the precision and accuracy of astronomical measurements, we need to identify, characterize, and overcome these various detector artifacts. In retrospect, many of the detector features first identified in thick CCDs also afflict measurements made with more traditional CCD detectors, albeit often at a reduced level since the photocharge is subject to the perturbing influence of lateral electric fields for a shorter time interval. I provide a qualitative overview of the physical effects we think are responsible for the observed device properties, and provide some perspective for the work that lies ahead.

  9. EVALUATION OF METRIC PRECISION FOR A RIPARIAN FOREST SURVEY

    EPA Science Inventory

    This paper evaluates the performance of a protocol to monitor riparian forests in western Oregon based on the quality of the data obtained from a recent field survey. Precision and accuracy are the criteria used to determine the quality of 19 field metrics. The field survey con...

  10. The Spectrum of Neurological Recovery

    PubMed Central

    Mir, Tanveer P.

    2012-01-01

    The equivalence of brain death with death is largely, although not universally accepted. Patients may have suffered insults such as cardiac arrest, vascular catastrophe, poisoning, or head trauma. Early identification of patients at greatest risk of poor neurologic outcome and management in the appropriate critical care setting is the key to maximizing neurological recovery. Recent technological advances and neuroimaging have made it possible to predict neurological reversibility with great accuracy. Significant improvements in therapy such as hypothermia, will improve outcomes in neurological catastrophies, particularly in anoxic-ischemic encephalopathy. The clinical spectrum and diagnostic criteria of minimally conscious and vegetative states is reviewed. The current understanding of the differences in prognosis and prediction of meaningful cognitive and functional recovery in each neurological state is described. Establishing an understanding of the ethical principles that guide medical decisions in clinical practice related to different neurological states is evolving into a new field called neuroethics. PMID:23610514

  11. Precise measurement of planeness.

    PubMed

    Schulz, G; Schwider, J

    1967-06-01

    Interference methods are reviewed-particularly those developed at the German Academy of Sciences in Berlin-with which the deviations of an optically flat surface from the ideal plane can be measured with a high degree of exactness. One aid to achieve this is the relative methods which measure the differences in planeness between two surfaces. These are then used in the absolute methods which determine the absolute planeness of a surface. This absolute determination can be effected in connection with a liquid surface, or (as done by the authors) only by suitable evaluation of relative measurements between unknown plates in various positional combinations. Experimentally, one uses two- or multiple-beam interference fringes of equal thickness(1) or of equal inclination. The fringes are observed visually, scanned, or photographed, and in part several wavelengths or curves of equal density (Aquidensiten) are employed. The survey also brings the following new methods: a relative method, where, with the aid of fringes of superposition, the fringe separation is subdivided equidistantly thus achieving an increase of measuring precision, and an absolute method which determines the deviations of a surface from ideal planeness along arbitrary central sections, without a liquid surface, from four relative interference photographs.

  12. Prompt and Precise Prototyping

    NASA Technical Reports Server (NTRS)

    2003-01-01

    For Sanders Design International, Inc., of Wilton, New Hampshire, every passing second between the concept and realization of a product is essential to succeed in the rapid prototyping industry where amongst heavy competition, faster time-to-market means more business. To separate itself from its rivals, Sanders Design aligned with NASA's Marshall Space Flight Center to develop what it considers to be the most accurate rapid prototyping machine for fabrication of extremely precise tooling prototypes. The company's Rapid ToolMaker System has revolutionized production of high quality, small-to-medium sized prototype patterns and tooling molds with an exactness that surpasses that of computer numerically-controlled (CNC) machining devices. Created with funding and support from Marshall under a Small Business Innovation Research (SBIR) contract, the Rapid ToolMaker is a dual-use technology with applications in both commercial and military aerospace fields. The advanced technology provides cost savings in the design and manufacturing of automotive, electronic, and medical parts, as well as in other areas of consumer interest, such as jewelry and toys. For aerospace applications, the Rapid ToolMaker enables fabrication of high-quality turbine and compressor blades for jet engines on unmanned air vehicles, aircraft, and missiles.

  13. Soviet precision timekeeping research and technology

    SciTech Connect

    Vessot, R.F.C.; Allan, D.W.; Crampton, S.J.B.; Cutler, L.S.; Kern, R.H.; McCoubrey, A.O.; White, J.D.

    1991-08-01

    This report is the result of a study of Soviet progress in precision timekeeping research and timekeeping capability during the last two decades. The study was conducted by a panel of seven US scientists who have expertise in timekeeping, frequency control, time dissemination, and the direct applications of these disciplines to scientific investigation. The following topics are addressed in this report: generation of time by atomic clocks at the present level of their technology, new and emerging technologies related to atomic clocks, time and frequency transfer technology, statistical processes involving metrological applications of time and frequency, applications of precise time and frequency to scientific investigations, supporting timekeeping technology, and a comparison of Soviet research efforts with those of the United States and the West. The number of Soviet professionals working in this field is roughly 10 times that in the United States. The Soviet Union has facilities for large-scale production of frequency standards and has concentrated its efforts on developing and producing rubidium gas cell devices (relatively compact, low-cost frequency standards of modest accuracy and stability) and atomic hydrogen masers (relatively large, high-cost standards of modest accuracy and high stability). 203 refs., 45 figs., 9 tabs.

  14. Glass ceramic ZERODUR enabling nanometer precision

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Westerhoff, Thomas

    2014-03-01

    The IC Lithography roadmap foresees manufacturing of devices with critical dimension of < 20 nm. Overlay specification of single digit nanometer asking for nanometer positioning accuracy requiring sub nanometer position measurement accuracy. The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion (CTE), the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR® to full fill the ever tighter CTE specification for wafer stepper components. In this paper we present the ZERODUR® Lithography Roadmap on the CTE metrology and tolerance. Additionally, simulation calculations based on a physical model are presented predicting the long term CTE behavior of ZERODUR® components to optimize dimensional stability of precision positioning devices. CTE data of several low thermal expansion materials are compared regarding their temperature dependence between - 50°C and + 100°C. ZERODUR® TAILORED 22°C is full filling the tight CTE tolerance of +/- 10 ppb / K within the broadest temperature interval compared to all other materials of this investigation. The data presented in this paper explicitly demonstrates the capability of ZERODUR® to enable the nanometer precision required for future generation of lithography equipment and processes.

  15. Improving the precision of astrometry for space debris

    SciTech Connect

    Sun, Rongyu; Zhao, Changyin; Zhang, Xiaoxiang

    2014-03-01

    The data reduction method for optical space debris observations has many similarities with the one adopted for surveying near-Earth objects; however, due to several specific issues, the image degradation is particularly critical, which makes it difficult to obtain precise astrometry. An automatic image reconstruction method was developed to improve the astrometry precision for space debris, based on the mathematical morphology operator. Variable structural elements along multiple directions are adopted for image transformation, and then all the resultant images are stacked to obtain a final result. To investigate its efficiency, trial observations are made with Global Positioning System satellites and the astrometry accuracy improvement is obtained by comparison with the reference positions. The results of our experiments indicate that the influence of degradation in astrometric CCD images is reduced, and the position accuracy of both objects and stellar stars is improved distinctly. Our technique will contribute significantly to optical data reduction and high-order precision astrometry for space debris.

  16. Precise Truss Assembly using Commodity Parts and Low Precision Welding

    NASA Technical Reports Server (NTRS)

    Komendera, Erik; Reishus, Dustin; Dorsey, John T.; Doggett, William R.; Correll, Nikolaus

    2013-01-01

    We describe an Intelligent Precision Jigging Robot (IPJR), which allows high precision assembly of commodity parts with low-precision bonding. We present preliminary experiments in 2D that are motivated by the problem of assembling a space telescope optical bench on orbit using inexpensive, stock hardware and low-precision welding. An IPJR is a robot that acts as the precise "jigging", holding parts of a local assembly site in place while an external low precision assembly agent cuts and welds members. The prototype presented in this paper allows an assembly agent (in this case, a human using only low precision tools), to assemble a 2D truss made of wooden dowels to a precision on the order of millimeters over a span on the order of meters. We report the challenges of designing the IPJR hardware and software, analyze the error in assembly, document the test results over several experiments including a large-scale ring structure, and describe future work to implement the IPJR in 3D and with micron precision.

  17. Precise Truss Assembly Using Commodity Parts and Low Precision Welding

    NASA Technical Reports Server (NTRS)

    Komendera, Erik; Reishus, Dustin; Dorsey, John T.; Doggett, W. R.; Correll, Nikolaus

    2014-01-01

    Hardware and software design and system integration for an intelligent precision jigging robot (IPJR), which allows high precision assembly using commodity parts and low-precision bonding, is described. Preliminary 2D experiments that are motivated by the problem of assembling space telescope optical benches and very large manipulators on orbit using inexpensive, stock hardware and low-precision welding are also described. An IPJR is a robot that acts as the precise "jigging", holding parts of a local structure assembly site in place, while an external low precision assembly agent cuts and welds members. The prototype presented in this paper allows an assembly agent (for this prototype, a human using only low precision tools), to assemble a 2D truss made of wooden dowels to a precision on the order of millimeters over a span on the order of meters. The analysis of the assembly error and the results of building a square structure and a ring structure are discussed. Options for future work, to extend the IPJR paradigm to building in 3D structures at micron precision are also summarized.

  18. [Precision nutrition in the era of precision medicine].

    PubMed

    Chen, P Z; Wang, H

    2016-12-06

    Precision medicine has been increasingly incorporated into clinical practice and is enabling a new era for disease prevention and treatment. As an important constituent of precision medicine, precision nutrition has also been drawing more attention during physical examinations. The main aim of precision nutrition is to provide safe and efficient intervention methods for disease treatment and management, through fully considering the genetics, lifestyle (dietary, exercise and lifestyle choices), metabolic status, gut microbiota and physiological status (nutrient level and disease status) of individuals. Three major components should be considered in precision nutrition, including individual criteria for sufficient nutritional status, biomarker monitoring or techniques for nutrient detection and the applicable therapeutic or intervention methods. It was suggested that, in clinical practice, many inherited and chronic metabolic diseases might be prevented or managed through precision nutritional intervention. For generally healthy populations, because lifestyles, dietary factors, genetic factors and environmental exposures vary among individuals, precision nutrition is warranted to improve their physical activity and reduce disease risks. In summary, research and practice is leading toward precision nutrition becoming an integral constituent of clinical nutrition and disease prevention in the era of precision medicine.

  19. Design of high-precision ranging system for laser fuze

    NASA Astrophysics Data System (ADS)

    Chen, Shanshan; Zhang, He; Xu, Xiaobin

    2016-10-01

    According to the problem of the high-precision ranging in the circumferential scanning probe laser proximity fuze, a new type of pulsed laser ranging system has been designed. The laser transmitting module, laser receiving module and ranging processing module have been designed respectively. The factors affecting the ranging accuracy are discussed. And the method of improving the ranging accuracy is studied. The high-precision ranging system adopts the general high performance microprocessor C8051FXXX as the core. And the time interval measurement chip TDC-GP21 was used to implement the system. A PCB circuit board was processed to carry on the experiment. The results of the experiment prove that a centimeter level accuracy ranging system has been achieved. The works can offer reference for ranging system design of the circumferential scanning probe laser proximity fuze.

  20. Precision respiratory medicine and the microbiome.

    PubMed

    Rogers, Geraint B; Wesselingh, Steve

    2016-01-01

    A decade of rapid technological advances has provided an exciting opportunity to incorporate information relating to a range of potentially important disease determinants in the clinical decision-making process. Access to highly detailed data will enable respiratory medicine to evolve from one-size-fits-all models of care, which are associated with variable clinical effectiveness and high rates of side-effects, to precision approaches, where treatment is tailored to individual patients. The human microbiome has increasingly been recognised as playing an important part in determining disease course and response to treatment. Its inclusion in precision models of respiratory medicine, therefore, is essential. Analysis of the microbiome provides an opportunity to develop novel prognostic markers for airways disease, improve definition of clinical phenotypes, develop additional guidance to aid treatment selection, and increase the accuracy of indicators of treatment effect. In this Review we propose that collaboration between researchers and clinicians is needed if respiratory medicine is to replicate the successes of precision medicine seen in other clinical specialties.

  1. Personalized Proteomics: The Future of Precision Medicine.

    PubMed

    Duarte, Trevor T; Spencer, Charles T

    2016-01-01

    Medical diagnostics and treatment has advanced from a one size fits all science to treatment of the patient as a unique individual. Currently, this is limited solely to genetic analysis. However, epigenetic, transcriptional, proteomic, posttranslational modifications, metabolic, and environmental factors influence a patient's response to disease and treatment. As more analytical and diagnostic techniques are incorporated into medical practice, the personalized medicine initiative transitions to precision medicine giving a holistic view of the patient's condition. The high accuracy and sensitivity of mass spectrometric analysis of proteomes is well suited for the incorporation of proteomics into precision medicine. This review begins with an overview of the advance to precision medicine and the current state of the art in technology and instrumentation for mass spectrometry analysis. Thereafter, it focuses on the benefits and potential uses for personalized proteomic analysis in the diagnostic and treatment of individual patients. In conclusion, it calls for a synthesis between basic science and clinical researchers with practicing clinicians to design proteomic studies to generate meaningful and applicable translational medicine. As clinical proteomics is just beginning to come out of its infancy, this overview is provided for the new initiate.

  2. Personalized Proteomics: The Future of Precision Medicine

    PubMed Central

    Duarte, Trevor T.; Spencer, Charles T.

    2016-01-01

    Medical diagnostics and treatment has advanced from a one size fits all science to treatment of the patient as a unique individual. Currently, this is limited solely to genetic analysis. However, epigenetic, transcriptional, proteomic, posttranslational modifications, metabolic, and environmental factors influence a patient’s response to disease and treatment. As more analytical and diagnostic techniques are incorporated into medical practice, the personalized medicine initiative transitions to precision medicine giving a holistic view of the patient’s condition. The high accuracy and sensitivity of mass spectrometric analysis of proteomes is well suited for the incorporation of proteomics into precision medicine. This review begins with an overview of the advance to precision medicine and the current state of the art in technology and instrumentation for mass spectrometry analysis. Thereafter, it focuses on the benefits and potential uses for personalized proteomic analysis in the diagnostic and treatment of individual patients. In conclusion, it calls for a synthesis between basic science and clinical researchers with practicing clinicians to design proteomic studies to generate meaningful and applicable translational medicine. As clinical proteomics is just beginning to come out of its infancy, this overview is provided for the new initiate. PMID:27882306

  3. Precision mass measurements of highly charged ions

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, A. A.; Bale, J. C.; Brunner, T.; Chaudhuri, A.; Chowdhury, U.; Ettenauer, S.; Frekers, D.; Gallant, A. T.; Grossheim, A.; Lennarz, A.; Mane, E.; MacDonald, T. D.; Schultz, B. E.; Simon, M. C.; Simon, V. V.; Dilling, J.

    2012-10-01

    The reputation of Penning trap mass spectrometry for accuracy and precision was established with singly charged ions (SCI); however, the achievable precision and resolving power can be extended by using highly charged ions (HCI). The TITAN facility has demonstrated these enhancements for long-lived (T1/2>=50 ms) isobars and low-lying isomers, including ^71Ge^21+, ^74Rb^8+, ^78Rb^8+, and ^98Rb^15+. The Q-value of ^71Ge enters into the neutrino cross section, and the use of HCI reduced the resolving power required to distinguish the isobars from 3 x 10^5 to 20. The precision achieved in the measurement of ^74Rb^8+, a superallowed β-emitter and candidate to test the CVC hypothesis, rivaled earlier measurements with SCI in a fraction of the time. The 111.19(22) keV isomeric state in ^78Rb was resolved from the ground state. Mass measurements of neutron-rich Rb and Sr isotopes near A = 100 aid in determining the r-process pathway. Advanced ion manipulation techniques and recent results will be presented.

  4. Accuracy Evaluation of Electron-Probe Microanalysis as Applied to Semiconductors and Silicates

    NASA Technical Reports Server (NTRS)

    Carpenter, Paul; Armstrong, John

    2003-01-01

    An evaluation of precision and accuracy will be presented for representative semiconductor and silicate compositions. The accuracy of electron-probe analysis depends on high precision measurements and instrumental calibration, as well as correction algorithms and fundamental parameter data sets. A critical assessment of correction algorithms and mass absorption coefficient data sets can be made using the alpha factor technique. Alpha factor analysis can be used to identify systematic errors in data sets and also of microprobe standards used for calibration.

  5. Apparatus Makes Precisely Saturated Solutions

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.

    1989-01-01

    Simple laboratory apparatus establishes equilibrium conditions of temperature and concentration in solutions for use in precise measurements of saturation conditions. With equipment typical measurement of saturation concentration of protein in solution established and measured within about 24 hours. Precisely saturated solution made by passing solvent or solution slowly along column packed with solute at precisely controlled temperature. If necessary, flow stopped for experimentally determined interval to allow equilibrium to be established in column.

  6. Test Expectancy Affects Metacomprehension Accuracy

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  7. Novel closed-loop approaches for precise relative navigation of widely separated GPS receivers in LEO

    NASA Astrophysics Data System (ADS)

    Tancredi, U.; Renga, A.; Grassi, M.

