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Sample records for corrective measures study

  1. Internal tibial torsion correction study. [measurements of strain for corrective rotation of stressed tibia

    Science.gov (United States)

    Cantu, J. M.; Madigan, C. M.

    1974-01-01

    A quantitative study of internal torsion in the entire tibial bone was performed by using strain gauges to measure the amount of deformation occuring at different locations. Comparison of strain measurements with physical dimensions of the bone produced the modulus of rigidity and its behavior under increased torque. Computerized analysis of the stress distribution shows that more strain occurs near the torqued ends of the bones where also most of the twisting and fracturing takes place.

  2. Studies on the true coincidence correction in measuring filter samples by gamma spectrometry

    CERN Document Server

    Lian Qi; Chang Yong Fu; Xia Bing

    2002-01-01

    The true coincidence correction in measuring filter samples has been studied by high efficiency HPGe gamma detectors. The true coincidence correction for a specific three excited levels de-excitation case has been analyzed, and the typical analytical expressions of true coincidence correction factors have been given. According to the measured relative efficiency on the detector surface with 8 'single' energy gamma emitters and efficiency of filter samples, the peak and total efficiency surfaces are fitted. The true coincidence correction factors of sup 6 sup 0 Co and sup 1 sup 5 sup 2 Eu calculated by the efficiency surfaces agree well with experimental results

  3. Correcting for multivariate measurement error by regression calibration in meta-analyses of epidemiological studies

    DEFF Research Database (Denmark)

    Tybjærg-Hansen, Anne

    2009-01-01

    Within-person variability in measured values of multiple risk factors can bias their associations with disease. The multivariate regression calibration (RC) approach can correct for such measurement error and has been applied to studies in which true values or independent repeat measurements of t...

  4. Resource Conservation and Recovery Act corrective measures study: Area 6 decontamination pond facility, corrective action unit no. 92

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    Corrective Action Unit (CAU) No. 92, the Area 6 Decontamination Pond Facility (DPF), is an historic disposal unit located at the Nevada Test Site (NTS) in Nye County, Nevada (Figures 1 - 1, 1-2, and 1-3). The NTS is operated by the U.S. Department of Energy, Nevada Operations Office (DOE/NV), which has been required by the Nevada Division of Environmental Protection (NDEP) to characterize the DPF under the requirements of the Resource Conservation and Recovery Act (RCRA) Part A Permit (NDEP, 1995) for the NTS and Title 40 Code of Federal Regulations (CFR) Part 265 (1996c). The DPF is prioritized in the Federal Facility Agreement and Consent Order (FFACO, 1996) but is governed by the permit. The DPF was characterized through sampling events in 1994, 1996, and 1997. The results of these sampling events are contained in the Final Resource Conservation and Recovery Act Industrial Site Environmental Restoration Site Characterization Report, Area 6 Decontamination Pond Facility, Revision I (DOE/NV, 1997). This Corrective Measures Study (CMS) for the Area 6 DPF has been prepared for the DOE/NV`s Environmental Restoration Project. The CMS has been developed to support the preparation of a Closure Plan for the DPF. Because of the complexities of the contamination and regulatory issues associated with the DPF, DOE/NV determined a CMS would be beneficial to the evaluation and selection of a closure alternative.

  5. Mixed waste landfill corrective measures study final report Sandia National Laboratories, Albuquerque, New Mexico.

    Energy Technology Data Exchange (ETDEWEB)

    Peace, Gerald (Jerry) L.; Goering, Timothy James (GRAM, Inc., Albuquerque, NM)

    2004-03-01

    The Mixed Waste Landfill occupies 2.6 acres in the north-central portion of Technical Area 3 at Sandia National Laboratories, Albuquerque, New Mexico. The landfill accepted low-level radioactive and mixed waste from March 1959 to December 1988. This report represents the Corrective Measures Study that has been conducted for the Mixed Waste Landfill. The purpose of the study was to identify, develop, and evaluate corrective measures alternatives and recommend the corrective measure(s) to be taken at the site. Based upon detailed evaluation and risk assessment using guidance provided by the U.S. Environmental Protection Agency and the New Mexico Environment Department, the U.S. Department of Energy and Sandia National Laboratories recommend that a vegetative soil cover be deployed as the preferred corrective measure for the Mixed Waste Landfill. The cover would be of sufficient thickness to store precipitation, minimize infiltration and deep percolation, support a healthy vegetative community, and perform with minimal maintenance by emulating the natural analogue ecosystem. There would be no intrusive remedial activities at the site and therefore no potential for exposure to the waste. This alternative poses minimal risk to site workers implementing institutional controls associated with long-term environmental monitoring as well as routine maintenance and surveillance of the site.

  6. Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams

    DEFF Research Database (Denmark)

    Azangwe, Godfrey; Grochowska, Paulina; Georg, Dietmar

    2014-01-01

    Purpose: The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially u...... measurements, the authors recommend the use of detectors that require relatively little correction, such as unshielded diodes, diamond detectors or microchambers, and solid state detectors such as alanine, TLD, Al2O3:C, or scintillators.......Purpose: The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially...... useful as a reference data set for small beam dosimetry measurements. Methods: Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm2 to 4.2 × 4.2 cm2 and the measurements were extended to larger fields...

  7. Study on the modification of measured wavefront aberration data for customized visual correction

    Science.gov (United States)

    Liu, Ming; Zhang, Yong; Zhang, Zhidong; Quan, Wei; An, Li

    2008-12-01

    Wavefront aberration of human eye is an important foundation for customized vision correction. In most current aberrometers, near infrared light is used to measure ocular wavefront aberration, whereas for customized visual correction, wavefront aberration data in visible range are required. With the measured wavefront aberration, corneal topography and eye's axial lengths data, individual eye models for twenty normal human eyes are constructed with the optical design software ZEMAX. Changing the incidence light wavelength and the refractive indexes of eye models, the values of defocus, astigmatism, higher-order aberrations in the measuring wavelength (833nm) and at the most sensitive wavelength of human eye (555nm) are obtained. Average focus shift between 833nm and 555nm is found to be about 0.94D, and different slightly for different individuals; the differences of astigmatism and higher-order aberrations between 833nm and 555nm are quite slight. For customized visual correction, the measured defocus value should be modified, whereas the measured astigmatism and higher-order aberrations could be used directly for the current correction precision. Individual eye model is a useful tool for accurate transformation of the measured wavefront aberration data into the data for visible spectrum.

  8. Detector to detector corrections: A comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Azangwe, Godfrey, E-mail: g.azangwe@iaea.org; Grochowska, Paulina; Izewska, Joanna; Meghzifene, Ahmed [International Atomic Energy Agency, Vienna International Centre, PO Box 100, 1400 Vienna (Austria); Georg, Dietmar; Hopfgartner, Johannes; Lechner, Wolfgang [Department of Radiation Oncology, Medical University Vienna/AKH Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria and Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University Vienna, Vienna, Währinger Gürtel 18-20, A-1090 Vienna (Austria); Andersen, Claus E.; Beierholm, Anders R.; Helt-Hansen, Jakob [Center for Nuclear Technologies, Technical University of Denmark, Risø Campus, DK-4000 Roskilde (Denmark); Mizuno, Hideyuki; Fukumura, Akifumi [National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi 263-8555 (Japan); Yajima, Kaori [Association for Nuclear Technology in Medicine, 7-16, Nihonbashikodenmacho, chuou-ku, Tokyo 103-0001 (Japan); Gouldstone, Clare; Sharpe, Peter [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW (United Kingdom); Palmans, Hugo [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom and EBG MedAustron GmbH, Medical Physics Department, A-2700 Wiener Neustadt (Austria)

    2014-07-15

    Purpose: The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially useful as a reference data set for small beam dosimetry measurements. Methods: Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm{sup 2} to 4.2 × 4.2 cm{sup 2} and the measurements were extended to larger fields of up to 10 × 10 cm{sup 2}. Measurements were performed at 5 cm depth, in a 6 MV photon beam. Detectors used included alanine, thermoluminescent dosimeters (TLDs), stereotactic diode, electron diode, photon diode, radiophotoluminescent dosimeters (RPLDs), radioluminescence detector based on carbon-doped aluminium oxide (Al{sub 2}O{sub 3}:C), organic plastic scintillators, diamond detectors, liquid filled ion chamber, and a range of small volume air filled ionization chambers (volumes ranging from 0.002 cm{sup 3} to 0.3 cm{sup 3}). All detector measurements were corrected for volume averaging effect and compared with dose ratios determined from alanine to derive a detector correction factors that account for beam perturbation related to nonwater equivalence of the detector materials. Results: For the detectors used in this study, volume averaging corrections ranged from unity for the smallest detectors such as the diodes, 1.148 for the 0.14 cm{sup 3} air filled ionization chamber and were as high as 1.924 for the 0.3 cm{sup 3} ionization chamber. After applying volume averaging corrections, the detector readings were consistent among themselves and with alanine measurements for several small detectors but they differed for larger detectors, in particular for some small ionization chambers with volumes larger than 0.1 cm{sup 3}. Conclusions: The results demonstrate

  9. Measuring coverage in MNCH: a prospective validation study in Pakistan and Bangladesh on measuring correct treatment of childhood pneumonia.

    Directory of Open Access Journals (Sweden)

    Tabish Hazir

    Full Text Available Antibiotic treatment for pneumonia as measured by Demographic and Health Surveys (DHS and Multiple Indicator Cluster Surveys (MICS is a key indicator for tracking progress in achieving Millennium Development Goal 4. Concerns about the validity of this indicator led us to perform an evaluation in urban and rural settings in Pakistan and Bangladesh.Caregivers of 950 children under 5 y with pneumonia and 980 with "no pneumonia" were identified in urban and rural settings and allocated for DHS/MICS questions 2 or 4 wk later. Study physicians assigned a diagnosis of pneumonia as reference standard; the predictive ability of DHS/MICS questions and additional measurement tools to identify pneumonia versus non-pneumonia cases was evaluated. Results at both sites showed suboptimal discriminative power, with no difference between 2- or 4-wk recall. Individual patterns of sensitivity and specificity varied substantially across study sites (sensitivity 66.9% and 45.5%, and specificity 68.8% and 69.5%, for DHS in Pakistan and Bangladesh, respectively. Prescribed antibiotics for pneumonia were correctly recalled by about two-thirds of caregivers using DHS questions, increasing to 72% and 82% in Pakistan and Bangladesh, respectively, using a drug chart and detailed enquiry.Monitoring antibiotic treatment of pneumonia is essential for national and global programs. Current (DHS/MICS questions and proposed new (video and pneumonia score methods of identifying pneumonia based on maternal recall discriminate poorly between pneumonia and children with cough. Furthermore, these methods have a low yield to identify children who have true pneumonia. Reported antibiotic treatment rates among these children are therefore not a valid proxy indicator of pneumonia treatment rates. These results have important implications for program monitoring and suggest that data in its current format from DHS/MICS surveys should not be used for the purpose of monitoring antibiotic

  10. Measurement error correction for the cumulative average model in the survival analysis of nutritional data: application to Nurses' Health Study.

    Science.gov (United States)

    Qiu, Weiliang; Rosner, Bernard

    2010-01-01

    The use of the cumulative average model to investigate the association between disease incidence and repeated measurements of exposures in medical follow-up studies can be dated back to the 1960s (Kahn and Dawber, J Chron Dis 19:611-620, 1966). This model takes advantage of all prior data and thus should provide a statistically more powerful test of disease-exposure associations. Measurement error in covariates is common for medical follow-up studies. Many methods have been proposed to correct for measurement error. To the best of our knowledge, no methods have been proposed yet to correct for measurement error in the cumulative average model. In this article, we propose a regression calibration approach to correct relative risk estimates for measurement error. The approach is illustrated with data from the Nurses' Health Study relating incident breast cancer between 1980 and 2002 to time-dependent measures of calorie-adjusted saturated fat intake, controlling for total caloric intake, alcohol intake, and baseline age.

  11. Corrective Change of Retinal Thickness Measured by Optical Coherence Tomography and Histologic Studies

    Institute of Scientific and Technical Information of China (English)

    GeJ; LuoRJ

    1999-01-01

    Purpose:To evaluate the correlation of retinal thickness between optical coherence tomography(OCT)images and histologic slides.Methods:Retinal thickness was measured in 16 rabbit retinal histologic slides.The same eyes has been previously measured by OCT fr the comparison of results between two methods.Retinal thickness of each OCT image section was measured using both the manually assisted(requiring localization of reflectivity peaks by observer)and automated modes of the computer software.Results:Retinal thickness measured by OCT demonstrated a high degree of correlation with retinal histologic study.The automated method(Cc=0.66,P<0.01) was less reliable than the manually assisted one (Cc=0.84,P<0.001).The former had an error in 95% confidence interval,ranged between-0.71 and 11.09μm.The latter had a less error,ranged from -2.99 to 5.13μm.Conclusion:OCT can quantitatively measure the retinal thickness.However,automatical identification of the reflective boundaries by computer may result in errors in some cases.To masure the retinal thickess by manually assisted mode can increase the accuracy.

  12. Study of Top Dead Center Measurement and Correction Method in a Diesel Engine

    Directory of Open Access Journals (Sweden)

    Ruijiao Miao

    2013-06-01

    Full Text Available The thermal loss angle error analysis and maximum pressure determination method analysis were conducted first. Then the polytropic exponent method, the inflection point analysis, the loss function method and the symmetry method were utilized under different rotating speed, load and cooling water temperature, to calculate TDC in D6114 diesel engine and the results were compared with TDC position measured under the same condition with direct method of measurement. The study proved that (1 thermal loss angle of the diesel engine ranges from -1.0 ~ -0.6°CA; (2 Thermal loss angle is mainly affected by rotating speed and is reducing when rotate speed increases;(3 the symmetry method is generally the optimum for calculating the thermal loss angle of automotive diesel engines, with an error within 0.2°CA.

  13. Correction of errors in power measurements

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen

    1998-01-01

    Small errors in voltage and current measuring transformers cause inaccuracies in power measurements.In this report correction factors are derived to compensate for such errors.......Small errors in voltage and current measuring transformers cause inaccuracies in power measurements.In this report correction factors are derived to compensate for such errors....

  14. Simplified correction of g-value measurements

    DEFF Research Database (Denmark)

    Duer, Karsten

    1998-01-01

    A double glazed unit (Ipasol Natura 66/34) has been investigated in the Danish experimental setup METSET. The corrections of the experimental data are very important for the investigated sample as it shows significant spectral selectivity. In (Duer, 1998) and in (Platzer, 1998) the corrections have...... been carried out using a detailed physical model based on ISO9050 and prEN410 but using polarized data for non-normal incidence. This model is only valid for plane, clear glazings and therefor not suited for corrections of measurements performed on complex glazings. To investigate a more general...... correction procedure the results from the measurements on the Interpane DGU have been corrected using the principle outlined in (Rosenfeld, 1996). This correction procedure is more general as corrections can be carried out without a correct physical model of the investigated glazing. On the other hand...

  15. Phase I Focused Corrective Measures Study/Feasibility Study for the L-Area Oil and Chemical Basin (904-83G)

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-02-01

    This report presents the completed Resource Conservation and Recovery Act (RCRA) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Focused Corrective Measures Study/Feasibility Study (CMS/FS) for the L-Area Oil and Chemical Basin (LAOCB)/L-Area Acid Caustic Basin (9LAACB) Solid Waste Management Unit/Operable Unit (SWMU/OU) at the Savannah River Site (SRS).

  16. Measurement Error Correction Formula for Cluster-Level Group Differences in Cluster Randomized and Observational Studies

    Science.gov (United States)

    Cho, Sun-Joo; Preacher, Kristopher J.

    2016-01-01

    Multilevel modeling (MLM) is frequently used to detect cluster-level group differences in cluster randomized trial and observational studies. Group differences on the outcomes (posttest scores) are detected by controlling for the covariate (pretest scores) as a proxy variable for unobserved factors that predict future attributes. The pretest and…

  17. Correcting for static shift of magnetotelluric data with airborne electromagnetic measurements: a case study from Rathlin Basin, Northern Ireland

    Science.gov (United States)

    Delhaye, Robert; Rath, Volker; Jones, Alan G.; Muller, Mark R.; Reay, Derek

    2017-05-01

    Galvanic distortions of magnetotelluric (MT) data, such as the static-shift effect, are a known problem that can lead to incorrect estimation of resistivities and erroneous modelling of geometries with resulting misinterpretation of subsurface electrical resistivity structure. A wide variety of approaches have been proposed to account for these galvanic distortions, some depending on the target area, with varying degrees of success. The natural laboratory for our study is a hydraulically permeable volume of conductive sediment at depth, the internal resistivity structure of which can be used to estimate reservoir viability for geothermal purposes; however, static-shift correction is required in order to ensure robust and precise modelling accuracy.We present here a possible method to employ frequency-domain electromagnetic data in order to correct static-shift effects, illustrated by a case study from Northern Ireland. In our survey area, airborne frequency domain electromagnetic (FDEM) data are regionally available with high spatial density. The spatial distributions of the derived static-shift corrections are analysed and applied to the uncorrected MT data prior to inversion. Two comparative inversion models are derived, one with and one without static-shift corrections, with instructive results. As expected from the one-dimensional analogy of static-shift correction, at shallow model depths, where the structure is controlled by a single local MT site, the correction of static-shift effects leads to vertical scaling of resistivity-thickness products in the model, with the corrected model showing improved correlation to existing borehole wireline resistivity data. In turn, as these vertical scalings are effectively independent of adjacent sites, lateral resistivity distributions are also affected, with up to half a decade of resistivity variation between the models estimated at depths down to 2000 m. Simple estimation of differences in bulk porosity, derived using

  18. Techniques for transparent lattice measurement and correction

    Science.gov (United States)

    Cheng, Weixing; Li, Yongjun; Ha, Kiman

    2017-07-01

    A novel method has been successfully demonstrated at NSLS-II to characterize the lattice parameters with gated BPM turn-by-turn (TbT) capability. This method can be used at high current operation. Conventional lattice characterization and tuning are carried out at low current in dedicated machine studies which include beam-based measurement/correction of orbit, tune, dispersion, beta-beat, phase advance, coupling etc. At the NSLS-II storage ring, we observed lattice drifting during beam accumulation in user operation. Coupling and lifetime change while insertion device (ID) gaps are moved. With the new method, dynamical lattice correction is possible to achieve reliable and productive operations. A bunch-by-bunch feedback system excites a small fraction (∼1%) of bunches and gated BPMs are aligned to see those bunch motions. The gated TbT position data are used to characterize the lattice hence correction can be applied. As there are ∼1% of total charges disturbed for a short period of time (several ms), this method is transparent to general user operation. We demonstrated the effectiveness of these tools during high current user operation.

  19. On Association Measures for Continuous Variables and Correction for Chance

    NARCIS (Netherlands)

    Warrens, Matthijs J.

    2015-01-01

    This paper studies correction for chance for association measures for continuous variables. The set of linear transformations of Pearson's product-moment correlation is used as the domain of the correction for chance function. Examples of measures in this set are Tucker's congruence coefficient, Job

  20. Algorithmic Error Correction of Impedance Measuring Sensors

    Science.gov (United States)

    Starostenko, Oleg; Alarcon-Aquino, Vicente; Hernandez, Wilmar; Sergiyenko, Oleg; Tyrsa, Vira

    2009-01-01

    This paper describes novel design concepts and some advanced techniques proposed for increasing the accuracy of low cost impedance measuring devices without reduction of operational speed. The proposed structural method for algorithmic error correction and iterating correction method provide linearization of transfer functions of the measuring sensor and signal conditioning converter, which contribute the principal additive and relative measurement errors. Some measuring systems have been implemented in order to estimate in practice the performance of the proposed methods. Particularly, a measuring system for analysis of C-V, G-V characteristics has been designed and constructed. It has been tested during technological process control of charge-coupled device CCD manufacturing. The obtained results are discussed in order to define a reasonable range of applied methods, their utility, and performance. PMID:22303177

  1. Algorithmic Error Correction of Impedance Measuring Sensors

    Directory of Open Access Journals (Sweden)

    Vira Tyrsa

    2009-12-01

    Full Text Available This paper describes novel design concepts and some advanced techniques proposed for increasing the accuracy of low cost impedance measuring devices without reduction of operational speed. The proposed structural method for algorithmic error correction and iterating correction method provide linearization of transfer functions of the measuring sensor and signal conditioning converter, which contribute the principal additive and relative measurement errors. Some measuring systems have been implemented in order to estimate in practice the performance of the proposed methods. Particularly, a measuring system for analysis of C-V, G-V characteristics has been designed and constructed. It has been tested during technological process control of charge-coupled device CCD manufacturing. The obtained results are discussed in order to define a reasonable range of applied methods, their utility, and performance.

  2. Study of a model for correcting the effects of horizontal advection on surface fluxes measurement based on remote sensing

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>As well known, the methods of remote sensing and Bowen Ratio for retrieving surface flux are based on energy balance closure; however, in most cases, surface energy observed in experiment is lack of closure. There are two main causes for this: one is from the errors of the observation devices and the differences of their observational scale; the other lies in the effect of horizontal advection on the surface flux measurement. Therefore, it is very important to estimate the effects of horizontal advection quantitatively. Based on the local advection theory and the surface experiment, a model has been proposed for correcting the effect of horizontal advection on surface flux measurement, in which the relationship between the fetch of the measurement and pixel size for remote sensed data was considered. By means of numerical simulations, the sensitivities of the main parameters in the model and the scaling problems of horizontal advection were analyzed. At last, by using the observational data acquired in agricultural field with relatively homogeneous surface, the model was validated.

  3. COUPLING MEASUREMENT AND CORRECTION AT RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    PILAT,F.; BEEBE-WANG,J.; FISCHER,W.; PTITSYN,V.; SATOGATA,T.

    2002-06-02

    Coupling correction at RHIC has been operationally achieved through a two-step process: using local triplet skew quadrupoles to compensate coupling corn rolled low-beta triplet quadrupoles, and minimizing the tune separation and residual coupling with orthogonal global skew quadrupole families. An application has been developed for global correction that allows skew quadrupole tuning and tune display with a choice of different tune measurement techniques, including tune-meter, Schottky and phase lock loop (PLL). Coupling effects have been analysed by using 1024-turn (TBT) information from the beam position monitor (BPM) system. These data allow the reconstruction of the off-diagonal terms of the transfer matrix, a measure of global coupling. At both injection and storage energies, coordination of tune meter kicks with TBT acquisition at 322 BPM's in each ring allows the measurement of local coupling at all BPM locations.

  4. Individualized correction of insulin measurement in hemolyzed serum samples.

    Science.gov (United States)

    Wu, Zhi-Qi; Lu, Ju; Chen, Huanhuan; Chen, Wensen; Xu, Hua-Guo

    2016-11-05

    Insulin measurement plays a key role in the investigation of patients with hypoglycemia, subtype classification of diabetes mellitus, insulin resistance, and impaired beta cell function. However, even slight hemolysis can negatively affect insulin measurement due to RBC insulin-degrading enzyme (IDE). Here, we derived and validated an individualized correction equation in an attempt to eliminate the effects of hemolysis on insulin measurement. The effects of hemolysis on insulin measurement were studied by adding lysed self-RBCs to serum. A correction equation was derived, accounting for both percentage and exposure time of hemolysis. The performance of this individualized correction was evaluated in intentionally hemolyzed samples. Insulin concentration decreased with increasing percentage and exposure time of hemolysis. Based on the effects of hemolysis on insulin measurement of 17 donors (baseline insulin concentrations ranged from 156 to 2119 pmol/L), the individualized hemolysis correction equation was derived: INScorr = INSmeas/(0.705lgHbplasma/Hbserum - 0.001Time - 0.612). This equation can revert insulin concentrations of the intentionally hemolyzed samples to values that were statistically not different from the corresponding insulin baseline concentrations (p = 0.1564). Hemolysis could lead to a negative interference on insulin measurement; by individualized hemolysis correction equation for insulin measurement, we can correct and report reliable serum insulin results for a wide range of degrees of sample hemolysis. This correction would increase diagnostic accuracy, reduce inappropriate therapeutic decisions, and improve patient satisfaction with care.

  5. Use of two-part regression calibration model to correct for measurement error in episodically consumed foods in a single-replicate study design: EPIC case study.

    Directory of Open Access Journals (Sweden)

    George O Agogo

    Full Text Available In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference measurements are required. Short-term reference measurements for foods that are not consumed daily contain excess zeroes that pose challenges in the calibration model. We adapted two-part regression calibration model, initially developed for multiple replicates of reference measurements per individual to a single-replicate setting. We showed how to handle excess zero reference measurements by two-step modeling approach, how to explore heteroscedasticity in the consumed amount with variance-mean graph, how to explore nonlinearity with the generalized additive modeling (GAM and the empirical logit approaches, and how to select covariates in the calibration model. The performance of two-part calibration model was compared with the one-part counterpart. We used vegetable intake and mortality data from European Prospective Investigation on Cancer and Nutrition (EPIC study. In the EPIC, reference measurements were taken with 24-hour recalls. For each of the three vegetable subgroups assessed separately, correcting for error with an appropriately specified two-part calibration model resulted in about three fold increase in the strength of association with all-cause mortality, as measured by the log hazard ratio. Further found is that the standard way of including covariates in the calibration model can lead to over fitting the two-part calibration model. Moreover, the extent of adjusting for error is influenced by the number and forms of covariates in the calibration model. For episodically consumed foods, we advise researchers to pay special attention to response distribution, nonlinearity, and covariate inclusion in specifying the calibration model.

  6. Errors and Correction of Precipitation Measurements in China

    Institute of Scientific and Technical Information of China (English)

    REN Zhihua; LI Mingqin

    2007-01-01

    In order to discover the range of various errors in Chinese precipitation measurements and seek a correction method, 30 precipitation evaluation stations were set up countrywide before 1993. All the stations are reference stations in China. To seek a correction method for wind-induced error, a precipitation correction instrument called the "horizontal precipitation gauge" was devised beforehand. Field intercomparison observations regarding 29,000 precipitation events have been conducted using one pit gauge, two elevated operational gauges and one horizontal gauge at the above 30 stations. The range of precipitation measurement errors in China is obtained by analysis of intercomparison measurement results. The distribution of random errors and systematic errors in precipitation measurements are studied in this paper.A correction method, especially for wind-induced errors, is developed. The results prove that a correlation of power function exists between the precipitation amount caught by the horizontal gauge and the absolute difference of observations implemented by the operational gauge and pit gauge. The correlation coefficient is 0.99. For operational observations, precipitation correction can be carried out only by parallel observation with a horizontal precipitation gauge. The precipitation accuracy after correction approaches that of the pit gauge. The correction method developed is simple and feasible.

  7. Optics measurements and corrections at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Bai M.; Aronson, J.; Blaskiewicz, M.; Luo, Y.; Robert-Demolaize, G.; White, S.

    2012-05-20

    The further improvement of RHIC luminosity performance requires more precise understanding of the RHIC modeling. Hence, it is necessary to minimize the beta-beat, deviation of measured beta function from the calculated beta functions based on an model. The correction of betabeat also opens up the possibility of exploring operating RHIC polarized protons at a working point near integer, a prefered choice for both luminosity as well as beam polarization. The segment-by-segment technique for reducing beta-beat demonstrated in the LHC operation for reducing the beta-beat was first tested in RHIC during its polarized proton operation in 2011. It was then fully implemented during the RHIC polarized proton operation in 2012. This paper reports the commissioning results. Future plan is also presented.

  8. Phase 1 RCRA Facility Investigation & Corrective Measures Study Work Plan for Single Shell Tank (SST) Waste Management Areas

    Energy Technology Data Exchange (ETDEWEB)

    MCCARTHY, M.M.

    1999-08-01

    This document is the master work plan for the Resource Conservation and Recovery Act of 1976 (RCRA) Corrective Action Program (RCAP) for single-shell tank (SST) farms at the US. Department of Energy's (DOE'S) Hanford Site. The DOE Office of River Protection (ORP) initiated the RCAP to address the impacts of past and potential future tank waste releases to the environment. This work plan defines RCAP activities for the four SST waste management areas (WMAs) at which releases have contaminated groundwater. Recognizing the potential need for future RCAP activities beyond those specified in this master work plan, DOE has designated the currently planned activities as ''Phase 1.'' If a second phase of activities is needed for the WMAs addressed in Phase 1, or if releases are detected at other SST WMAs, this master work plan will be updated accordingly.

  9. QT measurement and heart rate correction during hypoglycemia

    DEFF Research Database (Denmark)

    Christensen, Toke Folke; Randløv, Jette; Christensen, Leif Engmann;

    2010-01-01

    Introduction. Several studies show that hypoglycemia causes QT interval prolongation. The aim of this study was to investigate the effect of QT measurement methodology, heart rate correction, and insulin types during hypoglycemia. Methods. Ten adult subjects with type 1 diabetes had hypoglycemia...... induced by intravenous injection of two insulin types in a cross-over design. QT measurements were done using the slope-intersect (SI) and manual annotation (MA) methods. Heart rate correction was done using Bazett's (QTcB) and Fridericia's (QTcF) formulas. Results. The SI method showed significant...... a significant impact on the prolongation of QT during hypoglycemia. Heart rate correction may also influence the QT during hypoglycemia while the type of insulin is insignificant. Prolongation of QTc in this study did not reach pathologic values suggesting that QTc prolongation cannot fully explain the dead...

  10. Pixelized measurement of {sup 99m}Tc-HDP micro particles formed in gamma correction phantom pinhole scan: A reference study

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joo Young; Yoon, Do Kyun; Chung, Yong An [Catholic University of Korea, College of Medicine, Seoul (Korea, Republic of); Cheon, Gi Jeong; Lee, Yun Sang; Ha, Seunggyun [Radiopharmaceutical Science Laboratory, Dept. of Nuclear MedicineSeoul National University, College of Medicine, Seoul (Korea, Republic of); Bahk, Yong Whee [Dept. of Nuclear Medicine, Sung Ae General Hospital, Seoul (Korea, Republic of)

    2016-09-15

    Currently, traumatic bone diseases are diagnosed by assessing the micro {sup 99m}Tc-hydroxymethylene diphosphonate (HDP) uptake in injured trabeculae with ongoing osteoneogenesis demonstrated by gamma correction pinhole scan (GCPS). However, the mathematic size quantification of micro-uptake is not yet available. We designed and performed this phantom-based study to set up an in-vitro model of the mathematical calculation of micro-uptake by the pixelized measurement. The micro {sup 99m}Tc-HDP deposits used in this study were spontaneously formed both in a large standard flood and small house-made dish phantoms. The processing was as follows: first, phantoms were flooded with distilled water and {sup 99m}Tc-HDP was therein injected to induce micro {sup 99m}Tc-HDP deposition; second, the deposits were scanned using parallel-hole and pinhole collimator to generally survey {sup 99m}Tc-HDP deposition pattern; and third, the scans underwent gamma correction (GC) to discern individual deposits for size measurement. In original naïve scans, tracer distribution was simply nebulous in appearance and, hence, could not be measured. Impressively, however, GCPS could discern individual micro deposits so that they were calculated by pixelized measurement. Phantoms naturally formed micro {sup 99m}Tc-HDP deposits that are analogous to {sup 99m}Tc-HDP uptake on in-vivo bone scan. The smallest one we measured was 0.414 mm. Flooded phantoms and therein injected {sup 99m}Tc-HDP form nebulous micro {sup 99m}Tc-HDP deposits that are rendered discernible by GCPB and precisely calculable using pixelized measurement. This method can be used for precise quantitative and qualitative diagnosis of bone and joint diseases at the trabecular level.

  11. Radiative corrections in nucleon time-like form factors measurements

    Energy Technology Data Exchange (ETDEWEB)

    Van de Wiele, Jacques [Universite de Paris-Sud, Institut de Physique Nucleaire, Orsay Cedex (France); Ong, Saro [Universite de Paris-Sud, Institut de Physique Nucleaire, Orsay Cedex (France); Universite de Picardie Jules Verne, Amiens (France)

    2013-02-15

    The completely general radiative corrections to lowest order, including the final- and initial-state radiations, are studied in proton-antiproton annihilation into an electron-positron pair. Numerical estimates have been made in a realistic configuration of the PANDA detector at FAIR for the proton time-like form factors measurements. (orig.)

  12. Interface corrective force measurements in Boston brace treatment.

    Science.gov (United States)

    van den Hout, J A A M; van Rhijn, L W; van den Munckhof, R J H; van Ooy, A

    2002-08-01

    Brace application has been reported to be effective in treating idiopathic adolescent scoliosis. The exact working mechanism of a thoracolumbo spinal orthosis is a result of different mechanisms and is not completely understood. One of the supposed working mechanisms is a direct compressive force working through the brace upon the body and thereby correcting the scoliotic deformity, achieving optimal fit of the individual orthosis. In this study we measured these direct forces exerted by the pads in a Boston brace in 16 patients with idiopathic adolescent scoliosis, using the electronic PEDAR measuring device (Novel, Munich, Germany). This is designed as an in-shoe measuring system consisting of two shoe insoles (size 8 1/2), wired to a computer, recording static and dynamic pressure distribution under the plantar surface of the foot. After positioning the inserts between the lumbar and thoracic pads and the body, we measured the forces acting upon the body in eight different postures. In all positions the mean corrective force through the lumbar brace pad was larger than the mean corrective force over the thoracic brace pad. Some changes in body posture resulted in statistically significant alterations in the exerted forces. There was no significant correlation between the magnitude of the compressive force over the lumbar and thoracic brace-pad and the degree of correction of the major curve. Comparing the corrective forces in a relatively new (6 months) brace, there was no statistically relevant difference, although the corrective force was slightly larger in the new braces. We think that the use of this pressure measurement device is practicable and of value for studies of the working mechanism of brace treatment, and in the future it might be of help in achieving optimal fit of the individual orthosis.

  13. Working session 4: Preventative and corrective measures

    Energy Technology Data Exchange (ETDEWEB)

    Clark, R. [Golder Federal Services Inc., Redmond, WA (United States); Slama, G. [Framatome, Paris (France)

    1997-02-01

    The Preventive and Corrective Measures working session included 13 members from France, Germany, Japan, Spain, Slovenia, and the United States. Attendee experience included regulators, utilities, three steam generator vendors, consultants and researchers. Discussions centered on four principal topics: (1) alternate materials, (2) mechanical mitigation, (3) maintenance, and (4) water chemistry. New or replacement steam generators and original equipment steam generators were separately addressed. Four papers were presented to the session, to provide information and stimulate various discussion topics. Topics discussed and issues raised during the several meeting sessions are provided below, followed by summary conclusions and recommendations on which the group was able to reach a majority consensus. The working session was composed of individuals with diverse experience and varied areas of specialized expertise. The somewhat broad range of topics addressed by the group at times saw discussion participation by only a few individuals. As in any technical meeting where all are allowed the opportunity to speak their mind, straying from an Individual topic was not unusual. Where useful, these stray topics are also presented below within the context In which they occurred. The main categories of discussion were: minimize sludge; new steam generators; maintenance; mechanical mitigation; water chemistry.

  14. Studies on absorption coefficients of dual-energy γ-rays and measuring error correction for multiphase fraction determination

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this article, principle and mathematical method of determining the phase fractions of multiphase flows by using a dual-energy γ-ray system have been described. The dual-energy γ-ray device is composed of radioactive isotopes of 241Am and 137Cs with γ-ray energies of 59.5 and 662 keV, respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The modified arithmetic is beneficial to removing the extra Compton scattering from the measured value. The result shows that the dual-energy γ-ray technique can be used in three-phase flow with average accuracy greater than 95%, which enables us to determine phase fractions almost independent of the flow regime. Improvement has been achieved on measurement accuracy of phase fractions.

  15. Self-attenuation artifacts and correction factors of light element measurements by X-ray analysis: Implication for mineral dust composition studies

    Science.gov (United States)

    Formenti, P.; Nava, S.; Prati, P.; Chevaillier, S.; Klaver, A.; Lafon, S.; Mazzei, F.; Calzolai, G.; Chiari, M.

    2010-01-01

    On a global scale, mineral dust is one of the major components of atmospheric aerosols and has important effects on the radiative budget of the atmosphere and thus on climate forcing. An accurate measurement of the concentration of crustal elements, namely Na, Mg, Al, Si, K, Ca, Ti, and Fe, is mandatory for the study of desert aerosols. The concentration of light elements, when measured by X-ray emission techniques such as X-ray fluorescence (XRF) and particle-induced X-ray emission (PIXE), can be underestimated owing to self-absorption of the emitted soft X-rays inside aerosol particles. In this work, we analyzed dust samples collected in field campaigns and samples produced in the laboratory using dust of known composition. Measurements have been conducted with PIXE and energy-dispersive XRF (ED-XRF), together with an attenuation-free technique such as particle-induced gamma-ray emission (PIGE) and attenuation corrected wavelength-dispersive XRF (WD-XRF) by internal standard calibration. We focus on the determination of Al and present results of a PIXE versus PIGE intercomparison. Aluminum concentration was measured with both techniques in dust samples collected by aircraft sampling over western Africa during winter 2006 and summer 2007. An underestimation of the Al concentration determined by PIXE was observed (up to 40%), and it was compared with the results of a simple calculation using basic physics and the size distribution of the collected aerosol. Similar attenuation was observed for Mg, Al, and Si in the laboratory samples analyzed by ED-XRF and WD-XRF. In order to use concentration ratios involving light elements as tracers of the region of emission of the sampled dust, these artifacts (i.e., underestimation of the concentration of light elements) induced by self-attenuation should be properly considered and corrected.

  16. Correction of the second-order degree of coherence measurement

    Institute of Scientific and Technical Information of China (English)

    Congcong Li; Xiangdong Chen; Shen Li; Fangwen Sun

    2016-01-01

    The measurement of the second-order degree of coherence [g(2)(τ)] is one of the important methods used to study the dynamical evolution of photon-matter interaction systems.Here,we use a nitrogen-vacancy center in a diamond to compare the measurement of g(2)(τ) with two methods.One is the prototype measurement process with a tunable delay.The other is a start-stop process based on the time-to-amplitude conversion (TAC) and multichannel analyzer (MCA) system,which is usually applied to achieve efficient measurements.The divergence in the measurement results is observed when the delay time is comparable with the mean interval time between two neighboring detected photons.Moreover,a correction function is presented to correct the results from the TAC-MCA system to the genuine g(2)(τ).Such a correction method will provide a way to study the dynamics in photonic systems for quantum information techniques.

  17. PET measurements of cerebral metabolism corrected for CSF contributions

    Energy Technology Data Exchange (ETDEWEB)

    Chawluk, J.; Alavi, A.; Dann, R.; Kushner, M.J.; Hurtig, H.; Zimmerman, R.A.; Reivich, M.

    1984-01-01

    Thirty-three subjects have been studied with PET and anatomic imaging (proton-NMR and/or CT) in order to determine the effect of cerebral atrophy on calculations of metabolic rates. Subgroups of neurologic disease investigated include stroke, brain tumor, epilepsy, psychosis, and dementia. Anatomic images were digitized through a Vidicon camera and analyzed volumetrically. Relative areas for ventricles, sulci, and brain tissue were calculated. Preliminary analysis suggests that ventricular volumes as determined by NMR and CT are similar, while sulcal volumes are larger on NMR scans. Metabolic rates (18F-FDG) were calculated before and after correction for CSF spaces, with initial focus upon dementia and normal aging. Correction for atrophy led to a greater increase (%) in global metabolic rates in demented individuals (18.2 +- 5.3) compared to elderly controls (8.3 +- 3.0,p < .05). A trend towards significantly lower glucose metabolism in demented subjects before CSF correction was not seen following correction for atrophy. These data suggest that volumetric analysis of NMR images may more accurately reflect the degree of cerebral atrophy, since NMR does not suffer from beam hardening artifact due to bone-parenchyma juxtapositions. Furthermore, appropriate correction for CSF spaces should be employed if current resolution PET scanners are to accurately measure residual brain tissue metabolism in various pathological states.

  18. Improvements for Optics Measurement and Corrections software

    CERN Document Server

    Bach, T

    2013-01-01

    This note presents the improvements for the OMC software during a 14 month technical student internship at CERN. The goal of the work was to improve existing software in terms of maintainability, features and performance. Significant improvements in stability, speed and overall development process were reached. The main software, a Java GUI at the LHC CCC, run for months without noteworthy problems. The overall running time of the software chain used for optics corrections was reduced from nearly half an hour to around two minutes. This was the result of analysing and improving several involved programs and algorithms.

  19. Use of Two-Part Regression Calibration Model to Correct for Measurement Error in Episodically Consumed Foods in a Single-Replicate Study Design: EPIC Case Study

    NARCIS (Netherlands)

    Agogo, G.O.; Voet, van der H.; Veer, van 't P.; Ferrari, P.; Leenders, M.; Muller, D.C.; Sánchez-Cantalejo, E.; Bamia, C.; Braaten, T.; Knüppel, S.; Johansson, I.; Eeuwijk, van F.A.; Boshuizen, H.C.

    2014-01-01

    In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference m

  20. Use of Two-Part Regression Calibration Model to Correct for Measurement Error in Episodically Consumed Foods in a Single-Replicate Study Design : EPIC Case Study

    NARCIS (Netherlands)

    Agogo, George O; der Voet, Hilko van; Veer, Pieter Van't; Ferrari, Pietro; Leenders, Max; Muller, David C; Sánchez-Cantalejo, Emilio; Bamia, Christina; Braaten, Tonje; Knüppel, Sven; Johansson, Ingegerd; van Eeuwijk, Fred A; Boshuizen, Hendriek

    2014-01-01

    In epidemiologic studies, measurement error in dietary variables often attenuates association between dietary intake and disease occurrence. To adjust for the attenuation caused by error in dietary intake, regression calibration is commonly used. To apply regression calibration, unbiased reference m

  1. Corrective measures evaluation report for Tijeras Arroyo groundwater.

    Energy Technology Data Exchange (ETDEWEB)

    Witt, Johnathan L (North Wind, Inc., Idaho Falls, ID); Orr, Brennon R. (North Wind, Inc., Idaho Falls, ID); Dettmers, Dana L. (North Wind, Inc., Idaho Falls, ID); Hall, Kevin A. (North Wind, Inc., Idaho Falls, ID); Howard, M. Hope (North Wind, Inc., Idaho Falls, ID)

    2005-08-01

    This Corrective Measures Evaluation report was prepared as directed by a Compliance Order on Consent issued by the New Mexico Environment Department to document the process of selecting the preferred remedial alternative for Tijeras Arroyo Groundwater. Supporting information includes background concerning the site conditions and potential receptors and an overview of work performed during the Corrective Measures Evaluation. The evaluation of remedial alternatives included identifying and describing four remedial alternatives, an overview of the evaluation criteria and approach, comparing remedial alternatives to the criteria, and selecting the preferred remedial alternative. As a result of the Corrective Measures Evaluation, monitored natural attenuation of the contaminants of concern (trichloroethene and nitrate) is the preferred remedial alternative for implementation as the corrective measure for Tijeras Arroyo Groundwater. Design criteria to meet cleanup goals and objectives and the corrective measures implementation schedule for the preferred remedial alternative are also presented.

  2. Monte Carlo simulated corrections for beam commissioning measurements with circular and MLC shaped fields on the CyberKnife M6 System: a study including diode, microchamber, point scintillator, and synthetic microdiamond detectors

    Science.gov (United States)

    Francescon, P.; Kilby, W.; Noll, J. M.; Masi, L.; Satariano, N.; Russo, S.

    2017-02-01

    Monte Carlo simulation was used to calculate correction factors for output factor (OF), percentage depth-dose (PDD), and off-axis ratio (OAR) measurements with the CyberKnife M6 System. These include the first such data for the InCise MLC. Simulated detectors include diodes, air-filled microchambers, a synthetic microdiamond detector, and point scintillator. Individual perturbation factors were also evaluated. OF corrections show similar trends to previous studies. With a 5 mm fixed collimator the diode correction to convert a measured OF to the corresponding point dose ratio varies between  -6.1% and  -3.5% for the diode models evaluated, while in a 7.6 mm  ×  7.7 mm MLC field these are  -4.5% to  -1.8%. The corresponding microchamber corrections are  +9.9% to  +10.7% and  +3.5% to  +4.0%. The microdiamond corrections have a maximum of  -1.4% for the 7.5 mm and 10 mm collimators. The scintillator corrections are  15%, reducing to    d max were  stopping power perturbations. The microdiamond OAR corrections were  <3% outside the beam. This paper provides OF corrections that can be used for commissioning new CyberKnife M6 Systems and retrospectively checking estimated corrections used previously. We recommend the PDD and OAR corrections are used to guide detector selection and inform the evaluation of results rather than to explicitly correct measurements.

  3. Aperiodicity Correction for Rotor Tip Vortex Measurements

    Science.gov (United States)

    2011-05-01

    Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Wire Anemometry (HWA), see, e.g., Refs. 1–5. Further- more, for such point measurement techniques...components along x- and y-axis, ms−1 uc, vc Vortex convection velocities, ms−1 Vθ Swirl velocity, ms−1 x, y, z Measurement coordinate system, mm xc, yc...techniques such LDV and Hot - 1 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is

  4. One Moon, many measurements 2: Photometric corrections

    Science.gov (United States)

    Besse, S.; Yokota, Y.; Boardman, J.; Green, R.; Haruyama, J.; Isaacson, P.; Mall, U.; Matsunaga, T.; Ohtake, M.; Pieters, C.; Staid, M.; Sunshine, J.; Yamamoto, S.

    2013-09-01

    Observations of the lunar surface within the past 10 years have been made with various lunar remote sensing instruments, the Moon Mineralogy Mapper (M3) onboard the Chandrayaan-1 mission, the Spectral Profiler (SP), the Multiband Imager (MI), the Terrain Camera (TC) onboard the SELENE mission, and the ground based USGS Robotic Lunar Observatory (ROLO) for some of them. The lunar phase functions derived from these datasets, which are used in the photometric modeling to correct for the various illumination conditions of the data, are compared to assess their differences and similarity in order to improve interpretations of lunar surface spectra. The phase functions are found to be similar across various phase angles except in the 0-20° range. Differences across the 0-20° range likely result from two different inputs in the photometric modeling of the M3 and SP data: (1) M3 has larger emission angles due to the characteristics of the instrument and the attitude of the spacecraft, and (2) M3 viewing geometry was derived from the local topography whereas SP used a spherical Moon (no topography). The combination of these two different inputs affects the phase function at small phase angles where shadows play a more substantial role, with spatial resolution differences between M3 and SP being another possible source for the differences. SP data are found to be redder (i.e., steeper slope with increasing wavelengths) than MI, M3 and ROLO. Finally, the M3 overall reflectance is also found to be lower than that the other instruments (i.e., MI, SP, and ROLO), generally at least 10% darker than MI. These differences can be observed at local scales in specific examples at hundreds of meters resolutions. At regional and global scales, the same differences are found, which demonstrates the overall stability of the various datasets. The observations from M3, TC, SP and MI are very stable and agree well; however caution should be used when making interpretations based on the

  5. Improved Error Thresholds for Measurement-Free Error Correction

    Science.gov (United States)

    Crow, Daniel; Joynt, Robert; Saffman, M.

    2016-09-01

    Motivated by limitations and capabilities of neutral atom qubits, we examine whether measurement-free error correction can produce practical error thresholds. We show that this can be achieved by extracting redundant syndrome information, giving our procedure extra fault tolerance and eliminating the need for ancilla verification. The procedure is particularly favorable when multiqubit gates are available for the correction step. Simulations of the bit-flip, Bacon-Shor, and Steane codes indicate that coherent error correction can produce threshold error rates that are on the order of 10-3 to 10-4—comparable with or better than measurement-based values, and much better than previous results for other coherent error correction schemes. This indicates that coherent error correction is worthy of serious consideration for achieving protected logical qubits.

  6. Are We Correctly Measuring the Star Formation in Galaxies?

    Science.gov (United States)

    McQuinn, K. B. W.; Skillman, E. D.; Dolphin, A. E.; Mitchell, N. P.

    2016-06-01

    Integrating our knowledge of star formation (SF) traced by observations at different wavelengths is essential for correctly interpreting and comparing SF activity in a variety of systems and environments. This study compares extinction corrected integrated ultraviolet (UV) emission from resolved galaxies with color-magnitude diagram (CMD) based star formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The data sets are from the panchromatic Starburst Irregular Dwarf Survey and include deep legacy GALEX UV imaging, Hubble Space Telescope optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near-UV fluxes predicted from the CMD-based SFRs—using four different models—agree with the measured, extinction corrected, integrated near-UV fluxes from GALEX images, but the far-UV (FUV) predicted fluxes do not. Furthermore, we find a systematic deviation between the SFRs based on integrated FUV luminosities and existing scaling relations, and the SFRs based on the resolved stellar populations. This offset is not driven by different SF timescales, variations in SFRs, UV attenuation, nor stochastic effects. This first comparison between CMD-based SFRs and an integrated FUV emission SFR indicator suggests that the most likely cause of the discrepancy is the theoretical FUV-SFR calibration from stellar evolutionary libraries and/or stellar atmospheric models. We present an empirical calibration of the FUV-based SFR relation for dwarf galaxies, with uncertainties, which is 53% larger than previous relations.

  7. Measuring perceptual centers using the phase correction response.

    Science.gov (United States)

    Villing, Rudi C; Repp, Bruno H; Ward, Tomas E; Timoney, Joseph M

    2011-07-01

    The perceptual center (P-center) is fundamental to the timing of heterogeneous event sequences, including music and speech. Unfortunately, there is currently no comprehensive and reliable model of P-centers in acoustic events, so P-centers must instead be measured empirically. This study reviews existing measurement methods and evaluates two methods in detail-the rhythm adjustment method and a new method based on the phase correction response (PCR) in a synchronous tapping task. The two methods yielded consistent P-center estimates and showed no evidence of P-center context dependence. The PCR method appears promising because it is accurate and efficient and does not require explicit perceptual judgments. As a secondary result, the magnitude of the PCR is shown to vary systematically with the onset complexity of speech sounds, which presumably reflects the perceived clarity of a sound's P-center.

  8. Are We Correctly Measuring Star-Formation Rates?

    Science.gov (United States)

    McQuinn, Kristen B.; Skillman, Evan D.; Dolphin, Andrew E.; Mitchell, Noah P.

    2017-01-01

    Integrating our knowledge of star formation (SF) traced by observations at different wavelengths is essential for correctly interpreting and comparing SF activity in a variety of systems and environments. This study compares extinction-corrected, integrated ultraviolet (UV) emission from resolved galaxies with color-magnitude diagram (CMD) based star-formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The data sets are from the panchromatic Starburst Irregular Dwarf Survey (STARBIRDS) and include deep legacy GALEX UV imaging, Hubble Space Telescope optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near-UV fluxes predicted from the CMD-based SFRs—using four different models—agree with the measured, extinction corrected, integrated near-UV fluxes from GALEX images, but the far-UV (FUV) predicted fluxes do not. Furthermore, we find a systematic deviation between the SFRs based on integrated FUV luminosities and existing scaling relations, and the SFRs based on the resolved stellar populations. This offset is not driven by different SF timescales, variations in SFRs, UV attenuation, nor stochastic effects. This first comparison between CMD-based SFRs and an integrated FUV emission SFR indicator suggests that the most likely cause of the discrepancy is the theoretical FUV-SFR calibration from stellar evolutionary libraries and/or stellar atmospheric models. We present an empirical calibration of the FUV-based SFR relation for dwarf galaxies, with uncertainties, which is ˜53% larger than previous relations. These results have signficant implications for measuring FUV-based SFRs of high-redshift galaxies.

  9. Pre-correction of projected gratings for surface profile measurement

    Science.gov (United States)

    Sun, Cuiru; Lu, Hua

    2008-11-01

    This paper discusses errors caused by unequal grating pitch in applying the phase-shifted digital grating projection method for object profile measurement. To address the related issues, a new scheme is proposed to effectively improve the uniformity of the projected grating pitch across the object surface with no additional hardware cost. The improvement is mainly realized via a grating pitch pre-correction algorithm assisted by Digital Speckle/Image Correlation (DSC/DIC). DIC is utilized to accurately determine the surface grating pitch variation when an originally equal-pitched grating pattern is slant projected to the surface. With the actual pitch distribution function determined, a pre-corrected grating with unequal pitch is generated and projected, and the iterative algorithm reaches a constant pitched surface grating. The mapping relationship between the object surface profile (or out-of-plane displacement) and the fringe phase changes is obtained with a real-time subtraction based calibration. A quality guide phase unwrapping method is also adopted in the fringe processing. Finally, a virtual reference phase plane obtained by a 3-point plane fitting algorithm is subtracted to eliminate the carrier phase. The study shows that a simple optical system implemented with the mentioned improvements remarkably increase the accuracy and the efficiency of the measurement.

  10. Measurement and Correction of the Fermilab Booster Optics with LOCO*

    CERN Document Server

    Tan, C Y; Triplett, A K; McAteer, M

    2015-01-01

    The optics of the original Booster lacked the ability for full optics correction and it was not until 2009 when new optics corrector packages were installed between gradient magnets that this ability became available. The optics correction method that is chosen is called LOCO (Linear Optics from Closed Orbits) that measures the orbit response from every beam position monitor (BPM) in the ring from every kick of every dipole corrector. The large data set collected allows LOCO to not only calculate the quadrupole and skew quadrupole currents that both reduces beta beatings and corrects coupling, it also finds the dipole kicker strengths, BPM calibrations and their tilts by minimizing the difference between the measured and ideal orbit response of the beam. The corrected optics have been loaded into Booster and it is currently being tested to be eventually used in normal operations.

  11. Corrective measures evaluation report for technical area-v groundwater.

    Energy Technology Data Exchange (ETDEWEB)

    Witt, Johnathan L (North Wind, Inc., Idaho Falls, ID); Orr, Brennon R. (North Wind, Inc., Idaho Falls, ID); Dettmers, Dana L. (North Wind, Inc., Idaho Falls, ID); Hall, Kevin A. (North Wind, Inc., Idaho Falls, ID); Howard, Hope (North Wind, Inc., Idaho Falls, ID)

    2005-07-01

    This Corrective Measures Evaluation Report was prepared as directed by the Compliance Order on Consent issued by the New Mexico Environment Department to document the process of selecting the preferred remedial alternative for contaminated groundwater at Technical Area V. Supporting information includes background information about the site conditions and potential receptors and an overview of work performed during the Corrective Measures Evaluation. Evaluation of remedial alternatives included identification and description of four remedial alternatives, an overview of the evaluation criteria and approach, qualitative and quantitative evaluation of remedial alternatives, and selection of the preferred remedial alternative. As a result of the Corrective Measures Evaluation, it was determined that monitored natural attenuation of all contaminants of concern (trichloroethene, tetrachloroethene, and nitrate) was the preferred remedial alternative for implementation as the corrective measure to remediate contaminated groundwater at Technical Area V of Sandia National Laboratories/New Mexico. Finally, design criteria to meet cleanup goals and objectives and the corrective measures implementation schedule for the preferred remedial alternative are presented.

  12. Correction

    DEFF Research Database (Denmark)

    Pinkevych, Mykola; Cromer, Deborah; Tolstrup, Martin

    2016-01-01

    [This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.].......[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.]....

  13. Corrective measures evaluation work plan : Tijeras Arroyo Groundwater : revision 0.

    Energy Technology Data Exchange (ETDEWEB)

    Wymore, Ryan A.; Collins, Sue S.; Skelly, Michael Francis; Koelsch, Michael C.

    2004-12-01

    This document, which is prepared as directed by the Compliance Order on Consent (COOC) issued by the New Mexico Environment Department, outlines a process to evaluate remedial alternatives to identify a corrective measure for the Sandia National Laboratories Tijeras Arroyo Groundwater (TAG). The COOC provides guidance for implementation of a Corrective Measures Evaluation (CME) for TAG. This Work Plan documents an initial screening of remedial technologies and presents a list of possible remedial alternatives for those technologies that passed the screening. This Work Plan outlines the methods for evaluating these remedial alternatives and describes possible site-specific evaluation activities necessary to estimate remedy effectiveness and cost. These methods will be reported in the CME Report. This Work Plan outlines the CME Report, including key components and a description of the corrective measures process.

  14. Coupling measurement and correction at the SSRF storage ring

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Brightness is an important parameter for 3rd generation light source. Correcting the emittance coupling is a realistic way to increase brightness without any additional equipment in a machine under operation. The main sources of emittance coupling are betatron coupling and vertical dispersion. At the SSRF storage ring, tune split and LOCO are used to measure the respective betatron and emittance coupling. Both of these sources can be corrected by skew quadrupoles. By measuring the skew quadrupole-coupling response matrix, betatron coupling can be changed from 0.014% to 2%. But the vertical dispersion changes at the same time. LOCO can find the suitable setting to correct simultaneously the betatron coupling and vertical dispersion. The emittance coupling can be reduced to 0.17% by this method. More simulations show the potential for smaller emittance coupling if more skew quadrupoles are employed.

  15. Correcting for response lag in unsteady pressure measurements in water

    Energy Technology Data Exchange (ETDEWEB)

    Conger, R.N. [John Graham Associates, Seattle, WA (United States); Ramaprian, B.R. [Washington State Univ., Pullman, WA (United States). Dept. of Mechanical and Materials Engineering

    1993-12-01

    There is not much information available on the use of diaphragm-type pressure transducers for the measurements of unsteady pressures in liquids. A procedure for measuring the dynamic response of a pressure transducer in such applications and correcting for its inadequate response is discussed in this report. An example of the successful use of this method to determine unsteady surface pressures on a pitching airfoil in a water channel is presented.

  16. AC dipole based optics measurement and correction at RHIC

    CERN Document Server

    Shen, X; Bai, M; White, S; Robert-Domolaize, G; Luo, Y; Marusic, A; Tomas, R

    2013-01-01

    Independent component analysis (ICA) was applied to the AC dipole based optics measurement at RHIC to extract beta functions as well as phase advances at each BPM. Existence of excessive beta-beat was observed in both rings of RHIC at polarized proton store energy. A unique global optics correction scheme was then developed and tested successfully during the RHIC polarized proton run in 2013. The feasibility of using horizontal closed orbit bump at sextupole for arc beta-beat correction was also demonstrated.

  17. Research on UV radiation measurements and correction methods

    Science.gov (United States)

    Huang, Bo; Dai, Cai-hong; Yu, Jai-lin; Wu, Zhi-feng; Ouyang, Hui-quan

    2011-06-01

    The widely use of UV radiation led to the demand for improved understanding of the properties of instrumentation used to measure this radiation. The UV radiometers are mainly influenced by the factors as operating conditions, environmental conditions and the UV sources to be calibrated and measured. In addition, large errors can occur due to out-of-band, non-linear, and non-ideal cosine or spatial response of the UV meters. Through a new designed measurement system for cosine response property, we do some measuring experiments to 21 kinds of UV radiometers and calculate the relative deviation of each UV meters. The cosine errors are existed universally. It is recommended that keeping the UV source closing to a point source and perpendicular to UV detector when it is measured is very important. We also design and fulfill an experimental system to reflect the measuring errors of UV radiometers when measuring sources and calibrated sources are mismatched. The results show that if the measurement is of a broadband source, it is wise to unify the measuring and calibrated source or the two sources have similar spectral distribution. If that is not possible, we can calculate the spectral mismatch correction factor and spectral matching characteristic factor to correct the measuring data. All the works above are to let the users in appropriate usage of UV Radiometers in a standardized and comparable way and make the measurement quantities more accurate.

  18. Correcting systematic errors in high-sensitivity deuteron polarization measurements

    Energy Technology Data Exchange (ETDEWEB)

    Brantjes, N.P.M. [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Dzordzhadze, V. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Gebel, R. [Institut fuer Kernphysik, Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Gonnella, F. [Physica Department of ' Tor Vergata' University, Rome (Italy); INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Gray, F.E. [Regis University, Denver, CO 80221 (United States); Hoek, D.J. van der [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Imig, A. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Kruithof, W.L. [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Lazarus, D.M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Lehrach, A.; Lorentz, B. [Institut fuer Kernphysik, Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Messi, R. [Physica Department of ' Tor Vergata' University, Rome (Italy); INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Moricciani, D. [INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Morse, W.M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Noid, G.A. [Indiana University Cyclotron Facility, Bloomington, IN 47408 (United States); and others

    2012-02-01

    This paper reports deuteron vector and tensor beam polarization measurements taken to investigate the systematic variations due to geometric beam misalignments and high data rates. The experiments used the In-Beam Polarimeter at the KVI-Groningen and the EDDA detector at the Cooler Synchrotron COSY at Juelich. By measuring with very high statistical precision, the contributions that are second-order in the systematic errors become apparent. By calibrating the sensitivity of the polarimeter to such errors, it becomes possible to obtain information from the raw count rate values on the size of the errors and to use this information to correct the polarization measurements. During the experiment, it was possible to demonstrate that corrections were satisfactory at the level of 10{sup -5} for deliberately large errors. This may facilitate the real time observation of vector polarization changes smaller than 10{sup -6} in a search for an electric dipole moment using a storage ring.

  19. Velocity Correction and Measurement Uncertainty Analysis of Light Screen Velocity Measuring Method

    Institute of Scientific and Technical Information of China (English)

    ZHENG Bin; ZUO Zhao-lu; HOU Wen

    2012-01-01

    Light screen velocity measuring method with unique advantages has been widely used in the velocity measurement of various moving bodies.For large air resistance and friction force which the big moving bodies are subjected to during the light screen velocity measuring,the principle of velocity correction was proposed and a velocity correction equation was derived.A light screen velocity measuring method was used to measure the velocity of big moving bodies which have complex velocity attenuation,and the better results were gained in practical tests.The measuring uncertainty after the velocity correction was calculated.

  20. Re-investigating the isotopic fractionation corrections in radiocarbon measurements

    Science.gov (United States)

    Fahrni, S.; Santos, G. M.; Xu, X.; Southon, J. R.

    2012-12-01

    By convention (Stuiver and Polach, 1977), 14C data has to be corrected for any isotopic fractionation occurring in nature, during the sample preparation or the measurement. The fractionation factor b = 2.0 used to correct the 14C/12C ratio for shifts in the 13C/12C ratio has been proposed in 1954 (Craig, 1954) and has been applied ever since. While theoretical considerations have suggested moderate deviations of b from 2.0, some measurements have suggested larger differences (e.g. Saliege and Fontes, 1984). With the increasing precision of radiocarbon measurements, potential deviations of b from 2.0 become more significant, since these could cause shifts of several decades in some radiocarbon dates (Southon, 2011). It is therefore of great interest for the radiocarbon community to re-evaluate the fractionation corrections. We present approaches for the experimental determination of b and discuss results and their effects on radiocarbon dating. Stuiver M., Polach H.A., 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355-63. Saliege J.F., Fontes J.C., 1984. Essai de détermination expérimentale du fractionnement des isotopes 13C et 14C du carbone au cours de processus naturels. International Journal of Applied Radiation and Isotopes 35(1):55-62. Craig H., 1954. Carbon 13 in plants and the relationships between carbon 13 and carbon 14 in nature. Journal of Geology 62(2):115-49. Southon J., 2011. Are the Fractionation Corrections Correct: Are the Isotopic Shifts for 14C/12C Ratios in Physical Processes and Chemical Reactions Really Twice Those for 13C/12C? Radiocarbon 53(4):691-704.

  1. Improved correction of VIPERS angular selection effects in clustering measurements

    Science.gov (United States)

    Pezzotta, A.; Granett, B. R.; Bel, J.; Guzzo, L.; de la Torre, S.; Aff004

    2016-10-01

    Clustering estimates in galaxy redshift surveys need to account and correct for the way targets are selected from the general population, as to avoid biasing the measured values of cosmological parameters. The VIMOS Public Extragalactic Redshift Survey (VIPERS) is no exception to this, involving slit collisions and masking effects. Pushed by the increasing precision of the measurements, e.g. of the growth rate f, we have been re-assessing these effects in detail. We present here an improved correction for the two-point correlation function, capable to recover the amplitude of the monopole of the two-point correlation function ξ(r) above 1 h-1 Mpc to better than 2.

  2. Measuring inappropriate responses of adolescents to problematic social situations in secure institutional and correctional youth care: a validation study of the TOPS-A

    NARCIS (Netherlands)

    G.H.P. van der Helm; W. Matthys; X. Moonen; N. Giesen; E.S. van der Heide; G.J.J.M. Stams

    2013-01-01

    The present study examined the construct, concurrent and divergent validity, and reliability of the "Taxonomy of Problematic Social Situations-Adolescent self-report version" (TOPS-A) in a sample of 128 adolescents placed in Dutch secure juvenile facilities. The instrument measures inappropriate res

  3. Correction method for line extraction in vision measurement.

    Directory of Open Access Journals (Sweden)

    Mingwei Shao

    Full Text Available Over-exposure and perspective distortion are two of the main factors underlying inaccurate feature extraction. First, based on Steger's method, we propose a method for correcting curvilinear structures (lines extracted from over-exposed images. A new line model based on the Gaussian line profile is developed, and its description in the scale space is provided. The line position is analytically determined by the zero crossing of its first-order derivative, and the bias due to convolution with the normal Gaussian kernel function is eliminated on the basis of the related description. The model considers over-exposure features and is capable of detecting the line position in an over-exposed image. Simulations and experiments show that the proposed method is not significantly affected by the exposure level and is suitable for correcting lines extracted from an over-exposed image. In our experiments, the corrected result is found to be more precise than the uncorrected result by around 45.5%. Second, we analyze perspective distortion, which is inevitable during line extraction owing to the projective camera model. The perspective distortion can be rectified on the basis of the bias introduced as a function of related parameters. The properties of the proposed model and its application to vision measurement are discussed. In practice, the proposed model can be adopted to correct line extraction according to specific requirements by employing suitable parameters.

  4. Differential correction method applied to measurement of the FAST reflector

    Science.gov (United States)

    Li, Xin-Yi; Zhu, Li-Chun; Hu, Jin-Wen; Li, Zhi-Heng

    2016-08-01

    The Five-hundred-meter Aperture Spherical radio Telescope (FAST) adopts an active deformable main reflector which is composed of 4450 triangular panels. During an observation, the illuminated area of the reflector is deformed into a 300-m diameter paraboloid and directed toward a source. To achieve accurate control of the reflector shape, positions of 2226 nodes distributed around the entire reflector must be measured with sufficient precision within a limited time, which is a challenging task because of the large scale. Measurement of the FAST reflector makes use of stations and node targets. However, in this case the effect of the atmosphere on measurement accuracy is a significant issue. This paper investigates a differential correction method for total stations measurement of the FAST reflector. A multi-benchmark differential correction method, including a scheme for benchmark selection and weight assignment, is proposed. On-site evaluation experiments show there is an improvement of 70%-80% in measurement accuracy compared with the uncorrected measurement, verifying the effectiveness of the proposed method.

  5. Atmospheric Corrections for Altimetry Studies over Inland Water

    Directory of Open Access Journals (Sweden)

    M. Joana Fernandes

    2014-05-01

    Full Text Available Originally designed for applications over the ocean, satellite altimetry has been proven to be a useful tool for hydrologic studies. Altimeter products, mainly conceived for oceanographic studies, often fail to provide atmospheric corrections suitable for inland water studies. The focus of this paper is the analysis of the main issues related with the atmospheric corrections that need to be applied to the altimeter range to get precise water level heights. Using the corrections provided on the Radar Altimeter Database System, the main errors present in the dry and wet tropospheric corrections and in the ionospheric correction of the various satellites are reported. It has been shown that the model-based tropospheric corrections are not modeled properly and in a consistent way in the various altimetric products. While over the ocean, the dry tropospheric correction (DTC is one of the most precise range corrections, in some of the present altimeter products, it is the correction with the largest errors over continental water regions, causing large biases of several decimeters, and along-track interpolation errors up to several centimeters, both with small temporal variations. The wet tropospheric correction (WTC from the on-board microwave radiometers is hampered by the contamination on the radiometer measurements of the surrounding lands, making it usable only in the central parts of large lakes. In addition, the WTC from atmospheric models may also have large errors when it is provided at sea level instead of surface height. These errors cannot be corrected by the user, since no accurate expression exists for the height variation of the WTC. Alternative and accurate corrections can be computed from in situ data, e.g., DTC from surface pressure at barometric stations and WTC from Global Navigation Satellite System permanent stations. The latter approach is particularly favorable for small lakes and reservoirs, where GNSS-derived WTC at a single

  6. Correction factors for gravimetric measurement of peritumoural oedema in man.

    Science.gov (United States)

    Bell, B A; Smith, M A; Tocher, J L; Miller, J D

    1987-01-01

    The water content of samples of normal and oedematous brain in lobectomy specimens from 16 patients with cerebral tumours has been measured by gravimetry and by wet and dry weighing. Uncorrected gravimetry underestimated the water content of oedematous peritumoural cortex by a mean of 1.17%, and of oedematous peritumoural white matter by a mean of 2.52%. Gravimetric correction equations calculated theoretically and from an animal model of serum infusion white matter oedema overestimate peritumoural white matter oedema in man, and empirical gravimetric error correction factors for oedematous peritumoural human white matter and cortex have therefore been derived. These enable gravimetry to be used to accurately determine peritumoural oedema in man.

  7. Correct use of repeated measures analysis of variance.

    Science.gov (United States)

    Park, Eunsik; Cho, Meehye; Ki, Chang-Seok

    2009-02-01

    In biomedical research, researchers frequently use statistical procedures such as the t-test, standard analysis of variance (ANOVA), or the repeated measures ANOVA to compare means between the groups of interest. There are frequently some misuses in applying these procedures since the conditions of the experiments or statistical assumptions necessary to apply these procedures are not fully taken into consideration. In this paper, we demonstrate the correct use of repeated measures ANOVA to prevent or minimize ethical or scientific problems due to its misuse. We also describe the appropriate use of multiple comparison tests for follow-up analysis in repeated measures ANOVA. Finally, we demonstrate the use of repeated measures ANOVA by using real data and the statistical software package SPSS (SPSS Inc., USA).

  8. Does an instrumented treadmill correctly measure the ground reaction forces?

    Directory of Open Access Journals (Sweden)

    Patrick A. Willems

    2013-11-01

    Since the 1990s, treadmills have been equipped with multi-axis force transducers to measure the three components of the ground reaction forces during walking and running. These measurements are correctly performed if the whole treadmill (including the motor is mounted on the transducers. In this case, the acceleration of the treadmill centre of mass relative to the reference frame of the laboratory is nil. The external forces exerted on one side of the treadmill are thus equal in magnitude and opposite in direction to the external forces exerted on the other side. However, uncertainty exists about the accuracy of these measures: due to friction between the belt and the tread-surface, due to the motor pulling the belt, some believe that it is not possible to correctly measure the horizontal components of the forces exerted by the feet on the belt. Here, we propose a simple model of an instrumented treadmill and we demonstrate (1 that the forces exerted by the subject moving on the upper part of the treadmill are accurately transmitted to the transducers placed under it and (2 that all internal forces – including friction – between the parts of the treadmill are cancelling each other.

  9. Grayscale imbalance correction in real-time phase measuring profilometry

    Science.gov (United States)

    Zhu, Lin; Cao, Yiping; He, Dawu; Chen, Cheng

    2016-10-01

    Grayscale imbalance correction in real-time phase measuring profilometry (RPMP) is proposed. In the RPMP, the sufficient information is obtained to reconstruct the 3D shape of the measured object in one over twenty-four of a second. Only one color fringe pattern whose R, G and B channels are coded as three sinusoidal phase-shifting gratings with an equivalent shifting phase of 2π/3 is sent to a flash memory on a specialized digital light projector (SDLP). And then the SDLP projects the fringe patterns in R, G and B channels sequentially onto the measured object in one over seventy-two of a second and meanwhile a monochrome CCD camera captures the corresponding deformed patterns synchronously with the SDLP. Because the deformed patterns from three color channels are captured at different time, the color crosstalk is avoided completely. But due to the monochrome CCD camera's different spectral sensitivity to R, G and B tricolor, there will be grayscale imbalance among these deformed patterns captured at R, G and B channels respectively which may result in increasing measuring errors or even failing to reconstruct the 3D shape. So a new grayscale imbalance correction method based on least square method is developed. The experimental results verify the feasibility of the proposed method.

  10. Optics measurement and correction for the Relativistic Heavy Ion Collider

    Science.gov (United States)

    Shen, Xiaozhe

    The quality of beam optics is of great importance for the performance of a high energy accelerator like the Relativistic Heavy Ion Collider (RHIC). The turn-by-turn (TBT) beam position monitor (BPM) data can be used to derive beam optics. However, the accuracy of the derived beam optics is often limited by the performance and imperfections of instruments as well as measurement methods and conditions. Therefore, a robust and model-independent data analysis method is highly desired to extract noise-free information from TBT BPM data. As a robust signal-processing technique, an independent component analysis (ICA) algorithm called second order blind identification (SOBI) has been proven to be particularly efficient in extracting physical beam signals from TBT BPM data even in the presence of instrument's noise and error. We applied the SOBI ICA algorithm to RHIC during the 2013 polarized proton operation to extract accurate linear optics from TBT BPM data of AC dipole driven coherent beam oscillation. From the same data, a first systematic estimation of RHIC BPM noise performance was also obtained by the SOBI ICA algorithm, and showed a good agreement with the RHIC BPM configurations. Based on the accurate linear optics measurement, a beta-beat response matrix correction method and a scheme of using horizontal closed orbit bumps at sextupoles for arc beta-beat correction were successfully applied to reach a record-low beam optics error at RHIC. This thesis presents principles of the SOBI ICA algorithm and theory as well as experimental results of optics measurement and correction at RHIC.

  11. Method for measuring multiple scattering corrections between liquid scintillators

    Science.gov (United States)

    Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; Wurtz, R. E.

    2016-07-01

    A time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.

  12. Measuring and correcting wobble in large-scale transmission radiography

    CERN Document Server

    Rogers, Thomas W; Morton, Edward J; Griffin, Lewis D

    2016-01-01

    Large-scale transmission radiography scanners are used to image vehicles and cargo containers. Acquired images are inspected for threats by a human operator or a computer algorithm. To make accurate detections, it is important that image values are precise. However, due to the scale of such systems, they can be mechanically unstable, causing the imaging array to wobble during a scan. This leads to an effective loss of precision in the captured image. We consider the measurement of wobble and amelioration of the consequent loss of image precision. Following our previous work, we use Beam Position Detectors (BPDs) to measure the cross-sectional profile of the X-ray beam, allowing for estimation, and thus correction of wobble. We propose: (i) a model of image formation with a wobbling detector array; (ii) a method of wobble correction derived from this model; (iii) methods for calibrating sensor sensitivities and relative offsets; (iv) a Random Regression Forest based method for instantaneous estimation of detec...

  13. Automated fat measurement and segmentation with intensity inhomogeneity correction

    Science.gov (United States)

    Sussman, Daniel L.; Yao, Jianhua; Summers, Ronald M.

    2010-03-01

    Adipose tissue (AT) content, especially visceral AT (VAT), is an important indicator for risks of many disorders, including heart disease and diabetes. Fat measurement by traditional means is often inaccurate and cannot separate subcutaneous and visceral fat. MRI offers a medium to obtain accurate measurements and segmentation between subcutaneous and visceral fat. We present an approach to automatically label the voxels associated with adipose tissue and segment them between subcutaneous and visceral. Our method uses non-parametric non-uniform intensity normalization (N3) to correct for image artifacts and inhomogeneities, fuzzy c-means to cluster AT regions and active contour models to separate SAT and VAT. Our algorithm has four stages: body masking, preprocessing, SAT and VAT separation, and tissue classification and quantification. The method was validated against a manual method performed by two observers, which used thresholds and manual contours to separate SAT and VAT. We measured 25 patients, 22 of which were included in the final analysis and the other three had too much artifact for automated processing. For SAT and total AT, differences between manual and automatic measurements were comparable to manual inter-observer differences. VAT measurements showed more variance in the automated method, likely due to inaccurate contours.

  14. Evaluation of a novel correction procedure to remove electrode impedance effects from broadband SIP measurements

    Science.gov (United States)

    Huisman, Johan Alexander; Zimmermann, Egon; Esser, Odilia; Haegel, Franz-Hubert; Treichel, Andrea; Vereecken, Harry

    2016-12-01

    Broadband spectral induced polarization (SIP) measurements of the complex electrical resistivity can be affected by the contact impedance of the potential electrodes above 100 Hz. In this study, we present a correction procedure to remove electrode impedance effects from SIP measurements to improve the accuracy of broadband complex electrical resistivity measurements. The first step in this correction procedure is to estimate the electrode impedance using a measurement with reversed current and potential electrodes. In a second step, this estimated electrode impedance is used to correct SIP measurements based on a simplified electrical model of the SIP measurement system. We evaluated this new correction procedure using SIP measurements on water because of the well-defined dielectric properties. It was found that the difference between the corrected and expected phase of the complex electrical resistivity of water was below 0.1 mrad at 1 kHz for a wide range of electrode impedances. In addition, SIP measurements on a saturated unconsolidated sediment sample with two types of potential electrodes showed that the measured phase of the electrical resistivity was very similar (difference resistivity was improved for frequencies up to 1 kHz, but errors remained for higher frequencies due to the approximate nature of the electrode impedance estimates and some remaining unknown parasitic capacitances that led to current leakage. It was concluded that the proposed correction procedure for SIP measurements improved the accuracy of the phase measurements by an order of magnitude in the kHz frequency range. Further improvement of this accuracy requires a method to accurately estimate parasitic capacitances in situ.

  15. Correction

    CERN Document Server

    2002-01-01

    Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.

  16. Effect of refractive correction on ocular optical quality measurement using double-pass system

    Institute of Scientific and Technical Information of China (English)

    WAN Xiu-hua; CAI Xiao-gu; QIAO Li-ya; ZHANG Ye; TAN Jia-xuan; Jhanji Vishal; WANG Ning-li

    2013-01-01

    Background Optical Quality Analysis System Ⅱ (OQAS,Visiometrics,Terrassa,Spain) that uses double-pass (DP) technique is the only commercially available device that allows objective measurement of ocular retinal image quality.This study aimed to evaluate the impact of spectacle lenses on the ocular optical quality parameters and the validity of the optometer within OQAS.Methods Seventy eyes of healthy volunteers were enrolled.Optical quality measurements were performed using OQAS with an artificial pupil diameter of 4.0 mm.Three consecutive measurements were obtained from spectacle correction corresponding to subjective refraction and from the OQAS built-in optometer separately.The modulation transfer function cutoff frequency,the Strehl ratio,the width of the point spread function (PSF) at 10% of its maximal height (PSF10),and the width of the PSF at 50% of its maximal height (PSF50) were analyzed.Results There was no significant difference in any of the parameters between the spectacle correction and the optometer correction (all P >0.05,paired t-test).A good agreement was found between both the methods and a good intraobserver repeatability in both the correction methods.Difference in best focus between two methods was the only parameter associated significantly with optical quality parameter differences.Best focus difference,built-in optometer correction with or without external cylindrical lens,and age were associated significantly with PSF10 difference.No linear correlation between refractive status and optical quality measurement difference was observed.A hyperopic bias (best focus difference of (0.50±0.44) D) and a relatively better optical quality using spectacle correction in high myopia group were found.Conclusions OQAS based on DP system is a clinically reliable instrument.In patients with high myopia,measurements using built-in optometer correction should be considered and interpreted with caution.

  17. EPU correction scheme study at the CLS

    Energy Technology Data Exchange (ETDEWEB)

    Bertwistle, Drew, E-mail: drew.bertwistle@lightsource.ca; Baribeau, C.; Dallin, L.; Chen, S.; Vogt, J.; Wurtz, W. [Canadian Light Source Inc. 44 Innovation Boulevard, Saskatoon, SK S7N 2V3 (Canada)

    2016-07-27

    The Canadian Light Source (CLS) Quantum Materials Spectroscopy Center (QMSC) beamline will employ a novel double period (55 mm, 180 mm) elliptically polarizing undulator (EPU) to produce photons of arbitrary polarization in the soft X-ray regime. The long period and high field of the 180 mm period EPU will have a strong dynamic focusing effect on the storage ring electron beam. We have considered two partial correction schemes, a 4 m long planar array of BESSY-II style current strips, and soft iron L-shims. In this paper we briefly consider the implementation of these correction schemes.

  18. Correction

    CERN Multimedia

    2002-01-01

    The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.   The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.

  19. Correction

    Directory of Open Access Journals (Sweden)

    2012-01-01

    Full Text Available Regarding Gorelik, G., & Shackelford, T.K. (2011. Human sexual conflict from molecules to culture. Evolutionary Psychology, 9, 564–587: The authors wish to correct an omission in citation to the existing literature. In the final paragraph on p. 570, we neglected to cite Burch and Gallup (2006 [Burch, R. L., & Gallup, G. G., Jr. (2006. The psychobiology of human semen. In S. M. Platek & T. K. Shackelford (Eds., Female infidelity and paternal uncertainty (pp. 141–172. New York: Cambridge University Press.]. Burch and Gallup (2006 reviewed the relevant literature on FSH and LH discussed in this paragraph, and should have been cited accordingly. In addition, Burch and Gallup (2006 should have been cited as the originators of the hypothesis regarding the role of FSH and LH in the semen of rapists. The authors apologize for this oversight.

  20. Correction

    Directory of Open Access Journals (Sweden)

    2014-01-01

    Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].

  1. Written Corrective Feedback in Second Language Acquisition and Writing Studies

    Science.gov (United States)

    Ferris, Dana R.

    2012-01-01

    Written corrective feedback, referred to hereafter as "written CF" and also known as "grammar correction" or "error correction", has been a controversial topic in second language studies over the past fifteen years. Inspired by John Truscott's thought-provoking 1996 essay in "Language Learning", many different researchers have undertaken new…

  2. Corrections of rotation of the Galaxy to measured P of pulsars

    Institute of Scientific and Technical Information of China (English)

    容建湘; 萧耐园; 陆埮

    1999-01-01

    The P of pulsars provides important information for studying their physical processes. In an all-round way the effect of the Galactic rotation on the measured P of pulsars is studied. It is shown that among 706 pulsars discovered so far there are 16 pulsars whose measured values of P have been affected by the Galactic rotation. So, it is necessary to make the corresponding corrections for those pulsars.

  3. Correction.

    Science.gov (United States)

    2015-10-01

    In the article by Quintavalle et al (Quintavalle C, Anselmi CV, De Micco F, Roscigno G, Visconti G, Golia B, Focaccio A, Ricciardelli B, Perna E, Papa L, Donnarumma E, Condorelli G, Briguori C. Neutrophil gelatinase–associated lipocalin and contrast-induced acute kidney injury. Circ Cardiovasc Interv. 2015;8:e002673. DOI: 10.1161/CIRCINTERVENTIONS.115.002673.), which published online September 2, 2015, and appears in the September 2015 issue of the journal, a correction was needed. On page 1, the institutional affiliation for Elvira Donnarumma, PhD, “SDN Foundation,” has been changed to read, “IRCCS SDN, Naples, Italy.” The institutional affiliation for Laura Papa, PhD, “Institute for Endocrinology and Experimental Oncology, National Research Council, Naples, Italy,” has been changed to read, “Institute of Genetics and Biomedical Research, Milan Unit, Milan, Italy” and “Humanitas Research Hospital, Rozzano, Italy.” The authors regret this error.

  4. 78 FR 48075 - Western Pacific Fisheries; 2013 Annual Catch Limits and Accountability Measures; Correcting...

    Science.gov (United States)

    2013-08-07

    ... Catch Limits and Accountability Measures; Correcting Amendment AGENCY: National Marine Fisheries Service...- season accountability measures upon attainment of the annual catch limit. Accordingly, in the...

  5. Consideration of kaolinite interference correction for quartz measurements in coal mine dust.

    Science.gov (United States)

    Lee, Taekhee; Chisholm, William P; Kashon, Michael; Key-Schwartz, Rosa J; Harper, Martin

    2013-01-01

    Kaolinite interferes with the infrared analysis of quartz. Improper correction can cause over- or underestimation of silica concentration. The standard sampling method for quartz in coal mine dust is size selective, and, since infrared spectrometry is sensitive to particle size, it is intuitively better to use the same size fractions for quantification of quartz and kaolinite. Standard infrared spectrometric methods for quartz measurement in coal mine dust correct interference from the kaolinite, but they do not specify a particle size for the material used for correction. This study compares calibration curves using as-received and respirable size fractions of nine different examples of kaolinite in the different correction methods from the National Institute for Occupational Safety and Health Manual of Analytical Methods (NMAM) 7603 and the Mine Safety and Health Administration (MSHA) P-7. Four kaolinites showed significant differences between calibration curves with as-received and respirable size fractions for NMAM 7603 and seven for MSHA P-7. The quartz mass measured in 48 samples spiked with respirable fraction silica and kaolinite ranged between 0.28 and 23% (NMAM 7603) and 0.18 and 26% (MSHA P-7) of the expected applied mass when the kaolinite interference was corrected with respirable size fraction kaolinite. This is termed "deviation," not bias, because the applied mass is also subject to unknown variance. Generally, the deviations in the spiked samples are larger when corrected with the as-received size fraction of kaolinite than with the respirable size fraction. Results indicate that if a kaolinite correction with reference material of respirable size fraction is applied in current standard methods for quartz measurement in coal mine dust, the quartz result would be somewhat closer to the true exposure, although the actual mass difference would be small. Most kinds of kaolinite can be used for laboratory calibration, but preferably, the size fraction

  6. 靶场光学测量数据大气折射修正研究%Study on Correction of Atmospheric Refraction Error of Optical Measurement Data in Navy Range

    Institute of Scientific and Technical Information of China (English)

    周慧; 赵满庆

    2012-01-01

    Atmospheric refraction error is one of the primary systems errors. How to correct the atmospheric refraction error of optical measurement data in navy rage was studied in this paper. First, the model of atmospheric refraction error was founded. In succession, the computing process was introduced in detail At last, the data of negative elevation, low elevation and high elevation were used to correct the atmospheric refraction error of optical measurement data to test the method. The results verify that the method is scientific and reasonable. The method can not only correct the atmospheric refraction error of optical measurement data in navy range but also improve the data precision and reliability.%研究外弹道数据测量优化问题,在外弹道测量数据处理中,由于大气折射误差,引起系统误差.当目标相对于测量装备为低负仰角时,大气折射给俯仰角带来的测量误差最大可达3'~4',造成测量数据不准确.为了对靶场的光学测量数据进行有效的大气折射修正,提出了建立俯仰角折射修正模型,接着详细论述了折光修正计算过程,最后以负仰角、低仰角和大仰角的目标为例,采用改进方法进行大气折射修正仿真,检验修正结果.结果表明,新方法科学、合理,具有工程应用价值.靶场光学测量数据大气折射修正方法很好地修正了由于大气折射带来的高度误差,提高了数据处理精度和数据可靠性.

  7. Estimation and relevance of depth correction in paediatric renal studies

    Energy Technology Data Exchange (ETDEWEB)

    Lythgoe, M.F.; Gradwell, M.J.; Evans, K.; Gordon, I. [Department of Radiology, Great Ormond Street Hospital for Children NHS Trust, London (United Kingdom)

    1998-02-01

    Measurement of absolute renal function by gamma camera techniques requires knowledge of kidney depth to correct for soft tissue attenuation, there is debate about the need to take depth into account when only relative renal function is estimated. The aim of this study was to derive a formula for renal depth in children and to assess the importance of depth correction when relative renal function is assessed with dimercaptosuccinic acid (DMSA) on the gamma camera. In this study, kidney depths were derived from measurements on abdominal computerised tomography (CT) images in 57 children in the supine position with two normally located kidneys. Using best-subset regression analysis, one formula for both left and right kidney depth (KD, cm) was developed based on the easily measured parameters of height (H, cm) and body weight (W, kg). The inclusion of extra variables was found to significantly improve the model compared with a model using weight alone (P<0.005). A second group of 19 children who underwent technetium-99m DMSA scans, had differential function estimated from both anterior and posterior views and the geometric mean method. The mean difference in differential renal function calculated by the geometric mean method versus the posterior image was only 1.2%. In conclusion, we present a new formula for the estimation of paediatric kidney depth for the absolute quantitation of kidney uptake. Further, for normally located kidneys it appears unnecessary to use the geometric mean method or to correct for individual renal depth when calculating differential function. (orig.) With 2 figs., 1 tab., 22 refs.

  8. Estimation of correction coefficients for measured coal bed methane contents

    Institute of Scientific and Technical Information of China (English)

    Lei Bo; Fu Xuehai; Zhou Baoyan; Shen Jian; Zou Mingjun; Feng Qing

    2012-01-01

    Improving the accuracy and precision of coal bed methane (CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aerial weight method,and the well-point aerial weight method,were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data.The data from the Nos.3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards.The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method.The three methods provide similar results for the Nos.3 and 15 seams in that the correction factor is lower for the former seam.The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank.The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.

  9. [Correction method for infrared spectral emissivity measurement system based on integrating sphere reflectometer].

    Science.gov (United States)

    Zhang, Yu-Feng; Dai, Jing-Min; Zhang, Yu; Pan, Wei-Dong; Zhang, Lei

    2013-08-01

    In view of the influence of non-ideal reference standard on spectral emissivity measurement, by analyzing the principle of infrared emissivity measurement system based on integrating sphere reflectometer, a calibration method suitable for measuring spectral emissivity system using the reflection measurement was proposed. By fitting a spectral reflectance curve of the reference standard sample to the given reflectance data, the correction coefficient of measurement system was computed. Then the output voltage curve of reference standard sample was corrected by this coefficient. The system error caused by the imperfection of reference standard was eliminated. The correction method was applied to the spectral emissivity measurement system based on integrating sphere reflectometer. The results measured by the corrected system and the results measured by energy comparison measurement were compared to verify the feasibility and effectivity of this correction method in improving the accuracy of spectral emissivity measurement.

  10. False positive and false negative radon measurement results due to uncertainties in seasonal correction factors

    Energy Technology Data Exchange (ETDEWEB)

    Cliff, K.D.; Miles, J.C.H.; Naismith, S.P. [National Radiological Protection Board, Chilton (United Kingdom)

    1994-12-31

    Data from the UK national survey of radon in 2300 homes has been re-analysed to determine the uncertainty in seasonal correction factors applied to measurements of less than 1 year. The required correction factor for each six-month result was calculated from the known annual average for the appropriate home. The seasonal correction factors derived for each month were found to be approximately log-normally distributed, with an average geometric standard deviation of 1.36. Following this initial survey, radon measurements have been made in more than 80,000 homes in southwest England to determine whether they are above the UK radon Action Level of 2000 Bq.m{sup -3}. The measurements were carried out over three months in each case using etched track detectors in two locations in each home, and the results were corrected for the average seasonal variation found in the original UK study of radon in homes. Because of the uncertainty in the seasonal correction factors, households with between 130 and 300 Bq.m{sup -3} were advised to have a second three-month measurement in a different season before deciding whether or not to take remedial action. More than 7000 homes were remonitored for this purpose. The results are analysed to show the number of false positive and false negative results that would have been reported if advice had been based solely on the initial measurement. It is shown that the present scheme results in extremely small numbers of false positive and false negative results. (author).

  11. Nerve conduction studies in upper extremities: skin temperature corrections.

    Science.gov (United States)

    Halar, E M; DeLisa, J A; Soine, T L

    1983-09-01

    The relationship of skin to near nerve (NN) temperature and to nerve conduction velocity (NCV) and distal latency (DL) was studied in 34 normal adult subjects before and after cooling both upper extremities. Median and ulnar motor and sensory NCV, DL, and NN temperature were determined at ambient temperature (mean X skin temp = 33 C) and after cooling, at approximately 26, 28, and 30 C of forearm skin temperature. Skin temperatures on the volar side of the forearm, wrist, palm, and fingers and NN temperature at the forearm, midpalm, and thenar or hypothenar eminence were compared with respective NCV and DL. Results showed a significant linear correlation between skin temperature and NN temperature at corresponding sites (r2 range, 0.4-0.84; p less than 0.005). Furthermore, both skin and NN temperatures correlated significantly with respective NCV and DL. Midline wrist skin temperature showed the best correlation to NCV and DL. Median motor and sensory NCV were altered 1.5 and 1.4m/sec/C degree and their DL 0.2 msec/C degree of wrist skin temperature change, respectively. Ulnar motor and sensory NCV were changed 2.1 and 1.6m/sec/C degree respectively, and 0.2 msec/C degree wrist temperature for motor and sensory DL. Average ambient skin temperature at the wrist (33 C) was used as a standard skin temperature in the temperature correction formula: NCV or DL(temp corrected) = CF(Tst degree - Tm degree) + obtained NCV or DL, where Tst = 33 C for wrist, Tm = the measured skin temperature, and CF = correction factor of tested nerve. Use of temperature correction formula for NCV and DL is suggested in patients with changed wrist skin temperature outside 29.6-36.4C temperature range.

  12. A Classroom Research Study on Oral Error Correction

    Science.gov (United States)

    Coskun, Abdullah

    2010-01-01

    This study has the main objective to present the findings of a small-scale classroom research carried out to collect data about my spoken error correction behaviors by means of self-observation. With this study, I aimed to analyze how and which spoken errors I corrected during a specific activity in a beginner's class. I used Lyster and Ranta's…

  13. An improved method for correction of air temperature measured using different radiation shields

    Science.gov (United States)

    Cheng, Xinghong; Su, Debin; Li, Deping; Chen, Lu; Xu, Wenjing; Yang, Meilin; Li, Yongcheng; Yue, Zhizhong; Wang, Zijing

    2014-11-01

    The variation of air temperature measurement errors using two different radiation shields (DTR502B Vaisala, Finland, and HYTFZ01, Huayun Tongda Satcom, China) was studied. Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012. Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers (FRP) Stevenson screen. In most cases, the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield. The measured errors changed sharply at sunrise and sunset, and reached maxima at noon. Their diurnal variation characteristics were, naturally, related to changes in solar radiation. The relationships between the record errors, global radiation, and wind speed were nonlinear. An improved correction method was proposed based on the approach described by Nakamura and Mahrt (2005) (NM05), in which the impact of the solar zenith angle (SZA) on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively. Measurement errors were reduced significantly after correction by either method for both shields. The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3% and 40.4% higher than those using the NM05 method, respectively.

  14. $\\beta$-particle energy-summing correction for $\\beta$-delayed proton emission measurements

    CERN Document Server

    Meisel, Z; Crawford, H L; Cyburt, R H; Grinyer, G F; Langer, C; Montes, F; Schatz, H; Smith, K

    2016-01-01

    A common approach to studying $\\beta$-delayed proton emission is to measure the energy of the emitted proton and corresponding nuclear recoil in a double-sided silicon-strip detector (DSSD) after implanting the $\\beta$-delayed proton emitting ($\\beta$p) nucleus. However, in order to extract the proton-decay energy, the measured energy must be corrected for the additional energy implanted in the DSSD by the $\\beta$-particle emitted from the $\\beta$p nucleus, an effect referred to here as $\\beta$-summing. We present an approach to determine an accurate correction for $\\beta$-summing. Our method relies on the determination of the mean implantation depth of the $\\beta$p nucleus within the DSSD by analyzing the shape of the total (proton + recoil + $\\beta$) decay energy distribution shape. We validate this approach with other mean implantation depth measurement techniques that take advantage of energy deposition within DSSDs upstream and downstream of the implantation DSSD.

  15. Information-theoretic approach to quantum error correction and reversible measurement

    CERN Document Server

    Nielsen, M A; Schumacher, B; Barnum, H N; Caves, Carlton M.; Schumacher, Benjamin; Barnum, Howard

    1997-01-01

    Quantum operations provide a general description of the state changes allowed by quantum mechanics. The reversal of quantum operations is important for quantum error-correcting codes, teleportation, and reversing quantum measurements. We derive information-theoretic conditions and equivalent algebraic conditions that are necessary and sufficient for a general quantum operation to be reversible. We analyze the thermodynamic cost of error correction and show that error correction can be regarded as a kind of ``Maxwell demon,'' for which there is an entropy cost associated with information obtained from measurements performed during error correction. A prescription for thermodynamically efficient error correction is given.

  16. Accurate NIRS measurement of muscle oxygenation by correcting the influence of a subcutaneous fat layer

    Science.gov (United States)

    Yamamoto, Katsuyuki; Niwayama, Masatsugu; Lin, Ling; Shiga, Toshikazu; Kudo, Nobuki; Takahashi, Makoto

    1998-01-01

    Although the inhomogeneity of tissue structure affects the sensitivity of tissue oxygenation measurement by reflectance near-infrared spectroscopy, few analyses of this effect have been reported. In this study, the influence of a subcutaneous fat layer on muscle oxygenation measurement was investigated by Monte Carlo simulation and experimental studies. In the experiments, measurement sensitivity was examined by measuring the falling rate of oxygenation in occlusion tests on the forearm using a tissue oxygen monitor. The fat layer thickness was measured by ultrasonography. Results of the simulation and occlusion tests clearly showed that the presence of a fat layer greatly decreases the measurement sensitivity and increases the light intensity at the detector. The correction factors of sensitivity were obtained from this relationship and were successfully validated by experiments on 12 subjects whose fat layer thickness ranged from 3.5 to 8 mm.

  17. Analytic PSF Correction for Gravitational Flexion Studies

    CERN Document Server

    Levinson, Rebecca Sobel

    2013-01-01

    Given a galaxy image, one cannot simply measure its flexion. An image's spin one and three shape properties, typically associated with F- and G-flexion, are actually complicated functions of the galaxy's intrinsic shape and the telescope's PSF, in addition to the lensing properties. The same is true for shear. In this work we create a completely analytic mapping from apparent measured galaxy flexions to gravitational flexions by (1) creating simple models for a lensed galaxy and for a PSF whose distortions are dominated by atmospheric smearing and optical aberrations, (2) convolving the two models, and (3) comparing the pre- and post-convolved flexion-like shape variations of the final image. For completeness, we do the same for shear. As expected, telescope astigmatism, coma, and trefoil can corrupt measurements of shear, F- flexion, and G-flexion, especially for small galaxies. We additionally find that PSF size dilutes the flexion signal more rapidly than the shear signal. Moreover, mixing between shears, ...

  18. Condenser Microphone Protective Grid Correction for High Frequency Measurements

    Science.gov (United States)

    Lee, Erik; Bennett, Reginald

    2010-01-01

    Use of a protective grid on small diameter microphones can prolong the lifetime of the unit, but the high frequency effects can complicate data interpretation. Analytical methods have been developed to correct for the grid effect at high frequencies. Specifically, the analysis pertains to quantifying the microphone protective grid response characteristics in the acoustic near field of a rocket plume noise source. A frequency response function computation using two microphones will be explained. Experimental and instrumentation setup details will be provided. The resulting frequency response function for a B&K 4944 condenser microphone protective grid will be presented, along with associated uncertainties

  19. Measurement error of self-reported physical activity levels in New York City: assessment and correction.

    Science.gov (United States)

    Lim, Sungwoo; Wyker, Brett; Bartley, Katherine; Eisenhower, Donna

    2015-05-01

    Because it is difficult to objectively measure population-level physical activity levels, self-reported measures have been used as a surveillance tool. However, little is known about their validity in populations living in dense urban areas. We aimed to assess the validity of self-reported physical activity data against accelerometer-based measurements among adults living in New York City and to apply a practical tool to adjust for measurement error in complex sample data using a regression calibration method. We used 2 components of data: 1) dual-frame random digit dialing telephone survey data from 3,806 adults in 2010-2011 and 2) accelerometer data from a subsample of 679 survey participants. Self-reported physical activity levels were measured using a version of the Global Physical Activity Questionnaire, whereas data on weekly moderate-equivalent minutes of activity were collected using accelerometers. Two self-reported health measures (obesity and diabetes) were included as outcomes. Participants with higher accelerometer values were more likely to underreport the actual levels. (Accelerometer values were considered to be the reference values.) After correcting for measurement errors, we found that associations between outcomes and physical activity levels were substantially deattenuated. Despite difficulties in accurately monitoring physical activity levels in dense urban areas using self-reported data, our findings show the importance of performing a well-designed validation study because it allows for understanding and correcting measurement errors.

  20. Intra-operative measurement of applied forces during anterior scoliosis correction.

    Science.gov (United States)

    Fairhurst, H; Little, J P; Adam, C J

    2016-12-01

    Spinal instrumentation and fusion for the treatment of scoliosis is primarily a mechanical intervention to correct the deformity and halt further progression. While implant-related complications remain a concern, little is known about the magnitudes of the forces applied to the spine during surgery, which may affect post-surgical outcomes. In this study, the compressive forces applied to each spinal segment during anterior instrumentation were measured in a series of patients with Adolescent Idiopathic Scoliosis. A force transducer was designed and retrofit to a routinely used surgical tool, and compressive forces applied to each segment during surgery were measured for 15 scoliosis patients. Cobb angle correction achieved by each force was measured on intra-operative fluoroscope images. Relative changes in orientation of the screw within the vertebra were also measured to detect intra-operative screw plough. Intra-operative forces were measured for a total of 95 spinal segments. The mean applied compressive force was 540N (SD 230N, range 88N-1019N). There was a clear trend for higher forces to be applied at segments toward the apex of the scoliosis. Fluoroscopic evidence of screw plough was detected at 10 segments (10.5%). The magnitude of forces applied during anterior scoliosis correction vary over a broad range. These forces do reach magnitudes capable of causing intra-operative vertebral body screw plough. Surgeons should be aware there is a risk for tissue overload during correction, however the clinical implications of intra-operative screw plough remain unclear. The dataset presented here is valuable for providing realistic input parameters for in silico surgical simulations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Improvement of surface planarity measurements by temperature correction and structural simulations

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Maximilian; Biebel, Otmar; Bortfeldt, Jonathan; Flierl, Bernhard; Hertenberger, Ralf; Loesel, Philipp; Mueller, Ralph [LMU Muenchen (Germany); Zibell, Andre [JMU Wuerzburg (Germany)

    2016-07-01

    Novel micro pattern gaseous detectors, like Micromegas, for particle physics experiments require precise flat active layers of 2-3 m{sup 2} in size. A construction procedure developed at LMU for 2 m{sup 2} sized Micromegas achieves surface planarities with a RMS below 30 μm. The measurements were performed using a laser distance sensor attached to a coordinate measurement machine. Studies were made to investigate the influence of temperature variations on these measurements. The temperature is monitored by several sensors. We present results containing corrections of the measurements in respect to temperature changes. In addition simulations with the FEM program ANSYS are compared to measured detector panel deformations introduced by forces, in order to study their effect on the surface planarity.

  2. Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

    Science.gov (United States)

    Pan, Xicai; Yang, Daqing; Li, Yanping; Barr, Alan; Helgason, Warren; Hayashi, Masaki; Marsh, Philip; Pomeroy, John; Janowicz, Richard J.

    2016-10-01

    This study assesses a filtering procedure on accumulating precipitation gauge measurements and quantifies the effects of bias corrections for wind-induced undercatch across four ecoclimatic regions in western Canada, including the permafrost regions of the subarctic, the Western Cordillera, the boreal forest, and the prairies. The bias corrections increased monthly precipitation by up to 163 % at windy sites with short vegetation and sometimes modified the seasonal precipitation regime, whereas the increases were less than 13 % at sites shielded by forest. On a yearly basis, the increase of total precipitation ranged from 8 to 20 mm (3-4 %) at sites shielded by vegetation and 60 to 384 mm (about 15-34 %) at open sites. In addition, the bias corrections altered the seasonal precipitation patterns at some windy sites with high snow percentage ( > 50 %). This study highlights the need for and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate-hydrology models.

  3. Study of tip loss corrections using CFD rotor computations

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær

    2014-01-01

    Tip loss correction is known to play an important role for engineering prediction of wind turbine performance. There are two different types of tip loss corrections: tip corrections on momentum theory and tip corrections on airfoil data. In this paper, we study the latter using detailed CFD...... computations for wind turbines with sharp tip. Using the technique of determination of angle of attack and the CFD results for a NordTank 500 kW rotor, airfoil data are extracted and a new tip loss function on airfoil data is derived. To validate, BEM computations with the new tip loss function are carried out...... and compared with CFD results for the NordTank 500 kW turbine and the NREL 5 MW turbine. Comparisons show that BEM with the new tip loss function can predict correctly the loading near the blade tip....

  4. Optics measurement and correction during acceleration with beta-squeeze in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    In the past, beam optics correction at RHIC has only taken place at injection and at final energy, with interpolation of corrections partially into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats that, if corrected, could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoiding the high-order multipole fields sampled by particles within the bunch. We recently demonstrated successful beam optics corrections during acceleration at RHIC. We verified conclusively the superior control of the beam realized via these corrections

  5. Botox injection as a temporary measure for correcting gummy smile

    Directory of Open Access Journals (Sweden)

    Anil Sargur Ramu

    2014-01-01

    Full Text Available The exposure of more than 3 mm of the gum during the smile is known as gingival or gummy smile (GS. Botulinum toxin (BT has been used since 1989 for cosmetic reasons to treat frown lines and since, then its use has been tried for various cosmetic procedures, the effects of which can last from 6 weeks to 8 months. BT has been tried as an initial and temporary option for treatment of GS cases due to the ease and safety of the applications. We hereby report a case of GS induced by orthodontic treatment for proclination correction by extracting upper and lower first premolars treated effectively by local administration of BT. Though the treatment effects lasts for 6 months to 1 year the cosmetic benefits are worth the treatment procedure.

  6. A terahertz study of taurine: Dispersion correction and mode couplings

    Science.gov (United States)

    Dai, Zelin; Xu, Xiangdong; Gu, Yu; Li, Xinrong; Wang, Fu; Lian, Yuxiang; Fan, Kai; Cheng, Xiaomeng; Chen, Zhegeng; Sun, Minghui; Jiang, Yadong; Yang, Chun; Xu, Jimmy

    2017-03-01

    The low-frequency characteristics of polycrystalline taurine were studied experimentally by terahertz (THz) absorption spectroscopy and theoretically by ab initio density-functional simulations. Full optimizations with semi-empirical dispersion correction were performed in spectral computations and vibrational mode assignments. For comparison, partial optimizations with pure density functional theory were conducted in parallel. Results indicate that adding long-range dispersion correction to the standard DFT better reproduces the measured THz spectra than the popular partial optimizations. The main origins of the observed absorption features were also identified. Moreover, a coupled-oscillators model was proposed to explain the experimental observation of the unusual spectral blue-shift with the increase of temperature. Such coupled-oscillators model not only provides insights into the temperature dynamics of non-bonded interactions but also offers an opportunity to better understand the physical mechanisms behind the unusual THz spectral behaviors in taurine. Particularly, the simulation approach and novel coupled-oscillators model presented in this work are applicable to analyze the THz spectra of other molecular systems.

  7. Possible use of psychological corrective measures for people with abnormal sexual preferences

    Directory of Open Access Journals (Sweden)

    Babina S.V.

    2015-08-01

    Full Text Available The paper studies the possibility of psychological corrective measures aimed at persons with abnormal sexual preferences. We reviewed domestic and foreign scientific publications described the treatment of sexual disorders and the basic directions of the therapy, and indicated its positive and negative aspects. We have studied progress notes and etiology of "personality disorders and behavior in adulthood" disease class, "disorders of sexual preference" disease subsection and analyzed the efficiency of the psychopharmacological treatment, cognitive-behavioral therapy, and psychotherapy for each violation of sexual preference. The most productive methods of therapeutic intervention are identified. This analysis allows making the most appropriate scheme of psychological correction and treatment for persons with abnormalities of sexual preference.

  8. Respiratory effort correction strategies to improve the reproducibility of lung expansion measurements

    Energy Technology Data Exchange (ETDEWEB)

    Du, Kaifang; Reinhardt, Joseph M. [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa 52242 (United States); Christensen, Gary E. [Department of Electrical and Computer Engineering, The University of Iowa, Iowa City, Iowa 52242 (United States); Ding, Kai [Department of Radiation Oncology, Johns Hopkins University, Baltimore, Maryland 21231 (United States); Bayouth, John E. [Department of Human Oncology, University of Wisconsin - Madison, Madison, Wisconsin 53792 (United States)

    2013-12-15

    Purpose: Four-dimensional computed tomography (4DCT) can be used to make measurements of pulmonary function longitudinally. The sensitivity of such measurements to identify change depends on measurement uncertainty. Previously, intrasubject reproducibility of Jacobian-based measures of lung tissue expansion was studied in two repeat prior-RT 4DCT human acquisitions. Difference in respiratory effort such as breathing amplitude and frequency may affect longitudinal function assessment. In this study, the authors present normalization schemes that correct ventilation images for variations in respiratory effort and assess the reproducibility improvement after effort correction.Methods: Repeat 4DCT image data acquired within a short time interval from 24 patients prior to radiation therapy (RT) were used for this analysis. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. In addition to computing the ventilation maps from end expiration to end inspiration, the authors investigated the effort normalization strategies using other intermediated inspiration phases upon the principles of equivalent tidal volume (ETV) and equivalent lung volume (ELV). Scatter plots and mean square error of the repeat ventilation maps and the Jacobian ratio map were generated for four conditions: no effort correction, global normalization, ETV, and ELV. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2 mm distance-to-agreement and 5% ventilation difference.Results: The pattern of regional pulmonary ventilation changes as lung volume changes. All effort correction strategies improved reproducibility when changes in respiratory effort were greater than 150 cc (p < 0.005 with regard to the gamma pass rate). Improvement of reproducibility was

  9. Geometric correction factor for transepithelial electrical resistance measurements in transwell and microfluidic cell cultures

    Science.gov (United States)

    Yeste, J.; Illa, X.; Gutiérrez, C.; Solé, M.; Guimerà, A.; Villa, R.

    2016-09-01

    Transepithelial electrical resistance (TEER) measurements are regularly used in in vitro models to quantitatively evaluate the cell barrier function. Although it would be expected that TEER values obtained with the same cell type and experimental setup were comparable, values reported in the literature show a large dispersion for unclear reasons. This work highlights a possible error in a widely used formula to calculate the TEER, in which it may be erroneously assumed that the entire cell culture area contributes equally to the measurement. In this study, we have numerically calculated this error in some cell cultures previously reported. In particular, we evidence that some TEER measurements resulted in errors when measuring low TEERs, especially when using Transwell inserts 12 mm in diameter or microfluidic systems that have small chamber heights. To correct this error, we propose the use of a geometric correction factor (GCF) for calculating the TEER. In addition, we describe a simple method to determine the GCF of a particular measurement system, so that it can be applied retrospectively. We have also experimentally validated an interdigitated electrodes (IDE) configuration where the entire cell culture area contributes equally to the measurement, and it also implements minimal electrode coverage so that the cells can be visualized alongside TEER analysis.

  10. Adjusting wheal size measures to correct atopy misclassification

    Directory of Open Access Journals (Sweden)

    Zhang H

    2011-08-01

    Full Text Available Hongmei Zhang1,*, Wilfried Karmaus1,*, Jianjun Gan2, Weichao Bao1,*, Yan D Zhao3, Dewi Rahardja3, John W Holloway5, Martha Scott4,5, Syed Hasan Arshad4,51Department of Epidemiology and Biostatistics, The University of South Carolina, Columbia, SC, USA; 2GlaxoSmithKline, Research Triangle Park, NC, USA; 3Department of Clinical Science and Simmons Cancer Center, UT Southwestern Medical Center, Dallas, TX, USA; 4The David Hide Asthma and Allergy Research Center, St Mary’s Hospital, Newport, Isle of Wight, UK; 5School of Medicine, University of Southampton, Southampton, UK *These authors contributed equally to this articlePurpose: Skin prick testing (SPT is fundamental to the practice of clinical allergy identifying relevant allergens and predicting the clinical expression of disease. Wheal sizes on SPT are used to identify atopic cases, and the cut-off value for a positive test is commonly set at 3 mm. However, the measured wheal sizes do not solely reflect the magnitude of skin reaction to allergens, but also skin reactivity (reflected in the size of histamine reaction and other random or non-random factors. We sought to estimate wheal sizes exclusively due to skin response to allergens and propose gender-specific cutoff points of atopy.Methods: We developed a Bayesian method to adjust observed wheal sizes by excluding histamine and other factor effects, based on which revised cutoff points are proposed for males and females, respectively. The method is then applied to and intensively evaluated using a study population aged 18, at a location on the Isle of Wight in the United Kingdom. To evaluate the proposed approach, two sample t-tests for population means and proportion tests are applied.Results: Four common aeroallergens, house dust mite (HDM, grass pollen, dog dander, and alternaria are considered in the study. Based on 3 mm cutoff, males tend to be more atopic than females (P-values are between 0.00087 and 0.062. After applying the

  11. Intensity-value corrections for integrating sphere measurements of solid samples measured behind glass.

    Science.gov (United States)

    Johnson, Timothy J; Bernacki, Bruce E; Redding, Rebecca L; Su, Yin-Fong; Brauer, Carolyn S; Myers, Tanya L; Stephan, Eric G

    2014-01-01

    Accurate and calibrated directional-hemispherical reflectance spectra of solids are important for both in situ and remote sensing. Many solids are in the form of powders or granules and to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass for the ultraviolet (UV), visible, or near-infrared spectral regions. Using both experimental methods and a simple optical model, we demonstrate that glass (fused quartz in our case) leads to artifacts in the reflectance values. We report our observations that the measured reflectance values, for both hemispherical and diffuse reflectance, are distorted by the additional reflections arising at the air-quartz and sample-quartz interfaces. The values are dependent on the sample reflectance and are offset in intensity in the hemispherical case, leading to measured values up to ~6% too high for a 2% reflectance surface, ~3.8% too high for 10% reflecting surfaces, approximately correct for 40-60% diffuse-reflecting surfaces, and ~1.5% too low for 99% reflecting Spectralon® surfaces. For the case of diffuse-only reflectance, the measured values are uniformly too low due to the polished glass, with differences of nearly 6% for a 99% reflecting matte surface. The deviations arise from the added reflections from the quartz surfaces, as verified by both theory and experiment, and depend on sphere design. Empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300-2300 nm range.

  12. The quantification and correction of wind-induced precipitation measurement errors

    Science.gov (United States)

    Kochendorfer, John; Rasmussen, Roy; Wolff, Mareile; Baker, Bruce; Hall, Mark E.; Meyers, Tilden; Landolt, Scott; Jachcik, Al; Isaksen, Ketil; Brækkan, Ragnar; Leeper, Ronald

    2017-04-01

    Hydrologic measurements are important for both the short- and long-term management of water resources. Of the terms in the hydrologic budget, precipitation is typically the most important input; however, measurements of precipitation are subject to large errors and biases. For example, an all-weather unshielded weighing precipitation gauge can collect less than 50 % of the actual amount of solid precipitation when wind speeds exceed 5 m s-1. Using results from two different precipitation test beds, such errors have been assessed for unshielded weighing gauges and for weighing gauges employing four of the most common windshields currently in use. Functions to correct wind-induced undercatch were developed and tested. In addition, corrections for the single-Alter weighing gauge were developed using the combined results of two separate sites in Norway and the USA. In general, the results indicate that the functions effectively correct the undercatch bias that affects such precipitation measurements. In addition, a single function developed for the single-Alter gauges effectively decreased the bias at both sites, with the bias at the US site improving from -12 to 0 %, and the bias at the Norwegian site improving from -27 to -4 %. These correction functions require only wind speed and air temperature as inputs, and were developed for use in national and local precipitation networks, hydrological monitoring, roadway and airport safety work, and climate change research. The techniques used to develop and test these transfer functions at more than one site can also be used for other more comprehensive studies, such as the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE).

  13. Clearing the waters: Evaluating the need for site-specific field fluorescence corrections based on turbidity measurements

    Science.gov (United States)

    Saraceno, John F.; Shanley, James B.; Downing, Bryan D.; Pellerin, Brian A.

    2017-01-01

    In situ fluorescent dissolved organic matter (fDOM) measurements have gained increasing popularity as a proxy for dissolved organic carbon (DOC) concentrations in streams. One challenge to accurate fDOM measurements in many streams is light attenuation due to suspended particles. Downing et al. (2012) evaluated the need for corrections to compensate for particle interference on fDOM measurements using a single sediment standard in a laboratory study. The application of those results to a large river improved unfiltered field fDOM accuracy. We tested the same correction equation in a headwater tropical stream and found that it overcompensated fDOM when turbidity exceeded ∼300 formazin nephelometric units (FNU). Therefore, we developed a site-specific, field-based fDOM correction equation through paired in situ fDOM measurements of filtered and unfiltered streamwater. The site-specific correction increased fDOM accuracy up to a turbidity as high as 700 FNU, the maximum observed in this study. The difference in performance between the laboratory-based correction equation of Downing et al. (2012) and our site-specific, field-based correction equation likely arises from differences in particle size distribution between the sediment standard used in the lab (silt) and that observed in our study (fine to medium sand), particularly during high flows. Therefore, a particle interference correction equation based on a single sediment type may not be ideal when field sediment size is significantly different. Given that field fDOM corrections for particle interference under turbid conditions are a critical component in generating accurate DOC estimates, we describe a way to develop site-specific corrections.

  14. Units-of-Measure Correctness in Fortran Programs

    OpenAIRE

    Contrastin, Mistral; Rice, Andrew; Danish, Matthew; Orchard, Dominic A.

    2015-01-01

    This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/MCSE.2016.17 The authors argue that they can increase confidence in Fortran programs with unit annotations and CamFort units-of-measure analysis. This work was supported by the Engineering and Physical Sciences Research Council (EP/M026124/1). The second author additionally thanks the Software Sustainability Institute for its support.

  15. Comparing measurement error correction methods for rate-of-change exposure variables in survival analysis.

    Science.gov (United States)

    Veronesi, Giovanni; Ferrario, Marco M; Chambless, Lloyd E

    2013-12-01

    In this article we focus on comparing measurement error correction methods for rate-of-change exposure variables in survival analysis, when longitudinal data are observed prior to the follow-up time. Motivational examples include the analysis of the association between changes in cardiovascular risk factors and subsequent onset of coronary events. We derive a measurement error model for the rate of change, estimated through subject-specific linear regression, assuming an additive measurement error model for the time-specific measurements. The rate of change is then included as a time-invariant variable in a Cox proportional hazards model, adjusting for the first time-specific measurement (baseline) and an error-free covariate. In a simulation study, we compared bias, standard deviation and mean squared error (MSE) for the regression calibration (RC) and the simulation-extrapolation (SIMEX) estimators. Our findings indicate that when the amount of measurement error is substantial, RC should be the preferred method, since it has smaller MSE for estimating the coefficients of the rate of change and of the variable measured without error. However, when the amount of measurement error is small, the choice of the method should take into account the event rate in the population and the effect size to be estimated. An application to an observational study, as well as examples of published studies where our model could have been applied, are also provided.

  16. Coupling Measurements and Corrections for the Combined Ramp and Squeeze

    CERN Document Server

    Persson, Tobias Hakan Bjorn; Langner, Andy Sven; Malina, Lukas; Maclean, Ewen Hamish; Coello De Portugal - Martinez Vazquez, Jaime Maria; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Schaumann, Michaela; Solfaroli Camillocci, Matteo; Skowronski, Piotr Krzysztof; Tomas Garcia, Rogelio; Garcia-Tabares Valdivieso, Ana; Wenninger, Jorg; CERN. Geneva. ATS Department

    2016-01-01

    In operation of the LHC the ramp and the squeeze process have been independent beam processes up to now. Making them into a combined process would save time to reach the point where the beams are brought to collision. This would increase the integrated luminosity provided by the LHC. One possible source of problems could be deviation from the ideal optics and in particular the control of the transverse coupling. In this report we focus on the coupling measurements that were taken during the Combined Ramp and Squeeze (CRS) MD.

  17. Limitations of Significance Testing in Clinical Research: A Review of Multiple Comparison Corrections and Effect Size Calculations with Correlated Measures.

    Science.gov (United States)

    Vasilopoulos, Terrie; Morey, Timothy E; Dhatariya, Ketan; Rice, Mark J

    2016-03-01

    Modern clinical research commonly uses complex designs with multiple related outcomes, including repeated-measures designs. While multiple comparison corrections and effect size calculations are needed to more accurately assess an intervention's significance and impact, understanding the limitations of these methods in the case of dependency and correlation is important. In this review, we outline methods for multiple comparison corrections and effect size calculations and considerations in cases of correlation and summarize relevant simulation studies to illustrate these concepts.

  18. Covariate measurement error correction methods in mediation analysis with failure time data.

    Science.gov (United States)

    Zhao, Shanshan; Prentice, Ross L

    2014-12-01

    Mediation analysis is important for understanding the mechanisms whereby one variable causes changes in another. Measurement error could obscure the ability of the potential mediator to explain such changes. This article focuses on developing correction methods for measurement error in the mediator with failure time outcomes. We consider a broad definition of measurement error, including technical error, and error associated with temporal variation. The underlying model with the "true" mediator is assumed to be of the Cox proportional hazards model form. The induced hazard ratio for the observed mediator no longer has a simple form independent of the baseline hazard function, due to the conditioning event. We propose a mean-variance regression calibration approach and a follow-up time regression calibration approach, to approximate the partial likelihood for the induced hazard function. Both methods demonstrate value in assessing mediation effects in simulation studies. These methods are generalized to multiple biomarkers and to both case-cohort and nested case-control sampling designs. We apply these correction methods to the Women's Health Initiative hormone therapy trials to understand the mediation effect of several serum sex hormone measures on the relationship between postmenopausal hormone therapy and breast cancer risk.

  19. Correcting for Measurement Error in Time-Varying Covariates in Marginal Structural Models.

    Science.gov (United States)

    Kyle, Ryan P; Moodie, Erica E M; Klein, Marina B; Abrahamowicz, Michał

    2016-08-01

    Unbiased estimation of causal parameters from marginal structural models (MSMs) requires a fundamental assumption of no unmeasured confounding. Unfortunately, the time-varying covariates used to obtain inverse probability weights are often error-prone. Although substantial measurement error in important confounders is known to undermine control of confounders in conventional unweighted regression models, this issue has received comparatively limited attention in the MSM literature. Here we propose a novel application of the simulation-extrapolation (SIMEX) procedure to address measurement error in time-varying covariates, and we compare 2 approaches. The direct approach to SIMEX-based correction targets outcome model parameters, while the indirect approach corrects the weights estimated using the exposure model. We assess the performance of the proposed methods in simulations under different clinically plausible assumptions. The simulations demonstrate that measurement errors in time-dependent covariates may induce substantial bias in MSM estimators of causal effects of time-varying exposures, and that both proposed SIMEX approaches yield practically unbiased estimates in scenarios featuring low-to-moderate degrees of error. We illustrate the proposed approach in a simple analysis of the relationship between sustained virological response and liver fibrosis progression among persons infected with hepatitis C virus, while accounting for measurement error in γ-glutamyltransferase, using data collected in the Canadian Co-infection Cohort Study from 2003 to 2014.

  20. Probabilistic correction of precipitation measurement errors using a Bayesian Model Average Approach applied for the estimation of glacier accumulation

    Science.gov (United States)

    Moya Quiroga, Vladimir; Mano, Akira; Asaoka, Yoshihiro; Udo, Keiko; Kure, Shuichi; Mendoza, Javier

    2013-04-01

    Precipitation is a major component of the water cycle that returns atmospheric water to the ground. Without precipitation there would be no water cycle, all the water would run down the rivers and into the seas, then the rivers would dry up with no fresh water from precipitation. Although precipitation measurement seems an easy and simple procedure, it is affected by several systematic errors which lead to underestimation of the actual precipitation. Hence, precipitation measurements should be corrected before their use. Different correction approaches were already suggested in order to correct precipitation measurements. Nevertheless, focusing on the outcome of a single model is prone to statistical bias and underestimation of uncertainty. In this presentation we propose a Bayesian model average (BMA) approach for correcting rain gauge measurement errors. In the present study we used meteorological data recorded every 10 minutes at the Condoriri station in the Bolivian Andes. Comparing rain gauge measurements with totalisators rain measurements it was possible to estimate the rain underestimation. First, different deterministic models were optimized for the correction of precipitation considering wind effect and precipitation intensities. Then, probabilistic BMA correction was performed. The corrected precipitation was then separated into rainfall and snowfall considering typical Andean temperature thresholds of -1°C and 3°C. Hence, precipitation was separated into rainfall, snowfall and mixed precipitation. Then, relating the total snowfall with the glacier ice density, it was possible to estimate the glacier accumulation. Results show a yearly glacier accumulation of 1200 mm/year. Besides, results confirm that in tropical glaciers winter is not accumulation period, but a low ablation one. Results show that neglecting such correction may induce an underestimation higher than 35 % of total precipitation. Besides, the uncertainty range may induce differences up

  1. Errors of first-order probe correction for higher-order probes in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Nielsen, Jeppe Majlund; Pivnenko, Sergiy

    2004-01-01

    An investigation is performed to study the error of the far-field pattern determined from a spherical near-field antenna measurement in the case where a first-order (mu=+-1) probe correction scheme is applied to the near-field signal measured by a higher-order probe....

  2. Computer assisted screening, correction, and analysis of historical weather measurements

    Science.gov (United States)

    Burnette, Dorian J.; Stahle, David W.

    2013-04-01

    A computer program, Historical Observation Tools (HOB Tools), has been developed to facilitate many of the calculations used by historical climatologists to develop instrumental and documentary temperature and precipitation datasets and makes them readily accessible to other researchers. The primitive methodology used by the early weather observers makes the application of standard techniques difficult. HOB Tools provides a step-by-step framework to visually and statistically assess, adjust, and reconstruct historical temperature and precipitation datasets. These routines include the ability to check for undocumented discontinuities, adjust temperature data for poor thermometer exposures and diurnal averaging, and assess and adjust daily precipitation data for undercount. This paper provides an overview of the Visual Basic.NET program and a demonstration of how it can assist in the development of extended temperature and precipitation datasets using modern and early instrumental measurements from the United States.