    2014-01-01

    This paper deals with the relative navigation of a formation of two spacecrafts separated by hundreds of kilometers based on processing dual-frequency differential carrier-phase GPS measurements. Specific requirements of the considered application are high relative positioning accuracy and real-time on board implementation. These can be conflicting requirements. Indeed, if on one hand high accuracy can be achieved by exploiting the integer nature of double-difference carrier-phase ambiguities, on the other hand the presence of large ephemeris errors and differential ionospheric delays makes the integer ambiguities determination challenging. Closed-loop schemes, which update the relative position estimates of a dynamic filter with feedback from integer ambiguities fixing algorithms, are customarily employed in these cases. This paper further elaborates such approaches, proposing novel closed loop techniques aimed at overcoming some of the limitations of traditional algorithms. They extend techniques developed for spaceborne long baseline relative positioning by making use of an on-the-fly ambiguity resolution technique especially developed for the applications of interest. Such techniques blend together ionospheric delay compensation techniques, nonlinear models of relative spacecraft dynamics, and partial integer validation techniques. The approaches are validated using flight data from the Gravity Recovery and Climate Experiment (GRACE) mission. Performance is compared to that of the traditional closed-loop scheme analyzing the capability of each scheme to maximize the percentage of correctly fixed integer ambiguities as well as the relative positioning accuracy. Results show that the proposed approach substantially improves performance of the traditional approaches. More specifically, centimeter-level root-mean square relative positioning is feasible for spacecraft separations of more than 260 km, and an integer ambiguity fixing performance as high as 98% is

  8. Centroid precision and orientation precision of planar localization microscopy.

    PubMed

    McGray, C; Copeland, C R; Stavis, S M; Geist, J

    2016-09-01

    The concept of localization precision, which is essential to localization microscopy, is formally extended from optical point sources to microscopic rigid bodies. Measurement functions are presented to calculate the planar pose and motion of microscopic rigid bodies from localization microscopy data. Physical lower bounds on the associated uncertainties - termed centroid precision and orientation precision - are derived analytically in terms of the characteristics of the optical measurement system and validated numerically by Monte Carlo simulations. The practical utility of these expressions is demonstrated experimentally by an analysis of the motion of a microelectromechanical goniometer indicated by a sparse constellation of fluorescent nanoparticles. Centroid precision and orientation precision, as developed here, are useful concepts due to the generality of the expressions and the widespread interest in localization microscopy for super-resolution imaging and particle tracking.

  9. What do we mean by accuracy in geomagnetic measurements?

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  10. Precise Orbit Solution for Swarm Using Space-Borne GPS Data and Optimized Pseudo-Stochastic Pulses

    PubMed Central

    Zhang, Bingbing; Wang, Zhengtao; Zhou, Lv; Feng, Jiandi; Qiu, Yaodong; Li, Fupeng

    2017-01-01

    Swarm is a European Space Agency (ESA) project that was launched on 22 November 2013, which consists of three Swarm satellites. Swarm precise orbits are essential to the success of the above project. This study investigates how well Swarm zero-differenced (ZD) reduced-dynamic orbit solutions can be determined using space-borne GPS data and optimized pseudo-stochastic pulses under high ionospheric activity. We choose Swarm space-borne GPS data from 1–25 October 2014, and Swarm reduced-dynamic orbits are obtained. Orbit quality is assessed by GPS phase observation residuals and compared with Precise Science Orbits (PSOs) released by ESA. Results show that pseudo-stochastic pulses with a time interval of 6 min and a priori standard deviation (STD) of 10−2 mm/s in radial (R), along-track (T) and cross-track (N) directions are optimized to Swarm ZD reduced-dynamic precise orbit determination (POD). During high ionospheric activity, the mean Root Mean Square (RMS) of Swarm GPS phase residuals is at 9–11 mm, Swarm orbit solutions are also compared with Swarm PSOs released by ESA and the accuracy of Swarm orbits can reach 2–4 cm in R, T and N directions. Independent Satellite Laser Ranging (SLR) validation indicates that Swarm reduced-dynamic orbits have an accuracy of 2–4 cm. Swarm-B orbit quality is better than those of Swarm-A and Swarm-C. The Swarm orbits can be applied to the geomagnetic, geoelectric and gravity field recovery. PMID:28335538

  11. Precise Orbit Solution for Swarm Using Space-Borne GPS Data and Optimized Pseudo-Stochastic Pulses.

    PubMed

    Zhang, Bingbing; Wang, Zhengtao; Zhou, Lv; Feng, Jiandi; Qiu, Yaodong; Li, Fupeng

    2017-03-20

    Swarm is a European Space Agency (ESA) project that was launched on 22 November 2013, which consists of three Swarm satellites. Swarm precise orbits are essential to the success of the above project. This study investigates how well Swarm zero-differenced (ZD) reduced-dynamic orbit solutions can be determined using space-borne GPS data and optimized pseudo-stochastic pulses under high ionospheric activity. We choose Swarm space-borne GPS data from 1-25 October 2014, and Swarm reduced-dynamic orbits are obtained. Orbit quality is assessed by GPS phase observation residuals and compared with Precise Science Orbits (PSOs) released by ESA. Results show that pseudo-stochastic pulses with a time interval of 6 min and a priori standard deviation (STD) of 10(-2) mm/s in radial (R), along-track (T) and cross-track (N) directions are optimized to Swarm ZD reduced-dynamic precise orbit determination (POD). During high ionospheric activity, the mean Root Mean Square (RMS) of Swarm GPS phase residuals is at 9-11 mm, Swarm orbit solutions are also compared with Swarm PSOs released by ESA and the accuracy of Swarm orbits can reach 2-4 cm in R, T and N directions. Independent Satellite Laser Ranging (SLR) validation indicates that Swarm reduced-dynamic orbits have an accuracy of 2-4 cm. Swarm-B orbit quality is better than those of Swarm-A and Swarm-C. The Swarm orbits can be applied to the geomagnetic, geoelectric and gravity field recovery.

  12. Cardiac output method comparison studies: the relation of the precision of agreement and the precision of method.

    PubMed

    Hapfelmeier, Alexander; Cecconi, Maurizio; Saugel, Bernd

    2016-04-01

    Cardiac output (CO) plays a crucial role in the hemodynamic management of critically ill patients treated in the intensive care unit and in surgical patients undergoing major surgery. In the field of cardiovascular dynamics, innovative techniques for CO determination are increasingly available. Therefore, the number of studies comparing these techniques with a reference, such as pulmonary artery thermodilution, is rapidly growing. There are mainly two outcomes of such method comparison studies: (1) the accuracy of agreement and (2) the precision of agreement. The precision of agreement depends on the precision of each method, i.e., the precision that the studied and the reference technique are able to achieve. We call this "precision of method". A decomposition of variance shows that method agreement does not only depend on the precision of method but also on another important source of variability, i.e., the method's general variability about the true values. Ignorance of that fact leads to falsified conclusions about the precision of method of the studied technique. In CO studies, serial measurements are frequently confused with repeated measurements. But as the actual CO of a subject changes from assessment to assessment, there is no real repetition of a measurement. This situation equals a scenario in which single measurements are given for multiple true values per subject. In such a case it is not possible to assess the precision of method.

  13. High current high accuracy IGBT pulse generator

    SciTech Connect

    Nesterov, V.V.; Donaldson, A.R.

    1995-05-01

    A solid state pulse generator capable of delivering high current triangular or trapezoidal pulses into an inductive load has been developed at SLAC. Energy stored in a capacitor bank of the pulse generator is switched to the load through a pair of insulated gate bipolar transistors (IGBT). The circuit can then recover the remaining energy and transfer it back to the capacitor bank without reversing the capacitor voltage. A third IGBT device is employed to control the initial charge to the capacitor bank, a command charging technique, and to compensate for pulse to pulse power losses. The rack mounted pulse generator contains a 525 {mu}F capacitor bank. It can deliver 500 A at 900V into inductive loads up to 3 mH. The current amplitude and discharge time are controlled to 0.02% accuracy by a precision controller through the SLAC central computer system. This pulse generator drives a series pair of extraction dipoles.

  14. French Meteor Network for High Precision Orbits of Meteoroids

    NASA Technical Reports Server (NTRS)

    Atreya, P.; Vaubaillon, J.; Colas, F.; Bouley, S.; Gaillard, B.; Sauli, I.; Kwon, M. K.

    2011-01-01

    There is a lack of precise meteoroids orbit from video observations as most of the meteor stations use off-the-shelf CCD cameras. Few meteoroids orbit with precise semi-major axis are available using film photographic method. Precise orbits are necessary to compute the dust flux in the Earth s vicinity, and to estimate the ejection time of the meteoroids accurately by comparing them with the theoretical evolution model. We investigate the use of large CCD sensors to observe multi-station meteors and to compute precise orbit of these meteoroids. An ideal spatial and temporal resolution to get an accuracy to those similar of photographic plates are discussed. Various problems faced due to the use of large CCD, such as increasing the spatial and the temporal resolution at the same time and computational problems in finding the meteor position are illustrated.

  15. High-precision thermal and electrical characterization of thermoelectric modules

    SciTech Connect

    Kolodner, Paul

    2014-05-15

    This paper describes an apparatus for performing high-precision electrical and thermal characterization of thermoelectric modules (TEMs). The apparatus is calibrated for operation between 20 °C and 80 °C and is normally used for measurements of heat currents in the range 0–10 W. Precision thermometry based on miniature thermistor probes enables an absolute temperature accuracy of better than 0.010 °C. The use of vacuum isolation, thermal guarding, and radiation shielding, augmented by a careful accounting of stray heat leaks and uncertainties, allows the heat current through the TEM under test to be determined with a precision of a few mW. The fractional precision of all measured parameters is approximately 0.1%.

  16. Precision analysis of passive BD aided pseudolites positioning system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoming; Zhao, Yan

    2007-11-01

    In recent years BD (BeiDou positioning system), an active satellite navigation system, has been widely applied in geodetic survey, precise engineering survey and GNC (guide, navigation and control system) of weapons because of its reliability and availability. However, it has several problems on the accuracy, anti-interference and active-positioning. A passive BD aided pseudolites positioning system is introduced in details in this paper. The configuration and the operating principle of system are presented. In analyzing the precision of location, one of the crucial aspects to be studied is how to determine the arrangement of the pseudolites to get the good GDOP, which is discussed in the different arrangements of the pseudolites in this paper. The simulation results show that the VDOP (vertical dilution of precision) of BD is improved due to introducing the pseudolites. The experiments indicate the validity of the methods and the improvement of the positioning precision in the BD aided pseudolite system.

  17. More Questions on Precision Teaching.

    ERIC Educational Resources Information Center

    Raybould, E. C.; Solity, J. E.

    1988-01-01

    Precision teaching can accelerate basic skills progress of special needs children. Issues discussed include using probes as performance tests, charting daily progress, using the charted data to modify teaching methods, determining appropriate age levels, assessing the number of students to be precision taught, and carefully allocating time. (JDD)

  18. Do Fixation Cues Ensure Fixation Accuracy in Split-Fovea Studies of Word Recognition?

    ERIC Educational Resources Information Center

    Jordan, Timothy R.; Paterson, Kevin B.; Kurtev, Stoyan; Xu, Mengyun

    2009-01-01

    Many studies have claimed that hemispheric processing is split precisely at the foveal midline and so place great emphasis on the precise location at which words are fixated. These claims are based on experiments in which a variety of fixation procedures were used to ensure fixation accuracy but the effectiveness of these procedures is unclear. We…

  19. The Accuracy of Webcams in 2D Motion Analysis: Sources of Error and Their Control

    ERIC Educational Resources Information Center

    Page, A.; Moreno, R.; Candelas, P.; Belmar, F.

    2008-01-01

    In this paper, we show the potential of webcams as precision measuring instruments in a physics laboratory. Various sources of error appearing in 2D coordinate measurements using low-cost commercial webcams are discussed, quantifying their impact on accuracy and precision, and simple procedures to control these sources of error are presented.…

  20. Precision magnetic field mapping for CERN experiment NA62

    NASA Astrophysics Data System (ADS)

    Fry, John R.; Ruggiero, Giuseppe; Bergsma, Felix

    2016-12-01

    In the CERN experiment NA62, low-mass straw-tube tracking-chambers have been designed to operate in vacuum and, in conjunction with precisely mapped magnetic fields, enable the determination of the trajectories of the charged decay products of a 75 GeV/c K+ with high accuracy. This is particularly important for the crucial measurement of the branching fraction for the decay K+ → π + ν ν, which has the potential to reveal BSM physics. The charged particles passing through the magnetic field of a dipole magnet receive a transverse-momentum kick, ΔP T = 270 MeV/c, which the physics requires to be determined to better than one part in a thousand. This puts stringent constraints on the required accuracy and precision of the magnetic field components at all points through which charged particles pass. Before reaching the dipole magnet the particles travel through an evacuated steel tank of length 90 m, where residual magnetic fields of typical size 50 μT modify the trajectories of the charged particles and require measurement with a precision of better than 10 μT. In this paper we describe in detail the different approaches to the measurement and analysis of the magnetic field for the two regions, the corrections to the raw data necessary to produce the final field map, and the physics validation procedures showing that the required accuracy and precision of the field maps have been achieved.

  1. Sources, Sinks, and Model Accuracy

    EPA Science Inventory

    Spatial demographic models are a necessary tool for understanding how to manage landscapes sustainably for animal populations. These models, therefore, must offer precise and testable predications about animal population dynamics and how animal demographic parameters respond to ...

  2. Joint Estimation of Multiple High-dimensional Precision Matrices

    PubMed Central

    Cai, T. Tony; Li, Hongzhe; Liu, Weidong; Xie, Jichun

    2017-01-01

    Motivated by analysis of gene expression data measured in different tissues or disease states, we consider joint estimation of multiple precision matrices to effectively utilize the partially shared graphical structures of the corresponding graphs. The procedure is based on a weighted constrained ℓ∞/ℓ1 minimization, which can be effectively implemented by a second-order cone programming. Compared to separate estimation methods, the proposed joint estimation method leads to estimators converging to the true precision matrices faster. Under certain regularity conditions, the proposed procedure leads to an exact graph structure recovery with a probability tending to 1. Simulation studies show that the proposed joint estimation methods outperform other methods in graph structure recovery. The method is illustrated through an analysis of an ovarian cancer gene expression data. The results indicate that the patients with poor prognostic subtype lack some important links among the genes in the apoptosis pathway.

  3. Recovery Act Milestones

    ScienceCinema

    Rogers, Matt

    2016-07-12

    Every 100 days, the Department of Energy is held accountable for a progress report on the American Recovery and Reinvestment Act. Update at 200 days, hosted by Matt Rogers, Senior Advisor to Secretary Steven Chu for Recovery Act Implementation.

  4. Recovery Act Milestones

    SciTech Connect

    Rogers, Matt

    2009-01-01

    Every 100 days, the Department of Energy is held accountable for a progress report on the American Recovery and Reinvestment Act. Update at 200 days, hosted by Matt Rogers, Senior Advisor to Secretary Steven Chu for Recovery Act Implementation.

  5. UXO Precise Position Tracking Ranger

    DTIC Science & Technology

    2008-01-01

    magnetometer or a Geonics EM-61 electromagnetic metal detector . The initial focus was on acquiring high accuracy, fixed point navigation and large area...Is integrated with Geometrics G-858 magnetometer and Geonics EM-61 electromagnetic metal detector • Provides ~20 cm positioning accuracy (1 σ

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

    PubMed Central

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

    2015-01-01

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

  7. Youth in Recovery

    ERIC Educational Resources Information Center

    de Miranda, John; Williams, Greg

    2011-01-01

    Young people are entering long-term recovery probably in greater numbers than ever before. A key word here is "probably" because we know precious little about the phenomenon of young people who recover from alcohol and drug addition. This article is a preliminary exploration of youth in recovery. It reviews several types of recovery support…

  8. What Is "No Recovery?"

    ERIC Educational Resources Information Center

    Kauffman, Jeffrey

    2008-01-01

    Thanatologists, as Balk recently commented (Balk, 2004), have been saying that there is no recovery from bereavement, or that we should not speak of bereavement as leading to a recovery. The term recovery has a high level of plasticity and can be shaped to fit diverse meanings, including contradictory meanings. We will sort our way through some of…

  9. Enhanced oil recovery update

    SciTech Connect

    Smith, R.V

    1989-03-01

    Technology continues to grow in the realm of enhanced oil recovery. Since 1950 several processes have proven economic for oil recovery. Others are still in their infancy and must be custom designed for each reservoir. This paper gives a general overview of these processes. The author focuses on the latest technology and the outlook for enhanced oil recovery operations.

  10. State of the Field: Extreme Precision Radial Velocities

    NASA Astrophysics Data System (ADS)

    Fischer, Debra A.; Anglada-Escude, Guillem; Arriagada, Pamela; Baluev, Roman V.; Bean, Jacob L.; Bouchy, Francois; Buchhave, Lars A.; Carroll, Thorsten; Chakraborty, Abhijit; Crepp, Justin R.; Dawson, Rebekah I.; Diddams, Scott A.; Dumusque, Xavier; Eastman, Jason D.; Endl, Michael; Figueira, Pedro; Ford, Eric B.; Foreman-Mackey, Daniel; Fournier, Paul; Fűrész, Gabor; Gaudi, B. Scott; Gregory, Philip C.; Grundahl, Frank; Hatzes, Artie P.; Hébrard, Guillaume; Herrero, Enrique; Hogg, David W.; Howard, Andrew W.; Johnson, John A.; Jorden, Paul; Jurgenson, Colby A.; Latham, David W.; Laughlin, Greg; Loredo, Thomas J.; Lovis, Christophe; Mahadevan, Suvrath; McCracken, Tyler M.; Pepe, Francesco; Perez, Mario; Phillips, David F.; Plavchan, Peter P.; Prato, Lisa; Quirrenbach, Andreas; Reiners, Ansgar; Robertson, Paul; Santos, Nuno C.; Sawyer, David; Segransan, Damien; Sozzetti, Alessandro; Steinmetz, Tilo; Szentgyorgyi, Andrew; Udry, Stéphane; Valenti, Jeff A.; Wang, Sharon X.; Wittenmyer, Robert A.; Wright, Jason T.