  3. A method to correct sampling ghosts in historic near-infrared Fourier transform spectrometer (FTS measurements

    Directory of Open Access Journals (Sweden)

    S. Dohe

    2013-08-01

    Full Text Available The Total Carbon Column Observing Network (TCCON has been established to provide ground-based remote sensing measurements of the column-averaged dry air mole fractions (DMF of key greenhouse gases. To ensure network-wide consistency, biases between Fourier transform spectrometers at different sites have to be well controlled. Errors in interferogram sampling can introduce significant biases in retrievals. In this study we investigate a two-step scheme to correct these errors. In the first step the laser sampling error (LSE is estimated by determining the sampling shift which minimises the magnitude of the signal intensity in selected, fully absorbed regions of the solar spectrum. The LSE is estimated for every day with measurements which meet certain selection criteria to derive the site-specific time series of the LSEs. In the second step, this sequence of LSEs is used to resample all the interferograms acquired at the site, and hence correct the sampling errors. Measurements acquired at the Izaña and Lauder TCCON sites are used to demonstrate the method. At both sites the sampling error histories show changes in LSE due to instrument interventions (e.g. realignment. Estimated LSEs are in good agreement with sampling errors inferred from the ratio of primary and ghost spectral signatures in optically bandpass-limited tungsten lamp spectra acquired at Lauder. The original time series of Xair and XCO2 (XY: column-averaged DMF of the target gas Y at both sites show discrepancies of 0.2–0.5% due to changes in the LSE associated with instrument interventions or changes in the measurement sample rate. After resampling, discrepancies are reduced to 0.1% or less at Lauder and 0.2% at Izaña. In the latter case, coincident changes in interferometer alignment may also have contributed to the residual difference. In the future the proposed method will be used to correct historical spectra at all TCCON sites.

  4. A method to correct sampling ghosts in historic near-infrared Fourier transform spectrometer (FTS) measurements

    Science.gov (United States)

    Dohe, S.; Sherlock, V.; Hase, F.; Gisi, M.; Robinson, J.; Sepúlveda, E.; Schneider, M.; Blumenstock, T.

    2013-08-01

    The Total Carbon Column Observing Network (TCCON) has been established to provide ground-based remote sensing measurements of the column-averaged dry air mole fractions (DMF) of key greenhouse gases. To ensure network-wide consistency, biases between Fourier transform spectrometers at different sites have to be well controlled. Errors in interferogram sampling can introduce significant biases in retrievals. In this study we investigate a two-step scheme to correct these errors. In the first step the laser sampling error (LSE) is estimated by determining the sampling shift which minimises the magnitude of the signal intensity in selected, fully absorbed regions of the solar spectrum. The LSE is estimated for every day with measurements which meet certain selection criteria to derive the site-specific time series of the LSEs. In the second step, this sequence of LSEs is used to resample all the interferograms acquired at the site, and hence correct the sampling errors. Measurements acquired at the Izaña and Lauder TCCON sites are used to demonstrate the method. At both sites the sampling error histories show changes in LSE due to instrument interventions (e.g. realignment). Estimated LSEs are in good agreement with sampling errors inferred from the ratio of primary and ghost spectral signatures in optically bandpass-limited tungsten lamp spectra acquired at Lauder. The original time series of Xair and XCO2 (XY: column-averaged DMF of the target gas Y) at both sites show discrepancies of 0.2-0.5% due to changes in the LSE associated with instrument interventions or changes in the measurement sample rate. After resampling, discrepancies are reduced to 0.1% or less at Lauder and 0.2% at Izaña. In the latter case, coincident changes in interferometer alignment may also have contributed to the residual difference. In the future the proposed method will be used to correct historical spectra at all TCCON sites.

  5. Effect of joint rotation correction when measuring elongation of the gastrocnemius medialis tendon and aponeurosis.

    Science.gov (United States)

    Arampatzis, Adamantios; Monte, Gianpiero De; Karamanidis, Kiros

    2008-06-01

    It is well known that during maximal plantar flexion contractions the ankle joint rotation overestimates the actual elongation of the tendon and aponeurosis. The aim of this study was to examine the influence of the curve length changes of the Achilles tendon on the joint rotation corrected elongation and strain of the gastrocnemius medialis (GM) tendon and aponeurosis. Nine subjects (age: 29.4+/-5.7 years, body mass: 78.8+/-6.8 kg, body height: 178+/-4 cm) participated in the study. The subjects performed maximal voluntary isometric plantarflexion contractions in the prone position on a Biodex-dynamometer. Ultrasonography (Aloka SSD 4000) was used to visualize the muscle belly of the GM muscle-tendon unit. To calculate the curve length changes of the Achilles tendon its surface contour was reconstructed using a series of small reflective skin markers having a diameter of 2.5mm. The elongation of the GM tendon and aponeurosis was calculated (a) as the difference of the measured and the passive (due to joint rotation) displacement of the tendon and aponeurosis and (b) as the difference of the measured displacement and the length changes of the reconstructed Achilles tendon surface contour. The absolute difference between the elongation obtained by both methods were 1.2+/-0.4mm. These differences were due to the higher changes in length obtained by the reconstruction of the tendon curved surface contour as compared to the changes observed in the passive displacement of the digitised point at the aponeurosis. Without correcting for angle joint rotation, the measured elongation clearly overestimates the actual elongation of the GM tendon and aponeurosis. After the passive displacement correction the calculated elongation still overestimates the actual elongation of the GM tendon and aponeurosis. However, this overestimation has a negligible effect on the examined in vivo strain ( approximately 0.3%) of the tendon and aponeurosis.

  6. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.

    Science.gov (United States)

    Hindasageri, V; Vedula, R P; Prabhu, S V

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

  7. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient

    Science.gov (United States)

    Hindasageri, V.; Vedula, R. P.; Prabhu, S. V.

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

  8. Correctional services and prison chaplaincy in Australia: an exploratory study.

    Science.gov (United States)

    Carey, Lindsay B; Del Medico, Laura

    2014-12-01

    This paper summarizes an exploratory study undertaken to consider the work of Australian chaplaincy personnel ministering to prisoners within correctional facilities. This qualitative research was not concerned with specific correctional institutions per se, but predominantly about the perspectives of chaplains concerning their professional contribution and issues they experienced while trying to provide pastoral care to prisoners. Data from a single-focus group indicated that prison chaplains were striving to fulfill religious and spiritual duties according to national and international standards for the treatment of prisoners. Given various frustrations identified by participants, that either impeded or thwarted their professional role as chaplains, a number of improvements were subsequently identified in order to develop the efficiency and effectiveness of chaplaincy and thus maximize the benefits of pastoral care to prisoners. Implications of this exploratory study relate not only to prison chaplaincy but also to ecclesiastical organizations, correctional facilities, governments and the need of support for further research to be conducted.

  9. Evaluation of Correction Algorithm for the Reflectance Measured with Optical Glass

    Institute of Scientific and Technical Information of China (English)

    车江宁; 周志华; 陈东辉

    2003-01-01

    The proposed algorithm for reflectance measured with optical glass has been verified with materials of various forms. The refiectances measured with optical glass (raw), without glass (true) and corrected by the algorithm are compared. The results show that the corrected reflectance agrees very well with true one and their color differences fall below the acceptable limit, which indicates the validity of the correction algorithm. The algorithm could be used not only for fiber-forming materials, but also for powder- forming, granulate-forming, etc.

  10. Attenuation correction effects on SPECT/CT procedures: phantoms studies.

    Science.gov (United States)

    Oliveira, M L; Seren, M E G; Rocha, F C; Brunetto, S Q; Ramos, C D; Button, V L S N

    2013-01-01

    Attenuation correction is widely used in SPECT/CT (Single Photon Emission Computed Tomography) procedures, especially for imaging of the thorax region. Different compensation methods have been developed and introduced into clinical practice. Most of them use attenuation maps obtained using transmission scanning systems. However, this gives extra dose of radiation to the patient. The purpose of this study was to identify when attenuation correction is really important during SPECT/CT procedures.For this purpose, we used Jaszczak phantom and phantom with three line sources, filled with technetium ((99m)-Tc), with scattering materials, like air, water and acrylic, in different detectors configurations. In all images acquired were applied analytic and iterative reconstruction algorithms; the last one with or without attenuation correction. We analyzed parameters such as eccentricity, contrast and spatial resolution in the images.The best reconstruction algorithm on average was iterative, for images with 128 × 128 and 64 × 64 matrixes. The analytical algorithm was effective only to improve eccentricity in 64 × 64 matrix and matrix in contrast 128 × 128 with low statistics. Turning to the clinical routine examinations, on average, for 128 × 128 matrix and low statistics counting, the best algorithm was the iterative, without attenuation correction,improving in 150% the three parameters analyzed and, for the same matrix size, but with high statistical counting, iterative algorithm with attenuation correction was 25% better than that without correction. We can conclude that using the iterative algorithm with attenuation correction in the water, and its extra dose given, is not justified for the procedures of low statistic counting, being relevant only if the intention is to prioritize contrast in acquisitions with high statistic counting.

  11. β-particle energy-summing correction for β-delayed proton emission measurements

    Science.gov (United States)

    Meisel, Z.; del Santo, M.; Crawford, H. L.; Cyburt, R. H.; Grinyer, G. F.; Langer, C.; Montes, F.; Schatz, H.; Smith, K.

    2017-02-01

    A common approach to studying β-delayed proton emission is to measure the energy of the emitted proton and corresponding nuclear recoil in a double-sided silicon-strip detector (DSSD) after implanting the β-delayed proton-emitting (βp) nucleus. However, in order to extract the proton-decay energy, the measured energy must be corrected for the additional energy implanted in the DSSD by the β-particle emitted from the βp nucleus, an effect referred to here as β-summing. We present an approach to determine an accurate correction for β-summing. Our method relies on the determination of the mean implantation depth of the βp nucleus within the DSSD by analyzing the shape of the total (proton + recoil + β) decay energy distribution shape. We validate this approach with other mean implantation depth measurement techniques that take advantage of energy deposition within DSSDs upstream and downstream of the implantation DSSD.

  12. Calculation of correction factors for ionization chamber measurements with small fields in low-density media.

    Science.gov (United States)

    Pisaturo, O; Pachoud, M; Bochud, F O; Moeckli, R

    2012-07-21

    The quantity of interest for high-energy photon beam therapy recommended by most dosimetric protocols is the absorbed dose to water. Thus, ionization chambers are calibrated in absorbed dose to water, which is the same quantity as what is calculated by most treatment planning systems (TPS). However, when measurements are performed in a low-density medium, the presence of the ionization chamber generates a perturbation at the level of the secondary particle range. Therefore, the measured quantity is close to the absorbed dose to a volume of water equivalent to the chamber volume. This quantity is not equivalent to the dose calculated by a TPS, which is the absorbed dose to an infinitesimally small volume of water. This phenomenon can lead to an overestimation of the absorbed dose measured with an ionization chamber of up to 40% in extreme cases. In this paper, we propose a method to calculate correction factors based on the Monte Carlo simulations. These correction factors are obtained by the ratio of the absorbed dose to water in a low-density medium □D(w,Q,V1)(low) averaged over a scoring volume V₁ for a geometry where V₁ is filled with the low-density medium and the absorbed dose to water □D(w,QV2)(low) averaged over a volume V₂ for a geometry where V₂ is filled with water. In the Monte Carlo simulations, □D(w,QV2)(low) is obtained by replacing the volume of the ionization chamber by an equivalent volume of water, according to the definition of the absorbed dose to water. The method is validated in two different configurations which allowed us to study the behavior of this correction factor as a function of depth in phantom, photon beam energy, phantom density and field size.

  13. Algorithm-supported visual error correction (AVEC) of heart rate measurements in dogs, Canis lupus familiaris.

    Science.gov (United States)

    Schöberl, Iris; Kortekaas, Kim; Schöberl, Franz F; Kotrschal, Kurt

    2015-12-01

    Dog heart rate (HR) is characterized by a respiratory sinus arrhythmia, and therefore makes an automatic algorithm for error correction of HR measurements hard to apply. Here, we present a new method of error correction for HR data collected with the Polar system, including (1) visual inspection of the data, (2) a standardized way to decide with the aid of an algorithm whether or not a value is an outlier (i.e., "error"), and (3) the subsequent removal of this error from the data set. We applied our new error correction method to the HR data of 24 dogs and compared the uncorrected and corrected data, as well as the algorithm-supported visual error correction (AVEC) with the Polar error correction. The results showed that fewer values were identified as errors after AVEC than after the Polar error correction (p error correction is more suitable for dog HR and HR variability than is the customized Polar error correction, especially because AVEC decreases the likelihood of Type I errors, preserves the natural variability in HR, and does not lead to a time shift in the data.

  14. Study of orbit correction for eRHIC FFAG design

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hao, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    The unique feature of the orbits in the eRHIC Fixed Field Alternating Gradient (FFAG) design is that multiple accelerating and decelerating bunches pass through the same magnets with different horizontal offsets. Therefore, it is critical for the eRHIC FFAG to correct multiple orbits in the same vacuum pipe for better spin transmission and alignment of colliding beams. In this report, the effects on orbits from multiple error sources will be studied. The orbit correction method will be described and results will be presented.

  15. Bias-Correction in Vector Autoregressive Models: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Tom Engsted

    2014-03-01

    Full Text Available We analyze the properties of various methods for bias-correcting parameter estimates in both stationary and non-stationary vector autoregressive models. First, we show that two analytical bias formulas from the existing literature are in fact identical. Next, based on a detailed simulation study, we show that when the model is stationary this simple bias formula compares very favorably to bootstrap bias-correction, both in terms of bias and mean squared error. In non-stationary models, the analytical bias formula performs noticeably worse than bootstrapping. Both methods yield a notable improvement over ordinary least squares. We pay special attention to the risk of pushing an otherwise stationary model into the non-stationary region of the parameter space when correcting for bias. Finally, we consider a recently proposed reduced-bias weighted least squares estimator, and we find that it compares very favorably in non-stationary models.

  16. Minimizing errors in phase change correction measurements for gauge blocks using a spherical contact technique

    Science.gov (United States)

    Stoup, John R.; Faust, Bryon S.; Doiron, Theodore D.

    1998-09-01

    One of the most elusive measurement elements in gage block interferometry is the correction for the phase change on reflection. Techniques used to quantify this correction have improved over the year, but the measurement uncertainty has remained relatively constant because some error sources have proven historically difficult to reduce. The precision engineering division at the National Institute of Standards and Technology has recently developed a measurement technique that can quantify the phase change on reflection correction directly for individual gage blocks and eliminates some of the fundamental problems with historical measurement methods. Since only the top surface of the gage block is used in the measurement, wringing film inconsistencies are eliminated with this technique thereby drastically reducing the measurement uncertainty for the correction. However, block geometry and thermal issues still exist. This paper will describe the methods used to minimize the measurement uncertainty of the phase change on reflection evaluation using a spherical contact technique. The work focuses on gage block surface topography and drift eliminating algorithms for the data collection. The extrapolation of the data to an undeformed condition and the failure of these curves to follow theoretical estimates are also discussed. The wavelength dependence of the correction was directly measured for different gage block materials and manufacturers and the data will be presented.

  17. Bias-correction in vector autoregressive models: A simulation study

    DEFF Research Database (Denmark)

    Engsted, Tom; Pedersen, Thomas Quistgaard

    We analyze and compare the properties of various methods for bias-correcting parameter estimates in vector autoregressions. First, we show that two analytical bias formulas from the existing literature are in fact identical. Next, based on a detailed simulation study, we show that this simple and...

  18. Plantar measurements to determine success of surgical correction of Stage IIb adult acquired flatfoot deformity.

    Science.gov (United States)

    Matheis, Erika A; Spratley, E Meade; Hayes, Curtis W; Adelaar, Robert S; Wayne, Jennifer S

    2014-01-01

    Adult acquired flatfoot deformity is a degenerative disease causing medial arch dysfunction. Surgical correction has typically involved tendon reconstruction with calcaneal osteotomy; however, the postoperative changes have not been fully characterized. The present study assessed the success of surgical correction of Stage IIb adult acquired flatfoot deformity through changes in plantar pressures and patient-generated outcome scores. With Institutional Review Board approval, 6 participants were evaluated before and after surgery using pedobarography, the Foot and Ankle Outcome Score, and the Medical Outcomes Study 36-item short-form questionnaire. The plantar pressures were recorded using a TekScan HRMat(®) during walking and in a 1- and 2-foot stance. The resulting contour maps were segmented into 9 regions, with the peak pressure, normalized force, and arch index calculated. Surgical effects were analyzed using paired t tests. Postoperatively, the Foot and Ankle Outcome Score and Medical Outcomes Study 36-item short-form questionnaire scores increased significantly from 180 ± 78 to 360 ± 136 (p < .03) and 47 ± 18 to 71 ± 19 (p = .06), respectively. During the 2-foot stance, the normalized force had increased significantly in the lateral midfoot (p < .03), although no significant differences were found in peak pressures. No significant differences were observed in the 1-foot stance. During walking, the normalized force increased significantly in the lateral mid- and forefoot (p < .05). The peak pressure increased significantly in the lateral forefoot (p < .01). The arch index values demonstrated no significant changes. The increased questionnaire scores indicated that surgical correction improved the self-perceived health of the participants. Lateral shifts in the peak pressure and normalized force suggest that forefoot and midfoot loading is altered postoperatively, consistent with the goal of offloading the dysfunctional arch. Thus, the present study has

  19. Scoring correction for MMPI-2 Hs scale with patients experiencing a traumatic brain injury: a test of measurement invariance.

    Science.gov (United States)

    Alkemade, Nathan; Bowden, Stephen C; Salzman, Louis

    2015-02-01

    It has been suggested that MMPI-2 scoring requires removal of some items when assessing patients after a traumatic brain injury (TBI). Gass (1991. MMPI-2 interpretation and closed head injury: A correction factor. Psychological assessment, 3, 27-31) proposed a correction procedure in line with the hypothesis that MMPI-2 endorsement may be affected by symptoms of TBI. This study assessed the validity of the Gass correction procedure. A sample of patients with a TBI (n = 242), and a random subset of the MMPI-2 normative sample (n = 1,786). The correction procedure implies a failure of measurement invariance across populations. This study examined measurement invariance of one of the MMPI-2 scales (Hs) that includes TBI correction items. A four-factor model of the MMPI-2 Hs items was defined. The factor model was found to meet the criteria for partial measurement invariance. Analysis of the change in sensitivity and specificity values implied by partial measurement invariance failed to indicate significant practical impact of partial invariance. Overall, the results support continued use of all Hs items to assess psychological well-being in patients with TBI. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Elliptical Weighted HOLICs for Weak Lensing Shear Measurement. part1:Definitions and isotropic PSF correction

    CERN Document Server

    Okura, Yuki

    2010-01-01

    We develop a new method to estimate gravitational shear by adopting an elliptical weight function to measure background galaxy images. In doing so, we introduce a new concept of "zero plane" which is an imaginal source plane where shapes of all sources are perfect circles, and regard the intrinsic shear as the result of an imaginal lensing distortion. This makes the relation between the observed shear, the intrinsic shear and lensing distortion more simple and thus higher-order calculation more easy. The elliptical weight function allows us to measure the mutiplemoment of shape of background galaxies more precisely by weighting highly to brighter parts of image and moreover to reduce systematic error due to insufficient expansion of the weight function in the original approach of KSB. Point Spread Function(PSF) correction in E-HOLICs methods becomes more complicated than those in KSB methods. In this paper we studied isotropic PSF correction in detail. By adopting the lensing distortion as the ellipticity of ...

  1. Positron annihilation lifetime spectroscopy source correction determination: A simulation study

    Science.gov (United States)

    Kanda, Gurmeet S.; Keeble, David J.

    2016-02-01

    Positron annihilation lifetime spectroscopy (PALS) can provide sensitive detection and identification of vacancy-related point defects in materials. These measurements are normally performed using a positron source supported, and enclosed by, a thin foil. Annihilation events from this source arrangement must be quantified and are normally subtracted from the spectrum before analysis of the material lifetime components proceeds. Here simulated PALS spectra reproducing source correction evaluation experiments have been systematically fitted and analysed using the packages PALSfit and MELT. Simulations were performed assuming a single lifetime material, and for a material with two lifetime components. Source correction terms representing a directly deposited source and various foil supported sources were added. It is shown that in principle these source terms can be extracted from suitably designed experiments, but that fitting a number of independent, nominally identical, spectra is recommended.

  2. Aspects of probe correction for odd-order probes in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Pivnenko, Sergey N.; Breinbjerg, Olav

    2004-01-01

    Probe correction aspects for the spherical near-field antenna measurements are investigated. First, the spherical mode analyses of the radiated fields of several antennas are performed. It is shown that many common antennas are essentially so-called odd-order antennas. Second, the errors caused...... by the use of the first-order probe correction [1] for a rectangular waveguide probe, that is an odd-order antenna, are demonstrated. Third, a recently developed probe correction technique for odd-order probes is applied for the rectangular waveguide probe and shown to provide accurate results....

  3. Case Study: Learner Attitudes Towards the Correction of Mistakes

    Directory of Open Access Journals (Sweden)

    Galina Kavaliauskienė

    2013-01-01

    Full Text Available The objective of the research is to explore learner attitudes to correction of mistakes or feedback as a language learning tool in oral, electronically- and paper-written work as well as peer correction of mistakes. Feedback is a method used in the teaching of languages to improve performance by sharing observations, concerns and suggestions with regard to written work or oral presentation. It includes not only correcting learners, but also assessing them. Both correction and assessment depend on mistakes being made, reasons for mistakes, and class activities. Recently the value of feedback in language studies has been a matter of debate among language teaching practitioners. The research into the effects of feedback is far from conclusive. Teachers’ and students’ expectations toward feedback are found to be opposing, and the most frequent reason given is its negative impact on students’ confidence and motivation. However, at the university level the issue of feedback has been examined in passing and there is insufficient research into learner attitudes to feedback in English for Specific Purposes. The hypothesis for the present study is to find out whether criticism has a negative impact on student confidence and whether perceptions of feedback depend on professional specialization. The research methods. A survey of students’ perceptions of teachers’ feedback in various class activities was administered to various groups of undergraduate students of psychology and penitentiary law. Statistical treatment of students’ responses using Statistical Package for the Social Sciences software (SPSS was carried out in order to establish the level of significance for the two small samples of participants. The respondents in this research participated students of two different specializations, penitentiary law and psychology, who study English for Specific Purposes at the Faculty of Social Policy, Mykolas Romeris University in Vilnius

  4. Case Study: Learner Attitudes Towards the Correction of Mistakes

    Directory of Open Access Journals (Sweden)

    Galina Kavaliauskienė

    2012-07-01

    Full Text Available The objective of the research is to explore learner attitudes to correction of mistakes or feedback as a language learning tool in oral, electronically- and paper-written work as well as peer correction of mistakes.Feedback is a method used in the teaching of languages to improve performance by sharing observations, concerns and suggestions with regard to written work or oral presentation. It includes not only correcting learners, but also assessing them. Both correction and assessment depend on mistakes being made, reasons for mistakes, and class activities. Recently the value of feedback in language studies has been a matter of debate among language teaching practitioners. The research into the effects of feedback is far from conclusive. Teachers’ and students’ expectations toward feedback are found to be opposing, and the most frequent reason given is its negative impact on students’ confidence and motivation. However, at the university level the issue of feedback has been examined in passing and there is insufficient research into learner attitudes to feedback in English for Specific Purposes.The hypothesis for the present study is to find out whether criticism has a negative impact on student confidence and whether perceptions of feedback depend on professional specialization.The research methods. A survey of students’ perceptions of teachers’ feedback in various class activities was administered to various groups of undergraduate students of psychology and penitentiary law. Statistical treatment of students’ responses using Statistical Package for the Social Sciences software (SPSS was carried out in order to establish the level of significance for the two small samples of participants.The respondents in this research participated students of two different specializations, penitentiary law and psychology, who study English for Specific Purposes at the Faculty of Social Policy, Mykolas Romeris University in Vilnius, Lithuania

  5. Correction of raindrop size distributions measured by Parsivel disdrometers, using a two-dimensional video disdrometer as a reference

    Directory of Open Access Journals (Sweden)

    T. H. Raupach

    2015-01-01

    Full Text Available The raindrop size distribution (DSD quantifies the microstructure of rainfall and is critical to studying precipitation processes. We present a method to improve the accuracy of DSD measurements from Parsivel (particle size and velocity disdrometers, using a two-dimensional video disdrometer (2DVD as a reference instrument. Parsivel disdrometers bin raindrops into velocity and equivolume diameter classes, but may misestimate the number of drops per class. In our correction method, drop velocities are corrected with reference to theoretical models of terminal drop velocity. We define a filter for raw disdrometer measurements to remove particles that are unlikely to be plausible raindrops. Drop concentrations are corrected such that on average the Parsivel concentrations match those recorded by a 2DVD. The correction can be trained on and applied to data from both generations of OTT Parsivel disdrometers, and indeed any disdrometer in general. The method was applied to data collected during field campaigns in Mediterranean France for a network of first- and second-generation Parsivel disdrometers, and on a first-generation Parsivel in Payerne, Switzerland. We compared the moments of the resulting DSDs to those of a collocated 2DVD, and the resulting DSD-derived rain rates to collocated rain gauges. The correction improved the accuracy of the moments of the Parsivel DSDs, and in the majority of cases the rain rate match with collocated rain gauges was improved. In addition, the correction was shown to be similar for two different climatologies, suggesting its general applicability.

  6. Flow gradient corrections on hot-wire measurements using an X-wire probe

    Science.gov (United States)

    Gooden, J. H. M.; van Lent, M.

    A method has been developed to correct hot-wire measurements by means of a single X-wire probe for the effect of gradients normal to the plane of the wires in the mean flow velocities as well as in the turbulence intensities. Dataprocessing is performed in an iterative way, using the results of measurements with different probe rolling angles, to determine the gradient corrections along the traverse from the previous loop. The method has been applied to measurements in the wake above the trailing edge flap of a wing and it is shown that substantial improvements in the results have been achieved.

  7. Correction for the diffraction loss in the ultrasonic attenuation measurement in VHF range

    Institute of Scientific and Technical Information of China (English)

    WEI Tingcun

    2002-01-01

    Two silicate glasses which have different acoustic properties and different thickness,were taken as the specimens, their frequency dependences of the longitudinal attenuation coef-ficients were measured in the frequency range of 50 to 300 MHz by the pulse reflection method,and the diffraction loss included in the measurement was corrected by theoretical calculationusing A. O. Williams' expression. It has been shown that the measurement error of attenuationcoefficient due to diffraction loss could be corrected very well by this method, regardless of thethickness of specimens.

  8. Optical-Thickness Corrections to Transient Ece Temperature-Measurements in Tokamak and Stellarator Plasmas

    NARCIS (Netherlands)

    Peters, M.; Gorini, G.; Mantica, P.

    1995-01-01

    The conditions are examined under which optical thickness (tau) corrections to electron cyclotron emission (ECE) measurements of electron temperature (T-e) can be neglected. By means of simple algebra it is demonstrated that for measurements of T-e transients the ECE radiation temperature (T-rad) ca

  9. Influence and Correction from the Human Body on the Measurement of a Power-Frequency Electric Field Sensor.

    Science.gov (United States)

    Xiao, Dongping; Liu, Huaitong; Zhou, Qiang; Xie, Yutong; Ma, Qichao

    2016-06-10

    According to the operating specifications of existing electric field measuring instruments, measuring technicians must be located far from the instruments to eliminate the influence of the human body occupancy on a spatial electric field. Nevertheless, in order to develop a portable safety protection instrument with an effective electric field warning function for working staff in a high-voltage environment, it is necessary to study the influence of an approaching human body on the measurement of an electric field and to correct the measurement results. A single-shaft electric field measuring instrument called the Type LP-2000, which was developed by our research team, is used as the research object in this study. First, we explain the principle of electric field measurement and describe the capacitance effect produced by the human body. Through a theoretical analysis, we show that the measured electric field value decreases as a human body approaches. Their relationship is linearly proportional. Then, the ratio is identified as a correction coefficient to correct for the influence of human body proximity. The conclusion drawn from the theoretical analysis is proved via simulation. The correction coefficient kb = 1.8010 is obtained on the basis of the linear fitting of simulated data. Finally, a physical experiment is performed. When no human is present, we compare the results from the Type LP-2000 measured with Narda EFA-300 and the simulated value to verify the accuracy of the Type LP-2000. For the case of an approaching human body, the correction coefficient kb* = 1.9094 is obtained by comparing the data measured with the Type LP-2000 to the simulated value. The correction coefficient obtained from the experiment (i.e., kb*) is highly consistent with that obtained from the simulation (i.e., kb). Two experimental programs are set; under these programs, the excitation voltages and distance measuring points are regulated to produce different electric field

  10. Influence and Correction from the Human Body on the Measurement of a Power-Frequency Electric Field Sensor

    Science.gov (United States)

    Xiao, Dongping; Liu, Huaitong; Zhou, Qiang; Xie, Yutong; Ma, Qichao

    2016-01-01

    According to the operating specifications of existing electric field measuring instruments, measuring technicians must be located far from the instruments to eliminate the influence of the human body occupancy on a spatial electric field. Nevertheless, in order to develop a portable safety protection instrument with an effective electric field warning function for working staff in a high-voltage environment, it is necessary to study the influence of an approaching human body on the measurement of an electric field and to correct the measurement results. A single-shaft electric field measuring instrument called the Type LP-2000, which was developed by our research team, is used as the research object in this study. First, we explain the principle of electric field measurement and describe the capacitance effect produced by the human body. Through a theoretical analysis, we show that the measured electric field value decreases as a human body approaches. Their relationship is linearly proportional. Then, the ratio is identified as a correction coefficient to correct for the influence of human body proximity. The conclusion drawn from the theoretical analysis is proved via simulation. The correction coefficient kb = 1.8010 is obtained on the basis of the linear fitting of simulated data. Finally, a physical experiment is performed. When no human is present, we compare the results from the Type LP-2000 measured with Narda EFA-300 and the simulated value to verify the accuracy of the Type LP-2000. For the case of an approaching human body, the correction coefficient kb* = 1.9094 is obtained by comparing the data measured with the Type LP-2000 to the simulated value. The correction coefficient obtained from the experiment (i.e., kb*) is highly consistent with that obtained from the simulation (i.e., kb). Two experimental programs are set; under these programs, the excitation voltages and distance measuring points are regulated to produce different electric field

  11. Comparative study of van der Waals corrections to the bulk properties of graphite.

    Science.gov (United States)

    Rêgo, Celso R C; Oliveira, Luiz N; Tereshchuk, Polina; Da Silva, Juarez L F

    2015-10-21

    Graphite is a stack of honeycomb (graphene) layers bound together by nonlocal, long-range van der Waals (vdW) forces, which are poorly described by density functional theory (DFT) within local or semilocal exchange-correlation functionals. Several approximations have been proposed to add a vdW correction to the DFT total energies (Stefan Grimme (D2 and D3) with different damping functions (D3-BJ), Tkatchenko-Scheffler (TS) without and with self-consistent screening (TS  +  SCS) effects). Those corrections have remarkly improved the agreement between our results and experiment for the interlayer distance (from 3.9 to 0.6%) [corrected] and high-level random-phase approximation (RPA) calculations for interlayer binding energy (from 69.5 to 1.5%). [corrected]. We report a systematic investigation of various structural, energetic and electron properties with the aforementioned vdW corrections followed by comparison with experimental and theoretical RPA data. Comparison between the resulting relative errors shows that the TS  +  SCS correction provides the best results; the other corrections yield significantly larger errors for at least one of the studied properties. If considerations of computational costs or convergence problems rule out the TS  +  SCS approach, we recommend the D3-BJ correction. Comparison between the computed π(z)Γ-splitting and experimental results shows disagreements of 10% or more with all vdW corrections. Even the computationally more expensive hybrid PBE0 has proved unable to improve the agreement with the measured splitting. Our results indicate that improvements of the exchange-correlation functionals beyond the vdW corrections are necessary to accurately describe the band structure of graphite.

  12. Corrective measures evaluation work plan : Technical Area V Groundwater : revision 0.

    Energy Technology Data Exchange (ETDEWEB)

    Lebow, Patrick S.; Dettmers, Dana L.; Hall, Kevin A.

    2004-12-01

    This document, which is prepared as directed by the Compliance Order on Consent (COOC) issued by the New Mexico Environment Department, identifies and outlines a process to evaluate remedial alternatives to identify a corrective measure for the Sandia National Laboratories/New Mexico Technical Area (TA)-V Groundwater. The COOC provides guidance for implementation of a Corrective Measures Evaluation (CME) for the TA-V Groundwater. This Work Plan documents an initial screening of remedial technologies and presents a list of possible remedial alternatives for those technologies that passed the screening. This Work Plan outlines the methods for evaluating these remedial alternatives and describes possible site-specific evaluation activities necessary to estimate remedy effectiveness and cost. These methods will be reported in the CME Report. This Work Plan outlines the CME Report, including key components and a description of the corrective measures process.

  13. Correction for Measurement Error from Genotyping-by-Sequencing in Genomic Variance and Genomic Prediction Models

    DEFF Research Database (Denmark)

    Ashraf, Bilal; Janss, Luc; Jensen, Just

    Genotyping-by-sequencing (GBSeq) is becoming a cost-effective genotyping platform for species without available SNP arrays. GBSeq considers to sequence short reads from restriction sites covering a limited part of the genome (e.g., 5-10%) with low sequencing depth per individual (e.g., 5-10X per....... In the current work we show how the correction for measurement error in GBSeq can also be applied in whole genome genomic variance and genomic prediction models. Bayesian whole-genome random regression models are proposed to allow implementation of large-scale SNP-based models with a per-SNP correction...... for measurement error. We show correct retrieval of genomic explained variance, and improved genomic prediction when accounting for the measurement error in GBSeq data...

  14. Taking laser Doppler vibrometry off the tripod: correction of measurements affected by instrument vibration

    Science.gov (United States)

    Halkon, Ben J.; Rothberg, Steve J.

    2017-04-01

    Laser Doppler vibrometers (LDVs) are now well-established as an effective non-contact alternative to traditional contacting transducers. Despite 30 years of successful applications, however, very little attention has been given to sensitivity to vibration of the instrument itself. In this paper, the sensitivity to instrument vibration is confirmed before development theoretically and experimentally of a practical scheme to enable correction of measurements for arbitrary instrument vibration. The scheme requires a pair of correction sensors with appropriate orientation and relative location, while using frequency domain processing to accommodate inter-channel time delay and signal integrations. Error reductions in excess of 30 dB are delivered in laboratory tests with simultaneous instrument and target vibration over a broad frequency range. Ultimately, application to measurement on a vehicle simulator experiencing high levels of vibration demonstrates the practical nature of the correction technique and its robustness in a challenging measurement environment.

  15. Experimental results on a wall interference correction method with interface measurements

    Science.gov (United States)

    Lo, C. F.; Ulbrich, N.

    1992-01-01

    A wall interference assessment and correction method for subsonic two-dimensional wind tunnel testing is presented. This method calculates a pressure coefficient and angle of attack correction based on velocity measurements on interfaces inside of the wind tunnel. A mathematical representation of the test article is not required. An experimental verification of the suggested technique is given. A NACA 0012 airfoil is tested at a Mach number of 0.70 and at two different angles of attack. Calculated blockage corrections show reasonable agreement with results based on Hackett's method. Corrected surface pressures compare favorably to free-air flow field data if the tunnel flow field is subsonic. The present wall interference correction method can be applied to transonic tunnel flow fields with some restrictions. Errors are estimated and it is shown that the expected error in calculating the pressure coefficient correction on the model surface is in the order of the error of pressure coefficient measurement on interfaces. Necessary testing equipment in existing tunnels can easily be modified if the present method is applied.

  16. Method for Correcting Control Surface Angle Measurements in Single Viewpoint Photogrammetry

    Science.gov (United States)

    Burner, Alpheus W. (Inventor); Barrows, Danny A. (Inventor)

    2006-01-01

    A method of determining a corrected control surface angle for use in single viewpoint photogrammetry to correct control surface angle measurements affected by wing bending. First and second visual targets are spaced apart &om one another on a control surface of an aircraft wing. The targets are positioned at a semispan distance along the aircraft wing. A reference target separation distance is determined using single viewpoint photogrammetry for a "wind off condition. An apparent target separation distance is then computed for "wind on." The difference between the reference and apparent target separation distances is minimized by recomputing the single viewpoint photogrammetric solution for incrementally changed values of target semispan distances. A final single viewpoint photogrammetric solution is then generated that uses the corrected semispan distance that produced the minimized difference between the reference and apparent target separation distances. The final single viewpoint photogrammetric solution set is used to determine the corrected control surface angle.

  17. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: -> Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. -> Deconvolution of the luminosity spectrum distortion due to the ISR emission. -> Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  18. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: - Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. - Deconvolution of the luminosity spectrum distortion due to the ISR emission. - Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  19. Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea

    Directory of Open Access Journals (Sweden)

    Ophélie Sagnol

    2014-01-01

    Full Text Available Determining the position of animals at sea can be particularly difficult and yet, accurate range and position of animals at sea are essential to answer a wide range of biological questions. Shore-based theodolite techniques have been used in a number of studies to examine marine mammal movement patterns and habitat use, offering reliable position measurements. In this study we explored the accuracy of theodolite measurements by comparing positional information of the same objects using two independent techniques: a shore-based theodolite station and an onboard GPS over a range of 25 km from the shore-based station. The technique was developed to study the habitat use of sperm whales (Physeter macrocephalus off Kaikoura, New Zealand. We observed that the position accuracy fell rapidly with an increase in range from the shore-based station. Results showed that the horizontal angle was accurately determined, but this was not the case for the vertical angle. We calibrated the position of objects at sea with a regression-based correction to fit the difference in distance between simultaneously recorded theodolite fixes and GPS positions. This approach revealed the necessity to calibrate theodolite measurements with objects at sea of known position.

  20. Corrections for measurements of tritium in subterranean vapor using silica gel.

    Science.gov (United States)

    Whicker, Jeffrey J; Dewart, Jean M; Allen, Shannon P; Eisele, William F; McNaughton, Michael W; Green, Andrew A

    2011-01-01

    Hazardous contaminants buried within vadose zones can accumulate in soil gas. The concentrations and spatial extent of these contaminants are measured to evaluate potential transport to groundwater for public risk evaluation. Tritium is an important contaminant found and monitored for in vadose zones across numerous sites within the US nuclear weapons complex, including Los Alamos National Laboratory. The extraction, collection, and laboratory analysis of tritium from subterranean soil gas presents numerous technical challenges that have not been fully studied. Particularly, the lack of moisture in the soil gas in the vadose zone makes it difficult to obtain enough sample (e.g., > 5 g) to provide for the required measurement sensitivity, and often, only small amounts of moisture can be collected. Further, although silica gel has high affinity for water vapor and is prebaked prior to sampling, there is still sufficient residual moisture in the prebaked gel to dilute the relatively small amount of sampled moisture; thereby, significantly lowering the "true" tritium concentration in the soil gas. This paper provides an evaluation of the magnitude of the bias from dilution, provides methods to correct past measurements by applying a correction factor (CF), and evaluates the uncertainty of the CF values. For this, 10,000 Monte Carlo calculations were performed, and distribution parameters of CF values were determined and evaluated. The mean and standard deviation of the distribution of CF values were 1.53 ± 0.36, and the minimum, median, and maximum values were 1.14, 1.43, and 5.27, respectively.

  1. Hypergol Maintenance Facility Hazardous Waste South Staging Areas, SWMU 070 Corrective Measures Implementation

    Science.gov (United States)

    Miller, Ralinda R.

    2016-01-01

    This document presents the Corrective Measures Implementation (CMI) Year 10 Annual Report for implementation of corrective measures at the Hypergol Maintenance Facility (HMF) Hazardous Waste South Staging Areas at Kennedy Space Center, Florida. The work is being performed by Tetra Tech, Inc., for the National Aeronautics and Space Administration (NASA) under Indefinite Delivery Indefinite Quantity (IDIQ) NNK12CA15B, Task Order (TO) 07. Mr. Harry Plaza, P.E., of NASA's Environmental Assurance Branch is the Remediation Project Manager for John F. Kennedy Space Center. The Tetra Tech Program Manager is Mr. Mark Speranza, P.E., and the Tetra Tech Project Manager is Robert Simcik, P.E.

  2. Correction of motion measurement errors beyond the range resolution of a synthetic aperture radar

    Science.gov (United States)

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2008-06-24

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  3. Rotor Wake Vortex Definition Using 3C-PIV Measurements: Corrected for Vortex Orientation

    Science.gov (United States)

    Burley, Casey L.; Brooks, Thomas F.; vanderWall, Berend; Richard, Hughues Richard; Raffel, Markus; Beaumier, Philippe; Delrieux, Yves; Lim, Joon W.; Yu, Yung H.; Tung, Chee

    2003-01-01

    Three-component (3-C) particle image velocimetry (PIV) measurements, within the wake across a rotor disk plane, are used to determine wake vortex definitions important for BVI (Blade Vortex Interaction) and broadband noise prediction. This study is part of the HART II test program conducted using a 40 percent scale BO-105 helicopter main rotor in the German-Dutch Wind Tunnel (DNW). In this paper, measurements are presented of the wake vortex field over the advancing side of the rotor operating at a typical descent landing condition. The orientations of the vortex (tube) axes are found to have non-zero tilt angles with respect to the chosen PIV measurement cut planes, often on the order of 45 degrees. Methods for determining the orientation of the vortex axis and reorienting the measured PIV velocity maps (by rotation/projection) are presented. One method utilizes the vortex core axial velocity component, the other utilizes the swirl velocity components. Key vortex parameters such as vortex core size, strength, and core velocity distribution characteristics are determined from the reoriented PIV velocity maps. The results are compared with those determined from velocity maps that are not corrected for orientation. Knowledge of magnitudes and directions of the vortex axial and swirl velocity components as a function of streamwise location provide a basis for insight into the vortex evolution.

  4. A method to correct sampling ghosts in historic near-infrared Fourier Transform Spectrometer (FTS measurements

    Directory of Open Access Journals (Sweden)

    S. Dohe

    2013-04-01

    Full Text Available The Total Carbon Column Observing Network (TCCON has been established to provide ground-based remote sensing measurements of the column-average dry air mole fractions of key greenhouse gases. To ensure the network wide consistency, biases between Fourier Transform spectrometers at different sites have to be well controlled. In this study we investigate a fundamental correction scheme for errors in the sampling of the interferogram. This is a two-step procedure in which the laser sampling error (LSE is quantified using a subset of suitable interferograms and then used to resample all the interferograms in the timeseries. Timeseries of measurements acquired at the TCCON sites Izaña and Lauder are used to demonstrate the method. At both sites the sampling error histories show changes in LSE due to instrument interventions. Estimated LSE are in good agreement with sampling errors inferred from lamp measurements of the ghost to parent ratio (Lauder. The LSE introduce retrieval biases which are minimised when the interferograms are resampled. The original timeseries of Xair and XCO2 at both sites show discrepancies of 0.2–0.5% due to changes in the LSE associated with instrument interventions or changes in the measurement sample rate. After resampling discrepancies are reduced to 0.1% at Lauder and 0.2% at Izaña. In the latter case, coincident changes in interferometer alignment may also contribute to the residual difference.

  5. Optics measurement and correction during beam acceleration in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-09-09

    To minimize operational complexities, setup of collisions in high energy circular colliders typically involves acceleration with near constant β-functions followed by application of strong focusing quadrupoles at the interaction points (IPs) for the final beta-squeeze. At the Relativistic Heavy Ion Collider (RHIC) beam acceleration and optics squeeze are performed simultaneously. In the past, beam optics correction at RHIC has taken place at injection and at final energy with some interpolation of corrections into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats which if corrected could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoidance of higher-order multipole fields sampled by particles within the bunch. In this report the methodology now operational at RHIC for beam optics corrections during acceleration with simultaneous beta-squeeze will be presented together with measurements which conclusively demonstrate the superior beam control. As a valuable by-product, the corrections have minimized the beta-beat at the profile monitors so reducing the dominant error in and providing more precise measurements of the evolution of the beam emittances during acceleration.

  6. Measurement and correction of variations in interstellar dispersion in high-precision pulsar timing

    CERN Document Server

    Keith, M J; Shannon, R M; Hobbs, G B; Manchester, R N; Bailes, M; Bhat, N D R; Burke-Spolaor, S; Champion, D J; Chaudhary, A; Hotan, A W; Khoo, J; Kocz, J; Oslowski, S; Ravi, V; Reynolds, J E; Sarkissian, J; van Straten, W; Yardley, D R B

    2012-01-01

    Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At a typical observing wavelength, this delay can vary by tens of microseconds on five-year time scales, far in excess of signals of interest to pulsar timing arrays, such as that induced by a gravitational-wave background. Measurement of these delay variations is not only crucial for the detection of such signals, but also provides an unparallelled measurement of the turbulent interstellar plasma at au scales. In this paper we demonstrate that without consideration of wavelength- independent red-noise, 'simple' algorithms to correct for interstellar dispersion can attenuate signals of interest to pulsar timing arrays. We present a robust method for this correction, which we validate through simulations, and apply it to observations from the Parkes Pulsar Timing Array. Correction for dispersion variations comes at a cost of increased band-limited white noise. We discuss scheduling to minimise this additi...

  7. Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms

    Directory of Open Access Journals (Sweden)

    M. Collaud Coen

    2010-04-01

    Full Text Available The aerosol light absorption coefficient is an essential parameter involved in atmospheric radiation budget calculations. The Aethalometer (AE has the great advantage of measuring the aerosol light absorption coefficient at several wavelengths, but the derived absorption coefficients are systematically too high when compared to reference methods. Up to now, four different correction algorithms of the AE absorption coefficients have been proposed by several authors. A new correction scheme based on these previously published methods has been developed, which accounts for the optical properties of the aerosol particles embedded in the filter. All the corrections have been tested on six datasets representing different aerosol types and loadings and include multi-wavelength AE and white-light AE. All the corrections have also been evaluated through comparison with a Multi-Angle Absorption Photometer (MAAP for four datasets lasting between 6 months and five years. The modification of the wavelength dependence by the different corrections is analyzed in detail. The performances and the limits of all AE corrections are determined and recommendations are given.

  8. Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms

    Science.gov (United States)

    Collaud Coen, M.; Weingartner, E.; Apituley, A.; Ceburnis, D.; Fierz-Schmidhauser, R.; Flentje, H.; Henzing, J. S.; Jennings, S. G.; Moerman, M.; Petzold, A.; Schmid, O.; Baltensperger, U.

    2010-04-01

    The aerosol light absorption coefficient is an essential parameter involved in atmospheric radiation budget calculations. The Aethalometer (AE) has the great advantage of measuring the aerosol light absorption coefficient at several wavelengths, but the derived absorption coefficients are systematically too high when compared to reference methods. Up to now, four different correction algorithms of the AE absorption coefficients have been proposed by several authors. A new correction scheme based on these previously published methods has been developed, which accounts for the optical properties of the aerosol particles embedded in the filter. All the corrections have been tested on six datasets representing different aerosol types and loadings and include multi-wavelength AE and white-light AE. All the corrections have also been evaluated through comparison with a Multi-Angle Absorption Photometer (MAAP) for four datasets lasting between 6 months and five years. The modification of the wavelength dependence by the different corrections is analyzed in detail. The performances and the limits of all AE corrections are determined and recommendations are given.

  9. Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms

    Directory of Open Access Journals (Sweden)

    M. Collaud Coen

    2009-07-01

    Full Text Available The aerosol light absorption coefficient is an essential parameter involved in atmospheric radiation budget calculations. The Aethalometer (AE has the great advantage of measuring the aerosol light absorption coefficient at several wavelengths, but the derived absorption coefficients are systematically too high when compared to reference methods. Up to now, four different correction algorithms of the AE absorption coefficients have been proposed by several authors. A new correction scheme based on these previously published methods has been developed, which accounts for the optical properties of the aerosol particles embedded in the filter. All the corrections have been tested on six datasets representing different aerosol types and loadings and include multi-wavelength AE and white-light AE. All the corrections have also been evaluated through comparison with a Multi-Angle Absorption Photometer (MAAP for four datasets lasting between 6 months and five years. The modification of the wavelength dependence by the different corrections is analyzed in detail. The performances and the limits of all AE corrections are determined and recommendations are given.

  10. Corrections for Measurements of Tritium in Subterranean Vapor using Silica Gel

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey [Los Alamos National Laboratory; Dewart, Jean M [Los Alamos National Laboratory; Allen, Shannon P [Los Alamos National Laboratory; Eisele, William F [Los Alamos National Laboratory; Mcnaughton, Michael C [Los Alamos National Laboratory; Green, Andrew A [Los Alamos National Laboratory

    2009-01-01

    Hazardous contaminants buried within vadose zones can accumulate in soil gas. The concentrations and spatial extent of these contaminants are measured to evaluate potential transport to ground water for public risk evaluation. Tritium is an important contaminant found in and monitored for in vadose zones across numerous sites within the United States nuclear weapons complex, including Los Alamos National Laboratory. The extraction, collection, and laboratory analysis of tritium from subterranean soil gas presents numerous technical challenges that have not been fully studied. Particularly, the lack of soil moisture in the soil gas in the vadose zone makes it difficult to obtain enough sample moisture (e.g., > 5 g) to provide for the required sensitivity, and often, only small amounts of moisture can be collected. Further, although silica gel has high affinity for water vapor and is prebaked prior to sampling, there is still sufficient residual moisture in the prebaked gel to dilute the relatively small amount of sampled moisture; thereby, significantly lowering the 'true' tritium concentration in the soil gas. This paper provides an evaluation of the magnitude of the bias from dilution, provides methods to correct past measurements by applying a correction factor (CF), and evaluates the uncertainty of the CF values. For this, ten-thousand Monte Carlo calculations were perfonned and distribution parameters of CF values were detennined and evaluated. The mean and standard deviation of the distribution of CF values were 1.53 {+-} 0.36, and the minimum, median, and maximum values were 1.14, 1.43, and 5.27, respectively.

  11. Correction factors to convert microdosimetry measurements in silicon to tissue in 12C ion therapy

    Science.gov (United States)

    Bolst, David; Guatelli, Susanna; Tran, Linh T.; Chartier, Lachlan; Lerch, Michael L. F.; Matsufuji, Naruhiro; Rosenfeld, Anatoly B.

    2017-03-01

    Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic 12C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length to calculate the lineal energy was introduced as an alternative to the mean chord length because it was found that adopting Cauchy’s formula for the was not appropriate for the radiation field typical of HIT as it is very directional. can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident 12C ion beam can be adopted as . The tissue equivalence conversion method and were adopted to determine the RBE10, calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of the determination of .

  12. Measurement, analysis and correction of the closed orbit distortion in Indus-2 synchrotron radiation source

    Indian Academy of Sciences (India)

    Riyasat Husain; A D Ghodke; Surendra Yadav; A C Holikatti; R P Yadav; P Fatnani; T A Puntambekar; P R Hannurkar

    2013-02-01

    The paper presents the measurement, analysis and correction of closed orbit distortion (COD) in Indus-2 at 550 MeV injection energy and 2 GeV synchrotron radiation user run energy. The measured COD was analysed and fitted to understand major sources of errors in terms of the effective quadrupole misalignments. The rms COD was corrected down to less than 0.6 mm in both horizontal and vertical planes. A golden orbit was set for the operating synchrotron radiation beamlines. With COD correction, the injection efficiency at 550 MeV was improved by ∼ 50% and the beam lifetime at 2 GeV was increased by ∼8 h. In this paper, the method of global COD correction based on singular value decomposition (SVD) of the orbit response matrix is described. Results for the COD correction in both horizontal and vertical planes at 550 MeV injection energy and at 2 GeV synchrotron radiation user run energy are discussed.

  13. A new measurement of the leading hadronic corrections to the muon g-2*

    Directory of Open Access Journals (Sweden)

    Trentadue Luca

    2016-01-01

    Full Text Available A novel approach to determine the leading hadronic corrections to the muon g-2 is proposed. It consists in a measurement of the effective electromagnetic coupling in the space-like region. This method may become feasible at flavor factories resulting in a determination potentially competitive with the dispersive approach via time-like data.

  14. Shading correction and calibration in bacterial fluorescence measurement by image processing system

    NARCIS (Netherlands)

    Wilkinson, M.H.F.

    1994-01-01

    An image processing system with applications in bacterial (immuno-)fluorescence measurement has been developed. To reach quantitative results, correction for non-uniformities in system sensitivity, both as a function of time (calibration for drifts) and as a function of image coordinates (shading co

  15. Shading correction and calibration in bacterial fluorescence measurement by image processing system

    NARCIS (Netherlands)

    Wilkinson, M.H.F.

    1994-01-01

    An image processing system with applications in bacterial (immuno-)fluorescence measurement has been developed. To reach quantitative results, correction for non-uniformities in system sensitivity, both as a function of time (calibration for drifts) and as a function of image coordinates (shading co

  16. 76 FR 65673 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures; Correction

    Science.gov (United States)

    2011-10-24

    ... Species; Atlantic Shark Management Measures; Correction AGENCY: National Marine Fisheries Service (NMFS... several Atlantic shark stocks and announced NMFS' intent to amend the 2006 Consolidated Highly Migratory Species (HMS) Fishery Management Plan (FMP) via the rulemaking process to rebuild these shark stocks...

  17. Terrain correction for gravity measurements, using a digital terrain model (DTM)

    NARCIS (Netherlands)

    Ketelaar, A.C.R.

    1987-01-01

    A single-term expression is given to calculate the gravitational effect for any square vertical prism with a sloping surface. A moderate measure of approximation is involved. The expression is well suited to automatic calculation of the terrain correction when a digital terrain model is available. T

  18. MEASUREMENT OF MOTION CORRECTED WIND VELOCITY USING AN AEROSTAT LOFTED SONIC ANEMOMETER

    Science.gov (United States)

    An aerostat-lofted, sonic anemometer was used to determine instantaneous 3 dimensional wind velocities at altitudes relevant to fire plume dispersion modeling. An integrated GPS, inertial measurement unit, and attitude heading and reference system corrected the wind data for th...

  19. Spatial Resolution Correction for Electrochemical Wall-shear Stress Measurements using Rectangular Sensors

    Directory of Open Access Journals (Sweden)

    Fethi Aloui

    2016-01-01

    Full Text Available This article is mainly motivated by the growing needs for highly resolved measurements for wall-bounded turbulent flows and aims to proposes a spatial correction coefficient in order to increase the wall-shear stress sensors accuracy. As it well known for the hot wire anemometry, the fluctuating streamwise velocity measurement attenuation is mainly due to the spatial resolution and the frequency response of the sensing element. The present work agrees well with this conclusion and expands it to the wall-shear stress fluctuations measurements using electrochemical sensors and suggested a correction method based on the spanwise correlation coefficient to take into account the spatial filtering effects on unresolved wall-shear stress measurements due to too large sensor spanwise size.

  20. Functions of diffraction correction and analytical solutions in nonlinear acoustic measurement

    CERN Document Server

    Alliès, Laurent; Nadi, M

    2008-01-01

    This paper presents an analytical formulation for correcting the diffraction associated to the second harmonic of an acoustic wave, more compact than that usually used. This new formulation, resulting from an approximation of the correction applied to fundamental, makes it possible to obtain simple solutions for the second harmonic of the average acoustic pressure, but sufficiently precise for measuring the parameter of nonlinearity B/A in a finite amplitude method. Comparison with other expressions requiring numerical integration, show the solutions are precise in the nearfield.

  1. Case Study: Learner Attitudes Towards the Correction of Mistakes

    OpenAIRE

    Galina Kavaliauskienė; Lilija Anusienė

    2013-01-01

    The objective of the research is to explore learner attitudes to correction of mistakes or feedback as a language learning tool in oral, electronically- and paper-written work as well as peer correction of mistakes. Feedback is a method used in the teaching of languages to improve performance by sharing observations, concerns and suggestions with regard to written work or oral presentation. It includes not only correcting learners, but also assessing them. Both correction and assessmen...

  2. Case Study: Learner Attitudes Towards the Correction of Mistakes

    OpenAIRE

    Galina Kavaliauskienė; Lilija Anusienė

    2012-01-01

    The objective of the research is to explore learner attitudes to correction of mistakes or feedback as a language learning tool in oral, electronically- and paper-written work as well as peer correction of mistakes.Feedback is a method used in the teaching of languages to improve performance by sharing observations, concerns and suggestions with regard to written work or oral presentation. It includes not only correcting learners, but also assessing them. Both correction and assessment depend...

  3. The association of long-term exposure to PM2.5 on all-cause mortality in the Nurses' Health Study and the impact of measurement-error correction.

    Science.gov (United States)

    Hart, Jaime E; Liao, Xiaomei; Hong, Biling; Puett, Robin C; Yanosky, Jeff D; Suh, Helen; Kioumourtzoglou, Marianthi-Anna; Spiegelman, Donna; Laden, Francine

    2015-05-01

    Long-term exposure to particulate matter less than 2.5 μm in diameter (PM2.5) has been consistently associated with risk of all-cause mortality. The methods used to assess exposure, such as area averages, nearest monitor values, land use regressions, and spatio-temporal models in these studies are subject to measurement error. However, to date, no study has attempted to incorporate adjustment for measurement error into a long-term study of the effects of air pollution on mortality. We followed 108,767 members of the Nurses' Health Study (NHS) 2000-2006 and identified all deaths. Biennial mailed questionnaires provided a detailed residential address history and updated information on potential confounders. Time-varying average PM2.5 in the previous 12-months was assigned based on residential address and was predicted from either spatio-temporal prediction models or as concentrations measured at the nearest USEPA monitor. Information on the relationships of personal exposure to PM2.5 of ambient origin with spatio-temporal predicted and nearest monitor PM2.5 was available from five previous validation studies. Time-varying Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95 percent confidence intervals (95%CI) for each 10 μg/m(3) increase in PM2.5. Risk-set regression calibration was used to adjust estimates for measurement error. Increasing exposure to PM2.5 was associated with an increased risk of mortality, and results were similar regardless of the method chosen for exposure assessment. Specifically, the multivariable adjusted HRs for each 10 μg/m(3) increase in 12-month average PM2.5 from spatio-temporal prediction models were 1.13 (95%CI:1.05, 1.22) and 1.12 (95%CI:1.05, 1.21) for concentrations at the nearest EPA monitoring location. Adjustment for measurement error increased the magnitude of the HRs 4-10% and led to wider CIs (HR = 1.18; 95%CI: 1.02, 1.36 for each 10 μg/m(3) increase in PM2.5 from the spatio-temporal models and

  4. A Planar-Dimensions Machine Vision Measurement Method Based on Lens Distortion Correction

    Directory of Open Access Journals (Sweden)

    Qiucheng Sun

    2013-01-01

    Full Text Available Lens distortion practically presents in a real optical imaging system causing nonuniform geometric distortion in the images and gives rise to additional errors in the vision measurement. In this paper, a planar-dimensions vision measurement method is proposed by improving camera calibration, in which the lens distortion is corrected on the pixel plane of image. The method can be divided into three steps: firstly, the feature points, only in the small central region of the image, are used to get a more accurate perspective projection model; secondly, rather than defining a uniform model, the smoothing spline function is used to describe the lens distortion in the measurement region of image, and two correction functions can be obtained by fitting two deviation surfaces; finally, a measurement method for planar dimensions is proposed, in which accurate magnification factor of imaging system can be obtained by using the correction functions. The effectiveness of the method is demonstrated by applying the proposed method to the test of measuring shaft diameter. Experimental data prove that the accurate planar-dimensions measurements can be performed using the proposed method even if images are deformed by lens distortion.

  5. Correction for partial reflection in ultrasonic attenuation measurements using contact transducers.

    Science.gov (United States)

    Treiber, Martin; Kim, Jin-Yeon; Jacobs, Laurence J; Qu, Jianmin

    2009-05-01

    This research investigates the influence of partial reflection on the measurement of the absolute ultrasonic attenuation coefficient using contact transducers. The partial, frequency-dependent reflection arises from the thin fluid-layer interface formed between the transducer and specimen surface. It is experimentally shown that neglecting this reflection effect leads to a significant overestimation in the measured attenuation coefficient. A systematic measurement procedure is proposed that simultaneously obtains the ultrasonic signals needed to calculate both the reflection coefficient of the interface and the attenuation coefficient, without disturbing the existing coupling conditions. The true attenuation coefficient includes a correction based on the measured reflection coefficient--this is called the reflection correction. It is shown that including the reflection correction also reduces the variation (random error) in the measured attenuation coefficient. The accuracy of the proposed method is demonstrated for a material with a known attenuation coefficient. The proposed method is then used to measure the high attenuation coefficient of a cement-based material.

  6. Accounting for vegetation height and wind direction to correct eddy covariance measurements of energy fluxes over hilly crop fields

    Science.gov (United States)

    Zitouna-Chebbi, Rim; Prévot, Laurent; Jacob, Frédéric; Voltz, Marc

    2015-05-01

    As agricultural hilly watersheds are widespread throughout the world, there is a strong need for reliable estimates of land surface fluxes, especially evapotranspiration, over crop fields on hilly slopes. In order to obtain reliable estimates from eddy covariance (EC) measurements in such conditions, the current study aimed at proposing adequate planar fit tilt corrections that account for the combined effects of topography, wind direction, and vegetation height on airflow inclinations. EC measurements were collected within an agricultural hilly watershed in northeastern Tunisia, throughout the growth cycles of cereals, legumes, and pasture. The wind had two dominant directions that induced upslope and downslope winds. For upslope winds, the airflows were parallel to the slopes and slightly came closer to the horizontal plane when vegetation grew. For downslope winds, over fields located in the lee of the rim top, the airflows were almost horizontal over bare soil and came closer to the topographical slope when vegetation grew. We therefore adjusted the planar fit tilt correction on EC measurements according to vegetation height and by discriminating between upslope and downslope winds. This adjusted tilt correction improved the energy balance closure in most cases, and the obtained energy balance closures were similar to that reported in the literature for flat conditions. We conclude that EC data collected within crop fields on hilly slopes can be used for monitoring land surface fluxes, provided planar fit tilt corrections are applied in an appropriate manner.

  7. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional

  8. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    Directory of Open Access Journals (Sweden)

    N. Hanrieder

    2015-05-01

    Full Text Available Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR. The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP, a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC procedure

  9. Customized schematic eye model for refraction correction design based on ocular wavefront and corneal topography measurements

    Science.gov (United States)

    Curatu, Eugene O.; Pettit, George H.; Campin, John A.