    2016-06-01

    The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of the art Doppler precision and identified the critical path challenges for reaching 10 cm s-1 measurement precision. The presentations and discussion of key issues for instrumentation and data analysis and the workshop recommendations for achieving this bold precision are summarized here. Beginning with the High Accuracy Radial Velocity Planet Searcher spectrograph, technological advances for precision radial velocity (RV) measurements have focused on building extremely stable instruments. To reach still higher precision, future spectrometers will need to improve upon the state of the art, producing even higher fidelity spectra. This should be possible with improved environmental control, greater stability in the illumination of the spectrometer optics, better detectors, more precise wavelength calibration, and broader bandwidth spectra. Key data analysis challenges for the precision RV community include distinguishing center of mass (COM) Keplerian motion from photospheric velocities (time correlated noise) and the proper treatment of telluric contamination. Success here is coupled to the instrument design, but also requires the implementation of robust statistical and modeling techniques. COM velocities produce Doppler shifts that affect every line identically, while photospheric velocities produce line profile asymmetries with wavelength and temporal dependencies that are different from Keplerian signals. Exoplanets are an important subfield of astronomy and there has been an impressive rate of discovery over the past two decades. However, higher precision RV measurements are required to serve as a discovery technique for potentially habitable worlds, to confirm and characterize detections from transit missions, and to provide mass measurements for other space-based missions. The future of exoplanet science has very different trajectories depending on the precision that can

  11. High Accuracy Time Transfer Synchronization

    DTIC Science & Technology

    1994-12-01

    HIGH ACCURACY TIME TRANSFER SYNCHRONIZATION Paul Wheeler, Paul Koppang, David Chalmers, Angela Davis, Anthony Kubik and William Powell U.S. Naval...Observatory Washington, DC 20392 Abstract In July 1994, the US Naval Observatory (USNO) Time Service System Engineering Division conducted a...field test to establish a baseline accuracy for two-way satellite time transfer synchro- nization. Three Hewlett-Packard model 5071 high performance

  12. Process Analysis Via Accuracy Control

    DTIC Science & Technology

    1982-02-01

    0 1 4 3 NDARDS THE NATIONAL February 1982 Process Analysis Via Accuracy Control RESEARCH PROG RAM U.S. DEPARTMENT OF TRANSPORTATION Maritime...SUBTITLE Process Analysis Via Accuracy Control 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...examples are contained in Appendix C. Included, are examples of how “A/C” process - analysis leads to design improvement and how a change in sequence can

  13. Angular MET sensor for precise azimuth determination

    NASA Astrophysics Data System (ADS)

    Zaitsev, Dmitry; Antonov, Alexander; Krishtop, Vladimir

    2016-12-01

    This paper describes using a MET-based low-noise angular motion sensor to precisely determine azimuth direction in a dynamic-scheme method of measuring Earth's rotation velocity vector. The scheme includes installing a sensor on a rotating platform so that it could scan a space and seek for the position of highest Earth's rotation vector projection on its axis. This method is very efficient provided a low-noise sensor is used. We take a low-cost angular sensor based on MET (molecular electronic transduction) technology. Sensors of this kind were originally developed for the seismic activity monitoring and are well-known for very good noise performance and high sensitivity. This approach, combined with use of special signal processing algorithms, allowed for reaching the accuracy of 0.07° for a measurement time of 200 seconds.

  14. Composite materials for precision space reflector panels

    NASA Technical Reports Server (NTRS)

    Tompkins, Stephen S.; Funk, Joan G.; Bowles, David E.; Towell, Timothy W.; Connell, John W.

    1992-01-01

    One of the critical technology needs of large precision reflectors for future astrophysical and optical communications satellites lies in the area of structural materials. Results from a materials research and development program at NASA Langley Research Center to provide materials for these reflector applications are discussed. Advanced materials that meet the reflector panel requirements are identified, and thermal, mechanical and durability properties of candidate materials after exposure to simulated space environments are compared. A parabolic, graphite-phenolic honeycomb composite panel having a surface accuracy of 70.8 microinches rms and an areal weight of 1.17 lbm/sq ft was fabricated with T50/ERL1962 facesheets, a PAEI thermoplastic surface film, and Al and SiO(x) coatings.

  15. Sfermion precision measurements at a linear collider

    SciTech Connect

    A. Freitas et al.

    2003-09-25

    At future e{sup +}e{sup -} linear colliders, the event rates and clean signals of scalar fermion production--in particular for the scalar leptons--allow very precise measurements of their masses and couplings and the determination of their quantum numbers. Various methods are proposed for extracting these parameters from the data at the sfermion thresholds and in the continuum. At the same time, NLO radiative corrections and non-zero width effects have been calculated in order to match the experimental accuracy. The substantial mixing expected for the third generation sfermions opens up additional opportunities. Techniques are presented for determining potential CP-violating phases and for extracting tan {beta} from the stau sector, in particular at high values. The consequences of possible large mass differences in the stop and sbottom system are explored in dedicated analyses.

  16. Precision of sensing, memory and fluctuating environments

    NASA Astrophysics Data System (ADS)

    Aquino, Gerardo; Endres, Robert

    2012-02-01

    Multiple cell types were recently shown to sense their chemical environment with astonishing accuracy, crucial for nutrient scavenging, mating, immune response, and development. It is currently unknown if this sensing near the single-molecule detection limit is due to highly precise single measurements, or due to learning over time. In this work, we analyze if cell memory can allow cells to sense beyond the current estimates of the fundamental physical limit. By merging Bayesian inference with information theoretic concepts, we derive analytical formulas which show that memory improves sensing in correlated fluctuating environments, but not in strongly uncorrelated environments. Despite many analogies with problem solving strategies in engineering, our theory shows fundamental differences in interpreting noisy stimuli in the microscopic and macroscopic world.

  17. Improvement of the precision of lattice parameter determination by nano-beam electron diffraction.

    PubMed

    Saitoh, Koh; Nakahara, Hirotaka; Tanaka, Nobuo

    2013-01-01

    A highly precise determination of lattice parameters using higher-order Laue zone (HOLZ) reflections observed in nano-beam electron diffraction is presented. The introduction of more than 40 HOLZ reflections, whose positions are corrected by considering the aberration of the electron optics and are determined with an accuracy of 0.04 nm⁻¹, allows us to achieve a remarkable high precision of a 0.02% error, which is four times higher than the precision without HOLZ reflections.

  18. On Comparing Precision Orbit Solutions of Geodetic Satellites Given Several Atmospheric Density Models

    DTIC Science & Technology

    2014-08-01

    Preprint) AAS 15-752 ON COMPARING PRECISION ORBIT SOLUTIONS OF GEODETIC SATELLITES GIVEN SEVERAL ATMOSPHERIC DENSITY MODELS John G. Warner∗, Krysta...tool. High precision laser ranging data to geodetic satellites were used as test cases to evaluate the solution accuracy and predictive capabilities...2014 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE On Comparing Precision Orbit Solutions of Geodetic Satellites Given Several

  19. Electromagnetic Real-Time Tumor Position Monitoring and Dynamic Multileaf Collimator Tracking Using a Siemens 160 MLC: Geometric and Dosimetric Accuracy of an Integrated System

    SciTech Connect

    Krauss, Andreas; Nill, Simeon; Tacke, Martin; Oelfke, Uwe

    2011-02-01

    Purpose: Dynamic multileaf collimator tracking represents a promising method for high-precision radiotherapy to moving tumors. In the present study, we report on the integration of electromagnetic real-time tumor position monitoring into a multileaf collimator-based tracking system. Methods and Materials: The integrated system was characterized in terms of its geometric and radiologic accuracy. The former was assessed from portal images acquired during radiation delivery to a phantom in tracking mode. The tracking errors were calculated from the positions of the tracking field and of the phantom as extracted from the portal images. Radiologic accuracy was evaluated from film dosimetry performed for conformal and intensity-modulated radiotherapy applied to different phantoms moving on sinusoidal trajectories. A static radiation delivery to the nonmoving target served as a reference for the delivery to the moving phantom with and without tracking applied. Results: Submillimeter tracking accuracy was observed for two-dimensional target motion despite the relatively large system latency of 500 ms. Film dosimetry yielded almost complete recovery of a circular dose distribution with tracking in two dimensions applied: 2%/2 mm gamma-failure rates could be reduced from 59.7% to 3.3%. For single-beam intensity-modulated radiotherapy delivery, accuracy was limited by the finite leaf width. A 2%/2 mm gamma-failure rate of 15.6% remained with tracking applied. Conclusion: The integrated system we have presented marks a major step toward the clinical implementation of high-precision dynamic multileaf collimator tracking. However, several challenges such as irregular motion traces or a thorough quality assurance still need to be addressed.

  20. All-digital precision processing of ERTS images

    NASA Technical Reports Server (NTRS)

    Bernstein, R. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Digital techniques have been developed and used to apply precision-grade radiometric and geometric corrections to ERTS MSS and RBV scenes. Geometric accuracies sufficient for mapping at 1:250,000 scale have been demonstrated. Radiometric quality has been superior to ERTS NDPF precision products. A configuration analysis has shown that feasible, cost-effective all-digital systems for correcting ERTS data are easily obtainable. This report contains a summary of all results obtained during this study and includes: (1) radiometric and geometric correction techniques, (2) reseau detection, (3) GCP location, (4) resampling, (5) alternative configuration evaluations, and (6) error analysis.

  1. On Issues of Precision for Hardware-based Volume Visualization

    SciTech Connect

    LaMar, E C

    2003-04-11

    This paper discusses issues with the limited precision of hardware-based volume visualization. We will describe the compositing OVER operator and how fixed-point arithmetic affects it. We propose two techniques to improve the precision of fixed-point compositing and the accuracy of hardware-based volume visualization. The first technique is to perform dithering of color and alpha values. The second technique we call exponent-factoring, and captures significantly more numeric resolution than dithering, but can only produce monochromatic images.

  2. A Comparison of three high-precision quadrature schemes

    SciTech Connect

    Bailey, David H.; Li, Xiaoye S.

    2003-07-01

    The authors have implemented three numerical quadrature schemes, using the new Arbitrary Precision (ARPREC) software package, with the objective of seeking a completely ''automatic'' arbitrary precision quadrature facility, namely one that does not rely on a priori information of the function to be integrated. Such a facility is required, for example, to permit the experimental identification of definite integrals based on their numerical values. The performance and accuracy of these three quadrature schemes are compared using a suite of 15 integrals, ranging from continuous, well-behaved functions on finite intervals to functions with vertical derivatives and integrable singularities at endpoints, as well as several integrals on an infinite interval.

  3. Ultra-rare Disease and Genomics-Driven Precision Medicine

    PubMed Central

    Lee, Sangmoon

    2016-01-01

    Since next-generation sequencing (NGS) technique was adopted into clinical practices, revolutionary advances in diagnosing rare genetic diseases have been achieved through translating genomic medicine into precision or personalized management. Indeed, several successful cases of molecular diagnosis and treatment with personalized or targeted therapies of rare genetic diseases have been reported. Still, there are several obstacles to be overcome for wider application of NGS-based precision medicine, including high sequencing cost, incomplete variant sensitivity and accuracy, practical complexities, and a shortage of available treatment options. PMID:27445646

  4. A precision synchrotron radiation detector using phosphorescent screens

    SciTech Connect

    Jung, C.K.; Lateur, M.; Nash, J.; Tinsman, J. ); Butler, J. ); Wormser, G. . Lab. de l'Accelerateur Lineaire); Levi, M.; Rouse, F. )

    1990-01-01

    A precision detector to measure synchrotron radiation beam positions has been designed and installed as part of beam energy spectrometers at the Stanford Linear Collider (SLC). The distance between pairs of synchrotron radiation beams is measured absolutely to better than 28 {mu}m on a pulse-to-pulse basis. This contributes less than 5 MeV to the error in the measurement of SLC beam energies (approximately 50 GeV). A system of high-resolution video cameras viewing precisely aligned fiducial wire arrays overlaying phosphorescent screens has achieved this accuracy. 3 refs., 5 figs., 1 tab.

  5. Precise Editing of the Zebrafish Genome Made Simple and Efficient

    PubMed Central

    Hoshijima, Kazuyuki; Jurynec, Michael J.; Grunwald, David Jonah

    2016-01-01

    SUMMARY We present simple and efficient methods for creating heritable modifications of the zebrafish genome. Precisely modified alleles are generated by homologous recombination between the host genome and dsDNA donor molecules, stimulated by the induction of chromosomally targeted DSBs. Several kilobase-long tracts of genome sequence can be replaced. Tagging donor sequences with reporter genes that can be subsequently excised improves recovery of edited alleles by an order of magnitude and facilitates recovery of recessive and phenotypically silent conditional mutations. We generate and demonstrate functionality of: i) alleles with a single codon change, ii) an allele encoding an epitope-tagged version of an endogenous protein, iii) alleles expressing reporter proteins, and iv) a conditional allele in which an exon is flanked by recombinogenic loxP sites. Our methods make recovery of a broad range of genome editing events very practicable, significantly advancing applicability of the zebrafish for studying normal biological processes and modeling diseases. PMID:27003937

  6. Simulation of Local Tie Accuracy on VLBI Antennas

    NASA Technical Reports Server (NTRS)

    Kallio, Ulla; Poutanen, Markku

    2010-01-01

    We introduce a new mathematical model to compute the centering parameters of a VLBI antenna. These include the coordinates of the reference point, axis offset, orientation, and non-perpendicularity of the axes. Using the model we simulated how precisely parameters can be computed in different cases. Based on the simulation we can give some recommendations and practices to control the accuracy and reliability of the local ties at the VLBI sites.

  7. Precision Instrument and Equipment Repairers.

    ERIC Educational Resources Information Center

    Wyatt, Ian

    2001-01-01

    Explains the job of precision instrument and equipment repairers, who work on cameras, medical equipment, musical instruments, watches and clocks, and industrial measuring devices. Discusses duties, working conditions, employment and earnings, job outlook, and skills and training. (JOW)

  8. Battleground Energy Recovery Project

    SciTech Connect

    Bullock, Daniel

    2011-12-31

    In October 2009, the project partners began a 36-month effort to develop an innovative, commercial-scale demonstration project incorporating state-of-the-art waste heat recovery technology at Clean Harbors, Inc., a large hazardous waste incinerator site located in Deer Park, Texas. With financial support provided by the U.S. Department of Energy, the Battleground Energy Recovery Project was launched to advance waste heat recovery solutions into the hazardous waste incineration market, an area that has seen little adoption of heat recovery in the United States. The goal of the project was to accelerate the use of energy-efficient, waste heat recovery technology as an alternative means to produce steam for industrial processes. The project had three main engineering and business objectives: Prove Feasibility of Waste Heat Recovery Technology at a Hazardous Waste Incinerator Complex; Provide Low-cost Steam to a Major Polypropylene Plant Using Waste Heat; and Create a Showcase Waste Heat Recovery Demonstration Project.

  9. Precision radiotherapy for brain tumors

    PubMed Central

    Yan, Ying; Guo, Zhanwen; Zhang, Haibo; Wang, Ning; Xu, Ying

    2012-01-01

    OBJECTIVE: Precision radiotherapy plays an important role in the management of brain tumors. This study aimed to identify global research trends in precision radiotherapy for brain tumors using a bibliometric analysis of the Web of Science. DATA RETRIEVAL: We performed a bibliometric analysis of data retrievals for precision radiotherapy for brain tumors containing the key words cerebral tumor, brain tumor, intensity-modulated radiotherapy, stereotactic body radiation therapy, stereotactic ablative radiotherapy, imaging-guided radiotherapy, dose-guided radiotherapy, stereotactic brachytherapy, and stereotactic radiotherapy using the Web of Science. SELECTION CRITERIA: Inclusion criteria: (a) peer-reviewed articles on precision radiotherapy for brain tumors which were published and indexed in the Web of Science; (b) type of articles: original research articles and reviews; (c) year of publication: 2002-2011. Exclusion criteria: (a) articles that required manual searching or telephone access; (b) Corrected papers or book chapters. MAIN OUTCOME MEASURES: (1) Annual publication output; (2) distribution according to country; (3) distribution according to institution; (4) top cited publications; (5) distribution according to journals; and (6) comparison of study results on precision radiotherapy for brain tumors. RESULTS: The stereotactic radiotherapy, intensity-modulated radiotherapy, and imaging-guided radiotherapy are three major methods of precision radiotherapy for brain tumors. There were 260 research articles addressing precision radiotherapy for brain tumors found within the Web of Science. The USA published the most papers on precision radiotherapy for brain tumors, followed by Germany and France. European Synchrotron Radiation Facility, German Cancer Research Center and Heidelberg University were the most prolific research institutes for publications on precision radiotherapy for brain tumors. Among the top 13 research institutes publishing in this field, seven

  10. Precise Point Positioning with Partial Ambiguity Fixing.

    PubMed

    Li, Pan; Zhang, Xiaohong

    2015-06-10

    Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. Subsequently the success rate and ratio-test are simultaneously used in an iterative process to increase the possibility of finding a subset of decorrelated ambiguities which can be fixed with high confidence. One can apply the proposed PAR method to try to achieve an ambiguity-fixed solution when full ambiguity resolution (FAR) fails. We validate this method using data from 450 stations during DOY 021 to 027, 2012. Results demonstrate the proposed PAR method can significantly shorten the time to first fix (TTFF) and increase the fixing rate. Compared with FAR, the average TTFF for PAR is reduced by 14.9% for static PPP and 15.1% for kinematic PPP. Besides, using the PAR method, the average fixing rate can be increased from 83.5% to 98.2% for static PPP, from 80.1% to 95.2% for kinematic PPP respectively. Kinematic PPP accuracy with PAR can also be significantly improved, compared to that with FAR, due to a higher fixing rate.

  11. High precision innovative micropump for artificial pancreas

    NASA Astrophysics Data System (ADS)

    Chappel, E.; Mefti, S.; Lettieri, G.-L.; Proennecke, S.; Conan, C.

    2014-03-01

    The concept of artificial pancreas, which comprises an insulin pump, a continuous glucose meter and a control algorithm, is a major step forward in managing patient with type 1 diabetes mellitus. The stability of the control algorithm is based on short-term precision micropump to deliver rapid-acting insulin and to specific integrated sensors able to monitor any failure leading to a loss of accuracy. Debiotech's MEMS micropump, based on the membrane pump principle, is made of a stack of 3 silicon wafers. The pumping chamber comprises a pillar check-valve at the inlet, a pumping membrane which is actuated against stop limiters by a piezo cantilever, an anti-free-flow outlet valve and a pressure sensor. The micropump inlet is tightly connected to the insulin reservoir while the outlet is in direct communication with the patient skin via a cannula. To meet the requirement of a pump dedicated to closed-loop application for diabetes care, in addition to the well-controlled displacement of the pumping membrane, the high precision of the micropump is based on specific actuation profiles that balance effect of pump elasticity in low-consumption push-pull mode.

  12. LLNL/Lion Precision LVDT amplifier

    SciTech Connect

    Hopkins, D.J.

    1994-04-01

    A high-precision, low-noise, LVDT amplifier has been developed which is a significant advancement on the current state of the art in contact displacement measurement. This amplifier offers the dynamic range of a typical LVDT probe but with a resolution that rivals that of non contact displacement measuring systems such as capacitance gauges and laser interferometers. Resolution of 0.1 {mu} in with 100 Hz bandwidth is possible. This level of resolution is over an order of magnitude greater than what is now commercially available. A front panel switch can reduce the bandwidth to 2.5 Hz and attain a resolution of 0.025 {mu} in. This level of resolution meets or exceeds that of displacement measuring laser interferometry or capacitance gauge systems. Contact displacement measurement offers high part spatial resolution and therefore can measure not only part contour but surface finish. Capacitance gauges and displacement laser interferometry offer poor part spatial resolution and can not provide good surface finish measurements. Machine tool builders, meteorologists and quality inspection departments can immediately utilize the higher accuracy and capabilities that this amplifier offers. The precision manufacturing industry can improve as a result of improved capability to measure parts that help reduce costs and minimize material waste.

  13. Precise Point Positioning with Partial Ambiguity Fixing

    PubMed Central

    Li, Pan; Zhang, Xiaohong

    2015-01-01

    Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. Subsequently the success rate and ratio-test are simultaneously used in an iterative process to increase the possibility of finding a subset of decorrelated ambiguities which can be fixed with high confidence. One can apply the proposed PAR method to try to achieve an ambiguity-fixed solution when full ambiguity resolution (FAR) fails. We validate this method using data from 450 stations during DOY 021 to 027, 2012. Results demonstrate the proposed PAR method can significantly shorten the time to first fix (TTFF) and increase the fixing rate. Compared with FAR, the average TTFF for PAR is reduced by 14.9% for static PPP and 15.1% for kinematic PPP. Besides, using the PAR method, the average fixing rate can be increased from 83.5% to 98.2% for static PPP, from 80.1% to 95.2% for kinematic PPP respectively. Kinematic PPP accuracy with PAR can also be significantly improved, compared to that with FAR, due to a higher fixing rate. PMID:26067196

  14. Compact, Precise Inertial Rotation Sensors for Spacecraft

    NASA Technical Reports Server (NTRS)

    Rosing, David; Oseas, Jeffrey; Korechoff, Robert

    2006-01-01

    A document describes a concept for an inertial sensor for measuring the rotation of an inertially stable spacecraft around its center of gravity to within 100 microarcseconds or possibly even higher precision. Whereas a current proposal for a spacecraft-rotation sensor of this accuracy requires one spacecraft dimension on the order of ten meters, a sensor according to this proposal could fit within a package smaller than 1 meter and would have less than a tenth of the mass. According to the concept, an inertial mass and an apparatus for monitoring the mass would be placed at some known distance from the center of gravity so that any rotation of the spacecraft would cause relative motion between the mass and the spacecraft. The relative motion would be measured and, once the displacement of the mass exceeded a prescribed range, a precisely monitored restoring force would be applied to return the mass to a predetermined position. Measurements of the relative motion and restoring force would provide information on changes in the attitude of the spacecraft. A history of relative motion and restoring-force measurements could be kept, enabling determination of the cumulative change in attitude during the observation time.

  15. Precision Timed Infrastructure: Design Challenges

    DTIC Science & Technology

    2013-09-19

    recognized the need to precisely model and control time. Mod- elica [30], Simulink [28], and Ptolemy II [12] can precisely model time in both physical and...languages have different ways of expressing computations and timing constraints [5]. For instance, Mod- elica [30], Simulink [28], Giotto [17], Ptolemy ...Languages Intermediate Languages Assembly Languages Modelica Ptolemy IIGiotto and E machine Modelyze PRET Compilation Hide machine dependent details

  16. Fundamental Physics and Precision Measurements

    NASA Astrophysics Data System (ADS)

    Hänsch, T. W.

    2006-11-01

    "Very high precision physics has always appealed to me. The steady improvement in technologies that afford higher and higher precision has been a regular source of excitement and challenge during my career. In science, as in most things, whenever one looks at something more closely, new aspects almost always come into play …" With these word from the book "How the Laser happened", Charles H. Townes expresses a passion for precision that is now shared by many scientists. Masers and lasers have become indispensible tools for precision measurements. During the past few years, the advent of femtosecond laser frequency comb synthesizers has revolutionized the art of directly comparing optical and microwave frequencies. Inspired by the needs of precision laser spectroscopy of the simple hydrogen atom, such frequency combs are now enabling ultra-precise spectroscopy over wide spectral ranges. Recent laboratory experiments are already setting stringent limits for possible slow variations of fundamental constants. Laser frequency combs also provide the long missing clockwork for optical atomic clocks that may ultimately reach a precision of parts in 1018 and beyond. Such tools will open intriguing new opportunities for fundamental experiments including new tests of special and general relativity. In the future, frequency comb techniques may be extended into the extreme ultraviolet and soft xray regime, opening a vast new spectral territory to precision measurements. Frequency combs have also become a key tool for the emerging new field of attosecond science, since they can control the electric field of ultrashort laser pulses on an unprecedented time scale. The biggest surprise in these endeavours would be if we found no surprise.

  17. Disruptive advancement in precision lens mounting

    NASA Astrophysics Data System (ADS)

    Lamontagne, Frédéric; Desnoyers, Nichola; Doucet, Michel; Côté, Patrice; Gauvin, Jonny; Anctil, Geneviève

    2015-09-01

    Threaded rings are used to fix lenses in a large portion of opto-mechanical assemblies. This is the case for the low cost drop-in approach in which the lenses are dropped into cavities cut into a barrel and clamped with threaded rings. The walls of a cavity are generally used to constrain the lateral and axial position of the lens within the cavity. In general, the drop-in approach is low cost but imposes fundamental limitations especially on the optical performances. On the other hand, active alignment methods provide a high level of centering accuracy but increase the cost of the optical assembly. This paper first presents a review of the most common lens mounting techniques used to secure and center lenses in optical systems. Advantages and disadvantages of each mounting technique are discussed in terms of precision and cost. Then, the different contributors which affect the centering of a lens when using the drop-in approach, such as the threaded ring, friction, and manufacturing errors, are detailed. Finally, a patent pending lens mounting technique developed at INO that alleviates the drawbacks of the drop-in and the active alignment approaches is introduced. This innovative auto-centering method requires a very low assembly time, does not need tight manufacturing tolerances and offers a very high level of centering accuracy, usually less than 5 μm. Centering test results performed on real optical assemblies are also presented.

  18. Precision of spiral-bevel gears

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1983-01-01

    The kinematic errors in spiral bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gears during assembly, and by eccentricity of the assembled gears were determined. One mathematical model corresponds to the motion of the contact ellipse across the tooth surface, (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: (1) kinematic errors induced by errors of manufacture may be minimized by applying special machine settings, the original error may be reduced by order of magnitude, the procedure is most effective for geometry 2 gears, (2) when trying to adjust the bearing contact pattern between the gear teeth for geometry I gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially; (3) the kinematic accuracy of spiral bevel drives are most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The precision of mounting accuracy and manufacture are most crucial for the gear, and less so for the pinion. Previously announced in STAR as N82-30552

  19. Precision of spiral-bevel gears

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1982-01-01

    The kinematic errors in spiral bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gears during assembly, and by eccentricity of the assembled gears were determined. One mathematical model corresponds to the motion of the contact ellipse across the tooth surface, (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: (1) kinematic errors induced by errors of manufacture may be minimized by applying special machine settings, the original error may be reduced by order of magnitude, the procedure is most effective for geometry 2 gears, (2) when trying to adjust the bearing contact pattern between the gear teeth for geometry 1 gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially; (3) the kinematic accuracy of spiral bevel drives are most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The precision of mounting accuracy and manufacture are most crucial for the gear, and less so for the pinion.

  20. 3D imaging: how to achieve highest accuracy

    NASA Astrophysics Data System (ADS)

    Luhmann, Thomas

    2011-07-01

    The generation of 3D information from images is a key technology in many different areas, e.g. in 3D modeling and representation of architectural or heritage objects, in human body motion tracking and scanning, in 3D scene analysis of traffic scenes, in industrial applications and many more. The basic concepts rely on mathematical representations of central perspective viewing as they are widely known from photogrammetry or computer vision approaches. The objectives of these methods differ, more or less, from high precision and well-structured measurements in (industrial) photogrammetry to fully-automated non-structured applications in computer vision. Accuracy and precision is a critical issue for the 3D measurement of industrial, engineering or medical objects. As state of the art, photogrammetric multi-view measurements achieve relative precisions in the order of 1:100000 to 1:200000, and relative accuracies with respect to retraceable lengths in the order of 1:50000 to 1:100000 of the largest object diameter. In order to obtain these figures a number of influencing parameters have to be optimized. These are, besides others: physical representation of object surface (targets, texture), illumination and light sources, imaging sensors, cameras and lenses, calibration strategies (camera model), orientation strategies (bundle adjustment), image processing of homologue features (target measurement, stereo and multi-image matching), representation of object or workpiece coordinate systems and object scale. The paper discusses the above mentioned parameters and offers strategies for obtaining highest accuracy in object space. Practical examples of high-quality stereo camera measurements and multi-image applications are used to prove the relevance of high accuracy in different applications, ranging from medical navigation to static and dynamic industrial measurements. In addition, standards for accuracy verifications are presented and demonstrated by practical examples

  1. Radiochromic film dosimetry: considerations on precision and accuracy for EBT2 and EBT3 type films.

    PubMed

    Dreindl, Ralf; Georg, Dietmar; Stock, Markus

    2014-05-01

    Gafchromic® EBT2 film is a widely used dosimetric tool for quality assurance in radiation therapy. In 2012 EBT3 was presented as a replacement for EBT2 films. The symmetric structure of EBT3 films to reduce face-up/down dependency as well as the inclusion of a matte film surface to frustrate Newton Ring artifacts present the most prominent improvements of EBT3 films. The aim of this study was to investigate the characteristics of EBT3 films, to benchmark the films against the known EBT2-features and to evaluate the dosimetric behavior over a time period greater than 6 months. All films were irradiated to clinical photon beams (6 MV, 10 MV and 18 MV) on an Elekta Synergy Linac equipped with a Beam Modulator MLC in solid water phantom slabs. Film digitalization was done with a flatbed transparency scanner (Type Epson Expression 1680 Pro). MATLAB® was used for further statistical calculations and image processing. The investigations on post-irradiation darkening, film orientation, film uniformity and energy dependency resulted in negligible differences between EBT2 and EBT3 film. A minimal improvement in face-up/down dependence was found for EBT3. The matte film surface of EBT3 films turned out to be a practical feature as Newton rings could be eliminated completely. Considering long-term behavior (> 6 months) a shift of the calibration curve for EBT2 and EBT3 films due to changes in the dynamic response of the active component was observed. In conclusion, the new EBT3 film yields comparable results to its predecessor EBT2. The general advantages of radiochromic film dosimeters are completed by high film homogeneity, low energy dependence for the observed energy range and a minimized face-up/down dependence. EBT2 dosimetry-protocols can also be used for EBT3 films, but the inclusion of periodical recalibration-interval (e.g. once a quarter) is recommended for protocols of both film generations.

  2. New procedure for improving precision and accuracy of instrumental color measurements of beef.

    PubMed

    Khatri, Mamata; Phung, Vinh T; Isaksson, Tomas; Sørheim, Oddvin; Slinde, Erik; Egelandsdal, Bjørg

    2012-07-01

    The surface layers of steaks from bovine M. semimembranosus were prepared to have deoxy- (DMb), oxy- (OMb) and metmyoglobin (MMb) states using either chemicals (CHEM) or oxygen partial pressure packaging (OPP). Ninety-six different meat surface areas were measured in reflectance mode (400-1100 nm) for each preparation method. Reflectance spectra were converted to absorbance (A) and then transformed by Kubelka-Munk transformation (K/S) and/or extended multiplicative scatter correction (EMSC). Transformed spectra of prepared pure states were used to make calibration models of MMb, DMb and OMb using either selected wavelengths (SW) or partial least square (PLS) regression. Finally, the predicted myoglobin states were normalized to ensure that no state was <0 or >1 and the sum of all states equal to 1. Multivariate calibrations (i.e. PLS) outperformed the univariate calibrations (i.e. SW). The OPP method of preparing pure states was clearly best for OMb while the CHEM method was best for preparing MMb on fresh meat surfaces. Both preparation methods needed improvement concerning DMb. The CHEM(K/S) SW and the OPP EMSC(A) PLS methods predicted MMb, DMb and OMb with root-mean-square errors of cross validation (RMSECV) equal to 0.08, 0.16 and 0.18 (range 0-1) and 0.04, 0.04 and 0.04 (range 0-1), respectively. This new reflectance protocol has potential for routine meat color measurements.

  3. Accuracy, Precision, Sensitivity, and Specificity of Noninvasive ICP Absolute Value Measurements.

    PubMed

    Krakauskaite, Solventa; Petkus, Vytautas; Bartusis, Laimonas; Zakelis, Rolandas; Chomskis, Romanas; Preiksaitis, Aidanas; Ragauskas, Arminas; Matijosaitis, Vaidas; Petrikonis, Kestutis; Rastenyte, Daiva

    2016-01-01

    An innovative absolute intracranial pressure (ICP) value measurement method has been validated by multicenter comparative clinical studies. The method is based on two-depth transcranial Doppler (TCD) technology and uses intracranial and extracranial segments of the ophthalmic artery as pressure sensors. The ophthalmic artery is used as a natural pair of "scales" that compares ICP with controlled pressure Pe, which is externally applied to the orbit. To balance the scales, ICP = Pe a special two-depth TCD device was used as a pressure balance indicator. The proposed method is the only noninvasive ICP measurement method that does not need patient-specific calibration.

  4. On the accuracy and precision of numerical waveforms: effect of waveform extraction methodology

    NASA Astrophysics Data System (ADS)

    Chu, Tony; Fong, Heather; Kumar, Prayush; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela

    2016-08-01

    We present a new set of 95 numerical relativity simulations of non-precessing binary black holes (BBHs). The simulations sample comprehensively both black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1-3. The simulations cover on average 24 inspiral orbits, plus merger and ringdown, with low initial orbital eccentricities e\\lt {10}-4. A subset of the simulations extends the coverage of non-spinning BBHs up to mass ratio q = 10. Gravitational waveforms at asymptotic infinity are computed with two independent techniques: extrapolation and Cauchy characteristic extraction. An error analysis based on noise-weighted inner products is performed. We find that numerical truncation error, error due to gravitational wave extraction, and errors due to the Fourier transformation of signals with finite length of the numerical waveforms are of similar magnitude, with gravitational wave extraction errors dominating at noise-weighted mismatches of ˜ 3× {10}-4. This set of waveforms will serve to validate and improve aligned-spin waveform models for gravitational wave science.

  5. Incorporating precision, accuracy and alternative sampling designs into a continental monitoring program for colonial waterbirds

    USGS Publications Warehouse

    Steinkamp, Melanie J.; Peterjohn, B.G.; Keisman, J.L.

    2003-01-01

    A comprehensive monitoring program for colonial waterbirds in North America has never existed. At smaller geographic scales, many states and provinces conduct surveys of colonial waterbird populations. Periodic regional surveys are conducted at varying times during the breeding season using a variety of survey methods, which complicates attempts to estimate population trends for most species. The US Geological Survey Patuxent Wildlife Research Center has recently started to coordinate colonial waterbird monitoring efforts throughout North America. A centralized database has been developed with an Internet-based data entry and retrieval page. The extent of existing colonial waterbird surveys has been defined, allowing gaps in coverage to be identified and basic inventories completed where desirable. To enable analyses of comparable data at regional or larger geographic scales, sampling populations through statistically sound sampling designs should supersede obtaining counts at every colony. Standardized breeding season survey techniques have been agreed upon and documented in a monitoring manual. Each survey in the manual has associated with it recommendations for bias estimation, and includes specific instructions on measuring detectability. The methods proposed in the manual are for developing reliable, comparable indices of population size to establish trend information at multiple spatial and temporal scales, but they will not result in robust estimates of total population numbers.

  6. Army Direct Fire Accuracy: Precision and Its Effects on the Battlefield

    DTIC Science & Technology

    2007-11-02

    away ( Loeb 2003). This capability, which provides the tanker a fifty power zoom to see this extended range, is 42 critical to today’s complex...battlefield mixed with enemy and civilian vehicles ( Loeb 2003). Tanks commanders have the option of destroying the target itself, at a new effective range... Loeb 2003). This combination of units supports the military’s desire to enforce more combined arms and joint participation in order to maximize

  7. Phylogenomic datasets provide both precision and accuracy in estimating the timescale of placental mammal phylogeny.

    PubMed

    dos Reis, Mario; Inoue, Jun; Hasegawa, Masami; Asher, Robert J; Donoghue, Philip C J; Yang, Ziheng

    2012-09-07

    The fossil record suggests a rapid radiation of placental mammals following the Cretaceous-Paleogene (K-Pg) mass extinction 65 million years ago (Ma); nevertheless, molecular time estimates, while highly variable, are generally much older. Early molecular studies suffer from inadequate dating methods, reliance on the molecular clock, and simplistic and over-confident interpretations of the fossil record. More recent studies have used Bayesian dating methods that circumvent those issues, but the use of limited data has led to large estimation uncertainties, precluding a decisive conclusion on the timing of mammalian diversifications. Here we use a powerful Bayesian method to analyse 36 nuclear genomes and 274 mitochondrial genomes (20.6 million base pairs), combined with robust but flexible fossil calibrations. Our posterior time estimates suggest that marsupials diverged from eutherians 168-178 Ma, and crown Marsupialia diverged 64-84 Ma. Placentalia diverged 88-90 Ma, and present-day placental orders (except Primates and Xenarthra) originated in a ∼20 Myr window (45-65 Ma) after the K-Pg extinction. Therefore we reject a pre K-Pg model of placental ordinal diversification. We suggest other infamous instances of mismatch between molecular and palaeontological divergence time estimates will be resolved with this same approach.

  8. Accuracy and Precision Analysis of Chamber-Based Nitrous Oxide Gas Flux Estimates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chamber-based estimates of soil-to-atmosphere nitrous oxide (N2O) gas flux tend to underestimate actual emission rates due to inherently non-linear time series data. In theory, this limitation can be minimized by adjusting measurement conditions to reduce non-linearity and/or by using flux-calculati...

  9. Enhancing the precision and accuracy within and among AmeriFlux site measurements

    SciTech Connect

    Law, Bev

    2013-11-25

    This is the final report for AmeriFlux QA/QC at Oregon State University. The major objective of this project is to contribute to the AmeriFlux network by continuing to build consistency in AmeriFlux measurements by addressing objectives stated in the AmeriFlux strategic plan and self evaluation, the North American Carbon Program, and the US Carbon Cycle Science Program. The project directly contributes to NACP and CCSP goals to establish an integrated, near-real time network of observations to inform climate change science.