    2002-06-01

    The subject of this paper relates to the ocular optical design and vision analysis of refractive correction of the eye. After the purpose statement and the assumption list, the concept of the schematic eye matching a particular (measured) wavefront is introduced. This concept is based on the fact that the ocular wavefront, together with the corneal topography, can be seen as the mathematical global representation of the eye working in monochromatic light and having a foveal vision. The discussed design technique, including an iterative optimization method, could be applied in any ocular correction that utilizes cornea topography and/or ocular wavefront, e.g. contact lens or intra-corneal implant. However, the application this paper refers to is the ocular refractive correction by a procedure using the LADARVISION. It consists of surgical removal and subsequent replacement of a corneal flap on a stromal surface whose shape has been changed by laser ablation of the tissue. Subsequent sections of this paper are dedicated to establishing the limits of possible refractive correction, the influences of the flap and corneal topography into the refractive correction calculation. Finally a realistic evaluation of the results and a list of possible developments of this new optical design method are discussed.

  10. A measuring and correcting method about locus errors in robot welding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    When tubules regularly arranged are welded onto a bobbin by robot, the position and orientation of some tubules may be changed by such factors as thermal deformations and positioning errors etc. Which make it very difficult to weld automatically and continuously by the method of teaching and playing. In this paper, a kind of error measuring system is presented. By which the position and orientation errors of tubules relative to the teaching one can be measured. And, a method to correct the locus errors is also proposed, by which the moving locus planned via teaching points can be corrected in real time according to measured error parameters. So that, just by teaching one, all tubules on a bobbin could be welded automatically.

  11. Analysis and Correction of Diffraction Effect on the B/A Measurement at High Frequencies

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dong(章东); GONG Xiu-Fen(龚秀芬); LIU Xiao-Zhou(刘晓宙); KUSHIBIKI Jun-ichi; NISHINO Hideo

    2004-01-01

    A numerical method is developed to analyse and to correct the diffraction effect in the measurement of acoustic nonlinearity parameter B/A at high frequencies. By using the KZK nonlinear equation and the superposition approach of Gaussian beams, an analytical model is derived to describe the second harmonic generation through multi-layer medium SiO2/liquid specimen/SiO2. Frequency dependence of the nonlinear characterization curve for water in 110-155 MHz is numerically and experimentally investigated. With the measured dip position and the new model, values of B/A for water are evaluated. The results show that the present method can effectively correct the diffraction effect in the measurement.

  12. Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Younkin, K; Long, CN

    2003-11-01

    Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

  13. Errors in Thermographic Camera Measurement Caused by Known Heat Sources and Depth Based Correction

    Directory of Open Access Journals (Sweden)

    Mark Christian E. Manuel

    2016-03-01

    Full Text Available Thermal imaging has shown to be a better tool for the quantitative measurement of temperature than single spot infrared thermometers. However, thermographic cameras can encounter errors in acquiring accurate temperature measurements in the presence of other environmental heat sources. Some of these errors arise due to the inability of the thermal camera to detect objects and features in the infrared domain. In this paper, the thermal image is registered as a stereo image from a Kinect system prior to depth-based correction. Experiments demonstrating the error are presented together with the determination of the measurement errors under prior knowledge of the thermographed scene. The proposed correction scheme improves the accuracy of the thermal image through augmentation using the Kinect system.

  14. Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

    Science.gov (United States)

    Weigel, Ralf; Spichtinger, Peter; Mahnke, Christoph; Klingebiel, Marcus; Afchine, Armin; Petzold, Andreas; Krämer, Martina; Costa, Anja; Molleker, Sergej; Reutter, Philipp; Szakáll, Miklós; Port, Max; Grulich, Lucas; Jurkat, Tina; Minikin, Andreas; Borrmann, Stephan

    2016-10-01

    Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO - High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s-1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO

  15. Optics measurements and corrections at the early commissioning of SuperKEKB

    CERN Document Server

    Ohnishi, Y; Morita, A; Koiso, H; Oide, K; Ohmi, K; Zhou, D; Funakoshi, Y; Carmignani, N; Liuzzo, S M; Biagini, M E; Boscolo, M; Guiducci, S

    2017-01-01

    We present experimental results of measurements and corrections for the optics at the early Phase-1 commissioning of SuperKEKB. The aim of SuperKEKB is a positron-electron collider built to achieve the target luminosity of 8x10^35 cm^−2s^−1. We have three stages; Phase-1 is the commissioning of the machine without the final focus magnets and detector solenoid(no collision); the collision with the final focus system and the Belle II detector will be performed at Phase-2 and Phase-3. The strategy for the luminosity upgrade is a novel "nano-beam” scheme found elsewhere[1]. In order to achieve the target luminosity, the vertical emittance has to be reduced by corrections of machine error measured with an orbit response. The vertical emittance should be achieved to be less than 10pm(∼0.2% coupling) during Phase-1 by fully utilizing correction tools of skew quadrupole-likecoils wound on sextupole magnets and power supplies for each correction coil in quadrupole magnets.

  16. Correction of magnetotelluric static shift by analysis of 3D forward modelling and measured test data

    Science.gov (United States)

    Zhang, Kun; Wei, Wenbo; Lu, Qingtian; Wang, Huafeng; Zhang, Yawei

    2016-06-01

    To solve the problem of correction of magnetotelluric (MT) static shift, we quantise factors that influence geological environments and observation conditions and study MT static shift according to 3D MT numerical forward modelling and field tests with real data collection. We find that static shift distortions affect both the apparent resistivity and the impedance phase. The distortion results are also related to the frequency. On the basis of synthetic and real data analysis, we propose the concept of generalised static shift resistivity (GSSR) and a new method for correcting MT static shift. The approach is verified by studying 2D inversion models using synthetic and real data.

  17. The performance of functional methods for correcting non-Gaussian measurement error within Poisson regression: corrected excess risk of lung cancer mortality in relation to radon exposure among French uranium miners.

    Science.gov (United States)

    Allodji, Rodrigue S; Thiébaut, Anne C M; Leuraud, Klervi; Rage, Estelle; Henry, Stéphane; Laurier, Dominique; Bénichou, Jacques

    2012-12-30

    A broad variety of methods for measurement error (ME) correction have been developed, but these methods have rarely been applied possibly because their ability to correct ME is poorly understood. We carried out a simulation study to assess the performance of three error-correction methods: two variants of regression calibration (the substitution method and the estimation calibration method) and the simulation extrapolation (SIMEX) method. Features of the simulated cohorts were borrowed from the French Uranium Miners' Cohort in which exposure to radon had been documented from 1946 to 1999. In the absence of ME correction, we observed a severe attenuation of the true effect of radon exposure, with a negative relative bias of the order of 60% on the excess relative risk of lung cancer death. In the main scenario considered, that is, when ME characteristics previously determined as most plausible from the French Uranium Miners' Cohort were used both to generate exposure data and to correct for ME at the analysis stage, all three error-correction methods showed a noticeable but partial reduction of the attenuation bias, with a slight advantage for the SIMEX method. However, the performance of the three correction methods highly depended on the accurate determination of the characteristics of ME. In particular, we encountered severe overestimation in some scenarios with the SIMEX method, and we observed lack of correction with the three methods in some other scenarios. For illustration, we also applied and compared the proposed methods on the real data set from the French Uranium Miners' Cohort study.

  18. Numerical correction of the phase error due to electromagnetic coupling effects in 1D EIT borehole measurements

    Science.gov (United States)

    Zhao, Y.; Zimmermann, E.; Huisman, J. A.; Treichel, A.; Wolters, B.; van Waasen, S.; Kemna, A.

    2012-12-01

    Spectral Electrical Impedance Tomography (EIT) allows obtaining images of the complex electrical conductivity for a broad frequency range (mHz to kHz). It has recently received increased interest in the field of near-surface geophysics and hydrogeophysics because of the relationships between complex electrical properties and hydrogeological and biogeochemical properties and processes observed in the laboratory with Spectral Induced Polarization (SIP). However, these laboratory results have also indicated that a high phase accuracy is required for surface and borehole EIT measurements because many soils and sediments are only weakly polarizable and show phase angles between 1 and 20 mrad. In the case of borehole EIT measurements, long cables and electrode chains (>10 meters) are typically used, which leads to undesired inductive coupling between the electric loops for current injection and potential measurement and capacitive coupling between the electrically conductive cable shielding and the soil. Depending on the electrical properties of the subsurface and the measured transfer impedances, both coupling effects can cause large phase errors that have typically limited the frequency bandwidth of field EIT measurement to the mHz to Hz range. The aim of this study is i) to develop correction procedures for these coupling effects to extend the applicability of EIT to the kHz range and ii) to validate these corrections using controlled laboratory measurements and field measurements. In order to do so, the inductive coupling effect was modeled using electronic circuit models and the capacitive coupling effect was modeled by integrating discrete capacitances in the electrical forward model describing the EIT measurement process. The correction methods were successfully verified with measurements under controlled conditions in a water-filled rain barrel, where a high phase accuracy of 2 mrad in the frequency range up to 10 kHz was achieved. In a field demonstration using

  19. First measurement and correction of nonlinear errors in the experimental insertions of the CERN Large Hadron Collider

    Science.gov (United States)

    Maclean, E. H.; Tomás, R.; Giovannozzi, M.; Persson, T. H. B.

    2015-12-01

    Nonlinear magnetic errors in low-β insertions can contribute significantly to detuning with amplitude, linear and nonlinear chromaticity, and lead to degradation of dynamic aperture and beam lifetime. As such, the correction of nonlinear errors in the experimental insertions of colliders can be of critical significance for successful operation. This is expected to be of particular relevance to the LHC's second run and its high luminosity upgrade, as well as to future colliders such as the Future Circular Collider. Current correction strategies envisioned for these colliders assume it will be possible to calculate optimized local corrections through the insertions, using a magnetic model of the errors. This paper shows however, that reliance purely upon magnetic measurements of the nonlinear errors of insertion elements is insufficient to guarantee a good correction quality in the relevant low-β* regime. It is possible to perform beam-based examination of nonlinear magnetic errors via the feed-down to readily observed beam properties upon application of closed orbit bumps, and methods based upon feed-down to tune have been utilized at RHIC, SIS18, and SPS. This paper demonstrates the extension of such methodology to include direct observation of feed-down to linear coupling in the LHC. It is further shown that such beam-based studies can be used to complement magnetic measurements performed during LHC construction, in order to validate and refine the magnetic model of the collider. Results from first attempts of the measurement and correction of nonlinear errors in the LHC experimental insertions are presented. Several discrepancies of beam-based studies with respect to the LHC magnetic model are reported.

  20. Correcting acoustic Doppler current profiler discharge measurements biased by sediment transport

    Science.gov (United States)

    Mueller, D.S.; Wagner, C.R.

    2007-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) is attributed to the movement of sediment on or near the streambed, and is an issue widely acknowledged by the scientific community. The integration of a differentially corrected global positioning system (DGPS) to track the movement of the ADCP can be used to avoid the systematic bias associated with a moving bed. DGPS, however, cannot provide consistently accurate positions because of multipath errors and satellite signal reception problems on waterways with dense tree canopy along the banks, in deep valleys or canyons, and near bridges. An alternative method of correcting for the moving-bed bias, based on the closure error resulting from a two-way crossing of the river, is presented. The uncertainty in the mean moving-bed velocity measured by the loop method is shown to be approximately 0.6cm/s. For the 13 field measurements presented, the loop method resulted in corrected discharges that were within 5% of discharges measured utilizing DGPS to compensate for moving-bed conditions. ?? 2007 ASCE.

  1. Position error correction in absolute surface measurement based on a multi-angle averaging method

    Science.gov (United States)

    Wang, Weibo; Wu, Biwei; Liu, Pengfei; Liu, Jian; Tan, Jiubin

    2017-04-01

    We present a method for position error correction in absolute surface measurement based on a multi-angle averaging method. Differences in shear rotation measurements at overlapping areas can be used to estimate the unknown relative position errors of the measurements. The model and the solving of the estimation algorithm have been discussed in detail. The estimation algorithm adopts a least-squares technique to eliminate azimuthal errors caused by rotation inaccuracy. The cost functions can be minimized to determine the true values of the unknowns of Zernike polynomial coefficients and rotation angle. Experimental results show the validity of the method proposed.

  2. Longitudinal changes in heart rate-corrected measures of exercise performance in children.

    Science.gov (United States)

    Chintala, Kavitha; Epstein, Michael L; Singh, Tajinder P

    2008-01-01

    Interpretation of change in exercise performance over time in children with repaired congenital heart disease is often hampered by poor effort that limits the maximum heart rate; this is often difficult to distinguish from chronotropic impairment, a common finding in these children. In an attempt to address this limitation, we sought to examine measures of exercise performance that are corrected for heart rate in healthy children and to determine if these change with somatic growth. We studied two serial graded exercise tests in 24 healthy children at an interval of >3 years. Paired comparisons revealed that maximum oxygen pulse (O(2) pulse), O(2) pulse at ventilatory anaerobic threshold, O(2) pulse at a heart rate of 140 beats per minute, and slope of the VO(2)-heart rate relationship all increased with age. However, when indexed to somatic growth, there was no change in the mean values of these parameters over time. We conclude that O(2 )pulse and slope of the VO(2)-heart rate relationship during exercise increase in proportion to somatic growth in children so that optimal oxygen delivery to the exercising muscles is ensured. This study provides the "normative" response of exercise parameters to growth, against which responses of children with repaired congenital heart disease may be compared.

  3. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Directory of Open Access Journals (Sweden)

    N. Hanrieder

    2015-08-01

    Full Text Available Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR. The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP, a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC procedure

  4. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional

  5. Sound velocity measurement methods for porous sandstone. Measurements, finite element modelling, and diffraction correction

    CERN Document Server

    Sæther, Mathias; Ersland, Geir

    2016-01-01

    Acoustic material parameters of gas hydrate bearing porous rocks are important for evaluation of methods to exploit the vast methane gas resources present in the earth's subsurface, potentially combined with CO2 injection. A solid buffer method for measuring changes of the compressional wave velocity in porous rocks with changing methane hydrate contents under high-pressure hydrate-forming conditions, is tested and evaluated with respect to effects influencing on the measurement accuracy. The limited space available in the pressure chamber represents a challenge for the measurement method. Several effects affect the measured compressional wave velocity, such as interference from sidewall reflections, diffraction effects, the amount of torque (force) used to achieve acoustic coupling, and water draining of the watersaturated rock specimen. Test measurements using the solid buffer method in the pressure chamber at atmospheric conditions are compared to independent measurements using a water-bath immersion measu...

  6. Prospects for the LHC optics measurements and corrections at higher energy

    CERN Document Server

    Tomas, R; Coello, J; Kain, V; Kuhn, M; Langner, A S; Levinsen, Y I; Li, K S B; Maclean, E H; Maier, V; Magnin, N; McAteer, MJ; Persson, T H B; Skowronski, P; Westenberger, R; White, S

    2014-01-01

    LHC will resume operation in 2015 at 6.5 TeV. The higher energy allows for smaller IP beta functions, further enhancing the optics errors in the triplet quadrupoles. Moreover the uncertainty in the calibration of some quadrupoles will slightly increase due to saturation effects. The complete magnetic cycle of the LHC will take longer due to the higher energy and extended squeeze sequence. All these issues require more precise and more efficient optics measurements and corrections to guarantee the same optics quality level as in 2012 when a 7% peak beta-beating was achieved. This paper summarizes the on-going efforts for achieving faster and more accurate optics measurements and corrections.

  7. A new measurement of the leading hadronic corrections to the muon g-2

    Science.gov (United States)

    Trentadue, Luca

    2016-11-01

    A novel approach to determine the leading hadronic corrections to the muon g-2 is proposed. It consists in a measurement of the effective electromagnetic coupling in the space-like region. This method may become feasible at flavor factories resulting in a determination potentially competitive with the dispersive approach via time-like data. This talk is based on a work done in collaboration with C. Carloni Calame, M. Passera, and G. Venanzoni.

  8. Consolidating the Bilingual Education in the Major of Finance:Existing Defects and Corrective Measures

    Institute of Scientific and Technical Information of China (English)

    毛蓓蓓

    2013-01-01

    Under the trend of globalization and international financial integration, Chinese scholars have argued that executing bi-lingual education in the major of finance is necessary to advance the comprehensive quality and competitive ability of college stu-dents. However, universities attempting to implement bilingual education are procrastinated with many obstacles. To resolve this issue, corrective measures are to be given in the aspects of textbook publishing, professor training and curriculum adjustments.

  9. Measurement of the $B^-$ lifetime using a simulation free approach for trigger bias correction

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

    2010-04-01

    The collection of a large number of B hadron decays to hadronic final states at the CDF II detector is possible due to the presence of a trigger that selects events based on track impact parameters. However, the nature of the selection requirements of the trigger introduces a large bias in the observed proper decay time distribution. A lifetime measurement must correct for this bias and the conventional approach has been to use a Monte Carlo simulation. The leading sources of systematic uncertainty in the conventional approach are due to differences between the data and the Monte Carlo simulation. In this paper they present an analytic method for bias correction without using simulation, thereby removing any uncertainty between data and simulation. This method is presented in the form of a measurement of the lifetime of the B{sup -} using the mode B{sup -} {yields} D{sup 0}{pi}{sup -}. The B{sup -} lifetime is measured as {tau}{sub B{sup -}} = 1.663 {+-} 0.023 {+-} 0.015 ps, where the first uncertainty is statistical and the second systematic. This new method results in a smaller systematic uncertainty in comparison to methods that use simulation to correct for the trigger bias.

  10. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    Science.gov (United States)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  11. Analysis of the PKT correction for direct CO2 flux measurements over the ocean

    Directory of Open Access Journals (Sweden)

    S. Landwehr

    2013-10-01

    Full Text Available Eddy covariance measurements of air–sea CO2 fluxes can be affected by cross-sensitivities of the CO2 measurement to water vapour, resulting in order-of-magnitude biases. Well established causes for these biases are (i cross-sensitivity of the broadband non-dispersive infrared sensors due to band-broadening and spectral overlap (commercial sensors typically correct for this and (ii the effect of air density fluctuations (removed by determining the CO2 mixing ratio respective to dry air. However, another bias related to water vapour fluctuations has recently been observed with open-path sensors, and was attributed to sea salt build-up and water films on sensor optics. Two very different approaches have been used to deal with these water vapour-related biases. Miller et al. (2010 employed a membrane drier to physically eliminate 97% of the water vapour fluctuations in the sample air before it enters the gas analyser. Prytherch et al. (2010a on the other hand, employed the empirical (Peter K. Taylor, PKT post-processing correction to correct open-path sensor data. In this paper, we test these methods side by side using data from the Surface Ocean Aerosol Production (SOAP experiment in the Southern Ocean. The air–sea CO2 flux was directly measured with four closed-path analysers, two of which were positioned down-stream of a membrane dryer. The CO2 fluxes from the two dried gas analysers matched each other and were in general agreement with common parametrisations. The flux estimates from the un-dried sensors agreed with the dried sensors only during periods with low latent heat flux (≤ 7 W m−2. When latent heat flux was higher, CO2 flux estimates from the un-dried sensors exhibited large scatter and an order-of magnitude bias. We applied the PKT correction to the flux data from the un-dried analysers and found that it did not remove the bias when compared to the data from the dried gas analyser. Our detailed analysis of the correction

  12. Status of corrective measures technology for shallow land burial at arid sites

    Science.gov (United States)

    Abeele, W. V.; Nyhan, J. W.; Drennon, B. J.; Lopez, E. A.; Herrera, W. J.; Langhorst, G. J.

    The field research program involving corrective measure technologies for arid shallow land burial sites is described. Soil erosion and infiltration of water into a simulated trench cap with various surface treatments was measured and compared with similar data from agricultural systems across the United States. Report of field testing of biointrusion barriers continues at a closed-out waste disposal site at Los Alamos. Final results of an experiment designed to determine the effects of subsidence on the performance of a cobble-gravel biobarrier system are reported, as well as the results of hydrologic modeling activities involving biobarrier systems.

  13. Direct emissivity measurements on liquids and corrections to multi-color pyrometers

    Science.gov (United States)

    Nordine, Paul C.; Schiffman, Robert A.

    1988-01-01

    Optical pyrometry provides a means for non-contact temperature measurements whose accuracy depends on the accuracy with which specimen emittance is known. Two methods for obtaining the required emittance data are discussed in which the emittance is determined from measurements of the wavelength or polarization dependence of light emitted by the specimen. The spectral technique, multi-color pyrometry, yields apparent values for specimen emittance and temperature from emitted intensity measurements at two or more wavelengths. Emittance corrections cannot be eliminated by increasing the number of spectral intensity measurements required by an n-color pyrometer. Even if this were possible, the accuracy of temperature measurements by n-color pyrometry decreases with n such that pyrometers that require four intensity measurements would be impractical. In contrast, emittance values and corrections for one-color pyrometers can be accurately measured by the polarized light technique. The polarized light technique involves measurement of the degree of polarization for light emitted at an angle of 45 deg to the specimen normal. The reflectivities (r) for light polarized parallel (p) and normal (n) to the plane of emission are related by r(p) = r(n) squared. This leads to a simple relation between the intensity ratio for light emitted in the two polarized states and the emittance, i.e., e(n) = 2 - I(p)/I(n). The true specimen temperature is also obtained if absolute intensities are measured. Delvelopment of the polarized light technique in combination with one-color optical pyrometry is recommended to achieve accurate non-contact temperature measurements on liquids.

  14. Region of Interest Correction Factors Improve Reliability of Diffusion Imaging Measures Within and Across Scanners and Field Strengths

    Science.gov (United States)

    Venkatraman, Vijay K; Gonzalez, Christopher E.; Landman, Bennett; Goh, Joshua; Reiter, David A.; An, Yang; Resnick, Susan M.

    2017-01-01

    Diffusion tensor imaging (DTI) measures are commonly used as imaging markers to investigate individual differences in relation to behavioral and health-related characteristics. However, the ability to detect reliable associations in cross-sectional or longitudinal studies is limited by the reliability of the diffusion measures. Several studies have examined reliability of diffusion measures within (i.e. intra-site) and across (i.e. inter-site) scanners with mixed results. Our study compares the test-retest reliability of diffusion measures within and across scanners and field strengths in cognitively normal older adults with a follow-up interval less than 2.25 years. Intra-class correlation (ICC) and coefficient of variation (CoV) of fractional anisotropy (FA) and mean diffusivity (MD) were evaluated in sixteen white matter and twenty-six gray matter bilateral regions. The ICC for intra-site reliability (0.32 to 0.96 for FA and 0.18 to 0.95 for MD in white matter regions; 0.27 to 0.89 for MD and 0.03 to 0.79 for FA in gray matter regions) and inter-site reliability (0.28 to 0.95 for FA in white matter regions, 0.02 to 0.86 for MD in gray matter regions) with longer follow-up intervals were similar to earlier studies using shorter follow-up intervals. The reliability of across field strengths comparisons was lower than intra- and inter-site reliability. Within and across scanner comparisons showed that diffusion measures were more stable in larger white matter regions (> 1500 mm3). For gray matter regions, the MD measure showed stability in specific regions and was not dependent on region size. Linear correction factor estimated from cross-sectional or longitudinal data improved the reliability across field strengths. Our findings indicate that investigations relating diffusion measures to external variables must consider variable reliability across the distinct regions of interest and that correction factors can be used to improve consistency of measurement across

  15. Ground based measurements on reflectance towards validating atmospheric correction algorithms on IRS-P6 AWiFS data

    Science.gov (United States)

    Rani Sharma, Anu; Kharol, Shailesh Kumar; Kvs, Badarinath; Roy, P. S.

    In Earth observation, the atmosphere has a non-negligible influence on the visible and infrared radiation which is strong enough to modify the reflected electromagnetic signal and at-target reflectance. Scattering of solar irradiance by atmospheric molecules and aerosol generates path radiance, which increases the apparent surface reflectance over dark surfaces while absorption by aerosols and other molecules in the atmosphere causes loss of brightness to the scene, as recorded by the satellite sensor. In order to derive precise surface reflectance from satellite image data, it is indispensable to apply the atmospheric correction which serves to remove the effects of molecular and aerosol scattering. In the present study, we have implemented a fast atmospheric correction algorithm to IRS-P6 AWiFS satellite data which can effectively retrieve surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code, which is used to generate look-up-tables (LUTs). The algorithm requires information on aerosol optical depth for correcting the satellite dataset. The proposed method is simple and easy to implement for estimating surface reflectance from the at sensor recorded signal, on a per pixel basis. The atmospheric correction algorithm has been tested for different IRS-P6 AWiFS False color composites (FCC) covering the ICRISAT Farm, Patancheru, Hyderabad, India under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e., Red soil, Chick Pea crop, Groundnut crop and Pigeon Pea crop were conducted to validate the algorithm and found a very good match between surface reflectance and atmospherically corrected reflectance for all spectral bands. Further, we aggregated all datasets together and compared the retrieved AWiFS reflectance with

  16. Corrections for underresolved scalar measurements in turbulent flows using a DNS database

    Science.gov (United States)

    Burattini, Paolo; Kinet, Maxime; Carati, Daniele; Knaepen, Bernard

    2007-07-01

    We estimate the effect of finite spatial resolution of a probe for scalar measurements, using a database from direct numerical simulations (DNS). These are for homogeneous isotropic turbulence in temporal decay, Schmidt number unity, and low Taylor-microscale Reynolds number (≃27 42). The probe could be a cold wire for measuring temperature in a turbulent flow. Correction factors for the scalar variance, scalar dissipation rate, and mixed velocity-scalar derivative skewness are estimated, for a sensor length up to 15 times the Batchelor length scale. It is shown that the lack of resolution yields the largest attenuation on the dissipation rate, followed by the scalar variance. On the contrary, the mixed skewness, which is affected the least, is overestimated. Further, it is shown that if one estimates the mixed skewness via the scalar variance dynamical equation and neglects the term involving the time derivative of the scalar energy spectrum, large errors in the correction factor of the mixed skewness are introduced. Finally, it is found that correction factors obtained assuming Kraichnan scalar model spectrum and following Wyngaard (in Phys Fluids 14:2052 2054, 1971) approach are close to those from the DNS.

  17. Precise measurement and calculation of coincidence summing corrections for point and linear sources.

    Science.gov (United States)

    Sima, Octavian; Arnold, Dirk

    2012-09-01

    Point sources of (60)Co, (133)Ba, (134)Cs and (152)Eu, calibrated at Physikalisch-Technische Bundesanstalt were measured in 13 positions on the axis of a 50% relative efficiency p-type detector. The peak and total efficiencies were calibrated using single photon emitting nuclides. Precise experimental values of the coincidence summing corrections were evaluated in each geometry. Synthetic linear source data, as well as the corresponding peak and total efficiency curves, were prepared using the dependence of the count rates on the position of the emitting point. The coincidence summing corrections for the linear sources were computed, analyzed with respect to different approximations and compared with simulations carried out with GESPECOR. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Tijeras Arroyo Groundwater Current Conceptual Model and Corrective Measures Evaluation Report - December 2016.

    Energy Technology Data Exchange (ETDEWEB)

    Copland, John R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-03-01

    This Tijeras Arroyo Groundwater Current Conceptual Model and Corrective Measures Evaluation Report (CCM/CME Report) has been prepared by the U.S. Department of Energy (DOE) and Sandia Corporation (Sandia) to meet requirements under the Sandia National Laboratories-New Mexico (SNL/NM) Compliance Order on Consent (the Consent Order). The Consent Order, entered into by the New Mexico Environment Department (NMED), DOE, and Sandia, became effective on April 29, 2004. The Consent Order identified the Tijeras Arroyo Groundwater (TAG) Area of Concern (AOC) as an area of groundwater contamination requiring further characterization and corrective action. This report presents an updated Conceptual Site Model (CSM) of the TAG AOC that describes the contaminant release sites, the geological and hydrogeological setting, and the distribution and migration of contaminants in the subsurface. The dataset used for this report includes the analytical results from groundwater samples collected through December 2015.

  19. Study on the vehicle license plate tilt correction

    Institute of Scientific and Technical Information of China (English)

    Li Guihui; Li Yuanjin; Li Lanyou

    2006-01-01

    The shortage of current different approaches of the vehicle license plate(VLP) tilt correction is analyzed in the paper and a new rotary correction method put forward based on the former ways of the VLP tilt correction in the horizontal direction and the vertical direction Owing to the VLP tilt taking place in the vertical direction, the array of the image's pixels of the same column is broken, and even different rows come into being superposition.The VLP tilt taking place in the horizontal direction, by which the array of the image's pixels of the same row broken, and so much as different columns come into being superposition.

  20. Application of distance correction to ChemCam laser-induced breakdown spectroscopy measurements

    Science.gov (United States)

    Mezzacappa, A.; Melikechi, N.; Cousin, A.; Wiens, R. C.; Lasue, J.; Clegg, S. M.; Tokar, R.; Bender, S.; Lanza, N. L.; Maurice, S.; Berger, G.; Forni, O.; Gasnault, O.; Dyar, M. D.; Boucher, T.; Lewin, E.; Fabre, C.

    2016-06-01

    Laser-induced breakdown spectroscopy (LIBS) provides chemical information from atomic, ionic, and molecular emissions from which geochemical composition can be deciphered. Analysis of LIBS spectra in cases where targets are observed at different distances, as is the case for the ChemCam instrument on the Mars rover Curiosity, which performs analyses at distances between 2 and 7.4 m is not a simple task. In our previous work we showed that spectral distance correction based on a proxy spectroscopic standard created from first-shot dust observations on Mars targets ameliorates the distance bias in multivariate-based elemental-composition predictions of laboratory data. In this work, we correct an expanded set of neutral and ionic spectral emissions for distance bias in the ChemCam data set. By using and testing different selection criteria to generate multiple proxy standards, we find a correction that minimizes the difference in spectral intensity measured at two different distances and increases spectral reproducibility. When the quantitative performance of distance correction is assessed, there is improvement for SiO2, Al2O3, CaO, FeOT, Na2O, K2O, that is, for most of the major rock forming elements, and for the total major-element weight percent predicted. However, for MgO the method does not provide improvements while for TiO2, it yields inconsistent results. In addition, we have observed that many emission lines do not behave consistently with distance, evidenced from laboratory analogue measurements and ChemCam data. This limits the effectiveness of the method.

  1. The impact of temporal aggregation of solid precipitation measurements on the correction for wind-induced undercatch.

    Science.gov (United States)

    Stagnaro, Mattia; Colli, Matteo; Lanza, Luca

    2017-04-01

    Solid precipitation measurements are affected by systematic wind-induced errors, due to the aerodynamic response of catching type gauges. The snowflakes deviate from their undisturbed trajectories due to the alteration of the airflow field around the body of the gauge and the corresponding developed turbulence. The resulting effect consists in a certain degree of undercatch, which is a function of the undisturbed wind velocity. The correction of wind-induced errors has been addressed in the literature from the conceptual, numerical and experimental point of view. The Collection Efficiency (CE) curve of a single gauge, i.e. the relationship between the expected undercatch and the undisturbed wind speed, is derived from CFD simulations or field test studies (Colli et al., 2015; Wolff et al., 2015). This is used to apply a suitable transfer function (TF) to correct the wind-induced errors in real world measurements. Snowfall depth and wind speed measurements are commonly recorded at a temporal resolution in the order of 30-60 minutes, although the effect of wind bursts can affect the measurements at a much higher resolution. In this work, we investigate the impact of the aggregation scale on the accuracy of snowfall data when corrected by using the transfer function. From the WMO SPICE (Solid Precipitation Intercomparison Experiment) field campaign, we selected a number of snowfall events recorded at the Marshall Field test site (Colorado, USA) during the winter seasons from 2013 to 2015. We used three Geonor weighing type gauges with different configurations: unshielded, Single Alter shielded (SA) and the Double Fence Intercomparison Reference (DFIR). Both precipitation and wind speed data are quality controlled and provided with the time resolution of one minute. The Transfer Function has been derived from the selected number of snowfall events by comparison with the field reference (DFIR). Starting from the reference snowfall measurements and the wind speed values

  2. RCM skill assessment applying precipitation, temperature and hydrological performance measures: comparing different RCM resolutions and bias correction methods

    Science.gov (United States)

    Pasten-Zapata, Ernesto; Jones, Julie; Moggridge, Helen; Widmann, Martin

    2017-04-01

    Global Climate Models (GCMs) are the main tool to assess futures changes in climate and their impacts. Due to their coarse resolution, GCMs fail to accurately simulate observed climate variables at the catchment scale. Therefore, climate researchers have focused on increasing model resolution by nesting Regional Climate Models (RCMs) into the GCMs for regional areas, a process known as dynamical downscaling. Commonly, RCMs also have simulation biases at the catchment scale and therefore statistical techniques, known as bias correction methods, are used to reduce such biases. In this project the skill to simulate precipitation and temperature from five reanalysis-driven Euro-CORDEX RCMs is evaluated. Furthermore, RCM precipitation and temperature outputs are coupled with a hydrological model (the HEC-HMS model) to simulate river flow at the catchment scale. Precipitation, temperature and hydrological biases are assessed using a range of metrics combining mean, extremes, time series and distribution measures. In order to evaluate the dynamical downscaling effect, the RCMs are analyzed at two resolutions: 0.44° and 0.11°. Additionally, both resolutions are bias-corrected employing the parametric quantile-mapping method: a) temperature is bias-corrected using the normal distribution, and b) precipitation is bias-corrected using the gamma and double-gamma distributions. Four catchments across England and Wales covering different climate conditions and topographical characteristics are used as study sites. The results from this study provide an overview of the skill of current state-of-the-art RCMs and their suitability for hydrological impact analysis at the catchment scale. Furthermore, for precipitation the study analyses the performance of the commonly-used gamma distribution quantile-mapping bias-correction method comparing it to the double-gamma distribution method considering their implications towards the simulation of hydrological impacts.

  3. Deconvolution as a means of correcting turbulence power spectra measured by LDA

    Science.gov (United States)

    Buchhave, Preben; Velte, Clara

    2014-11-01

    Measurement of turbulence power spectra by means of laser Doppler anemometry (LDA) has proven to be a difficult task. Among the problems affecting the shape of the spectrum are noise in the signal and changes in the sample rate caused by unintentional effects in the measuring apparatus or even in the mathematical algorithms used to evaluate the spectrum. We analyze the effect of various causes of bias in the sample rate and show that the effect is a convolution of the true spectrum with various spectral functions. We show that these spectral functions can be measured with the available data from a standard LDA processor and we use this knowledge to correct the measured spectrum by deconvolution. We present results supported by realistic computer generated data using two different spectral estimators, the so-called slotted autocovariance method and the so-called direct method.

  4. Bias corrections of GOSAT SWIR XCO2 and XCH4 with TCCON data and their evaluation using aircraft measurement data

    Science.gov (United States)

    Inoue, Makoto; Morino, Isamu; Uchino, Osamu; Nakatsuru, Takahiro; Yoshida, Yukio; Yokota, Tatsuya; Wunch, Debra; Wennberg, Paul O.; Roehl, Coleen M.; Griffith, David W. T.; Velazco, Voltaire A.; Deutscher, Nicholas M.; Warneke, Thorsten; Notholt, Justus; Robinson, John; Sherlock, Vanessa; Hase, Frank; Blumenstock, Thomas; Rettinger, Markus; Sussmann, Ralf; Kyrö, Esko; Kivi, Rigel; Shiomi, Kei; Kawakami, Shuji; De Mazière, Martine; Arnold, Sabrina G.; Feist, Dietrich G.; Barrow, Erica A.; Barney, James; Dubey, Manvendra; Schneider, Matthias; Iraci, Laura T.; Podolske, James R.; Hillyard, Patrick W.; Machida, Toshinobu; Sawa, Yousuke; Tsuboi, Kazuhiro; Matsueda, Hidekazu; Sweeney, Colm; Tans, Pieter P.; Andrews, Arlyn E.; Biraud, Sebastien C.; Fukuyama, Yukio; Pittman, Jasna V.; Kort, Eric A.; Tanaka, Tomoaki

    2016-08-01

    We describe a method for removing systematic biases of column-averaged dry air mole fractions of CO2 (XCO2) and CH4 (XCH4) derived from short-wavelength infrared (SWIR) spectra of the Greenhouse gases Observing SATellite (GOSAT). We conduct correlation analyses between the GOSAT biases and simultaneously retrieved auxiliary parameters. We use these correlations to bias correct the GOSAT data, removing these spurious correlations. Data from the Total Carbon Column Observing Network (TCCON) were used as reference values for this regression analysis. To evaluate the effectiveness of this correction method, the uncorrected/corrected GOSAT data were compared to independent XCO2 and XCH4 data derived from aircraft measurements taken for the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) project, the National Oceanic and Atmospheric Administration (NOAA), the US Department of Energy (DOE), the National Institute for Environmental Studies (NIES), the Japan Meteorological Agency (JMA), the HIAPER Pole-to-Pole observations (HIPPO) program, and the GOSAT validation aircraft observation campaign over Japan. These comparisons demonstrate that the empirically derived bias correction improves the agreement between GOSAT XCO2/XCH4 and the aircraft data. Finally, we present spatial distributions and temporal variations of the derived GOSAT biases.

  5. Work-related stress among correctional officers: A qualitative study.

    Science.gov (United States)

    Viotti, Sara

    2016-01-25

    Correctional officers (COs) are exposed to various factors likely to jeopardize their health and safety. Even if numerous studies have been focused on work-related stress among COs, few studies have been carried out in Italy. Indentify the work-related factors and comprehend how they negatively affect the COs' psychological health in the Italian penal system. A qualitative approach was employed. Twenty-eight COs employed in a detention block of an Italian jail were interviewed face-to-face. For the analyses of the text, Template Analysis technique was followed. The analyses of the text highlighted six macro-categories and thirteen categories hierarchically linked to them: A) Intrinsic work-related factors with six categories: demanding contact with prisoners, high level of responsibility, health risks, critical events, lack of intellectual and social stimulation, and conflict value; B) Factors related to the type of contract and work organization: challenging working hours contrasted with social time, and relocation; C) Social factors: relationships with colleagues and hierarchy; D) Organizational factors: organizational injustice, E) External factors: negative social image; F) Physical environmental factors: physical structure of the prison building. The results indicated that COs are at high risk of stress. More specifically, the analyses highlighted that the most stressful part of the COs' job concerns their relationship with the inmates.

  6. Measurement and correction of microscopic head motion during magnetic resonance imaging of the brain.

    Directory of Open Access Journals (Sweden)

    Julian Maclaren

    Full Text Available Magnetic resonance imaging (MRI is a widely used method for non-invasive study of the structure and function of the human brain. Increasing magnetic field strengths enable higher resolution imaging; however, long scan times and high motion sensitivity mean that image quality is often limited by the involuntary motion of the subject. Prospective motion correction is a technique that addresses this problem by tracking head motion and continuously updating the imaging pulse sequence, locking the imaging volume position and orientation relative to the moving brain. The accuracy and precision of current MR-compatible tracking systems and navigator methods allows the quantification and correction of large-scale motion, but not the correction of very small involuntary movements in six degrees of freedom. In this work, we present an MR-compatible tracking system comprising a single camera and a single 15 mm marker that provides tracking precision in the order of 10 m and 0.01 degrees. We show preliminary results, which indicate that when used for prospective motion correction, the system enables improvement in image quality at both 3 T and 7 T, even in experienced and cooperative subjects trained to remain motionless during imaging. We also report direct observation and quantification of the mechanical ballistocardiogram (BCG during simultaneous MR imaging. This is particularly apparent in the head-feet direction, with a peak-to-peak displacement of 140 m.

  7. X-ray beam hardening correction for measuring density in linear accelerator industrial computed tomography

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ri-Feng; WANG Jue; CHEN Wei-Min

    2009-01-01

    Due to X-ray attenuation being approximately proportional to material density, it is possible to measure the inner density through Industrial Computed Tomography (ICT) images accurately. In practice, however, a number of factors including the non-linear effects of beam hardening and diffuse scattered radia-tion complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction, and uses polynomial fitting coefficient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction, the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple, and it is valuable for measuring the ICT density and making use of the CT images to recognize materials.

  8. A Linear-correction Least-squares Approach for Geolocation Using FDOA Measurements Only

    Institute of Scientific and Technical Information of China (English)

    LI Jinzhou; GUO Fucheng; JIANG Wenli

    2012-01-01

    A linear-correction least-squares(LCLS) estimation procedure is proposed for geolocation using frequency difference of arrival(FDOA) measurements only.We first analyze the measurements of FDOA,and further derive the Cramér-Rao lower bound(CRLB) of geolocation using FDOA measurements.For the localization model is a nonlinear least squares(LS) estimator with a nonlinear constrained,a linearizing method is used to convert the model to a linear least squares estimator with a nonlinear constrained.The Gauss-Newton iteration method is developed to conquer the source localization problem.From the analysis of solving Lagrange multiplier,the algorithm is a generalization of linear-correction least squares estimation procedure under the condition of geolocation using FDOA measurements only.The algorithm is compared with common least squares estimation.Comparisons of their estimation accuracy and the CRLB are made,and the proposed method attains the CRLB.Simulation resuits are included to corroborate the theoretical development.

  9. Study on geometric correction of airborne multiangular imagery

    Institute of Scientific and Technical Information of China (English)

    LIU; Qiang; (刘强); LIU; Qinhuo; (柳钦火); XIAO; Qing; (肖青); TIAN; Guoliang; (田国良)

    2002-01-01

    An automatic image matching algorithm, and its application to geometric correction of airborne multiangular remote sensed imagery, are presented in this paper. The image-matching algorithm is designed to find correct match for images containing localized geometric distortion and spectral variation. Mathematical tools such as wavelet decomposition, B-spline, and multi-variant correlation estimator are integrated in the frame of pyramidal matching. The simulated experiment and our practice in correcting airborne multiangular images show that the matching algorithm is robust to the few random abnormal points and can achieve subpixel match accuracy in most area of the image. After geometric correction and registration, multiangular observations for each ground pixel are extracted and sun/view geometry is also simultaneously derived.

  10. Flux correction for closed-path laser spectrometers without internal water vapor measurements

    Directory of Open Access Journals (Sweden)

    R. V. Hiller

    2012-01-01

    Full Text Available Recently, instruments became available on the market that provide the possibility to perform eddy covariance flux measurements of CH4 and many other trace gases, including the traditional CO2 and H2O. Most of these instruments employ laser spectroscopy, where a cross-sensitivity to H2O is frequently observed leading to an increased dilution effect. Additionally, sorption processes at the intake tube walls modify and delay the observed H2O signal in closed-path systems more strongly than the signal of the sampled trace gas. Thereby, a phase shift between the trace gas and H2O fluctuations is introduced that dampens the H2O flux observed in the sampling cell. For instruments that do not provide direct H2O measurement in the sampling cell, transfer functions from externally measured H2O fluxes are needed to estimate the effect of H2O on trace gas flux measurements. The effects of cross-sensitivity and the damping are shown for an eddy covariance setup with the Fast Greenhouse Gas Analyzer (FGGA, Los Gatos Research Inc. that measures CO2, CH4, and H2O fluxes. This instrument is technically identical with the Fast Methane Analyzer (FMA, Los Gatos Research Inc. that does not measure H2O concentrations. Hence, we used measurements from a FGGA to derive a modified correction for the FMA accounting for dilution as well as phase shift effects in our instrumental setup. With our specific setup for eddy covariance flux measurements, the cross-sensitivity counteracts the damping effects, which compensate each other. Hence, the new correction only deviates very slightly from the traditional Webb, Pearman, and Leuning density correction, which is calculated from separate measurements of the atmospheric water vapor flux.

  11. Determination of Correction Factors for Small Field Based on Measurement and Numerical Calculation using Cylindrical Ionization Chambers

    CERN Document Server

    Park, Kwangwoo; Park, Sungho; Choi, Jin Hwa; Park, Suk Won; Bak, Jino

    2015-01-01

    We studied the investigation of volume averaging effect for air-filled cylindrical ionization chambers to determine correction factors in small photon field for the given chamber. As a method, we measured output factors using several cylindrical ionization chambers and calculated with mathematical method similar to deconvolution in which we modeled non-constant and inhomogeneous exposure function in the cavity of chamber. The parameters in exposure function and correction factors were determined by solving a system of equations we developed with measurement data and geometry of the given chamber. Correction factors (CFs) we had found are very similar to that from Monte Carlo (MC) simulation. For example, CFs in this study were computed as 1.116 for PTW31010, and 1.0225 for PTW31016, while CFs from MC were reported as approximately between 1.17 and 1.20 for PTW31010, and between 1.02 and 1.06 for PTW31016 in of 6MV photon beam . Furthermore, the result from the method of deconvolution combined with MC for cham...

  12. Model-based approach for beam hardening correction and resolution measurements in microtomography

    Science.gov (United States)

    van de Casteele, Elke

    resolution of the muCT system is the main topic. The resolution of an imaging system describes the ability to distinguish adjacent objects in an image. It is often used as a quality measure. Two different concepts may be comprised by the term image resolution: high-contrast small-detail resolution, also called spatial resolution, for distinguishing adjacent objects of high contrast, and low-contrast large-detail resolution, or contrast resolution, for differentiating an object from its background. A resolution measure combining both aspects is found in the modulation transfer function (MTF), which is the magnitude of the Fourier transformed PSF of the imaging device. The MTF describes how much contrast at a specific spatial frequency is maintained by the imaging process. Two methods for determining the MTF are explained and tested. The effect of beam hardening, geometric magnification, and sample material on the resolution measurement is studied.

  13. Water column correction for coral reef studies by remote sensing.

    Science.gov (United States)

    Zoffoli, Maria Laura; Frouin, Robert; Kampel, Milton

    2014-09-11

    Human activity and natural climate trends constitute a major threat to coral reefs worldwide. Models predict a significant reduction in reef spatial extension together with a decline in biodiversity in the relatively near future. In this context, monitoring programs to detect changes in reef ecosystems are essential. In recent years, coral reef mapping using remote sensing data has benefited from instruments with better resolution and computational advances in storage and processing capabilities. However, the water column represents an additional complexity when extracting information from submerged substrates by remote sensing that demands a correction of its effect. In this article, the basic concepts of bottom substrate remote sensing and water column interference are presented. A compendium of methodologies developed to reduce water column effects in coral ecosystems studied by remote sensing that include their salient features, advantages and drawbacks is provided. Finally, algorithms to retrieve the bottom reflectance are applied to simulated data and actual remote sensing imagery and their performance is compared. The available methods are not able to completely eliminate the water column effect, but they can minimize its influence. Choosing the best method depends on the marine environment, available input data and desired outcome or scientific application.

  14. A novel method for incorporating respiratory-matched attenuation correction in the motion correction of cardiac PET-CT studies

    Science.gov (United States)

    McQuaid, Sarah J.; Lambrou, Tryphon; Hutton, Brian F.

    2011-05-01

    Mismatches between PET and CT datasets due to respiratory effects can lead to artefactual perfusion defects. To overcome this, we have proposed a method of aligning a single CT with each frame of a gated PET study in a semi-automatic manner, incorporating a statistical shape model of the diaphragm and a rigid registration of the heart. This ensures that the structures that could influence the appearance of the reconstructed cardiac activity are correctly matched between emission and transmission datasets. When tested on two patient studies, it was found in both cases that attenuation correction using the proposed technique resulted in PET images that were closer to the gold standard of attenuation correction with a gated CT, compared with scenarios where only heart matching was considered (and not the diaphragm) or where no transformation was performed (i.e. where a single CT frame was used to attenuation-correct all PET frames). These preliminary results suggest that diaphragm matching between PET and CT improves the quantitative accuracy of reconstructed PET images and that the proposed method of using a statistical shape model to describe the diaphragm shape and motion, in combination with a rigid registration to determine respiratory-induced heart motion, is a feasible method of achieving this.

  15. Determinations of the correction factors for small fields in cylindrical ionization chambers based on measurement and numerical calculation

    Science.gov (United States)

    Park, Kwangwoo; Choi, Wonhoon; Park, Sungho; Choi, Jin Hwa; Park, Suk Won; Bak, Jino

    2015-07-01

    We investigated the volume averaging effect for air-filled cylindrical ionization chambers to determine the correction factors in a small photon field for a given chamber. We measured output factors with several cylindrical ionization chambers, and by using a mathematical method similar to deconvolution, we modeled the non-constant and inhomogeneous exposure function in the cavity of the chamber. The parameters in the exposure function and the correction factors were determined by solving a system of equations that we had developed by using the measured data and the geometry of the given chamber. The correction factors (CFs) were very similar to those obtained from Monte Carlo (MC) simulations. For example, the CFs in this study were found to be 1.116 for PTW31010 and 1.0225 for PTW31016 while the CFs obtained from MC simulations were reported as being approximately between 1.17 and 1.20 for PTW31010 and between 1.02 and 1.06 for PTW31016 in a 6-MV photon beam of 1 × 1 cm2. Furthermore, the method of deconvolution combined with the MC result for the chamber's response function showed a similar CF for PTW 30013, which was reported as 2.29 and 1.54 for a 1 × 1 cm2 and a 1.5 × 1.5 cm2 field size, respectively. The CFs from our method were similar, 2.42 and 1.54. In addition, we report CFs for PTW30013, PTW31010, PTW31016, IBA FC23-C, and IBA CC13. As a consequence, we suggest the use of our method to measure the correct output factor by using the fact that an inhomogeneous exposure causes a volume averaging effect in the cavity of air-filled cylindrical ionization chamber. The result obtained by using our method is very similar to that obtained from MC simulations. The method we developed can easily be applied in clinics.

  16. A distortion-correction method for workshop machine vision measurement system

    Science.gov (United States)

    Chen, Ruwen; Huang, Ren; Zhang, Zhisheng; Shi, Jinfei; Chen, Zixin

    2008-12-01

    The application of machine vision measurement system is developing rapidly in industry for its non-contact, high speed, and automation characteristics. However, there are nonlinear distortions in the images which are vital to measuring precision, for the object dimensions are determined by the image properties. People are interested in this problem and put forward some physical model based correction methods which are widely applied in engineering. However, these methods are difficult to be realized in workshop for the images are non-repetitive interfered by the coupled dynamic factors, which means the real imaging is a stochastic process. A new nonlinear distortion correction method based on a VNAR model (Volterra series based nonlinear auto-regressive time series model) is proposed to describe the distorted image edge series. The model parameter vectors are achieved by the laws of data. The distortion-free edges are obtained after model filtering and the image dimensions are transformed to measuring dimensions. Experimental results show that the method is reliable and can be applied to engineering.

  17. Error analysis and corrections to pupil diameter measurements with Langley Research Center's oculometer

    Science.gov (United States)

    Fulton, C. L.; Harris, R. L., Jr.

    1980-01-01

    Factors that can affect oculometer measurements of pupil diameter are: horizontal (azimuth) and vertical (elevation) viewing angle of the pilot; refraction of the eye and cornea; changes in distance of eye to camera; illumination intensity of light on the eye; and counting sensitivity of scan lines used to measure diameter, and output voltage. To estimate the accuracy of the measurements, an artificial eye was designed and a series of runs performed with the oculometer system. When refraction effects are included, results show that pupil diameter is a parabolic function of the azimuth angle similar to the cosine function predicted by theory: this error can be accounted for by using a correction equation, reducing the error from 6% to 1.5% of the actual diameter. Elevation angle and illumination effects were found to be negligible. The effects of counting sensitivity and output voltage can be calculated directly from system documentation. The overall accuracy of the unmodified system is about 6%. After correcting for the azimuth angle errors, the overall accuracy is approximately 2%.

  18. Toward Best Practices For Assessing Near Surface Sensor Fouling: Potential Correction Approaches Using Underway Ferry Measurements

    Science.gov (United States)

    Sastri, A. R.; Dewey, R. K.; Pawlowicz, R.; Krogh, J.

    2016-02-01

    Data from long term deployments of sensors on autonomous, mobile and cabled observation platforms suffer potential quality issues associated with bio-fouling. This issue is of particular concern for optical sensors, such as fluorescence and/or absorbance-based instruments for which light emitting/receiving surfaces are prone to fouling due constant contact with the marine environment. Here we examine signal quality for backscatter, chlorophyll and CDOM fluorescence from a single triplet instrument installed in a ferry box system (nominal depth of 3m) operated by Ocean Networks Canada. The time series consists of 22 months of 8-10 daily transits across the productive waters of the Strait of Georgia, British Columbia, Canada (Nanaimo on Vancouver Island and Vancouver on mainland BC). Instruments were cleaned every 2 weeks since all three instruments experienced significant signal attenuation during that period throughout the year. We experimented with a variety of pre- and post-cleaning measurements in an effort to develop `correction factors' with which to account for the effects of fouling. We found that CDOM fluorescence was especially sensitive to fouling and that correction factors derived from measurements of the fluorescence of standardized solutions successfully accounted for fouling. Similar results were found for chlorophyll fluorescence. Here we present results from our measurements and assess the efficacy of each of these approaches using comparisons against additional instruments less prone to signal attenuation over short periods.

  19. Evaluation of imaging technologies to correct for photon attenuation in the overlying tissue for in vivo bone strontium measurements

    Energy Technology Data Exchange (ETDEWEB)

    Heirwegh, C M; Chettle, D R; Pejovic-Milic, A [Medical Physics and Applied Radiation Science, McMaster University, Hamilton, L8S 4K1 (Canada)], E-mail: cheirweg@uoguelph.ca

    2010-02-21

    The interpretation of measurements of bone strontium in vivo using energy dispersive x-ray fluorescence spectroscopy is presently hindered by overlying skin and soft-tissue absorption of the strontium x-rays. The use of imaging technologies to measure the overlying soft-tissue thickness at the index finger measuring site might allow correction of the strontium reading to estimate its concentration in bone. An examination of magnetic resonance (MR), computed tomography (CT) and high-frequency ultrasound (US) imaging technologies revealed that 55 MHz US had the smallest range of measurement uncertainty at 3.2% followed by 1 Tesla MR, 25 MHz US, 8 MHz US and CT at 4.3, 5.4, 6.6 and 7.1% uncertainty, respectively. Of these, only CT imaging appeared to underestimate total thickness (p < 0.05). Furthermore, an inter-study comparison on the accuracy of US measurements of the overlying tissue thickness at finger and ankle in nine subjects was investigated. The 8 MHz US system used in prior in vivo experiments was found to perform satisfactorily in a repeat study of ankle measurements, but indicated that finger thickness measurements may have been misread in previous studies by up to 17.7% (p < 0.025). Repeat ankle measurements were not significantly different from initial measurements at 2.2% difference.

  20. Slip Correction Measurements of Polystyrene and Polyvinyltoluene Aerosol Particles Using AN Improved Millikan Apparatus.

    Science.gov (United States)

    Allen, Michael Dana

    A slip correction equation of the form C(Kn) = 1 + Kn{(alpha) + (beta)exp(-(gamma)/Kn)} with Kn the particle Knudsen number is routinely used to correct Stokes' law for progressively lower than predicted drag force as Kn increases. The published values of the parameters ((alpha), (beta), and (gamma)) are based on Millikan's original values corrected with an improved value of mean free path for gas molecules in dry air. In this work, Millikan's most accurate raw data were carefully reviewed and the slip correction parameters were reevaluated using the latest published values of physical constants and nonlinear least squares function fitting. The values of (alpha), (beta), and (gamma) given by Millikan in 1923 adjusted for a modern value of the mean free path ((lamda) = 0.0673 (mu)m at 23(DEGREES)C and 760 mm of Hg) were 1.209, 0.406, and 0.893, respectively. Improved values of these parameters calculated by least squares using Millikan's most accurate raw data are 1.155, 0.471, and 0.596, respectively. Though these two sets of values appear significantly different, the maximum percentage difference in the calculated correction factor is less than 2.0% over the Knudsen number range of 0.001 to 100. This error is small when compared to differences which may be caused by different particle surfaces and gas compositions. An improved version of the Millikan oil-drop apparatus was built and slip correction measurements were made on ninety solid, spherical particles in air. Measurements were made on eleven polystyrene latex-divinylbenzene particles, twenty-five polyvinyltoluene particles, and fifty-four polystyrene latex particles, spanning a Knudsen number range from 0.03 to 7.2. The values of (alpha), (beta), and (gamma) computed using nonlinear least squares function fitting for a mean free path at 23(DEGREES)C of 0.0673 (mu)m and a viscosity of 1.83245 x 10('-4) gcm('-1)s(' -1) were 1.142, 0.558, and 0.99 respectively. The value of (alpha) agrees very closely with

  1. Simple, Fast and Effective Correction for Irradiance Spatial Nonuniformity in Measurement of IVs of Large Area Cells at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Moriarty, Tom

    2016-11-21

    The NREL cell measurement lab measures the IV parameters of cells of multiple sizes and configurations. A large contributing factor to errors and uncertainty in Jsc, Imax, Pmax and efficiency can be the irradiance spatial nonuniformity. Correcting for this nonuniformity through its precise and frequent measurement can be very time consuming. This paper explains a simple, fast and effective method based on bicubic interpolation for determining and correcting for spatial nonuniformity and verification of the method's efficacy.

  2. Research and application of air mercury measurement based on transverse Zeeman background correction

    Science.gov (United States)

    Zhang, Yong; Si, Fuqi; Zeng, Yi; Li, Chuangxin; Liu, Wenqing

    2016-10-01

    Mercury is known as a highly toxic metal, which will have a significant health hazard to the human body. To monitor the trace mercury pollution in air, the development of monitoring instruments has been conducted. In this paper the mercury analyzer is developed based on the cold atomic absorption spectrometry theory by exploiting the transverse Zeeman-Effect background correction technology. The experiments have been done to test the performance of the system. At the same time, the same experiments with RA-915 mercury analyzer have been done to compare with the results. First, zero gas was measured for an hour and high concentration mercury sample gas was measured for four days. The results of zero gas shows that the detection limit of the system is 2.19ng/m3 and the standard deviation is 0.73. The concentration fluctuation is within a tight range of +/-1.5ng/m3. The results of high concentration sample gas are in good agreement with the results of RA-915, and the correlation coefficient is 0.95. Second, laboratory air was measured for 12 hours. The results compared with RA-915 are in good agreement and have the same variation trend. Additionally, the atmospheric mercury concentration near the non-ferrous metal smelter in Tongling city has been measured by the system and the RA-915. The measurement results from two analyzers have a good linear correlation with correlation coefficient of 0.98 and slope of 1.027. It indicates that the system has accurate background correction ability, low detection limit and is applicable to long-term air mercury on-line monitoring.

  3. Error correction algorithm for high accuracy bio-impedance measurement in wearable healthcare applications.

    Science.gov (United States)

    Kubendran, Rajkumar; Lee, Seulki; Mitra, Srinjoy; Yazicioglu, Refet Firat

    2014-04-01

    Implantable and ambulatory measurement of physiological signals such as Bio-impedance using miniature biomedical devices needs careful tradeoff between limited power budget, measurement accuracy and complexity of implementation. This paper addresses this tradeoff through an extensive analysis of different stimulation and demodulation techniques for accurate Bio-impedance measurement. Three cases are considered for rigorous analysis of a generic impedance model, with multiple poles, which is stimulated using a square/sinusoidal current and demodulated using square/sinusoidal clock. For each case, the error in determining pole parameters (resistance and capacitance) is derived and compared. An error correction algorithm is proposed for square wave demodulation which reduces the peak estimation error from 9.3% to 1.3% for a simple tissue model. Simulation results in Matlab using ideal RC values show an average accuracy of for single pole and for two pole RC networks. Measurements using ideal components for a single pole model gives an overall and readings from saline phantom solution (primarily resistive) gives an . A Figure of Merit is derived based on ability to accurately resolve multiple poles in unknown impedance with minimal measurement points per decade, for given frequency range and supply current budget. This analysis is used to arrive at an optimal tradeoff between accuracy and power. Results indicate that the algorithm is generic and can be used for any application that involves resolving poles of an unknown impedance. It can be implemented as a post-processing technique for error correction or even incorporated into wearable signal monitoring ICs.

  4. Scale factor correction for Gaussian beam truncation in second moment beam radius measurements

    Science.gov (United States)

    Hofer, Lucas R.; Dragone, Rocco V.; MacGregor, Andrew D.

    2017-04-01

    Charged-couple devices (CCD) and complementary metal oxide semiconductor (CMOS) image sensors, in conjunction with the second moment radius analysis method, are effective tools for determining the radius of a laser beam. However, the second moment method heavily weights sensor noise, which must be dealt with using a thresholding algorithm and a software aperture. While these noise reduction methods lower the random error due to noise, they simultaneously generate systematic error by truncating the Gaussian beam's edges. A scale factor that is invariant to beam ellipticity and corrects for the truncation of the Gaussian beam due to thresholding and the software aperture has been derived. In particular, simulations showed an order of magnitude reduction in measured beam radius error when using the scale factor-irrespective of beam ellipticity-and further testing with real beam data demonstrated that radii corrected by the scale factor are independent of the noise reduction parameters. Thus, through use of the scale factor, the accuracy of beam radius measurements made with a CCD or CMOS sensor and the second moment are significantly improved.

  5. Results of error correction techniques applied on two high accuracy coordinate measuring machines

    Energy Technology Data Exchange (ETDEWEB)

    Pace, C.; Doiron, T.; Stieren, D.; Borchardt, B.; Veale, R. (Sandia National Labs., Albuquerque, NM (USA); National Inst. of Standards and Technology, Gaithersburg, MD (USA))

    1990-01-01

    The Primary Standards Laboratory at Sandia National Laboratories (SNL) and the Precision Engineering Division at the National Institute of Standards and Technology (NIST) are in the process of implementing software error correction on two nearly identical high-accuracy coordinate measuring machines (CMMs). Both machines are Moore Special Tool Company M-48 CMMs which are fitted with laser positioning transducers. Although both machines were manufactured to high tolerance levels, the overall volumetric accuracy was insufficient for calibrating standards to the levels both laboratories require. The error mapping procedure was developed at NIST in the mid 1970's on an earlier but similar model. The error mapping procedure was originally very complicated and did not make any assumptions about the rigidness of the machine as it moved, each of the possible error motions was measured at each point of the error map independently. A simpler mapping procedure was developed during the early 1980's which assumed rigid body motion of the machine. This method has been used to calibrate lower accuracy machines with a high degree of success and similar software correction schemes have been implemented by many CMM manufacturers. The rigid body model has not yet been used on highly repeatable CMMs such as the M48. In this report we present early mapping data for the two M48 CMMs. The SNL CMM was manufactured in 1985 and has been in service for approximately four years, whereas the NIST CMM was delivered in early 1989. 4 refs., 5 figs.

  6. Error Correction of Measured Unstructured Road Profiles Based on Accelerometer and Gyroscope Data

    Directory of Open Access Journals (Sweden)

    Jinhua Han

    2017-01-01

    Full Text Available This paper describes a noncontact acquisition system composed of several time synchronized laser height sensors, accelerometers, gyroscope, and so forth in order to collect the road profiles of vehicle riding on the unstructured roads. A method of correcting road profiles based on the accelerometer and gyroscope data is proposed to eliminate the adverse impacts of vehicle vibration and attitudes change. Because the power spectral density (PSD of gyro attitudes concentrates in the low frequency band, a method called frequency division is presented to divide the road profiles into two parts: high frequency part and low frequency part. The vibration error of road profiles is corrected by displacement data obtained through two times integration of measured acceleration data. After building the mathematical model between gyro attitudes and road profiles, the gyro attitudes signals are separated from low frequency road profile by the method of sliding block overlap based on correlation analysis. The accuracy and limitations of the system have been analyzed, and its validity has been verified by implementing the system on wheeled equipment for road profiles’ measuring of vehicle testing ground. The paper offers an accurate and practical approach to obtaining unstructured road profiles for road simulation test.

  7. Reconstruction of high-resolution 3D dose from matrix measurements : error detection capability of the COMPASS correction kernel method

    NARCIS (Netherlands)

    Godart, J.; Korevaar, E. W.; Visser, R.; Wauben, D. J. L.; van t Veld, Aart

    2011-01-01

    TheCOMPASS system (IBADosimetry) is a quality assurance (QA) tool which reconstructs 3D doses inside a phantom or a patient CT. The dose is predicted according to the RT plan with a correction derived from 2D measurements of a matrix detector. This correction method is necessary since a direct recon

  8. Collaboration between Correctional and Public School Systems for Juvenile Offenders: A Case Study.

    Science.gov (United States)

    Hellriegel, Kimberly L.; Yates, James R.

    The educational processes for youth who participated in a county-run correctional facility for juvenile offenders were studied. The county's Leadership Academy, a 48-bed correctional treatment center where juveniles are placed when ordered into direct care, is designed to divert repeat male offenders from the state-run correctional system. The…

  9. Park correction for FINO1-wind speed measurements at alpha ventus

    Energy Technology Data Exchange (ETDEWEB)

    Kinder, F.; Westerhellweg, A.; Neumann, T. [DEWI, Wilhelmshaven (Germany)

    2013-02-15

    The FINO1-research platform and its 100m-mast were erected in 2003 to perform investigations of the marine atmospheric boundary layer for offshore wind energy projects. Meteorological measurements focus on wind speed and wind direction measured at different heights [1]. After six years of undisturbed measurements between 2004 and 2009, the offshore wind farm alpha ventus influences the wind and turbulence conditions reaching FINO1 from eastern directions. In the wake of a wind turbine the flow is changed such that the turbulence intensity increases while the wind speed decreases. To continue free flow measurements from eastern directions a LiDAR-device was mounted on the alpha ventus converter station in April 2011. The LiDAR measurements are evaluated in comparison with data from FINO1 for the recovery of the undisturbed wind field at FINO1 and to develop a park correction for the FINO1-wind measurement. For the period of May 2011 to September 2012 the park factor (vLiDAR/vFINO1) for eastern directions is calculated from 10-minute mean values and then averaged for 2 -wind direction bins, 2 m/s-wind speed bins and three different stability classes for four heights respectively. Only data points were regarded during which all the wind turbines influencing the particular wind direction bin were operating. The park effect increases for lower wind speeds and for heights close to the nacelle with highest values occurring during stable atmospheric stratification. (orig.)

  10. Elliptically Weighted HOLICs for Weak-lensing Shear Measurement. I. Definitions and Isotropic Point-spread Function Correction

    Science.gov (United States)

    Okura, Yuki; Futamase, Toshifumi

    2011-03-01

    We develop a new method of estimating gravitational shear by adopting an elliptical weight function to measure background galaxy images. In doing so, we introduce the new concept of "zero plane," which is an imaginary source plane where shapes of all sources are perfect circles, and regard the intrinsic shear as the result of an imaginary lensing distortion. This makes the relation between the observed shear, intrinsic shear, and lensing distortion much simpler, and thus higher-order calculations are easier. The elliptical weight function allows us to measure the multipole moments of the shapes of background galaxies more precisely by weighting brighter parts of the image highly, and to reduce systematic error due to insufficient expansion of the weight function in the original approach of Kaiser et al. (KSB). Point-spread function (PSF) correction in the elliptically weighted higher-order lensing image characteristics (E-HOLICs) method becomes more complicated than in the KSB method. In this paper, we study isotropic PSF correction in detail. By adopting the lensing distortion as the ellipticity of the weight function, we are able to show that the shear estimation in the E-HOLICs method reduces to solve a polynomial in the absolute magnitude of the distortion. We compare the systematic errors between our approach and that of KSB using the Shear Testing Programme 2 simulation. It is confirmed that the KSB method overestimates the input shear for images with large ellipticities, and E-HOLICs correctly estimates the input shear even for such images. Anisotropic PSF correction and analysis of real data will be presented in a forthcoming paper.

  11. Study of Fusion Dynamics Using Skyrme Energy Density Formalism with Different Surface Corrections

    Institute of Scientific and Technical Information of China (English)

    Ishwar Dutt; Narinder K. Dhiman

    2010-01-01

    @@ Within the framework of Skyrme energy density formalism, we investigate the role of surface corrections on the fusion of colliding nuclei. The coefficient of surface correction is varied between 1/36 and 4/36, and its impact is studied on about 180 reactions. The detailed investigations indicate a linear relationship between the fusion barrier heights and strength of the surface corrections. Our analysis of the fusion barriers advocate the strength of surface correction of 1/36.

  12. Correction of optical absorption and scattering variations in Laser Speckle Rheology measurements.

    Science.gov (United States)

    Hajjarian, Zeinab; Nadkarni, Seemantini K

    2014-03-24

    Laser Speckle Rheology (LSR) is an optical technique to evaluate the viscoelastic properties by analyzing the temporal fluctuations of backscattered speckle patterns. Variations of optical absorption and reduced scattering coefficients further modulate speckle fluctuations, posing a critical challenge for quantitative evaluation of viscoelasticity. We compare and contrast two different approaches applicable for correcting and isolating the collective influence of absorption and scattering, to accurately measure mechanical properties. Our results indicate that the numerical approach of Monte-Carlo ray tracing (MCRT) reliably compensates for any arbitrary optical variations. When scattering dominates absorption, yet absorption is non-negligible, diffusing wave spectroscopy (DWS) formalisms perform similar to MCRT, superseding other analytical compensation approaches such as Telegrapher equation. The computational convenience of DWS greatly simplifies the extraction of viscoelastic properties from LSR measurements in a number of chemical, industrial, and biomedical applications.

  13. Measurement of Interobserver Disagreement: Correction of Cohen’s Kappa for Negative Values

    Directory of Open Access Journals (Sweden)

    Tarald O. Kvålseth

    2015-01-01

    Full Text Available As measures of interobserver agreement for both nominal and ordinal categories, Cohen’s kappa coefficients appear to be the most widely used with simple and meaningful interpretations. However, for negative coefficient values when (the probability of observed disagreement exceeds chance-expected disagreement, no fixed lower bounds exist for the kappa coefficients and their interpretations are no longer meaningful and may be entirely misleading. In this paper, alternative measures of disagreement (or negative agreement are proposed as simple corrections or modifications of Cohen’s kappa coefficients. The new coefficients have a fixed lower bound of −1 that can be attained irrespective of the marginal distributions. A coefficient is formulated for the case when the classification categories are nominal and a weighted coefficient is proposed for ordinal categories. Besides coefficients for the overall disagreement across categories, disagreement coefficients for individual categories are presented. Statistical inference procedures are developed and numerical examples are provided.

  14. Study on Overall Concept Planning of Terminal Correction Mortar Projectiles

    Institute of Scientific and Technical Information of China (English)

    XU Jin-xiang

    2008-01-01

    The system composition, the operational principle of terminal correction mortar projectiles (TCMP) and the concept planning design of TCMP are researched in this paper. An overall design and aerodynamic configuration layout for TCMP are made in this paper, and its aerodynamic coefficients are calculated by using computational fluid dynamics (CFD) software. Test results of TCMP simulated ballistic projectiles indicate the designed TCMP can satisfy the interior ballistic demand and has a fine flight stability. The drag coefficients identified from the radar velocity-time data are in accord with the CFD computed results. According to the exposure frequency of the ground laser designator, a four-quadrant impulse correction scheme and a high exposure frequency impulse correction scheme are brought. The latter can calculate the target azimuth angle by counting the times of the facula passing through one quadrant. Simulation results also show that the guidance precision of the velocity pursuit is higher than that of the body pursuit, and the detector axis is less circuitous. Researches on the typical trajectory indicate that the terminal impulse correction can improve the hit precision of TCMP remarkably.

  15. Measurement errors in polymerase chain reaction are a confounding factor for a correct interpretation of 5-HTTLPR polymorphism effects on lifelong premature ejaculation: a critical analysis of a previously published meta-analysis of six studies.

    Directory of Open Access Journals (Sweden)

    Paddy K C Janssen

    Full Text Available OBJECTIVE: To analyze a recently published meta-analysis of six studies on 5-HTTLPR polymorphism and lifelong premature ejaculation (PE. METHODS: Calculation of fraction observed and expected genotype frequencies and Hardy Weinberg equilibrium (HWE of cases and controls. LL,SL and SS genotype frequencies of patients were subtracted from genotype frequencies of an ideal population (LL25%, SL50%, SS25%, p = 1 for HWE. Analysis of PCRs of six studies and re-analysis of the analysis and Odds ratios (ORs reported in the recently published meta-analysis. RESULTS: Three studies deviated from HWE in patients and one study deviated from HWE in controls. In three studies in-HWE the mean deviation of genotype frequencies from a theoretical population not-deviating from HWE was small: LL(1.7%, SL(-2.3%, SS(0.6%. In three studies not-in-HWE the mean deviation of genotype frequencies was high: LL(-3.3%, SL(-18.5% and SS(21.8% with very low percentage SL genotype concurrent with very high percentage SS genotype. The most serious PCR deviations were reported in the three not-in-HWE studies. The three in-HWE studies had normal OR. In contrast, the three not-in-HWE studies had a low OR. CONCLUSIONS: In three studies not-in-HWE and with very low OR, inadequate PCR analysis and/or inadequate interpretation of its gel electrophoresis resulted in very low SL and a resulting shift to very high SS genotype frequency outcome. Consequently, PCRs of these three studies are not reliable. Failure to note the inadequacy of PCR tests makes such PCRs a confounding factor in clinical interpretation of genetic studies. Currently, a meta-analysis can only be performed on three studies-in-HWE. However, based on the three studies-in-HWE with OR of about 1 there is not any indication that in men with lifelong PE the frequency of LL,SL and SS genotype deviates from the general male population and/or that the SL or SS genotype is in any way associated with lifelong PE.

  16. Correction of Thermal Deviations of Fabry-Perot Resonator Based Measurements of Specific Gases in Millimeter Wave Bands

    Directory of Open Access Journals (Sweden)

    J. Libich

    2012-04-01

    Full Text Available Due to the thermal expansivity of the material used in the Fabry-Perot resonator mirrors, the resonator cavity length can change and this might therefore have an impact on the resonant frequency during high-resolution spectroscopy measurements. Based on measurements and simulations, this paper discusses the influences of temperature on the precise determination of gas attenuation measured in a Fabry-Perot resonator. Several measures to mitigate such influence and to correct the measured results were tested. A correction method for the measured data was proposed.

  17. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    Directory of Open Access Journals (Sweden)

    A. R. Rodi

    2012-11-01

    Full Text Available A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns – angle of attack, angle of sideslip, dynamic pressure and the error in static pressure – if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft – a trailing cone – and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS and inertial measurement unit (IMU system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

  18. Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

    Directory of Open Access Journals (Sweden)

    A. R. Rodi

    2012-05-01

    Full Text Available Geometric altitude data from a combined Global Navigation Satellite System (GNSS and inertial measurement unit (IMU system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft – a "trailing cone" – in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

  19. The effect of wind farms on vultures in northern Spain - fatalities behaviour and correction measures

    Energy Technology Data Exchange (ETDEWEB)

    Camina, Alvaro

    2011-07-01

    Full text: Spain is one of the leading countries on wind energy, accounting for 20,155 MW installed by 2010. The study has been made in a large area, 300 km long and 50 km width, extending over eight provinces accounting for 170 wind farms and 4605 turbines. 89 wind farms were sampled between 2001 and 2009 for bird fatalities. Collisions involved 2191 griffon vultures Gyps fulvus, the most affected species with 75% of them being adult birds. Other species colliding were the cinereous vulture Aegypius monachus (2 individuals) and the Egyptian vulture Neophron percnopterus (4 individuals). Around 5-10% of turbines caused up to 60% of fatalities and mortality was temporally clumped and related with the species biology. It was lower in January- February while griffons are incubating, increasing in March when hatching. Then, it was reduced until September with a new increase at November-December. In order to explain causes in detail and reduce mortality a pilot study was carried out in a portion of this area (10 wind farms and 267 turbines) from 2005 to the present. Due to high mortality rates on griffons, 33 turbines were shut down by authorities in June 2008. Relationships between flight altitude at turbines area with both weather conditions and landscape features were analysed by means of statistical parametric GLM models. Results included air temperature; turbine features such as its slope and time of the year as significant variables. On the other side, the European policy against the Bovine Spongiform Encephalopathy (BSE) also contributed to increase both mortality and vulture.s crossings through the turbines. Closure of vulture restaurants and carcass removal in the area caused food lacking for these birds. Then, they were forced to feed from a rubbish dump close to the turbines. Correction measures such as opening vulture restaurants since June 2009 and ceasing droppings at the rubbish dump significantly reduced flying rates of griffons to previous levels. In

  20. Final corrective action study for the former CCC/USDA facility in Ramona, Kansas.

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, L. M. (Environmental Science Division)

    2011-04-20

    Past operations at a grain storage facility formerly leased and operated by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) in Ramona, Kansas, resulted in low concentrations of carbon tetrachloride in groundwater that slightly exceed the regulatory standard in only one location. As requested by the Kansas Department of Health and Environment, the CCC/USDA has prepared a Corrective Action Study (CAS) for the facility. The CAS examines corrective actions to address groundwater impacted by the former CCC/USDA facility but not releases caused by other potential groundwater contamination sources in Ramona. Four remedial alternatives were considered in the CAS. The recommended remedial alternative in the CAS consists of Environmental Use Control to prevent the inadvertent use of groundwater as a water supply source, coupled with groundwater monitoring to verify the continued natural improvement in groundwater quality. The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) has directed Argonne National Laboratory to prepare a Corrective Action Study (CAS), consistent with guidance from the Kansas Department of Health and Environment (KDHE 2001a), for the CCC/USDA grain storage facility formerly located in Ramona, Kansas. This effort is pursuant to a KDHE (2007a) request. Although carbon tetrachloride levels at the Ramona site are low, they remain above the Kansas Tier 2 risk-based screening level (RBSL) and the U.S. Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 5 {micro}g/L (Kansas 2003, 2004). In its request for the CAS, the KDHE (2007a) stated that, because of these levels, risk is associated with potential future exposure to contaminated groundwater. The KDHE therefore determined that additional measures are warranted to limit future use of the property and/or exposure to contaminated media as part of site closure. The KDHE further requested comparison of at least two corrective

  1. Study on effective correction of Japanese students' speech drafts

    OpenAIRE

    竹野, 茂; Shigeru, TAKENO

    2000-01-01

    This paper is concerned with the effective correction of students' speech drafts. Japanese students are not familiar not only with the speech performance in English but also with speech writing. This paper exposes the difficulties in speech writing in English for Japanese students, and in the way they develop their opinions. The author considers that the difficulities in speech writing for students come from the interference of Japanese (L1), that is "cultural conflict". Through the correctio...

  2. THE CALCULATION OF BURNABLE POISON CORRECTION FACTORS FOR PWR FRESH FUEL ACTIVE COLLAR MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Croft, Stephen [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory

    2012-06-19

    Gd{sub 2}O{sub 3} burnable poison on the measurement of fresh pressurized water reactor fuel. To empirically determine the response function over the range of historical and future use we have considered enrichments up to 5 wt% {sup 235}U/{sup tot}U and Gd weight fractions of up to 10 % Gd/UO{sub 2}. Parameterized correction factors are presented.

  3. [Evaluation, correction and impact of non-response in studies of childhood obesity].

    Science.gov (United States)

    Santiago-Pérez, María Isolina; Pérez-Ríos, Mónica; Malvar, Alberto; Suanzes, Jorge; Hervada, Xurxo

    2017-09-25

    To evaluate and correct the impact of non-response in the prevalence of underweight, overweight and obesity in children aged 6 to 15 years old using silhouette scales. Cross-sectional study carried out in 2013 among 8,145 Galician schoolchildren aged 6-15 years old. The students who agreed to participate were weighed and measured and, based on body mass index, the prevalence of underweight, overweight and obesity was estimated. Teachers rated all students using silhouette scales. The valuations were used to estimate the prevalence corrected by non-response. Using the Bayes theorem, participation rates were estimated according to weight status. The participation rate was 92.3% in the 6 -to 11-year-old group, and 90% in the 12- to 15-year old age group. In both groups, the prevalence of underweight and overweight were similar between participants and non-participants. However, obesity was higher among non-participants, especially at 12 to 15 years of age (6.3% vs. 12.2% ; p < 0.05). The prevalence did not change when corrected by the teacher's valuation. The participation rate of obese students was lower than the overall rate (82% vs. 90% at 12 to 15 years old; p < 0.05). The presence of participation bias, which was greater at 12-15 years old, was confirmed. However, the impact of the bias on prevalence was negligible due to the high participation rate. In obesity studies with objective measures, it is essential to quantify non-participation, as well as to assess its impact and correct it. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  4. Correction of SOHO CELIAS/SEM EUV Measurements saturated by extreme solar flare events

    CERN Document Server

    Didkovsky, L V; Jones, A R; Wieman, S; Tsurutani, B T; McMullin, D

    2006-01-01

    The solar irradiance in the Extreme Ultraviolet (EUV) spectral bands has been observed with a 15 sec cadence by the SOHO Solar EUV Monitor (SEM) since 1995. During remarkably intense solar flares the SEM EUV measurements are saturated in the central (zero) order channel (0.1 -- 50.0 nm) by the flare soft X-ray and EUV flux. The first order EUV channel (26 -- 34 nm) is not saturated by the flare flux because of its limited bandwidth, but it is sensitive to the arrival of Solar Energetic Particles (SEP). While both channels detect nearly equal SEP fluxes, their contributions to the count rate is sensibly negligible in the zero order channel but must be accounted for and removed from the first channel count rate. SEP contribution to the measured SEM signals usually follows the EUV peak for the gradual solar flare events. Correcting the extreme solar flare SEM EUV measurements may reveal currently unclear relations between the flare magnitude, dynamics observed in different EUV spectral bands, and the measured Ea...

  5. SU-D-BRC-06: Experimental and Monte Carlo Studies of Fluence Corrections for Graphite Calorimetry in Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, A [University College London, London (United Kingdom); National Physical Laboratory, Teddington (United Kingdom); Thomas, R [National Physical Laboratory, Teddington (United Kingdom); Bouchard, H [University of Montreal, Montreal (Canada); Kacperek, A [National Eye Proton therapy Centre, Clatterbridge Cancer Centre, Wirral (United Kingdom); Vondracek, V [Proton Therapy Center, Prague (Czech Republic); Royle, G [University College London, London (United Kingdom); Palmans, H [National Physical Laboratory, Teddington (United Kingdom); EBG MedAustron GmbH, Wiener Neustadt (Austria)

    2016-06-15

    Purpose: For photon and electron beams, the standard device used to measure absorbed dose is a calorimeter. Standards laboratories are currently working on the establishment of graphite calorimeters as a primary standard for proton beams. To provide a practical method for graphite calorimetry, it is necessary to convert dose to graphite to dose to water, requiring knowledge of the water-to-graphite stopping-power ratio and the fluence correction factor. This study aims to present a novel method to determine fluence corrections experimentally, and to apply this methodology to low- and high-energy proton beams. Methods: Measurements were performed in 60 MeV and 180 MeV proton beams. Experimental information was obtained from depth-dose ionization chamber measurements performed in a water phantom. This was repeated with different thicknesses of graphite plates in front of the water phantom. One distinct advantage of this method is that only ionization chamber perturbation factors for water are required. Fluence corrections were also obtained through Monte Carlo simulations for comparison with the experiments. Results: The experimental observations made in this study confirm the Monte Carlo results. Overall, fluence corrections between water and graphite increased with depth, with a maximum correction of 1% for the low-energy beam and 4% for the high-energy beam. The results also showed that a fraction of the secondary particles generated in proton therapy beams do not have enough energy to cross the ionization chamber wall; thus, their contribution is not accounted for in the measured fluence corrections. This effect shows up as a discrepancy in fluence corrections of 1% and has been confirmed by simulations of the experimental setup. Conclusion: Fluence corrections derived by experiment do not account for low-energy secondary particles that are stopped in the ion chamber wall. This work will contribute to a practical graphite calorimetry technique for determining

  6. Optimization of post-run corrections for water stable isotope measurements by laser spectroscopy

    Science.gov (United States)

    van Geldern, Robert; Barth, Johannes A. C.

    2013-04-01

    Light stable isotope analyses of hydrogen and oxygen of water are used in numerous aquatic studies from various scientific fields. The advantage of using stable isotope ratios is that water molecules serve as ubiquitous and already present natural tracers. Traditionally, the samples were analyzed in the laboratory by isotope ratio mass spectrometry (IRMS). Within recent years these analyses have been revolutionized by the development of new isotope ratio laser spectroscopy (IRIS) systems that are said to be cheaper, more robust and mobile compared to IRMS. Although easier to operate, laser systems also need thorough calibration with international reference materials and raw data need correction for analytical effects. A major issue in systems that use liquid injection via a vaporizer module is the memory effect, i.e. the carry-over from the previous analyzed sample in a sequence. This study presents an optimized and simple post-run correction procedure for liquid water injection developed for a Picarro water analyzer. The Excel(TM) template will rely exclusively on standard features implemented in MS Office without the need to run macros, additional code written in Visual Basic for Applications (VBA) or to use a database-related software such as MS Access or SQL Server. These protocols will maximize precision, accuracy and sample throughput via an efficient memory correction. The number of injections per unknown sample can be reduced to 4 or less. This procedure meets the demands of faster throughput with reduced costs per analysis. Procedures were verified by an international proficiency test and traditional IRMS techniques. The template is available free for scientific use from the corresponding author or the journals web site (van Geldern and Barth, 2012). References van Geldern, R. and Barth, J.A.C. (2012) Limnol. Oceanogr. Methods 10:1024-1036 [doi: 10.4319/lom.2012.10.1024

  7. Comparison between measured tissue phantom ratio values and calculated from percent depth doses with and without peak scatter correction factor in a 6 MV beam

    Directory of Open Access Journals (Sweden)

    Ganesh Narayanasamy

    2015-01-01

    Full Text Available The purpose of this study is to examine the accuracy of calculated tissue phantom ratio (TPR data with measured TPR values of a 6MV photon beam. TPR was calculated from the measured percent depth dose (PDD values using 2 methods – with and without correcting for the differences in peak scatter fraction (PSF. Mean error less than 1% was observed between the measured and calculated TPR values with the PSF correction, for all clinically relevant field sizes and depths. When not accounting for the PSF correction, mean difference between the measured and calculated TPR values was larger than 1% for square field sizes ranging from 3 cm to 10 cm.

  8. A Correction Formula for the ST Segment Measurements for the AC-coupled Electrocardiograms

    DEFF Research Database (Denmark)

    Schmid, Ramun; Isaksen, Jonas; Leber, Remo

    2016-01-01

    correction formula can be applied when only four parameters are known: the possibly estimated QRS area A, the QRS duration W, the beat-to-beat interval TRR, and the filter time constant T, further, the time point Tj to correct - after the J point - must be specified. Results: The fomula is correct within 0...

  9. Measurement of vascular permeability in spinal cord using Evans Blue spectrophotometry and correction for turbidity.

    Science.gov (United States)

    Warnick, R E; Fike, J R; Chan, P H; Anderson, D K; Ross, G Y; Gutin, P H

    1995-05-01

    Vascular permeability can be visualized by Evans Blue (EB) extravasation and quantified by spectrophotometry after formamide extraction of the tissue. However, formamide extracts show significant turbidity, which may contribute to the total optical density at the wavelength of measurement (e.g., 620 lambda). We developed a simple method for estimating the component of the total optical density of a dyed specimen contributed by turbidity. Our method, which uses a determination of turbidity made at another point of the light spectrum (740 lambda), was more precise than two other EB quantification techniques. We therefore recommend it for individual correction of formamide extracts of spinal cord specimens. The application of this technique to the brain remains to be determined.

  10. Precision Measurements of the Cluster Red Sequence using an Error Corrected Gaussian Mixture Model

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Jiangang; /Fermilab /Michigan U.; Koester, Benjamin P.; /Chicago U.; Mckay, Timothy A.; /Michigan U.; Rykoff, Eli S.; /UC, Santa Barbara; Rozo, Eduardo; /Ohio State U.; Evrard, August; /Michigan U.; Annis, James; /Fermilab; Becker, Matthew; /Chicago U.; Busha, Michael; /KIPAC, Menlo Park /SLAC; Gerdes, David; /Michigan U.; Johnston, David E.; /Northwestern U. /Brookhaven

    2009-07-01

    The red sequence is an important feature of galaxy clusters and plays a crucial role in optical cluster detection. Measurement of the slope and scatter of the red sequence are affected both by selection of red sequence galaxies and measurement errors. In this paper, we describe a new error corrected Gaussian Mixture Model for red sequence galaxy identification. Using this technique, we can remove the effects of measurement error and extract unbiased information about the intrinsic properties of the red sequence. We use this method to select red sequence galaxies in each of the 13,823 clusters in the maxBCG catalog, and measure the red sequence ridgeline location and scatter of each. These measurements provide precise constraints on the variation of the average red galaxy populations in the observed frame with redshift. We find that the scatter of the red sequence ridgeline increases mildly with redshift, and that the slope decreases with redshift. We also observe that the slope does not strongly depend on cluster richness. Using similar methods, we show that this behavior is mirrored in a spectroscopic sample of field galaxies, further emphasizing that ridgeline properties are independent of environment. These precise measurements serve as an important observational check on simulations and mock galaxy catalogs. The observed trends in the slope and scatter of the red sequence ridgeline with redshift are clues to possible intrinsic evolution of the cluster red-sequence itself. Most importantly, the methods presented in this work lay the groundwork for further improvements in optically-based cluster cosmology.

  11. Does Your Optical Particle Counter Measure What You Think it Does? Calibration and Refractive Index Correction Methods.

    Science.gov (United States)

    Rosenberg, Phil; Dean, Angela; Williams, Paul; Dorsey, James; Minikin, Andreas; Pickering, Martyn; Petzold, Andreas

    2013-04-01

    Optical Particle Counters (OPCs) are the de-facto standard for in-situ measurements of airborne aerosol size distributions and small cloud particles over a wide size range. This is particularly the case on airborne platforms where fast response is important. OPCs measure scattered light from individual particles and generally bin particles according to the measured peak amount of light scattered (the OPC's response). Most manufacturers provide a table along with their instrument which indicates the particle diameters which represent the edges of each bin. It is important to correct the particle size reported by OPCs for the refractive index of the particles being measured, which is often not the same as for those used during calibration. However, the OPC's response is not a monotonic function of particle diameter and obvious problems occur when refractive index corrections are attempted, but multiple diameters correspond to the same OPC response. Here we recommend that OPCs are calibrated in terms of particle scattering cross section as this is a monotonic (usually linear) function of an OPC's response. We present a method for converting a bin's boundaries in terms of scattering cross section into a bin centre and bin width in terms of diameter for any aerosol species for which the scattering properties are known. The relationship between diameter and scattering cross section can be arbitrarily complex and does not need to be monotonic; it can be based on Mie-Lorenz theory or any other scattering theory. Software has been provided on the Sourceforge open source repository for scientific users to implement such methods in their own measurement and calibration routines. As a case study data is presented showing data from Passive Cavity Aerosol Spectrometer Probe (PCASP) and a Cloud Droplet Probe (CDP) calibrated using polystyrene latex spheres and glass beads before being deployed as part of the Fennec project to measure airborne dust in the inaccessible regions of

  12. An Electronic Nose for Reliable Measurement and Correct Classification of Beverages

    Directory of Open Access Journals (Sweden)

    Mahammad A. Hannan

    2011-06-01

    Full Text Available This paper reports the design of an electronic nose (E-nose prototype for reliable measurement and correct classification of beverages. The prototype was developed and fabricated in the laboratory using commercially available metal oxide gas sensors and a temperature sensor. The repeatability, reproducibility and discriminative ability of the developed E-nose prototype were tested on odors emanating from different beverages such as blackcurrant juice, mango juice and orange juice, respectively. Repeated measurements of three beverages showed very high correlation (r > 0.97 between the same beverages to verify the repeatability. The prototype also produced highly correlated patterns (r > 0.97 in the measurement of beverages using different sensor batches to verify its reproducibility. The E-nose prototype also possessed good discriminative ability whereby it was able to produce different patterns for different beverages, different milk heat treatments (ultra high temperature, pasteurization and fresh and spoiled milks. The discriminative ability of the E-nose was evaluated using Principal Component Analysis and a Multi Layer Perception Neural Network, with both methods showing good classification results.

  13. Impact of and correction for instrument sensitivity drift on nanoparticle size measurements by single-particle ICP-MS.

    Science.gov (United States)

    El Hadri, Hind; Petersen, Elijah J; Winchester, Michael R

    2016-07-01

    The effect of ICP-MS instrument sensitivity drift on the accuracy of nanoparticle (NP) size measurements using single particle (sp)ICP-MS is investigated. Theoretical modeling and experimental measurements of the impact of instrument sensitivity drift are in agreement and indicate that drift can impact the measured size of spherical NPs by up to 25 %. Given this substantial bias in the measured size, a method was developed using an internal standard to correct for the impact of drift and was shown to accurately correct for a decrease in instrument sensitivity of up to 50 % for 30 and 60 nm gold nanoparticles. Graphical Abstract Correction of nanoparticle size measurement by spICP-MS using an internal standard.

  14. Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Treado, Colleen J.; /Massachusetts U., Amherst

    2012-09-07

    The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

  15. The main injector chromaticity correction sextupole magnets: Measurements and operating schemes

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; Bogacz, A.; Brown, B.C.; Harding, D.J.; Fang, S.J.; Martin, P.S.; Glass, H.D.; Sim, J.

    1995-05-01

    The Fermilab Main Injector (FMI) is a high intensity proton synchrotron which will be used to accelerate protons and antiprotons from 8.9 GeV/c to 150 GeV/c. The natural chromaticities of the machine for the horizontal and the vertical Planes are {minus}33.6 and {minus}33.9 respectively. The {Delta}p/p of the beam at injection is about 0.002. The chromaticity requirements of the FMI, are primarily decided by the {Delta}p/p = 0.002 of the beam at injection. This limits the final chromaticity of the FMI to be {plus_minus}5 units. To correct the chromaticity in the FMI two families of sextupole magnets will be installed in the lattice, one for each plane. A sextupole magnet suitable for the FMI needs has been designed and a number of them are being built. New chromaticity compensation schemes have been worked out in the light of recently proposed faster acceleration ramps. On an R/D sextupole magnet the low current measurements have been carried out to determine the electrical properties. Also, using a Morgan coil, measurements have been performed to determine the higher ordered multipole components up to 18-poles. An overview of these result are presented here.

  16. Differences in aerosol absorption Ångström exponents between correction algorithms for a particle soot absorption photometer measured on the South African Highveld

    Science.gov (United States)

    Backman, J.; Virkkula, A.; Vakkari, V.; Beukes, J. P.; Van Zyl, P. G.; Josipovic, M.; Piketh, S.; Tiitta, P.; Chiloane, K.; Petäjä, T.; Kulmala, M.; Laakso, L.

    2014-12-01

    Absorption Ångström exponents (AAEs) calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example, to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are widely used and are common at aerosol monitoring stations globally. Several correction algorithms are used to account for artefacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are substantial differences between the AAEs calculated from these corrections. Depending on the used correction, AAEs can change by as much as 46%. The study also highlights that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol when using the same data set. The AAE ranged between 1.17 for non-corrected data to 1.96 for the correction that gave the greatest values. Furthermore, the study implies that the AAEs reported for a site depend on at which filter transmittance the filter is changed. In this work, the AAEs were calculated from data measured with a three-wavelength particle soot absorption photometer (PSAP) at Elandsfontein on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals, by a factor of 15. The correlation coefficient between the dilution-corrected PSAP and a non-diluted Multi-Angle Absorption Photometer (MAAP) was 0.9. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites that are not often visited or suffer from high levels of pollution.

  17. Should Studies of Diabetes Treatment Stratification Correct for Baseline HbA1c?

    Directory of Open Access Journals (Sweden)

    Angus G Jones

    Full Text Available Baseline HbA1c is a major predictor of response to glucose lowering therapy and therefore a potential confounder in studies aiming to identify other predictors. However, baseline adjustment may introduce error if the association between baseline HbA1c and response is substantially due to measurement error and regression to the mean. We aimed to determine whether studies of predictors of response should adjust for baseline HbA1c.We assessed the relationship between baseline HbA1c and glycaemic response in 257 participants treated with GLP-1R agonists and assessed whether it reflected measurement error and regression to the mean using duplicate 'pre-baseline' HbA1c measurements not included in the response variable. In this cohort and an additional 2659 participants treated with sulfonylureas we assessed the relationship between covariates associated with baseline HbA1c and treatment response with and without baseline adjustment, and with a bias correction using pre-baseline HbA1c to adjust for the effects of error in baseline HbA1c.Baseline HbA1c was a major predictor of response (R2 = 0.19,β = -0.44,p<0.001.The association between pre-baseline and response was similar suggesting the greater response at higher baseline HbA1cs is not mainly due to measurement error and subsequent regression to the mean. In unadjusted analysis in both cohorts, factors associated with baseline HbA1c were associated with response, however these associations were weak or absent after adjustment for baseline HbA1c. Bias correction did not substantially alter associations.Adjustment for the baseline HbA1c measurement is a simple and effective way to reduce bias in studies of predictors of response to glucose lowering therapy.

  18. Analysis of measured data of human body based on error correcting frequency

    Science.gov (United States)

    Jin, Aiyan; Peipei, Gao; Shang, Xiaomei

    2014-04-01

    Anthropometry is to measure all parts of human body surface, and the measured data is the basis of analysis and study of the human body, establishment and modification of garment size and formulation and implementation of online clothing store. In this paper, several groups of the measured data are gained, and analysis of data error is gotten by analyzing the error frequency and using analysis of variance method in mathematical statistics method. Determination of the measured data accuracy and the difficulty of measured parts of human body, further studies of the causes of data errors, and summarization of the key points to minimize errors possibly are also mentioned in the paper. This paper analyses the measured data based on error frequency, and in a way , it provides certain reference elements to promote the garment industry development.

  19. Self-attenuation correction factors for bioindicators measured by gamma spectrometry for energies <100keV

    Energy Technology Data Exchange (ETDEWEB)

    Manduci, L., E-mail: manduci@orange.f [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); Tenailleau, L. [GEA, Groupe d' Etudes Atomiques, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); Trolet, J.L. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); De Vismes, A. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); IRSN/DEI/STEME/LMRE, Bois des Rames Bt 501, 91400 Orsay (France); Lopez, G.; Piccione, M. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France)

    2010-01-21

    The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using gamma spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

  20. Sensitivities of various probe correction techniques to noise and inaccurate channel balance in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Pivnenko, Sergey; Breinbjerg, Olav

    2005-01-01

    Sensitivities of various probe correction techniques to noise and inaccurate channel balance in the spherical near-field antenna measurements are investigated. The simulation results show the level of uncertainty in the determination of the directivity of an antenna in the presence of -60 dB noise......, and as a function of the level of error in the channel balance for the different probe correction techniques....

  1. Surface finish measurement studies

    Science.gov (United States)

    Teague, E. C.

    1983-01-01

    The performance of stylus instruments for measuring the topography of National Transonic Facility (NTF) model surfaces both for monitoring during fabrication and as an absolute measurement of topography was evaluated. It was found that the shop-grade instruments can damage the surface of models and that their use for monitoring fabrication procedures can lead to surface finishes that are substantially out of range in critical areas of the leading edges. The development of a prototype light-scattering instrument which would allow for rapid assessment of the surface finish of a model is also discussed.

  2. Method Specific Calibration Corrects for DNA Extraction Method Effects on Relative Telomere Length Measurements by Quantitative PCR

    Science.gov (United States)

    Holland, Rebecca; Underwood, Sarah; Fairlie, Jennifer; Psifidi, Androniki; Ilska, Joanna J.; Bagnall, Ainsley; Whitelaw, Bruce; Coffey, Mike; Banos, Georgios; Nussey, Daniel H.

    2016-01-01

    Telomere length (TL) is increasingly being used as a biomarker in epidemiological, biomedical and ecological studies. A wide range of DNA extraction techniques have been used in telomere experiments and recent quantitative PCR (qPCR) based studies suggest that the choice of DNA extraction method may influence average relative TL (RTL) measurements. Such extraction method effects may limit the use of historically collected DNA samples extracted with different methods. However, if extraction method effects are systematic an extraction method specific (MS) calibrator might be able to correct for them, because systematic effects would influence the calibrator sample in the same way as all other samples. In the present study we tested whether leukocyte RTL in blood samples from Holstein Friesian cattle and Soay sheep measured by qPCR was influenced by DNA extraction method and whether MS calibration could account for any observed differences. We compared two silica membrane-based DNA extraction kits and a salting out method. All extraction methods were optimized to yield enough high quality DNA for TL measurement. In both species we found that silica membrane-based DNA extraction methods produced shorter RTL measurements than the non-membrane-based method when calibrated against an identical calibrator. However, these differences were not statistically detectable when a MS calibrator was used to calculate RTL. This approach produced RTL measurements that were highly correlated across extraction methods (r > 0.76) and had coefficients of variation lower than 10% across plates of identical samples extracted by different methods. Our results are consistent with previous findings that popular membrane-based DNA extraction methods may lead to shorter RTL measurements than non-membrane-based methods. However, we also demonstrate that these differences can be accounted for by using an extraction method-specific calibrator, offering researchers a simple means of accounting for

  3. Method Specific Calibration Corrects for DNA Extraction Method Effects on Relative Telomere Length Measurements by Quantitative PCR.

    Science.gov (United States)

    Seeker, Luise A; Holland, Rebecca; Underwood, Sarah; Fairlie, Jennifer; Psifidi, Androniki; Ilska, Joanna J; Bagnall, Ainsley; Whitelaw, Bruce; Coffey, Mike; Banos, Georgios; Nussey, Daniel H

    2016-01-01

    Telomere length (TL) is increasingly being used as a biomarker in epidemiological, biomedical and ecological studies. A wide range of DNA extraction techniques have been used in telomere experiments and recent quantitative PCR (qPCR) based studies suggest that the choice of DNA extraction method may influence average relative TL (RTL) measurements. Such extraction method effects may limit the use of historically collected DNA samples extracted with different methods. However, if extraction method effects are systematic an extraction method specific (MS) calibrator might be able to correct for them, because systematic effects would influence the calibrator sample in the same way as all other samples. In the present study we tested whether leukocyte RTL in blood samples from Holstein Friesian cattle and Soay sheep measured by qPCR was influenced by DNA extraction method and whether MS calibration could account for any observed differences. We compared two silica membrane-based DNA extraction kits and a salting out method. All extraction methods were optimized to yield enough high quality DNA for TL measurement. In both species we found that silica membrane-based DNA extraction methods produced shorter RTL measurements than the non-membrane-based method when calibrated against an identical calibrator. However, these differences were not statistically detectable when a MS calibrator was used to calculate RTL. This approach produced RTL measurements that were highly correlated across extraction methods (r > 0.76) and had coefficients of variation lower than 10% across plates of identical samples extracted by different methods. Our results are consistent with previous findings that popular membrane-based DNA extraction methods may lead to shorter RTL measurements than non-membrane-based methods. However, we also demonstrate that these differences can be accounted for by using an extraction method-specific calibrator, offering researchers a simple means of accounting for

  4. Library-based scatter correction for dedicated cone beam breast CT: a feasibility study

    Science.gov (United States)

    Shi, Linxi; Vedantham, Srinivasan; Karellas, Andrew; Zhu, Lei

    2016-04-01

    Purpose: Scatter errors are detrimental to cone-beam breast CT (CBBCT) accuracy and obscure the visibility of calcifications and soft-tissue lesions. In this work, we propose practical yet effective scatter correction for CBBCT using a library-based method and investigate its feasibility via small-group patient studies. Method: Based on a simplified breast model with varying breast sizes, we generate a scatter library using Monte-Carlo (MC) simulation. Breasts are approximated as semi-ellipsoids with homogeneous glandular/adipose tissue mixture. On each patient CBBCT projection dataset, an initial estimate of scatter distribution is selected from the pre-computed scatter library by measuring the corresponding breast size on raw projections and the glandular fraction on a first-pass CBBCT reconstruction. Then the selected scatter distribution is modified by estimating the spatial translation of the breast between MC simulation and the clinical scan. Scatter correction is finally performed by subtracting the estimated scatter from raw projections. Results: On two sets of clinical patient CBBCT data with different breast sizes, the proposed method effectively reduces cupping artifact and improves the image contrast by an average factor of 2, with an efficient processing time of 200ms per conebeam projection. Conclusion: Compared with existing scatter correction approaches on CBBCT, the proposed library-based method is clinically advantageous in that it requires no additional scans or hardware modifications. As the MC simulations are pre-computed, our method achieves a high computational efficiency on each patient dataset. The library-based method has shown great promise as a practical tool for effective scatter correction on clinical CBBCT.

  5. A Study of IR Loss Correction Methodologies for Commercially Available Pyranometers

    Energy Technology Data Exchange (ETDEWEB)

    Long, Chuck; Andreas, Afshin; Augustine, John; Dooraghi, Mike; Habte, Aron; Hall, Emiel; Kutchenreiter, Mark; McComiskey, Allison; Reda, Ibrahim; Sengupta, Manajit

    2017-03-24

    This presentation provides a high-level overview of a study of IR Loss Connection Methodologies for Commercially Available Pyranometers. The IR Loss Corrections Study is investigating how various correction methodologies work for several makes and models of commercially available pyranometers in common use, both when operated in ventilators with DC fans and without ventilators, as when they are typically calibrated.

  6. Increasing the accuracy and temporal resolution of two-filter radon-222 measurements by correcting for the instrument response

    Science.gov (United States)

    Griffiths, Alan D.; Chambers, Scott D.; Williams, Alastair G.; Werczynski, Sylvester

    2016-06-01

    Dual-flow-loop two-filter radon detectors have a slow time response, which can affect the interpretation of their output when making continuous observations of near-surface atmospheric radon concentrations. While concentrations are routinely reported hourly, a calibrated model of detector performance shows that ˜ 40 % of the signal arrives more than an hour after a radon pulse is delivered. After investigating several possible ways to correct for the detector's slow time response, we show that a Bayesian approach using a Markov chain Monte Carlo sampler is an effective method. After deconvolution, the detector's output is redistributed into the appropriate counting interval and a 10 min temporal resolution can be achieved under test conditions when the radon concentration is controlled. In the case of existing archived observations, collected under less ideal conditions, the data can be retrospectively reprocessed at 30 min resolution. In one case study, we demonstrate that a deconvolved radon time series was consistent with the following: measurements from a fast-response carbon dioxide monitor; grab samples from an aircraft; and a simple mixing height model. In another case study, during a period of stable nights and days with well-developed convective boundary layers, a bias of 18 % in the mean daily minimum radon concentration was eliminated by correcting for the instrument response.

  7. A First/Third-Order Probe Correction Technique for Spherical Near-Field Antenna Measurements Using Three Probe Orientations

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Breinbjerg, Olav

    2008-01-01

    A probe correction technique is described for spherical near-field antenna measurements based on sampling the near field for three probe orientations in each measurement direction. The technique applies to odd-order probes whose radiated field contains (significant) power only in the first (µ=±1)...

  8. Occupational stress and mental health among correctional officers: a cross-sectional study.

    Science.gov (United States)

    Ghaddar, Ali; Mateo, Inmaculada; Sanchez, Pablo

    2008-01-01

    A harsh psychosocial environment in the workplace might cause adverse health events, but the association has not been well demonstrated in the penitentiary environment. This cross-sectional study was designed to explore the association between workplace psychosocial risks and the mental health of correctional officers in a Spanish penitentiary center. A self-administered questionnaire was distributed to correctional officers. A total of 164 responded anonymously (response rate 43%). The SF36 survey was used to measure mental health and ISTAS21 (Spanish version of Copenhagen Psychosocial Questionnaire) was used to measure exposure to workplace psychosocial conditions. Low scores were obtained for mental health, high scores were obtained for psychological demands, low self-esteem, and low control and influence and moderate scores for low social support, double exposure, and insecurity at work. A linear regression analysis was constructed to study the influence of workplace psychosocial conditions (independent variables) on mental health (dependent variable). The effect was adjusted for sex, age, seniority, and occupational group. Psychological demands (highest impact), low control and influence, and double exposure had significant inverse associations with mental health. The association between low social support, low self-esteem, and insecurity at work with mental health was insignificant. Psychosocial work conditions are a potential target for mental health promotion programs at work.

  9. 77 FR 3121 - Program Integrity: Gainful Employment-Debt Measures; Correction

    Science.gov (United States)

    2012-01-23

    ... regulations, the errors resulting from this misapplication. We do not change the regression analysis model... retention rates. Correcting this language does not change the regression analysis model itself or the... in repayment rates.'' On page 34461, second column, first full paragraph, we correct the phrase...

  10. On the truncation of the azimuthal mode spectrum of high-order probes in probe-corrected spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Laitinen, Tommi

    2011-01-01

    Azimuthal mode (m mode) truncation of a high-order probe pattern in probe-corrected spherical near-field antenna measurements is studied in this paper. The results of this paper provide rules for appropriate and sufficient m-mode truncation for non-ideal first-order probes and odd-order probes wi...

  11. Measurement of the Lick indices in early-type galaxies: Line-of-sight velocity distribution corrections for IC 1459

    Directory of Open Access Journals (Sweden)

    Samurović Srđan

    2009-01-01

    Full Text Available In this paper we analyze the measurements of the absorption line-strength Lick indices in the early-type galaxy IC 1459. We use the long-slit spectra of the elliptical galaxy IC 1459 from which its kinematics had previously been extracted to calculate the Lick indices for the observed spectral region (Mg2, Fe5270, Fe5335 and Hβ. We apply the usual procedure and correct the indices to the Lick spectral resolution and for the zero velocity dispersion. The procedure applied in this paper also corrects to non-Gaussian line-of-sight velocity distribution (LOSVD observed in this galaxy, especially in its outer parts. The findings of Kuntschner (2004 were tested and it is shown that the departures from the Gaussian LOSVD may indeed cause erroneous determinations of the Lick indices. The impact of the introduction of non-Gaussian LOSVD differs for different indices. For the galaxy IC 1459 it is shown that the iron indices are especially sensitive when the correction due to anistropies is introduced: the corrections for Fe5270 and Fe5335 are ~10 and ~19 percent larger, respectively, than the corrections obtained in case of a pure Gaussian. The corrections for Mg2 index are shown to be negligible and the corrections of the Hβ index due to anisotropies are also small (below ~ 4 per cent at most.

  12. Reducing overlay sampling for APC-based correction per exposure by replacing measured data with computational prediction

    Science.gov (United States)

    Noyes, Ben F.; Mokaberi, Babak; Oh, Jong Hun; Kim, Hyun Sik; Sung, Jun Ha; Kea, Marc

    2016-03-01

    One of the keys to successful mass production of sub-20nm nodes in the semiconductor industry is the development of an overlay correction strategy that can meet specifications, reduce the number of layers that require dedicated chuck overlay, and minimize measurement time. Three important aspects of this strategy are: correction per exposure (CPE), integrated metrology (IM), and the prioritization of automated correction over manual subrecipes. The first and third aspects are accomplished through an APC system that uses measurements from production lots to generate CPE corrections that are dynamically applied to future lots. The drawback of this method is that production overlay sampling must be extremely high in order to provide the system with enough data to generate CPE. That drawback makes IM particularly difficult because of the throughput impact that can be created on expensive bottleneck photolithography process tools. The goal is to realize the cycle time and feedback benefits of IM coupled with the enhanced overlay correction capability of automated CPE without impacting process tool throughput. This paper will discuss the development of a system that sends measured data with reduced sampling via an optimized layout to the exposure tool's computational modelling platform to predict and create "upsampled" overlay data in a customizable output layout that is compatible with the fab user CPE APC system. The result is dynamic CPE without the burden of extensive measurement time, which leads to increased utilization of IM.

  13. First Industrial Tests of a Drum Monitor Matrix Correction for the Fissile Mass Measurement in Large Volume Historic Metallic Residues with the Differential Die-away Technique

    Energy Technology Data Exchange (ETDEWEB)

    Antoni, R.; Passard, C.; Perot, B.; Batifol, M.; Vandamme, J.C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 St Paul-lez-Durance, (France); Grassi, G. [AREVA NC, 1 place Jean-Millier, 92084 Paris-La-Defense cedex (France)

    2015-07-01

    The fissile mass in radioactive waste drums filled with compacted metallic residues (spent fuel hulls and nozzles) produced at AREVA La Hague reprocessing plant is measured by neutron interrogation with the Differential Die-away measurement Technique (DDT. In the next years, old hulls and nozzles mixed with Ion-Exchange Resins will be measured. The ion-exchange resins increase neutron moderation in the matrix, compared to the waste measured in the current process. In this context, the Nuclear Measurement Laboratory (NML) of CEA Cadarache has studied a matrix effect correction method, based on a drum monitor ({sup 3}He proportional counter inside the measurement cavity). A previous study performed with the NML R and D measurement cell PROMETHEE 6 has shown the feasibility of method, and the capability of MCNP simulations to correctly reproduce experimental data and to assess the performances of the proposed correction. A next step of the study has focused on the performance assessment of the method on the industrial station using numerical simulation. A correlation between the prompt calibration coefficient of the {sup 239}Pu signal and the drum monitor signal was established using the MCNPX computer code and a fractional factorial experimental design composed of matrix parameters representative of the variation range of historical waste. Calculations have showed that the method allows the assay of the fissile mass with an uncertainty within a factor of 2, while the matrix effect without correction ranges on 2 decades. In this paper, we present and discuss the first experimental tests on the industrial ACC measurement system. A calculation vs. experiment benchmark has been achieved by performing dedicated calibration measurement with a representative drum and {sup 235}U samples. The preliminary comparison between calculation and experiment shows a satisfactory agreement for the drum monitor. The final objective of this work is to confirm the reliability of the

  14. Missed radiative corrections in muon g-2 and proton charge radius measurements

    Directory of Open Access Journals (Sweden)

    Arbuzov Andrej

    2016-01-01

    Full Text Available QED radiative corrections to the muon anomalous magnetic moment and elastic electron-proton scattering are discussed. It is shown that a collective effect due to mutual interaction of muons within experimental conditions might provide a contribution to the observed muon magnetic moment. This effect is parameterized by an effective mean shift of muons off their mass shells. Higher order corrections to elastic electronproton at low energies are systematically treated within the leading and next-to-leading logarithmic approximation. The corrections are relevant for the modern experiments on proton form factor and charge radius definition.

  15. Measurement and Multiple Scattering Correction of K-Shell Ionization Cross Sections of Silver by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chang-Geng; FU Yu-Chuan; AN Zhu; TANG Chang-Huan; LUO Zheng-Ming

    2001-01-01

    The K-shell ionization cross sections of silver have been measured by electron impact. In order to overcomethe difliculties in. Preparing a self-supporting thin targets, a thin target with a thick substrate was used inour experiments. The influence of electrons reflected from the substrate was corrected by means of a detailed calculation of electron transport. The path of the electrons passing through the silver target of 31.2 μg/cm2 wascalculated by the EGS4 Monte Carlo program. This method of correction for the measurement is reported for the first time.

  16. Decreasing range resolution of a SAR image to permit correction of motion measurement errors beyond the SAR range resolution

    Science.gov (United States)

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2010-07-20

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  17. An Experimental Study of Corrective Feedback during Video-Conferencing

    Science.gov (United States)

    Monteiro, Kátia

    2014-01-01

    This study investigated the effectiveness of oral metalinguistic feedback and recasts as well as the effect of focused tasks (FT) in the development of implicit and explicit knowledge during video-conference interactions. This was accomplished by partial replication of a study performed in a classroom setting. Three groups of Brazilian EFL…

  18. Differences in aerosol absorption Ångström exponents between correction algorithms for particle soot absorption photometer measured on South African Highveld

    Directory of Open Access Journals (Sweden)

    J. Backman

    2014-09-01

    Full Text Available Absorption Ångstrom exponents (AAE calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are a widely used method and are commonly used at aerosol monitoring stations globally. Several correction algorithms are used to account for the artifacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are significant differences between the AAEs calculated from these corrections. The study also shows that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol for the same data set. In this work the AAEs were calculated from data measured with a three-wavelength Particle Soot Absorption Photometer (PSAP at Elandsfontein on deployed on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals. The dilution-corrected PSAP showed a good agreement with a non-diluted MAAP. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites are not often visited or suffer from high levels of pollution.

  19. Differences in aerosol absorption Ångström exponents between correction algorithms for particle soot absorption photometer measured on South African Highveld

    Science.gov (United States)

    Backman, J.; Virkkula, A.; Vakkari, V.; Beukes, J. P.; Van Zyl, P.; Josipovic, M.; Piketh, S.; Tiitta, P.; Chiloane, K.; Petäjä, T.; Kulmala, M.; Laakso, L.

    2014-09-01

    Absorption Ångstrom exponents (AAE) calculated from filter-based absorption measurements are often used to give information on the origin of the ambient aerosol, for example to distinguish between urban pollution and biomass burning aerosol. Filter-based absorption measurements are a widely used method and are commonly used at aerosol monitoring stations globally. Several correction algorithms are used to account for the artifacts associated with filter-based absorption techniques. These algorithms are of profound importance when determining the absolute amount of absorption by the aerosol. However, this study shows that there are significant differences between the AAEs calculated from these corrections. The study also shows that the difference between AAEs calculated using different corrections can lead to conflicting conclusions on the type of aerosol for the same data set. In this work the AAEs were calculated from data measured with a three-wavelength Particle Soot Absorption Photometer (PSAP) at Elandsfontein on deployed on the South African Highveld for 23 months. The sample air of the PSAP was diluted to prolong filter change intervals. The dilution-corrected PSAP showed a good agreement with a non-diluted MAAP. Thus, the study also shows that the applicability of the PSAP can be extended to remote sites are not often visited or suffer from high levels of pollution.

  20. Drift-corrected trends and periodic variations in MIPAS IMK/IAA ozone measurements

    Directory of Open Access Journals (Sweden)

    E. Eckert

    2013-07-01

    Full Text Available Drifts, trends and periodic variations were calculated from monthly zonally averaged ozone profiles. The ozone profiles, among many other species, were derived from level-1b data of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS by means of the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT, Institute for Meteorlogy and Climate Research (IMK. All trend and drift analyses were performed using a multilinear parametric trend model which includes a linear term, several harmonics with period lengths from three to twenty four months and the quasi-biennial oscillation (QBO. Drifts at 2-sigma significance level were mainly negative for ozone relative to Aura MLS and Odin OSIRIS and negative or near zero for most of the comparisons to Lidar measurements. Lidar stations used here include those at Hohenpeissenberg (47.8° N, 11.0° E, Lauder (45.0° S, 169.7° E, Mauna Loa (19.5° N, 155.6° W, Observatoire Haute Provence (43.9° N, 5.7° E and Table Mountain (34.4° N, 117.7° W. Drifts against ACE-FTS were found to be mostly insignificant. The assessed MIPAS ozone trends cover the time period of July 2002 to April 2012 and range from -0.5 ppmv decade-1 to +0.5 ppmv decade-1 depending on altitude and latitude. From the drift analyses we derive that the real ozone trends might be slighly more positive/less negative than those calculated from the MIPAS data, by conceding the possibility of MIPAS having a very small (approx. within -0.3 ppmv decade-1 negative drift for ozone. This leads to drift-corrected trends of -0.4 ppmv decade-1 to +0.55 ppmv decade-1 for the time period covered by MIPAS Envisat measurements with very few negative and large areas of positive trends, which is in good agreement with recent literature. Differences of the trends compared with recent literature could be explained by a possible shift of the subtropical mixing barriers. Results for the altitude-latitude distribution of

  1. Study of Reed-Solomon correction for mass memory

    Science.gov (United States)

    Newman, B.; Hutton, S. J.

    1992-03-01

    Logica has performed a study of Reed-Solomon coding in the context of protecting a mass memory in the harsh space environment, e.g., against galactic cosmic rays and heavy ion rich solar flares. The study examined the relation between the final bit error rate, the rate at which the code is used to scrub errors from the memory, and the rate at which errors occur. The RS(255,252) code was considered.

  2. Using Correction Equations Based on Measured Height and Weight Weakens Associations between Obesity Based on Self-Reports and Chronic Diseases

    Directory of Open Access Journals (Sweden)

    Cynthia L. Murray

    2013-01-01

    Full Text Available Objective. Researchers have established a preponderance of height overestimation among men and weight underestimation among women in self-reported anthropometric data, which skews obesity prevalence data and obscures obesity-chronic disease relationships. The objective of this study was to reevaluate associations between obesity and chronic diseases using body mass index (BMI correction equations derived from measured data. Methods. Measured height and weight (MHW data were collected on a subsample of the 17,126 Atlantic Canadians who participated in the 2007-2008 Canadian Community Health Survey (CCHS. To obtain corrected BMI estimates for the 17,126 adults, correction equations were developed in the MHW subsample and multiple regression procedures were used to model BMI. To test obesity-chronic disease relationships, logistic regression models were utilized. Results. The correction procedure eliminated statistically significant relations (P<0.05 between obesity and chronic bronchitis and obesity and stroke. Also, correction attenuated many relationships between adiposity and chronic disease. For example, among obese adults, there was a 13%, 12%, and 7% reduction in the adjusted odds ratios for asthma, urinary incontinence, and cardiovascular disease, respectively. Conclusion. Further research is needed to fully understand how the usage of self-reported data alters our understanding of the relationships between overweight or obesity and chronic diseases.

  3. Wheel skid correction is a prerequisite to reliably measure wheelchair sports kinematics based on inertial sensors

    NARCIS (Netherlands)

    Van der Slikke, R.M.A.; Berger, M.A.M.; Bregman, D.J.J.; Veeger, H.E.J.

    2015-01-01

    Accurate knowledge of wheelchair kinematics during a match could be a significant factor in performance improvement in wheelchair basketball. To date, most systems for measuring wheelchair kinematics are not suitable for match applications or lack detail in key kinematic outcomes. This study describ

  4. Wheel skid correction is a prerequisite to reliably measure wheelchair sports kinematics based on inertial sensors

    NARCIS (Netherlands)

    Van der Slikke, R.M.A.; Berger, M.A.M.; Bregman, D.J.J.; Veeger, H.E.J.

    2015-01-01

    Accurate knowledge of wheelchair kinematics during a match could be a significant factor in performance improvement in wheelchair basketball. To date, most systems for measuring wheelchair kinematics are not suitable for match applications or lack detail in key kinematic outcomes. This study

  5. Wheel skid correction is a prerequisite to reliably measure wheelchair sports kinematics based on inertial sensors

    NARCIS (Netherlands)

    Van der Slikke, R.M.A.; Berger, M.A.M.; Bregman, D.J.J.; Veeger, H.E.J.

    2015-01-01

    Accurate knowledge of wheelchair kinematics during a match could be a significant factor in performance improvement in wheelchair basketball. To date, most systems for measuring wheelchair kinematics are not suitable for match applications or lack detail in key kinematic outcomes. This study describ

  6. Sampling variability of computer-aided fractal-corrected measures of liver fibrosis in needle biopsy specimens

    Institute of Scientific and Technical Information of China (English)

    Fabio Grizzi; Carlo Russo; Barbara Franceschini; Mariagrazia Di Rocco; Valter Torri; Emanuela Morenghi; Luigi Rainiero Fassati; Nicola Dioguardi

    2006-01-01

    AIM: To assess the sampling variability of computeraided, fractal-corrected measures of fibrosis in liver biopsies.METHODS: Samples were derived from six to eight different parts of livers removed from 12 patients with clinically and histologically proven cirrhosis undergoing orthotopic liver transplantation. Sirius red-stained sections with a thickness of 2 μm were digitized using a computer-aided image analysis system that automatically measures the surface of fibrosis, as well as its outline perimeter, fractal surface and outline dimensions,wrinkledness, and Hurst coefficient.RESULTS: We found a high degree of inter-sample variability in the measurements of the surface [coefficient of variation (CV) = 43% ± 13%] and wrinkledness (CV = 28% ± 9%) of fibrosis, but the inter-sample variability of Hurst's exponent was low (CV = 14% ± 2%).CONCLUSION: This study suggests that Hurst's exponent might be used in clinical practice as the best histological estimate of fibrosis in the whole organ,and evidences the fact that biopsy sections, which are fundamental for the qualitative diagnosis of chronic hepatitis, play a key role in the quantitative estimate of architectural changes in liver tissue.

  7. Measurement and Correction of K-Shell Ionization Cross Sections for Copper and Gallium by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    周长庚; 安竹; 罗正明

    2001-01-01

    The K-shell ionization cross sections of Cu and Ga are measured by electron impact and the data of Ga arereported for the first time. The method of a thin chemical compound target with a thick substrate is formallyused in the experiment. The influence of electrons reflected from the substrate is corrected by means of acalculation of electron transport.

  8. A Correction for the Epsilon Approximate Test in Repeated Measures Designs with Two or More Independent Groups.

    Science.gov (United States)

    Lecoutre, Bruno

    1991-01-01

    The routine epsilon approximate test in repeated measures designs when the condition of circularity is unfulfilled uses an erroneous formula in the case of two or more groups. Because this may lead to underestimation of the deviation from circularity when the subject number is small, a correction is proposed. (Author/SLD)

  9. The File. Case Study in Correction (1977-1979).

    Science.gov (United States)

    Lang, Serge

    In reaction to the 1977 Survey of the American Professoriate by Everett C. Ladd and Seymour Martin Lipset, Serge Lang began a file of letters expressing concern over and opposition to the study. The controversy began when Lang wrote a letter to the researchers expressing his opposition, with copies to members of the academic community,…

  10. The File. Case Study in Correction (1977-1979).

    Science.gov (United States)

    Lang, Serge

    In reaction to the 1977 Survey of the American Professoriate by Everett C. Ladd and Seymour Martin Lipset, Serge Lang began a file of letters expressing concern over and opposition to the study. The controversy began when Lang wrote a letter to the researchers expressing his opposition, with copies to members of the academic community,…

  11. Aberration corrected STEM to study an ancient hair dyeing formula

    Science.gov (United States)

    Patriarche, G.; Van Elslande, E.; Castaing, J.; Walter, P.

    2014-05-01

    Lead-based chemistry was initiated in ancient Egypt for cosmetic preparation more than 4000 years ago. Here, we study a hair-dyeing recipe using lead salts described in text since Greco-Roman times. We report direct evidence about the shape and distribution of PbS nanocrystals that form within the hair during blackening.