  10. Measurement Accuracy and Precision Assessment of an Image-Based Clothing and Equipment Sizing System

    DTIC Science & Technology

    1999-07-01

    circumference, chest circumference, waist circumference , hip circumference, and sleeve length (spine-wrist). The test sample consisted of a subset of...compare the means of all dimensions. Waist circumference was excluded from this comparison due to the difference in measurement definition between the two...neck circumference, chest circumference, waist circumference , hip circumference, and sleeve length (spine-wrist). A detailed analysis of 0 the

  11. High precision optical surface metrology using deflectometry

    NASA Astrophysics Data System (ADS)

    Huang, Run

    Software Configurable Optical Test System (SCOTS) developed at University of Arizona is a highly efficient optical metrology technique based on the principle of deflectometry, which can achieve comparable accuracy with interferometry but with low-cost hardware. In a SCOTS test, an LCD display is used to generate structured light pattern to illuminate the test optics and the reflected light is captured by a digital camera. The surface slope of test optics is determined by triangulation of the display pixels, test optics, and the camera. The surface shape is obtained by the integration of the slopes. Comparing to interferometry, which has long served as an accurate non-contact optical metrology technology, SCOTS overcomes the limitation of dynamic range and sensitivity to environment. It is able to achieve high dynamic range slope measurement without requiring null optics. In this dissertation, the sensitivity and performance of the test system have been analyzed comprehensively. Sophisticated calibrations of system components have been investigated and implemented in different metrology projects to push this technology to a higher accuracy including low-order terms. A compact on-axis SCOTS system lowered the testing geometry sensitivity in the metrology of 1-meter highly aspheric secondary mirror of Large Binocular Telescope. Sub-nm accuracy was achieved in testing a high precision elliptical X-ray mirror by using reference calibration. A well-calibrated SCOTS was successfully constructed and is, at the time of writing this dissertation, being used to provide surface metrology feedback for the fabrication of the primary mirror of Daniel K. Inouye Solar Telescope which is a 4-meter off-axis parabola with more than 8 mm aspherical departure.

  12. Alignment techniques required by precise measurement of effective focal length

    NASA Technical Reports Server (NTRS)

    Wise, T. D.

    1980-01-01

    The characteristics of false color imagery produced by instrumentation on earth resource mapping satellites are examined. The spatial fidelity of the imagery is dependent upon the geometric accuracy (GA) and the band-to-band registration (BBR) with which the telescope instrument is assembled. BBR and GA require knowledge of telescope effective focal length (EFL) to one part in 10,000 in order that the next generation of earth mappers be able to carry out their missions. The basis for this level of precision is briefly considered, and a description is given of the means by which such precise EFL measurements have been carried out. Attention is given to accuracy requirements, the technique used to measure effective focal length, possible sources of error in the EFL measurement, approaches for eliminating errors, and the results of the efforts to control measurement errors in EFL determinations.

  13. Ground control requirements for precision processing of ERTS images

    USGS Publications Warehouse

    Burger, Thomas C.

    1973-01-01

    With the successful flight of the ERTS-1 satellite, orbital height images are available for precision processing into products such as 1:1,000,000-scale photomaps and enlargements up to 1:250,000 scale. In order to maintain positional error below 100 meters, control points for the precision processing must be carefully selected, clearly definitive on photos in both X and Y. Coordinates of selected control points measured on existing ½ and 15-minute standard maps provide sufficient accuracy for any space imaging system thus far defined. This procedure references the points to accepted horizontal and vertical datums. Maps as small as 1:250,000 scale can be used as source material for coordinates, but to maintain the desired accuracy, maps of 1:100,000 and larger scale should be used when available.

  14. Universal recovery map for approximate Markov chains

    PubMed Central

    Sutter, David; Fawzi, Omar; Renner, Renato

    2016-01-01

    A central question in quantum information theory is to determine how well lost information can be reconstructed. Crucially, the corresponding recovery operation should perform well without knowing the information to be reconstructed. In this work, we show that the quantum conditional mutual information measures the performance of such recovery operations. More precisely, we prove that the conditional mutual information I(A:C|B) of a tripartite quantum state ρABC can be bounded from below by its distance to the closest recovered state RB→BC(ρAB), where the C-part is reconstructed from the B-part only and the recovery map RB→BC merely depends on ρBC. One particular application of this result implies the equivalence between two different approaches to define topological order in quantum systems. PMID:27118889

  15. Assessment of the Accuracy of Close Distance Photogrammetric JRC Data

    NASA Astrophysics Data System (ADS)

    Kim, Dong Hyun; Poropat, George; Gratchev, Ivan; Balasubramaniam, Arumugam

    2016-11-01

    By using close range photogrammetry, this article investigates the accuracy of the photogrammetric estimation of rock joint roughness coefficients (JRC), a measure of the degree of roughness of rock joint surfaces. This methodology has proven to be convenient both in laboratory and in site conditions. However, the accuracy and precision of roughness profiles obtained from photogrammetric 3D images have not been properly established due to the variances caused by factors such as measurement errors and systematic errors in photogrammetry. In this study, the influences of camera-to-object distance, focal length and profile orientation on the accuracy of JRC values are investigated using several photogrammetry field surveys. Directional photogrammetric JRC data are compared with data derived from the measured profiles, so as to determine their accuracy. The extent of the accuracy of JRC values was examined based on the error models which were previously developed from laboratory tests and revised for better estimation in this study. The results show that high-resolution 3D images (point interval ≤1 mm) can reduce the JRC errors obtained from field photogrammetric surveys. Using the high-resolution images, the photogrammetric JRC values in the range of high oblique camera angles are highly consistent with the revised error models. Therefore, the analysis indicates that the revised error models facilitate the verification of the accuracy of photogrammetric JRC values.

  16. The Influence of Motor Skills on Measurement Accuracy

    NASA Astrophysics Data System (ADS)

    Brychta, Petr; Sadílek, Marek; Brychta, Josef

    2016-10-01

    This innovative study trying to do interdisciplinary interface at first view different ways fields: kinantropology and mechanical engineering. A motor skill is described as an action which involves the movement of muscles in a body. Gross motor skills permit functions as a running, jumping, walking, punching, lifting and throwing a ball, maintaining a body balance, coordinating etc. Fine motor skills captures smaller neuromuscular actions, such as holding an object between the thumb and a finger. In mechanical inspection, the accuracy of measurement is most important aspect. The accuracy of measurement to some extent is also dependent upon the sense of sight or sense of touch associated with fine motor skills. It is therefore clear that the level of motor skills will affect the precision and accuracy of measurement in metrology. Aim of this study is literature review to find out fine motor skills level of individuals and determine the potential effect of different fine motor skill performance on precision and accuracy of mechanical engineering measuring.

  17. A review of precision oscillators. [for frequency standards

    NASA Technical Reports Server (NTRS)

    Hellwig, H.

    1974-01-01

    Precision oscillators used in PTTI applications include quartz crystal, rubidium gas cell, cesium beam, and hydrogen maser oscillators. A general characterization and comparison of these devices is given including accuracy, stability, environmental sensitivity, size, weight, power consumption, availability and cost. Areas of special concern in practical applications are identified and a projection of future performance specifications is given. An attempt is made to predict physical and performance characteristics of new designs potentially available in the near future.

  18. High Precision Digital Frequency Signal Source Based on FPGA

    NASA Astrophysics Data System (ADS)

    Yanbin, SHI; Jian, GUO; Ning, CUI

    The realization method of DDS technology is introduced, and its superior technical characteristics are analyzed in this paper. According to its characteristics, the high accuracy digital frequency signal source based on FPGA is designed. The simulation result indicated, compares with the traditional signal source, this type of signal source realized by the method of FPGA+DDS have many merits such as high precision and fast switch speed, which can satisfies the developing tendency of test facility.

  19. Three-D multilateration: A precision geodetic measurement system

    NASA Technical Reports Server (NTRS)

    Escobal, P. R.; Ong, K. M.; Vonroos, O. H.; Shumate, M. S.; Jaffe, R. M.; Fliegel, H. F.; Muller, P. M.

    1973-01-01

    A technique of satellite geodesy for determining the relative three dimensional coordinates of ground stations within one centimeter over baselines of 20 to 10,000 kilometers is discussed. The system is referred to as 3-D Multilateration and has applications in earthquake hazard assessment, precision surveying, plate tectonics, and orbital mechanics. The accuracy is obtained by using pulsed lasers to obtain simultaneous slant ranges between several ground stations and a moving retroreflector with known trajectory for aiming the lasers.

  20. High Accuracy Temperature Measurements Using RTDs with Current Loop Conditioning

    NASA Technical Reports Server (NTRS)

    Hill, Gerald M.

    1997-01-01

    To measure temperatures with a greater degree of accuracy than is possible with thermocouples, RTDs (Resistive Temperature Detectors) are typically used. Calibration standards use specialized high precision RTD probes with accuracies approaching 0.001 F. These are extremely delicate devices, and far too costly to be used in test facility instrumentation. Less costly sensors which are designed for aeronautical wind tunnel testing are available and can be readily adapted to probes, rakes, and test rigs. With proper signal conditioning of the sensor, temperature accuracies of 0.1 F is obtainable. For reasons that will be explored in this paper, the Anderson current loop is the preferred method used for signal conditioning. This scheme has been used in NASA Lewis Research Center's 9 x 15 Low Speed Wind Tunnel, and is detailed.

  1. Accuracy of genomic selection in European maize elite breeding populations.

    PubMed

    Zhao, Yusheng; Gowda, Manje; Liu, Wenxin; Würschum, Tobias; Maurer, Hans P; Longin, Friedrich H; Ranc, Nicolas; Reif, Jochen C

    2012-03-01

    Genomic selection is a promising breeding strategy for rapid improvement of complex traits. The objective of our study was to investigate the prediction accuracy of genomic breeding values through cross validation. The study was based on experimental data of six segregating populations from a half-diallel mating design with 788 testcross progenies from an elite maize breeding program. The plants were intensively phenotyped in multi-location field trials and fingerprinted with 960 SNP markers. We used random regression best linear unbiased prediction in combination with fivefold cross validation. The prediction accuracy across populations was higher for grain moisture (0.90) than for grain yield (0.58). The accuracy of genomic selection realized for grain yield corresponds to the precision of phenotyping at unreplicated field trials in 3-4 locations. As for maize up to three generations are feasible per year, selection gain per unit time is high and, consequently, genomic selection holds great promise for maize breeding programs.

  2. Transverse Mercator with an accuracy of a few nanometers

    NASA Astrophysics Data System (ADS)

    Karney, Charles F. F.

    2011-08-01

    Implementations of two algorithms for the transverse Mercator projection are described; these achieve accuracies close to machine precision. One is based on the exact equations of Thompson and Lee and the other uses an extension of Krüger's series for the mapping to higher order. The exact method provides an accuracy of 9 nm over the entire ellipsoid, while the errors in the series method are less than 5 nm within 3900 km of the central meridian. In each case, the meridian convergence and scale are also computed with similar accuracy. The speed of the series method is competitive with other less accurate algorithms and the exact method is about five times slower.

  3. Precision instrument placement using a 4-DOF robot with integrated fiducials for minimally invasive interventions

    NASA Astrophysics Data System (ADS)

    Stenzel, Roland; Lin, Ralph; Cheng, Peng; Kronreif, Gernot; Kornfeld, Martin; Lindisch, David; Wood, Bradford J.; Viswanathan, Anand; Cleary, Kevin

    2007-03-01

    Minimally invasive procedures are increasingly attractive to patients and medical personnel because they can reduce operative trauma, recovery times, and overall costs. However, during these procedures, the physician has a very limited view of the interventional field and the exact position of surgical instruments. We present an image-guided platform for precision placement of surgical instruments based upon a small four degree-of-freedom robot (B-RobII; ARC Seibersdorf Research GmbH, Vienna, Austria). This platform includes a custom instrument guide with an integrated spiral fiducial pattern as the robot's end-effector, and it uses intra-operative computed tomography (CT) to register the robot to the patient directly before the intervention. The physician can then use a graphical user interface (GUI) to select a path for percutaneous access, and the robot will automatically align the instrument guide along this path. Potential anatomical targets include the liver, kidney, prostate, and spine. This paper describes the robotic platform, workflow, software, and algorithms used by the system. To demonstrate the algorithmic accuracy and suitability of the custom instrument guide, we also present results from experiments as well as estimates of the maximum error between target and instrument tip.

  4. Recovery and Money Management

    PubMed Central

    Rowe, Michael; Serowik, Kristin L.; Ablondi, Karen; Wilbur, Charles; Rosen, Marc I.

    2014-01-01

    Objective Social recovery and external money management are important approaches in contemporary mental health care, but little research has been done on the relationship between the two or on application of recovery principles to money management for people at risk of being assigned a representative payee or conservator. Methods Twenty-five transcripts out of forty-nine total qualitative interviews with persons receiving SSI or SSDI who were at risk of being assigned a money manager were analyzed to assess the presence of recognized recovery themes. Results The recovery principles of self-direction and responsibility were strong themes in participant comments related to money management. Conclusions and Implications for Practice Money management interventions should incorporate peoples’ recovery-related motivations to acquire financial management skills as a means to direct and assume responsibility for one’s finances. Staff involved in money management should receive training to support client’s recovery-related goals. PMID:23750764

  5. Intermediate water recovery system

    NASA Technical Reports Server (NTRS)

    Deckman, G.; Anderson, A. R. (Editor)

    1973-01-01

    A water recovery system for collecting, storing, and processing urine, wash water, and humidity condensates from a crew of three aboard a spacecraft is described. The results of a 30-day test performed on a breadboard system are presented. The intermediate water recovery system produced clear, sterile, water with a 96.4 percent recovery rate from the processed urine. Recommendations for improving the system are included.

  6. Astronomic Position Accuracy Capability Study.

    DTIC Science & Technology

    1979-10-01

    portion of F. E. Warren AFB, Wyoming. The three points were called THEODORE ECC , TRACY, and JIM and consisted of metal tribrachs plastered to cinder...sets were computed as a deviation from the standard. Accuracy figures were determined from these residuals. Homo - geneity of variances was tested using

  7. The hidden KPI registration accuracy.

    PubMed

    Shorrosh, Paul

    2011-09-01

    Determining the registration accuracy rate is fundamental to improving revenue cycle key performance indicators. A registration quality assurance (QA) process allows errors to be corrected before bills are sent and helps registrars learn from their mistakes. Tools are available to help patient access staff who perform registration QA manually.

  8. Improving Speaking Accuracy through Awareness

    ERIC Educational Resources Information Center

    Dormer, Jan Edwards

    2013-01-01

    Increased English learner accuracy can be achieved by leading students through six stages of awareness. The first three awareness stages build up students' motivation to improve, and the second three provide learners with crucial input for change. The final result is "sustained language awareness," resulting in ongoing…

  9. Inventory accuracy in 60 days!

    PubMed

    Miller, G J

    1997-08-01

    Despite great advances in manufacturing technology and management science, thousands of organizations still don't have a handle on basic inventory accuracy. Many companies don't even measure it properly, or at all, and lack corrective action programs to improve it. This article offers an approach that has proven successful a number of times, when companies were quite serious about making improvements. Not only can it be implemented, but also it can likely be implemented within 60 days per area, if properly managed. The hardest part is selling people on the need to improve and then keeping them motivated. The net cost of such a program? Probably less than nothing, since the benefits gained usually far exceed the costs. Improved inventory accuracy can aid in enhancing customer service, determining purchasing and manufacturing priorities, reducing operating costs, and increasing the accuracy of financial records. This article also addresses the gap in contemporary literature regarding accuracy program features for repetitive, JIT, cellular, and process- and project-oriented environments.

  10. Overestimation of required recovery time during repeated sprint exercise with self-regulated recovery.

    PubMed

    Phillips, Shaun M; Thompson, Richard; Oliver, Jon L

    2014-12-01

    This study investigated the reliability and accuracy of self-regulated recovery time and performance during repeated sprinting. On 4 occasions, 14 men (24.5 ± 5.0 years) completed 10 × 6 seconds cycle sprints against 7.5% body mass, self-regulating (SR) recovery time to maintain performance. Subjects then repeated the test, but with a reduced recovery (RR) of 10% less recovery time. Across the first 4 trials, there were no between-trial differences in peak power output (PPO) or mean power output (MPO), recovery time, or fatigue index (p > 0.05). Random variation in recovery time was reduced across trials 3-4 (coefficient of variation [CV] = 7.5%, 95% confidence limits [CL] = 5.4-12.4%) compared with trials 1-2 (CV = 16.0, 95% CL = 11.4-27.0%) and 2-3 (CV = 10.1%, 95% CL = 7.2-16.7%) but was consistent across trials for PPO and MPO (between-trials CV, ≤3.3%). There were no trial effects for any performance, physiological, or perceptual measures when comparing SR with RR (p > 0.05), although heart rate and perceptual measures increased with subsequent sprint efforts (p ≤ 0.05). After 2 familiarization trials, subjects can reliably self-regulate recovery time to maintain performance during repeated sprints. However, subjects overestimate the amount of recovery time required, as reducing this time by 10% had no effect on performance, perceptual, or physiological parameters. Self-regulated sprinting is potentially a reliable training tool, particularly for sprint training where maintenance of work is desired. However, overestimation of required recovery time means that performance improvements may not be achieved if the goal of training is improvement of repeated sprint performance with incomplete recovery.

  11. Image recovery from edge primitives

    NASA Technical Reports Server (NTRS)

    Alter-Gartenberg, Rachel; Huck, Friedrich O.; Narayanswamy, Ramkumar

    1990-01-01

    A method for extracting edge primitives from Mach-band patterns is presented together with a method for recovering image representations of features outlined by the edge boundaries. The accuracy, stability, and resolution of these representations are assessed. Since these representations are most commonly used in characterizing targets, this method of low-level processing offers new opportunities for computer vision and high data-compressing coding. Two bandpass filters are considered, the spatially invariant Laplacian of Gaussian filter and spatially variant intensity-dependent spatial (IDS) summation. It is shown that the recovery from the IDS bandpass data is particularly advantageous in applications for which robustness to local and temporal variations in illumination is important. It is concluded that the edge primitives extracted from bandpassed images can be an efficient way to store, transmit, and represent images.

  12. Mixed-precision evaluation of two-electron integrals by Rys quadrature

    NASA Astrophysics Data System (ADS)

    Asadchev, Andrey; Gordon, Mark S.

    2012-08-01

    A mixed precision implementation of two-electron integrals is demonstrated to have two benefits: (a) computations can be performed reliably in 32-bit precision on architectures for which 32-bit precision is significantly faster than 64-bit precision (e.g. graphical processing units), and (b) numerical results that match those using higher than 64-bit precision can be recovered without a significant penalty associated with performing the entire computation in higher precision. A justification is presented for using mixed precision in the Rys two-electron integral quadrature algorithm, together with timings and numerical results using a variety of floating-point types. The code discussed here presents a systematic way to control the accuracy of the Rys algorithm, regardless of the types and numbers of integrals.

  13. SPFP: Speed without compromise—A mixed precision model for GPU accelerated molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Le Grand, Scott; Götz, Andreas W.; Walker, Ross C.

    2013-02-01

    A new precision model is proposed for the acceleration of all-atom classical molecular dynamics (MD) simulations on graphics processing units (GPUs). This precision model replaces double precision arithmetic with fixed point integer arithmetic for the accumulation of force components as compared to a previously introduced model that uses mixed single/double precision arithmetic. This significantly boosts performance on modern GPU hardware without sacrificing numerical accuracy. We present an implementation for NVIDIA GPUs of both generalized Born implicit solvent simulations as well as explicit solvent simulations using the particle mesh Ewald (PME) algorithm for long-range electrostatics using this precision model. Tests demonstrate both the performance of this implementation as well as its numerical stability for constant energy and constant temperature biomolecular MD as compared to a double precision CPU implementation and double and mixed single/double precision GPU implementations.

  14. Precision of a splitting device for water samples

    USGS Publications Warehouse

    Capel, Paul D.; Nacionales, Fernando C.; Larson, Steven J.

    1995-01-01

    Two identical cone splitters, devices designed to split water and its suspended solids into equal aliquots for semi-volatile organic chemical and trace element analyses, were evaluated for their precision. The water-splitting evaluations consisted of experiments to test the effect of water volume, the effect of combining outlet ports, and the effect of different techniques of water introduction. The solids-splitting evaluations consisted of experi- ments to test the effect of particle size (nine different particle diameters ranging from very coarse sand to clay) and suspended-solids concentration. In general, water was equally split with a precision of less than 5 percent relative standard deviation. The accuracy of splitting the solids was a function of particle size. Clay, silt, and fine and medium sand were split with a precision relative standard deviation of less than 7 percent, and coarse sand was split with a relative standard deviation between 12 and 45 percent.

  15. Hospital service recovery.

    PubMed

    Gutbezahl, Cary; Haan, Perry

    2006-01-01

    An organization's ability to correct service errors is an important factor in achieving success in today's service economy. This paper examines service recovery in hospitals in the U.S. First is a general review of service recovery theories. Next is a discussion of specific service issues related to the hospital environment. The literature on service recovery is used to make specific recommendations to hospitals for ways to improve their ability to remedy service errors when they occur. Suggestions for future research in the field of service recovery are also made.

  16. Apollo Recovery Operations

    NASA Technical Reports Server (NTRS)

    Interbartolo, Michael

    2009-01-01

    Objectives include: a) Describe the organization of recovery force command and control and landing areas; b) Describe the function and timeline use of the Earth Landing System (ELS); c) Describe Stable 1 vs Stable 2 landing configurations and the function of the Command Module Uprighting System; d) Explain the activities of the helicopter and swimmer teams in egress and recovery of the crew; e)Explain the activities of the swimmer teams and primary recovery ship in recovery of the Command Module; and f) Describe several landing incidents that occurred during Apollo.

  17. Resource Recovery Guide

    SciTech Connect

    Abert, J.G.

    1983-01-01

    Resource Recovery Guides is a collection of articles orignally published between 1975 and 1981. Many of these articles were not easily available to interested readers. Subjects discussed include newspaper recycling, aluminum recovery, codisposal of solid waste and dry sewage sludge, and the recovery of glass from urban refuse. Includes a combined author and subject index. Contents: National concerns for recycling and resource recovery of municipal waste: policy perspectives. Planning, procurement, marketing, economics, and finance. Waste as a source of raw materials. Waste as an energy source.

  18. Electric Quadrupole Transition Measurements of Hydrogen Molecule with High Precision

    NASA Astrophysics Data System (ADS)

    Cheng, Cun-Feng; Wang, Jin; Tan, Yan; Liu, An-Wen; Hu, Shui-Ming

    2013-06-01

    Molecular hydrogen is the most fundamental, and the only neutral molecule expected to be both calculated and measured with extremely high accuracy. High-precision measurements of its spectroscopy, especially the levels at the electric ground state, play an important role in the examination of precise quantum chemistry calculations and some fundamental physical constants. In the infrared region, H_2, being a homonuclear diatomic molecule, only has very weak electric quadrupole transitions. We established a new spectroscopy approach with ultra-high precision and sensitivity as well, based on a laser-locked cavity ring-down spectrometer. An equivalent absorption path-length of thousands of kilometers and a frequency precision of 10^{-5} cm^{-1} have been achieved. Ro-vibrational spectra of the second overtone of H_2 have been recorded. The obtained results will provide a direct examination of the high-accuracy quantum theory. It also shades light on the determination of fundamental physical constants such as the electron/proton mass ratio in a molecular system.

  19. Precision cleaning apparatus and method

    DOEpatents

    Schneider, T.W.; Frye, G.C.; Martin, S.J.

    1998-01-13

    A precision cleaning apparatus and method are disclosed. The precision cleaning apparatus includes a cleaning monitor further comprising an acoustic wave cleaning sensor such as a quartz crystal microbalance (QCM), a flexural plate wave (FPW) sensor, a shear horizontal acoustic plate mode (SH--APM) sensor, or a shear horizontal surface acoustic wave (SH--SAW) sensor; and measurement means connectable to the sensor for measuring in-situ one or more electrical response characteristics that vary in response to removal of one or more contaminants from the sensor and a workpiece located adjacent to the sensor during cleaning. Methods are disclosed for precision cleaning of one or more contaminants from a surface of the workpiece by means of the cleaning monitor that determines a state of cleanliness and any residual contamination that may be present after cleaning; and also for determining an effectiveness of a cleaning medium for removing one or more contaminants from a workpiece. 11 figs.

  20. Precision cleaning apparatus and method

    DOEpatents

    Schneider, Thomas W.; Frye, Gregory C.; Martin, Stephen J.

    1998-01-01

    A precision cleaning apparatus and method. The precision cleaning apparatus includes a cleaning monitor further comprising an acoustic wave cleaning sensor such as a quartz crystal microbalance (QCM), a flexural plate wave (FPW) sensor, a shear horizontal acoustic plate mode (SH--APM) sensor, or a shear horizontal surface acoustic wave (SH--SAW) sensor; and measurement means connectable to the sensor for measuring in-situ one or more electrical response characteristics that vary in response to removal of one or more contaminants from the sensor and a workpiece located adjacent to the sensor during cleaning. Methods are disclosed for precision cleaning of one or more contaminants from a surface of the workpiece by means of the cleaning monitor that determines a state of cleanliness and any residual contamination that may be present after cleaning; and also for determining an effectiveness of a cleaning medium for removing one or more contaminants from a workpiece.

  1. A precision mechanical nerve stimulator

    NASA Technical Reports Server (NTRS)

    Tcheng, Ping; Supplee, Frank H., Jr.; Prass, Richard L.

    1988-01-01

    An electromechanical device, used to apply and monitor stimulating pulses to a mammalian motor nerve, has been successfully developed at NASA Langley Research Center. Two existing force transducers, a flight skin friction balance and a miniature skin friction balance which were designed for making aerodynamic drag measurements, were modified and incorporated to form this precision instrument. The nerve stimulator is a type one servomechanism capable of applying and monitoring stimulating pulses of 0 to 10 grams with a precision of better than +/- 0.05 grams. Additionally, the device can be independently used to apply stimulating pulses by displacing the nerve from 0 to 0.25 mm with a precision of better than +/- 0.001 mm while measuring the level of the load applied.

  2. Precision-guaranteed quantum metrology

    NASA Astrophysics Data System (ADS)

    Sugiyama, Takanori

    2015-04-01

    Quantum metrology is a general term for methods to precisely estimate the value of an unknown parameter by actively using quantum resources. In particular, some classes of entangled states can be used to significantly suppress the estimation error. Here we derive a formula for rigorously evaluating an upper bound for the estimation error in a general setting of quantum metrology with arbitrary finite data sets. Unlike in the standard approach, where lower bounds for the error are evaluated in an ideal setting with almost infinite data, our method rigorously guarantees the estimation precision in realistic settings with finite data. We also prove that our upper bound shows the Heisenberg limit scaling whenever the linearized uncertainty, which is a popular benchmark in the standard approach, shows it. As an example, we apply our result to a Ramsey interferometer, and numerically show that the upper bound can exhibit the quantum enhancement of precision for finite data.

  3. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1982-01-01

    Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory.

  4. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1983-01-01

    Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory. Previously announced in STAR as N82-32733

  5. Improved accuracies for satellite tracking

    NASA Technical Reports Server (NTRS)

    Kammeyer, P. C.; Fiala, A. D.; Seidelmann, P. K.

    1991-01-01

    A charge coupled device (CCD) camera on an optical telescope which follows the stars can be used to provide high accuracy comparisons between the line of sight to a satellite, over a large range of satellite altitudes, and lines of sight to nearby stars. The CCD camera can be rotated so the motion of the satellite is down columns of the CCD chip, and charge can be moved from row to row of the chip at a rate which matches the motion of the optical image of the satellite across the chip. Measurement of satellite and star images, together with accurate timing of charge motion, provides accurate comparisons of lines of sight. Given lines of sight to stars near the satellite, the satellite line of sight may be determined. Initial experiments with this technique, using an 18 cm telescope, have produced TDRS-4 observations which have an rms error of 0.5 arc second, 100 m at synchronous altitude. Use of a mosaic of CCD chips, each having its own rate of charge motion, in the focal place of a telescope would allow point images of a geosynchronous satellite and of stars to be formed simultaneously in the same telescope. The line of sight of such a satellite could be measured relative to nearby star lines of sight with an accuracy of approximately 0.03 arc second. Development of a star catalog with 0.04 arc second rms accuracy and perhaps ten stars per square degree would allow determination of satellite lines of sight with 0.05 arc second rms absolute accuracy, corresponding to 10 m at synchronous altitude. Multiple station time transfers through a communications satellite can provide accurate distances from the satellite to the ground stations. Such observations can, if calibrated for delays, determine satellite orbits to an accuracy approaching 10 m rms.

  6. MAPPING SPATIAL THEMATIC ACCURACY WITH FUZZY SETS

    EPA Science Inventory

    Thematic map accuracy is not spatially homogenous but variable across a landscape. Properly analyzing and representing spatial pattern and degree of thematic map accuracy would provide valuable information for using thematic maps. However, current thematic map accuracy measures (...

  7. Precision glass molding: an integrative approach for the production of high precision micro-optics

    NASA Astrophysics Data System (ADS)

    Hünten, Martin; Klocke, Fritz; Dambon, Olaf

    2010-02-01

    Miniaturization and integration are the dominating factors for the success of numerous optical devices. Conventional manufacturing processes for the fabrication of precise glass optics by means of grinding and polishing cannot cope the increasing demands in terms of precision, volume and costs. Here, precision glass molding is the enabling technology to meet these demands of the future optical products and applications. Since the market requests further miniaturization and integration of the micro optical components the possession of the entire sequence of processes is absolutely essential. With the accomplished and ongoing developments at the Fraunhofer IPT, the replication of double-sided (a)spherical and (a)cylindrical glass lenses with form accuracies of < 150 nm as well as lens arrays and even freeform optics could be realized. Therefore, a sequence of processes needs to be passed. The FEM-simulation of the molding process which was driven to a point capable to simulate even the molding of freeform optics is the first process step. Further on, new mold design concepts were generated to enable the replication of free formed optics. The research works focusing on the mold manufacturing led to sophisticated grinding process strategies able to realized complex mold geometries such as lens arrays. With regard to the coating of the molds, proceedings were developed assuring a defect free and uniform coating which enables the longevity of the molds and therewith helps reducing the final costs per lens. Thus, the precision glass molding becomes more and more interesting even for highly complex mid volume lots, characteristic for European or US optics manufacturer.

  8. Precision protection through indirect correlations

    SciTech Connect

    Jin, Yao

    2016-04-15

    The dynamics of the quantum Fisher information of the parameters of the initial atomic state is studied, in the framework of open quantum systems, for a pair of static two-level atoms coupled to a bath of fluctuating vacuum scalar fields. Our results show that the correlations between the two atoms as well as the precision limit in quantum metrology are determined by the separation between the two atoms. Remarkably, when the separation between the two atoms approaches zero, the quantum Fisher information, thus the precision limit of the estimation of the parameters of the initial atomic state will be survived from the vacuum fluctuations after long time evolution.

  9. Precision Manipulation with Cooperative Robots

    NASA Technical Reports Server (NTRS)

    Stroupe, Ashley; Huntsberger, Terry; Okon, Avi; Aghzarian, Hrand

    2005-01-01

    This work addresses several challenges of cooperative transportThis work addresses several challenges of cooperative transport and precision manipulation. Precision manipulation requires a rigid grasp, which places a hard constraint on the relative rover formation that must be accommodated, even though the rovers cannot directly observe their relative poses. Additionally, rovers must jointly select appropriate actions based on all available sensor information. Lastly, rovers cannot act on independent sensor information, but must fuse information to move jointly; the methods for fusing information must be determined.

  10. Microbiopsy/precision cutting devices

    DOEpatents

    Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

    1999-01-01

    Devices for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways 1) intravascularly, 2) extravascularly, 3) by vessel puncture, and 4) externally. Additionally, the devices may be used in precision surgical cutting.

  11. Microbiopsy/precision cutting devices

    DOEpatents

    Krulevitch, P.A.; Lee, A.P.; Northrup, M.A.; Benett, W.J.

    1999-07-27

    Devices are disclosed for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways (1) intravascularly, (2) extravascularly, (3) by vessel puncture, and (4) externally. Additionally, the devices may be used in precision surgical cutting. 6 figs.

  12. PRECISION RADIAL VELOCITIES WITH CSHELL

    SciTech Connect

    Crockett, Christopher J.; Prato, L.; Mahmud, Naved I.; Johns-Krull, Christopher M.; Jaffe, Daniel T.; Beichman, Charles A. E-mail: lprato@lowell.edu E-mail: cmj@rice.edu

    2011-07-10

    Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s{sup -1} precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M{sub JUP} exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.

  13. Precision agriculture and food security.

    PubMed

    Gebbers, Robin; Adamchuk, Viacheslav I

    2010-02-12

    Precision agriculture comprises a set of technologies that combines sensors, information systems, enhanced machinery, and informed management to optimize production by accounting for variability and uncertainties within agricultural systems. Adapting production inputs site-specifically within a field and individually for each animal allows better use of resources to maintain the quality of the environment while improving the sustainability of the food supply. Precision agriculture provides a means to monitor the food production chain and manage both the quantity and quality of agricultural produce.

  14. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    PubMed

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a

  15. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    PubMed Central

    Larsen, K.K.; Wielandt, D.; Schiller, M.; Bizzarro, M.

    2016-01-01

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr3+, CrCl2+ and CrCl2+) with equilibrium mass-dependent isotope fractionation spanning a range of ~1‰/amu and consistent with theory. The heaviest isotopes partition into Cr3+, intermediates in CrCl2+ and the lightest in CrCl2+/CrCl3°. Thus, for a typical reported loss of ~25% Cr (in the form of Cr3+) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected 53Cr/52Cr (μ53 Cr* of 5.2 ppm) and 54Cr/52Cr (μ54Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr3+ by >5 days exposure to HNO3 —H2O2 solutions at room temperature, resulting in >~98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that

  16. Acceleration Disturbances onboard of Geodetic Precision Space Laboratories

    NASA Astrophysics Data System (ADS)

    Peterseim, Nadja; Jakob, Flury; Schlicht, Anja

    Bartlomiej Oszczak, b@dgps.pl University of Warmia and Mazury in Olsztyn, Poland, Olsztyn, Poland Olga Maciejczyk, omaciejczyk@gmail.com Poland In this paper there is presented the study on the parameters of the ASG-EUPOS real-time RTK service NAWGEO such as: accuracy, availability, integrity and continuity. Author's model is used for tests. These parameters enable determination of the quality of received information and practical applications of the service. Paper includes also the subject related to the NAWGEO service and algorithms used in determination of mentioned parameters. The results of accuracy and precision analyses and study on availability demonstrated that NAWGEO service enables a user a position determination with a few centimeters accuracy with high probability in any moment of time.

  17. Precise GPS ephemerides from DMA and NGS tested by time transfer

    NASA Technical Reports Server (NTRS)

    Lewandowski, Wlodzimierz W.; Petit, Gerard; Thomas, Claudine

    1992-01-01

    It was shown that the use of the Defense Mapping Agency's (DMA) precise ephemerides brings a significant improvement to the accuracy of GPS time transfer. At present a new set of precise ephemerides produced by the National Geodetic Survey (NGS) has been made available to the timing community. This study demonstrates that both types of precise ephemerides improve long-distance GPS time transfer and remove the effects of Selective Availability (SA) degradation of broadcast ephemerides. The issue of overcoming SA is also discussed in terms of the routine availability of precise ephemerides.

  18. Sensor fusion for precision agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Information-based management of crop production systems known as precision agriculture relies on different sensor technologies aimed at characterization of spatial heterogeneity of a cropping environment. Remote and proximal sensing systems have been deployed to obtain high-resolution data pertainin...

  19. Drilling Precise Orifices and Slots

    NASA Technical Reports Server (NTRS)

    Richards, C. W.; Seidler, J. E.

    1983-01-01

    Reaction control thrustor injector requires precisely machined orifices and slots. Tooling setup consists of rotary table, numerical control system and torque sensitive drill press. Components used to drill oxidizer orifices. Electric discharge machine drills fuel-feed orifices. Device automates production of identical parts so several are completed in less time than previously.