  12. Improving sap flux density measurements by correctly determining thermal diffusivity, differentiating between bound and unbound water.

    Science.gov (United States)

    Vandegehuchte, Maurits W; Steppe, Kathy

    2012-07-01

    Several heat-based sap flow methods, such as the heat field deformation method and the heat ratio method, include the thermal diffusivity D of the sapwood as a crucial parameter. Despite its importance, little attention has been paid to determine D in a plant physiological context. Therefore, D is mostly set as a constant, calculated during zero flow conditions or from a method of mixtures, taking into account wood density and moisture content. In this latter method, however, the meaning of the moisture content is misinterpreted, making it theoretically incorrect for D calculations in sapwood. A correction to this method, which includes the correct application of the moisture content, is proposed. This correction was tested for European and American beech and Eucalyptus caliginosa Blakely & McKie. Depending on the dry wood density and moisture content, the original approach over- or underestimates D and, hence, sap flux density by 10% and more.

  13. Biopsy site selfies--a quality improvement pilot study to assist with correct surgical site identification.

    Science.gov (United States)

    Nijhawan, Rajiv I; Lee, Erica H; Nehal, Kishwer S

    2015-04-01

    Determining the biopsy site location of a skin cancer before treatment is often challenging. To study the implementation and effectiveness of biopsy site selfies as a quality improvement measure for correct surgical site identification. In the first phase, the ability of dermatologic surgeon and patient to definitively identify the biopsy site and whether photography was needed to ensure site agreement were recorded. In the second phase, patients were requested to take biopsy site selfies, and after implementation, similar data were collected including whether a biopsy site selfie was helpful for definitive site identification. In the first phase, the physician and patient were unable to identify the biopsy site 17.6% (49/278) and 25.5% (71/278) of cases, respectively. A photograph was needed in 22.7% of cases (63/278). After implementation of biopsy site selfies, the physician and patient were unable to identify the biopsy site 17.4% (23/132) and 15.2% (20/132) of cases, respectively. Biopsy site selfies were available for 64.1% of cases for which no internal image was available and critical for site identification in 21.4% of these cases. Biopsy site selfies has proven to be helpful for correct surgical site identification by both the physician and the patient and may also provide further reassurance and confidence for patients.

  14. Deepbite correction with incisor intrusion in adults: a long-term cephalometric study.

    Science.gov (United States)

    Kale Varlık, Selin; Onur Alpakan, Ödül; Türköz, Çağrı

    2013-09-01

    The purpose of this study was to investigate the long-term stability of deep overbite correction with mandibular incisor intrusion with utility arches in adult patients. Pretreatment, posttreatment, and 5-years postretention lateral cephalograms of 31 patients (mean age, 26.8 years; range, 24.1-30.9 years) with Class II Division 1 malocclusion and deepbite, treated by maxillary first premolar extraction and mandibular incisor intrusion, were traced and measured. Significant decreases in overjet and overbite (6.4 ± 1.2 and 3.9 ± 0.7 mm, respectively), significant retroclination (17° ± 1.9°) and retraction (3.8 ± 1.1 mm) of the maxillary incisors, and significant increases in protrusion (0.8 ± 1.5 mm), proclination (0.6° ± 0.9°), and intrusion (2.6 ± 1.4 mm) of the mandibular incisors were observed at posttreatment. At postretention, there were statistically significant but clinically unimportant increases in overjet and overbite (0.4 ± 0.2 and 0.8 ± 0.4 mm, respectively) and extrusion of the mandibular incisors (0.8 ± 1.1 mm). Correction of deepbite in nongrowing patients by mandibular incisor intrusion with a utility arch can be considered effective and stable. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  15. Correction: Understanding metal homeostasis in primary cultured neurons. Studies using single neuron subcellular and quantitative metallomics.

    Science.gov (United States)

    Colvin, Robert A; Lai, Barry; Holmes, William R; Lee, Daewoo

    2015-09-01

    Correction for 'Understanding metal homeostasis in primary cultured neurons. Studies using single neuron subcellular and quantitative metallomics' by Robert A. Colvin et al., Metallomics, 2015, 7, 1111-1123.

  16. Demonstration of a Bit-Flip Correction for Enhanced Sensitivity Measurements

    CERN Document Server

    Cohen, L; Istrati, D; Retzker, A; Eisenberg, H S

    2016-01-01

    The sensitivity of classical and quantum sensing is impaired in a noisy environment. Thus, one of the main challenges facing sensing protocols is to reduce the noise while preserving the signal. State of the art quantum sensing protocols that rely on dynamical decoupling achieve this goal under the restriction of long noise correlation times. We implement a proof of principle experiment of a protocol to recover sensitivity by using an error correction for photonic systems that does not have this restriction. The protocol uses a protected entangled qubit to correct a bit-flip error. Our results show a recovery of about 87% of the sensitivity, independent of the noise rate.

  17. Demonstration of a quantum error correction for enhanced sensitivity of photonic measurements

    Science.gov (United States)

    Cohen, L.; Pilnyak, Y.; Istrati, D.; Retzker, A.; Eisenberg, H. S.

    2016-07-01

    The sensitivity of classical and quantum sensing is impaired in a noisy environment. Thus, one of the main challenges facing sensing protocols is to reduce the noise while preserving the signal. State-of-the-art quantum sensing protocols that rely on dynamical decoupling achieve this goal under the restriction of long noise correlation times. We implement a proof-of-principle experiment of a protocol to recover sensitivity by using an error correction for photonic systems that does not have this restriction. The protocol uses a protected entangled qubit to correct a single error. Our results show a recovery of about 87 % of the sensitivity, independent of the noise probability.

  18. Real-time single-shot measurement and correction of pulse phase and amplitude for ultrafast lasers

    Science.gov (United States)

    Pestov, Dmitry; Ryabtsev, Anton; Rasskazov, Gennady; Lozovoy, Vadim V.; Dantus, Marcos

    2014-05-01

    The transition of femtosecond lasers from the laboratory to commercial applications requires real-time automated pulse compression, ensuring optimum performance without assistance. Single-shot phase measurements together with closed-loop optimization based on real-time multiphoton intrapulse interference phase scan are demonstrated. On-the-fly correction of amplitude, as well as second- and third-order phase distortions based on the real-time measurements, is accomplished by a pulse shaper.

  19. The evaluation of four different diffuse radiation correction models applied to shadow ring measurements for Beer Sheva, Israel

    Science.gov (United States)

    Kudish, Avraham I.; Evseev, Efim G.

    2007-09-01

    The measurement of the horizontal diffuse radiation, a priori a straightforward task, is fraught with difficulties. It is possible to measure the diffuse radiation by both direct and indirect methods. The most accurate method is probably the indirect one, which utilizes concurrent measurements of the horizontal global and the normal incidence beam radiation. The disadvantage of this method is the relatively expensive tracking system required for measuring the latter. The diffuse radiation can be measured directly with a pyranometer outfitted with either an occulting disk or shadow ring, which prevent the beam radiation from impinging on the pyranometer sensor. The former method can provide accurate measurements of the diffuse radiation but requires a relatively expensive sun tracking system in the east-west axis. The shadow ring is a stationary device with regard to the east-west axis and blocks the beam radiation component by creating a permanent shadow on the pyranometer sensor. The disadvantage of the shadow ring is that it also blocks a portion of the sky, which necessitates a geometrical correction factor. There is also a need to correct for anisotropic sky conditions. Four correction models have been applied to the data and the results evaluated and ranked.

  20. Describing and quantifying asthma comorbidity [corrected]: a population study.

    Directory of Open Access Journals (Sweden)

    Andrea S Gershon

    Full Text Available BACKGROUND: Asthma comorbidity has been correlated with poor asthma control, increased health services use, and decreased quality of life. Managing it improves these outcomes. Little is known about the amount of different types of comorbidity associated with asthma and how they vary by age. METHODOLOGY/PRINCIPAL FINDINGS: The authors conducted a population study using health administrative data on all individuals living in Ontario, Canada (population 12 million. Types of asthma comorbidity were quantified by comparing physician health care claims between individuals with and without asthma in each of 14 major disease categories; results were adjusted for demographic factors and other comorbidity and stratified by age. Compared to those without asthma, individuals with asthma had higher rates of comorbidity in most major disease categories. Most notably, they had about fifty percent or more physician health care claims for respiratory disease (other than asthma in all age groups; psychiatric disorders in individuals age four and under and age 18 to 44; perinatal disorders in individuals 17 years and under, and metabolic and immunity, and hematologic disorders in children four years and under. CONCLUSION/SIGNIFICANCE: Asthma appears to be associated with significant rates of various types of comorbidity that vary according to age. These results can be used to develop strategies to recognize and address asthma comorbidity to improve the overall health of individuals with asthma.

  1. Retrieval of SO2 from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash

    Directory of Open Access Journals (Sweden)

    A. J. Prata

    2009-02-01

    Full Text Available The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 columnar abundance retrieval when multispectral Thermal InfraRed (TIR data are used. The ash particles within the plume with effective radii (from 1 to 10 μm reduce the Top Of Atmosphere (TOA radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computation speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7 μm SO2 absorption bands, and the split window bands centered around 11 and 12 μm required for ash retrieval. This allows the possibility of a simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS and the Spin Enhanced Visible and Infrared Imager (SEVIRI measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimations are carried out by using a least squares fit method and the Brightness Temperature Difference (BTD procedures, respectively. The simulated TOA radiance Look-Up Table (LUT needed for the SO2 columnar abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrieval at 8.7 μm – the SO2 columnar abundance corrected by the ash influence is less than one half of the values retrieved without the correction. The ash correction on SO2 retrieval at 7.3 μm is much less important and only significant for low SO2 columnar abundances. Results also show that the simplified and

  2. Impact of and correction for instrument sensitivity drift on nanoparticle size measurements by single-particle ICP-MS

    OpenAIRE

    El Hadri, Hind; Petersen, Elijah J.; Winchester, Michael R.

    2016-01-01

    The effect of ICP-MS instrument sensitivity drift on the accuracy of NP size measurements using single particle (sp)ICP-MS is investigated. Theoretical modeling and experimental measurements of the impact of instrument sensitivity drift are in agreement and indicate that drift can impact the measured size of spherical NPs by up to 25 %. Given this substantial bias in the measured size, a method was developed using an internal standard to correct for the impact of drift and was shown to accura...

  3. Measurement of the Lick Indices in Early-Type Galaxies: Line-of-Sight Velocity Distribution Corrections for IC 1459

    Directory of Open Access Journals (Sweden)

    Samurović, S.

    2009-12-01

    Full Text Available In this paper we analyse the measurements of the absorption line-strength Lick indices in the early-type galaxy IC 1459. We use thelong-slit spectra of the elliptical galaxy IC 1459 from which its kinematicshad previously been extracted to calculate the Lick indices forthe observed spectral region (Mg$_2$, Fe5270, Fe5335 and H$_beta$. Weapply the usual procedure and correct the indices to the Lick spectralresolution and for the zero velocity dispersion. The procedure applied in thispaper also corrects to non-Gaussian line-of-sight velocity distribution(LOSVD observed in this galaxy, especially in its outer parts. The findingsof Kuntschner (2004 were tested and it is shown that the departures from theGaussian LOSVD may indeed cause erroneous determinations of the Lick indices. The impact of the introduction of non-Gaussian LOSVD differs for differentindices. For the galaxy IC~1459 it is shown that the iron indices areespecially sensitive when the correction due to anistropies is introduced: thecorrections for Fe5270 and Fe5335 are $sim 10$ and $sim 19$ percentlarger, respectively, than the corrections obtained in case of a pure Gaussian. The corrections for Mg$_2$ index are shown to be negligible and thecorrections of the H$_beta$ index due to anisotropies are also small (below$sim 4$ per cent at most.

  4. Correction of measured charged-particle spectra for energy losses in the target - A comparison of three methods

    CERN Document Server

    Soederberg, J; Alm-Carlsson, G; Olsson, N

    2002-01-01

    The experimental facility, MEDLEY, at the The Svedberg Laboratory in Uppsala, has been constructed to measure neutron-induced charged-particle production cross-sections for (n, xp), (n, xd), (n, xt), (n, x sup 3 He) and (n, x alpha) reactions at neutron energies up to 100 MeV. Corrections for the energy loss of the charged particles in the target are needed in these measurements, as well as for loss of particles. Different approaches have been used in the literature to solve this problem. In this work, a stripping method is developed, which is compared with other methods developed by Rezentes et al. and Slypen et al. The results obtained using the three codes are similar and they could all be used for correction of experimental charged-particle spectra. Statistical fluctuations in the measured spectra cause problems independent of the applied technique, but the way to handle it differs in the three codes.

  5. Shallow Water Measurements Using a Single Green Laser Corrected by Building a Near Water Surface Penetration Model

    Directory of Open Access Journals (Sweden)

    Jianhu Zhao

    2017-04-01

    Full Text Available To reduce the size and cost of an integrated infrared (IR and green airborne LiDAR bathymetry (ALB system, and improve the accuracy of the green ALB system, this study proposes a method to accurately determine water surface and water bottom heights using a single green laser corrected by the near water surface penetration (NWSP model. The factors that influence the NWSP of green laser are likewise analyzed. In addition, an NWSP modeling method is proposed to determine the relationship between NWSP and the suspended sediment concentration (SSC of the surface layer, scanning angle of a laser beam and sensor height. The water surface and water bottom height models are deduced by considering NWSP and using only green laser based on the measurement principle of the IR laser and green laser, as well as employing the relationship between NWSP and the time delay of the surface return of the green laser. Lastly, these methods and models are applied to a practical ALB measurement. Standard deviations of 3.0, 5.3, and 1.3 cm are obtained by the NWSP, water-surface height, and water-bottom height models, respectively. Several beneficial conclusions and recommendations are drawn through the experiments and discussions.

  6. Finite element model determination of correction factors used for measurement of aortic diameter via conductance.

    Science.gov (United States)

    Hettrick, D A; Battocletti, J; Ackmann, J; Warltier, D C

    1999-01-01

    Traditional methods for estimating the slope alpha and offset volume Vp for determining real-time chamber volume by the conductance catheter technique are not suited to measurements made in the aorta due to the relatively low resistivity of the aortic wall. We developed three distinct three-dimensional finite element models of the conductance catheter and surrounding tissues in order to predict alpha and Vp and to examine the nature of the electric field near the aortic wall. A heterogeneous isotropic model of the catheter, aorta and surrounding tissues accurately predicted the values of alpha and Vp. A homogeneous anisotropic model was developed to examine the effects of anisotropy of blood and the layers of the aortic wall on measured values of resistance, alpha and Vp. This model demonstrated that anisotropy of blood and aortic wall tissue can increase the values of both alpha and Vp. Finally, a three-dimensional homogeneous isotropic rectangular model allowed examination of the effects of catheter position. This model showed small effects of catheter position on measured resistance (9.7% increase) and larger effects on alpha (21.2% decrease) and Vp (41.9% increase). We conclude the following: the FEA models may lead to accurate estimate values of alpha and Vp in vivo. The unique anisotropic conductive properties of the layers of the aortic wall contribute to the high observed values of alpha and Vp in the aorta. Finally, catheter position has a proportionately greater effect on alpha and Vp than on measured resistance. The results of this study should assist in the determination of aortic mechanical properties using conductance catheter measurements of vessel dimension.

  7. Electroweak Corrections for the Study of the Higgs Potential at the LC

    CERN Document Server

    Boudjema, F; Ishikawa, T; Kaneko, T; Kato, K; Kurihara, Y; Shimizu, Y; Yasui, Y

    2005-01-01

    The full electroweak radiative correction is calculated for the process ee--> nunubarHH which is a window for the study of the Higgs potential at the future linear collider. The calculation is done by using GRACE, the automated system for the calculation of Feynman diagrams. The magnitude of the weak correction in the G-mu scheme is small in the high energy region where this process dominates over the ZHH production.

  8. Impact of post-manipulation corrective core exercises on the spinal deformation and lumbar strength in golfers: a case study.

    Science.gov (United States)

    Shin, Chul-Ho; Kim, Minjeong; Park, Gi Duck

    2015-09-01

    [Purpose] This study examined spinal shape in professional golfers with chronic back pain, and analyzed the effects of a 4-week regimen of semi-weekly manipulation and corrective core exercises on spinal shape. [Subjects] Two golfers with chronic back pain. [Methods] The pelvis and spinal vertebrae were corrected using the Thompson "drop" technique. Angle and force were adjusted to place the pelvis, lumbar spine, and thoracic vertebrae in neutral position. The technique was applied twice weekly after muscle massage in the back and pelvic areas. The golfers performed corrective, warmup stretching exercises, followed by squats on an unstable surface using the Togu ball. They then used a gym ball for repetitions of hip rotation, upper trunk extension, sit-ups, and pelvic anterior-posterior, pelvic left-right, and trunk flexion-extension exercises. The session ended with cycling as a cool-down exercise. Each session lasted 60 minutes. [Results] The difference in height was measured on the left and right sides of the pelvic bone. The pelvic tilt changed significantly in both participants after the 4-week program. [Conclusion] In golfers, core muscles are critical and are closely related to spinal deformation. Core strengthening and spinal correction play a pivotal role in the correction of spinal deformation.

  9. SU-E-T-17: A Mathematical Model for PinPoint Chamber Correction in Measuring Small Fields

    Energy Technology Data Exchange (ETDEWEB)

    Li, T; Zhang, Y; Li, X; Heron, D.E.; Huq, M.Saiful [University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

    2014-06-01

    Purpose: For small field dosimetry, such as measuring the cone output factor for stereotactic radiosurgery, ion chambers often result in underestimation of the dose, due to both the volume averaging effect and the lack of electron equilibrium. The purpose of this work is to develop a mathematical model, specifically for the pinpoint chamber, to calculate the correction factors corresponding to different type of small fields, including single cone-based circular field and non-standard composite fields. Methods: A PTW 0.015cc PinPoint chamber was used in the study. Its response in a certain field was modeled as the total contribution of many small beamlets, each with different response factor depending on the relative strength, radial distance to the chamber axis, and the beam angle. To get these factors, 12 cone-shaped circular fields (5mm,7.5mm, 10mm, 12.5mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 50mm, 60mm) were irradiated and measured with the PinPoint chamber. For each field size, hundreds of readings were recorded for every 2mm chamber shift in the horizontal plane. These readings were then compared with the theoretical doses as obtained with Monte Carlo calculation. A penalized-least-square optimization algorithm was developed to find out the beamlet response factors. After the parameter fitting, the established mathematical model was validated with the same MC code for other non-circular fields. Results: The optimization algorithm used for parameter fitting was stable and the resulted response factors were smooth in spatial domain. After correction with the mathematical model, the chamber reading matched with the Monte Carlo calculation for all the tested fields to within 2%. Conclusion: A novel mathematical model has been developed for the PinPoint chamber for dosimetric measurement of small fields. The current model is applicable only when the beam axis is perpendicular to the chamber axis. It can be applied to non-standard composite fields. Further

  10. Retrieval of SO2 from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash

    Directory of Open Access Journals (Sweden)

    S. Corradini

    2009-05-01

    Full Text Available The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 column abundance retrieval when multispectral Thermal InfraRed (TIR data are used. The ash particles within the plume with effective radii from 1 to 10 μm reduce the Top Of Atmosphere (TOA radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computational speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7 μm SO2 absorption bands, and the split window bands centered around 11 and 12 μm required for ash retrieval. This allows the possibility of simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS and the Spin Enhanced Visible and Infrared Imager (SEVIRI measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimation is carried out by using a best weighted least squares fit method and the Brightness Temperature Difference (BTD procedures, respectively. The simulated TOA radiance Look-Up Table (LUT needed for the SO2 column abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrievals at 8.7 μm, where the corrected SO2 column abundance values are less than 50% of the uncorrected values. The ash correction on SO2 retrieval at 7.3 μm is much less important and only significant for low SO2 column abundances. Results also show that the simplified and faster correction procedure

  11. Two-Photon Exchange Corrections to Precise Measurements of Proton Electroweak Form Factors

    Science.gov (United States)

    Afanasev, Andrei

    2004-10-01

    Higher-order QED effects play an important role for extracting information on proton form factors from electron scattering data. For the electric form factor of the proton, a previously neglected two-photon-exchange correction reconciles an observed discrepancy between Rosenbluth and polarization techniques [1]. We use a similar approach based on General Parton Distributions to compute additional radiative corrections to parity-violating electron scattering. [1] Y.C. Chen, A. Afanasev, S.J. Brodsky, C.E. Carlson and M. Vanderhaeghen, ``Partonic calculation of the two-photon exchange contribution to elastic electron proton scattering at large momentum transfer,`` arXiv:hep-ph/0403058, to appear in Phys.Rev.Lett.

  12. A hybrid solution using computational prediction and measured data to accurately determine process corrections with reduced overlay sampling

    Science.gov (United States)

    Noyes, Ben F.; Mokaberi, Babak; Mandoy, Ram; Pate, Alex; Huijgen, Ralph; McBurney, Mike; Chen, Owen

    2017-03-01

    Reducing overlay error via an accurate APC feedback system is one of the main challenges in high volume production of the current and future nodes in the semiconductor industry. The overlay feedback system directly affects the number of dies meeting overlay specification and the number of layers requiring dedicated exposure tools through the fabrication flow. Increasing the former number and reducing the latter number is beneficial for the overall efficiency and yield of the fabrication process. An overlay feedback system requires accurate determination of the overlay error, or fingerprint, on exposed wafers in order to determine corrections to be automatically and dynamically applied to the exposure of future wafers. Since current and future nodes require correction per exposure (CPE), the resolution of the overlay fingerprint must be high enough to accommodate CPE in the overlay feedback system, or overlay control module (OCM). Determining a high resolution fingerprint from measured data requires extremely dense overlay sampling that takes a significant amount of measurement time. For static corrections this is acceptable, but in an automated dynamic correction system this method creates extreme bottlenecks for the throughput of said system as new lots have to wait until the previous lot is measured. One solution is using a less dense overlay sampling scheme and employing computationally up-sampled data to a dense fingerprint. That method uses a global fingerprint model over the entire wafer; measured localized overlay errors are therefore not always represented in its up-sampled output. This paper will discuss a hybrid system shown in Fig. 1 that combines a computationally up-sampled fingerprint with the measured data to more accurately capture the actual fingerprint, including local overlay errors. Such a hybrid system is shown to result in reduced modelled residuals while determining the fingerprint, and better on-product overlay performance.

  13. A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2009-01-01

    tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between...... the theoretical absorption coefficient and the reverberation room measurement. The angle-weighted absorption coefficient, together with the size correction, agrees satisfactorily with the measured absorption data by the reverberation chamber method. At high frequencies and for large samples, the averaged...... weighting corresponds well with the measurement, whereas at low frequencies and for small panels, the relatively flat distribution agrees better....

  14. Method for correction of measured polarization angles from motional Stark effect spectroscopy for the effects of electric fields

    Science.gov (United States)

    Luce, T. C.; Petty, C. C.; Meyer, W. H.; Holcomb, C. T.; Burrell, K. H.; Bergsten, L. J.

    2016-12-01

    An approximate method to correct the motional Stark effect (MSE) spectroscopy for the effects of intrinsic plasma electric fields has been developed. The motivation for using an approximate method is to incorporate electric field effects for between-pulse or real-time analysis of the current density or safety factor profile. The toroidal velocity term in the momentum balance equation is normally the dominant contribution to the electric field orthogonal to the flux surface over most of the plasma. When this approximation is valid, the correction to the MSE data can be included in a form like that used when electric field effects are neglected. This allows measurements of the toroidal velocity to be integrated into the interpretation of the MSE polarization angles without changing how the data is treated in existing codes. In some cases, such as the DIII-D system, the correction is especially simple, due to the details of the neutral beam and MSE viewing geometry. The correction method is compared using DIII-D data in a variety of plasma conditions to analysis that assumes no radial electric field is present and to analysis that uses the standard correction method, which involves significant human intervention for profile fitting. The comparison shows that the new correction method is close to the standard one, and in all cases appears to offer a better result than use of the uncorrected data. The method has been integrated into the standard DIII-D equilibrium reconstruction code in use for analysis between plasma pulses and is sufficiently fast that it will be implemented in real-time equilibrium analysis for control applications.

  15. A comparative study on preprocessing techniques in diabetic retinopathy retinal images: illumination correction and contrast enhancement.

    Science.gov (United States)

    Rasta, Seyed Hossein; Partovi, Mahsa Eisazadeh; Seyedarabi, Hadi; Javadzadeh, Alireza

    2015-01-01

    To investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal image quality, a comparative study was carried out. We studied and implemented a few illumination correction and contrast enhancement techniques on color retinal images to find out the best technique for optimum image enhancement. To compare and choose the best illumination correction technique we analyzed the corrected red and green components of color retinal images statistically and visually. The two contrast enhancement techniques were analyzed using a vessel segmentation algorithm by calculating the sensitivity and specificity. The statistical evaluation of the illumination correction techniques were carried out by calculating the coefficients of variation. The dividing method using the median filter to estimate background illumination showed the lowest Coefficients of variations in the red component. The quotient and homomorphic filtering methods after the dividing method presented good results based on their low Coefficients of variations. The contrast limited adaptive histogram equalization increased the sensitivity of the vessel segmentation algorithm up to 5% in the same amount of accuracy. The contrast limited adaptive histogram equalization technique has a higher sensitivity than the polynomial transformation operator as a contrast enhancement technique for vessel segmentation. Three techniques including the dividing method using the median filter to estimate background, quotient based and homomorphic filtering were found as the effective illumination correction techniques based on a statistical evaluation. Applying the local contrast enhancement technique, such as CLAHE, for fundus images presented good potentials in enhancing the vasculature segmentation.

  16. The assessment of four different correction models applied to the diffuse radiation measured with a shadow ring using global and normal beam radiation measurements for Beer Sheva, Israel

    Energy Technology Data Exchange (ETDEWEB)

    Kudish, Avraham I.; Evseev, Efim G. [Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, E D Bergmann Campus, Beer Sheva 84105 (Israel)

    2008-02-15

    The measurement of the diffuse radiation incident on a horizontal surface, a priori a straightforward task, is fraught with difficulties. It is possible to measure the diffuse radiation by three different techniques: two of which measure it directly and the third indirectly. The most accurate is the indirect one, which is based upon the concurrent measurements of the horizontal global and the normal incidence beam radiation. The disadvantage of this being the relatively expensive tracking system required for measuring the latter. The diffuse radiation can be measured directly with a pyranometer outfitted with either an occulting disk or shadow ring, which prevent the beam radiation from impinging on the pyranometer sensor. The occulting disk can provide accurate measurements of the diffuse radiation but it requires a relatively expensive sun tracking system in the east-west axis. The shadow ring is a stationary device with regard to the east-west axis and blocks the beam radiation component by creating a permanent shadow on the pyranometer sensor. The major disadvantage of the shadow ring is that it also blocks that portion of the diffuse radiation obscured by the shadow ring. This introduces a measurement error that must be corrected to account for that portion of the sky obscured by the shadow band. In addition to this geometric correction factor there is a need to correct for anisotropic sky conditions. Four correction models have been applied to the data for Beer Sheva, Israel and the results have been evaluated both graphically and statistically. An attempt has been made to score the relative performance of the models under different sky conditions. (author)

  17. "Effects of networking on career success: A longitudinal study": Correction to Wolff and Moser (2009).

    Science.gov (United States)

    2017-02-01

    Reports an error in "Effects of networking on career success: A longitudinal study" by Hans-Georg Wolff and Klaus Moser (Journal of Applied Psychology, 2009[Jan], Vol 94[1], 196-206). In the article, results from a confirmatory factor analysis on subjective career success in the Measures section contained an error in the reported Chi-square (i.e., χ² (5, N = 257) = 9.17). This error does not alter any conclusions or substantive statements in the original article. The correct fit indices are " χ²(5, N = 257) 9.67, p = .08, RMSEA = 0.059, CFI = 1.00." (The following abstract of the original article appeared in record 2009-00697-007.) Previous research has reported effects of networking, defined as building, maintaining, and using relationships, on career success. However, empirical studies have relied exclusively on concurrent or retrospective designs that rest upon strong assumptions about the causal direction of this relation and depict a static snapshot of the relation at a given point in time. This study provides a dynamic perspective on the effects of networking on career success and reports results of a longitudinal study. Networking was assessed with 6 subscales that resulted from combining measures of the facets of (a) internal versus external networking and (b) building versus maintaining versus using contacts. Objective (salary) and subjective (career satisfaction) measures of career success were obtained for 3 consecutive years. Multilevel analyses showed that networking is related to concurrent salary and that it is related to the growth rate of salary over time. Networking is also related to concurrent career satisfaction. As satisfaction remained stable over time, no effects of networking on the growth of career satisfaction were found. (PsycINFO Database Record

  18. A Novel Approach to Correct Diffraction Effect in Measurement of Ultrasonic Velocity and Attenuation at High Frequencies

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dong(章东); LIU Xiao-Zhou(刘晓宙); GONG Xiu-Fen(龚秀芬); KUSHIBIKI Jun-Ichi

    2003-01-01

    A novel method to correct diffraction effect in measurement of ultrasonic velocity and attenuation at high frequencies is developed by using the superposition technique of Gaussian beams. To examine the validity of this numerical approach, the amplitude loss and phase advance due to the diffraction effect for an SiO2 specimen are numerically calculated in 30-240MHz, and the results are in good agreement with those by the Papadakis method.

  19. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP at high black carbon mass concentration levels

    Directory of Open Access Journals (Sweden)

    A.-P. Hyvärinen

    2013-01-01

    Full Text Available The Multi-Angle Absorption Photometer (MAAP is a widely-used instrument for aerosol black carbon (BC measurements. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments characterized by high black carbon concentrations. The artifact occurs after a filter spot change – as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ~3 μg m−3 at the typical MAAP flow rate of 16.7 L min−1 or 1 m3 h−1. The artifact is caused by erroneous dark counts in the photodetector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photodetector raw signals. It was found that, in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m−3 (at the flow rate of 16.7 L min−1 are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 L min−1 and concentration of about 24 μg m−3 (BC accumulation rate ~0.4 μg min−1, the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from

  20. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP) at high black carbon mass concentration levels

    Science.gov (United States)

    Hyvärinen, A.-P.; Vakkari, V.; Laakso, L.; Hooda, R. K.; Sharma, V. P.; Panwar, T. S.; Beukes, J. P.; van Zyl, P. G.; Josipovic, M.; Garland, R. M.; Andreae, M. O.; Pöschl, U.; Petzold, A.

    2013-01-01

    The Multi-Angle Absorption Photometer (MAAP) is a widely-used instrument for aerosol black carbon (BC) measurements. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments characterized by high black carbon concentrations. The artifact occurs after a filter spot change - as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal) is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ~3 μg m-3 at the typical MAAP flow rate of 16.7 L min-1 or 1 m3 h-1. The artifact is caused by erroneous dark counts in the photodetector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photodetector raw signals. It was found that, in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m-3 (at the flow rate of 16.7 L min-1) are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 L min-1 and concentration of about 24 μg m-3 (BC accumulation rate ~0.4 μg min-1), the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from Gual Pahari (India), Beijing (China), and Welgegund (South Africa). In Beijing, the results could also be compared against a

  1. Correction of ocular dystopia.

    Science.gov (United States)

    Janecka, I P

    1996-04-01

    The purpose of this study was to examine results with elective surgical correction of enophthalmos. The study was a retrospective assessment in a university-based referral practice. A consecutive sample of 10 patients who developed ocular dystopia following orbital trauma was examined. The main outcome measures were a subjective evaluation by patients and objective measurements of patients' eye position. The intervention was three-dimensional orbital reconstruction with titanium plates. It is concluded that satisfactory correction of enophthalmos and ocular dystopia can be achieved with elective surgery using titanium plates. In addition, intraoperative measurements of eye position in three planes increases the precision of surgery.

  2. A pertinent analytic method to correctly measure contributions to growth in gross domestic product

    Directory of Open Access Journals (Sweden)

    Brunet Antoine

    2009-01-01

    Full Text Available In this paper, Antoine Brunet questions the OECD method in calculating contributions to GDP growth. He tries to show this method induces the users to seriously misjudge the contribution of external trade balance to GDP growth. He shows there is an alternative method, i.e. the AB method which is mathematically as correct as the OECD one. And this method is much more pertinent and allows the users to distinguish between two kinds of countries: on the one hand, the mercantilist countries and on the other hand, the non-mercantilist countries.

  3. On the Importance of CP-corrected Gradient Optimization in the Study of Hydrogen Bonded Systems

    Institute of Scientific and Technical Information of China (English)

    王伟周; 蒲雪梅; 郑文旭; 黄宁表; 田安民

    2003-01-01

    Geometries, harmonic vibrational frequencies and interaction energies of the water-hydrogen sulfide dimer, hydrogen fluoride dimer and glycine zwitterion-water dimer were determined by the counterpoise-corrected (CP-corrected) gradient optimization that explicitly corrects for the basis set superpusition error (BSSE) and CP-uncorrected (normal) gradient opfimization respectively at the B3LYP and MP2 levels of theory, employing the popular Pople's standard 6-31G(d), 6-31G(d,p) and 6-311+ +G(d,p) basis sets in order to assess the importance of CP-corrected gradient optimiTation in the study of hydrogen bonded systems. The normal optimization of these three H-bonded systems obtained using these popular basis sets all yielded erratic results, whereas use of CP-corrected gradient optimization led to consistent results with those from larger basis sets. So this CP receipt becomes useful and necessary to correctly describe large systems, where the use of small basis sets may be necessary.

  4. Effect of physiological heart rate variability on quantitative T2 measurement with ECG-gated Fast Spin Echo (FSE) sequence and its retrospective correction.

    Science.gov (United States)

    de Roquefeuil, Marion; Vuissoz, Pierre-André; Escanyé, Jean-Marie; Felblinger, Jacques

    2013-11-01

    Quantitative T2 measurement is applied in cardiac Magnetic Resonance Imaging (MRI) for the diagnosis and follow-up of myocardial pathologies. Standard Electrocardiogram (ECG)-gated fast spin echo pulse sequences can be used clinically for T2 assessment, with multiple breath-holds. However, heart rate is subject to physiological variability, which causes repetition time variations and affects the recovery of longitudinal magnetization between TR periods. The bias caused by heart rate variability on quantitative T2 measurements is evaluated for fast spin echo pulse sequence. Its retrospective correction based on an effective TR is proposed. Heart rate variations during breath-holds are provided by the ECG recordings from healthy volunteers. T2 measurements were performed on a phantom with known T2 values, by synchronizing the sequence with the recorded ECG. Cardiac T2 measurements were performed twice on six volunteers. The impact of T1 on T2 is also studied. Maximum error in T2 is 26% for phantoms and 18% for myocardial measurement. It is reduced by the proposed compensation method to 20% for phantoms and 10% for in vivo measurements. Only approximate knowledge of T1 is needed for T2 correction. Heart rate variability may cause a bias in T2 measurement with ECG-gated FSE. It needs to be taken into account to avoid a misleading diagnosis from the measurements. © 2013.

  5. Spatial measurement error and correction by spatial SIMEX in linear regression models when using predicted air pollution exposures.

    Science.gov (United States)

    Alexeeff, Stacey E; Carroll, Raymond J; Coull, Brent

    2016-04-01

    Spatial modeling of air pollution exposures is widespread in air pollution epidemiology research as a way to improve exposure assessment. However, there are key sources of exposure model uncertainty when air pollution is modeled, including estimation error and model misspecification. We examine the use of predicted air pollution levels in linear health effect models under a measurement error framework. For the prediction of air pollution exposures, we consider a universal Kriging framework, which may include land-use regression terms in the mean function and a spatial covariance structure for the residuals. We derive the bias induced by estimation error and by model misspecification in the exposure model, and we find that a misspecified exposure model can induce asymptotic bias in the effect estimate of air pollution on health. We propose a new spatial simulation extrapolation (SIMEX) procedure, and we demonstrate that the procedure has good performance in correcting this asymptotic bias. We illustrate spatial SIMEX in a study of air pollution and birthweight in Massachusetts.

  6. 76 FR 1665 - Stakeholder Meetings Regarding the U.S.-Flag Great Lakes Fleet Revitalization Study; Correction

    Science.gov (United States)

    2011-01-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Stakeholder Meetings Regarding the U.S.-Flag Great Lakes Fleet Revitalization Study; Correction AGENCY: Maritime Administration, Department of Transportation. ACTION: Correction Notice....

  7. Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP at high black carbon mass concentration levels

    Directory of Open Access Journals (Sweden)

    A.-P. Hyvärinen

    2012-09-01

    Full Text Available The Multi-Angle Absorption Photometer (MAAP is a widely-used instrument for aerosol black carbon observations. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments with high black carbon concentrations. The artifact occurs after a filter spot change – as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ∼3 μg m−3 at the typical MAAP flow rate of 16.7 l min−1 or 1 m3 h−1. The artifact is caused by erroneous dark counts in the photo detector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photo detector raw signals. It was found that in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m−3 (at the flow rate of 16.7 l min−1 are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 l min−1 and concentration of about 24 μg m−3 (BC accumulation rate ∼0.4 μg min−1, the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from Gual Pahari

  8. A Correction of Random Incidence Absorption Coefficients for the Angular Distribution of Acoustic Energy under Measurement Conditions

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2009-01-01

    Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause...... discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam...... the theoretical absorption coefficient and the reverberation room measurement. The angle-weighted absorption coefficient, together with the size correction, agrees satisfactorily with the measured absorption data by the reverberation chamber method. At high frequencies and for large samples, the averaged...

  9. Corrective Feedback in Classrooms at Different Proficiency Levels: A Case Study of Chinese as a Foreign Language

    Directory of Open Access Journals (Sweden)

    Liu Li

    2014-08-01

    Full Text Available This paper presents a study investigating the relationship between corrective feedback, students’ language proficiency and classroom communication orientation in classrooms of Chinese as a Foreign Language (CFL at a US university. Inspired by Lyster and Mori (2006, this comparative analysis of teacher-student interaction investigates the immediate effects of prompt, recast, and explicit correction on learner uptake and repair across three different Chinese proficiency levels. By use of two measurement tools—Error Treatment Model and COLT coding scheme, the study attempts to seek the distribution pattern of feedbacks and the sequent uptakes, as well as the impact of learners’ proficiency levels on the pattern of feedback and uptakes in CFL classrooms. Results show that recasts still remain the most common feedback type across the classes in this study. The uptake of feedback is influenced both by classroom communication orientation and the students’ language proficiency.

  10. Partial volume correction of brain PET studies using iterative deconvolution in combination with HYPR denoising.

    Science.gov (United States)

    Golla, Sandeep S V; Lubberink, Mark; van Berckel, Bart N M; Lammertsma, Adriaan A; Boellaard, Ronald

    2017-12-01

    Accurate quantification of PET studies depends on the spatial resolution of the PET data. The commonly limited PET resolution results in partial volume effects (PVE). Iterative deconvolution methods (IDM) have been proposed as a means to correct for PVE. IDM improves spatial resolution of PET studies without the need for structural information (e.g. MR scans). On the other hand, deconvolution also increases noise, which results in lower signal-to-noise ratios (SNR). The aim of this study was to implement IDM in combination with HighlY constrained back-PRojection (HYPR) denoising to mitigate poor SNR properties of conventional IDM. An anthropomorphic Hoffman brain phantom was filled with an [(18)F]FDG solution of ~25 kBq mL(-1) and scanned for 30 min on a Philips Ingenuity TF PET/CT scanner (Philips, Cleveland, USA) using a dynamic brain protocol with various frame durations ranging from 10 to 300 s. Van Cittert IDM was used for PVC of the scans. In addition, HYPR was used to improve SNR of the dynamic PET images, applying it both before and/or after IDM. The Hoffman phantom dataset was used to optimise IDM parameters (number of iterations, type of algorithm, with/without HYPR) and the order of HYPR implementation based on the best average agreement of measured and actual activity concentrations in the regions. Next, dynamic [(11)C]flumazenil (five healthy subjects) and [(11)C]PIB (four healthy subjects and four patients with Alzheimer's disease) scans were used to assess the impact of IDM with and without HYPR on plasma input-derived distribution volumes (V T) across various regions of the brain. In the case of [(11)C]flumazenil scans, Hypr-IDM-Hypr showed an increase of 5 to 20% in the regional V T whereas a 0 to 10% increase or decrease was seen in the case of [(11)C]PIB depending on the volume of interest or type of subject (healthy or patient). References for these comparisons were the V Ts from the PVE-uncorrected scans. IDM improved quantitative accuracy

  11. Validation of phenol red versus gravimetric method for water reabsorption correction and study of gender differences in Doluisio's absorption technique.

    Science.gov (United States)

    Tuğcu-Demiröz, Fatmanur; Gonzalez-Alvarez, Isabel; Gonzalez-Alvarez, Marta; Bermejo, Marival

    2014-10-01

    The aim of the present study was to develop a method for water flux reabsorption measurement in Doluisio's Perfusion Technique based on the use of phenol red as a non-absorbable marker and to validate it by comparison with gravimetric procedure. The compounds selected for the study were metoprolol, atenolol, cimetidine and cefadroxil in order to include low, intermediate and high permeability drugs absorbed by passive diffusion and by carrier mediated mechanism. The intestinal permeabilities (Peff) of the drugs were obtained in male and female Wistar rats and calculated using both methods of water flux correction. The absorption rate coefficients of all the assayed compounds did not show statistically significant differences between male and female rats consequently all the individual values were combined to compare between reabsorption methods. The absorption rate coefficients and permeability values did not show statistically significant differences between the two strategies of concentration correction. The apparent zero order water absorption coefficients were also similar in both correction procedures. In conclusion gravimetric and phenol red method for water reabsorption correction are accurate and interchangeable for permeability estimation in closed loop perfusion method.

  12. A Case Study of EFL Teachers’ Perceptions and Practices in Written Corrective Feedback

    Directory of Open Access Journals (Sweden)

    Hussam Rajab

    2016-01-01

    Full Text Available Based on a mixed-method approach, this interpretive exploratory case study aimed to identify English as Foreign Language (EFL teachers’ perceptions and practices in Written Corrective Feedback (WCF in the Saudi context. The study analysed quantitative data gathered from an anonymous custom designed 15-question online survey and qualitative data from an open-ended question (at the end of the online survey and semi-structured interviews. Participants were one hundred and eighty-four English as a Foreign Language (EFL teachers (n =184 who responded to the online survey (113 females and 71 males and 7 participants who responded to the semi-structured interview (5 males and 2 females. The study findings indicated no significant differences between male and female teachers in considering “time” as the main factor in following a particular strategy for written corrective feedback (93%. The results from the semi-structured interviews highlighted the need for further research in written corrective feedback in the Saudi context to address serious issues related to the teachers’ work-load. Some recommendations were identified for further research in written corrective feedback. Keywords: Saudi, Mixed methods, Survey, Written corrective feedback

  13. A Study of Students’ and Teachers’ Preferences and Attitudes towards Correction of Classroom Written Errors in Iranian EFL Context

    Directory of Open Access Journals (Sweden)

    Leila Hajian

    2014-09-01

    Full Text Available Written error correction may be the most widely used method for responding to student writing. Although there are various studies investigating error correction, there are little researches considering teachers’ and students’ preferences towards written error correction. The present study investigates students’ and teachers’ preferences and attitudes towards correction of classroom written errors in Iranian EFL context by using questionnaire. In this study, 80 students and 12 teachers were asked to answer the questionnaire. Then data were collected and analyzed by descriptive method. The findings from teachers and students show positive attitudes towards written error correction. Although the results of this study demonstrate teachers and students have some common preferences related to written error correction, there are some important discrepancies. For example; students prefer all error be corrected, but teachers prefer selecting some. However, students prefer teachers’ correction rather than peer or self-correction. This study considers a number of difficulties regarding students and teachers in written error correction processes with some suggestions. This study shows many teachers might believe written error correction takes a lot of time and effort to give comments. This study indicates many students does not have any problems in rewriting their paper after getting feedback. It might be one main positive point to improve their writing and it might give them self-confidence. Keywords: Error correction, teacher feedback, preferences.

  14. Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne’s house (Pompeii, Italy)

    Science.gov (United States)

    2013-01-01

    Background A microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne’s House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared. Results Microclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5°C due to the roof change, and the minimum temperature increased 0.5°C. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4°C, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4°C. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings. Conclusions The roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes. PMID:23683173

  15. Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne's house (Pompeii, Italy).

    Science.gov (United States)

    Merello, Paloma; García-Diego, Fernando-Juan; Zarzo, Manuel

    2013-05-17

    A microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne's House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared. Microclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5°C due to the roof change, and the minimum temperature increased 0.5°C. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4°C, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4°C. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings. The roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes.

  16. Principal components analysis corrects for stratification in genome-wide association studies.

    Science.gov (United States)

    Price, Alkes L; Patterson, Nick J; Plenge, Robert M; Weinblatt, Michael E; Shadick, Nancy A; Reich, David

    2006-08-01

    Population stratification--allele frequency differences between cases and controls due to systematic ancestry differences-can cause spurious associations in disease studies. We describe a method that enables explicit detection and correction of population stratification on a genome-wide scale. Our method uses principal components analysis to explicitly model ancestry differences between cases and controls. The resulting correction is specific to a candidate marker's variation in frequency across ancestral populations, minimizing spurious associations while maximizing power to detect true associations. Our simple, efficient approach can easily be applied to disease studies with hundreds of thousands of markers.

  17. A Study of Corrective Feedback and Learner's Uptake in Classroom Interactions

    Directory of Open Access Journals (Sweden)

    Fatemeh Esmaeili

    2014-07-01

    Full Text Available The present study aims to examine corrective feedback and learner uptake in classroom interactions. Inspired by Lyster and Ranta’s corrective feedback framework (1997, this study intends to describe and analyze the patterns of corrective feedback utilized by Iranian teachers, and learners' uptake and the repair of those errors. To this aim, 400 minutes of classroom interaction from three elementary EFL classes which comprised 29 EFL learners were audiotaped and transcribed. The learners were within age range of 16-29 and were native speakers of Turkish language. The teachers were within 26-31 age range and had 3-4 years experience of teaching and hold MA degree in TOEFL. Analysis of data constituted the frequency of six different feedback types used by three teachers, in addition distribution of learners' uptake following each feedback type. The findings indicated that among six corrective feedback types, recast was the most frequent feedback utilized by teachers although it did not lead to high amount of learner uptake. Metalinguistic feedback, elicitation and clarification request led to higher level of uptake. It was also found that explicit feedback was more effective than implicit feedback in promoting learner uptake. Keywords: Corrective Feedback, Learner Uptake, Classroom Interaction, EFL Teachers, EFL Learners

  18. Tide-corrected strain rate and crevasses of Campbell Glacier Tongue in East Antarctica measured by SAR interferometry

    Science.gov (United States)

    Han, H.; Lee, H.

    2016-12-01

    Measurement of flow velocity strain rate of a floating glacier is critical to the investigation of detailed flow regime and crevassing mechanism. We measured the surface deformation of Campbell Glacier Tongue (CGT) in East Antarctica from the 14 COSMO-SkyMed one-day tandem differential interferometric SAR (DInSAR) image pairs obtained in 2011. By removing the vertical tidal deflection obtained from the double-differential InSAR (DDInSAR) signals, we derived the tide-corrected ice-flow velocity and strain rate of CGT. The vertical tidal deflection of CGT was estimated by multiplying the tidal variations corresponding to the DInSAR images by the DDInSAR-derived tide deflection ratio, which was removed from the DInSAR signals to extract ice velocity only. The orientation of crevasses in CGT was nearly perpendicular to the direction of the most tensile strain rate calculated from the tide-corrected ice velocity. This demonstrates that the crevasses form by ice flow in respect of the DInSAR accuracy, not by tidal deflection. The tide correction of DInSAR signals over floating glaciers by using the DDInSAR-derived tide deflection ratio is useful for estimating accurate ice velocity and strain rate for analyzing crevasses. The tide-corrected ice velocity and strain rate will thus be of great value in a better understating of ice dynamics of floating glaciers. This research was funded by National Research Foundation of Korea (NRF-2016R1D1A1A09916630).

  19. Array processing——a new method to detect and correct errors on array resistivity logging tool measurements

    Institute of Scientific and Technical Information of China (English)

    Philip D.RABINOWITZ; Zhiqiang ZHOU

    2007-01-01

    In recent years more and more multi-array logging tools, such as the array induction and the array lateralog, are applied in place of conventional logging tools resulting in increased resolution, better radial and vertical sounding capability and other features. Multi-array logging tools acquire several times more individual measurements than conventional logging tools. In addition to new information contained in these data, there is a certain redundancy among the measurements. The sum of the measurements actually composes a large matrix. Providing the measurements are error-free, the elements of this matrix show certain consistencies. Taking advantage of these consistencies, an innovative method is developed to detect and correct errors in the array resistivity logging tool raw measurements, and evaluate the quality of the data. The method can be described in several steps. First, data consistency patterns are identified based onthe physics of the measurements. Second, the measurements are compared against the consistency patterns for error and bad data detection. Third, the erroneous data are eliminated and the measurements are re-constructed according to the consistency patterns. Finally, the data quality is evaluated by comparing the raw measurements with the re-constructed measurements. The method can be applied to all array type logging tools, such as array induction tool and array resistivity tool. This paper describes the method and illustrates its application with the High Definition Lateral Log (HDLL, Baker Atlas) instrument. To demonstrate the efficiency of the method, several field examples are shown and discussed.

  20. Atmospheric corrections in interferometric synthetic aperture radar surface deformation - a case study of the city of Mendoza, Argentina

    Science.gov (United States)

    Balbarani, S.; Euillades, P. A.; Euillades, L. D.; Casu, F.; Riveros, N. C.

    2013-09-01

    Differential interferometry is a remote sensing technique that allows studying crustal deformation produced by several phenomena like earthquakes, landslides, land subsidence and volcanic eruptions. Advanced techniques, like small baseline subsets (SBAS), exploit series of images acquired by synthetic aperture radar (SAR) sensors during a given time span. Phase propagation delay in the atmosphere is the main systematic error of interferometric SAR measurements. It affects differently images acquired at different days or even at different hours of the same day. So, datasets acquired during the same time span from different sensors (or sensor configuration) often give diverging results. Here we processed two datasets acquired from June 2010 to December 2011 by COSMO-SkyMed satellites. One of them is HH-polarized, and the other one is VV-polarized and acquired on different days. As expected, time series computed from these datasets show differences. We attributed them to non-compensated atmospheric artifacts and tried to correct them by using ERA-Interim global atmospheric model (GAM) data. With this method, we were able to correct less than 50% of the scenes, considering an area where no phase unwrapping errors were detected. We conclude that GAM-based corrections are not enough for explaining differences in computed time series, at least in the processed area of interest. We remark that no direct meteorological data for the GAM-based corrections were employed. Further research is needed in order to understand under what conditions this kind of data can be used.

  1. Surface EMG measurements during fMRI at 3T : Accurate EMG recordings after artifact correction

    NARCIS (Netherlands)

    van Duinen, Hiske; Zijdewind, Inge; Hoogduin, H; Maurits, N

    2005-01-01

    In this experiment, we have measured surface EMG of the first dorsal interosseus during predefined submaximal isometric contractions (5, 15, 30, 50, and 70% of maximal force) of the index finger simultaneously with fMRI measurements. Since we have used sparse sampling fMRI (3-s scanning; 2-s non-sca

  2. Comparative Study of Different Pulse Artifact Correction Techniques during Concurrent EEG-FMRI using FMRIB

    Directory of Open Access Journals (Sweden)

    Md Belayat Hossain

    2016-08-01

    Full Text Available In this work, a comparative study of three pulse artifact (PA correction methods –optimal basis set (OBS, simple mean (AAS and Gaussian-weighted mean (GWM – along with standard parameters setting for both gradient artefact (GA and pulse artefact (PA correction, using open source Functional MRI of Brain (FMRIB tool-box, in combined EEG-fMRI, is reported. It has been found that, of these three methods, OBS is better in preserving bio-signal while removing PA successfully.

  3. Final Corrective Action Study for the Former CCC/USDA Facility in Hanover, Kansas

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, Lorraine M. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2013-11-01

    Low concentrations of carbon tetrachloride in groundwater and vapor intrusion into a limited number of residences (attributable to the contaminant concentrations in groundwater) have been identified in Hanover, Kansas, at and near a grain storage facility formerly leased and operated by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA). At the request of the Kansas Department of Health and Environment (KDHE 2009h), the CCC/USDA has prepared this Corrective Action Study (CAS) for the facility. The CAS examines corrective actions to address the contamination in groundwater and soil vapor.

  4. [Study on temperature correctional models of quantitative analysis with near infrared spectroscopy].

    Science.gov (United States)

    Zhang, Jun; Chen, Hua-cai; Chen, Xing-dan

    2005-06-01

    Effect of enviroment temperature on near infrared spectroscopic quantitative analysis was studied. The temperature correction model was calibrated with 45 wheat samples at different environment temperaturs and with the temperature as an external variable. The constant temperature model was calibated with 45 wheat samples at the same temperature. The predicted results of two models for the protein contents of wheat samples at different temperatures were compared. The results showed that the mean standard error of prediction (SEP) of the temperature correction model was 0.333, but the SEP of constant temperature (22 degrees C) model increased as the temperature difference enlarged, and the SEP is up to 0.602 when using this model at 4 degrees C. It was suggested that the temperature correctional model improves the analysis precision.

  5. Gold weight implantation as a treatment measure for correction of paralytic lagophthalmos

    Directory of Open Access Journals (Sweden)

    P Manodh

    2011-01-01

    Full Text Available Ocular complications from facial nerve paralysis can be quite devastating. Facial nerve paralysis results in cosmetic as well as functional problems. Paralysis of the upper eyelids leads to lagophthalmos, which results in incomplete closure of the lid over the cornea, leading to potential complication of corneal ulceration. The management of the affected eye in patients with facial palsy has been improved. Previously, ointment, eye drops, taping, partial or complete tarsorrhaphy was the primary treatment for inability to close the eyelid. Other mechanical techniques for reanimating lid closure are palpebral springs, encircling the upper and lower eyelids with silicone or fascia lata and temporalis muscle transfer. The most popular and widely used static procedure in facial nerve palsy is the upper eyelid gold weight implant. Gold eyelid implants are designed for the gravity assisted treatment of the functional defect of lagophthalmos resulting from facial paralysis. We report a case of a patient with facial paralysis who underwent gold weight implantation of the upper eyelid for correction of paralytic lagophthalmos.

  6. Gold weight implantation as a treatment measure for correction of paralytic lagophthalmos.

    Science.gov (United States)

    Manodh, P; Devadoss, Pradeep; Kumar, Nishant

    2011-01-01

    Ocular complications from facial nerve paralysis can be quite devastating. Facial nerve paralysis results in cosmetic as well as functional problems. Paralysis of the upper eyelids leads to lagophthalmos, which results in incomplete closure of the lid over the cornea, leading to potential complication of corneal ulceration. The management of the affected eye in patients with facial palsy has been improved. Previously, ointment, eye drops, taping, partial or complete tarsorrhaphy was the primary treatment for inability to close the eyelid. Other mechanical techniques for reanimating lid closure are palpebral springs, encircling the upper and lower eyelids with silicone or fascia lata and temporalis muscle transfer. The most popular and widely used static procedure in facial nerve palsy is the upper eyelid gold weight implant. Gold eyelid implants are designed for the gravity assisted treatment of the functional defect of lagophthalmos resulting from facial paralysis. We report a case of a patient with facial paralysis who underwent gold weight implantation of the upper eyelid for correction of paralytic lagophthalmos.

  7. [Why and how should the patient perform a correct home blood pressure measurement?].

    Science.gov (United States)

    Krzesinski, F; Krzesinski, J M

    2009-04-01

    Home blood pressure (BP) measurement is a medical prescription. The interpretation of the results must be left to the physician. This method is complementary to the classical office BP measurement and the 24 hour ambulatory blood pressure measurement. It must be proposed to some selected patients on the basis of their capacity of learning and understanding the place of the technique for the diagnosis and the treatment compliance. It allows a more active contribution of the patient to the management of her chronic disease and, this, may improve the prevention of cardiovascular complication. A normal blood pressure during self BP measurement is equal or lower to 135/85 mmHg or even lower in high cardiovascular risk patients. This new technique, already largely used by patients, needs adequate education and good advice for buying a validated device.

  8. Measuring protein-bound glutathioine (PSSG): Critical correction for cytosolic glutathione species

    Science.gov (United States)

    Introduction: Protein glutathionylation is gaining recognition as an important posttranslational protein modification. The common first step in measuring protein glutathionylation is the denaturation and precipitation of protein away from soluble, millimolar quantities of glutathione (GSH) and glut...

  9. Studies on Written Corrective Feedback: Theoretical Perspectives, Empirical Evidence, and Future Directions

    Science.gov (United States)

    Wang, Ting; Jiang, Lin

    2015-01-01

    The role of written corrective feedback (WCF) in the process of acquiring a second language (L2) has been an issue of considerable controversies over past decades. This article intends to provide a critical review of the increasing number of WCF studies thus far and to inspire new perspectives for future research. It starts by briefly tracing the…

  10. Scoliosis correction with shape-memory metal : results of an experimental study

    NARCIS (Netherlands)

    Elstrodt, JA; Veldhuizen, AG; van Horn, [No Value

    2002-01-01

    The biocompatibility and functionality of a new scoliosis correction device, based on the properties of the shape-memory metal nickel-titanium alloy, were studied. With this device, the shape recovery forces of a shape-memory metal rod are used to achieve a gradual three-dimensional scoliosis correc

  11. Bullying in School: Case Study of Prevention and Psycho-Pedagogical Correction

    Science.gov (United States)

    Ribakova, Laysan A.; Valeeva, Roza A.; Merker, Natalia

    2016-01-01

    The purpose of the study was the theoretical justification and experimental verification of content, complex forms and methods to ensure effective prevention and psycho-pedagogical correction of bullying in school. 53 teenage students from Kazan took part in the experiment. A complex of diagnostic techniques for the detection of violence and…

  12. Collaboration between Correctional and Public School Systems Serving Juvenile Offenders: A Case Study.

    Science.gov (United States)

    Hellriegel, Kimberly L.; Yates, James R.

    1999-01-01

    This case study examined the relationship between an educational agency and a human service agency in providing services to juvenile offenders in a county-operated correctional facility as they transition to the local public school system. It urges juvenile justice and public school systems to work together to effectively meet the needs of this…

  13. Collaboration between Correctional and Public School Systems Serving Juvenile Offenders: A Case Study.

    Science.gov (United States)

    Hellriegel, Kimberly L.; Yates, James R.

    1999-01-01

    This case study examined the relationship between an educational agency and a human service agency in providing services to juvenile offenders in a county-operated correctional facility as they transition to the local public school system. It urges juvenile justice and public school systems to work together to effectively meet the needs of this…

  14. High-accuracy current measurement with low-cost shunts by means of dynamic error correction

    OpenAIRE

    Weßkamp, Patrick; Melbert, Joachim

    2016-01-01

    Measurement of electrical current is often performed by using shunt resistors. Thermal effects due to self-heating and ambient temperature variation limit the achievable accuracy, especially if low-cost shunt resistors with increased temperature coefficients are utilized. In this work, a compensation method is presented which takes static and dynamic temperature drift effects into account and provides a significant reduction of measurement error. A thermal model of the shunt...

  15. Main corrective measures in an early phase of nuclear power plants’ preparation for safe long term operation

    Energy Technology Data Exchange (ETDEWEB)

    Krivanek, Robert, E-mail: r.krivanek@iaea.org [International Atomic Energy Agency (IAEA), Department of Nuclear Safety and Security, Operational Safety Section, Vienna 1400 (Austria); Fiedler, Jan, E-mail: fiedler@fme.vutbr.cz [University of Technology Brno, Faculty of Mechanical Engineering, Energy Institute, Technická 2896/2, 616 69 Brno (Czech Republic)

    2017-05-15

    Highlights: • Results of SALTO missions provide the most important issues for safe long term operation (LTO) of nuclear power plants. • The most important technical corrective measures in an early phase of preparation for safe LTO are described. • Their satisfactory resolution creates a basis for further activities to demonstrate preparedness for safe LTO. - Abstract: This paper presents the analysis of main technical deficiencies of nuclear power plants (NPPs) in preparedness for safe long term operation (LTO) and the main corrective measures in an early phase of preparation for safe LTO of NPPs. It focuses on technical aspects connected with management of physical ageing of NPP structures, systems and components (SSCs). It uses as a basis results of IAEA SALTO missions performed between 2005 and 2016 (see also paper NED8805 in Nuclear Engineering and Design in May 2016) and the personal experiences of the authors with preparation of NPPs for safe LTO. This paper does not discuss other important aspects of safe LTO of NPPs, e.g. national nuclear energy policies, compliance of NPPs with the latest international requirements on design, obsolescence, environmental impact and economic aspects of LTO. Chapter 1 provides a brief introduction of the current status of the NPP’ fleet in connection with LTO. Chapter 2 provides an overview of SALTO peer review service results with a focus on deficiencies related to physical ageing of safety SSCs and a demonstration that SSCs will perform their safety function during the intended period of LTO. Chapter 3 discusses the main corrective measures which NPPs typically face during the preparation for demonstration of safe LTO. Chapter 4 summarizes the current status of the NPP’ fleet in connection with LTO and outlines further steps needed in preparation for safe LTO.

  16. Optical Coherence Tomography–Based Corneal Power Measurement and Intraocular Lens Power Calculation Following Laser Vision Correction (An American Ophthalmological Society Thesis)

    Science.gov (United States)

    Huang, David; Tang, Maolong; Wang, Li; Zhang, Xinbo; Armour, Rebecca L.; Gattey, Devin M.; Lombardi, Lorinna H.; Koch, Douglas D.

    2013-01-01

    Purpose: To use optical coherence tomography (OCT) to measure corneal power and improve the selection of intraocular lens (IOL) power in cataract surgeries after laser vision correction. Methods: Patients with previous myopic laser vision corrections were enrolled in this prospective study from two eye centers. Corneal thickness and power were measured by Fourier-domain OCT. Axial length, anterior chamber depth, and automated keratometry were measured by a partial coherence interferometer. An OCT-based IOL formula was developed. The mean absolute error of the OCT-based formula in predicting postoperative refraction was compared to two regression-based IOL formulae for eyes with previous laser vision correction. Results: Forty-six eyes of 46 patients all had uncomplicated cataract surgery with monofocal IOL implantation. The mean arithmetic prediction error of postoperative refraction was 0.05 ± 0.65 diopter (D) for the OCT formula, 0.14 ± 0.83 D for the Haigis-L formula, and 0.24 ± 0.82 D for the no-history Shammas-PL formula. The mean absolute error was 0.50 D for OCT compared to a mean absolute error of 0.67 D for Haigis-L and 0.67 D for Shammas-PL. The adjusted mean absolute error (average prediction error removed) was 0.49 D for OCT, 0.65 D for Haigis-L (P=.031), and 0.62 D for Shammas-PL (P=.044). For OCT, 61% of the eyes were within 0.5 D of prediction error, whereas 46% were within 0.5 D for both Haigis-L and Shammas-PL (P=.034). Conclusions: The predictive accuracy of OCT-based IOL power calculation was better than Haigis-L and Shammas-PL formulas in eyes after laser vision correction. PMID:24167323

  17. Studying Photosynthesis by Measuring Fluorescence

    Science.gov (United States)

    Sanchez, Jose Francisco; Quiles, Maria Jose

    2006-01-01

    This paper describes an easy experiment to study the absorption and action spectrum of photosynthesis, as well as the inhibition by heat, high light intensity and the presence of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the photosynthetic process. The method involves measuring the chlorophyll fluorescence emitted by intact…

  18. Method for correction of errors in observation angles for limb thermal emission measurements. [for satellite sounding of atmosphere

    Science.gov (United States)

    Abbas, M. M.; Shapiro, G. L.; Conrath, B. J.; Kunde, V. G.; Maguire, W. C.