  20. Precision Teaching ... and All That!

    ERIC Educational Resources Information Center

    Raybould, E. C.; Solity, J. E.

    1988-01-01

    Two proponents of the precision teaching approach to teaching the handicapped discuss such principles as: the problem of partial application of the method; relationship to behaviorism; relationship to experiential learning; and the importance of fluency in task performance, mastery learning, and recordkeeping. (DB)

  1. Precision Machining Technology. Curriculum Guide.

    ERIC Educational Resources Information Center

    Idaho State Dept. of Education, Boise. Div. of Vocational Education.

    This curriculum guide was developed from a Technical Committee Report prepared with the assistance of industry personnel and containing a Task List which is the basis of the guide. It presents competency-based program standards for courses in precision machining technology and is part of the Idaho Vocational Curriculum Guide Project, a cooperative…

  2. Cushing's disease: towards precision medicine.

    PubMed

    Kaiser, Ursula B

    2015-06-01

    The pathogenesis of Cushing's disease is poorly understood; two recent reports identifying somatic mutations in USP8 in pituitary corticotroph tumors provide exciting advances in this field. These mutations alter EGFR trafficking and signaling, raising the prospect that EGFR inhibitors may move the treatment of this disease into the era of precision medicine.

  3. Precision Efficacy Analysis for Regression.

    ERIC Educational Resources Information Center

    Brooks, Gordon P.

    When multiple linear regression is used to develop a prediction model, sample size must be large enough to ensure stable coefficients. If the derivation sample size is inadequate, the model may not predict well for future subjects. The precision efficacy analysis for regression (PEAR) method uses a cross- validity approach to select sample sizes…

  4. Precision Cleaning - Path to Premier

    NASA Technical Reports Server (NTRS)

    Mackler, Scott E.

    2008-01-01

    ITT Space Systems Division s new Precision Cleaning facility provides critical cleaning and packaging of aerospace flight hardware and optical payloads to meet customer performance requirements. The Precision Cleaning Path to Premier Project was a 2007 capital project and is a key element in the approved Premier Resource Management - Integrated Supply Chain Footprint Optimization Project. Formerly precision cleaning was located offsite in a leased building. A new facility equipped with modern precision cleaning equipment including advanced process analytical technology and improved capabilities was designed and built after outsourcing solutions were investigated and found lacking in ability to meet quality specifications and schedule needs. SSD cleans parts that can range in size from a single threaded fastener all the way up to large composite structures. Materials that can be processed include optics, composites, metals and various high performance coatings. We are required to provide verification to our customers that we have met their particulate and molecular cleanliness requirements and we have that analytical capability in this new facility. The new facility footprint is approximately half the size of the former leased operation and provides double the amount of throughput. Process improvements and new cleaning equipment are projected to increase 1st pass yield from 78% to 98% avoiding $300K+/yr in rework costs. Cost avoidance of $350K/yr will result from elimination of rent, IT services, transportation, and decreased utility costs. Savings due to reduced staff expected to net $4-500K/yr.

  5. "Sizing Up" Codependency Recovery.

    ERIC Educational Resources Information Center

    Messner, Beth A.

    1996-01-01

    Analyzes codependency related, self-help literature with a dramatistic lens to explore M. Beattie's bibliotherapeutic portrayal of codependency and codependency recovery. Depicts Beattie's "stylistic medicine" for codependency recovery as a three-step, rebirth experience: (1) recognize the codependent pollution within; (2) engage in…

  6. Accuracy of implant impression techniques.

    PubMed

    Assif, D; Marshak, B; Schmidt, A

    1996-01-01

    Three impression techniques were assessed for accuracy in a laboratory cast that simulated clinical practice. The first technique used autopolymerizing acrylic resin to splint the transfer copings. The second involved splinting of the transfer copings directly to an acrylic resin custom tray. In the third, only impression material was used to orient the transfer copings. The accuracy of stone casts with implant analogs was measured against a master framework. The fit of the framework on the casts was tested using strain gauges. The technique using acrylic resin to splint transfer copings in the impression material was significantly more accurate than the two other techniques. Stresses observed in the framework are described and discussed with suggestions to improve clinical and laboratory techniques.

  7. A high accuracy sun sensor

    NASA Astrophysics Data System (ADS)

    Bokhove, H.

    The High Accuracy Sun Sensor (HASS) is described, concentrating on measurement principle, the CCD detector used, the construction of the sensorhead and the operation of the sensor electronics. Tests on a development model show that the main aim of a 0.01-arcsec rms stability over a 10-minute period is closely approached. Remaining problem areas are associated with the sensor sensitivity to illumination level variations, the shielding of the detector, and the test and calibration equipment.

  8. Enhancing and evaluating diagnostic accuracy.

    PubMed

    Swets, J A; Getty, D J; Pickett, R M; D'Orsi, C J; Seltzer, S E; McNeil, B J

    1991-01-01

    Techniques that may enhance diagnostic accuracy in clinical settings were tested in the context of mammography. Statistical information about the relevant features among those visible in a mammogram and about their relative importances in the diagnosis of breast cancer was the basis of two decision aids for radiologists: a checklist that guides the radiologist in assigning a scale value to each significant feature of the images of a particular case, and a computer program that merges those scale values optimally to estimate a probability of malignancy. A test set of approximately 150 proven cases (including normals and benign and malignant lesions) was interpreted by six radiologists, first in their usual manner and later with the decision aids. The enhancing effect of these feature-analytic techniques was analyzed across subsets of cases that were restricted progressively to more and more difficult cases, where difficulty was defined in terms of the radiologists' judgements in the standard reading condition. Accuracy in both standard and enhanced conditions decreased regularly and substantially as case difficulty increased, but differentially, such that the enhancement effect grew regularly and substantially. For the most difficult case sets, the observed increases in accuracy translated into an increase of about 0.15 in sensitivity (true-positive proportion) for a selected specificity (true-negative proportion) of 0.85 or a similar increase in specificity for a selected sensitivity of 0.85. That measured accuracy can depend on case-set difficulty to different degrees for two diagnostic approaches has general implications for evaluation in clinical medicine. Comparative, as well as absolute, assessments of diagnostic performances--for example, of alternative imaging techniques--may be distorted by inadequate treatments of this experimental variable. Subset analysis, as defined and illustrated here, can be useful in alleviating the problem.

  9. Investigation of the Accuracy of Google Earth Elevation Data

    NASA Astrophysics Data System (ADS)

    El-Ashmawy, Khalid L. A.

    2016-09-01

    Digital Elevation Models (DEMs) comprise valuable source of elevation data required for many engineering applications. Contour lines, slope - aspect maps are part of their many uses. Moreover, DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally-produced relief maps. This paper proposes a method of generating DEM by using Google Earth elevation data which is easier and free. The case study consisted of three different small regions in the northern beach in Egypt. The accuracy of the Google earth derived elevation data are reported using root mean square error (RMSE), mean error (ME) and maximum absolute error (MAE). All these accuracy statistics were computed using the ground coordinates of 200 reference points for each region of the case study. The reference data was collected with total station survey. The results showed that the accuracies for the prepared DEMs are suitable for some certain engineering applications but inadequate to meet the standard required for fine/small scale DEM for very precise engineering study. The obtained accuracies for terrain with small height difference can be used for preparing large area cadastral, city planning, or land classification maps. In general, Google Earth elevation data can be used only for investigation and preliminary studies with low cost. It is strongly concluded that the users of Google Earth have to test the accuracy of elevation data by comparing with reference data before using it.

  10. Municipal water consumption forecast accuracy

    NASA Astrophysics Data System (ADS)

    Fullerton, Thomas M.; Molina, Angel L.

    2010-06-01

    Municipal water consumption planning is an active area of research because of infrastructure construction and maintenance costs, supply constraints, and water quality assurance. In spite of that, relatively few water forecast accuracy assessments have been completed to date, although some internal documentation may exist as part of the proprietary "grey literature." This study utilizes a data set of previously published municipal consumption forecasts to partially fill that gap in the empirical water economics literature. Previously published municipal water econometric forecasts for three public utilities are examined for predictive accuracy against two random walk benchmarks commonly used in regional analyses. Descriptive metrics used to quantify forecast accuracy include root-mean-square error and Theil inequality statistics. Formal statistical assessments are completed using four-pronged error differential regression F tests. Similar to studies for other metropolitan econometric forecasts in areas with similar demographic and labor market characteristics, model predictive performances for the municipal water aggregates in this effort are mixed for each of the municipalities included in the sample. Given the competitiveness of the benchmarks, analysts should employ care when utilizing econometric forecasts of municipal water consumption for planning purposes, comparing them to recent historical observations and trends to insure reliability. Comparative results using data from other markets, including regions facing differing labor and demographic conditions, would also be helpful.

  11. 76 FR 35024 - Precision Dynamics Corporation San Fernando, CA; Precision Dynamics Corporation, Also Known as...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-15

    ... Employment and Training Administration Precision Dynamics Corporation San Fernando, CA; Precision Dynamics... for Worker Adjustment Assistance on January 28, 2011, applicable to workers of Precision Dynamics... the subject firm. The Valencia, California location of Precision Dynamics Corporation, also known...

  12. Beyond precision surgery: Molecularly motivated precision care for gastric cancer.

    PubMed

    Choi, Y Y; Cheong, J-H

    2017-03-01

    Gastric cancer is one of the leading causes of cancer-related deaths worldwide. Despite the high disease prevalence, gastric cancer research has not gained much attention. Recently, genome-scale technology has made it possible to explore the characteristics of gastric cancer at the molecular level. Accordingly, gastric cancer can be classified into molecular subtypes that convey more detailed information of tumor than histopathological characteristics, and these subtypes are associated with clinical outcomes. Furthermore, this molecular knowledge helps to identify new actionable targets and develop novel therapeutic strategies. To advance the concept of precision patient care in the clinic, patient-derived xenograft (PDX) models have recently been developed. PDX models not only represent histology and genomic features, but also predict responsiveness to investigational drugs in patient tumors. Molecularly curated PDX cohorts will be instrumental in hypothesis generation, biomarker discovery, and drug screening and testing in proof-of-concept preclinical trials for precision therapy. In the era of precision medicine, molecularly tailored therapeutic strategies should be individualized for cancer patients. To improve the overall clinical outcome, a multimodal approach is indispensable for advanced cancer patients. Careful, oncological principle-based surgery, combined with a molecularly guided multidisciplinary approach, will open new horizons in surgical oncology.

  13. Time and position accuracy using codeless GPS

    NASA Technical Reports Server (NTRS)

    Dunn, C. E.; Jefferson, D. C.; Lichten, S. M.; Thomas, J. B.; Vigue, Y.; Young, L. E.

    1994-01-01

    The Global Positioning System has allowed scientists and engineers to make measurements having accuracy far beyond the original 15 meter goal of the system. Using global networks of P-Code capable receivers and extensive post-processing, geodesists have achieved baseline precision of a few parts per billion, and clock offsets have been measured at the nanosecond level over intercontinental distances. A cloud hangs over this picture, however. The Department of Defense plans to encrypt the P-Code (called Anti-Spoofing, or AS) in the fall of 1993. After this event, geodetic and time measurements will have to be made using codeless GPS receivers. However, there appears to be a silver lining to the cloud. In response to the anticipated encryption of the P-Code, the geodetic and GPS receiver community has developed some remarkably effective means of coping with AS without classified information. We will discuss various codeless techniques currently available and the data noise resulting from each. We will review some geodetic results obtained using only codeless data, and discuss the implications for time measurements. Finally, we will present the status of GPS research at JPL in relation to codeless clock measurements.

  14. Firing temperature accuracy of four dental furnaces.

    PubMed

    Haag, Per; Ciber, Edina; Dérand, Tore

    2011-01-01

    In spite of using recommended firing and displayed temperatures, low-fired dental porcelain more often demonstrates unsatisfactory results after firing than porcelain fired at higher temperatures. It could therefore be anticipated that temperatures shown on the display are incorrect, implying that the furnace does not render correct firing programs for low-fired porcelain. The purpose of this study is to investigate deviations from the real temperature during the firing process and also to illustrate the service and maintenance discipline of furnaces at dental laboratories. Totally 20 units of four different types of dental furnaces were selected for testing of temperature accuracy with usage of a digital temperature measurement apparatus, Therma 1. In addition,the staffs at 68 dental laboratories in Sweden were contacted for a telephone interview on furnace brand and on service and maintenance program performed at their laboratories. None of the 20 different dental furnaces in the study could generate the firing temperatures shown on the display, indicating that the hypothesis was correct. Multimat MCII had the least deviation of temperature compared with displayfigures. 62 out of 68 invited dental laboratories chose to participate in the interviews and the result was that very few laboratories had a service and maintenance program living up to quality standards. There is room for improving the precision of dental porcelain furnaces as there are deviations between displayed and read temperatures during the different steps of the firing process.

  15. Precise 3D image alignment in micro-axial tomography.

    PubMed

    Matula, P; Kozubek, M; Staier, F; Hausmann, M

    2003-02-01

    Micro (micro-) axial tomography is a challenging technique in microscopy which improves quantitative imaging especially in cytogenetic applications by means of defined sample rotation under the microscope objective. The advantage of micro-axial tomography is an effective improvement of the precision of distance measurements between point-like objects. Under certain circumstances, the effective (3D) resolution can be improved by optimized acquisition depending on subsequent, multi-perspective image recording of the same objects followed by reconstruction methods. This requires, however, a very precise alignment of the tilted views. We present a novel feature-based image alignment method with a precision better than the full width at half maximum of the point spread function. The features are the positions (centres of gravity) of all fluorescent objects observed in the images (e.g. cell nuclei, fluorescent signals inside cell nuclei, fluorescent beads, etc.). Thus, real alignment precision depends on the localization precision of these objects. The method automatically determines the corresponding objects in subsequently tilted perspectives using a weighted bipartite graph. The optimum transformation function is computed in a least squares manner based on the coordinates of the centres of gravity of the matched objects. The theoretically feasible precision of the method was calculated using computer-generated data and confirmed by tests on real image series obtained from data sets of 200 nm fluorescent nano-particles. The advantages of the proposed algorithm are its speed and accuracy, which means that if enough objects are included, the real alignment precision is better than the axial localization precision of a single object. The alignment precision can be assessed directly from the algorithm's output. Thus, the method can be applied not only for image alignment and object matching in tilted view series in order to reconstruct (3D) images, but also to validate the

  16. Temporal accuracy of human cortico-cortical interactions

    PubMed Central

    Abeles, Moshe

    2016-01-01

    The precision in space and time of interactions among multiple cortical sites was evaluated by examining repeating precise spatiotemporal patterns of instances in which cortical currents showed brief amplitude undulations. The amplitudes of the cortical current dipoles were estimated by applying a variant of synthetic aperture magnetometry to magnetoencephalographic (MEG) recordings of subjects tapping to metric auditory rhythms of drum beats. Brief amplitude undulations were detected in the currents by template matching at a rate of 2–3 per second. Their timing was treated as point processes, and precise spatiotemporal patterns were searched for. By randomly teetering these point processes within a time window W, we estimated the accuracy of the timing of these brief amplitude undulations and compared the results with those obtained by applying the same analysis to traces composed of random numbers. The results demonstrated that the timing accuracy of patterns was better than 3 ms. Successful classification of two different cognitive processes based on these patterns suggests that at least some of the repeating patterns are specific to a cognitive process. PMID:26843604

  17. Microwave Plasma Hydrogen Recovery System

    NASA Technical Reports Server (NTRS)

    Atwater, James; Wheeler, Richard, Jr.; Dahl, Roger; Hadley, Neal

    2010-01-01

    A microwave plasma reactor was developed for the recovery of hydrogen contained within waste methane produced by Carbon Dioxide Reduction Assembly (CRA), which reclaims oxygen from CO2. Since half of the H2 reductant used by the CRA is lost as CH4, the ability to reclaim this valuable resource will simplify supply logistics for longterm manned missions. Microwave plasmas provide an extreme thermal environment within a very small and precisely controlled region of space, resulting in very high energy densities at low overall power, and thus can drive high-temperature reactions using equipment that is smaller, lighter, and less power-consuming than traditional fixed-bed and fluidized-bed catalytic reactors. The high energy density provides an economical means to conduct endothermic reactions that become thermodynamically favorable only at very high temperatures. Microwave plasma methods were developed for the effective recovery of H2 using two primary reaction schemes: (1) methane pyrolysis to H2 and solid-phase carbon, and (2) methane oligomerization to H2 and acetylene. While the carbon problem is substantially reduced using plasma methods, it is not completely eliminated. For this reason, advanced methods were developed to promote CH4 oligomerization, which recovers a maximum of 75 percent of the H2 content of methane in a single reactor pass, and virtually eliminates the carbon problem. These methods were embodied in a prototype H2 recovery system capable of sustained high-efficiency operation. NASA can incorporate the innovation into flight hardware systems for deployment in support of future long-duration exploration objectives such as a Space Station retrofit, Lunar outpost, Mars transit, or Mars base. The primary application will be for the recovery of hydrogen lost in the Sabatier process for CO2 reduction to produce water in Exploration Life Support systems. Secondarily, this process may also be used in conjunction with a Sabatier reactor employed to

  18. Positioning Accuracy in Otosurgery Measured with Optical Tracking

    PubMed Central

    Óvári, Attila; Neményi, Dóra; Just, Tino; Schuldt, Tobias; Buhr, Anne; Mlynski, Robert; Csókay, András; Pau, Hans-Wilhelm; Valálik, István

    2016-01-01

    Objectives To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic training model with optical tracking. Study Design In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions. Methods Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises. Results Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons’ tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training. Conclusions Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons. PMID:27027500

  19. Green Solvents for Precision Cleaning

    NASA Technical Reports Server (NTRS)

    Grandelli, Heather; Maloney, Phillip; DeVor, Robert; Surma, Jan; Hintze, Paul

    2013-01-01

    Aerospace machinery used in liquid oxygen (LOX) fuel systems must be precision cleaned to achieve a very low level of non-volatile residue (< 1 mg0.1 m2), especially flammable residue. Traditionally chlorofluorocarbons (CFCs) have been used in the precision cleaning of LOX systems, specifically CFC 113 (C2Cl3F3). CFCs have been known to cause the depletion of ozone and in 1987, were banned by the Montreal Protocol due to health, safety and environmental concerns. This has now led to the development of new processes in the precision cleaning of aerospace components. An ideal solvent-replacement is non-flammable, environmentally benign, non-corrosive, inexpensive, effective and evaporates completely, leaving no residue. Highlighted is a green precision cleaning process, which is contaminant removal using supercritical carbon dioxide as the environmentally benign solvent. In this process, the contaminant is dissolved in carbon dioxide, and the parts are recovered at the end of the cleaning process completely dry and ready for use. Typical contaminants of aerospace components include hydrocarbon greases, hydraulic fluids, silicone fluids and greases, fluorocarbon fluids and greases and fingerprint oil. Metallic aerospace components range from small nuts and bolts to much larger parts, such as butterfly valves 18 in diameter. A fluorinated grease, Krytox, is investigated as a model contaminant in these preliminary studies, and aluminum coupons are employed as a model aerospace component. Preliminary studies are presented in which the experimental parameters are optimized for removal of Krytox from aluminum coupons in a stirred-batch process. The experimental conditions investigated are temperature, pressure, exposure time and impeller speed. Temperatures of 308 - 423 K, pressures in the range of 8.3 - 41.4 MPa, exposure times between 5 - 60 min and impeller speeds of 0 - 1000 rpm were investigated. Preliminary results showed up to 86 cleaning efficiency with the

  20. Method for grinding precision components

    DOEpatents

    Ramanath, Srinivasan; Kuo, Shih Yee; Williston, William H.; Buljan, Sergej-Tomislav

    2000-01-01

    A method for precision cylindrical grinding of hard brittle materials, such as ceramics or glass and composites comprising ceramics or glass, provides material removal rates as high as 19-380 cm.sup.3 /min/cm. The abrasive tools used in the method comprise a strong, light weight wheel core bonded to a continuous rim of abrasive segments containing superabrasive grain in a dense metal bond matrix.

  1. Method for grinding precision components

    SciTech Connect

    Ramanath, S.; Kuo, S.Y.; Williston, W.H.; Buljan, S.T.

    2000-02-01

    A method for precision cylindrical grinding of hard brittle materials, such as ceramics or glass and composites comprising ceramics or glass, provides material removal rates as high as 19--380 cm{sup 3}/min/cm. The abrasive tools used in the method comprise a strong, light weight wheel core bonded to a continuous rim of abrasive segments containing superabrasive grain in a dense metal bond matrix.

  2. Precision linear ramp function generator

    DOEpatents

    Jatko, W.B.; McNeilly, D.R.; Thacker, L.H.

    1984-08-01

    A ramp function generator is provided which produces a precise linear ramp function which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.

  3. High precision triangular waveform generator

    DOEpatents

    Mueller, Theodore R.

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  4. Precision linear ramp function generator

    DOEpatents

    Jatko, W. Bruce; McNeilly, David R.; Thacker, Louis H.

    1986-01-01

    A ramp function generator is provided which produces a precise linear ramp unction which is repeatable and highly stable. A derivative feedback loop is used to stabilize the output of an integrator in the forward loop and control the ramp rate. The ramp may be started from a selected baseline voltage level and the desired ramp rate is selected by applying an appropriate constant voltage to the input of the integrator.

  5. Solvent recycle/recovery

    SciTech Connect

    Paffhausen, M.W.; Smith, D.L.; Ugaki, S.N.

    1990-09-01

    This report describes Phase I of the Solvent Recycle/Recovery Task of the DOE Chlorinated Solvent Substitution Program for the US Air Force by the Idaho National Engineering Laboratory, EG G Idaho, Inc., through the US Department of Energy, Idaho Operations Office. The purpose of the task is to identify and test recovery and recycling technologies for proposed substitution solvents identified by the Biodegradable Solvent Substitution Program and the Alternative Solvents/Technologies for Paint Stripping Program with the overall objective of minimizing hazardous wastes. A literature search to identify recycle/recovery technologies and initial distillation studies has been conducted. 4 refs.

  6. Measuring Diagnoses: ICD Code Accuracy

    PubMed Central

    O'Malley, Kimberly J; Cook, Karon F; Price, Matt D; Wildes, Kimberly Raiford; Hurdle, John F; Ashton, Carol M

    2005-01-01

    Objective To examine potential sources of errors at each step of the described inpatient International Classification of Diseases (ICD) coding process. Data Sources/Study Setting The use of disease codes from the ICD has expanded from classifying morbidity and mortality information for statistical purposes to diverse sets of applications in research, health care policy, and health care finance. By describing a brief history of ICD coding, detailing the process for assigning codes, identifying where errors can be introduced into the process, and reviewing methods for examining code accuracy, we help code users more systematically evaluate code accuracy for their particular applications. Study Design/Methods We summarize the inpatient ICD diagnostic coding process from patient admission to diagnostic code assignment. We examine potential sources of errors at each step and offer code users a tool for systematically evaluating code accuracy. Principle Findings Main error sources along the “patient trajectory” include amount and quality of information at admission, communication among patients and providers, the clinician's knowledge and experience with the illness, and the clinician's attention to detail. Main error sources along the “paper trail” include variance in the electronic and written records, coder training and experience, facility quality-control efforts, and unintentional and intentional coder errors, such as misspecification, unbundling, and upcoding. Conclusions By clearly specifying the code assignment process and heightening their awareness of potential error sources, code users can better evaluate the applicability and limitations of codes for their particular situations. ICD codes can then be used in the most appropriate ways. PMID:16178999

  7. Recovery After Stroke: Healthy Eating

    MedlinePlus

    Recovery After Stroke: Healthy Eating Eating well after stroke is key to your recovery. Choosing healthy foods can help you keep up ... get the nutrition you need for your stroke recovery.  Eat your biggest meal early in the day ...

  8. Do not let precision medicine be kidnapped.

    PubMed

    Yang, Zhiping

    2015-12-01

    Obama’s precision medicine initiative made the medical community boil over after the initiative’s release. Precision medicine has been advocated by the majority of scientists and doctors. However, some experts have questioned this concept. This article does not oppose precision medicine. However, the incentive of vigorously promoting precision medicine at present is a concern.

  9. Precision GPS ephemerides and baselines

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The required knowledge of the Global Positioning System (GPS) satellite position accuracy can vary depending on a particular application. Application to relative positioning of receiver locations on the ground to infer Earth's tectonic plate motion requires the most accurate knowledge of the GPS satellite orbits. Research directed towards improving and evaluating the accuracy of GPS satellite orbits was conducted at the University of Texas Center for Space Research (CSR). Understanding and modeling the forces acting on the satellites was a major focus of the research. Other aspects of orbit determination, such as the reference frame, time system, measurement modeling, and parameterization, were also investigated. Gravitational forces were modeled by truncated versions of extant gravity fields such as, Goddard Earth Model (GEM-L2), GEM-T1, TEG-2, and third body perturbations due to the Sun and Moon. Nongravitational forces considered were the solar radiation pressure, and perturbations due to thermal venting and thermal imbalance. At the GPS satellite orbit accuracy level required for crustal dynamic applications, models for the nongravitational perturbation play a critical role, since the gravitational forces are well understood and are modeled adequately for GPS satellite orbits.

  10. Camera Sensor Arrangement for Crop/Weed Detection Accuracy in Agronomic Images

    PubMed Central

    Romeo, Juan; Guerrero, José Miguel; Montalvo, Martín; Emmi, Luis; Guijarro, María; Gonzalez-de-Santos, Pablo; Pajares, Gonzalo

    2013-01-01

    In Precision Agriculture, images coming from camera-based sensors are commonly used for weed identification and crop line detection, either to apply specific treatments or for vehicle guidance purposes. Accuracy of identification and detection is an important issue to be addressed in image processing. There are two main types of parameters affecting the accuracy of the images, namely: (a) extrinsic, related to the sensor's positioning in the tractor; (b) intrinsic, related to the sensor specifications, such as CCD resolution, focal length or iris aperture, among others. Moreover, in agricultural applications, the uncontrolled illumination, existing in outdoor environments, is also an important factor affecting the image accuracy. This paper is exclusively focused on two main issues, always with the goal to achieve the highest image accuracy in Precision Agriculture applications, making the following two main contributions: (a) camera sensor arrangement, to adjust extrinsic parameters and (b) design of strategies for controlling the adverse illumination effects. PMID:23549361

  11. Camera sensor arrangement for crop/weed detection accuracy in agronomic images.

    PubMed

    Romeo, Juan; Guerrero, José Miguel; Montalvo, Martín; Emmi, Luis; Guijarro, María; Gonzalez-de-Santos, Pablo; Pajares, Gonzalo

    2013-04-02

    In Precision Agriculture, images coming from camera-based sensors are commonly used for weed identification and crop line detection, either to apply specific treatments or for vehicle guidance purposes. Accuracy of identification and detection is an important issue to be addressed in image processing. There are two main types of parameters affecting the accuracy of the images, namely: (a) extrinsic, related to the sensor's positioning in the tractor; (b) intrinsic, related to the sensor specifications, such as CCD resolution, focal length or iris aperture, among others. Moreover, in agricultural applications, the uncontrolled illumination, existing in outdoor environments, is also an important factor affecting the image accuracy. This paper is exclusively focused on two main issues, always with the goal to achieve the highest image accuracy in Precision Agriculture applications, making the following two main contributions: (a) camera sensor arrangement, to adjust extrinsic parameters and (b) design of strategies for controlling the adverse illumination effects.

  12. Precision guided parachute LDRD final report

    SciTech Connect

    Gilkey, J.C.

    1996-07-01

    This report summarizes the results of the Precision Guided Parachute LDRD, a two year program at Sandia National Laboratories which developed a Global Positioning System (GPS) guided parachute capable of autonomous flight and landings. A detailed computer model of a gliding parachute was developed for software only simulations. A hardware in-the-loop simulator was developed and used for flight package system integration and design validation. Initial parachute drop tests were conducted at Sandia`s Coyote Canyon Cable Facility, followed by a series of airdrops using Ross Aircraft`s Twin Otter at the Burris Ranch Drop Zone. Final flights demonstrated in-flight wind estimation and the capability to fly a commanded heading. In the past, the cost and logistical complexity of an initial navigation system ruled out actively guiding a parachute. The advent of the low-cost, light-weight Global Positioning System (GPS) has eliminated this barrier. By using GPS position and velocity measurements, a guided parachute can autonomously steer itself to a targeted point on the ground through the use of control drums attached to the control lanyards of the parachute. By actively correcting for drop point errors and wind drift, the guidance accuracy of this system should be on the order of GPS position errors. This would be a significant improvement over unguided airdrops which may have errors of a mile or more.

  13. Thermal expansion as a precision actuator

    NASA Astrophysics Data System (ADS)

    Miller, Chris; Montgomery, David; Black, Martin; Schnetler, Hermine

    2016-07-01

    The UK ATC has developed a novel thermal actuator design as part of an OPTICON project focusing on the development of a Freeform Active Mirror Element (FAME). The actuator uses the well understood concept of thermal expansion to generate the required force and displacement. As heat is applied to the actuator material it expands linearly. A resistance temperature device (RTD) is embedded in the centre of the actuator and is used both as a heater and a sensor. The RTD temperature is controlled electronically by injecting a varying amount of current into the device whilst measuring the voltage across it. Temperature control of the RTD has been achieved to within 0.01°C. A 3D printed version of the actuator is currently being used at the ATC to deform a mirror but it has several advantages that may make it suitable to other applications. The actuator is cheap to produce whilst obtaining a high accuracy and repeatability. The actuator design would be suitable for applications requiring large numbers of actuators with high precision.

  14. Mapmaking for precision 21 cm cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Tegmark, Max; Liu, Adrian; Ewall-Wice, Aaron; Hewitt, Jacqueline N.; Morales, Miguel F.; Neben, Abraham R.; Parsons, Aaron R.; Zheng, Haoxuan

    2015-01-01

    In order to study the "Cosmic Dawn" and the Epoch of Reionization with 21 cm tomography, we need to statistically separate the cosmological signal from foregrounds known to be orders of magnitude brighter. Over the last few years, we have learned much about the role our telescopes play in creating a putatively foreground-free region called the "EoR window." In this work, we examine how an interferometer's effects can be taken into account in a way that allows for the rigorous estimation of 21 cm power spectra from interferometric maps while mitigating foreground contamination and thus increasing sensitivity. This requires a precise understanding of the statistical relationship between the maps we make and the underlying true sky. While some of these calculations would be computationally infeasible if performed exactly, we explore several well-controlled approximations that make mapmaking and the calculation of map statistics much faster, especially for compact and highly redundant interferometers designed specifically for 21 cm cosmology. We demonstrate the utility of these methods and the parametrized trade-offs between accuracy and speed using one such telescope, the upcoming Hydrogen Epoch of Reionization Array, as a case study.

  15. Precise Global DEM Generation by ALOS PRISM

    NASA Astrophysics Data System (ADS)

    Tadono, T.; Ishida, H.; Oda, F.; Naito, S.; Minakawa, K.; Iwamoto, H.

    2014-04-01

    The Japan Aerospace Exploration Agency (JAXA) generated the global digital elevation/surface model (DEM/DSM) and orthorectified image (ORI) using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi"), which was operated from 2006 to 2011. PRISM consisted of three panchromatic radiometers that acquired along-track stereo images. It had a spatial resolution of 2.5 m in the nadir-looking radiometer and achieved global coverage, making it a suitable potential candidate for precise global DSM and ORI generation. In the past 10 years or so, JAXA has conducted the calibration of the system corrected standard products of PRISM in order to improve absolute accuracies as well as to validate the high-level products such as DSM and ORI. In this paper, we introduce an overview of the global DEM/DSM dataset generation project, including a summary of ALOS and PRISM, in addition to the global data archive status. It is also necessary to consider data processing strategies, since the processing capabilities of the level 1 standard product and the high-level products must be developed in terms of both hardware and software to achieve the project aims. The automatic DSM/ORI processing software and its test processing results are also described.

  16. Millisecond, micron precision multi-whisker detector.

    PubMed

    Grady, Stephen K; Hoang, Thanh T; Gautam, Shree Hari; Shew, Woodrow L

    2013-01-01

    The neural mechanisms of somatosensory information processing in the rodent vibrissae system are a topic of intense debate and research. Certain hypotheses emphasize the importance of stick-slip whisker motion, high-frequency resonant vibrations, and/or the ability to decode complex textures. Other hypotheses focus on the importance of integrating information from multiple whiskers. Tests of the former require measurements of whisker motion that achieve high spatiotemporal accuracy without altering the mechanical properties of whiskers. Tests of the latter require the ability to monitor the motion of multiple whiskers simultaneously. Here we present a device that achieves both these requirements for two-dimensional whisker motion in the plane perpendicular to the whiskers. Moreover, the system we present is significantly less expensive (<$2.5 k) and simpler to build than alternative devices which achieve similar detection capabilities. Our system is based on two laser diodes and two linear cameras. It attains millisecond temporal precision and micron spatial resolution. We developed automated algorithms for processing the data collected by our device and benchmarked their performance against manual detection by human visual inspection. By this measure, our detection was successful with less than 10 µm deviation between the automated and manual detection, on average. Here, we demonstrate its utility in anesthetized rats by measuring the motion of multiple whiskers in response to an air puff.

  17. Precision Saturated Absorption Spectroscopy of H3+

    NASA Astrophysics Data System (ADS)

    Guan, Yu-chan; Liao, Yi-Chieh; Chang, Yung-Hsiang; Peng, Jin-Long; Shy, Jow-Tsong

    2016-06-01

    In our previous work on the Lamb dips of the νb{2} fundamental band of H3+, the saturated absorption spectrum was obtained by the third-derivative spectroscopy using frequency modulation [1]. However, the frequency modulation also causes error in absolute frequency determination. To solve this problem, we have built an offset-locking system to lock the OPO pump frequency to an iodine-stabilized Nd:YAG laser. With this modification, we are able to scan the OPO idler frequency precisely and obtain the profile of the Lamb dips. Double modulation (amplitude modulation of the idler power and concentration modulation of the ion) is employed to subtract the interference fringes of the signal and increase the signal-to-noise ratio effectively. To Determine the absolute frequency of the idler wave, the pump wave is offset locked on the R(56) 32-0 a10 hyperfine component of 127I2, and the signal wave is locked on a GPS disciplined fiber optical frequency comb (OFC). All references and lock systems have absolute frequency accuracy better than 10 kHz. Here, we demonstrate its performance by measuring one transition of methane and sixteen transitions of H3+. This instrument could pave the way for the high-resolution spectroscopy of a variety of molecular ions. [1] H.-C. Chen, C.-Y. Hsiao, J.-L. Peng, T. Amano, and J.-T. Shy, Phys. Rev. Lett. 109, 263002 (2012).

  18. RECOVERY OF RUTHENIUM VALUES

    DOEpatents

    Grummitt, W.E.; Hardwick, W.H.

    1961-01-01

    A process is given for the recovery of ruthenium from its aqueous solutions by oxidizing the ruthenium to the octavalent state and subsequently extracting the ruthenium into a halogen-substituted liquid paraffin.

  19. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  20. Knowledge discovery by accuracy maximization

    PubMed Central

    Cacciatore, Stefano; Luchinat, Claudio; Tenori, Leonardo

    2014-01-01

    Here we describe KODAMA (knowledge discovery by accuracy maximization), an unsupervised and semisupervised learning algorithm that performs feature extraction from noisy and high-dimensional data. Unlike other data mining methods, the peculiarity of KODAMA is that it is driven by an integrated procedure of cross-validation of the results. The discovery of a local manifold’s topology is led by a classifier through a Monte Carlo procedure of maximization of cross-validated predictive accuracy. Briefly, our approach differs from previous methods in that it has an integrated procedure of validation of the results. In this way, the method ensures the highest robustness of the obtained solution. This robustness is demonstrated on experimental datasets of gene expression and metabolomics, where KODAMA compares favorably with other existing feature extraction methods. KODAMA is then applied to an astronomical dataset, revealing unexpected features. Interesting and not easily predictable features are also found in the analysis of the State of the Union speeches by American presidents: KODAMA reveals an abrupt linguistic transition sharply separating all post-Reagan from all pre-Reagan speeches. The transition occurs during Reagan’s presidency and not from its beginning. PMID:24706821