    1984-01-01

    Thermal emission measurements of the earth's stratospheric limb from space platforms require an accurate knowledge of the observation angles for retrieval of temperature and constituent distributions. Without the use of expensive stabilizing systems, however, most observational instruments do not meet the required pointing accuracies, thus leading to large errors in the retrieval of atmospheric data. This paper describes a self-constituent method of correcting errors in pointing angles by using information contained in the observed spectrum. Numerical results based on temperature inversions of synthetic thermal emission spectra with assumed random errors in pointing angles are presented.

  19. Effect of Refractive Correction Error on Retinal Nerve Fiber Layer Thickness: A Spectralis Optical Coherence Tomography Study

    Science.gov (United States)

    Ma, Xiaoli; Chen, Yutong; Liu, Xianjie; Ning, Hong

    2016-01-01

    Background Identifying and assessing retinal nerve fiber layer defects are important for diagnosing and managing glaucoma. We aimed to investigate the effect of refractive correction error on retinal nerve fiber layer (RNFL) thickness measured with Spectralis spectral-domain optical coherence tomography (SD-OCT). Material/Methods We included 68 participants: 32 healthy (normal) and 36 glaucoma patients. RNFL thickness was measured using Spectralis SD-OCT circular scan. Measurements were made with a refractive correction of the spherical equivalent (SE), the SE+2.00D and the SE–2.00D. Results Average RNFL thickness was significantly higher in the normal group (105.88±10.47 μm) than in the glaucoma group (67.67±17.27 μm, Prefractive correction error significantly affected measurements of average (Prefractive correction error significantly increased average (Prefractive correction. However, −2.00D of refractive correction error did not significantly affect RNFL thickness measurements in either group. Conclusions Positive defocus error significantly affects RNFL thickness measurements made by the Spectralis SD-OCT. Negative defocus error did not affect RNFL measurement examined. Careful correction of refractive error is necessary to obtain accurate baseline and follow-up RNFL thickness measurements in healthy and glaucomatous eyes. PMID:28030536

  20. Orientation correction of wind direction measurements by means of staring lidar

    Science.gov (United States)

    Schmidt, Michael; José Trujillo, Juan; Kühn, Martin

    2016-09-01

    In spite of the efforts made at the time of installation of wind vanes or ultrasonic anemometers (Sonic), there is always a remaining uncertainty of several degrees in the absolute north of such sensors. In this research a method is presented to reduce the azimuthal orientation error of wind direction sensors by means of Doppler Lidar measurements. The method is based on the comparison between the conventional sensor and a distant long range lidar pointing to it in staring mode. By comparing their line-of-sight wind speeds any misalignment between both systems can be estimated more accurately. This method was applied in an measurement campaign in the offshore wind farm alpha ventus next to the meteorological mast FINO 1. The maximum alignment error of a Sonic was reduced to below ±1°. This accurate alignment has asserted, that no bias exists between Lidar and Sonic wind speed measurements.

  1. Quantitative study of FORC diagrams in thermally corrected Stoner- Wohlfarth nanoparticles systems

    Science.gov (United States)

    De Biasi, E.; Curiale, J.; Zysler, R. D.

    2016-12-01

    The use of FORC diagrams is becoming increasingly popular among researchers devoted to magnetism and magnetic materials. However, a thorough interpretation of this kind of diagrams, in order to achieve quantitative information, requires an appropriate model of the studied system. For that reason most of the FORC studies are used for a qualitative analysis. In magnetic systems thermal fluctuations "blur" the signatures of the anisotropy, volume and particle interactions distributions, therefore thermal effects in nanoparticles systems conspire against a proper interpretation and analysis of these diagrams. Motivated by this fact, we have quantitatively studied the degree of accuracy of the information extracted from FORC diagrams for the special case of single-domain thermal corrected Stoner- Wohlfarth (easy axes along the external field orientation) nanoparticles systems. In this work, the starting point is an analytical model that describes the behavior of a magnetic nanoparticles system as a function of field, anisotropy, temperature and measurement time. In order to study the quantitative degree of accuracy of our model, we built FORC diagrams for different archetypical cases of magnetic nanoparticles. Our results show that from the quantitative information obtained from the diagrams, under the hypotheses of the proposed model, is possible to recover the features of the original system with accuracy above 95%. This accuracy is improved at low temperatures and also it is possible to access to the anisotropy distribution directly from the FORC coercive field profile. Indeed, our simulations predict that the volume distribution plays a secondary role being the mean value and its deviation the only important parameters. Therefore it is possible to obtain an accurate result for the inversion and interaction fields despite the features of the volume distribution.

  2. Reproducibility and day time bias correction of optoelectronic leg volumetry: a prospective cohort study

    Directory of Open Access Journals (Sweden)

    Baumgartner Iris

    2011-10-01

    Full Text Available Abstract Background Leg edema is a common manifestation of various underlying pathologies. Reliable measurement tools are required to quantify edema and monitor therapeutic interventions. Aim of the present work was to investigate the reproducibility of optoelectronic leg volumetry over 3 weeks' time period and to eliminate daytime related within-individual variability. Methods Optoelectronic leg volumetry was performed in 63 hairdressers (mean age 45 ± 16 years, 85.7% female in standing position twice within a minute for each leg and repeated after 3 weeks. Both lower leg (legBD and whole limb (limbBF volumetry were analysed. Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW, and as intra-class correlation coefficients (ICC. Results A total of 492 leg volume measurements were analysed. Both legBD and limbBF volumetry were highly reproducible with CVA of 0.5% and 0.7%, respectively. Within-individual reproducibility of legBD and limbBF volumetry over a three weeks' period was high (CVW 1.3% for both; ICC 0.99 for both. At both visits, the second measurement revealed a significantly higher volume compared to the first measurement with a mean increase of 7.3 ml ± 14.1 (0.33% ± 0.58% for legBD and 30.1 ml ± 48.5 ml (0.52% ± 0.79% for limbBF volume. A significant linear correlation between absolute and relative leg volume differences and the difference of exact day time of measurement between the two study visits was found (P W. Conclusions Leg volume changes can be reliably assessed by optoelectronic leg volumetry at a single time point and over a 3 weeks' time period. However, volumetry results are biased by orthostatic and daytime-related volume changes. The bias for day-time related volume changes can be minimized by a time-correction formula.

  3. Pile-up corrections for high-precision superallowed {beta} decay half-life measurements via {gamma}-ray photopeak counting

    Energy Technology Data Exchange (ETDEWEB)

    Grinyer, G.F. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada)], E-mail: ggrinyer@physics.uoguelph.ca; Svensson, C.E.; Andreoiu, C. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Andreyev, A.N. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Austin, R.A.E. [Department of Astronomy and Physics, St. Mary' s University, Halifax, NS, B3H 3C3 (Canada); Ball, G.C. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Bandyopadhyay, D. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Chakrawarthy, R.S. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Finlay, P. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Garrett, P.E. [Department of Physics, University of Guelph, Guelph, Ont, Canada N1G 2W1 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Hackman, G. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Hyland, B. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Kulp, W.D. [School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 0430 (United States); Leach, K.G. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Leslie, J.R. [Department of Physics, Queen' s University, Kingston, Ont., K7L 3N6 (Canada); Morton, A.C.; Pearson, C.J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Phillips, A.A. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada); Sarazin, F. [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Schumaker, M.A. [Department of Physics, University of Guelph, Guelph, Ont, N1G 2W1 (Canada)] (and others)

    2007-09-11

    A general technique that corrects {gamma}-ray gated {beta} decay-curve data for detector pulse pile-up is presented. The method includes corrections for non-zero time-resolution and energy-threshold effects in addition to a special treatment of saturating events due to cosmic rays. This technique is verified through a Monte Carlo simulation and experimental data using radioactive beams of {sup 26}Na implanted at the center of the 8{pi}{gamma}-ray spectrometer at the ISAC facility at TRIUMF in Vancouver, Canada. The {beta}-decay half-life of {sup 26}Na obtained from counting 1809-keV {gamma}-ray photopeaks emitted by the daughter {sup 26}Mg was determined to be T{sub 1/2}=1.07167{+-}0.00055s following a 27{sigma} correction for detector pulse pile-up. This result is in excellent agreement with the result of a previous measurement that employed direct {beta} counting and demonstrates the feasibility of high-precision {beta}-decay half-life measurements through the use of high-purity germanium {gamma}-ray detectors. The technique presented here, while motivated by superallowed-Fermi {beta} decay studies, is general and can be used for all half-life determinations (e.g. {alpha}-, {beta}-, X-ray, fission) in which a {gamma}-ray photopeak is used to select the decays of a particular isotope.

  4. Determination of correction factors for borehole natural gamma-ray measurements by Monte Carlo simulations

    NARCIS (Netherlands)

    Maucec, M.; Hendriks, Peter; Limburg, J.; de Meijer, R. J.

    2009-01-01

    The analysis of natural gamma-ray spectra measured in boreholes has to take into account borehole parameters such as the presence of casings and borehole diameter. For large, high-efficiency gamma-ray detectors, such as BGO-based systems, which employ full-spectrum data analysis, corresponding corre

  5. ADC non-linear error corrections for low-noise temperature measurements in the LISA band

    Energy Technology Data Exchange (ETDEWEB)

    Sanjuan, J; Lobo, A; Mateos, N [Institut de Ciencies de l' Espai, CSIC, Fac. de Ciencies, Torre C5, 08193 Bellaterra (Spain); Ramos-Castro, J [Dep. Eng. Electronica, UPC, Campus Nord, Ed. C4, J Girona 1-3, 08034 Barcelona (Spain); DIaz-Aguilo, M, E-mail: sanjuan@ieec.fcr.e [Dep. Fisica Aplicada, UPC, Campus Nord, Ed. B4/B5, J Girona 1-3, 08034 Barcelona (Spain)

    2010-05-01

    Temperature fluctuations degrade the performance of different subsystems in the LISA mission. For instance, they can exert stray forces on the test masses and thus hamper the required drag-free accuracy. Also, the interferometric system performance depends on the stability of the temperature in the optical elements. Therefore, monitoring the temperature in specific points of the LISA subsystems is required. These measurements will be useful to identify the sources of excess noise caused by temperature fluctuations. The required temperature stability is still to be defined, but a figure around 10{mu}K Hz{sup -1/2} from 0.1 mHz to 0.1 Hz can be a good rough guess. The temperature measurement subsystem on board the LISA Pathfinder mission exhibits noise levels of 10{mu}K Hz{sup -1/2} for f >0.1 mHz. For LISA, based on the above hypothesis, the measurement system should overcome limitations related to the analog-to-digital conversion stage which degrades the performance of the measurement when temperature drifts. Investigations on the mitigation of such noise will be here presented.

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

    Directory of Open Access Journals (Sweden)

    Andreas Pfaffel

    2016-09-01

    Full Text Available Approaches to correcting correlation coefficients for range restriction have been developed under the framework of large sample theory. The accuracy of missing data techniques for correcting correlation coefficients for range restriction has thus far only been investigated with relatively large samples. However, researchers and evaluators are often faced with a small or moderate number of applicants but must still attempt to estimate the population correlation between predictor and criterion. Therefore, in the present study we investigated the accuracy of population correlation estimates and their associated standard error in terms of small and moderate sample sizes. We applied multiple imputation by chained equations for continuous and naturally dichotomous criterion variables. The results show that multiple imputation by chained equations is accurate for a continuous criterion variable, even for a small number of applicants when the selection ratio is not too small. In the case of a naturally dichotomous criterion variable, a small or moderate number of applicants leads to biased estimates when the selection ratio is small. In contrast, the standard error of the population correlation estimate is accurate over a wide range of conditions of sample size, selection ratio, true population correlation, for continuous and naturally dichotomous criterion variables, and for direct and indirect range restriction scenarios. The findings of this study provide empirical evidence about the accuracy of the correction, and support researchers and evaluators in their assessment of conditions under which correlation coefficients corrected for range restriction can be trusted.

  7. Correcting waveform bias using principal component analysis: Applications in multicentre motion analysis studies.

    Science.gov (United States)

    Clouthier, Allison L; Bohm, Eric R; Rudan, John F; Shay, Barbara L; Rainbow, Michael J; Deluzio, Kevin J

    2017-01-01

    Multicentre studies are rare in three dimensional motion analyses due to challenges associated with combining waveform data from different centres. Principal component analysis (PCA) is a statistical technique that can be used to quantify variability in waveform data and identify group differences. A correction technique based on PCA is proposed that can be used in post processing to remove nuisance variation introduced by the differences between centres. Using this technique, the waveform bias that exists between the two datasets is corrected such that the means agree. No information is lost in the individual datasets, but the overall variability in the combined data is reduced. The correction is demonstrated on gait kinematics with synthesized crosstalk and on gait data from knee arthroplasty patients collected in two centres. The induced crosstalk was successfully removed from the knee joint angle data. In the second example, the removal of the nuisance variation due to the multicentre data collection allowed significant differences in implant type to be identified. This PCA-based technique can be used to correct for differences between waveform datasets in post processing and has the potential to enable multicentre motion analysis studies.

  8. Power analysis for multivariate and repeated measurements designs via SPSS: correction and extension of D'Amico, Neilands, and Zambarano (2001).

    Science.gov (United States)

    Osborne, Jason W

    2006-05-01

    D'Amico, Neilands, and Zambarano (2001) published SPSS syntax to perform power analyses for three complex procedures: ANCOVA, MANOVA, and repeated measures ANOVA. Unfortunately, the published SPSS syntax for performing the repeated measures analysis needed some minor revision in order to perform the analysis correctly. This article presents the corrected syntax that will successfully perform the repeated measures analysis and provides some guidance on modifying the syntax to customize the analysis.

  9. Does recombinant human erythropoietin accelerate correction of post-ulcer-bleeding anaemia? A pilot study

    Institute of Scientific and Technical Information of China (English)

    Spiros D. Ladas; Dimitrios Polymeros; Thomas Pagonis; Konstantinos Triantafyllou; Gregorios Paspatis; Maria Hatziargiriou; Sotirios A.Raptis

    2004-01-01

    AIM: Anaemia caused by acute upper gastrointestinal bleeding is treated with blood transfusion or iron, but patients usually face a two-month recovery period from posthaemorrhage anaemia. This prospective, randomised, open,pilot study was designed to investigate whether recombinant human erythropoietin (Epoetin) therapy accelerate haematocrit increase in the post-bleeding recovery period.METHODS: We studied hospitalised patients admitted because of acute ulcer bleeding or haemorrhagic gastritis,who had a haematocrit of 27-33% and did not receive blood transfusions. One day after the endoscopic confirmation of cessation of bleeding, they were randomised either to erythropoietin (20 000 IU Epoetin alfa subcutaneously, on days 0, 4 and 6) plus iron (100 mg im, on days 1- 6, (G1) or iron only (G2). Haematocrit was measured on days 0, 6, 14,30, 45, and 60, respectively.RESULTS: One patient from G1 and two from G2 were lost to follow-up. Therefore, 14 and 13 patients from G1 and G2respectively were analysed. Demographic characteristics, serum iron, ferritin, total iron binding capacity, reticulocytes, and haematocrit were not significantly different at entry to the study.Median reticulocyte counts were significantly different between groups on day six (G1: 4.0, 3.0-6.4 vsG2: 3.5, 2.1-4.4%,P=0.03) and median haematocrit on day fourteen [G1: 35.9,30.7-41.0 vsG2: 32.5, 29.5-37.0% (median, range), P=0.04].CONCLUSION: Erythropoietin administration significantly accelerates correction of anemia after acute ulcer bleeding.The haematocrit gain is equivalent to one unit of transfused blood two weeks after the bleeding episode.

  10. Bias Correction and Random Error Characterization for the Assimilation of HRDI Line-of-Sight Wind Measurements

    Science.gov (United States)

    Tangborn, Andrew; Menard, Richard; Ortland, David; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A new approach to the analysis of systematic and random observation errors is presented in which the error statistics are obtained using forecast data rather than observations from a different instrument type. The analysis is carried out at an intermediate retrieval level, instead of the more typical state variable space. This method is carried out on measurements made by the High Resolution Doppler Imager (HRDI) on board the Upper Atmosphere Research Satellite (UARS). HRDI, a limb sounder, is the only satellite instrument measuring winds in the stratosphere, and the only instrument of any kind making global wind measurements in the upper atmosphere. HRDI measures doppler shifts in the two different O2 absorption bands (alpha and B) and the retrieved products are tangent point Line-of-Sight wind component (level 2 retrieval) and UV winds (level 3 retrieval). This analysis is carried out on a level 1.9 retrieval, in which the contributions from different points along the line-of-sight have not been removed. Biases are calculated from O-F (observed minus forecast) LOS wind components and are separated into a measurement parameter space consisting of 16 different values. The bias dependence on these parameters (plus an altitude dependence) is used to create a bias correction scheme carried out on the level 1.9 retrieval. The random error component is analyzed by separating the gamma and B band observations and locating observation pairs where both bands are very nearly looking at the same location at the same time. It is shown that the two observation streams are uncorrelated and that this allows the forecast error variance to be estimated. The bias correction is found to cut the effective observation error variance in half.

  11. Thresholds for Correcting Errors, Erasures, and Faulty Syndrome Measurements in Degenerate Quantum Codes.

    Science.gov (United States)

    Dumer, Ilya; Kovalev, Alexey A; Pryadko, Leonid P

    2015-07-31

    We suggest a technique for constructing lower (existence) bounds for the fault-tolerant threshold to scalable quantum computation applicable to degenerate quantum codes with sublinear distance scaling. We give explicit analytic expressions combining probabilities of erasures, depolarizing errors, and phenomenological syndrome measurement errors for quantum low-density parity-check codes with logarithmic or larger distances. These threshold estimates are parametrically better than the existing analytical bound based on percolation.

  12. Awareness and Attitude toward Refractive Error Correction Methods: A Population Based Study in Mashhad

    Directory of Open Access Journals (Sweden)

    Saber Moghaddam Ranjbar AK

    2013-10-01

    Full Text Available Objectives: This study was designed to determine the level of awareness and attitude toward refractive correction methods in a randomly selected population in Mashhad, Iran. Materials and Methods: A random cluster sampling method was applied to choose 193 subjects aged 12 years and above from Mashhad population. A structured questionnaire with open-ended and closed-ended questions was designed to gather the participants' demographic data such as: gender, age, educational status and occupation, as well as their awareness and attitude toward refractive correction methods (Spectacles, Contact lenses and Refractive surgery. Results:  In overall, 39% of the participants had a clear perception of 'ophthalmologist' and 'optometrist' terms. 80.3%, 87% and 71% of respondents had no information of contact lens application instead of spectacles, cosmetic contact lenses and contact lenses with both refractive correction and cosmetic properties, respectively. 82.5% of participants were not aware of the possibility of refractive surgery for improving their eyesight and decreasing their dependency on spectacles. Awareness about contact lenses and refractive surgery’s adverse effects were only 16% and 8%, respectively. Conclusion: Awareness and perception of refractive correction methods was low among the participants of this study. Although, ophthalmologists were the first source of consultation on sight impairments among respondents, a predominant percentage of subjects were not even aware of obvious differences between an ophthalmologist and an optometrist. These findings emphasize the necessity for proper public education on ophthalmic care and the available services, specially the new correction methods for improvement of quality of life.

  13. An analytical study of PPP-RTK corrections: precision, correlation and user-impact

    Science.gov (United States)

    Khodabandeh, A.; Teunissen, P. J. G.

    2015-11-01

    PPP-RTK extends the PPP concept by providing single-receiver users, next to orbits and clocks, also information about the satellite phase and code biases, thus enabling single-receiver ambiguity resolution. It is the goal of the present contribution to provide an analytical study of the quality of the PPP-RTK corrections as well as of their impact on the user ambiguity resolution performance. We consider the geometry-free and the geometry-based network derived corrections, as well as the impact of network ambiguity resolution on these corrections. Next to the insight that is provided by the analytical solutions, the closed form expressions of the variance matrices also demonstrate how the corrections depend on network parameters such as number of epochs, number of stations, number of satellites, and number of frequencies. As a result we are able to describe in a qualitative sense how the user ambiguity resolution performance is driven by the data from the different network scenarios.

  14. Fast atmospheric correction algorithm based on the darkest pixel approach for retrieving the aerosol optical thickness: comparison with in-situ AOT measurements

    Science.gov (United States)

    Themistocleous, Kyriacos; Hadjimitsis, Diofantos G.; Alexakis, Dimitrios

    2011-11-01

    Darkest pixel atmospheric correction is the simplest and fully image-based correction method. This paper presents an overview of a proposed 'fast atmospheric correction algorithm' developed at MATLAB based on the RT equation basics and the darkest pixel approach. The task is to retrieve the aerosol optical thickness (AOT) from the application of this atmospheric correction. The effectiveness of this algorithm is performed by comparing the AOT values from the algorithm with those measured in-situ both from MICROTOPS II hand-held sunphotometer and the CIMEL sunphotometer (AERONET).

  15. Accurate correction of magnetic field instabilities for high-resolution isochronous mass measurements in storage rings

    CERN Document Server

    Shuai, P; Zhang, Y H; Litvinov, Yu A; Wang, M; Tu, X L; Blaum, K; Zhou, X H; Yuan, Y J; Audi, G; Yan, X L; Chen, X C; Xu, X; Zhang, W; Sun, B H; Yamaguchi, T; Chen, R J; Fu, C Y; Ge, Z; Huang, W J; Liu, D W; Xing, Y M; Zeng, Q

    2014-01-01

    Isochronous mass spectrometry (IMS) in storage rings is a successful technique for accurate mass measurements of short-lived nuclides with relative precision of about $10^{-5}-10^{-7}$. Instabilities of the magnetic fields in storage rings are one of the major contributions limiting the achievable mass resolving power, which is directly related to the precision of the obtained mass values. A new data analysis method is proposed allowing one to minimise the effect of such instabilities. The masses of the previously measured at the CSRe $^{41}$Ti, $^{43}$V, $^{47}$Mn, $^{49}$Fe, $^{53}$Ni and $^{55}$Cu nuclides were re-determined with this method. An improvement of the mass precision by a factor of $\\sim 1.7$ has been achieved for $^{41}$Ti and $^{43}$V. The method can be applied to any isochronous mass experiment irrespective of the accelerator facility. Furthermore, the method can be used as an on-line tool for checking the isochronous conditions of the storage ring.

  16. NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models.

    Science.gov (United States)

    Hsu, Li-Ta; Gu, Yanlei; Kamijo, Shunsuke

    2015-07-17

    Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

  17. Measurement and correction of the 3rd order resonance in the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, F.; /CERN; Alexahin, Y.; Lebedev, V.; Still, D.; Valishev, A.; /Fermilab

    2006-06-01

    At Fermilab Tevatron BPM system has been recently upgraded resulting much better accuracy of beam position measurements and improvements of data acquisition for turn-by-turn measurements. That allows one to record the beam position at each turn for 8000 turns for all BPMs (118 in each plane) with accuracy of about 10-20 {micro}m. In the last decade a harmonic analysis tool has been developed at CERN that allows relating each FFT line derived from the BPM data with a particular non-linear resonance in the machine. In fact, one can even detect the longitudinal position of the sources of these resonances. Experiments have been performed at the Tevatron in which beams have been kicked to various amplitudes to analyze the 3rd order resonance. It was possible to address this rather large resonance to some regular machine sextupoles. An alternative sextupole scheme allowed the suppression of this resonance by a good factor of 2. Lastly, the experimental data are compared with model calculations.

  18. Measuring party nationalisation: A new Gini-based indicator that corrects for the number of units

    DEFF Research Database (Denmark)

    Bochsler, Daniel

    2010-01-01

    The study of the territorial distribution of votes in elections has become an important field of the political party research in recent years. Quantitative studies on the homogeneity of votes and turnout employ different indicators of territorial variance, but despite important progresses...

  19. The need for seasonal correction functions when calculating the annual electricity use of appliances based on shorter period measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bennich, Peter (Testlab, The Swedish Energy Agency, Eskilstuna (Sweden)); Oefverholm, Egil; Bjoern, Torgny (The Swedish Energy Agency, Eskilstuna (Sweden)); Norstedt, Inger (The Swedish Consumer Agency, Stockholm (Sweden))

    2011-07-01

    Along with the increasing number of smart electricity meters in the homes - both meters installed by the utilities and simpler ones installed by the household owners themselves - the interest in reliable methods for scaling up data measured during a limited time of the year to annual values, will most likely increase. For example, by measuring some specific loads for some time in a home, an inhabitant may assess possible annual savings when replacing old appliances with new ones. However, a straight forward scaling up calculation to annual values is not always appropriate. An obvious example is lighting, which displays a clear seasonal effect due to the difference in daylight: annual values based on measured summer data will strongly underestimate the annual consumption whereas winter data will lead to an overestimate. Another example going in the opposite direction is cold appliances, where the increase in ambient temperature during the summer increases the electricity consumption. This paper discusses an analysis of a set of appliances which nearly all display different seasonal effects. Apart from lighting and cold appliances, also washing machines, dish washers, TVs and PCs are analysed. Factors influencing the seasonality are discussed; either it is due to behaviour and/or technical parameters as well. Our analysis is based on 10 min measurements of appliances in 400 randomly selected households in Sweden. 40 households were measured during a full year and provided data for establishing seasonal correction functions. (See Appendix 1 for more details on the methodology.)

  20. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    Science.gov (United States)

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry.

  1. Correction for the 17O interference in δ(13C) measurements when analyzing CO2 with stable isotope mass spectrometry

    Science.gov (United States)

    Coplen, Tyler B.; Brand, Willi A.; Assonov, Sergey S.

    2010-01-01

    Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011 180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 – λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygen-bearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.

  2. POGO satellite orbit corrections: an opportunity to improve the quality of the geomagnetic field measurements?

    Science.gov (United States)

    Stockmann, Reto; Christiansen, Freddy; Olsen, Nils; Jackson, Andrew

    2015-06-01

    We present an attempt to improve the quality of the geomagnetic field measurements from the Polar Orbiting Geophysical Observatory (POGO) satellite missions in the late 1960s. Inaccurate satellite positions are believed to be a major source of errors for using the magnetic observations for field modelling. To improve the data, we use an iterative approach consisting of two main parts: one is a main field modelling process to obtain the radial field gradient to perturb the orbits and the other is the state-of-the-art GPS orbit modelling software BERNESE to calculate new physical orbits. We report results based on a single-day approach showing a clear increase of the data quality. That single-day approach leads, however, to undesirable orbital jumps at midnight. Furthermore, we report results obtained for a much larger data set comprising almost all of the data from the three missions. With this approach, we eliminate the orbit discontinuities at midnight but only tiny quality improvements could be achieved for geomagnetically quiet data. We believe that improvements to the data are probably still possible, but it would require the original tracking observations to be found.

  3. Correcting for Test Score Measurement Error in ANCOVA Models for Estimating Treatment Effects

    Science.gov (United States)

    Lockwood, J. R.; McCaffrey, Daniel F.

    2014-01-01

    A common strategy for estimating treatment effects in observational studies using individual student-level data is analysis of covariance (ANCOVA) or hierarchical variants of it, in which outcomes (often standardized test scores) are regressed on pretreatment test scores, other student characteristics, and treatment group indicators. Measurement…

  4. High-precision measurement of (186)Os/(188)Os and (187)Os/(188)Os: isobaric oxide corrections with in-run measured oxygen isotope ratios.

    Science.gov (United States)

    Chu, Zhu-Yin; Li, Chao-Feng; Chen, Zhi; Xu, Jun-Jie; Di, Yan-Kun; Guo, Jing-Hui

    2015-09-01

    We present a novel method for high precision measurement of (186)Os/(188)Os and (187)Os/(188)Os ratios, applying isobaric oxide interference correction based on in-run measurements of oxygen isotopic ratios. For this purpose, we set up a static data collection routine to measure the main Os(16)O3(-) ion beams with Faraday cups connected to conventional 10(11) amplifiers, and (192)Os(16)O2(17)O(-) and (192)Os(16)O2(18)O(-) ion beams with Faraday cups connected to 10(12) amplifiers. Because of the limited number of Faraday cups, we did not measure (184)Os(16)O3(-) and (189)Os(16)O3(-) simultaneously in-run, but the analytical setup had no significant influence on final (186)Os/(188)Os and (187)Os/(188)Os data. By analyzing UMd, DROsS, an in-house Os solution standard, and several rock reference materials, including WPR-1, WMS-1a, and Gpt-5, the in-run measured oxygen isotopic ratios were proven to present accurate Os isotopic data. However, (186)Os/(188)Os and (187)Os/(188)Os data obtained with in-run O isotopic compositions for the solution standards and rock reference materials show minimal improvement in internal and external precision, compared to the conventional oxygen correction method. We concluded that, the small variations of oxygen isotopes during OsO3(-) analytical sessions are probably not the main source of error for high precision Os isotopic analysis. Nevertheless, use of run-specific O isotopic compositions is still a better choice for Os isotopic data reduction and eliminates the requirement of extra measurements of the oxygen isotopic ratios.

  5. Development of Tissue to Total Mass Correction Factor for Porites divaricata in Calcification Rate Studies

    Science.gov (United States)

    Cannone, T. C.; Kelly, S. K.; Foster, K.

    2013-05-01

    One anticipated result of ocean acidification is lower calcification rates of corals. Many studies currently use the buoyant weights of coral nubbins as a means of estimating skeletal weight during non-destructive experiments. The objectives of this study, conducted at the Little Cayman Research Centre, were twofold: (1) to determine whether the purple and yellow color variations of Porites divaricata had similar tissue mass to total mass ratios; and (2) to determine a correction factor for tissue mass based on the total coral mass. T-test comparisons indicated that the tissue to total mass ratios were statistically similar for purple and yellow cohorts, thus allowing them to be grouped together within a given sample population. Linear regression analysis provided a correction factor (r2 = 0.69) to estimate the tissue mass from the total mass, which may eliminate the need to remove tissue during studies and allow subsequent testing on the same nubbins or their return to the natural environment. Additional work is needed in the development of a correction factor for P. divaricata with a higher prediction accuracy.

  6. Measuring food intake in studies of obesity.

    Science.gov (United States)

    Lissner, Lauren

    2002-12-01

    The problem of how to measure habitual food intake in studies of obesity remains an enigma in nutritional research. The existence of obesity-specific underreporting was rather controversial until the advent of the doubly labelled water technique gave credence to previously anecdotal evidence that such a bias does in fact exist. This paper reviews a number of issues relevant to interpreting dietary data in studies involving obesity. Topics covered include: participation biases, normative biases,importance of matching method to study, selective underreporting, and a brief discussion of the potential implications of generalised and selective underreporting in analytical epidemiology. It is concluded that selective underreporting of certain food types by obese individuals would produce consequences in analytical epidemiological studies that are both unpredictable and complex. Since it is becoming increasingly acknowledged that selective reporting error does occur, it is important to emphasise that correction for energy intake is not sufficient to eliminate the biases from this type of error. This is true both for obesity-related selective reporting errors and more universal types of selective underreporting, e.g. foods of low social desirability. Additional research is urgently required to examine the consequences of this type of error.

  7. Performance Improvement of Membrane Stress Measurement Equipment through Evaluation of Added Mass of Membrane and Error Correction

    Directory of Open Access Journals (Sweden)

    Sang-Wook Jin

    2017-01-01

    Full Text Available One of the most important issues in keeping membrane structures in stable condition is to maintain the proper stress distribution over the membrane. However, it is difficult to determine the quantitative real stress level in the membrane after the completion of the structure. The stress relaxation phenomenon of the membrane and the fluttering effect due to strong wind or ponding caused by precipitation may cause severe damage to the membrane structure itself. Therefore, it is very important to know the magnitude of the existing stress in membrane structures for their maintenance. The authors have proposed a new method for separately estimating the membrane stress in two different directions using sound waves instead of directly measuring the membrane stress. The new method utilizes the resonance phenomenon of the membrane, which is induced by sound excitations given through an audio speaker. During such experiment, the effect of the surrounding air on the vibrating membrane cannot be overlooked in order to assure high measurement precision. In this paper, an evaluation scheme for the added mass of membrane with the effect of air on the vibrating membrane and the correction of measurement error is discussed. In addition, three types of membrane materials are used in the experiment in order to verify the expandability and accuracy of the membrane measurement equipment.

  8. Correcting for bias of molecular confinement parameters induced by small-time-series sample sizes in single-molecule trajectories containing measurement noise

    Science.gov (United States)

    Calderon, Christopher P.

    2013-07-01

    Several single-molecule studies aim to reliably extract parameters characterizing molecular confinement or transient kinetic trapping from experimental observations. Pioneering works from single-particle tracking (SPT) in membrane diffusion studies [Kusumi , Biophys. J.BIOJAU0006-349510.1016/S0006-3495(93)81253-0 65, 2021 (1993)] appealed to mean square displacement (MSD) tools for extracting diffusivity and other parameters quantifying the degree of confinement. More recently, the practical utility of systematically treating multiple noise sources (including noise induced by random photon counts) through likelihood techniques has been more broadly realized in the SPT community. However, bias induced by finite-time-series sample sizes (unavoidable in practice) has not received great attention. Mitigating parameter bias induced by finite sampling is important to any scientific endeavor aiming for high accuracy, but correcting for bias is also often an important step in the construction of optimal parameter estimates. In this article, it is demonstrated how a popular model of confinement can be corrected for finite-sample bias in situations where the underlying data exhibit Brownian diffusion and observations are measured with non-negligible experimental noise (e.g., noise induced by finite photon counts). The work of Tang and Chen [J. Econometrics0304-407610.1016/j.jeconom.2008.11.001 149, 65 (2009)] is extended to correct for bias in the estimated “corral radius” (a parameter commonly used to quantify confinement in SPT studies) in the presence of measurement noise. It is shown that the approach presented is capable of reliably extracting the corral radius using only hundreds of discretely sampled observations in situations where other methods (including MSD and Bayesian techniques) would encounter serious difficulties. The ability to accurately statistically characterize transient confinement suggests additional techniques for quantifying confined and/or hop

  9. GRACE leakage error correction with regularization technique: Case studies in Greenland and Antarctica

    Science.gov (United States)

    Mu, Dapeng; Yan, Haoming; Feng, Wei; Peng, Peng

    2017-01-01

    Filtering is a necessary step in the Gravity Recovery and Climate Experiment (GRACE) data processing, but leads to signal leakage and attenuation obviously, and adversely affects the quality of global and regional mass change estimates. We propose to use the Tikhonov regularization technique with the L-curve method to solve a correction equation which can reduce the leakage error caused by filter involved in GRACE data processing. We first demonstrate that the leakage error caused by the Gaussian filter can be well corrected by our regularization technique with simulation studies in Greenland and Antarctica. Furthermore, our regularization technique can restore the spatial distribution of original mass changes. For example, after applying the regularization method to GRAEC data (2003-2012), we find that GRACE mass changes tend to move from interior to coastal area in Greenland, which are consistent with recent other studies. After being corrected for glacial isostatic adjustment (GIA) effect, our results show that the ice mass loss rates were 274 ± 30 and 107 ± 34 Gt/yr in Greenland and Antarctica from 2003 to 2012, respectively. And a 10 ± 4 Gt/yr increase rate in Greenland interior is also detected.

  10. Did I say dog or cat? A study of semantic error detection and correction in children.

    Science.gov (United States)

    Hanley, J Richard; Cortis, Cathleen; Budd, Mary-Jane; Nozari, Nazbanou

    2016-02-01

    Although naturalistic studies of spontaneous speech suggest that young children can monitor their speech, the mechanisms for detection and correction of speech errors in children are not well understood. In particular, there is little research on monitoring semantic errors in this population. This study provides a systematic investigation of detection and correction of semantic errors in children between the ages of 5 and 8years as they produced sentences to describe simple visual events involving nine highly familiar animals (the moving animals task). Results showed that older children made fewer errors and corrected a larger proportion of the errors that they made than younger children. We then tested the prediction of a production-based account of error monitoring that the strength of the language production system, and specifically its semantic-lexical component, should be correlated with the ability to detect and repair semantic errors. Strength of semantic-lexical mapping, as well as lexical-phonological mapping, was estimated individually for children by fitting their error patterns, obtained from an independent picture-naming task, to a computational model of language production. Children's picture-naming performance was predictive of their ability to monitor their semantic errors above and beyond age. This relationship was specific to the strength of the semantic-lexical part of the system, as predicted by the production-based monitor.

  11. Retrospective study comparing model-based deformation correction to intraoperative magnetic resonance imaging for image-guided neurosurgery.

    Science.gov (United States)

    Luo, Ma; Frisken, Sarah F; Weis, Jared A; Clements, Logan W; Unadkat, Prashin; Thompson, Reid C; Golby, Alexandra J; Miga, Michael I

    2017-07-01

    Brain shift during tumor resection compromises the spatial validity of registered preoperative imaging data that is critical to image-guided procedures. One current clinical solution to mitigate the effects is to reimage using intraoperative magnetic resonance (iMR) imaging. Although iMR has demonstrated benefits in accounting for preoperative-to-intraoperative tissue changes, its cost and encumbrance have limited its widespread adoption. While iMR will likely continue to be employed for challenging cases, a cost-effective model-based brain shift compensation strategy is desirable as a complementary technology for standard resections. We performed a retrospective study of [Formula: see text] tumor resection cases, comparing iMR measurements with intraoperative brain shift compensation predicted by our model-based strategy, driven by sparse intraoperative cortical surface data. For quantitative assessment, homologous subsurface targets near the tumors were selected on preoperative MR and iMR images. Once rigidly registered, intraoperative shift measurements were determined and subsequently compared to model-predicted counterparts as estimated by the brain shift correction framework. When considering moderate and high shift ([Formula: see text], [Formula: see text] measurements per case), the alignment error due to brain shift reduced from [Formula: see text] to [Formula: see text], representing [Formula: see text] correction. These first steps toward validation are promising for model-based strategies.

  12. Supersymmetric QCD corrections and phenomenological studies in relation to coannihilation of dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Harz, Julia

    2013-11-15

    In this thesis, we assume a minimal supersymmetric extension of the Standard Model (MSSM) with conserved R-parity such that the lightest neutralino is the cold dark matter candidate. A stringent constraint on the MSSM parameter space can be set by the comparison of the predicted neutralino relic density with the experimentally determined value. In order to match the high experimental precision, uncertainties within the theoretical calculation have to be reduced. One of the main uncertainties arises from the cross section of annihilation and coannihilation processes of the dark matter particle. In a phenomenological study we investigate the interplay of neutralino-neutralino annihilation, neutralino-stop coannihilation and stop-stop annihilation. We demonstrate that neutralino-stop coannihilation contributes significantly to the neutralino relic density and is furthermore very well motivated due to the recent discovery of a 125 GeV Higgs boson. Due to this ample motivation we have calculated the full O({alpha}{sub s}) supersymmetric QCD corrections to neutralino-squark coannihilation. We show in detail our DR/on-shell renormalization scheme for the treatment of ultraviolet divergences, and describe the phase space slicing method which is used to handle soft and collinear infrared divergences. Further, we comment on the treatment of occurring intermediate onshell states. The whole calculation is provided within the numerical tool DM rate at NLO that serves as an extension to existing relic density calculators, which consider only an effective tree-level calculation. Based on three example scenarios we study the impact of the NLO corrections on the total (co)annihilation cross section, and observe corrections of up to 30 %. This leads to a correction of 5 - 9 % on the relic density, which is larger than the current experimental uncertainty and is, thus, important to be taken into account.

  13. The "residential" effect fallacy in neighborhood and health studies: formal definition, empirical identification, and correction.

    Science.gov (United States)

    Chaix, Basile; Duncan, Dustin; Vallée, Julie; Vernez-Moudon, Anne; Benmarhnia, Tarik; Kestens, Yan

    2017-07-31

    Because of confounding from the urban/rural and socioeconomic organizations of territories and resulting correlation between residential and nonresidential exposures, classically estimated residential neighborhood-outcome associations capture nonresidential environment effects, overestimating residential intervention effects. Our study diagnosed and corrected this "residential" effect fallacy bias applicable to a large fraction of neighborhood and health studies. Our empirical application investigated the effect that hypothetical interventions raising the residential number of services would have on the probability that a trip is walked. Using global positioning systems (GPS) tracking and mobility surveys over 7 days (227 participants, 7440 trips), we employed a multilevel linear probability model to estimate the trip-level association between residential number of services and walking to derive a naïve intervention effect estimate; and a corrected model accounting for numbers of services at the residence, trip origin, and trip destination to determine a corrected intervention effect estimate (true effect conditional on assumptions). There was a strong correlation in service densities between the residential neighborhood and nonresidential places. From the naïve model, hypothetical interventions raising the residential number of services to 200, 500, and 1000 were associated with an increase by 0.020, 0.055, and 0.109 of the probability of walking in the intervention groups. Corrected estimates were of 0.007, 0.019, and 0.039. Thus, naïve estimates were overestimated by multiplicative factors of 3.0, 2.9, and 2.8. Commonly estimated residential intervention-outcome associations substantially overestimate true effects. Our somewhat paradoxical conclusion is that, to estimate residential effects, investigators critically need information on nonresidential places visited.

  14. Fingerprinting the extended Higgs sector using one-loop corrected Higgs boson couplings and future precision measurements

    Directory of Open Access Journals (Sweden)

    Shinya Kanemura

    2015-07-01

    Full Text Available We calculate radiative corrections to a full set of coupling constants for the 125 GeV Higgs boson at the one-loop level in two Higgs doublet models with four types of Yukawa interaction under the softly-broken discrete Z2 symmetry. The renormalization calculations are performed in the on-shell scheme, in which the gauge dependence in the mixing parameter which appears in the previous calculation is consistently avoided. We first show the details of our renormalization scheme, and present the complete set of the analytic formulae of the renormalized couplings. We then numerically demonstrate how the inner parameters of the model can be extracted by the future precision measurements of these couplings at the high luminosity LHC and the International Linear Collider.

  15. Fingerprinting the extended Higgs sector using one-loop corrected Higgs boson couplings and future precision measurements

    CERN Document Server

    Kanemura, Shinya; Yagyu, Kei

    2015-01-01

    We calculate radiative corrections to a full set of coupling constants for the 125 GeV Higgs boson at the one-loop level in two Higgs doublet models with four types of Yukawa interaction under the softly-broken discrete $Z_2$ symmetry. The renormalization calculations are performed in the on-shell scheme, in which the gauge dependence in the mixing parameter which appears in the previous calculation is consistently avoided. We first show the details of our renormalizaton scheme, and present the complete set of the analytic formulae of the renormalized couplings. We then numerically demonstrate how the inner parameters of the model can be extracted by the future precision measurements of these couplings at the high luminosity LHC and the International Linear Collider.

  16. Gyroscopic corrections improve wearable sensor data prior to measuring dynamic sway in the gait of people with Multiple Sclerosis.

    Science.gov (United States)

    Brodie, Matthew A D; Psarakis, Michael; Hoang, Phu

    2016-09-01

    Accelerometers are incorporated into many consumer devices providing new ways to monitor gait, mobility, and fall risk. However, many health benefits have not been realised because of issues with data quality that results from gravitational 'cross-talk' when the wearable device is tilted. Here we present an adaptive filter designed to improve the quality of accelerometer data prior to measuring dynamic pelvic sway patterns during a six minute walk test in people with and without Multiple Sclerosis (MS). Optical motion capture was used as the gold standard. Improved wearable device accuracy (≤4.4% NRMSE) was achieved using gyroscopic corrections and scaling filter thresholds by step frequency. The people with MS presented significantly greater pelvis sway range to compensate for their lower limb weaknesses and joint contractures. The visualisation of asymmetric pelvic sway in people with MS illustrates the potential to better understand their mobility impairments for reducing fall risk.

  17. An Empirical Study of Atmospheric Correction Procedures for Regional Infrasound Amplitudes with Ground Truth.

    Science.gov (United States)

    Howard, J. E.

    2014-12-01

    This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.

  18. An example of model result correction to study the impact of climate change on electricity consumption

    Science.gov (United States)

    Parey, S.; Galloy, G.; Nogaj, M.

    2012-04-01

    Climate is changing and temperature evolutions are thought to impact electricity consumption in the future. In order to estimate these possible shifts, climate model results for two future periods: 2050 and 2100 are considered. However, the use of the electricity consumption forecast model with climate model outputs for the current period give unrealistic results compared to forecasts made with observations. As a matter of fact, consumption is forecasted using a taylor-designed mean of French temperatures. Therefore, it is necessary for the model results to be as close as possible to this observed mean. The first studies had been made using the so-called "delta method", which consists in adding future changes to the observations. This however supposes that there is no variance change, which is not necessarily valid. Thus, in a second step, the percentile correction method has been used, firstly considering the whole annual distribution. This is however not satisfactory, as the seasonal distributions remain too much biased. Thus, the correction had to be applied on a monthly basis. The method and results of the correction will be presented for this example of France.

  19. Hydrogen isotope correction for laser instrument measurement bias at low water vapor concentration using conventional isotope analyses: application to measurements from Mauna Loa Observatory, Hawaii.

    Science.gov (United States)

    Johnson, L R; Sharp, Z D; Galewsky, J; Strong, M; Van Pelt, A D; Dong, F; Noone, D

    2011-03-15

    The hydrogen and oxygen isotope ratios of water vapor can be measured with commercially available laser spectroscopy analyzers in real time. Operation of the laser systems in relatively dry air is difficult because measurements are non-linear as a function of humidity at low water concentrations. Here we use field-based sampling coupled with traditional mass spectrometry techniques for assessing linearity and calibrating laser spectroscopy systems at low water vapor concentrations. Air samples are collected in an evacuated 2 L glass flask and the water is separated from the non-condensable gases cryogenically. Approximately 2 µL of water are reduced to H(2) gas and measured on an isotope ratio mass spectrometer. In a field experiment at the Mauna Loa Observatory (MLO), we ran Picarro and Los Gatos Research (LGR) laser analyzers for a period of 25 days in addition to periodic sample collection in evacuated flasks. When the two laser systems are corrected to the flask data, they are strongly coincident over the entire 25 days. The δ(2)H values were found to change by over 200‰ over 2.5 min as the boundary layer elevation changed relative to MLO. The δ(2)H values ranged from -106 to -332‰, and the δ(18)O values (uncorrected) ranged from -12 to -50‰. Raw data from laser analyzers in environments with low water vapor concentrations can be normalized to the international V-SMOW scale by calibration to the flask data measured conventionally. Bias correction is especially critical for the accurate determination of deuterium excess in dry air.

  20. Comparison of different cell type correction methods for genome-scale epigenetics studies.

    Science.gov (United States)

    Kaushal, Akhilesh; Zhang, Hongmei; Karmaus, Wilfried J J; Ray, Meredith; Torres, Mylin A; Smith, Alicia K; Wang, Shu-Li

    2017-04-14

    Whole blood is frequently utilized in genome-wide association studies of DNA methylation patterns in relation to environmental exposures or clinical outcomes. These associations can be confounded by cellular heterogeneity. Algorithms have been developed to measure or adjust for this heterogeneity, and some have been compared in the literature. However, with new methods available, it is unknown whether the findings will be consistent, if not which method(s) perform better. Methods: We compared eight cell-type correction methods including the method in the minfi R package, the method by Houseman et al., the Removing unwanted variation (RUV) approach, the methods in FaST-LMM-EWASher, ReFACTor, RefFreeEWAS, and RefFreeCellMix R programs, along with one approach utilizing surrogate variables (SVAs). We first evaluated the association of DNA methylation at each CpG across the whole genome with prenatal arsenic exposure levels and with cancer status, adjusted for estimated cell-type information obtained from different methods. We then compared CpGs showing statistical significance from different approaches. For the methods implemented in minfi and proposed by Houseman et al., we utilized homogeneous data with composition of some blood cells available and compared them with the estimated cell compositions. Finally, for methods not explicitly estimating cell compositions, we evaluated their performance using simulated DNA methylation data with a set of latent variables representing "cell types". Results from the SVA-based method overall showed the highest agreement with all other methods except for FaST-LMM-EWASher. Using homogeneous data, minfi provided better estimations on cell types compared to the originally proposed method by Houseman et al. Further simulation studies on methods free of reference data revealed that SVA provided good sensitivities and specificities, RefFreeCellMix in general produced high sensitivities but specificities tended to be low when

  1. Correction for FDG PET dose extravasations: Monte Carlo validation and quantitative evaluation of patient studies

    Energy Technology Data Exchange (ETDEWEB)

    Silva-Rodríguez, Jesús, E-mail: jesus.silva.rodriguez@sergas.es; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es [Fundación Ramón Domínguez, Santiago de Compostela, Galicia (Spain); Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Sánchez, Manuel; Mosquera, Javier; Luna-Vega, Víctor [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Cortés, Julia; Garrido, Miguel [Servicio de Medicina Nuclear, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia, Spain and Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Pombar, Miguel [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia (Spain); Ruibal, Álvaro [Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Fundación Tejerina, 28003, Madrid (Spain)

    2014-05-15

    Purpose: Current procedure guidelines for whole body [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) state that studies with visible dose extravasations should be rejected for quantification protocols. Our work is focused on the development and validation of methods for estimating extravasated doses in order to correct standard uptake value (SUV) values for this effect in clinical routine. Methods: One thousand three hundred sixty-seven consecutive whole body FDG-PET studies were visually inspected looking for extravasation cases. Two methods for estimating the extravasated dose were proposed and validated in different scenarios using Monte Carlo simulations. All visible extravasations were retrospectively evaluated using a manual ROI based method. In addition, the 50 patients with higher extravasated doses were also evaluated using a threshold-based method. Results: Simulation studies showed that the proposed methods for estimating extravasated doses allow us to compensate the impact of extravasations on SUV values with an error below 5%. The quantitative evaluation of patient studies revealed that paravenous injection is a relatively frequent effect (18%) with a small fraction of patients presenting considerable extravasations ranging from 1% to a maximum of 22% of the injected dose. A criterion based on the extravasated volume and maximum concentration was established in order to identify this fraction of patients that might be corrected for paravenous injection effect. Conclusions: The authors propose the use of a manual ROI based method for estimating the effectively administered FDG dose and then correct SUV quantification in those patients fulfilling the proposed criterion.

  2. Spectral interference corrections for the measurement of (238)U in materials rich in thorium by a high resolution gamma-ray spectrometry.

    Science.gov (United States)

    Yücel, H; Solmaz, A N; Köse, E; Bor, D

    2009-11-01

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively.

  3. Using intervention-oriented evaluation to diagnose and correct students' persistent climate change misconceptions: A Singapore case study.

    Science.gov (United States)

    Pascua, Liberty; Chang, Chew-Hung

    2015-10-01

    The evaluation of classroom-based educational interventions is fraught with tensions, the most critical of which is choosing between focusing the inquiry on measuring the effects of treatment or in proximately utilizing the data to improve practice. This paper attempted to achieve both goals through the use of intervention-oriented evaluation of a professional development program intended to diagnose and correct students' misconceptions of climate change. Data was gathered, monitored and analyzed in three stages of a time-series design: the baseline, treatment and follow-up stages. The evaluation itself was the 'intervention' such that the data was allowed to 'contaminate' the treatment. This was achieved through giving the teacher unimpeded access to the collected information and to introduce midcourse corrections as she saw fit to her instruction. Results showed a significant development in students' conceptual understanding only after the teacher's decision to use direct and explicit refutation of misconceptions. Due to the accessibility of feedback, it was possible to locate specifically at which point in the process that the intervention was most effective. The efficacy of the intervention was then measured through comparing the scores across the three research stages. The inclusion of a comparison group to the design is recommended for future studies.

  4. Laser speckle contrast imaging of blood flow from anesthetized mice: correcting drifts in measurements due to breathing movements

    Science.gov (United States)

    Nogueira, Gesse E. C.; Ribeiro, Márcio A. C.; Campos, Juliane C.; Ferreira, Julio C. B.

    2015-06-01

    Background: Laser speckle contrast imaging allows non-invasive assessment of cutaneous blood flow. Although the technique is attractive to measure a quantity related to the skin blood flow (SBF) in anesthetized animal models, movements from breathing can mask the SBF signal. As a consequence, the measurement is overestimated because a variable amount of a DC component due to the breathing movements is added to the SBF signal. Objective: To evaluate a method for estimating the background level of the SBF signal, rejecting artefacts from breathing. Methods: A baseline correction method used for accurate DNA sequencing was evaluated, based on estimating the background level of a signal in small temporal sliding-windows. The method was applied to evaluate a mouse model of hindlimb ischemia. SBF signals from hindlimbs of anesthetized C57BL/6 mice (n=13) were registered. The mean SBF (Fi and Fc from ischemic and control hindlimbs) were computed from the registers and from the corresponding estimated background levels (Fib and Fcb from ischemic and control hindlimbs). Results: The mean values of the percentages (a measure of ischemia) MI = (Fi/Fc).100 and MIb = (Fib/Fcb).100 were computed to be 30+/-4% and 23+/-3% respectively (mean +/- SE). Evidences of statistical differences between both, ischemic and control hindlimbs, were obtained (p<0.05, paired student-t). The mean error [(MI-MIb)/MIb].100 obtained was 45+/-14% (mean+/-SE). Conclusion: The recovery of a corrupted SBF signal by breathing artefacts is feasible, allowing more accurate measurements.

  5. Determination of the mass attenuation coefficients for X-ray fluorescence measurements correction by the Rayleigh to Compton scattering ratio

    Energy Technology Data Exchange (ETDEWEB)

    Conti, C.C., E-mail: ccconti@ird.gov.br [Institute for Radioprotection and Dosimetry – IRD/CNEN, Rio de Janeiro (Brazil); Physics Institute, State University of Rio de Janeiro – UERJ, Rio de Janeiro (Brazil); Anjos, M.J. [Physics Institute, State University of Rio de Janeiro – UERJ, Rio de Janeiro (Brazil); Salgado, C.M. [Nuclear Engineering Institute – IEN/CNEN, Rio de Janeiro (Brazil)

    2014-09-15

    Highlights: •This work describes a procedure for sample self-absorption correction. •The use of Monte Carlo simulation to calculate the mass attenuation coefficients curve was effective. •No need for transmission measurement, saving time, financial resources and effort. •This article provides de curves for the 90° scattering angle. •Calculation on-line at (www.macx.net.br). -- Abstract: X-ray fluorescence technique plays an important role in nondestructive analysis nowadays. The development of equipment, including portable ones, enables a wide assortment of possibilities for analysis of stable elements, even in trace concentrations. Nevertheless, despite of the advantages, one important drawback is radiation self-attenuation in the sample being measured, which needs to be considered in the calculation for the proper determination of elemental concentration. The mass attenuation coefficient can be determined by transmission measurement, but, in this case, the sample must be in slab shape geometry and demands two different setups and measurements. The Rayleigh to Compton scattering ratio, determined from the X-ray fluorescence spectrum, provides a link to the mass attenuation coefficient by means of a polynomial type equation. This work presents a way to construct a Rayleigh to Compton scattering ratio versus mass attenuation coefficient curve by using the MCNP5 Monte Carlo computer code. The comparison between the calculated and literature values of the mass attenuation coefficient for some known samples showed to be within 15%. This calculation procedure is available on-line at (www.macx.net.br)

  6. Estimation of an image derived input function with MR-defined carotid arteries in FDG-PET human studies using a novel partial volume correction method

    DEFF Research Database (Denmark)

    Sari, Hasan; Erlandsson, Kjell; Law, Ian

    2017-01-01

    Kinetic analysis of (18)F-fluorodeoxyglucose positron emission tomography data requires an accurate knowledge the arterial input function. The gold standard method to measure the arterial input function requires collection of arterial blood samples and is an invasive method. Measuring an image...... segmentation of the carotid arteries from MR images. The simulation study results showed that at least 92% of the true intensity could be recovered after the partial volume correction. Results from 19 subjects showed that the mean cerebral metabolic rate of glucose calculated using arterial samples and partial...... volume corrected image derived input function were 26.9 and 25.4 mg/min/100 g, respectively, for the grey matter and 7.2 and 6.7 mg/min/100 g for the white matter. No significant difference in the estimated cerebral metabolic rate of glucose values was observed between arterial samples and corrected...

  7. The Effects of Computer-Mediated Synchronous and Asynchronous Direct Corrective Feedback on Writing: A Case Study

    Science.gov (United States)

    Shintani, Natsuko

    2016-01-01

    This case study investigated the characteristics of computer-mediated synchronous corrective feedback (SCF, provided while students wrote) and asynchronous corrective feedback (ACF, provided after students had finished writing) in an EFL writing task. The task, designed to elicit the use of the hypothetical conditional, was completed by two…

  8. Comments and corrections on 3D modeling studies of locomotor muscle moment arms in archosaurs

    Directory of Open Access Journals (Sweden)

    Karl Bates

    2015-10-01

    Full Text Available In a number of recent studies we used computer modeling to investigate the evolution of muscle leverage (moment arms and function in extant and extinct archosaur lineages (crocodilians, dinosaurs including birds and pterosaurs. These studies sought to quantify the level of disparity and convergence in muscle moment arms during the evolution of bipedal and quadrupedal posture in various independent archosaur lineages, and in doing so further our understanding of changes in anatomy, locomotion and ecology during the group’s >250 million year evolutionary history. Subsequent work by others has led us to re-evaluate our models, which revealed a methodological error that impacted on the results obtained from the abduction–adduction and long-axis rotation moment arms in our published studies. In this paper we present corrected abduction–adduction and long axis rotation moment arms for all our models, and evaluate the impact of this new data on the conclusions of our previous studies. We find that, in general, our newly corrected data differed only slightly from that previously published, with very few qualitative changes in muscle moments (e.g., muscles originally identified as abductors remained abductors. As a result the majority of our previous conclusions regarding the functional evolution of key muscles in these archosaur groups are upheld.

  9. Customized photorefractive keratectomy to correct high ametropia after penetrating keratoplasty: A pilot study.

    Science.gov (United States)

    De Rosa, Giuseppe; Boccia, Rosa; Santamaria, Carmine; Fabbozzi, Lorenzo; De Rosa, Luigi; Lanza, Michele

    2015-01-01

    To evaluate preliminarily the safety and efficacy of customized photorefractive keratectomy (PRK) to correct ametropia and irregular astigmatism after penetrating keratoplasty (PK). This pilot study included five eyes of five patients with a mean spherical equivalent of -5.1±1.46D (range from -2.75 to -6.50D). In all cases, ametropia and irregular astigmatism was corrected with topography-guided customized PRK. Ocular examinations with topographic analysis were performed preoperatively as well as at 1, 3 and 6 months after surgery. All eyes gained postoperatively at least three Snellen lines of uncorrected visual acuity. Mean refractive spherical equivalent was 0.62±0.63D (range from -0.25 to -1.75D) at 6 months postoperatively. Our pilot study suggests that customized PRK can be a safe and effective method for treating ametropia and irregular astigmatisms after PK. Future studies with larger samples and longer follow-ups should be performed to confirm these results. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  10. A study of respiration-correlated cone-beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

    Science.gov (United States)

    Santoro, J. P.; McNamara, J.; Yorke, E.; Pham, H.; Rimner, A.; Rosenzweig, K. E.; Mageras, G. S.

    2012-01-01

    Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D image-based correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II–IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction

  11. Measurement of sediment and crustal thickness corrected RDA for 2D profiles at rifted continental margins: Applications to the Iberian, Gulf of Aden and S Angolan margins

    Science.gov (United States)

    Cowie, Leanne; Kusznir, Nick

    2014-05-01

    Subsidence analysis of sedimentary basins and rifted continental margins requires a correction for the anomalous uplift or subsidence arising from mantle dynamic topography. Whilst different global model predictions of mantle dynamic topography may give a broadly similar pattern at long wavelengths, they differ substantially in the predicted amplitude and at shorter wavelengths. As a consequence the accuracy of predicted mantle dynamic topography is not sufficiently good to provide corrections for subsidence analysis. Measurements of present day anomalous subsidence, which we attribute to mantle dynamic topography, have been made for three rifted continental margins; offshore Iberia, the Gulf of Aden and southern Angola. We determine residual depth anomaly (RDA), corrected for sediment loading and crustal thickness variation for 2D profiles running from unequivocal oceanic crust across the continental ocean boundary onto thinned continental crust. Residual depth anomalies (RDA), corrected for sediment loading using flexural backstripping and decompaction, have been calculated by comparing observed and age predicted oceanic bathymetries at these margins. Age predicted bathymetric anomalies have been calculated using the thermal plate model predictions from Crosby & McKenzie (2009). Non-zero sediment corrected RDAs may result from anomalous oceanic crustal thickness with respect to the global average or from anomalous uplift or subsidence. Gravity anomaly inversion incorporating a lithosphere thermal gravity anomaly correction and sediment thickness from 2D seismic reflection data has been used to determine Moho depth, calibrated using seismic refraction, and oceanic crustal basement thickness. Crustal basement thicknesses derived from gravity inversion together with Airy isostasy have been used to correct for variations of crustal thickness from a standard oceanic thickness of 7km. The 2D profiles of RDA corrected for both sediment loading and non-standard crustal

  12. Prevalence and risk factors for Sick Building Syndrome among Italian correctional officers: A pilot study

    Directory of Open Access Journals (Sweden)

    Francesco Chirico

    2017-03-01

    Full Text Available Introduction: Over the past two decades, numerous studies on indoor air and the Sick Building Syndrome (SBS have been conducted, mostly in office environments. However, there is little knowledge about SBS in police officers. This study was aimed to fill this gap. Methods: A cross-sectional questionnaire survey was conducted in 2016 at the Triveneto Penitentiary Center, Northern Italy. Chi-square was used to test the difference of prevalence between office workers (OWs and correctional officers (COs of personal characteristics, cases of SBS, and general and mucocutaneous symptoms associated with SBS. A binary logistic regression was used to identify among individual, environmental, and psychosocial characteristics, factors associated with correctional officers’ Sick Building Syndrome. Results: Chi-squared analyses revealed that there were statistically significant differences in the estimated prevalence of SBS general symptoms (χ2 (1 = 12.22, P < .05, SBS mucocutaneous symptoms (χ2 (1 = 9.04, P < .05, and cases of SBS (χ2 (1 = 4.39, P <.05 between COs and OWs. COs reported that their health had been affected by the passive smoking (β = 2.34, P < .05 and unpleasant odour (β = 2.51, P < .05 as environmental risk factors; work-family conflict (β = 2.14, P < .05, psychological and physical isolation (β = 2.07, P < .05, and negative public image (β = 2.06, P < .05 as psychosocial risk factors. Finally, atopy (β = 2.02, P < .05 and to be current smoker (β = 2.02, P < .05 were statistically significant behavioral predictors of SBS among correctional officers. Discussion: Our survey showed that symptoms compatible with the sick building syndrome are common in correctional officers and that psychosocial work climate and exposure to passive smoking could have a strong influence on the prevalence of both general and mucocutaneous symptoms associated with SBS. A health policy for passive tobacco smoking within prisons, and for work-related stress

  13. Adding attenuation corrected images in myocardial perfusion imaging reduces the need for a rest study.

    Science.gov (United States)

    Trägårdh, Elin; Valind, Sven; Edenbrandt, Lars

    2013-04-01

    The American Society of Nuclear Cardiology and the Society of Nuclear Medicine conclude that incorporation of attenuation corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve diagnostic accuracy. The aim was to investigate the value of adding AC stress-only images for the decision whether a rest study is necessary or not. 1,261 patients admitted to (99m)Tc MPS were studied. The stress studies were interpreted by two physicians who judged each study as "no rest study necessary" or "rest study necessary", by evaluating NC stress-only and NC + AC stress-only images. When there was disagreement between the two physicians, a third physician evaluated the studies. Thus, agreement between 2 out of 3 physicians was evaluated. The physicians assessed 214 more NC + AC images than NC images as "no rest study necessary" (17% of the study population). The number of no-rest-study-required was significantly higher for NC + AC studies compared to NC studies (859 vs 645 cases (p rest study necessary" (22 NC + AC cases; 8 NC cases), (no statistically significant difference). In 11 of these, the final report stated "suspected/possible ischemia or infarction in a small area". Adding AC stress-only images to NC stress-only images reduce the number of unnecessary rest studies substantially.

  14. Attenuation Correction in SPECT during Image Reconstruction using an Inverse Monte Carlo Method: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Shahla Ahmadi

    2011-09-01

    Full Text Available Introduction: The main goal of SPECT imaging is to determine activity distribution inside the organs of the body. However, due to photon attenuation, it is almost impossible to do a quantitative study. In this paper, we suggest a mathematical relationship between activity distribution and its corresponding projections using a transfer matrix. Monte Carlo simulation was used to find a precise transfer matrix including the effects of photon attenuation.  Material and Methods: List mode output of the SIMIND Monte Carlo simulator was used to find the relationship between activity distribution and pixel values in projections. The MLEM iterative reconstruction method was then used to reconstruct the activity distribution from the projections. Attenuation-free projections were also simulated. Reconstructed images from these projections were used as reference images. Our suggested attenuation correction method was evaluated using three different phantom configurations: uniform activity and uniform attenuation phantom, non-uniform activity and non-uniform attenuation phantom, and NCAT torso phantom. The mean pixel values and fits between profiles were used as quantitative parameters. Results: Images free from attenuation-related artifacts were reconstructed by our suggested method. A significant increase in pixel values was found after attenuation correction. Better fits between profiles of the corrected and reference images were also found for all phantom configurations.  Discussion and Conclusion: Using a Monte Carlo method, it is possible to find the most precise relationship between activity distribution and its projections. Therefore, it is possible to create mathematical projections that include the effects of attenuation. This helps to have a more realistic comparison between mathematical and real projections, which is a necessary step for image reconstruction using MLEM. This results in images with much better quantitative accuracy at a cost of

  15. Study on battery state of charge correct algorithm of electric vehicle

    Institute of Scientific and Technical Information of China (English)

    KAN Ping; QIAN Lijun

    2012-01-01

    State of Charge (SOC) is used to adjust the initialization SOC value so as to make electric vehicle simulation results close to real vehicle performance. This paper firstly analyses the battery SOC correct algorithm, then uses ADVISOR which is a electric vehicle simulation software to simulate a hybrid electric car with three different cases of no SOC correct, linear SOC correct and zero delta SOC correct, as well as makes the compare and analysis for those simulation results. In the end, an overall conclusion to SOC correct algorithm is given.

  16. Moderators of correctional treatment success: an exploratory study of racial differences.

    Science.gov (United States)

    Spiropoulos, Georgia V; Salisbury, Emily J; Van Voorhis, Patricia

    2014-07-01

    An important area in correctional rehabilitation research is to better understand how offenders differentially respond to correctional treatments. Potential treatment moderators forwarded in the literature are gender, race/ethnicity, and personality types. This exploratory study asked whether a group of parolees had demographic and personality moderators of treatment and, if so, were the moderating influences different by race? An experimental design was used to randomly assign a sample of 937 male parolees (n = 658 African American, n = 279 White) to the experimental group that received the cognitive-behavioral treatment program and the control group that did not. Discrete-time event history analysis independently tested the program-moderating effects of demographic and personality characteristics (age, prior employment status, educational attainment, marital status, social class, risk of recidivism, prior violence, IQ, reading level, cognitive maturity, personality type, residential urbanization) on recidivism for African American and White parolees. This study found that the age group and personality type of the parolees interacted with the cognitive-behavioral program in ways that created racially disparate recidivism outcomes.

  17. A study of the pressure correction approach in the colocated grid arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Miettinen, A. [Helsinki University of Technology, Espoo (Finland)

    1997-12-31

    A pressure correction approach in a collocated grid arrangement is studied. The SIMPLE algorithm has been implemented into a two-dimensional Navier-Stokes solver for incompressible flows. A multigrid Poisson solver for the pressure correction equation is utilized. It has been tested alone and as a part of the Navier- Stokes solver. In the former case. the improvement in the convergence rate is remarkable. As a part of a carefully performed Navier-Stokes computation, the multigrid Poisson solver is able to decrease the total CPU time to one third. Cell-face velocity formulas for the continuity equation are also studied. The solution method is tested using several flow cases including a lid-driven cavity and a buoyancy-driven flow. The Rhie and Chow interpolation method and its simplified and limited versions are compared with each other. The traditional Rhie and Chow interpolation method had problems if the flow field contained a high pressure gradient, which can be overcome by using the two latter versions. For buoyancy-driven flows, a body force term in the cell-face velocity formula has been proposed, but the buoyancy-driven test case (Ra -> 10{sup 9}) indicated that this is not necessary. (orig.) 72 refs.

  18. Impact of attenuation correction and gated acquisition in SPECT myocardial perfusion imaging: results of the multicentre SPAG (SPECT Attenuation Correction vs Gated) study

    Energy Technology Data Exchange (ETDEWEB)

    Genovesi, Dario; Giorgetti, Assuero; Gimelli, Alessia; Kusch, Annette; D' Aragona Tagliavia, Irene; Casagranda, Mirta; Marzullo, Paolo [Fondazione CNR-Regione Toscana ' ' G. Monasterio' ' , Nuclear Medicine, Pisa (Italy); Cannizzaro, Giorgio [A.O.V. Cervello, Nuclear Medicine, Palermo (Italy); Giubbini, Raffaele; Bertagna, Francesco [Spedali Civili, Nuclear Medicine, Brescia (Italy); Fagioli, Giorgio; Rossi, Massimiliano; Romeo, Annadina [Ospedale Maggiore, Nuclear Medicine, Bologna (Italy); Bertolaccini, Pietro; Bonini, Rita [Ospedale SS Giacomo e Cristoforo, Nuclear Medicine, Massa (Italy)

    2011-10-15

    In clinical myocardial single photon emission computed tomography (SPECT), attenuation artefacts may cause a loss of specificity in the identification of diseased vessels that can be corrected by means of gated SPECT (GSPECT) acquisition or CT attenuation correction (AC). The purpose of this multicentre study was to assess the impact of GSPECT and AC on the diagnostic performance of myocardial scintigraphy, according to patient's sex, body mass index (BMI) and site of coronary artery disease (CAD). We studied a group of 104 patients who underwent coronary angiography within 1 month before or after the SPECT study. Patients with a BMI > 27 were considered ''overweight''. Attenuation-corrected and standard GSPECT early images were randomly interpreted by three readers blinded to the clinical data. In the whole group, GSPECT and AC showed a diagnostic accuracy of 86.5% (sensitivity 82%, specificity 93%) and 77% (sensitivity 75.4%, specificity 81.4%), respectively (p < 0.05). In women, when anterior ischaemia was matched with CAD, AC failed to show any increase in specificity (AC 63.6% vs GSPECT 63.6%) with evident loss of sensitivity (AC 72.7% vs GSPECT 90.9%). AC significantly improved SPECT specificity in the identification of right CAD in overweight men (AC 100% vs GSPECT 66.7%, p <0.05). AC improved specificity in the evaluation of right CAD in overweight men. In the other evaluable subgroups specificity was not significantly affected while sensitivity was frequently reduced. (orig.)

  19. Comparing bias correction methods in downscaling meteorological variables for a hydrologic impact study in an arid area in China

    Science.gov (United States)

    Fang, G. H.; Yang, J.; Chen, Y. N.; Zammit, C.

    2015-06-01

    Water resources are essential to the ecosystem and social economy in the desert and oasis of the arid Tarim River basin, northwestern China, and expected to be vulnerable to climate change. It has been demonstrated that regional climate models (RCMs) provide more reliable results for a regional impact study of climate change (e.g., on water resources) than general circulation models (GCMs). However, due to their considerable bias it is still necessary to apply bias correction before they are used for water resources research. In this paper, after a sensitivity analysis on input meteorological variables based on the Sobol' method, we compared five precipitation correction methods and three temperature correction methods in downscaling RCM simulations applied over the Kaidu River basin, one of the headwaters of the Tarim River basin. Precipitation correction methods applied include linear scaling (LS), local intensity scaling (LOCI), power transformation (PT), distribution mapping (DM) and quantile mapping (QM), while temperature correction methods are LS, variance scaling (VARI) and DM. The corrected precipitation and temperature were compared to the observed meteorological data, prior to being used as meteorological inputs of a distributed hydrologic model to study their impacts on streamflow. The results show (1) streamflows are sensitive to precipitation, temperature and solar radiation but not to relative humidity and wind speed; (2) raw RCM simulations are heavily biased from observed meteorological data, and its use for streamflow simulations results in large biases from observed streamflow, and all bias correction methods effectively improved these simulations; (3) for precipitation, PT and QM methods performed equally best in correcting the frequency-based indices (e.g., standard deviation, percentile values) while the LOCI method performed best in terms of the time-series-based indices (e.g., Nash-Sutcliffe coefficient, R2); (4) for temperature, all

  20. Clinical Practice Variability in Temperature Correction of Arterial Blood Gas Measurements and Outcomes in Hypothermia-Treated Patients After Cardiac Arrest.

    Science.gov (United States)

    Terman, Samuel Waller; Nicholas, Katherine S; Hume, Benjamin; Silbergleit, Robert

    2015-09-01

    Mechanical ventilation in patients treated with mild therapeutic hypothermia (MTH) for the postcardiac arrest syndrome may be challenging given changes in solubility of arterial blood gases (ABGs) with cooling. Whether ABG measurements should be temperature corrected (TC) remain unknown. We sought to describe practice variability in TC at a single institution and explored the association between TC and neurological outcome. We conducted a retrospective cohort study reviewing electronic health records of all patients treated with MTH after cardiac arrest. We examined whether the percentage of TC ABGs relative to total number of ABGs drawn for each subject during hypothermia was associated with the neurological outcome at hospital discharge and 6-12-month follow-up. The cerebral performance category of 1-2 was defined as a favorable outcome in the logistic regression models. 1223 ABGs were obtained during MTH on 122 subjects over 6 years. TC was never used in 72 subjects (59%; no TC group), made available in 1-74% of ABGs in 17 subjects (14%; intermediate TC group), and made available in ≥75% of ABGs in 33 subjects (27%; mostly TC group). Groups differed in the proportion of subjects with shockable presenting rhythms (47% vs. 47% vs. 76%, p=0.02) and admitting ICU (p=0.005). Favorable 6-month outcomes were more common in the mostly TC than no TC group (48% vs. 25%; OR [95% CI]: 2.9 [1.2-7.1]), but not after adjustment (OR 1.5, 95% CI 0.33-6.9). There was substantial practice variability in the temperature correction strategy. Availability of temperature-corrected ABGs was not associated with improved neurological outcomes after adjusting for covariates.

  1. Study of weak corrections to Drell-Yan, top-quark pair, and dijet production at high energies with MCFM

    Science.gov (United States)

    Campbell, John M.; Wackeroth, Doreen; Zhou, Jia

    2016-11-01

    Electroweak (EW) corrections can be enhanced at high energies due to the soft or collinear radiation of virtual and real W and Z bosons that result in Sudakov-like corrections of the form αWllogn(Q2/MW,Z 2) , where αW=α /(4 π sin2θW) and n ≤2 l -1 . The inclusion of EW corrections in predictions for hadron colliders is, therefore, especially important when searching for signals of possible new physics in distributions probing the kinematic regime Q2≫MV2. Next-to-leading order (NLO) EW corrections should also be taken into account when their size [O (α )] is comparable to that of QCD corrections at next-to-next-to-leading order (NNLO) [O (αs2)]. To this end, we have implemented the NLO weak corrections to the neutral-current Drell-Yan process, top-quark pair production and dijet production in the parton-level Monte Carlo program MCFM. This enables a combined study with the corresponding QCD corrections at NLO and NNLO. We provide both the full NLO weak corrections and their Sudakov approximation since the latter is often used for a fast evaluation of weak effects at high energies and can be extended to higher orders. With both the exact and approximate results at hand, the validity of the Sudakov approximation can be readily quantified.

  2. Retrieval of tropospheric NO2 using the MAX-DOAS method combined with relative intensity measurements for aerosol correction

    Directory of Open Access Journals (Sweden)

    P. F. Levelt

    2010-10-01

    Full Text Available Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS is a technique to measure trace gas amounts in the lower troposphere from ground-based scattered sunlight observations. MAX-DOAS observations are especially suitable for validation of tropospheric trace gas observations from satellite, since they have a representative range of several kilometers, both in the horizontal and in the vertical dimension. A two-step retrieval scheme is presented here, to derive aerosol corrected tropospheric NO2 columns from MAX-DOAS observations. In a first step, boundary layer aerosols, characterized in terms of aerosol optical thickness (AOT, are estimated from relative intensity observations, which are defined as the ratio of the sky radiance at elevation α and the sky radiance in the zenith. Relative intensity measurements have the advantage of a strong dependence on boundary layer AOT and almost no dependence on boundary layer height. In a second step, tropospheric NO2 columns are derived from differential slant columns, based on AOT-dependent air mass factors. This two-step retrieval scheme was applied to cloud free periods in a twelve month data set of observations in De Bilt, The Netherlands. In a comparison with AERONET (Cabauw site a mean difference in AOT (AERONET minus MAX-DOAS of −0.01±0.08 was found, and a correlation of 0.85. Tropospheric-NO2 columns were compared with OMI-satellite tropospheric NO2. For ground-based observations restricted to uncertainties below 10%, no significant difference was found, and a correlation of 0.88.

  3. Comparing bias correction methods in downscaling meteorological variables for hydrologic impact study in an arid area in China

    Science.gov (United States)

    Fang, G. H.; Yang, J.; Chen, Y. N.; Zammit, C.

    2014-11-01

    Water resources are essential to the ecosystem and social economy in the desert and oasis of the arid Tarim River Basin, Northwest China, and expected to be vulnerable to climate change. Regional Climate Models (RCM) have been proved to provide more reliable results for regional impact study of climate change (e.g. on water resources) than GCM models. However, it is still necessary to apply bias correction before they are used for water resources research due to often considerable biases. In this paper, after a sensitivity analysis on input meteorological variables based on Sobol' method, we compared five precipitation correction methods and three temperature correction methods to the output of a RCM model with its application to the Kaidu River Basin, one of the headwaters of the Tarim River Basin. Precipitation correction methods include Linear Scaling (LS), LOCal Intensity scaling (LOCI), Power Transformation (PT), Distribution Mapping (DM) and Quantile Mapping (QM); and temperature correction methods include LS, VARIance scaling (VARI) and DM. These corrected precipitation and temperature were compared to the observed meteorological data, and then their impacts on streamflow were also compared by driving a distributed hydrologic model. The results show: (1) precipitation, temperature, solar radiation are sensitivity to streamflow while relative humidity and wind speed are not, (2) raw RCM simulations are heavily biased from observed meteorological data, which results in biases in the simulated streamflows, and all bias correction methods effectively improved theses simulations, (3) for precipitation, PT and QM methods performed equally best in correcting the frequency-based indices (e.g. SD, percentile values) while LOCI method performed best in terms of the time series based indices (e.g. Nash-Sutcliffe coefficient, R2), (4) for temperature, all bias correction methods performed equally well in correcting raw temperature. (5) For simulated streamflow

  4. Comparing bias correction methods in downscaling meteorological variables for hydrologic impact study in an arid area in China

    Directory of Open Access Journals (Sweden)

    G. H. Fang

    2014-11-01

    Full Text Available Water resources are essential to the ecosystem and social economy in the desert and oasis of the arid Tarim River Basin, Northwest China, and expected to be vulnerable to climate change. Regional Climate Models (RCM have been proved to provide more reliable results for regional impact study of climate change (e.g. on water resources than GCM models. However, it is still necessary to apply bias correction before they are used for water resources research due to often considerable biases. In this paper, after a sensitivity analysis on input meteorological variables based on Sobol' method, we compared five precipitation correction methods and three temperature correction methods to the output of a RCM model with its application to the Kaidu River Basin, one of the headwaters of the Tarim River Basin. Precipitation correction methods include Linear Scaling (LS, LOCal Intensity scaling (LOCI, Power Transformation (PT, Distribution Mapping (DM and Quantile Mapping (QM; and temperature correction methods include LS, VARIance scaling (VARI and DM. These corrected precipitation and temperature were compared to the observed meteorological data, and then their impacts on streamflow were also compared by driving a distributed hydrologic model. The results show: (1 precipitation, temperature, solar radiation are sensitivity to streamflow while relative humidity and wind speed are not, (2 raw RCM simulations are heavily biased from observed meteorological data, which results in biases in the simulated streamflows, and all bias correction methods effectively improved theses simulations, (3 for precipitation, PT and QM methods performed equally best in correcting the frequency-based indices (e.g. SD, percentile values while LOCI method performed best in terms of the time series based indices (e.g. Nash–Sutcliffe coefficient, R2, (4 for temperature, all bias correction methods performed equally well in correcting raw temperature. (5 For simulated streamflow

  5. The Assessment of Atmospheric Correction Processors for MERIS Based on In-Situ Measurements-Updates in OC-CCI Round Robin

    Science.gov (United States)

    Muller, Dagmar; Krasemann, Hajo; Zuhilke, Marco; Doerffer, Roland; Brockmann, Carsten; Steinmetz, Francois; Valente, Andre; Brotas, Vanda; Grant, kMicheal G.; Sathyendranath, Shubha; Melin, Frederic; Franz, Bryan A.; Mazeran, Constant; Regner, Peter

    2016-08-01

    The Ocean Colour Climate Change Initiative (OC- CCI) provides a long-term time series of ocean colour data and investigates the detectable climate impact. A reliable and stable atmospheric correction (AC) procedure is the basis for ocean colour products of the necessary high quality.The selection of atmospheric correction processors is repeated regularly based on a round robin exercise, at the latest when a revised production and release of the OC-CCI merged product is scheduled. Most of the AC processors are under constant development and changes are implemented to improve the quality of satellite-derived retrievals of remote sensing reflectances. The changes between versions of the inter-comparison are not restricted to the implementation of AC processors. There are activities to improve the quality flagging for some processors, and the system vicarious calibration for AC algorithms in their sensor specific behaviour are widely studied. Each inter-comparison starts with an updated in-situ database, as more spectra are included in order to broaden the temporal and spatial range of satellite match-ups. While the OC-CCI's focus has laid on case-1 waters in the past, it has expanded to the retrieval of case-2 products now. In light of this goal, new bidirectional correction procedures (normalisation) for the remote sensing spectra have been introduced. As in-situ measurements are not always available at the satellite sensor specific central wave- lengths, a band-shift algorithm has to be applied to the dataset.In order to guarantee an objective selection from a set of four atmospheric correction processors, the common validation strategy of comparisons between in-situ and satellite-derived water leaving reflectance spectra, is aided by a ranking system. In principal, the statistical parameters are transformed into relative scores, which evaluate the relationship of quality dependent on the algorithms under study. The sensitivity of these scores to the selected

  6. The output factor correction as function of the photon beam field size - direct measurement and calculation from the lateral dose response functions of gas-filled and solid detectors.

    Science.gov (United States)

    Poppinga, Daniela; Delfs, Björn; Meyners, Jutta; Harder, Dietrich; Poppe, Björn; Looe, Hui Khee

    2017-08-28

    The first aim of this study has been to extend the systematic experimental study of the field size dependence of the output factor correction for three micro-ionization chambers (PTW 31014, PTW 31022 and IBA Razor chamber), two silicon diodes (PTW 60017 and IBA Razor Diode) and the synthetic diamond detector microDiamond (PTW 60019) in a 6 MV photon beam down to an effective field side length of 2.6mm, and to summarize the present knowledge of this factor by treating it as a function of the dosimetric field size. In order to vary the dosimetric field size over this large range, output factors measurements were performed at source-to-surface distances of 60cm and 90cm. Since the output factors obtained with the organic scintillation detector Exradin W1 (Standard Imaging, Middleton, USA) at all field sizes closely agreed with those measured by EBT3 radiochromic films (ISP Corp, Wayne, USA), the scintillation detector served as the reference detector. The measured output correction factors reflect the influences of the volume averaging and density effects upon the uncorrected output factor values. In case of the microDiamond detector these opposing influences result in output factor correction values less than 1 for moderately small field sizes and larger than 1 for very small field sizes. Our results agree with most of the published experimental as well as Monte-Carlo simulated data within detector-specific limits of uncertainty. The dosimetric field side length has been identified as a reliable determinant of the output factor correction, and typical functional curve shapes of the field-size dependent output factor correction vs. dosimetric field side length have been associated with gas-filled, silicon diode and synthetic diamond detectors. The second aim of this study has been a novel, semi-empirical approach to calculate the field-size dependent output correction factors of small photon detectors by convolving film measured true dose profile data with measured

  7. Correction: Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents

    Science.gov (United States)

    Hachani, Roxanne; Lowdell, Mark; Birchall, Martin; Hervault, Aziliz; Mertz, Damien; Begin-Colin, Sylvie; Thanh, Nguy&Ecirtil; N. Thi&Cmb. B. Dot; Kim

    2016-02-01

    Correction for `Polyol synthesis, functionalisation, and biocompatibility studies of superparamagnetic iron oxide nanoparticles as potential MRI contrast agents' by Roxanne Hachani et al., Nanoscale, 2015, DOI: 10.1039/c5nr03867g.

  8. Correction: Iron-doping-enhanced photoelectrochemical water splitting performance of nanostructured WO3: a combined experimental and theoretical study.

    Science.gov (United States)

    Zhang, Teng; Zhu, Zonglong; Chen, Haining; Bai, Yang; Xiao, Shuang; Zheng, Xiaoli; Xue, Qingzhong; Yang, Shihe

    2015-09-07

    Correction for 'Iron-doping-enhanced photoelectrochemical water splitting performance of nanostructured WO3: a combined experimental and theoretical study' by Teng Zhang et al., Nanoscale, 2015, 7, 2933-2940.

  9. Theoretical study of the adsorption of aromatic units on carbon allotropes including explicit (empirical) DFT dispersion corrections and implicitly dispersion-corrected functionals: the pyridine case.

    Science.gov (United States)

    Ramos-Berdullas, Nicolás; Pérez-Juste, Ignacio; Van Alsenoy, Christian; Mandado, Marcos

    2015-01-01

    The suitability of implicitly dispersion-corrected functionals, namely the M06-2X, for the determination of interaction energies and electron polarization densities in adsorption studies of aromatic molecules on carbon allotropes surfaces is analysed by comparing the results with those obtained using explicit dispersion through Grimme's empirical corrections. Several models of increasing size for the graphene sheet together with one-dimensional curved carbon structures, (5,5), (6,6) and (7,7) armchair single-walled nanotubes, and two-dimensional curved carbon structures, C60 fullerene, have been considered as substrates in this work, whereas pyridine has been chosen as an example for the adsorbed aromatic molecule. Comparison with recent experimental estimations of the adsorption energy and calculations using periodic boundary conditions on a supercell of 72 carbon atoms indicates that a finite model containing ninety six carbon atoms (C96) approaches quite well the adsorption on a graphene sheet. Analysis of the interaction energy components reveals that the M06-2X functional accounts for most of the dispersion energy implicitly, followed far by wB97X and B3LYP, whereas B97 and BLYP do not differ too much from HF. It has been found that M06-2X corrects only the energy component associated to dispersion and leaves the rest, electrostatic, Pauli and induction "unaltered" with respect to the other DFT functionals investigated. Moreover, only the M06-2X functional reflects the effect of dispersion on the electron polarization density, whereas for the remaining functionals the polarization density does not differ too much from the HF density. This makes the former functional more suitable a priori for the calculation of electron density related properties in these adsorption complexes.

  10. Comparison of the FFT/matrix inversion and system matrix techniques for higher-order probe correction in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Nielsen, Jeppe Majlund; Breinbjerg, Olav

    2011-01-01

    Two higher-order probe-correction techniques for spherical near-field antenna measurements are compared in details for the accuracy they provide and their computational cost. The investigated techniques are the FFT/matrix inversion and the system matrix inversion. Each of these techniques allows...... and a higher-order probe....... correction of general high-order probes, including non-symmetric dual-polarized antennas with independent ports. The investigation was carried out by processing with each technique the same measurement data for a challenging case with an antenna under test significantly offset from the center of rotation...

  11. Comparing range data across the slow-time dimension to correct motion measurement errors beyond the range resolution of a synthetic aperture radar

    Science.gov (United States)

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2010-08-17

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  12. Reproducibility of Intra- and Inter-scanner Measurements of Liver Fat Using Complex Confounder-corrected Chemical Shift Encoded MRI at 3.0 Tesla

    Science.gov (United States)

    Wu, Bing; Han, Wei; Li, Zhenhong; Zhao, Yonghua; Ge, Mingmei; Guo, Xueqing; Wu, Xinhuai

    2016-01-01

    The purpose of this study was to prospectively evaluate the reproducibility of the proton density fat-fraction (PDFF) of the liver using the IDEAL algorithm, a quantitative confounder-corrected chemical-shift-encoded MRI method. Data were obtained from 15 volunteers on four different days. The first and the third examinations were conducted on scanner one with one-week intervals, while the second and the fourth tests were performed on scanner two with same time interval. For each test, two MR scans were performed, one before and one after a meal. Regions-of-interest measurements were manually calculated to estimate the PDFF in the right and left lobes on the PDFF images. Reproducibility was measured using the intra-class correlation coefficient (ICC). The ICCs of the PDFF in the right and left lobes were 0.935 and 0.878, respectively. The intra-scanner ICCs of the right lobe before and after a meal or at a one-week interval were 0.924 and 0.953, respectively. The inter-scanner ICCs of PDFF the next day and at a one-week interval were 0.920 and 0.864, respectively. The PDFF of liver derived from IDEAL demonstrated high intra- and inter-scanner measurement reproducibility. The PDFF of the right lobe before a meal was more reproducible than after-meal measurements. PMID:26763303

  13. Correction of tuberous breast deformity: A retrospective study comparing lipofilling versus breast implant augmentation.

    Science.gov (United States)

    Brault, Nicolas; Stivala, Alessio; Guillier, David; Moris, Vivien; Revol, Marc; François, Caroline; Cristofari, Sarra

    2017-03-01

    Breast implants and, more recently, autologous fat grafting are the two most common treatments used to correct tuberous breast deformity (TBD). The post-surgical quality of life between the two techniques is not well demonstrated. This study aimed to compare satisfaction and health-related quality of life in patients affected by TBD between these two techniques. All TBD patients operated between January 2008 and May 2015 were retrospectively identified, and only those treated with implants or lipofilling were included. Satisfaction was evaluated at least 6 months after surgery with the postoperative Breast-Q(®) augmentation module. From January 2008 to May 2015, 62 patients were recruited in our study, and 37 patients were evaluated using a Breast-Q questionnaire after at least 6 months of follow-up. Breast implant-augmented patients were significantly more satisfied concerning the "satisfaction with breasts" module (p = 0.002) and the "satisfaction with outcome" module (p = 0.00008). A question-by-question analysis revealed several interesting and significant differences, showing higher scores in most of the questions in the breast implant group. Patients in the lipofilling group, interestingly, had a mean of 1.6 interventions compared to the mean 1.36 interventions in the implant group (p = 0.23). This reflects the need to perform more surgical sessions in the lipofilling group to achieve a satisfactory result. Our study demonstrated that tuberous breast correction with implants can achieve better satisfaction along with good outcomes than lipofilling usually does.

  14. Correction of diagnostic x-ray spectra measured with CdTe and CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M. [Osaka Univ., Suita (Japan). Medical School; Kanamori, H.; Toragaito, T.; Taniguchi, A.

    1996-07-01

    We modified the formula of stripping procedure presented by E. Di. Castor et al. We added the Compton scattering and separated K{sub {alpha}} radiation of Cd and Te (23 and 27keV, respectively). Using the new stripping procedure diagnostic x-ray spectra (object 4mm-Al) of tube voltage 50kV to 100kV for CdTe and CdZnTe detectors are corrected with comparison of those spectra for the Ge detector. The corrected spectra for CdTe and CdZnTe detectors coincide with those for Ge detector at lower tube voltage than 70kV. But the corrected spectra at higher tube voltage than 70kV do not coincide with those for Ge detector. The reason is incomplete correction for full energy peak efficiencies of real CdTe and CdZnTe detectors. (J.P.N.)

  15. Ocular correction effects on EMG activity of stomatognathic muscles in children with functional mandibular lateral- deviation: a case control study.

    Science.gov (United States)

    Monaco, A; Cattaneo, R; Spadaro, A; D'Andrea, P; Marzo, G; Gatto, R

    2006-06-01

    This study was conducted in order to determine the ocular correction effects on electromyography activity of anterior temporal, masseter, sternocleidomastoid and anterior digastric muscles in children with functional mandibular lateral-deviation. This study was performed on 32 subjects, aged between 8 and 12 years with functional lateral deviation of mandible and oculo-extrinsic muscular tone disorders. After complete ophthalmologic evaluation and ocular correction prescription, the children were randomly divided into two groups: study and control. In the study group (16 subjects) EMG activity at rest was recorded in the following conditions: with eyes closed; with eyes open; with ocular correction modified through electromyographic control. In the control group (16 subjects) EMG activity at rest was recorded in the following conditions: with eyes closed; with eyes open; with conventional ocular correction. Data were acquired in 15-seconds trial using a SEMG K7, while the subjects maintained rest dental position. Both groups presented a significative correlation between value of lateral-deviation and the degree of ocular-extrinsic muscular tone disorders (r=0.69). In addition, a significant statistical increase of EMG activity at rest with eyes open in both groups was observed in the anterior temporal left and right. A significant decrease of EMG activity with open eyes was observed only with ocular correction upon electromyographic control (study group). The findings, expressed as Symmetry Index, showed a significant increase of muscles imbalance right/left with conventional methods of ocular correction (p corrective lenses, could have an important consequence in clinical diagnostic and therapeutic behaviour because anterior temporal muscles are important in postural position of the mandible. Instead EMG corrective lenses could improve tonus and balance of stomatognathic muscles and, therefore, support the functionality of orthodontic treatment. Moreover, the data

  16. Sulfate and sulfide sulfur isotopes (δ34S and δ33S) measured by solution and laser ablation MC-ICP-MS: An enhanced approach using external correction

    Science.gov (United States)

    Pribil, Michael; Ridley, William I.; Emsbo, Poul

    2015-01-01

    Isotope ratio measurements using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) commonly use standard-sample bracketing with a single isotope standard for mass bias correction for elements with narrow-range isotope systems measured by MC-ICP-MS, e.g. Cu, Fe, Zn, and Hg. However, sulfur (S) isotopic composition (δ34S) in nature can range from at least − 40 to + 40‰, potentially exceeding the ability of standard-sample bracketing using a single sulfur isotope standard to accurately correct for mass bias. Isotopic fractionation via solution and laser ablation introduction was determined during sulfate sulfur (Ssulfate) isotope measurements. An external isotope calibration curve was constructed using in-house and National Institute of Standards and Technology (NIST) Ssulfate isotope reference materials (RM) in an attempt to correct for the difference. The ability of external isotope correction for Ssulfate isotope measurements was evaluated by analyzing NIST and United States Geological Survey (USGS) Ssulfate isotope reference materials as unknowns. Differences in δ34Ssulfate between standard-sample bracketing and standard-sample bracketing with external isotope correction for sulfate samples ranged from 0.72‰ to 2.35‰ over a δ34S range of 1.40‰ to 21.17‰. No isotopic differences were observed when analyzing Ssulfide reference materials over a δ34Ssulfide range of − 32.1‰ to 17.3‰ and a δ33S range of − 16.5‰ to 8.9‰ via laser ablation (LA)-MC-ICP-MS. Here, we identify a possible plasma induced fractionation for Ssulfate and describe a new method using external isotope calibration corrections using solution and LA-MC-ICP-MS.

  17. GED Success: Case Study of an English Language Learner in Correctional Education

    Science.gov (United States)

    Gardner, Susanne

    2017-01-01

    Understanding the elements of educational success for adult English language learners (ELLs) is an important priority for correctional educators, especially today with an increased population of non-English speaking students in correctional schools throughout the country. There is a dearth of information, however, about incarcerated adult ELLs and…

  18. Comparison of ordered subsets expectation maximization and Chang's attenuation correction method in quantitative cardiac SPET: a phantom study.

    Science.gov (United States)

    Dey, D; Slomka, P J; Hahn, L J; Kloiber, R

    1998-12-01

    Photon attenuation is one of the primary causes of artifacts in cardiac single photon emission tomography (SPET). Several attenuation correction algorithms have been proposed. The aim of this study was to compare the effect of using the ordered subsets expectation maximization (OSEM) reconstruction algorithm and Chang's non-uniform attenuation correction method on quantitative cardiac SPET. We performed SPET scans of an anthropomorphic phantom simulating normal and abnormal myocardial studies. Attenuation maps of the phantom were obtained from computed tomographic images. The SPET projection data were corrected for attenuation using OSEM reconstruction, as well as Chang's method. For each defect scan and attenuation correction method, we calculated three quantitative parameters: average radial maximum (ARM) ratio of the defect-to-normal area, maximum defect contrast (MDC) and defect volume, using automated three-dimensional quantitation. The differences between the two methods were less than 4% for defect-to-normal ARM ratio, 19% for MDC and 13% for defect volume. These differences are within the range of estimated statistical variation of SPET. The calculation times of the two methods were comparable. For all SPET studies, OSEM attenuation correction gave a more correct activity distribution, with respect to both the homogeneity of the radiotracer and the shape of the cardiac insert. The difference in uniformity between OSEM and Chang's method was quantified by segmental analysis and found to be less than 8% for the normal study. In conclusion, OSEM and Chang's attenuation correction are quantitatively equivalent, with comparable calculation times. OSEM reconstruction gives a more correct activity distribution and is therefore preferred.

  19. Skeletal Class II correction and neuromuscular adaptation with twin-block: A cephalometric and electromyography study in adults

    OpenAIRE

    Sandeep Kumar; Tulika Tripathi; Maninder Singh Sidhu; Puneet Yadav; Ashish Dabas

    2016-01-01

    Introduction: It is believed that significant changes in electromyography (EMG) activity are observed at the end of the treatment, which are concomitant with a clinical improvement seen in sagittal jaw relationship during skeletal Class II correction by functional appliances. It is thought that similar interaction occurs between bone shape and muscle activity in the maxillofacial complex this study aims at evaluating the effects of twin-block on correction of skeletal Class II by lateral ceph...

  20. Correction of interstitial water changes in calibration methods applied to XRF core-scanning major elements in long sediment cores: Case study from the South China Sea

    Science.gov (United States)

    Chen, Quan; Kissel, Catherine; Govin, Aline; Liu, Zhifei; Xie, Xin

    2016-05-01

    Fast and nondestructive X-ray fluorescence (XRF) core scanning provides high-resolution element data that are widely used in paleoclimate studies. However, various matrix and specimen effects prevent the use of semiquantitative raw XRF core-scanning intensities for robust paleoenvironmental interpretations. We present here a case study of a 50.8 m-long piston Core MD12-3432 retrieved from the northern South China Sea. The absorption effect of interstitial water is identified as the major source of deviations between XRF core-scanning intensities and measured element concentrations. The existing two calibration methods, i.e., normalized median-scaled calibration (NMS) and multivariate log-ratio calibration (MLC), are tested with this sequence after the application of water absorption correction. The results indicate that an improvement is still required to appropriately correct the influence of downcore changes in interstitial water content in the long sediment core. Consequently, we implement a new polynomial water content correction in NMS and MLC methods, referred as NPS and P_MLC calibrations. Results calibrated by these two improved methods indicate that the influence of downcore water content changes is now appropriately corrected. We therefore recommend either of the two methods to be applied for robust paleoenvironmental interpretations of major elements measured by XRF-scanning in long sediment sequences with significant downcore interstitial water content changes.

  1. Experimental study of multi-photon contamination on the measurement of fluorescent decay time

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the measurement of fluorescent lifetime based on time correlation-single photon counting technique by means of TAC, due to the contamination of multi-photons a deviation of fluorescent lifetime measured from the expected value is experimentally studied. A correction function instead of a simple exponential function is used to fit the experiment data. The validation of the correction function is checked using the experimental data of several test samples: YAP, NaI(T1) and LSO. The results show that the correction function well fits the data and the reasonable fluorescent lifetimes are obtained.

  2. Correction of population stratification in large multi-ethnic association studies.

    Directory of Open Access Journals (Sweden)

    David Serre

    Full Text Available BACKGROUND: The vast majority of genetic risk factors for complex diseases have, taken individually, a small effect on the end phenotype. Population-based association studies therefore need very large sample sizes to detect significant differences between affected and non-affected individuals. Including thousands of affected individuals in a study requires recruitment in numerous centers, possibly from different geographic regions. Unfortunately such a recruitment strategy is likely to complicate the study design and to generate concerns regarding population stratification. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed 9,751 individuals representing three main ethnic groups - Europeans, Arabs and South Asians - that had been enrolled from 154 centers involving 52 countries for a global case/control study of acute myocardial infarction. All individuals were genotyped at 103 candidate genes using 1,536 SNPs selected with a tagging strategy that captures most of the genetic diversity in different populations. We show that relying solely on self-reported ethnicity is not sufficient to exclude population stratification and we present additional methods to identify and correct for stratification. CONCLUSIONS/SIGNIFICANCE: Our results highlight the importance of carefully addressing population stratification and of carefully "cleaning" the sample prior to analyses to obtain stronger signals of association and to avoid spurious results.

  3. Spectral interference corrections for the measurement of {sup 238}U in materials rich in thorium by a high resolution {gamma}-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yuecel, H. [Turkish Atomic Energy Authority (TAEA), Besevler Yerleskesi, Tandogan, 06100 Ankara (Turkey)], E-mail: alfa.haluky@gmail.com; Solmaz, A.N.; Koese, E.; Bor, D. [Institute of Nuclear Sciences of Ankara University (AU-INS), Tandogan, 06100 Ankara (Turkey)

    2009-11-15

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of {sup 234}Th and 1001.0 keV of {sup 234m}Pa, which are often used in the measurement of {sup 238}U activity by the {gamma}-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the {gamma}-rays overlapping the analytical peaks, due to the contribution of {sup 232}Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference {gamma}-rays of {sup 232}Th and {sup 235}U to the mixed peak at 63.3 keV of {sup 234}Th ({sup 238}U) leads to the remarkably large systematic influence of 0.8-122% in the measured {sup 238}U activity, but in case of ignoring the contribution of {sup 232}Th via the interference {gamma}-ray at 1000.7 keV of {sup 228}Ac to the mixed peak at 1001 keV of {sup 234m}Pa ({sup 238}U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate {sup 238}U activity results. Additionally, if one ignores the contribution of {sup 232}Th to both {sup 238}U and {sup 40}K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be {approx}6% and {approx}1% via the analytical peaks at 63.3 and 1001 keV for measurement of the {sup 238}U activity, respectively.

  4. The 3D Pelvic Inclination Correction System (PICS): A universally applicable coordinate system for isovolumetric imaging measurements, tested in women with pelvic organ prolapse (POP).

    Science.gov (United States)

    Reiner, Caecilia S; Williamson, Tom; Winklehner, Thomas; Lisse, Sean; Fink, Daniel; DeLancey, John O L; Betschart, Cornelia

    2017-07-01

    In pelvic organ prolapse (POP), the organs are pushed downward along the lines of gravity, so measurements along this longitudinal body axis are desirable. We propose a universally applicable 3D coordinate system that corrects for changes in pelvic inclination and that allows the localization of any point in the pelvis at rest or under dynamic conditions on magnetic resonance images (MRI) of pelvic floor disorders in a scanner- and software independent manner. The proposed 3D coordinate system called 3D Pelvic Inclination Correction System (PICS) is constructed utilizing four bony landmark points, with the origin set at the inferior pubic point, and three additional points at the sacrum (sacrococcygeal joint) and both ischial spines, which are clearly visible on MRI images. The feasibility and applicability of the moving frame was evaluated using MRI datasets from five women with pelvic organ prolapse, three undergoing static MRI and two undergoing dynamic MRI of the pelvic floor in a supine position. The construction of the coordinate system was performed utilizing the selected landmarks, with an initial implementation completed in MATLAB. In all cases the selected landmarks were clearly visible, with the construction of the 3D PICS and measurement of pelvic organ positions performed without difficulty. The resulting distance from the organ position to the horizontal PICS plane was compared to a traditional measure based on standard measurements in 2D slices. The two approaches demonstrated good agreement in each of the cases. The developed approach makes quantitative assessment of pelvic organ position in a physiologically relevant 3D coordinate system possible independent of pelvic movement relative to the scanner. It allows the accurate study of the physiologic range of organ location along the body axis ("up or down") as well as defects of the pelvic sidewall or birth-related pelvic floor injuries outside the midsagittal plane, not possible before in a 2D

  5. FTIR spectroscopic imaging and mapping with correcting lenses for studies of biological cells and tissues.

    Science.gov (United States)

    Kimber, James A; Foreman, Liberty; Turner, Benjamin; Rich, Peter; Kazarian, Sergei G

    2016-06-23

    Histopathology of tissue samples is used to determine the progression of cancer usually by staining and visual analysis. It is recognised that disease progression from healthy tissue to cancerous is accompanied by spectral signature changes in the mid-infrared range. In this work, FTIR spectroscopic imaging in transmission mode using a focal plane array (96 × 96 pixels) has been applied to the characterisation of Barrett's oesophageal adenocarcinoma. To correct optical aberrations, infrared transparent lenses were used of the same material (CaF2) as the slide on which biopsies were fixed. The lenses acted as an immersion objective, reducing scattering and improving spatial resolution. A novel mapping approach using a sliding lens is presented where spectral images obtained with added lenses are stitched together such that the dataset contained a representative section of the oesophageal tissue. Images were also acquired in transmission mode using high-magnification optics for enhanced spatial resolution, as well as with a germanium micro-ATR objective. The reduction of scattering was assessed using k-means clustering. The same tissue section map, which contained a region of high grade dysplasia, was analysed using hierarchical clustering analysis. A reduction of the trough at 1077 cm(-1) in the second derivative spectra was identified as an indicator of high grade dysplasia. In addition, the spatial resolution obtained with the lens using high-magnification optics was assessed by measurements of a sharp interface of polymer laminate, which was also compared with that achieved with micro ATR-FTIR imaging. In transmission mode using the lens, it was determined to be 8.5 μm and using micro-ATR imaging, the resolution was 3 μm for the band at a wavelength of ca. 3 μm. The spatial resolution was also assessed with and without the added lens, in normal and high-magnification modes using a USAF target. Spectroscopic images of cells in transmission mode using two

  6. Importance of the Hubbard correction on the thermal conductivity calculation of strongly correlated materials: a case study of ZnO

    Science.gov (United States)

    Consiglio, Anthony; Tian, Zhiting

    2016-11-01

    The wide bandgap semiconductor, ZnO, has gained interest recently as a promising option for use in power electronics such as thermoelectric and piezoelectric generators, as well as optoelectronic devices. Though much work has been done to improve its electronic properties, relatively little is known of its thermal transport properties with large variations in measured thermal conductivity. In this study, we examine the effects of a Hubbard corrected energy functional on the lattice thermal conductivity of wurtzite ZnO calculated using density functional theory and an iterative solution to the Boltzmann transport equation. Showing good agreement with existing experimental measurements, and with a detailed analysis of the mode-dependence and phonon properties, the results from this study highlight the importance of the Hubbard correction in calculations of thermal transport properties of materials with strongly correlated electron systems.

  7. Electroweak Corrections to p p →μ+μ-e+e-+X at the LHC: A Higgs Boson Background Study

    Science.gov (United States)

    Biedermann, B.; Denner, A.; Dittmaier, S.; Hofer, L.; Jäger, B.

    2016-04-01

    The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state μ+μ-e+e-, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W - or Z -boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z -pair production and the Higgs signal.

  8. Electroweak Corrections to pp→μ^{+}μ^{-}e^{+}e^{-}+X at the LHC: A Higgs Boson Background Study.

    Science.gov (United States)

    Biedermann, B; Denner, A; Dittmaier, S; Hofer, L; Jäger, B

    2016-04-22

    The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state μ^{+}μ^{-}e^{+}e^{-}, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W- or Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z-pair production and the Higgs signal.

  9. Electroweak corrections to $pp \\to \\mu^+\\mu^-e^+e^- + X$ at the LHC -- a Higgs background study

    CERN Document Server

    Biedermann, B; Dittmaier, S; Hofer, L; Jäger, B

    2016-01-01

    The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state $\\mu^+\\mu^-e^+e^-$, we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal.

  10. Is Bonferroni correction more sensitive than Random Field Theory for most fMRI studies?

    CERN Document Server

    Tierney, Tim M; Carmichael, David W

    2016-01-01

    Random Field Theory has been used in the fMRI literature to address the multiple comparisons problem. The method provides an analytical solution for the computation of precise p-values when its assumptions are met. When its assumptions are not met the thresholds generated by Random Field Theory can be more conservative than Bonferroni corrections, which are arguably too stringent for use in fMRI. As this has been well documented theoretically it is surprising that a majority of current studies (~80%) would not meet the assumptions of Random Field Theory and therefore would have reduced sensitivity. Specifically most data is not smooth enough to meet the good lattice assumption. Current studies smooth data on average by twice the voxel size which is rarely sufficient to meet the good lattice assumption. The amount of smoothing required for Random Field Theory to produce accurate p-values increases with image resolution and decreases with degrees of freedom. There is no rule of thumb that is valid for all study...

  11. Measurements of beta ray spectra inside nuclear generating stations using a silicon detector coincidence telescope: skin dose beta correction factors for TL elements

    Energy Technology Data Exchange (ETDEWEB)

    Horowitz, Y.S.; Weizmann, Y. [Ben Gurion University of the Negev (Israel); Hirning, C.R. [Ontario Hydro, Whitby (Canada). Health Physics

    1996-10-01

    The measurement of beta ray spectra at various work locations inside nuclear generating stations operated by Ontario Hydro is described. The measurements were carried out using an advanced coincidence telescope spectrometer using silicon detectors only. The spectrometer is capable of measuring electron energies over the range 70-2500 keV with close to 100% efficiency. Over 40 beta ray spectra were measured at various work locations in three nuclear generating stations. Photon rejection is carried out by requiring a coincidence between either two or three detectors. Monte Carlo calculations were then used to estimate beta correction factors for the LiF:Mg,Ti elements used in the Ontario Hydro thermoluminescence dosemeters. Averaging over all the measured beta correction factors for the `skin chip (100 mg. cm{sup -2}) results in a value of 2.73 {+-} 0.77 and for the extremity dosemeter (240 mg.cm{sup -2}) an average value of 4.42 {+-} 1.17 is obtained. These values are 57% and 120% greater, respectively, than the current values used by Ontario Hydro. In addition, beta correction factors for nine representative spectra were calculated for 40 mg.cm{sup -2} and 20 mg.cm{sup -2} chips, and the results demonstrate the benefits of decreased dosemeter thickness. The average value of the beta correction factor, as well as the spread in the beta correction factor, decreases dramatically from 4.80 {+-} 2.1 (240 mg.cm{sup -2}) to 1.29 {+-} 0.1 (20mg.cm{sup -2}). (Author).

  12. Dual-channel red/blue fluorescence dosimetry with broadband reflectance spectroscopic correction measures protoporphyrin IX production during photodynamic therapy of actinic keratosis

    Science.gov (United States)

    Kanick, Stephen Chad; Davis, Scott C.; Zhao, Yan; Hasan, Tayyaba; Maytin, Edward V.; Pogue, Brian W.; Chapman, M. Shane

    2014-01-01

    Abstract. Dosimetry for aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) photodynamic therapy of actinic keratosis was examined with an optimized fluorescence dosimeter to measure PpIX during treatment. While insufficient PpIX generation may be an indicator of incomplete response, there exists no standardized method to quantitate PpIX production at depths in the skin during clinical treatments. In this study, a spectrometer-based point probe dosimeter system was used to sample PpIX fluorescence from superficial (blue wavelength excitation) and deeper (red wavelength excitation) tissue layers. Broadband white light spectroscopy (WLS) was used to monitor aspects of vascular physiology and inform a correction of fluorescence for the background optical properties. Measurements in tissue phantoms showed accurate recovery of blood volume fraction and reduced scattering coefficient from WLS, and a linear response of PpIX fluorescence versus concentration down to 1.95 and 250 nM for blue and red excitations, respectively. A pilot clinical study of 19 patients receiving 1-h ALA incubation before treatment showed high intrinsic variance in PpIX fluorescence with a standard deviation/mean ratio of >0.9. PpIX fluorescence was significantly higher in patients reporting higher pain levels on a visual analog scale. These pilot data suggest that patient-specific PpIX quantitation may predict outcome response. PMID:24996661

  13. An Evaluation of the Nonlinearity Correction Applied to Atmospheric Emitted Radiance Interferometer (AERI) Data Collected by the Atmospheric Radiation Measurement Program

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. D. [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.; Knuteson, R. O. [Univ. of Wisconsin, Madison, WI (United States); Revercomb, H. E. [Univ. of Wisconsin, Madison, WI (United States); Dedecker, R. G. [Univ. of Wisconsin, Madison, WI (United States); Feltz, W. F. [Univ. of Wisconsin, Madison, WI (United States)

    2004-09-01

    Mercury Cadmium Telluride (MCT) detectors provide excellent sensitivity to infrared radiation and are used in passive infrared remote sensors such as the Atmospheric Emitted Radiance Interferometer (AERI). However, MCT detectors have a nonlinear response and thus this nonlinearity must be characterized and corrected to provide accurate infrared radiance observations. This paper discusses the significance of the nonlinearity correction applied to AERI data and its impacts on the parameters retrieved from the AERI spectra. It also evaluates the accuracy of the scheme used to determine the nonlinearity of the MCT detectors used in the Atmospheric Radiation Measurement (ARM) Program’s AERIs.

  14. Direct measurements of blood glucose concentration in the presence of saccharide interferences using slope and bias orthogonal signal correction and Fourier transform near-infrared spectroscopy.

    Science.gov (United States)

    Abookasis, David; Workman, Jerome J

    2011-02-01

    Saccharide interferences such as Dextran, Galactose, etc. have a great potential to interfere with near infrared (NIR) glucose analysis since they have a similar spectroscopic fingerprint and are present physiologically at large relative concentrations. These can lead to grossly inappropriate interpretation of patient glucose levels and resultant treatment in critical care and hospital settings. This study describes a methodology to reduce this effect on glucose analysis using an NIR Fourier transform spectroscopy method combined with a multivariate calibration technique (PLS) using preprocessing by orthogonal signal correction (OSC). A mathematical approach based on the use of a single calibration based bias and slope correction was applied in addition to a standard OSC was investigated. This approach is combined with a factorial interferent calibration design to accommodate for interference effects. We named this approach as a slope and bias OSC (sbOSC). sbOSC differs from OSC in the way it handles the prediction. In sbOSC, statistics on slope and bias obtained from a set of calibration samples are then used as a validation parameter in the prediction set. Healthy human volunteer blood with different glucose (80 to 200 mg/dL) and hematocrit (24 to 48 vol.%) levels containing high expected levels of inteferents have been measured with a transmittance near-infrared Fourier transform spectrometer operates in the broadband spectral range of 1.25-2.5 μm (4000-8000 cm(-1)). The effect of six interferents compounds used in intensive care and operating rooms, namely Dextran, Fructose, Galactose, Maltose, Mannitol, and Xylose, were tested on blood glucose. A maximum interference effect (MIE) parameter was used to rank the significance for the individual interferent type on measurement error relative to the total NIR whole blood glucose measurement error. For comparison, a YSI (Yellow Springs Instrument) laboratory reference glucose analyzer and NIR data were collected at

  15. Use of Diazepam to Correct Hemodynamic Changes in Explosive Mine Injury: Experimental Study

    Directory of Open Access Journals (Sweden)

    V. N. Yelsky

    2007-01-01

    Full Text Available Objective. To study the hemodynamic effect of benzodiazepine tranquilizers in explosive mine injury in an experiment.Materials and methods. The study was performed on non-inbred male rats; hemodynamic parameters were examined at the systemic, organ, and microcirculatory levels.Results. Circulatory adaptive changes occurring at the beginning of a premorbid load further become pathogenic, which in combination with a progressive change in blood-brain barrier resistance results in the severer course of premorbid load-complicated explosive mine injury than that of isolated one. Correction of occurring disorders, by stimulating the stress-limiting GABAergic system with diazepam, is most effective within the first 25 minutes after isolated explosive mine injury and within the first 15 minutes after complicated one. Conclusion. Under the conditions of deep collieries where medical aid was generally late, emergency medical activation of urgent adaptation mechanisms by the techniques specially developed by the authors for these conditions is the most effective way of preventing the complications of explosive mine injury. 

  16. Identification and correction of spectral contamination in 2H/1H and 18O/16O measured in leaf, stem, and soil water.

    Science.gov (United States)

    Schultz, Natalie M; Griffis, Timothy J; Lee, Xuhui; Baker, John M

    2011-11-15

    Plant water extracts typically contain organic materials that may cause spectral interference when using isotope ratio infrared spectroscopy (IRIS), resulting in errors in the measured isotope ratios. Manufacturers of IRIS instruments have developed post-processing software to identify the degree of contamination in water samples, and potentially correct the isotope ratios of water with known contaminants. Here, the correction method proposed by an IRIS manufacturer, Los Gatos Research, Inc., was employed and the results were compared with those obtained from isotope ratio mass spectrometry (IRMS). Deionized water was spiked with methanol and ethanol to create correction curves for δ(18)O and δ(2)H. The contamination effects of different sample types (leaf, stem, soil) and different species from agricultural fields, grasslands, and forests were compared. The average corrections in leaf samples ranged from 0.35 to 15.73‰ for δ(2)H and 0.28 to 9.27‰ for δ(18)O. The average corrections in stem samples ranged from 1.17 to 13.70‰ for δ(2)H and 0.47 to 7.97‰ for δ(18)O. There was no contamination observed in soil water. Cleaning plant samples with activated charcoal had minimal effects on the degree of spectral contamination, reducing the corrections, by on average, 0.44‰ for δ(2)H and 0.25‰ for δ(18)O. The correction method eliminated the discrepancies between IRMS and IRIS for δ(18)O, and greatly reduced the discrepancies for δ(2)H. The mean differences in isotope ratios between IRMS and the corrected IRIS method were 0.18‰ for δ(18)O, and -3.39‰ for δ(2)H. The inability to create an ethanol correction curve for δ(2)H probably caused the larger discrepancies. We conclude that ethanol and methanol are the primary compounds causing interference in IRIS analyzers, and that each individual analyzer will probably require customized correction curves.

  17. Study of statistically correcting model CMAQ-MOS for forecasting regional air quality

    Institute of Scientific and Technical Information of China (English)

    XU Jianming; HE Jinhai; YANG Yuanqin; WANG Jiahe; XU Xiangde; LIU Yu; DING Guoan; CHEN Huailiang; HU Jiangkai; ZHANG Jianchun; WU Hao; LI Weiliang

    2005-01-01

    Based on analysis of the air pollution observational data at 8 observation sites in Beijing including outer suburbs during the period from September 2004 to March 2005, this paper reveals synchronal and in-phase characteristics in the spatial and temporal variation of air pollutants on a city-proper scale at deferent sites; describes seasonal differences of the pollutant emission influence between the heating and non-heating periods, also significantly local differences of the pollutant emission influence between the urban district and outer suburbs, i.e. the spatial and temporal distribution of air pollutant is closely related with that of the pollutant emission intensity. This study shows that due to complexity of the spatial and temporal distribution of pollution emission sources, the new generation Community Multi-scale Air Quality (CMAQ) model developed by the EPA of USA produced forecasts, as other models did, with a systematic error of significantly lower than observations, albeit the model has better capability than previous models had in predicting the spatial distribution and variation tendency of multi-sort pollutants. The reason might be that the CMAQ adopts average amount of pollutant emission inventory, so that the model is difficult to objectively and finely describe the distribution and variation of pollution emission sources intensity on different spatial and temporal scales in the areas, in which the pollution is to be forecast. In order to correct the systematic prediction error resulting from the average pollutant emission inventory in CMAQ, this study proposes a new way of combining dynamics and statistics and establishes a statistically correcting model CMAQ-MOS for forecasts of regional air quality by utilizing the relationship of CMAQ outputs with corresponding observations, and tests the forecast capability. The investigation of experiments presents that CMAQ-MOS reduces the systematic errors of CMAQ because of the uncertainty of pollution

  18. An Empirical Study of End-User Behaviour in Spreadsheet Error Detection & Correction

    CERN Document Server

    Bishop, Brian

    2008-01-01

    Very little is known about the process by which end-user developers detect and correct spreadsheet errors. Any research pertaining to the development of spreadsheet testing methodologies or auditing tools would benefit from information on how end-users perform the debugging process in practice. Thirteen industry-based professionals and thirty-four accounting & finance students took part in a current ongoing experiment designed to record and analyse end-user behaviour in spreadsheet error detection and correction. Professionals significantly outperformed students in correcting certain error types. Time-based cell activity analysis showed that a strong correlation exists between the percentage of cells inspected and the number of errors corrected. The cell activity data was gathered through a purpose written VBA Excel plug-in that records the time and detail of all cell selection and cell change actions of individuals.

  19. Improved Extended Multiplicative Scatter Correction Algorithm Applied in Blood Glucose Noninvasive Measurement with FT-IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Qingbo Li

    2013-01-01

    Full Text Available In order to improve the predictive accuracy of human blood glucose quantitative analysis model with fourier transform infrared (FT-IR spectroscopy, this paper uses a method named improved extended multiplicative scatter correction (Im-EMSC, which can effectively eliminate the scattering effects caused by human body strong scattering. The principal components of the differential spectra are used instead of the pure spectra of the analytes in this algorithm. Calibrate the unwanted physical characteristic through the shape of the curve of principal components, and extract the original glucose concentration information. Im-EMSC can efficiently remove most of the pathlength difference and baseline shift influences. Firstly, Im-EMSC is used as a preprocessing method, and then partial least squares (PLS regression method is adopted to establish a quantitative analysis model. In this paper, the result of Im-EMSC is compared with those popular scattering correction algorithms of multiplicative scatter correction (MSC and extended multiplicative scatter correction (EMSC preprocessing methods. Experimental results show that the prediction accuracy has been greatly improved with Im-EMSC method, which is helpful for human noninvasive glucose concentration detection technology.

  20. Correcting for variable laser-target distances of laser-induced breakdown spectroscopy measurements with ChemCam using emission lines of Martian dust spectra

    Energy Technology Data Exchange (ETDEWEB)

    Melikechi, N.; Mezzacappa, A. [Optical Science Center for Applied Research, Delaware State University, Dover, DE (United States); Cousin, A.; Lanza, N.L. [Los Alamos National Laboratory, Los Alamos, NM (United States); Lasue, J. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Clegg, S.M. [Los Alamos National Laboratory, Los Alamos, NM (United States); Berger, G. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Wiens, R.C. [Los Alamos National Laboratory, Los Alamos, NM (United States); Maurice, S. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Tokar, R.L.; Bender, S. [Planetary Science Institute, Flagstaff, AZ (United States); Forni, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Breves, E.A.; Dyar, M.D. [Dept. of Astronomy, Mount Holyoke College, South Hadley, MA (United States); Frydenvang, J. [The Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Delapp, D. [Los Alamos National Laboratory, Los Alamos, NM (United States); Gasnault, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Newsom, H.; Ollila, A.M. [Earth and Planetary Sciences, University of New Mexico, Alburquerque, NM (United States); Lewin, E. [Institut des Sciences de la Terre, Universite Grenoble l-CNRS, Grenoble (France); and others

    2014-06-01

    As part of the Mars Science Laboratory, the ChemCam instrument acquires remote laser induced breakdown spectra at distances that vary between 1.56 m and 7 m. This variation in distance affects the intensities of the measured LIBS emission lines in non-trivial ways. To determine the behavior of a LIBS emission line with distance, it is necessary to separate the effects of many parameters such as laser energy, laser spot size, target homogeneity, and optical collection efficiency. These parameters may be controlled in a laboratory on Earth but for field applications or in space this is a challenge. In this paper, we show that carefully selected ChemCam LIBS emission lines acquired from the Martian dust can be used to build an internal proxy spectroscopic standard. This in turn, allows for a direct measurement of the effects of the distance of various LIBS emission lines and hence can be used to correct ChemCam LIBS spectra for distance variations. When tested on pre-launch LIBS calibration data acquired under Martian-like conditions and with controlled and well-calibrated targets, this approach yields much improved agreement between targets observed at various distances. This work lays the foundation for future implementation of automated routines to correct ChemCam spectra for differences caused by variable distance. - Highlights: • Selected Martian dust emission lines are used to correct for variable laser-target distances. • The correction model yields improved agreement between targets observed at various distances. • The impact of the model reduces the bias between predicted and actual compositions by as much as 70%. • When implemented, the model will yield spectral corrections for various ChemCam measurements. • This work is a foundation to perform novel stand-off LIBS measurements on Earth and other planets.

  1. Comparison of accuracy of uncorrected and corrected sagittal tomography in detection of mandibular condyle erosions: An exvivo study

    Directory of Open Access Journals (Sweden)

    Asieh Zamani Naser

    2010-01-01

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